JP2011027219A - Actuator for electromotive parking brake and electromotive parking brake using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a space-saving actuator which obtains a predetermined torque for operation to pull a brake and naturally returns to a brake operation position again, and an electromotive brake using the actuator. <P>SOLUTION: The actuator 1 includes a motor M which rotates a driving shaft 12, a sun gear 21 which is fixed to the driving shaft, one or more planet gears 22 which are disposed around the circumference of the sun gear and are disposed to engage with the sun gear, a carrier 25 which rotatably retains the planet gears, a ring gear 23 which is disposed outside the planet gears and is disposed to engage with the planet gears, the first pulley 28 which rotates along with the carrier and winds the first inner cable 5, the second pulley 29 which rotates along with the ring gear and winds the second inner cable 6, and a stopper mechanism 13 which allows rotation from the motor of the driving shaft and obstructs rotation from the gear side. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an actuator for an electric parking brake (hereinafter referred to as an actuator) and an electric parking brake using the same. More specifically, the present invention relates to an actuator having a simple structure and an electric parking brake using the actuator.

  FIG. 6 shows the actuator of Patent Document 1. The actuator 100 includes a crankshaft 101 that is rotationally driven by a power source, and two small-diameter gears 102a and 102b that are pivotally supported in parallel to the pin 101a of the crank. A first ring gear 103a and a second ring gear 103b formed with internal teeth that mesh with the small-diameter gears 102a and 102b are arranged outside the small-diameter gears 102 and 103, respectively, so as to be rotatable concentrically with the crankshaft 101. Has been. One end of each of the tension members 104 and 105 is connected to the first ring gear 103a and the second ring gear 103b, respectively, and the other end thereof is connected to a member that operates a brake. The first ring gear 103a and the second ring gear 103b are formed so that the ratio of the number of teeth of the corresponding small-diameter gears 102a and 102b is different. Therefore, when the crankshaft 101 rotates in one direction, a relative angular difference is generated between the first ring gear 103a and the second ring gear 103b in accordance with the difference in the ratio of the number of teeth, thereby causing the tension members 104 and 105 to rotate. Are wound in opposite directions.

  FIG. 7 shows a reduction gear of Patent Document 2. The speed reducer 110 includes shafts 113 and 113 arranged symmetrically with respect to the rotation center of the input side bracket 112 fixed to the input shaft 111, and planetary gears 114 and 114 rotatably attached to the shafts 113. have. A rotating ring gear 115 that meshes with the planetary gears 114 and 114 is disposed outside the planetary gears 114 and 114. The rotating ring gear 115 is connected to the output shaft 116, and the rotation from the input shaft 111 is transmitted to the output shaft 116 via the planetary gear 114.

WO 2006/066295 JP-A-7-332448

  In Patent Document 1, a mechanism for separately supporting the rotation of the first ring and the second ring is required (for example, outside the ring). Therefore, the mechanism is complicated and it is difficult to save space. Moreover, since there is no self-restraining force, the brake may be loosened.

  Therefore, an object of the present invention is to provide an actuator that uses a planetary gear speed reduction mechanism, saves space, and is less likely to loosen a brake, and an electric brake using the actuator.

  An actuator of the present invention is an electric parking brake actuator that operates left and right parking brakes by pulling and operating two inner cables, and is a motor that is fixed to a vehicle body and that rotates a drive shaft. A sun gear fixed to the drive shaft, one or more planetary gears arranged around the sun gear and arranged to mesh with the sun gear, the planetary gear rotatably held, and the sun A carrier that is concentrically rotatable with the gear, a ring gear that is disposed outside the planetary gear and meshes with the carrier, and that is concentrically rotatable with the sun gear, and rotates together with the carrier. A first pulley that winds the first inner cable in one direction, and the ring gear rotates together with the second inner cable. A second pulley for winding the cable in the other direction, allow rotation of the motor of the drive shaft, is characterized by comprising a stopper mechanism which prevents the rotation from the gear side.

  An electric parking brake of the present invention has a brake operation member, one of the actuators described above that operates by operating the brake operation member, and a first pulley and a second pulley of the actuator each having one end. The first and second inner cables are locked, and left and right parking brakes to which the other ends of the first and second inner cables are respectively connected.

  (1) Since the actuator of the present invention uses the planetary gear speed reduction mechanism, two different powers in the rotational directions can be obtained by the ring gear and the carrier on which the planetary gear is pivotally supported. And since those motive powers are coaxial with the drive shaft of a motor, it is space-saving. Further, since the stopper mechanism that allows rotation of the drive shaft from the motor and prevents rotation from the gear side is provided, the brake can be maintained so as not to loosen.

  (2) As such an actuator, a drive gear for transmitting the rotation of the motor to the drive shaft, a brake spring interposed between the drive gear and the drive shaft, and a cylindrical shape disposed around the brake spring A brake member is formed on the drive gear to push the end of the brake spring in a direction to reduce the spring diameter, and the end of the brake spring is increased on the drive shaft. An arm member that pushes in the direction is formed, and when the drive shaft attempts to rotate, the diameter of the brake spring increases, abuts against the inner surface of the brake drum, the rotation is prevented, and the drive gear attempts to rotate The spring diameter decreases and the brake spring does not touch the inner surface of the brake drum If, because the drive shaft by the brake spring does not reverse rotation, a more secure mechanism.

  (3) Further, by adjusting the respective diameters of the first pulley and the second pulley, a difference in torque applied to winding of the first inner cable and the second inner cable caused by a reduction ratio between the carrier and the ring gear. If they are the same, they can also serve as an equalizer.

  (4) The electric parking brake of the present invention is a space-saving system, and the assembly space can be reduced.

FIG. 1 is an exploded perspective view of the actuator of the present invention. FIG. 2 is a schematic view of the electric parking brake of the present invention. FIG. 3 is a partially enlarged view showing a transmission mechanism of the actuator of FIG. FIG. 4 is a schematic diagram showing how the stopper mechanism operates. FIG. 5 is a partially enlarged view showing a planetary gear reducer of the actuator of FIG. FIG. 6 is a cross-sectional view showing a conventional technique. FIG. 7 is a cross-sectional view showing a conventional technique.

  Next, an embodiment of an actuator and an electric parking brake according to the present invention will be described with reference to the drawings. First, an electric parking brake (hereinafter referred to as a brake device) of the present invention will be described with reference to FIG. The brake device 2 shown in FIG. 2 operates the left and right parking brakes 4 and 4 of the vehicle body by operating an operation button or an operation lever 3 (brake operation member) arranged in the vehicle. For example, when the operation button 3 is pressed, the actuator 1 of the present invention is operated, and the inner cables 5 and 6 are pulled, whereby the parking brakes 4 and 4 are operated. The operation button or operation lever 3 is connected to the actuator 1 by an electric wire or a communication cable 7.

  The parking brakes 4 and 4 are each provided with a conventionally known drum, and are braked by pulling the inner cables 5 and 6. The brake is provided with a return spring 4a and is always biased in a direction in which the brake is released, that is, in a direction in which the inner cables 5, 6 are pulled. On the other hand, when the brake is applied, the inner cables 5 and 6 are pulled and operated against the urging force.

  The inner cables 5 and 6 are conventionally known cables obtained by twisting a plurality of metal strands. Cable ends 5a and 6a are provided at the ends of the inner cables 5 and 6, respectively (see FIG. 1). The cable ends 5a and 6a are joined to the inner cables 5 and 6 by being formed by pouring metal with a mold or being fixed by caulking, respectively. The cable ends 5a and 6a are formed in a columnar shape, and the inner cables 5 and 6 extend from near the middle of the outer periphery of the columnar member.

  The operation lever 3 may also be used as a manual parking brake operation lever. In that case, the brake device 2 is used when a failure such as breakage occurs in the inner cable for manual brake operation, and the pulling operation of the operation lever 3 is detected by a detector such as a limit switch, and the detected signal Is transmitted to the actuator 1.

  Such a brake device 2 is used in an automobile, a special vehicle, or a construction machine.

  As shown in FIG. 1, the actuator 1 includes a motor 8 having an output gear 8a, a transmission mechanism 10 for transmitting rotation of the output gear 8a of the motor 8, and a tip of a drive shaft 12 of the transmission mechanism. It consists of the planetary gear speed reducer 20 arrange | positioned coaxially so that rotation is possible. The motor 8 is fixed to a frame (not shown) of the vehicle body. In the following description, the left and right sides of the drawings are referred to as front and rear for the sake of simplicity.

  As shown in FIG. 3, the transmission mechanism 10 includes a drive gear 11 to which the rotation of the output gear 8a of the motor is transmitted, a drive shaft 12 that is supported by the drive gear 11 near the rear end, and rotates together. The drive shaft 12 includes a stopper mechanism 13 (see FIG. 1) that prevents the rotational motion from being transmitted to the drive gear 11 side due to the rotation. Further, since the output gear 8a and the drive gear 11 are formed as helical gears, the meshing state starts and ends simultaneously over the entire tooth width. Therefore, power can be transmitted continuously, the generation of vibration and noise can be reduced, and the meshing rate increases, compared to spur gears. Greater torque transmission is possible. The output gear 8a may be a worm and the drive gear 11 may be a worm wheel that meshes with the worm. Further, the front end of the drive shaft 12 is a fitting portion 12b in which a horizontal surface is formed on a cylindrical part of the front end.

  The stopper mechanism 13 includes a spring-like brake spring 14 disposed on the outer periphery of the drive shaft 12 and a cylindrical brake drum 15 disposed on the outer periphery of the brake spring 14. The brake drum 15 is fixed to a housing (not shown) such as a motor.

  Both ends of the spring of the brake spring 14 are bent inside the spring (coiled portion). In the drawing, these spring ends are denoted by reference numerals 14a and 14a. The spring end portions 14a and 14a are arranged in the axial direction of the spring so as to be separated from each other by the height of the wound spring, but in the circumferential direction so as to be close to each other on one side. Arranged (inside the ends of both springs). A pushing member 11a of the drive gear 11 described later is disposed on the approaching side (see FIG. 4a).

  The drive gear 11 has a pushing member 11a projecting from the front in the radial direction toward the front on the front surface thereof. The pushing member 11 a is slightly curved along the circumference of the drive gear 11, and is formed in a substantially oval shape with the central portion curved as a whole. And the pushing member 11a is arrange | positioned between the said spring end parts 14a and 14a, and protrudes in the length which can push both front and back spring end parts 14a and 14a.

  Further, transmission members 12 a and 12 a are provided near the middle of the drive shaft 12. The transmission members 12 a and 12 a are arm members (transmission members) that protrude two radially outward of the drive shaft 12. These arm members 12a and 12a are formed by extending both arms in a V shape, and are outside the spring end portions 14a and 14a, that is, opposite to the pushing member 11a of the drive gear 11 (outside both spring end portions). (See FIG. 4b).

  FIG. 4 shows how the stopper mechanism 13 operates. FIG. 4a shows a state in which the drive gear 11 rotates. At this time, even if the pushing member 11a rotates in either the forward or reverse direction (see reference numerals L1 and R1), the spring ends 14a and 14a of the brake spring 14 are rotated. Abutting on the inner side, the spring diameter of the brake spring 14 is reduced (see symbol r1). On the other hand, as shown in FIG. 4b, the transmission member 12a of the drive shaft 12 abuts from the outside of the spring end portions 14a, 14a of the brake spring 14 and pushes the spring end portion 14a in the directions of L2 and R2. As a result, the spring diameter increases (see symbol r2). When the spring diameter increases, the brake spring 14 comes into contact with the inner peripheral surface of the brake drum 15 and the diameter cannot be increased any further. Therefore, the rotation of the drive shaft 12 is hindered.

  Next, the planetary gear speed reducer 20 will be described with reference to FIG. As shown in FIG. 5, the planetary gear speed reducer 20 is fitted in the vicinity of the front end of the drive shaft 12 and fixed at that portion, and is arranged around the sun gear 21 at equal intervals. One or more planetary gears 22 that mesh with the sun gear 21, and a ring gear 23 that is disposed so as to surround the planetary gears 22 and meshes with the planetary gears 22. The ring gear 23 is rotatably disposed on the outer periphery of the planetary gear 22. In the center of the sun gear, a fitting hole 21a formed in substantially the same cross-sectional shape as the fitting portion 12b (see FIG. 3) of the drive shaft 12 is formed.

  In the present embodiment, four planetary gears 22 are arranged at equal intervals in the ring gear 23, but one or more, preferably about three to four, may be arranged. A planetary gear hole 22a having a large diameter is formed at the center of the planetary gear 22, and cylindrical collars 24, 24 are fitted from the front and rear to be pivotally supported. The collar 24 includes a cylindrical portion 24 a that passes through the planetary gear hole 22 a, and a flange-like portion 24 b that extends outward from the lower end of the cylindrical portion 24 a and has substantially the same diameter as the planetary gear 22. . The bowl-shaped parts 24b and 24a are arranged so as to sandwich the planetary gear 22 from the front and rear. A collar hole 24c passes through the center of the collar 24 in the axial direction.

  A carrier 25 and a base 26 are disposed on the front and rear sides of the front and rear surfaces of the collar-shaped portion 24b of the collar 24, respectively. Four holes 25a and 26a are formed at equal intervals on the plate surfaces of the carrier 25 and the base 26, respectively. The holes 25a and 26a correspond to the collar hole 24c of the collar 24, and the shaft 27 passes therethrough. The shaft ends are supported by a carrier 25 and a base 26, respectively, and the collars 24 and 24 are rotatably supported.

  In the carrier 25, raised portions 25b, 25b, 25b, 25b are provided at positions between the holes 25a, 25a, 25a, 25a so as to protrude inward (rearward). Similarly, a raised portion 26b is provided on the base 26 so as to protrude inward (forward) between the holes 26a. The raised portions 25b and 26b are formed so as to have a thickness almost equal to the thickness of the ring gear 23 or the planetary gear 22 in the axial direction when the tip surfaces thereof are brought into contact with each other. A pin 25c extends rearward from the raised portion 25b of the carrier 25. On the other hand, a pin hole 26c into which the pin 25c can be inserted is formed in the raised portion 26b of the base 26. The carrier 25 and the base 26 are integrated with the pin 25c and the pin hole 26c with the planetary gear 22 interposed therebetween.

  A shaft hole may be formed at the rotation center of the carrier 25, and a shaft member or the like extending from the frame of the vehicle body may be inserted into the shaft hole. By doing so, the planetary speed reducer 20 can also be pivotally supported from the side opposite to the motor 8.

A first pulley 28 having a common center of rotation is pivotally supported on the front surface of the carrier 26. A cable locking portion 28a is formed on the outer periphery of the first pulley 28, and the cable end 5a of the first inner cable 5 is locked. The cable end 5 a is a cylindrical member, and is locked so that the central axis of the cylindrical member is substantially parallel to the axial direction of the actuator 1. Therefore, the first inner cable 5 is rotatable in a direction in which the first inner cable 5 approaches or separates from the outer periphery of the first pulley 28 with the axis of the cable end 5a as the rotation center. On the other hand, the second pulley 29 is arranged on the outer periphery so that the outer periphery of the ring gear 23 has an inner diameter. In the second pulley 29, the second inner cable 6 extends in a direction opposite to the first inner cable 5. In the figure, the cable end of the second inner cable 6 is denoted by reference numeral 6a, and the cable locking portion of the second pulley 29 is denoted by reference numeral 29a.
Since the second cable end 6a and the cable locking portion 29a have the same configuration as the first cable end 5a and the cable locking portion 28a, detailed description thereof will be omitted.

  Further, the diameters of the first pulley 28 and the second pulley 29 are adjusted so that the loads when the first inner cable 5 and the second inner cable 6 are wound are the same. If it does so, it can also serve as an equalizer and is space-saving.

1 Actuator of an electric brake device (actuator)
2 Electric brake device (brake device)
3 Operation lever (operation button)
4 Parking brake 5 First inner cable 5a Cable end 6 Second inner cable 6a Cable end 7 Communication cable 8 Motor 8a Output gear 10 Transmission mechanism 11 Drive gear 11a Pushing member 12 Drive shaft 12a Transmission member (arm member)
12b Fitting part 13 Stopper mechanism 14 Brake spring 14a Spring end part 15 Brake drum 20 Planetary gear speed reducer 21 Sun gear 21a Fitting hole 22 Planetary gear hole 22a Planetary gear hole 23 Ring gear 24 Collar 24a Cylindrical part 24b Saddle-shaped part 24c collar hole 25 carrier 25a shaft hole 25b raised portion 25c pin 26 base 26a shaft hole 26b raised portion 26c pin hole 27 shaft 28 first pulley 28a cable locking portion 29 second pulley 29a cable locking portion

Claims (4)

An electric parking brake actuator for operating left and right parking brakes by pulling and operating two inner cables,
A motor fixed to the vehicle body and rotating the drive shaft;
A sun gear fixed to the drive shaft;
One or more planetary gears arranged around and engaged with the sun gear;
A carrier that rotatably holds the planetary gear and that is rotatably provided concentrically with the sun gear;
A ring gear arranged outside the planetary gear and meshing with the planetary gear so as to be rotatable concentrically with the sun gear;
A first pulley that rotates with the carrier and winds the first inner cable in one direction;
A second pulley that rotates with the ring gear and winds the second inner cable in the other direction;
An actuator comprising a stopper mechanism that allows rotation of the drive shaft from the motor and prevents rotation from the gear side. The stopper mechanism is
A drive gear for transmitting rotation of the motor to a drive shaft;
A brake spring interposed between the drive gear and the drive shaft;
It is equipped with a cylindrical brake drum arranged around the brake spring,
The driving gear is formed with a pushing member that pushes the end of the brake spring in a direction to reduce the spring diameter,
An arm member is formed on the drive shaft to push the end of the brake spring in the direction of increasing the spring diameter,
When the drive shaft tries to rotate, the diameter of the brake spring increases, abuts against the inner surface of the brake drum, and its rotation is hindered,
The actuator according to claim 1, wherein when the drive gear attempts to rotate, the diameter of the brake spring decreases, and the brake spring does not contact the inner surface of the brake drum. The difference in rotational torque between the first inner cable and the second inner cable caused by the reduction ratio between the carrier and the ring gear is made equal by adjusting the diameters of the first pulley and the second pulley. 3. The electric actuator according to 2. A brake operating member;
The actuator according to any one of claims 1 to 3, which operates by operating the brake operation member;
A first inner cable and a second inner cable each having one end locked to the first pulley and the second pulley of the actuator;
An electric parking brake comprising left and right parking brakes to which the other end sides of the first inner cable and the second inner cable are respectively connected.

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