JP2001122090A - Motor-driven parking brake - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor-driven parking brake easily switched over to manual operation from the pull-operated state of a brake cable. SOLUTION: A sub-lever 4 with a brake cable 5 rigidly fixed thereto is driven by a motor M through a planetary gear mechanism G2. Connection between the sub-lever 4 and the motor M is released by releasing a stopper mechanism 52 of a stationary element (such as a ring gear 40) of the planetary gear mechanism G2 to obtain free rotation. The sub-lever 4 and an operating lever 3 have play by a specified angle and are energized by a coil spring 33. When play is blocked against the energizing force of the coil spring 33 by the operation of the operating lever 3, the motor M is started by a limit switch LS to take assist action.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electric parking brake. More specifically, the present invention relates to an electric parking brake that can be easily switched to manual operation when an electric actuator breaks down.

[0002]

2. Description of the Related Art Japanese Unexamined Patent Publication No. Hei 4-230467 discloses a servo assisted parking brake which can immediately switch to manual operation when an electric actuator fails. This is shown in FIG.
Operation lever 10 provided with conventionally known ratchet claw 100
1, a manual operation mechanism including a driving plate 103 rotatable around the support shaft 102 by a clockwise pulling operation of the operation lever, and a brake cable 104 having an end connected to the driving plate. I have. Further, the screw shaft 106 connected to the motor M, the planetary gear unit G, and the carrier 105 as an output element thereof, and a nut 107 screwed to the screw shaft (rotating spindle).
And an electric operation mechanism including a turning plate 108 that rotates around the support shaft 102 in cooperation with the nut, and a lever 109 for manually connecting and disconnecting the turning plate 108 and the entrainment plate 103. Have.

In this device, an electric operation mechanism and a manual operation mechanism are arranged in parallel, and a lever 109 is connected to a driving plate 103.
When it is engaged with the first notch 110, the electric operation is possible. When it is engaged with the second notch 111,
It is configured to allow manual operation.

On the other hand, JP-A-3-70659 discloses that
As shown in FIG. 8, an electric actuator 112 is interposed between an operation lever 101 having a ratchet claw 100 and a brake cable 104, that is, a parking brake in which an electric operation mechanism and a manual operation mechanism are arranged in series. A booster is disclosed. This is based on its structure,
Both manual operation and electric operation can be performed without using a switching lever or the like.

[0005]

The above-mentioned conventional electric parking brakes can be manually operated when electric operation is no longer possible. However, when the brake is manually released from the state in which the brake is applied, since a large tension is applied to the brake cable 104, it is necessary to manually operate the switching lever 109 or to remove the ratchet claw 100. Need great power. In particular, in these parking brakes, since the brake cable 104 is pulled by the electric actuator, a stronger tension is generated than in the manual operation, so that it is difficult to release the ratchet pawl.

An object of the present invention is to provide an electric parking brake that can relatively easily switch from a state in which a brake cable is pulled by an electric operation to a manual operation.

[0007]

An electric parking brake according to the present invention includes a mechanism for converting the rotation of a motor into a pulling force of a brake cable through a speed reducer, and allows an operation in a direction in which the brake cable is pulled. An electric parking brake provided with a detachable ratchet mechanism for preventing operation in an opposite direction, wherein the speed reducer includes a planetary gear reducer having a sun gear, a planetary gear, a carrier of a planetary gear, and a ring gear. Together with the sun gear,
Of the carrier and the ring gear, either the carrier or the ring gear is a stationary element, the other two elements constitute an input element and an output element, and the stationary element is provided rotatably around its own axis, It is characterized by having a locking means capable of switching between a state in which the rotation is permitted and a state in which the rotation is restricted.

According to a second aspect of the parking brake of the present invention, an operation lever rotatably supported by a bracket and a rotatably supported concentrically with the operation lever, one end of a brake cable is provided. A connected sub-lever, an electric actuator for rotating the sub-lever in a direction in which the brake cable is pulled when the operation lever is rotated in a direction in which the brake cable is pulled, and an operation provided between the operation lever and the bracket. A detachable ratchet mechanism for allowing the lever to rotate in the direction in which the brake cable is pulled and preventing the lever from rotating in the opposite direction, wherein the operation lever and the sub-lever release the tension of the brake cable from the operation lever. When pivoted in the direction, the sub-lever is directly pivoted in the same direction without using an electric actuator. It is and, the electric actuator decelerates the motor, the rotation of the motor, provided with a sun gear, planetary gears, and a planetary reduction gear having a carrier and a ring gear of the planetary gear, the sun gear,
Of the carrier and the ring gear, either the carrier or the ring gear is a stationary element, the other two elements constitute an input element and an output element, and the stationary element is rotatably provided, and It is characterized in that it is provided with a locking means which can be manually switched between an allowed state and a restricted state.

In this device, the sub-lever and the operation lever are relatively rotatably supported within a predetermined angle range, and the sub-lever is constantly biased against the operation lever in the direction of pulling the brake cable. Means for detecting that the operating lever has been turned in the pulling direction of the brake cable against the urging force of the spring,
A control circuit for rotating the motor in the direction in which the brake cable is pulled based on the detection by the detection means is preferable. Further, it is preferable that a one-way clutch is provided between the motor and the input element, which transmits torque by rotation in a direction of pulling a brake cable of the motor as viewed from the motor side and makes rotation in the opposite direction free.

[0010]

In the normal operation of the parking brake of the present invention, the stationary element of the planetary gear reducer is restrained by a locking means so as not to rotate. In this state, the motor side, the reduction gear, and the brake cable side are connected. Therefore, when the motor is rotated in one direction, the rotation is decelerated by the speed reducer and then converted into an operation force of the brake cable. Thereby, the electric brake operation is performed. In the case of the brake release operation, the brake cable is sent out using the electric actuator by, for example, rotating the motor in the reverse direction. Alternatively, reverse the motor or turn off the electromagnetic clutch to eliminate the load on the motor side,
Release the brake manually.

When the electric operation cannot be performed due to a decrease in the power supply voltage or a failure of the motor, the restraining of the stationary element by the locking means is released. As a result, the output element of the speed reducer idles, so that the brake cable can be operated manually.

In a brake state in which tension is applied to the brake cable, a one-way rotational force based on the tension of the brake cable is applied to the stationary element by the action of the ratchet mechanism. In this case, however, a deceleration action is performed with the “input element” as the stationary element and the “static element” as the input element, so that the engagement between the locking means and the stationary element can be easily released. Therefore, even if a failure occurs in the electric system in the brake state, the brake state can be easily released manually.

In the second aspect of the parking brake of the present invention (claim 2), when the operating lever is operated in the direction of applying the brake, the motor rotates the sub-lever via the speed reducer and pulls the brake cable. . Therefore, the operation lever only needs to function as a switch of the electric actuator, so that the brake can be easily applied. When releasing the brake, the operating force of the operating lever is directly transmitted to the sub-lever, and the braking action can be released. When a speed reducer having a self-restraining action such as a worm gear speed reducer is used on the motor side in addition to the planetary gear speed reducer, the operation can be performed by rotating the motor in reverse.

In this case, when a failure occurs in the electric system, the locking means is operated to make the stationary element of the reduction gear of the electric actuator freely rotatable, as in the case described above. In this case, the operation of the locking means is also easy. Particularly in the brake state, a large tension is applied to the brake cable by the action of the ratchet mechanism, but it is easy to release the restraint of the stationary element as in the case described above.

A sub-lever and an operation lever are rotatably supported within a predetermined angle range, and a spring is provided for constantly urging the sub-lever with respect to the operation lever in the direction of pulling the brake cable. Means for detecting that the operating lever is turned in the direction of pulling the brake cable against the urging force of the spring, and control for rotating the motor in the direction of pulling the brake cable based on the detection of the detecting means. In the case of a parking brake having a circuit (claim 3), when the operating lever is turned in the direction in which the brake is applied, the tension of the brake cable is applied to the sub-lever against the urging force of the spring. , Only the operating lever pivots somewhat. As a result, the position of the operation lever and the position of the sub-lever are shifted, and the detecting means detects that. As a result, the motor of the electric actuator rotates, and the brake cable can be pulled and operated while being assisted by the electric actuator.

To release the brake state, the operation lever may be rotated in the reverse direction while rotating the motor in the reverse direction. The same applies to the case where the electric system has failed.

A parking brake having a one-way clutch interposed between the motor and the input element for transmitting torque by rotation in a direction in which a brake cable of the motor is pulled when viewed from the motor side and freeing rotation in the opposite direction. (Claim 4)
In the case of, the operation lever can be rotated faster than the rotation speed of the sub lever by the motor due to the sliding action of the one-way clutch. Therefore, during the early stage of the braking operation, while the pulling force of the brake cable is weak,
Regardless of the rotational speed of the motor, the operation lever can be operated with a natural feeling of the driver. To release the brake, return the operation lever while rotating the motor in the reverse direction. When the electric system is out of order, it is the same as the case described above.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an electric parking brake according to the present invention will be described below with reference to the drawings. 1 is a schematic exploded perspective view showing an embodiment of the parking brake of the present invention, FIG. 2 is a partially cutaway plan view showing the entire parking brake, FIG. 3 is a partially cutaway side view of the parking brake, 4a is an enlarged view of a main part of FIG. 2, FIG. 4b is a sectional view taken along the line IV-IV of FIG. 4a, FIG. 5 is a side view of the parking brake seen from the back side, FIG.
6 and 6b are cross-sectional views each showing an embodiment of the locking means according to the present invention.

A parking brake A shown in FIG. 1 includes a bracket 1 fixed to a frame of an automobile, an operation lever 3 and a sub-lever 4 rotatably supported by a support shaft 2 on the bracket, and an end connected to the sub-lever 4. A brake cable 5 whose part is locked and a power unit 6 for rotating the sub-lever 4 in the direction of pulling the brake cable are provided. The power unit 6 includes a motor M, a first reduction gear G1 connected to an output shaft of the motor, and a one-way clutch 7 connected to the output shaft.
And a planetary gear type second reducer G connected to the output shaft
Consists of two. In this embodiment, a worm gear reducer is used as the first reducer G1.

The bracket 1 is formed by bending a metal plate into a substantially L-shape to form a mounting base 11 and a rising portion 12.
Are provided. Further, the end of the rising portion 12 is extended and folded in a U-shape, and the supporting portion 13 of the first reduction gear G1 is formed.
(See FIG. 2). On the left side of the rising portion 12, a locking piece 15 having ratchet teeth 14 arranged in an arc shape is provided. On the right side, a bearing portion 16 for rotatably supporting the support shaft 2 and a second gear reducer G2 are provided. A holding unit 17 is provided. The gear case 18 is attached to the holding portion (see FIG. 4A).

The operating lever 3 includes a main body 20 formed by bending a metal plate into a U-shaped cross section and forming a rear side into a cylindrical shape, and a grip 21 attached to a rear portion of the main body 20 (FIG. 2).
And FIG. 3). A hole 22 through which the support shaft 2 penetrates is formed near the distal end of the main body 20. Further, somewhat behind the front end, a pin 23 is attached so as to pass between left and right walls constituting the main body, and a ratchet claw 24 is rotatably provided on the pin 23 (see FIG. 4B).

The ratchet pawl 24 is provided at its lower end with a locking pawl 25 which meshes with the ratchet teeth 14 provided on the bracket 1 described above. As shown in FIG. 3, the upper end thereof is connected to a ratchet releasing push button 26 provided at the rear end of the main body 20 so as to be freely retractable by a connecting rod 27. The push button 26 has a spring 28
Of the ratchet claw 24
Are always urged to the side where the locking claws 25 mesh with the ratchet teeth 14.

The ratchet teeth 14, ratchet pawls 24 and locking pawls 25 are shaped such that when the operating lever 3 is pulled up, the locking pawls 25 slide on the ratchet teeth 14 against the urging force of the spring 28. It is shaped to be locked when pushed down. The ratchet pawl 24, the ratchet teeth 14, the push button 26, and the connecting rod 27 are conventionally known. However, the connecting rod 27 is bent in a crank shape to avoid interference with a connecting pin 29 that connects the operation lever 3 and the sub-lever 4 so as to transmit torque. The connecting pin 29 is fixed near the center of the main body 20 of the operation lever 3 so as to penetrate the left and right walls and protrude to the rear side.

The sub-lever 4 is mounted on the back side of the operation lever 3 so as to be rotatable around the same support shaft 2. The sub-lever 4 is a plate-shaped member having a predetermined shape, and is bent so as to project downward before and after the support shaft 2, as shown in FIG. The sub-lever 4 can be formed by punching a metal plate into a predetermined shape. The front end side of the sub-lever 4 is a sector gear 4a that meshes with a gear 48 described later. In addition, the brake cable 5
A pin 4b for rotatably locking the cable end 5a fixed to the end of the cable is protruded. A long hole 30 into which the connection pin 29 is inserted is formed at the rear end of the sub lever 4. The long hole 30 is oriented vertically so that the connecting pin 29 can move in the rotation direction of the sub-lever 4. Therefore, the operating lever 3 and the sub-lever 4 arranged concentrically on the back side thereof are connected with a play in the rotating direction so as to be relatively rotatable within a predetermined angle range. The reason that the sub-lever 4 is bent as described above is to avoid interference with the second limit switch LS2 and to make the sub-lever 4 follow the operation lever 3 at the rear.

As shown in FIG. 4A, the support shaft 2 protrudes from the back surface of the sub-lever 4, and a needle (roller) bearing 31 is rotatably mounted on the protruding portion 2a. A commercially available cam roller or cam follower can be used for the needle bearing 31 and the support shaft 2. Furthermore, in the upper part somewhat rearward from the front end of the operating lever 1,
Locking pins 32 penetrating the left and right walls of the main body 20 are fixed. Around the bearing 31, a recoil spring 33 is provided.
5, one arm 34 is locked to the lower edge of the sub-lever 2, and the other arm 35 is locked to the locking pin 32, as shown in FIG. Thus, the operation lever 3 and the sub lever 4 are constantly urged in the direction in which the operation lever 2 is pulled up with respect to the sub lever 4. Therefore, the connecting pin 29 of the operation lever 3 is stopped by contacting the lower end of the long hole 30 of the sub lever 4.

When the operating lever 3 is pulled up, only the operating lever 3 can be pulled up within the range of the play of the elongated hole 30 and the connecting pin 29, leaving the sub-lever 4 urged downward by the brake cable 5. After the connecting pin 29 comes into contact with the upper end of the elongated hole 30, the sub-lever 4 is pulled up together against the urging force of the brake cable 5. A first limit switch LS1 for detecting the position of the connecting pin 29 is attached to the upper part of the rear end of the sub-lever 4. This first limit switch LS1
When the operating lever 3 is being pulled up, it is possible to detect that the operating lever 3 has been pulled up by detecting that the connecting pin 29 has come up inside the elongated hole 30.
Reference numeral LS2 in FIG. 5 is a second limit switch for detecting whether the ratchet pawl 24 is engaged with or disengaged from the ratchet tooth row 14, and is attached to the inner surface of the wall of the operation lever 3.

The first reduction gear G1 is composed of a worm connected to the output shaft of the motor M and a worm wheel meshing with the worm. A commercially available product set with the motor M is used. Can. The shaft of the worm wheel, which is the output shaft, is connected to a cylindrical shaft 36 as shown in FIG. 4a. Its shaft 36
Inside, a case which is an input side of a one-way clutch (one-way clutch) 7 is fitted and fixed. The output shaft 37 of the one-way clutch is connected to the input shaft 38 of the second reduction gear G2.

As shown in FIGS. 4A and 4B, a second reducer G2, which is a planetary gear reducer, includes a sun gear 39 fixed to the input shaft 38 and a gear case 18 fixed to the bearing 16 of the bracket 1. The ring gear 40 rotatably supported by the three, the three planetary gears 41 interposed therebetween, and the planetary gears 41 are held at equal intervals,
It comprises a carrier 42 which is itself an output member. The carrier 42 has three shafts 43 for rotatably supporting the planetary gear 41, two disk members 44 and 45 for supporting them from both sides, and an output shaft 46 fixed to the upper disk member 45 in FIG. Consists of

As shown in FIG. 5, the gear case 18 includes a cylindrical member 18a having a bottom and a bracket 1a.
And a mounting piece 18b for fixing the mounting piece 18b. A notch 18c is formed in the bottomed cylindrical member 18a to avoid interference with the sub-lever 4. At the center of the bottom of the bottomed cylindrical member 18a, as shown in FIG.
A support shaft 47 protrudes, and the support shaft 48 rotatably supports the gear 48. The gear 48 is connected so as not to rotate with respect to the output shaft 46 of the second reduction gear G2.

The above-described ring gear 40 normally functions as a stationary gear, and therefore, as shown in FIG. 6A, a plurality (for example, eight) of notches or grooves 51 are formed on the outer peripheral surface, and the notches or grooves 51 are formed. A stopper mechanism 52 that engages with the groove 51 and restricts rotation of the ring gear 40 is provided on the gear case 18. The stopper mechanism 52 always restricts the rotation of the ring gear 40, and permits the rotation in the event of a failure of the electric system or the like. Locking means that can be switched to

The stopper mechanism 52 is connected to the gear case 18.
A cylindrical guide 53 provided in the radial direction, a slide pin 54 that is movable in the radial direction along the guide, and a tip of which engages with the groove 51 of the ring gear 40, and the slide pin 54 is always kept outward. A biasing spring 55 and a switching lever 56 for pushing the slide pin 54 inward are provided. The switching lever 56 is supported rotatably about a support shaft 57. The contact portion of the switching lever 56 with the slide pin 54 is an arc-shaped eccentric cam 58. When the switching lever 56 is rotated clockwise to push the slide pin 54, the slide pin is reversed from a certain angle. 54 returns upward. When the switching lever 56 is released in this state, the switching lever 56 is further urged clockwise by the urging force of the slide pin 54 in the return direction. Thereby, the switching lever 56
Abuts against a stopper 59 provided on the guide 53 and can be locked so that the slide pin 54 does not return any further. In addition, as a stopper mechanism of the ring gear 40,
The internal thread 6 provided on the gear case 18 as shown in FIG.
0 and a screw 61 screwed into the female screw 60.

As shown in FIG. 3, the parking brake A configured as described above is mounted on the wheel side of the vehicle via a load sensor 70 for confirming that the pulling force is reliably transmitted to the brake. It is used by being connected to a brake shoe or a brake pad of the provided brake 71. Such a brake 71 is normally urged by a return spring to a side where a brake shoe or the like releases the brake of the wheel, and when the brake cable 5 is pulled in the direction of the arrow P against the urging force of the return spring. Brakes. In the above embodiment, the brake cable 5 is slidably guided by the conduit 72, and both ends thereof are fixed or locked to the vicinity of the parking brake A and the vicinity of the load sensor 70, respectively. The conduit 72 together with the brake cable 5 constitutes a so-called pull control cable. Hereinafter, the operation and effect of the parking brake A will be described.

[Braking Operation] When the operating lever 3 of the parking brake A is slowly pulled up in the direction of arrow J in FIG. 3, the first limit switch LS1 detects the connecting pin 29. Therefore, the motor M of FIG. 1 rotates,
The output shaft of the first reduction gear G1 is reduced in speed and rotates in the direction of arrow K. Thereby, the cylindrical shaft 3 of the one-way clutch 7
6 rotates in the same direction, and the sun gear 39 of the second reduction gear G2 rotates in the same direction. In the second reduction gear G2, the ring gear 40
Is restricted by the stopper mechanism 52,
The planetary gear 41 rotates in the ring gear 40 with the arrow K while rotating.
Orbit in the direction. Accordingly, the output shaft 46 fixed to the carrier 42 is decelerated and rotates in the direction of arrow K. As a result, the gear 48 rotates in the direction of the arrow K, and the sector gear 4a meshing with the gear 48 rotates in the direction of the arrow J. Therefore, the sub-lever 4 pulls the brake cable 5 in the direction of arrow P, and the brake is applied.

The above operation is performed when the speed of pulling up the operation lever 3 is low. In this case, since the rotation speed of the sub-lever 4 by the motor M is high, a torque for rotating the sub-lever 4 is applied from the motor M side. . Therefore, the one-way clutch 7 transmits the torque, and the above operation is performed. However, in the initial stage of the operation of applying the brake, the pulling speed of the operation lever 3 is often faster than the rotation speed of the sub lever 4 by the motor M because the tension of the brake cable 5 is low. In this case, since the sub-lever 4 is pulled up from the operation lever 3 via the connecting pin 29, the motor M side is to be rotated from the sub-lever 4 side via the one-way clutch 7. However, in this case, since the one-way clutch 7 is in the idling direction, the operation lever 3 can be freely pulled up without being affected by the load on the motor side. Then, the assisting operation by the motor M is performed only when the tension of the brake cable 5 increases after the braking starts to work. That is, the parking brake A is
From the middle of the manual operation, the operation automatically shifts to the power assist operation as needed.

As described above, in the parking brake A, the brake cable can be maintained only by maintaining the operating lever 3 in a state where the limit switch LS1 is acted on the sub-lever 4 against the urging force of the recoil spring (reference numeral 33 in FIG. 5). 5
Can be subtracted. When the lifting of the operation lever 3 is stopped after the brake operation is completed, only the sub-lever 4 continues to rotate and catches up with the angle of the operation lever 3. Therefore, the limit switch LS does not detect the connection pin 29, and the operation of pulling the brake cable 5 stops. When the lifting of the operating lever 3 is stopped, there is play between the operating lever 3 and the sub-lever 4, so that the operating lever 3 can be returned somewhat downward even though the one-way clutch 7 is in the opposite direction. By doing so, the ratchet pawl 24 can be meshed with the ratchet teeth row 14.

The raising of the operating lever can be stopped halfway to engage the ratchet. However, in that case, the brake operation is stopped in a state where sufficient tension is not applied to the brake cable 5. Therefore, it is preferable that the tension of the brake cable 5 is detected by a sensor and the motor M is stopped when a sufficient tension is generated.

[Brake release operation] The operation lever 3 is slightly pulled, and the ratchet release push button 2 is released.
Press 6 to release the ratchet. At that time, the position of the ratchet pawl 24 is detected by the second limit switch LS2, and the motor M rotates in the opposite direction. The reverse rotation of the motor M is performed in order to avoid the restraining action on the motor M side by setting the one-way clutch 7 to the idling direction because a worm gear reducer having a restraining force is employed as the first reducer G1. . In this state, the operation lever 3 is in a range where it cannot catch up with the rotation of the motor M, that is, the one-way clutch 7
Can freely rotate the operation lever 3 downward within the range of the idle direction. In this case, since the brake cable 5 is pulled by the return spring of the brake 71, the operation to relax the force for supporting the operation lever 5 upward is rather performed. Further, the rotation speed of the motor M is set so as not to hinder the rotation of the operation lever 3 in the free return direction.
It is preferable to rotate at high speed.

[Operation in Case of Failure of Electric System] If the electric system fails due to a decrease in the power supply voltage or the like, the motor M cannot be rotated. Therefore, in order to operate manually, it is necessary to release the connection between the first reduction gear G1 side and the operation lever 3 side. Such a release may be achieved by, for example, releasing the connection between the gear 48 and the sector gear 4a. However, a strong contact force acts between them based on the tension of the brake cable 5,
The accompanying frictional force is also large. Therefore, it is not easy to release the connection between the gear 48 and the sector gear 4a.

In the parking brake A, the above problem is solved by adopting a method in which the rotation of the ring gear 40 of the second reduction gear G2 is made free. That is, when the stopper mechanism 52 is released and the switching lever 56 is pulled up, the slide pin 54 projects radially outward by the urging force of the spring 55. The frictional force applied to the slide pin 54 is reduced by the planetary gear reducer G2 (the gear 4
The speed is increased when viewed from the number of revolutions of 8), so that the force is relatively weak. The reduction ratio is determined by the planetary gear reducer,
This corresponds to a reduction ratio when the carrier 42 when the sun gear 39 is restrained and the ring gear 40 as an output element is used as an input element. Therefore, switching to manual operation is easy.

After operating the switching lever 56, the ring gear 40 freely rotates and the planetary gear reducer has no self-restraining action, so that the operating lever 3 can be freely rotated in any direction. Can be. Therefore, the operating lever 3 is released while pressing the push button 26 to release the restraint by the ratchet mechanism, as in the case of the normal manual operation.
If you move the sub-lever 4 downward,
Rotates, and the force for pulling the brake cable 5 can be reduced. Further, if necessary, the brake can be manually applied by manually pulling up the operation lever 3.

In the above embodiment, a worm gear reducer is used as the first reducer G1, but a planetary gear reducer may be used as the first reducer. In that case, since there is no self-restraining action, it is not necessary to rotate the motor M in the reverse direction when releasing the brake. In the above embodiment,
Although the sun gear 39 of the second reduction gear G2 is used as an input element on the motor M side and the carrier 42 is used as an output element, the carrier may be used as an output element and the sun gear may be used as an input element. Also in this case, the ring gear, which is a stationary element, is restrained by a locking means so as to be freely detachable. Further, although the reduction ratio is reduced, the sun gear can be used as an input element and the ring gear can be used as an output element. In this case, the carrier, which is a stationary element, is restrained by a locking means so as to be freely detachable.

The above-described parking brake A is provided with a power assist device that automatically performs power assist when the operating force increases during manual operation.
However, the device of the present invention can also be applied to a fully electric type parking brake in which the brake cable is pulled or loosened only by operating the operation button or switch on the instrument panel, for example.

[Brief description of the drawings]

FIG. 1 is a schematic exploded perspective view showing an embodiment of a parking brake according to the present invention.

FIG. 2 is a partially cutaway plan view showing the entire parking brake.

FIG. 3 is a partially cutaway side view of the parking brake.

4A is an enlarged view of a main part of FIG. 2, and FIG. 4B is a sectional view taken along the line IV-IV of FIG. 4A.

FIG. 5 is a side view of the parking brake as viewed from the back side.

6a and 6b are cross-sectional views each showing an embodiment of the locking means according to the present invention.

FIG. 7 is a partially cutaway side view showing an example of a conventional electric parking brake.

FIG. 8 is a side view showing another example of the conventional electric parking brake.

[Explanation of symbols]

 Reference Signs List A parking brake 1 bracket 2 support shaft 3 operating lever 4 sub-lever 5 brake cable 6 power unit G1 first reducer G2 second reducer 7 one-way clutch 14 ratchet teeth 18 gear case 24 ratchet pawl 26 push button 29 connecting pin 30 long hole 4a Sector gear 33 Recoil spring LS1 First limit switch LS2 Second limit switch 39 Sun gear 40 Ring gear 41 Planetary gear 42 Carrier 48 Gear 51 Groove 52 Stopper mechanism 53 Guide 54 Slide pin 55 Spring 56 Switching lever 57 Support shaft 58 Eccentric cam 59 Stopper 70 Load Sensor 71 Brake 72 Pipe

Claims (4)

[Claims] 1. A detachable ratchet mechanism comprising a mechanism for converting the rotation of a motor into a pulling force of a brake cable via a speed reducer, allowing an operation in a direction in which the brake cable is pulled, and preventing an operation in the opposite direction. An electric parking brake provided, wherein the speed reducer is a sun gear,
A planetary gear reducer having a planetary gear, a carrier of the planetary gear and a ring gear, wherein one of the sun gear, the carrier and the ring gear is a stationary element, and the other two elements are an input element and an output element. And an electric parking brake, wherein the stationary element is provided rotatably around its own axis, and is provided with locking means capable of switching between a state in which the rotation is permitted and a state in which the stationary element is restricted. . 2. An operation lever rotatably supported by a bracket, a sub-lever rotatably supported concentrically with the operation lever and connected to one end of a brake cable, and an operation lever. An electric actuator for rotating the sub-lever in the direction in which the brake cable is pulled when the brake cable is turned in the direction in which the brake cable is pulled; and a rotation in the direction in which the brake cable is pulled for the operation lever, provided between the operation lever and the bracket. And a detachable ratchet mechanism for preventing rotation in the opposite direction. When the operation lever and the sub-lever rotate the operation lever in a direction to loosen the tension of the brake cable, the electric actuator is provided. The sub-lever is connected so as to rotate in the same direction directly without using a motor, and the electric actuator is And a planetary gear reducer having a sun gear, a planetary gear, a planetary gear carrier and a ring gear for reducing the rotation of the motor, and any one of the carrier or the ring gear among the sun gear, the carrier and the ring gear is provided. In the stationary element, the other two elements constitute an input element and an output element, and the stationary element is provided rotatably, and can be manually switched between a state in which the rotation is permitted and a state in which the rotation is restricted. Electric parking brake with locking means available. 3. A spring for supporting the sub-lever and the operation lever so as to be relatively rotatable within a predetermined angle range, and for constantly urging the sub-lever against the operation lever in the direction of pulling the brake cable. Means for detecting that the operating lever has been turned in the direction of pulling the brake cable against the urging force of the spring, and based on the detection of the detecting means, the motor is turned in the direction of pulling the brake cable. The parking brake according to claim 2, further comprising a control circuit for rotating the parking brake. 4. A one-way clutch is provided between the motor and the input element to transmit torque by rotation in a direction of pulling a brake cable of the motor and to make rotation in the opposite direction free when viewed from the motor side. The parking brake according to claim 2.