JP6502172B2 - Electric brake device - Google Patents

Description

  The present invention relates to an electric brake system, and relates to a technology for estimating a coil temperature by constructing a static condition using a current intermediate to a hysteresis characteristic of an actuator.

The following techniques have been proposed as an electric brake device using an electric motor.
1. By depressing the brake pedal, the rotational movement of the electric motor is converted into linear movement via a linear movement mechanism, and the brake pad is pressed against the brake disc to apply a braking force (Japanese Patent Application Laid-Open No. 2001-147118).
2. An electric brake device using a planetary roller screw mechanism (Patent Document 2).
3. The technique which provides a thermistor in the neutral point terminal of each phase coil in an electric motor, and measures the average temperature of each phase coil by this thermistor (patent document 3).
4. A technology for estimating coil temperature from temperature characteristics of voltage and current and copper resistance when the electric motor is in a stopped state (Patent Document 4).

Unexamined-Japanese-Patent No. 6-327190 Unexamined-Japanese-Patent No. 2006-194356 Unexamined-Japanese-Patent No. 11-234964 JP 2004-208453 A

  In the electric brake device as described in Patent Documents 1 and 2, when an abnormality occurs in the coil of the electric motor, there is a possibility that the brake function may be reduced. This electric motor has a very limited mounting space for the vehicle, and there is a problem that an increase in unsprung weight of the vehicle due to an increase in the size of the electric motor causes deterioration of the riding comfort of the occupant. For this reason, it may be difficult to design to reduce the copper loss of the motor coil to reduce the amount of heat generation.

In order to avoid the above situation, temperature control of the motor coil is required, and for that purpose it is necessary to estimate the motor coil temperature with high accuracy. For example, as shown in Patent Document 4, there is a method of estimating the motor coil temperature by using the temperature dependency of the resistance value of copper.
However, in order to remove the influence of the inductance, the induced voltage coefficient, etc. in which accurate modeling is difficult under the situation where the frequency band of the input voltage is difficult to define, the predetermined voltage input and the angular velocity of the motor are approximately zero. A certain state must be maintained for a predetermined time. Therefore, it may be difficult to implement the coil temperature estimation function of Patent Document 4 in an electric brake control system that must follow an arbitrary brake target command.

  In general, in the case of an electric brake system, the inertia of the electric motor is often extremely small in order to reduce the mounting space for the vehicle and to improve the frequency response. In this case, even in a situation where the electric motor can be brought into a stationary state, the angular velocity rises instantaneously with respect to a slight torque input, so it may be difficult to maintain a strict stationary state. If it is attempted to maintain a strict stationary state, the occupants of the vehicle may feel discomfort and may adversely affect the vehicle behavior.

As a method which is not affected by the above, for example, a countermeasure as shown in Patent Document 3 in which a temperature sensitive element such as a thermistor is disposed on a motor coil is generally used.
However, it may be disadvantageous in terms of motor size and assembly cost. Further, for example, in a servomotor of a system such as an electric actuator used for a brake, the current may be concentrated on a predetermined coil to cause heat generation to be biased, and an accurate coil temperature may not be detected. At this time, in the measure to measure the average temperature of each coil as in Patent Document 3, there is a possibility that the system may stop in a state where the heat load still has a margin, and conversely, the specific coil temperature rises too much. There is a possibility of

  An object of the present invention is to provide an electric brake system capable of reducing the influence on the vehicle behavior and detecting the motor coil temperature with high accuracy in detecting the motor coil temperature.

The electric brake device of the present invention comprises a brake rotor 8, a friction member 9 brought into contact with the brake rotor 8, a friction member operating means 6 bringing the friction member 9 into contact with the brake rotor 8, and the friction member operation means 6. The electric motor 4 for driving the motor, the current estimation means 22 for estimating the current of the electric motor 4, and the estimated braking force which is the estimated value of the braking force generated by pressing the friction member 9 against the brake rotor 8 In an electric brake device DB comprising a braking force estimation means 28 and a control device 2 for controlling the electric motor 4 to follow the estimated braking force against a target braking force,
The control device 2 is
Regarding the reaction force of the pressing force of the friction member operating means 6 during the driving of the electric motor 4, the reaction force based on the positive efficiency in the operation to increase the braking force and the reaction force based on the reverse efficiency in the operation to decrease the braking force Hysteresis estimation function means 24 for estimating a hysteresis characteristic having
Static condition constructing means 25 for constructing a static condition by applying a current corresponding to the positive efficiency side and the reverse efficiency side of the hysteresis characteristic to the electric motor 4 for a predetermined time;
From the relationship between the voltage of the electric motor 4 for which the time set by the static condition construction means 25 has elapsed and the current estimated by the current estimation means 22, the coil of the electric motor 4 is determined according to the defined conditions And temperature estimation means 19 for estimating the temperature.
The static condition refers to a state in which the angular velocity of the electric motor is an extremely small value of zero to substantially zero. The predetermined value, the predetermined time, and the predetermined condition are respectively determined by results of tests and simulations.

The frictional force acting on the electric brake device DB changes the direction of the frictional drag with respect to the change in the rotational direction at pressure increase and pressure decrease, so that hysteresis characteristics occur.
According to this configuration, the hysteresis estimating function means 24 estimates the hysteresis characteristic while the electric motor 4 is driven. The static condition constructing means 25 applies a current corresponding to between the positive efficiency side and the reverse efficiency side of the hysteresis characteristic to the electric motor 4 for a predetermined time to construct a static condition. The temperature estimation means 19 uses the electric motor according to the conditions determined from the relationship between the voltage of the electric motor 4 for which the predetermined time has elapsed and the current estimated by the current estimation means 22 (referred to as "estimated current"). Estimate the coil temperature of 4.

  As described above, the electric motor in the electric brake is made strict by utilizing the current in the middle of the hysteresis characteristic which can maintain the braking force constant in a state where the electric motor angular velocity is substantially zero even while the electric motor 4 is being driven. The coil temperature can be accurately estimated, as opposed to the prior art, which is difficult to maintain at rest. Further, since the motor current can also be made constant by the above, the coil temperature can be accurately estimated with respect to the prior art which is affected by the error of the inductance.

The temperature estimation unit 19 determines that the absolute value of the change amount of the target braking force is equal to or less than a predetermined value, and the deviation between the target braking force and the estimated braking force is equal to or less than a set value. The coil temperature may be estimated when
The predetermined value and the setting value are respectively determined by the results of tests and simulations.

  In this case, when the absolute value of the change amount of the target braking force satisfies the predetermined value or less, the static condition of the electric brake device DB can be more surely satisfied. By satisfying the condition that the deviation between the target braking force and the estimated braking force is less than or equal to the set value, it can be determined that the braking force follows the target braking force. By estimating the coil temperature after satisfying these conditions, the motor coil temperature can be estimated more accurately. In addition, in the situation where there is a demand for maintaining the braking force substantially constant as described above, by performing the above-mentioned coil temperature estimation, it is possible to reduce the influence on the vehicle behavior without the occupant of the vehicle feeling discomfort. .

The temperature estimation means 19
A time measurement unit 29 which measures an elapsed time from a state in which follow-up control of the estimated braking force to the target braking force is started after the coil temperature is estimated by the temperature estimating means 19;
A temperature estimation non-execution unit 30 that does not execute the estimation of the coil temperature until the elapsed time measured by the time measurement unit 29 reaches the set time;
May be included.
The set time is determined by the result of a test or simulation.

  It is conceivable that the coil temperature hardly changes until the elapsed time from the state where tracking control is started reaches the set time after the coil temperature is once estimated. Therefore, estimation of the coil temperature is intentionally not performed until the elapsed time measured by the time measurement unit 29 reaches the set time. In other words, the coil temperature is not frequently estimated. Thereby, the load of arithmetic processing can be reduced.

  The temperature estimation unit 19 may include a set time changing unit 31 that changes the set time based on a correlation in which the set time of the elapsed time decreases as the estimated braking force increases. The setting time changing unit 31 can perform the estimation control of the coil temperature finely in detail by changing the setting time which is a reference of whether to execute the estimation of the coil temperature according to the estimated braking force.

The temperature estimation means 19
A time measurement unit 29 which measures an elapsed time from a state in which follow-up control of the estimated braking force to the target braking force is started after the coil temperature is estimated by the temperature estimating means 19;
When the elapsed time measured by the time measuring unit 29 reaches a set time or more, and at least one of the estimated braking force and the current estimated by the current estimating means 22 is a predetermined value or more, the coil temperature A temperature estimation execution unit 32 that forcibly executes the estimation of
May be included.
The set time and the set value are determined by results of tests and simulations, respectively.

  According to this configuration, the temperature estimation execution unit 32 detects the coil when the elapsed time measured by the time measurement unit 29 reaches the set time or more and at least one of the estimated braking force and the estimated current is a predetermined value or more. Force the temperature estimation. Under such conditions, the coil temperature may be increased excessively.

  The electric brake device according to the present invention comprises a brake rotor, a friction member brought into contact with the brake rotor, friction member operating means for bringing the friction member into contact with the brake rotor, and an electric motor for driving the friction member operation means. Controlling the electric motor, current estimation means for estimating the current of the electric motor, braking force estimation means for obtaining an estimated braking force which is an estimated value of the braking force generated by pressing the friction member against the brake rotor; And a controller for performing tracking control of the estimated braking force with respect to the target braking force. With regard to the reaction force of the pressing force of the friction member operating means during the drive of the electric motor, the control device is a reaction force based on the positive efficiency in the operation for increasing the braking force and a reverse efficiency in the operation for reducing the braking force. A hysteresis estimation function means for estimating a hysteresis characteristic having a reaction force based thereon, and applying a current corresponding to a distance between the positive efficiency side and the reverse efficiency side of the hysteresis characteristic to the electric motor for a predetermined time. Determined from the relationship between static condition constructing means for constructing a condition, the voltage of the electric motor for which the time set by the static condition constructing means has elapsed, and the current estimated by the current estimation means Temperature estimation means for estimating the coil temperature of the electric motor according to the conditions. Therefore, with regard to detecting the motor coil temperature, the influence on the vehicle behavior can be reduced, and the motor coil temperature can be accurately estimated.

It is a block diagram of a control system of an electric servo system concerning an embodiment of this invention. It is a figure showing roughly the electric brake equipment of the electric servo system. It is a figure which shows the hysteresis characteristic of the electric actuator of the same electric brake device. It is a flowchart which performs estimation of motor coil temperature of the same electric brake device. It is a figure which shows transition of the brake force and motor current of the same electric brake device. It is a figure which shows transition of the brake force and motor current of the same electric brake device.

An electric brake system of an electric servo system according to an embodiment of the present invention will be described with reference to FIGS. 1 to 6.
As shown in FIG. 1, the electric servo system includes a plurality of electric brake devices DB, a power supply device 3, and a host ECU 17. Each of the electric brake devices DB includes an electric actuator 1 and a control device 2. First, the electric actuator 1 will be described.

  As shown in FIG. 2, the electric actuator 1 includes an electric motor 4, a reduction mechanism 5 for decelerating the rotation of the electric motor 4, a direct acting mechanism 6 as friction member operating means, and a parking brake mechanism as a parking brake. 7, a brake rotor 8 and a friction member 9. The electric motor 4, the reduction mechanism 5, and the linear movement mechanism 6 are incorporated into, for example, a housing or the like not shown. The electric motor 4 comprises a three-phase synchronous motor or the like.

  The speed reduction mechanism 5 is a mechanism that transmits the rotation of the electric motor 4 to the tertiary gear 11 fixed to the rotating shaft 10 by decelerating and includes the primary gear 12, the intermediate gear 13, and the tertiary gear 11. In this example, the reduction mechanism 5 reduces the rotation of the primary gear 12 attached to the rotor shaft 4 a of the electric motor 4 by the intermediate gear 13, and the tertiary gear 11 fixed to the end of the rotating shaft 10. Transmission is possible.

  The linear motion mechanism 6, which is a friction member operating means, converts the rotational motion output from the reduction mechanism 5 into a linear motion of the linear motion portion 14 by the feed screw mechanism, and abuts the friction member 9 against the brake rotor 8. It is a mechanism to separate. The linear motion portion 14 is detentated and supported movably in the axial direction indicated by the arrow mark A1. A friction member 9 is provided at the outboard side end of the linear movement portion 14. By transmitting the rotation of the electric motor 4 to the linear motion mechanism 6 via the reduction mechanism 5, the rotational motion is converted into a linear motion, which is converted into the pressing force of the friction member 9. Generates the braking force which is the axial force of In the state where a plurality of electric motor devices DB (FIG. 1) are mounted on a vehicle, the outside of the vehicle is referred to as the outboard side, and the center side of the vehicle is referred to as the inboard side.

  As an actuator 16 of the parking brake mechanism 7, for example, a linear solenoid is applied. The locking member (solenoid pin) 15 is advanced by the actuator 16 and fitted into a locking hole (not shown) formed in the intermediate gear 13 for locking thereby inhibiting rotation of the intermediate gear 13. , Parking lock state. By disengaging the lock member 15 from the locking hole, the rotation of the intermediate gear 13 is allowed to be in the unlocked state.

  As shown in FIG. 1, the control device 2 of each of the electric brake devices DB is connected to the power supply device 3 and a host ECU 17 which is a higher control means of each of the control devices 2. In FIG. 1, only the control device 2 and the electric actuator 1 in one electric brake device DB are shown, and illustration of the other electric brake devices is omitted. For example, an electric control unit that controls the entire vehicle is applied as the host ECU 17. The host ECU 17 also has an integrated control function of each of the electric brake devices DB. For example, a target value command (target braking force) such as a braking force is input from the host ECU 17 to the control computing unit 18 of the control device 2.

The power supply device 3 supplies electric power to the electric motor 4 and the control device 2 in each of the electric brake devices DB.
The control device 2 includes a control computing unit 18, a coil temperature estimator 19 as temperature estimation means, a motor driver 21, and a current sensor 22 as current estimation means. The control computing unit 18 and the coil temperature estimator 19 may be implemented by, for example, a processor such as a microcomputer or a hardware module such as an ASIC, an FPGA, or a DSP.

  The control computing unit 18 includes a control computing function unit 23, a hysteresis estimating function unit 24, a static condition constructing unit 25, and a current limiting unit 26. The control calculation function unit 23 generates a control signal of the motor driver 21 from the values of various sensors so as to achieve the control target from the host ECU 17. At this time, it is preferable that the current limiting means 26 execute a process of protecting the exciting coil 4a from heat generation according to the estimation result of the coil temperature estimator 19 with reference to the estimation result.

  The heat generation protection by the current limiting means 26 may be a process of limiting the current upper limit value according to the estimated temperature of the coil temperature estimator 19 described later, and the operation of the electric motor 4 is stopped when the estimated temperature exceeds a predetermined value. It is good also as processing to do. In the process of limiting the current upper limit value, it is necessary for the control computing unit 18 to execute arithmetic processing, but it is possible to prevent the electric motor 4 from being undesirably stopped from driving. The process of stopping the operation of the electric motor 4 can perform this process simply and reliably. The process of limiting the current upper limit value may be used in combination with the process of stopping the operation.

  The motor driver 21 converts DC power of the power supply 3 into three-phase AC power used for driving the electric motor 4. The motor driver 21 may form, for example, a half bridge circuit using a switch element such as a MOSFET. Further, the motor driver 21 may include a pre-driver that drives the switch element instantaneously.

  The current sensor 22 is a current detection unit that obtains the current flowing through the three-phase excitation coil 4a. The current sensor 22 is one of the various sensors, and may use, for example, a current sensor that detects a magnetic field generated around the power transmission path, and detects a voltage drop amount using a shunt resistor and an operational amplifier. A current sensor may be used. When the current sensor that detects the magnetic field is used, the current sensor that detects the voltage drop amount with high efficiency and high accuracy can be mounted at low cost. Further, in measuring the three-phase current, for example, the current may be measured only in any two of the three phases, and the remaining one phase may be obtained using the characteristic that the total sum of the three-phase currents is zero.

  The electric motor 4 is suitable for an electric servo system in which a brushless DC motor including an excitation coil 4a, a rotor angle sensor 27, and a rotor (not shown) having permanent magnets is compatible with high speed, small size and high precision. It is. The excitation coil 4a may be a concentrated winding which is concentrated on one tooth and may be a distributed winding across a plurality of teeth. By comparing the two, concentrated windings can be miniaturized, and distributed windings can be made to have high efficiency and low torque ripple.

  As the rotor angle sensor 27, for example, a sensor such as a resolver or a magnetic encoder may be mounted on the electric motor 4, and the rotor angle may be estimated without so-called sensor using a coil voltage during rotation. When a sensor such as a magnetic encoder is used, it is possible to detect the rotor angle with high accuracy from low speed to stop, and it is advantageous to save space when sensorless estimation of the rotor angle.

  The braking force of the electric brake device DB is estimated by the braking force estimation means 28. The braking force estimation means 28 is a braking force that is actually generated from the characteristics of the electric actuator 1 and the detected value obtained by sensing the influence of the electric braking device DB itself or the wheels generated by the operation of the electric braking device DB. Any means that can estimate the In addition, the brake force estimation means 28 may be, for example, a load sensor that detects the load of the electric actuator 1.

  For example, a magnetic sensor is applied to the load sensor. As shown in FIG. 2, when the friction member 9 presses the brake rotor 8, a reaction force to the inboard side acts on the linear movement portion 14. A load sensor formed of a magnetic sensor magnetically detects the reaction force of the braking force as an axial displacement amount. As shown in FIG. 1, the braking force estimation means 28 sets the braking force based on the sensor output of the load sensor by setting in advance the relationship between the reaction force of the braking force and the sensor output in a test or the like. It can be estimated. In addition, it is also possible to apply an optical sensor other than a magnetic sensor, an eddy current sensor, or a capacitance sensor as the load sensor.

  In this embodiment, in particular, as shown in FIG. 1, the control device 2 is provided with a coil temperature estimator 19, and the control computing unit 18 is provided with hysteresis estimation function means 24 and static condition construction means 25. Hysteresis estimation function means 24 estimates the hysteresis characteristics of the electric actuator 1. The hysteresis characteristic is based on the reaction force based on the positive efficiency in the operation of increasing the braking force and the reverse efficiency in the operation of reducing the braking force with respect to the reaction force of the pressing force of the linear motion mechanism 6 while the electric motor 4 is driven. And a reaction force.

  Here, FIG. 3 is a diagram showing the hysteresis characteristic of this electric actuator. Hereinafter, description will be made with reference to FIGS. 1 and 2 as appropriate. The horizontal axis of FIG. 3 represents torque, which generally corresponds to motor torque or current. The vertical axis in FIG. 3 indicates the pressing force generated by the electric actuator 1 (FIG. 1), and if the coefficient of friction μ between the friction member 9 (FIG. 2) and the brake rotor 8 (FIG. 2) is constant, The pressing force corresponds to, for example, the braking force in the electric brake device.

  The direction of the frictional drag with respect to the change in the rotational direction of the electric motor 4 at pressure increase and decrease is changed mainly by the friction force acting on the electric actuator 1 (FIG. 1). It occurs. For example, the motor current at the time of holding the braking force constant generally corresponds to the current between the positive efficiency and the reverse efficiency (indicated by hatching in FIG. 3) in the hysteresis characteristic shown in FIG.

  As shown in FIG. 1, the static condition constructing means 25 applies a current corresponding to a distance between the positive efficiency side and the reverse efficiency side of the hysteresis characteristic to the electric motor 4 for a predetermined time to set static conditions. To construct. The predetermined time is set, for example, to several milliseconds to several tens of milliseconds according to the results of tests, simulations and the like.

The coil temperature estimator 19 calculates the electric motor according to the condition determined from the relationship between the voltage of the electric motor 4 for which the time determined by the static condition constructing means 25 has elapsed and the estimated current estimated by the current sensor 22. The coil temperature at 4 is estimated. The voltage of the electric motor 4 may use the output value according to the control calculation result as it is, or the voltage of the electric motor 4 may be directly measured. From the voltage and current described above, the estimated temperature of each phase is derived based on, for example, the following relational expression.
R (k) = V (k) / I (k)
t = (R (k) -R _o ) / (R _o · α)
t: Estimated temperature V (k): Voltage I (k): Current R _o : Reference resistance α: Temperature resistance coefficient The motor voltage is an AC voltage to each phase of UVW, but as mentioned above, the electric motor is completely When stationary, it is a DC voltage.

  In principle, coil temperature estimator 19 determines that the absolute value of the amount of change in the target braking force given from host ECU 17 is equal to or less than a predetermined value, and that the target braking force and the estimated braking force When the deviation is below the set value, the coil temperature is estimated. The coil temperature estimator 19 includes a time measurement unit 29, a temperature estimation non-execution unit 30, a set time change unit 31, and a temperature estimation execution unit 32. After the coil temperature is estimated by the coil temperature estimator 19, the time measuring unit 29 measures an elapsed time from a state in which follow-up control of the estimated braking force to the target braking force is started.

  The temperature estimation non-execution unit 30 does not execute the estimation of the coil temperature until the elapsed time measured by the time measurement unit 29 reaches the set time. It is conceivable that the coil temperature hardly changes until the elapsed time from the state where tracking control is started reaches the set time after the coil temperature is once estimated. Therefore, estimation of the coil temperature is intentionally not performed until the elapsed time measured by the time measurement unit 29 reaches the set time. In other words, the coil temperature is not frequently estimated until the elapsed time to be measured reaches the set time.

  The set time changing unit 31 changes the set time based on the correlation in which the set time in the elapsed time decreases as the estimated brake force estimated by the brake force estimating means 28 increases. As described above, the setting time changing unit 31 performs the estimation control of the coil temperature finely by changing the setting time which is a reference of whether to perform the estimation of the coil temperature according to the estimated braking force.

  The temperature estimation execution unit 32 has one of the estimated braking force estimated by the braking force estimating means 28 and the estimated current estimated by the current sensor 22 when the elapsed time measured by the time measuring unit 29 reaches the set time or more. When one or both of the values are equal to or greater than a predetermined value, estimation of the coil temperature is forcibly executed regardless of the target brake force and the value of the change amount of the target brake force. When such a condition is satisfied, estimation of the coil temperature is forcibly executed regardless of the target brake force or the like. Under such conditions, the coil temperature may be increased excessively.

FIG. 4 is a flowchart for performing the estimation of the motor coil temperature of the electric brake device. After the process starts, the control computing unit 18 acquires the target braking force F _r (step S1), and acquires the estimated braking force F _b (step S2). Next, the control computing unit 18 determines whether this control is in the current control mode or the braking force control mode (step S3). If it is determined that the braking force control mode is in effect, the process proceeds to step S19. If it is determined that the current control mode is set, the process _proceeds to step S4, and the control computing unit 18 determines whether the elapsed time of current control, that is, the elapsed time n _ci from the state where tracking control is started, is _{equal to} or greater than a predetermined value _nith. judge. If the elapsed time _{n ci} is the predetermined value _{n i @ th} or more (step S4: yes), the control arithmetic unit 18, thereby estimating the coil temperature to the coil temperature estimator 19 (step S5). Thereafter, the process proceeds to step S19.

If the elapsed time _{n ci} is less than the predetermined value _{n i @ th} (Step S4: no), the control arithmetic unit 18, counts continuously the elapsed time _{n ci} by adding the counter is the time measuring section 29 ( Step S7). After that, the control computing unit 18 estimates a current corresponding to between the positive efficiency side and the reverse efficiency side (between the hysteresis) of the hysteresis characteristic in the current braking force (step S11). The static condition constructing means 25 of the control computing unit 18 controls the motor current to the current estimated in the step S11 (step S13). At this time, the control system in step S13 must be a stable control system in which the motor current and the motor voltage which is the manipulated variable converge to a predetermined value in a finite time, and such a control system is It is also suitable for brake force control. After step S13, the present process is terminated.

  In step S19, the temperature estimation execution unit 32 of the coil temperature estimator 19 determines whether or not the estimation of the coil temperature is forcibly performed. If the mode (Step S19) for forcibly measuring the coil temperature is provided even when the determination does not correspond to the determinations in steps S6, S8, and S15, the heat load of the motor coil 4a is not estimated without the estimation of the coil temperature. It is considered preferable because the situation beyond the limit can be prevented. When it corresponds to the above, for example, the case where monotonous increase and monotonous decrease of target brake force are continued for a long time etc. can be considered.

If the condition for forcibly measuring the coil temperature is satisfied (step S19: yes) and switching from the braking force control to the current control mode occurs, the process proceeds to step S11. If the condition for forcibly measuring the coil temperature is not satisfied (step S19: no), the coil temperature estimator 19 determines whether the absolute value of the change amount of the target braking force F _r is equal to or less than a _{predetermined} value F _rth It is determined whether or not it is (step S6).

The coil temperature estimator 19 determines that the absolute value of the change amount of the target braking force F _r is equal to or less than the _{predetermined} value F _rth (step S6: yes), and the target braking force F _r and the estimated braking force F _b If it is determined that the deviation is less than or equal to the set value F _ath (step S8: yes), the control computing unit 18 determines whether the elapsed time n _cf from the state where follow-up control is started is more than a predetermined value n _fth (step S15). If this determination is true (step S15: yes), the process proceeds to step S9.

If it does not correspond to the determinations in steps S6, S8 and S15, the control computing unit 18 determines whether this control is in the current control mode or the braking force control mode (step S18). If it is in the current control mode, the control computing unit 18 clears the counters that measure the elapsed times n _ci and n _cf of the current control (steps S16 and S17). Thereafter, brake force control is executed via step S12 (step S14). Thereafter, the process ends. In step S18, in the case of the continued braking force control mode, the control computing unit 18 adds a counter for brake force control mode continuation determination (step S10). Next, the process proceeds to step S12.

5 and 6 are diagrams showing the transition of the braking force and the motor current of the electric brake device, respectively. In FIG. 5, the target braking force _Fr is changed with the passage of time, and the constant target braking force _Fr is shifted for a predetermined time. At this time, the actual braking force F _b (or estimated braking force F _b ) follows the target braking force F _r . In this example, as indicated by the dotted line in the figure, the coil temperature estimator 19 estimates the coil temperature when the constant target braking force F _r shifts for a predetermined time.

In FIG. 6A, after the coil temperature is estimated by the coil temperature estimator 19 (indicated by the dotted line in FIG. 6), the coil temperature is estimated until the elapsed time measured by the time measurement unit 29 reaches the set time. An example not to execute is shown. By not estimating the coil temperature so frequently as this, the load of arithmetic processing can be reduced.
FIG. 6B shows an example in which the coil temperature estimator 19 forcibly executes the coil temperature. Specifically, when the elapsed time measured by time measuring unit 29 reaches the set time or more and at least one of the estimated braking force and the estimated current is a predetermined value or more, temperature estimation execution unit 32 determines the coil. Force the temperature estimation. Under such conditions, the coil temperature may be increased excessively.

  According to the electric brake device DB described above, by utilizing the intermediate current of the hysteresis characteristic which can maintain the braking force constant in a state where the electric motor angular velocity is substantially zero even while the electric motor 4 is being driven. The coil temperature can be estimated accurately, as opposed to the prior art, where it is difficult to maintain the electric motor in the electric brake in strict static condition. Further, since the motor current can also be made constant by the above, the coil temperature can be accurately estimated with respect to the prior art which is affected by the error of the inductance.

  In principle, in coil temperature estimator 19, the absolute value of the change amount of the target braking force given from host ECU 17 is equal to or less than the defined value, and the deviation between the target braking force and the estimated braking force is equal to or less than the set value. When the coil temperature is estimated. By satisfying the condition that the absolute value of the change amount of the target braking force is equal to or less than a predetermined value, the static condition of the electric brake device DB can be more surely satisfied. By satisfying the condition that the deviation between the target braking force and the estimated braking force is less than or equal to the set value, it can be determined that the braking force follows the target braking force. By estimating the coil temperature after satisfying these conditions, the motor coil temperature can be estimated more accurately.

Another embodiment will be described.
An operation may be provided to estimate the coil temperature or forcibly invalidate the current control mode. For example, when only a weak brake operation is performed, it is difficult to think of a case where the motor temperature is rising. In addition, in the situation where high precision brake force control is required, such as during antilock control, the above coil temperature may not be estimated.
As the electric motor, for example, a DC motor or a stepping motor using a brush or a slip ring may be applied.
The direct acting mechanism may be a mechanism such as a planetary roller screw or a ball lamp.

  The vehicle equipped with this electric brake device may be an electric car that drives driving wheels by a motor, or a hybrid car that drives one of the front and rear wheels by an engine and the other by a motor. In addition, an engine car that drives driving wheels with only an engine may be applied to the vehicle. The type of brake may be a disc brake type or a drum brake type.

  As mentioned above, although the form for implementing this invention was demonstrated based on embodiment, embodiment disclosed this time is an illustration and restrictive at no points. The scope of the present invention is indicated not by the above description but by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

2 ... Control device 4 ... Electric motor 6 ... Linear motion mechanism (friction member operation means)
8 ... brake rotor 9 ... friction member 19 ... coil temperature estimator (temperature estimation means)
22 ... Current sensor (current estimation means)
24 ... hysteresis estimation function means 25 ... static condition construction means 28 ... braking force estimation means 29 ... time measurement unit 30 ... temperature estimation non-execution unit 31 ... setting time change unit 32 ... temperature estimation execution unit

Claims (5)

A brake rotor, a friction member to be brought into contact with the brake rotor, a friction member operating means for bringing the friction member into contact with the brake rotor, an electric motor for driving the friction member operation means, and a current of the electric motor A current estimation means, a braking force estimation means for obtaining an estimated braking force which is an estimated value of a braking force generated by pressing the friction member against the brake rotor, a target brake for controlling the estimated braking force by controlling the electric motor In an electric brake device comprising a control device for following and controlling force,
The controller is
The reaction force based on the positive efficiency in the operation of increasing the braking force, and the reaction force based on the reverse efficiency in the operation of reducing the braking force, of the reaction force of the pressing force of the friction member operating means during driving of the electric motor Hysteresis estimation function means for estimating hysteresis characteristics that it has;
Static condition constructing means for constructing a static condition by applying a current corresponding to the positive efficiency side and the reverse efficiency side of the hysteresis characteristic to the electric motor for a predetermined time;
The coil temperature of the electric motor is estimated according to the determined condition from the relationship between the voltage of the electric motor after the determined time has elapsed by the static condition constructing means and the current estimated by the current estimating means. Temperature estimation means,
An electric brake device characterized by having.   The electric brake device according to claim 1, wherein the temperature estimation unit determines that the absolute value of the change amount of the target braking force is equal to or less than a predetermined value as the determined condition, and the target braking force and the target braking force. An electric brake system for estimating the coil temperature when the deviation of the estimated braking force is equal to or less than a set value. The electric brake device according to claim 1, wherein the temperature estimation unit is
A time measurement unit that measures an elapsed time from a state in which follow-up control of the estimated braking force to the target braking force is started after the coil temperature is estimated by the temperature estimating means;
A temperature estimation non-execution unit that does not execute the estimation of the coil temperature until the elapsed time measured by the time measurement unit reaches the set time;
And an electric brake device.   The electric brake device according to claim 3, wherein the temperature estimation unit changes a setting time changing unit that changes the setting time based on a correlation that the setting time of the elapsed time decreases as the estimated braking force increases. Electric brake device. The electric brake device according to any one of claims 1 to 4, wherein the temperature estimation unit is
A time measurement unit that measures an elapsed time from a state in which follow-up control of the estimated braking force to the target braking force is started after the coil temperature is estimated by the temperature estimating means;
The coil temperature is estimated when the elapsed time measured by the time measuring unit reaches a set time or more, and at least one of the estimated braking force and the current estimated by the current estimating means is greater than or equal to a predetermined value. A temperature estimation execution unit that forcibly executes
And an electric brake device.

Images