JPH08312701A - Electrically operated braking device - Google Patents

Abstract

PURPOSE: To provide an electrically operated braking device provided with an automatic adjuster mechanism, capable of easily keeping the pad clearance constant without controlling the rotational number of a motor by preventing the inertia of the motor from being transmitted to a screw shaft side in releasing of braking force. CONSTITUTION: When a brake pedal 1 is depressed, a motor 20 is driven in response to an input signal from a depressing force sensor 2, and an output shaft 16 is rotated. A spring 15 rotates a ball screw shaft 12 and moves a nut 11 while being fastened by the rotation of the output shaft, and a piston 8 is moved and presses a disc pad 5 against a disc 6. When a friction member is worn, the piston 8 is returned by the specified amount without being rotated by restoring force of an elastically deformed piston seal 9, so as to keep the pad clearance constant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrically operated brake device, and more particularly to a compact and lightweight electrically operated brake device with an automatic adjuster mechanism in which a pad clearance is always constant.

[0002]

2. Description of the Related Art In recent years, in addition to a hydraulic brake actuation circuit, an electrically actuated brake device (so-called by-wire system) for actuating a brake by an electric signal has been developed. The electrically operated braking device converts the pedaling force of the brake pedal into an electric signal and operates the braking device by a signal from an electronic control device, so the entire system is lighter and smaller than conventional hydraulic circuit type braking devices. There is an advantage that the system can be easily constructed in executing various controls of the brake device (anti-skid control, traction control, automatic brake control, etc.).

As an example of such an electrically operated brake device, Japanese Patent Laid-Open Nos. 2-57731 and 5-321961 are known.
Japanese Unexamined Patent Application Publication No. 2003-242242 discloses a brake actuating device that utilizes the rotational force of an ultrasonic motor. Of these, JP-A-5-3
The brake device described in Japanese Patent Laid-Open No. 21961 discloses a rotating disk rotor, a friction member arranged so as to face the friction surface of the disk rotor, and a torque receiving member that receives torque transmitted from the disk rotor to the friction member. A counter member supported by the torque receiving member and facing the back surface of the friction member, a motor held by the counter member, and provided between the motor and the friction member, and rotated by the motor. A screw mechanism having a first screw member and a second screw member that is screwed with the first screw member and presses the friction member against the friction surface of the disk rotor according to the rotation of the first screw member. The motor can be operated with a rotational torque that corresponds to the pedaling force of the brake pedal, and the piston can be moved forward to operate the brake. Thus as in the prior art booster device, the master cylinder, and unnecessary components such as piping.

Further, in this device, when the friction member is worn, the screwing position of the first screw member and the second screw member is changed by an amount corresponding to the amount of wear, and the friction member causes friction of the disk rotor. The surface is always pressed properly. That is, since the position adjustment of the friction member with respect to the disk rotor, that is, the brake clearance (pad clearance) adjustment is performed every time braking is performed, it is not necessary to provide a special adjustment device, and there is an advantage that the device cost can be reduced. .

[0005]

However, in the case of the adjuster mechanism of the above device, the piston may not always return smoothly due to the inertia of the motor, the holding torque, etc., and the pad clearance should be adjusted so that it is always constant. There is a problem that is difficult. Further, in the device described in Japanese Patent Laid-Open No. 5-321961, the output shaft of the motor is directly screwed into the piston, so the inertia of the motor acts on the piston, and the pad clearance can be adjusted accurately. There is a problem that you can not. Therefore, the present invention adopts a configuration in which the output shaft of the motor and the screw on the piston side are free when the braking force is released, and the inertia of the motor is prevented from being transmitted to the screw shaft side, so that the rotation speed of the motor It is an object of the present invention to provide a novel electric actuation brake device with an auto-adjuster mechanism that can easily maintain a constant pad clearance without controlling the above, and solve the above problems.

[0006]

Therefore, according to the present invention, a cylinder 7 formed in a caliper 4 of a brake device and a piston 8 held by an elastically deformable piston seal arranged in the cylinder 7 are provided. , The same piston 8
Shaft 12 coupled to the shaft 12 via a reversible screw, a spring 15 attached to the shaft 12 with a predetermined tightening margin, and a motor 20 via the spring 15.
Shaft 16 capable of transmitting the rotational force of the shaft to the shaft 12
And an electric control device 3 for controlling the motor and an electronic control device 3 for controlling the motor, which is a means for solving the problems.

[0007]

When the brake pedal 1 is stepped on, the motor 20 is driven according to the input signal from the pedaling force sensor 2 and the output shaft 16 rotates. The rotation of the output shaft 16 tightly holds the ball screw shaft 12 while tightening the spring 15, further rotates the ball screw shaft 12 to move the nut 11, and accordingly the piston 8 also moves to move the disc pad 5 to the disc 6 And apply the brakes. When the friction member is worn, the piston 8 returns by a predetermined amount without rotating due to the restoring force of the elastically deformed piston seal 9, and keeps the pad clearance constant.
That is, the piston seal 9 is capable of changing the holding positions of the piston and the piston seal when the brake is operated, but when the brake is released, the piston is returned only to the amount returned by the elastic force of the piston seal. , The pad clearance can always be kept constant.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of an electrically operated brake device according to an embodiment of the present invention incorporated in a caliper. 1 in the figure
Is a brake pedal, 2 is a pedaling force sensor, 3 is an electronic control unit (ECU), 4 is a brake caliper, 5 is two disc pads, and 6 is a disc arranged between the disc pads. I'm using
A description of those detailed configurations will be omitted.

A cylinder 7 is formed in the caliper 4, and a piston seal 9 is attached to the inner peripheral surface of the cylinder 7. The piston seal 9 holds the piston 8, and when the piston seal 9 itself elastically deforms, it has a function of giving a returning force to the piston by its elastic force. The holding positions of the piston seal 9 and the piston 8 can be changed when moving with a force stronger than the holding force of.

The piston 8 is formed in a cylindrical shape with one end closed, and one of the disk pads 5 is attached to the outer surface of the one end. Is provided with a pressing force sensor 10. The pressing force sensor 10 is a sensor that detects the pressing force of the piston, and controls the brake pressure in the manner described below based on the signal from this sensor. The pressing force sensor 10 can be replaced with another sensor (including a pedaling force sensor) capable of detecting the operating state of the brake pedal, and the pressing force sensor can be omitted if necessary. .

A nut 11 is fixed in the center of the piston 8 so as to coincide with the axis of the piston 8.
Ball screw shaft 1 with reversible ball screw coupling 12a
One end of 2 is screwed. A bearing portion 14 is formed on the ball screw shaft 12, the bearing portion 14 is axially supported on the caliper 4 side via a thrust bearing 13, and the other end of the ball screw shaft 12 has a predetermined tightening margin. One end of the spring 15 is attached. The other end of the spring 15 has an output shaft 16 of the motor 20.
Is loosely fitted, and the end of the spring 15 and the output shaft 16 of the motor 20 are configured to come into contact with a protrusion 17 provided on the output shaft side. This spring 1
When the motor 20 rotates in the forward rotation direction (the arrow A direction in the drawing), the spring 15 tightens the output of the motor 20 through the spring 15 and the ball screw shaft 12
When the motor 20 rotates in the reverse direction (the direction of the arrow B in the figure), the spring 15
Is loosened, the output shaft 16 and the ball screw shaft 12 become free, and the rotational force of the motor 20 causes the ball screw shaft 1 to rotate.
2 is not transmitted.

The motor 20 is attached to the caliper 4 via a motor support member 21.
Is controlled and driven by a command from an electronic control unit (ECU) 3. Therefore, the electronic control unit (EC
U) When the motor 20 is controlled and driven by the command from 3, the rotation of the motor 20 is transmitted from the output shaft 16 to the spring 15, and the spring 15 transmits the rotational force to the ball screw shaft 12 while tightening the ball screw shaft 12. . When the ball screw shaft 12 rotates, the nut 11
Can move to the left in the figure to push the piston 8 to the left in the figure, and press the disc pad 5 against the disc 6 to apply the brake.

At this time, the piston seal 9 is elastically deformed by the movement of the piston, and this deforming force gives a returning force to the piston. Further, when the pad clearance is wide, the piston 8 has a piston seal 9
It is moved by a force stronger than the holding force of the piston and the holding position of the piston and the piston seal is set. The signals from the pressing force sensor 10 and the brake pedal pedal force sensor 2 are transmitted to the electronic control unit 3, and the electronic control unit 3 controls the motor 20 based on these signals.

The operation of the electrically operated brake device having the above structure will be described. Since there is no command from the electronic control unit 3 before the brake is actuated, this brake unit is shown in FIG.
State (brake release state). When the driver steps on the brake pedal 1, the pedaling force at this time is detected by the pedaling force sensor 2.
Is detected by and input to the electronic control unit 3. The electronic control unit 3 drives the motor 20 according to the input signal and rotates the output shaft 16. The rotation of the output shaft 16 tightly holds the ball screw shaft 12 while tightening the spring 15, and further rotates the ball screw shaft 12 to move the nut 11 to the left in the drawing, and the piston 8 also moves accordingly to move the disc 8. Press the pad 5 against the disc 6 and apply the brake.

At this time, the piston seal 9 is elastically deformed by the movement of the piston, and when the pad clearance is wide, the piston 8 is moved with a force stronger than the holding force of the piston seal 9. 8 and the piston seal 9 are held at different positions, and the piston seal 9 is elastically deformed at this position. And
When the pressing force applied to the disk 6 by the disk pad 5 reaches a predetermined value, the pressing force sensor 10 detects this value and outputs it to the electronic control unit 3. The electronic control unit 3 stops the operation of the motor 20 based on the signal from the pressing force sensor 10.

When the brake is released, the motor 20 is activated by the pedaling force signal to open the brake while rotating the output shaft in the reverse direction (direction B in the figure). When the brake is completely released, the spring 15 is loosened, the output shaft 16 and the spring 15 are in a free state, and the rotational force due to the inertia of the motor 20 is not transmitted to the ball screw shaft. Further, the piston 8 coupled to the ball screw shaft by the reversible screw coupling returns by a predetermined amount without rotating due to the restoring force of the elastically deformed piston seal 9, and keeps the pad clearance constant. Furthermore, even if the friction member wears, it is possible to change the holding position of the piston and piston seal when the brake is activated, but when the brake is released, the piston returns to the original amount due to the elastic force of the piston seal. Clearance can always be kept constant.

As described above, according to the present invention, the spring 15 is interposed between the output shaft 16 of the motor 20 and the ball screw shaft 12, and the pad clearance is determined by a simple auto adjuster mechanism that determines the piston return amount by the piston seal. Can always be kept constant. Further, in the present invention, a vehicle speed sensor, an inter-vehicle distance sensor, a torque sensor of a motor, or the like is adopted, and while each sensor is combined as necessary, pressurization and holding of a braking force by a control signal from an electronic control unit, Since the pressure can be reduced, not only normal brake control but also anti-skid control, traction control, automatic brake control, etc. can be executed.

[0018]

As described above in detail, according to the present invention, the pad clearance is always constant without being affected by the inertia of the motor by the simple auto-adjuster mechanism in which the spring is interposed between the output shaft of the motor and the ball screw shaft. This can be maintained, and the device can be simplified and the device can be reduced in size and weight. In addition, antiskid control, traction control, automatic brake control, etc. can be easily realized by the control by the electronic control device while reducing the cost of the device. It is possible to achieve excellent operational effects such as.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of an electrically operated brake device as an embodiment according to the present invention.

[Explanation of symbols]

 1 brake pedal 2 pedal force sensor 3 electronic control device 4 disc pad 5 disc 7 cylinder 8 piston 9 piston seal 10 pressing force sensor 11 nut 12 ball screw shaft 13 thrust bearing 15 spring 16 output shaft 20 motor

Claims (4)

[Claims] 1. A cylinder 7 formed in a caliper 4 of a brake device, a piston 8 held by an elastically deformable piston seal arranged in the cylinder 7, and a piston 8 and a reversible screw. Shaft 12 coupled together, a spring 15 attached to the shaft 12 with a predetermined tightening margin, and an output shaft 16 and an output shaft 16 capable of transmitting the rotational force of the motor 20 to the shaft 12 via the spring 15. An electrically operated brake device comprising a motor 24 for operating 16 and an electronic control device 3 for controlling the motor. 2. The spring and the output shaft are connected so as to tighten the spring when the motor rotates forward and loosen the spring when the motor rotates reversely so that the spring and the output shaft are free. The electrically operated braking device according to item 1. 3. The electric appliance according to claim 1, wherein the piston seal holds the piston with a holding force capable of changing a holding position of the piston when the piston is pushed with a force of a predetermined value or more. Actuated braking device. 4. The electronic control unit is configured to control a motor by a signal from a sensor such as a pedaling force sensor, a pressing force sensor, an inter-vehicle distance sensor, a vehicle speed sensor, or the like. An electrically operated braking device according to any one of the above.