JP4690268B2 - Electric linear actuator and electric brake device - Google Patents

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).

  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 be designed in a compact manner 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 2).

  Usually, since the electric brake device is attached under the spring of the vehicle, it is desired to be able to operate stably even under vibration from the road surface and to be designed compactly.

JP-A-6-327190 (Figs. 1 and 5) JP 2003-343620 A (FIG. 1)

  The ball screw mechanism and the ball ramp mechanism employed in the above-described conventional electric linear actuator have a certain degree of boosting function by the motion conversion mechanism along the lead screw thread and the inclined cam surface. A large boosting function as required by a brake device or the like cannot be secured. For this reason, in the electric linear actuator that employs these motion conversion mechanisms, the drive force is increased by incorporating a separate reduction mechanism as described above, but a gear reduction mechanism such as a planetary gear reduction mechanism is incorporated. Impedes the compact design of the electric linear actuator.

  In addition, when an electric linear actuator using a ball screw mechanism is incorporated in an electric brake device, the linear movement stroke of the brake member that presses the member to be braked is relatively small and formed on the ball screw nut and the screw shaft. Since the amount of movement of the ball in the ball circulation path is reduced, the specific ball is likely to be worn, and the grease is not efficiently stirred, resulting in a problem that the durable life of the ball screw is reduced.

  For such problems, the present applicant can secure a large boosting function without incorporating a separate speed reduction mechanism, and an electric motor as an electric linear actuator suitable for an electric brake device having a small linear stroke. A plurality of planetary rollers rotatably supported by the carrier are interposed between the outer diameter surface of the rotor shaft and the inner diameter surface of the outer ring member fixed to the outer diameter side of the rotor shaft. The planetary roller revolves while rotating around the rotor shaft as the rotor shaft rotates, and spiral ridges are provided on the outer diameter surface of the rotor shaft or the inner diameter surface of the outer ring member, and the outer diameter surface of each planetary roller is provided. A circumferential groove in which the spiral ridge engages at the same pitch as the spiral ridge, or a spiral groove in which the lead angle is different and the spiral ridge engages at the same pitch as the spiral ridge, around the rotor shaft. Each play that revolves while spinning The carrier for supporting the rollers are relatively moved in the axial direction, it has proposed a mechanism for converting the rotary motion of the rotor shaft to linear motion of the carrier previously (Japanese Patent Application No. 2005-6714, Japanese Patent Application No. 2005-217429). These previously proposed electric linear actuators have spiral ridges provided on the outer diameter surface of the rotor shaft or the inner diameter surface of the outer ring member as circumferential ridges, and a spiral groove is provided on the outer diameter surface of each planetary roller. These ridges may be provided on the planetary roller side, and the grooves engaged therewith may be provided on the outer ring member side or the rotor shaft side.

  The electric linear actuator described above lubricates a groove between the outer diameter surface of the rotor shaft or the inner diameter surface of the outer ring member and the outer diameter surface of the planetary roller and the grooves that engage with each other with a lubricant such as grease. Although necessary, there is a problem that the lubricant supplied between the ridges and the grooves is gradually pushed out along with the rolling contact between the planetary roller and the rotor shaft and the outer ring member, resulting in insufficient lubrication. When such lubrication is insufficient, wear and seizure are likely to occur between the planetary roller that is in rolling contact with the rotor shaft and the outer ring member, and the life of the linear motion actuator is shortened.

  Accordingly, an object of the present invention is to eliminate insufficient lubrication between a planetary roller in rolling contact with an electric linear actuator and a rotor shaft or outer ring member.

  In order to solve the above problems, an electric linear actuator of the present invention is provided between an outer diameter surface of a rotor shaft of an electric motor and an inner diameter surface of an outer ring member fixed to the outer diameter side of the rotor shaft. A plurality of planetary rollers rotatably supported by the carrier so that each of these planetary rollers revolves while rotating around the rotor shaft as the rotor shaft rotates. On the radial surface or the inner diameter surface of the outer ring member and the outer diameter surface of each planetary roller, the spiral ridges and circumferential grooves or the circumferential grooves or spiral grooves and circumferential ridges of the same pitch that engage with each other, or at the same pitch A spiral ridge and a spiral groove having different lead angles are provided, and a carrier supporting each planetary roller that revolves while rotating around the rotor shaft is relatively moved in the axial direction, and the rotational motion of the rotor shaft is controlled by the carrier. In linear motion And conversion, the electric linear motion actuator for linearly driving a driven object, employing the configuration in which the lubricant applying member for applying a contact with a lubricant on the outer diameter surface of the planetary rollers.

  That is, by providing a lubricant application member that contacts the outer diameter surface of the planetary roller and applies the lubricant, insufficient lubrication between the rolling planetary roller and the rotor shaft or outer ring member can be solved. As a means for supplying the lubricant to the lubricant application member, a method of applying or impregnating the lubricant in advance to the contact portion of the lubricant application member with the outer diameter surface of the planetary roller, or this contact A method of providing a lubricant supply path to the part can be employed.

  By simultaneously bringing the lubricant application member into contact with the outer diameter surface of the planetary roller adjacent on both sides, the lubricant application member can be brought into contact with the adjacent planetary roller on both sides in a balanced manner. Further, the lubricant can be applied to the outer diameter surfaces of two adjacent planetary rollers with one lubricant application member, and the number of the lubricant application members can be reduced.

  On the contact surface of the lubricant application member that contacts the outer diameter surface of the planetary roller, a groove that fits the protrusion provided on the outer diameter surface of the planetary roller, or a protrusion that fits the groove. By providing, the lubricant can be efficiently applied to the ridges or grooves on the outer diameter surface of the planetary roller.

  By forming at least the portion of the lubricant application member that contacts the outer diameter surface of the planetary roller with resin, it is possible to eliminate the possibility of the outer diameter surface of the planetary roller being worn or brazed.

  The lubricant application member may have a concave arc surface that is in sliding contact with the outer diameter surface of the planetary roller.

  The lubricant application member may be a roller having a cylindrical surface that is in rolling contact with the outer diameter surface of the planetary roller.

  The lubricant application member can be supported by the carrier.

  The lubricant application member can be formed integrally with the carrier except for the roller-shaped member.

  The electric brake device according to the present invention includes an electric linear actuator that linearly drives the brake member by converting the rotational motion of the electric motor into a linear motion, and presses the brake member that is linearly driven against the member to be braked. In the electric brake device, any one of the electric linear actuators described above is used as the electric linear actuator so that the brake can be operated with a large linear driving force without incorporating a separate speed reduction mechanism. At the same time, the lubrication deficiency between the planetary roller, which is in rolling contact with the electric linear actuator, and the rotor shaft and outer ring member can be resolved.

  The electric linear actuator of the present invention is provided with the lubricant application member that contacts the outer diameter surface of the planetary roller and applies the lubricant, so that lubrication between the planetary roller that is in rolling contact with the rotor shaft and the outer ring member is provided. The shortage can be resolved.

  By simultaneously bringing the lubricant application member into contact with the outer diameter surface of the planetary roller adjacent on both sides, the lubricant application member can be brought into contact with the adjacent planetary roller on both sides in a balanced manner. Further, the lubricant can be applied to the outer diameter surfaces of two adjacent planetary rollers with one lubricant application member, and the number of the lubricant application members can be reduced.

  On the contact surface of the lubricant application member that contacts the outer diameter surface of the planetary roller, a groove that fits the protrusion provided on the outer diameter surface of the planetary roller, or a protrusion that fits the groove is provided. Thus, the lubricant can be efficiently applied to the ridges or grooves on the outer diameter surface of the planetary roller.

  By forming at least the portion of the lubricant application member that contacts the outer diameter surface of the planetary roller with resin, it is possible to eliminate the possibility of the outer diameter surface of the planetary roller being worn or brazed.

  The electric brake device according to the present invention uses the above-described electric linear actuator for the electric linear actuator, so that the brake can be operated with a large linear driving force without incorporating a separate reduction mechanism, and the electric linear actuator can be operated. Insufficient lubrication between the planetary roller in contact with the dynamic actuator and the rotor shaft or outer ring member can be resolved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 to 5 show the electric linear actuator of the first embodiment. As shown in FIGS. 1 and 2, the electric linear actuator includes an outer ring member 3 in which an electric motor 2 is fitted on one end side of a cylindrical casing 1 and is fitted on the other end side of the casing 1. Between the inner diameter surface and the outer diameter surface of the rotor shaft 2 a of the electric motor 2 extending to the center of the outer ring member 3, three planetary rollers 5 that are rotatably supported by the carrier 4 are interposed. The roller 5 revolves while rotating around the rotation of the rotor shaft 2a, and is in sliding contact with the outer diameter surfaces of the planetary rollers 5 on both sides between the adjacent planetary rollers 5, Three fan-shaped lubricant application members 6 for applying grease as a lubricant are arranged. Each lubricant application member 6 is supported by the carrier 4 via a bottomed partial cylindrical case 7 described later.

  Each planetary roller 5 is rotatably supported by a needle roller bearing 8 on a support shaft 4a of a carrier 4 fitted on the rotor shaft 2a, and its rotation is supported by the carrier 4 by a thrust ball bearing 9. Further, a linear drive member 10 is supported by a thrust ball bearing 11 on the carrier 4 that revolves together with each planetary roller 5, and the linear motion of each planetary roller 5 is transmitted to the linear drive member 10 via the carrier 4. It has become. The inside of the actuator is sealed by a boot 12 mounted between the outer diameter side of the linear drive member 10 and the outer ring member 3, and the inner diameter side of the linear drive member 10 through which the rotor shaft 2a passes is a membrane seal. 13 is sealed.

  As shown in FIG. 3 (a), two spiral grooves 3a are provided on the inner diameter surface of the outer ring member 3 to which the planetary rollers 5 are in rolling contact, and the strip members having a square cross section are circumferentially attached to the spiral grooves 3a. Thus, two spiral ridges 3 b are formed on the inner diameter surface of the outer ring member 3. Further, as shown in FIG. 3 (b), the spiral ridges 3b are fitted into the outer diameter surfaces of the planetary rollers 5, and one spiral groove having the same pitch as the spiral ridges 3b but having a different lead angle. 5a is provided. The reason why the spiral ridges 3b of the outer ring member 3 are two multi-threads is to increase the degree of freedom in setting the difference in the lead angle with the spiral groove 5a of the planetary roller 5, and the spiral ridges 3b. May be one. In addition, the spiral directions of the spiral protrusion 3b and the spiral groove 5a shown in FIGS. 3 (a) and 3 (b) appear to be opposite to each other, but are shown in FIG. 3 (a). Since the spiral ridge 3b is screwed into a portion on the back side of the spiral groove 5a shown in FIG. 3B, the directions of the spirals of both are the same. Accordingly, each planetary roller 5 that revolves while rotating around the rotor shaft 2a and whose spiral groove 5a is screwed with the spiral protrusion 3b of the outer ring member 3 has a lead angle between the spiral protrusion 3b and the spiral groove 5a. It moves linearly in the axial direction due to the difference.

  The fan-shaped lubricant application member 6 is made of resin, and as shown in FIGS. 4A and 4B, on both sides of the fan shape, a concave arc surface 6a that is in sliding contact with the outer diameter surface of the adjacent planetary roller 5 is used. The concave arc surface 6a is formed with a plurality of convex ridges 6b that fit into the spiral grooves 5a of the planetary roller 5, and the concave arc surface 6a on which the convex ridges 6b are formed. Grease is applied to the outer diameter surface.

  As shown in FIGS. 5 (a) and 5 (b), the bottomed partial cylindrical case 7 includes partial cylindrical portions 7a that support the outer diameter side of the three lubricant application members 6, and each lubricant application. The bottom portion 7b supports the end surface of the member 6 in the axial direction. The bottom portion 7b is provided with a hole 7c into which the rotor shaft 2a is fitted. In the case 7, the distal end side of the partial cylindrical portion 7a is externally fitted to the carrier 4, and the retaining ring 14 is fitted into a groove 7d provided on the inner diameter surface of the distal end portion of the partial cylindrical portion 7a. Is done.

  FIG. 6 shows an electric brake device that employs the electric linear actuator described above. This electric brake device is a disc brake in which brake pads 23 as brake members are arranged oppositely on both sides of a disc rotor 22 as a braked member inside the caliper body 21, and the electric linear actuator is connected to the caliper body 21. The brake pad 23 is pressed against the disc rotor 22 by the linear drive member 10. The linear drive member 10 is prevented from rotating by a key 24 on the brake pad 23 on the pressing side.

  7 and 8 show the electric linear actuator of the second embodiment. This electric linear actuator has the same basic configuration as that of the first embodiment, and the three fan-shaped lubricant application members 6 are formed integrally with the carrier 4. Only the concave arc surface 6a portion of each lubricant application member 6 that is in sliding contact with the outer diameter surface is formed of the resin 15, and the planetary roller 5 is not supported by the support shaft 4a of the carrier 4, so that the carrier The difference is that the axial direction is fixed at the bottom portion 7 b of the bottomed partially cylindrical case 7 fixed to 4. Other parts are the same as those of the first embodiment.

  9 to 11 show an electric linear actuator of the third embodiment. As shown in FIGS. 9 and 10, this electric linear actuator has one spiral protrusion 3 b on the inner diameter surface of the outer ring member 3, and the outer diameter surfaces of the three planetary rollers 5. The point that the spiral groove 5a is a circumferential groove 5b provided at the same pitch as the spiral ridge 3b, and the three lubricant application members 6 are transferred to the outer diameter surfaces of the planetary rollers 5 on both sides. The first embodiment is a roller-like shape having a cylindrical surface in contact with the bottom portion 7b of the bottomed partially cylindrical case 7 fixed to the carrier 4. Different.

  The roller-shaped lubricant application member 6 is made of resin, and as shown in FIG. 11A, a plurality of circumferential ridges 6b that fit into the circumferential grooves 5b of the planetary roller 5 are formed on its cylindrical surface. In addition, grease is applied to the outer diameter surface of the planetary roller 5 on the cylindrical surface on which the ridge 6b is formed. Each roller-like lubricant application member 6 is supported by the bottomed partial cylindrical case 7 in the axial direction and the outer diameter side. When the spiral groove 5a is provided on the outer diameter surface of the planetary roller 5 as in the first embodiment, the cylindrical surface of the lubricant application member 6 is formed on the cylindrical surface of the lubricant application member 6 as shown in FIG. The spiral ridge 6c having the reverse lead may be formed at the same pitch as the spiral groove 5a.

  12 and 13 show an electric linear actuator of the fourth embodiment. This electric linear actuator has the same basic configuration as that of the third embodiment, and the three roller-shaped lubricant application members 6 are provided on a second support shaft provided on the carrier 4. The cylindrical surface is rotatably supported by 4b, and the cylindrical surface is in contact with the outer diameter surface of the planetary roller 5 on one side only. Other parts are the same as those of the third embodiment.

  In each of the above-described embodiments, spiral ridges are provided on the inner diameter surface of the outer ring member, and spiral grooves and circumferential grooves are provided on the outer diameter surface of the planetary roller. However, the spiral ridges are provided on the outer diameter surface of the rotor shaft. Alternatively, the spiral ridge provided on the outer diameter surface of the rotor shaft or the inner diameter surface of the outer ring member may be a circumferential ridge, and the spiral groove may be provided on the outer diameter surface of the planetary roller. It is also possible to provide these ridges on the planetary roller side, and provide grooves that engage with the ridges on the outer ring member side or the rotor shaft side.

  Moreover, in each embodiment mentioned above, it fits into the spiral groove | channel and circumferential groove | channel of a planetary roller in the concave arc surface of a lubricant application | coating member contact | abutted to the outer diameter surface of a planetary roller, or the contact surface of a cylindrical surface. Protrusions are provided, but when spiral ridges or circumferential ridges are provided on the outer diameter surface of the planetary roller, it is preferable to provide grooves in which these ridges fit into the contact surface of the lubricant application member. . The contact surface of the lubricant application member can also be a flat surface without ridges or grooves. When a groove is provided on the contact surface, it is a wide groove into which a plurality of ridges fit. You can also.

1 is a longitudinal sectional view showing an electric linear actuator according to a first embodiment. Sectional view along the line II-II in FIG. a and b are front views showing the spiral ridge of the outer ring member and the spiral groove of the planetary roller in FIG. a is a front view showing the lubricant application member of FIG. 1, and b is a sectional view taken along line IVb-IVb of a. a is a side view showing the case of FIG. 1, and b is a cross-sectional view taken along line Vb-Vb of a. 1 is a longitudinal sectional view showing an electric brake device employing the electric linear actuator of FIG. A longitudinal sectional view showing an electric linear actuator of a second embodiment Sectional view along line VIII-VIII in FIG. A longitudinal section showing an electric linear actuator of a 3rd embodiment Sectional view along line XX in FIG. a is a front view showing the lubricant application member of FIG. 9, and b is a front view showing a modification of a. A longitudinal section showing an electric linear actuator of a 4th embodiment Sectional drawing along the XIII-XIII line of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Casing 2 Electric motor 2a Rotor shaft 3 Outer ring member 3a Spiral groove 3b Spiral protrusion 4 Carrier 4a, 4b Support shaft 5 Planetary roller 5a Spiral groove 5b Circumferential groove 6 Lubricant application member 6a Concave arc surface 6b, 6c Convex 7 Case 7a Partial cylindrical portion 7b Bottom portion 7c Hole 8 Needle roller bearing 9 Thrust ball bearing 10 Linear drive member 11 Thrust ball bearing 12 Boot 13 Film seal 14 Retaining ring 15 Resin 21 Caliper body 22 Disc rotor 23 Brake pad 24 Key

Claims (5)

A plurality of planetary rollers rotatably supported by the carrier are interposed between the outer diameter surface of the rotor shaft of the electric motor and the inner diameter surface of the outer ring member fixed to the outer diameter side of the rotor shaft. Each planetary roller revolves while rotating around the rotor shaft as the rotor shaft rotates, the outer diameter surface of the rotor shaft or the inner diameter surface of the outer ring member, and the outer diameter surface of each planetary roller The spiral ridges and circumferential grooves of the same pitch that engage with each other or the spiral grooves and circumferential ridges of the same pitch, or spiral ridges and spiral grooves of the same pitch and different lead angles, Electric linear motion that linearly drives the driven object by relatively moving in the axial direction the carrier supporting each planetary roller that revolves while rotating around it, and converting the rotational motion of the rotor shaft into the linear motion of the carrier In the actuator
Between each of the adjacent planetary rollers, a plurality of fan-shaped lubricant application members that apply the lubricant in contact with the outer diameter surface of the planetary roller over the entire length in the axial direction are provided, and both sides of the sector of the lubricant application member A concave arc surface that is in sliding contact with the outer diameter surface of the adjacent planetary roller, a case for supporting the end surface of each lubricant application member in the axial direction, and a case in which the case is fixed to the carrier in the axial direction. Electric direct acting actuator that is characterized.   2. The electric linear actuator according to claim 1, wherein the lubricant application member is simultaneously brought into contact with the outer diameter surface of the planetary roller adjacent on both sides.   On the contact surface of the lubricant application member that contacts the outer diameter surface of the planetary roller, a groove that fits the protrusion provided on the outer diameter surface of the planetary roller, or a protrusion that fits the groove. The electric linear actuator according to claim 1 or 2 provided.   4. The electric linear actuator according to claim 1, wherein at least a portion of the lubricant application member that contacts the outer diameter surface of the planetary roller is formed of resin. 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 4 as a dynamic actuator.

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