JP7424263B2 - Vehicle electric parking brake device - Google Patents

Description

The present disclosure relates to an electric parking brake device for a vehicle.

Patent Document 1 states, "The electric parking brake device is configured to be operable in response to input from the driver, while reducing the load on the battery and waste of power when restarting the engine due to idle stop control." ``A starter 30 connected to a battery 80, an idle stop control unit 12 that automatically stops the engine and automatically restarts the engine by the starter, and a starter that responds to input from the driver. an electric parking brake device 40 including an electric motor 42 connected to the battery and driven by the electric motor in response to the actuation request; Prohibits the idle stop control unit from restarting the engine when the electric motor is in a driving state, and responds to the predetermined operation request when the idle stop control unit is restarting the engine. and an arbitration unit that prohibits driving of the electric motor."

The applicant has developed an electric parking brake device as described in Patent Document 2. In this device, for the purpose of reducing the power consumption of the electric motor when a parking brake instruction is given, the electric parking brake device is driven by an electric motor and moves in the forward direction to apply the parking brake, A linear motion member that releases the parking brake by being moved in a backward direction that is opposite to the forward direction, and a controller that controls the electric motor.The controller releases the parking brake. In doing so, the power supply to the electric motor is stopped when a release threshold time has elapsed from the time when the amount of power supply to the electric motor became constant.

In the device disclosed in Patent Document 1, restarting the engine is prohibited when the electric parking brake device is in operation. On the other hand, if the engine is being restarted, operation of the electric parking brake device is prohibited. That is, the device on one side that is activated first has priority, and the operation of the device on the other side is prohibited. However, depending on the status of the storage battery, etc., other devices such as an engine starter may request to interrupt the operation of the electric parking brake device (i.e., to reduce the power consumption of the electric motor MT). request) may be made.

For example, in the device of Patent Document 2, in the middle of a release operation and the linear motion member (also referred to as an "output member") has been moved in the backward direction to some extent, an operation interruption request is received from outside the device. Assume that the interruption request is terminated after that. Upon completion of the operation interruption request, the output member is returned to the backward direction again. In the movement of the output member, the point in time when the amount of current applied to the electric motor becomes constant is set as a starting point (reference), and the current applied to the electric motor is stopped at a time from this starting point. For this reason, if the drive of the electric motor is stopped during the release operation, the starting point may become unclear and the amount of movement of the output member may become excessive (that is, excessive displacement may occur).

JP2016-203872 Patent application No. 2020-079922

An object of the present invention is to provide an electric parking brake device that can suppress excessive displacement of an output member when an operation interruption request is terminated.

The electric parking brake device according to the present invention drives an electric motor (MT) in a normal rotation direction (Da) to press a friction member (MS) against a rotating member (KT) provided on a wheel of a vehicle to brake the parking brake. , and drives the electric motor (MT) in the reverse direction (Db) to release the parking brake, and includes a controller (ECU) that controls the electric motor (MT).

In the electric parking brake device according to the present invention, when releasing the parking brake, the controller (ECU) determines a contact cancellation state in which the rotating member (KT) and the friction member (MS) are no longer in contact with each other. Execute a release control to stop energizing the electric motor (MT) when a release threshold time (tk) has elapsed from the point in time, and request interruption of the release control while the release control is being executed. If so, the drive of the electric motor (MT) is stopped.

Furthermore, in the electric parking brake device according to the present invention, the controller (ECU) executes the release control at the end point when the request is ended, if the request is made before determining the contact release state. . On the other hand, if the request is made after determining the contact release state, the release control is executed after driving the electric motor (MT) in the normal rotation direction (Da) at the end point.

In the release control, if the drive of the electric motor MT is stopped while the electric motor MT is being driven in reverse, the starting point of the release continuation time Tk becomes unclear. According to the above configuration, if a cancellation interruption request is made after the contact cancellation state is determined, the electric motor MT is driven to rotate in the forward direction at the end of the request. As a result, the friction member MS is brought into contact with the rotating member KT again. Thereafter, the electric motor MT is driven in the reverse direction, and after the contact release state is determined, the drive of the electric motor MT is terminated based on the release duration Tk. The starting point of the release duration Tk is determined and clarified again by the re-contact between the rotating member KT and the friction member MS. Therefore, even if there is an interruption request during release control, excessive displacement of the output member SB can be suppressed.

Further, in the electric parking brake device according to the present invention, the controller (ECU) executes the release control at the end point when the request is ended, if the request is made before determining the contact cancellation state. . On the other hand, if the request is made after determining the contact release state, the electric motor (MT) is driven in the reverse direction (Db) from the end point, and the release threshold time (tk ), the driving of the electric motor (MT) is stopped when a specific threshold time (tn) shorter than 100 ms has elapsed.

If there is a request to interrupt the operation after the contact-resolved state is determined, the output member SB has been displaced to some extent at the time the request ends. According to the above configuration, the electric motor MT is driven in reverse at the end of the request, but since the threshold value (i.e., the specific threshold time tn) related to the continuation time Tk of canceling the reverse drive is set short, the output Excessive displacement of member SB can be suppressed.

FIG. 1 is an overall configuration diagram for explaining an embodiment of an electric parking brake device EP. It is a schematic diagram for explaining the details of electric actuator DN. FIG. 3 is a flowchart for explaining cancellation control processing. FIG. 3 is a time series diagram for explaining the operation of release control. FIG. 3 is a flowchart for explaining a first processing example of cancellation interruption control. FIG. 6 is a time series diagram for explaining the operation of re-cancellation processing. FIG. 3 is a time series diagram for explaining the operation of the first identification cancellation process. FIG. 7 is a flowchart for explaining a second processing example of release interruption control. FIG. 7 is a time series diagram for explaining the operation of the second identification cancellation process.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of an electric parking brake device EP for a vehicle according to the present invention will be described with reference to the drawings.

<Symbols of component parts, subscripts at the end of the symbol, and direction of movement/movement>
In the following description, components, elements, signals, etc. with the same symbol, such as "MT", have the same function. In the direction of motion/movement of the members (friction member MS itself, parking cable CB, output member SB, end member EN, etc.) related to the friction member MS (including the brake lining BL described later), the "forward direction Ha" is the friction The "backward direction Hb (opposite direction to the forward direction Ha)" corresponds to the direction in which the member MS approaches the rotating member KT (including the brake drum BD, which will be described later), and the "backward direction Hb (direction opposite to the forward direction Ha)" corresponds to the direction in which the friction member MS moves away from the rotating member KT. handle. Therefore, when the member related to the friction member MS is moved in the forward direction Ha, the pressing force (also referred to as "clamping force") Fa, which is the force with which the friction member MS is pressed against the rotating member KT, is increased, and the braking force is increased. is increased. Conversely, when the member related to the friction member MS is moved in the backward direction Hb, the clamping force Fa is reduced and the braking force is reduced.

In the rotational direction of the electric motor MT, the normal rotation direction Da of the electric motor MT corresponds to the movement of each member in the forward direction Ha. Further, the reverse direction Db (rotation direction opposite to the forward rotation direction Da) of the electric motor MT corresponds to the backward direction Hb of each member. That is, when the electric motor MT is rotationally driven in the normal rotation direction Da, the friction member MS is moved in the forward direction Ha, the tightening force Fa is increased, and the braking force is increased. Conversely, when the electric motor MT is rotationally driven in the reverse direction Db, the friction member MS is moved in the backward direction Hb, the tightening force Fa is reduced, and the braking force is reduced.

In the energization amount (for example, current value) of the electric motor MT, the energization amount corresponding to the forward rotation direction Da is the "forward rotation energization amount Ia", and the energization amount corresponding to the reverse rotation direction Db is the "reverse rotation energization amount Ib", They are called respectively. The forward energization amount Ia corresponds to when a positive voltage is applied to the electric motor MT, and the reverse energization amount Ib corresponds to when a negative voltage is applied to the electric motor MT. Therefore, the forward rotation and reverse rotation energization amounts Ia and Ib differ in the direction in which the current flows (that is, the energization direction).

<Brake device DB>
The brake device DB is provided on the wheels of the vehicle and generates a braking force on the wheels (for example, rear wheels). In the braking device DB, a friction member MS (brake pad, brake lining, etc.) is pressed by a rotating member KT (brake disc, brake drum, etc.) to generate a braking force (referred to as "deceleration braking force Fx") that decelerates the vehicle. , and a braking force (referred to as "parking braking force Fp") that maintains the stopped state of the vehicle.

With reference to the overall configuration diagram of FIG. 1, the braking device DB will be explained using a known drum type brake as an example. The deceleration braking force Fx is generated using the pressure (hydraulic pressure) of the brake fluid in the wheel cylinder (not shown) as a power source. Moreover, the parking braking force Fp is generated using the electric motor MT included in the electric actuator (also simply referred to as "actuator") DN as a power source. The electric motor MT is energized and driven by a controller ECU that receives power from a power source (generator AL, storage battery BT) mounted on the vehicle. Note that the deceleration braking force Fx is used for the service brake, and the parking braking force Fp is used for the parking brake.

《Service brake operation》
The braking device DB includes a brake drum BD, brake shoes BSa, BSb, a wheel cylinder (not shown), and a backing plate BP to generate a deceleration braking force Fx.

In the braking device DB, the brake drum BD (an example of a "rotating member KT") is fixed to the wheel so as to rotate together with the wheel around the rotation axis Jk of the wheel. The braking device DB is equipped with two brake shoes BSa and BSb. The two brake shoes BSa and BSb extend in an arc shape along the inner peripheral surface Mn of the cylindrical brake drum BD. A brake lining BL (an example of a "friction member MS") is baked onto the brake shoes BSa and BSb. The brake device DB is equipped with a disc-shaped backing plate BP. Wheel cylinders, brake shoes BSa, BSb, etc. (not shown) are arranged outside the backing plate BP in the vehicle width direction.

Two brake shoes BSa and BSb are pressed against the inner peripheral surface Mn of the brake drum BD by the wheel cylinder. As a result, braking torque is applied to the brake drum BD due to friction between the brake lining BL provided on the brake shoes BSa, BSb and the brake drum BD (in particular, the inner circumferential surface Mn), and as a result, the braking force is applied to the wheels. Generate Fx. In other words, the wheel cylinder is used to decelerate the vehicle while it is running.

Specifically, the lower end portions of the brake shoes BSa, BSb are rotatably supported by the backing plate BP around two rotational positions Ja, Jb. The wheel cylinder is supported by the upper end of the backing plate BP. The wheel cylinder has two movable parts (pistons) that can protrude in the longitudinal direction of the vehicle, and the movable parts are protruded by the pressure of the brake fluid in the wheel cylinder. The protrusion of the movable part pushes the upper ends of the brake shoes BSa, BSb, and the brake lining BL is pressed against the inner circumferential surface Mn of the brake drum BD. Friction between the brake lining BL and the inner circumferential surface Mn applies braking torque to the brake drum BD, thereby braking the wheels.

The braking device DB is equipped with a return member (for example, a coil spring) not shown, and when the pressure on the brake shoes BSa, BSb is released by the return member, the brake shoes BSa, BSb are returned to the brake drum. It is moved away from the inner circumferential surface Mn of the BD.

《Operation of parking brake》
The braking device DB includes, in addition to the above-mentioned components (brake drum BD, etc.), an electric actuator DN, a parking lever PL, a parking cable CB, and a shoe strut ST to generate parking braking force Fp. .

The electric actuator DN is used for braking during parking as an actuator that drives the brake shoes BSa and BSb. Specifically, the two brake shoes BSa and BSb are moved by the electric actuator DN driven by the electric motor MT so as to generate the parking braking force Fp. Details of the actuator DN will be described later. Note that the actuator DN may be used for braking while the vehicle is running (ie, service brake).

The parking lever PL is provided between one of the two brake shoes BSa, BSb (for example, the brake shoe BSa) and the backing plate BP so as to overlap the brake shoe BSa and the backing plate BP. ing. The parking lever PL is rotatably supported by the brake shoe BSa about the rotation axis Jp. In the parking lever PL, a parking cable CB is connected to a lower end Pb on the side far from the rotation axis JP.

A shoe strut ST is provided between the two brake shoes BSa and BSb. When applying the parking brake, the parking cable CB is pulled in the forward direction Ha by the actuator DN. As a result, the parking lever PL attempts to rotate around the rotation axis Jp, so that the shoe strut ST is stretched between the two brake shoes BSa and BSb. The tension of the shoe strut ST pushes one brake shoe BSb, and the reaction force pushes the other brake shoe BSa. As a result, the brake linings BL of the brake shoes BSa, BSb are pressed against the inner peripheral surface Mn of the brake drum BD, and parking braking force Fp is generated.

When releasing the parking brake, the tension of the parking cable CB is reduced by the actuator DN, and the tightening force Fa (pressing force) of the brake lining BL against the inner peripheral surface Mn of the brake drum BD is reduced. Then, the inner circumferential surface Mn of the brake drum BD and the brake lining BL are eventually separated by the return member.

<Electric parking brake device EP>
An embodiment of an electric parking brake device EP according to the present invention will be described with reference to a schematic diagram including a partial cross-sectional view of FIG. A vehicle equipped with the electric parking brake device EP is provided with a parking brake switch (also simply referred to as a "parking switch") SW. The parking switch SW is a switch operated by the driver, and outputs an on or off signal Sw (referred to as a "parking signal") to an electronic control unit ECU (also referred to as a "controller"). That is, the parking switch SW operated by the driver instructs the operation (applying operation or releasing operation) of the parking brake that maintains the stopped state of the vehicle. Specifically, when the parking signal Sw is in the on state (ON), application (operation) of the parking brake is instructed so that it is effective. Conversely, when the parking signal Sw is in an off state (OFF), an instruction is given to release (actuate) the parking brake so that it does not work.

The vehicle is equipped with a plurality of controllers (electronic control units) ECA and ECB in addition to a controller ECU for the electric parking brake device EP. These controllers are connected via a communication bus BS so that signals (detected values, calculated values, etc.) are shared. For example, the vehicle speed Vx, the operation amount Ap of an acceleration operation member (for example, an accelerator pedal), etc. are input to the controller ECU from the communication bus BS. The vehicle speed Vx and the acceleration operation amount Ap are used for the automatic mode of the electric parking brake device EP.

While the release control is being executed, an operation interruption request to interrupt the release control may be transmitted from the other controllers ECA and ECB to the controller ECU via the communication bus BS. The other controllers ECA and ECB are devices that share a power source (a power source, a storage battery BT, and a generator AL) with the electric parking brake device EP (i.e., controller ECU), and also control a large electric motor and a solenoid. (system). For example, such devices include an engine starting device, a speed change control device, and the like.

When a large electrical device (for example, an electric motor or a solenoid) is started (when the power is turned on), a large current exceeding the rated current value is temporarily passed in the initial stage. This large current is called "rush current" or "starting current." The above-mentioned operation interruption request is made in order to avoid restarting each device due to a drop in the voltage of the power supply BT due to an inrush current. For example, an operation interruption request (a request to start, continue, or end interruption) is made using a control flag FK (also referred to as a "request flag"). Specifically, "FK=0" indicates "no interruption request", and "FK=1" indicates "interruption request present". Therefore, the suspension request is started when the request flag FK is changed from "0" to "1", and when the request flag FK is maintained at "1", the suspension request is continued and the request flag FK is changed to "1". The interrupt request is ended by transitioning from "0" to "0".

The electric parking brake device EP includes an electric actuator DN and a controller ECU. Actuator DN generates parking braking force Fp by electric motor MT. The actuator DN will be explained below. Note that the characteristic part of the electric parking brake device EP according to the present invention is a control algorithm programmed into the controller ECU.

《Electric actuator DN》
The electric actuator DN is fixed to the inner surface of the backing plate BP in the vehicle width direction on the opposite side of the backing plate BP from the brake shoes BSa, BSb. A parking cable CB is extended from the actuator DN. The parking cable CB passes through a through hole provided in the backing plate BP, and is connected to the parking lever PL (particularly, the lower end portion Pb).

The actuator DN includes a housing HG, an electric motor MT, a speed reducer GS, a power conversion mechanism HN, a parking cable CB, and an end member EN. The housing HG supports the electric motor MT, the speed reducer GS, and the power conversion mechanism HN, and covers these components. Electric motor MT is a power source for generating parking braking force Fp. Electric motor MT is driven by controller ECU.

The speed reducer GS is composed of a plurality of gears. For example, the speed reducer GS includes a large diameter gear DK and a small diameter gear SK. A small diameter gear SK is fixed to the output shaft SF of the electric motor MT. A large diameter gear DK is meshed with the small diameter gear SK. The output of the electric motor MT (ie, the rotational power of the output shaft SF) is reduced in speed via the reduction gear GS. The reduced rotational power of the electric motor MT is input to the power conversion mechanism HN.

The power conversion mechanism HN includes an input member NB, an output member SB, and a rotation prevention member MD. A large diameter gear DK is fixed to the input member NB. Therefore, the input member NB is rotationally driven integrally with the large diameter gear DK. The input member NB has a cylindrical shape, and a male thread Oj is formed on the outer circumference thereof. The input member NB is a "bolt member".

The male thread Oj of the input member NB is screwed into the female thread Mj of the output member SB. Specifically, the output member SB has a cylindrical shape, and a female thread Mj is formed on the inner peripheral portion (inside the through hole). The output member SB is a "nut member". In the power conversion mechanism HN, an input member NB (bolt member) and an output member SB (nut member) are engaged with each other, and the rotational power of the electric motor MT is converted into linear power. Here, a self-locking mechanism (a mechanism with zero reverse efficiency) is employed as the power conversion mechanism HN.

The rotational movement of the output member SB is regulated by the rotation stopper MD fixed to the housing HG. That is, the output member SB is prevented from rotating by the rotation prevention member MD, and the linear movement of the output member SB is guided. For example, a flange portion Fl is provided on the outer peripheral portion of the output member SB, and at least one chamfer is formed on the flange portion Fl. The rotation prevention member MD has a cylindrical shape, and its inner surface is processed so that it can fit into the two chamfers of the flange portion Fl. The rotational movement of the output member SB is regulated by sliding the two-chamfered portion (flat surface) of the flange portion Fl and the two-chamfered portion (flat surface) of the detent member MD. Thereby, the output member SB is linearly moved along the rotation axis Jn of the input member NB. Note that the detent member MD has an end surface Mb formed on the opposite side to the side to which the large diameter gear DK is fixed.

The parking cable CB passes through the inner peripheral surface (through hole) of the input member NB and extends in the direction of the rotation axis Jn. One end of the parking cable CB is coupled to a parking lever PL, which is a movable member, so as to operate the brake shoes BSa, BSb. An end member EN is coupled to the other end of the parking cable CB. The end member EN has a cylindrical portion and a flange portion. The parking cable CB and the end member EN are joined (fixed) by crimping the cylindrical portion of the end member EN from the outside. The flange portion (particularly the end surface Ma) of the end member EN projects outward in the radial direction from the end portion Mc of the output member SB, and is capable of abutting against the end portion Mc. Further, the flange portion (particularly the end surface Ma) can come into contact with the end surface Mb of the detent member MD.

In FIG. 2, a state (a) shown on the left side with respect to the rotation axis Jn (dotted chain line) of the input member NB illustrates a state in which the electric motor MT is driven and tension is applied to the parking cable CB. In state (a), the brake shoes BSa, BSb are pressed against the brake drum BD, and the wheels are restrained by the electric parking brake device EP (that is, the parking braking force Fp is applied to the wheels). This state (a) is called the "applied state" and is a state in which the parking brake is in effect.

In FIG. 2, a state (b) shown on the right side of the input member NB with respect to the rotation axis Jn illustrates a state in which the tension on the parking cable CB is released. Here, the end member EN and the output member SB are not integrated, but are configured to be separable in the axial direction. In state (b), the brake shoes BSa and BSb are apart from the brake drum BD, and the parking braking force Fp does not act on the wheels. This state (b) is called a "released state" and is a state in which the parking brake is not working.

《Controller ECU》
A controller ECU (electronic control unit) controls the electric motor MT and drives the actuator DN. The controller ECU includes an electric circuit board on which a microprocessor MP and the like are mounted, and a control algorithm programmed into the microprocessor MP. The controller ECU is supplied with power from a storage battery BT charged by a generator AL. Using the power from the storage battery BT, the controller ECU executes the above control algorithm and energizes the electric motor MT. Note that, as described above, power is also supplied to the controllers ECA and ECB of other systems by the storage battery BT.

In the controller ECU, a drive signal Mt for controlling the electric motor MT is calculated based on a control algorithm in the microprocessor MP. Further, the controller ECU is equipped with a drive circuit DR to drive the electric motor MT. In the drive circuit DR, a bridge circuit is formed by switching elements (power semiconductor devices such as MOS-FETs and IGBTs). The energization state of each switching element is controlled according to the drive signal Mt, and the output of the electric motor MT is controlled. The drive circuit DR includes an energization amount sensor IA that detects the actual forward rotation energization amount Ia (corresponding to the forward rotation direction Da) and reverse rotation energization amount Ib (corresponding to the reverse rotation direction Db) of the electric motor MT. For example, a current sensor is employed as the energization amount sensor IA, and currents Ia and Ib supplied to the electric motor MT are detected.

The application operation of the parking brake (that is, the operation of applying the parking brake, and the transition from the release state (b) to the application state (a)) will be explained. The control of actuator DN when the parking brake is applied is called "application control." When the parking switch SW is operated and the parking signal Sw is switched from off to on, application of a positive voltage to the electric motor MT is started. The electric motor MT is supplied with the forward rotation energization amount Ia, and the electric motor MT is rotationally driven in the forward rotation direction Da. This rotational power is transmitted to the input member NB via the reducer GS. The rotational power of the input member NB is converted into linear power of the output member SB. Here, the output member SB is guided to move along the rotation axis Jn (movement in the forward direction Ha) by the rotation preventing member MD (particularly, the two chamfered portions of the flange portion Fl and the inner peripheral portion Mm). When applying the parking brake, the output member SB is moved in the forward direction Ha. In a state where the end portion Mc of the input member NB and the end surface Ma of the end member EN are not in contact with each other, no tension is applied to the parking cable CB. Therefore, the electric motor MT generates an output corresponding to the frictional force (sliding friction) with respect to the movement of the input member NB, output member SB, detent member MD, etc.

Since the parking cable CB and the end member EN are fixed, when the end Mc of the input member NB and the end surface Ma of the end member EN come into contact, tension is generated in the parking cable CB. By moving the end member EN in the forward direction Ha, the tension of the parking cable CB is increased. As a result, the tightening force Fa of the brake lining BL against the brake drum BD is increased, and the parking braking force Fp is increased. Since the torque output of the electric motor MT is approximately proportional to the forward energization amount Ia, the energization to the electric motor MT is stopped when the forward energization amount Ia reaches the end threshold ix. Here, the end threshold ix is a predetermined value (constant) set in advance, and corresponds to a value that can ensure a sufficient pressing state between the brake lining BL and the brake drum BD so that the parking brake is effective. . Since the power conversion mechanism HN self-locks, the tension in the parking cable CB is maintained even after the power supply to the electric motor MT is stopped, and the parking brake is maintained in an applied state (that is, in an applied state).

Next, the parking brake release operation (that is, the operation of disabling the parking brake, and the transition from the application state (a) to the release state (b)) will be explained. The control of the actuator DN when the parking brake is released is called "release control." When the parking switch SW is operated and the parking signal Sw is switched from on to off, application of a negative voltage to the electric motor MT is started. A reverse energization amount Ib is supplied to the electric motor MT, and the electric motor MT is rotationally driven in a reverse direction Db. The output member SB is moved in the backward direction Hb (the opposite direction (opposite direction) to the forward direction Ha) by the rotational power of the electric motor MT. As a result, the tension of the parking cable CB is reduced, and the tightening force Fa (as a result, the parking braking force Fp) is reduced. Then, the end surface Ma of the end member EN comes into contact with the end Mb of the rotation prevention member MD. Up to this point, the end member EN and the output member SB are moved as one. That is, when the parking brake is released (disabled), the output member SB is moved in the backward direction Hb.

Further, when the electric motor MT is driven in the reverse direction Db, the end member EN and the output member SB are separated (separated). Thereby, the tension of the parking cable CB is set to approximately "0 (zero)". From this point on, the electric motor MT is driven in the reverse direction Db based on the time T. Then, the end Mk of the output member SB (opposite to the end Mc) and the part Md of the input member NB are connected to the electric motor MT with a certain distance (i.e., gap Lr) between them. energization is stopped, and movement of the output member SB in the backward direction Hb is stopped. In other words, when the output member SB stops moving, there is a gap between the end Mk of the output member SB and the portion Md of the input member NB, so that a stopper or the like is not required.

<Release control processing>
The release control process will be described with reference to the flowchart in FIG. 3. "Release control" is control that serves as a reference for transitioning from an application state where the parking brake is working to a release state where it is not working. In other words, the release control is a control for releasing the parking brake. The release control is started when the parking signal Sw is switched from on to off. Here, switching the parking signal Sw from on to off is referred to as a "release instruction." The release control is performed by drive control of the electric motor MT. Specifically, in the release control, the electric motor MT is energized (for example, a negative voltage is applied), and the electric motor MT is driven in the reverse direction Db.

In step S110, various signals including the parking signal Sw and the actual energization amounts Ia and Ib are read. For example, the forward rotation and reverse rotation energization amounts Ia and Ib (actual values) are detected by the energization amount sensor IA (current sensor) provided in the drive circuit DR. Furthermore, the energization amount sensor IA may be built into the electric motor MT.

In step S120, electric motor MT is energized. Specifically, at the time of the cancellation instruction (corresponding calculation cycle) when the parking signal Sw changes from on to off, a voltage with a negative sign (-) is applied to the electric motor MT. After the energization is started, in step S120, the application of the negative voltage to the electric motor MT is continued. Thereby, the electric motor MT continues to be driven in the reverse direction Db.

In step S130, it is determined whether or not the state is in a contact-resolved state (referred to as "contact-resolved determination"). The "contact released state" is a state in which the brake lining BL (i.e., friction member MS) and brake drum BD (i.e., rotating member KT), which were in contact, are no longer in contact with each other. For example, the contact cancellation determination is performed based on "whether the amount of reverse energization Ib is constant or not." The contact-resolved state is determined based on the fact that the amount of reverse energization Ib has become constant (a constant state of the amount of reverse energization Ib).

In a state where the brake lining BL (friction member MS) and the brake drum BD (rotating member KT) are substantially out of contact (contact canceled state), the tension in the parking cable CB becomes substantially zero, and the reverse energization amount Ib remains constant. . At this time, the output of the electric motor MT is determined by the friction (sliding) of the power transmission mechanism (electric motor MT, reduction gear GS, input member NB, output member SB, parking cable CB, etc.) from the electric motor MT to the friction member MS. (dynamic friction) only. In other words, the magnitude of the reverse energization amount Ib supplied to the electric motor MT in the contact-released state is a value corresponding to the friction of the power transmission member.

For example, "a constant state of the reverse energization amount Ib (i.e., a contact-resolved state)" means that the state in which the reverse energization amount Ib is within a predetermined range (within the determination amount ih) is a predetermined state. The determination is made at the point in time that continues for a time th (referred to as "determination time"). In addition, the contact release state is a state in which the amount of change dIb (which is a time differential value of the amount of reverse energization Ib and is also referred to as the "release energization change amount") with respect to time T in the amount of reverse energization Ib is equal to or less than the determined amount of change dx. may be determined at a time when the determination period th is maintained. Here, the determination amount ih, the determination time th, and the determination change amount dx are predetermined values (constants) set in advance.

In step S130, when it is determined that the contact is in the contact-resolved state (also referred to as "contact-resolved confirmed"), the control flag FF (also referred to as the "determination flag") is set to "1". Here, the judgment flag FF is "0" to indicate that "the contact is not resolved or the contact state is unknown" (also referred to as "contact resolved unconfirmed"), and "1" to indicate " "Contact cancellation confirmed" is displayed. Note that the determination flag FF is set to "0 (contact cancellation undetermined)" as an initial value before starting execution of the cancellation control.

In order to improve the robustness of contact cancellation determination, "the reverse energization amount Ib is equal to or greater than the release amount ik" may be added as a permission condition to the determination conditions. For example, when the transmission efficiency of the power transmission member (reducer GS, power conversion mechanism HN, etc.) decreases, the amount of change dIb of the reverse energization amount Ib with respect to time T (i.e., the increasing slope of the reverse energization amount Ib) becomes small. Therefore, even if the brake lining BL is still in contact with the brake drum BD, a situation may arise in which the constant state of the reverse energization amount Ib is determined. Therefore, in the state of "Ib<ik", the execution of the contact resolution determination is prohibited, and only when the state of "Ib≧ik" is reached, the execution of the contact resolution determination is permitted. Here, the release amount ik is a predetermined value (negative constant). The release amount ik is determined when the electric motor MT is driven with no load in a normal state (normal temperature) (i.e., sliding friction of the electric motor MT, reducer GS, input member NB, output member SB, rotation prevention member MD, etc.) The value is set to be slightly larger than the amount of current that corresponds to .

If step S130 is negative, the process returns to step S110. On the other hand, if step S130 is affirmed, the process proceeds to step S140. Here, the time point when step S130 is affirmed for the first time (the corresponding calculation cycle) is referred to as the "confirmation time point."

In step S140, the release duration time Tk is calculated. The cancellation continuation time Tk is the time from the time when step S130 is affirmed for the first time (the corresponding calculation cycle). In other words, the cancellation duration Tk is the time elapsed from the starting point (reference) at the time of switching (transition) from the state of unconfirmed contact to the confirmed state of contact dissolving (confirmed time). It is.

In step S150, it is determined whether "the release continuation time Tk is longer than or equal to the release threshold time tk". Here, the release threshold time tk is a predetermined value (constant) set in advance, and is a threshold value corresponding to the release continuation time Tk for terminating the release control (release operation). If "Tk<tk" and step S150 is negative, the process returns to step S110. On the other hand, if "Tk≧tk" and step S150 is affirmed, the process proceeds to step S160. In step S160, application of voltage to electric motor MT is stopped, and energization is stopped. That is, in step S160, driving of the electric motor MT is stopped, and the release control is ended.

As explained above, in the electric parking brake device EP, when the parking brake is released, the contact cancellation state is determined for the first time (for example, the time when the amount of reverse energization Ib to the electric motor MT becomes constant) ), when the release threshold time tk has elapsed (corresponding calculation cycle), the power supply to the electric motor MT is stopped, and the driving of the electric motor MT is stopped. As a result, the movement of the output member SB in the backward direction Hb is completed, and the output member SB comes to rest. At this time, the end Mk of the output member SB and the portion Md of the input member NB have a gap Lr and are not in contact with each other. In other words, since the release control of the electric parking brake device EP is performed according to the time T, there is no need to restrict the movement of the output member SB in the backward direction Hb by contact with a movement restriction member such as a stopper. .

In a state where the electric parking brake device EP is released, the electric motor MT and the members driven by the electric motor MT (output member SB, input member NB, etc.) are in a non-restricted state (free state). Specifically, when the parking brake is released (that is, the parking brake is not working), the male thread Oj and the female thread Mj of the power conversion mechanism HN are not tightened. Therefore, when the parking brake instruction is issued again and the application control of the electric parking brake device EP is started, there is no need to supply power to release this tightening, and the power of the electric motor MT is reduced. Power saving is achieved. Furthermore, since the movement restricting member of the output member SB can be omitted, the device can be made smaller and lighter.

<Release control operation>
The operation of release control will be described with reference to the time series diagram (transition diagram of state quantities with respect to time T) in FIG. 4 . Note that the reverse energization amount Ib (for example, current value) has a negative sign (-) with respect to the forward rotation energization amount Ia, which has a positive sign (+), and corresponds to the movement of the electric motor MT in the reverse direction Db. ing. That is, the forward rotation energization amount Ia and the reverse rotation energization amount Ib are different in the energization direction (for example, the direction in which the current flows). In the example, the above-mentioned permission condition "Ib≧ik(<0)" is provided in the release control, but this condition can be omitted.

The parking switch SW is turned from the on state to the off state, and release control is started at time t0. Due to the release control, a negative voltage is applied to the electric motor MT. As a result, energization of the electric motor MT is started, and the electric motor MT is driven in the reverse direction. That is, the operation based on the release control (release operation) is started. At time t0, the determination flag FF is set to "0 (contact cancellation undetermined)" as an initial value. The electric motor MT is driven in the reverse direction Db, but at least until time t1, the end member EN and the output member SB are in contact with each other, and tension is applied to the parking cable CB. By driving the electric motor MT in reverse, the tension in the parking cable CB is gradually reduced, and the reverse energization amount Ib (negative value) gradually increases and approaches "0".

At time t1, the reverse energization amount Ib becomes equal to or greater than the release amount ik, and the prohibited contact cancellation determination is permitted. At time t2, in the braking device DB, the brake lining BL and the brake drum BD (in particular, the inner circumferential surface Mn) are substantially no longer in contact with each other. Accordingly, at time t2, the reverse energization amount Ib becomes substantially constant for the first time, and it is determined that "the reverse energization amount Ib has become constant." However, at time t2, the constant state of the reverse energization amount Ib has not yet continued over the determination time th, so the contact-resolved state is not determined (determined). Note that the constant state of the reverse energization amount Ib is determined by the fact that the energization amount Ib is within a predetermined range ih (a determination amount and a predetermined constant set in advance). Further, the constant state is determined when the time change amount dIb of the reverse energization amount Ib (which is a time differential value and the release energization change amount) is less than or equal to the determination change amount dx (a predetermined constant set in advance). It's okay.

At time t3, when a determination time th (a preset constant) has elapsed from time t2, it is determined (confirmed) that the contact is in the released state, and step S130 is satisfied for the first time. Accordingly, at time t3 (confirmation time), the determination flag FF is switched from "0 (contact cancellation not confirmed)" to "1 (contact cancellation confirmed)", and the cancellation continuation time Tk is calculated (time integration) is started. At time t4, when a release threshold time tk (a preset constant) has elapsed from time t3, the application of the negative voltage to electric motor MT is stopped, and energization is stopped. That is, the release control is ended, the amount of reverse energization (for example, current value) Ib is set to "0", and the reverse drive of the electric motor MT is stopped. At this time, the determination flag FF is returned from "1" to the initial value "0". Upon completion of the release control, the movement of the output member SB is stopped. Note that at the end of the release control, there is a gap between the output member SB and the input member NB.

<First processing example of cancellation interruption control>
A first processing example of release interruption control will be described with reference to the flowchart of FIG. 5. The "cancellation interruption control" is control performed when there is a request (suspension request) from another controller ECA or ECB to suspend the operation of the cancellation control while the above-mentioned cancellation control is being executed. In other words, the release interruption control is a control for bringing the parking brake into the released state after a request to interrupt the operation of the release control is received. For example, a request to interrupt the release operation is made by transmitting and receiving a control flag (request flag) FK between the controllers via the communication bus BS. Note that the controller ECU and the other controllers ECA and ECB share a power source BT.

In step S210, various signals including the request flag FK, determination flag FF, and forward and reverse energization amounts Ia and Ib (values detected by the energization amount sensor IA) are read. In step S220, it is determined whether "the release operation is being interrupted or not" based on the operation interruption request flag FK. If the state where the request flag FK is "1 (interruption requested)" continues and the operation by the release control (release operation) is being interrupted, step S220 is affirmed and the process proceeds to step S250. If the request flag FK continues to be "0 (no interruption request)" and the release operation is not interrupted, step S230 is denied and the process proceeds to step S240.

In step S230, it is determined based on the request flag FK whether "interruption of the release operation is started or not." If “FK=0” in the previous calculation cycle and transitions to “FK=1” in the current calculation cycle, it is determined that the cancellation operation is to be interrupted (that is, step S230 is affirmed), and the process is continued. The process advances to step S240. If step S230 is affirmed, the release duration Tk is reset and returned to "0". On the other hand, if there is no request to suspend the release operation and the request flag FK remains at "0", the start of suspension is not determined (i.e., step S230 is denied), and the process returns to step S210 (i.e. , the release operation continues). Note that the time point when step S230 is affirmed for the first time (the corresponding calculation cycle) is referred to as the "interruption start time point."

In step S240, application of the negative voltage to the electric motor MT is stopped in response to the request to interrupt the release operation. That is, in the calculation cycle in which step S230 is affirmed, the energization to the electric motor MT is immediately stopped, and the reverse drive of the electric motor MT is stopped.

In step S250, it is determined based on the request flag FK whether or not the suspension of the release operation is ended. If "FK=1" in the previous calculation cycle and transitions to "FK=0" in the current calculation cycle, the interruption request is terminated, so it is determined that the interruption of the release operation is completed (i.e., Step S250 is affirmative), and the process proceeds to step S260. On the other hand, if the request for interrupting the release operation continues and the request flag FK remains "1", it is not determined that the interrupt has ended (that is, step S250 is denied), and the process proceeds to step S240 ( In other words, the power supply to the electric motor MT continues to be stopped. Note that the time point when step S250 is affirmed for the first time (the corresponding calculation cycle) is referred to as the "interruption end time point."

In step S260, based on the determination flag FF, it is determined whether or not the contact was in a canceled state when the operation interruption was requested (that is, whether the contact was resolved or whether the contact was not resolved). If "FF=0" and the interruption request is received before the contact cancellation state is determined (contact cancellation is undetermined at the time the interruption request is started), step S270 is denied. , the process proceeds to step S270. On the other hand, if "FF=1" and the interruption request is received after the contact cancellation state is confirmed (if the contact cancellation is confirmed at the time the interruption request is started), step S270 is affirmed. , the process proceeds to step S280.

In step S270, the release control described with reference to FIGS. 3 and 4 is executed again. The process in which the release control is executed again is called "re-release process (process when an interruption request is made before contact cancellation is confirmed)". When the re-release process is executed, the brake lining BL is in contact with the brake drum BD. Therefore, even if the release operation is executed again, since the contact cancellation determination is performed, the amount of movement of the output member SB in the backward direction Hb will not become excessive (that is, the output member SB will not be returned too much).

In step S280, once the electric motor MT is energized with the forward rotation energization amount Ia and the electric motor MT is driven in the forward rotation direction Da, the release control described with reference to FIGS. 3 and 4 is executed again. . The process in which the release control operation is executed again after the forward rotation energization amount Ia is supplied to the electric motor MT is called "first specific release process (process when an interruption request is made after contact cancellation is confirmed)". be called. In the release control, the point in time when the contact cancellation is established is used as a reference, and the reverse energization amount Ib is stopped based on the time from this reference (namely, the release continuation time Tk). When the energization is stopped in response to the interruption request, the reference for the release duration Tk becomes unclear, and an excessive displacement of the output member SB in the backward direction Hb may occur. Therefore, in the first specific cancellation process, at the end of the interruption request, first, the electric motor MT is driven to rotate in the normal direction, and the brake lining BL and the brake drum BD are brought into contact again (i.e., a state in which contact cancellation is uncertain). ). After that, the operation based on the release control (see FIGS. 3 and 4) is executed again. Due to the release control, the contact cancellation determination is performed again and the reference (starting point) of the release duration Tk is clarified, so that excessive displacement of the output member SB is suppressed.

≪Supply of forward energization amount Ia in the first specific cancellation process≫
Hereinafter, the supply (application) of the forward rotation energization amount Ia in the first specification cancellation process will be explained in detail. The forward rotation energization amount Ia is supplied to drive the electric motor MT to rotate in the forward direction to bring the brake lining BL and the brake drum BD into contact, and to return the contact-resolved state to the contact-resolved state. This is to deal with the following situations. The reverse energization amount Ib in the release operation is eventually stopped according to time (particularly, the release duration Tk). However, if the reverse energization amount Ib is stopped due to an interruption request, ``a situation in which the starting point of the cancellation duration Tk becomes unclear'' and ``when the reverse energization amount Ib is supplied again, the reverse energization amount "Situation affected by inrush current corresponding to Ib" occurs. Due to these situations, the output member SB is excessively displaced in the backward direction Hb.

In the first specification cancellation process, the forward rotation energization amount Ia is determined by "determination of inrush current" and "contact state between brake lining BL (i.e., friction member MS) and brake drum BD (i.e., rotating member KT)". determination (referred to as “contact determination”)”. Although these determinations are related to each other, they will be explained in order below.

The forward rotation energization amount Ia is affected by the rush current when the electric motor MT is started. Therefore, when supplying the normal rotation energization amount Ia, it is necessary to determine whether there is an influence of rush current. For example, the presence or absence of the influence of rush current is determined based on the energization time Tj (referred to as "application duration time") of the forward rotation energization amount Ia. This is based on the fact that the time (period) during which the rush current flows is known. An application continuation time Tj is calculated, which is the time during which the electric motor MT is energized (supplied) with the normal rotation energization amount Ia from the time when the energization (supply) of the normal rotation energization amount Ia is started. Then, based on the fact that the application duration Tj has exceeded a predetermined time tt (referred to as "specific application time"), it is determined that the influence of the rush current is no longer exerted. Here, the specific application time tt is a predetermined value (constant) set in advance. If the application duration Tj is less than the specific application time tt, the above contact determination is prohibited and the supply of the forward energization amount Ia is continued. Contact determination is permitted when the application duration Tj is longer than the specific application time tt. Then, when the presence of contact is denied (that is, the case of non-contact), the supply of the normal rotation energization amount Ia is continued. However, if the presence of contact is affirmed, the supply of the forward energization amount Ia is stopped (terminated).

In a situation where an inrush current is an influence, the forward rotation energization amount Ia changes rapidly. Therefore, the influence of the rush current may be determined based on the time variation dIa of the forward energization amount Ia (which is a time differential value of the forward energization amount Ia, also referred to as "the energization variation"). From the point in time when the supply of the forward energization amount Ia to the electric motor MT is started, the applied energization change amount dIa is calculated based on the forward energization amount Ia. Then, when the applied energization change amount dIa continues to be less than a predetermined change amount dj (referred to as "application determination change amount") for an application determination time tj, it is determined that the inrush current is no longer affected by the inrush current. be done. Here, the application determination time tj and the application determination change amount dj are constants (predetermined values) set in advance. In other words, "if the applied energization change amount dIa is equal to or greater than the applied judgment change amount dj", or "even if the applied energization change amount dIa is less than the applied judgment change amount dj, the application judgment time tj has not passed. If there is no contact determination, the contact determination is prohibited and the supply of the forward energization amount Ia is continued. After the state of "dIa<dj" continues for the application determination time tj, contact determination is permitted. When the presence of contact is denied, the forward rotation energization amount Ia is supplied, but when the presence of contact is affirmed, the supply of the forward rotation energization amount Ia is stopped.

Next, the contact determination of "whether or not the brake lining BL and the brake drum BD have contacted each other" will be explained. The contact determination is performed based on a comparison between the normal energization amount Ia and the threshold energization amount iz (also referred to as "energization amount comparison"). The threshold energization amount iz is a predetermined value (constant) set in advance. If the forward energization amount Ia is less than the threshold energization amount iz, it is determined that "the brake lining BL and the brake drum BD are not in contact (no contact)" and the supply of the forward energization amount Ia continues. be done. When the forward rotation energization amount Ia is equal to or greater than the threshold energization amount iz, it is determined that "the brake lining BL and the brake drum BD have contacted (contact)", and the supply of the forward rotation energization amount Ia is terminated.

The contact determination may be performed based on the applied energization change amount dIa (time differential value of the forward rotation energization amount Ia). This is based on the fact that when the brake lining BL starts to come into contact with the brake drum BD, the load on the electric motor MT increases and the forward rotation energization amount Ia increases. Specifically, when the applied energization change amount dIa is less than the predetermined change amount di (referred to as "contact determination change amount"), it is determined that there is no contact, and the supply of the normal rotation energization amount Ia is continued. Then, when the applied energization change amount dIa is equal to or greater than the contact determination change amount di, it is determined that there is a contact, and the supply (energization) of the normal rotation energization amount Ia is terminated. Here, the contact determination change amount di is a predetermined value (positive constant) set in advance.

As explained above, the supply (application) of the forward rotation energization amount Ia in the first specification cancellation process includes two determinations: an inrush current determination and a contact determination. As the inrush current determination, at least one of the "method based on the applied duration Tj" and the "method based on the applied energization variation dIa" is adopted. In addition, as the contact determination, at least one of "a method based on a comparison of energization amount" and "a method based on an applied energization change amount dIa" is adopted. Furthermore, since the energization pattern of the normal energization amount Ia is known, the influence of rush current and contact may be determined based on the application duration Tj. Therefore, the following combinations are possible for determination regarding the forward rotation energization amount Ia.
(1) The influence of the rush current is determined based on the application duration Tj, and the contact state is determined based on the comparison of the energization amounts.
(2) The influence of the rush current is determined based on the applied duration Tj, and the contact state is determined based on the applied energization change amount dIa.
(3) The influence of inrush current is determined based on the applied energization change amount dIa, and the contact state is determined based on the comparison of energization amounts.
(4) The influence of inrush current and the contact state are determined based on the applied current change amount dIa.
(5) The influence of the rush current and the contact state are determined based on the application duration Tj.

<Operation of re-cancellation process>
The operation of the re-cancellation process in step S270 will be described with reference to the time series diagram of FIG. 6 (diagram showing changes in state quantities with respect to time T). In the re-cancellation process of the cancellation suspension control, the same operation as the cancellation control is restarted when the suspension request is terminated. In other words, the cancellation control is executed again at the end of the interruption request. In the example, a request to interrupt the release operation is started at time point u2. Therefore, the operation from time point u0 to time point u2 corresponds to release control, and the operation after time point u2 corresponds to release interruption control. Note that the period from time point u3 to time point u7 is also the operation of release control. Here, the above-described permission determination of "Ib≧ik" may be omitted.

At time point u0, a release operation is instructed and release control is started. By the release control, a negative voltage is applied to the electric motor MT, and driving of the electric motor MT in the reverse direction Db (reverse drive) is started. At the time u0 when the electric motor MT starts being energized (the time when the supply of the reverse energization amount Ib starts, and the time when the reverse drive starts), "FK=0" continues, and the release operation from other controllers is interrupted. There are no requirements. At time point u1, the permission condition "Ib≧ik" is satisfied, and the contact cancellation determination in step S130 is executed.

At time point u2, "FK=0 (no interruption request)" is switched to "FK=1 (interruption request present)", and interruption (stopping) of the release operation is requested via the communication bus BS. At time u2 (interruption start time), release interruption control is started based on this interruption request. By the release interruption control, the voltage application to the electric motor MT is stopped, and the reverse energization amount Ib is set to "0" (processing of step S240). Further, between time point u0 and time point u2 (especially time point u2 when the reverse energization amount Ib is stopped), the contact cancellation state has not yet been determined, so the contact cancellation state is uncertain, and the determination flag FF is The initial value remains "0 (undefined)".

From time point u2 to time point u3, since "FK=1" is received in the controller ECU, "Ib=0" is maintained and the drive of electric motor MT is stopped. Then, at time point u3, the switching from "FK=1" to "FK=0" is received, and the suspension of the release operation is ended. At time point u3 (interruption end point), step S130 (contact cancellation determination) has not yet been affirmed, and the contact cancellation state has not been determined (determined) (that is, "FF=0" is maintained). This corresponds to the case where the contact cancellation state has not been determined at the time of the interruption request (contact cancellation has not yet been determined), so that the re-cancellation process of step S270 is executed from the end time point u3 of the interruption request. In the re-cancellation process, the same process as the process of the cancellation control is repeated again. In other words, from time point u3 onwards, the release control is executed again.

At time point u3, a negative voltage is applied to the electric motor MT again, the reverse energization amount Ib is supplied, and reverse drive is started. At time point u4, the reverse energization amount Ib becomes equal to or greater than the release amount ik, and the prohibited contact cancellation determination is permitted. At time point u5, it is determined for the first time that the reverse energization amount Ib is in a constant state. At time point u6, the constant state of the reverse energization amount Ib continues to be determined for the determination time th (a preset constant), and the contact released state of the electric motor MT is determined (that is, step S130 is affirmed). ). At this time point u6, the determination flag FF is switched from "0" to "1", and calculation of the release continuation time Tk (accumulation of the time T) is started. At time u7, when a release threshold time tk (a preset constant) has elapsed from time u6, the voltage application to electric motor MT is stopped, and the energization of reverse energization amount Ib is stopped. The reverse drive of the electric motor MT is stopped, and the release interruption control is ended. Upon completion of the control, the movement of the output member SB is stopped. Note that the determination flag FF is returned from "1" to the initial value "0" in response to the end of the control.

In the release interruption control, when there is a request from another controller to interrupt the operation (release operation) by the release control (interruption start time), the power supply to the electric motor MT is immediately stopped. Thereby, a drop in the power supply voltage due to rush current in a device (for example, an engine starting device, a speed change control device) including another controller that shares the power source BT, AL with the controller ECU can be suppressed.

The re-cancellation process of the cancellation suspension control is performed when the cancellation request is canceled when the contact cancellation state is not determined at the time when the cancellation request is made (suspension start point) (in other words, when the cancellation request is made before the contact cancellation is confirmed). This is the processing at the time of termination. In the re-cancellation process, the same drive control of the electric motor MT as the cancellation control is immediately executed again at the point in time when the suspension request is terminated (that is, the point in time when the request termination is received, and the termination point in time). u3 to time point u7). By the re-release process, the parking brake is quickly transitioned to the released state without the output member SB being returned too far when the interruption request ends.

<Operation of first identification cancellation process>
The operation of the first identification cancellation process in step S280 will be described with reference to the time series diagram of FIG. 7. In the first specific cancellation process of the cancellation interruption control, when the interruption request is terminated, the normal rotation energization amount Ia is once energized to the electric motor MT, and the electric motor MT is driven in the forward rotation direction Da, and then the cancellation is performed. The same operation as the control is resumed. In the example, the request for interrupting the release operation is started at time v4. Therefore, the operation from time point v0 to time point v4 corresponds to release control, and the operation after time point v4 corresponds to release interruption control. Note that the period from time v8 to time v12 is also the operation of release control. As described above, the permission determination of "Ib≧ik" may be omitted.

Hereinafter, in the supply of the normal rotation energization amount Ia, the first specific cancellation process will be described using the above (1) as an example. At time point v0, a release instruction is issued and release control is started. At time v0 (the time point at which the supply of reverse energization amount Ib starts, and the time point when reverse drive starts), release control is started, and a negative voltage is applied to electric motor MT. A reverse energization amount Ib is supplied to the electric motor MT, and the electric motor MT is driven in the reverse direction. At time point v1, the condition "Ib≧ik" is satisfied, and contact cancellation determination is permitted. At time point v2, it is determined for the first time that the reverse energization amount Ib is in a constant state. Thereafter, the reverse energization amount Ib is maintained at a constant state, and at time v3, when determination time th has elapsed from time v2, step S130 is affirmed for the first time, and the contact-released state of electric motor MT is determined (determined). In response to the positive result of the contact cancellation determination at time point v3, the determination flag FF is switched from the initial value "0 (contact cancellation unconfirmed)" to "1 (contact cancellation confirmed)". At the same time, calculation of the release duration Tk is started. In other words, the release duration Tk is increased from the initial value "0" starting from the time point v3 when the contact release state is determined.

At time point v4, the received request flag FK is switched from "0" to "1", and another controller requests that the release operation be stopped (interrupted). At time point v4 (interruption start time), release interruption control is started in response to this interruption request. The voltage application to the electric motor MT is stopped, and the reverse energization amount Ib is set to "0" (processing of step S240). The cancellation continuation time Tk is reset to "0 (initial value)" at time v4 (the time when energization is stopped based on the interruption request). At time v4, step S130 (contact cancellation determination) has already been affirmed, and the contact cancellation state has been determined (determined) (that is, "FF=1").

At time point v5, "FK=1" is switched to "FK=0", and the interruption of the release operation is ended (affirmative in step S250). At time point v5 (interruption end time point), since the contact-resolved state has been determined, execution of the first identification cancellation process in step S280 is started. In the first specific cancellation process, the normal rotation energization amount Ia is once increased, and then the cancellation control operation is executed. Therefore, at time v5, first, application of a voltage with a positive sign (+) is started to the electric motor MT.

Calculation of the application duration Tj is started from time point v5 (start point of normal rotation drive), which is the start point of supply of the normal rotation energization amount Ia. Until time point v6, since "Tj<tt", energization amount determination (determination related to rush current) is prohibited. At time point v6, application duration Tj becomes equal to or longer than specific application time tt, which is a predetermined time, and energization amount determination is permitted. Note that the time point at which "Tj≧tt" is satisfied for the first time is referred to as a "specific time point." From the specific point in time v6, comparison of energization amounts is performed. At time point v7, contact between the brake lining BL and the brake drum BD begins, and the forward rotation energization amount Ia is gradually increased. However, until time point v8, since "Ia<iz", the normal rotation energization amount Ia is continuously supplied. At time v8, the forward energization amount Ia becomes equal to or greater than the threshold energization amount iz, and the supply of the forward energization amount Ia is stopped. In addition, at time point v8, the same process as the release control is started. In other words, the release control is executed again from time point v8 (start time of reverse drive).

The operation after time v8 is the same as that after time u3 described with reference to FIG. At time v8, driving of the electric motor MT in the reverse direction Db is started. At time point v9, the condition "Ib≧ik" is satisfied, and contact cancellation determination is permitted. At time point v10, it is determined for the first time that the amount of reverse energization Ib is constant. At time v11, the constant state of the reverse energization amount Ib continues for the determination time th. Therefore, at time point v11, contact cancellation is determined, and calculation of the cancellation continuation time Tk is started. At time v12, when the release threshold time tk has elapsed from time v11, the application of the negative voltage to electric motor MT is stopped, and the driving of electric motor MT is stopped. At time point v12, the release interruption control (control when there is an operation interruption request during execution of release control) is ended.

Similarly to the above, when a request for interrupting the release operation is received from another controller (interruption start time), the release interrupt control immediately stops energizing the electric motor MT. Therefore, even if an inrush current occurs in another controller that shares a power source with the controller ECU, a voltage drop caused by the inrush current is avoided.

In the first specific cancellation process for interrupting the release operation, at the time when the request end is received (see interruption end point v5), the same operation as the release control (reverse drive of the electric motor MT) is not restarted immediately. In the first specific cancellation process, before the cancellation operation is started, the electric motor MT is once energized with the forward rotation energization amount Ia. As a result, the electric motor MT is driven in the normal rotation direction Da, and the brake lining BL is brought into contact with the brake drum BD again. After that, the release operation (supply of reverse energization amount Ib) is restarted. By the first specific cancellation process, the reset cancellation duration Tk is calculated again, so the starting point of the cancellation duration Tk is clarified. In addition, the influence of rush current when electric motor MT is driven in reverse again is eliminated. Thereby, the output member SB is moved to an appropriate position, and excessive displacement in the backward direction Hb can be suitably suppressed.

<Second processing example of cancellation interruption control>
A second processing example of release interruption control will be described with reference to the flowchart of FIG. 8 . In the first process example, excessive displacement of the output member SB is suppressed by the first specific release process (control that performs a release operation after driving the electric motor MT in normal rotation). Instead, in the second processing example, the execution time of the release operation is shortened, thereby suppressing the output member SB from returning too much. In the second processing example as well, the release interruption control is executed when an interruption request is made from the other controllers ECA and ECB that share the power supply BT with the controller ECU during the execution of the release control. For example, an operation interruption request (request for start, continuation, and end) is made by receiving and transmitting a request flag FK.

In the second processing example of the release interruption control, the processing in step S280 is omitted, but the processing in step S290 and step S300 is added to the first processing example. The processing of steps with the same symbols as in the first processing example is the same in the second processing example. For this reason, explanations regarding them will be omitted. Hereinafter, differences from the first processing example will be explained.

If step S260 is negative (that is, if the release interruption request is received before the contact-resolved state is determined), the same re-driving process as in the first process example is executed. On the other hand, if step S260 is affirmed (that is, if the release interruption request is received after the contact-resolved state is determined), a specific threshold time tn is calculated in step S290. The specific threshold time tn is a threshold corresponding to the second return time Tn for terminating the release operation. The specific threshold time tn is determined as a value smaller than the release threshold time tk.

For example, the specific threshold time tn is calculated based on the first return time Tm and the calculation map Ztn. The "first return time Tm" is the time from the time when the contact-resolved state is confirmed (confirmation time) to the time when the interruption request is received (interruption start time), and the cancellation continuation time Tk at the interruption start point. It is. In the calculation map Ztn, the specific threshold time tn is calculated to be smaller than the release threshold time tk and to decrease as the first return time Tm increases.

In step S300, a negative voltage is applied to the electric motor MT, and a reverse energization amount Ib is supplied. Thereby, the electric motor MT is driven in the reverse direction Db. Further, in step S300, a time Tn (referred to as "second return time") from the time when step S250 is satisfied (the time when the interruption ends) is calculated. If the second return time Tn is less than the specific threshold time tn, the supply of the reverse energization amount Ib continues, and the electric motor MT continues to be driven in the reverse direction Db. Then, when the second return time Tn becomes equal to or longer than the specific threshold time tn, the supply of the reverse energization amount Ib is stopped, and the processing of the release interruption control is ended. The process in step S300 is referred to as "second identification cancellation process."

In the first specific release process in the first process example, the electric motor MT is once driven in the normal rotation direction Da at the end of the interruption, and then the release control is executed again. In the second specific release process in the second processing example, the electric motor MT is driven in the reverse direction Db from the time when the interruption ends, and a second return time Tn from the time when the interruption ends is calculated. Then, when the second return time Tn reaches the specific threshold time tn, the driving of the electric motor MT is stopped, and the processing of the release interruption control is completed. Since the specific threshold time tn is determined to be smaller than the release threshold time tk, excessive pulling back of the output member SB can be suppressed. Note that when the release operation is performed again, an inrush current related to the reverse energization amount Ib is generated due to the resupply of the reverse energization amount Ib, but the effect thereof is known. Therefore, the amount of movement (displacement) of the output member SB due to the rush current can be estimated in advance. Therefore, the specific threshold time tn is determined with this influence in mind.

The cancellation duration Tk is reset at the time when the cancellation suspension request is received (the suspension start time), but the time from the confirmation time to the suspension start time (i.e., the cancellation duration Tk at the suspension start time) is It is stored as 1 return time Tm. This is based on the fact that it is possible to determine how much the output member SB has been displaced before the operation interruption is requested based on the first return time Tm. Then, based on the first return time Tm, it is calculated such that the longer the first return time Tm, the smaller the specific threshold time tn. In the second specific cancellation process, the amount of pullback (displacement) of the output member SB before the interruption request is taken into consideration in the time required for reverse drive after the interruption is completed, according to the first return time Tm, so that the output member SB is properly adjusted. position, and excessive pulling back can be reliably suppressed.

<Operation of second identification cancellation process>
The operation of the second identification cancellation process in step S300 will be described with reference to the time series diagram in FIG. In the second specific release process, the electric motor MT is driven in the reverse direction Db at the time when the end of the request for interrupting the release operation is received (the time when the interruption ends). At the same time, a second return time Tn is calculated from the point in time when the interruption ends. Then, when the second return time Tn passes a specific threshold time tn that is shorter than the release threshold time tk, the energization to the electric motor MT is stopped, and the movement of the output member SB is stopped. In the example, the period from time w0 to time w4 corresponds to the activation of the release control, and the period after time w4 corresponds to the activation of the release interruption control. As described above, the permission determination of "Ib≧ik" may be omitted.

Release control is started at time w0. A negative voltage is applied to the electric motor MT, and a reverse energization amount Ib is supplied. Thereby, the electric motor MT is driven in the reverse direction Db. At time w0, the determination flag FF is set to the initial value "0". At time point w1, "Ib≧ik" is established, and contact cancellation determination is permitted. At time point w2, it is determined for the first time that the amount of reverse energization Ib is constant. The duration of this constant state is calculated from time point w2. At a time point w3 when the constant state cancellation duration reaches the determination time th, the contact cancellation state is determined (determined). At time w3 (determined time), the determination flag FF is switched from "0" to "1", and the cancellation continuation time Tk is calculated.

Basically, the release control is terminated when the release duration time Tk reaches the release threshold time tk. However, in the example, interruption of the release operation is requested at time w4 before the release duration time Tk reaches the release threshold time tk. Therefore, at time point w4, release interruption control is started, and energization to electric motor MT is stopped. At time w4 (interruption start time), the cancellation continuation time Tk is once reset, and the value of the cancellation continuation time Tk at this time is stored as the first return time Tm. That is, the first return time Tm is the time from the confirmed time w3 at which the contact-resolved state is established to the interruption start time w4. Then, at time w4, a specific threshold time tn is calculated based on the first return time Tm. The specific threshold time tn is a time shorter than the release threshold time tk, and is calculated so as to become shorter as the first return time Tm becomes longer, according to the calculation map Ztn.

Due to the release interruption control, energization to the electric motor MT is stopped from the time w4 when the start of interruption is received (interruption start time) to the time w5 when the end of the interruption request is received (interruption end time). There is. At time w5, when the interruption request is terminated, the negative voltage is again applied to the electric motor MT, and the reverse energization amount Ib is energized. Thereby, the electric motor MT is driven in the reverse direction Db. Simultaneously with the start of the reverse drive of the electric motor MT, calculation of the second return time Tn is started. If the second return time Tn is less than the specific threshold time tn, the electric motor MT continues to be driven in reverse. Then, at a time point w6 when the second return time Tn becomes equal to or greater than the specific threshold time tn, the reverse drive of the electric motor MT is stopped, and the release interruption control (that is, the second specific release process) is ended.

When the operation interruption request is received after the contact-resolved state is determined, the brake lining BL and the brake drum BD are separated from each other at the end of the interruption. That is, the release operation has progressed to some extent, and the output member SB is being returned to its proper position. The electric motor MT is driven in reverse based on the time from the start of energization (i.e., the second return time Tn), but the threshold value related to that time (i.e., the specific threshold time tn) is calculated in a short time. Therefore, excessive movement of the output member SB is suppressed. Furthermore, in calculating the specific threshold time tn, the first return time Tm is taken into account. That is, the specific threshold time tn is determined to be smaller as the first return time Tm is larger. As a result, the state of movement of the output member SB before the interruption request is taken into account, so the output member SB is returned to an appropriate position.

<Summary and operation/effect of embodiments of electric parking brake device EP>
The embodiments of the electric parking brake device EP will be summarized below. In the electric parking brake device EP, when the electric motor MT is driven in the forward rotation direction Da, the friction member MS is pressed against the rotating member KT provided on the wheel, the parking brake is applied, and the electric motor MT is rotated in the reverse rotation direction. The parking brake is released by driving in the direction Db (opposite to the normal rotation direction Da). The electric parking brake device EP is equipped with a controller ECU that controls the electric motor MT.

In the first embodiment (first processing example of release control + release interruption control), the controller ECU performs release control at a point in time (determined When the release threshold time tk has elapsed from the point in time), the power supply to the electric motor MT is stopped (see FIGS. 3 and 4). In other words, when releasing the parking brake, the release control determines the release threshold time tk from the determined point in time, based on the determined point in time when determining the contact-resolved state in which the rotating member KT and the friction member MS are no longer in contact with each other. The drive of the electric motor MT is stopped when the time period has elapsed.

Further, when the cancellation control is requested to be interrupted by another controller or the like while the cancellation control is being executed, the controller ECU performs the following operation as the cancellation interruption control. In the release interruption control, the drive of the electric motor MT is stopped at the start of the interruption request. Furthermore, in the release interruption control, if there is a request to interrupt the release control before the contact removal state is determined (that is, the interruption start time is before the confirmed time, and the contact removal state has not been determined at the interruption start time). ), "the same control as the release control" (i.e., release control) is executed at the time when the interruption request is terminated (at the end of the interruption request) (step S270 in FIG. 5 and FIG. 6). reference). On the other hand, if there is a request to interrupt the release control after determining the contact-resolved state (that is, if the interruption start point is later than the confirmed point and the contact-resolved state is determined at the time of interruption start), the interruption request is made. After the electric motor MT is driven in the normal rotation direction Da at the end of , "the same control as the release control" (that is, the release control) is executed (see step S280 in FIG. 5 and FIG. 7).

In the electric parking brake device EP, when a request to interrupt the release operation is received from another controller ECA or ECB while the release control is being executed, the power supply to the electric motor MT is immediately stopped. Therefore, a drop in power supply voltage due to rush current in a device (for example, an engine starting device, a speed change control device) including another controller that shares the power source BT, AL with the controller ECU can be suppressed.

In the release control, the starting point is the determined time when the contact-resolved state is determined for the first time, and the control is terminated based on the time Tk (release duration time) from this determined time, and the energization to the electric motor MT is stopped. . Once the power supply to the electric motor MT is stopped while the release control is being executed, the time required for the end of the release control (that is, the starting point of the release duration time Tk) becomes unclear. If there is an interruption request before the contact-resolved state is determined, the contact-resolved state has not yet been determined. Therefore, the cancellation control is executed again at the end of the interruption request (interruption end point). Then, the contact release state is determined, and thereafter, the energization to the electric motor MT is stopped (that is, the release control is ended) based on "Tk≧tk". On the other hand, if there is an interruption request after the contact-resolved state is determined, the electric motor MT is driven in the forward rotation direction Da at the end of the interruption request (interruption end point), and the friction member MS and the rotating member KT are The state is returned to a state in which the contact cancellation is uncertain (that is, a state in which the contact cancellation state has not been determined). Thereafter, after the contact-resolved state is determined (confirmed), energization to the electric motor MT is stopped based on "Tk≧tk". According to the above configuration, since the starting point (determined point) of the release duration Tk is made clear, even if there is an interruption request during release control, the output member SB will be returned to the appropriate position, and the output member SB will not be pulled back excessively. (i.e. excessive displacement) can be avoided.

The controller ECU determines whether "the contact is released or not" based on the forward rotation energization amount Ia supplied to the electric motor MT. For example, the contact-resolved state is determined by comparing the forward energization amount Ia with the threshold energization amount iz, or based on the applied energization change amount dIa (time change amount of the energization amount Ia). When the friction member MS and the rotating member KT come into contact, the load on the electric motor MT increases, so the forward rotation energization amount Ia is increased. Therefore, even if the pressing force Fa (clamping force) of the friction member MS against the rotating member KT is not actually detected, the contact state between the friction member MS and the rotating member KT can be determined based on the change in the forward rotation energization amount Ia. It is possible to understand.

Also in the second embodiment (second processing example of release control + release interruption control), similarly to the first embodiment, the controller ECU causes the release threshold time tk to elapse from the determination point at which the contact release state is determined. At this point, release control is executed to stop driving the electric motor MT. Then, when the cancellation control is requested to be interrupted while the cancellation control is being executed, the cancellation interruption control is executed and the drive of the electric motor MT is stopped. In response to the interruption request, the power supply to the electric motor MT is immediately stopped, so that a drop in the power supply voltage caused by the rush current is suppressed.

In the electric parking brake device EP according to the second embodiment, the controller ECU performs the following operation as release interruption control. If there is a request to interrupt the release control before determining the contact-resolved state, "the same control as the release control" (i.e., release control) is executed at the time when the interruption request is ended (the time when the interruption ends). (See step S270 in FIG. 8 and FIG. 6). On the other hand, if there is an interruption request after determining the contact-resolved state, the electric motor MT is driven in the reverse direction Db from the time the interruption request ends. Then, when a specific threshold time tn shorter than the release threshold time tk has elapsed from the end of the interruption request, the driving of the electric motor MT is stopped.

If there is an operation interruption request after the contact-resolved state is determined, the output member SB has been returned to a certain extent and the friction member MS has already separated from the rotating member KT at the end of the interruption. In the second embodiment, at the end of the interruption request, the electric motor MT is driven in the reverse direction Db, but the driving time is limited to a short time. Specifically, the reverse rotation drive is stopped when a specific threshold time tn has elapsed from the start time, and the specific threshold time tn is set shorter than the release threshold time tk. Therefore, excessive displacement of the output member SB is suppressed.

In the controller ECU, the time from the time when the contact cancellation state is determined to the time when the interruption request is started (interruption start time) is stored as the first return time Tm. Then, it is calculated such that the longer the first return time Tm is, the smaller the specific threshold time tn is. In determining the specific threshold time tn, the amount of movement (displacement) of the output member SB before the interruption request is taken into consideration based on the first return time Tm, so excessive pullback of the output member SB is suitably suppressed. .

<Other embodiments>
Other embodiments of the electric parking brake device EP will be described below. Other embodiments also provide the same effects as described above (quick restart of release operation, suppression of excessive movement of output member SB, etc.).

In the above embodiment, the operation of the electric parking brake device EP in response to the operation of the parking switch SW (application control in response to an application instruction/release control in response to a release instruction) has been described. The instruction to apply/release the electric parking brake device EP may be automatically issued instead of operating the parking switch SW. A situation in which the electric parking brake device EP is automatically activated is referred to as an "automatic mode." In the automatic mode, for example, when the vehicle stops, the electric parking brake device EP is automatically instructed to apply, and the parking braking force Fp is generated (applied). Furthermore, when the driver operates an acceleration operating member (such as an accelerator pedal) and the operating amount Ap increases from "0 (zero)," the electric parking brake device EP is automatically instructed to release. The automatic mode is executed using the vehicle speed Vx and acceleration operation amount Ap acquired by the controller ECU via the communication bus BS.

In a vehicle equipped with an automatic braking device, the automatic mode of the electric parking brake device EP may be executed without any operation by the driver. For example, to assist driving during traffic jams, the vehicle speed Vx is automatically adjusted by detecting a preceding vehicle. Then, when the preceding vehicle stops, the vehicle automatically stops while maintaining the following distance, an application instruction is automatically given, and the electric parking brake system EP is applied. Thereafter, when the preceding vehicle starts moving, a release instruction is automatically issued, the electric parking brake device EP is released, and the vehicle speed Vx of the own vehicle is adjusted so as to follow the preceding vehicle.

In the embodiment described above, a drum type brake was employed as the braking device DB. Instead, a disc brake may be employed as the braking device DB. In the disc type brake, a brake pad is used as the friction member MS, and a brake disc is used as the rotating member KT.

EP...electric parking brake device, BT...storage battery (power supply), AL...generator (power supply), ECA, ECB...other controllers, FK...request flag (control flag for requesting interruption of release operation), FF...judgment flag (control flag for contact cancellation determination), SW...parking switch, BS...communication bus, DB...braking device, KT...rotating member, BD...brake drum (an example of rotating member KT), MS...friction member, BL...brake Lining (an example of friction member MS), BSa, BSb...brake shoe, ST...shoe strut, CB...parking cable, PL...parking lever, BP...backing plate, DN...electric actuator, MT...electric motor, GS...reducer , NB...input member, SB...output member, MD...rotating member, EN...end member, ECU...controller (for electric parking brake device), MP...microprocessor, DR...drive circuit, IA...current flow sensor (e.g. , current sensor), Ia...Forward rotation energization amount (energization amount corresponding to the forward rotation direction Da), Ib...Reverse rotation energization amount (the energization amount corresponding to the reverse rotation direction Db), Tk...Cancellation duration time, Tm...First return Time, Tn...second return time, tk...release threshold time, tn...specific threshold time.

Claims (2)

A vehicle in which an electric motor is driven in a forward direction to press a friction member against a rotating member provided on a wheel of the vehicle to apply a parking brake, and the electric motor is driven in a reverse direction to release the parking brake. An electric parking brake device,
comprising a controller for controlling the electric motor;
The controller includes:
When releasing the parking brake, a release control is executed to stop driving the electric motor when a release threshold time has elapsed from the time when a contact release state in which the rotating member and the friction member are no longer in contact is determined. At the same time,
If interruption of the release control is requested while the release control is being executed, driving of the electric motor is stopped;
The controller includes:
If the request is made before the contact cancellation state is determined, the release control is executed at the end point when the request is ended;
The electric parking brake device for a vehicle is configured to execute the release control after driving the electric motor in the normal rotation direction at the end time when the request is made after determining the contact release state. A vehicle in which an electric motor is driven in a forward direction to press a friction member against a rotating member provided on a wheel of the vehicle to apply a parking brake, and the electric motor is driven in a reverse direction to release the parking brake. An electric parking brake device,
comprising a controller for controlling the electric motor;
The controller includes:
When releasing the parking brake, a release control is executed to stop driving the electric motor when a release threshold time has elapsed from the time when a contact release state in which the rotating member and the friction member are no longer in contact is determined. At the same time,
If interruption of the release control is requested while the release control is being executed, driving of the electric motor is stopped;
The controller includes:
If the request is made before the contact cancellation state is determined, the release control is executed at the end point when the request is ended;
If the request is made after determining the contact release state, the electric motor is driven in the reverse direction from the end point, and a specific threshold time shorter than the release threshold time has elapsed from the end point. An electric parking brake device for a vehicle that stops driving the electric motor at a certain point in time.