JP2008248901A - Braking force detection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a braking force detection device capable of preventing the occurrence of distortion unwanted in a caliper bracket and improving detection accuracy. <P>SOLUTION: In the braking force detection device, a projection is provided to a circumferential end part of a pad back plate so that a portion in contact with the circumferential end part and a brake load receiving part of the caliper bracket is further on the outside in the radial direction of a brake disc than a tangential line passing the pressing center of an arc passing the pressing center of a piston with the rotational center of the brake disc as the center. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a braking force detection device that detects a braking force (braking force) by a disc brake.

  When performing braking control of a vehicle, braking force is one of important information. For example, if the braking force actually applied can be detected when the brake is applied, the state of the road surface can be easily estimated. If the road surface condition is known, ABS control (anti-skid brake system control) can be performed more accurately, and the vehicle can be safely stopped at a short distance.

  In addition, if the braking force applied to each wheel can be detected when the vehicle is turned or when braking is performed on a road surface having a low friction coefficient (μ), the braking force of each wheel can be individually controlled. Can be done more safely.

  Conventionally, a disc brake that detects a braking force by providing a load cell or attaching a strain gauge to a support engagement portion of a fixed support of a friction pad of a disc brake has been developed.

  However, in the vicinity of the friction pad, it tends to become high temperature due to heat generated by friction between the friction pad and the brake disk. Considering heat resistance, environmental resistance, life, etc. As inappropriate.

Therefore, a braking force measuring device that is not easily affected by heat is proposed in Japanese Patent Laid-Open No. 6-123665. The braking force measuring device disclosed in this publication includes a support member having a pair of substantially vertical beams interposed between a brake caliper and a knuckle arm, and detection means for detecting displacement of the beams. Is done.
JP-A-6-123665

  According to the braking force measuring device described in Patent Document 1 described above, there is an advantage that it is not easily affected by heat, but since the braking force measuring device is H-shaped in cross section, the brake disc shaft between the caliper bracket and the knuckle There is a problem that the distance in the direction becomes large and the measuring apparatus becomes large. It is also difficult to place a displacement detection device between the two beams.

  Furthermore, in the braking force measuring device described in Patent Document 1, since the deformation due to the braking force acts in the opposite direction when the vehicle is moving forward and backward, strain is also generated in both the tension and compression directions, and the zero point of the sensor output There is a problem of stabilization of the detection output such that correction is difficult.

  Therefore, the present applicant has previously proposed a braking force detection device that can easily correct the zero point of the sensor output and stabilize the detection output (Japanese Patent Application No. 2006-252973). According to the brake force detecting device of the prior application, the sensor plate is attached to the connecting portion so as to be subjected to the deformation in the tensile direction generated at the connecting portion. The deformation is one direction of tension, and the zero point correction of the sensor output is facilitated, and the detection output can be stabilized.

  By the way, according to the brake force detection device of this prior application, when the brake is applied when the vehicle moves forward, the brake disk rotates while the pad presses against the brake disk. The pad back plate to which the pad is bonded is pressed against the brake load receiving portion of the caliper bracket.

  At this time, the brake load receiving portion extends across a tangent line passing through the pressing center of the arc passing through the pressing center of the piston centering on the rotation center of the brake disk across the radial direction of the brake disk. The contact point of the brake load receiving part is above or below the tangent and is not stable.

  When the pad back plate comes into contact with the brake load receiving part below the tangent line, a moment is generated in which the end of the pad back plate on the opposite side moves radially outward with this contact point as a fulcrum. There is a problem in that the brake load receiving portion of the sensor plate is bent outward, and the inner bridge is pulled accordingly, and unnecessary distortion may occur in the sensor plate.

  Accordingly, an object of the present invention is to provide a brake force detecting device that can prevent the caliper bracket from being distorted due to unnecessary pulling of the caliper bracket and can obtain a linear distortion characteristic during braking.

  According to the present invention, the wheel is rotatably supported, and is attached to the wheel support that is supported by the vehicle body by the suspension, the brake disk that rotates together with the wheel, and the pad back plate that is disposed on both sides of the brake disk. A pair of friction pads, a brake caliper that incorporates a pushing member that advances and retreats in a direction parallel to the axis of the brake disc that pushes the friction pad toward the brake disc, and the brake disc of the friction pad. A caliper bracket for supporting the friction pad on both sides in a circumferential direction, a caliper bracket that supports the brake caliper, and is fixed to the wheel support body, and comprising the caliper bracket A strain detecting means for detecting the strain during braking. At least one of the circumferential end of the pad back plate or the brake load receiving portion of the caliper bracket receiving the brake load in contact with the circumferential end is provided with the circumferential end and the brake load receiving portion. A protrusion is provided so that a portion of the brake disk is located radially outside the tangent line passing through the pushing center of the pushing member of the pushing member centering on the rotation center of the brake disk. A brake force detecting device is provided.

  According to the present invention, when the brake torque is generated in the forward direction, the protrusion is provided so as to be radially outward of the brake disk from the tangent line passing through the push center of the push member. Therefore, it is possible to prevent generation of a moment in which the opposite side in the circumferential direction of the pad back plate moves outward in the radial direction with the inner side in the radial direction of the brake disc as a fulcrum from the tangent.

  As a result, there is no distortion of the caliper bracket caused by pushing the brake load receiving part of the caliper bracket on the entry side due to this moment, and only the distortion caused by the bending of the brake load receiving part of the caliper bracket on the delivery side. Since it can detect, a linear distortion characteristic can be obtained and the detection accuracy of a braking force can be improved.

  Even when the brake torque is generated in the reverse direction, it is possible to prevent the occurrence of the moment generated when the pad back plate hits the brake load receiving portion of the caliper bracket, similarly to the case where the brake torque is generated in the forward direction.

  As a result, there is no distortion of the caliper bracket caused by pushing the brake load receiving part of the caliper bracket on the delivery side due to this moment, and only the distortion caused by the bending of the brake load receiving part of the caliper bracket on the entry side is generated. Since it can detect, a linear distortion characteristic can be obtained and the detection accuracy of a braking force can be improved.

  Hereinafter, an example of the braking force detection device of the present invention will be described. FIG. 1 is an external perspective view of a disc brake equipped with a brake force detection device. FIG. 2 is a left side view of FIG.

  As shown in FIGS. 1 and 2, the brake disc (disc rotor) 2 is fixed to a wheel (not shown) and rotates together with the wheel. Reference numeral 4 denotes a knuckle (wheel support), which rotatably supports the wheel and is connected to the vehicle body via a suspension (not shown).

  A caliper bracket 8 is attached to the knuckle 4 with bolts 10 and 12. The caliper bracket 8 supports a pair of friction pads 19 and 21 disposed on both sides in the axial direction of the brake disk 2 on both the turn-in side and the turn-out side of the brake disk 2. The friction pads 19 and 21 are bonded to the pad back plates 18 and 20, respectively.

  The caliper bracket 8 is slidably fitted with two slide pins 15 and 17 fixed to the brake caliper 6 by two bolts 14 and 16, and the brake caliper 6 is shown in FIG. Thus, a piston (pushing member) 24 is built in that moves forward and backward in a direction parallel to the axis of the brake disc 2 and presses the friction pads 19 and 21 toward the brake disc 2.

  The brake caliper 6 integrally has a wheel cylinder 22, and a piston 24 is fitted in the wheel cylinder 22. The hydraulic pressure from the brake master cylinder is supplied to the piston chamber 26 via the hydraulic pressure supply port 28.

  The brake disc 2 is connected to the hub 3. When hydraulic pressure is supplied from the brake master cylinder into the piston chamber 26 via the hydraulic pressure supply port 28, the piston 24 is pushed leftward in FIG. 3 and the pad 19 is pressed against the brake disc 2.

  The brake caliper 6 moves to the right by the reaction force of the piston 24 pressing the pad 19 against the brake disc 2, and the opposite pad 21 is also pressed against the brake disc 2 to brake the rotation of the brake disc 2.

  FIG. 4 shows a main part of a braking force detection device to which the present invention can be applied. 5 is a sectional view taken along line 5-5 of FIG. 4, and FIG. 6 is a plan view of FIG. As apparent from FIG. 6, the caliper bracket 8 includes a pair of brake load receiving portions 8a and 8b, an inner connecting portion (inner bridge portion) 8c for connecting the brake load receiving portions 8a and 8b, and an outer connecting portion ( Outer bridge portion) 8d.

  A recess 55 is formed on the radially outer side surface of the brake disk 2 of the inner connecting portion 8 c of the caliper bracket 8. A sensor plate 56 is fixed to the recess 55 by a pair of bolts 58 and 60.

  As shown in FIG. 6, a brake torque sensor 48 composed of a strain gauge is attached to the sensor plate 56, and the brake torque sensor 48 is connected to an amplifier 50 that amplifies the output.

  When the brake is applied when the vehicle moves forward, the brake disc rotates while the pads 19 and 21 press the brake disc 2, so that the pads 19 and 21 are dragged by the brake disc 2 and move in the rotation direction of the brake disc. Then, the pad back plates 18 and 20 are in pressure contact with the brake load receiving portion 8 b of the caliper bracket 8.

  Since the caliper bracket 8 is fixed to the knuckle 4 by screwing the bolts 10 and 12 into the screw holes 32 and 34, the caliper bracket 8 is attached to the sensor plate 56 fixed to the radially outer side surface of the brake disk 2 of the inner connecting portion 8c. Generates a tensile load, and the tensile load causes the sensor plate 56 to deform in the tensile direction.

  This deformation is detected by the brake torque sensor 48, and the braking force is detected based on the amount of strain of the sensor plate 56 by amplifying the output of the brake torque sensor 48 with the amplifier 50 connected to the brake torque sensor 48.

  Since the distortion of the sensor plate 56 occurs only when the brake torque is transmitted through the brake load receiving portion 8b and the inner connecting portion 8c of the caliper bracket 8, it is difficult to be affected by vertical force and lateral force. Brake force can be detected well.

  When the brake is applied when the vehicle is reverse, the brake disc 2 rotates in the opposite direction to the forward direction, so that the pads 19 and 21 are dragged by the brake disc 2 and the pad back plates 18 and 20 are brake load receiving portions. Press contact 8a.

  Therefore, a tensile load is generated in the inner connecting portion 8c on the radially outer side of the brake disc 2 with respect to the line connecting the screw holes 32 and 34 even when retreating. Due to this tensile load, the sensor plate 56 is deformed in the tensile direction, and the brake torque is detected by the brake torque sensor 48 based on the deformation amount of the sensor plate 56.

  Therefore, since the deformation of the sensor plate 56 due to the braking force is in one direction of tension both when the vehicle is moving forward and backward, the zero point correction of the sensor output is facilitated, and the detection output can be stabilized.

  In the brake force detection device described above, the output of the brake torque sensor 48 formed of a strain gauge when the brake is applied during reverse is the output of the brake torque sensor 48 when the brake is applied during forward as shown in FIG. And symmetric about the vertical axis.

  Therefore, the resolution of the brake torque sensor 48 can be improved by a factor of about two compared to the case where the brake torque sensor 48 formed of a strain gauge undergoes deformation in the tensile direction during forward movement and undergoes deformation in the compression direction during backward movement. .

  FIG. 8 shows a main part of a braking force detection device of a comparative example for explaining the problem to be solved by the present invention. FIG. 8 is obtained by adding a pad back plate 18 which is omitted in FIG.

  The pad back plate 18 has projecting end portions 18a and 18b. The brake load receiving portion 8a has a recess 9 for receiving the projecting end portion 18a. The brake load receiving portion 8b has a recess for receiving the projecting end portion 18b. 11 is formed.

  Reference numeral 24 a denotes a pressing center of the piston 24, and 24 b denotes a pressing portion of the piston 24. The brake load receiving portion 8b of the caliper bracket 8 extends from the radially inner side to the outer side of the brake disk 2 with respect to a tangent line passing through the pressing center 24a of the piston 24 centered on the rotation center of the brake disk 2 and passing through the pressing center. It extends over.

  Therefore, when the brake is applied when the vehicle moves forward, the pads 19 and 21 rotate in the direction of the arrow 62 while the pads 19 and 21 press the brake disc 2, so that the pads 19 and 21 are dragged by the brake disc 2 and The pad back plates 18 and 20 move in the rotational direction and come into pressure contact with the brake load receiving portion 8b of the caliper bracket 8, but the pressure contacts are not stable because they are inside or outside the tangent.

  When the pressure contact point between the pad back plate 18 and the brake load receiving portion 8b is radially inward of the tangent line as indicated by an arrow 64, the opposite side of the pad back plate 18 in the circumferential direction is located at the pressure contact point as a fulcrum. As shown by an arrow 66, a moment that moves outward in the radial direction is generated.

  As a result, the protruding end 18a of the pad back plate 18 pushes up the protrusion 23 of the brake load receiving portion 8a, the brake load receiving portion 8a bends outward as indicated by an arrow 68, and the inner bridge 8c is pulled accordingly. Unnecessary distortion occurs in the sensor plate 56.

  FIG. 9 shows a main part of a braking force detection device according to an embodiment of the present invention that solves this problem. FIG. 10 is similar to FIG. 9, and shows a tangent line 76 passing through the pressing center 24 a of the arc 74 passing through the pressing center 24 a of the piston 24 around the rotation center of the brake disk 2. FIG. 11 is an enlarged view of a main part of FIG.

  As best shown in FIG. 10, the projecting end portions 18a, 18b of the pad back plate 18 in the circumferential direction have portions where the projecting end portions 18a, 18b and the brake load receiving portions 8a, 8b come into contact with each other. Further, protrusions 70 and 72 are provided so as to be radially outward of the brake disc 2. The pad back plate 20 is also provided with a protrusion at a similar position.

  Therefore, when the brake is applied when the vehicle moves forward, since the brake disk 2 rotates in the direction of the arrow 62 while the pads 19 and 21 press the brake disk 2, the pads 19 and 21 are dragged by the brake disk 2. The brake disc 2 moves in the rotational direction, and the protrusions 72 of the pad back plates 18 and 20 are pressed against the brake load receiving portion 8 b of the caliper bracket 8 as indicated by an arrow 74.

  As described above, according to the present embodiment, the pad back plates 18 and 20 are pressed against the brake load receiving portion 8b on the outer side in the radial direction of the brake disk 2 with respect to the tangent line 78. No moment is generated in which the opposite end 18a moves outward in the radial direction of the brake disc 2.

  As a result, there is no distortion of the sensor plate 56 due to the pulling of the inner bridge 8c caused by pushing up the brake load receiving portion 8a of the caliper bracket 8 on the entrance side by this moment, and the brake load on the caliper bracket 8 on the delivery side. Since only the strain of the sensor plate 56 generated by the bending of the receiving portion 8b can be detected, linear strain characteristics can be obtained, and the accuracy of the braking force detection device can be improved.

  In the embodiment described above, the protrusion 72 is formed on the protruding end portion 18b of the pad back plate 18, but the present invention is not limited to this, and the recess of the brake load receiving portion 8b as shown in FIG. 11 may be formed with protrusions 78.

  With reference to FIG. 13, the operation of the comparative example shown in FIG. When the brake is applied when the vehicle is moving backward, the brake disc 2 rotates in the opposite direction to that when moving forward as indicated by the arrow 82, so that the pads 19 and 21 are dragged by the brake disc 2 and the pad back plate 18, 20 is in pressure contact with the brake load receiving portion 8a.

  As indicated by an arrow 84, when the protruding end portion 18 a of the pad back plate 18 is in pressure contact with the brake load receiving portion 8 a on the radially inner side of the brake disk 2 with respect to the tangent line 78, the pad back plate 18 is opposite to the circumferential direction. As shown by an arrow 86, a projecting end portion 18 b of the brake disc 2 is moved outward in the radial direction, and this moment pushes up the protrusion 25 of the brake load receiving portion 8 b, and the brake load receiving portion 8 b is indicated by an arrow 88. As shown in the figure, the sensor plate 56 is bent outward and unnecessary distortion occurs.

  In the embodiment of the present invention, as shown in FIG. 14, a portion where the protruding end portion 18 a of the pad back plate 18 and the brake load receiving portion 8 a come into contact with each other is outside the tangent line 78 in the radial direction of the brake disk 2. Since the protrusion 70 is formed on the protruding end 18 a, the moment that the circumferentially opposite end 18 b of the pad back plate 18 moves outward in the radial direction of the brake disk 2 is not achieved.

  Therefore, there is no distortion of the sensor plate 56 due to the pulling of the inner bridge 8c caused by pushing the brake load receiving portion 8b of the caliper bracket 8 on the delivery side by this moment, and the brake load receiving on the caliper bracket 8 on the entry side. Since only the strain of the sensor plate 56 generated by the bending of the portion 8a can be detected, linear strain characteristics can be obtained even in the reverse direction, and the accuracy of the braking force detection device can be improved.

1 is an external perspective view of a disc brake to which a brake force detection device of the present invention can be applied. It is a left view of the disc brake of FIG. It is a schematic sectional drawing of a disc brake. It is a front view of the caliper bracket which attached the brake torque sensor. FIG. 5 is a sectional view taken along line 5-5 of FIG. FIG. 5 is a plan view of FIG. 4. It is a figure which shows the relationship between a brake torque and a strain gauge (brake torque sensor) output. It is a front view which shows the principal part of a comparative example. It is a front view which shows the principal part of the brake force detection apparatus which concerns on this invention embodiment. FIG. 10 is a view similar to FIG. 9 and showing an arc passing through the pressing center of the piston centered on the rotation center of the brake disc and a tangent line of the arc passing through the pressing center. It is a principal part enlarged view of FIG. It is a figure which shows the principal part of other embodiment of this invention. It is a front view explaining the effect | action of the comparative example at the time of vehicle reverse. It is a front view explaining the effect | action of this invention embodiment at the time of vehicle reverse.

Explanation of symbols

2 Brake disc (disc rotor)
4 Knuckle 6 Brake caliper 8 Caliper bracket 8a, 8b Brake load receiving part 8c Inner connecting part (inner bridge)
8d Outer connection part (outer bridge)
18, 20 Pad back plate 19, 21 Pad 48 Strain gauge (brake torque sensor)
56 Sensor plates 70, 72 Protrusions 76 Arc 78 passing through the piston pressing center centered on the center of rotation of the brake disk 78 Tangent line passing through the pressing center and in contact with the arc

Claims (1)

A wheel support that supports the wheel rotatably and is supported by the vehicle body by a suspension;
A brake disc that rotates with the wheels,
A pair of friction pads respectively bonded to the pad back plate disposed on both sides of the brake disc;
A brake caliper having a built-in pushing member that advances and retracts in a direction parallel to the axis of the brake disc that pushes the friction pad toward the brake disc;
A caliper bracket that supports the friction pad on both sides of the brake pad in the circumferential direction of the brake pad, supports the brake caliper, and is fixed to the wheel support;
A brake force detection device for a brake device comprising:
Comprising strain detecting means for detecting strain at the time of braking generated in the caliper bracket;
At least one of the circumferential end portion of the pad back plate or the brake load receiving portion of the caliper bracket receiving the brake load in contact with the circumferential end portion includes the circumferential end portion and the brake load receiving portion. A protrusion is provided so that a portion of the brake disc is located radially outside the tangent line passing through the pushing center of the pushing member of the pushing member about the rotation center of the brake disc. Brake force detection device characterized by that.

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