JP2022139636A - Vehicular brake device - Google Patents

Abstract

To provide a vehicular brake device which enables improvement of flexibility in arrangement of load sensors.SOLUTION: A vehicular brake device includes: a brake rotating body 2 which rotates with a wheel; friction members 31, 32 which are pressed against the brake rotating body 2 during braking; torque receiving parts 4, 41 which prevent rotation of the friction members 31, 32 to provide a brake force to the wheel; a driving device 5 which drives the friction members 31, 32 to press the friction members 31, 32 to the brake rotating body 2; load sensors 61, 62 which are provided in at least one of the driving device 5 and the torque receiving parts 4, 41 and detect a force acting in a direction different from a direction in which the driving device 5 drives the friction members 31, 32; and a calculation part 71 which calculates the brake force based on detection values of the load sensors 61, 62.SELECTED DRAWING: Figure 1

Description

The present invention relates to a vehicle braking system.

2. Description of the Related Art As a vehicle braking device, for example, one using a drum brake is known as described in Japanese Patent Laid-Open No. 2010-274689. In this vehicle braking system, the anchor is provided with a load sensor in order to calculate the braking force.

JP 2010-274689 A

In the vehicle braking device described above, the load sensor is provided on the anchor arranged at the lower portion within the wheel. In this arrangement, the wiring of the load sensor must be routed across the wheel from the bottom to the top. Prone. If the load sensor is placed only at the anchor, it becomes difficult to eliminate the complexity of the wiring. In other words, the conventional configuration has room for improvement in terms of the degree of freedom in arranging the load sensor.

SUMMARY OF THE INVENTION An object of the present invention is to provide a vehicle braking system capable of improving the degree of freedom in arranging a load sensor.

A vehicle braking device according to the present invention includes a brake rotator that rotates together with a wheel, a friction member that is pressed against the brake rotator during braking, and a braking force that is applied to the wheel by preventing rotation of the friction member. a torque receiving portion, a driving device for driving the friction member to press it against the brake rotating body, and a torque receiving portion provided in at least one of the driving device and the torque receiving portion, the driving device driving the friction member. a load sensor for detecting forces in different directions; and a calculation unit for calculating the braking force based on the detection value of the load sensor.

For example, when a vehicle braking device has two friction members (brake shoes), when a braking torque is generated while the vehicle is moving forward, a downward force is applied to the leading shoe due to reaction of the torque, and an upward force is applied to the trailing shoe. is added. That is, a force in a direction different from the direction in which the driving device drives (moves) the friction member is applied to the brake shoe. The magnitude of these vertical forces corresponds to the magnitude of braking torque (braking force). Therefore, the braking torque can be calculated by detecting a force in a direction different from the direction in which the driving device drives the friction member during braking.

In the conventional configuration, the load sensor detects the force in the direction in which the drive device presses the friction member (in the longitudinal direction of the vehicle). is provided in However, according to the invention, the load sensors need only be arranged to receive forces in different directions with respect to the direction in which the drive drives the friction member. Therefore, the load sensor is not limited to the portion of the friction member that directly receives the load, and may be, for example, a drive device. As described above, according to the present invention, the load sensor can detect a force in a direction different from the direction in which the driving device drives the friction member, thereby improving the degree of freedom in arranging the load sensor.

1 is a configuration diagram (sectional view seen from the left side of a vehicle) of a vehicle braking device according to a first embodiment; FIG. 1 is a configuration diagram (a cross-sectional view as seen from above the vehicle) of a vehicle braking device according to a first embodiment; FIG. FIG. 7 is a configuration diagram (a cross-sectional view as seen from the left side of the vehicle) of the load sensor of the second embodiment; FIG. 4 is a sectional view taken along line IV-IV of FIG. 3; FIG. 11 is a configuration diagram (sectional view seen from the left side of the vehicle) of the load sensor of the third embodiment; FIG. 11 is a configuration diagram (sectional view seen from the left side of the vehicle) of a load sensor according to a fourth embodiment; FIG. 11 is a configuration diagram (sectional view seen from the left side of the vehicle) of a modification of the second embodiment;

An embodiment of the present invention will be described below with reference to the drawings. In addition, in each of the following embodiments, the same reference numerals are given to the parts that are the same or equivalent to each other. Moreover, each figure used for 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. Also, in the description, the wheels are taken as the wheels on the left side of the vehicle. In FIG. 2, the display of the back plate 4 and the like is omitted.

<First embodiment>
As shown in FIGS. 1 and 2, the vehicle braking system 1 of the first embodiment is a so-called leading/trailing drum brake, comprising a rotating drum (corresponding to a "brake rotating body") 2 and a 1 brake shoe (corresponding to a "friction member") 31, a second brake shoe (corresponding to a "friction member") 32, a back plate (corresponding to a "torque receiving portion") 4, and an anchor (corresponding to a "torque ) 41 , a drive device 5 , a first load sensor 61 , a second load sensor 62 , and a brake ECU 7 .

The rotating drum 2 is a member that rotates together with the wheels. 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 arc-shaped members each having a lining 30 on the outer peripheral side. The first brake shoe 31 is arranged relatively forward and is a leading shoe when the vehicle moves forward. The second brake shoe 32 is arranged relatively rearward and is a trailing shoe when the vehicle moves forward. The first brake shoe 31 and the second brake shoe 32 are arranged in an arc shape.

The back plate 4 is fixed to a vehicle body member (not shown) that rotatably supports the wheel. An anchor 41 is fixed to the lower portion of the back plate 4 , and a driving device 5 is fixed to the upper portion of the back plate 4 . A lower end portion of the first brake shoe 31 is supported by the front end portion of the anchor 41 so as to be rotatable and vertically movable. A lower end portion of the second brake shoe 32 is supported by the rear end portion of the anchor 41 so as to be rotatable and vertically movable.

The support of the anchor 41 enables the upper end portion of the first brake shoe 31 and the upper end portion of the second brake shoe 32 to open (separate) in the front-rear direction. The anchor 41 and the back plate 4 function as a torque receiving portion that applies braking force to the wheels by preventing rotation of the first brake shoe 31 and the second brake shoe 32 . The first brake shoe 31 and the second brake shoe 32 are connected by a return spring 90 and configured to return to the initial position when no force is applied from the driving device 5 .

The driving device 5 is a device (actuator) that drives the first brake shoe 31 and the second brake shoe 32 to press them against the rotating drum 2 . The driving device 5 of the first embodiment constitutes an electric mechanical brake (EMB) that drives the first piston 52 and the second piston 53 with an electric motor 55 . The driving device 5 is arranged between the upper end of the first brake shoe 31 and the upper end of the second brake shoe 32 .

The driving device 5 includes a fixed portion 51 , a first piston 52 , a second piston 53 , a linear motion converting portion 54 and an electric motor 55 . The fixed portion 51 is a portion of the driving device 5 that is fixed to the back plate 4 . The fixed portion 51 can also be said to be a housing of the driving device 5 . More specifically, the fixed portion 51 includes a first cylinder portion 511 , a second cylinder portion 512 and a housing portion 513 .

The first cylinder portion 511 constitutes a vehicle front portion of the fixing portion 51 and is arranged to face the first brake shoe 31 . The first cylinder portion 511 is formed in a tubular shape that opens forward of the vehicle. Inside the first cylinder portion 511, the front end portion of the screw shaft 541 of the direct motion converting portion 54 is arranged.

The second cylinder portion 512 constitutes the vehicle rear portion of the fixing portion 51 and is arranged so as to face the second brake shoe 32 . The second cylinder portion 512 is formed in a tubular shape that opens rearward of the vehicle. The second cylinder portion 512 is arranged coaxially with the first cylinder portion 511 . That is, the central axis of the first cylinder portion 511 and the central axis of the second cylinder portion 512 are positioned on the same straight line. A rear end portion of the screw shaft 541 of the direct motion converting portion 54 is arranged in the second cylinder portion 512 .

The accommodating portion 513 is a portion that accommodates the direct motion conversion portion 54 and is positioned between the first cylinder portion 511 and the second cylinder portion 512 . The housing portion 513 extends in the lateral direction of the vehicle so as to connect the first cylinder portion 511 and the second cylinder portion 512 to the electric motor 55 positioned on the vehicle body side (partially not shown). The accommodating portion 513 is inserted through a through hole of the back plate 4 and fixed to the back plate 4 .

The first piston 52 constitutes a movable portion that drives the first brake shoe 31 and presses it against the rotating drum 2 . The first piston 52 is arranged to face the upper end of the first brake shoe 31 . The first piston 52 is arranged to be movable back and forth in the first cylinder portion 511 . The first piston 52 includes a nut portion 521 and a contact portion 522 provided at the front end of the nut portion 521 .

The nut portion 521 is arranged so as to be movable in the front-rear direction and unrotatable with respect to the first cylinder portion 511 . That is, the first piston 52 and the first cylinder portion 511 are provided with a rotation stop mechanism (not shown) (for example, a rail groove and a rail) so that the first piston 52 does not rotate about the axis with respect to the first cylinder portion 511. engagement) is formed.

The nut portion 521 is screwed onto the threaded shaft 541 of the direct-acting converting portion 54 and moves back and forth as the threaded shaft 541 rotates. That is, when the screw shaft 541 rotates forward, the first piston 52 moves forward (toward the first brake shoe 31), and when the screw shaft 541 rotates backward, the first piston 52 moves rearward.

The contact portion 522 is provided at the front end portion of the nut portion 521 and is a portion that contacts the first brake shoe 31 . The abutting portion 522 has a shape in which a rearwardly extending slit 522a is formed in the front end face of a columnar member, that is, is formed in a concave shape as a whole. The slit 522a opens forward and upward. That is, the contact portion 522 is composed of left and right side walls 522b and a rear bottom wall 522c. It can also be said that the contact portion 522 protrudes forward from the nut portion 521 in a U shape. The upper rear end portion of the first brake shoe 31 is arranged within the slit 522 a of the contact portion 522 . The bottom wall 522c of the contact portion 522 and the upper rear end portion of the first brake shoe 31 are in contact with each other.

The second piston 53 is a piston member arranged in the second cylinder portion 512 so as to be movable in the front-rear direction. The second piston 53 is formed in the same shape (front-rear inversion) as the contact portion 522 of the first piston 52 . That is, the second piston 53 has a shape in which a slit 53a extending forward is formed in the rear end surface of a columnar member, that is, the second piston 53 is formed in a concave shape as a whole. The slit 53a is open rearward and vertically. That is, the second piston 53 is composed of left and right side walls 53b and a front bottom wall 53c.

The upper front end portion of the second brake shoe 32 is arranged inside the slit 53 a of the second piston 53 . The bottom wall 53c of the second piston 53 and the upper front end portion of the second brake shoe 32 are in contact with each other. The second piston 53 is arranged to receive force from the screw shaft 541 . Therefore, when the first piston 52 moves forward and presses the first brake shoe 31 , the reaction force of the first brake shoe 31 pressing the first piston 52 rearward is transferred via the screw shaft 541 to the second brake shoe 31 . It is transmitted to the piston 53. That is, the second piston 53 pushes the second brake shoe 32 rearward with the same force as the force with which the first piston 52 pushes the first brake shoe 31 . According to the law of action and reaction, the second piston 53 moves backward as the first piston 52 moves forward.

The linear motion converter 54 is a mechanism that converts the rotary motion of the output shaft 551 of the electric motor 55 into the linear motion of the first piston 52 . The direct-acting conversion portion 54 is configured to transmit power from the output shaft 551 to the screw shaft 541 via the reduction gear. It can be said that the first piston 52 constitutes a part of the direct-acting converter 54 .

The electric motor 55 is a drive source for the drive device 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 direct-acting converter 54 .

The first load sensor 61 and the second load sensor 62 are provided on at least one of the driving device 5 and the torque receiving portion (here, the back plate 4 and the anchor 41). and the force applied to the second brake shoe 32 in the vertical direction. Here, the force in the vertical direction is an example of a force in a direction different from the front-rear direction, which is the direction in which the driving device drives the friction member. The first load sensor 61 is configured to detect a downward force applied to the first brake shoe 31 . The second load sensor 62 is configured to detect an upward force applied to the second brake shoe 32 . The first load sensor 61 and the second load sensor 62 are provided in the driving device 5 .

More specifically, the first load sensor 61 is fixed to the first piston 52 and the first brake shoe 31 . The first load sensor 61 is of a strain gauge type, and includes a strain generating body 611 to which a strain gauge (not shown) is attached, and a transmission section 612 that amplifies the signal of the strain gauge and transmits it to the brake ECU 7. ing.

The strain-generating body 611 is a cylindrical metal member that is assumed to be elastically deformed by a load. The strain generating body 611 is disposed so as to pass through the contact portion 522 and the upper rear end portion of the first brake shoe 31 in the left-right direction. The strain generating body 611 includes a through hole 91 formed in each side wall 522b of the contact portion 522 and penetrating in the left and right direction, and a through hole 92 formed in the upper rear end portion of the first brake shoe 31 and penetrating in the left and right direction. and is inserted through. The transmitter 612 is fixed to the vehicle body side end of the strain body 611 .

When braking torque is generated while the vehicle is moving forward, a downward force is applied to the first brake shoe 31 due to reaction of the torque, as indicated by the arrow in FIG. When the first brake shoe 31 receives a downward force and tries to move downward, the strain body 611 fixed to the first piston 52 prevents the downward movement. That is, the downward force applied to the first brake shoe 31 is applied to the strain-generating body 611, and the central portion of the strain-generating body 611 elastically deforms downward. A downward force (load) applied to the first brake shoe 31 from this deformation is detected.

A second load sensor 62 is fixed to the second piston 53 and the second brake shoe 32 . Like the first load sensor 61, the second load sensor 62 is of a strain gauge type, and includes a strain-generating body 621 to which a strain gauge (not shown) is attached, and a signal from the strain gauge that is amplified and transmitted to the brake ECU 7. and a transmitter 622 .

The strain-generating body 621 is a columnar member, and is disposed so as to pass through the upper front end portions of the second piston 53 and the second brake shoe 32 in the left-right direction. The strain generating body 621 has a through hole 93 formed in each side wall 53b of the second piston 53 and penetrating in the left and right direction, and a through hole 94 formed in the upper front end portion of the second brake shoe 32 and penetrating in the left and right direction. is inserted into the The transmitter 622 is fixed to the end of the strain body 621 on the vehicle body side.

When braking torque is generated while the vehicle is moving forward, an upward force is applied to the second brake shoe 32 due to the torque reaction, as indicated by the arrow in FIG. When the second brake shoe 32 receives an upward force and attempts to move upward, the strain body 621 fixed to the second piston 53 prevents the upward movement. That is, the upward force applied to the second brake shoe 32 is applied to the strain-generating body 621, and the central portion of the strain-generating body 621 deforms upward. An upward force (load) applied to the second brake shoe 32 from this deformation is detected.

The brake ECU 7 is an electronic control unit including a processor, memory, and the like. Brake ECU7 controls the drive device 5 according to a braking request. When the brake ECU 7 forwardly rotates the output shaft 551 of the electric motor 55 in response to a braking request, the first piston 52 moves forward to press the first brake shoe 31 against the rotating drum 2, and the second piston 53 moves backward. to press the second brake shoe 32 against the rotating drum 2. As a result, a frictional force (resisting force) is generated against the rotation of the wheels and the rotating drum 2, and a braking force is applied.

The brake ECU 7 includes a calculator 71 that calculates a braking force (braking torque) based on detection values of the load sensors 61 and 62 . While the vehicle is moving forward, the greater the force with which the first piston 52 presses the first brake shoe 31 and the force with which the second piston 53 presses the second brake shoe 32, the greater the frictional force that is generated. The downward force applied to 31 and the upward force applied to the second brake shoe 32 are increased. That is, the greater the braking force applied while the vehicle is running, the greater the vertical force applied to each of the brake shoes 31 and 32 . The braking force and the vertical force applied to each brake shoe 31, 32 correspond to each other. Therefore, the calculator 71 can calculate the braking force based on the vertical force applied to each brake shoe 31 , 32 .

When a braking force is generated while the vehicle is moving backward, an upward force is applied to the first brake shoe 31 and a downward force is applied to the second brake shoe 32 . When the load sensors 61 and 62 are configured to detect any load in the vertical direction, or when an initial load is set, the force in the vertical direction applied by braking during backward movement of the vehicle can also be detected. In this case, since the brake ECU 7 can grasp that the vehicle is moving backward based on information from other ECUs, the calculation unit 71 calculates the braking force when the vehicle is moving backward based on the detection values of the load sensors 61 and 62. can be calculated.

(Effect of the first embodiment)
According to the first embodiment, the load sensors 61 and 62 may be arranged so as to receive vertical forces applied to the corresponding brake shoes 31 and 32 . Therefore, the load sensors 61 and 62 can be installed on the drive device 5 as in the above-described embodiment without being limited to the anchor 41 that directly receives the load of the brake shoes 31 and 32 . Thus, according to the first embodiment, by setting the detection direction of the load sensors 61 and 62 in the vertical direction, the degree of freedom in arranging the load sensors 61 and 62 can be improved.

Further, according to the first embodiment, since the load sensors 61 and 62 are provided in the driving device 5, the wiring of the load sensors 61 and 62 is arranged in the upper part of the wheel. This suppresses complication of wiring.

<Second embodiment>
The configuration of the second embodiment differs from the configuration of the first embodiment mainly in the configuration of the load sensor. The different parts will be described below with reference to FIGS. 3 and 4. FIG. In the description of the second embodiment, the description and drawings of the first embodiment can be referred to as appropriate.

The load sensor 63 of the second embodiment is a sensor that detects vertical force applied to the first brake shoe 31 . The load sensor 63 includes a strain body 631 , strain gauges 632 and 633 and an auxiliary member 634 .

The strain-generating body 631 is an annular metal member assumed to be elastically deformed by a load. The strain generating body 631 is fixed to the back plate 4 via, for example, a plurality of fastening members (not shown). Movement of the strain generating body 631 is restricted by the back plate 4 . The strain generating body 631 is arranged so as to partially surround the first brake shoe 31 with the auxiliary member 634 interposed therebetween. In summary, the strain body 631 is an annular member fixed to the back plate 4 so as to surround part of the first brake shoe 31 . Note that the strain-generating body 631 may be fixed to the driving device 5 . In this example, the strain body 631 is formed in an annular shape, but it does not have to be in an annular shape as long as it is formed so as to surround part of the first brake shoe 31 . For example, the strain-generating body 631 may be formed in a square shape. It can be said that the strain generating body 631 is not limited to an annular shape, and may be an angular annular shape having a polygonal outer shape.

The strain gauges 632 and 633 are sensors that measure the strain (deformation) of an object, as in the first embodiment, and their electrical resistance changes depending on the applied force. The strain gauge 632 has a plate shape and is fixed to the upper surface of the strain generating body 631 . The strain gauge 633 is plate-shaped and fixed to the lower surface of the strain generating body 631 .

The auxiliary member 634 is arranged between the first brake shoe 31 and the strain body 631 and is a member for transmitting the vertical force received by the first brake shoe 31 to the strain body 631 . The auxiliary member 634 is fixed to the upper rear end portion of the first brake shoe 31 . The auxiliary member 634 of this example is formed in an elliptical cylindrical shape having an elliptical cross section with a long axis extending in the vertical direction and a short axis extending in the horizontal direction. The length of this long axis is slightly smaller than the inner diameter of the strain body 631 . In summary, the auxiliary member 634 is a member that is positioned inside the strain body 631 and fixed to the first brake shoe 31 so as to transmit the vertical force received by the first brake shoe 31 to the strain body 631 . be. Since the auxiliary member 634 has an elliptical cylindrical shape, stress concentration on the strain generating body 631 of the auxiliary member 634 is suppressed.

It should be noted that the load sensor 63 may be provided with transmitters 635 and 636 . The transmitter 635 amplifies the signal of the strain gauge 632 and transmits it to the brake ECU 7 . Similarly, the transmitter 636 amplifies the signal of the strain gauge 633 and transmits it to the brake ECU 7 . The strain gauges 632, 633 and the corresponding transmitters 635, 636 can be connected by wiring, for example. The arrangement positions of the transmission units 635 and 636 can be set arbitrarily.

According to the configuration of the second embodiment, when a downward force is applied to the first brake shoe 31 during braking while the vehicle is moving forward, the force is transmitted to the strain generating body 631 via the auxiliary member 634 . Since the movement of the strain-generating body 631 is restricted, the lower inner peripheral surface of the strain-generating body 631 is pressed by the auxiliary member 634, and the strain-generating body 631 is deformed. This deformation is detected by at least the strain gauge 633 .

Also, in braking while the vehicle is moving backward, an upward force is applied to the first brake shoe 31, the upper inner peripheral surface of the strain body 631 is pressed by the auxiliary member 634, and the strain body 631 is deformed. This deformation is detected by at least the strain gauge 632 . As a result, the amount of deformation of the strain generating body 631 is transmitted to the brake ECU 7, and the calculating section 71 calculates the braking force based on the amount of deformation of the strain body 631, as in the first embodiment.

As described above, even with the configuration of the second embodiment, the load sensor 63 can be arranged in the upper part of the wheel by taking advantage of the degree of freedom of arrangement, and the same effects as those of the first embodiment can be exhibited. A configuration similar to that of the load sensor 63 may be provided for the second brake shoe 32 . Also, only one of the strain gauges 632 and 633 may be provided.

<Third Embodiment>
The configuration of the third embodiment differs from the configuration of the first embodiment mainly in the configuration of the load sensor. The different parts will be described below with reference to FIG. In the explanation of the third embodiment, the explanations and drawings of the first and second embodiments can be referred to as appropriate.

The load sensor 64 of the third embodiment is a sensor provided on the first piston 52 of the driving device 5 and detects a vertical force applied to the first brake shoe 31 . The load sensor 64 includes a strain body 641 and strain gauges 642 . The strain generating body 641 is arranged in the slit 522 a of the contact portion 522 . The strain generating body 641 is arranged below the first brake shoe 31 .

One end (rear end) of the strain generating body 641 is fixed to the bottom wall 522c of the contact portion 522, and the upper surface of the other end (front end) is configured to contact or face the first brake shoe 31 with a gap. It is a plate-like member extending in the front-rear direction. A front end portion of the strain generating body 641 protrudes upward. The strain-generating body 641 is formed so that its vertical width is smaller than its horizontal width so that it can be easily elastically deformed in the vertical direction.

A strain gauge 642 is fixed to the lower surface of the strain generating body 641 . A signal from the strain gauge 642 is transmitted to the brake ECU 7 via, for example, a transmission section (not shown) that amplifies the signal. When a downward force is applied to the first brake shoe 31 during braking while the vehicle is moving forward, the first brake shoe 31 presses the strain body 641 downward, deforming one end (front end) of the strain body 641 downward. . This deformation is transmitted to the brake ECU 7 , and the braking force is calculated by the calculation section 71 .

In addition, the initial load can be set to the load sensor 64 by setting the state in which the strain generating body 641 is pressed against the first brake shoe 31 in advance and deformed as the initial state. As a result, when the first brake shoe 31 receives an upward force and moves upward, the amount of deformation of the strain body 641 becomes smaller than in the initial state, and the change can be detected. With this configuration, the change in the load of the strain body 641 is detected even during braking while the vehicle is moving backward, and the calculating section 71 can calculate the braking force. The configuration in which the initial load is applied to the load sensor can also be applied to the first embodiment, for example.

With the configuration of the third embodiment, the load sensor 64 is also provided in the driving device 5, and the same effects as those of the first embodiment are exhibited. Note that the configuration of the load sensor 64 may be provided on the second piston 53 . In this case, the strain body 641 is arranged above the second brake shoe 32 in the slit 53a, for example.

<Fourth Embodiment>
The configuration of the fourth embodiment differs from the configuration of the first embodiment mainly in the configurations of the load sensor and the piston. The different parts will be described below with reference to FIG. In the explanation of the fourth embodiment, the explanations and drawings of the first to third embodiments can be referred to as appropriate.

Unlike the first embodiment, the slit 522a of the first piston 52 of the fourth embodiment opens forward and in the left-right direction. That is, the contact portion 522 is composed of upper and lower side walls 522d and a bottom wall 522c. The upper rear end portion of the first brake shoe 31 is arranged within the slit 522a.

The load sensor 65 of the fourth embodiment is a sensor provided on the first piston 52 of the driving device 5 and detects a vertical force applied to the first brake shoe 31 . The load sensor 65 includes a sensor portion 651 having a piezoelectric element (not shown) and a preload portion 652 that applies an initial load to the sensor portion 651 .

The sensor part 651 is a part that is arranged below the first brake shoe 31 and detects a downward force applied to the upper surface of the first brake shoe 31 . The sensor portion 651 is fixed on the lower wall 522d of the contact portion 522. As shown in FIG. The upper surface of the sensor portion 651 is in contact with the first brake shoe 31 .

The preload portion 652 is provided on the upper wall 522 d of the contact portion 522 . The sensor portion 651 and the preload portion 652 are arranged so as to sandwich the first brake shoe 31 from above and below. The preload portion 652 includes a pressing portion 652a, a spring 652b, and a pedestal portion 652c. The pressing portion 652a is a member that contacts the first brake shoe 31 and presses it downward. The pressing portion 652a is formed in a spherical shape. The pressing portion 652a is arranged to face the sensor portion 651 with the first brake shoe 31 interposed therebetween.

The spring 652b is a biasing member that biases the pressing portion 652a downward, having a lower end fixed to the pressing portion 652a and an upper end fixed to the pedestal portion 652c. The pedestal portion 652 c is a member that functions as a pedestal for the spring 652 b and is fixed to the contact portion 522 . The pedestal portion 652c is fixed by, for example, press fitting into a through hole 522e formed in the upper wall 522d and penetrating vertically. The pedestal portion 652c may be configured by a portion of the upper wall 522d.

In the initial state, that is, when the electric motor 55 is not driven, the preload portion 652 presses the first brake shoe 31 toward the sensor portion 651 with a predetermined force. Accordingly, in the initial state, the sensor section 651 detects downward force. In other words, the initial value of the load sensor 65 is greater than zero.

When a downward force is applied to the first brake shoe 31 during braking while the vehicle is moving forward, the sensor portion 651 is pressed downward, and the detected value of the load sensor 65 increases from the initial value (initial value>0). When an upward force is applied to the first brake shoe 31 during braking while the vehicle is moving backward, the first brake shoe 31 pushes the pressing portion 652a upward, and the downward pressing force on the sensor portion 651 becomes smaller than in the initial state. . As a result, the detected value of the load sensor 65 becomes smaller than the initial value. In other words, the load sensor 65 having this configuration can detect the braking force not only when the vehicle is moving forward but also when the vehicle is moving backward.

Even with the configuration of the fourth embodiment, the load sensor 65 can be provided in the driving device 5, and the same effects as those of the first embodiment can be exhibited. Note that the configuration of the load sensor 65 may be provided in the second piston 53 . Even in this case, the sensor portion 651 and the preload portion 652 are arranged so as to sandwich the second brake shoe 32 from above and below. For example, the sensor part 651 is fixed to the lower surface of the upper wall of the second piston 53 and the preload part 652 is provided on the lower wall of the second piston 53 .

<Others>
The present invention is not limited to the above embodiments. For example, in the present invention, the braking force may be calculated based on forces in different directions with respect to the direction in which the driving device drives the friction member. The braking force may be calculated based on the force in the direction tilted with respect to the direction. For example, the auxiliary member, the strain-generating body, and the strain gauge may be attached so as to be intentionally inclined with respect to the brake shoe. If the assembly of the auxiliary member is tilted with respect to the brake shoe due to variations in the material, the auxiliary member and the elastic body come into contact with each other when the brake shoe moves forward, hindering the forward movement of the brake shoe. can be considered. In order to suppress this phenomenon, as shown in FIG. 7, the auxiliary member 634, the strain-generating body 631, and the strain gauges 632 and 633 are intentionally inclined so that the auxiliary member 634 and the strain-generating member 634 and the strain-generating member 634 are tilted when the first brake shoe 31 advances. The gap on the side with which the body 631 contacts is increased. As a result, even when the auxiliary member 634 is attached to the first brake shoe 31 inconsistently, it is possible to suppress a decrease in braking force due to contact between the auxiliary member 634 and the strain-generating body 631 . It can be said that the load sensor 6 detects a force including a vertical force component. In addition, the present invention can be applied to, for example, a duo-servo type drum brake regardless of the type of drum brake. Further, the driving device 5 may be a hydraulic driving device that drives the piston by hydraulic pressure. Also, if the load on the leading shoe can be detected, the load on the trailing shoe can be estimated. Therefore, a load sensor may be provided for only one of the first brake shoe 31 and the second brake shoe 32 .

A load sensor that detects the vertical force of the brake shoe may be provided on the anchor 41 . For example, a load sensor may be provided at the connecting portion between the anchor 41 and the first brake shoe 31 to detect downward movement of the first brake shoe 31 with respect to the anchor 41 . For example, the load sensor 64 may be provided on the anchor 41 .

DESCRIPTION OF SYMBOLS 1... Vehicle braking device, 2... Rotating drum (brake rotating body), 31... First brake shoe (friction member), 32... Second brake shoe (friction member), 4... Back plate (torque receiving portion), 41 . . Anchor (torque receiving portion) 5 .. Driving device 61 to 65 .. Load sensor 71 .

Claims (3)

a brake rotor that rotates with the wheel;
a friction member 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 driving device that drives the friction member and presses it against the brake rotor;
a load sensor provided in at least one of the driving device and the torque receiving portion and detecting a force in a direction different from a direction in which the driving device drives the friction member;
a calculation unit that calculates the braking force based on the detected value of the load sensor;
A vehicle braking device. 2. The vehicle braking system according to claim 1, wherein said load sensor is provided in said driving device. The load sensor is
a strain body fixed to at least one of the torque receiving portion and the driving device so as to surround a portion of the friction member;
a strain gauge fixed to at least one of an upper surface and a lower surface of the strain body;
an auxiliary member positioned inside the strain body and fixed to the friction member so as to transmit the force in the different direction received by the friction member to the strain body;
The vehicle braking system according to claim 1, comprising:

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