JP5096609B2 - Electric brake device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make helical convex stripes not come into contact with a groove fringe and to make side surfaces of the helical convex stripes fitting into grooves not be biasedly abutted on by sidewalls of the grooves in a base part side or the top side when the helical convex stripes fit into peripheral directional grooves or helical grooves. <P>SOLUTION: The sidewalls of the helical grooves 7a of a planetary roller 7 are inclined such that a groove width is widened from a groove bottom side to a groove fringe side, the sidewalls of the helical convex stripes of an outer wheel member 5 are inclined such that a stripe width is narrowed from a base part side to the top side, the side surfaces of the inclined helical convex stripes are formed in an arc face 5c becoming middle high in an inclined direction, thereby the contact of the helical convex stripes to the groove fringes is prevented the base part sides or the top sides of the side surfaces of the helical convex stripe fitting into the helical grooves 7a are not abutted on by the sidewalls of the helical grooves 7a when the helical concave stripes fit into the helical grooves 7a. <P>COPYRIGHT: (C)2012,JPO&amp;INPIT

Description

  The present invention relates to an electric brake device that presses a brake member against a member to be braked using an electric linear actuator that converts a rotational movement of an electric motor into a linear movement to linearly drive a driven object.

  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.

  With respect 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 small linear stroke, A plurality of planetary rollers rotatably supported by a carrier are provided between a rotating shaft to which rotation is transmitted from the rotor shaft of the motor and an outer ring member fixed to the inner surface of the casing on the outer diameter side of the rotating shaft. By interposing, each of these planetary rollers revolves while rotating around the rotation shaft as the rotation shaft rotates, and provided with spiral ridges on the outer diameter surface of the rotation shaft or the inner diameter surface of the outer ring member, The outer circumferential surface of the planetary roller is provided with 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 at the same pitch as the spiral ridges but with different lead angles. Around the axis of rotation The carrier for supporting the respective planetary rollers to rolling while revolving by relatively moved in the axial direction, has proposed a mechanism for converting the rotary motion of the rotary shaft into a linear motion of the carrier previously (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). 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 JP 2007-32717 A JP 2007-37305 A JP 2003-343620 A

  The electric linear actuators described in Patent Documents 2 and 3 can ensure a large boosting function with a compact design without incorporating a separate speed reduction mechanism, but can be applied to the outer diameter surface of the rotating shaft or the inner diameter surface of the outer ring member. Since the lead angle of the provided spiral ridge is different from the lead angle of the circumferential groove or spiral groove provided on the outer diameter surface of the planetary roller, the outer diameter surface of the planetary roller is the outer diameter surface of the rotating shaft or the inner diameter of the outer ring member. When the spiral ridges fit into the circumferential grooves or spiral grooves while rolling to the surface, the spiral ridges contact the groove edges, and the torcross resulting from this contact resistance reduces the conversion efficiency to linear motion There is a problem to do.

  In addition, after the spiral ridge is fitted in the circumferential groove or the spiral groove of the planetary roller, one side surface of the spiral ridge is brought into contact with one side wall of the planetary roller groove, and the planetary roller is linearly driven. Force is transmitted, but if the base side or the top side of the spiral ridge is biased and abutted against the side wall of the groove, the contact surface pressure at these abutting portions becomes high and fatigue damage is likely to occur. There is also. In the case where the top side of the spiral ridge is abutted in a biased manner, the peripheral speed difference of the abutting portion is increased, so that wear tends to occur.

  Therefore, the object of the present invention is to prevent the spiral ridges from coming into contact with the groove edges when the spiral ridges are fitted into the circumferential grooves or the spiral grooves, and the spirals fitted into these grooves. It is to prevent the side surfaces of the ridges from coming into contact with the side walls of the groove in the base side or the top side.

  In order to solve the above problems, an electric brake device according to the present invention includes an electric linear actuator that linearly drives a brake member by converting a rotary motion of an electric motor into a linear motion, and the electric linear actuator The brake member is disposed opposite to both sides of the braked member inside the caliper body to which the casing is fixed, and the brake member linearly driven by the electric linear actuator is pressed against the braked member. In this case, the electric linear actuator is rotatably supported by a carrier between a rotating shaft that transmits rotation from the rotor shaft of the electric motor and an outer ring member disposed on the outer diameter side of the rotating shaft. Each of these planetary rollers revolves while rotating around the rotation shaft as the rotation shaft rotates. In addition, a spiral protrusion is provided on the outer diameter surface of the rotating shaft or the inner diameter surface of the outer ring member, and the outer periphery of each planetary roller is fitted with a spiral protrusion at the same pitch as the spiral protrusion. Directional grooves or spiral grooves with the same pitch as the spiral ridges but with different lead angles are provided to fit the spiral ridges, and the width of the circumferential grooves or the side walls of the spiral grooves extends from the groove bottom side to the groove edge side. The side surface of the spiral ridge is inclined so that the width of the spiral ridge narrows from the base side to the top side, and at least one of the side walls of the inclined grooves and the side surface of the spiral ridge is inclined in the inclination direction. An electric linear actuator is used which is formed with a convex curved surface having a middle height, the spiral ridge is brought into contact with the circumferential groove or the side wall of the spiral groove only on one side surface thereof, and the groove bottom surface is not contacted. Adopted the configuration.

  That is, the side surface of the circumferential groove or the spiral groove of the planetary roller is inclined so that the groove width widens from the groove bottom side to the groove edge side, and the side surface of the spiral protrusion on the outer diameter surface of the rotating shaft or the inner diameter surface of the outer ring member Are inclined so that the width of the stripe narrows from the base side to the top side, so that when the spiral protrusion is fitted into the circumferential groove or the spiral groove, the spiral protrusion does not come into contact with the groove edge. By forming at least one of the inclined groove side wall and the side surface of the spiral ridge with a convex curved surface having a middle height in the tilt direction, the side surface of the spiral ridge fitted into these grooves is a middle high convex curved surface. It was made to contact | abut to the side wall of a groove | channel by the center part, and it was made not to contact | abut to the side wall of a groove | channel biased by the base side or the top part side.

  By making the convex curved surface an arc surface, the convex curved surface can be easily formed with high accuracy.

  By making the radius of curvature of the arc surface larger than the height of the spiral ridge, the contact area between the side surface of the spiral ridge and the circumferential groove or the side wall of the spiral groove is increased, and these contact surfaces The pressure can be reduced.

  By making the inclination angle of the side wall of the circumferential groove or the spiral groove equal to the inclination angle of the side surface of the spiral ridge, the base side or the top side of the side surface of the spiral ridge is reduced with a slight protrusion amount of the convex curved surface. It is possible to prevent the grooves from coming into contact with the side walls of the grooves.

  The spiral ridges provided on the outer diameter surface of the rotating shaft or the inner diameter surface of the outer ring member are formed by the strip members that surround the spiral grooves provided on the outer diameter surface of the rotating shaft or the inner diameter surface of the outer ring member. Thus, the spiral ridge can be easily formed with high accuracy.

  By forming the strip member by drawing a metal, it is possible to increase the strength by work hardening using an inexpensive metal material with few alloy components and to form the strip member at a high yield at a low cost. Further, if the strip member is wound in a spiral shape during the drawing process, it is possible to facilitate the circumferential attachment to the spiral groove.

  In the electric brake device of the present invention, the circumferential groove or the spiral groove side wall of the planetary roller is inclined so that the groove width extends from the groove bottom side to the groove edge side, and the outer diameter surface of the rotating shaft or the inner diameter of the outer ring member. The side surfaces of the spiral ridges of the surface are inclined so that the width of the ridges is narrowed from the base side to the top side, and at least one of the side walls of the inclined grooves and the side surfaces of the spiral ridges is a medium-height convex surface in the inclination direction. Therefore, when the spiral ridges are fitted into the circumferential grooves or the spiral grooves, contact with the groove edges of the spiral ridges can be prevented, and the spiral ridges fitted into these grooves can be prevented. It is possible to prevent the base side and the top side of the side surface from being biased to the side wall of the groove.

  By making the convex curved surface an arc surface, the convex curved surface can be easily formed with high accuracy.

  By making the radius of curvature of the arc surface larger than the height of the spiral ridge, the contact area between the side surface of the spiral ridge and the circumferential groove or the side wall of the spiral groove is increased, and these contact surfaces The pressure can be reduced.

  By making the inclination angle of the side wall of the circumferential groove or the spiral groove equal to the inclination angle of the side surface of the spiral ridge, the base side or the top side of the side surface of the spiral ridge is reduced with a slight protrusion amount of the convex curved surface. It is possible to prevent the grooves from coming into contact with the side walls of the grooves.

  The spiral ridges provided on the outer diameter surface of the rotating shaft or the inner diameter surface of the outer ring member are formed by the strip members that surround the spiral grooves provided on the outer diameter surface of the rotating shaft or the inner diameter surface of the outer ring member. Thus, the spiral ridge can be easily formed with high accuracy.

  By forming the strip member by drawing a metal, it is possible to increase the strength by work hardening using an inexpensive metal material with few alloy components and to form the strip member at a high yield at a low cost. Further, if the strip member is wound in a spiral shape during the drawing process, it is possible to facilitate the circumferential attachment to the spiral groove.

The longitudinal cross-sectional view which shows the electric linear actuator used for the electric brake device of embodiment 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. (A) is sectional drawing which expands and shows the spiral groove of the planetary roller of FIG. 1, and the spiral protrusion of an outer ring member, (b) is sectional drawing which shows the modification of (a). 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 used in this electric brake device is provided with a flange 1 b that projects so as to form a bowl shape on one end side of the cylindrical portion 1 a of the casing 1. The electric motor 2 is attached to the flange 1b in parallel with the cylindrical portion 1a, and 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 gears 3a, 3b, 3c. The three supported by the support shaft 6a of the carrier 6 are rotatably supported between the rotary shaft 4 and the outer ring member 5 fixed to the inner surface of the cylindrical portion 1a. Planetary rollers 7 are interposed, and each planetary roller 7 revolves while rotating around the rotating shaft 4 as the rotating shaft 4 rotates. In addition, between the adjacent planetary rollers 7, three fan-shaped lubricant application members 8 for applying grease as a lubricant are disposed in sliding contact with the outer diameter surfaces of the planetary rollers 7 on both sides. ing. Each lubricant application member 8 is housed in a bottomed partial cylindrical case 9 attached to the support shaft 6 a of the carrier 6.

  On the side of the casing 1 where the flange 1b is provided, there is provided a peripheral wall 1c that continues to the outer periphery including the cylindrical portion 1a and the flange 1b, and a lid 1d is attached to the peripheral wall 1c, and the gears 3a, 3b, 3c are The inner wall 1c and the lid 1d are arranged so as to mesh with each other within the same axial cross section. The rotary shaft 4 to which the gear 3c is attached is supported by a ball bearing 10 in a hole provided in the lid 1d, and the intermediate gear 3b that meshes with the gear 3a attached to the rotor shaft 2a and the gear 3c has a flange 1b and a lid 1d. Is supported by a ball bearing 12 on a shaft pin 11 passed to

  An annular groove 13 is provided in the inner diameter surface of the cylindrical portion 1a of the casing 1, and a stopper 14 that receives the axial reaction force of the linear motion actuator generated in the outer ring member 5 is fitted into the annular groove 13, and the inner diameter surface thereof. An annular holding member 15 is fixedly fitted on the inner diameter surface of the cylindrical portion 1a. The stopper 14 is divided into a plurality in the circumferential direction and can be easily fitted into the annular groove 13, and the holding member 15 is partially cut away in the circumferential direction so as not to interfere with the intermediate gear 3 b. .

  Each planetary roller 7 is supported by a support shaft 6 a of a carrier 6 fitted on the rotary shaft 4 so as to be rotatable by a needle roller bearing 16, and its rotation is supported by the carrier 6 by a thrust ball bearing 17. Further, a linear drive member 18 is supported by a thrust ball bearing 19 on the carrier 6 that revolves together with each planetary roller 7, and the linear motion of each planetary roller 7 is transmitted to the linear drive member 18 via the carrier 6. It has become.

  As shown in FIG. 4 (a), two spiral grooves 5a are provided on the inner surface of the outer ring member 5 to which the planetary rollers 7 are in rolling contact, and the strip members 5b are circumferentially attached to the spiral grooves 5a. Two spiral ridges are formed on the inner diameter surface of the outer ring member 5. The strip member 5b is formed by drawing a low carbon steel, and the strength is increased by work hardening.

  Further, as shown in FIG. 4B, the spiral ridge formed by the strip member 5b is fitted into the outer diameter surface of each planetary roller 7, and the lead angle is different at the same pitch as the spiral ridge. One spiral groove 7a is provided. 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 ridges shown in FIGS. 4 (a) and 4 (b) and the spiral direction of the spiral groove 7a seem to be opposite to each other, but the spiral ridges shown in FIG. 4 (a). Is screwed into the portion on the back side of the spiral groove 7a shown in FIG. 4 (b), so that the directions of the spirals are the same. Therefore, each planetary roller 7 that revolves while rotating around the rotation shaft 4 and whose spiral groove 7a is screwed with the spiral protrusion of the outer ring member 5 is caused by the difference in the lead angle between the spiral protrusion and the spiral groove 7a. Move linearly in the axial direction.

  As shown in an enlarged view in FIG. 5 (a), the spiral groove 7a on the outer diameter surface of the planetary roller 7 has inclined side walls so that the groove width extends from the groove bottom side to the groove edge side, and the strip member 5b. The spiral protrusions on the inner diameter surface of the outer ring member 5 formed by the steps are inclined at an angle equal to the inclination angle of the side wall of the spiral groove 7a so that the width of the spiral narrows from the base side to the top side. The side surface of the ridge is formed by an arcuate surface 5c that is middle and high in the tilt direction. A radius of curvature R1 of the circular arc surface 5c is formed larger than the height H of the spiral ridge. Accordingly, when the planetary roller 7 is in rolling contact with the inner surface of the outer ring member 5 and the spiral ridge of the outer ring member 5 is fitted into the spiral groove 7a having different lead angles of the planetary roller 7, the spiral ridge is formed into the spiral groove 7a. The side surface of the spiral ridge fitted into the spiral groove 7a is not biased against the side wall of the spiral groove 7a on the base side or the top side.

  FIG. 5B shows a modification of the spiral groove 7 a of the planetary roller 7 and the spiral ridges of the outer ring member 5. This modification is different in that both the side surfaces of the spiral ridges of the outer ring member 5 and the side walls of the spiral grooves 7a are formed by arcuate surfaces 5c and 7c that are middle and high in the inclination direction, respectively. Other portions are the same as those in the embodiment, and the radius of curvature R1 of the arc surface 5c and the radius of curvature R2 of the arc surface 7c are both formed larger than the height H of the spiral ridge. In addition, only the side wall of the spiral groove 7a can be formed by the circular arc surface 7c.

  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 18. In this figure, the electric linear actuator is shown in a cross section orthogonal to the cross section shown in FIG. 1, and the linear drive member 18 is locked to the pressing brake pad 23 by a key 24.

  In the embodiment described above, the spiral protrusion is provided on the inner diameter surface of the outer ring member, and the spiral groove having a different lead angle is provided on the outer diameter surface of the planetary roller. Circumferential grooves having the same pitch may be provided, and the spiral ridges may be provided on the outer diameter surface of the rotating shaft.

DESCRIPTION OF SYMBOLS 1 Casing 1a Cylindrical part 1b Flange 1c Perimeter wall 1d Lid 2 Electric motor 2a Rotor shaft 3a, 3b, 3c Gear 4 Rotating shaft 5 Outer ring member 5a Spiral groove 5b Strip member 5c Arc surface 6 Carrier 6a Support shaft 7 Planetary roller 7a Spiral groove 7c Arc surface 8 Lubricant application member 9 Case 10 Ball bearing 11 Axle pin 12 Ball bearing 13 Annular groove 14 Stopper 15 Holding member 16 Needle roller bearing 17 Thrust ball bearing 18 Linear drive member 19 Thrust ball bearing 21 Caliper body 22 Disc rotor 23 Brake pad 24 key

Claims (6)

An electric linear motion actuator that linearly drives the brake member by converting the rotational motion of the electric motor into a linear motion, and the caliper body in which the casing of the electric linear motion actuator is fixed is provided on both sides of the braked member. In the electric brake device in which the brake member is disposed so as to oppose and the brake member that is linearly driven by the electric linear actuator is pressed against the braked member,
The electric linear actuator is rotatably supported by a carrier between a rotating shaft that transmits rotation from the rotor shaft of the electric motor and an outer ring member disposed on the outer diameter side of the rotating shaft. A plurality of planetary rollers are interposed so that each of the planetary rollers revolves while rotating around the rotation shaft as the rotation shaft rotates, and the outer diameter surface of the rotation shaft or the inner diameter surface of the outer ring member A spiral groove on the outer diameter surface of each 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. A spiral groove into which the strip is fitted is provided, and the side wall of the circumferential groove or the spiral groove is inclined so that the groove width spreads from the groove bottom side to the groove edge side. Inclined to narrow from side to top And forming at least one of the side walls of the inclined grooves and the side surfaces of the spiral ridges with a convex curved surface having a middle height in the inclined direction, and the spiral ridges on the circumferential grooves or spirals only on one side surface thereof. An electric brake device using an electric linear actuator that is in contact with a side wall of the groove and is not in contact with the bottom surface of the groove.   The electric brake device according to claim 1, wherein the convex curved surface is an arc surface.   The electric brake device according to claim 2, wherein a radius of curvature of the arc surface is larger than a height of the spiral protrusion.   The electric brake device according to any one of claims 1 to 3, wherein an inclination angle of a side wall of the circumferential groove or the spiral groove is equal to an inclination angle of a side surface of the spiral protrusion.   The spiral protrusion provided on the outer diameter surface of the rotating shaft or the inner diameter surface of the outer ring member is formed by a strip member that is attached to a spiral groove provided on the outer diameter surface of the rotating shaft or the inner diameter surface of the outer ring member. Item 5. The electric brake device according to any one of Items 1 to 4.   The electric brake device according to claim 5, wherein the strip member is formed by drawing a metal.

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