JP2007308085A - Electric parking brake device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To restrict turning around a screw shaft of an equalizer 31. <P>SOLUTION: The electric parking brake device is provided with a conversion mechanism B for converting rotation drive force of an electric motor 11 to linear drive force; a distribution mechanism C driven by the linear drive force and distributing the linear drive force to two output parts; cables 17, 19 connected to the respective output parts of the distribution mechanism C and transmitting the linear drive force to the respective parking brakes 13, 15; and an electric control device for controlling normal/reverse rotation drive of the electric motor 11. The conversion mechanism B is provided with a screw shaft 25 having a male screw 25a and rotated/driven by the electric motor 11 in the state that movement in an axial direction is restricted; a nut 27 thread-engaged with the male screw 25a of the screw shaft; and a guide plate 29 for guiding movement in the screw shaft direction of the nut 27 in the state that rotation around the screw shaft of the nut 27 is restricted. The equalizer 31 of the distribution mechanism C is provided with a slide engagement part interposed between the nut 27 and the guide plate 29 and slidably engaged with a guide flat surface 29a. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a parking brake device employed in a vehicle, and in particular, with an electric motor as an input source, the parking brake is braked by forward rotation of the electric motor, and the parking brake is released by reverse rotation of the electric motor. The present invention relates to an electric parking brake device configured to be in a state.

As one of the electric parking brake devices of this type, a conversion mechanism that converts the rotational driving force of an electric motor into a linear driving force, and the linear driving force that is driven by the linear driving force and distributes the linear driving force to two output units. A distribution mechanism, a pair of cables connected to each output portion of the distribution mechanism to transmit the linear driving force to each parking brake, and an electric control device for controlling forward / reverse rotation driving of the electric motor (For example, refer to Patent Document 1).
JP 2004-161063 A

  In the above-described conventional electric parking brake device, the conversion mechanism has a male screw on the outer periphery and is driven to rotate forward or backward by the electric motor in a state where movement in the axial direction is restricted. And a nut that is screwed onto the male screw of the screw shaft, and the distribution mechanism is swingably supported by the nut at a central portion and is movable in the screw shaft direction together with the nut. And an equalizer coupled to each of the cables at a tip portion of a pair of arm portions extending from the central portion toward the outer diameter of the screw shaft.

  By the way, in the above-described conventional electric parking brake device, the nut is formed in a cylindrical shape, and the screw shaft is configured to penetrate in the radial direction of the cylindrical nut. The nut axis is substantially orthogonal. Further, an equalizer is assembled to one end of the nut so as to be swingable around the axis of the nut. For this reason, in such a configuration, it is possible to regulate the rotation of the nut and the equalizer around the screw shaft by respectively connecting the pair of cables to the tip portions (output portions) of the pair of arm portions of the equalizer.

  However, in the configuration described above, when the screw shaft is driven to rotate in the forward or reverse direction by the electric motor, it is inevitable that the nut and the equalizer rotate to some extent around the screw shaft. As a result of this rotation, an excessive force is applied to the connecting portion of the equalizer and the cable, and the durability of the device may be impaired. Further, as in Patent Document 1, when a tension sensor is assembled to a cable, rotation around the screw axis of the equalizer may adversely affect durability and accuracy of the tension sensor.

  In order to solve the above-described problems, the present invention provides an electric parking brake device of the above-described type in which the conversion mechanism has a male screw on the outer periphery and is restricted from moving in the axial direction by the electric motor. A screw shaft that is driven to rotate in the forward direction or the reverse direction, a nut that is screwed to the male screw of the screw shaft, and rotation of the nut around the screw shaft in a state where the rotation of the nut around the screw shaft is limited. Guide means for guiding the movement, wherein the distribution mechanism is swingably supported by the nut at a central portion and is movable in the screw shaft direction together with the nut, and the diameter of the screw shaft from the central portion. An equalizer coupled to each of the cables at a distal end portion of a pair of arm portions extending outward, wherein the guide means has both coupling centers of the equalizer and the cables; A guide plane extending parallel to a plane including the axis of the screw shaft and extending in the screw axis direction, and the equalizer is interposed between the nut and the guide plane at a central portion thereof, and slides relative to the guide plane. A sliding engagement portion (preferably formed in a flat plate shape) that engages movably, the equalizer is restricted from rotating around a screw axis by the guide plane, and the nut is When the torque around the screw shaft is received in either the forward or reverse direction from the screw shaft, the nut engages with the equalizer and is restricted from rotating around the screw shaft.

  In this electric parking brake device, a sliding engagement portion that is slidably engaged with the guide plane is provided at the center portion of the equalizer, and when the equalizer moves in the screw shaft direction together with the nut, Is guided by the guide plane, and the rotation (unnecessary movement) around the screw shaft is restricted. This makes it possible to improve the durability of the device without excessive force acting on the connecting portion of the equalizer to each cable and the cable. When a tension sensor is assembled to the cable, it is possible to improve the accuracy and durability of the tension sensor.

  In implementing the present invention, when the nut receives torque around the screw shaft in either the forward or reverse direction from the screw shaft and engages with the equalizer, a force acting on the equalizer from the nut is applied to the equalizer. It is also possible to have a component force in a direction in which the equalizer is pressed against the guide plane within the slidable engagement region between the sliding engagement portion and the guide plane. In this case, no matter how large the force acting on the equalizer from the nut is, the equalizer does not tilt (oscillate) on the guide plane, and the above-described effects can be obtained stably.

  In carrying out the present invention, a support portion of the nut for swingably supporting the equalizer is formed in a spherical shape, and a supported portion of the equalizer that is swingably supported by the support portion of the nut is a cylinder. It can also be formed in a shape. In this case, it is possible to reduce the amount of torque transmitted from the nut support portion to the equalizer supported portion compared to the case where the nut support portion and the equalizer supported portion are both formed in a cylindrical shape. Thus, it is possible to make sure that the equalizer does not rotate around the screw axis due to the rotation of the nut around the screw axis.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an actuator of an electric parking brake device for an automobile embodying the present invention. This actuator decelerates and transmits a rotational driving force, which is an output of an electric motor 11, and the deceleration mechanism. A conversion mechanism B that converts the rotational driving force of the electric motor 11 transmitted via A into a linear driving force, and the linear driving force that is driven by the linear driving force converted by the conversion mechanism B and that outputs the linear driving force to two output units A distribution mechanism C that distributes the electric motor 11, a pair of cables 17 and 19 that are connected to the output portions of the distribution mechanism C and transmit linear driving force to the parking brakes 13 and 15, and forward and reverse rotation driving of the electric motor 11. An electric control unit ECU (see FIG. 2) for controlling is provided.

  The electric motor 11 is assembled together with the speed reduction mechanism A in a housing 21 (the cover is removed in FIG. 1) assembled to the vehicle body. Further, as shown in FIG. 2, the electric motor 11 is electrically connected to the electric control unit ECU, and its operation is controlled by the electric control unit ECU. Is driven to rotate in the forward direction, and the driver is driven to rotate in the reverse direction by operating the release switch SW2.

  The speed reduction mechanism A is configured by an appropriate number of speed reduction gear trains (not shown), each gear is incorporated in a casing 23 assembled to the housing 21, and an input gear is an output shaft ( The output gear is fixed to one end of the screw shaft 25 (the end protruding into the casing 23).

  The conversion mechanism B moves the nut 27 in the screw shaft direction in a state where the screw shaft 25, the nut 27 screwed to the screw shaft 25, and the rotation of the nut 27 around the screw shaft are restricted. A guide plate 29 is provided as a guide means for guiding, and the nut 27 is moved from the right position (release position) in FIG. 1 to the left position (braking position) in FIG. ) And the nut 27 is rotated from the left position (braking position) in FIG. 1 to the right position (FIG. 1). The screw shaft 25 is moved in the axial direction toward the release position.

  The distribution mechanism C distributes the linear driving force acting on the nut 27 equally to the two output parts, and is supported by the nut 27 at the center part 31a so as to be swingable. And an equalizer 31 that is coupled to the cables 17 and 19 at the tip portions (output portions) of a pair of arm portions 31b and 31c extending from the center portion 31a toward the outer diameter of the screw shaft 25. ing.

  The screw shaft 25 has a male screw 25a on the outer periphery, and is assembled to the housing 21 via a pair of bearings 26 and 28 so as to be rotatable and immovable in the axial direction. The screw shaft 25 is rotationally driven in the forward or reverse direction by the electric motor 11 via the speed reduction mechanism A in a state where movement in the axial direction is restricted by the bearings 26 and 28. .

  The nut 27 has a female screw 27a on the inner periphery, and is screwed to the male screw 25a of the screw shaft 25 by the female screw 27a. The nut 27 has a cross-sectional shape perpendicular to the axis O1 of the screw shaft 25, as shown in FIG. 3, the upper part is circular and the lower part is rectangular, and the lower rectangular corner parts 27b, It can be engaged with the back surface of the sliding engagement portion 31a1 of the central portion 31a of the equalizer 31 at 27c. Further, the nut 27 has a support portion 27d that supports the equalizer 31 in a swingable manner at one end portion in the screw shaft direction, and this support portion 27d is a ball as shown in FIGS. It is formed into a shape.

  The guide plate 29 is a resin plate, and is fixed on the bottom wall 21 a of the housing 21 as shown in FIGS. 1, 3, and 4, and is connected between the equalizer 31 and the cables 17 and 19. A guide plane 29a parallel to a plane including both the coupling centers O2, O3 and the axis O1 of the screw shaft 25 is provided. The guide plane 29a has a required width W2 (a width slightly wider than the width W1 of the sliding engagement portion 31a1 in the equalizer 31), extends in the screw axis direction, and the sliding engagement of the equalizer 31. The joint part 31a1 is slidably engaged.

  The equalizer 31 is slidably engaged with the guide flat surface 29a of the guide plate 29 at the lower surface of the sliding engagement portion 31a1 provided in the central portion 31a and interposed between the nut 27 and the guide plate 29. In addition, the slidable engagement region S between the lower surface of the sliding engagement portion 31a1 and the guide plane 29a has a length in the screw shaft direction L (see FIG. 4) and a width W1 (see FIG. 3). The equalizer 31 is supported by a support portion 27d of the nut 27 at a supported portion 31a2 provided at the center portion 31a so as to be swingable. The supported portion 31a2 is formed in a cylindrical shape.

  The equalizer 31 is connected to one end portion of the inner wire 17a in one cable 17 so as to be directly rotatable at the distal end portion of the arm portion 31b which is one output portion, and the arm portion which is the other output portion. 31c is connected to one end of the inner wire 19a of the other cable 19 via the tension sensor TS and the rod 33 so as to be rotatable.

  One cable 17 is composed of an inner wire 17a and an outer tube 17b that covers the outer periphery of the inner wire 17a other than both ends. The other end of the inner wire 17a is an operating portion of one parking brake 13. It is connected to. The other cable 19 is composed of an inner wire 19a and an outer tube 19b that covers the outer periphery of the inner wire 19a other than both ends, and the other end of the inner wire 19a is an operating portion of the other parking brake 15. It is connected to.

  As shown in FIG. 1, the tension sensor TS is interposed together with the rod 33 at a connection portion between the inner wire 19 a of the other cable 19 and the distal end portion of the arm portion 31 c which is the other output portion of the equalizer 31. The tension of the inner wire 19a in the other cable 19 is detected, and the detection signal (tension detection value) is input to the electric control unit ECU. As schematically shown in FIG. 2, the electric control unit ECU is electrically connected to the brake switch SW1, the release switch SW2, and the tension sensor TS, and is also electrically connected to the electric motor 11 and the indicator lamp IL. Has been.

  In this embodiment configured as described above, when both the cables 17 and 19 and the like are normal and the actuator operates normally, when the brake switch SW1 is operated, the electric motor 11 is driven to rotate in the forward direction. As the screw shaft 25 of the mechanism B is rotated forward, the nut 27 and the equalizer 31 are moved from the right position (release position) in FIG. 1 toward the left position (braking position) in FIG. Move in the direction. For this reason, the inner wires 17a and 19a of both the cables 17 and 19 are pulled, and both the parking brakes 13 and 15 are brought into a braking state. When the nut 27 and the equalizer 31 are moved to the left position (braking position) in FIG. 1, the tension detected by the tension sensor TS becomes a set value, the indicator lamp IL is lit, and the electric motor 11 is The rotational drive is stopped and the braking state of both parking brakes 13 and 15 is maintained.

  Further, when the release switch SW2 is operated when the actuator operates normally, the electric motor 11 is driven in reverse rotation, and the screw shaft 25 of the conversion mechanism B is rotated in reverse, whereby the nut 27 and the equalizer 31 are driven. Moves from the left position (braking position) in FIG. 1 to the right position (release position) in FIG. For this reason, the inner wires 17a and 19a of both cables 17 and 19 are loosened, and both parking brakes 13 and 15 are released. When the nut 27 and the equalizer 31 are moved to the right position (release position) in FIG. 1, the tension detected by the tension sensor TS becomes substantially zero, the indicator lamp IL is turned off, and the reverse of the electric motor 11 is performed. The rotational drive is stopped, and the release state of both parking brakes 13 and 15 is maintained.

  By the way, in the above-described embodiment, the guide plate 29 extends in the screw axis direction in parallel to a plane including both the coupling centers O2 and O3 of the equalizer 31 and the cables 17 and 19 and the axis O1 of the screw shaft 25. The equalizer 31 includes a sliding engagement portion 31a2 interposed between the nut 27 and the guide plane 29a and slidably engaged with the guide plane 29a. When the equalizer 31 is restricted from rotating around the screw shaft by the guide plane 29a and the nut 27 receives torque around the screw shaft in either the forward or reverse direction from the screw shaft 25, the rectangular corner of the nut 27 is The portion 27b or 27c is engaged with the back surface of the sliding engagement portion 31a1 of the equalizer 31, and the nut 27 is restricted from rotating around the screw shaft (see the phantom line in FIG. 3).

  For this reason, in this embodiment, an unreasonable force does not act on the coupling portions of the equalizer 31 to the cables 17 and 19, the inner wires 17a and 19a of the cables 17 and 19, the rod 33, the tension sensor TS, and the like. The durability of the device can be improved. Further, an excessive force does not act on the tension sensor TS provided between the inner wire 17a of the cable 17 and the rod 33, and the accuracy and durability of the tension sensor TS can be improved.

  In this embodiment, as is apparent from the configuration shown in FIGS. 3 and 4, when the nut 27 receives torque around the screw shaft 25 from the screw shaft 25 and engages the equalizer 31, the nut 27 The amount of force acting on the equalizer 31 in the direction in which the equalizer 31 is pressed against the guide plane 29a within the slidable engagement region S between the sliding engagement portion 31a2 of the equalizer 31 and the guide plane 29a of the guide plate 29. It is configured to have power. For this reason, no matter how large the force acting on the equalizer 31 from the nut 27 is, the equalizer 31 does not tilt (oscillate) on the guide plane 29a, and the above-described operational effects can be obtained stably.

  The reaction force of the above-described component force is a vertical drag acting on the nut 27 from the guide plane 29a of the guide plate 20 through the sliding engagement portion 31a2 of the equalizer 31, and the point of application of this vertical drag is described above. Within the engagement region S, the sliding engagement portion 31a2 of the equalizer 31 and the slidable engagement region S of the guide flat surface 29a of the guide plate 29 are also present on the outer side in the width direction of the applied force point. Further, when the rectangular corner portion 27b or 27c of the nut 27 is engaged with the back surface of the sliding engagement portion 31a1 of the equalizer 31, the acting force received by the nut 27 from the screw shaft 25 in the direction opposite to the above-described normal force and the above-described force. When the couple of the vertical drag acts on the nut 27, the rotation of the nut 27 around the screw shaft is restricted.

  In this embodiment, the support portion 27d of the nut 27 that supports the equalizer 31 so as to be swingable is formed in a spherical shape, and the supported portion of the equalizer 31 that is swingably supported by the support portion 27d of the nut 27 is supported. The part 31a2 is formed in a cylindrical shape. For this reason, compared with the case where both the support part 27d of the nut 27 and the supported part 31a2 of the equalizer 31 are formed in a cylindrical shape, the amount of torque transmitted from the support part 27d of the nut 27 to the supported part 31a2 of the equalizer 31 The rotation of the nut 27 around the screw axis can ensure that the equalizer 31 does not rotate around the screw axis.

It is a top view which shows one Embodiment of the electric parking brake apparatus by this invention. It is a block diagram which shows the relationship between the electric motor and tension sensor which are shown in FIG. 1, and the electric control apparatus, the brake switch, the release switch, and the indicator lamp which are not shown in FIG. FIG. 3 is a cross-sectional view taken along line 3-3 in FIG. 1. It is a principal part vertical side view which shows the relationship between the screw shaft shown in FIG. 3, a nut, an equalizer, and a guide plate.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Electric motor, 13, 15 ... Parking brake, 17, 19 ... Pair of cables, 21 ... Housing, 23 ... Casing, 25 ... Screw shaft, 25a ... Male screw, 27 ... Nut, 27a ... Female screw, 27b, 27c ... Rectangular Corner portion, 27d ... support portion, 29 ... guide plate, 29a ... guide plane, 31 ... equalizer, 31a ... center portion, 31a1 ... sliding engagement portion, 31a2 ... supported portion, 31b, 31c ... arm portion, 33 ... Rod, ECU ... Electric control device, A ... Deceleration mechanism, B ... Conversion mechanism, C ... Distribution mechanism, TS ... Tension sensor, SW1 ... Braking switch, SW2 ... Release switch, IL ... Indicator lamp, O1 ... Screw shaft Center, O2, O3 ... coupling center between equalizer and cable, S ... slidable engagement between the sliding engagement portion of the equalizer and the guide plane of the guide plate Area.

Claims (4)

A conversion mechanism that converts the rotational driving force of the electric motor into a linear driving force, a distribution mechanism that is driven by the linear driving force and distributes the linear driving force to two output units, and each output unit of the distribution mechanism In an electric parking brake device comprising a pair of cables connected to transmit the linear driving force to each parking brake, and an electric control device for controlling forward / reverse rotation driving of the electric motor,
The conversion mechanism has a male screw on the outer periphery and is rotationally driven in the forward or reverse direction by the electric motor in a state where movement in the axial direction is restricted, and is screwed onto the male screw of the screw shaft And a guide means for guiding the movement of the nut in the screw shaft direction in a state where rotation around the screw shaft of the nut is limited,
The distribution mechanism is swingably supported by the nut at a central portion, and is movable in the screw shaft direction together with the nut, and extends from the central portion toward the outer diameter of the screw shaft. Equipped with an equalizer coupled to each cable at the tip of the part,
The guide means includes a guide plane extending in the screw axis direction parallel to a plane including both coupling centers of the equalizer and the cables and the axis of the screw shaft, and the equalizer has the nut and the central portion thereof. A sliding engagement portion interposed between the guide planes and slidably engaged with the guide plane; the equalizer is restricted from rotating about a screw axis by the guide plane; The electric parking brake characterized in that when the nut receives torque around the screw shaft in either the forward or reverse direction from the screw shaft, the nut engages with the equalizer and is restricted from rotating around the screw shaft. apparatus.   2. The electric parking brake device according to claim 1, wherein the nut acts on the equalizer from the nut when the nut receives torque around the screw shaft in either the forward or reverse direction from the screw shaft and engages the equalizer. Has a component force in a direction in which the equalizer is pressed against the guide plane within the slidable engagement region between the sliding engagement portion of the equalizer and the guide plane. Parking brake device.   3. The electric parking brake device according to claim 1, wherein the sliding engagement portion of the equalizer is formed in a flat plate shape. 4. The electric parking brake device according to claim 1, wherein a support portion of the nut that swingably supports the equalizer is formed in a spherical shape, and is supported swingably by the support portion of the nut. The electric parking brake device, wherein the supported portion of the equalizer is formed in a cylindrical shape.

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