JP2012241825A - Electric linear actuator and electric disk brake device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely transmit the rotation of a rotary shaft to each of a plurality of planetary rollers without loss.SOLUTION: An electric linear actuator is configured as follows. An even number of planetary rollers 21 is incorporated between the inner-diameter surface of an outer ring member 5 and the outer-diameter surface of a rotary shaft 10. The same number of roller shafts 19 as that of the planetary rollers 21 is provided in a carrier 14 rotatable centering around the rotary shaft 10. Each roller shaft 19 freely rotatably supports each of the planetary rollers 21. The pair of roller shafts 19 circumferentially adjacent to each other is made as a set. An extension coil spring 23 is stretched between the pair of roller shafts 19, becoming the set, so as to circumferentially bias the pair of roller shafts 19. Then, each spiral groove 22 formed on the outer periphery of each of the planetary rollers 21 is brought into pressure contact with flanks 6a, 6b on both sides of a spiral protrusion 6 formed on the inner periphery of the outer ring member 5 in order to be engaged with each spiral groove 22. The roller shafts 19 are biased to the radial inside by the radial component force of the reaction force against the contact pressure in order to bring the planetary rollers 21 into pressure contact with the outer diameter surface of the rotary shaft 10.

Description

  The present invention relates to an electric linear actuator that linearly drives a driven member such as a brake pad, and an electric disc brake device using the electric linear actuator.

  In an electric linear actuator that uses an electric motor as a drive source, the rotational motion of the rotor shaft of the electric motor is converted into a linear motion of a driven member that is supported by a motion conversion mechanism so as to be movable in the axial direction. .

  Ball screw mechanisms and ball ramp mechanisms are known as motion conversion mechanisms employed in electric linear actuators. Although these motion conversion mechanisms have a certain degree of boosting function, electric disk brake devices, etc. It is not possible to secure a large boosting function as required by the company.

  Therefore, in the electric linear actuator that employs the motion conversion mechanism as described above, a reduction mechanism such as a planetary gear mechanism is separately incorporated to increase the driving force. There is a problem that the configuration is complicated and the electric linear actuator is enlarged.

  In order to solve such problems, the applicant of the present application can secure a large boosting function without incorporating a speed reduction mechanism, and is suitable for use in an electric disc brake device having a relatively small linear motion stroke. Japanese Patent Application Laid-Open No. H10-228688 has already proposed a linear actuator.

  In the electric linear actuator described in Patent Document 1, a plurality of planetary rollers are incorporated between a rotating shaft that is rotationally driven by an electric motor and an outer ring member that is provided outside the rotating shaft. Each of the plurality of planetary rollers is rotatably supported by a carrier that can rotate around a rotation axis, and the rotation of the rotation shaft causes the planetary roller to revolve while rotating by frictional contact with the rotation shaft. The outer ring member and the carrier are relatively linearly moved in the axial direction by meshing between the spiral groove or the circumferential groove formed on the outer diameter surface of the roller and the spiral protrusion provided on the inner diameter surface of the outer ring member. .

  Here, when the planetary roller is assembled with a negative fitting clearance between the outer diameter surface of the rotating shaft and the inner diameter surface of the outer ring member, there is a problem that the assembling takes time and costs increase. Therefore, in order to solve such problems, in the electric linear actuator described in Patent Document 1, a roller shaft that rotatably supports a plurality of planetary rollers is supported by a carrier so as to be movable in a radial direction. Each of the plurality of roller shafts is urged radially inward by an elastic member so that each of the planetary rollers is in elastic contact with the outer diameter surface of the rotating shaft.

JP 2009-197863 A

  By the way, in the electric linear actuator described in Patent Document 1, a C-shaped ring is employed as an elastic member, and each roller shaft is radially inward as a built-in that circumscribes the C-shaped ring to a plurality of roller shafts. Although the C-shaped ring has a feature that the cost is low, since it is manufactured by bending spring steel, a ring having excellent roundness cannot be obtained. For this reason, the spring load cannot be uniformly applied to a plurality of planetary rollers, and there is a possibility that slip occurs at the contact portion between the rotating shaft and the planetary roller, causing the rotating shaft to idle. The point which should be improved in aiming at the improvement of rotation transmission efficiency was left.

  Further, in the above-mentioned Patent Document 1, an embodiment in which each of a plurality of planetary rollers is individually pressed against a rotation shaft by a compression coil spring is shown, but a large space is ensured for accommodating the compression coil spring. I can't. For this reason, a large pressing force cannot be applied to each of the planetary rollers, and in this case as well, there are still points to be improved in order to improve the rotation transmission efficiency to the planetary rollers. It had been.

  An object of the present invention is an electric linear motion in which a planetary roller is rotated and revolved by contact rotation with a rotating shaft, and a carrier supporting the planetary roller and an outer ring member are relatively moved in an axial direction. In the actuator, the rotation of the rotary shaft can be reliably transmitted to each of the plurality of planetary rollers without loss.

  In order to solve the above-mentioned problems, in the electric linear actuator according to the present invention, an outer ring member is incorporated in a cylindrical housing, and the rotation is driven on the axis of the outer ring member by using an electric motor as a drive source. An even number of planetary rollers are assembled between the outer diameter surface of the rotating shaft and the inner diameter surface of the outer ring member, and the same number of roller shafts as the planetary rollers that rotatably support each of the even number of planetary rollers, and Cross sections provided on the outer diameter surface of the outer ring member on the outer diameter surface of the planetary roller, respectively, supporting a carrier having a disk that supports the shaft end of each roller shaft so as to be rotatable about the rotation shaft. An outer ring member is formed by forming a spiral groove or a circumferential groove meshing with a V-shaped spiral ridge, rotating the rotating shaft, and rotating and revolving a plurality of planetary rollers by frictional contact with the rotating shaft. In the electric linear actuator that moves relative to the carrier in the axial direction, the shaft insertion hole formed in the disk of the carrier is sized so that the roller shaft can be inserted with a margin, and supports the planetary roller. A groove formed on the outer periphery of the planetary roller by energizing the pair of roller shafts in the circumferential direction between a pair of adjacent roller shafts and an even number of roller shafts. The structure which incorporated the elastic member which press-contacts this flank to the flank of a spiral protrusion was employ | adopted.

  Further, in the electric disc brake device according to the present invention, the brake pad is linearly driven by the electric linear actuator, and the brake disc is pressed by the brake pad to apply a braking force to the brake disc. In the electric disc brake device, a configuration using the electric linear actuator according to the present invention is adopted as the electric linear actuator.

  In the electric linear actuator having the above-described configuration, an elastic member is incorporated between a pair of roller shafts, and the pair of roller shafts is biased in the circumferential direction by the elastic member. The groove flank formed on the outer periphery of the planetary roller supported by the outer ring member can be brought into pressure contact with the spiral protrusion flank provided on the inner periphery of the outer ring member. At this time, since the spiral protrusion has a lead angle, a component force directed radially inward acts on the planetary roller, and the planetary roller moves radially inward by the radial component force, It will come into strong contact with the outer diameter surface of the rotating shaft.

  As a result, when the rotating shaft is rotated by driving the electric motor, the rotation of the rotating shaft is reliably transmitted to each of the plurality of planetary rollers without loss, and the planetary roller revolves while rotating. One of the outer ring member and the carrier linearly moves in the axial direction by the engagement of the spiral groove or circumferential groove formed on the outer diameter surface of the outer ring member and the spiral protrusion provided on the inner diameter surface of the outer ring member.

  For this reason, by connecting the brake pad of the electric disc brake device to one member that linearly moves in the axial direction among the outer ring member and the carrier, the brake pad can be linearly driven and pressed against the brake disc. A braking force can be applied to the brake disc.

  Here, by providing the elastic member between the shaft end portions where the pair of roller shafts penetrates the carrier and is located outside, a large space can be secured for the incorporation of the elastic member, and the elastic member having a large spring constant can be secured. Can be incorporated.

  The elastic member may be a tension spring or a compression spring. An M-shaped thin plate having a pair of engagement pieces locked to a tension coil spring or a pair of roller shafts at both ends as an extension spring, and an inwardly bent portion formed between the pair of engagement pieces A spring or wirework spring can be employed.

  On the other hand, as a compression spring, there is a pair of engagement pieces locked to a compression coil spring or a pair of roller shafts at both ends, and an M-shape in which an inward bending portion is formed between the pair of engagement pieces A thin plate spring or a wire-work spring can be employed.

  In the present invention, as described above, the pair of roller shafts is formed on the outer periphery of the planetary roller rotatably supported by each of the pair of roller shafts by urging the pair of roller shafts in the circumferential direction by the elastic member. Since the flank of the groove is brought into pressure contact with the flank of the spiral ridge having a lead angle, the planetary roller can be moved radially inward to make strong contact with the outer diameter surface of the rotating shaft. As a result, the rotation of the rotation shaft can be reliably transmitted to each of the plurality of planetary rollers without loss, and an electric linear actuator having excellent rotation transmission efficiency can be provided.

A longitudinal sectional view showing an embodiment of an electric linear actuator according to the present invention Sectional drawing which expands and shows a part of FIG. Sectional view along line III-III in FIG. Sectional view along line IV-IV in FIG. (a) is a development view showing a contact portion between the spiral ridge and the planetary roller, (b) is a right side view of (a). Sectional drawing which shows the other example of an elastic member Sectional drawing which shows another example of an elastic member Sectional drawing which shows another example of an elastic member A longitudinal sectional view showing an embodiment of an electric disc brake device according to the present invention

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows an embodiment of an electric linear actuator according to the present invention. The electric linear actuator A shown in this embodiment has a cylindrical housing 1, and a base plate 2 projecting radially outward is provided at one end of the housing 1, and an outer surface of the base plate 2. Is covered by a cover 3 bolted to one end of the housing 1.

  An outer ring member 5 is incorporated in the housing 1. The outer ring member 5 is prevented from rotating and is movable in the axial direction along the inner diameter surface of the housing 1, and a spiral protrusion 6 having a V-shaped cross section is provided on the inner diameter surface as shown in FIG. ing.

  As shown in FIG. 1, a bearing member 7 is incorporated in the housing 1 on one end side in the axial direction of the outer ring member 5. The bearing member 7 has a disk shape, and a boss portion 7a is provided at the center thereof. The bearing member 7 is prevented from moving toward the cover 3 by a retaining ring 8 attached to the inner diameter surface of the housing 1.

  A pair of rolling bearings 9 is incorporated in the boss portion 7a of the bearing member 7 with an interval in the axial direction, and the rotating shaft 10 disposed on the axis of the outer ring member 5 is rotatably supported by the rolling bearing 9. Has been.

  An electric motor 11 is supported on the base plate 2 of the housing 1, and the rotation of the rotor shaft 12 of the electric motor 11 is transmitted to the rotating shaft 10 by a gear reduction mechanism 13 incorporated in the cover 3. .

  A carrier 14 that is rotatable about the rotation shaft 10 is incorporated inside the outer ring member 5. As shown in FIG. 2 and FIG. 3, the carrier 14 has a pair of discs 14a and 14b facing each other in the axial direction, and a pair of discs 14a is provided by a plurality of interval adjusting column portions 15 provided on one disc 14b. , 14b is kept constant.

  The carrier 14 is supported by a slide bearing 16 incorporated in the inner surface of the pair of disks 14a and 14b so as to be rotatable about the rotary shaft 10 and slidable in the axial direction. The retaining ring 17 attached to the portion prevents the rotating shaft 10 from coming off the shaft end.

  In each of the pair of disks 14a and 14b in the carrier 14, four pairs of shaft insertion holes 18 opposed in the axial direction are formed at an interval of 90 ° in the circumferential direction. A shaft end portion of the roller shaft 19 is inserted into each of 18. Each roller shaft 19 is fitted with a pair of opposed bearings 20, and planetary rollers 21 are rotatably supported by the bearings 20.

  The number of roller shafts 19 is not limited to four and may be an even number of four or more.

  A spiral groove 22 is formed on the outer diameter surface of the planetary roller 21 at the same pitch as that of the spiral protrusion 6 provided on the outer ring member 5, and the spiral protrusion 6 is engaged with the spiral groove 22. . In place of the spiral groove 22, a plurality of circumferential grooves may be formed at the same pitch as the pitch of the spiral ridge 6.

  Here, the shaft insertion hole 18 formed in the pair of disks 14a and 14b is sized so that the shaft end portion of the roller shaft 19 can be inserted with a margin, and a gap is provided between the roller shaft 19 and the gap. Within this range, the roller shaft 19 is movable.

  Both end portions of the roller shaft 19 penetrate the disks 14a and 14b, and end portions located outside from the outer surfaces of the disks 14a and 14b are small diameter shaft portions 19a. In the four roller shafts 19 provided at an interval of 90 ° in the circumferential direction, a pair of roller shafts 19 adjacent in the circumferential direction is a set, and the small-diameter shaft portion 19a of the pair of roller shafts 19 forming the set. As shown in FIG. 4, a tension coil spring 23 as an elastic member is stretched between them.

The tension coil spring 23 urges the pair of roller shafts 19 in the circumferential direction so that a pair of roller shafts 19 adjacent in the circumferential direction approach each other, and a pair of planetary rollers paired by the urging. one of the planetary rollers 21 of 21, FIG. 5 (a), the contact by T ₁ with respect to each side flanks 6a, one flank 6a and 6b of the helical ridge 6 (b), the addition, the other planetary rollers 21 are in contact with _{T 2} relative to the other flank 6b.

  At this time, since the spiral protrusion 6 is provided with a lead angle, each of the pair of planetary rollers 21 as a pair moves radially inward along the flank 6a, 6b and moves outside the rotating shaft 10. Strong contact with the radial surface.

  As shown in FIG. 2, a thrust bearing 24 is incorporated between the opposed surfaces of the inner disk 14 a located on the bearing member 7 side and the planetary roller 21 among the pair of disks 14 a and 14 b of the carrier 14.

  In addition, an annular support member 25 and a thrust bearing 26 are incorporated between the opposed surfaces of the inner disk 14 a and the bearing member 7 in the carrier 14, and the thrust bearing 26 is loaded on the carrier 14 and the support member 25. It is designed to receive axial thrust loads.

  A circular recess 27 is formed on the support member 25 on the surface facing the inner disk 14 a, and the aforementioned tension coil spring 23 is accommodated in the circular recess 27.

  The opening at the other end located outside the end opening of the housing 1 of the outer ring member 5 is closed by attaching the seal cover 29 to prevent foreign matter from entering the inside. On the other hand, the other end opening of the housing 1 is blocked by a boot 30 attached between the other end and the other end of the outer ring member 5 to prevent foreign matter from entering the inside.

  The electric linear actuator A shown in the embodiment has the above structure, and FIG. 9 shows an electric disc brake device B that employs the electric linear actuator A. In the electric disc brake device B, a caliper body portion 41 is integrally provided at the other end portion of the housing 1 in the electric linear actuator A, and a brake having a part of the outer peripheral portion disposed in the caliper body portion 41. A fixed brake pad 43 and a movable brake pad 44 are provided on both sides of the disk 42, and the movable brake pad 44 is connected and integrated with the other end of the outer ring member 5.

  In the state of use of the electric linear actuator A to the electric disc brake device B as shown in FIG. 9, when the rotary shaft 10 is rotated by driving the electric motor 11 shown in FIG. 1, frictional contact with the rotary shaft 10 occurs. The planetary roller 21 revolves while rotating.

  At this time, the spiral groove 22 is formed on the outer diameter surface of the planetary roller 21, and the spiral protrusion 6 provided on the inner diameter surface of the outer ring member 5 is engaged with the spiral groove 22. The outer ring member 5 moves in the axial direction by rotation and revolution, the movable brake pad 44 is pressed against the brake disc 42, and a braking force is applied to the brake disc 42.

  In the electric linear actuator shown in FIGS. 1 to 4, a roller shaft 19 that rotatably supports the planetary roller 21 and a roller shaft 19 that is adjacent to the roller shaft 19 in the circumferential direction are paired, and a pair of rollers constituting the pair. The tension coil spring 23 is stretched between the small-diameter shaft portions 19a of the shaft 19, and the pair of roller shafts 19 are urged in the circumferential direction so that the pair of roller shafts 19 approach each other. As shown in (b), the flank on both sides of the spiral groove 22 formed on the outer periphery of the planetary roller 21 is brought into pressure contact with the flank 6a, 6b of the spiral protrusion 6 provided on the inner periphery of the outer ring member 5. it can. At this time, since the spiral protrusion 6 has a lead angle, a component force directed inward in the radial direction of the reaction force against the pressure contact force acts on the planetary roller 21, and the planetary roller is caused by the radial component force. 21 moves radially inward and makes strong contact with the outer diameter surface of the rotary shaft 10.

  Therefore, no slip occurs at the contact portion between the rotating shaft 10 and the plurality of planetary rollers 21, and the rotation of the rotating shaft 10 is reliably transmitted to each of the plurality of planetary rollers 21 without loss. The outer ring member 5 is surely linearly driven, and the electric linear actuator A is not disabled.

  In FIG. 4, the tension coil spring 23 is employed as an elastic member that is spanned between the small-diameter shaft portions 19 a of the pair of roller shafts 19 and urges each roller shaft 19 in the circumferential direction. It is not limited to the tension coil spring 23.

  6 to 8 show other examples of the elastic member. In FIG. 6, a pair of engaging pieces 31a engaged with the small diameter shaft portions 19a of the pair of roller shafts 19 are provided at both ends, and an inwardly bent portion 31b is formed between the pair of engaging pieces 31a. A thin plate spring 31 made of an M-shaped spring steel plate is used as an elastic member, and the thin plate spring 31 is spanned between the small-diameter shaft portions 19a of the pair of roller shafts 19. Instead of the thin plate spring 31, a wire work spring obtained by bending a steel wire into an M shape may be adopted.

  In FIG. 7, the compression coil spring 32 as a compression spring is used as an elastic member, and the compression coil spring 32 is assembled between the small-diameter shaft portions 19a of the pair of roller shafts 19 to form the pair of roller shafts 19 in the circumferential direction. The flank of the spiral groove 22 formed on the outer periphery of the planetary roller 21 is pressed against the flank of the spiral protrusion 6, and the planetary roller 21 is removed from the rotary shaft 10 by the radial component of the reaction force against the pressure. It is made to press against the radial surface.

  In FIG. 8, a pair of engaging pieces 33a engaged with the small diameter shaft portions 19a of the pair of roller shafts 19 are provided at both ends, and an inwardly bent portion 33b is formed between the pair of engaging pieces 33a. A thin plate spring 33 made of an M-shaped spring steel plate as a compression spring is used as an elastic member, and the thin plate spring 33 is assembled between the small-diameter shaft portions 19a of the pair of roller shafts 19 so that the pair of roller shafts 19 is surrounded. The flank of the spiral groove 22 formed on the outer periphery of the planetary roller 21 is pressed against the flank of the spiral ridge 6, and the planetary roller 21 is rotated by the radial component of the reaction force against the pressure. It is made to press-contact with the outer diameter surface of. In place of the thin plate spring 33, a wire work spring obtained by bending a steel wire into an M shape may be adopted.

  In any of the elastic members shown in FIGS. 6 to 8, the planetary roller 21 can be brought into strong elastic contact with the outer diameter surface of the rotary shaft 10, and the rotation of the rotary shaft 10 can be reliably transmitted to each of the plurality of planetary rollers 21. can do.

  In the embodiment, the outer ring member 5 is moved in the axial direction by the rotation and revolution of the planetary roller 21, but the outer ring member 5 may be fixed and the carrier 14 may be moved in the axial direction.

A Electric linear actuator B Electric disc brake device 1 Housing 5 Outer ring member 6 Spiral protrusion 6a, 6b Flank 10 Rotating shaft 11 Electric motor 14 Carrier 21 Planetary roller 22 Spiral groove 23 Tension coil spring (elastic member)
31 Thin leaf spring (elastic member)
31a Engagement piece 31b Bending part 32 Compression coil spring (compression spring)
33 Thin leaf spring (compression spring)
51 Brake disc 53 Movable brake pad (brake pad)

Claims (8)

An outer ring member is assembled in a cylindrical housing, and a rotary shaft that is driven to rotate by using an electric motor as a drive source is provided on the axis of the outer ring member. Between the outer diameter surface of the rotary shaft and the inner diameter surface of the outer ring member. An even number of planetary rollers are incorporated, and a carrier having the same number of planetary rollers as the planetary rollers that rotatably supports each of the even number of planetary rollers and a disk that supports the shaft end portion of each roller shaft. A spiral groove or a circumferential groove that is rotatably supported around the center and meshes with a spiral protrusion having a V-shaped cross section provided on an inner diameter surface of the outer ring member is formed on each outer diameter surface of the planetary roller, An electric linear actuator that rotates a rotating shaft and rotates and revolves a plurality of planetary rollers by frictional contact with the rotating shaft to move the outer ring member and the carrier relatively in the axial direction. Stomach,
The shaft insertion hole formed in the disk of the carrier is sized to allow the roller shaft to be inserted with a margin, and an even number of roller shafts that support the planetary roller are made into a pair of adjacent roller shafts. An elastic member is incorporated between the pair of roller shafts to urge the pair of roller shafts in the circumferential direction to press the flank of the groove formed on the outer periphery of the planetary roller to the flank of the spiral protrusion. Electric linear actuator.   2. The electric linear actuator according to claim 1, wherein the elastic member includes a tension spring whose ends are locked to shaft end portions of a pair of roller shafts.   The electric linear motion actuator according to claim 2, wherein the tension spring is a tension coil spring.   The tension spring has a pair of engagement pieces locked to the pair of roller shafts at both ends, and an M-shaped thin plate spring in which an inward bending portion is formed between the pair of engagement pieces, or The electric linear actuator according to claim 2, comprising a wire work spring.   The electric linear actuator according to claim 1, wherein the elastic member includes a compression spring whose ends are locked to shaft end portions of a pair of roller shafts.   The electric linear actuator according to claim 5, wherein the compression spring is a compression coil spring.   The compression spring has an M-shaped thin plate spring having a pair of engaging pieces locked to the pair of roller shafts at both ends and an inwardly bent portion formed between the pair of engaging pieces, or 6. The electric linear actuator according to claim 5, comprising a wire work spring. In the electric disc brake device in which the brake pad is linearly driven by the electric linear actuator, the brake disc is pressed with the brake pad, and braking force is applied to the brake disc.
The electric disk brake device, wherein the electric linear actuator comprises the electric linear actuator according to any one of claims 1 to 7.

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