JP2011172379A - Electric linear motion actuator and electric braking device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric linear motion actuator capable of smoothly guiding the linear movement of an output member performing linear movement even if a lateral moment acts to the output member, and shortening the length in an axial direction of the entire electric linear motion actuator. <P>SOLUTION: The movement of a carrier 6 for supporting a planet roller 7 is regulated in an axial direction, an outer ring member 5 internally fitted so as to be slidable in the axial direction to the inner diameter surface of a cylindrical portion 1a of a housing 1 is whirl-stopped by a key 25 to a driven object to be coupled, the outer ring member 5 is used as an output member for linear movement, a rotating shaft 4 is arranged in parallel to the rotor shaft 2a of the electric motor 2, and the rotation is transmitted from the rotor shaft 2a to the rotating shaft 4. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an electric linear motion actuator that linearly drives a driven object by converting the rotational motion of an electric motor into linear motion, and an electric brake that presses a brake member against the braked member using the electric linear motion actuator Relates to the device.

  Many of the electric linear actuators that convert the rotational motion of the electric motor into linear motion to drive the driven object linearly employ a ball screw mechanism or a ball ramp mechanism as the motion conversion mechanism. In many cases, a gear reduction mechanism such as a planetary gear reduction mechanism is incorporated so that a large linear driving force can be obtained (see, for example, Patent Document 1).

  The ball screw mechanism and the ball ramp mechanism employed in the electric linear actuator described above have a certain degree of boosting function by a motion conversion mechanism along the lead screw thread and the inclined cam surface. It is not possible to secure a large boosting function that is necessary for the above. For this reason, in the electric linear actuator that employs these motion conversion mechanisms, a separate reduction mechanism such as a planetary gear reduction mechanism is incorporated to increase the driving force. In this way, a separate reduction mechanism is incorporated. Impedes the compact design of the electric linear actuator.

  For such problems, the present inventors can ensure a large boosting function without incorporating a separate speed reduction mechanism, and as an electric linear actuator suitable for an electric brake device that requires a large thrust, A plurality of planetary rollers rotatably supported by the carrier are interposed between a rotating shaft to which rotation is transmitted from the electric motor and an outer ring member fixed to the inner diameter surface of the housing on the outer diameter side of the rotating shaft. The planetary roller revolves while rotating around the rotation shaft as the rotation shaft rotates, and a spiral protrusion is provided on the inner diameter surface of the outer ring member, and the spiral protrusion is provided on the outer diameter surface of the planetary roller. A circumferential groove into which the spiral ridges are fitted at the same pitch as or a spiral groove into which the spiral ridges are fitted at the same pitch as the spiral ridges with different lead angles and revolves while rotating around the rotation axis. Support planetary roller First, a mechanism in which the carrier is relatively moved in the axial direction, the rotational motion of the rotating shaft is converted into the linear motion of the carrier, and the linear drive member connected to the carrier or the carrier is used as the output member for linearly driving the driven object. It has been proposed (see Patent Documents 2 and 3).

  On the other hand, many hydraulic brake devices have been adopted, but in recent years, with the introduction of advanced brake control such as ABS (Antilock Brake System), these controls are performed without a complicated hydraulic circuit. Electric brake devices that can do this are attracting attention. The electric brake device operates an electric motor in response to a brake pedal depression signal or the like, and incorporates an electric linear actuator as described above into a caliper body to press a brake member against a member to be braked (for example, a patent) Reference 4).

JP-A-6-327190 JP 2007-32717 A JP 2007-37305 A JP 2003-343620 A

  Patent Documents 2 and 3 describe an electric linear actuator that uses a linear drive member connected to the carrier or a linear drive member as an output member that linearly moves, and does not incorporate a separate speed reduction mechanism. However, since the linearly moving carrier and the linear drive member have a relatively short length in the axial direction, for example, in an electric brake device using this electric linear actuator, a brake to be driven is used. A tangential force acts on the member from the braked member, but a part of this tangential force acts as a lateral moment on the carrier and linear drive member connected to the brake member, making it difficult to smoothly guide these linear motions. There is a problem. When the linear drive member guided by the outer ring member is connected to the brake member, when the brake member is worn, the axial protrusion amount of the linear drive member from the outer ring member is increased, and the guide length is shortened. Therefore, smooth guidance of the linear drive member becomes more difficult.

  Further, the electric linear actuator includes the rotor shaft of the electric motor as a rotating shaft, and the components of the linear actuator are arranged on the outer diameter side thereof, and the electric motor and the linear actuator are coaxially connected in series. Since it arrange | positions, there also exists a problem that the whole axial direction length dimension becomes long.

  Accordingly, an object of the present invention is to make it possible to smoothly guide the linear motion of the output member even if a lateral moment acts on the linearly-moving output member, and to determine the axial length of the entire electric linear actuator. It is to shorten the dimensions.

  In order to solve the above-described problems, the present invention provides a carrier between a rotating shaft to which rotation is transmitted from an electric motor and an outer ring member fitted inside the inner diameter surface of the housing on the outer diameter side of the rotating shaft. A plurality of planetary rollers that are rotatably supported are interposed so that these planetary rollers revolve around the rotation shaft as the rotation shaft rotates, and spirally project on the inner surface of the outer ring member. A circumferential groove into which the spiral ridge is fitted at the same pitch as the spiral ridge, or a spiral ridge with a different lead angle at the same pitch as the spiral ridge, is provided on the outer diameter surface of the planetary roller. The outer ring member and the carrier are moved relative to each other in the axial direction, and the rotational movement of the rotary shaft is converted into the linear movement of the output member in the axial direction to be connected to the linearly moving output member. Electric drive that drives the driven object in a straight line An output member that restricts movement of the carrier in the axial direction, prevents the outer ring member from rotating, and is fitted into the inner diameter surface of the housing so as to be slidable in the axial direction, and linearly moves the outer ring member. As described above, a configuration is adopted in which the rotating shaft is arranged so as not to be coaxial with the rotor shaft of the electric motor, and rotation is transmitted from the rotor shaft to the rotating shaft.

  That is, the movement of the carrier in the axial direction is restricted, the outer ring member is prevented from rotating, the inner ring surface of the housing is slidably fitted in the axial direction, and the outer ring member is used as an output member that linearly moves. The outer ring member as a member can be guided with a long dimension in the axial direction on the inner diameter surface of the housing, and even if a lateral moment acts on the linearly moving output member, the linear motion of the output member can be smoothly guided. The rotation shaft is arranged so as not to be coaxial with the rotor shaft of the electric motor, and rotation is transmitted from the rotor shaft to the rotation shaft, so that the overall axial length can be shortened.

  By disposing the rotating shaft in parallel with the rotor shaft of the electric motor, the overall axial length can be made the shortest and the outer shape can be made compact with less irregularities.

  The rotation can be transmitted from the rotor shaft of the electric motor to the rotation shaft using a gear.

  The bearing that supports the rotating shaft is disposed at an axial position between the rotation transmitting portion from the rotor shaft and the planetary roller, so that the bearing is attached to the lid that closes the opening of the housing into which the rotating shaft is inserted. The lid can be formed into a thin and simple shape without the need for assembly.

  An annular member having an annular portion that supports the rotating shaft with a single bearing, is interposed between the rotating shaft and the outer ring member, and contacts the inner diameter surface of the outer ring member with a minute radial displacement. Thus, the momentary load is applied to the bearing of the rotating shaft even if the planetary roller is pressed against the outer diameter surface of the rotating shaft by indirectly supporting the rotating shaft at a portion axially separated from the support portion by the bearing. It can be prevented from working.

  By forming the spiral ridges provided on the inner diameter surface of the outer ring member with the strip members that surround the spiral grooves provided on the inner diameter surface of the outer ring member, the spiral ridges can be easily and accurately formed.

  By providing an elastic member that presses and urges the planetary roller against the outer diameter surface of the rotating shaft, each planetary roller is not preloaded by a negative gap between the outer diameter surface of the rotating shaft and the inner diameter surface of the outer ring member. The rotational torque of the rotating shaft can be stably transmitted to the planetary roller.

  The means for pressing and urging the planetary roller is provided with support pins for rotatably supporting the planetary roller on the inner diameter surface of the carrier, and restricting the support pins from moving in the circumferential direction on the carrier, It is possible to attach it while allowing movement in the radial direction, and bias it toward the rotary shaft side inward in the radial direction by the elastic member.

  The elastic member that urges the support pin radially inward may be a ring-shaped elastic member that is wound so as to envelop the support pin and elastically deforms so as to reduce the diameter.

  The present invention also includes an electric linear actuator that linearly drives the brake member by converting the rotational motion of the electric motor into linear motion, and presses the brake member that is linearly driven against the braked member. Therefore, by adopting a configuration in which any one of the above-described electric linear actuators is used as the electric linear actuator, a tangential force acting on the brake member from the braked member is laterally applied to the output member that moves linearly. Even when acting as a moment, the linear motion of the output member can be smoothly guided, and the axial length of the electric linear actuator can be shortened.

  The electric linear actuator of the present invention restricts the movement of the carrier supporting the planetary roller in the axial direction, prevents the outer ring member from rotating, and is fitted into the inner diameter surface of the housing so as to be slidable in the axial direction. Since the member is an output member that linearly moves and the rotation shaft is arranged so as not to be coaxial with the rotor shaft of the electric motor, even if a lateral moment acts on the linearly moving output member, the linear movement of the output member It can be guided smoothly and the overall axial length can be shortened.

  In the electric brake device of the present invention, the brake member that presses against the member to be braked is linearly driven by using the electric linear actuator described above, so that the tangential force acting on the brake member from the member to be braked is applied. However, even if acting as a lateral moment on the linearly moving output member, the linear motion of the output member can be smoothly guided, and the axial length of the electric linear actuator can be shortened. .

A longitudinal sectional view showing an embodiment of an electric linear actuator Sectional view along the line II-II in FIG. Sectional view along line III-III in FIG. (A), (b) is a front view which shows the spiral protrusion of the outer ring member of FIG. 1, and the spiral groove of the planetary roller, respectively. 1 is a longitudinal sectional view showing an electric brake device employing the electric linear actuator of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. As shown in FIGS. 1 to 3, the electric linear actuator is provided with a flange 1b projecting to one end of a cylindrical portion 1a of the housing 1, and the electric motor 2 is connected to the cylindrical portion 1a on the flange 1b. Attached in parallel, the rotation of the rotor shaft 2a of the electric motor 2 is transmitted to the rotation shaft 4 disposed in parallel with the rotor shaft 2a at the center of the cylindrical portion 1a by the gears 3a, 3b, 3c. The four planetary rollers 7 rotatably supported by the carrier 6 are interposed between the rotating shaft 4 and the outer ring member 5 fitted in the inner surface of the cylindrical portion 1a so as to be slidable in the axial direction. Each planetary roller 7 revolves while rotating around the rotating shaft 4 as it rotates.

  A lid 1c is attached to the side of the housing 1 where the flange 1b is provided, and the gears 3a, 3b, 3c are arranged so as to mesh with each other in the same axial section of the space covered with the lid 1c. The gears 3a, 3b, and 3c may be spur gears or helical gears, and the material may be a resin that can be reduced in weight, or a sintered material that can be easily molded, in addition to a metal such as steel. it can. The gears 3a, 3b, and 3c may be formed of different materials. Also, a shaft support member 8 is fitted on the lid 1c side of the cylindrical portion 1a, and the rotation shaft 4 to which the gear 3c is attached is an axial portion between the gear 3c and the planetary roller 7, and the shaft support member 8 is attached. Are supported by ball bearings 9. The shaft support member 8 is fixed to the housing 1 with retaining rings 10 on both sides, and also serves to regulate the movement of the rotary shaft 4 and the carrier 6 in the axial direction. An intermediate gear 3b meshed with the gear 3a and the gear 3c attached to the rotor shaft 2a is supported by a ball bearing 12 on a shaft pin 11 passed between the flange 1b and the lid 1c.

  The carrier 6 includes a carrier body 6a and a support plate 6b that are externally fitted to the rotary shaft 4 by means of sliding bearings 13a and 13b formed of a sintered material, and a carrier body 6a and a support plate 6b that are separated from each other. It comprises a support pin 6c that is supported at both ends and rotatably supports the planetary roller 7, and a plurality of connecting rods 6d that connect the support plate 6b in phase with the carrier body 6a, and both ends of each connecting rod 6d. Is connected to the carrier body 6a and the support plate 6b by bolts 6e. Each of the sliding bearings 13a and 13b may be formed of a resin, ceramics, a metal such as an aluminum alloy or a copper alloy, or a composite material thereof.

  The carrier body 6a that revolves together with the planetary roller 7 is supported on the end surface of the shaft support member 8 by a thrust roller bearing 14 via a support member 6f so as to be revolved, and to the base end side of the rotary shaft 4. The support plate 6b, which is restricted in movement and connected to the carrier body 6a by the connecting rod 6d, is secured to a retaining ring 15 attached to the tip of the rotating shaft 4 via a sliding bearing 16 formed of a sintered material. Thus, the movement of the rotating shaft 4 toward the tip side is restricted. Accordingly, the carrier 6 is restricted from moving in the axial direction of the rotating shaft 4. The slide bearing 16 may also be formed of a resin, ceramics, a metal such as an aluminum alloy or a copper alloy, or a composite material thereof.

  The planetary roller 7 is rotatably supported on a support pin 6c of the carrier 6 by a needle roller bearing 17, and its rotation is supported by a carrier body 6a by a thrust roller bearing 18, and each support pin 6c is Both ends of the carrier body 6a and the support plate 6b are attached to radial slots 19 provided in the radial direction so that movement in the circumferential direction is restricted and movement in the radial direction is allowed.

  Grooves 20 are provided on the outer diameter surfaces of both end portions of each support pin 6c, and a reduced diameter ring spring 21 formed of spring steel with a part cut in the circumferential direction is fitted into these grooves 20, Each support pin 6c is wound and attached so as to envelop. Accordingly, each planetary roller 7 rotatably supported by each support pin 6c is pressed and urged against the outer diameter surface of the rotary shaft 4, and the rotational torque of the rotary shaft 4 is stably transmitted to each planetary roller 7.

  The connecting rod 6d connects the carrier body 6a and the support plate 6b between the adjacent planetary rollers 7, and the outer diameter surfaces of the planetary rollers 7 on both sides are connected between the connecting rods 6d and the inner diameter surface of the outer ring member 5. A fan-shaped lubricant application member 22 that slides on and applies grease is held. Further, a seal member 23 is mounted on the inner diameter surface on the front end side of the outer ring member 5 so as to block the inner diameter portion where the planetary roller 7 and the lubricant application member 22 are arranged from the outside. The seal member 23 is formed by pressing a thin steel plate, and is fitted into the outer ring member 5 with a cylindrical portion formed on the outer periphery.

  The carrier body 6a and the support plate 6b are annular members that are in contact with the inner diameter surface of the outer ring member 5 with small radial displacements via sliding bearings 24a and 24b, respectively, and indirectly support the rotating shaft 4. Thus, moment load is prevented from acting on the ball bearing 9 that supports the rotating shaft 4 at one place. Each of the slide bearings 24a and 24b is formed of a sintered material, and is fixed to the outer diameter surfaces of the carrier body 6a and the support plate 6b by press-fitting. Each of the slide bearings 24a and 24b may also be formed of a resin, ceramics, a metal such as an aluminum alloy or a copper alloy, or a composite material thereof.

  A driven object is connected to the front end side of the outer ring member 5, and a key 25 is provided on the front end surface of the outer ring member 5 so as to be prevented from rotating by the driven object. Accordingly, the outer ring member 5 fitted in the inner diameter surface of the cylindrical portion 1a of the housing 1 so as to be slidable in the axial direction moves relative to the carrier 6 in which the axial movement in both directions is restricted, and outputs linearly. It becomes a member. The cylindrical portion 1a on the side where the driven object is connected to the outer ring member 5 is open, and the outer ring member 5 is guided in a long length in the axial direction on the inner diameter surface of the cylindrical portion 1a and protrudes from the cylindrical portion 1a. Smooth linear motion with long strokes.

  As shown in FIG. 4 (a), two spiral grooves 5a are provided on the inner diameter surface of the outer ring member 5 to which the planetary rollers 7 are in rolling contact, and separate strip members are attached around the spiral grooves 5a. 5 b, two spiral ridges are formed on the inner diameter surface of the outer ring member 5. Further, as shown in FIG. 4B, the spiral ridge formed by the strip member 5b is fitted into the outer diameter surface of the planetary roller 7, and one lead having a different lead angle at the same pitch as the spiral ridge. The spiral groove 7a is provided. Due to the engagement of the spiral ridges and the spiral grooves 7a, the planetary roller 7 that revolves while rotating around the rotation shaft 4 has a shaft angle with the outer ring member 5 due to the difference in the lead angle between the spiral ridges and the spiral grooves 7a. Move relative to the direction. The reason why the spiral ridges of the outer ring member 5 are two multi-threads is to increase the degree of freedom in setting the difference in the lead angle with the spiral groove 7a of the planetary roller 7. Articles may be used. The spiral groove 7a of the planetary roller 7 may be a circumferential groove having the same pitch as that of the spiral protrusion.

  FIG. 5 shows an electric brake device that employs the electric linear actuator described above. This electric brake device is a disc brake in which a brake pad 33 as a brake member is disposed oppositely on both sides of a disc rotor 32 as a braked member inside the caliper body 31, and the electric linear actuator is connected to the caliper body 31. The outer ring member 5 as an output member that linearly moves is locked to a brake pad 33 as a driven object by a key 25, and presses the brake pad 33 against the disc rotor 32. In this figure, the electric linear actuator is shown in a cross section orthogonal to the cross section shown in FIG.

  In the embodiment described above, the rotating shaft is arranged in parallel with the rotor shaft of the electric motor, but the rotating shaft can also be arranged at right angles to the rotor shaft. In this case, the rotation of the rotor shaft can be transmitted to the rotating shaft by meshing of the bevel gear or meshing of the worm and the gear. The material of the bevel gear or the worm and the gear may be a resin or a sintered material in addition to a metal such as a steel material, and the pair of bevel gears or the worm and the gear that mesh with each other may be formed of different materials.

  In the above-described embodiment, the spiral protrusion on the inner diameter surface of the outer ring member is formed by a separate stripe member fitted in the spiral groove. However, the spiral protrusion can be formed integrally with the outer ring member.

DESCRIPTION OF SYMBOLS 1 Housing 1a Cylindrical part 1b Flange 1c Cover 2 Electric motor 2a Rotor shaft 3a, 3b, 3c Gear 4 Rotating shaft 5 Outer ring member 5a Spiral groove 5b Strip member 6 Carrier 6a Carrier body 6b Support plate 6c Support pin 6d Connecting rod 6e Bolt 6f Support member 7 Planetary roller 7a Spiral groove 8 Shaft support member 9 Ball bearing 10 Retaining ring 11 Axle pin 12 Ball bearings 13a, 13b Sliding bearing 14 Thrust roller bearing 15 Retaining ring 16 Sliding bearing 17 Needle roller bearing 18 Thrust roller bearing 19 Long Hole 20 Groove 21 Reduced diameter ring spring 22 Lubricant application member 23 Seal member 24a, 24b Slide bearing 25 Key 31 Caliper body 32 Disc rotor 33 Brake pad

Claims (10)

  A plurality of planetary rollers rotatably supported by the carrier are interposed between a rotating shaft to which rotation is transmitted from the electric motor and an outer ring member fitted into the inner diameter surface of the housing on the outer diameter side of the rotating shaft. These planetary rollers revolve while rotating around the rotation axis as the rotation shaft rotates, and provided with spiral ridges on the inner diameter surface of the outer ring member, on the outer diameter surface of the planetary roller, The outer ring member and the carrier are provided with a circumferential groove into which the spiral ridges are fitted at the same pitch as the spiral ridges, or a spiral groove into which the spiral ridges are fitted at different pitches and the same pitch as the spiral ridges. The motor linearly drives the driven object connected to the linearly moving output member by converting the rotational motion of the rotary shaft into the linear motion of the output member in the axial direction. In the actuator, the carrier The rotation shaft is used as an output member that linearly moves the outer ring member. An electric linear actuator, wherein the electric linear actuator is arranged so as not to be coaxial with a rotor shaft of the electric motor, and the rotation is transmitted from the rotor shaft to the rotating shaft.   The electric linear actuator according to claim 1, wherein the rotary shaft is arranged in parallel with a rotor shaft of the electric motor.   The electric linear actuator according to claim 1 or 2, wherein a rotation is transmitted from a rotor shaft of the electric motor using a gear on the rotating shaft.   The electric linear actuator according to any one of claims 1 to 3, wherein a bearing that supports the rotating shaft is disposed in an axial position between a rotation transmitting portion from the rotor shaft and the planetary roller.   An annular member having an annular portion that supports the rotating shaft with a single bearing, is interposed between the rotating shaft and the outer ring member, and contacts the inner diameter surface of the outer ring member with a minute radial displacement. 5. The electric linear actuator according to claim 1, wherein the rotary shaft is indirectly supported by a portion separated from the support portion by the bearing in the axial direction.   The electric linear actuator according to any one of claims 1 to 5, wherein the spiral protrusion provided on the inner diameter surface of the outer ring member is formed by a strip member that is circumferentially attached to a spiral groove provided on the inner diameter surface of the outer ring member.   The electric linear actuator according to any one of claims 1 to 6, further comprising an elastic member that presses and biases the planetary roller toward the outer diameter surface of the rotation shaft.   The means for urging and pressing the planetary roller is provided with support pins for rotatably supporting the planetary roller on the inner diameter surface of the carrier, and these support pins restrict the movement of the planetary roller to the carrier, The electric linear motion actuator according to claim 7, wherein the electric linear motion actuator is attached by allowing movement in a radial direction and urged toward the rotary shaft side radially inward by the elastic member.   The electric type according to claim 8, wherein the elastic member that urges the support pin radially inward is a ring-shaped elastic member that is wound so as to envelop the support pin and elastically deforms so as to reduce the diameter. Linear actuator.   An electric brake device that includes an electric linear actuator that linearly drives a brake member by converting a rotational movement of the electric motor into a linear movement, and presses the brake member that is linearly driven against the member to be braked. An electric brake device using the electric linear actuator according to any one of claims 1 to 9 as a dynamic actuator.

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