WO2017018338A1 - Electric linear actuator and electric brake device - Google Patents

Abstract

The present invention is an electric linear actuator, wherein: a gear case (30) for housing a gear speed reducer (41) is molded from a reinforcing fiber-containing resin; between a gear support section (39) and another gear support section (48), and between yet another gear support section (49) and still another different gear support section (51), ribs (52, 54) for connecting said gear support sections, which are for supporting gears in the gear case (30), are respectively provided; the resin reinforcing fibers are oriented parallel to the directions in which said ribs (52, 54) extend; and the linear expansion coefficients between the gear support section (39) and the other gear support section (48), and between the yet another gear support section (49) and still another different gear support section (51) are made to approach the linear expansion coefficient of the gears of the gear speed reducer (41) to prevent the occurrence of changes in gear meshing due to temperature changes.

Description

Electric linear actuator and electric brake device

The present invention relates to an electric linear actuator and an electric brake device that linearly drive a brake pad of a brake device.

2. Description of the Related Art Conventionally, an electric linear actuator that linearly drives a brake pad in an electric brake device is described in Patent Document 1 below. In the electric linear actuator described in Patent Document 1, one end portion of a gear case is connected to an inner side end portion on the vehicle body side of a caliper housing in which a linear motion member for pressing a brake pad is incorporated. The rotation of the rotor shaft of the electric motor supported by the other end is decelerated by a gear reduction mechanism incorporated in the gear case, and the rotation of the output gear of the gear reduction mechanism is reduced by the rotation / linear motion conversion mechanism. Converted into linear motion, the brake pad is pressed against the brake disc by the linear motion member.

In the above-described electric linear actuator used in the electric brake device, it is easily affected by heat generated by frictional contact of the brake pad with the brake disc, and the heat is transmitted to the electric motor via the gear case. When transmitted, the magnet of the electric motor may be demagnetized, and thus the gear case is formed of a synthetic resin having low thermal conductivity instead of metal.

Also, since the electric linear actuator is mounted under the spring of the suspension mechanism, the gear case is often made of resin from the viewpoint of reducing the unsprung weight.

Here, since the linear expansion coefficient of the gear case made of resin is different from that of the gear made of metal, when the gear case or the gear thermally expands due to a change in the ambient temperature, the center axis of the gear support portion that rotatably supports the gear There is a large difference between the linear expansion amount of the gear and the linear expansion amount of the pitch circle diameter of the gear, a change occurs in the gear backlash, noise is generated, and the torque transmission efficiency of the gear reduction mechanism decreases.

By the way, in the following Patent Document 2, even when a metal core resin gear in which a resin outer peripheral portion formed with teeth meshing with a drive gear is supported by a metal cylindrical portion is used as a driven gear, Based on the linear expansion coefficient of gears, driven gears and housings, tooth height, and distance between gear shafts, the thickness of the resin part is set appropriately, and even if the ambient temperature changes, the positional relationship between the gears remains unchanged, A technique for making backlash substantially unchanged has been proposed.

Further, in Patent Document 3 below, a pitch circle circle having substantially the same diameter as the pitch circle diameter of each gear is provided on each side of the resin gear and the motor gear meshing therewith, and the motor gear is pressed against the resin gear by a spring. A technique has been proposed in which the spring absorbs fluctuations in the inter-axis distance due to temperature changes and makes the inter-axis distance constant.

Therefore, it is conceivable to solve the problem in the case where the gear case of the electric linear motion actuator is made of resin by employing the techniques described in Patent Documents 2 and 3 above.

Japanese Patent Laying-Open No. 2015-52341 JP 2004-338712 A JP 2005-258316 A

By the way, the electric linear actuator is mounted under the spring of the suspension mechanism and is used in extremely severe environments affected by vibration and muddy water. Since the shortage causes a problem in durability, it is necessary to mold with a resin containing reinforcing fibers.

In the resin containing reinforcing fibers, the linear expansion coefficient is significantly different between the orientation direction of the reinforcing fibers and the direction perpendicular thereto. In the technique described in Patent Document 2, there is no description about the orientation of the reinforcing fibers, and When the resin is employed, the positional relationship between the gears varies greatly depending on the orientation, noise is generated, or torque transmission efficiency is reduced. For this reason, when the gear case is made of resin containing reinforcing fibers, the technique of Patent Document 2 cannot be adopted.

On the other hand, in Patent Document 3, the backlash of the gear is reduced to 0 by absorbing the fluctuation of the distance between the shafts due to the temperature change by the spring pressing the motor gear against the resin gear. However, the gear expands greatly in the radial direction under high temperature use environment. Therefore, a force in a direction to further reduce the backlash acts, and the frictional force between the gears increases, and the torque transmission efficiency of the gear reduction mechanism deteriorates. For this reason, there is a problem in adopting the technique described in Patent Document 3.

The problem of the present invention is that even when the gear case that houses the gear reduction mechanism of the electric linear actuator is formed of resin containing reinforcing fiber, the positional relationship between the gears is not changed significantly due to temperature change. It is to be able to maintain a proper meshing state.

In order to solve the above problems, in the electric linear actuator according to the present invention, an electric motor, a gear reduction mechanism including a metal gear that decelerates and outputs the rotation of the rotor shaft of the electric motor, A rotation / linear motion converting mechanism for converting the rotation of the output gear of the gear speed reducing mechanism into a linear motion of a linear motion member incorporated in the housing, and the gear case that houses the gear speed reducing mechanism is made of resin. In the dynamic actuator, a resin as a material for forming the gear case is made of reinforced fiber, a rib connecting the gear support portion is provided between the gear support portions supporting the gear of the gear case, and the rib extends in parallel with the extending direction. A configuration in which resin reinforcing fibers are oriented is employed.

As described above, a high-strength and durable gear case can be obtained by using reinforced fibers as the gear case forming material.

Also, ribs connecting the gear support portions are provided between the gear support portions that support the gears of the gear case, and the resin reinforcing fibers are oriented parallel to the direction in which the ribs extend, so that the linear expansion in the rib length direction is achieved. The coefficient is close to the metal linear expansion coefficient.

At this time, since the rib is provided so as to connect the gear support portion, the difference between the linear expansion amount between the gear support portions and the linear expansion amount in the radial direction of the gear is extremely small, and a temperature change occurs. Even in this case, the gears maintain an appropriate meshing state without any change in backlash, and no noise is generated and the torque transmission efficiency of the gear reduction mechanism is not reduced.

In the electric linear actuator according to the present invention, the gear case includes a case main body provided with a peripheral wall on the bottom plate, and a lid that closes the opening of the peripheral wall of the case main body. You may support so that rotation is possible. In this case, a rib is provided between the gear support portions formed on the bottom plate and the lid of the case body.

Here, when a gate is provided at one end of the rib, the molten resin injected from the gate flows from one end of the rib toward the other end, and the resin flow direction is parallel to the length direction of the rib. It becomes.

At this time, since the direction of the reinforcing fiber depends on the flow direction of the resin, the direction of the reinforcing fiber is also parallel to the length direction of the rib, and the reinforcing fiber can be oriented parallel to the direction in which the rib extends.

The reinforcing fiber in the resin containing reinforcing fiber may be glass fiber or carbon fiber.

In the electric 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 apparatus, the electric linear actuator is composed of the electric linear actuator described above, and the brake pad is linearly driven by the linear member of the electric linear actuator.

In the present invention, as described above, since the gear case is formed of the resin containing the reinforcing fibers, a gear case having high strength and excellent durability can be obtained.

In addition, by providing ribs between the gear support portions that support the gears of the gear case and orienting resin reinforcing fibers parallel to the direction in which the ribs extend, the linear expansion coefficient in the length direction of the ribs is changed to the metal linear expansion coefficient. Can be approached. As a result, the difference between the linear expansion amount between the gear support parts and the linear expansion amount in the radial direction of the gear is extremely small, and even when the temperature changes, the gears are properly meshed so that the backlash does not change. The state can be maintained, and generation of noise and reduction in torque transmission efficiency of the gear reduction mechanism can be suppressed.

The longitudinal cross-sectional view which shows embodiment of the electric brake device which employ | adopted the electric linear motion actuator which concerns on this invention Sectional drawing which expands and shows the gear case part of FIG. Sectional view along line III-III in FIG. Right side view of the gear case shown in FIG. 1 with the lid removed. Sectional view along line VV in FIG. Front view showing the case body of the gear case Sectional view along line VI-VI in FIG. 6A Front view showing the lid of the gear case Sectional view along line VII-VII in FIG. 7A Rear view showing another example of the case body of the gear case Sectional view along line VIII-VIII in FIG. 8A Rear view showing another example of lid of gear case Sectional view along line IX-IX in Fig. 9A

Hereinafter, embodiments of the present invention will be described with reference to the drawings. As shown in FIGS. 1 and 4, the electric brake device includes a brake disk 10 that rotates integrally with a wheel (not shown), and a caliper 11 provided on the outer periphery of the brake disk 10.

The caliper 11 has a configuration in which a claw portion 13 that is axially opposed to the outer peripheral portion of the outer side surface of the brake disc 10 is provided at the outer end portion of the cylindrical caliper housing 12 disposed on the inner side of the brake disc 10. The outer brake pad 14 is supported by the claw portion 13. Note that the inner side of the vehicle body is referred to as the inner side and the side surface of the vehicle body is referred to as the outer side with the electric brake device attached to the vehicle body.

An inner brake pad 15 is disposed opposite to the outer peripheral portion of the inner side surface of the brake disc 10, and the inner brake pad 15 is moved toward the brake disc 10 by an electric linear actuator 20 provided in the caliper housing 12. The

A mount 16 is provided on the outer periphery of the inner side surface of the brake disc 10. The mount 16 is fixed to a knuckle (not shown), and as shown in FIG. 4, slide pins 18 extending in a direction orthogonal to the brake disk 10 are provided on each of a pair of opposed pin support pieces 17 provided on both sides thereof. The caliper 11 is slidably supported by each of the slide pins 18.

Although not shown in detail in the drawing, the mount 16 is supported so as to be movable toward the brake disc 10 in a state in which each of the outer side brake pad 14 and the inner side brake pad 15 is non-rotatable (non-rotating). is doing.

As shown in FIG. 1, the electric linear actuator 20 has an outer ring member 21 as a linear member incorporated in a caliper housing 12 as a housing. The outer ring member 21 has a cylindrical shape, and the opening at the outer side end is closed by attaching a cap 22. The outer ring member 21 is supported by the caliper housing 12 so as to be slidable in the axial direction, and is prevented from rotating with respect to the inner brake pad 15 as will be described later.

A shaft support member 23 is incorporated in the caliper housing 12 from the inner side end of the outer ring member 21. The shaft support member 23 has a disk shape, and a boss portion 23a is provided at the center thereof.

An annular protrusion 24 is provided on the inner periphery of the inner end of the caliper housing 12 on the vehicle body side, and the annular protrusion 24 prevents the shaft support member 23 from coming out of the inner end of the caliper housing 12. ing.

A pair of rolling bearings 25 are incorporated in the boss portion 23a of the shaft support member 23 at intervals in the axial direction, and the rotating shaft 26 disposed on the axis of the outer ring member 21 is rotatable by the rolling bearings 25. It is supported.

As shown in FIGS. 2 and 5, a motor support plate 27 is provided at the inner end of the caliper housing 12. As shown in FIG. 5, a head fitting hole 28 is provided at the other end of the motor support plate 27, and a small-diameter head 29 a of an electric motor 29 is fitted into the head fitting hole 28. An electric motor 29 is supported at the other end portion of 27.

Further, as shown in FIGS. 2 and 5, a gear case 30 is provided on the inside surface of the motor support plate 27. The gear case 30 includes a case body 31 and a lid 34. The case body 31 has a configuration in which a peripheral wall 33 is provided on one outer peripheral portion of the bottom plate 32, and the opening of the peripheral wall 33 is closed by attaching a lid 34.

At the time of attaching the lid 34, here, a fitting groove 35 is formed on the opening end surface of the peripheral wall 33. On the other hand, the lid 34 is provided with a protruding portion 36 on one outer peripheral portion, and the protruding portion 36 is formed in the fitting groove 35. Although fitted, the attachment of the lid 34 is not limited to this. For example, it may be screwed.

A plurality of bolt insertion holes 37 a are formed on the outer periphery of the peripheral wall 33 in the bottom plate 32 of the case body 31. On the other hand, the motor support plate 27 is provided with screw holes 37b at positions facing the respective bolt insertion holes 37a, and the case main body is attached to the motor support plate 27 by tightening the bolts 38 screwed into the screw holes 37b from the bolt insertion holes 37a. 31 is attached.

As shown in FIGS. 5, 6 </ b> A, and 6 </ b> B, the bottom plate 32 of the case body 31 is formed with a shaft insertion hole 39 at a position facing the rotation shaft 26, and the rotation shaft is inserted into the gear case 30 from the shaft insertion hole 39. The end of 26 faces.

The bottom plate 32 of the case body 31 is provided with an opening 40 at a position facing the rotor shaft 29 b of the electric motor 29, and the end of the rotor shaft 29 b faces the gear case 30 from the opening 40.

As shown in FIGS. 4 and 5, the gear case 30 is provided with a gear reduction mechanism 41 that reduces the rotation of the rotor shaft 29 b of the electric motor 29 to a plurality of stages and transmits it to the end of the rotation shaft 26. .

The gear reduction mechanism 41 includes an input gear 42 attached to the rotor shaft 29 b, a first idle gear 43 that meshes with the input gear 42, and a second idle gear that is provided coaxially with the first idle gear 43. The gear 44 and an output gear 45 that is attached to the shaft end of the rotary shaft 26 and meshes with the second idle gear 44, reduce the rotation of the rotor shaft 29b in two stages, and transmit the rotation to the rotary shaft 26. ing.

Here, each of the input gear 42, the first idle gear 43, the second idle gear 44 and the output gear 45 is made of metal, and the first idle gear 43 and the second idle gear 44 are provided with bearings 47 on both sides of the gear shaft 46. It is supported so that it can rotate freely. On the other hand, one end portion of the gear shaft 46 is supported by a shaft hole 48 as a gear support portion formed in the bottom plate 32 of the case main body 31, and the other end portion is supported by a shaft hole 49 as a gear support portion formed in the lid 34. It is supported. Thereby, the rigidity of the 1st idle gear 43 and the 2nd idle gear 44 can be rotated highly.

The output gear 45 has a boss portion 50 on the shaft center, and the boss portion 50 is serrated to the shaft end portion of the rotating shaft 26 and is prevented from rotating, and a small diameter portion provided at one end of the boss portion 50. 50a is inserted into the shaft insertion hole 39 as the above-mentioned gear support portion formed in the bottom plate 32 of the case body 31, and is rotatably supported. Further, the small diameter portion 50b provided at the other end of the boss portion 50 is inserted into a gear support hole 51 as a gear support portion formed in the lid 34 and is rotatably supported. As a result, both ends of the output gear 45 can be rotationally supported, and together with the support structure of the first idle gear 43 and the second idle gear 44, the respective gears can be stably engaged with each other.

Each of the case main body 31 and the lid 34 in the gear case 30 is a resin molded product made of engineering plastics containing reinforcing fibers. As the engineering plastic, polyphenylene sulfide (PPS), polybutylene terephthalate (PBT), polyacetal (POM), or the like can be used.

Also, carbon fiber or glass fiber can be adopted as the reinforcing fiber.

As shown in FIGS. 5, 6 </ b> A, and 6 </ b> B, on the inner surface of the bottom plate 32 in the case body 31, a straight line connecting the centers of both holes 39 and 48 between the shaft insertion hole 39 and the shaft hole 48 as a gear support portion. A rib 52 is formed. The rib 52 is provided with cylindrical portions 52 a and 52 b around the shaft insertion hole 39 and the shaft hole 48. On the rib 52, a gate 53 is provided at one end of the shaft insertion hole 39 on a straight line connecting the centers of the shaft insertion hole 39 and the shaft hole 48.

On the other hand, on the inner surface of the lid 34, as shown in FIGS. 5, 7 A, and 7 B, a straight line connecting the center of both the holes 49, 51 between the shaft hole 49 as the gear support portion and the gear support hole 51. The rib 54 is formed. The rib 54 is provided with cylindrical portions 54 a and 54 b around the shaft hole 49 and the gear support hole 51. On the rib 54, a gate 55 is provided at one end portion on the straight side of the gear support hole 51 that connects the shaft hole 49 and the center of the gear support hole 51.

As shown in FIG. 1, between the rotating shaft 26 and the outer ring member 21, a rotation / linear motion converting mechanism that converts the rotational motion of the rotating shaft 26 into a linear motion in the axial direction of the outer ring member 21 as a linear motion member. 60 is provided.

As shown in FIGS. 1 and 3, the rotation / linear motion conversion mechanism 60 is a spiral provided on the outer periphery of the planetary roller 61 incorporated between the outer ring member 21 and the rotation shaft 26 on the inner periphery of the outer ring member 21. A plurality of circumferential grooves 63 meshing with the protrusions 62 are formed at equal intervals in the axial direction at the same pitch as the spiral protrusions 62, and the planetary roller 61 is brought into frictional contact with the rotation shaft 26 by the rotation of the rotation shaft 26. The outer ring member 21 is moved in the axial direction by revolving while rotating. In place of the circumferential groove 63, a spiral groove having the same pitch as that of the spiral protrusion 62 and having a different lead angle may be provided.

Here, the planetary roller 61 is rotatably supported by a carrier 64 that is rotatably supported around the rotation shaft 26. The carrier 64 has a pair of discs 64a and 64b facing each other in the axial direction, and a plurality of spacing adjusting members 64c are provided at intervals in the circumferential direction toward the other disc 64b on one side outer periphery of one disc 64a. The pair of disks 64a and 64b are connected to each other by tightening a screw 65 screwed into the end face of the interval adjusting member 64c.

As shown in FIG. 1, each of the pair of disks 64a and 64b is rotatably supported by a slide bearing 66 incorporated between the rotating shaft 26 and a slide that rotatably supports the outer disk 64a. The bearing 66 is secured by a washer 67 fitted to the shaft end of the rotating shaft 26 and a retaining ring 68 attached to the shaft end of the rotating shaft 26.

Each of the pair of discs 64a and 64b is provided with a shaft insertion hole 69 formed of a pair of long holes facing each other in the axial direction at intervals in the circumferential direction. The planetary roller 61 is rotatably supported by each of the plurality of roller shafts 70 that are slidably supported.

Both end portions of the plurality of roller shafts 70 penetrate the disks 64a and 64b, and a ring groove 70a is formed on the outer periphery of the end portion located outside from the outer surface of the disks 64a and 64b, and on the groove bottom surface of the ring groove 70a. An elastic ring 71 is assembled so as to circumscribe. The elastic ring 71 is assembled in an expanded state, and by its restoring elasticity, each of the plurality of roller shafts 70 is urged radially inward, and the planetary roller 61 is pressed against the outer diameter surface of the rotating shaft 26. Yes.

As shown in FIG. 1, a thrust bearing 72, a pressure seat plate 73, and a pressure seat plate 74 are assembled in this order from the planetary roller 61 side between the inner side disk 64 b and the planetary roller 61 in the carrier 64. The pressure seat plate 73 and the pressure receiving seat plate 74 are in contact with each other through the spherical seat 75. Further, a gap is provided between the fitting surfaces of the pressure receiving seat plate 74 and the roller shaft 70, and the roller shaft 70 and the pressure seat plate 73 are freely adjustable within the range of the gap.

Further, a backup plate 76 and a thrust bearing 77 are incorporated between the inner side disk 64b of the carrier 64 and the above-mentioned shaft support member 23 that rotatably supports the rotary shaft 26, and the outer ring member 21 through the planetary roller 61. The axial reaction force applied to the carrier 64 is supported by the thrust bearing 77.

The outer side opening of the caliper housing 12 is closed by a bellows 78 incorporated between the outer ring member 21 and the outer side end.

A rotation-preventing groove 79 is formed on the front end surface of the cap 22 that closes the opening of the outer side end portion of the outer ring member 21, and the rotation-preventing groove 79 is provided around the pad holder 80 of the inner brake pad 15. The stop protrusion 81 is engaged, and the outer ring member 21 is prevented from rotating with respect to the inner brake pad 15 by the engagement.

Here, since the pad holder 80 is supported by the mount 16 so as to be movable in the axial direction and is prevented from rotating, the outer ring member 21 is prevented from rotating with respect to the caliper housing 12 and is movable in the axial direction. It has been supported.

The electric brake device shown in the embodiment has the above-described configuration. FIG. 1 shows a state in which the braking force is released from the brake disc 10, and the pair of brake pads 14 and 15 are separated from the brake disc 10. .

When the electric motor 29 shown in FIG. 5 is driven in the state where the braking force is released as described above, the rotation of the rotor shaft 29b of the electric motor 29 is decelerated by the gear reduction mechanism 41, and the rotation shown in FIGS. The rotation is transmitted to the shaft 26 and the rotation shaft 26 rotates in the braking direction.

As shown in FIG. 1, since the outer diameter surfaces of the plurality of planetary rollers 61 are in elastic contact with the outer diameter surface of the rotation shaft 26, the rotation of the rotation shaft 26 causes the planetary roller 61 to contact the rotation shaft 26. Revolves while rotating by contact friction.

At this time, since the circumferential groove 63 formed on the outer diameter surface of the planetary roller 61 is engaged with the spiral protrusion 62 provided on the inner diameter surface of the outer ring member 21, the circumferential groove 63 and the spiral protrusion 62 are engaged. Accordingly, the outer ring member 21 moves in the axial direction, the inner brake pad 15 in contact with the outer ring member 21 comes into contact with the brake disc 10, and starts to press the brake disc 10 in the axial direction. The caliper 11 moves toward the direction in which the outer brake pad 14 supported by the claw portion 13 approaches the brake disc 10 by the reaction force of the pressing force, and the outer brake pad 14 contacts the brake disc 10. The outer brake pad 14 strongly clamps the outer periphery of the brake disk 10 from both sides in the axial direction with the inner brake pad 15, and a braking force is applied to the brake disk 10.

When the braking force is applied as described above, an axial load is applied from the outer ring member 21 to the planetary roller 61. The input portion of the axial load is an engaging portion of a spiral protrusion 62 provided on the inner diameter surface of the outer ring member 21 and a circumferential groove 63 formed on the outer diameter surface of the planetary roller 61. An unbalanced load is applied to.

At this time, a pressure seat plate 73 and a pressure receiving seat plate 74 are incorporated between the planetary roller 61 and the inner disk 64b of the carrier 64, and a spherical seat 75 is provided on the opposing surface of the both seat plates 73, 74. As described above, when an offset load is applied to the planetary roller 61, the pressure seat plate 73 tilts in a state where the pressure seat plate 73 is in contact with the spherical seat 75, and the pressure seat plate 73 and the pressure receiving seat plate 74. The contact pressure distribution in the circumferential direction is made uniform at the contact portion.

For this reason, the axial load of the same magnitude is applied to the thrust bearing 72 throughout the entire circumferential direction, and there is no inconvenience that the raceway surface and the rolling element are unevenly worn.

When the rotor shaft 29b of the electric motor 29 shown in FIG. 5 is reversely rotated after braking the brake disk 10, the rotating shaft 26 shown in FIG. 1 is decelerated and rotated in the reverse direction to that described above, and the planetary roller 61 that revolves while rotating. The outer ring member 21 is moved backward by the engagement of the circumferential groove 63 and the spiral protrusion 62, and the outer brake pad 14 and the inner brake pad 15 release the brake disc 10 and the braking force is released.

Here, since heat is generated by frictional contact of the brake pads 14 and 15 with the brake disc 10, the electric linear actuator 20 that operates the electric brake device is easily affected by heat. For example, when the heat is transmitted to the electric motor 29 through the gear case 30, the magnet of the electric motor 29 may be demagnetized.

However, in the embodiment, since the gear case 30 is made of resin, and the resin has low thermal conductivity, the electric motor 29 is not affected by heat.

Here, if the gear case 30 is made of resin in which reinforcing fibers are not mixed, there is a problem in durability, and the gear case 30 made of resin and the plurality of metal gears 42 to 45 forming the gear reduction mechanism 41 are not provided. Due to the difference in coefficient of linear expansion, a change occurs in backlash at the meshing portion of the input gear 42 and the first idle gear 43 and the meshing portion of the second idle gear 44 and the output gear 45, and rattling noise is generated and torque transmission efficiency is increased. Or drop.

In the embodiment, since both the case main body 31 and the lid 34 forming the gear case 30 are molded with a resin containing reinforcing fiber, it is excellent in durability and can sufficiently withstand use even in a severe environment. Can do.

In the case main body 31, as shown in FIGS. 6A and 6B, a linear rib 52 is provided between the shaft insertion hole 39 and the shaft hole 48 as the gear support portion and connects the centers of the two holes. Since the gate 53 is provided on one end of the straight line connecting the center of the shaft insertion hole 39 and the shaft hole 48 on the rib 52, the molten resin injected from the gate 53 flows along the rib 52, and the resin The resin reinforcing fibers are oriented in parallel to the flow direction, that is, the length direction of the ribs 52, and the linear expansion coefficient in the length direction of the ribs 52 can be made closer to the linear expansion coefficient of the metal.

On the other hand, in the lid 34, as shown in FIGS. 7A and 7B, a linear rib 54 that connects the centers of both holes is provided between a shaft hole 49 and a gear support hole 51 as a gear support portion. 54, the gate 55 is provided at one end on a straight line connecting the center of the shaft hole 49 and the gear support hole 51. Therefore, the molten resin injected from the gate 55 flows along the rib 54, and the flow of the resin The resin reinforcing fibers are oriented parallel to the direction, that is, parallel to the length direction of the ribs 54, and the linear expansion coefficient in the length direction of the ribs 54 can be brought close to the linear expansion coefficient of the metal.

For this reason, the difference between the linear expansion amount between the shaft insertion hole 39 and the shaft hole 48 and between the shaft hole 49 and the gear support hole 51 and the linear expansion amount in the radial direction of the gear becomes extremely small. In addition, the relative positional relationship between the input gear 42 and the first idle gear 43 and the relative positional relationship between the second idle gear 44 and the output gear 45 are small, and the backlash at the gear meshing portion varies. Therefore, the generation of noise such as rattling noise and the reduction in transmission efficiency of the gear reduction mechanism are suppressed.

6A and 6B, the linear rib 52 is provided between the shaft insertion hole 39 and the shaft hole 48 on the inner surface side of the bottom plate 32, but on the outer surface side of the bottom plate 32 as shown in FIGS. 8A and 8B. A straight rib 52 is provided between the shaft insertion hole 39 and the shaft hole 48, and a cylindrical portion 52 a covering the periphery of the shaft insertion hole 39, a disc portion 52 c covering the shaft hole 48, and a gate 53 are provided on the rib 52. May be.

7A and 7B, a linear rib 54 is provided between the shaft hole 49 and the gear support hole 51 on the inner surface side of the lid 34. However, as shown in FIGS. 9A and 9B, the outer surface of the lid 34 is provided. On the side, a linear rib 54 is provided between the shaft hole 49 and the gear support hole 51, and a disc portion 54 c that covers the shaft hole 49, a disc portion 54 d that covers the gear support hole 51, and a gate 55 are provided on the rib 54. It may be.

In the embodiment, each of the idle gears 43, 44 and the output gear 45 is rotatably supported by the gear case 30 and the electric motor 29 is supported by the gear case 30 for the input gear 42. May be rotatably supported by a gear case.

When the input gear is rotatably supported by the gear case, the input gear can be directly meshed with the output gear so that the number of reduction stages in the gear reduction mechanism 41 can be one stage or can be two or more stages. Also, the rib 52 can be formed between the input gear 42 and the first idle gear 43 and between the input gear 42 and the output gear 45 so that the rigidity can be appropriately improved.

12 Caliper housing (housing)
15 Brake pad 20 Electric linear actuator 21 Outer ring member (linear motion member)
29 Electric motor 29b Rotor shaft 30 Gear case 31 Case body 32 Bottom plate 33 Perimeter wall 34 Lid 39 Shaft insertion hole (gear support portion)
41 Gear reduction mechanism 45 Output gear 48, 49 Shaft hole (gear support)
51 Gear support hole (Gear support)
52, 54 Rib 53, 55 Gate 60 Rotation / linear motion conversion mechanism

Claims (5)

1. An electric motor (29), a gear reduction mechanism (41) comprising a metal gear that decelerates and outputs the rotation of the rotor shaft (29b) of the electric motor (29), and an output gear of the gear reduction mechanism (41) A gear case that has a rotation / linear motion conversion mechanism that converts the rotation of (45) into a linear motion of the linear motion member (21) incorporated in the housing (12), and houses the gear reduction mechanism (41). 30) In the electric linear actuator made of resin,
   The resin as the material for forming the gear case (30) is made of reinforcing fiber, and between the gear support portion (39) supporting the gear of the gear case (30) and the other gear support portion (48), these While providing the rib (52) which connects a gear support part (39,48), between these gear support parts (49,51) between other gear support parts (51) further different from another gear support part (49). The electric linear actuator is characterized in that the other reinforcing ribs (54) are provided and the reinforcing fibers of the resin are oriented in parallel to the extending direction of the ribs (52, 54).
2. The gear case (30) includes a case main body (31) provided with a peripheral wall (33) on a bottom plate (32), and a lid (34) for closing the opening of the peripheral wall (33) in the case main body (31). A gear support (39) and other gear support (48) for rotatably supporting gears on the bottom plate (32) and the lid (34) of the case body (31), and further gears. Another gear support portion (51) further different from the support portion (49) is provided at the opposing position, and between the gear support portion (39) and the other gear support portion (48) and still another gear support portion. The electric linear actuator according to claim 1, wherein the ribs (52, 54) are respectively provided between another gear support portion (51) different from (49).
3. The electric linear actuator according to claim 1 or 2, wherein a gate (55) is provided at one end of the rib (52, 54).
4. The electric linear actuator according to any one of claims 1 to 3, wherein the reinforcing fiber in the resin containing reinforcing fiber is made of glass fiber or carbon fiber.
5. The brake pad (15) is linearly driven by the electric linear actuator (20), and the brake disk (10) is pressed by the brake pad (15) to apply a braking force to the brake disk (10). In the electric brake device
   The electric linear actuator (20) comprises the electric linear actuator according to any one of claims 1 to 4, and the brake is applied by the linear member (21) of the electric linear actuator (20). An electric brake device characterized in that the pad (15) is linearly driven.

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