JP4883349B2 - Electric power steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce meshing noise and reduce the manufacturing cost. <P>SOLUTION: In the electric power steering device 1, a steering mechanism 5 is driven by an electric motor through a drive gear 25, an intermediate gear 26, and a driven gear 27. The drive gear 25, the intermediate gear 26, and the driven gear 27 are turnably supported by a housing body 31 composed of a single part. Since the housing body 31 can highly accurately position the central axis lines 25a, 26a, 27a of the respective gears 25, 26, 27 in parallel with each other, the meshing noise can be reduced. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to an electric power steering apparatus.

  As the electric power steering apparatus, there is an electric power steering apparatus called a so-called rack parallel type. In this type, an electric motor for assisting steering is attached to the housing of the steering mechanism, and the output shaft of the electric motor is arranged in parallel with the rack bar of the steering mechanism. The rotational driving force of the electric motor as the steering assisting force is transmitted to the ball screw mechanism through the sequentially engaged three gears, that is, the first gear, the second gear, and the third gear. Then, it is transmitted to the rack bar (see, for example, Patent Document 1).

In Patent Document 1, the housing is composed of first, second and third housings. A first gear is supported on the first and second housings. The second gear is supported by the first housing so that the backlash between the gears can be adjusted. The third gear is supported by the third housing.
Japanese Patent Laid-Open No. 10-278813

  However, since the first, second and third housings of Patent Document 1 are separate from each other, it is very difficult to position the central axes of the three gears in parallel with each other. As a result, the alignment error of the three gears tends to increase. If the gear alignment error is large, the tooth contact of the gear is deteriorated, and a steering sound, for example, a gear meshing sound generated when a steering operation is performed increases.

  Further, if the three gears are adjusted in parallel with each other, it takes time and manufacturing cost increases. Furthermore, since the three housings have a large number of parts, the manufacturing cost is high.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an inexpensive electric power steering apparatus that can suppress the meshing noise to be small.

The electric power steering device of the present invention includes a drive gear driven by an electric motor, a first support shaft that supports the drive gear, an intermediate gear that is driven by the drive gear, and a second support that supports the intermediate gear. a shaft, a driven gear driven by the intermediate gear comprises a third support shaft for supporting the driven gear, and a steering mechanism that is driven by the driven gear, the first supporting shaft Contact and third support shaft Are supported rotatably at a plurality of positions in the axial length direction of the respective support shafts in the same housing made of a single component , and the second support shaft is connected to the second support shaft in the housing. The rotation position is adjustable at a plurality of positions in the axial direction and is supported so as to be fixed at an arbitrary rotation position. The housing includes an opening hole having a diameter larger than that of the intermediate gear, The two spindles are installed at one end in the axial direction so that they can rotate together. Are outer circumference is characterized in that it comprises a fitted end plates in the openings. According to the present invention, it is possible to accurately position the drive gear, the intermediate gear, and the driven gear in a predetermined appropriate relationship by the same housing. As a result, the meshing sound can be reduced. Further, the number of parts of the housing can be reduced, and the manufacturing cost can be reduced.
In the present invention, the housing has positioning surfaces for positioning the central axes of the drive gear, the intermediate gear, and the driven gear in parallel to each other, and includes a first support shaft, a second support shaft, and a third support shaft. In some cases, the respective supporting shafts are rotatably supported at a plurality of positions in the axial length direction of the respective supporting shafts on the corresponding positioning surfaces.

  Further, in the present invention, the central axes of the drive gear, the intermediate gear, and the driven gear are arranged in parallel to each other, and the housing defines a first accommodation space for accommodating the drive gear, and the drive gear is rotatable. A second cylindrical portion that divides a second accommodating space for accommodating the intermediate gear and rotatably supports the intermediate gear, and a third for accommodating the driven gear. And a third cylindrical portion that divides the housing space and rotatably supports the driven gear. In this case, since the first, second and third cylindrical portions are easily formed in parallel to each other, the central axes of the drive gear, the intermediate gear and the driven gear are arranged in parallel to each other.

  Further, in the present invention, each of the accommodation spaces is opened at one end in the axial direction of the corresponding cylindrical portion, and any one of the accommodation spaces is opened in the opposite direction to the remaining two accommodation spaces. The accommodation space opened in the opposite direction to the two accommodation spaces may partially overlap at least one of the remaining two accommodation spaces when viewed from the axial direction of the accommodation space. . In this case, it contributes to miniaturization of the housing.

  In the present invention, the second accommodation space may be opened in the opposite direction to the first and third accommodation spaces. In this case, it contributes to miniaturization of the housing.

In the present invention, the first support shaft above SL is rotatably supported by a plurality of bearings which are held on the inner peripheral surface of the first tubular portion, the plurality of bearings, with the driving gear The first support shaft may be disposed on the same side in the axial direction. In this case, since the first support shaft is in a cantilever state, an assembly error between the first support shaft and the housing can be easily reduced. As a result, it is possible to suppress the occurrence of the inclination of the first spindle due to the assembly error. Further, since the plurality of bearings can stably support the cantilevered drive gear, the central axes of the drive gear and the intermediate gear are maintained parallel to each other.

In the present invention, the second support shaft above SL may have been supported by a support hole formed in the bottom portion of the second cylindrical portion and the inner peripheral surface of the inlet opening of the second cylindrical portion . In this case, since the second support shaft can be stably supported in the both-sided state, the occurrence of the inclination of the second support shaft, and hence the center axis of the intermediate gear, can be suppressed. Moreover, since the inner peripheral surface of the inlet opening of the second cylindrical portion is larger in diameter than the support hole, the occurrence of the inclination of the second support shaft can be suppressed.

Further, in the present invention, by the end plate, as the opening hole, the inlet opening is busy peeling of the second cylindrical portion, the outer periphery of the end plate is an inner peripheral surface of the inlet opening of the second cylindrical portion In some cases, an O-ring having elasticity is interposed between the fitting portion and the inner peripheral surface of the inlet opening of the second cylindrical portion. In this case, the clearance between the inner peripheral surface of the inlet opening and the fitting portion of the end plate is secured to facilitate assembly, and even if there is a clearance due to the aligning action of the elastic support using the O-ring. The occurrence of the inclination of the two spindles can be further suppressed. Further, a sealing effect can be obtained by the O-ring.

In the present invention, the end plate closes the inlet opening of the second cylindrical portion as the opening hole, and the end plate is secondly formed by the edge of the inlet opening of the second cylindrical portion. Including a receiving portion fastened to the edge of the inlet opening of the second cylindrical portion by a fastening mechanism, the fastening mechanism including the other end in the axial direction of the second spindle and A pressurizing member that presses the receiving portion of the end plate against the edge of the inlet opening of the second cylindrical portion by engaging the bottom portion of the second cylindrical portion and pulling the second support shaft in the axial direction. May include. In this case, since the pressure member and the receiving portion sandwich the housing in a pressed state therebetween, the housing and the second support shaft are stably fastened to each other. Since the receiving portion is received by the large-diameter inlet edge of the second cylindrical portion in a pressed state, the occurrence of the inclination of the second support shaft can be further suppressed.

  In the present invention, the steering mechanism includes a rack bar arranged coaxially with the driven gear, and an end cover is provided at the open end of the first and third cylindrical portions, and an outer surface of the end cover is provided on the outer surface of the end cover. The cylindrical motor housing of the electric motor is connected, and the cylindrical portion through which the rack bar is inserted is formed to protrude, and the outer diameter of the cylindrical portion is made smaller than the inner diameter of the third cylindrical portion. When the third cylinder portion is viewed in the axial direction, the third housing space and the motor housing may partially overlap. In this case, the housing can be reduced in size while arranging the cylindrical portion and the motor housing without difficulty.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a schematic diagram of an electric power steering apparatus according to an embodiment of the present invention. Referring to FIG. 1, an electric power steering apparatus 1 includes a steering shaft 4 that transmits a steering torque applied to a steering wheel 3 as a steering member in order to steer a steered wheel 2, and a steering torque from the steering shaft 4. For example, a steering mechanism 5 composed of a rack and pinion mechanism for steering the steered wheels 2, and an intermediate shaft 6 provided between the steering shaft 4 and the steering mechanism 5 as a shaft coupling for transmitting rotation therebetween. And have.

  The steering shaft 4 is inserted into the steering column 7 and is rotatably supported by the steering column 7. The steering column 7 is supported on the vehicle body 9 via a bracket 8. A steering wheel 3 is connected to one end of the steering shaft 4. An intermediate shaft 6 is connected to the other end of the steering shaft 4.

  The intermediate shaft 6 includes a power transmission shaft 10, a universal joint 11 provided at one end of the intermediate shaft 6, and a universal joint 12 provided at the other end of the intermediate shaft 6.

  The steering mechanism 5 supports a pinion shaft 13 as an input shaft, a rack bar 14 as a steered shaft extending in a lateral direction of the automobile (a direction orthogonal to the straight traveling direction), the pinion shaft 13 and the rack bar 14. And a rack housing 15. The pinion teeth 13a of the pinion shaft 13 and the rack teeth 14a of the rack bar 14 mesh with each other.

  The pinion shaft 13 is rotatably supported by the rack housing 15. The rack bar 14 is supported by the rack housing 15 so as to be linearly reciprocable. The rack housing 15 is fixed to the vehicle body 9. Both ends of the rack bar 14 protrude from both sides of the rack housing 15. Each end of the rack bar 14 is connected to the corresponding steering wheel 2 via a tie rod and a knuckle arm (not shown).

  When the steering wheel 3 is steered, the steering torque is transmitted to the steering mechanism 5 via the steering shaft 4 and the like. In the steering mechanism 5, the rotation of the pinion shaft 13 is converted into linear movement of the rack bar 14 along the lateral direction of the automobile by the pinion teeth 13a and the rack teeth 14a. Thereby, the steering wheel 2 can be steered.

  The electric power steering apparatus 1 can obtain a steering assist force according to the steering torque. That is, the electric power steering apparatus 1 includes a torque sensor 16 that detects steering torque, an ECU (Electronic Control Unit) 17 as a control unit, an electric motor 18 for assisting steering, and a speed reducer 19. Have.

  In the present embodiment, the electric motor 18 and the speed reducer 19 are provided in association with the steering mechanism 5.

  FIG. 2 is a perspective view of the steering mechanism 5 shown in FIG. FIG. 3 is a front view of the steering mechanism 5 of the electric power steering apparatus 1 shown in FIG.

  With reference to FIGS. 2 and 3, the rack housing 15 of the steering mechanism 5 includes a first housing 20 and a second housing 21.

  The first housing 20 includes a first cylindrical portion 20 a extending along the rack bar 14, and a second cylindrical portion 20 b as a portion for receiving and supporting the torque sensor 16 while supporting the pinion shaft 13. And an attached portion 20c attached to and supported by the vehicle body 9.

  The second housing 21 is supported by the vehicle body 9 via the first housing 20. The second housing 21 includes a cylindrical portion 21 a that extends along the rack bar 14, and a gear housing 21 b that supports the electric motor 18 and forms a part of the speed reducer 19. The cylindrical portion 21a is formed by a third cylindrical portion 35 of the housing body 31 described later and a cylindrical portion 32f of the end cover 32. The gear housing 21b is formed by a portion of the housing main body 31 other than the extending portion 70 of the third cylindrical portion 35 and a portion of the end cover 32 other than the cylindrical portion 32f.

  Returning to FIG. 1, the pinion shaft 13 has an input shaft 22, an output shaft 23, and a torsion bar 24. The input shaft 22 and the output shaft 23 are connected to each other on the same axis via a torsion bar 24. The input shaft 22 is connected to the steering wheel 3 via the intermediate shaft 6 and the steering shaft 4. Pinion teeth 13 a are provided at the end of the output shaft 23. When steering torque is input to the input shaft 22, the torsion bar 24 is elastically torsionally deformed, whereby the input shaft 22 and the output shaft 23 are relatively rotated.

  The torque sensor 16 is provided in association with the torsion bar 24 and detects torque based on a relative rotational displacement amount between the input shaft 22 and the output shaft 23 via the torsion bar 24. The torque detection result is given to the ECU 17.

  The ECU 17 controls the electric motor 18 based on the above torque detection result, a vehicle speed detection result given from a vehicle speed sensor (not shown), and the like.

  The electric motor 18 includes a motor housing 18a and an output shaft 18b that is rotatably supported by the motor housing 18a via a bearing. The output shaft 18b of the electric motor 18 is arranged in parallel with the direction in which the rack bar 14 extends, and a predetermined distance is separated between the output shaft 18b and the rack bar 14.

  The reduction gear 19 is driven by a drive gear 25 driven by the electric motor 18, an intermediate gear 26 driven by the drive gear 25, a driven gear 27 driven by the intermediate gear 26, and a driven gear 27. A nut 28 and a screw shaft 30 driven by the nut 28 via a plurality of balls 29 are provided.

  The drive gear 25, the intermediate gear 26, and the driven gear 27 are each composed of an oblique gear, and constitute an oblique gear mechanism.

  The nut 28, the ball 29, and the screw shaft 30 constitute a ball screw mechanism. The ball screw mechanism functions as a conversion mechanism that converts the rotational motion of the nut 28 into linear motion of the screw shaft 30. The nut 28 has a female screw. The nut 28 is fixed to the driven gear 27 so as to be integrally rotatable. For example, the nut 28 is integrally formed with the driven gear 27. The screw shaft 30 has a male screw. The screw shaft 30 is fixed to the rack bar 14 so as to move integrally. In the present embodiment, the male screw of the screw shaft 30 is formed on the outer periphery of the rack bar 14, and the screw shaft 30 and the rack bar 14 are integrally formed.

  The output of the electric motor 18 is transmitted to the rack bar 14 of the steering mechanism 5 via the drive gear 25, the intermediate gear 26, and the driven gear 27 in order, and further via the ball screw mechanism.

  When the steering wheel 3 is operated, the steering torque is detected by the torque sensor 16, and the electric motor 18 generates a steering assist force according to the torque detection result and the vehicle speed detection result. The steering assist force is transmitted to the rack bar 14 via the speed reducer 19, and at the same time, the movement of the steering wheel 3 is transmitted to the rack bar 14 of the steering mechanism 5, and the steered wheel 2 is steered. Specifically, the output rotation of the electric motor 18 is converted into a linear motion of the rack bar 14 while being decelerated by a speed reducer 19 as a transmission device, and is transmitted to the rack bar 14. As a result, steering is assisted. The

  FIG. 4 is a partial cross-sectional right side view of the main part of the steering mechanism 5 of the S4-S4 cross section shown in FIG. FIG. 5 is a cross-sectional view taken along a line S5-S5 shown in FIG. 6 is a cross-sectional view taken along a line S6-S6 shown in FIG.

  Referring to FIG. 5, in the present embodiment, center axis 25a of drive gear 25 and center axis 26a of intermediate gear 26 are arranged in parallel to each other. Further, the center axis 26a of the intermediate gear 26 and the center axis 27a of the driven gear 27 are arranged in parallel to each other. The rack bar 14, the nut 28, and the screw shaft 30 are disposed concentrically with the driven gear 27.

  4 and 6, the central axis 26a of the intermediate gear 26 is connected to the central axis 25a of the drive gear 25 and the follower when viewed from the axial direction S2 (corresponding to the direction in which the central axis 26a extends). A plane P0 (shown by a two-dot chain line) including the central axis 27a of the gear 27 is arranged at a predetermined distance in the normal direction of the plane P0.

  With reference to FIGS. 3 and 5, the second housing 21 includes a housing body 31 and an end cover 32. The housing body 31 is made of a single component and supports the drive gear 25, the intermediate gear 26 and the driven gear 27. As described above, the housing main body 31 made of a single component has a minimum number of components, so that the component cost and assembly cost can be reduced. The end cover 32 is made of a single part and is fixed to the housing body 31.

  In this embodiment, the drive gear 25, the intermediate gear 26, and the driven gear 27 are rotatably supported by a housing body 31 as the same housing.

  FIG. 7 is an exploded perspective view of the second housing 21 shown in FIG. FIG. 8 is an exploded perspective view of the second housing 21 shown in FIG. 3, and is a perspective view seen from a direction different from FIG. 9A, 9B, and 9C are a left side view, a front view, and a right side view of the housing main body 31 of the second housing 21 shown in FIG.

  With reference to FIGS. 7 and 8, the housing main body 31 includes a first cylindrical portion 33, a second cylindrical portion 34, and a third cylindrical portion 35. The 1st cylinder part 33, the 2nd cylinder part 34, and the 3rd cylinder part 35 are mutually connected, and are integrally formed by the metal, for example, aluminum alloy.

  With reference to FIG. 5 and FIG. 8, the 1st cylinder part 33 has comprised the bottomed cylindrical shape. The first cylinder portion 33 supports the drive gear 25. The first cylinder portion 33 defines a first accommodation space 33 a for accommodating the drive gear 25.

  Referring to FIGS. 7 and 8, the first cylindrical portion 33 has a first end portion 33b and a second end portion 33c arranged on opposite sides in the axial direction S1. The first end portion 33b is covered. The first accommodation space 33a is open only in one direction in the axial direction S1 (corresponding to the left side in FIG. 5) only by the second end 33c as one end of the first cylindrical portion 33. Yes. The second end portion 33c has an end surface 33e that intersects the axial direction S1 at a right angle.

  The axial direction S1 of the first cylindrical portion 33 corresponds to the direction in which the axial line of the first cylindrical portion 33 extends. The axial direction of the first housing space 33a, the axial direction of the drive gear 25, and a drive gear support described later. The axial direction of the shaft 38 coincides with each other.

  With reference to FIG. 5 and FIG. 7, the second cylindrical portion 34 has a bottomed cylindrical shape. The second cylinder portion 34 supports the intermediate gear 26. The second cylinder portion 34 defines a second accommodation space 34 a for accommodating the intermediate gear 26.

  Referring to FIGS. 7 and 8, the second cylindrical portion 34 has a first end portion 34b and a second end portion 34c arranged on opposite sides in the axial direction S2.

  The axial direction S2 of the second cylindrical portion 34 corresponds to the direction in which the axial line of the second cylindrical portion 34 extends. The axial direction S2 of the second accommodating space 34a and the axial direction of the intermediate gear support shaft 46, which will be described later, are mutually connected. They coincide with each other and are parallel to the axial direction of the intermediate gear 26 and the axial direction S1 of the first cylindrical portion 33.

  The first end 34b is a relatively large-diameter circular hole and forms an inlet opening 34h as an opening hole. The inlet opening 34h has a circular shape with an inner diameter longer by a predetermined length than the outer diameter of the intermediate gear 26, and functions as an inlet when the intermediate gear 26 is incorporated into the second accommodation space 34a during assembly. The first end portion 34b has an end surface 34d as an edge portion of the inlet opening 34h. The end face 34d intersects the axial direction S2 at a right angle.

  The second end portion 34c is closed, and a support hole 34i as a relatively small-diameter circular hole is formed at the center thereof. The support hole 34 i is provided to support the intermediate gear 26. The second end portion 34c has an end surface 34e as an edge portion of the support hole 34i. The end face 34e intersects the axial direction S2 at a right angle.

  The second accommodation space 34a is open only toward the other end in the axial direction S2 (corresponding to the right side in FIG. 5) only at the first end 34b as one end.

  With reference to FIG. 5 and FIG. 8, the 3rd cylinder part 35 has comprised the cylindrical shape. The third cylinder portion 35 rotatably supports the driven gear 27 and allows the rack bar 14 to pass therethrough. The third cylinder portion 35 defines a third accommodation space 35 a for accommodating the driven gear 27.

  Referring to FIGS. 7 and 8, the third cylindrical portion 35 has a first end portion 35b and a second end portion 35c that are arranged on opposite sides in the axial direction S3. Both the first end 35b and the second end 35c are open. The inner peripheral surface of the second end portion 35c is formed with a larger diameter than the inner peripheral surface of the first end portion 35b. It can be said that the third accommodation space 35a is open toward one side in the axial direction S3 at the second end portion 35c as one end of the third cylindrical portion 35 in the axial direction S3.

  The axial direction S3 of the third cylindrical portion 35 corresponds to the direction in which the axial line of the third cylindrical portion 35 extends. The axial direction of the third accommodating space 35a, the axial direction of the driven gear 27, and the axial direction of the rack bar 14 , And the axial direction of a driven gear support shaft 62 described later, and are parallel to the axial directions S1 and S2.

  The first end portion 35b of the third cylindrical portion 35 has an end surface 35d that intersects the axial direction S3 at a right angle. The second end portion 35c of the third cylindrical portion 35 has an end surface 35e that intersects the axial direction S3 at a right angle. The end surface 35e and the end surface 33e of the second end portion 33c of the first cylindrical portion 33 are disposed at the same position in the axial direction S3.

  Referring to FIGS. 9A, 9B, and 9C, the second accommodation space 34a is opened in the direction opposite to the first accommodation space 33a and the third accommodation space 35a adjacent to the second accommodation space 34a. Has been. Further, when the second accommodation space 34a is viewed from the axial direction S2, the second accommodation space 34a partially overlaps the first accommodation space 33a as the remaining accommodation space, and the remaining It partially overlaps with the third accommodation space 35a as the accommodation space.

  That is, a partial region 33a1 in the circumferential direction which is a part of the first accommodation space 33a and is in the vicinity of the second end 33c of the first cylindrical portion 33, and a part of the second accommodation space 34a. In addition, a partial region 34a1 in the circumferential direction in the vicinity of the first end 34b of the second cylindrical portion 34 overlaps with each other when viewed in the axial directions S1 and S2. Further, a part of the third accommodation space 35a and a part of the circumferential direction 35a2 in the vicinity of the second end 35c of the third cylindrical portion 35, and a part of the second accommodation space 34a. In addition, a partial region 34a2 in the circumferential direction in the vicinity of the first end 34b of the second cylindrical portion 34 overlaps with each other when viewed in the axial directions S2 and S3.

  Each of the regions 33a1, 34a1, 34a2, and 35a2 includes a portion that supports the corresponding gears 25, 26, and 27, as will be described later. Thereby, since each large cylinder part 33,34,35 can receive the corresponding gear 25,26,27 stably, the inclination of each gear 25,26,27 does not arise easily, The housing body 31 can be reduced in size.

  5 and 8, the end cover 32 is attached to the end portion of the housing body 31 in the axial direction S1, and is fixed by a plurality of bolts 36 as fixing members. The end cover 32 has a first portion 32a and a second portion 32b. The first portion 32a and the second portion 32b are formed integrally with each other, and are disposed adjacent to each other in a direction orthogonal to the axial direction S1.

  The first portion 32 a of the end cover 32 is disposed at the second end portion 33 c as the open side end portion of the first cylindrical portion 33. The first portion 32 a of the end cover 32 positions the electric motor 18 and is positioned on the housing body 31. The electric motor 18 is positioned on the housing body 31 via the end cover 32. The electric motor 18 is fixed to the housing body 31 with bolts 37 (see FIG. 11) as a fixing member. The end cover 32 is sandwiched between the electric motor 18 and the housing body 31.

  The second portion 32 b of the end cover 32 is disposed at the second end 35 c as the open side end of the third cylindrical portion 35, and covers the second end 35 c.

  The end cover 32 has a connection portion 32c between the first portion 32a and the second portion 32b. The connection portion 32 c covers the second end portion 35 c of the third cylinder portion 35 while supporting the electric motor 18.

  10A, 10B, and 10C are a left side view, a front view, and a right side view of the end cover 32 of the second housing 21 shown in FIG. FIG. 11 is a left side view of the steering mechanism 5 shown in FIG.

  10A, 10B, and 10C, the end cover 32 has an inner surface 32d that faces the housing main body 31, and an outer surface 32e that is opposite to the inner surface 32d.

  The inner surface 32d of the end cover 32 has a portion corresponding to the first portion 32a and a portion corresponding to the second portion 32b. The outer surface 32e of the end cover 32 has a portion corresponding to the first portion 32a and a portion corresponding to the second portion 32b.

  A portion of the inner surface 32d of the end cover 32 corresponding to the first portion 32a includes an annular end surface 32a1 in contact with the end surface 33e of the second end portion 33c of the first tube portion 33 of the housing body 31, and the first tube. And an annular convex portion 32a2 fitted to the inner peripheral surface of the second end portion 33c of the portion 33. The annular protrusion 32a2 is formed so as to protrude from the annular end face 32a1 in the axial direction S1. The outer periphery of the annular protrusion 32a2 is formed on a cylindrical surface.

  8 and 11, on the outer surface 32e of the end cover 32, a portion corresponding to the first portion 32a includes a cylindrical inner peripheral surface 32a3, and an annular end surface 32a4 surrounding the inner peripheral surface 32a3. have. The inner peripheral surface 32a3 is disposed concentrically on the outer periphery of the annular convex portion 32a2 of the inner surface 32d, and is fitted to the fitting portion at the end of the motor housing 18a of the electric motor 18. The end surface 32a4 of the outer surface 32e is formed in parallel with the end surface 32a1 of the inner surface 32d, and is in contact with the end surface of the end portion of the motor housing 18a of the electric motor 18.

  The fitting portion and the end surface of the end portion of the motor housing 18 a of the electric motor 18 constitute a connecting portion for connecting to the housing main body 31.

  The above-described inner peripheral surface 32a3 and end surface 32a4 of the end cover 32 function as a connecting portion for connecting to the connecting portion of the motor housing 18a of the electric motor 18, and the electric motor 18 can be positioned.

  Referring to FIGS. 9B and 10B, a portion of inner surface 32d of end cover 32 corresponding to second portion 32b has an annular end surface 32b1 and an annular convex portion 32b2. The annular protrusion 32b2 is formed to protrude in the axial direction S3 from the inner peripheral edge of the annular end surface 32b1. The outer periphery of the annular convex portion 32b2 is formed on a cylindrical surface and is fitted to the inner peripheral surface of the second end portion 35c of the third cylindrical portion 35 of the housing body 31. The annular end surface 32 b 1 is in contact with the end surface 35 e of the second end portion 35 c of the third cylindrical portion 35 of the housing body 31. Thereby, the end cover 32 is positioned on the housing body 31.

  Referring to FIGS. 5 and 10B, the portion corresponding to the second portion 32b on the outer surface 32e of the end cover 32 has a cylindrical portion 32f protruding in the axial direction S3. The threaded shaft 30 of the rack bar 14 is inserted into the cylindrical portion 32f so as to be movable in the axial direction S3. The cylindrical portion 32f is concentrically disposed on the outer periphery of the annular convex portion 32b2 of the inner surface 32d, and is concentrically disposed on the inner peripheral surface 68 of the third cylindrical portion 35 of the housing body 31.

  Referring to FIG. 11, the maximum outer diameter D1 of the cylindrical portion 32f is made smaller than the maximum inner diameter of the third cylindrical portion 35 (corresponding to the maximum outer diameter D2 of the third accommodation space 35a). ing. When viewed in the axial direction S3, the third housing space 35a of the third cylindrical portion 35 and the motor housing 18a partially overlap each other.

  FIG. 12 is an enlarged view of the main part of FIG. 5 and mainly shows the drive gear 25. Referring to FIG. 12, the electric power steering apparatus 1 includes a drive gear support shaft 38 as a first support shaft that supports the drive gear 25, and a plurality of bearings 39 and 40 that rotatably support the drive gear 25. A fixing member 41 and a lock nut 42 for restricting the axial movement of the bearings 39 and 40, and a shaft coupling 43 for connecting the drive gear support shaft 38 to the output shaft 18b of the electric motor 18. Yes.

  The drive gear 25 is rotatably supported by the first cylindrical portion 33 of the housing body 31 via the drive gear support shaft 38 and the two bearings 39 and 40. The first cylindrical portion 33 holds two bearings 39 and 40. The two bearings 39 and 40 support the drive gear support shaft 38 in a rotatable manner.

  The bearing 39 includes an outer ring 39a, an inner ring 39b, and a plurality of balls 39c as rolling elements that are movably interposed between the inner ring 39b and the outer ring 39a. The bearing 40 includes an outer ring 40a, an inner ring 40b, and a plurality of balls 40c as rolling elements that are movably interposed between the inner ring 40b and the outer ring 40a. Each of the bearings 39 and 40 is a deep groove type ball bearing.

  The drive gear 25 is an inclined gear, is formed in a substantially cylindrical shape with metal, and has a plurality of inclined teeth on the outer periphery.

  The drive gear 25 is fixed concentrically so that it can rotate integrally with one end of the drive gear support shaft 38 in the axial direction S1. The drive gear 25 and the drive gear support shaft 38 are integrally formed in this embodiment. The drive gear 25 and the drive gear support shaft 38 may be formed separately from each other and fixed to each other.

  The drive gear 25 is supported in a cantilever state. The plurality of bearings 39 and 40 are arranged on the same side of the drive gear support shaft 38 in the axial direction S1 with respect to the drive gear 25. One bearing 39 is disposed adjacent to the drive gear 25. The other bearing 40 is disposed away from the drive gear 25 in the axial direction S1. One bearing 39 and the other bearing 40 are arranged at a predetermined interval between the end surfaces facing each other.

  The drive gear support shaft 38 has a stepped cylindrical shape extending in the axial direction S1. The drive gear support shaft 38 has a large diameter portion 38a and a small diameter portion 38c connected to the large diameter portion 38a via an end wall 38b. The large diameter portion 38a is disposed adjacent to the drive gear 25 and is formed in a cylindrical surface. The small diameter part 38c is formed in the cylindrical surface, and is arrange | positioned on both sides of the drive gear 25 on both sides of the large diameter part 38a.

  The drive gear support shaft 38 rotates integrally with the shaft coupling 43, the first holding portion 38 d that holds the inner ring 39 b of one bearing 39, the second holding portion 38 e that holds the inner ring 40 b of the other bearing 40, and the shaft coupling 43. And a connecting portion 38f connected in such a manner.

  The connecting portion 38f is disposed at the other end on the opposite side of the drive gear 25 from the end of the drive gear support shaft 38 in the axial direction S1.

  The first holding portion 38 d restricts the axial movement of the inner ring 39 b of one bearing 39. The first holding portion 38d receives a fitting portion that fits on the inner peripheral surface of the inner ring 39b and a first end surface of the inner ring 39b, and restricts the movement of the inner ring 39b in one direction in the axial direction S1. And a second restricting portion that receives the other end face of the inner ring 39b and restricts the movement of the inner ring 39b in the other direction of the axial direction S1. The fitting portion of the first holding portion 38 d is composed of the outer peripheral surface of the large diameter portion 38 a adjacent to the drive gear 25. The first restricting portion of the first holding portion 38 d is formed from the side surface of the drive gear 25. The second restricting portion of the first holding portion 38d includes a retaining ring 44 fitted in a circumferential groove formed on the outer peripheral surface of the large diameter portion 38a.

  The second holding portion 38e restricts the axial movement of the inner ring 40b of the other bearing 40. The second holding portion 38e includes a fitting portion that is fitted to the inner peripheral surface of the inner ring 40b, and a regulating portion that receives one end face of the inner ring 40b and restricts the movement of the inner ring 40b in one direction of the axial direction S1. And have. The fitting portion of the second holding portion 38e is composed of the outer peripheral surface of the small diameter portion 38c. The restricting portion of the second holding portion 38e includes an end wall 38b.

  The drive gear support shaft 38 is restricted from moving on both sides in the axial direction S1 by the first cylindrical portion 33 of the housing body 31 via the fixing member 41 and the pair of bearings 39 and 40.

  Referring to FIGS. 12 and 7, the first cylindrical portion 33 includes a main portion 33 f as a cylindrical portion that forms the inner peripheral surface 45, and the first cylindrical portion 33 in the axial direction S <b> 1. And a bottom portion 33g disposed at the end portion 33b.

  The first accommodating space 33a is surrounded and partitioned by the inner peripheral surface 45 and the bottom 33g of the first cylindrical portion 33. The first accommodation space 33a is opened toward one side in the axial direction S1, specifically, toward the side opposite to the bottom 33g. In the first housing space 33a, the drive gear 25 as a housed component can be incorporated from the above-mentioned one side in the axial direction S1.

  The inner peripheral surface 45 includes a first portion 45a surrounding the drive gear 25, a second portion 45b holding the pair of bearings 39 and 40, a third portion 45c holding the fixing member 41, and an end. And a fourth portion 45d on which the cover 32 is fitted. The first portion 45a, the second portion 45b, the third portion 45c, and the fourth portion 45d are arranged adjacent to each other from the bottom 33g side along the axial direction S1 in this order. It is formed in a larger diameter in order.

  In the inner peripheral surface 45, the first portion 45a has a circular arc shape when viewed from the axial direction S1. An opening is formed between the arc ends. Through this opening, the inside of the first cylinder portion 33 communicates with the inside of the second cylinder portion 34. The second portion 45b is connected to the first portion 45a via the end wall 45e. The 2nd part 45b consists of a cylindrical surface continuous in the circumferential direction. The third portion 45c has a female screw. The fixing member 41 is screwed into the female screw. The fourth portion 45d is connected to the third portion 45c via the end wall 45f, and is formed of a cylindrical surface that is continuous in the circumferential direction.

  The fixing member 41 is engaged with the inner peripheral surface 45 of the first cylindrical portion 33 so that the position in the axial direction S1 can be adjusted. The fixing member 41 has an annular shape, and a male screw is formed on the outer periphery thereof. The fixing member 41 is screwed into the female thread of the third portion 45 c of the inner peripheral surface 45 in the inlet side opening of the first cylindrical portion 33. By adjusting the screwing amount of the fixing member 41, the outer ring 40a of the bearing 40 can be pressed and urged with a predetermined pressing force. Further, a lock nut 42 as a detent member is screwed into the male screw of the fixing member 41. An end surface of the lock nut 42 is in contact with an end wall 45 f in the opening on the inlet side of the first cylindrical portion 33. The lock nut 42 prevents the fixing member 41 from moving in the axial direction S1.

  The fixing member 41 functions as a preload application member for applying a preload in the axial direction S1 to the pair of bearings 39 and 40 as described below. As a result, since the bearing clearance (play) for the two bearings 39 and 40 is removed, it is difficult for the drive gear 25 to tilt when engaged.

  That is, the inner rings 39b, 40b of the two bearings 39, 40 are restricted from moving relative to each other in the axial direction S1, and are spaced apart from each other by a predetermined distance in the axial direction S1. They are arranged side by side. At the same time, in the outer rings 39a, 40a of the two bearings 39, 40, the end surfaces on the far side are in contact with the end wall 45e of the first cylindrical portion 33 and the end surface of the fixing member 41, and the axial direction S1. Has been received. Further, the outer rings 39a and 40a are allowed to move toward each other.

  In this state, the fixing member 41 is screwed into the first cylindrical portion 33, the position of the fixing member 41 is adjusted in the axial direction S1, the two outer rings 39a and 40a are brought close to each other, and the distance therebetween is adjusted to a predetermined distance. I have to. For example, the interval between the outer rings 39a and 40a in the axial direction S1 is shorter than the interval between the inner rings 39b and 40b.

  Thereby, it is possible to apply a pressing force as a predetermined preload in the axial direction S1 to both the bearings 39 and 40. The inner ring 39b and the outer ring 39a of the bearing 39 are urged toward each other in the direction opposite to the axial direction S1. At the same time, the inner ring 40b and the outer ring 40a of the bearing 40 are urged toward each other in the direction opposite to the axial direction S1. As a result, the bearing clearance between both bearings 39 and 40 is removed.

  FIG. 13 is an enlarged view of a main part of FIG. 5 and mainly shows the intermediate gear 26. Referring to FIG. 13, the electric power steering apparatus 1 includes an intermediate gear support shaft 46 as a second support shaft that supports the intermediate gear 26, an end plate 47 provided on the intermediate gear support shaft 46, and an intermediate gear. A plurality of bearings 48 and 49 supported by the support shaft 46 and rotatably supporting the intermediate gear 26, a spacer 50 separating the bearings 48 and 49, and axial movement of the bearings 48 and 49 A fixing member 51 and a lock nut 52 for regulating

  Further, the electric power steering apparatus 1 has a biasing mechanism 53 for adjusting the position of the intermediate gear 26 with respect to the housing body 31. In the biasing mechanism 53, the position of the central axis 26 a of the intermediate gear 26 can be adjusted by rotating the intermediate gear support shaft 46. Thereby, the backlash amount related to the intermediate gear 26 is adjusted.

  Further, the electric power steering apparatus 1 is a rotation restricting member for restricting the rotation of the intermediate gear support shaft 46 whose rotation position is adjusted, and has a fastening member 54 as a pressure member. The fastening member 54 constitutes a fastening mechanism 74 that fastens the intermediate gear support shaft 46 whose position has been adjusted as will be described later.

  The intermediate gear support shaft 46 is composed of a rod-shaped member extending in one direction. The intermediate gear support shaft 46 has a first end 46a as one end in the longitudinal direction (corresponding to the axial direction S2) and a second end 46b as the other end in the longitudinal direction. And an intermediate portion 46c in the longitudinal direction. An intermediate portion 46 c of the intermediate gear support shaft 46 supports the bearings 48 and 49. An end plate 47 is provided on the first end 46 a of the intermediate gear support shaft 46. The intermediate gear support shaft 46 and the end plate 47 are integrated so as to be able to rotate integrally and form a shaft unit.

  In the shaft unit of the present embodiment, the intermediate gear support shaft 46 and the end plate 47 are integrally formed and constitute a single component. The intermediate gear support shaft 46 and the end plate 47 may be formed separately from each other and fixed to each other.

  One bearing 48 includes an outer ring 48a, an inner ring 48b, and a plurality of balls 48c as rolling elements that are movably interposed between the inner ring 48b and the outer ring 48a. The other bearing 49 has an outer ring 49a, an inner ring 49b, and a plurality of balls 49c as rolling elements that are movably interposed between the inner ring 49b and the outer ring 49a. Each of the bearings 48 and 49 is a deep groove type ball bearing.

  The second cylinder portion 34 of the housing body 31 supports the above-described shaft unit. That is, the inner peripheral surface of the inlet opening 34 h of the second cylindrical portion 34 supports the first end portion 46 a of the intermediate gear support shaft 46 via the end plate 47. The inner peripheral surface of the support hole 34 i of the second cylindrical portion 34 directly supports a portion 46 f adjacent to the second end portion 46 b of the intermediate gear support shaft 46. The intermediate gear support shaft 46 rotatably supports the intermediate gear 26 via bearings 48 and 49.

  The intermediate gear 26 includes a metal core bar 55 having a cylindrical shape, and a tooth portion 56 that surrounds the core bar 55 and is formed of a synthetic resin member in an annular shape.

  A plurality of oblique teeth are formed on the outer periphery of the tooth portion 56. The tooth portion 56 is formed shorter in the axial direction S <b> 2 than the core metal 55. The inner peripheral surface of the tooth portion 56 is fixed to the outer periphery of the core bar 55 so as to rotate integrally.

  The inner peripheral surface of the cored bar 55 has a small diameter part 55a and a large diameter part 55b. The small diameter portion 55a and the large diameter portion 55b are connected via an annular end wall 55c. The small diameter portion 55 a is provided at one end portion of the inner peripheral surface of the core bar 55 in the axial direction S <b> 2 and is disposed adjacent to the end plate 47. The large diameter part 55b is provided in the other end part and intermediate part of the inner peripheral surface of the cored bar 55 in the axial direction S2. The large-diameter portion has a cylindrical portion that is provided at an intermediate portion in the axial direction S2 and extends straight in the axial direction S2. A circumferential groove extending in the circumferential direction is formed at the end of the large-diameter portion 55b in the axial direction S2 and on the end opposite to the small-diameter portion 55a. A retaining ring 57 is fitted in the circumferential groove.

  The inner peripheral surface of the cored bar 55 holds bearings 48 and 49. That is, the large-diameter portion 55b functions as a fitting portion that fits on the outer circumferences of the outer rings 48a and 49a of the two bearings 48 and 49. The end wall 55c functions as a restricting portion that receives one end face of the outer ring 48a of one bearing 48 and restricts movement of the outer ring 48a in one direction in the axial direction S2. The retaining ring 57 functions as a second restricting portion that receives the other end face of the outer ring 49a of the other bearing 49 and restricts the movement of the outer ring 49a in the other direction of the axial direction S2.

  As a result, the outer rings 48a and 49a of the two bearings 48 and 49 and the spacer 50 are fitted in the large diameter portion 55b of the inner peripheral surface of the core metal 55 side by side in the axial direction S2, and the axial direction S2 Is sandwiched between the end wall 55c and the retaining ring 57. As a result, the two bearings 48 and 49 are restricted from moving to both sides in the axial direction S <b> 2 with respect to the cored bar 55. The two bearings 48 and 49 are restricted from relative movement to both sides in the axial direction S2.

  The inner rings 48b and 49b of the two bearings 48 and 49 are rotatably supported by the intermediate gear support shaft 46 of the shaft unit, and are restricted from moving in the axial direction S2 with respect to the intermediate gear support shaft 46. Yes.

  The intermediate gear support shaft 46 has a central axis 46 d parallel to the longitudinal direction of the intermediate gear support shaft 46 and an outer peripheral surface 58. The outer peripheral surface 58 is a fitting portion in which the two bearings 48 and 49 are fitted to the restriction portion 58d that restricts the movement of the two bearings 48 and 49 in the axial direction S2 at the intermediate portion 46c of the intermediate gear support shaft 46. The joint 58e has an engaging portion 58f with which the fixing member 51 and the lock nut 52 are engaged. The restricting portion 58d, the fitting portion 58e, and the engaging portion 58f are arranged in this order in the axial direction S2 and are arranged concentrically with each other.

  The restricting portion 58d is disposed adjacent to the end plate 47 in the axial direction S2, and has a larger diameter than the fitting portion 58e.

  The fitting portion 58e is adjacent to the restricting portion 58d in the axial direction S2, is connected to the restricting portion 58d via the end wall 58g, and includes a cylindrical surface extending in a predetermined length parallel to the longitudinal direction.

  The engaging portion 58f is formed with a male screw as a screw portion. A fixing member 51 and a lock nut 52 are screwed into the male screw.

  The intermediate portion 46 c of the intermediate gear support shaft 46 holds the bearings 48 and 49 in order to support the intermediate gear 26 via the two bearings 48 and 49. That is, the restricting portion 58d functions as a restricting portion that receives one end face of the inner ring 48b of the bearing 48 and restricts the movement of the inner ring 48a in one direction in the axial direction S2. The fixing member 51 screwed into the male screw of the engaging portion 58f functions as a restricting portion that receives the other end face of the inner ring 49b of the bearing 49 and restricts the movement of the inner ring 49b in the other direction of the axial direction S2. Two bearings 48 and 49 are sandwiched between the fixing member 51 and the end wall 58 g via the spacer 50. Thereby, the movement of the two bearings 48 and 49 to both sides in the axial direction S2 with respect to the intermediate gear support shaft 46 is restricted. In the axial direction S2, the inner rings 48b and 49b of the two bearings 48 and 49 are restricted from moving relative to each other, but are allowed to move toward each other.

  The fixing member 51 functions as a preload applying member for applying a preload in the axial direction S2 to the pair of bearings 48 and 49 held as described above. As a result, since the bearing clearance (play) for the two bearings 48 and 49 is removed, it is difficult for the intermediate gear 26 to tilt when engaged.

  That is, the fixing member 51 is screwed into the engaging portion 58f, the position of the fixing member 51 is adjusted in the axial direction S2, the inner rings 48b and 49b are brought close to each other, and the distance therebetween is adjusted to a predetermined distance. For example, the distance between the inner rings 48b and 49b in the axial direction S2 is shorter than the distance between the outer rings 48a and 49a.

  Thereby, it is possible to apply a pressing force as a predetermined preload in the axial direction S2 to both the bearings 48 and 49. The inner ring 48b and the outer ring 48a of the bearing 48 are urged toward each other in the direction opposite to the axial direction S2. At the same time, the inner ring 49b and the outer ring 49a of the bearing 49 are urged toward each other in the direction opposite to the axial direction S2. As a result, the bearing clearance between both the bearings 48 and 49 is removed.

  Further, the outer peripheral surface 58 of the intermediate gear support shaft 46 has an eccentric portion 58 c that is eccentric with respect to the central axis 46 d of the intermediate gear support shaft 46 in the intermediate portion 46 c of the intermediate gear support shaft 46.

  The eccentric part 58c has the above-mentioned regulation part 58d, the above-mentioned fitting part 58e, and the above-mentioned engaging part 58f.

  Further, the outer peripheral surface 58 of the intermediate gear support shaft 46 is supported at a portion 46 f adjacent to the second end portion 46 b of the intermediate gear support shaft 46 and is directly supported by the second cylindrical portion 34. have.

  The supported portion 58a is disposed adjacent to the engaging portion 58f in the axial direction S2. The supported portion 58a is formed on a cylindrical surface having a smaller diameter than the eccentric portion 58c. This cylindrical surface has a central axis parallel to the longitudinal direction of the intermediate gear support shaft 46. This central axis corresponds to the central axis 46d of the intermediate gear support shaft 46 described above.

  Further, the intermediate gear support shaft 46 has an engagement portion 46 g with which the fastening member 54 is engaged at the second end portion 46 b of the intermediate gear support shaft 46.

  The engaging portion 46g is arranged on the outer peripheral surface 58 on the tip side of the supported portion 58a in the longitudinal direction of the intermediate gear support shaft 46. The engaging portion 46g has a male screw having a smaller diameter than the eccentric portion 58c and a smaller diameter than the cylindrical surface of the supported portion 58a. This male screw is screwed to the female screw of the fastening member 54.

  The first end portion 46a of the intermediate gear support shaft 46 functions as a supported portion 46e supported by the second tube portion 34 of the housing body 31 via the end plate 47, and a biasing mechanism 53 as will be described later. And a connecting portion 59. In the longitudinal direction of the intermediate gear support shaft 46, the connecting portion 59 is disposed at the tip. The first end 46 a and the outer periphery 47 a of the end plate 47 are arranged concentrically with the central axis 46 d of the intermediate gear support shaft 46.

  The end plate 47 is disposed at the first end 46 a of the intermediate gear support shaft 46 in the longitudinal direction of the intermediate gear support shaft 46. The end plate 47 is made of an annular plate member. The end plate 47 has a first main surface 47b and a second main surface 47c which are a pair of main surfaces facing each other. The first main surface 47 b is disposed in the second cylindrical portion 34 of the housing body 31. The second main surface 47 c is disposed on the opposite side to the first main surface 47 b and is disposed outside the second cylindrical portion 34. The first main surface 47 b and the second main surface 47 c intersect with the longitudinal direction of the intermediate gear support shaft 46 at a right angle. The end plate 47 has an outer periphery 47a.

  The outer periphery 47a is a fitting portion 47d as a first portion fitted into the inlet opening 34h of the second cylindrical portion 34 of the housing body 31, and the fitting portion 47d is adjacent to the fitting portion 47d in the axial direction S2 and is a second portion. It has the adjacent part 47e as a 2nd part arrange | positioned outside the cylinder part 34. As shown in FIG.

  The fitting portion 47d is formed with a predetermined length in the axial direction S2 from the first main surface 47b. The fitting portion 47d includes a cylindrical surface that extends continuously in an endless manner in the circumferential direction. The cylindrical surface is disposed concentrically with the central axis 46 d of the intermediate gear support shaft 46.

  The fitting portion 47d is formed with a circumferential groove that extends continuously in an endless manner in the circumferential direction. An O-ring 60 as a seal member is fitted in the circumferential groove. The O-ring 60 has elasticity and extends continuously in the circumferential direction. The O-ring 60 is interposed between the inner peripheral surface of the inlet opening 34h of the second cylindrical portion 34 and the fitting portion 47d of the outer periphery 47a of the end plate 47 in a state of being elastically deformed, and the elastic force is provided therebetween. Is sealed.

  Referring to FIGS. 4 and 13, end plate 47 has an outer peripheral edge portion 47 j that forms adjacent portion 47 e of outer periphery 47 a.

  The outer peripheral edge portion 47j is formed with a predetermined length from the second main surface 47c in the axial direction S2. The outer peripheral edge portion 47j is oval when viewed from the axial direction S2. The oval has an arc portion as a portion having a relatively long distance from the central axis 46d and a straight portion as a portion having a relatively short distance from the central axis 46d. The outer peripheral edge portion 47j does not form the fitting portion 47d of the outer periphery 47a.

  The outer peripheral edge portion 47j has two extending portions 47f that extend outward in the radial direction from the fitting portion 47d of the outer periphery 47a. The extending portion 47f forms the arc portion described above. In addition, the outer peripheral edge portion 47j has two cutout portions 47g1 and 47g2 that form the above-described linear portion. One cutout portion 47g1 is disposed in the vicinity of the third cylindrical portion 35 and functions as an escape portion that has escaped from the third cylindrical portion 35. In the present embodiment, the two extending portions 47f and the two cutout portions 47g1 and 47g2 are alternately adjacent to each other in the circumferential direction. The two extending portions 47f have a point-symmetric shape with the center axis 46d as the center of symmetry. The notch 47g2 may be abolished.

  The outer peripheral edge portion 47j functions as a cover portion that covers the end surface 34d as an edge portion of the inlet opening 34h. In the present embodiment, the extending portion 47f of the outer peripheral edge portion 47j covers only a portion 34d1 that is a part of the end surface 34d and overlaps the extending portion 47f when viewed from the axial direction S2.

  The two extending portions 47f are arranged on opposite sides in the radial direction. An outer periphery 47a corresponding to the extending portion 47f is formed on a cylindrical surface having a predetermined radius. The cylindrical surface is concentric with the fitting portion 47d of the outer periphery 47a, and is formed to have a larger diameter than the fitting portion 47d, and forms the maximum outer diameter of the outer periphery 47a, via the fitting portion 47d and the end surface 47h. Connected.

  The end surface 47h is in contact with the end surface 34d of the second cylindrical portion 34 and functions as a receiving portion received in the axial direction S2. The receiving portion is fastened to the end surface 34d of the second cylindrical portion 34 by the fastening member 54, and is fixed in a tightened state in the axial direction S2.

  The two notches 47g1 and 47g2 are disposed on the opposite sides in the radial direction and are formed in the same shape. Hereinafter, description will be given in accordance with the notch 47g1.

  The notch 47g1 has a portion that is radially outward from the fitting portion 47d of the outer periphery 47a and a portion that is recessed radially inward from the fitting portion 47d of the outer periphery 47a. The recessed portion exposes the portion 34d2 other than the portion 34d1 of the end surface 34d of the second cylindrical portion 34, and is connected to the fitting portion 47d via the end surface 47i.

  Returning to FIG. 13, the fastening member 54 is disposed at the second end 46 b of the intermediate gear support shaft 46 on the side opposite to the end plate 47 in the axial direction S <b> 2 and is disposed outside the second cylindrical portion 34. And disposed adjacent to the bottom 34g of the second cylindrical portion 34. On the outside of the second cylindrical portion 34, the bottom portion 34g is open. The fastening member 54 can be attached to the intermediate gear support shaft 46 from the outside of the second cylindrical portion 34.

  The fastening member 54 is a bottomed cylindrical member. The inner peripheral surface of the fastening member 54 is formed with a female screw as the engaging portion 54 b and is screwed into the male screw of the engaging portion 46 g of the end portion 46 b of the intermediate gear support shaft 46. The outer periphery of the fastening member 54 has a tool engaging portion 54 c that can engage with a tool for screwing the fastening member 54 into the intermediate gear support shaft 46. The tool engaging portion 54c includes planes facing each other. When the fastening member 54 is screwed into the intermediate gear support shaft 46, the fastening member 54 can freely connect the second end 46 b of the intermediate gear support shaft 46 to the bottom 34 g of the second cylindrical portion 34 of the housing body 31. Fastened at the pivot position.

  The fastening mechanism 74 has a fastening member 54 as a pressure member, an end plate 47, and a second cylinder portion 34. That is, the fastening member 54 and the end plate 47 are connected via the intermediate gear support shaft 46. At the same time, the second cylindrical portion 34 is sandwiched between the fastening member 54 and the end plate 47. When the fastening member 54 is screwed to the intermediate gear support shaft 46, the intermediate gear support shaft 46 is pulled in the axial direction S2, and the fastening member 54 and the end plate 47 try to approach each other. As a result, the end surface 54 a of the fastening member 54 is pressed against the end surface 34 e of the bottom 34 g of the second cylindrical portion 34, and at the same time, the end surface 47 h as a receiving portion of the end plate 47 is against the end surface 34 d of the second cylindrical portion 34. Pressed. As a result, the intermediate gear support shaft 46 is fixed to the second cylindrical portion 34.

  Referring to FIGS. 13 and 7, the second cylindrical portion 34 includes a main portion 34f as a cylindrical portion extending in the axial direction S2 and a bottom portion disposed at the second end 34c in the axial direction S2. 34g. The second cylindrical portion 34 has an inner peripheral surface 61.

  The inner peripheral surface 61 is a first portion 61a as a fitting portion into which the outer periphery 47a of the end plate 47 is fitted, and the first portion 61a is adjacent to the first portion 61a in the axial direction S2 and surrounds the tooth portion 56 of the intermediate gear 26. A second portion 61b, a third portion 61c adjacent to the second portion 61b in the axial direction S2 and surrounding the fixing member 41 and the lock nut 42, and a fourth portion as a fitting portion in which the intermediate gear support shaft 46 is fitted. 61d. The first, second, and third portions 61a, 61b, 61c are formed in the main body portion 34f. The fourth portion 61d is formed on the bottom 34g. The first portion 61a, the second portion 61b, the third portion 61c, and the fourth portion 61d are arranged adjacent to each other from the first end 34b side in this order along the axial direction S2. However, it is formed in a small diameter in this order.

  The first portion 61a is provided on a first end 34b as one end in the axial direction S2, and is formed of a cylindrical surface that is endlessly continuous in the circumferential direction. The fitting portion 47d of the outer periphery 47a of the end plate 47 is fitted into the first portion 61a without rattling. The first portion 61a forms an inlet opening 34h and corresponds to an inner peripheral surface of the inlet opening 34h (also referred to as an inner peripheral surface 61a of the inlet opening 34h).

  The second portion 61b is provided with an opening. Through this opening, the second tube portion 34 communicates with the inside of the first tube portion 33 and the third tube portion 35.

  The third portion 61 c surrounds a portion that is a part of the core metal 55 of the intermediate gear 26 and protrudes from the end face of the tooth portion 56 in the axial direction S <b> 2. The third portion 61 c includes a convex curved portion projecting inward in the radial direction corresponding to the first cylindrical portion 33 and the third cylindrical portion 35.

  The fourth portion 61d has a cylindrical surface, forms a support hole 34i, and corresponds to the inner peripheral surface of the support hole 34i (also referred to as the inner peripheral surface 61d of the support hole 34i). The supported portion 58a of the outer peripheral surface 58 of the intermediate gear support shaft 46 is fitted and supported by the fourth portion 61d.

  The inlet opening 34h and the support hole 34i as a pair of circular holes are arranged on the same axis line, and the center axis line of the inner peripheral surface of the first cylinder part 33 and the inner part of the third cylinder part 35 It arrange | positions in parallel with the center axis line of a surrounding surface. An end surface 34d as an edge of the inlet opening 34h is formed in an annular flat surface and intersects the central axis of the inner peripheral surface 61a of the inlet opening 34h perpendicularly. Further, an end surface 34e as an edge portion of the support hole 34i is provided on the outer surface of the bottom portion 34g. The end surface 34e is formed in an annular flat surface and intersects the central axis of the inner peripheral surface 61d of the support hole 34i perpendicularly.

  FIG. 14 is an enlarged view of a main part of FIG. 5, and mainly shows the driven gear 27. Referring to FIG. 14, the electric power steering apparatus 1 includes a driven gear support shaft 62 as a third support shaft that supports the driven gear 27 and a plurality of bearings 63 and 64 that rotatably support the driven gear 27. And two fixing members 65 and 66 for restricting the axial movement of the bearings 63 and 64.

  The third cylinder portion 35 holds two bearings 63 and 64. The two bearings 63 and 64 support the driven gear support shaft 62 so as to be rotatable. One bearing 63 has an outer ring 63a, an inner ring 63b, and a plurality of balls 63c as rolling elements that are movably interposed between the inner ring 63b and the outer ring 63a. The other bearing 64 includes an outer ring 64a, a pair of inner rings 64b and 64d, and a plurality of balls 64c as rolling elements that are movably interposed between the inner rings 64b and 64d and the outer ring 64a. The other bearing 64 is restricted by fixed members 65 and 66 from moving to both sides of the driven gear support shaft 62 and the housing body 31 in the axial direction S3. The driven gear support shaft 62 is connected to the driven gear 27 so as to rotate integrally, and supports the driven gear 27. Further, the driven gear support shaft 62 is connected to the nut 28 so as to rotate integrally, and is formed integrally with the nut 28 in this embodiment. The nut 28 drives the screw shaft 30 via the ball 29.

  The driven gear 27 is formed in a ring shape from metal. A plurality of inclined teeth are formed on the outer periphery of the driven gear 27.

  The driven gear support shaft 62 has a cylindrical shape and extends in the axial direction S3. The outer periphery 67 of the driven gear support shaft 62 has a first portion 67a in which one bearing 63 is fitted, a second portion 67b corresponding to the outer periphery of the nut 28, and a third portion in which the driven gear 27 is fitted. Portion 67c, a fourth portion 67d that forms the maximum outer diameter portion of the driven gear support shaft 62, and a fifth portion 67e that is smaller in diameter than the fourth portion 67d and into which the other bearing 64 is fitted. And a sixth portion 67f as a screw portion in which a male screw is formed.

  These first to sixth portions 67a, 67b, 67c, 67d, 67e, and 67f are sequentially arranged in the axial direction S3. The first, second, third, fifth, and sixth portions 67a, 67b, 67c, 67e, and 67f are formed to have a smaller diameter as the distance from the fourth portion 67d increases in the axial direction S3. Yes. Further, the third portion 67c and the fourth portion 67d are connected via an end wall 67g. Further, the fourth portion 67d and the fifth portion 67e are connected via an end wall 67h.

  The driven gear support shaft 62 is rotatably supported by two bearings 63 and 64 held by first and fifth portions 67 a and 67 e of the outer periphery 67.

  A third portion 67c of the outer periphery 67 of the driven gear support shaft 62 is formed in a cylindrical surface. The third portion 67c is fixed to the inner peripheral surface of the driven gear 27 by press fitting. Thus, both the relative movement and the relative rotation of the driven gear 27 and the driven gear support shaft 62 in the axial direction S3 are restricted. The side surface of the driven gear 27 is in contact with the end wall 67g.

  The fifth portion 67e is formed in a cylindrical surface. The fifth portion 67e is fitted to the inner peripheral surfaces of the pair of inner rings 64b and 64d of the bearing 64. One end surface of one inner ring 64b of the bearing 64 is in contact with the end wall 67h.

  The fixing member 65 is screwed to the male screw of the sixth portion 67f.

  The fixing member 65 has an annular shape and has an inner peripheral surface. An internal thread is formed on the inner peripheral surface. The end surface of the fixing member 65 is in contact with the end surface of the other inner ring 64d of the bearing 64 and presses this end surface. In the axial direction S3, the fixing member 65 and the end wall 67h sandwich and fix the pair of inner rings 64b and 64d of the bearing 64 therebetween.

  The nut 28 is formed integrally with the driven gear support shaft 62 and is supported by the third cylindrical portion 35 via the driven gear support shaft 62.

  The screw shaft 30 is threadedly engaged with the nut 28 and is disposed concentrically with the nut 28. In a state where the rotation of the screw shaft 30 around its axis is restricted, the nut 28 is relatively rotated around the axis of the screw shaft 30 so that the nut 28 and the screw shaft 30 are relatively relative to each other in the axial direction S3. Can move. The screw shaft 30 is disposed concentrically with the rack bar 14 and is integrally formed.

  The rack bar 14, the screw shaft 30, the nut 28, the driven gear support shaft 62, and the driven gear 27 are disposed concentrically on the third cylindrical portion 35 of the housing body 31 via a pair of bearings 63 and 64. 3 of the cylindrical portion 35.

  One bearing 63 is a deep groove ball bearing. The other bearing 64 is a single double-row outward angular ball bearing.

  The outer ring 64a of the bearing 64 has two raceway grooves. Each of the pair of inner rings 64b and 64d of the bearing 64 has a single raceway groove. One raceway groove of the outer ring 64a and one raceway groove of one inner ring 64b face each other, and a plurality of balls 64c are interposed therebetween. Further, the other raceway groove of the outer ring 64a and the raceway groove of the other inner ring 64d face each other, and a plurality of balls 64c are interposed therebetween. Thus, the bearing 64 has two rows of ball rows. In addition, in a state where the end faces facing each other of the pair of inner rings 64b and 64d are in contact with each other, each ball 64c is brought into contact with the corresponding raceway grooves of the inner rings 64b and 64d and the outer ring 64a with a predetermined preload. Has been.

  A predetermined amount of preload in the axial direction S3 is applied to the bearing 64. That is, the fixing member 65 is screwed to the male screw of the sixth portion 67f of the outer periphery 67 of the driven gear support shaft 62, whereby the pair of inner rings 64b and 64d are sandwiched between the fixing member 65 and the end wall 67h. The mutually facing end surfaces of the pair of inner rings 64b and 64d are in contact with each other. Thereby, each ball 64c is brought into contact with the corresponding raceway grooves of the inner rings 64b and 64d and the outer ring 64a, and from the corresponding raceway grooves of the inner rings 64b and 64d and the raceway groove of the outer ring 64a, the balls 64c in the axial direction S3. They are pressed against each other in opposite directions. As a result, the clearance (play) between each ball 64c and the corresponding track groove is removed. The outer ring 64a of the bearing 64 is fixed to the third cylindrical portion 35 as will be described later.

  The inner peripheral surface 68 of the third cylindrical portion 35 is disposed at the first end portion 35b in the axial direction S3 and forms a minimum inner diameter of the inner peripheral surface 68, and the first portion 68a. A second portion 68b holding one bearing 63, a third portion 68c containing the nut 28 adjacent to the second portion 68b, and a driven portion adjacent to the third portion 68c. A fourth portion 68d for housing the gear 27, a fifth portion 68e for housing the other bearing 64 adjacent to the fourth portion 68d, and a screw having an internal thread formed adjacent to the fifth portion 68e It has a sixth portion 68f as a portion and a seventh portion 68g formed on the cylindrical surface adjacent to the sixth portion 68f.

  These first to seventh portions 68a, 68b, 68c, 68d, 68e, 68f, 68g are arranged in the order described above in the first end portion 35b of the third cylindrical portion 35 in the axial direction S3. To the second end portion 35c are arranged adjacent to each other and have a larger diameter in the order described. The first portion 68a and the second portion 68b are connected via an end wall 68h. The fourth portion 68d and the fifth portion 68e are connected via an end wall 68i.

  The second portion 68b of the inner peripheral surface 68 of the third cylindrical portion 35 is formed by a cylindrical surface, and is fitted to the outer periphery of the outer ring 63a of the bearing 63 to receive this outer periphery. The end surface of the outer ring 63a is in contact with the end wall 68h. Thereby, the movement to the one direction of the axial direction S3 of the bearing 63 with respect to the 3rd cylinder part 35 is controlled.

  The inner diameter of the third portion 68 c is larger than the maximum outer diameter of the nut 28.

  The fourth portion 68d has a circular arc shape when viewed from the axial direction S3, and communicates with the inside of the second cylindrical portion 34 through the arc ends.

  The fifth portion 68e is formed by an endless cylindrical surface that is continuous in the circumferential direction. The outer periphery of the outer ring 64a of the bearing 64 and the outer periphery of the annular spacer 69 are fitted to the fifth portion 68e.

  The fixing member 66 is screwed into the female screw of the sixth portion 68f. The fixing member 66 has an annular shape, and a male screw is formed on the outer periphery thereof. As the fixing member 66 is screwed into the female screw of the sixth portion 68f, the outer ring 64a of the bearing 64 is sandwiched between the end wall 68i and the fixing member 66 via the spacer 69 in the axial direction S3. . As a result, the movement of the bearing 64 to both sides in the axial direction S3 with respect to the third cylinder portion 35 is restricted.

  The annular protrusion 32b2 of the end cover 32 is fitted into the seventh portion 68g.

  These first to seventh portions 68a, 68b, 68c, 68d, 68e, 68f, and 68g define the third accommodation space 35a inside thereof. The third accommodation space 35a is open to both sides in the axial direction S3. The third accommodation space 35a accommodates the driven gear 27 and the driven gear support shaft 62, and the screw shaft 30 is inserted therethrough.

  Referring to FIGS. 14 and 9B, the third cylindrical portion 35 has a predetermined length in the axial direction S3 from the axial position of the end surface 34d of the second cylindrical portion 34 toward the first end 35b. It has the extension part 70 as an extended cylinder part. The rack bar 14 is inserted into the extended portion 70 and the nut 28 is accommodated.

  Referring to FIG. 7 and FIG. 9C, the extending portion 70 is formed with a plurality of thin portions 70a formed to be thin in the radial direction and thick in the radial direction protruding radially outward from the thin portions 70a. And a plurality of thick portions 70b. The thin portions 70 a and the thick portions 70 b are alternately arranged in the circumferential direction of the third cylindrical portion 35. The plurality of thin wall portions 70a are equally arranged in the circumferential direction. The plurality of thick portions 70b are evenly arranged in the circumferential direction.

  The thick portion 70b is provided with a screw hole 71 as a connecting portion. A female screw is formed in the screw hole 71, and a bolt is screwed therein. Thereby, the 1st housing 20 and the 2nd housing 21 are connected (refer to Drawing 2).

  Two thick portions 70b adjacent to each other in the circumferential direction and a thin portion 70a between them form concave portions 70c, 70d, and 70e that are recessed in the radial direction. These recesses 70c, 70d, and 70e are provided at three locations in the present embodiment.

  In addition, the plurality of thick portions 70b are arranged at positions avoiding overlapping with the second cylindrical portion 34 when viewed from the axial direction S3. Thereby, of the three recesses 70 c, 70 d, 70 e, the recess 70 c closest to the second cylindrical portion 34 functions as an escape portion that escapes from the interference with the end plate 47.

  The concave portion 70c as the escape portion has a cutout portion 70f obtained by cutting out a part of the thin portion 70a in the circumferential direction into a concave curved shape. The notch 70f has a bowl shape having a circular arc shape as a concave curved surface when viewed from the axial direction S3. The center of curvature of the bowl shape is arranged concentrically at the center of the inner peripheral surface of the inlet opening 34 h of the second cylindrical portion 34. The curvature radius of the bowl shape is equal to or larger than the radius of the inner peripheral surface of the inlet opening 34h. The notch portion 70f is disposed outward of the inner peripheral surface of the inlet opening 34h in the radial direction of the inlet opening 34h of the second cylindrical portion 34. The recess 70 c and the notch 70 f as escape portions are provided for operating the biasing mechanism 53.

  FIG. 15 is a schematic diagram of the speed reducer 19 and the biasing mechanism 53 shown in FIG. Referring to FIGS. 13 and 15, the biasing mechanism 53 includes an intermediate gear support shaft 46, an end plate 47, an inlet opening 34 h as a pair of circular holes on the same axis line of the second cylindrical portion 34, and a support hole. 34i. By rotating the intermediate gear support shaft 46 about its center axis 46d, the center axis of the eccentric portion 58c of the outer periphery 58 of the intermediate gear support shaft 46 (corresponding to the center axis 26a of the intermediate gear 26) is moved. be able to. At this time, the central axis of the eccentric part 58c moves while drawing an arc-shaped trajectory centered on the central axis 46d. As a result, the biasing mechanism 53 moves the center axis 26a of the intermediate gear 26 in parallel with respect to the center axes 25a and 27a of both the drive gear 25 and the driven gear 27, thereby biasing and adjusting the position. Can do.

  In the present embodiment, the positions of the central axis 25 a of the drive gear 25 and the central axis 27 a of the driven gear 27 are restricted with respect to the housing body 31. On the other hand, the position of the central axis 26 a of the intermediate gear 26 can be adjusted by the biasing mechanism 53 with respect to the housing body 31. As a result, the central axis 26a of the intermediate gear 26 can be moved closer to or away from the central axis 25a of the drive gear 25. Similarly, the central axis 26a of the driven gear 27 can also be moved closer. Or move away. As a result, the backlash amount between the drive gear 25 and the intermediate gear 26 can be adjusted, and the backlash amount between the driven gear 27 and the intermediate gear 26 can be adjusted.

  Referring to FIGS. 13 and 15, in the biasing mechanism 53, the intermediate gear support shaft 46 is supported by the inlet opening 34 h and the support hole 34 i on the same axis, and the rotation position can be adjusted. . That is, in a state where the intermediate gear support shaft 46 is not fixed to the second cylindrical portion 34 of the housing body 31, the intermediate gear support shaft 46 is concentric with the inlet opening 34h and the support hole 34i. The rotation position of the intermediate gear support shaft 46 can be adjusted by rotating around the central axis 46d. In the state where the intermediate gear support shaft 46 is fixed to the second cylindrical portion 34, the intermediate gear support shaft 46 cannot be rotated.

  In this way, by adjusting the rotation position of the intermediate gear support shaft 46, the position of the center axis of the eccentric portion 58c of the outer periphery 58 (corresponding to the center axis 26a of the intermediate gear 26) is adjusted with respect to the center axis 46d. can do. As a result, the position of the intermediate gear 26 can be adjusted with respect to the drive gear 25 and the driven gear 27 positioned on the housing body 31.

  When the position of the intermediate gear 26 is adjusted, the backlash between the intermediate gear 26 and the drive gear 25 and the backlash between the intermediate gear 26 and the driven gear 27 both increase (or decrease) by substantially equal amounts. The central axes 25a, 26a, 27a of the gears 25, 26, 27 and the central axis 46d of the intermediate gear support shaft 46 are arranged as follows.

  That is, the first plane P1 including the central axis 46d of the intermediate gear support shaft 46 and the central axis 26a of the intermediate gear 26 is considered. Also, consider a second plane P2 that is orthogonal to a predetermined bisecting plane PD described below and includes a central axis 26a. Here, the predetermined bisecting plane PD is the third plane P3 including the central axis 25a of the drive gear 25 and the central axis 26a of the intermediate gear 26, the central axis 27a of the driven gear 27, and the center of the intermediate gear 26. This is a plane that passes through the central axis 26a of the intermediate gear 26 by dividing the angle DC formed by the fourth plane P4 including the axis 26a into two equal parts.

  The adjustment range of the rotation position of the intermediate gear support shaft 46 is restricted within a predetermined rotation position range DB as will be described later. When the rotational position of the intermediate gear support shaft 46 is adjusted within this range DB, the central axis 26a of the intermediate gear 26 has an arcuate movement locus centered on the central axis 46d when viewed from the axial direction S2. Draw and move. When the rotational position of the intermediate gear support shaft 46 is adjusted to the center position of the range DB, the first plane P1 coincides with the second plane P2.

  After adjusting the position of the intermediate gear 26 by the biasing mechanism 53, the intermediate gear support shaft 46 is fixed to the housing body 31 by the fastening member 54 of the fastening mechanism 74. Thereby, the position of the intermediate gear 26 can be fixed so as not to be adjusted.

  Further, when the rotation position of the intermediate gear support shaft 46 is adjusted, the third cylindrical portion 35 and the end plate 47 are corresponding to a predetermined rotation position range DB (see FIG. 15) of the intermediate gear support shaft 46. It is considered that mutual interference occurs between the two.

  Therefore, referring to FIGS. 4 and 13, in the present embodiment, in order to prevent interference between the third cylindrical portion 35 and the end plate 47, the third cylindrical portion 35 of the housing body 31 has a relief portion. A recess 70c is provided. The end plate 47 is also provided with a notch 47g1 as a relief portion. When the intermediate gear support shaft 46 is in a rotation position within a predetermined rotation position range DB, the recess 70c and the notch 47g1 face each other apart.

  Further, the biasing mechanism 53 has a stopper 75 that prevents the rotation of the intermediate gear support shaft 46 out of the predetermined rotation position range DB of the intermediate gear support shaft 46. This stopper 75 consists of a pair of convex part provided in the recessed part 70c. When the intermediate gear support shaft 46 rotates in one direction, if it tries to rotate beyond the end of the predetermined rotation position range DB, either one of the stoppers according to the rotation direction. 75 contacts the notch 47g1. The pair of stoppers 75 prevent rotation at both ends of the predetermined rotation position range DB. Thereby, since the predetermined rotation position range DB of the intermediate gear support shaft 46 is restricted, it is possible to prevent the intermediate gear support shaft 46 from rotating to an inappropriate rotation position.

  Referring to FIGS. 1 and 5, the electric power steering apparatus 1 of the present embodiment as described above includes a drive gear 25 driven by the electric motor 18, an intermediate gear 26 driven by the drive gear 25, A driven gear 27 driven by the intermediate gear 26 and a steering mechanism 5 driven by the driven gear 27 are provided. The drive gear 25, the intermediate gear 26, and the driven gear 27 are characterized by being rotatably supported by a housing body 31 as the same housing.

  According to the present embodiment, the housing main body 31 can accurately position the drive gear 25, the intermediate gear 26, and the driven gear 27 in a predetermined appropriate relationship. As a result, the meshing sound can be reduced. Since the number of parts of the housing body 31 can be reduced, the manufacturing cost can be reduced.

  Referring to FIG. 5, the center axis 25 a of the drive gear 25, the center axis 26 a of the intermediate gear 26, and the center axis 27 a of the driven gear 27 are arranged in parallel to each other. The housing body 31 defines a first housing space 33a for housing the drive gear 25, and a second cylinder for housing the intermediate gear 26, and a first cylindrical portion 33 that rotatably supports the drive gear 25. A second cylinder portion 34 that divides the housing space 34a and rotatably supports the intermediate gear 26, and a third housing space 35a that accommodates the driven gear 27 and rotates the driven gear 27. The third cylinder portion 35 to be supported is included. In this case, the first, second, and third cylindrical portions 33, 34, and 35 are easily formed in parallel with each other, so that the center axis 25 a of the drive gear 25, the center axis 26 a of the intermediate gear 26, and the driven gear 27 Center axes 27a are arranged in parallel to each other.

  9A, 9B and 9C, each of the accommodating spaces 33a, 34a, 35a is opened at one end in the axial direction S1, S2, S3 of the corresponding cylindrical portion 33, 34, 35, respectively. Yes. Any one of the accommodation spaces (corresponding to the second accommodation space 34a in this embodiment) corresponds to the remaining two accommodation spaces (in this embodiment, the first and third accommodation spaces 33a and 35a). Is open in the opposite direction. The second accommodation space 34a opened in the direction opposite to the remaining two accommodation spaces 33a and 35a is the same as the remaining two accommodation spaces 33a and 35a when viewed from the axial direction S2 of the accommodation space 34a. It partially overlaps both. In this case, it contributes to miniaturization of the housing body 31.

  7 and 8, in the present embodiment, the second accommodation space 34a is opened in the direction opposite to the first and third accommodation spaces 33a, 35a. In this case, it contributes to miniaturization of the housing body 31.

  Referring to FIG. 12, drive gear support shaft 38 as a first support shaft that supports drive gear 25 is provided. The drive gear support shaft 38 is rotatably supported by a plurality of bearings 39 and 40 held on the inner peripheral surface 45 of the first cylindrical portion 33. The plurality of bearings 39 and 40 are arranged on the same side of the drive gear support shaft 38 in the axial direction S1 with respect to the drive gear 25. In this case, since the drive gear support shaft 38 is cantilevered, the assembly error between the drive gear support shaft 38 and the housing body 31 can be easily reduced. As a result, it is possible to suppress the occurrence of the inclination of the drive gear support shaft 38 due to the assembly error. Further, since the plurality of bearings 39 and 40 can stably support the drive gear 25 in the cantilever state, the central axis 25a of the drive gear 25 and the central axis 26a of the intermediate gear 26 are maintained in parallel to each other.

  Referring to FIG. 13, an intermediate gear support shaft 46 is provided as a second support shaft that supports the intermediate gear 26. The intermediate gear support shaft 46 is supported by an inner peripheral surface 61d of a support hole 34i formed in the bottom 34g of the second cylindrical portion 34 and an inner peripheral surface 61a of the inlet opening 34h of the second cylindrical portion 34. ing. In this case, since the intermediate gear support shaft 46 can be stably supported with high rigidity in the both-sided state, it is possible to suppress the occurrence of the inclination of the intermediate gear support shaft 46 and consequently the central axis 26a of the intermediate gear 26. Moreover, since the inner peripheral surface 61a of the inlet opening 34h of the second cylindrical portion 34 has a larger diameter than the support hole 34i, the occurrence of the inclination of the intermediate gear support shaft 46 can be suppressed.

  Referring to FIG. 13, a large-diameter end plate 47 that closes the inlet opening 34 h of the second cylindrical portion 34 is provided at the first end portion 46 a as one end in the axial direction S <b> 2 of the intermediate gear support shaft 46. It has been. The outer periphery 47 a of the end plate 47 includes a fitting portion 47 d that is fitted to the inner peripheral surface 61 a of the inlet opening 34 h of the second cylindrical portion 34. An elastic O-ring 60 is interposed between the fitting portion 47d and the inner peripheral surface 61a of the inlet opening 34h of the second cylindrical portion 34. This ensures a gap between the inner peripheral surface 61a of the inlet opening 34h and the fitting portion 47d and facilitates assembly, and there is a gap due to the aligning action of the elastic support using the O-ring 60. Also, the occurrence of the inclination of the intermediate gear support shaft 46 can be further suppressed. Further, a sealing effect can be obtained by the O-ring 60.

  Referring to FIG. 13, a large-diameter end plate 47 that closes the inlet opening 34 h of the second cylindrical portion 34 is provided at the first end portion 46 a as one end in the axial direction S <b> 2 of the intermediate gear support shaft 46. It has been. The end plate 47 is received in the axial direction S2 of the intermediate gear support shaft 46 by an end face 34d as an edge of the inlet opening 34h of the second cylindrical portion 34, and is input to the second cylindrical portion 34 by the fastening mechanism 74. An end surface 47h is included as a receiving portion fastened to an end surface 34d as an edge portion of the opening 34h. The fastening mechanism 74 engages with the second end 46b as the other end in the axial direction S2 of the intermediate gear support shaft 46 and the bottom 34g of the second cylindrical portion 34 so that the intermediate gear support shaft 46 is moved in the axial direction S2. By pulling, a fastening member 54 as a pressurizing member that pressurizes the end surface 47 h as an edge of the inlet opening 34 h of the second cylindrical portion 34 as a receiving portion of the end plate 47 is included.

  In this case, the fastening member 54 and the end surface 47h as the receiving portion are connected by the intermediate gear support shaft 46, and the housing main body 31 is held in a pressed state therebetween, so that the housing main body 31 and the intermediate gear support shaft 46 are connected to each other. Fastened to each other stably. Since the end surface 47h as the receiving portion is received in a pressed state by the end surface 34d as the edge portion of the large-diameter inlet opening 34h of the second cylindrical portion 34, the inclination of the central axis 26a of the intermediate gear 26 is further generated. Can be suppressed.

  Referring to FIGS. 5 and 11, steering mechanism 5 includes rack bar 14 arranged coaxially with driven gear 27. An end cover 32 is provided to cover the second end portions 33c and 35c as the open side end portions of the first tube portion 33 and the third tube portion 35. A cylindrical motor housing 18a of the electric motor 18 is connected to the outer surface 32e of the end cover 32, and a cylindrical portion 32f into which the rack bar 14 is inserted is formed to protrude. The outer diameter of the cylindrical portion 32 f is smaller than the inner diameter of the third cylindrical portion 35. When the third cylindrical portion 35 is viewed in the axial direction S3, the third accommodation space 35a and the motor housing 18a partially overlap. In this case, the housing body 31 can be reduced in size while arranging the cylindrical portion 32f and the motor housing 18a without difficulty.

  4, 5, 12, 13, and 14, the housing main body 31 made of a single part has the central axes 25 a, 26 a, 27 a of the gears 25, 26, 27 parallel to each other. The following cylindrical surfaces as positioning surfaces for positioning, that is, the second portion 45b of the inner peripheral surface 45 as the bearing holding surface of the first cylindrical portion 33, the support holes 34i of the second cylindrical portion 34, An inlet opening 34h of the second cylindrical portion 34 and a fifth portion 68e of the inner peripheral surface 68 as a bearing holding surface of the third cylindrical portion 35 are integrally formed. This is preferable for suppressing the occurrence of inclination between the central axes 25a, 26a, 27a of the gears 25, 26, 27.

  In addition to this, since the end surfaces 34d and 34e forming a pair of parallel planes as a fixing surface for fixing the intermediate gear support shaft 46 after the position adjustment are formed integrally with the above-described positioning surface, It is preferable to suppress the occurrence of the inclination.

  Since one end surface 34d forming a pair of parallel planes has a large diameter and the other end surface 34e has a small diameter, the direction of the central axis 46d of the intermediate gear support shaft 46 is mainly the edge of the large-diameter inlet opening 34h. It is regulated by the end face 34d. Therefore, there is no possibility that the intermediate gear support shaft 46 is inclined when the screw is engaged with the fastening member 54 in contact with the small-diameter end surface 34e.

  The second portion 45b of the inner peripheral surface 45 as the bearing holding surface of the first cylindrical portion 33, the inner peripheral surface of the inlet opening 34h of the second cylindrical portion 34, and the bearing holding surface of the third cylindrical portion 35 Since each of the fifth portion 68e of the inner peripheral surface 68 is formed with a larger diameter than the corresponding gears 25, 26, 27, it is preferable to suppress the occurrence of inclination.

  Further, since the bearings 39 and 40 that support the drive gear support shaft 38 are separated from each other and are plural, it is easy to ensure a long axial distance between the ball rows of the bearings 39 and 40. At the same time, the axial distance between the ball rows of the pair of bearings 39 and 40 is such that the second portion 45b of the inner peripheral surface 45 serving as the bearing holding surface of the first cylindrical portion 33 that supports the drive gear support shaft 38. The size is equal to or larger than the inner diameter. Thereby, the drive gear support shaft 38 can be stably supported, which contributes to suppressing the occurrence of inclination between the drive gear 25 and the intermediate gear 26.

  Further, the end plate 47 has a cutout portion 47g2 having the same shape as the cutout portion 47g1 on the side opposite to the cutout portion 47g1 as a relief portion in the radial direction. As a result, the end face 47h as the receiving portion of the end plate 47 is disposed at a symmetric position in the radial direction across the central axis 46d, so that the fastening force can be received in a well-balanced manner and it is difficult to produce an inclination at the time of fastening. Can do.

  Moreover, the following modifications can be considered about this embodiment. In the following description, differences from the above-described embodiment will be mainly described, and the same components are denoted by the same reference numerals and description thereof is omitted. For example, the drive gear 25, the intermediate gear 26, and the driven gear 27 may be spur gears that mesh with each other.

  In each of the above-described embodiments, it is also conceivable that the overlap between the third housing space 35a and the motor housing 18a when viewed from the axial direction S3 is avoided. Moreover, the case where the end cover 32 is abolished is also considered.

  16 is a cross-sectional view of a modified example of the fastening member shown in FIG. Referring to FIG. 16, the fastening member 54 has a shaft portion 54d formed with a male screw, and a large-diameter head portion 54e formed at the end of the shaft portion 54d and including the tool engaging portion 54c. May be. That is, an internal thread as an engaging portion 46 g is formed at the second end portion 46 b of the intermediate gear support shaft 46. A male screw as the engaging portion 54b of the fastening member 54 is screwed into the female screw. Also in this case, the intermediate gear support shaft 46 can be fastened to the housing body 31 in the same manner as the fastening member 54 having the above-described female screw.

  In FIG. 16, the support hole 34 i supports the second end portion 46 b of the intermediate gear support shaft 46. Also in this case, the support hole 34i can stably support the intermediate gear support shaft 46 as in the case of supporting the portion 46f adjacent to the end portion 46b as described above.

  Further, as the fastening mechanism 74, it is conceivable to fix only the end plate 47 to the second cylindrical portion 34.

  In each of the above-described embodiments, a circumferential groove may be formed on the inner circumferential surface of the inlet opening 34h of the second cylindrical portion 34, and the O-ring 60 may be fitted into the circumferential groove. In this case, the circumferential groove of the fitting portion 47d of the outer periphery 47a of the end plate 47 can be eliminated. In short, an elastic O-ring 60 may be interposed between the fitting portion 47d of the outer periphery 47a of the end plate 47 and the inner peripheral surface of the inlet opening 34h of the second cylindrical portion 34. Note that the O-ring 60 may be abolished.

  Further, in each of the above-described embodiments, it is conceivable that the intermediate gear support shaft 46 and the end plate 47 are formed separately and are fitted and fixed to each other so that they can be positioned concentrically. It is also conceivable that the intermediate gear support shaft 46 and the end plate 47 which are separate from each other are fitted concentrically with each other so as to be relatively rotatable. In this case, when the rotational position of the intermediate gear support shaft 46 is adjusted, the end plate 47 is fixed to the housing body 31 and the intermediate gear support shaft 46 and the end plate 47 are relatively rotated. After the adjustment, the intermediate gear support shaft 46 and the end plate 47 are fixed.

  In each of the above-described embodiments, the drive gear support shaft 38 may be supported by a single double row type bearing (not shown).

  Further, when the second accommodation space 34a is viewed from the axial direction S2, the second accommodation space 34a partially overlaps only one of the first and third accommodation spaces 33a and 35a. Is also possible. Also in this case, the housing body 31 can be downsized. In short, when the second accommodation space 34a is viewed from the axial direction S2, the second accommodation space 34a is part of at least one of the first and third accommodation spaces that are the remaining two accommodation spaces. As long as they overlap.

  In each of the above-described embodiments, it is also conceivable that the opening direction of each cylindrical portion 33, 34, 35 is different from the above-described direction. In short, any one of the accommodation spaces only needs to be opened in the opposite direction to the remaining two accommodation spaces. Furthermore, any one accommodation space is opened in the opposite direction to the remaining two accommodation spaces, and the accommodation space opened in the opposite direction to the remaining two accommodation spaces is the axial direction S1 of the accommodation space. , S2 and S3, it preferably overlaps at least one of the remaining two accommodation spaces.

  Moreover, in each above-mentioned embodiment, it is also considered that the biasing mechanism 53 is abolished. In this case, the housing main body 31 supports the gears 25, 26, and 27 so that the position cannot be adjusted. It is also conceivable that at least a part of the three gears 25, 26, 27 is exposed as the housing body 31. Even in these cases, the same housing body 31 can support the gears 25, 26, and 27 without inclining, and contributes to reducing the meshing noise. In short, it is only necessary that the same housing body 31 supports each of the gears 25, 26, and 27. In addition, various design changes can be made within the scope of matters described in the claims.

It is a side view of schematic structure of the electric power steering device of one embodiment of the present invention. FIG. 2 is a perspective view of the steering mechanism shown in FIG. FIG. 3 is a front view of the steering mechanism of the electric power steering apparatus shown in FIG. 4 is a partial cross-sectional right side view of the main part of the steering mechanism of the S4-S4 cross section shown in FIG. FIG. 5 is a cross-sectional view taken along a line S5-S5 shown in FIG. 6 is a cross-sectional view taken along a line S6-S6 shown in FIG. FIG. 7 is an exploded perspective view of the second housing shown in FIG. FIG. 8 is an exploded perspective view of the second housing shown in FIG. 3 from a different viewpoint from FIG. 7. 9A, 9B and 9C are a left side view, a front view and a right side view of the housing body of the second housing shown in FIG. 10A, 10B, and 10C are a left side view, a front view, and a right side view of the end cover of the second housing shown in FIG. 11 is a left side view of the steering mechanism shown in FIG. FIG. 12 is an enlarged view of a main part of FIG. 5 and mainly shows a drive gear. FIG. 13 is an enlarged view of a main part of FIG. 5 and mainly shows an intermediate gear. FIG. 14 is an enlarged view of a main part of FIG. 5 and mainly shows a driven gear. FIG. 15 is a schematic diagram of the reduction gear and the biasing mechanism shown in FIG. It is sectional drawing of the modification of the fastening member shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Electric power steering apparatus, 5 ... Steering mechanism, 14 ... Rack bar, 18 ... Electric motor, 18a ... Motor housing, 25 ... Drive gear, 25a ... Center axis of drive gear, 26 ... Intermediate gear, 26a ... Intermediate gear Central axis 27, driven gear 27 a Central axis of driven gear 31, housing body (housing) 32, end cover 32 e, outer surface of end cover 32 f cylindrical portion of end cover 33 ... 1st cylinder part, 33a ... 1st accommodation space, 33c ... 2nd edge part (opening side edge part of 1st cylinder part), 34 ... 2nd cylinder part, 34a ... 2nd accommodation space 34b ... first end, 34d ... end face (edge), 34g ... bottom, 34h ... inlet opening, 34i ... support hole, 35 ... third tube, 35a ... third housing space, 35c ... first End of 2 (open side end of the third cylinder) , 38 ... drive gear support shaft (first support shaft), 39, 40 ... bearing, 45 ... inner peripheral surface of (first tube portion), 46 ... intermediate gear support shaft, 46a ... first end ( One end in the axial direction of the intermediate gear support shaft, 46b ... Second end (the other end in the axial direction of the intermediate gear support shaft), 47 ... End plate, 47a ... Outer periphery (of the end plate), 47d ... (End plate) Fitting part, 47h ... end face (receiving part), 54 ... fastening member (pressurizing member), 60 ... O-ring, 61a ... inner peripheral surface, 74 ... fastening mechanism, D1 ... (in the cylindrical part) Outer diameter, D2 ... Inner diameter (of the third cylinder), S1, S2, S3 ... Axial direction

Claims (10)

Driven by an electric motor, a first support shaft supporting the drive gear, an intermediate gear driven by the drive gear, a second support shaft supporting the intermediate gear, and driven by the intermediate gear A driven gear, a third support shaft for supporting the driven gear, and a steering mechanism driven by the driven gear;
The first supporting shaft Contact and third support shaft, in the same housing of a single part, is rotatably supported at a plurality of positions in the axial direction of the axles,
The second support shaft is supported in the housing so that the rotation position is adjustable at a plurality of positions in the axial length direction of the second support shaft and is fixed at an arbitrary rotation position.
The housing includes an opening hole having a diameter larger than that of the intermediate gear,
The electric power steering apparatus, wherein the second support shaft includes an end plate which is provided at one end in the axial direction so as to be integrally rotatable and whose outer periphery is fitted in the opening hole .   2. The housing according to claim 1, wherein the housing has positioning surfaces for positioning the central axes of the driving gear, the intermediate gear, and the driven gear in parallel with each other, and the first supporting shaft, the second supporting shaft, and the third supporting shaft. An electric power steering device in which the support shafts are rotatably supported at a plurality of positions in the axial length direction of each support shaft on the corresponding positioning surfaces. In Claim 1 or 2, the central axes of the drive gear, the intermediate gear and the driven gear are arranged in parallel to each other,
The housing defines a first housing space for housing the drive gear and a first cylinder portion for rotatably supporting the drive gear, and a second housing space for housing the intermediate gear. A second cylindrical portion that rotatably supports the intermediate gear, and a third cylindrical portion that divides a third accommodation space for accommodating the driven gear and supports the driven gear rotatably. An electric power steering device. In Claim 3, each said accommodation space is each opened at one end of the direction of an axis of a corresponding cylinder part,
Any one accommodation space is opened in the opposite direction to the remaining two accommodation spaces, and the accommodation space opened in the opposite direction to the remaining two accommodation spaces is viewed from the axial direction of the accommodation space. Sometimes, the electric power steering device is characterized in that it partially overlaps at least one of the remaining two accommodation spaces.   5. The electric power steering apparatus according to claim 4, wherein the second accommodation space is opened in a direction opposite to the first and third accommodation spaces.   In any one of Claims 3-5, the said 1st spindle is rotatably supported by the some bearing hold | maintained at the internal peripheral surface of the 1st cylinder part, The said some bearing is An electric power steering device, wherein the electric power steering device is disposed on the same side in the axial direction of the first support shaft with respect to the drive gear.   The second support shaft according to any one of claims 3 to 6, wherein the second support shaft is supported by an inner peripheral surface of a support hole formed in a bottom portion of the second cylindrical portion and an inlet opening of the second cylindrical portion. An electric power steering device. In any one of claims 3 7, by the end plate, as the opening hole, the inlet opening is busy peeling of the second cylindrical portion, the outer periphery of the end plate, the second tubular portion It includes a fitting portion fitted to the inner peripheral surface of the inlet opening, and an elastic O-ring is interposed between the fitting portion and the inner peripheral surface of the inlet opening of the second cylindrical portion. An electric power steering device. 9. The inlet opening of the second cylinder part as the opening hole is closed by the end plate according to claim 3, and the end plate is an inlet opening of the second cylinder part. Including a receiving portion that is received in the axial direction of the second support shaft by the edge portion of the second cylindrical portion and fastened to the edge portion of the inlet opening of the second cylindrical portion by the fastening mechanism
The fastening mechanism engages with the other axial end of the second support shaft and the bottom of the second cylindrical portion, and pulls the second support shaft in the axial direction, thereby moving the receiving portion of the end plate to the first position. An electric power steering apparatus comprising a pressure member that pressurizes an edge of the inlet opening of the two cylindrical portions. In any one of Claims 3-9, the said steering mechanism contains the rack bar arrange | positioned coaxially with a driven gear,
End covers are provided at the open end portions of the first and third tube portions, and a cylindrical motor housing of the electric motor is connected to the outer surface of the end cover, and a rack bar is inserted through the end cover. A protruding part is formed,
The outer diameter of the cylindrical portion is smaller than the inner diameter of the third cylindrical portion, and the third housing space and the motor housing partially overlap when the third cylindrical portion is viewed in the axial direction. An electric power steering device.

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