JPH11287270A - Dynamoelectric brake gear - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a kickback to a brake pedal in antilock control, in a dynamoelectric brake gear which generates a braking force by jointly using the output of a hydraulic and a electric motor. SOLUTION: An accumulator 6 is installed in a conduit 4 feeding a dynamoelectric brake with hydraulic pressure from a master cylinder 5, and a restriction 7 is installed in space between this accumulator 6 and the master cylinder 5. In addition to the braking force by the hydraulic pressure from the master cylinder 5, an electric motor of the dynamoelectric brake 2 is operated by a controller 8 accorring to the threadling force of a brake pedal 33 detected by a threadling force sensor 34, whereby the braking force is generated. In antilock control, a brake fluid to be suddenly returned to the side of the master cylinder 5 by way of the conduit 4 by operation of the electric motor, is accumulated in the accumulator 6, so that a kickback to the brake pedal 33 is thus reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric brake device for generating a braking force by using both the output of an electric actuator and the hydraulic pressure from a master cylinder.

[0002]

2. Description of the Related Art A so-called "dry brake" in which a braking force is generated by the output of an electric motor without using a brake fluid as a braking device for a vehicle such as an automobile.
Devices are known.

[0003] Generally, this type of dry brake device is
For example, as disclosed in International Patent Publication No. 96/03301, the rotational force of an electric motor is converted into forward and backward movements of a piston by a roller screw mechanism, and a friction pad is pressed against a disk rotor by the piston to thereby provide a braking force. Is occurring. The brake pedal depression force (or displacement amount) by the driver is detected by a sensor, and the controller controls the rotation of the electric motor according to the detection to obtain a desired braking force.

In a dry brake device, various sensors are used to detect vehicle conditions such as the rotational speed of each wheel, vehicle speed, vehicle acceleration, steering angle, and vehicle lateral acceleration.
By controlling the rotation of the electric motor based on these detections by the controller, boost control, antilock control, traction control, vehicle stabilization control, and the like can be relatively easily incorporated.

However, in a dry brake device in which a braking force is generated by the rotation force of an electric motor, if the motor cannot be energized due to a failure of the electric system of the vehicle, the brake may not be able to be operated. is there.

Therefore, for example, in Japanese Unexamined Patent Publication No. 60-206766, a hydraulic chamber is formed around the piston using a stepped piston, and the hydraulic chamber is formed in the hydraulic chamber by operating a brake pedal. Connect a working master cylinder,
The brake can be operated by the hydraulic pressure from the master cylinder in addition to the output of the electric motor. Thus, even when the electric system fails, the brake can be directly operated by the hydraulic pressure from the master cylinder, and the braking force can be secured.

[0007]

However, the following problems have been encountered in the conventional electric brake device in which the braking force is generated by using both the output of the electric motor and the hydraulic pressure from the master cylinder. .

When anti-lock control is executed by the controller, the electric motor rotates in the forward and reverse directions to forcibly move the piston forward and backward, thereby appropriately increasing or decreasing the braking force, thereby preventing the wheels from being locked. . At this time, the volume of the hydraulic pressure chamber is increased or decreased by the reciprocation of the piston, and in conjunction with this, the brake fluid is supplied to and discharged from the master cylinder, and the stroke of the brake pedal changes periodically. This periodic change in the stroke of the brake pedal is transmitted to the driver as kickback, and the driver can experience the execution of the antilock control.

However, if the kickback is excessively large, the driver will feel uncomfortable. In particular, the control to reduce the braking force to avoid locking the wheels
Since it is necessary to perform the operation promptly, the brake pedal is suddenly returned at the time of the braking force reduction control, which makes the driver easily feel uncomfortable, which is a problem.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and uses both the output of an electric motor and the hydraulic pressure from a master cylinder to generate a braking force and reduce kickback during antilock control. It is an object of the present invention to provide an electric brake device adapted to perform the operation.

[0011]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides an electric brake which generates a braking force by using both the hydraulic pressure of a brake fluid from a master cylinder and the output of an electric actuator. The apparatus is characterized in that a pressure accumulating means is provided in a conduit for supplying brake fluid from the master cylinder to the electric brake main body, and a throttle is provided between the master cylinder and the pressure accumulating means in the conduit.

With this configuration, when the brake fluid is suddenly returned from the electric brake main body to the master cylinder through the pipe by the operation of the electric actuator, the throttle becomes a large resistance, and the throttle becomes large. Since the hydraulic pressure increases and the hydraulic pressure is accumulated in the accumulator, the hydraulic pressure transmitted to the master cylinder is reduced.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows a schematic configuration in a case where the electric brake device of the present invention is applied to a front wheel side of a brake device 1 of a four-wheeled vehicle. As shown in FIG. 1, the braking device 1 has electric disc brakes 2 and 3 mounted on each front wheel (not shown) and each rear wheel (not shown). Front wheel side electric disc brake 2 (Electric disc brake body)
Are connected to a master cylinder 5 via a pipe 4. A pressure accumulator 6 (pressure accumulating means) is connected to the pipeline 4, and a throttle 7 is provided between the connection portion and the master cylinder 5. The front and rear wheel-side electric disc brakes 2 and 3 are connected to a controller 8.

As shown in FIG. 2, the electric disc brake 2 on the front wheel side according to the present invention is a caliper floating type disc brake, and a caliper body 9 has a disc rotor which rotates together with wheels (not shown). A piston 11 is provided so as to face a sliding surface on one side (usually inside the vehicle body) 10, and a claw portion 12 is formed so as to face a sliding surface on the other side. The piston 11 side and the claw portion 12 side
The disk rotors 10 are connected to each other by a bridge 13 that straddles the outer periphery. Brake pads 14 and 15 are interposed between the sliding surfaces on both sides of the disk rotor 10 and the piston 11 and the claw portion 12, respectively.

The caliper body 9 and the friction members 14 and 15 are formed by a carrier 16 mounted on the vehicle body side by a disk rotor 10.
Are supported so as to be movable along the axial direction. And
By moving the piston 11 forward and pressing one of the brake pads 14 against a sliding surface on one side of the disk rotor 10, the caliper main body 9 moves due to the reaction force, and the claw portion 12 is moved.
As a result, the other brake pad 15 is pressed against the other sliding surface of the disk rotor 10 to generate a braking force.

The piston 11 is inserted through a nut member 18 rotatably supported by a caliper body 9 by a cross roller bearing 17. Opposite screw grooves 19 and 20 are formed on the outer peripheral surface of the piston 11 and the inner peripheral surface of the nut member 18, respectively. A plurality of steel balls 21 are loaded between the screw grooves 19 and 20 so as to circulate. Thus, these form a ball screw mechanism.

This ball screw mechanism can mutually convert the rotational movement of the nut member 18 and the linear movement of the piston 11, that is, convert the rotational movement of the nut member 18 into the linear movement of the piston 11. And piston
The linear motion of 11 can be converted into the rotational motion of the nut member 18.

A DC servomotor 23 (electric actuator) is provided on the outer periphery of the nut member 18 in the front housing 22 connected to the caliper body 9. A substantially cylindrical rotor 24 of a DC servomotor 23 is press-fitted and fixed to the outer periphery of the nut member 18, and the nut member 18 and the rotor 24 are inserted through the stator 25. The DC servo motor 23 can rotate its rotor 24 by a predetermined angle in response to a control signal. Further, a rotary encoder 26 for detecting the rotational position of the nut member 18 is attached to the caliper body 9.

A rear housing 27 is connected to an end of the front housing 22. The piston 11 is guided by the guide member 28 attached to the rear end thereof with the rear housing 27 so as to be able to advance and retreat along the axial direction, and its rotation is restricted. This gives D
By rotating the nut member 18 by the C servo motor 23, the piston 11 can be moved forward and backward.

A cylinder 29 is formed in the rear housing 27 so as to face the rear end of the piston 11. A hydraulic piston 30 is slidably fitted into the cylinder 29, and the hydraulic piston 30 allows the hydraulic chamber 29a to be inserted into the cylinder 29.
Are formed. The hydraulic piston 30 is in contact with a guide member 28 attached to the rear end of the piston 11. Further, the rear housing 27 is provided with a connection hole 31 communicating with the hydraulic chamber 29a. In FIG. 2, reference numeral 32 denotes a dust seal.

The stator 25 and the rotary encoder 26 of the DC servomotor 23 are connected to the controller 8, and the connection hole 31 is connected to the master cylinder 5 through the connection pipe 4 via the pressure accumulator 6 and the throttle 7.

The master cylinder 5 generates a hydraulic pressure by operating the brake pedal 33, and is provided with a tread force sensor 34 for detecting the tread force (or displacement) of the brake pedal 33. The pedal force sensor 34 is connected to the controller 8.

The controller 8 includes a pedaling force sensor 34 for detecting the pedaling force (or displacement) of the brake pedal 33, a rotational speed sensor 35 for detecting the rotational speed of each wheel, and a vehicle speed.
A detection signal is input from various sensors (not shown) for detecting a vehicle state such as a vehicle acceleration, a steering angle, and a vehicle lateral acceleration. Then, a control signal is output in accordance with the pedaling force (or displacement) of the brake pedal 33 detected by the pedaling force sensor 34, the DC servo motor 23 is rotated by a desired angle, the piston 11 is advanced, and the frictions 14 and 15 are disc-shaped. The rotor 10 is pressed. Further, when releasing the braking, the amount of return of the piston 11 from the predetermined braking position is controlled to be constant, and the encoder is controlled.
By initially setting 26, the pad clearance is always kept constant against wear of the frictions 14 and 15.

Further, the controller 8 detects the locked state of the wheels by the rotation speed sensor 35 during braking,
The brake is released by rotating the C servomotor 23 in the reverse direction, and when the lock state is released, the braking force is restored. In this way, the DC servomotor 23 is periodically rotated in the forward and reverse directions,
Is forcibly moved forward and backward to quickly increase and decrease the braking force appropriately, thereby performing anti-lock control for preventing wheel lock.

In addition, the controller 8 controls traction control and vehicle stabilization control by controlling the rotation of the DC servo motor 23 and adjusting the braking force for each wheel based on detection signals from various sensors. It may be performed.

The accumulator 6 comprises a piston 36 and a spring means 37
Thus, the hydraulic pressure of the brake fluid introduced from the pipeline 4 can be accumulated by the compression of the spring means 37.
Further, the spring means 37 is set to an initial load that is not compressed by the hydraulic pressure generated in the master cylinder 5 by the operation of the brake pedal 33 by a normal driver.

The flow passage area of the throttle 7 has almost no resistance at the flow velocity of the brake fluid discharged from the master cylinder 5 in the pipeline 4 by the operation of the brake pedal 33 by a normal driver. It is set so as to generate a sufficiently large resistance to the rapid flow of the brake fluid in the pipeline 4 due to the reciprocation of the piston 11 during the lock control.

The rear wheel-side electric brake 3 has substantially the same structure as the front wheel-side electric brake 2 except that the hydraulic mechanism is omitted, and generates a braking force only by a control signal from the controller 8. It is made to let.

Next, the operation of the present embodiment configured as described above will be described.

When the driver steps on the brake pedal 33,
The brake fluid of the hydraulic pressure corresponding to the treading force is applied to the master cylinder.
From the pipe 28, the fluid is supplied to the hydraulic chamber 29 a through the connection hole 31 through the connection hole 31, and the piston 11 is advanced to press the frictions 14 and 15 against the sliding surface of the disk rotor 10. At this time, the pressure accumulator 6 and the throttle 7 hardly affect the hydraulic pressure and flow of the brake fluid generated in the pipeline 4 by the operation of the brake pedal 33 by the driver, and the brake fluid is directly supplied to the hydraulic pressure chamber 29a.
Supplied to Similarly, when the brake is released by returning the brake pedal 33, the accumulator 6 and the throttle 7 have almost no effect, and the brake fluid is directly returned to the master cylinder 5.

At the same time, the depression force of the brake pedal 33 is detected by the depression force sensor 34, a control signal corresponding to the depression force of the pedal is output by the controller 8, and the rotor 24 of the DC servomotor 23 is rotated by a desired angle, and the ball is rotated. The piston 11 is advanced through the screw mechanism. In this way, in addition to the hydraulic pressure from the master cylinder 5, the thrust due to the rotational force of the DC servomotor 23 acts on the piston 11 to increase the pressing force of the frictions 14 and 15 to perform the boosting control. .

The ball screw mechanism can also convert the linear motion of the piston 11 into the rotary motion of the nut member 18, so that the DC servo motor 23
Even when a control signal or electric power is not supplied to the hydraulic pressure chamber 29a from the master cylinder 5, the piston 11 moves forward while rotating the nut member 18 to remove the frictions 14 and 15 from the disk rotor 10. Can be pressed. As a result, the braking force can be ensured even when the electric system fails. Conversely, if the hydraulic mechanism fails, the braking force can be ensured by the DC servomotor 23.

Next, a case where the anti-lock control is executed by the controller 8 will be described.

During the antilock control, when the DC servo motor 23 rotates in the forward and reverse directions by the control signal of the controller 8 and the piston 11 moves forward and backward, the volume of the hydraulic chamber 29a is increased or decreased. When the brake is released, the piston 11 retreats to reduce the volume of the hydraulic chamber 29a, and the brake fluid flows from the hydraulic chamber 29a through the pipe 4 to the master cylinder 5 side. At this time, a rapid flow occurs in the brake fluid in the pipeline 4 and the throttle 7
Becomes large resistance, the hydraulic pressure on the hydraulic pressure chamber 29a side of the throttle 7 increases, compressing the spring means 37 of the accumulator 6, and this hydraulic pressure is stored in the accumulator 6. Note that a small amount of brake fluid passes through the throttle 7 and is returned to the master cylinder 5. At the time of braking return, the piston 11 advances to increase the volume of the hydraulic chamber 29a, and the brake fluid stored in the accumulator 6 at the time of braking release is supplied to the hydraulic chamber 29a.

As described above, the periodic sudden flow of the oil liquid generated in the pipe line 4 due to the reciprocation of the piston 11 during the antilock control is absorbed and attenuated by the pressure accumulator 6 and the throttle 7, so that the master oil is absorbed by the master. Since transmission to the cylinder 5 is suppressed, kickback to the brake pedal 33 can be reduced, and pedal operation feeling during antilock control can be improved.

Thus, particularly when the antilock control is started on a low μ (friction coefficient) road such as a road on snow and a road on ice,
When the anti-lock control changes from a high μ road to a low μ road such as a pavement road, etc., even if the braking force is suddenly released and a large amount of brake fluid is returned to the pipeline 4 from the hydraulic chamber 29a. Further, the sudden transmission of the hydraulic pressure to the master cylinder 5 can be suppressed, and the brake pedal 33 can be prevented from returning suddenly and largely, so that the driver does not feel uncomfortable.

The electric disc brake 3 on the rear wheel side does not perform braking by hydraulic pressure, and its braking force is controlled only by a control signal from the controller 8.

In the present embodiment, an example using an electric disc brake equipped with a DC servomotor is described. However, the present invention is not limited to this, and the output of an electric actuator such as a piezoelectric element and the output of a liquid Other types of brakes can be used as long as the brakes generate a braking force in combination with pressure.

[0040]

As described in detail above, the present invention relates to an electric brake device which generates a braking force by using both the hydraulic pressure of the brake fluid from the master cylinder and the output of the electric actuator. By providing the pressure accumulating means in the pipeline for supplying the brake fluid to the electric brake main body and providing a throttle between the master cylinder and the pressure accumulating means in the pipeline, the operation of the electric actuator allows
When the brake fluid is rapidly returned from the electric brake main body to the master cylinder side through the pipeline, the throttle becomes a large resistance, and the fluid pressure in the pipeline increases, and the fluid pressure is accumulated in the pressure accumulating means. The hydraulic pressure transmitted to the master cylinder is reduced. As a result, kickback during antilock control can be reduced, and the operational feeling of the brake pedal can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a braking device for a four-wheel vehicle in which an electric brake device according to an embodiment of the present invention is applied to a front wheel side.

FIG. 2 is a longitudinal sectional view of an electric disc brake used in the electric brake device according to one embodiment of the present invention.

[Explanation of symbols]

 2 Electric disc brake (Electric brake main body) 4 Pipe line 5 Master cylinder 6 Accumulator (accumulator) 7 Throttle 23 DC servo motor (Electric actuator)

Claims (1)

[Claims] 1. An electric brake device which generates a braking force by using both a hydraulic pressure of a brake fluid from a master cylinder and an output of an electric actuator, wherein a pipe for supplying the brake fluid from the master cylinder to an electric brake body. An electric brake device, wherein a pressure accumulating means is provided in a path, and a throttle is provided between the master cylinder and the pressure accumulating means in the pipeline.