JP2010236656A - Disc brake device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To appropriately adjust return amount of an electric motor of a parking brake mechanism when a parking brake is released. <P>SOLUTION: During operation of the parking brake, liquid pressure is supplied to inside of a cylinder 36, a feed screw 44 is rotated in the advancing direction of a locknut 40 by the electric motor 49, and a brake pad is pressed by the liquid pressure applied to a piston 38 and the locknut 40. The braking state is held by the locknut 40. During release of the parking brake, after liquid pressure within the cylinder 36 is released, a port 36A is closed to seal inside of the cylinder 36, and with the locknut 40 restricted by brake fluid, the feed screw 44 is rotated in the retracting direction of the locknut 40 by the electric motor 49. Thus, by stopping the electric motor 49 when it reaches stall electric current, return amount of the electric motor 49 is adjusted. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a disc brake device for a vehicle provided with a parking brake mechanism.

  In a hydraulic disc brake for a vehicle, for example, as described in Patent Document 1, a parking brake mechanism that can maintain a braking state even after releasing the hydraulic pressure after generating a braking force by the hydraulic pressure There is something with. In the technique described in Patent Document 1, the piston is advanced by hydraulic pressure, the brake pad is pressed against the disc rotor to generate a braking force, and in this state, the parking brake mechanism is operated by the electric motor to brake the piston. Hold in position. As a result, the braking state can be maintained even after the hydraulic pressure is released, and it can be used as a parking brake.

JP 2007-177996 A

  However, the one described in Patent Document 1 has the following problems. When releasing the parking brake, the nut member holding the piston is moved backward by rotating the electric motor in the direction opposite to that when the parking brake is operated. At this time, it is difficult to accurately determine the return position of the electric motor, and if the return amount is insufficient, the brake feeling is lowered due to movement of the nut member due to hydraulic pressure during normal braking, and the return amount If it exceeds, the responsiveness at the time of parking brake operation will fall.

  An object of this invention is to provide the brake device which can adjust appropriately the return amount of the electric motor of a parking brake mechanism at the time of parking brake cancellation | release.

In order to solve the above problems, a disc brake device according to the present invention includes a pair of brake pads arranged on both sides of a disc rotor, a cylinder, and a piston inserted into the cylinder, The piston is propelled by supplying hydraulic pressure into the cylinder, the pair of brake pads are pressed against the disc rotor to generate a braking force, and the brake pad is moved by supplying hydraulic pressure into the cylinder. When pressing against the disc rotor, an electric motor is used as a drive source, and a parking brake mechanism that mechanically holds the piston in the braking position even after the hydraulic pressure from the cylinder is released, and a predetermined hydraulic pressure is supplied to the cylinder A hydraulic pressure supply device, and a parking brake control device that controls the operation of the hydraulic pressure supply device and the electric motor,
The piston comprises a first piston having a first pressure receiving area and a second piston having a second pressure receiving area with respect to the hydraulic pressure in the cylinder,
When the parking brake is released, the parking brake control device releases the predetermined hydraulic pressure in the cylinder and then energizes the electric motor in a state where the second piston is restrained by the hydraulic pressure. When the electric motor is rotated in the parking brake release direction and the electric motor reaches a predetermined stall current value, energization of the electric motor is stopped.

  According to the disc brake device of the present invention, the return amount of the electric motor of the parking brake mechanism can be appropriately adjusted when the parking brake is released.

It is a block diagram showing a schematic structure of a disc brake device concerning one embodiment of the present invention. FIG. 2 is a hydraulic circuit diagram showing a configuration of a hydraulic pressure generation source of the disc brake device of FIG. 1. It is a longitudinal section of a disc brake provided with a parking brake mechanism of a disc brake device concerning one embodiment of the present invention. It is a longitudinal cross-sectional view which expands and shows the threaded part of the lock nut and feed screw of the disc brake of FIG. It is a time chart which shows control of the parking brake mechanism by the parking brake control apparatus of the disc brake apparatus of FIG. It is a time chart which shows control of the parking brake mechanism by the parking brake control apparatus in the modification of the disc brake apparatus of FIG.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 shows a schematic configuration of the disc brake device according to the present embodiment. As shown in FIG. 1, a disc brake device 1 is a brake device mounted on an automobile, and includes disc brakes 2A and 2B mounted on the front two wheels, and a disc with a parking brake mounted on the rear two wheels, respectively. The brakes 3A and 3B, the hydraulic pressure supply device 4 for supplying hydraulic pressure to these disc brakes 2A, 2B, 3A and 3B, the master cylinder 5 for generating hydraulic pressure, and the parking brake control of the disc brakes 3A and 3B And a parking brake control device 6 for carrying out.

  The disc brakes 2A, 2B and 3A, 3B generate braking force by pushing the brake pad 8 by advancing the piston by hydraulic pressure against the disc rotor 7 rotating together with the wheels. Further, the disc brakes 3A and 3B mounted on the rear two wheels are provided with parking brake mechanisms 9A and 9B for holding the braking force even after the hydraulic pressure is released, which will be described in detail later. Pressure sensors 10A, 10B, 11A, and 11B that detect supply hydraulic pressure are connected to the disc brakes 2A, 2B, 3A, and 3B, respectively. Various sensors such as the hydraulic pressure supply device 4, the parking brake control device 6, the pressure sensors 10A, 10B, 11A, and 11B and the in-vehicle devices are connected to each other by an in-vehicle network system (CAN) and exchange various signals. It is like that.

  The master cylinder 5 generates hydraulic pressure by operating the brake pedal 12 by the driver. At this time, the booster 13 assists the operating force of the brake pedal 5. The master cylinder 5 is connected to a brake sensor 14 that detects an operation (displacement, pedaling force, etc.) of the brake pedal 12. The master cylinder 5 is a tandem type and is provided with two systems of output ports 5A and 5B.

  The hydraulic pressure supply device 4 distributes and supplies the hydraulic pressure generated in the master cylinder 5 to each of the disc brakes 2A, 2B, 3A, and 3B according to the operation of the brake pedal 12 by the driver to generate a braking force. Further, based on vehicle information detected by various sensors such as the hydraulic pressure sensors 10A, 10B, 11A, 11B, and the brake sensor 14, and on-vehicle equipment, the fluid pressure pump 29, which will be described later, changes the disc brakes 2A, 2B, 3A, 3B Brake such as boost control, braking force distribution control, brake assist control, anti-lock control, traction control, vehicle stabilization control, slope start assist control, etc. by controlling the hydraulic pressure to be supplied by ECU (Electronic Control Unit) 4A Execute control.

  Here, the hydraulic pressure supply device 4 will be described in more detail with reference to FIG. As shown in FIG. 2, the hydraulic pressure supply device 4 is connected to one output port 5A of the master cylinder 5 and supplies a hydraulic pressure to the disc brakes 2A and 3B of the left front wheel and the right rear wheel. And a second hydraulic system that is connected to the other output port 5B and supplies a hydraulic pressure to the disc brakes 2B and 3A for the right front wheel and the left rear wheel. Since the first hydraulic system and the second hydraulic system have the same structure, only the first system will be described below. Further, in FIG. 2, “′” is added to the reference numerals of the corresponding components of the first hydraulic system for the respective components of the second hydraulic system.

  The hydraulic pressure supply device 4 has a main pipeline 15 connected to the output port 5A of the master cylinder 5, and the main pipeline 15 branches into two, a first main pipeline 16 and a second main pipeline 17, and a disc brake. Connect to 2A and 3B, respectively. A master cylinder shut-off control valve 18 and a check valve 19 are provided in the main line 15 in parallel. The master cylinder shut-off control valve 18 is a normally open solenoid valve that opens and closes the main line 15, and the check valve 19 allows only the flow of brake fluid from the master cylinder 5 side of the main line 15. The first main pipeline 16 is provided with a pressure increase control valve 20 and a check valve 21 in parallel. The pressure increase control valve 20 is a normally open solenoid valve that opens and closes the first main pipeline 16, and the check valve 21 allows only the flow of brake fluid from the disc brake 2 </ b> A side of the first main pipeline 16. The second main pipeline 17 is provided with a pressure increase control valve 22 and a check valve 23 in parallel. The pressure increase control valve 22 is a normally open solenoid valve that opens and closes the second main pipeline 17, and the check valve 23 allows only the flow of brake fluid from the disc brake 3 B side of the second main pipeline 17.

  The hydraulic pressure supply device 4 includes first and second pressure reducing lines 25 and 26 that connect the disk brakes 2A and 3B and the reservoir 24, respectively. The first and second pressure reducing lines 25 and 26 include: Pressure reducing control valves 27 and 28 are provided, respectively. The decompression control valves 27 and 28 are normally closed solenoid valves that open and close the first and second decompression conduits 25 and 26, respectively.

  Further, the hydraulic pressure supply device 4 includes a hydraulic pressure pump 29 that is a hydraulic pressure source, and the discharge side of the hydraulic pressure pump 29 is connected to the master cylinder shutoff valve 18 and the check valve of the main line 15 via the check valve 30. 19 is connected to the downstream side, and the suction side is connected to the reservoir 24 via check valves 31 and 32. The suction side of the hydraulic pump 29 is connected to the upstream side of the master cylinder shutoff control valve 18 and the check valve 19 in the main line 15 via a check valve 31 and an on-off valve 33 which is a normally closed solenoid valve. .

  Thus, normally, the hydraulic pressure generated in the master cylinder 5 by the driver's brake operation is supplied directly to the disc brakes 2A and 3B via the main line 15 and the first and second main lines 16 and 17. For example, when executing anti-lock control or the like, the pressure increase control valves 20 and 22 are closed, the hydraulic pressures of the disc brakes 2A and 3B are held, and further, the pressure reduction control valves 27 and 28 are opened, The hydraulic pressures 2A and 3B are released to the reservoir 24, and the hydraulic pressures of the disc brakes 2A and 3B are reduced. The control valves 18, 18 ', 20, 20', 22, 22 ', 27, 27', 28, 28 ', the hydraulic pump 29, and the on-off valves 33, 33' are connected to the ECU 4A. Is controlled by.

  For example, when the hydraulic pressure supplied to the disc brakes 2A and 3B is increased when executing vehicle stabilization control or the like, the master cylinder shut-off control valve 18 is closed and the hydraulic pump 29 is operated to operate the main pipeline. 15, the hydraulic pressure of the hydraulic pump 29 is supplied to the disc brakes 2A and 3B. At this time, the on-off valve 33 is opened as needed to supply brake fluid from the master cylinder 5 side to the suction side of the hydraulic pump 29.

  Then, based on vehicle information detected by various sensors, vehicle-mounted devices, etc., the ECU 4A controls the master cylinder cutoff control valve 18, the pressure increase control valves 20, 22, the pressure reduction control valves 27, 28, the on-off valve 33, and the hydraulic pump. By controlling the operation of 29 and appropriately holding, reducing and increasing the hydraulic pressure supplied to the disc brakes 2A and 3B, boost control, braking force distribution control, brake assist control, antilock control, traction control, Brake control such as vehicle stabilization control and slope start assist control is executed.

  The parking brake control device 6 is connected to an ECU 4A of the hydraulic pressure supply device 4, an electric motor 49 (described later) provided in the parking brake mechanisms 9A and 9B of the disc brakes 3A and 3B, and a parking brake switch 55. Then, when the driver operates the parking brake switch 55, a control signal is output to the ECU 4A of the hydraulic pressure supply device 4 and the electric motor 49 of the parking brake mechanisms 9A, 9B, and the liquid to the cylinders 36 of the disc brakes 3A, 3B is output. The pressure supply and the operation of the electric motor 49 are controlled to execute the operation and release of the parking brake.

  Next, disc brakes 3A and 3B provided with parking brake mechanisms 9A and 9B will be described with reference to FIGS. Since the disc brakes 3A and 3B have the same structure, the disc brake 3 will be described here.

  As shown in FIG. 3, the disc brake 3 is a caliper floating type hydraulic disc brake, and a pair of brake pads 8 disposed on both sides of the disc rotor 7 that rotates together with the wheels, and a caliper 35 straddling the disc rotor 7. And a carrier (not shown) that is fixed to a non-rotating portion of the vehicle and supports the brake pad 8 and the caliper 35 movably along the axial direction of the disc rotor 7.

  The caliper 35 is provided with a cylinder 36 at a portion facing one brake pad 8, and a claw portion 37 is formed across the disk rotor 7 and facing the other brake pad 8. A bottomed cylindrical piston 38 as a first piston is slidably inserted into the cylinder 36 via a piston seal 39 having a rollback function.

  A lock nut 40 as a second piston is slidably inserted into the piston 38 via a piston seal 41 having a rollback function, and an outer flange portion 42 formed at the rear end portion of the lock nut 40 is provided. It abuts on the rear end of the piston 38. The caliper 35 is provided with a port 36 </ b> A for supplying hydraulic pressure into the cylinder 36. The lock nut 40 is prevented from rotating by inserting an axially extending pin 43 attached to the flange portion 42 into the side wall of the piston 38. Further, the piston 38 is prevented from rotating with respect to the caliper 35. The leading end of the feed screw 44 is screwed into the lock nut 40. The rear end portion of the feed screw 44 is inserted and penetrated through the bottom of the cylinder 36 in a fluid-tight and rotatable manner, and extends to the inside of a drive mechanism 45 attached to the rear end portion of the caliper 35. The feed screw 44 is supported on the bottom portion of the cylinder 36 by a flange portion 46 formed at an intermediate portion thereof, a thrust bearing 47 and a fixing nut 48, and is fixed in the axial direction.

  The drive mechanism 45 is a combination of an electric motor 49 and a speed reduction mechanism including a worm 51 attached to a shaft 50 of the electric motor 49 and a worm wheel 52 that meshes with the worm 51. The worm wheel 52 is connected to the rear end portion of the feed screw 44 that protrudes through the bottom of the cylinder 36. Thereby, the rotation of the electric motor 49 is decelerated and the feed screw 44 is rotationally driven, and the lock nut 40 can be moved forward and backward by the rotation of the feed screw 44. When the electric motor 49 is stopped, the rotation of the feed screw 44 is locked by the meshing of the worm 51 and the worm wheel 52.

  As shown in FIG. 4, the screw portion 53 (female screw) of the lock nut 40 and the screw portion 54 (male screw) of the feed screw 44 that are screwed together are trapezoidal screws having a certain gap δ (play) in the axial direction. In addition, when the axial load is applied between the lock nut 40 and the feed screw 44, the rotation is locked by the frictional force and the movement in the axial direction is fixed. It is like that. 4A shows a state in which the lock nut 40 is displaced in the forward direction with respect to the feed screw 44, and FIG. 4B shows a state in which the lock nut 40 is displaced in the backward direction with respect to the feed screw 44. Indicates the state. The gap δ between the screw parts 53 and 54 is set to be sufficiently larger than the amount of deflection of the piston seals 39 and 41 caused by the axial movement of the piston 38.

Next, the operation of the disc brake 3 will be described.
When the disc brake 3 is used as a service brake that performs braking while the vehicle is running, when hydraulic pressure is supplied from the port 36A to the cylinder 36, the piston 38 moves forward while bending the piston seals 39 and 41. One brake pad 8 is pressed against the disc rotor 7. At this time, the caliper 35 is moved by the reaction force, the claw portion 37 presses the other brake pad 8 against the disc rotor 7, and the disc rotor 7 is sandwiched between the pair of brake pads 8 to generate a braking force. When the hydraulic pressure in the cylinder 36 is released, the piston 38 is retracted by the elastic force of the piston seals 39 and 41 to release the braking. In addition, when the brake pad 8 is worn, slip occurs between the piston seals 39 and 41 when the piston 38 moves forward, and the wear of the brake pad 8 is compensated by following the worn brake pad 8 by the piston 38. Thus, the gap between the disc rotor 7 and the brake pad 8, so-called pad clearance, does not change.

  At this time, the hydraulic pressure in the cylinder 36 acts on the first pressure receiving area of the piston 38 and also acts on the second pressure receiving area of the lock nut 40. However, as shown in FIG. 4A, the lock nut 40 is displaced in the forward direction with respect to the feed screw 44 and is in a restrained position in which the gap δ is eliminated. Therefore, the piston 38 moves forward alone. As a result, the pressure receiving area of the piston 38 becomes the first pressure receiving area obtained by subtracting the second pressure receiving area of the lock nut 40 from the entire cross-sectional area thereof, so that the thrust of the piston 38 is small and the load load on the front wheels is small. A braking force suitable for the rear wheel can be obtained.

  When the disc brake 3 is used as a parking brake, hydraulic pressure is supplied into the cylinder 36 and the feed screw 44 is rotated by the electric motor 49 in the direction in which the lock nut 40 moves forward. As a result, the flange portion 42 of the lock nut 40 abuts against the rear end portion of the piston 38, and the piston 38 and the lock nut 40 that have received the hydraulic pressure move forward together to press the brake pad 8 against the disc rotor 7. To generate braking force. At this time, the piston 38 adds the second pressure receiving area of the lock nut 40 to the first pressure receiving area, and the thrust of the piston 38 is larger than the thrust during service braking. As a result, a large braking force can be obtained with a relatively small hydraulic pressure, and the load of the hydraulic pressure source when the parking brake is operated can be reduced.

  Thereafter, when the hydraulic pressure to the cylinder 36 reaches a predetermined pressure, the electric motor 49 is stopped and the hydraulic pressure to the cylinder 36 is released. At this time, the friction force between the screw nuts 53 and 54 of the lock nut 40 and the feed screw 44 and the engagement between the worm 51 and the worm wheel 52 against the reaction force of the pressing force of the brake pad 8 to the disc rotor 7. When the feed screw 44 and the lock nut 40 are in the restrained state shown in FIG. 4B, the rotation of the feed screw 44 is locked and the lock nut 40 is fixed in the axial direction. Thereby, even if the hydraulic pressure to the cylinder 36 is released and the energization to the electric motor 49 is stopped, the piston 38 can be held at the braking position, and the braking force can be held as a parking brake.

  When releasing the parking brake, a hydraulic pressure slightly higher than the predetermined pressure when the parking brake is operated is supplied to the cylinder 36, and the electric motor 49 is rotated in the direction opposite to that when the parking brake is operated. As a result, an increase in thrust of the piston 38 due to an increase in hydraulic pressure releases the lock due to the frictional force between the screw parts 53 and 54, and the feed screw 44 rotates in the direction opposite to that during the operation of the parking brake, causing the lock nut to rotate. 40 moves backwards. Then, the hydraulic pressure in the cylinder 36 is released, the piston 38 and the lock nut 40 are retracted, and the parking brake is released.

  Next, the parking brake control device 6 outputs a control signal to the ECU 4A of the hydraulic pressure supply device 4 and controls the electric motor 49 when the parking brake is operated and released, and the hydraulic pump 29 of the ECU 4A of the hydraulic pressure supply device 4 And control of each control valve is demonstrated with reference to the time chart shown in FIG. FIG. 5 shows a parking brake switch 55, a gap δ between the screw portions 53 and 54 of the lock nut 40 and the feed screw 44, the hydraulic pressure supplied to the cylinder 36 of the disc brake 3 by the hydraulic pump 29, and the electric motor 49. The operating state of the master cylinder cutoff control valve 18 of the energization current and hydraulic pressure supply device 4 is shown.

  When operating the parking brake, when the parking brake switch 55 is in the operating position at time t1 shown in FIG. 5, a hydraulic pressure supply control signal is output from the parking brake control device 6 to the ECU 4A. In response to this hydraulic pressure supply control signal, the ECU 4A of the hydraulic pressure supply device 4 closes the master cylinder cutoff control valve 18 and starts supplying hydraulic pressure to the cylinder 36 of the disc brake 3 by the hydraulic pump 29. The piston 38 and the lock nut 40 move forward by this hydraulic pressure. Further, at time t1, the parking brake control device 6 starts energization of the electric motor 49 and rotates the feed screw 44 in a direction in which the lock nut 40 is advanced. At time t2, when the ECU 4A of the hydraulic pressure supply device 4 detects that the hydraulic pressure in the cylinder 36 has reached a predetermined pressure at the time of parking brake operation, the ECU 4A ends the pressure increase by the hydraulic pump 29, The electric motor 49 is continuously energized while maintaining the pressure by maintaining the master cylinder shut-off control valve 18 closed. At time t3, when the feed screw 44 moves to the position of FIG. 4B with respect to the lock nut 40 and the gap δ between the screw portions 53 and 54 between the lock nut 40 and the feed screw 44 becomes maximum, the load is reduced. The rotation of the electric motor 49 stops due to the increase. At this time, the parking brake control device 6 can detect the rotation stop of the electric motor 49 by monitoring the stall current of the electric motor 49 by the current detection means 56. At time t4 when a predetermined time has elapsed from time t3, the parking brake control device 6 determines that the rotation of the electric motor 49 is stopped because the stall current has continued for a predetermined time, stops energization of the electric motor 49, and hydraulic pressure A hydraulic pressure release control signal is output to the ECU 4A of the supply device 4. In response to this hydraulic pressure release control signal, the ECU 4A opens the master cylinder cutoff control valve 18 to reduce the hydraulic pressure in the cylinder 36. Then, the hydraulic pressure decreases and the hydraulic pressure is completely released at time t5. Here, the hydraulic pressure pump 29 may be driven by opening the pressure reduction control valve 28 and the on-off valve 33 in order to accelerate the pressure reduction of the cylinder 36.

  As a result, the disc brake 3 locks the piston 38 at the braking position, maintains the braking state, and operates as a parking brake.

  Next, when releasing the parking brake, when the parking brake switch 55 is in the release position at time t6, a hydraulic pressure supply control signal is output from the parking brake control device 6 to the ECU 4A. In response to this hydraulic pressure supply control signal, the ECU 4A of the hydraulic pressure supply device 4 closes the master cylinder cutoff control valve 18 and starts supplying hydraulic pressure to the cylinder 36 of the disc brake 3 by the hydraulic pump 29. When the hydraulic pressure in the cylinder 36 reaches a predetermined hydraulic pressure at the time of release at time t7, the hydraulic pressure is maintained by maintaining the master cylinder cutoff control valve 18 closed. Since the predetermined hydraulic pressure at the time of release is slightly larger than the predetermined hydraulic pressure at the time of operation, the gap δ between the screw portions 53 and 54 between the lock nut 40 and the feed screw 44 is not maximized, and is caused by friction between the screw portions 53 and 54. The lock is released. In this state, the parking brake control device 6 energizes the electric motor 49 to rotate the feed screw 44 in the direction in which the lock nut 40 is retracted. When the feed screw 44 moves to the position shown in FIG. 4A with respect to the lock nut 40 at time t8 and the gap δ between the screw portions 53 and 54 between the lock nut 40 and the feed screw 44 becomes zero, the load is reduced. The rotation of the electric motor 49 stops due to the increase. The parking brake control device 6 monitors the stall current of the electric motor 49 by the current detection means 56, and stops the rotation of the electric motor 49 when the stall current continues for a predetermined time at time t9 when a predetermined time has elapsed from time t8. Determination is made to stop energization of the electric motor 49, and a hydraulic pressure release control signal is output to the ECU 4A of the hydraulic pressure supply device 4. In response to this hydraulic pressure release control signal, the ECU 4A opens the master cylinder cutoff control valve 18 to reduce the hydraulic pressure in the cylinder 36.

  Then, the hydraulic pressure decreases, and the hydraulic pressure in the cylinder 36 is completely released at time t10. At this time, when the hydraulic pressure is released, the piston 38 and the lock nut 40 are moved backward by the elastic force of the piston seals 39 and 41. Accordingly, the gap δ between the screw portions 53 and 54 of the lock nut 40 and the feed screw 44 is not zero, and in this state, the lock nut 40 moves by the gap δ by the hydraulic pressure during service braking. As a result, the thrust to the brake pad 8 changes during braking, giving the driver a sense of incongruity. Therefore, after the hydraulic pressure in the cylinder 36 is completely released, the electric motor 49 is operated again so that the gap δ between the screw portions 53 and 54 between the lock nut 40 and the feed screw 44 is zero. Therefore, it is necessary to rotate the feed screw 44 in the direction in which the lock nut 40 is retracted. However, since the gap δ at time t10 depends on the elastic force of the piston seals 39 and 41, it varies depending on the environmental temperature and the predetermined pressure at the time of release and is not constant. Therefore, if the electric motor 49 is merely rotated for a certain period of time as in the prior art, the gap δ does not become zero and the driver feels uncomfortable as described above, or the lock nut 40 is set after the gap δ is zero. When the parking brake is operated next time, it takes time to complete the parking brake.

  In the present embodiment, the rotation amount (return amount) of the electric motor 49 is appropriately adjusted by the control of the parking brake control device 6 described below. At time t10, a hydraulic pressure supply control signal is output from the parking brake control device 6 to the ECU 4A. In response to this hydraulic pressure supply control signal, the ECU 4A energizes the normally open master cylinder shutoff control valve 18 of the hydraulic pressure supply device 4 to close them. At the same time, the parking brake control device 6 energizes the electric motor 49 to rotate the electric motor 49 in the parking brake release direction, that is, the direction in which the feed screw 44 moves backward. At this time, by closing the master cylinder shut-off control valve 18 and the pressure increase control valve 20, the inside of the cylinder 36 of the disc brake 3 is sealed, and the lock nut 40 is restrained by the brake fluid in the cylinder 36. In this state, the electric motor 49 rotates the feed screw 44, and at time t <b> 11, the feed screw 44 moves to the position shown in FIG. 4A, and between the screw portions 53 and 54 of the lock nut 40 and the feed screw 44. When the gap δ becomes 0, the lock nut 40 is restrained, so that the rotation of the electric motor 49 stops due to an increase in load without moving backward. When the parking brake control device 6 detects that the stall current (predetermined stall current value) has been reached by the current detection means 56 at time t12, the parking brake control device 6 stops energizing the electric motor 49. At time t12, the parking brake control device 6 outputs a hydraulic pressure release control signal to the ECU 4A of the hydraulic pressure supply device 4. In response to this hydraulic pressure release control signal, the ECU 4A stops energization of the master cylinder cutoff control valve 18 and opens it.

  As described above, when the parking brake is released, the feed screw 44 is moved in a state where the lock nut 40 is restrained by the brake fluid, so that the feed screw 44 is a screw portion between the lock nut 40 and the feed screw 44 shown in FIG. When the gap δ between 53 and 54 reaches a position where it becomes 0, the movement of the feed screw 44 is blocked by the lock nut 40 restrained by the hydraulic pressure, and the rotation of the electric motor 49 is stopped. By detecting this as a stall current and stopping energization of the electric motor 49, the gap δ shown in FIG. 2 (A) is zero without excessive or insufficient feed screw 44 and without retracting the lock nut 40. The return amount of the electric motor 49 can be adjusted appropriately. Accordingly, the gap δ does not become zero, and the driver feels uncomfortable, or the lock nut 40 is moved backward too much after the gap δ is set to zero, and it takes time to complete the parking brake at the next parking brake operation. Can be prevented.

  In the above embodiment, the inside of the cylinder 36 is sealed by closing the master cylinder shutoff control valve 18 and the pressure increase control valve 20 of the hydraulic pressure supply device 4. Another valve means may be provided in the middle of the pipe line to close the port 36A of the cylinder 36 to seal the inside of the cylinder 36.

  Next, a modified example of parking brake control by the parking brake control device 6 will be described with reference to a time chart shown in FIG. For the above-described embodiment, the same reference numerals are used for the same parts, and only different parts will be described in detail.

  With reference to FIG. 6, in the present modification, the same control as in the above embodiment is executed from time t1 to time t9. At time t9, when it is determined that the rotation of the electric motor 49 is stopped, the energization of the electric motor 49 is stopped, and a hydraulic pressure release control signal is output to the ECU 4A of the hydraulic pressure supply device 4, and the master cylinder cutoff control valve 18 is opened to reduce the hydraulic pressure in the cylinder 36. When the hydraulic pressure in the cylinder 36 decreases to a predetermined hydraulic pressure at time t10, a hydraulic pressure supply control signal is output from the parking brake control device 6 to the ECU 4A. In response to this hydraulic pressure supply control signal, the ECU 4A energizes the normally open master cylinder shutoff control valve 18 of the hydraulic pressure supply device 4 to close them. At the same time, the parking brake control device 6 energizes the electric motor 49 to rotate the electric motor 49 in the parking brake release direction, that is, the direction in which the feed screw 44 moves backward. At this time, by closing the master cylinder shut-off control valve 18 and the pressure increase control valve 20, the inside of the cylinder 36 of the disc brake 3 is sealed, and the lock nut 40 is restrained by the brake fluid in the cylinder 36. In this state, the electric motor 49 rotates the feed screw 44, and at time t <b> 11, the feed screw 44 moves to the position shown in FIG. 4A, and between the screw portions 53 and 54 of the lock nut 40 and the feed screw 44. When the gap δ becomes 0, the lock nut 40 is restrained, so that the rotation of the electric motor 49 stops due to an increase in load without moving backward.

  At time t12, the parking brake control device 6 stops energization of the electric motor 49 when the current detection means 56 detects that the stall current (predetermined stall current value) has been reached. Also, a hydraulic pressure release control signal is output to the ECU 4A of the hydraulic pressure supply device 4. In response to this hydraulic pressure release control signal, the ECU 4A stops energization of the master cylinder cutoff control valve 18 and the pressure increase control valve 20 and opens them.

  In this way, when the parking brake is released, the feed screw 44 is moved while the lock nut 40 is fixed. Therefore, when the feed screw 44 reaches the position shown in FIG. Is restrained and the rotation of the electric motor 49 is stopped, and the feed screw 44 can be reliably returned to the position shown in FIG. 4A without excess or deficiency, and the return amount of the electric motor 49 is adjusted appropriately. can do. Accordingly, the gap δ does not become zero, and the driver feels uncomfortable, or the lock nut 40 is moved backward too much after the gap δ is set to zero, and it takes time to complete the parking brake at the next parking brake operation. Can be prevented.

  1 disc brake device, 3 disc brake, 4 hydraulic pressure supply device, 6 parking brake control device, 7 disc rotor, 8 brake pad, 9 parking brake mechanism, 36 cylinder, 38 piston (first piston), 40 lock nut (first 2 piston), 49 Electric motor

Claims (1)

A pair of brake pads disposed on both sides of the disk rotor, a cylinder, and a piston inserted into the cylinder, and propelling the piston by supplying hydraulic pressure into the cylinder, When the brake pad is pressed against the disk rotor to generate a braking force, and when the brake pad is pressed against the disk rotor by supplying hydraulic pressure into the cylinder, the electric motor operates as a drive source, and the cylinder A parking brake mechanism that mechanically holds the piston in the braking position even after the hydraulic pressure from the cylinder is released, a hydraulic pressure supply device that supplies a predetermined hydraulic pressure to the cylinder, and an operation of the hydraulic pressure supply device and the electric motor A parking brake control device for controlling
The piston comprises a first piston having a first pressure receiving area and a second piston having a second pressure receiving area with respect to the hydraulic pressure in the cylinder,
When the parking brake is released, the parking brake control device releases the predetermined hydraulic pressure in the cylinder, and then energizes the electric motor in a state where the second piston is restrained by the liquid, thereby causing the parking motor to A disc brake device characterized in that when the electric motor is rotated in a release direction and the electric motor reaches a predetermined stall current value, energization to the electric motor is stopped.

Images