JP5360559B2 - Electric linear actuator and electric brake device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To avoid locally excessive contact bearing pressure on a rotating shaft even in the case that a planetary roller is inclined with the operating force of the spiral protruded strip of an outer ring member when an output member linearly drives a driven object against a load. <P>SOLUTION: A carrier 7 as an output member has linear motion while restricting the axial movement of an outer ring member 5. On the outer diameter face of the planetary roller 6 at the front side in the direction that the carrier 7 as the output member linearly drives the driven object against a load, a crowning 6b is provided whose diameter is smaller at the shaft end side. Even in the case that the planetary roller 6 linearly driving the driven object together with the carrier 7 is inclined inward to the front side in the direction of linearly driving it with force F of the spiral protruded strip 5a of the outer ring member 5, locally excessive contact bearing pressure is thus avoided on the front end side of the planetary roller 6 rolling around the rotating shaft 4. <P>COPYRIGHT: (C)2011,JPO&amp;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.

  In response to such a problem, the present inventors can secure a large boosting function without incorporating a separate speed reduction mechanism, and as an electric linear actuator suitable for an electric brake device having a relatively small linear motion stroke. A plurality of planets rotatably supported by a carrier between a rotating shaft to which rotation is transmitted from the rotor shaft of 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; These planetary rollers revolve while rotating around the rotating shaft as the rotating shaft rotates by interposing rollers, and spiral ridges are provided on the inner diameter surface of the outer ring member, and the outer diameter surface of the planetary roller is provided. The outer ring member and the carrier are provided with a circumferential groove into which the spiral ridge is fitted at the same pitch as the spiral ridge, or a spiral groove into which the spiral ridge is fitted with a different lead angle at the same pitch as the spiral ridge. Axial phase So moving, by converting the rotary motion of the rotary shaft to linear motion of the carrier, has developed a mechanism to previously obtained by an output member for linearly driving a driven object carrier (see Patent Documents 2 and 3). In addition, a mechanism has been proposed in which the movement of the carrier in the axial direction is regulated to make the outer ring member an output member that linearly moves (Japanese Patent Application No. 2008-260547).

  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

  The electric linear motion actuator using the carrier described in Patent Documents 2 and 3 as an output member that linearly moves can secure a large boosting function with a compact design without incorporating a separate speed reduction mechanism. As shown in FIG. 4A, when the driven object is linearly driven against the load, the inner diameter of the outer ring member 5 is connected to the planetary roller 6 that linearly drives the driven object together with the carrier 7. A force F in the driving direction acts obliquely from the spiral ridge 5a on the surface. For this reason, a moment M is generated in which the planetary roller is tilted inward in the driving direction, and the contact surface pressure on the front end side of the planetary roller that rolls around the rotation shaft is locally excessive, resulting in fatigue. Life may be reduced.

  In addition, the electric linear motion actuator in which the outer ring member proposed in Japanese Patent Application No. 2008-260547 is an output member that linearly moves is used when the outer ring member linearly drives the driven object against the load as an output member. As shown in FIG. 7A, a force F opposite to the driving direction acts on the planetary roller 6, which is restricted in axial movement together with the carrier 7, from the spiral protrusion 5 a of the outer ring member 5 in an oblique direction. For this reason, a moment M is generated in which the planetary roller is inclined inward toward the rear side opposite to the driving direction, and the contact surface pressure on the rear end side of the planetary roller that rolls around the rotation shaft is locally excessive. Therefore, the fatigue life may be reduced.

  Even when the carrier or outer ring member as the output member moves in the direction opposite to the driving direction without load, the force in the direction opposite to the above-mentioned direction is obliquely applied to the planetary roller from the spiral protrusion of the outer ring member. Although it acts, since this force is small, there is no possibility that the contact surface pressure between the planetary roller and the rotating shaft becomes excessive on the shaft end side. However, in the case where the output member linearly drives the driven object against the load in both directions, the planetary roller is tilted by the force acting from the spiral ridge of the outer ring member regardless of whether the output member is the carrier or the outer ring member. The contact surface pressure with the rotating shaft at both ends may be excessive.

  Therefore, the problem of the present invention is that when the output member linearly drives the driven object against the load, even if the planetary roller is tilted by the force acting from the spiral ridge of the outer ring member, the contact surface with the rotating shaft The pressure should not be excessive locally.

  In order to solve the above-described problems, the present invention provides a rotation shaft between a rotation shaft that transmits rotation from a rotor shaft of an electric motor and an outer ring member that is fitted on the inner diameter surface of the housing on the outer diameter side of the rotation shaft. A plurality of planetary rollers rotatably supported by the carrier so that these planetary rollers revolve around the rotation shaft as the rotation shaft rotates, and the inner diameter surface of the outer ring member A spiral groove on the outer diameter surface of the planetary roller, or a circumferential groove in which the spiral protrusion is fitted at the same pitch as the spiral protrusion, or a different lead angle at the same pitch as the spiral protrusion. The outer ring member and the carrier move relative to each other in the axial direction, and either one of the outer ring member and the carrier that moves relative to each other in the axial direction is rotated. For linear motion as an output member In other words, in the electric linear motion actuator in which the linearly moving output member linearly drives the driven object against the load in at least one direction, the movement of the outer ring member in the axial direction is restricted, and the carrier Is an output member that linearly moves, and on the outer diameter surface of the planetary roller, at least the carrier in the axial direction is an output member on the front side in the direction of linearly driving the driven object against a load, and the shaft end side has a small diameter. The structure which gave the crowning which becomes was adopted.

  That is, the movement of the outer ring member in the axial direction is restricted to make the carrier a linear output member, and at least the carrier in the axial direction acts as an output member on the outer diameter surface of the planetary roller against the load on the driven object. A direction in which the planetary roller that linearly drives the driven object together with the carrier linearly drives with a force from the spiral ridge of the outer ring member by providing a crowning having a small diameter on the shaft end side on the front side in the linear driving direction. The contact surface pressure on the front end side of the planetary roller that rolls around the rotation axis does not become excessive locally even if it tilts inward toward the front side of the planetary roller, and the fatigue life of the planetary roller can be extended. .

  The present invention also supports a carrier rotatably between a rotating shaft that transmits rotation from a rotor shaft of an electric motor and an outer ring member that is fitted on the inner diameter surface of the housing on the outer diameter side of the rotating shaft. Interposing a plurality of planetary rollers, these planetary rollers revolve around the rotation shaft as the rotation shaft rotates, and provide a spiral ridge on the inner diameter surface of the outer ring member, A circumferential groove in which the spiral ridges are fitted at the same pitch as the spiral ridges, or a spiral groove in which the spiral ridges are fitted with different lead angles at the same pitch as the spiral ridges, 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 changed to a linear movement using either the outer ring member or the carrier that moves relatively in the axial direction as an output member. Convert this linear motion In the electric linear actuator that linearly drives the driven object against the load in at least one direction, the output member is an output member that linearly moves the outer ring member by restricting movement of the carrier in the axial direction. The outer diameter surface of the planetary roller is provided with crowning in which at least the outer ring member in the axial direction is a rear side in the direction of linearly driving the driven object against a load as an output member, and the shaft end side drops to a small diameter. The configuration was also adopted.

  That is, the movement of the carrier in the axial direction is restricted, and the outer ring member is an output member that linearly moves. The planetary roller, whose axial movement is restricted, is tilted inwardly by the force from the spiral ridge of the outer ring member by providing a crowning with a small diameter on the rear side in the direction of linear drive. However, the contact surface pressure on the rear end side of the planetary roller that rolls around the rotating shaft is not locally increased, and the fatigue life of the planetary roller can be extended.

  The crowning imparting length is preferably not more than ½ of the trunk length of the planetary roller. This is because when the crowning application length exceeds 1/2 of the trunk length, the contact surface pressure with the rotating shaft at a portion where crowning is not applied increases.

  The drop amount per radius at the shaft end of the crowning is preferably 0.1 mm or less. This is because when the amount of the crowning drop exceeds 0.1 mm, a non-contact region with the rotating shaft is generated, and the average contact surface pressure in the axial direction increases.

  By applying the crowning to both sides of the planetary roller in the axial direction, even if the output member linearly drives the driven object against the load in both directions, the contact surface pressure between the planetary roller and the rotating shaft Can be kept from becoming excessive locally.

  The planetary roller is made of steel and has a carburized layer formed at least on the outer diameter surface and subjected to secondary quenching to ensure toughness while ensuring the surface hardness of the outer diameter surface of the planetary roller. Further, the fatigue life of the planetary roller can be further extended.

  The rotating shaft is made of steel and has a carburized layer formed on at least the outer diameter surface and subjected to secondary quenching, thereby ensuring the surface hardness of the outer diameter surface of the rotating shaft and increasing toughness. The fatigue life of the rotating shaft can be extended.

  The outer ring member is made of steel and has a carburized layer formed at least on the inner diameter surface and subjected to secondary quenching, thereby ensuring toughness of the inner ring surface of the outer ring member and increasing toughness. The fatigue life of the member can be extended.

  The present invention further includes an electric linear actuator that linearly drives the brake member by converting the rotational motion of the electric motor into a linear motion of the output member, and that electrically presses the brake member that is linearly driven against the member to be braked. In the brake system, the output member of the linear actuator drives the brake member linearly against the load by adopting a configuration using any of the electric linear actuators described above as the electric linear actuator. Sometimes, even if the planetary roller is tilted by the force from the spiral ridge of the outer ring member, the contact surface pressure of the planetary roller that rolls around the rotating shaft is not locally increased, and the planetary roller has a fatigue life. I was able to extend.

  The electric linear actuator of the present invention regulates the movement of the outer ring member in the axial direction, and makes the carrier linearly move, and at least the carrier in the axial direction is covered as an output member on the outer diameter surface of the planetary roller. Since a crowning with a small diameter on the shaft end side is provided on the front side in the direction in which the driven object is linearly driven against the load, the planetary roller that linearly drives the driven object together with the carrier is provided with a spiral ridge of the outer ring member. The contact surface pressure on the front end side of the planetary roller that rolls around the rotation axis does not become excessively large even if it tilts inward in the direction of linear drive by the force from the The fatigue life can be extended.

  In addition, the electric linear actuator of the present invention regulates the movement of the carrier in the axial direction to make the outer ring member an output member that linearly moves, and at least the outer ring member in the axial direction is output to the outer diameter surface of the planetary roller. As a member, a crowning with a small diameter on the shaft end side is provided on the rear side in the direction of linearly driving the driven object against the load, so that the planetary roller whose axial movement is restricted is a spiral of the outer ring member. Fatigue life of the planetary roller is ensured so that the contact surface pressure on the rear end side of the planetary roller that rolls around the rotation axis does not become excessive locally even if it is tilted inwardly by the force from the ridge. Can be extended.

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. Sectional view along line III-III in FIG. 1 is a longitudinal sectional view for explaining the movement of the carrier in FIG. 1 to linearly drive the driven object, and b is an enlarged longitudinal sectional view showing the outer diameter portion of the planetary roller 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 a is a longitudinal sectional view for explaining the movement of the outer ring member of FIG. 6 linearly driving the driven object, and b is a longitudinal sectional view showing an enlarged outer diameter portion of the planetary roller of a

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 to 4 show a first embodiment. 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. Installed in parallel. The rotation of the rotor shaft 2a of the electric motor 2 is transmitted to the rotating shaft 4 disposed at the center of the cylindrical portion 1a by the gears 3a, 3b, 3c, and rotates with the outer ring member 5 fixed to the inner diameter surface of the cylindrical portion 1a. Four planetary rollers 6 interposed between the shaft 4 are rotatably supported by the carrier 7 and revolve while rotating around the rotation shaft 4, and a spiral of an outer ring member 5 described later. The carrier 7 supporting the planetary roller 6 and the outer ring member 5 are moved relative to each other in the axial direction by the engagement between the ridge 5a and the spiral groove 6a of the planetary roller 6. In this embodiment, the movement of the outer ring member 5 in the axial direction is restricted, and the carrier 7 is an output member that linearly moves.

  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. A shaft support member 8 is fitted on the lid 1c side of the cylindrical portion 1a, and the base end side of the rotating shaft 4 to which the gear 3c is attached is supported by the shaft support member 8 with a ball bearing 9. The shaft support member 8 is brought into contact with the end surface of the outer ring member 5, and the outer ring member 5 is restricted from moving in the axial direction by a retaining ring 10a for retaining the shaft supporting member 8 and a retaining ring 10b on the opposite side. . 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 7 is supported at both ends by a carrier body 7a and a support plate 7b which are externally fitted to the rotary shaft 4 so as to be slidable and relatively rotatable by slide bearings 13a and 13b, and by a carrier body 7a and a support plate 7b which are spaced apart. The support pin 7c for rotatably supporting the planetary roller 6 and a plurality of connecting rods 7d for connecting the support plate 7b in phase with the carrier body 7a are connected to both ends of the connecting rod 7d with bolts 7e. The main body 7a and the support plate 7b are connected. Each support pin 7c is attached to both ends thereof in a radial slot 14 provided in the carrier body 7a and the support plate 7b so that movement in the circumferential direction is restricted and movement in the radial direction is allowed. It has been.

  Grooves 15 are provided on the outer diameter surfaces of both end portions of each support pin 7c, and a reduced diameter ring spring 16 formed of spring steel with a part cut in the circumferential direction is fitted in each groove 15, Each support pin 7c is wound and attached so as to envelop. Therefore, each planetary roller 6 rotatably supported by each support pin 7c is pressed against the outer diameter surface of the rotating shaft 4, and the rotational torque of the rotating shaft 4 is stably transmitted to each planetary roller 6.

  Each planetary roller 6 is rotatably supported on a support pin 7c of a carrier 7 by a needle roller bearing 17 mounted on an inner diameter surface, and its rotation is supported by a carrier body 7a by a thrust roller bearing 18. On the front side of the carrier 7 that revolves together with each planetary roller 6 and linearly moves as an output member, a connecting member 19 that connects to the driven object is provided. A fan-shaped lubricant application member 20 that slidably contacts the outer diameter surfaces of the planetary rollers 6 on both sides and applies grease between the adjacent planetary rollers 6 is provided between the connecting rod 7 d of the carrier 7 and the outer ring member 5. It is held between the inner diameter surface.

  The connecting member 19 is externally fitted to the cylindrical portion of the carrier body 7a and is prevented from coming off by a retaining ring 21, and is supported by the thrust roller bearing 22 so as to be rotatable relative to the carrier body 7a, and is connected to a driven object. A key 23 for preventing rotation is provided on the front end face. The outer diameter side of the connecting member 19 is sealed between the cylindrical portion 1a of the housing 1 by an annular seal member 24, and the inner diameter side of the connecting member 19 is the rotational shaft 4 fitted in the carrier body 7a. It is sealed with a film-like sealing member 25 so as to cover the end.

  As shown in FIG. 4 (a), two spiral ridges 5a are provided on the inner diameter surface of the outer ring member 5, and the spiral ridges 5a are fitted on the outer diameter surface of the planetary roller 6 to form a spiral. One spiral groove 6a having the same pitch as that of the protrusion 5a and having a different lead angle is provided. Due to the engagement of the spiral ridges 5a and the spiral grooves 6a, the planetary roller 6 that revolves while rotating around the rotation shaft 4 has a difference in the lead angle between the spiral ridges 5a and the spiral grooves 6a. The carrier 7 as the output member also moves linearly together with the planetary roller 6 so as to move relative to each other in the axial direction. The reason why the spiral ridge 5a of the outer ring member 5 is a two-row spiral is to increase the degree of freedom in setting the difference in the lead angle with the spiral groove 6a of the planetary roller 6, and the spiral ridge 5a. May be one. Further, the spiral groove 6a of the planetary roller 6 can be a circumferential groove having the same pitch as the spiral ridge 5a.

  Further, the carrier 7 as the output member linearly drives the driven member against the load via the connecting member 19 when linearly moving to the left indicated by the arrow in FIG. At this time, a leftward force F in the driving direction acts on the planetary roller 6 that linearly drives the driven object together with the carrier 7 from the spiral protrusion 5a of the outer ring member 5 obliquely. For this reason, a moment M is generated on the planetary roller 6 that inwardly tilts forward in the driving direction.

  As shown in FIG. 4B, the outer diameter surface of the planetary roller 6 is provided with a crowning 6b on the left side which is the front in the driving direction and the shaft end side drops to a small diameter. This figure is enlarged in the radial direction to clearly show the crowning 6b. The application length L of the crowning 6b is about 約 that is 1/2 or less of the trunk length of the planetary roller 6, and the drop amount d per radius at the shaft end is 0.08 mm that is 0.1 mm or less. ing. Therefore, even if the planetary roller 6 is inclined inward inward by the force F from the spiral protrusion 5a of the outer ring member 5, the contact surface on the front end side of the planetary roller 6 that rolls around the rotation shaft 4 is provided. There is no risk of excessive pressure locally.

  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. When the carrier 1 as the output member linearly moves to the left, the carrier 7 moves the brake pad 33 as the driven object against the load via the connecting member 19, and the disk rotor 32. It is designed to be pressed. In this figure, the electric linear actuator is shown in a cross section orthogonal to the cross section shown in FIG.

  6 and 7 show a second embodiment. This electric linear actuator has the same basic configuration as that of the first embodiment, and is an output member in which the movement of the carrier 7 in the axial direction is restricted and the outer ring member 5 moves linearly. Is mainly different. As shown in FIG. 6, in this embodiment, the carrier main body 7a and the support plate 7b of the carrier 7 are arranged opposite to the left and right of the first embodiment, and the carrier main body 7a is interposed via a support member 7f. A thrust roller bearing 26 is rotatably supported by a shaft support member 8 fitted on the lid 1c side of the cylindrical portion 1a of the housing 1. The shaft support member 8 is fixed on both sides in the axial direction by retaining rings 10a and 10c, and the support plate 7b is retained on the rotating shaft 4 by a retaining ring 28 via a slide bearing 27, so that the carrier 7 moves in the axial direction. It is regulated.

  The outer ring member 5 as the output member is slidably fitted into the cylindrical portion 1a of the housing 1 and is provided with a key 23 connected to the driven object to prevent rotation. The outer ring side of the outer ring member 5 is sealed between the cylindrical part 1 a by an annular seal member 24, and the inner side of the outer ring member 5 of the rotary shaft 4 fitted in the support plate 7 b of the carrier 7. It is sealed with a film-like sealing member 25 so as to cover the end. Other parts are the same as those of the first embodiment.

  As shown in FIG. 7 (a), two spiral ridges 5a are provided on the inner diameter surface of the outer ring member 5, and the spiral ridges 5a are fitted on the outer diameter surface of the planetary roller 6 to form a spiral. One spiral groove 6a having the same pitch as that of the protrusion 5a and having a different lead angle is provided, and the outer ring member 5 moves linearly so as to move relative to the carrier 7 in the axial direction.

  In this embodiment, when the outer ring member 5 as the output member linearly moves in both the left and right directions, the driven member is linearly driven against the load. When the outer ring member 5 is linearly driven to the left as shown by an arrow in FIG. 7A, the planetary roller 6 whose axial movement is restricted together with the carrier 7 has a spiral protrusion of the outer ring member 5. A rightward force F opposite to the driving direction acts diagonally from the strip 5a. For this reason, a moment M is generated in the planetary roller 6 that is inclined inward to the right side opposite to the driving direction. Although illustration is omitted, when the outer ring member 5 is linearly driven rightward, a leftward force F acts diagonally, and a moment is generated in the planetary roller 6 that is inclined inwardly to the left.

  As shown in FIG. 7B, the outer diameter surface of the planetary roller 6 is provided with a crowning 6b in which the shaft end side drops to a small diameter on both the left and right sides. This figure is also enlarged in the radial direction to clearly show the crowning 6b. The application length L of the crowning 6b is about ¼ of the trunk length of the planetary roller 6, and the drop amount d per radius at both shaft ends is 0.08 mm. Therefore, even if the planetary roller 6 is tilted inward to the left or right by the force F from the spiral protrusion 5a of the outer ring member 5, the contact at both ends of the planetary roller 6 that rolls around the rotation shaft 4 is achieved. There is no fear that the surface pressure will be excessive locally.

  In the embodiment described above, the spiral ridges on the inner surface of the outer ring member are integrally formed. However, a spiral groove is provided on the inner surface of the outer ring member, and the spiral ridge is formed by a separate member fitted in the spiral groove. It can also be formed.

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 ridge 6 Planetary roller 6a Spiral groove 6b Crowning 7 Carrier 7a Carrier main body 7b Support plate 7c Support pin 7d Connecting rod 7e Bolt 7f Support member 8 Shaft support member 9 Ball bearings 10a, 10b, 10c Retaining ring 11 Shaft pin 12 Ball bearings 13a, 13b Slide bearing 14 Long hole 15 Groove 16 Reduced ring spring 17 Needle roller bearing 18 Thrust Roller bearing 19 Connecting member 20 Lubricant application member 21 Retaining ring 22 Thrust roller bearing 23 Key 24, 25 Seal member 26 Thrust roller bearing 27 Sliding bearing 28 Retaining ring 31 Caliper body 32 Disc rotor 33 Brake pad

Claims (9)

A plurality of planetary rollers rotatably supported by a carrier between a rotating shaft to which rotation is transmitted from a rotor shaft of 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 The planetary roller contacts the outer periphery of the planetary roller with a cylindrical surface formed on the outer periphery of the rotary shaft so that these planetary rollers revolve around the rotary shaft as the rotary shaft rotates. A spiral groove having a V-shaped cross section is provided on the inner diameter surface of the outer ring member, and a circumferential groove in which the spiral protrusion is fitted at the same pitch as the spiral protrusion on the outer diameter surface of the planetary roller, or a spiral protrusion, A spiral groove in which spiral ridges are fitted with different lead angles at the same pitch is provided so that the outer ring member and the carrier are relatively moved in the axial direction, and the rotational movement of the rotating shaft is relatively moved in the axial direction. Either outer ring member or carrier Is converted into a linear motion that is an output member one, the electric linear motion actuator for linearly driving against the load driven object output member to the linear movement of at least one direction,
The movement of the outer ring member in the axial direction is restricted, and the carrier is used as an output member that linearly moves. At least the carrier in the axial direction is used as an output member on the outer diameter surface of the planetary roller, and the driven object is loaded. An electric linear actuator characterized in that a crowning having a small diameter on the shaft end side is provided on the front side in the direction of linear driving. A plurality of planetary rollers rotatably supported by a carrier between a rotating shaft to which rotation is transmitted from a rotor shaft of 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 The planetary roller contacts the outer periphery of the planetary roller with a cylindrical surface formed on the outer periphery of the rotary shaft so that these planetary rollers revolve around the rotary shaft as the rotary shaft rotates. A spiral groove having a V-shaped cross section is provided on the inner diameter surface of the outer ring member, and a circumferential groove in which the spiral protrusion is fitted at the same pitch as the spiral protrusion on the outer diameter surface of the planetary roller, or a spiral protrusion, A spiral groove in which spiral ridges are fitted with different lead angles at the same pitch is provided so that the outer ring member and the carrier are relatively moved in the axial direction, and the rotational movement of the rotating shaft is relatively moved in the axial direction. Either outer ring member or carrier Is converted into a linear motion that is an output member one, the electric linear motion actuator for linearly driving against the load driven object output member to the linear movement of at least one direction,
The outer ring member is an output member that linearly moves the outer ring member by restricting the movement of the carrier in the axial direction. At least the outer ring member in the axial direction is loaded on the outer diameter surface of the planetary roller as the output member. An electric linear actuator characterized in that a crowning is provided such that the shaft end side drops to a small diameter on the rear side in the direction of linear driving against the above.   3. The electric linear actuator according to claim 1, wherein a length of the crowning is set to ½ or less of a trunk length of the planetary roller.   The electric linear actuator according to any one of claims 1 to 3, wherein a drop amount per radius at the shaft end of the crowning is 0.1 mm or less.   The electric linear actuator according to any one of claims 1 to 4, wherein the crowning is provided on both sides of the planetary roller in the axial direction.   The electric linear actuator according to any one of claims 1 to 5, wherein the planetary roller is made of steel and has a carburized layer formed at least on an outer diameter surface and subjected to secondary quenching.   The electric linear actuator according to claim 6, wherein the rotating shaft is made of steel and has a carburized layer formed on at least an outer diameter surface and subjected to secondary quenching.   The electric linear actuator according to claim 6 or 7, wherein the outer ring member is made of steel and has a carburized layer formed on at least an inner diameter surface and subjected to secondary quenching.   In the electric brake device that includes an electric linear motion actuator that linearly drives the brake member by converting the rotary motion of the electric motor into a linear motion of the output member, 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 8 as the electric linear actuator.

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