JP2023080495A - Vehicular brake device - Google Patents

Abstract

To provide a vehicular brake device which can calculate a braking force applied to a wheel by a drum brake while achieving reduction of costs.SOLUTION: A vehicular brake device includes: a drum 12; a first brake shoe 15 and a second brake shoe 16; an anchor member 20 which prevents rotation of the brake shoes 15, 16 to apply a braking force to a wheel by the brake shoes 15, 16 being pressed to an inner peripheral surface 12a of the drum 12 in opposite directions; a sensor 22 which detects a force to be applied to the anchor member 20 based on a degree of deformation of a connection member 21 according to a difference between a first force applied from the first brake shoe 15 to the anchor member 20 and a second force applied from the second brake shoe 16 to the anchor member 20; and a control device 50 which calculates the braking force according to a detection value of the sensor 22.SELECTED DRAWING: Figure 2

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle braking system having a drum brake.

Patent Literature 1 discloses a vehicle braking device that includes a drum brake and a control device that calculates the braking force applied to the wheels by the drum brake. In this vehicular braking device, the anchor of the drum brake is provided with a first sensor for detecting the force input from the leading shoe to the anchor and a second sensor for detecting the force input from the trailing shoe to the anchor. It is The control device then calculates the braking force based on the difference between the force detected by the first sensor and the force detected by the second sensor.

Japanese Patent Publication No. 2020-532694

In the vehicle braking system described above, two sensors must be provided on the anchor in order to calculate the above braking force both when the vehicle moves forward and when the vehicle moves backward, which increases the cost. . In other words, there is room for improvement in terms of reducing the cost of the vehicle braking system as described above.

A vehicle braking device for solving the above problems comprises a drum that rotates integrally with a wheel of a vehicle, a first friction member and a second friction member that are arranged inside the drum, the first friction member and the an actuator for pressing the second friction member against the inner peripheral surface of the drum; and an actuator for pressing the first friction member and the second friction member against the inner peripheral surface in opposite directions. a torque receiving portion that prevents rotation of the first friction member and the second friction member and applies a braking force to the wheel; 2. Based on the degree of deformation of the torque receiving portion according to the difference between the force received by the torque receiving portion from the friction member and the second force in the direction opposite to the first force, the torque receiving portion A sensor that detects an applied force and a calculator that calculates a braking force to be applied to the wheel according to the detected value of the sensor.

When the wheels are rotating, when the first friction member and the second friction member are pressed against the inner peripheral surface of the drum by the operation of the actuator, a braking force is applied to the wheels as a force for decelerating the rotation of the wheels. At this time, the torque receiving portion receives the first force from the first friction member and the second force from the second friction member. Then, the torque receiving portion deforms according to the difference between the first force and the second force. The difference corresponds to the braking force applied to the wheels or the braking force.

Therefore, in the above configuration, the sensor detects the force applied to the torque receiving portion based on the degree of deformation of the torque receiving portion during braking. Then, the braking force is calculated according to the detected value of the sensor. That is, the braking force can be calculated even if the number of sensors is reduced.

Therefore, according to the above configuration, it is possible to calculate the braking force applied to the wheels by the drum brake while reducing the cost.

FIG. 1 is a configuration diagram showing an outline of a drum brake and a control device of a vehicle braking system according to an embodiment. FIG. 2 is a diagram showing the end face of the drum brake and the control device. FIG. 3 is an operation diagram showing the drum brake during braking. FIG. 4 is an end view showing a modified drum brake. FIG. 5 is an end view showing a modified drum brake. FIG. 6 is an end view showing a modified drum brake.

An embodiment of a vehicle braking system will be described below with reference to FIGS. 1 to 3. FIG.
As shown in FIG. 1 , the vehicle braking system 100 includes a drum brake 10 and a control device 50 .

<Drum brake>
The drum brake 10 includes a back plate 11 fixed to the vehicle body and a drum 12 attached to the vehicle axle. A drum 12 rotates together with the wheels of the vehicle. On the other hand, since the back plate 11 is fixed to the vehicle body, the back plate 11 does not rotate even when the wheels rotate. Therefore, the back plate 11 corresponds to the "fixing member".

The back plate 11 is a metal plate having a central hole 11a for passing an axle.
The drum 12 has a cylindrical portion 121 . The cylindrical portion 121 has a cylindrical shape around the axle. In the following description, the inner peripheral surface 12a of the cylindrical portion 121 may also be referred to as "the inner peripheral surface 12a of the drum 12".

The drum brake 10 comprises an actuation device 13 , a first brake shoe 15 and a second brake shoe 16 . The actuating device 13 , the first brake shoe 15 and the second brake shoe 16 are arranged inside the drum 12 respectively. The first brake shoe 15 corresponds to the "first friction member", and the second brake shoe 16 corresponds to the "second friction member". The first brake shoe 15 and the second brake shoe 16 are arranged such that the axle is positioned between the first brake shoe 15 and the second brake shoe 16 .

The actuation device 13 is located above the vehicle axle and between the first brake shoe 15 and the second brake shoe 16 . In this embodiment, the actuator 13 operates to press both the brake shoes 15 and 16 against the inner peripheral surface 12a of the drum 12 in accordance with the drive of the electric motor 14 .

The first brake shoe 15 and the second brake shoe 16 have an arc shape following the shape of the inner peripheral surface 12 a of the drum 12 . The first brake shoe 15 and the second brake shoe 16 each have a friction material 17 . When the actuator 13 is actuated, the friction material 17 of both brake shoes 15 and 16 is pressed against the inner peripheral surface 12a of the drum 12. As shown in FIG. The upper ends of the brake shoes 15 and 16 in FIG. 1 are referred to as "first ends of the brake shoes 15 and 16", and the lower ends of the brake shoes 15 and 16 in FIG. 1 are referred to as "second ends of the brake shoes 15 and 16". and At this time, the first ends of both brake shoes 15 and 16 are engaged with the actuating device 13 respectively. When the actuation device 13 is actuated, both the brake shoes 15 and 16 are displaced so that the first end of the first brake shoe 15 and the first end of the second brake shoe 16 are separated from each other. As a result, both brake shoes 15 and 16 are pressed against the inner peripheral surface 12a of the drum 12, respectively. That is, the actuating device 13 presses the brake shoes 15 and 16 against the inner peripheral surface 12a in opposite directions.

Of the two brake shoes 15 and 16, the brake shoe that is pressed in the rotational direction of the drum 12 functions as a "leading shoe," and the remaining brake shoes function as a "trailing shoe." That is, the first brake shoe 15 functions as a leading shoe, and the second brake shoe 16 functions as a leading shoe, depending on the direction of rotation of the wheel.

A return spring 19 is provided between the first brake shoe 15 and the second brake shoe 16 . A return spring 19 is arranged between the axle and the actuator 13 . A return spring 19 biases both brake shoes 15 and 16 to separate them from the inner peripheral surface 12 a of the drum 12 .

Also, as shown in FIGS. 1 and 2, an anchor member 20 is provided between the second end of the first brake shoe 15 and the second end of the second brake shoe 16 . That is, the anchor member 20 is arranged on the opposite side of the actuator 13 across the axle. Anchor member 20 is fixed to back plate 11 . Specifically, as shown in FIG. 2, a connecting member 21 is interposed between the back plate 11 and the anchor member 20 . The connecting member 21 is fixed to the back plate 11 and to the anchor member 20 . That is, the anchor member 20 is fixed to the back plate 11 via the connecting member 21 .

As shown in FIG. 2, the direction in which the first brake shoe 15 and the second brake shoe 16 are arranged in this order is referred to as "first direction X1". A direction in which the back plate 11, the connecting member 21, and the anchor member 20 are arranged in this order and which is orthogonal to the first direction X1 is referred to as a "second direction X2."

The connecting member 21 has a fixing surface 21 a in surface contact with the back plate 11 and an opposite surface 21 b in surface contact with the anchor member 20 . The fixed surface 21 a is fixed to the back plate 11 . On the other hand, the opposite surface 21b is located on the opposite side of the fixing surface 21a and is fixed to the anchor member 20. As shown in FIG. The connecting member 21 is configured such that the dimension in the first direction X1 is larger than the dimension in the second direction X2. The connecting member 21 is made of a material with relatively high rigidity. For example, the connecting member 21 is made of metal.

The anchor member 20 is configured by a metal plate. The anchor member 20 has a body portion 20a fixed to the connecting member 21 and a pair of input portions 20b and 20c extending from both ends of the body portion 20a toward the back plate 11. As shown in FIG. Of the two input portions 20b and 20c, the input portion connected to the first brake shoe 15 is the first input portion 20b, and the input portion connected to the second brake shoe 16 is the second input portion 20c. be.

As shown in FIG. 3, when both the brake shoes 15 and 16 are pressed against the drum 12 by the operation of the actuator 13, the first force F1 is input from the first brake shoe 15 to the anchor member 20 and , the second force F2 is input to the anchor member 20 from the second brake shoe 16 . That is, the anchor member 20 receives a first force F1 from the first brake shoe 15 and a second force F2 from the second brake shoe 16 . The input direction of the second force F<b>2 to the anchor member 20 is opposite to the input direction of the first force F<b>1 to the anchor member 20 . Incidentally, in this embodiment, the input direction of the first force F1 to the anchor member 20 and the input direction of the second force F2 to the anchor member 20 are parallel to the fixing surface 21a of the connecting member 21 .

In the example shown in FIG. 3, the second brake shoe 16 functions as a leading shoe and the first brake shoe 15 functions as a trailing shoe. Therefore, the second force F2 is greater than the first force F1. In other words, the first force F1 is approximately equal to the reaction force generated by pressing the first brake shoe 15 against the drum 12 . The second force F2 is approximately equal to the sum of the reaction force generated by pressing the second brake shoe 16 against the drum 12 and the braking force generated by pressing the second brake shoe 16 against the drum 12 . The reaction force generated by pressing the first brake shoe 15 against the drum 12 is approximately equal to the reaction force generated by pressing the second brake shoe 16 against the drum 12 . Therefore, the difference between the first force F1 and the second force F2 correlates with the braking force applied to the wheels by the drum brake 10 . In the present embodiment, since the anchor member 20 can be regarded as a rigid body, the anchor member 20 hardly deforms although the connecting member 21 that connects the anchor member 20 and the back plate 11 is deformed, ie, strained.

The drum brake 10 has a sensor 22 that detects the degree of deformation of the connecting member 21 . Sensor 22 is attached to connecting member 21 . The sensor 22 may be, for example, a strain gauge. That is, the sensor 22 detects the force applied to the connecting member 21 based on the degree of deformation of the connecting member 21 , that is, the degree of distortion of the connecting member 21 . A detection signal from the sensor 22 is input to the control device 50 .

In this embodiment, the back plate 11, the connecting member 21, and the anchor member 20 constitute a "torque receiving portion." The sensor 22 corresponds to a "sensor" that detects the force applied to the torque receiving portion based on the degree of deformation of the torque receiving portion.

<Control device>
As shown in FIGS. 1 and 2, a detection signal from the sensor 22 is input to the controller 50 . Such a control device 50 has an execution section 51 and a storage section 52 . For example, the execution unit 51 is a CPU. The storage unit 52 stores a control program executed by the execution unit 51 . The execution unit 51 functions as a braking control unit and a calculation unit by executing a control program.

The execution unit 51 controls the electric motor 14 by functioning as a braking control unit. When the execution unit 51 drives the electric motor 14, the operating device 13 operates and the two brake shoes 15 and 16 are displaced away from each other.

The execution unit 51 functions as a calculation unit to calculate the magnitude of the braking force applied to the wheels by the drum brake 10 as the braking force calculation value T. That is, the execution unit 51 derives the force F applied to the connecting member 21 based on the detection value of the sensor 22 . The execution unit 51 calculates the calculated braking force value T such that the larger the derived force F, the larger the value. For example, the execution unit 51 calculates the braking force calculation value T using the following relational expression (Equation 1). In the relational expression (Formula 1), "m" is a constant of proportionality. Thereby, the execution unit 51 calculates the braking force calculation value T according to the detection value of the sensor 22 .

T=F·m (Equation 1)
Note that, in the present embodiment, the braking force applied to the wheels is a force for decelerating the rotational speed of the wheels. Therefore, when the rotation of the wheels stops due to the operation of the drum brakes 10, the magnitude of the braking force applied to the wheels by the drum brakes 10 becomes 0 (zero).

<Actions and effects of the present embodiment>
When the electric motor 14 is driven, the actuator 13 is actuated, so that the brake shoes 15 and 16 are displaced away from each other. Then, the friction materials 17 of both brake shoes 15 and 16 are pressed against the inner peripheral surface 12a of the drum 12, respectively. When both brake shoes 15 and 16 are pressed against drum 12 in this way, both brake shoes 15 and 16 tend to rotate in the direction corresponding to the rotation of drum 12 . However, since the second ends of both brake shoes 15 and 16 are connected to the anchor member 20 of the torque receiving portion, the anchor member 20 prevents both brake shoes 15 and 16 from rotating. At this time, due to the rotation of the drum 12, the force pressing the brake shoe, which functions as the leading shoe, against the drum 12 among the two brake shoes 15 and 16 further increases. This amplifies the braking force applied to the wheels.

When a braking force is applied to the wheel by the drum brake 10, as shown in FIG. A second force F<b>2 is input from the second brake shoe 16 to the second input portion 20 c of the member 20 . In the example shown in FIG. 3, the second brake shoe 16 functions as a leading shoe and the first brake shoe 15 functions as a trailing shoe. Therefore, the second force F2 is greater than the first force F1.

When the first force F1 and the second force F2 are input to the anchor member 20, the connecting member 21 that connects the back plate 11 and the anchor member 20 has the difference between the first force F1 and the second force F2, Alternatively, a force F having a magnitude corresponding to the difference is input. As a result, while the anchor member 20 is hardly deformed, the connecting member 21 is distorted according to the force F input to the connecting member 21 . At this time, the greater the force F, the greater the degree of distortion of the connecting member 21 .

In this embodiment, the sensor 22 detects the degree of distortion of the connecting member 21 . That is, the sensor 22 detects the force F applied to the connecting member 21 . The control device 50 calculates a braking force calculation value T according to the force F detected by the sensor 22 . In this embodiment, the calculated braking force value T is calculated using the above relational expression (Equation 1). Therefore, the calculated braking force value T increases as the force F increases.

In this embodiment, it is not necessary to provide a plurality of sensors in the torque receiving portion in order to calculate the braking force calculation value T. FIG. Therefore, the calculated braking force value T can be calculated while reducing the cost.
The direction of rotation of the wheels changes depending on whether the vehicle moves forward or moves backward. In this embodiment, even if the first force F1 is greater than the second force F2, the sensor 22 can detect the force F according to the difference between the first force F1 and the second force F2. Therefore, the control device 50 can calculate the braking force calculation value T regardless of whether the vehicle moves forward or moves backward.

In this embodiment, the following effects can be further obtained.
(1) In this embodiment, the fixed portion fixed to the vehicle body, the input portion to which force is input from both brake shoes 15 and 16, and the deformation according to the difference between the first force F1 and the second force F2 The deformable parts are each composed of separate members. That is, the back plate 11 functions as a fixed portion, the anchor member 20 functions as an input portion, and the connecting member 21 functions as a deformable portion. As a result, compared to the case where the fixed portion, the input portion, and the deformation portion are made of the same member, that is, compared to the case where the torque receiving member is made of one member, the shape of the member making up the torque receiving portion is complicated. can be prevented from becoming

(2) When the force F applied to the connecting member 21 is the same, the greater the degree of distortion of the connecting member 21, the easier it is to increase the detection accuracy of the sensor 22 . In this embodiment, the direction of the first force F<b>1 and the direction of the second force F<b>2 input to the anchor member 20 are parallel to the fixing surface 21 a of the connecting member 21 . Therefore, the degree of distortion of the connecting member 21 tends to increase. Therefore, the detection accuracy of the sensor 22 can be increased, and the calculation accuracy of the braking force calculation value T can be increased.

(3) Since the anchor member 20 is fixed to the opposite surface 21b of the connecting member 21 that is farthest from the fixing surface 21a fixed to the back plate 11, the force F is input to the opposite surface 21b. As a result, compared to the case where the force F is input to the portion between the fixing surface 21a and the opposite surface 21b of the connecting member 21, the degree of distortion of the connecting member 21 tends to increase. Therefore, the detection accuracy of the force F by the sensor 22 can be increased, and the calculation accuracy of the braking force calculation value T can be increased.

<Change example>
The above embodiment can be implemented with the following modifications. The above embodiments and the following modifications can be combined with each other within a technically consistent range.

- The anchor member may be fixed to the back plate 11 without interposing the connecting member 21 . FIG. 4 shows an end view of the drum brake 10A when the anchor member 20A is directly fixed to the back plate 11. As shown in FIG. In this case, during braking, the portion of the anchor member 20A between the portion fixed to the back plate 11 and the portion to which the first force F1 and the second force F2 are input from both the brake shoes 15 and 16 is A certain deformation part is deformed. When the sensor 22 detects the degree of deformation of such a deformed portion, the control device 50 can calculate the braking force calculation value T based on the force detected by the sensor 22 .

- As a sensor, for example, a sensor 22B having a ring-shaped sensing portion as shown in FIG. 5 may be adopted. Such a sensor 22B is, for example, a washer-type piezoelectric force sensor. FIG. 5 shows an end view of drum brake 10B when sensor 22B is employed. A sensor 22B is interposed between the anchor member 20B and the back plate 11 in the drum brake 10B. The anchor member 20B is attached to the back plate 11 with a bolt 21B, which is an example of a connecting member. At this time, the shaft portion 21Ba of the bolt 21B passes through the sensor 22B in surface contact with the inner peripheral surface of the sensor 22B.

In this configuration, when the first force F1 and the second force F2 are input to the anchor member 20B, the shaft portion 21Ba of the bolt 21B deforms according to the difference between the first force F1 and the second force F2. The force F applied to the bolt 21B is detected by the sensor 22B detecting the degree of deformation of the shaft portion 21Ba at this time. Therefore, the control device 50 can calculate the braking force calculated value T based on the force F detected by the sensor 22B.

- The torque receiving portion may be composed of one member as shown in FIG. FIG. 6 shows an end view of the drum brake 10C in which the back plate 11 constitutes the torque receiving portion. The drum brake 10C has a shape in which a part of the back plate 11 is pushed out in the second direction X2. In this case, the portion of the back plate 11 that does not protrude in the second direction X2 is the fixing portion 111 that is fixed to the vehicle body. Further, the tip portion of the back plate 11 projecting in the second direction X2 is the input portion 112 to which the first force F1 and the second force F2 are input from the brake shoes 15 and 16 . A connecting portion 113 is a portion of the back plate 11 that connects the input portion 112 and the fixed portion 111 .

In this configuration, when the input portion 112 receives the first force F1 and the second force F2 from the brake shoes 15 and 16, the connecting portion 113 deforms. At this time, the force F applied to the connecting portion 113 is detected by the sensor detecting the degree of deformation of the connecting portion 113 . Therefore, the control device 50 can calculate the calculated braking force value T based on the force F detected by the sensor.

- In the above-described embodiment, the connecting member 21 is configured so that the direction of the first force F1 and the direction of the second force F2 are parallel to the fixing surface 21a, but the present invention is not limited to this. If the connecting member 21 is distorted according to the difference between the first force F1 and the second force F2 when the first force F1 and the second force F2 are input to the anchor member 20, the fixing surface 21a of the connecting member 21 , the direction of the first force F1 and the direction of the second force F2 may be slightly inclined.

- The portion of the connecting member 21 to which the force F corresponding to the difference between the first force F1 and the second force F2 is input does not have to be the opposite surface 21b. That is, if the connecting member 21 is distorted by the input of the force F to the connecting member 21, the force F may be input to the portion between the fixed surface 21a and the opposite surface 21b of the connecting member. .

- In the above embodiment, an electric dry drum brake is used as the drum brake 10, but the present invention is not limited to this. For example, the drum brake 10 may be a wet drum brake that operates according to hydraulic pressure supplied from an electric hydraulic supply source. In this case, the actuating device is the wheel cylinder. Further, the drum brake 10 may be a brake operated by hydraulic pressure supplied from the master cylinder.

- The control device 50 includes one or more processors that operate according to a computer program, one or more dedicated hardware circuits such as dedicated hardware that executes at least part of various processes, or a combination thereof. It can be configured as a circuit. Dedicated hardware may include, for example, an ASIC, which is an application specific integrated circuit. A processor includes a CPU and memory, such as RAM and ROM, which stores program code or instructions configured to cause the CPU to perform processes. Memory or storage media includes any available media that can be accessed by a general purpose or special purpose computer.

10, 10A, 10B, 10C... Drum brake 11... Back plate (an example of a fixing member)
DESCRIPTION OF SYMBOLS 12... Drum 12a... Inner peripheral surface 13... Operating device 15... First brake shoe (an example of a first friction member)
16... Second brake shoe (an example of a second friction member)
DESCRIPTION OF SYMBOLS 20, 20A, 20B... Anchor member 21... Connection member 21a... Fixed surface 21b... Opposite surface 21B... Bolt (an example of a connection member)
21Ba... Axle part 22, 22B... Sensor 50... Control device (an example of a calculation part)
100... Vehicle braking device

Claims (4)

a drum that rotates integrally with the wheels of the vehicle;
a first friction member and a second friction member disposed inside the drum;
an actuator for pressing the first friction member and the second friction member against the inner peripheral surface of the drum;
The first friction member and the second friction member are pressed against the inner peripheral surface in opposite directions by the operating device, thereby preventing rotation of the first friction member and the second friction member, thereby preventing the wheel from rotating. a torque receiving portion that applies a braking force to the
a first force that is the force that the torque receiving portion receives from the first friction member and a second force that is the force that the torque receiving portion receives from the second friction member and is a force in the opposite direction to the first force; a sensor that detects the force applied to the torque receiving portion based on the degree of deformation of the torque receiving portion according to the difference between
and a calculation unit that calculates a braking force to be applied to the wheel according to the detection value of the sensor. The torque receiving portion is
a fixing member fixed to the vehicle body of the vehicle;
an anchor member to which the first force and the second force are input;
a connecting member that connects the fixing member and the anchor member and deforms according to the difference when the first force and the second force are input to the anchor member;
The vehicle braking device according to claim 1, wherein the sensor detects the force applied to the torque receiving portion based on the degree of deformation of the connecting member. 3. The connecting member according to claim 2, wherein the fixing surface fixed to the fixing member and the direction of the first force and the direction of the second force are parallel to each other. Vehicle braking device. The vehicle braking device according to claim 2 or 3, wherein the anchor member is fixed to a surface of the connecting member opposite to a surface fixed to the fixing member.

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