Electric power steering device

The present invention relates to an electric power steering device that uses a motor as a source of steering assist force.

[0002] An electric power steering device for a vehicle includes a motor for steering assistance and a reduction gear mechanism for transmitting the rotational force of the motor to a steering means, and responds to the steering of the steering means. The operation of the steering means is assisted by the rotation of the motor, and the labor burden on the driver for steering is reduced.

[0003] The reduction gear mechanism is joined to the output shaft of the motor via a shaft joint, and a worm having a shaft portion on the opposite side of the motor, a worm wheel that meshes with the worm and is connected to the steering mechanism, and the worm. Between the bearing member that movably supports the other end of the worm and the worm wheel in the direction in which the distance between the rotation centers becomes longer and shorter, the operating body that moves the bearing member, and the operating body and the bearing member. A coil spring that is interposed and urges the bearing member in the radial direction to apply a preload to the meshing portion of the worm with the worm wheel is provided, and the backlash amount is reduced by applying the preload to the meshing portion. ing. (For example, Patent Document 1.) [0004] Further, in the worm, a portion separated from the joint portion with the output shaft of the motor on the opposite side of the motor is rotatably supported in the housing via a rolling bearing. There is. However, since the rolling bearing has a gap in the axial length direction between the inner ring and the outer ring fitted via the plurality of rolling elements, it is necessary to eliminate the gap in the axial length direction. In other words, the worm rattles in the axial length direction due to the gap in the axial length direction of the rolling bearing, and the abnormal noise generated by this rattling leaks into the passenger compartment, which causes discomfort to the driver. It is necessary to eliminate the gap in the axial length direction.

[0005] As one means of eliminating the gap in the axial length direction, an adjusting ring abutting on one side of the outer ring of the rolling bearing is screwed into the housing, and the adjusting ring is rotated to rotate the outer ring of the rolling bearing and the outer ring of the rolling bearing. By moving the inner ring relative to the axial length direction, a preload is applied to the worm to eliminate the gap in the axial length direction and to eliminate the rattling of the worm in the axial length direction.

By the way, the worm gear or the like of the reduction gear mechanism has its tooth streaks twisted in the rotation direction with respect to the rotation center line, and when a rotation torque is applied from the worm to the worm wheel, in other words, steering is assisted by the rotation of the motor. In this case, a component force (hereinafter referred to as a meshing reaction force) is generated so that the worm moves in the radial direction along the tooth line of the worm wheel, and the worm is pressed in the radial direction by the meshing reaction force and swings, and the male Since the peripheral surface of the shape joint portion comes into contact with the female joint portion and a tapping noise is likely to be generated, grease is applied between the male joint portion and the female joint portion to reduce the tapping noise. It is set to.

[0007] [Patent Document 1] Japanese Unexamined Patent Publication No. 2002-21943 [0008] [Problems to be Solved by the Invention] However, in a conventional electric power steering device, a male joint portion is formed by swinging a worm. And the grease between the female joints will flow out from the open end of the female joints, the amount of grease will be reduced, and the tapping noise will be more likely to occur, and improvement measures have been requested. In addition, since the adjustment ring for eliminating rattling in the axial length direction of the worm is arranged around the worm, an adjustment ring having a larger diameter than the worm is required, and the circumference of the worm is large. It took shape, and improvement measures were requested.

[0009] The present invention has been made in view of such circumstances, and its main purpose is to prevent the outflow of the lubricant filled between the male joint portion and the female joint portion, and to urge the lubricant. It is an object of the present invention to provide an electric power steering device capable of reducing the size of the means and the size of the circumference of the drive gear.

[Means for Solving the Problems] The electric power steering device according to the first invention is joined to the output shaft of a motor via a male joint portion and a female joint portion, and is a shaft on the opposite side of the motor. It is possible to move the drive gear having a portion, the driven gear that meshes with the drive gear and is connected to the steering means, and the drive gear and the driven gear that support the shaft portion in a direction in which the distance between the rotation centers is long or short. An electric power that includes a bearing member, a support member having an accommodating hole for accommodating the bearing member, and an urging means for urging the drive gear toward the anti-motor side, and assists steering by the rotation of the motor. In the steering device, at least one of the male joint portion and the female joint portion is provided with an outflow stop ring for preventing the outflow of the lubricant filled between the male joint portion and the female joint portion.<u style="single">The male joint portion has a recess recessed from the end surface in the axial length direction, and the biasing means is housed in the recess, and the outflow stop ring is between the inner peripheral surface and the outer peripheral surface thereof. In addition, it has a flexible portion whose axial length dimension is smaller than the radial dimension.</u>It is characterized by that.

[0011] In the first invention, the lubricant filled between the male joint portion and the female joint portion can be prevented from flowing out from the open end of the female joint portion, so that the male shape can be prevented. It can be used for a long time while suppressing the tapping noise of the joint and the female joint.<u style="single">Further, since the urging means is housed in the recess of the male joint, the urging means can be made smaller, and the circumference of the urging means can be made smaller, so that the entire electric power steering device can be made smaller. it can. Further, since the outflow stop ring is easily bent at the bending portion between the inner peripheral surface and the outer peripheral surface, it is possible to sufficiently secure the adjustment allowance for the backlash amount of the meshing portion of the drive gear and the driven gear, and also to prevent the outflow. Lubrication even when the drive gear, which can further enhance the lubricant outflow prevention function of the ring and can sufficiently secure the adjustment allowance for the backlash amount of the meshing portion, frequently swings due to the meshing reaction force. The outflow of the agent can be prevented, and the tapping noise of the male joint portion and the female joint portion can be reduced.</u>[0016] No.<u style="single">2</u>The electric power steering device according to the invention is<u style="single">A drive gear that is joined to the output shaft of the motor via a male joint and a female joint and has a shaft on the opposite side of the motor, a driven gear that meshes with the drive gear and is connected to the steering means, and the above. A bearing member that supports the shaft portion and can move in the direction in which the distance between the rotation centers of the drive gear and the driven gear becomes longer or shorter, a support member having an accommodating hole for accommodating the bearing member, and the drive gear as an anti-motor. In an electric power steering device provided with a urging means for urging to the side and assisting steering by rotation of the motor, at least one of the male joint portion and the female joint portion is a male joint portion and a female. The male joint portion is provided with an outflow stop ring for preventing the outflow of the lubricant filled between the shaped joint portions, and the male joint portion has a recess recessed in the axial length direction from the end face, and the recess is filled with the recess. It accommodates the urging means, and the outflow stop ring is characterized in that a plurality of the outflow stop rings are juxtaposed so as to be close to each other.</u>[0017] No.<u style="single">2</u>In the invention<u style="single">Since the lubricant filled between the male joint and the female joint can be prevented from flowing out from the open end of the female joint, the tapping noise of the male joint and the female joint can be heard. It can be used for a long time while suppressing it. Further, since the urging means is housed in the recess of the male joint, the urging means can be made smaller, and the circumference of the urging means can be made smaller, so that the entire electric power steering device can be made smaller. it can. Moreover,</u>Since it is possible to prevent the lubricant from flowing out from the open end of the female joint in two steps, it is possible to further enhance the lubricant outflow prevention function of the outflow stop ring.<u style="single">Ki, drive</u>Even when the moving gear frequently swings due to the meshing reaction force, it is possible to prevent the lubricant from flowing out and reduce the tapping noise of the male joint portion and the female joint portion.

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below with reference to the drawings showing the embodiments. Embodiment 1 FIG. 1 is an enlarged cross-sectional view of a reduction gear mechanism portion showing the configuration of the first embodiment of the electric power steering device according to the present invention, and FIG. 2 is a cross section showing the configuration of the entire part of the electric power steering device. FIG. 3 and FIG. 3 are explanatory views showing the relationship between the drive gear and the driven gear and the support holes of the support member.

[0019] The electric power steering device includes a motor 1 for steering assistance, a worm 3 as a drive gear coupled to the output shaft 1a of the motor 1 via a shaft joint 2, and a driven gear that meshes with the worm 3. It includes a reduction gear mechanism A having a worm wheel 4 as a gear, and a steering means 5 having a rotating shaft (described later) for supporting the worm wheel 4 and connecting to the worm wheel 4.

[0020] The steering means 5 has a first steering shaft 51 having one end connected to a steering wheel B for steering and having a cylinder 51a at the other end, and one end thereof inserted into the cylinder 51a. The torsion bar 52 is connected to the tubular portion 51a of the first steering shaft 51 and twisted by the action of the steering torque applied to the steering wheel B, and the other end is connected to the other end of the torsion bar 52 to reduce the gear. A second steering shaft 53 is provided as a rotation shaft connected to the mechanism A, and the second steering shaft 53 is connected to, for example, a rack pinion type steering mechanism (not shown) via a universal joint.

[0021] The worm 3 of the reduction gear mechanism A has shaft portions 3a and 3b at both ends, and the motor 1 is rotatably supported by the support member 7 via the rolling bearing 6 at one end of the shaft portion 3a. The shaft portion 3b at the other end is supported by the support member 7 via the cylindrical bearing member 8. The shaft portion 3a is press-fitted into the inner ring 6a of the rolling bearing 6. In the middle of the shaft portion 3a, a regulation ring 9 such as a C-shaped ring as a fail sail that faces one end of the inner ring 6a of the rolling bearing 6 and regulates the relative movement of the worm 3 with the inner ring 6a is detachably attached. .. The worm wheel 4 is fitted and fixed in the middle of the rotating shaft 5.

[0022] The support member 7 accommodates the worm 3, and the first accommodating portion 7a and the worm wheel 4 that rotatably support the shaft portions 3a and 3b of the worm 3 via the rolling bearing 6 and the bearing member 8 are accommodated. It has a second accommodating portion 7b accommodating and supporting the worm wheel 4 via a second steering shaft 53 and two rolling bearings 10 and 11 fitted to the second steering shaft 53.

[0023] The first accommodating portion 7a is elongated in the axial length direction of the worm 3, and a support hole 71 for fitting and supporting the rolling bearing 6 and a screw hole 72 connected to the support hole 71 are provided at one end in the longitudinal direction thereof. A motor mounting portion 73 is provided, and a screw ring 12 for fixing the rolling bearing 6 is screwed into the screw hole 72. Further, the motor 1 is mounted on the motor mounting portion 73.

[0024] The second accommodating portion 7b is provided with two support holes 74,75 for fitting and supporting the rolling bearings 10, 11. The center-to-center distance L between the center of the support hole 71 and the center of the support holes 74,75 is the sum of φd / 2 of the pitch circle diameter φd of the worm 3 and φD / 2 of the pitch circle diameter φD of the worm wheel. It is set so that it is equal to the specified size or smaller than the added size of φd / 2 and φD / 2.

[0025] By setting this dimension, the worm 3 becomes substantially parallel to the parallel region (CC region in the figure) of the rotation centers of the worm 3 and the worm wheel 4 around the support portion to the rolling bearing 6, or rotates. The distance H1 between the rotation centers on the shaft portion 3a side (motor side) is inclined so as to be shorter than the rotation center distance H2 on the shaft portion 3b side (anti-motor side) with respect to the parallel region CC of the center.

[0026] The output shaft 1a of the motor 1 and the shaft portion 3a of the worm 3 are joined via a male joint portion 21 having serrations and a female joint portion 22. The male joint portion 21 is configured by providing serrations on the peripheral surface of the shaft portion 3a, and the female joint portion 22 is provided with serrations inside the tubular member 23 fitted and fixed to the output shaft 1a. The male joint portion 21 and the female joint portion 22 are serrated and fitted so that a radial gap S1 is formed between the male joint portion 21 and the female joint portion 22. A lubricant made of grease is applied between the male joint portion 21 and the female joint portion 22.

[0027] The male joint portion 21 is provided with an annular groove 21a having a size equal to or less than the diameter of the valley portion of the serration at the end on the opposite side of the motor, and the open end of the female joint portion 22 is provided with serrations. An annular recess 22a having a size equal to or larger than the diameter of the valley is provided. An outflow stop ring 13 for preventing the outflow of the lubricant filled between the male joint portion 21 and the female joint portion 22 in contact with the annular recess 22a on the outer peripheral surface of the annular groove 21a is fitted. It is held. The annular recess 22a is provided from the edge of the female joint portion 22 on the opening side. Further, the annular recess 22a may be formed in a groove shape in the vicinity of the edge on the opening side of the female joint portion 22.

[0028] The end surface of the male joint portion 21 on the motor side, in other words, one end of the worm 3 is provided with a recess 21b recessed in the axial length direction. The recess 21b houses a coil spring 14 as an urging means for urging the worm 3 toward the anti-motor side by contacting one end of the output shaft 1a with the end surface.

[0029] The coil spring 14 is urged in parallel with the parallel region CC of the center of rotation, and this urging force is applied to one end of the worm 3 to the center O of the support portion of the shaft portion 3a to the rolling bearing 6. On the other hand, when the distance H1 between the rotation centers is increased and the worm 3 is inclined with respect to the parallel region CC of the rotation center as described above, the worm 3 is swung in the direction in which the inclination angle becomes smaller. It is done like this. Further, the urging force of the coil spring 14 is transmitted from the shaft portion 3a to the inner ring 6a via the regulation ring 9, and eliminates the gap in the axial length direction of the rolling bearing 6.

[0030] FIG. 4 is an enlarged cross section showing the configuration of the outflow stop ring. The outflow stop ring 13 is made of rubber or the like having a flexible portion 13a between the inner peripheral surface and the outer peripheral surface, for example, as shown in FIGS. 4A to 4E, in which the dimension in the axial length direction is smaller than the dimension in the radial direction. Made of elastic material. The outflow stop ring 13 in FIG. 4A has a substantially elliptical cross-sectional shape whose radial dimension is longer than the axial length dimension, and is inside between the inner peripheral surface and the outer peripheral surface and the radial center portion. The portion and the outer portion are designated as a flexible portion 13a. The outflow stop ring 13 in FIG. 4B has a substantially X-shaped cross-sectional shape having two contact ring portions 13b and 13b on the inner peripheral side and the outer peripheral side, and each contact ring portion 13b on the inner peripheral side and the outer peripheral side. Is used as the flexible portion 13a. The outflow stop ring 13 in FIG. 4 (c) has a substantially E-shaped cross section, and the radial central portion between the inner portion and the outer portion is a flexible portion 13a. The outflow stop ring 13 in FIG. 4 (d) has a substantially U-shaped cross section, in other words, is composed of an oil seal, and the radial central portion between the inner portion and the outer portion is a flexible portion 13a. Figure 4 (e) The outflow stop ring 13 has a cross-sectional shape of a substantially Y shape having one contact ring portion 13c on the inner peripheral side and two contact ring portions 13c on the outer peripheral side, and each contact on the inner peripheral side and the outer peripheral side. The ring portion 13c is used as the bending portion 13a.

The other end of the first accommodating portion 7a faces the concave hole 76 into which the shaft portion 3b of the other end of the worm 3 is inserted and the inner surface of the concave hole 76, and faces the inner surface of the concave hole 76 in the radial direction of the shaft portion 3b. A cylindrical accommodating hole 77 is provided, which is bored, in other words, in a direction in which the worm 3 is pressed toward the worm wheel 4. A bearing member 8 to which the shaft portion 3b is rotatably fitted in the accommodating hole 77, an elastic body 15 composed of a coil spring for urging the bearing member 8 in the pressing direction, and an elastic body 15 to the outside of the accommodating hole 77. A closing member 15 that closes the opening is housed. Further, a threaded portion 78 is provided on the side of the accommodating hole 77 that is open to the outside, and the obturator foramen 16 is screwed into the threaded portion 78.

[0032] A gap S2 larger than the radial gap S1 is provided between the closed hole member 16 and the bearing member 8, and the worm 3 is provided in a direction in which the distance H2 between the rotation centers becomes longer due to the meshing reaction force or the like. When moving, the movement of the worm 3 is regulated by the radial gap S1 so that the bearing member 8 does not come into contact with the closed hole member 16.

[0033] The bearing member 8 is provided with a bearing hole 8a bored so as to be orthogonal to the moving direction in the middle of the axial length direction, in other words, in the moving direction of moving along the accommodating hole 77. A slide bearing 17 in which the shaft portion 3b is rotatably fitted is inserted and fixed in the bearing hole 8a, and the shaft portion 3b is supported by the bearing member 8 via the slide bearing 17.

[0034] The support member 7 has a third accommodating portion 7c connected to the second accommodating portion 7b, and is attached to the steering wheel B by the relative rotational displacement of the steering shafts 51 and 53 in response to the twist of the torsion bar 17. A torque sensor 18 for detecting the applied steering torque is housed in the third accommodating portion 7c, and the motor 1 is driven and controlled based on the torque or the like detected by the torque sensor 18.

[0035] When the motor 1 and the reduction gear mechanism A are incorporated in the electric power steering device configured as described above, for example, the female joint portion 22 is filled with a lubricant made of grease by coating. The male joint portion 21 of the worm 3 is inserted into the female joint portion 22 of the output shaft 1a and serrated. In this case, the outflow stop ring 13 provided at the opposite end of the male joint 21 comes into contact with the annular recess 22a provided at the open end of the female joint 22, so that the female joint 22 It is possible to prevent the lubricant inside from flowing out from the open end portion of the female joint portion 22. Therefore, it can be used for a long time while suppressing the tapping noise of the male joint portion 21 and the female joint portion 22.

[0036] Further, when the female joint portion 22 of the output shaft 1a and the male joint portion 21 of the worm 3 are serrated and fitted, the radial gap S1 is provided between the male joint portion 21 and the female joint portion 22. Occurs. Further, the worm 3 supported by the rolling bearing 6 swings around the support portion (shaft portion 3a) to the rolling bearing 6 due to the gap between the inner ring 6a and the outer ring 6b of the rolling bearing 6, and the worm 3 and the male The center of rotation of the shape joint portion 21 can be inclined with respect to the center of the female joint portion 22 and the output shaft 1a within the range of the radial gap S1.

The relationship between the center-to-center distance L of the support holes 71 and the support holes 74,75 and the pitch circle diameter φd of the worm 3 and the pitch circle diameter φD of the worm wheel 4 is L &lt;φd / 2 + φD /. When 2, the worm 3 has a rotation center-to-center distance H1 on the motor side shorter than the rotation center-to-center distance H2 on the motor side with respect to the parallel region CC of the rotation center centered on the support portion to the rolling bearing 6. Tilt to be.

[0038] Since the inclined worm 3 is urged by the coil spring 14 on the motor 1 side of the rolling bearing 6 in parallel with the parallel region CC of the rotation center, the worm 3 provides a support portion to the rolling bearing 6. It swings in the direction in which the tilt angle becomes smaller as the center. By this swing, a preload can be applied to the meshing portions of the worm 3 and the worm wheel 4, and the backlash amount of the meshing portions can be reduced. Further, since the coil spring 14 urges the worm 3 to the non-motor side on the motor 1 side of the rolling bearing 6, it eliminates the gap in the axial length direction of the rolling bearing 6 and eliminates the rattling of the worm 3 in the axial length direction. be able to.

[0039] The relationship between the distance L between the centers of the support holes 71 and the support holes 74,75 and the pitch circle diameter φd of the worm 3 and the pitch circle diameter φD of the worm wheel 4 is L = φd / 2 + φD / 2. In some cases, the worm 3 is substantially parallel to the parallel region CC of the center of rotation. Since the worm 3 in this parallel state is urged by the coil spring 14 on the motor 1 side of the rolling bearing 6 in parallel with the parallel region CC of the rotation center, the backlash amount of the meshing portion can be reduced. it can. Further, since the coil spring 14 urges the worm 3 to the non-motor side on the motor 1 side of the rolling bearing 6, it eliminates the gap in the axial length direction of the rolling bearing 6 and eliminates the rattling of the worm 3 in the axial length direction. be able to.

[0040] Further, when the steering is assisted by the rotation of the motor 1, when the worm 3 moves in the direction in which the distance H2 between the rotation centers becomes longer due to the meshing reaction force or the like, the peripheral surface of the male joint portion 21 is a female joint. It abuts on the portion 22 and the movement of the worm 3 is restricted. In this case, since the gap S2 between the hole closing member 16 and the bearing member 8 is set to be larger than the radial gap S1, the bearing member 8 supporting the shaft portion 3b of the worm 3 hits the hole closing member 16. It is possible to prevent contact with each other, and it is possible to eliminate noise between the bearing member 8 and the obturator foramen 16. Since the noise can be eliminated in this way, it is not necessary to provide a cushioning member between the bearing member 8 and the obturator foramen 16 as in Patent Document 1 described above, and the number of parts can be reduced. Further, since the elastic body 15 made of a coil spring is interposed between the bearing member 8 and the obturator foramen 16, the above-mentioned movement of the worm 3 can be suppressed, and the peripheral surface of the male joint portion 21 is female. It is also possible to prevent the joint portion 22 from coming into contact with the joint portion 22. Further, instead of the elastic body 15, an urging means can be provided between the female joint portion 22 and the regulation ring 9.

Further, as shown in FIG. 4, the outflow stop ring 13 has a flexible portion 13a between the inner peripheral surface and the outer peripheral surface whose axial length direction is smaller than the radial dimension, so that the worm 3 has a flexure portion 13a. Even when a sufficient amount of swing is secured, the outflow of the lubricant can be prevented, and the tapping noise of the male joint portion 21 and the female joint portion 22 can be reduced.

[0042] In the embodiment described above, the gap S2 between the closed hole member 16 and the bearing member 8 is set to be larger than the radial gap S1, but the radial gap S1 and the gap S2 are made equal to each other. It may be set, or the gap S2 may be set to be smaller than the radial gap S1. In this case, the elastic body 15 formed of a coil spring interposed between the bearing member 8 and the hole closing member 16 can reduce the noise between the bearing member 8 and the hole closing member 16.

Embodiment 2 FIG. 5 is an enlarged cross-sectional view of a main part showing the configuration of Embodiment 2 of the electric power steering device. In the electric power steering device of the second embodiment, the outflow stop ring 13 of FIG. 4 is juxtaposed with the anti-motor side end of the male joint portion 21. In FIG. 5A, two annular grooves 21c and 21c separated in the axial length direction are provided, and an outflow stop ring 13 is inserted into each annular groove 21c. In FIG. 5B, an annular groove 21d having a width dimension into which two outflow stop rings 13 can be inserted is provided, and two outflow stop rings 13 are inserted into the annular groove 21d.

[0044] In the second embodiment, since it is possible to prevent the lubricant from flowing out from the open end of the female joint portion 22 in two steps, the lubricant outflow prevention function of the outflow stop ring 13 is further enhanced. Can be enhanced. Therefore, even when the worm 3 frequently swings due to the meshing reaction force, the outflow of the lubricant can be prevented, and the tapping noise of the male joint portion 21 and the female joint portion 22 can be reduced. Since other configurations and operations are the same as those in the first embodiment, the same parts are designated by the same reference numerals, and detailed description thereof and description of the action and effect will be omitted.

Embodiment 3 FIG. 6 is an enlarged cross-sectional view of a main part showing the configuration of the electric power steering apparatus according to the third embodiment. The electric power steering device according to the third embodiment has a substantially disc spring shape in which the male joint portion 21 has an outflow stop ring 13 at the opposite end of the male joint portion 21 and is in contact with one side of the outflow stop ring 13. The backup ring 19 is juxtaposed. In the third embodiment, the outflow stop ring 13 and the backup ring 19 are inserted into one annular groove 21e.

[0046] In the third embodiment, when the outflow stop ring 13 is bent by the swing of the worm 3, the bending force of the outflow stop ring 13 is transmitted to the backup ring 19, and the backup ring 19 is also bent. Therefore, the bending of the outflow stop ring 13 can be suppressed. Since other configurations and operations are the same as those in the first embodiment, the same parts are designated by the same reference numerals, and detailed description thereof and description of the action and effect will be omitted.

Embodiment 4 FIG. 7 shows the configuration of Embodiment 4 of the electric power steering device, (a) is an enlarged cross-sectional view of a main part, and (b) is line VII-VII of (a). It is a cross-sectional view of. In the electric power steering device of the fourth embodiment, instead of serration fitting the male joint portion 21 and the female joint portion 22, the male joint portion 21 and the female joint portion 22 are spline-fitted, and the male joint portion 21 and the female joint portion 22 are spline-fitted. An elastic ring 20 is provided between the motor side end portion of the shape joint portion 21 and the female joint portion to prevent the peripheral surface of the male joint portion 21 from coming into contact with the female joint portion 22.

[0048] In the fourth embodiment, splines having a quadrangular cross-sectional shape are provided on the peripheral surfaces of the male joint portion 21 and the female joint portion 22. Further, an annular recess 21f is provided at the end of the male joint portion 21 on the motor side, and the elastic ring 20 is fitted and held in the annular recess 21f.

[0049] In the fourth embodiment, since the side surfaces of the splines of the male joint portion 21 and the female joint portion 22 come into contact with each other orthogonally to the rotation direction of the output shaft 1a, the male joint portion 21 and the female joint portion 21 and the female The strength of the joint portion of the shape joint portion 22 can be increased as compared with the serration. Further, when the worm 3 swings around the support portion for the rolling bearing 6, the elastic ring 20 can be prevented from bending and the peripheral surface of the male joint portion 21 can be prevented from coming into contact with the female joint portion 22. It is possible to reduce the noise between the male joint portion 21 and the female joint portion 22. Since other configurations and operations are the same as those in the first embodiment, the same parts are designated by the same reference numerals, and detailed description thereof and description of the action and effect will be omitted.

Embodiment 5 FIG. 8 shows the configuration of Embodiment 5 of the electric power steering device, (a) is an enlarged cross-sectional view of a main part, and (b) is line VIII-VIII of (a). It is a cross-sectional view of. In the electric power steering device of the fifth embodiment, instead of serration fitting and spline fitting of the male joint portion 21 and the female joint portion 22, the male joint portion 21 and the female joint portion 22 are sandwiched between the male joint portion 21 and the female joint portion 22. A key 30 is provided to provide an elastic ring 20 between the motor side end of the male joint 21 and the female joint 22 to prevent the peripheral surface of the male joint 21 from coming into contact with the female joint 22. It is provided.

[0051] In the fifth embodiment, key grooves are provided at two positions separated in the circumferential direction on the peripheral surfaces of the male joint portion 21 and the female joint portion 22, and the key 30 is fitted in each key groove. It is matched. Further, an annular recess 21f is provided at the end of the male joint portion 21 on the motor side, and the elastic ring 20 is fitted and held in the annular recess 21f.

[0052] In the fifth embodiment, the relative rotation of the male joint portion 21 and the female joint portion 22 can be prevented by the key 30, and the rotation of the output shaft 1a is caused by the female joint portion 22 to the key 30. Since it can be transmitted to the male joint portion 21 via the passage, the strength of the joint portion of the male joint portion 21 and the female joint portion 22 can be increased as compared with the serration. Further, when the worm 3 swings around the support portion for the rolling bearing 6, the elastic ring 20 can be prevented from bending and the peripheral surface of the male joint portion 21 can be prevented from coming into contact with the female joint portion 22. It is possible to reduce the noise between the male joint portion 21 and the female joint portion 22. Since other configurations and operations are the same as those in the first embodiment, the same parts are designated by the same reference numerals, and detailed description thereof and description of the action and effect will be omitted.

BEST MODE FOR CARRYING OUT THE INVENTION FIG. 9 is an enlarged cross-sectional view of a main part showing the configuration of the sixth embodiment of the electric power steering device. In the electric power steering device of the sixth embodiment, the male joint portion 21 and the female joint portion 22 are joined by a flexible elastic body 31.

[0054] In the sixth embodiment, the end face of the male joint portion 21 and the female joint portion 22 are provided with fitting holes 21g and 22b having a quadrangular cross section, and one end of a prismatic elastic body 31 is provided. It is fitted into the fitting hole 21g, the other end of the elastic body 31 is fitted into the fitting hole 22b, and the rotation of the output shaft 1a is transmitted from the female joint portion 22 to the male joint portion 21 via the elastic body 31. It is designed to be transmitted. Further, the end face of the male joint portion 21 and the open end of the female joint portion 22 are separated by a dimension larger than allowing the worm 3 to swing.

[0055] In the sixth embodiment, the amount of swing of the worm 3 can be sufficiently secured, and the noise at the joint portion of the male joint portion 21 and the female joint portion 22 is eliminated. Further, since the elastic body 31 can be twisted when the rotation of the output shaft 1a is transmitted, the steering feeling can be improved. Since other configurations and operations are the same as those in the first embodiment, the same parts are designated by the same reference numerals, and detailed description thereof and description of the action and effect will be omitted.

Embodiment 7 FIG. 10 is an enlarged cross-sectional view of a main part showing the configuration of Embodiment 7 of the electric power steering device. In the electric power steering device of the seventh embodiment, the male joint portion 21 and the female joint portion 22 are joined by a flexible elastic body 32, and the amount of bending of the elastic body 32 is limited. A part 21h is provided.

[0057] In the seventh embodiment, the end of the male joint portion 21 on the motor side is connected to the cubic fitting convex portion 21j and the fitting convex portion 21j, and is larger than the fitting convex portion 21j. A cube-shaped limiting portion 21h is provided, and the female joint portion 22 is provided with a fitting hole 22c that is larger than the limiting portion 21h and has a quadrangular cross section. The fitting hole 22c has a longer size than the fitting convex portion 21j.

[0058] The elastic body 32 is made of a ring member having a quadrangular cross section, and the inside of the elastic body 32 is fitted to the fitting convex portion 21j. Then, the fitting hole 22c is fitted to the outside of the elastic body 32, so that the male joint portion 21 and the female joint portion 22 are joined by the elastic body 32.

[0059] In the seventh embodiment, the amount of swing of the worm 3 can be sufficiently secured, and the noise at the joint portion of the male joint portion 21 and the female joint portion 22 is eliminated. Further, when the elastic body 32 bends more than a certain amount due to the swing of the worm 3, the open end portion of the female joint portion 22 abuts on the limiting portion 21h to limit the bending amount of the elastic body 32. Therefore, damage to the elastic body 32 can be prevented. Further, since the elastic body 32 can be twisted when the rotation of the output shaft 1a is transmitted, the steering feeling can be improved. Since other configurations and operations are the same as those in the first embodiment, the same parts are designated by the same reference numerals, and detailed description thereof and description of the action and effect will be omitted.

8. FIG. 11 is an enlarged cross-sectional view of a main part showing the configuration of the eighth embodiment of the electric power steering device. In the electric power steering device of the eighth embodiment, the worm 3 is urged to the anti-motor side by the elastic body 31 of the sixth embodiment.

[0061] In the eighth embodiment, the end face of the male joint portion 21 and the open end of the female joint portion 22 are separated by a dimension equal to or larger than a distance capable of bending the elastic body 31 in the axial length direction. The elastic body 31 is bent in the axial length direction when the male joint portion 21 and the female joint portion 22 are joined via the elastic body 31.

[0062] In the eighth embodiment, since the elastic body 31 for transmission also serves as an urging spring, the number of parts can be reduced. Since other configurations and operations are the same as those of the first and sixth embodiments, the same parts are designated by the same reference numerals, and detailed description thereof and description of the action and effect will be omitted.

[0063] Embodiment 9 FIG. 12 is an enlarged cross-sectional view of a main part showing the configuration of the electric power steering device according to the ninth embodiment. The electric power steering device of the ninth embodiment anti-motors the worm 3 around the elastic body 31 of the sixth embodiment between the end face of the male joint 21 and the open end of the female joint 22. A coil spring 33 for urging the side is provided.

[0064] In the ninth embodiment, the end face of the male joint portion 21 and the open end of the female joint portion 22 are separated by a dimension capable of interposing a coil spring 33. Since other configurations and operations are the same as those of the first and sixth embodiments, the same parts are designated by the same reference numerals, and detailed description thereof and description of the action and effect will be omitted.

[0065] In the embodiment described above, the output shaft 1a of the motor 1 has the female joint portion 22, and the shaft portion 3a of the worm 3 has the male joint portion 21. The shaft 1a may have a male joint portion 21 and the shaft portion 3a may have a female joint portion 22. Further, the reduction gear mechanism A of the embodiment described above is a worm gear including a drive gear which is a worm 3 and a driven gear which is a worm wheel 4, and may be a bevel gear.

[Effect of the Invention] As described in detail above, according to the first invention, the lubricant filled between the male joint portion and the female joint portion flows out from the open end of the female joint portion. It can be used for a long time while suppressing the tapping noise of the male joint portion and the female joint portion.<u style="single">Moreover, even when the drive gear that can sufficiently secure the adjustment allowance for the backlash amount of the meshing portion frequently swings due to the meshing reaction force, the outflow of the lubricant can be prevented, and the male joint portion. And the tapping noise of the female joint can be reduced. Further, the urging means can be made smaller, the circumference of the urging means can be made smaller, and the entire electric power steering device can be made smaller.</u>[0068] No.<u style="single">2</u>According to the invention<u style="single">It is possible to prevent the lubricant filled between the male joint and the female joint from flowing out from the open end of the female joint, and suppress the tapping noise of the male joint and the female joint. It can be used for many years. Moreover,</u>Even when the drive gear that can sufficiently secure the adjustment allowance for the backlash amount of the meshing portion frequently swings due to the meshing reaction force, the outflow of the lubricant can be prevented, and the male joint portion and the female The tapping noise of the shape joint can be reduced.<u style="single">Further, the urging means can be made smaller, the circumference of the urging means can be made smaller, and the entire electric power steering device can be made smaller.</u>BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an enlarged cross-sectional view of a reduction gear mechanism portion showing the configuration of the first embodiment of the electric power steering device according to the present invention.

FIG. 2 is a cross-sectional view showing the configuration of the entire portion of the electric power steering device according to the present invention.

FIG. 3 is an explanatory diagram showing a relationship between a drive gear and a driven gear of the electric power steering device according to the present invention and a support hole of a support member.

FIG. 4 is an enlarged cross-sectional view showing a configuration of an outflow stop ring of the electric power steering device according to the present invention.

FIG. 5 is an enlarged cross-sectional view of a main part showing the configuration of the second embodiment of the electric power steering device according to the present invention.

FIG. 6 is an enlarged cross-sectional view of a main part showing the configuration of the third embodiment of the electric power steering device according to the present invention.

FIG. 7 shows the configuration of the fourth embodiment of the electric power steering device according to the present invention, in which (a) is an enlarged cross-sectional view of a main part, and (b) is a cross-sectional view of lines VII-VII of (a). It is a figure.

FIG. 8 shows the configuration of the fifth embodiment of the electric power steering device according to the present invention, (a) is an enlarged cross-sectional view of a main part, and (b) is a cross-sectional view of lines VIII-VIII of (a). It is a figure.

FIG. 9 is an enlarged cross-sectional view of a main part showing the configuration of the sixth embodiment of the electric power steering device according to the present invention.

FIG. 10 is an enlarged cross-sectional view of a main part showing the configuration of the seventh embodiment of the electric power steering device according to the present invention.

FIG. 11 is an enlarged cross-sectional view of a main part showing the configuration of the eighth embodiment of the electric power steering device according to the present invention.

FIG. 12 is an enlarged cross-sectional view of a main part showing the configuration of the ninth embodiment of the electric power steering device according to the present invention.

[Description of sign] 1 Motor 1a Output shaft 3 Worm (drive gear) 3b Shaft 4 Worm wheel (driven gear) 5 Steering means 7 Support member 77 Accommodation hole 8 Bearing member 21 Male joint 21b Recess 22 Female Joint part 13 Outflow stop ring 13a Bending part 14 Coil spring (urging means)