JP2003172384A - Electric brake device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce yield strength required for respective gears of deceleration gear mechanism for decelerating rotation of an electric motor and transmitting it to a rotation/linear motion conversion mechanism. <P>SOLUTION: When an output shaft 23 of the electric motor 20 is normally or reversely rotated, a worm 24 rotates a worm wheel 26 and rotates a screw shaft 42 through a clutch 22. The screw shaft 42 makes a piston 15 advance or retreat together with a nut member 43, and makes a brake pad 17 abut or separate to or from a disk rotor 18. The clutch 22 transmits rotation accompanied by the normal or reverse rotation of the electric motor 20 from the worm wheel 26 to the screw shaft 42. On the other hand, counterpart torque based on return reaction force applied to the piston 15 from the brake pad 17 is prevented from being transmitted to a worm gear 21, and a state that the counterpart torque is applied to the worm 24 and the worm wheel 26 is prevented from continue. <P>COPYRIGHT: (C)2003,JPO

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, and more specifically, after reducing the rotation output from an electric motor by a reduction gear mechanism, it is converted into a linear motion by a rotation / linear motion conversion mechanism for braking. The present invention relates to an electric brake device.

[0002]

2. Description of the Related Art Conventionally, as an electric brake device, Japanese Patent Laid-Open No.
There is one disclosed in Japanese Patent Publication No. 001-130402.
This electric brake device is a hydraulic brake-operated regular brake (disc brake) in which a parking brake mechanism operated by an electric motor is incorporated. The electric motor is operated only when the parking brake is applied and released, and the energization is stopped during the parking brake.

In this electric brake device, as shown in FIG. 5, the rotation of the output shaft 61 of the electric motor 60 is controlled by the rotation of the output shaft 6.
One-way clutch 6 from pinion gear 62 fixed to 1
3 to the first gear 64, which is the input shaft of the third gear, and the second gear 65, which is the output shaft thereof, to the large diameter gear 6 of the stepped third gear 66.
6a is transmitted. The rotation transmitted to the stepped third gear 66 is transmitted from the small diameter gear 66b to the fourth gear 67, and rotates the screw shaft 68 fixed to the fourth gear 67. That is, the pinion gear 62 and the first gear 6
A reduction gear train including the fourth gear 65, the stepped gear 66, and the fourth gear 67 reduces the rotation output from the electric motor 60 to rotate the screw shaft 68.

The screw shaft 68 includes a nut member 6
9 is moved to the disc rotor R side, and the piston 71 is advanced to the rotor R side via the disc spring 70. Then, the piston 71 presses the brake pad 72a against the rotor R, and also presses the brake pad 72b against the rotor R via the brake caliper 73. That is, the rotation / linear motion conversion mechanism including the screw shaft 68 and the nut member 69 converts the rotary motion output by the electric motor 60 into a linear motion.

Brake pads 72a and 72b are rotors R
When is braked with a predetermined pressing force, the power supply to the electric motor 60 is stopped. In this state, the brake pads 72a, 7
The return reaction force applied from 2b causes the piston 71 to move backward from the rotor R side, and the screw nut 6
The second gear 65 tries to rotate in reverse due to the reverse torque applied to the eighth, fourth gear 67 and the stepped third gear 66. Then,
The one-way clutch 63 regulates the reverse rotation of the second gear 65 and prohibits the reverse rotation of the first gear 64 and the electric motor 60. Therefore, even when the power supply to the electric motor 60 is stopped while the parking brake is applied, the piston 71 is kept in the advanced state and the brake pads 72a and 72b maintain the state in which the rotor R is braked.

[0006]

However, in the above electric brake device, the piston 71 and the one-way clutch 63 are used.
Between the fourth gear 67, which is a component of the reduction gear train,
A stepped third gear 66 and a second gear 65 are arranged. Therefore, when the parking brake is applied, a large reverse torque due to the return reaction force is applied to the fourth gear 67, the stepped third gear 66, and the second gear 65.

For this reason, the fourth gear 67, the stepped third gear 66, and the second gear 65 are required to have a large proof stress, so that they must all be made of metal. As a result, the weight of the reduction gear train is increased, and thus the weight of the entire electric brake device is increased.

The present invention has been made to solve the above problems, and a first object thereof is to reduce the rotation of an electric motor and transmit it to a rotation / linear motion converting mechanism. An object of the present invention is to provide an electric brake device that can further reduce the proof stress required for gears.

A second object of the present invention is to provide an electric brake device which can reduce the weight of the reduction gear mechanism in addition to the above first object.

[0010]

In order to achieve the first object, the invention according to claim 1 is an electric motor capable of rotating an output shaft in forward and reverse directions, and a rotation output from the output shaft by the electric motor. And a reduction gear mechanism for decelerating the rotation, and the rotation output by the reduction gear mechanism is converted into a linear motion, and the brake friction material is brought into contact with and separated from the braking rotor on the vehicle side by the forward and reverse rotations of the output shaft of the electric motor. A direct-acting conversion mechanism and a connecting means for restricting reverse transmission of reverse torque to the electric motor based on a return reaction force reversely input from the brake friction material to the direct-acting converting mechanism are provided. The electric brake device is provided between a gear mechanism and the direct-acting conversion mechanism, and prevents the reverse torque from being input to the reduction gear mechanism.

According to the first aspect of the invention, the connecting means provided between the reduction gear mechanism and the direct-acting conversion mechanism prevents the reverse torque based on the return reaction force from being input to the reduction gear mechanism. . For this reason, when the brake friction material is pressed against the vehicle-side rotating body and the parking brake is applied, the reverse torque based on the return reaction force applied from the brake friction material to the linear motion conversion mechanism is applied when the electric power supply to the electric motor is stopped. It does not become a state in which it is added to each gear of the reduction gear mechanism. As a result, the proof stress required for each gear of the reduction gear mechanism can be further reduced.

In order to achieve the second object, the second aspect
According to the invention described in claim 1, in the invention described in claim 1, at least one of a plurality of gears constituting the reduction gear mechanism is provided.
One is characterized by being integrally formed of synthetic resin.

According to the invention of claim 2, claim 1
In addition to the effect of the invention described in (1), since at least one of the plurality of gears is integrally formed of synthetic resin, the reduction gear mechanism can be lightened. As a result, the weight of the entire braking device can be reduced.

According to a third aspect of the present invention, in the first or second aspect of the invention, the reduction gear mechanism is a worm fixed to an output shaft of the electric motor, and a worm wheel in which the worm meshes. It is a worm gear consisting of and.

According to the invention of claim 3, claim 1
Alternatively, in addition to the effect of the invention described in claim 2, it is possible to obtain a necessary reduction ratio with a smaller number of gears as compared with a reduction gear mechanism in which a plurality of spur gears are meshed in order. As a result, for example, it is possible to reduce the component cost and the assembly cost.

According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, each component of the clutch is integrally formed of metal.

According to the invention of claim 4, claim 1
In addition to the action of the invention according to any one of claims 3 to 5, each component of the connecting means provided between the direct-acting conversion mechanism and the reduction gear mechanism has a thermal conductivity higher than that of synthetic resin. Since it is made of high metal, the heat generated in the vehicle-side rotary braking body or the like is radiated by the connecting means and is difficult to be transmitted to the electric motor side. Therefore, it is possible to suppress the output reduction of the electric motor due to the temperature increase.

According to a fifth aspect of the invention, in the invention according to any one of the first to fourth aspects, the braking rotor is a disk rotor. According to the invention described in claim 5, in addition to the action of the invention described in any one of claims 1 to 4, in the disc brake device having a larger return reaction force than the drum brake device. The respective effects of the inventions described in claims 1 and 2 become remarkable.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment in which the present invention is embodied in a disc brake device for a vehicle will be described below with reference to FIGS.

The electric brake device of this embodiment is a service brake in which a parking brake is integrated.
The common disk rotor is braked during the service brake operation and the parking brake operation.

As shown in FIG. 1, the electric brake device 10
The brake caliper 11 has a first cylinder body 12
The second cylinder body 13 is fixed, and the piston 15 is housed in the piston chamber 14 formed by the two cylinder bodies 12, 13. A hydraulic chamber 16 is formed in the piston chamber 14 by a piston 15. Hydraulic fluid is supplied to and discharged from the hydraulic chamber 16 by a brake master cylinder (not shown). Then, when a brake pedal (not shown) is operated and hydraulic fluid is pumped from the brake master cylinder to the hydraulic chamber 16, the piston 15 extends from the piston chamber 14 to the outside,
The brake pad (brake friction material) 17 fixed to the piston 15 is pressed against one surface of the disc rotor 18 (braking rotor). Further, the brake pad (brake friction material) 19 held by the brake caliper 11 is pressed against the other surface of the disc rotor 18, so that both brake pads 1
The disk rotor 18 is braked by 7, 19.

The electric brake device 10 includes an electric motor 20, a worm gear 21, and a clutch 22 for operating the piston 15 during parking braking. In the present embodiment, the worm gear 21 is a reduction gear mechanism, and the clutch 22 is a connecting means.

The electric motor 20 is provided so that its output shaft 23 is orthogonal to the central axis of the piston 15, and the output shaft 23 is integrally formed with a worm (gear) 24. The worm 24 is arranged in the gear housing 25,
It meshes with a worm wheel (gear) 26 arranged in the gear housing 25. The worm wheel 26 is supported by a support cylinder 27 formed in the gear housing 25 so as to be rotatable about the central axis of the piston 15. The worm wheel 26 is integrally molded of synthetic resin.

The worm wheel 26 includes a clutch 22.
A connecting plate 28 for outputting rotation is fixed to the. Three engaging protrusions (only one is shown) 28a are provided on the connecting plate 28 at equal angular intervals, and each engaging protrusion 28a is provided in three engaging recesses 26a provided on the worm wheel 26. They are respectively engaged in the axial direction. Then, the worm wheel 26 and the rotary plate 28 are engaged with each other by the engagement between the engagement protrusions 28a and the engagement recesses 26a.
And rotate together.

A clutch 22 to which rotation is transmitted from a worm wheel 26 is provided on the output side of the worm gear 21. The clutch 22 is a two-way type, and includes a clutch housing 29, a clutch input shaft 30, a clutch output shaft 31, and a ball 32. The clutch 22 includes the clutch input shaft 30 to the clutch output shaft 3
1 is bidirectionally permitted, and rotationally transmitted from the clutch output shaft 31 to the clutch input shaft 30 is bidirectionally regulated. In the present embodiment, the clutch housing 29, the clutch input shaft 30, the clutch output shaft 31, and the balls 32 are constituent members of the clutch 22, respectively.

The clutch input shaft 30 is composed of the gear housing 2
5, a shaft portion 33 rotatably supported by the support cylinder 27, a support plate 34 provided at an end portion of the shaft portion 33, and three input side engagement members provided on the support plate 34 at equal angular intervals. Joint part 3
5 and.

One end of the shaft 33 is fixed to the connecting plate 28 and rotates integrally with the worm wheel 26. As shown in FIGS. 2 to 4, each input side engagement portion 35 is formed in a substantially T-shape when viewed from the central axis direction, and a substantially fan-shaped space portion is formed inside the clutch housing 29 between adjacent ones. Is forming.

The clutch output shaft 31 is, as shown in FIG. 1, a shaft portion 36 provided on the central axis of the piston 15.
And a base portion 37 provided at the end of the shaft portion 36 and disposed in the clutch housing 29, and three output side engaging portions 38 provided on the outer peripheral surface of the base portion 37 at equal angular intervals. There is.

As shown in FIGS. 2 to 4, each output side engaging portion 38 is formed in a substantially fan shape when viewed from the central axis direction, and is formed by the adjacent input side engaging portions 35 inside the clutch housing 29. It is arranged in a substantially fan-shaped space.

The balls 32 are prevented from coming off the outer region of the outer peripheral surface 38a of the output side engaging portion 38 by the outer peripheral surface 38a of the output side engaging portion 38 and the inner peripheral surface 29a of the clutch housing 29. Is held.

In the clutch 22 constructed as described above, when a rotational torque is applied to the clutch input shaft 30, the clutch input shaft 30 shown in FIG.
As shown in FIG. 7, the input side engaging portions 35 abut on the balls 32 as the clutch input shaft 30 rotates, and the balls 32 are provided at the central portion in the circumferential direction with respect to the outer peripheral surface 38 a of the output side engaging portions 38. To place. Then, the clutch housing 29
Inner peripheral surface 29a and the outer peripheral surface 38a of each output side engaging portion 38
So that the ball 32 is not pinched between and. By such an operation, the rotation of the clutch output shaft 31 is bidirectionally permitted, and the rotation of the clutch input shaft 30 is permitted.
It is directly transmitted to 1.

If reverse torque is applied to the clutch output shaft 31 with no rotation torque applied to the clutch input shaft 30, as shown in FIG. 3, as the clutch output shaft 31 and the clutch input shaft 30 rotate, Each ball 32 moves outward from the central portion of the outer peripheral surface 38a of the output side engaging portion 38. Then, each ball 32 has an outer peripheral surface 29 a of the clutch housing 29 and an outer peripheral surface 38 of the output side engaging portion 38.
It is sandwiched between a and. By such an operation, the rotation of the clutch output shaft 31 is bidirectionally restricted so that the clutch input shaft 30 does not rotate.

Further, from this state, the clutch output shaft 3
When a rotational torque in the same direction as the reverse torque applied to the clutch input shaft 1 is applied to the clutch input shaft 30, as shown in FIG.
2 and the outer peripheral surface 38a of the output side engaging portion 38.
On the other hand, the ball 32 is arranged at the central portion in the circumferential direction. The balls 32 are prevented from being sandwiched between the outer peripheral surface 29a of the clutch housing 29 and the outer peripheral surface 38a of each output side engaging portion 38. By such an operation, the reverse rotation of the clutch output shaft 31 is allowed from the state where the rotation of the clutch output shaft 31 is restricted, and the reverse rotation of the clutch input shaft 30 is transmitted to the clutch output shaft 31.

As shown in FIG. 1, the second cylinder body 1
3 is provided with a support hole 13a opening to the hydraulic chamber 16, and the shaft portion 36 of the clutch output shaft 31 is arranged in the support hole 13a.

The shaft portion 36 is provided with a support portion 39 which is in sliding contact with the inner peripheral surface of the support hole 13a. A support body 40 is provided at the end of the shaft portion 36. The support 40 is
Thrust bearing 4 provided at the peripheral edge of the opening of the support hole 13a
It is rotatably supported in the fluid pressure chamber 16 by 1. The support portion 39 and the support body 40 support the clutch output shaft 31 rotatably and non-retractably in the axial direction.

A screw shaft 42 is provided on the piston 15 side of the support 40 so as to rotate integrally with the clutch output shaft 31. A nut member 43 is screwed onto the screw shaft 42, and the nut member 43 is attached to the piston 15
Is disposed in a concave portion 15a provided on the base end side of the.
The nut member 43 is coupled to the piston 15 by a key 45 that engages with a groove 44 provided on the inner peripheral surface of the recess 15a so as to be relatively movable in the axial direction and integrally rotatable. In the present embodiment, the piston 15, the screw nut 42, the nut member 43, and the key 45 form a linear motion conversion mechanism.

The electric brake device 1 configured as described above
No. 0 is operated by a brake master cylinder that pumps hydraulic oil by a brake pedal operation and a parking brake control device that controls the rotation of an electric motor by operating a parking brake switch.

Next, the operation of the present embodiment configured as described above will be described. (During normal braking operation) When the brake pedal is operated to pump hydraulic fluid from the brake master cylinder to the hydraulic chamber 16, the piston 15 moves toward the disc rotor 18 and presses the brake pads 17 and 19 against the rotor 18. . As a result, the rotation of the rotor 18 is braked by the brake pads 17 and 19.

When the brake operation of the brake pedal is stopped, the hydraulic oil is no longer pumped and the piston cannot be pressed against the rotor. As a result, the rotor 18 is not braked by both brake pads 17 and 19.

(During parking brake operation) When the parking brake control device rotates the electric motor 20 in the normal direction based on the operation of the parking brake switch, the worm 24 rotating together with the output shaft 23 rotates the clutch input shaft 30 together with the worm wheel 26. .

The clutch input shaft 30 is the clutch output shaft 3
1, the screw shaft 42 is rotated, and the screw shaft 42 moves together with the nut member 43 into the piston 1
5 is moved to the disc rotor 18 side.

Then, the piston 15 becomes the brake pad 1.
7 is pressed against the rotor 18, and the brake pad 19 is also pressed against the rotor 18 via the brake caliper 11.
As a result, the disc rotor 18 becomes
It is braked by 7, 19 and its rotation is restricted.

When the parking brake control device stops the normal rotation of the electric motor 20, the return reaction force applied from the brake pad 17 tries to retract the piston 15. And
Reverse torque in the reverse rotation direction is applied to the screw shaft 42 and the clutch output shaft 31 via the nut member 43.

Then, the clutch 22 causes the clutch output shaft 3 to move.
The reverse rotation of No. 1 is restricted so that the reverse torque is not transmitted to the clutch input shaft 30. As a result, the piston 15 is held in the advanced position, and the state where both brake pads 17 and 19 brake the disc rotor 18 is held.

Therefore, the piston 15 and the worm gear 21
Since the reverse rotation is restricted by the clutch 22 provided between and, the reverse torque based on the return reaction force is not applied to the worm gear 21 during the parking brake.

When the parking brake controller reverses the electric motor from the stopped state based on the release operation of the parking brake switch, the clutch input shaft 30 and the clutch output shaft 31 rotate in reverse, and the screw shaft 42 rotates in reverse.

Then, the piston 15 is retracted from the rotor 18 side together with the nut member 43. As a result, both brake pads 17 and 19 do not brake the disc rotor 18, and the parking brake state is released.

Next, the effects of this embodiment will be listed. (1) A clutch 22 (coupling means) is provided between the piston 15 and the nut member 43 (linear motion conversion mechanism) and the worm gear 21 (reduction gear mechanism). Therefore, in the state where the parking brake is applied and the electric power supply to the electric motor 20 is stopped, a large reverse torque based on the return reaction force is not applied to the worm gear 21. Therefore, since the proof force required for the worm 24 and the worm wheel 26 becomes smaller, it is possible to use those integrally formed of synthetic resin. Therefore, the weight of the worm gear 21 can be further reduced, and the weight of the electric brake device 10 as a whole can be reduced.

In particular, since this embodiment is embodied in a disc brake device having a larger return reaction force than the drum brake device, the proof stress required for each gear 24, 26 is significantly reduced, and the entire device is reduced. Can be further reduced in weight.

(2) Piston 15 and worm gear 21
Since the constituent members of the clutch 22 provided between the rotor R and the brake pad 1 are integrally formed of metal.
The heat generated in 7 is radiated by the clutch 22 and is difficult to be transmitted to the electric motor 20 side. As a result, it is possible to prevent the output of the electric motor 20 from decreasing due to the temperature increase.

(3) Since the worm gear 21 is used as the reduction gear mechanism, a required reduction ratio can be obtained with a smaller number of gears as compared with the conventional reduction gear mechanism in which four spur gears are meshed in order. be able to. As a result, for example, it is possible to reduce the component cost and the assembly cost.

Embodiments other than the above embodiment embodying the present invention will be listed below. In the one embodiment, the reduction gear mechanism may have a higher transmission efficiency than a plurality of spur gears meshed in order. With such a configuration, there are the effects described in (1) and (2) of the above-described embodiment. In addition, a position where it overlaps with the piston 15 in its operation direction, that is,
Since the electric motor can be arranged beside the brake caliper and an electric motor having a lower output can be used, the brake device as a whole can be downsized.

In the embodiment, the connecting means restricts the reverse operation of the worm gear due to the return reaction force.
It may be a wake clutch. This configuration also has the effects described in (1) to (3) of the above-described embodiment.

The present invention may be embodied in a parking brake device provided separately from the service brake device. -The present invention may be implemented in a drum brake device. That is, for example, a duo servo type drum brake device is configured as an electric brake device that swings a link connecting two brake shoes.
Even in such an embodiment, the proof stress required for each gear of the reduction gear mechanism can be further reduced.

The present invention is applicable to passenger vehicles such as sedans and buses, transportation vehicles such as trucks and vans, industrial vehicles such as forklifts and shovel loaders, construction vehicles such as power shovels and dump trucks, trains, and diesel locomotives. It can be embodied in an electric brake device provided in various vehicles such as railway vehicles.

Hereinafter, the technical idea understood from each of the above-mentioned embodiments will be described together with its effects. (1) In the invention according to claim 1 or 2,
An electric brake device, wherein the reduction gear mechanism is a spur gear train. With such a configuration, the electric motor can be arranged at a position overlapping the linear motion portion (piston 15) of the direct-acting conversion mechanism in the operation direction thereof, so that the overall size of the device can be reduced.

(2) The invention according to any one of claims 1 to 5, wherein the motion conversion mechanism is provided with the brake friction material.

[0058]

According to the inventions of claims 1 to 5, the reduction gear mechanism for reducing the rotation output from the electric motor, and the brake friction member are moved forward and backward by converting the reduced rotation into a linear motion. Since the connecting means for restricting the transmission of the reverse torque based on the return reaction force is provided between the rotation / linear motion converting mechanism and the rotating / linear motion converting mechanism, it is possible to further reduce the proof stress required for each gear of the reduction gear mechanism. .

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing an electric brake device of the present embodiment.

FIG. 2 is a schematic cross-sectional view taken along the line AA of FIG. 1 showing a clutch.

FIG. 3 is a schematic sectional view showing a clutch of the same.

FIG. 4 is a schematic sectional view showing a clutch of the same.

FIG. 5 is a schematic cross-sectional view showing a conventional electric brake device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Electric brake device, 15 ... Piston as a linear motion part which comprises a linear motion conversion mechanism, 17 ... Brake pad as a brake friction material, 18 ... Disk rotor as a braking rotor, 19 ... Brake as a brake friction material Pads, 20 ... Electric motor, 21 ... Worm gear as reduction gear mechanism, 22 ... Clutch as connecting means, 2
3 ... Output shaft, 24 ... Worm as a gear constituting a reduction gear mechanism, 26 ... Worm wheel similarly, 29 ... Clutch housing as a constituent member constituting coupling means, 30 ... Clutch input shaft, 31 ... Clutch output as well Shaft, 32 ... Ball, 42 ... Screw shaft constituting a linear motion converting mechanism, 43 ... Similar nut material,
45 ... Also the key.

Claims (5)

[Claims] 1. An electric motor capable of rotating an output shaft in forward and reverse directions, a reduction gear mechanism for reducing rotation output from the output shaft of the electric motor, and conversion of rotation output by the reduction gear mechanism into linear motion.
A direct-acting conversion mechanism that brings the brake friction material into and out of contact with the braking rotor on the vehicle side by forward and reverse rotations of the output shaft of the electric motor; and a return reaction force that is reversely input from the brake friction material to the direct-acting conversion mechanism. Connection means for restricting reverse transmission of reverse torque to the electric motor based on the above, the connection means is provided between the reduction gear mechanism and the direct-acting conversion mechanism, and the reverse torque is applied to the reduction gear mechanism. An electric brake device characterized by being prevented from being input. 2. The electric brake device according to claim 1, wherein at least one of the plurality of gears forming the reduction gear mechanism is integrally formed of synthetic resin. 3. The reduction gear mechanism is a worm gear including a worm fixed to an output shaft of the electric motor, and a worm wheel meshing with the worm. Electric brake device. 4. The electric brake device according to claim 1, wherein each component of the clutch is integrally formed of metal. 5. The electric brake device according to claim 1, wherein the braking rotor is a disc rotor.