JP2010173588A - Brake fixation detecting device and brake fixation releasing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To restrain influence through the fixation of a shoe and a friction surface of a drum caused by freezing. <P>SOLUTION: In this brake fixation detecting device, a strut 28 regulates a mutual interval between a first shoe 12 and a second shoe 14 when the respective abutting parts 12e and 14e of the first shoe 12 and the second shoe 14 abut on abutting object parts 28a and 28b arranged in respective both ends when a parking brake is released. A return switch detects a return from a push-contact position with the friction surface 22a of the drum 22 of the first shoe 12 and the second shoe 14, by detecting the approach of the abutting part 14e of the second shoe 14 and the abutting object part 28b of the strut 28. An ECU determines that the first shoe 12 or the second shoe 14 is fixed to the drum 22 when the return from the push-contact position of the first shoe 12 or the second shoe 14 is not detected when the parking brake is released. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a brake sticking detection device and a brake sticking release device.

  In a vehicle parking brake, a parking brake operating member such as a brake lever and a wheel brake are connected to a brake operating force transmission system including a cable. For example, if the vehicle is left for a long time in a cold region with the parking brake activated, the brake operating force transmission system may freeze and affect the smooth start of the vehicle. For this reason, for example, the presence or absence of freezing of the brake operating force transmission system is determined based on the amount of movement of the brake operating force transmission system from when the electromagnetic brake is released until a predetermined time elapses, and freezing has occurred. In such a case, a freeze release device has been proposed in which freezing is released by driving an electric motor to break ice (for example, see Patent Document 1).

JP 2007-182227 A

  However, for example, a brake operating force transmission system such as a cable may cause elastic deformation or movement that is difficult to predict. For this reason, it is difficult to accurately grasp the amount of movement of the brake operating force transmission system. In this regard, there is room for improvement in the technique described in Patent Document 1 described above.

  Accordingly, the present invention has been made to solve the above-described problems, and an object of the present invention is to suppress the influence of sticking between the shoe and the friction surface of the drum caused by freezing or the like.

  In order to solve the above-described problems, a drum brake sticking detection device according to an aspect of the present invention includes a drum that has a friction surface on an inner peripheral surface thereof, rotates with a wheel, and a backing plate that is non-rotatably attached to a vehicle body. A pair of shoes movably attached to the backing plate and pressed against the friction surface to apply braking force to the wheels, and both ends of the pair of shoes are connected to each other so as to approach each other. A pair of shoes that expands the pair of shoes in the direction in which the urging member extends and presses against the friction surface in accordance with an operation input that requires application of braking force to the wheel. Opening means, return detecting means for detecting return from a position of pressing against at least one friction surface of the pair of shoes, and determining whether any of the pair of shoes is fixed to the drum Comprising a freeze determining unit that, the. The sticking determination means is configured such that when at least one of the pair of shoes is fixed to the drum when the return from the pressing position is not detected in at least one of the pair of shoes when the pair of shoes is not expanded. judge.

  According to this aspect, since the return of the shoe is directly detected rather than the transmission system of the brake operating force, the adhesion between the shoe and the friction surface of the drum can be detected more accurately. Therefore, it is possible to quickly suppress the influence of the adhesion between the shoe and the friction surface of the drum.

  The shoe expanding means may include a wheel cylinder that expands the pair of shoes and presses them against the friction surface by pressing each pressed portion of the pair of shoes with each of the pair of pistons. The return detection means may detect the return from each pressing position of the pair of shoes by detecting the proximity between each pressed portion of the pair of shoes and each of the pair of pistons.

  When the shoe adheres to the friction surface of the drum, a clearance is generated between the pressed portion of the shoe and the piston even after the expansion of the shoe by the brake expanding means is released. According to this aspect, the return of the shoe from the pressing position can be easily detected using such a relative positional relationship between the pressed portion of the shoe and the piston.

  When the expansion of the pair of shoes by the shoe expansion means is released, the contact portions of the pair of shoes contact the contacted portions provided at both ends, and the mutual distance between the pair of shoes You may further provide the strut which regulates. The return detection means may detect a return from at least one pressing position of the pair of shoes by detecting the proximity of at least one contact part of the pair of shoes and the contacted part of the strut. .

  When the shoe adheres to the friction surface of the drum, a clearance is generated between the contacted portion of the shoe and the contact portion of the strut even after the spread of the shoe is released. According to this aspect, the return of the shoe from the pressing position can be easily detected using such a relative positional relationship between the contacted portion of the shoe and the contacting portion of the strut.

  The return detection means may detect a return from at least one pressing position of the pair of shoes by detecting distortion of the biasing member. When the expansion of the shoe is released, the distortion of the biasing member changes. According to this aspect, the return of the shoe from the pressing position can be easily detected using this.

  Another aspect of the present invention is a drum brake debonding device. This device has a friction surface on its inner peripheral surface, a drum that rotates together with the wheel, a backing plate that is non-rotatably attached to the vehicle body, a movably attached to the backing plate, and is pressed against the friction surface. A pair of shoes for applying a braking force to the wheel, an urging member having both ends connected to each of the pair of shoes and applying a urging force in a direction approaching the pair of shoes, and a braking force for the wheel. In accordance with an operation input that requires application, a pair of shoes is expanded in the direction in which the urging member extends and is pressed against the friction surface, and a pressing position of at least one of the pair of shoes on the friction surface A return detecting means for detecting a return from the head, a sticking judging means for judging whether or not one of the pair of shoes is stuck to the drum, and at least one of the pair of shoes is provided so as to be heated. Comprising a heater to be a fixed release control means for controlling the heater to heat at least one of a pair of shoes, a. The sticking determination means is configured such that when at least one of the pair of shoes is fixed to the drum when the return from the pressing position is not detected in at least one of the pair of shoes when the pair of shoes is not expanded. judge.

  According to this aspect, the adhesion between the shoe and the friction surface of the drum can be detected more accurately, and therefore the adhesion between the shoe and the friction surface of the drum can be quickly released.

  According to the present invention, it is possible to suppress the influence caused by the adhesion between the shoe and the friction surface of the drum caused by freezing or the like.

It is a figure which shows the structure of the drum brake device which concerns on 1st Embodiment. It is the figure which looked at the strut from the viewpoint P of FIG. FIG. 3 is an enlarged view of a region Q in FIG. 2. (A) is a front view of the second shoe, and (b) is a right side view of the second shoe. It is a flowchart which shows the procedure of the sticking release control with respect to the drum brake device which concerns on 1st Embodiment. It is the figure which looked at the strut which concerns on 2nd Embodiment from the viewpoint P of FIG. It is an enlarged view of the area | region R of FIG. It is a flowchart which shows the procedure of the sticking release control with respect to the drum brake device which concerns on 3rd Embodiment. It is a figure which shows the structure of the drum brake device which concerns on 4th Embodiment.

  Hereinafter, embodiments of the present invention (hereinafter referred to as “embodiments”) will be described in detail with reference to the drawings.

(First embodiment)
FIG. 1 is a diagram illustrating a configuration of a drum brake device 10 according to the first embodiment. In order to facilitate understanding, in FIG. 1, illustration of a cover and the like covering the inside is omitted. The drum brake device 10 shown in FIG. 1 is for the right rear wheel. The drum brake device for the left rear wheel is configured symmetrically with the drum brake device 10 with respect to the center line in the front-rear direction of the vehicle shown in FIG. Hereinafter, description of the drum brake device 10 will be omitted, and description of the drum brake device for the left rear wheel will be omitted.

  The drum brake device 10 includes a backing plate 11, a first shoe 12, a second shoe 14, an anchor 16, a wheel cylinder 18, a shoe gap automatic adjustment mechanism 20, a drum 22, and a parking brake mechanism 24. The backing plate 11 is attached to the vehicle body so as not to rotate. The first shoe 12 and the second shoe 14 are each formed in an arc shape, and are arranged in the drum 22 so as to draw a circle on both sides. The drum 22 has a friction surface 22a on the inner peripheral surface, and is fixed to the wheel so as to rotate together with the wheel. When the vehicle moves forward, the drum 22 rotates in the direction indicated by the arrow A. For this reason, the first shoe 12 becomes a leading shoe, and the second shoe 14 becomes a trading shoe.

  The first shoe 12 has a shoe web 12a, a shoe rim 12b, and a lining 12c. The shoe web 12a is formed as a flat plate having an arcuate outer shape, and the shoe rim 12b is formed as a flat plate curved along the outer periphery of the shoe web 12a. The shoe rim 12b is integrally attached to the outer periphery of the shoe web 12a so as to have a T-shaped cross section. The lining 12c is formed as a flat plate curved along the outer surface of the shoe rim 12b. The lining 12c is fixed to the outer surface of the shoe rim 12b by adhesion or the like.

  The second shoe 14 has a shoe web 14a, a shoe rim 14b, and a lining 14c. The configuration of the shoe web 14a, the shoe rim 14b, and the lining 14c is substantially the same as that of the shoe web 12a, the shoe rim 12b, and the lining 12c, except that the outer shape of the shoe web 14a is slightly different from the outer shape of the shoe web 12a.

  One end of the shoe webs 12 a and 14 a facing each other, that is, the lower end in FIG. 1, is arranged to face the anchor 16 fixed on the backing plate 11. A tension coil spring 34 is hooked on one end of each of the shoe webs 12a, 14a, and thereby, one end of each of the shoe webs 12a, 14a is pressed against the anchor 16. Thus, the first shoe 12 and the second shoe 14 are supported by the backing plate 11 so as to be able to expand in parallel with the backing plate 11. As the first shoe 12 and the second shoe 14 expand each other, each of the linings 12c and 14c is pressed against the friction surface 22a of the drum 22, and braking force is applied to the wheels.

  Shoe hold downs 26 and 27 are respectively provided in the intermediate portions of the shoe webs 12a and 14a. Each of the shoe hold-downs 26 and 27 is configured to be movable in parallel with the backing plate 11 together with each of the shoe webs 12a and 14a. Since the configurations of the shoe hold downs 26 and 27 are known, the description thereof is omitted.

  The wheel cylinder 18 has a pair of pistons 32. A parking lever or a parking brake pedal (hereinafter collectively referred to as a “parking brake operation member”) is provided around the driver's seat in the vehicle cabin. When the parking brake operating member is in the initial position, that is, when the parking brake is released, the other end of the shoe webs 12a, 14a, that is, the pressed portion provided at the upper end in FIG. Each abuts against the pressing surface of each of the pair of pistons 32.

  When a brake pedal (not shown) is depressed by the driver, hydraulic fluid is supplied into the wheel cylinder 18 according to the amount of operation, and the pair of pistons 32 are propelled away from each other. In this way, the wheel cylinder 18 expands the first shoe 12 and the second shoe 14 by pressing the pressed portions of the first shoe 12 and the second shoe 14 with each of the pair of pistons 32, thereby forming the friction surface 22 a. Press contact. Therefore, the wheel cylinder 18 functions as a shoe expanding means for expanding the first shoe 12 and the second shoe 14 with each other.

  The shoe gap automatic adjustment mechanism 20 has a strut 28. The strut 28 is provided so as to be expandable and contractible by a screw. By extending as the moving amount of the first shoe 12 increases, a gap between the strut 28 and the drum 22 is maintained within a predetermined range even if the linings 12c and 14c are worn. Configured to be maintained within. Since the structure of such a strut 28 is well-known, description is abbreviate | omitted.

  A return spring 30 that is an urging member is wound around the outer periphery of the strut 28. Both ends of the return spring 30 are connected to each of the first shoe 12 and the second shoe 14, and gives a biasing force in a direction in which the first shoe 12 and the second shoe 14 approach each other.

  The parking brake mechanism 24 also functions as shoe expansion means. The parking brake mechanism 24 includes a connecting pin 36, a brake shoe lever 38, a cable 40, and a return spring 42.

  The brake shoe lever 38 extends parallel to the shoe web 14a of the second shoe 14, and is disposed so as to overlap the shoe web 14a closer to the backing plate 11 than the shoe web 14a. One end of the brake shoe lever 38 is connected to the wheel cylinder 18 via the second shoe 14 and the connecting pin 36 so as to be rotatable. An intermediate portion around the connecting pin 36 of the brake shoe lever 38 is inserted into a notch formed in the strut 28.

  One end of the cable 40 is connected to the other end of the brake shoe lever 38. The other end of the cable 40 is connected to an operation member for parking brake via another cable (not shown). Instead of such a parking brake operation member, a so-called electric parking brake may be employed.

  A return spring 42 is wound around the outer periphery of the cable 40. The return spring 42 applies a biasing force to push the brake shoe lever 38. When the parking brake is released, the return spring 42 biases the brake shoe lever 38 away from the center of the drum 22 and locks it in the initial position.

  At this time, no force is applied to the first shoe 12 and the second shoe 14 in the expanding direction. For this reason, one end of each end comes into contact with the piston 32 of the wheel cylinder 18 by the urging forces of the return springs 30 in the closing directions. As a result, a clearance is provided between each of the linings 12c and 14c and the friction surface 22a of the drum 22, and the application of the braking force to the wheels is released. Hereinafter, the positions of the first shoe 12 and the second shoe 14 at this time are respectively referred to as “release positions”. When the brake shoe lever 38 is in an initial position where it is pressed against a locking portion (not shown) by the urging force of the return spring 42, a slight gap is provided between the intermediate portion and the notch portion of the strut 28. Is formed.

  When the parking brake operating member is operated from the initial position to the braking position by the driver, that is, when the parking brake is activated, the cable 40 is pulled, and the other end of the brake shoe lever 38 is pulled accordingly. As a result, the brake shoe lever 38 rotates about the connecting pin 36 toward the center of the drum brake device 10.

  When the parking brake operating member is operated, the brake shoe lever 38 rotates and the intermediate portion comes into contact with the notch portion of the strut 28, and the strut 28 is pushed forward as it is. As a result, the first shoe 12 is pushed by the strut 28 and moves from the release position, and the lining 12 c is pressed against the friction surface 22 a of the drum 22. Further, a reaction force in which the brake shoe lever 38 pushes the strut 28 is applied to the brake shoe lever 38 in a direction opposite to the direction in which the strut 28 is pushed. As a result, the second shoe 14 is pushed through the connecting pin 36 and moves from the release position, and the lining 14 c is pushed against the friction surface 22 a of the drum 22. Hereinafter, the positions of the first shoe 12 and the second shoe 14 when pressed against the drum 22 in this way are referred to as “pressing positions”, respectively.

  The parking brake mechanism 24 expands the first shoe 12 and the second shoe 14 in the direction in which the return spring 30 extends in accordance with an operation input requesting to apply braking force to the wheels, that is, an operation input to the parking brake operation member. Open and press against the friction surface 22a.

  However, in a cold region, for example, when the parking brake is activated and the vehicle is left for a long time with the first shoe 12 and the second shoe 14 pressed against the friction surface 22a of the drum 22, the first is caused by freezing. Each of the shoe 12 and the second shoe 14 may adhere to the drum 22. For this reason, in the drum brake device 10 according to the first embodiment, the return switch 50 is provided in order to detect whether the first shoe 12 or the second shoe 14 is fixed to the drum 22.

  FIG. 2 is a view of the strut 28 viewed from the viewpoint P of FIG. At both ends of the return spring 30, hook portions 30a and 30b are provided, respectively. The return spring 30 has a hook portion 30 a hooked on the hook portion 12 d of the first shoe 12 and a hook portion 30 b hooked on the hook portion 14 d of the second shoe 14.

  At both ends of the strut 28, contacted portions 28a and 28b, which are the bottoms of the notches, are provided, respectively. The first shoe 12 and the second shoe 14 are urged by the return spring 30 in a direction close to each other, that is, in a closing direction. For this reason, the contact portion 12 e of the first shoe 12 contacts the contacted portion 28 a of the strut 28, and the contact portion 14 e of the second shoe 14 contacts the contacted portion 28 b of the strut 28.

  Thus, when the parking brake mechanism 24 is released, the strut 28 has the abutted portions 28a in which the abutting portions 12e and 14e of the first shoe 12 and the second shoe 14 are provided at both ends, respectively. It abuts on 28b and regulates the mutual distance between the first shoe 12 and the second shoe 14. In the first embodiment, the return switch 50 is attached in the vicinity of the abutted portion 28 b of the strut 28.

  FIG. 3 is an enlarged view of a region Q in FIG. The return switch 50 is provided with a protrusion 50a. The return switch 50 is mounted on the strut 28 so that the protruding portion 50a protrudes from the contacted portion 28a.

  When the parking brake is released and the first shoe 12 and the second shoe 14 are in the release position, the contact portion 14e of the second shoe 14 is brought into contact with the contacted portion 28b of the strut 28 by the urging force of the return spring 30. Abut. At this time, the protrusion 50a is pushed by the contact portion 14e, and the return switch 50 is turned on.

  However, when at least one of the first shoe 12 and the second shoe 14 is fixed to the friction surface 22 a of the drum 22, the contact portion 14 e of the second shoe 14 does not contact the contacted portion 28 b of the strut 28. . The protruding portion 50a of the return switch 50 is held in a protruding state by an internal spring. Therefore, the return switch 50 is not turned on unless both the first shoe 12 and the second shoe 14 are separated from the friction surface 22a of the drum 22 and appropriately return from the pressing position by the urging force of the return spring 30. .

  Here, “return from the pressing position” in the first embodiment refers to a state in which the lining 12c or the lining 14c is separated from the friction surface 22a. Thus, the return switch 50 functions as return detection means, and when turned on, detects the return from the position where the first shoe 12 and the second shoe 14 are pressed against the friction surface 22a.

  The return switch 50 detects at least one of the first shoe 12 and the second shoe 14 by detecting the proximity of at least one contacted portion of the first shoe 12 and the second shoe 14 and the end of the strut. It may be provided to detect the return from the pressing position. For example, the return switch 50 may detect the proximity of the contact portion 12e of the first shoe 12 and the contacted portion 28a of the strut 28. In addition, a pair of return switches 50 are disposed around each of the contact portions 28a and 28b of the strut 28, and the proximity of the contact portion 12e of the first shoe 12 and the contact portion 28a of the strut 28, and the first The proximity of the contact portion 14e of the two shoes 14 and the contacted portion 28b of the strut 28 may be provided so as to be individually detectable.

  The return switch 50 is connected to an electronic control unit (not shown; hereinafter referred to as “ECU”). The ECU includes a CPU that executes various arithmetic processes, a ROM that stores various control programs, a RAM that is used as a work area for data storage and program execution, and is mounted inside the vehicle. The ECU controls various devices provided in the vehicle.

  The ECU determines whether any of the first shoe 12 and the second shoe 14 is fixed to the drum 22. When the ECU 1 detects that the first shoe 12 and the second shoe 14 are not expanded, when the first shoe 12 and the second shoe 14 are not returned from the pressing position, the shoe is a drum. 22 is determined to be fixed. Thus, the ECU functions as a sticking determination unit.

  FIG. 4A is a front view of the second shoe 14, and FIG. 4B is a right side view of the second shoe 14. Hereinafter, description will be made in relation to both FIG. 4 (a) and FIG. 4 (b).

  A pair of heaters 52 are attached to the inner surface of the shoe rim 14b so as to sandwich the shoe web 14a. Each of the heaters 52 extends over substantially the entire area of the inner surface of the shoe rim 14b facing the lining 14c. Although not shown, a pair of heaters 52 is attached to the inner surface of the shoe rim 12b of the first shoe 12 so as to sandwich the shoe web 12a. Each of the heaters 52 also extends over substantially the entire area of the inner surface of the shoe rim 12b facing the lining 14c. Each heater 52 of the first shoe 12 and the second shoe 14 is connected to the ECU. The ECU controls heating of the first shoe 12 and the second shoe 14 by the heater 52 by controlling on and off of the heater 52 attached to each of the first shoe 12 and the second shoe 14. The heater 52 may be provided so that at least one of the first shoe 12 and the second shoe 14 can be heated.

  FIG. 5 is a flowchart showing a procedure of sticking release control for the drum brake device 10 according to the first embodiment. The process in this flowchart starts when the ignition switch of the vehicle is turned on, and is repeatedly executed every predetermined time thereafter until the ignition switch is turned off.

  The ECU determines whether or not the parking brake has been released by determining whether or not a stop lamp switch (not shown) provided around the parking brake operating member has been turned off (S10). When the parking brake is in operation (N in S10), the processing in this flowchart is temporarily ended.

  When it is determined that the parking brake is released (Y in S10), the ECU determines whether or not the return switch 50 is off (S12). When the return switch 50 is turned on (N in S12), it is determined that both the first shoe 12 and the second shoe 14 have appropriately returned to the release positions, and the processing in this flowchart is temporarily ended.

  When the return switch 50 remains off despite the parking brake being released (Y in S12), the ECU indicates that the first shoe 12 or the second shoe 14 is fixed to the friction surface 22a of the drum 22. Then, the heaters 52 of both the first shoe 12 and the second shoe 14 are turned on (S14), and the first shoe 12 and the second shoe 14 are heated. In this way, the first shoe 12 or the second shoe 14 can be properly released from being fixed to the drum 22.

  In this way, the ECU functions as a sticking release control means for controlling on / off of the heater 52 so that the sticking of the first shoe 12 or the second shoe 14 to the drum 22 is released. The drum brake device 10 and the ECU function as a sticking detection device or a sticking release control device of the drum brake device 10.

(Second Embodiment)
FIG. 6 is a view of the strut 28 according to the second embodiment viewed from the viewpoint P of FIG. Unless otherwise specified, the configuration and operation of the drum brake device according to the second embodiment are the same as those of the drum brake device 10 according to the first embodiment. Hereinafter, the same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  In the second embodiment, a strain gauge 53 is provided instead of the return switch 50. The strain gauge 53 is attached around the hook portion 30 a of the return spring 30. Note that the strain gauge 53 may be attached to another portion of the return spring 30 such as the periphery of the hook portion 30b.

  When the parking brake is released from the operating state, the distortion of the return spring 30 changes. At this time, when the first shoe 12 or the second shoe 14 is fixed to the drum 22 and when both the first shoe 12 and the second shoe 14 are properly returned to the release position, the first shoe 12 is used. And the difference with the distortion of the return spring 30 when both the 2nd shoes 14 exist in a pressing position is different. The strain gauge 53 detects a return from at least one pressing position of the first shoe 12 and the second shoe 14 by detecting the strain of the return spring 30. Therefore, the strain gauge 53 functions as a return detection unit.

  The strain gauge 53 is connected to the ECU. The ECU holds a threshold value obtained in advance through experiments. When the amount of change in distortion of the return spring 30 when the parking brake is released is equal to or greater than the threshold, the ECU determines that both the first shoe 12 and the second shoe 14 have properly returned from the pressing position to the release position. To do. On the other hand, the ECU determines that the first shoe 12 or the second shoe 14 is fixed to the drum 22 when the amount of change in distortion of the return spring 30 when the parking brake is released is less than the threshold value. The control after determining that the sticking has occurred is the same as described above. Thus, the return of the first shoe 12 or the second shoe 14 can also be detected by detecting the distortion of the return spring 30.

(Third embodiment)
FIG. 7 is an enlarged view of a region R in FIG. Unless otherwise specified, the configuration and operation of the drum brake device according to the third embodiment are the same as those of the drum brake device 10 according to the first embodiment. Hereinafter, the same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  In the third embodiment, a pair of return switches 54 is provided instead of the return switch 50. When the parking brake is released, the pressed portion 12f of the first shoe 12 is in contact with the pressing surface 32a of the piston 32. The return switch 54 is attached in the vicinity of the pressed portion 12 f of the first shoe 12. The return switch 54 is provided with a protrusion 54a. The return switch 54 is arranged such that the protruding portion 54a protrudes from the pressed portion 12f when the pressed portion 12f of the first shoe 12 is separated from the pressing surface 32a of the piston 32.

  Although illustration is omitted, when the parking brake is released, the pressed portion of the second shoe 14 is in contact with the pressing surface 32a of the piston 32. The return switch 54 is attached in the vicinity of the pressed portion of the second shoe 14. At this time, the return switch 54 is arranged so that the protruding portion 54a protrudes from the pressed portion when the pressed portion of the second shoe 14 is separated from the pressing surface 32a of the piston 32. Each of the pair of return switches 54 detects each of the first shoe 12 and the second shoe 14 by detecting the proximity of the pressed portion of each of the first shoe 12 and the second shoe 14 and each of the pair of pistons. The return from the pressing position is detected. Therefore, the return switch 54 also functions as return detection means.

  FIG. 8 is a flowchart showing a procedure of sticking release control for the drum brake device according to the third embodiment. The process in this flowchart starts when the ignition switch of the vehicle is turned on, and is repeatedly executed every predetermined time thereafter until the ignition switch is turned off.

  The ECU determines whether or not the parking brake has been released by determining whether or not a stop lamp switch (not shown) provided around the parking brake operating member has been turned off (S30). When the parking brake is operating (N in S30), the processing in this flowchart is temporarily ended.

  When it is determined that the parking brake is released (Y in S30), the ECU determines whether or not the return switch 54 of the first shoe 12 is off (S32). If the return switch 54 of the first shoe 12 remains off despite the parking brake being released (Y in S32), the ECU indicates that the first shoe 12 is fixed to the friction surface 22a of the drum 22. The heater 52 attached to the first shoe 12 is turned on (S34).

  When the return switch 54 of the first shoe 12 is turned on (N in S32), the ECU determines that the first shoe 12 has properly returned to the release position, and this time the return switch 54 of the second shoe 14 is turned off. It is determined whether or not (S36). If the return switch 54 of the second shoe 14 remains off despite the parking brake being released (Y in S36), the ECU indicates that the second shoe 14 is fixed to the friction surface 22a of the drum 22. The heater 52 attached to the second shoe 14 is turned on (S38). When the return switch 54 of the second shoe 14 is turned on (N in S36), the ECU determines that the second shoe 14 has properly returned to the release position, and once ends the processing in this flowchart.

  Thus, by providing return detection means corresponding to each of the first shoe 12 and the second shoe 14, it is specified which of the first shoe 12 and the second shoe 14 is fixed to the drum 22. Is possible. For this reason, for example, it is possible to avoid turning on the heater 52 of the second shoe 14 even though only the first shoe 12 is fixed, and power consumption can be suppressed.

(Fourth embodiment)
FIG. 9 is a diagram illustrating a configuration of a drum brake device 100 according to the fourth embodiment. Unless otherwise specified, the configuration and operation of the drum brake device 100 according to the fourth embodiment are the same as those of the drum brake device 10 according to the first embodiment. Hereinafter, the same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  In the fourth embodiment, a first return switch 70 and a second return switch 72 are provided instead of the return switch 50. A displacement sensor may be provided in place of the first return switch 70 and the second return switch 72.

  The first return switch 70 is provided with a protrusion 70a. The first return switch 70 is fixed to the backing plate 11 inside the drum 22 so that the protruding portion 70a is pushed by the shoe rim 12b of the first shoe 12 when the first shoe 12 is in the release position. Similarly, the second return switch 72 is also provided with a protrusion 72a. The second return switch 72 is fixed to the backing plate 11 inside the drum 22 so that the protrusion 72a is pushed by the shoe rim 14b of the second shoe 14 when the second shoe 14 is in the release position.

  The first return switch 70 detects the return of the first shoe 12 from the pressing position by detecting the movement of the first shoe 12 to the release position. The second return switch 72 detects the return of the second shoe 14 from the pressing position by detecting the movement of the second shoe 14 to the release position. Thus, the first return switch 70 and the second return switch 72 each function as return detection means.

  The procedure of the sticking release control uses the detection result of the first return switch 70 instead of the detection result of the return switch 54 of the first shoe 12, and replaces the detection result of the return switch 54 of the second shoe 14 with the second return. Except that the detection result of the switch 72 is used, it is the same as the procedure of the sticking release control according to the third embodiment. Also by the first return switch 70 and the second return switch 72 provided in this way, the sticking generated in the first shoe 12 and the second shoe 14 can be individually detected.

  The present invention is not limited to the above-described embodiments, and an appropriate combination of the elements of each embodiment is also effective as an embodiment of the present invention. Various modifications such as design changes can be added to each embodiment based on the knowledge of those skilled in the art, and embodiments to which such modifications are added can also be included in the scope of the present invention.

  10 drum brake device, 11 backing plate, 12 first shoe, 12a shoe web, 12b shoe rim, 12c lining, 12e abutting portion, 12f pressed portion, 14 second shoe, 14a shoe web, 14b shoe rim, 14c lining, 14d Hook part, 14e contact part, 18 wheel cylinder, 22 drum, 22a friction surface, 24 parking brake mechanism, 28 strut, 28a, 28b contacted part, 30 return spring, 32 piston, 32a pressing surface, 38 brake shoe lever , 50 return switch, 50a protrusion, 52 heater, 53 strain gauge, 54 return switch, 54a protrusion, 70 first return switch, 70a protrusion 72 second return switch, 72a protruding part.

Claims (5)

A drum having a friction surface on the inner peripheral surface and rotating together with the wheel;
A backing plate attached to the vehicle body so that it cannot rotate,
A pair of shoes that are movably attached to the backing plate and apply a braking force to the wheels by being pressed against the friction surface;
Both ends of the pair of shoes are coupled to each other, and a biasing member that applies a biasing force in a direction in which the pair of shoes approaches each other,
Shoe expansion means for expanding the pair of shoes in a direction in which the biasing member extends and pressing against the friction surface in accordance with an operation input requesting application of braking force to the wheels;
Return detection means for detecting a return from a pressing position of at least one of the pair of shoes to the friction surface;
Fixing determination means for determining whether one of the pair of shoes is fixed to the drum;
With
The sticking determination means is configured such that when at least one of the pair of shoes does not return from the pressing position when expansion of the pair of shoes is released, at least one of the pair of shoes is the drum. A brake sticking detection device, characterized in that it is judged that the brake sticks. The shoe expanding means includes a wheel cylinder that expands the pair of shoes and presses against the friction surface by pressing each pressed portion of the pair of shoes with each of a pair of pistons,
The return detection means detects the return from the pressing position of each of the pair of shoes by detecting the proximity of each pressed portion of the pair of shoes and each of the pair of pistons. The brake sticking detection device according to claim 1, wherein When the expansion of the pair of shoes by the shoe expansion means is released, the contact portions of each of the pair of shoes come into contact with the contacted portions provided at both ends, and the pair of shoes It further comprises struts that regulate the mutual spacing of the shoes,
The return detection means detects the return from the pressing position of at least one of the pair of shoes by detecting the proximity of at least one contact part of the pair of shoes and the contacted part of the strut. The brake sticking detection device according to claim 1, wherein the brake sticking detection device is detected.   2. The brake adhering detection according to claim 1, wherein the return detection unit detects a return from the pressing position of at least one of the pair of shoes by detecting distortion of the biasing member. apparatus. A drum having a friction surface on the inner peripheral surface and rotating together with the wheel;
A backing plate attached to the vehicle body so that it cannot rotate,
A pair of shoes that are movably attached to the backing plate and apply a braking force to the wheels by being pressed against the friction surface;
Both ends of the pair of shoes are coupled to each other, and a biasing member that applies a biasing force in a direction in which the pair of shoes approaches each other,
Shoe expansion means for expanding the pair of shoes in a direction in which the biasing member extends and pressing against the friction surface in accordance with an operation input requesting application of braking force to the wheels;
Return detection means for detecting a return from a pressing position of at least one of the pair of shoes to the friction surface;
Fixing determination means for determining whether one of the pair of shoes is fixed to the drum;
A heater provided to heat at least one of the pair of shoes;
When it is determined that at least one of the pair of shoes is fixed to the drum, an adhesion release control means for controlling the heater to heat at least one of the pair of shoes;
With
The sticking determination means is fixed to the drum if the return from the pressing position is not detected by any of the pair of shoes when the pair of shoes is not expanded. The brake adhering release device, characterized in that

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