JP2004138183A - Actuator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an actuator capable of shutting off the transmission of the power from a driven member to an electric motor and embodied in a compact construction. <P>SOLUTION: Because the axis of the output shaft 2a of the motor 2 and the axis of a rotary shaft 3 are held in a bevel relationship, i.e., out of alignment, the motor 2 is not positioned in series to the rotary shaft 3 but is positioned laterally, and the easiness in mounting on a vehicle is enhanced by suppressing the overall length of the actuator. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an actuator, for example, a power window of an automobile, a wire winding mechanism of an electric parking brake device, a caliper pushing mechanism of an electric disc brake device, a cam phase conversion mechanism in a variable valve timing device of an engine, and a belt CVT pulley driving mechanism. The present invention relates to an actuator using an electric motor as a power source, which can be used for lifting devices for nursing care equipment, other industrial winches, hoists, cranes, various positioning devices, and the like.
[0002]
[Prior art]
For example, an actuator such as an electric parking brake driving device that reduces the burden on a driver by performing the operation of a parking brake of a vehicle using the power of an electric motor is known. As such an actuator, an electric motor rotates a screw shaft and pulls a connected Bowden wire by moving a nut screwed thereto to operate a parking brake or return a Bowden wire to release a parking brake. It has been proposed (see Patent Document 1).
[Patent Document 1]
JP-A-2002-220045
[0003]
[Problems to be solved by the invention]
By the way, in the actuator disclosed in the above-mentioned publication, an electromagnetic brake is used to fix the screw shaft when not operating. That is, by exciting the coil of the electromagnetic brake, the rotor connected to the screw shaft by the armature and the plate is sandwiched, and the screw shaft is fixed, so that unwanted operation or release of the brake is prevented. However, in such an actuator, it is necessary to always energize the electromagnetic brake when the brake is released or the brake is operating, and there is a problem that energy cannot be saved.
[0004]
On the other hand, Patent Document 2 below includes a power transmission device that transmits power from an electric motor to a wire connected to a brake device, but does not transmit power from the brake device to the electric motor. There is disclosed an actuator which does not need to be energized to fix the position of the wire when the brake is released or the brake is operated, thereby saving energy.
[Patent Document 2]
Japanese Patent Application No. 2002-124051
[0005]
However, the actuator disclosed in Patent Document 2 has a high cost because the electric motor is designed exclusively and has a hollow rotating shaft and is incorporated in the actuator. Therefore, it is conceivable to use a general-purpose electric motor to reduce the cost. However, when a general-purpose electric motor is arranged in series with the actuator, there is a problem that the overall length of the actuator is increased and the mountability on a vehicle is deteriorated.
[0006]
The present invention has been made in view of the problems of the related art, and an object of the present invention is to provide an actuator that can block transmission of power from a driven member to an electric motor and has a compact configuration. I do.
[0007]
[Means for Solving the Problems]
The actuator of the present invention
An actuator for driving a driven member,
A housing,
An electric motor attached to the housing;
A power transmission mechanism for transmitting the power of the electric motor to the driven member,
The power transmission mechanism,
Outer ring,
A rotation drive unit connected to the electric motor so as to transmit power,
A rotation driven unit that is rotationally displaced by receiving a rotational force from the rotation driving unit,
A conversion mechanism for converting the rotational movement of the rotary driven part into an axial movement of a moving member coupled to the driven member so that power can be transmitted;
A lock member disposed between the outer ring and the rotation driven portion, and
When a rotational force is input to the rotation driving unit and the rotation driven unit is to be rotated, the lock member is guided to a first position where frictional force is reduced with respect to the outer ring and the rotation driven unit. By doing so, transmission of rotational force from the rotation driving unit to the rotation driven unit is allowed, and a rotation force is input to the rotation driven unit so as to rotate the rotation driving unit in the first direction. When the lock member is guided to the second position where the frictional force is increased with respect to the outer ring and the rotation driven portion, the rotation from the rotation driven portion to the rotation drive portion is fixed. And at least in a state where the driven member is driven, the rotation driven portion is configured to receive a force from the driven member so as to rotate in the first direction,
The axis of the output shaft of the electric motor is maintained in a state of being inconsistent with the axis of the rotary drive unit.
[0008]
[Action]
The actuator of the present invention is an actuator that drives a driven member, and includes a housing, an electric motor attached to the housing, and a power transmission mechanism that transmits power of the electric motor to the driven member, The power transmission mechanism includes an outer ring, a rotation drive unit connected to the electric motor so as to be able to transmit power, a rotation driven unit that receives a rotational force from the rotation drive unit, and is rotationally displaced; A conversion mechanism configured to convert a rotational movement into an axial movement of a moving member that is capable of transmitting power to the driven member, and a lock member disposed between the outer ring and the rotary driven part. In addition, when a rotational force is input to the rotation driving unit and the rotation driven unit is to be rotated, the lock member has friction with the outer ring and the rotation driven unit. Is guided to the first position where the rotational drive is reduced, thereby allowing transmission of rotational force from the rotational drive to the rotationally driven part, and rotational force being input to the rotationally driven part so that the rotational drive is controlled. When trying to rotate in the first direction, the lock member is guided to the second position where the frictional force is higher with respect to the outer race and the rotation driven portion, so that the lock member is rotated from the rotation driven portion. A configuration in which the rotation to the rotation drive unit is fixed, and a force is received from the driven member so that the rotation driven unit rotates in the first direction at least when the driven member is driven. Since power transmission from the electric motor to the driven member (for example, a parking brake device) is allowed while power transmission from the driven member to the electric motor can be prevented, the electric motor Capacity Can fence, saving power is also reduced. Further, at least in a state where the driven member is driven, the lock member is configured to be urged to the second position by receiving a force from the driven member. The configuration of the power transmission mechanism can be simplified, and the cost can be reduced. Furthermore, since the axis of the output shaft of the electric motor is maintained in a state of being inconsistent with the axis of the rotary drive unit, the axis of the output shaft of the electric motor is arranged, for example, to intersect with the axis of the rotary drive unit. Then, even if a general-purpose electric motor is used, a more compact configuration is provided. Here, "the axes are kept in a mismatched state" means that the axes cross each other, are parallel, or have a helical relationship.
[0009]
Further, the “first position where the frictional force is low” and the “second position where the frictional force is high” are defined as a position of the second position which is higher than the first position when the lock member is displaced. Means the relative relationship that the frictional force between the lock member, the outer ring, and the rotation driven portion increases. For example, in an embodiment described later, the first position is The position on the cam surface inclined in one direction is near the rotation axis, and the second position is a position distant from the rotation axis on the cam surface.
[0010]
Further, it is preferable that power be transmitted to the output shaft of the electric motor and the rotation drive unit via a pair of gears that mesh with each other while the axes are maintained in a state of being inconsistent. .
[0011]
Further, it is preferable that a power transmission unit that receives supply of power from other than the electric motor is provided in the rotation drive unit.
[0012]
Further, when the conversion mechanism includes a screw shaft and a ball screw mechanism having a nut connected to the rotation driven portion, the rotation displacement of the rotation driven portion is efficiently converted into the axial displacement of the screw shaft. This is preferable because conversion can be performed and the configuration of the actuator can be reduced in size.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view of an actuator according to a first embodiment applied to an electric parking brake driving device. FIG. 2 is a view of the configuration of FIG. 1 taken along line II-II and viewed in the direction of the arrow, and FIG. 3 is a view of the configuration of FIG. 1 taken along line III-III and viewed in the direction of the arrow. FIG. 4 shows the operation of the clutch device.
[0014]
First, in FIG. 2, the electric motor 2 is attached to the motor-side housing 1A in such a manner that the shoulder 2b is spigot-fitted. The output shaft 2a of the electric motor is aligned with one end (right end in FIG. 2) of the worm shaft 22 supported on the motor-side housing 1A by bearings 20 and 21, and is connected to a D-plane or press-fitted. In such a manner as to rotate integrally. A worm gear 22a is formed at the center of the worm shaft 22. The outer ring of the bearing 20 is preloaded by a disc spring 24 on the motor-side housing 1A.
[0015]
In FIG. 1, the housing 1 is composed of a motor side housing 1A and a clutch housing 1B integrated by being connected by bolts 1C. The rotating shaft 3 arranged in the motor side housing 1A is hollow, and the left end thereof is rotatably supported by a bearing 9A whose outer ring is preloaded by a disc spring 25 in FIG. A worm wheel 3d is formed at the center of the rotating shaft 3 and meshes with a worm gear 22a of the worm shaft 22. A worm mechanism is constituted by the worm gear 22a and the worm wheel 3d. In the present embodiment, it is preferable that the lead angle is relatively large and the efficiency is high.
[0016]
Further, the rotary shaft 3 has a large-diameter portion 3a rotatably supported by a bearing 9B with respect to the motor-side housing 1A on the right end side of FIG. And six) claw portions 3b. The outer ring of the bearing 9B is fitted on both the inner peripheral surface of the motor-side housing 1A and the inner peripheral surface of the clutch housing 1B, whereby the clutch housing 1B and the electric motor 2 are aligned. In this way, by fitting the outer ring of the bearing 9B to the inner peripheral surface of the motor side housing 1A and the inner peripheral surface of the clutch housing 1B, for example, during assembly or inspection, the clutch from the motor side housing 1A is disengaged. Even when the housing 1B is separated, the rotating shaft 3 is supported by the two bearings 9A and 9B, which is convenient for handling.
[0017]
The clutch housing 1B has a shape such as connecting the large cylindrical portion 1a and the small cylindrical portion 1b. An outer ring 5 is attached to the inner peripheral surface of the large cylindrical portion 1a. Inside the outer ring 5 in the radial direction, between the adjacent claw portions 3b, rollers (three in this example) as lock members and keys 7 (three in this example may be provided) are locking members. It is arranged to be. The outer race 5 has a flange portion 5g projecting inward in the radial direction at the right end in FIG. 1, and the axial movement of the roller 6 is prevented by the flange portion 5g.
[0018]
The roller 6 is capable of rolling on the outer peripheral surface of a cylindrical rotary driven member 4 rotatably supported via a bearing 8 with respect to the large cylindrical portion 1a of the clutch housing 1B. The shape of the outer peripheral surface of the rotation driven member 4 will be described later with reference to FIG. A nut 10 is fitted on the inner peripheral surface of the rotation driven member 4, and is relatively rotated by a headless screw 4 </ b> A having a radially penetrating screw with the rotation driven member 4 and projecting a tip from the inner peripheral surface. It is improperly mounted. A screw shaft 11 penetrates through the nut 10. The screw shaft 11 further extends to the inside of the rotary shaft 3, thereby providing a compact configuration in the axial direction.
[0019]
A screw groove 11a (only a part is shown) is formed on the outer peripheral surface of the left half portion of the screw shaft 11 in FIG. 1, while a screw groove is formed on the inner peripheral surface of the nut 10 so as to face the screw groove 11a. A number of balls 12 are rotatably arranged in a spiral space formed by thread grooves 10a and 11a. Although not shown, a passage is provided for returning the ball 12 from one end of the nut 10 to the other end during operation. The nut 10, the screw shaft 11, and the ball 12 form a ball screw mechanism.
[0020]
The right half of the screw shaft 11 in FIG. 1 is a round shaft portion 11b, and a cylindrical moving case 13 is disposed at the tip thereof. The moving case 13 covering the round shaft portion 11b regardless of the axial position of the screw shaft 11 includes a large cylinder 13a, a short small cylinder 13b coaxially arranged on the right end side of the large cylinder 13a in FIG. 1, and a large cylinder 13a. And a flange portion 13c for connecting the small cylinder 13b. A key groove 13d is provided on the inner peripheral surface of the small cylinder 13b, and the small cylinder 13b is non-rotatably attached to the right end of the screw shaft 11 in FIG. The ring 15 is prevented from coming off from the screw shaft 11. One end of a wire (not shown) is connected to an end surface of the flange portion 13c, and the other end of the wire is connected to a parking brake device (brake device) not shown. By moving the wire to the left in FIG. 1, the brake device is operated to apply a braking force to wheels (not shown) by moving to the left in FIG. 1, and by moving to the right in FIG. 1, the braking of the brake device is released. It has become. It is assumed that the wire is constantly biased rightward in FIG. 1 by a spring or the like (not shown).
[0021]
The clutch housing 1B has a straight groove 1e extending from the right end side in FIG. On the other hand, the moving case 13 has a pin 17 planted near the left end of the large cylinder 13a in FIG. The inner end of the pin 17 is engaged with the straight groove 1e. Therefore, the movable case 13 cannot rotate relative to the clutch housing 1B, but can move relatively in the axial direction. A partition wall 1c that supports the round shaft portion 11b of the screw shaft 11 via a bush 1d is formed in the center inner periphery of the small cylindrical portion 1b of the clutch housing 1B, and is adjacent to the partition wall (to the right in FIG. 1). A packing 18 is disposed, and functions to seal the space between the outer peripheral surface of the round shaft portion 11b and the inner peripheral surface of the small cylindrical portion 1b, thereby preventing foreign matter from entering.
[0022]
The power transmission mechanism 50 includes the rotating shaft 3 as a rotation driving unit, the rotation driven member 4 as a rotation driven unit, the outer ring 5, and ball screw mechanisms (10, 11, 12) as conversion mechanisms. You.
[0023]
The detailed configuration of the power transmission mechanism 50 will be described. In FIG. 3, the rotation driven member 4 has three key grooves 4c in this example and three cam surfaces 4d in this example formed at equal intervals and alternately on its outer peripheral surface. The cam surface 4d has a slope shape inclined in one direction away from the rotation axis (axis) as going clockwise in FIG.
[0024]
The distance between the key 7 and the claw portions 3b on both sides of the key 7 is a, and the roller 6 bites between the outer ring 5 and the rotary driven member 4 (second position). Assuming that the distance from the claw 3b is b and the distance from the claw 3b on the clockwise side is c, a relationship of b>a> c is established.
[0025]
The operation of the present embodiment will be further described with reference to FIGS. First, it is assumed that the rollers 6 are in a locked state. In FIG. 1, when a driver performs a predetermined operation to operate a parking brake, electric power is supplied from a power source (not shown) to the electric motor 2, and an output shaft 2a of the electric motor 2 is transmitted through a worm gear 22a and a worm wheel 3d. Is transmitted, whereby the rotating shaft 3 rotates relative to the rotating driven member 4. At this time, in FIG. 4A, if the claw 3b rotates in the direction of arrow A, the end face of the claw 3b adjacent to the roller 6 tries to contact the roller 6, but the claw 3b The relationship between the gap between the roller 6 and the key 7 is as described above (b>a> c). Therefore, before the roller 6 is moved to the second position (the position indicated by the dotted line in FIG. 3), The end face of the claw 3b adjacent to the key 7 presses the key 7, whereby the rotary shaft 3 and the rotary driven member 4 rotate integrally. When the nut 10 rotates together with the rotation driven body 4, the screw shaft 11 non-rotatably supported by the clutch housing 1B via the moving case 13 forms a spiral space (transfer) formed by the screw grooves 10a, 11a. The ball 12 is pushed axially in a low-friction state by rolling balls 12, i.e. the rotational displacement is converted into an axial displacement. Since the moving case 13 moves together with the axial movement of the screw shaft 11, the power is transmitted to a brake device (not shown) via a wire (not shown) to apply a braking force to wheels (not shown). Has become. The ball 12 that has reached the one end by transferring the transfer path is returned to the other end of the transfer path via a circulation path (not shown).
[0026]
On the other hand, after the electric motor 2 stops, a constant urging force (or a braking reaction force may be applied) by a spring (not shown) acts on the wire, so that the moving case 13 and the screw shaft 11 urged by the spring are moved. The axial displacement is converted into a rotational displacement of the rotary driven body 4 via the nut 10, and thus the rotary driven body 4 tends to rotate relative to the rotary shaft 3. In this case, in FIG. 4C, since the cam surface 4d is about to rotate in the direction of arrow C, the roller 6 receives a force from the stationary outer race 5 and is far from the upper portion of the cam surface 4d, that is, the rotation axis. Pressed (biased) toward the side (second position). Thereby, the roller 6 stretches between the outer ring 5 and the cam surface 4d to apply a frictional force. This is called a locked state. In the locked state, the rotation of the rotary driven body 4 is prevented, so that the braking force of the brake device (not shown) can be maintained even if the biasing force of the wire is relatively large.
[0027]
Furthermore, when the driver performs a predetermined operation to release the parking brake in order to start the vehicle, electric power of the opposite polarity is supplied from a power supply (not shown) to the electric motor 2, and the electric power is supplied to the electric motor 2 via the worm gear 22a and the worm wheel 3d. The rotational force (power) of the output shaft 2a of the electric motor 2 is transmitted in a direction opposite to the above, whereby the rotating shaft 3 rotates relatively to the rotating driven body 4. At this time, in FIG. 4B, when the claw portion 3b rotates in the direction of arrow B, the end face of the claw portion 3b adjacent to the key 7 comes into contact with the key 7 and rotates the rotary driven body 4 in the same direction. . Therefore, since the end face of the claw portion 3b adjacent to the roller 6 presses the roller 6 toward the lower part of the cam surface 4d, that is, the side (first position) near the rotation axis, the roller 6 does not bite. The rotation shaft 3 and the rotation driven body 4 rotate integrally.
[0028]
According to the present embodiment, as shown in FIGS. 1 and 2, the axis of the output shaft 2 a of the electric motor 2 and the axis of the rotating shaft 3 are maintained in a helical relationship, that is, in an inconsistent state. Therefore, the electric motor 2 is not arranged in series with the rotary shaft 3 but arranged on the side thereof, and the overall length of the actuator is suppressed, so that the mountability on the vehicle is improved.
[0029]
FIG. 5 is a sectional view of the actuator according to the second embodiment. In FIG. 5, the left end of the rotating shaft 3 is exposed outward through an opening 1g formed in the motor-side housing 1A, and has a tool engaging portion 3f (having a spline shape or a D cross-sectional shape). And preferred). The space between the rotating shaft 3 and the motor-side housing 1A is sealed by a seal 30. Other configurations are the same as those of the embodiment shown in FIGS.
[0030]
According to the present embodiment, even when the battery cannot be supplied to the electric motor 2 when the battery is removed from the vehicle due to repair or the like, for example, the tool (not shown) is attached to the tool engaging portion 3f of the rotating shaft 3. ) Can be engaged and rotated by the operator's hand, so that the rotating shaft 3 can be arbitrarily rotated, whereby the operation or release of the brake device can be performed manually. That is, the tool engagement portion constitutes a power transmission unit that receives supply of power from other than the electric motor.
[0031]
When the actuator according to the present embodiment is applied to, for example, a seat adjustment mechanism, a dial (not shown) that can be turned by a driver's hand is connected to the tool engagement portion 3f. It is also conceivable that the movable case 13 is expanded and contracted in accordance with the rotation of the dial, and when a load is applied, the position of the seat is adjusted by assisting with the power from the electric motor 2.
[0032]
As described above, the present invention has been described with reference to the embodiments. However, the present invention should not be construed as being limited to the above embodiments, and it is needless to say that modifications and improvements can be made as appropriate. For example, a pair of gears that connect the output shaft of the electric motor and the rotary drive unit and that mesh with each other while the axes are maintained in a non-coincidence state include the worm gear 22a and the worm wheel 3d as well as the worm gear. Gears, spur gears and the like are conceivable.
[0033]
【The invention's effect】
The actuator of the present invention is an actuator that drives a driven member, and includes a housing, an electric motor attached to the housing, and a power transmission mechanism that transmits power of the electric motor to the driven member, The power transmission mechanism includes an outer ring, a rotation drive unit connected to the electric motor so as to be able to transmit power, a rotation driven unit that receives a rotational force from the rotation drive unit, and is rotationally displaced; A conversion mechanism configured to convert a rotational movement into an axial movement of a moving member that is capable of transmitting power to the driven member, and a lock member disposed between the outer ring and the rotary driven part. In addition, when a rotational force is input to the rotation driving unit and the rotation driven unit is to be rotated, the lock member has friction with the outer ring and the rotation driven unit. Is guided to the first position where the rotational drive is reduced, thereby allowing transmission of rotational force from the rotational drive to the rotationally driven part, and rotational force being input to the rotationally driven part so that the rotational drive is controlled. When trying to rotate in the first direction, the lock member is guided to the second position where the frictional force is higher with respect to the outer race and the rotation driven portion, so that the lock member is rotated from the rotation driven portion. A configuration in which the rotation to the rotation drive unit is fixed, and a force is received from the driven member so that the rotation driven unit rotates in the first direction at least when the driven member is driven. Since power transmission from the electric motor to the driven member (for example, a parking brake device) is allowed while power transmission from the driven member to the electric motor can be prevented, the electric motor Capacity Can fence, saving power is also reduced. Further, at least in a state where the driven member is driven, the lock member is configured to be urged to the second position by receiving a force from the driven member. The configuration of the power transmission mechanism can be simplified, and the cost can be reduced. Further, since the axis of the output shaft of the electric motor is maintained in a state of being inconsistent with the axis of the rotary drive unit, the axis of the output shaft of the electric motor is arranged, for example, to intersect with the axis of the rotary drive unit. Then, even if a general-purpose electric motor is used, a more compact configuration is provided.
[Brief description of the drawings]
FIG. 1 is a sectional view of an actuator according to a first embodiment.
FIG. 2 is a view of the configuration of FIG. 1 cut along a line II-II and viewed in a direction of an arrow.
FIG. 3 is a view of the configuration of FIG. 1 cut along a line III-III and viewed in a direction of an arrow.
FIG. 4 is a diagram showing the operation of the clutch device.
FIG. 5 is a sectional view of an actuator according to a second embodiment.
[Explanation of symbols]
1A Motor side housing 1B Clutch housing 2 Electric motor 3 Rotating shaft 3d Worm wheel 4 Rotating driven member 5 Outer ring 6 Roller 10 Nut 11 Screw shaft 13 Moving case 22a Worm gear

Claims (4)

An actuator for driving a driven member,
A housing,
An electric motor attached to the housing;
A power transmission mechanism for transmitting the power of the electric motor to the driven member,
The power transmission mechanism,
Outer ring,
A rotation drive unit connected to the electric motor so as to transmit power,
A rotation driven unit that is rotationally displaced by receiving a rotational force from the rotation driving unit,
A conversion mechanism for converting the rotational movement of the rotary driven part into an axial movement of a moving member coupled to the driven member so that power can be transmitted;
A lock member disposed between the outer ring and the rotation driven portion, and
When a rotational force is input to the rotation driving unit and the rotation driven unit is to be rotated, the lock member is guided to a first position where frictional force is reduced with respect to the outer ring and the rotation driven unit. By doing so, transmission of rotational force from the rotation driving unit to the rotation driven unit is allowed, and a rotation force is input to the rotation driven unit so as to rotate the rotation driving unit in the first direction. When the lock member is guided to the second position where the frictional force is increased with respect to the outer ring and the rotation driven portion, the rotation from the rotation driven portion to the rotation drive portion is fixed. And at least in a state where the driven member is driven, the rotation driven portion is configured to receive a force from the driven member so as to rotate in the first direction,
An actuator, wherein an axis of an output shaft of the electric motor is maintained in a state of being inconsistent with an axis of the rotation drive unit. The output shaft of the electric motor and the rotation drive unit are configured so that power is transmitted through a pair of gears meshing with each other in a state where the axes are maintained in a mismatched state. The actuator of claim 1, wherein The actuator according to claim 1, wherein the rotation drive unit includes a power transmission unit that receives supply of power from a unit other than the electric motor. The actuator according to claim 1, wherein the conversion mechanism includes a ball screw mechanism having a screw shaft and a nut connected to the rotation driven part.

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