JP4888331B2 - Parking brake system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make the slack of a cable small when torque is applied during the operation of a parking brake in a parking brake system including a duo-servo type drum brake. <P>SOLUTION: When the direction of torque expected to be applied to wheels is the direction P of forward rotation in a stop state of a vehicle, a solenoid 166b is excited and pin 160b is engaged with a portion 110b, which serves as a secondary shoe upon the application of the torque. Then, even when a pressing mechanism 120 is actuated, the brake shoe 110b is not displaced, but a brake shoe 110a is displaced. Thereby, force in the circumferential direction is transmitted to the brake shoe 110b via an adjuster and pressed against an anchor member 106. In this state, even if torque in the forward rotating direction is applied, displacement in the circumferential direction of a pair of the brake shoes 110a, b and the pressing mechanism 120 is suppressed and consequently, the braking force is prevented from lowering because the brake shoe 110b contacts the anchor member 106. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a parking brake system including a duo-servo type drum brake.

The parking drum brake described in Patent Document 1 includes (a) a non-rotating body, (b) a drum that rotates with a vehicle wheel, and an inner peripheral surface that is a friction surface, and (c) an inner peripheral side of the drum. A pair of brake shoes having a friction material on the outer peripheral surface, (d) an anchor fixed between the pair of brake shoes of the non-rotating body, and (e) one of the pair of brake shoes. A brake lever rotatably provided via a pin at an end of the anchor, a cable provided in a state of pulling an end opposite to the anchor of the brake lever, and (g ) An intermediate lever provided on the other brake shoe so as to be rotatable at an intermediate portion thereof; (h) a strut provided between the anchor side end portions of the brake lever and the intermediate lever; and (i) One brake shoe, the other brake shoe and the middle The lever, which is an anchor and a adjuster provided between the adjacent ends of the opposite side, the distance from the center of rotation of the intermediate lever to the strut is greater than the distance to the adjuster.
When the cable is pulled, the brake lever is rotated around the pin, and the intermediate lever is rotated via the strut. The rotation of the intermediate lever is transmitted to one brake shoe via the adjuster, and one brake shoe is pressed against the drum. Further, the other brake shoe is pressed against the drum by the force applied to the intermediate lever through the strut. In addition, a clearance gap arises between an adjuster and the other brake shoe by rotation of the above-mentioned intermediate lever.
In this parking brake operation state, when torque is applied to move one brake shoe away from the anchor, one brake shoe and the brake lever are moved in the circumferential direction so as to reduce the gap described above, and the adjuster is moved. Accordingly, the intermediate lever is rotated in the direction opposite to that when the brake is operated. The strut pushes back the brake lever by turning the intermediate lever. Since the distance from the rotation center of the intermediate lever to the strut is larger than the distance to the adjuster, the strut moves the brake lever in the direction opposite to the direction of movement caused by the torque. As a result, the path of the cable engaged with the brake lever becomes longer, and the cable is prevented from loosening.
When torque is applied to move the other brake shoe away from the anchor, the other brake shoe moves along the circumferential direction. The other intermediate lever rotates and moves one brake shoe and brake lever in a direction toward the anchor via the adjuster. This movement does not loosen the cable.

The parking brake described in Patent Document 2 includes the above-mentioned (a) non-rotating body, (b) drum, (c) a pair of brake shoes, (d) anchor, (e) brake lever and (f) cable, j) including a strut provided between the brake lever and the anchor side end of the other brake shoe, and the first connection point P1 between the strut and the brake lever is the brake shoe and the brake lever. The second connecting point P2 and the center point O of the drum brake are located on the side closer to the other brake shoe (anchor side) than that line.
When the cable is pulled, the second connection point P2 is moved along the arc around the center point O, and the first connection point P1 is moved radially outward. When the other brake shoe is biased toward the anchor and the pair of brake shoes are pressed against the drum, one brake shoe is separated from the anchor and the other brake shoe is not separated from the anchor.
In this parking brake operating state, even if torque is applied to move one brake shoe away from the anchor, the other brake shoe is in contact with the anchor, so that it is avoided that the braking force is reduced.
In addition, a torque is applied to move the other brake shoe away from the anchor, and the one brake shoe is moved in the circumferential direction. Avoided.
Patent Document 2 also describes that the elastic force of the return spring provided between the anchor and the other brake shoe is larger than the elastic force of the return spring provided between the brake shoe. Has been. Thereby, when a pressing force is applied, it is possible to make it difficult to separate the other brake shoe from the anchor.

The parking brake described in Patent Document 3 includes the above-described (a) non-rotating body, (b) drum, (c) a pair of brake shoes and (d) an anchor, and (m) a pair of brake shoes. A pair of intermediate levers pivotably provided at the intermediate portion of the intermediate lever, and (n) a brake lever pivotally provided around the pin at one end of the pair of intermediate levers on the anchor side, (o) A cable that applies a tensile force to the end of the brake lever opposite to the anchor, and (p) a pair of brake shoes and a pair of intermediate levers provided between the ends opposite to the anchor (Q) the other intermediate lever, the strut provided between the one intermediate lever and the brake lever, and (r) the anchor-side ends of the pair of brake shoes. A first return spring and (s) a pair of brake chassis It is intended to include a second return spring disposed between the ends of the adjuster side over, between the elastic force F ₁ of the first return spring, the rotation center and the first return spring of the intermediate lever The moment determined by the distance L ₁ (F ₁ × L ₁ ) is determined by the distance L ₂ between the elastic force F ₂ of the second return spring and the rotation center of the intermediate lever (F ₂ × L ₂ ). Has been bigger.
When tension is applied to the cable, the pair of intermediate levers are expanded with the adjuster as a fulcrum, thereby pressing the pair of brake shoes against the drum. In this case, since the moment due to the elastic force of the first return spring is larger than the moment due to the elastic force of the second return spring, the pair of brake shoes abut against the anchor at the anchor side end, and the adjuster at the end on the adjuster side. It will be in the state separated from.
When a torque for separating the other brake shoe from the anchor is applied in the operation state of the parking brake, the other brake shoe is moved along the circumferential direction and comes into contact with the adjuster. As a result, one intermediate lever is rotated, and the brake lever is rotated radially outward with the strut as a fulcrum. The brake lever also rotates radially outward when the adjuster pushes one of the intermediate levers in the circumferential direction. If the brake lever is pivoted radially outward, the cable path becomes longer and the cable is prevented from loosening.
When torque is applied to release one brake shoe from the anchor, one brake shoe moves in the circumferential direction and abuts the adjuster. The other intermediate lever rotates, and one intermediate lever and the brake lever are rotated radially outward via the struts. In addition, the movement of one brake shoe in the circumferential direction causes one intermediate lever to rotate, causing the brake lever to rotate radially outward. As a result, the cable path becomes longer and loosening is prevented.
JP-A-10-110758 JP-A-10-103391 JP 2001-165207 A

  An object of the present invention is to suppress a decrease in braking force when torque is applied to a wheel in a stopped state of the vehicle by a method different from the methods described in Patent Documents 1 to 3 described above.

Means and effects for solving the problem

The parking brake system according to claim 1 is a parking brake system including a duo-servo type drum brake, which rotates with (1) a non-rotating body and (2) a vehicle wheel, and an inner peripheral surface is a friction surface. A rotating drum, (3) a pair of brake shoes disposed on the inner peripheral side of the rotating drum and having a friction material on the outer peripheral surface, and (4) between the one end portions of the pair of brake shoes, An anchor member fixed to the rotating body, and (5) the ends of the pair of brake shoes opposite to the side on which the anchor member is provided are coupled to each other, and the one rotating drum of the pair of brake shoes A transmission member that transmits a circumferential force applied to the other brake shoe as an input to the other brake shoe; (6) provided on the one end side of the pair of brake shoes, and the friction material of the pair of brake shoes is used as the drum A pressing device that presses against the inner peripheral surface; (7) (a) an electric drive source; and (b) operated by the electric drive source and engaged with each of the pair of brake shoes, thereby the pair of brakes. At least one movement suppressing member that suppresses relative movement of at least one of the non-rotating body and the anchor member of each of the shoes; and (c) predicting the direction of torque applied to the wheels when the vehicle is stopped. Based on the prediction, prior to the operation of the pressing device, the electric drive source is controlled to become a secondary shoe when the torque is applied to one of the at least one movement suppressing member. And a movement suppression control unit that suppresses movement in a direction away from the anchor member although it becomes the secondary shoe when the pressing device is operated. Including the door.
In the drum brake included in the parking brake system, a pressing force is applied to both of the pair of brake shoes by the operation of the pressing device, and the brake is operated. However, if, for some reason, one of the pair of brake shoes is more easily moved than the other, the other brake shoe is not moved and only one brake shoe is moved. In this state, when a torque is applied to the wheel to cause the other brake shoe to move away from the anchor member, the other brake shoe moves away from the anchor member in the circumferential direction, and the accompanying force of the other brake shoe is reduced. It is transmitted to one brake shoe via the transmission member, and one brake shoe abuts on the anchor member. As described above, when the pair of brake shoes are moved in the circumferential direction in a state where the operation state of the pressing device is maintained, the braking force may be reduced depending on the structure of the pressing device.
On the other hand, in the parking brake system according to claim 1, when the vehicle is stopped, the direction of the torque applied to the wheels is predicted, and when the torque is applied before the operation of the pressing device, A movement suppressing member is engaged with a shoe (hereinafter simply referred to as a secondary shoe) to suppress the movement of the secondary shoe away from the anchor member. Even if the predicted direction of torque is the forward rotation direction or the reverse rotation direction, the movement suppressing member is engaged with the secondary shoe. Therefore, when a pressing force is applied to both of the pair of brake shoes, the primary shoe (hereinafter simply referred to as the primary shoe) is always more easily moved than the secondary shoe. As a result, the primary shoe is surely moved by the operation of the pressing device, and the circumferential force is transmitted to the secondary shoe via the transmission member. The secondary shoe is pressed against the anchor member.
Even if the torque in the direction predicted in this state is applied, since the secondary shoe is already in contact with the anchor member, the movement of the pair of brake shoes in the circumferential direction is suppressed, and the decrease in brake force is suppressed. The
As described above, in the parking brake system according to the first aspect of the present invention, the direction of the torque applied to the wheels is predicted in the stop state of the vehicle, and the movement suppressing member is engaged with the secondary shoe, thereby operating the pressing device. Sometimes, the movement of the secondary shoe is suppressed, and the decrease in braking force is suppressed. This method is different from the methods described in Patent Documents 1 to 3.
The secondary shoe is restrained from moving away from the anchor member due to the engagement with the movement restraining member, but is moved closer to the anchor member by the circumferential force transmitted from the primary shoe via the transmission member. It is desirable that the movement in the direction to be allowed is allowed. In this way, even when torque is applied in the engaged state between the secondary shoe and the movement suppressing member, the movement of the secondary shoe toward the anchor member is allowed well.
The pressing device can be operated by an electric motor. For example, a brake lever is operated by pulling a cable by an electric motor, and a pair of brake shoes can be pressed against a rotating drum by the brake lever and the strut. In that case, as described in claim 9, it is desirable to provide a holding mechanism capable of holding the friction material pressing force even when no electric current is supplied to the electric motor.
When the vehicle is stopped, the direction of the torque applied to the wheels can be predicted based on the inclination of the road surface on which the vehicle exists and the shift position of the transmission. The vehicle is stopped by the operation of the service brake, the parking brake is then operated, and the service brake is often released after the parking brake is activated. When the service brake is released, torque due to gravity is applied to the wheels, or drive torque from the vehicle drive source is applied.
In the stop state of the vehicle, the direction of the torque applied to the wheels can be predicted based on the inclination direction of the road surface on which the vehicle is stopped as described in claim 2. The inclination direction of the road surface is detected by an inclination detection device. When the vehicle is stopped on the uphill, it is predicted that torque in the reverse rotation direction is applied, and when the vehicle is stopped on the downhill, torque in the forward rotation direction is applied. The inclination detection device can also be considered as an attitude detection device that detects the inclination of the vehicle in the front-rear direction. The tilt detection device may include a longitudinal acceleration sensor, and may further include a vehicle height sensor.
Further, the parking brake may be operated even when the vehicle drive source is in an operating state and the shift position is at a position other than parking. In that case, if the shift position is at a position other than neutral, the direction of torque applied to the wheel can be predicted based on the shift position. When the shift position is a position for instructing forward movement, it is predicted that torque in the forward rotation direction is applied, and when it is in a position for instructing reverse movement, torque in the reverse rotation direction is predicted to be applied.
After the operation start command to the movement suppressing device is issued, the operation start command to the pressing device may be issued, or the operation start command to the pressing device may be issued first. It is only necessary that the movement suppressing member is engaged with the secondary shoe at the start of the actual operation of the pressing device, and when the delay of the pressing device is large (the time from the operation start command to the actual operation start is long) The operation start command to the pressing device can be issued first.
The parking brake system according to claim 3, wherein the movement suppression control unit includes a drive source control unit that controls the electric drive source in response to a parking brake operation command, and the parking brake system includes the drive source. And a pressing device control unit that operates the pressing device after the electric drive source is controlled by the control unit. In the parking brake system described in this section, the control of the electric drive source of the movement suppressing device is started according to the parking brake operation command, and then the operation of the pressing device is started. Even if the operation of the pressing device is started after confirming that the movement suppressing member is engaged with the secondary shoe, the operation is started after the time estimated to be engaged with the secondary shoe has elapsed. Alternatively, it may be started immediately after the electric drive source is started. In any case, it is possible to more reliably suppress the separation of the secondary shoe from the anchor member if the movement suppressing member is engaged with the secondary shoe before the start of the operation of the pressing device. When the pressing device has a structure that can be manually operated, it is desirable to output a command for delaying the operation of the parking brake operation member to the driver.
Further, the engagement state between the movement restraining member and the secondary shoe is maintained during the operation of the drum brake, or is maintained until a predetermined condition is satisfied after the operation of the drum brake (during operation). Or can be done. For example, the engagement state can be released when the drum brake is finished (when the pressing device is finished), when the torque is applied (for example, when the service brake is released), It can be canceled when a set time has elapsed since the operation of the device has ended. When the pressing device is of a floating type (a type in which the main body of the pressing device is not fixed to the non-rotating body), the engagement between the movement restraining member and the secondary shoe is applied until torque is applied. It is desirable to maintain the state. This is to suppress the movement of the pressing device in the rotation direction.
In the movement suppressing device, the number of movement suppressing members may be one or two. When there is one movement suppressing member, the one movement suppressing member selectively engages both of the pair of brake shoes. When there are two movement suppressing members, one of the movement suppressing members is engaged with one of the pair of brake shoes, and the other movement suppressing member is engaged with the other brake shoe. When there are two movement suppression members, one electric drive source may be provided in common for the two movement suppression members, or an electric drive source may be provided for each of the two movement suppression members. .
The movement suppression member can be an engagement rod (sometimes referred to as a pin or a slide member) or an engagement claw. In any case, by engaging with the brake shoe, the movement of the brake shoe away from the anchor member is suppressed.
An engagement portion is often formed on the brake shoe, but it is not essential. The engaging portion can be, for example, a notch, an engaging hole, an engaging recess, an engaging protrusion, or the like.
In addition, the movement suppressing member may be held on one of the non-rotating body and the anchor member so as to be linearly movable, or may be held rotatably (movable in a curve). In this specification, movement includes linear movement and curvilinear movement, and curvilinear movement includes rotation, rotation, and the like.
The electric drive source can be an electric motor, an electrically deformable member having a piezoelectric element or the like, or a solenoid.
The movement restraining device (size, shape of the movement restraining member, installation position of the holding device for holding the movement restraining member, etc.) is separated from the anchor member of the secondary shoe in the engaged state between the movement restraining member and the secondary shoe. It is desirable to design such that the movement in the direction close to the anchor member can be permitted. In addition, when the engaging portion is formed in the brake shoe and the engaging portion is a notch, the notch is in a direction away from the anchor member of the secondary shoe in a state where the movement suppressing member is engaged with the notch. The shape and size can be made to suppress the movement and allow the movement in the direction approaching the anchor member. Furthermore, when the engaging portion is an engaging protrusion, the shape of the movement suppressing member and the movement suppressing member are engaged with the movement suppressing member on the side farther from the anchor member than the engaging protrusion of the secondary shoe. It is desirable to determine the installation position of the holding device.
In addition, a movement suppression apparatus can also be designed so that the movement of the direction which approaches an anchor member can also be suppressed. The same applies to the design of the engaging portion when the engaging portion is provided in the brake shoe.

Hereinafter, the specific aspect of a movement suppression apparatus is demonstrated.
The parking brake system according to claim 4, wherein the movement suppressing member is provided corresponding to each of the pair of brake shoes, and the movement suppressing device includes any one of the non-rotating body and the anchor member. An engagement position that is fixedly provided on either side and engages each of the movement restraining members with the brake shoe in a non-actuated state of the drum brake, and a non-engagement position that is disengaged from the brake shoe. A movement restraining member holding device that holds the head in a movable manner.
The movement suppressing member holding device holds the movement suppressing member so as to be relatively movable, and is fixedly provided on one of the non-rotating body and the anchor member.
In addition, the movement suppressing member holding device is configured such that, when the drum brake is in an inoperative state, the movement suppressing member is a predetermined portion of the brake shoe (if the brake shoe has an engaging portion, the engaging portion) It is provided in the position which can be engaged. In other words, in the parking brake system described in this section, the movement suppressing member is engaged with the brake shoe when the drum brake is not in operation, and the movement suppressing member and the secondary shoe are engaged when the pressing device starts operating. Is in an engaged state. In the engaged state of the movement restraining member and the secondary shoe, it can be considered that either the non-rotating body or the anchor member is connected to the secondary shoe.
In the parking brake system according to claim 5, each of the movement suppressing members is an engagement rod, and each of the pair of brake shoes has an engaging portion that can be engaged with the movement suppressing member. The movement suppressing member holding device is provided at a position corresponding to the engaging portion of each of the pair of brake shoes in the non-actuated state of the drum brake of the non-rotating body, A linear movement type holding part that holds the linear movement type between the engagement position and the non-engagement position so that the linear movement type holding part is movable. And a biasing member that biases the engagement rod to a non-engagement position, and the electric drive source is provided corresponding to each of the engagement rods. Combine the rod Against the biasing force of the serial biasing member is moved to the engaged position from the disengaged position comprises a solenoid applying an electromagnetic driving force.
An engagement rod is provided for each of the pair of brake shoes, and the engagement rod is linearly moved between the engagement position and the non-engagement position. Movement of the brake shoe away from the anchor member is suppressed at the engagement position of the engagement rod, and movement of the brake shoe away from the anchor member is allowed at the non-engagement position. In the parking brake system described in this section, the engagement rod is urged to the non-engagement position by the urging means. In a state where no current is supplied to the solenoid, the engagement rod is in the non-engagement position.
Even if the movement restraining member holding device holds the engagement rod in a posture parallel to the backing plate as a non-rotating body and is movable in a parallel direction, it is in a posture perpendicular to the backing plate, It may be held so as to be movable in a vertical direction. Further, when the engaging portion is an engaging protrusion, the engaging protrusion may be provided on the surface of the brake shoe web facing the backing plate or on the surface opposite to the backing plate. .
The parking brake system according to claim 6, wherein each of the movement suppressing members is an engaging claw, and each of the pair of brake shoes has an engaging portion that can be engaged with the engaging claw. The movement suppressing member holding device is provided at a position corresponding to the engaging portion of each of the pair of brake shoes when the drum brake is in an inoperative state, and each of the engaging claws is respectively connected to the brake. A rotation-type holding portion that rotatably holds between an engagement position that engages with an engagement portion of the shoe and a non-engagement position that is disengaged from the engagement portion; An electric motor is provided corresponding to each of the engaging claws, and rotates the engaging claws between the engaging position and the non-engaging position.
The engaging claw is rotated between the engaging position and the non-engaging position. Due to the engagement between the engagement claw and the engagement portion of the brake shoe, the movement of the brake shoe away from the anchor member is suppressed.
The movement restraining device can be provided with a biasing means that biases the engaging claw to the non-engaging position. In that case, the engagement claw is held in the non-engagement position when no electric current is supplied to the electric motor.
The parking brake system according to claim 7, wherein each of the movement suppressing members is an engaging claw, and each of the pair of brake shoes has an engaging portion that can be engaged with the engaging claw. The movement suppressing member holding device is provided at a position corresponding to the engaging portion of each of the pair of brake shoes when the drum brake is in an inoperative state, and each of the engaging claws is respectively connected to the brake. A rotation-type holding portion that rotatably holds between an engagement position that engages with an engagement portion of the shoe and a non-engagement position that is disengaged from the engagement portion; An electric motor that is provided corresponding to one of the two engaging claws and rotates one of the engaging claw between the engaging position and the non-engaging position; Drive transmission that transmits rotation to the other engaging claw Including the mechanism.
Two engaging claws are rotated by one electric motor. The drive transmission mechanism transmits the rotation of the electric motor to the other engagement claw, and includes, for example, a pair of pulleys (which can be a gear) and a belt (which can also be a wire or a chain). It can be. Further, the drive transmission mechanism can directly transmit the rotation of one engagement claw to the other engagement claw. With the electric motor and the drive transmission mechanism, the first state where one engaging claw is in the engaging position and the other engaging claw is in the non-engaging position, and one engaging claw is in the non-engaging position, The second engagement claw is switched to the second state in the engagement position.
In the parking brake system according to claim 8, each of the movement restraining members is an engaging claw, the two engaging claws are integrally movable in the axial direction, and the movement restraining control unit is A first state in which one of the two engaging claws is engaged with one of the pair of brake shoes and the other engaging claw is not engaged with the other brake shoe, and the other engaging claw is the other brake. Means for engaging with the shoe and switching between a second state in which the one engaging claw does not engage with the one brake shoe.
The member that holds the two engaging claws is held so as to be linearly movable in the axial direction of the movement suppressing member holding device. When one engaging claw is engaged with one brake shoe, the other engaging claw is disengaged from the other brake shoe, and either the first state or the second state is selectively selected. Realized. The pair of brake shoes can be provided with engagement portions (engagement protrusions, notches, engagement holes, engagement recesses, etc.), but it is not essential.

In the parking brake system, the movement suppression member is provided in common to the pair of brake shoes, and each of the pair of brake shoes has an engaging portion with the movement suppression member, and the movement suppression member An apparatus includes a movement suppression member holding device fixedly provided on one of the non-rotating body and the anchor member, and rotatably holding the movement suppression member, and the movement suppression control unit includes By rotating the movement suppressing member, it is possible to include means for selectively engaging one engaging portion of the pair of brake shoes.
One movement restraining member is selectively engaged with one of the engaging portions of the pair of brake shoes by its rotation.

A parking brake system according to an embodiment of the present invention will be described in detail with reference to the drawings.
In FIG. 1, the code | symbol 10 shows an electric motor and the code | symbol 12 shows the motion conversion mechanism with a clutch. The motion conversion mechanism 12 with the clutch converts the rotation of the output shaft of the electric motor 10 into a linear motion of the output member, and prevents the electric motor 10 from being rotated by the force applied to the output member. Reference numerals 14 and 16 indicate left and right rear wheels, and reference numerals 18 and 20 indicate parking brakes provided on the wheels 14 and 16, respectively. The parking brakes 18 and 20 and the motion conversion mechanism 12 with the clutch are connected by cables 22 and 24, respectively. When the cables 22 and 24 are pulled by the operation of the electric motor 10, the parking brakes 18 and 20 are activated. In this embodiment, an electric parking brake mechanism 30 is constituted by the electric motor 10, the motion conversion mechanism 12 with a clutch, the cables 22, 24, the parking brakes 18, 20, and the like.

As shown in FIG. 2, the motion conversion mechanism 12 with a clutch includes a gear train 40, a clutch 42, a screw mechanism 44, and the like.
The gear train 40 includes a plurality of gears 46, 48 and 50. The gear 46 is engaged with the output shaft 52 of the electric motor 10, and the rotation of the gear 46 is transmitted to the gear 50 via the gear 48. On the end surface of the gear 50 opposite to the electric motor 10, a drive transmission portion 54 that protrudes in parallel with the axial direction is provided.
The clutch 42 is a one-way clutch, and can rotate integrally with a housing 60, a coil spring 62 provided on the inner peripheral side of the housing 60, and an output shaft 64 of the clutch 42, as shown in FIG. Rotor 66. The coil spring 62 is fitted to the housing 60 in a state where the winding diameter is elastically slightly contracted, and the outer peripheral surface thereof is in close contact with the inner peripheral surface of the housing 60, and the end portions 68, 70 are provided so as to protrude toward the inner peripheral side. The drive transmission portion 54 of the gear 50 is located in one of the two spaces sandwiched between the two end portions 68 and 70, and the rotor 66 is located in the other.

When the gear 50 rotates along with the rotation of the electric motor 10, the drive transmission portion 54 comes into contact with one of the end portions 68 and 70, and the coil spring 62 is tightened to tighten the inner peripheral surface of the housing 60 and the spring 62. The frictional force with the outer peripheral surface is reduced. Thereby, the coil spring 62 and the rotor 66 can be rotated, and the output shaft 64 is rotated. The output shaft 64 is rotated integrally with the gear 50, and the rotation of the electric motor 10 is transmitted to the output shaft 64 by the clutch 42.
When torque is applied to the output shaft 64 in a state where no electric current is supplied to the electric motor 10, the rotor 66 comes into contact with either one of the end portions 68 and 70, whereby the coil spring 62 is expanded in diameter. The frictional force between the outer peripheral surface of the coil spring 62 and the inner peripheral surface of the housing 60 is increased, and the rotation of the coil spring 62 is prevented. When the clutch 42 prevents the torque of the output shaft 64 from being transmitted to the gear 50 and no current is supplied to the electric motor 10, the electric motor 10 is not rotated by the torque applied to the output shaft 64. .

  The screw mechanism 44 is attached to the housing 80, a male screw member 82 extending in a direction parallel to the axis L, a nut (not shown) screwed to the male screw member 82, and the nut so as to be relatively rotatable around the M axis. And an equalizer 84. The male screw member 82 is supported by the housing 80 through a pair of radial bearings 85 (the other is not shown) and a needle thrust bearing 86 so as to be relatively rotatable. The inner cables 87 of the cables 22 and 24 are connected to both arms of the equalizer 84, respectively. The main body of the equalizer 84 is provided with an engagement protrusion 88, which is not shown, but is engaged with a guide provided in the housing 80 in a direction parallel to the axis L. As a result, the equalizer 84 is not relatively rotatable with respect to the housing 80 around the axis L, is relatively movable in a direction parallel to the axis L, and is relatively rotated around the engaging projection 88 (around the axis M). It is possible to move.

The equalizer 84 is movable relative to the housing 80 between a position indicated by a solid line and a position indicated by a two-dot chain line in FIG. 2, and the inner cable 22, 24 is moved along with the relative movement of the equalizer 84. The cable 87 is pulled or loosened. Further, the equalizer 84 is arranged around the engaging protrusion 88 (on the axis M) so that the tension applied to the inner cable 87 of the two cables 22 and 24 (hereinafter simply referred to as the tension of the cables 22 and 24) is the same. Around).
A tension sensor 90 that detects the tension of the cable 24 is provided inside the housing 80. Since the tension applied to the cables 22 and 24 by the equalizer 84 is set to the same magnitude, the tension applied to the cable 24 detected by the tension sensor 90 is also the tension applied to the cable 22.
Reference numeral 92 denotes an abnormality canceling device. The abnormal-time release device 92 is a device for releasing the parking brakes 18 and 20 when the electric motor 10 is abnormal. When the cable 93 is pushed into the gear 95 and a grip portion (not shown) is manually rotated, the gear 95 is rotated. The rotation of the gear 95 is transmitted to the gear 50 through the gears 46 and 48, and the equalizer 84 is moved in the direction of loosening the cables 22 and 24 by the rotation of the gear 50. Thereby, the parking brakes 18 and 20 are released.

  As shown in FIGS. 4 and 5, the parking brakes 18 and 20 are duo-servo type drum brakes in this embodiment. Therefore, hereinafter, the parking brakes 18 and 20 may be referred to as drum brakes as necessary. In FIG. 4, reference numeral 97 denotes a brake disk, reference numeral 98 denotes a caliper, and the brake disk 97 and the caliper 98 together constitute a disk brake 99 as a service brake. The drum brakes as the parking brakes 18 and 20 are provided on the inner peripheral side of the brake disc 97, and are drum-in disc brakes in this embodiment. Since the drum brakes 18 and 20 have the same structure, the drum brake 18 will be described and the description of the drum brake 20 will be omitted.

  The drum brake 18 includes a backing plate 100 as a non-rotating member attached to a vehicle body (not shown), and a drum 104 having a friction surface 102 on its inner peripheral surface and rotating together with the wheel 14. An anchor member 106 and an adjuster 108 as a relay link are provided at two positions separated in the diameter direction of the backing plate 100, respectively. The anchor member 106 is fixed to the backing plate 100, and the adjuster 108 is a floating type. A pair of brake shoes 110 a and 110 b each having an arc shape are attached between the anchor member 106 and the adjuster 108 so as to face the inner peripheral surface of the drum 104. The pair of brake shoes 110a and 110b are attached to the backing plate 100 so as to be movable along the surfaces thereof by shoe hold-down devices 112a and 112b. The through hole provided in the center of the backing plate 100 is for allowing the axle shaft (not shown) to pass therethrough.

  The pair of brake shoes 110a and 110b are operatively connected at one end to each other by an adjuster 108, and each other end abuts against the anchor member 106 and is rotatably supported. One end portions of the pair of brake shoes 110a and 110b are urged toward the adjuster 108 by an adjuster spring 114, and the other end portions are urged toward the anchor member 106 by a return spring 115. . Brake linings 116a and 116b as friction materials are held on the outer peripheral surfaces of the brake shoes 110a and 110b, and the pair of brake linings 116a and 116b are brought into contact with the friction surface 102 of the drum 104, whereby the brake linings 116a and 116b are arranged. A frictional force is generated between 116 b and the drum 104. The adjuster 108 is operated to adjust the gap between the pair of brake linings 116a and 116b and the drum 104 in accordance with the wear of the pair of brake shoes 110a and 110b.

FIG. 5 shows the pressing mechanism 120. The pressing mechanism 120 includes a brake lever 122 and a strut 124, and is supported by heads of bolts 138 and 140 that fix the anchor member 106 to the backing plate 100 so as to be relatively movable. Each of the brake lever 122 and the strut 124 is a plate-like member. When the brake lever 122 is sandwiched between two plate members constituting the strut 124, the brake lever 122 and the strut 124 have one end portion thereof. In FIG. 2, the shaft is connected so as to be relatively rotatable around the connecting shaft 126. In the brake lever 122, the brake shoe 110 a is engaged with an engaging portion 128 provided at a portion separated from the connecting shaft 126 toward the backing plate 100, and an end separated from the connecting shaft 126 in a direction parallel to the backing plate 100. The inner cable 87 of the cable 22 is connected to the engaging portion 130 provided in the portion. The inner cable 87 is guided by an outer tube 134 having one end fixed to a through-hole 132 provided in the backing plate 100, and extends to a side opposite to the side where the brake shoe 110 and the like of the backing plate 100 are disposed. It has been made.
Further, in the strut 124, the brake shoe 110 b is engaged with an engaging portion 135 provided at the end opposite to the connecting shaft 126.
In the state shown in the drawing, the engaging portion 130 is located on the backward rotation direction side from the center line N (of the fixed end of the cable 22 to the backing plate 100) of the through hole 132. Further, as will be described later, when the pressing mechanism 120 is relatively moved in the circumferential direction, the engaging portion 130 is also relatively moved, but by design, the pressing mechanism 120 is relatively moved from the center line N to a position on the forward rotation direction side. It is made not to be moved.

The pressing mechanism 120 is supported by the heads of the bolts 138 and 140 at the supported parts 136 and 137, and when the inner cable 87 is pulled, the brake lever 122 contacts the supported part 136 and the head of the bolt 138. As a result, the connecting shaft 126 and the strut 124 are moved rightward in FIG. 5, and the strut 124 pushes the brake shoe 110b to the right. At that time, the reaction force from the brake shoe 110b is transmitted to the brake shoe 110a via the strut 124, the connecting shaft 126 and the brake lever 122, and the brake shoe 110a is pushed to the left in FIG. The brake shoes 110a and 110b are spread by being applied with the same expansion force, and as a result, the brake linings 116a and 116b have the same size on the inner peripheral surface 102 of the drum 104. It is pressed with the power of The tensile force applied to the cable 22 is boosted according to the lever ratio of the brake lever 122, and from the boosted force, between the supported portions 136, 137 and the heads of the bolts 138, 140. Is applied to the brake shoes 110a and 110b as an expanding force having a magnitude obtained by subtracting a force corresponding to the frictional force.
The relationship shown in FIG. 6 is established between the pressing force and the brakeable torque in this case. From this relationship, the relationship between the tensile force of the cables 22 and 24 and the brakeable torque is acquired, and the supply current to the electric motor 10 is controlled so that the cable tension becomes the target tension.

A movement suppressing mechanism 150 is provided in the vicinity of the anchor member 106. The movement suppression mechanism 150 selectively suppresses the movement of one of the pair of brake shoes 110a and 110b away from the anchor member 106. The webs 151a, b of the pair of brake shoes 110a, b are provided with engaging holes 152a, 152b as engaging portions, respectively. The movement restraining mechanism 150 is linearly arranged in a direction perpendicular to the backing plate 100 with pins 160a and 160b serving as a pair of movement restraining members provided corresponding to the engagement holes 152a and 152b. Housings 162a, b that are held relative to each other, and biasing members that are provided between the housings 162a, b and the pins 160a, b and bias the pins 160a, b to the non-engagement position (retracted end). Springs 164a, b and solenoids 166a, b.
The housings 162a and 162b are fixedly provided at positions corresponding to the engagement holes 152a and b of the pair of brake shoes 110a and 110b, respectively, when the drum brakes 18 and 20 are not in operation.
The solenoids 166a and 166b apply an electromagnetic driving force to the pins 160a and 160b to move (advance) toward the engagement position against the urging force of the springs 164a and 164b. While the current is not supplied to the solenoids 166a and 166b (OFF), the pins 160a and b are in the non-engagement position due to the urging force of the springs 164a and b, but when the current is supplied (ON), the pins 160a and b are in the engagement position. Moved.
The engagement holes 152a, b suppress the movement of the brake shoes 110a, b away from the anchor member 106 and allow the movement of the approach toward the anchor member 106 when the pins 160a, b are engaged. To be the shape and size. As a result, even when torque is applied in a state where the pins 160a, b are engaged with the engagement holes 152a, b, the movement of the brake shoes 110a, b in a direction approaching the anchor member 106 is allowed well. Will be.

  In addition, while making the anchor side of engagement hole 152a, b into an inclined surface, the anchor side of pin 160a, b can be made into an inclined surface. As a result, it is possible to satisfactorily suppress the separation of the brake shoes 110a, b from the anchor member 106 in a state where the pins 160a, b are engaged with the engagement holes 152a, b.

The electric drive source (solenoids 166a and 166b) of the electric motor 10 and the movement suppressing mechanism 150 are controlled based on a command from the electric parking brake ECU 200, as shown in FIG. The electric parking brake ECU 200 mainly includes a computer and includes an input / output unit 202, an execution unit 204, a storage unit 206, and the like. A parking brake switch (hereinafter simply referred to as a parking switch) 210 and a tension sensor 90 (see FIG. 2) are connected to the input / output unit 202, and the electric motor 10 is connected via a drive circuit 212. Solenoids 166a and 166b are connected via a drive circuit 213, respectively. The electric motor 10 is an actuator for an electric parking brake.
The electric parking brake ECU 200 is connected via a CAN (Car Area Network) 214 to other computers provided in the vehicle, such as a slip control ECU (VSCUCU) 220, an engine / transmission ECU (ETC ECU) 222, and the like. The slip control ECU 220 is connected to a longitudinal acceleration sensor 226, a service brake switch 227, and the like, and the engine / transmission ECU 222 is connected to a shift position sensor 228, etc., and the longitudinal acceleration, ON / OFF of the service brake switch 227, the shift position Such information is supplied to the electric parking brake ECU 200 via the slip control ECU 220, the engine / transmission ECU 222, and the CAN 214.

When the parking switch 210 instructs the operation of the parking brakes 18 and 20 (hereinafter, the operation of the parking brakes 18 and 20 may be referred to as “lock”), the parking switch 210 is referred to as the release. In some cases, the switch is operated, for example, and may include a lock-side operation unit and a release-side operation unit. When the lock-side operation unit is operated (hereinafter abbreviated as the case where the lock instruction operation is performed), there is a lock request, and when the release-side operation unit is operated (hereinafter, the release instruction operation is performed). (Abbreviated as “Case”) is a release request.
The longitudinal acceleration sensor 226 detects the longitudinal acceleration of the vehicle, and the service brake switch 227 is turned on when a service brake operation member (not shown) is in an operating state, and is turned off when it is in a non-operating state. It is a switch that becomes a state. When the service brake operation member is in the operating state, the service brake 99 can be assumed to be in the operating state. Therefore, the service brake switch 227 can be a switch that detects the actual operating state of the service brake 99. For example, when the brake cylinder is held by the caliper 98, the hydraulic pressure of the brake cylinder is detected, and ON / OFF is detected based on the hydraulic pressure of the brake cylinder, and the electric motor is held by the caliper 98. In such a case, the current flowing through the electric motor and the pressing force can be detected, and ON / OFF can be detected based on these.
In this embodiment, the shift position sensor 228 detects the shift position based on the state of the transmission (for example, the current supply state to the solenoid of the solenoid valve: corresponding to the shift position). The position may be detected. This is because these can be considered to correspond in a stopped state of the vehicle.

Normally, the vehicle is stopped by the operation of the service brake 99, after which the parking brakes 18 and 20 are operated, and the service brake 99 is normally released in the operating state of the parking brakes 18 and 20. . In this case, when the vehicle is stopped on a slope, torque due to gravity is applied to the wheels. Further, when the shift position of the transmission is a position other than parking or neutral, drive torque (torque of the vehicle drive source) corresponding to the shift position is applied.
When the parking brakes 18 and 20 are operated, the pressing mechanism 120 applies a pressing force having the same magnitude to the pair of brake shoes 110a and 110b as described above. However, if the brake shoe 110a is more easily moved than the brake shoe 110b for some reason, the brake shoe 110b is not expanded by the pressing force applied from the pressing mechanism 120, and the brake shoe 110a is expanded. Be opened. The circumferential force applied to the brake shoe 110 a is transmitted to the brake shoe 110 b via the adjuster 108, and the brake shoe 110 b is pressed against the anchor member 106. Even when a torque in the forward rotation direction P is applied in this brake applied state, the slack of the cables 22 and 24 is small, but when a torque in the reverse rotation direction Q is applied, the brake shoe 110b is separated from the anchor member 106. Accordingly, the circumferential force is transmitted to the brake shoe 110 a via the adjuster 108, and the brake shoe 110 a comes into contact with the anchor member 106. The pair of brake shoes 110a, b are moved in the circumferential direction, the pressing mechanism 120 is also moved in the circumferential direction, the cables 22, 24 are loosened, and the braking force is reduced.
However, it is normal not to know which of the brake shoes 110a and 110b is easy to move and which is difficult to move. Therefore, in this embodiment, one of the pair of brake shoes 110a and 110b is selectively made difficult to move, and the other brake shoe is always moved by the operation of the pressing mechanism 120. It is.

When the vehicle is stopped, the direction of the torque applied to the wheels 14 and 16 is the forward rotation direction P when the road surface on which the vehicle exists is a downhill road surface (downhill), and the uphill road surface (uphill). Is the backward rotation direction Q. As shown in FIG. 7, there is an equation G = g · sin θ between the longitudinal acceleration G and the road inclination angle θ.
Is established. From this equation, when the slope is downward, the longitudinal acceleration G is a positive value and θ is a positive value. When the slope is upward, the longitudinal acceleration G is a negative value and θ is a negative value. It becomes clear. From this, based on the positive and negative of the longitudinal acceleration G, the direction of the road surface inclination can be acquired. In addition, when the absolute value of the inclination angle is equal to or larger than a predetermined set value, the road surface is inclined, and when it is smaller than the set value, it is acquired that it is substantially horizontal.
Furthermore, when the vehicle drive source is in an operating state, the parking switch 210 is operated at a shift position other than the parking position and the neutral position, the parking brakes 18 and 20 are operated. When the brake 99 is released, torque according to the shift position is applied. When the shift position is the forward instruction position, torque in the forward rotation direction P is applied, and when the shift position is the reverse instruction position, torque in the backward rotation direction Q is applied.
In this embodiment, when the road surface on which the vehicle is stopped is inclined, the direction of the torque is predicted based on the direction of the inclination, and the road surface on which the vehicle is stopped is almost horizontal. The direction of the torque is predicted based on the direction of the driving torque.
Note that the predicted torque direction can also be acquired based on both the magnitude of the road surface inclination angle, the direction and the magnitude of the driving torque, and the direction.

  In the present embodiment, the parking brake control program represented by the flowchart of FIG. 8 is executed at predetermined time intervals. In step 1 (hereinafter abbreviated as S1. The same applies to the other steps), it is determined whether or not the parking switch 210 has been operated. Is determined. In the case of a lock instruction, in S 3 and 4, as described above, the direction of the road surface inclination is acquired based on the detection value by the longitudinal acceleration sensor 226, and the driving torque is calculated based on the detection result by the shift position sensor 228. The orientation is acquired. In S5, the direction of the torque applied when the service brake 99 is released is predicted, and the solenoid corresponding to the secondary shoe when the torque is applied is selected. For example, when the direction of the applied torque is predicted to be the forward rotation direction P, the solenoid 166b corresponding to the brake shoe 110b is selected, and when the direction of the reverse rotation direction Q is predicted, the brake shoe Solenoid 166a corresponding to 110a is selected. In S6, current is supplied to the selected solenoid 166b (eg, when it is predicted that torque in the forward rotation direction P will be applied), and the pin 160b moves forward and engages the brake shoe 110b. In S7, the cables 22 and 24 are pulled, and the pressing mechanism 120 is operated.

The execution of S7 is shown in the flowchart of FIG. In S31, the electric motor 10 is rotated in one direction. In S32, the tension is detected by the tension sensor 90. In S33, it is determined whether or not the detected tension has reached the target tension. In this embodiment, the target tension is determined to be a magnitude that can keep the vehicle stopped. For example, when the inclination angle of the road surface on which the vehicle is stopped is large, it is determined to be a larger value when it is small, and when the vehicle is stopped on a downhill, the shift position is the forward instruction position, otherwise A larger value is determined. In addition, when the vehicle is stopped on an uphill, if the shift position is the reverse instruction position, the value is determined to be larger than that when it is not. In any case, when the target tension is reached, the electric motor 10 is stopped in S34.
When the cables 22 and 24 are pulled, the pin 160b is engaged with the brake shoe 110b, and the brake shoe 110b is hardly separated from the anchor member 106. Therefore, the brake shoe 110a is moved by the pressing mechanism 120, and the brake shoe 110b is not moved. The circumferential force applied to the brake shoe 110 a is transmitted to the brake shoe 110 b via the adjuster 108, and the brake shoe 110 b is pressed against the anchor member 106.

If the operation of the parking switch 210 is not detected in S1 of the flowchart of FIG. 8, it is determined in S8 whether or not the parking brakes 18 and 20 are in the applied state. If the parking brakes 18 and 20 are in the applied state, the determination in S8 is YES, and in S9, it is determined whether or not the service brake switch 227 is in the ON state (the service brake 99 is in the activated state). In S10, it is determined whether or not the set time has elapsed since the parking brakes 18 and 20 were activated (after the cable tension reached the target tension and the electric motor 10 was stopped). The set time is a time determined based on the time from when the driver normally performs the locking operation of the parking switch 210 until the operation of the service brake operation member (not shown) is released.
In the operation state of the parking brakes 18 and 20, the service brake 99 is in the operation state, and before the set time elapses, S1, 8 to 10 are repeatedly executed, and the solenoid 166b is maintained in the ON state. If the service brake 99 is released while S1, 8 to 10 are repeatedly executed, the determination in S9 is NO and the solenoid 166b is turned off in S11. The predicted torque is applied, and the secondary shoe 110b is pressed more strongly against the anchor member 106. In this state, the pin 160b does not need to be engaged with the brake shoe 110b.
Even if the service brake 99 is not released, the solenoid 166b is turned off when the set time has elapsed. This is because it is not desirable that the energization time of the solenoid 166b is too long.
Thus, in the parking brakes 18 and 20, the engagement state between the pin 160 and the brake shoe 110 is maintained until the torque is actually applied, so that the pressing mechanism 120 moves in the circumferential direction during that time. Can be favorably avoided, and the looseness of the cables 22 and 24 can be satisfactorily suppressed.
Further, since the pin 160 is biased to the non-engagement position by the spring 164, the pair of brake shoes 110a and 110b can be surely expanded even if a failure occurs in the electrical system.

On the other hand, when the release instruction operation of the parking switch 210 is performed, the determination in S2 is NO, and the parking brakes 18 and 20 are released in S12. As shown in the flowchart of FIG. 10, in S51, the electric motor 10 is rotated in the reverse direction. In S52, the detection value by the tension sensor 90 is read. In S53, the detection value can be regarded as almost zero. It is determined whether or not the value is below the value. While the values are larger than the set value, S52 and 53 are repeatedly executed. When the value is less than the set value, the supply current to the electric motor 10 is set to 0 in S54. The pair of brake shoes 110a and 110b are reduced in diameter by a return spring 115 or the like and returned to a predetermined non-operating position.
In S55, the current supply to the solenoid 166b is turned off. In most cases, the current supply to the solenoid 166b is turned off before the release operation of the parking switch 210 is performed, but the release operation is performed before the current supply to the solenoid 166b is turned off. In this case, it is not desirable that the current continues to be supplied to the solenoid 166b. S55 is a step provided to avoid this.

As described above, in the present embodiment, the movement suppression control unit is configured by the part that stores S1-6 of the parking brake control program represented by the flowchart of FIG. 8 of the electric parking brake ECU 200, the part that executes the parking brake control program, and the like. The movement suppression control unit and the movement suppression mechanism (a solenoid 166 as an electric drive source, a pin 160 as a movement suppression member, etc.) 150 constitute a movement suppression device. The pin 160 is an aspect of the engagement rod.
Moreover, a drive source control part is comprised by the part which memorize | stores S1,2,6 of the movement suppression control part, the part to perform, etc., and the torque direction prediction part is comprised by the part which memorize | stores S3-5, the part to perform, etc. Composed.
Furthermore, the pressing device control unit is configured by a part that stores S5 and S6 of the electric parking brake ECU 200, a part that executes the part, and the like.
Of the movement restraining devices, the housings 162a and 162b constitute a movement restraining member retaining device and a linearly movable retaining portion.

The current supply to the solenoid 166 can be turned off after the cable tension reaches the target tension. By doing so, the power consumption of the solenoid 166 can be further reduced. This is effective when the pressing mechanism 120 is fixedly provided on the backing plate 100.
Further, the structure of the movement suppressing mechanism is not limited to that in the above embodiment. For example, in the above-described embodiment, the spring 164 is disposed in a state of urging the pin 160 to the non-engagement position, but may be disposed in a state of urging the pin 160 to the engagement position. In that case, the current supply to the solenoid 166 may be turned off in the operation state of the parking brakes 18 and 20. Further, the housing 162, the solenoid 166, and the like can be provided on the side of the backing plate 100 opposite to the side on which the pair of brake shoes 110a, b is provided.

Further, the movement restraining mechanism can have the structure shown in FIGS. In the present embodiment, notches 298a and 298 as engaging portions are formed in the anchor member side portions from the center of the webs 151a and b of the pair of brake shoes 110a and 110b, respectively. The movement suppression mechanism 300 corresponds to each of the engagement claws 302a and 302b as a pair of movement suppression members, main bodies (housings) 303a and 303b that respectively hold the engagement claws 302a and b, and the engagement claws 302a and 302b. Electric motors 304a, b serving as electric drive sources provided, and springs 306a, b (illustration of 306b is omitted) for urging the engaging claws 302a, b to the non-engaging positions, respectively. .
The housings 303a and 303b are positions where the engaging claws 302a and 302b can engage with the notches 298a and b of the pair of brake shoes 110a and 110b when the parking brakes 18 and 20 are not in operation. Are provided respectively. The housings 303a, b are provided on the output shafts 316a, b of the electric motors 304a, b so as not to rotate relative to each other, and the engaging claws 302a, b are provided so as to be rotatable integrally with the housings 303a, b. .
The springs 306a and 306b are respectively provided between the engaging claws 302a and b and the backing plate 100, and the electric motors 304a and 304b are arranged on the side of the backing plate 100 on which the pair of brake shoes 110a and b are disposed. Is fixedly provided on the opposite side.
The shape and size of the notches 298a, b are such that the movement of the brake shoes 110a, b in a direction away from the anchor member 106 is suppressed in a state in which the engaging claws 302a, b are engaged, and the notch 298a, b approaches the anchor member 106. The size and shape allow the movement.

The movement suppression mechanism 300 is controlled in the same manner as in the above embodiment. In S6, 11, and 55 of the flowcharts of FIGS. 8 and 10 of the above embodiment, the selected solenoid may be replaced with the selected electric motor.
When the direction of the torque predicted to be applied to the wheels is the forward rotation direction P in the stop state of the vehicle, the electric motor 304b is selected. The electric claw 302b is rotated clockwise in FIG. 11 against the urging force of the spring 306b by the electric motor 304b, and engages with the notch 298b. Thereby, the separation of the secondary shoe 110b from the anchor member 106 is suppressed. Further, when the service brake 99 is released after the parking brakes 18 and 20 are operated, the current supply to the electric motor 304 is turned off. The engaging claw 302b is returned to the non-engaging position by the urging force of the spring 306b.
When the predicted direction of the torque is the backward rotation direction Q, the electric motor 304a is selected. The engaging claw 302a is rotated counterclockwise in FIG. 11 against the urging force of the spring 306a, and the claw portion 314a is engaged with the notch 298a. Accordingly, the movement of the secondary shoe 110a in the direction away from the anchor member 106 is suppressed, and a decrease in braking force when torque is applied can be suppressed.
In the present embodiment, the main bodies 303a and 303b correspond to the movement suppressing member holding device. The movement suppressing member holding device is also a rotation type holding unit.

  It is not essential to provide the springs 306a and 306b. In that case, even when the engaging claws 302a, b are engaged with the notches 298a, b of the secondary shoes 110a, b, even if the supply current to the electric motors 304a, b is set to 0, their engaged state Can be maintained.

The movement restraining mechanism can have the structure shown in FIGS. When the movement suppression mechanism 350 in the present embodiment is compared with the movement suppression mechanism 300 shown in FIGS. 11 and 12 described above, the movement suppression mechanism 350 can connect the main bodies (housings) 303a, b of the pair of engaging claws 302a, b. The point including the wire 352 to be connected, the electric motor corresponding to the engagement claw 302a is not provided, the point that the housing 303a is rotatably held by the support pin 354, the spring 306b corresponding to the engagement claw 302b The difference is that is not provided. The wire 352 is wound around each of the housings 303a and 303b so as not to rotate relative to each other. In this embodiment, at least one wire 352 is fixed to each of the housings 303a and 303b.
In the present embodiment, the urging force of the spring 306a is in a first state where the engaging claw 302b is in the engaged position and the engaging claw 302a is in the non-engaged position with no current supplied to the electric motor 304b.

  When the predicted direction of torque is the forward rotation direction P, the electric motor 304b is maintained in the first state in which no current is supplied. Since the engaging claw 302b is engaged with the brake shoe 110b, when the pressing mechanism 120 is operated, the separation of the brake shoe 110b from the anchor member 106 is suppressed. In this case, the first state is maintained even during the operation of the parking brakes 18 and 20 and after the parking brakes 18 and 20 are released. Regardless of whether or not the parking brakes 18 and 20 are operated, the engagement state between the engagement claw 302b and the brake shoe 110b is maintained, but this does not cause a problem. The movement suppression mechanism 350 is kept in the first state until it is necessary to switch to the second state.

If the predicted direction of torque is the backward rotation direction Q, the electric motor 304b is operated. The engagement claw 302b is rotated to the non-engagement position, and the engagement claw 302a is rotated to the engagement position against the urging force of the spring 306a. The engagement claw 302a is engaged with the notch 298a, and the engagement claw 302b is not engaged with the notch 298b. As a result, the movement of the brake shoe 110a away from the anchor member 106 is suppressed. In the second state, the holding current is continuously supplied to the electric motor 304b.
In this case, when the service brake 99 is released, the supply current to the electric motor 304 is set to zero. The pair of engaging claws 302a and 302b are rotated clockwise in FIG. 13 by the biasing force of the spring 306a, but the engaging claws 302b and the notches 298b are not engaged. However, if the parking brakes 18 and 20 are released and the brake springs 110a and 110b are returned to the non-operating position (the position when the parking brakes 18 and 20 are in the non-operating state) by the return spring 115, The first state.

The parking brake control program represented by the flowchart of FIG. 15 is executed at predetermined time intervals. Steps in which the same execution is performed as in the parking brake control program shown in the flowchart of FIG. 8 are given the same step numbers and description thereof is omitted.
In S5a, the direction of torque is predicted, and in S6a, it is determined whether or not the predicted direction of torque is the forward rotation direction P. In the forward rotation direction P, the cables 22 and 24 are pulled in S7. However, in the backward rotation direction Q, in S6b, the electric motor 304b is operated to enter the second state. After switching, the cables 22, 24 are pulled.
While the parking brakes 18 and 20 are operating, it is determined in S8a whether or not the vehicle is in the second state. When in the first state, S9 and 10 are not executed, but when in the second state, S9 and 10 are executed and the service brake 99 is released, or the parking brake When the set time has elapsed since the operation of 18, 20, the electric motor 304b is turned off in S11a.
Thus, in the present embodiment, when the predicted direction of the torque is the forward rotation direction P, there is an advantage that it is not necessary to operate the electric motor 304b. Moreover, when the parking brakes 18 and 20 are operated while stopped on a horizontal road surface, the probability that the shift position is in the forward instruction position is considered to be higher than the probability that the shift position is in the reverse instruction position. Therefore, the frequency with which the predicted direction of the torque is the forward rotation direction P is higher than the frequency with which the predicted rotation direction P is the reverse rotation direction Q. Therefore, if no current is supplied to the electric motor 304b and the first state is maintained, power consumption can be reduced. Further, in the first state, even if an electric system failure occurs, the brake shoes 110a can be moved in the circumferential direction, so that the parking brakes 18 and 20 can be applied.

  In addition, the engaging part provided in the web 151 of the brake shoe 110 can be an engaging protrusion, not a notch. For example, when the brake shoe 110 is engaged with the engagement claw 302, an engagement protrusion is formed on the anchor member 106 side of the engagement claw 302. Due to the engagement between the engagement protrusion and the engagement claw 302, the movement of the brake shoe 110 away from the anchor member 106 is suppressed.

The movement restraining mechanism may have a structure conceptually shown in FIG. In the present embodiment, engagement protrusions 398a, b are formed at the anchor side ends of the webs 151a, b of the pair of brake shoes 110a, b, respectively. The engaging protrusions 398a, b are provided on the surface of the webs 151a, b opposite to the side facing the backing plate 100. On the other hand, the movement suppressing mechanism 400 includes a housing (holding portion) 402 fixed to the anchor member 106 (either the anchor member 106 may be used as a housing or fixed to the anchor member 106), The engaging rods 404a and b are integrally formed with the engaging rods 406. The engaging rod 406 is held by the housing 402 so as to be relatively movable in the axial direction thereof. The engagement rod 406 is operated by an electric drive source (not shown). The electric drive source is, for example, a solenoid or a piezoelectric element that applies a driving force to the engagement rod 406 on the right side in FIG. 16 (Q tangential direction, but hereinafter referred to as Q direction), and the left side. It may include a solenoid, a piezoelectric element, or the like that applies a driving force (hereinafter abbreviated as P direction). As the engagement rod 406 moves in the axial direction, either one of the engagement claws 404a, b can be selectively engaged with either one of the engagement protrusions 398a, b of the brake shoes 110a, b. .
In the engagement rod 406, the engagement claws 404a, b are provided in a state of projecting toward the brake shoes 110a, b (a state facing the brake shoes 110a, b), respectively, and a pair of engagement claws 404a, b The length in the axial direction between the pair of brake shoes 110a, b in the non-operating state of the parking brakes 18, 20 (returned by the return spring 115) is the length between the engagement protrusions 398a, b of the pair of brake shoes 110a, b. In a state where one engagement claw 404a is engaged with the engagement protrusion 398a of one brake shoe 110a, the other engagement claw 404b is disengaged from the engagement protrusion 398b of the other brake shoe 110b. The other brake shoe 110b is allowed to move away from the anchor member 106.

For example, when the predicted direction of torque is the forward rotation direction P, a driving force in the P direction is applied to the engagement rod 406 by the electric drive source. The engagement rod 406 is moved linearly in the P direction in the axial direction, the engagement claw 404b is engaged with the engagement protrusion 398b, and the engagement claw 402a is disengaged from the engagement protrusion 398a. It becomes. The anchor member 106 and the brake shoe 110b are connected by the engagement rod 406, and the movement of the brake shoe 110b in the direction away from the anchor member 106 is suppressed. Due to the operation of the pressing mechanism 120, the brake shoe 110a is moved, and the parking brakes 18 and 20 are put into an operating state. Thereafter, when the service brake switch 227 is turned off, the current supply to the electric drive source is turned off, and no driving force is applied to the engagement rod 406.
When the predicted direction of the torque is the backward rotation direction Q, a driving force in the Q direction is applied to the engagement rod 406 by the electric drive source. The engagement rod 406 is moved in the Q direction, the engagement claw 404a is engaged with the engagement protrusion 398a, and the engagement claw 404b is disengaged from the engagement protrusion 398b. The movement of the brake shoe 110a away from the anchor member 106 is suppressed.
In the present embodiment, an engagement rod 406 as a movement restraining member is provided in common for the pair of brake shoes 110a and 110b.
The engagement rod 406 is biased to the first state by a spring provided between the engagement rod 406 and the main body 402, and the electromagnetic driving force by the solenoid resists the biasing force of the spring. It can be made to move to a 2nd state by giving to a joint rod.

The movement restraining mechanism may have a structure conceptually shown in FIGS. 17 (a) and 17 (b). In the present embodiment, in the movement suppressing mechanism 450, the anchor member 106 is a housing 452, and the engagement rod 454 is held by the housing 452 so as to be relatively movable in the axial direction. A pair of groove portions 460a and 460b are formed at both ends of the engagement rod 454 in the axial direction, and the pair of engagement claws 462a and 462b can rotate around the rotation shafts 464a and 464b, respectively. Retained. Each of the engaging claws 462a and 462 is urged to a non-engaging position by a spring (not shown). The groove portions 460a and b extend in the axial direction, have a size and a length that can accommodate the pair of brake shoes 110a and b, and the groove portions 460a and b of the pair of brake shoes 110a and b respectively Relative movement is allowed.
The groove portions 460a, b are respectively formed by a pair of protrusions 466a, b and protrusions 468a, b, and one protrusion 468a, b is longer in the axial direction than the other protrusion 466a, b. . The engaging claws 462a, b are held by the other protrusions 466a, b, the engaging claws 462a, b face the one protrusions 468a, b, and the engagement claws 462a, b and the protrusions 468a, b As a result, the brake shoes 110a and 110b are sandwiched.
On the other hand, pressing portions (cams) 470a and 470b are formed at both ends of the anchor 452 in the axial direction, respectively, and are shaped so as to be separated from the brake shoe 110 toward the outside in the axial direction.
As the electric drive source, the same one as in the embodiment shown in FIG. 16 can be adopted.

In the non-brake action state, both ends of the pair of brake shoes 110a and 110b are in contact with the anchor 452. When the predicted direction of torque is the P direction, the engagement rod 454 is moved in the P direction. Although the brake shoe 110a is moved relative to the groove 460a, the brake shoe 110a does not abut against the bottom of the groove 460a, so that no pressing force is applied. On the other hand, the engaging claw 462b is rotated to the engaging position by the pressing portion 470b. The brake shoe 110b is gripped by the engaging claw 462b and the protrusion 468b, and movement in the circumferential direction is suppressed.
When the pressing device 120 applies a pressing force in the expanding direction to the pair of brake shoes 110a and 110b, the movement of the brake shoe 110b in the direction away from the anchor 452 is suppressed. It is held in a state of contacting The brake shoe 110a is moved in the circumferential direction, transmitted to the brake shoe 110b via the adjuster 108, and pressed against the anchor 452. In this embodiment, even if the current supplied to the solenoid or the like is turned off in this state (even if the electric driving force is turned off), the movement of the brake shoe 110b in the circumferential direction is suppressed. Therefore, there is an advantage that it is not necessary to supply power to the solenoid until the service brake 99 is released.
When the predicted direction of torque is the Q direction, the engagement rod 454 is moved in the Q direction. The brake shoe 110b is moved relative to the groove portion 460b, and the brake shoe 110a is gripped by the engaging claw 464a and the protrusion 468a. Thereby, the movement of the brake shoe 110a in the direction away from the anchor 452 is suppressed. When a pressing force is applied to the brake shoes 110 a and b by the pressing device 120, the movement of the brake shoe 110 a is suppressed and the brake shoe 110 a is pressed against the anchor 454.

  In the above-described embodiment, the engagement portions are not provided in the brake shoes 110a, b, but the recesses as the engagement portions in the portions facing the engagement claws 462a, b of the webs 151a, b, or An engagement hole can also be formed. Moreover, the recessed part or the engagement hole may have a shape extending in the circumferential direction. In those cases, it is not essential that the protrusions 468a, b are longer than the opposing protrusions 466a, b.

  As described above, a plurality of embodiments of the present invention have been described. However, in addition to the above-described embodiments, the present invention can be implemented in various modifications and improvements based on the knowledge of those skilled in the art. it can.

1 is a diagram conceptually showing an entire parking brake system according to an embodiment of the present invention. It is a partial cross section figure showing the electric motor and motion conversion mechanism which are included in the said electric parking brake system. It is AA sectional drawing (sectional drawing of a clutch) of the said motion conversion mechanism. It is a top view of the drum brake contained in the said parking brake system. It is a front view (part cross section) showing the pressing mechanism and movement suppression mechanism of the drum brake. It is a figure which shows the relationship between a cable tension | tensile_strength and brakeable torque in the said parking brake system. It is a figure which shows the relationship between the gradient of the road surface and the longitudinal acceleration which the vehicle has stopped. It is a flowchart showing the parking brake control program memorize | stored in the memory | storage part of electric parking brake ECU of the said parking brake system. It is a flowchart showing a part (brake operation | movement) of the said program. It is a flowchart showing the other part (brake release) of the said program. It is a top view which shows the movement suppression mechanism different from the said movement suppression mechanism. It is a front view (partial cross section) of the said movement suppression mechanism. It is a top view which shows another movement suppression mechanism different from the said movement suppression mechanism. It is a front view (partial cross section) of the said movement suppression mechanism. It is a flowchart showing another parking brake control program memorize | stored in the memory | storage part of the said electric parking brake ECU. It is a figure which shows notionally the movement suppression mechanism different from the said movement suppression mechanism. (a) The movement suppression mechanism is a diagram conceptually showing another movement suppression mechanism. (b) It is AA sectional drawing of Fig.17 (a).

Explanation of symbols

  10: Electric motor 12: Motion conversion mechanism 18, 20: Drum brake (parking brake) 22, 24: Cable 104: Drum 106: Anchor member 108: Adjuster 110a, b: Brake shoe 120: Pushing mechanism 122: Brake lever 124: Strut 150, 300, 350, 400, 450: Movement suppression mechanism 151a, b: Web 152a, b: Notch 160a, b: Housing 162a, b: Pin 164a, b: Spring 166a, b: Solenoid 298a, b: Notch 302a , B: engagement claw 303a, b: housing 304a, b: electric motor 306a, b: spring 352: wire 398a, b, 448a, b: engagement protrusion 404a, b, 462a, b: engagement claw 406, 454: Engagement 468a, b: opposing protrusion 470a, b: pressing part

Claims (9)

A non-rotating body,
A rotating drum that rotates with the wheels of the vehicle and whose inner peripheral surface is a friction surface;
A pair of brake shoes disposed on the inner peripheral side of the rotating drum and having a friction material on the outer peripheral surface;
An anchor member fixed to the non-rotating body between one end portions of the pair of brake shoes,
The ends of the pair of brake shoes opposite to the side on which the anchor member is provided are connected to each other, and a circumferential force applied to one of the pair of brake shoes is transmitted as an input to the other brake shoe. A transmission member that,
A parking brake system provided with a duo-servo type drum brake, which is provided on the one end side of the pair of brake shoes and includes a pressing device that presses the friction material of the pair of brake shoes against the inner peripheral surface of the drum.
(a) an electric drive source; and (b) actuated by the electric drive source and engage with each of the pair of brake shoes to thereby form the non-rotating body and the anchor member of each of the pair of brake shoes. And (c) predicting the direction of torque applied to the wheels when the vehicle is stopped, and operating the pressing device based on the prediction. Previously, the electric drive source is controlled so that one of the at least one movement restraining member is engaged with a secondary shoe when the torque is applied, and the pressing device is operated. And a movement suppression device including a movement suppression control unit that suppresses the movement of the secondary shoe in a direction away from the anchor member. Rake system.   The movement suppression control unit is (a) an inclination detection device that detects an inclination direction of a road surface on which the vehicle is stopped, and (b) the road surface inclination direction detected by the inclination detection device based on the inclination direction of the road surface. The parking brake system according to claim 1, further comprising a torque direction prediction unit that predicts a direction of torque applied to the wheel.   The movement suppression control unit includes a drive source control unit that controls the electric drive source according to a parking brake operation command, and the parking brake system is controlled after the electric drive source is controlled by the drive source control unit. The parking brake system according to claim 1, further comprising a pressing device control unit that operates the pressing device.   The movement suppression member is provided corresponding to each of the pair of brake shoes, and the movement suppression device is fixedly provided on one of the non-rotating body and the anchor member, and the drum brake In the non-operating state, each of the movement suppressing members is movably held between an engagement position that engages with the pair of brake shoes and a non-engagement position that is disengaged from the brake shoes. The parking brake system according to any one of claims 1 to 3, comprising a restraining member holding device.   Each of the movement suppression members is an engagement rod, each of the pair of brake shoes has an engagement portion with the movement suppression member, and the movement suppression member holding device is the non-rotating body, The drum brake is provided at a position corresponding to each engaging portion of the pair of brake shoes in a non-acting state of the drum brake, and the engaging rod is linearly moved between the engaging position and the non-engaging position. A linear movement type holding part that holds the movable part, and the movement suppressing device is provided between each of the linear movement type holding part and each of the engagement rods, and the engagement rods are not engaged. A biasing member for biasing the position, wherein the electric drive source is provided corresponding to each of the engagement rods, and the engagement rod is opposed to the biasing force of the biasing member, From the disengaged position to the engaged position Parking brake system according to claim 4 comprising a solenoid applying an electromagnetic driving force to move the.   Each of the movement suppressing members is an engaging claw, each of the pair of brake shoes has an engaging portion with the engaging claw, and the movement suppressing member holding device is in an inoperative state of the drum brake. And the engagement position for engaging each of the engagement claws with the engagement portion of the brake shoe, respectively. A rotation-type holding portion that holds the electric drive source so as to be rotatable with respect to a non-engagement position that is disengaged from the portion, and the electric drive source is provided corresponding to each of the engagement claws, The parking brake system according to claim 4, further comprising an electric motor that rotates the motor between the engagement position and the non-engagement position.   Each of the movement suppressing members is an engaging claw, each of the pair of brake shoes has an engaging portion with the engaging claw, and the movement suppressing member holding device is in an inoperative state of the drum brake. And the engagement position for engaging each of the engagement claws with the engagement portion of the brake shoe, respectively. A rotation-type holding portion that is rotatably held between a non-engagement position that is disengaged from the portion, and the electric drive source is provided corresponding to one of the two engagement claws. An electric motor that rotates between the engagement position and the non-engagement position, and the movement suppressing device includes a drive transmission mechanism that transmits rotation of the electric motor to the other engagement claw. 4. The parking brake system according to 4.   Each of the movement restraining members is an engaging claw, and the two engaging claws are integrally movable in the axial direction, and the movement restraining control unit is configured such that one of the two engaging claws is a pair of the pair. A first state in which one of the brake shoes is engaged and the other engagement claw is not engaged with the other brake shoe; and the other engagement claw is engaged with the other brake shoe, and the one engagement claw The parking brake system according to claim 4, further comprising means for switching between a second state in which the first brake shoe is not engaged with the second brake shoe.   The pressing device is operated by an electric motor, and includes a holding mechanism that holds a friction material pressing force that is a pressing force of the friction material against the friction surface in a state where no current is supplied to the electric motor. The parking brake system according to any one of claims 1 to 8.

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