JP6472287B2 - Brake device for vehicle - Google Patents

Description

  The present invention has a contraction position restricting strut that is provided between a pair of brake shoe webs that are extended and driven by a wheel cylinder and that can be extended by rotation of an adjustment gear, and a pair of feed claws that engage with the adjustment gear. An adjustment lever that is rotatably supported by the web of one of the brake shoes, and the adjustment lever that is rotated to the side that rotates the adjustment gear in a direction in which the contraction position regulating strut is extended. A brake gap automatic adjusting means configured to adjust a gap between the pair of brake shoes and the brake drum, which is configured by an urging adjustment spring, and a pair of brake shoes attached to the contraction position side regulated by the contraction position regulation strut. Provided between the pair of brake shoes. A parking brake engaged with one end portion of the contraction position regulating strut and having one end portion pivotally supported on the web of the other brake shoe of the pair of brake shoes and a drum brake having a return spring A brake cable provided with a brake lever and driven by an electric actuator rotates the parking brake lever so that the contraction position regulating strut is pressed against the web of the one brake shoe by pulling the brake cable. The present invention relates to a vehicular brake device that is capable of obtaining a parking brake state and is connected to the parking brake lever.

  Drum brake having automatic braking gap adjusting means that automatically compensates for the gap corresponding to the amount of wear of the lining when the brake gap between the brake shoe and the brake drum increases by a predetermined amount or more due to wear of the brake shoe lining. Is known from US Pat.

Japanese Patent Laid-Open No. 2002-323076

  By the way, as the brake drum temporarily increases in diameter due to thermal expansion, the brake clearance automatic adjustment means operates in response to the expansion of the braking clearance between the brake drum and the brake shoe. When the brake drum is cooled to the original diameter, the brake gap between the brake drum and the brake shoe becomes small and the over-adjusted state occurs. May occur. In particular, in a drum brake in which a parking brake state can be obtained by operating an electric actuator, there is a possibility that problems such as errors due to a decrease in the braking gap may occur. On the other hand, in the one disclosed in the above-mentioned Patent Document 1, over adjustment is achieved by automatically stopping the operation of the braking gap automatic adjusting means at a predetermined temperature or higher by the action of the thermal expansion means made of bimetal or shape memory alloy. However, in order to change the temperature at which the operation of the braking gap automatic adjusting means is automatically stopped, it is necessary to replace the thermal expansion means.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a vehicle brake device that can prevent the occurrence of an over-adjustment state while making it unnecessary to change parts.

  In order to achieve the above object, the present invention is provided between a pair of brake shoe webs extended and driven by a wheel cylinder, and is engaged with a contraction position regulating strut that can be extended by rotation of an adjustment gear. An adjusting lever that is rotatably supported by the web of one of the pair of brake shoes, and the adjusting gear is rotated in a direction in which the contraction position regulating strut is extended. A brake gap automatic adjusting means for adjusting a gap between the pair of brake shoes and brake drum, and a contraction position side regulated by the contraction position regulation strut, which is composed of an adjustment spring for rotating and biasing the adjustment lever on the side A pair of the brake shoes is urged to a pair A drum brake having a return spring provided between rake shoes has one end pivotally supported by the web of the other brake shoe of the pair of brake shoes, and at one end of the contraction position regulating strut. An engaging parking brake lever is attached, and the parking brake lever is pulled so that the brake cable pulled by the electric actuator presses the contraction position restricting strut against the web of the one brake shoe by pulling the brake cable. In the vehicular brake device connected to the parking brake lever so as to be able to obtain a parking brake state by rotating, a control unit for controlling the operation of the electric actuator is configured to perform braking at a predetermined temperature or higher with the drum brake. When the brake cable is determined to have occurred, the brake cable is pulled only by rotating the parking brake lever to the side where the one brake shoe is expanded within a range less than the shoe clearance with the brake drum. The first feature is to control the electric actuator as described above.

  According to the present invention, in addition to the configuration of the first feature, the control unit performs the braking according to the amount of heat generated by the drum brake calculated based on the vehicle deceleration and the braking frequency exceeding a predetermined threshold. A second feature is that it is determined that the heat is equal to or higher than the predetermined temperature.

  According to the first aspect of the present invention, when the control unit determines that braking heat of a predetermined temperature or higher is generated, the brake shoe on the side where the adjustment lever is supported is within a range less than the shoe clearance. The brake cable is pulled by the electric actuator only by rotating the parking brake lever to the side to be expanded. At this time, if the pair of brake shoes is expanded against the spring force of the return spring by the operation of the wheel cylinder, the parking brake lever remains engaged and the contraction position regulating strut and one brake shoe are not connected. Although there is a slight gap, the length of the gap along the longitudinal direction of the contraction position regulating strut is smaller than the value required to extend the contraction position regulation strut by the rotation of the adjustment gear, and therefore the braking gap The automatic adjusting means does not operate so as to displace the reduced diameter position of the brake shoe to the outside, and the occurrence of an over-adjusted state of the braking gap automatic adjusting means can be prevented. Thereby, it is possible to suppress the occurrence of drag and to suppress the occurrence of problems such as errors when the parking brake state is obtained by the operation of the electric actuator controlled by the control unit. In addition, when changing the temperature at which the operation of the automatic braking gap adjusting means is automatically changed, the control program of the control unit may be changed, so that no part change is required.

  According to the second feature of the present invention, the braking heat of the drum brake can be easily determined based on the vehicle body deceleration and the braking frequency.

It is a front view of a drum brake. FIG. 2 is a view taken in the direction of arrow 2 in FIG. 1. It is a side view which shows the connection state of the brake cable to a parking brake lever. FIG. 4 is a cross-sectional view taken along line 4-4 of FIG.

  The embodiment of the present invention will be described with reference to FIGS. 1 to 4 attached herewith. First, in FIGS. 1 and 2, a drum brake 5 is provided on, for example, the left rear wheel of a four-wheel vehicle. The drum brake 5 is slidably contacted with a fixed back plate 6 and an inner periphery of a brake drum 7 that rotates together with the left rear wheel, and first and second brake shoes 8 disposed in the back plate 6. , 9, a wheel cylinder 10 fixed to the upper part of the back plate 6 so that the first and second brake shoes 8, 9 exert an expanding operation force, and the first and second brake shoes 8. , 9 and a brake gap automatic adjusting means 11 for automatically adjusting the gap between the brake drum 7 and a return provided between the first and second brake shoes 8, 9. And a pulling 12.

  The first and second brake shoes 8 and 9 are connected to the webs 13 and 14 formed in an arcuate shape along the inner periphery of the brake drum 7 and to be orthogonal to the outer periphery of the webs 13 and 14. Rims 15 and 16, and linings 17 and 18 attached to the outer circumferences of the rims 15 and 16.

  The outer end portions of the pair of pistons 19 provided in the wheel cylinder 10 are arranged so as to face the webs 13 and 14 at the upper end portions of the first and second brake shoes 8 and 9. An anchor block 20 is fixed to the lower part of the back plate 6 so as to serve as a fulcrum when the first and second brake shoes 8 and 9 are expanded and contracted. It is actuated by the output hydraulic pressure of a master cylinder (not shown) operated by a pedal, and exerts a force for driving the first and second brake shoes 8 and 9 to the side of expanding with the anchor block 20 as a fulcrum. .

  Between the lower ends of the webs 13, 14 in the first and second brake shoes 8, 9, a coil spring 21 for urging the lower ends of the webs 13, 14 toward the anchor block 20 is provided. Between the upper ends of the webs 13 and 14 in the first and second brake shoes 8 and 9, the return spring 12 for urging the first and second brake shoes 8 and 9 in the contracting direction is provided.

  The automatic braking gap adjusting means 11 is provided between the webs 13 and 14 of the first and second brake shoes 8 and 9 and can be extended by the rotation of the adjusting gear 28, and the contracting position regulating strut 24 and the adjusting gear. An adjustment having a feed claw 26a that engages with 28 and is rotatably supported by the web 14 of the second brake shoe 9, which is one of the first and second brake shoes 8, 9. The lever 26 includes an adjustment spring 27 that urges the adjustment lever 26 to turn the adjustment gear 28 in the direction in which the contraction position regulating strut 24 extends.

  The contraction position regulating strut 24 regulates the contraction position of the first and second brake shoes 8, 9, and the first brake shoe 8 is provided among the first and second brake shoes 8, 9. A first rod 29 having a first engagement portion 29a that engages with the upper portion of the web 13 and a second engagement portion 30a that engages with the upper portion of the web 14 included in the second brake shoe 9 are provided. A second rod 30 disposed coaxially with the first rod 29, and an adjustment bolt having one end inserted into the first rod 29 so as to be relatively movable in the axial direction and the other end threaded coaxially with the second rod 30; The adjusting gear 28 is disposed between the first and second rods 29 and 30 and is formed on the outer periphery of the adjusting bolt 31.

  A first locking recess 13a for engaging the first engagement portion 29a is provided on the upper portion of the web 13 in the first brake shoe 8, and a second engagement portion 29a is provided on the upper portion of the web 14 in the second brake shoe 9. The 2nd latching recessed part 14a which engages the 2 engaging part 30a is provided.

  An adjustment lever 26 having a feed claw 26 a that engages with the adjustment gear 28 is rotatably supported by the web 14 of the second brake shoe 9 via a support shaft 25. The adjustment spring 27 is provided between the web 14 and the adjustment lever 26. Moreover, the spring force of the adjustment spring 27 is set smaller than the spring force of the return spring 12.

  According to the automatic brake clearance adjusting means 11, when the first and second brake shoes 8 and 9 are expanded by the operation of the wheel cylinder 10, a constant value is caused due to wear of the linings 17 and 18. When expanded, the adjustment lever 26 is rotated around the axis of the support shaft 25 by the spring force of the adjustment spring 27, whereby the contraction position regulation is performed in response to the adjustment gear 28 rotating. The effective length of the strut 24 is increased and corrected.

  By the way, one end of the drum brake 5 is pivotally supported by the web 13 of the first brake shoe 8 which is the other of the first and second brake shoes 8 and 9, and is pivotally supported. A parking brake lever 32 that is engaged with one end of the contraction position regulating strut 24 is attached.

  Referring also to FIG. 3, the parking brake lever 32 extends vertically so as to partially overlap the web 13 in the first brake shoe 8 in a front view. The upper end of the first brake shoe 8 is provided with a connecting hole 34 connected to the upper portion of the web 13 of the first brake shoe 8 via a pin 33. A third locking recess 32a that engages the first engaging portion 29a of the strut 24 is provided.

  When the vehicle is parked, the parking brake lever 32 is rotated and driven in the counterclockwise direction of FIG. 1, and the rotation of the parking brake lever 32 causes the second brake shoe 9 to move to the brake shoe 9. A force in a direction of pressing the lining 18 on the inner periphery of the brake drum 7 acts via the contraction position regulating strut 24. Further, when the parking brake lever 32 is continuously rotated and driven in the counterclockwise direction of FIG. 1, the parking brake lever 32 has an engagement point with the first engagement portion 29a of the contraction position regulating strut 24 as a fulcrum. This time, the first brake shoe 8 expands through the pin 33 and the lining 17 of the first brake shoe 8 comes into pressure contact with the inner periphery of the brake drum 7. That is, the linings 17 and 18 of the first and second brake shoes 8 and 9 are pressed against the inner periphery of the brake drum 7 to obtain a parking brake state.

  Referring also to FIG. 4, the parking brake lever 32 is rotationally driven by the power exerted by the electric actuator 36, and the brake cable 37 pulled by the electric actuator 36 is connected to the brake cable 37. The parking brake lever 32 can be rotated to drive the parking brake lever 32 so as to press the contraction position restricting strut 24 against the web 14 of the second brake shoe 9 by pulling the parking brake. Connected to the bottom of the.

  The electric actuator 36 includes an electric motor 40 attached to the casing 38 with the rotation axis as the vertical direction, and a power conversion mechanism built in the casing 38 so as to convert the rotational power of the electric motor 40 into a linear force. (Not shown). The casing 38 has a cylindrical portion 38 a having a cable outlet 39 for pulling out the brake cable 37 at a distal end, and the outer surface of the back plate 6 so that the cable outlet 39 faces the back plate 6. Mounted on.

  The brake cable 37 connected to the power conversion mechanism is pulled out from the cable outlet 39 into the back plate 6, and the tip of the brake cable 37 is connected to the parking brake lever 32. In addition, a part of the brake cable 37 between the casing 38 and the parking brake lever 32 on the casing 38 side is regulated such that both ends in the longitudinal direction are restricted to fixed positions with respect to the casing 38 and the back plate 6. Surrounded by an outer cable 41 disposed in the back plate 6, a portion of the brake cable 37 between the outer cable 41 and the parking brake lever 32 is a bellows-shaped boot 42 disposed in the back plate 6. Covered with. The outer cable 41 is formed in a cylindrical shape by a material that has elasticity and is difficult to receive in the bending direction and has rigidity against a compressive load in the pulling direction 44 of the brake cable 37.

  In addition, the connecting portion 43 of the tip of the brake cable 37 to the parking brake lever 32 and the cable outlet 39 are arranged so as to be orthogonal to the pulling direction 44 of the parking brake lever 32 by the brake cable 37 so that the back They are arranged at positions that are symmetric with respect to a plane PL passing through the center of the plate 6.

  One end portion of the outer cable 41 is fixed to a first cable end cap 45 having a male screw portion 45a that is screwed to a tip portion of the cylindrical portion 38a in the casing 38, for example, and the other end of the outer cable 41 is fixed. The portion is fixed to one end of the second cable end cap 46 by, for example, caulking, and the first and second cable end caps 45 and 46 are formed in a cylindrical shape so that the brake cable 37 is inserted therethrough.

  A connector for connecting the outer cable 41 and the boot 42, that is, the second cable end cap 46 is supported by the anchor block 20 provided on the back plate 6, and surrounds the second cable end cap 46. The second cable end cap 46 is supported by the support portion 20 a formed integrally with the anchor block 20. In this way, one end portion in the longitudinal direction of the outer cable 41 is fixed to the first cable end cap 45 screwed into the cylindrical portion 38a of the casing 38, and the other end portion in the longitudinal direction of the outer cable 41 is fixed to the back plate 6. It is fixed to the second cable end cap 46 supported by the anchor block 20, and both end portions of the outer cable 41 are restricted to a fixed position with respect to the casing 38 and the back plate 6.

  Moreover, the central axis CL of the cable outlet 39 is set to extend in a direction different from the pulling direction 44 of the parking brake lever 32 by the brake cable 37, and the outer cable 41 includes the cable outlet 39 and the cable outlet 39. It arrange | positions so that it may curve between the anchor blocks 20. FIG.

  The front end of the brake cable 37 is fixed by caulking to a third cable end cap 47 that engages with the lower end of the parking brake lever 32, and one end of the boot 42 is connected to the second cable end cap 46. The other end of the boot 42 is fitted to the third cable end cap 47.

  When the third cable end cap 47 is directly engaged with the lower part of the parking brake lever 32, a connecting portion 43 of the tip end portion of the brake cable 37 to the parking brake lever 32 is configured.

  By the way, the operation of the electric motor 40 in the electric actuator 36 is controlled by the control unit C, and the control unit C has determined that the drum brake 5 generates braking heat of a predetermined temperature or higher. Sometimes, the second brake shoe 9 pulls the brake cable 37 only by rotating the parking brake lever 32 to the side in which the second brake shoe 9 expands within a range less than the shoe clearance d with the brake drum 7. The electric actuator 36 is controlled.

  Moreover, the control unit C determines that the braking heat is equal to or higher than the predetermined temperature when the amount of heat generated by the drum brake 5 calculated based on the vehicle deceleration and the braking frequency exceeds a predetermined threshold. The vehicle body deceleration can be read by an acceleration sensor 49 mounted on the vehicle, and the brake frequency can be read by a hydraulic pressure sensor 50 that detects a brake hydraulic pressure of the wheel cylinder 10. Is possible. It is also possible to calculate the vehicle body deceleration from the detected value of the wheel speed sensor (not shown), obtain the brake frequency from the brake lamp switch (not shown), or from the detected value of the wheel speed sensor. It is also possible to obtain the brake frequency by calculating the wheel deceleration and estimating the hydraulic pressure.

  Next, the operation of this embodiment will be described. The brake cable 37 is pulled out from the casing 38 of the electric actuator 36 attached to the back plate 6 of the drum brake 5 that enters the parking brake state according to the pulling operation of the parking brake lever 32. The tip of the brake cable 37 is connected to the parking brake lever 32, and a portion of the brake cable 37 between the casing 38 and the parking brake lever 32 on the casing 38 side is a cylindrical outer cable 41. Since the portion of the brake cable 37 between the outer cable 41 and the parking brake lever 32 is covered with the bellows-shaped boot 42, water can be prevented from entering the casing 38.

  Moreover, both ends in the longitudinal direction of the outer cable 41 made of a material having elasticity and flexibility in the bending direction and having rigidity against the compressive load in the pulling direction 44 are connected to the casing 38 and the Since the position is fixed at a fixed position with respect to the back plate 6, the elastic force on the side that tensions the brake cable 37 can be applied from the outer cable 41 to the brake cable 37, and undesired loosening of the brake cable 37 occurs. Suppressing and reducing invalid strokes.

  The casing 38 is attached to the outer surface of the back plate 6 with the cable outlet 39 for drawing out the brake cable 37 facing the inside of the back plate 6, and the outer cable 41 and the boot 42 are placed in the back plate 6. Since it is accommodated, it is possible to more reliably prevent water from entering the casing 38.

  Further, since the second cable end cap 46 connecting the outer cable 41 and the boot 42 is supported by the anchor block 20 provided on the back plate 6, the first and second brake shoes 8, 9 are rotated. By supporting the second cable end cap 46 that connects the outer cable 41 and the boot 42 with the anchor block 20 that is firmly configured by being a fulcrum, the back plate 6 is distorted by the operation of the electric actuator 36. This can be prevented.

  Further, the connecting portion 43 of the distal end portion of the brake cable 37 to the parking brake lever 32 and the cable outlet 39 are arranged so as to be orthogonal to the pulling direction 44 of the brake lever by the brake cable 37, and the back plate 6. Therefore, the brake cable 37 can be routed without bending as much as possible to contribute to the reduction of the invalid stroke.

  Further, since the central axis CL of the cable outlet 39 is set so as to extend in a direction different from the pulling direction 44, the degree of freedom of the mounting posture of the casing 38 with respect to the back plate 6 can be increased.

  Further, an adjustment that is supported by the web 14 of the second brake shoe 9 by having a contraction position regulating strut 24 that can be extended by the rotation of the adjustment gear 28 and a feed claw 26a that engages with the adjustment gear 28. The brake 26 automatic adjusting means 11 comprising a lever 26 and an adjustment spring 27 that urges the adjustment lever 26 to turn the adjustment gear 28 in a direction in which the contraction position regulating strut 24 extends. A return spring 12 provided between the first and second brake shoes 8 and 9 so as to bias the first and second brake shoes 8 and 9 toward the contracted position side regulated by the contracted position regulating strut 24; The drum brake 5 is provided with a shaft 13 such that one end of the drum brake 5 is rotatable on the web 13 of the first brake shoe 8. In addition, a parking brake lever 32 that is engaged with one end of the contraction position restricting strut 24 is attached, and the brake cable 37 that is pulled by the electric actuator 36 is pulled by the second brake shoe 9 by pulling the brake cable 37. The parking brake lever 32 is rotationally driven so as to press the contraction position restricting strut 24 against the web 14 and is connected to the parking brake lever 32 to control the operation of the electric actuator 36. When the control unit C that determines that the brake heat of the predetermined temperature or more is generated in the drum brake 5, the second brake shoe 9 is in a range less than the shoe clearance d between the second brake shoe 9 and the brake drum 7. The parking blur is The Kireba 32 only rotates and controls the electric actuator 36 so as to pull the brake cable 37.

  Accordingly, when the pair of brake shoes 8 and 9 are expanded against the spring force of the return spring 12 by the operation of the wheel cylinder 10, the contraction position restricting strut 24 and the second brake shoe with the parking brake lever 32 engaged. Although a slight gap is generated between the nine, the length of the gap along the longitudinal direction of the contraction position regulating strut 24 is a value necessary for extending the contraction position regulating strut 24 by the rotation of the adjustment gear 28. Therefore, the brake gap automatic adjusting means 11 does not operate so as to displace the reduced diameter positions of the brake shoes 8 and 9 outward, and the occurrence of an over-adjusted state of the brake gap automatic adjusting means 11 is prevented. Can do. Thereby, it is possible to suppress the occurrence of drag and to suppress the occurrence of problems such as errors when the parking brake state is obtained by the operation of the electric actuator 36 controlled by the control unit C. In addition, when changing the temperature at which the operation of the braking gap automatic adjusting means 11 is automatically stopped, the control program of the control unit C has only to be changed, so that no part change is required.

  Further, the control unit C determines that the braking heat is equal to or higher than the predetermined temperature when the amount of heat generated by the drum brake 5 calculated based on the vehicle deceleration and the braking frequency exceeds a predetermined threshold. The braking heat of the drum brake 5 can be easily determined based on the vehicle body deceleration and the braking frequency.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various design changes can be made without departing from the present invention described in the claims. Is possible.

5 ... Drum brake 7 ... Brake drum 8, 9 ... Brake shoe 10 ... Wheel cylinder 11 ... Braking gap automatic adjustment means 12 ... Return springs 13, 14 ... Web 24 ..Shrinkage position restricting strut 26 ... adjust lever 26a ... feed claw 27 ... adjust spring 28 ... adjust gear 32 ... parking brake lever 36 ... electric actuator 37 ... brake cable C ... Control unit d ... Shoe clearance

Claims (2)

  A contraction position regulating strut (24) which is provided between the webs (13, 14) of a pair of brake shoes (8, 9) which are driven to extend by the wheel cylinder (10) and which can be extended by the rotation of the adjustment gear (28). And a feed claw (26a) that engages with the adjustment gear (28), so that the web (14) of one brake shoe (9) of the pair of brake shoes (8, 9) is rotatable. An adjustment lever (26) to be supported, and an adjustment spring (rotatingly urging the adjustment lever (26) in a direction to rotate the adjustment gear (28) in a direction in which the contraction position regulating strut (24) is extended) 27) and a brake gap automatic adjusting hand configured to adjust a gap between the pair of brake shoes (8, 9) and the brake drum (7). (11) and the pair of brake shoes (8, 9) so as to bias the pair of brake shoes (8, 9) toward the contracted position side regulated by the contracted position regulating strut (24). One end of the drum brake (5) having a return spring (12) provided is rotatable on the web (13) of the other brake shoe (8) of the pair of brake shoes (8, 9). A parking brake lever (32) that is pivotally supported and engaged with one end of the contraction position restricting strut (24) is attached, and a brake cable (37) pulled by an electric actuator (36) is connected to the brake cable. The contraction position restricting strut (24) is pressed against the web (14) of the one brake shoe (9) by traction of (37). In the vehicle brake device connected to the parking brake lever (32), the operation of the electric actuator (36) is controlled in such a manner that the parking brake state can be obtained by rotationally driving the parking brake lever (32). When the control unit (C) determines that braking heat of a predetermined temperature or more is generated in the drum brake (5), the one brake shoe (9) is connected to the brake drum (7). The electric actuator (36) is controlled so as to pull the brake cable (37) only by rotating the parking brake lever (32) to the side of expanding operation within a range less than the shoe clearance (d). Brake device for vehicles.   The control unit (C) determines that the braking heat is equal to or higher than the predetermined temperature when the amount of heat generated by the drum brake (5) calculated based on the vehicle deceleration and the braking frequency exceeds a predetermined threshold. The vehicle brake device according to claim 1, wherein the determination is made.

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