JP7625906B2 - Vehicle Brake Device - Google Patents

Description

The present invention relates to a vehicle braking system.

A known vehicle braking device uses drum brakes, as described in JP 2002-67914 A, for example. In this vehicle braking device, a load sensor is provided on the anchor body to calculate the braking force. With this configuration, the actual braking force can be calculated with high accuracy by detecting the contact load between the brake shoe and the anchor body.

JP 2002-67914 A

In the above vehicle braking device, the anchor body is arranged at the bottom inside the wheel due to its configuration. Therefore, the load sensor installed on the anchor body is also arranged at the bottom inside the wheel. In this arrangement, the wiring for the load sensor must be routed so as to run vertically through the wheel, which can easily make the layout of the wiring that passes between moving parts such as the hub, brake shoe, and arm complicated.

The object of the present invention is to provide a vehicle braking device that can reduce the complexity of wiring without reducing the accuracy of braking force detection.

The vehicle braking device of the present invention comprises a brake rotor that rotates together with the wheel, a friction member that is pressed against the brake rotor during braking, a torque receiving portion that applies a braking force to the wheel by preventing rotation of the friction member, a fixed portion that houses a linear motion conversion portion and is fixed to the torque receiving portion, and a drive device having a movable portion that drives the friction member to press it against the brake rotor, a load sensor installed on the fixed portion and detects a force applied to the fixed portion, and a calculation portion that calculates the braking force based on the detection value of the one load sensor , wherein the friction member comprises a first friction member and a second friction member, and the first friction member and the second friction member are connected by an adjuster that is displaceable relative to the torque receiving portion.
a torque receiving portion that applies a braking force to the wheel by preventing rotation of the friction member; a fixed portion that accommodates a linear motion conversion portion and is fixed to the torque receiving portion, and a drive device having a movable portion that drives the friction member to press it against the brake rotor; a load sensor that is installed on the fixed portion and detects a force applied to the fixed portion; and a calculation portion that calculates the braking force based on a detection value of the one load sensor, wherein the fixed portion is inserted into a through hole of the torque receiving portion and fixed to the torque receiving portion, the load sensor is disposed within the through hole of the torque receiving portion, sandwiched between the torque receiving portion and the fixed portion, and is fixed to the fixed portion by a fixing member, the friction member comprises a first friction member and a second friction member, and the first friction member and the second friction member are connected by an adjuster that is displaceable relative to the torque receiving portion.

According to the present invention, the load sensor is disposed in a fixed portion of the drive device that is fixed to the torque receiving portion. This allows the load received by the torque receiving portion to be detected with high accuracy. Since the load and the actual braking force correspond with high accuracy, the actual braking force can be calculated with high accuracy. In addition, since the load sensor is provided in the drive device that is generally installed at the top inside the wheel, the complexity of wiring can be suppressed.

1 is a configuration diagram of a vehicle braking device according to a first embodiment (a cross-sectional view seen from the left side of a vehicle). 1 is a configuration diagram of a vehicle braking device according to a first embodiment (a cross-sectional view seen from above a vehicle); FIG. 11 is a configuration diagram (sectional view seen from above the vehicle) of a vehicle braking device according to a second embodiment. FIG. 11 is a configuration diagram of a vehicle braking device according to a third embodiment (a cross-sectional view seen from the left side of the vehicle). FIG. 13 is a configuration diagram (sectional view seen from above the vehicle) of a vehicle braking device according to a third embodiment.

Embodiments of the present invention will be described below with reference to the drawings. Note that in the following embodiments, parts that are identical or equivalent to each other are given the same reference numerals in the drawings. Also, each drawing used in the description is a conceptual diagram. In the following description, the front of the vehicle will be referred to as the front, and the rear of the vehicle will be referred to as the rear.

First Embodiment
As shown in Figures 1 and 2, the vehicle braking device 1 of the first embodiment is a duo-servo type drum brake, and includes a rotating drum (corresponding to the "brake rotating body") 2, a first brake shoe (corresponding to the "first friction member") 31, a second brake shoe (corresponding to the "second friction member") 32, an adjuster 33, a back plate 4 that constitutes a torque receiving portion, a drive device 5, a load sensor 6, and a brake ECU 7.

The rotating drum 2 is a member that rotates together with the wheel. The first brake shoe 31 and the second brake shoe 32 are friction members that are pressed against the rotating drum 2 during braking. The first brake shoe 31 and the second brake shoe 32 are each a convex arc-shaped member with a lining 30 on the outer periphery. The first brake shoe 31 is a leading shoe that is disposed relatively forward. The second brake shoe 32 is a trailing shoe that is disposed relatively rearward. The first brake shoe 31 and the second brake shoe 32 are disposed in an arc shape.

The first brake shoe 31 and the second brake shoe 32 are mounted on the back plate 4 so that they can be spread apart from each other by a shoe hold pin (not shown). The first brake shoe 31 and the second brake shoe 32 are connected by a return spring (not shown) and are configured to return to their initial positions when no force is applied.

The adjuster 33 is a rod-shaped member that transmits force from one end to the other end and is adjustable in length. The adjuster 33 is also called a shoe adjuster or floating support. One end (front end) of the adjuster 33 is fixed to the lower end of the first brake shoe 31, and the other end (rear end) of the adjuster 33 is fixed to the lower end of the second brake shoe 32. The adjuster 33 does not abut against the back plate 4 and is movable relative to the back plate 4. In this way, the first brake shoe 31 and the second brake shoe 32 are connected by the adjuster 33, which is displaceable relative to the back plate 4.

The back plate 4 is fixed to a vehicle body member (not shown) that rotatably supports the wheel. The back plate 4 functions as a torque receiving part that applies a braking force to the wheel by preventing the rotation of the first brake shoe 31 and the second brake shoe 32. The drive unit 5 is fixed to the back plate 4.

The drive unit 5 is an actuator that drives the first brake shoe 31. The drive unit 5 of the first embodiment constitutes an electric mechanical brake (EMB) that drives the first piston 52 with an electric motor 55. The drive unit 5 is disposed between the upper end of the first brake shoe 31 and the upper end of the second brake shoe 32. The drive unit 5 includes a fixed part 51, a first piston (corresponding to the "movable part") 52, a second piston 53, a linear motion conversion part 54, an electric motor 55, a first stopper 561, and a second stopper 562.

The fixed portion 51 is a portion of the drive unit 5 that is fixed to the back plate 4. The fixed portion 51 can also be considered a housing for the drive unit 5. In more detail, the fixed portion 51 includes a first cylinder portion 511, a second cylinder portion 512, and a storage portion 513. The first cylinder portion 511 constitutes the vehicle front portion of the fixed portion 51 and is disposed so as to face the first brake shoe 31. The first cylinder portion 511 is formed in a bottomed cylindrical shape that opens to the front of the vehicle. A through hole 511a is formed in the bottom of the first cylinder portion 511, through which the screw shaft 541 of the linear motion conversion unit 54 is inserted.

The second cylinder portion 512 constitutes the vehicle rear portion of the fixed portion 51 and is arranged to face the second brake shoe 32. The second cylinder portion 512 is formed in a cylindrical shape that opens toward the rear of the vehicle. The second cylinder portion 512 is arranged coaxially with the first cylinder portion 511. In other words, the central axis of the first cylinder portion 511 and the central axis of the second cylinder portion 512 are located on the same straight line.

The accommodation section 513 is a section that accommodates the linear motion conversion section 54 and the load sensor 6, and is located between the first cylinder section 511 and the second cylinder section 512. The accommodation section 513 extends in the left-right direction of the vehicle so as to connect the first cylinder section 511 and the second cylinder section 512, which are located on the outer side of the vehicle than the back plate 4, with the electric motor 55, which is located on the inner side of the vehicle than the back plate 4. The accommodation section 513 is inserted into the through hole 40 of the back plate 4 and fixed to the back plate 4. The torque received by the fixing section 51 is received by the part of the back plate 4 that forms the through hole 40. The torque received by the fixing section 51 may be received by a fastening section that fastens the fixing section 51 to the back plate 4.

The first piston 52 constitutes a movable part that drives the first brake shoe 31 to press it against the rotating drum 2. The first piston 52 is disposed opposite the upper end of the first brake shoe 31. The first piston 52 is a nut member disposed in the first cylinder portion 511. The first piston 52 is disposed so as to be movable in the front-rear direction relative to the first cylinder portion 511 but unable to rotate. In other words, the first piston 52 and the first cylinder portion 511 are formed with a rotation stop mechanism (e.g., engagement between a rail groove and a rail) (not shown) to prevent the first piston 52 from rotating around its axis relative to the first cylinder portion 511.

The first piston 52 is screwed onto the screw shaft 541 of the linear motion conversion unit 54 and moves back and forth in response to the rotation of the screw shaft 541. In other words, when the screw shaft 541 rotates forward, the first piston 52 moves forward (towards the first brake shoe 31), and when the screw shaft 541 rotates reversely, the first piston 52 moves backward.

The second piston 53 is a piston member that is arranged in the second cylinder portion 512 so as to be movable in the front-rear direction. The second piston 53 is arranged opposite the upper end of the second brake shoe 32.

The linear motion conversion unit 54 is a mechanism that converts the rotational motion of the output shaft 551 of the electric motor 55 into the linear motion of the first piston 52. The linear motion conversion unit 54 is configured to transmit power from the output shaft 551 to the screw shaft 541 via a reducer. The first piston 52 can be said to constitute a part of the linear motion conversion unit 54.

The electric motor 55 is the driving source of the drive unit 5 and is controlled by the brake ECU 7. The driving force of the electric motor 55 is transmitted to the first piston 52 via the output shaft 551 and the linear motion converter 54.

The first stopper 561 and the second stopper 562 are separate from the fixed part 51 and are parts that engage with the fixed part 51 in the front-rear direction. The first stopper 561 is a plate-shaped member, and its front surface abuts against a protrusion (inner wall part) 51a formed in the storage part 513. The forward movement of the first stopper 561 is restricted by the protrusion 51a.

The second stopper 562 is a plate-shaped member and is disposed rearward of the first stopper 561. The rear surface of the second stopper 562 abuts against a protrusion (inner wall portion) 51b formed in the storage portion 513. The rearward movement of the second stopper 562 is restricted by the protrusion 51b. The load sensor 6 is disposed between the first stopper 561 and the second stopper 562.

The load sensor 6 is a sensor that is installed in the fixed portion 51 and detects a force (load) applied to the fixed portion 51. The load sensor 6 includes, for example, a strain gauge. The load sensor 6 is sandwiched between the first stopper 561 and the second stopper 562 and detects the force in the front-rear direction (axial direction) received from the first stopper 561 and the second stopper 562. The detection result of the load sensor 6 is transmitted to the brake ECU 7 via wiring (not shown). In the first embodiment, the load sensor 6 is disposed in the drive unit 5, and it can be said that the drive unit 5 and the load sensor 6 are one unit. This unit is disposed in an upper portion inside the wheel.

The brake ECU 7 is an electronic control unit equipped with a processor, memory, etc. The brake ECU 7 controls the drive unit 5 in response to a braking request. When the brake ECU 7 rotates the output shaft 551 of the electric motor 55 in the forward direction in response to a braking request, the first piston 52 advances and presses the first brake shoe 31 against the rotating drum 2. This generates a frictional force (resistance force) against the rotation of the wheel and the rotating drum 2, which becomes a braking force. The brake ECU 7 is equipped with a calculation unit 71 that calculates the braking force based on the detection value of the load sensor 6.

(Braking while the vehicle is moving)
1, when braking control is performed while the vehicle is traveling, forces P1, R1, Fc, P2, R2, and F2 are generated at various points by force F1, which is generated when the first piston 52 presses the first brake shoe 31 (F1<F2). Force F2 is the reaction force of the second piston 53 against the second brake shoe 32, and is a value obtained by adding an increase due to frictional force to force F1.

The reaction force (=F1) from the first brake shoe 31 against the pressing force F1 of the first piston 52 can be received by the fixed part 51 and the back plate 4 via the linear motion conversion part 54, the first stopper 561, the load sensor 6, and the second stopper 562. In addition, the force (=F2) of the second brake shoe 32 pressing the second piston 53 can be received by the fixed part 51 and the back plate 4 via the second piston 53, the second stopper 562, the load sensor 6, and the first stopper 561.

When braking while driving, force F2 is greater than force F1, and the load sensor 6 is pressed forward by force F2. The load sensor 6 detects this force (load) and transmits it to the brake ECU 7. This force corresponds to the braking force with high accuracy, so the brake ECU 7 can calculate the actual braking force with high accuracy.

(Braking when the vehicle is stopped)
When braking control is performed while the vehicle is stopped, unlike when the vehicle is moving, the rotating drum 2 is not rotating, and therefore no frictional force is generated by the rotation of the rotating drum 2. As a result, the forces Fc and F2 become smaller, and the load sensor 6 is pressed backward, detecting a load (reaction force of the first brake shoe 31) equivalent to the force F1 with which the first piston 52 presses the first brake shoe 31. This force (axial force) corresponds to the output of the drive unit 5. Therefore, the brake ECU 7 can calculate the output of the drive unit 5 based on the detection value of the load sensor 6 while the vehicle is stopped. This makes it possible, for example, to calibrate the output of the drive unit 5 and detect the axial force when the parking brake is locked.

(Effects of the First Embodiment)
According to the first embodiment, the load sensor 6 is disposed in the drive device 5 at the fixed portion 51 fixed to the back plate 4. Therefore, the load received by the back plate 4 can be detected with high accuracy. Since the load and the actual braking force correspond with high accuracy, the actual braking force can be calculated with high accuracy. In addition, since the load sensor 6 is provided in the drive device 5 which is generally installed at the top inside the wheel, it is possible to suppress the complication of wiring. In addition, it is possible to unitize the drive device 5 and the load sensor 6, which makes it possible to simplify the wiring and improve the ease of assembly.

Second Embodiment
The vehicle braking system 1A of the second embodiment is different from the first embodiment mainly in the arrangement position of the load sensor 6. The differences will be described below. In the description of the second embodiment, the description and drawings of the first embodiment can be referred to as appropriate.

As shown in FIG. 3, the load sensor 6 of the second embodiment is disposed within the through-hole 40 of the backplate 4, sandwiched between the backplate 4 and the fixed portion 51 (accommodating portion 513). To explain an example of fixing, a fixed member 61 is disposed between the backplate 4 and the load sensor 6. A pin member 62 extending in the front-rear direction is fixed to the outer wall of the fixed portion 51, penetrating the fixed member 61. As a result, the fixed member 61 is fixed to the fixed portion 51, and the load sensor 6 is fixed between the fixed member 61 and the fixed portion 51. In addition, a pin member 63 extending in the left-right direction is fixed to the backplate 4, penetrating the fixed member 61. As a result, the fixed member 61 is fixed to the backplate 4.

In the second embodiment, there is no second piston 53, and the rear end of the fixed part 51 (the part corresponding to the second cylinder part 512) facing the first piston 52 is formed in a solid columnar (rod-like) shape. The rear end of this fixed part 51 is disposed opposite the second brake shoe 32.

In the second embodiment, when braking control is executed while driving, the rear end of the fixed part 51 is pressed by a pressing force (= F2) from the second brake shoe 32, as in the first embodiment. This pressing force is received by the back plate 4 via the fixed part 51 and the load sensor 6. At this time, the load sensor 6 receives a forward pressing force (due to elastic deformation) from the fixed part 51 and detects the load. As in the first embodiment, this load corresponds to the actual braking force with high precision. The brake ECU 7 can calculate the actual braking force based on the detection value of the load sensor 6.

In the second embodiment, the load sensor 6 is also placed on the fixed part 51 of the drive unit 5 located at the top inside the wheel, which makes it possible to prevent the wiring from becoming complicated. In addition, the drive unit 5 and the load sensor 6 can be unitized. In this way, the second embodiment also achieves the same effects as the first embodiment. However, with the configuration of the second embodiment, it is difficult to detect the axial force during braking when the vehicle is stopped.

Third Embodiment
The vehicle brake device 1B of the third embodiment is different from the first embodiment in that the driving force of the electric motor 55 is converted by the linear motion converter 54 and transmitted to the second piston 53. The differences will be described below. In the description of the third embodiment, the description and drawings of the first embodiment can be referred to as appropriate.

As shown in Figures 4 and 5, in the third embodiment, a screw shaft 542, which is part of the linear motion conversion unit 54, is disposed behind the screw shaft 541 via the load sensor 6. The screw shaft 542 is inserted into a through hole 512a formed in the bottom surface of the second cylinder unit 512. The second cylinder unit 512 is formed in a bottomed cylindrical shape that opens to the rear. The screw shafts 541 and 542 are configured so that the first piston 52 moves forward and the second piston 53 moves backward when the electric motor 55 rotates in the forward direction.

The load sensor 6 is disposed between the screw shaft 541 and the screw shaft 542 in the housing portion 513. The first stopper 561 is disposed between the load sensor 6 and the screw shaft 541. The second stopper 562 is disposed between the load sensor 6 and the screw shaft 542. As in the first embodiment, the first stopper 561 is restricted from moving forward by the fixed portion 51, and the second stopper 562 is restricted from moving backward by the fixed portion 51.

Even with the configuration of the third embodiment, when braking while traveling, the pressing force of the second brake shoe 32 is received by the fixed part 51 and the back plate 4 via the second piston 53, the screw shaft 542, the second stopper 562, the load sensor 6, and the first stopper 561. At this time, the load sensor 6 detects the forward pressing force from the second stopper 562. This force corresponds to the actual braking force with high precision, and the brake ECU 7 can calculate the actual braking force with high precision. In addition, the braking force when the vehicle is stopped can be calculated in the same way as in the first embodiment. In addition, since the load sensor 6 is arranged inside the drive unit 5, the complexity of wiring can be suppressed. In addition, the drive unit 5 and the load sensor 6 can be unitized.

＜Other＞
The present invention is not limited to the above embodiment. For example, the number of brake shoes does not need to be two as in the above embodiment, and one (e.g., an annular brake shoe) may be used. Furthermore, the drive device 5 is not limited to the EMB, and may be, for example, a hydraulic drive device that drives a movable part (piston) by hydraulic pressure.

1, 1A, 1B...vehicle braking device, 2...rotating drum (brake rotor), 31...first brake shoe (first friction member), 32...second brake shoe (second friction member), 33...adjuster, 4...back plate (torque receiving portion), 5...driving device, 51...fixed portion, 52...first piston (movable portion), 6...load sensor, 71...calculation portion.

Claims (2)

A brake rotor that rotates together with the wheel;
a friction member that is pressed against the brake rotor during braking;
a torque receiving portion that applies a braking force to the wheel by preventing rotation of the friction member;
a drive device including a fixed portion that houses a linear motion conversion portion and is fixed to the torque receiving portion, and a movable portion that drives the friction member to press it against the brake rotor;
A load sensor is installed on the fixed portion and detects a force applied to the fixed portion;
a calculation unit that calculates the braking force based on a detection value of the one of the load sensors;
Equipped with
The friction member includes a first friction member and a second friction member,
A vehicle brake device , wherein the first friction member and the second friction member are connected by an adjuster that is displaceable relative to the torque receiving portion . A brake rotor that rotates together with the wheel;
a friction member that is pressed against the brake rotor during braking;
a torque receiving portion that applies a braking force to the wheel by preventing rotation of the friction member;
a drive device including a fixed portion that houses a linear motion conversion portion and is fixed to the torque receiving portion, and a movable portion that drives the friction member to press it against the brake rotor;
A load sensor is installed on the fixed portion and detects a force applied to the fixed portion;
a calculation unit that calculates the braking force based on a detection value of the one of the load sensors;
Equipped with
the fixing portion is inserted into a through hole of the torque receiving portion and fixed to the torque receiving portion,
the load sensor is disposed in the through hole of the torque receiving portion, sandwiched between the torque receiving portion and the fixed portion, and fixed to the fixed portion by a fixing member,
The friction member includes a first friction member and a second friction member,
A vehicle brake device , wherein the first friction member and the second friction member are connected by an adjuster that is displaceable relative to the torque receiving portion .

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