JP2008213536A - Electric power steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric power steering device capable of preventing occurrence of wear of an intermediate gear in a gear pair mechanism with parallel axes and abnormal sound. <P>SOLUTION: This electric power steering device 1 has the gear pair mechanism with parallel axes 19a for reducing rotational speed outputted by an electric motor 18 for assisting steering. The gear pair mechanism with parallel axes 19a includes an idle gear 26 supported on an outer peripheral face 37d of an intermediate shaft 37 supported by a rack housing 15 to rotate freely through a bearing 39. The idle gear 26 includes a metallic sleeve 43 and an annular member 44 made of synthetic resin and fitted into the outer periphery 43e of the sleeve 43 to rotate integrally. This electric power steering device 1 is provided with a pair of annular flange plates 52 approaching and opposing to a pair of side faces 44b of the member 44 made of synthetic resin, respectively, or blocking parts 53, 55 for blocking a tooth groove 26e at both ends 26f in the direction of tooth width as a lubricant scattering prevention member for preventing lubricant from being scattered from meshing parts 26b, 26c of the idle gear 26 to sides of the idle gear 26. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to an electric power steering apparatus.

  The electric power steering apparatus includes an electric power steering apparatus called a rack assist type. This type of electric power steering apparatus has an electric motor for assisting steering, a parallel shaft gear mechanism as a speed reducer, and a ball screw mechanism. The ball screw mechanism has a ball screw shaft and a ball nut. A ball screw shaft is connected to a rack shaft of a rack and pinion type steering mechanism. The output of the electric motor is transmitted to the rack shaft via the speed reducer and the ball screw mechanism, and linearly moves the rack shaft.

The parallel shaft gear mechanism has three gears: a drive gear, an idle gear, and a driven gear. When the electric motor drives the drive gear, the rotation of the drive gear is transmitted to the driven gear via the idle gear. The rotation center axes of these three gears are arranged in parallel to each other.
Further, as a technique for suppressing gear wear, a technique for forming a groove for holding a lubricant on each tooth surface of the gear is known (see, for example, Patent Document 1).
JP 2003-207031 A

Since the idle gear of the parallel shaft gear mechanism is made of resin and meshes with both the drive gear and the driven gear, the idle gear is likely to be worn and as a result, noise is likely to occur. As a cause of wear, it is conceivable that when the gears mesh with each other, the lubricant is scattered from between the gear teeth to the side of the gear, and the lubricating action by the lubricant becomes insufficient.
Moreover, since the groove | channel for lubrication holding | maintenance of patent document 1 is open | released by the side surface of the gear, when the gears mesh, the scattering of the lubricant to the side of the gear cannot be prevented. Therefore, even if the technique of Patent Document 1 is applied to the above-described parallel shaft gear mechanism, wear cannot be suppressed.

  Accordingly, an object of the present invention is to provide an electric power steering device that can suppress wear of an idle gear of a parallel shaft gear mechanism.

  The electric power steering apparatus (1) of the present invention includes an idle gear (26) having a tooth portion (26d) formed of a synthetic resin (44), and decelerates the output rotation of the steering assist electric motor (18). A parallel shaft gear mechanism (19a), a housing (15) for housing the parallel shaft gear mechanism, a lubricant (G) filled in at least the meshing portions (26b, 26c) of the idle gear in the housing, A lubricant scattering suppression member (52, 53, 55) that suppresses the scattering of the lubricant from the gear meshing portion to the side (S2) of the idle gear is provided. According to the present invention, when the gears of the parallel shaft gear mechanism mesh with each other, since the lubricant is held in the meshing portion of the idle gear, it is possible to suppress the occurrence of wear due to the lack of lubricant over a long period of time, As a result, generation | occurrence | production of unusual noise can be suppressed.

  In the present invention, the lubricant scattering suppression member may include a counter plate (52) provided so as to rotate integrally with the idle gear and opposed from the side of the meshing portion of the idle gear. In this case, scattering of the lubricant from the meshing portion of the idle gear to the side of the idle gear can be suppressed by the counter plate. In addition, since the lubricant scattering suppression member is provided in the idle gear, it is possible to suppress the lubricant scattering in all the meshing portions of the idle gear and the plurality of other gears, and the structure for this can be simplified.

  In the present invention, the idle gear includes a metal sleeve (43) rotatably supported on the outer periphery (37d) of the support shaft (37) supported by the housing via a rolling bearing (39), An annular synthetic resin member (44) fitted to the outer periphery (43e) of the sleeve so as to be integrally rotatable, and the counter plate is attached to the outer periphery of the sleeve by welding, press-fitting, adhesion or caulking, There may be a case where a metal annular flange plate (52) that faces and faces each of the pair of side surfaces (44b) of the member. In this case, the annular flange plate can suppress the scattering of the lubricant from the meshing portion of the idle gear to the side of the idle gear. Moreover, a lubricant scattering suppression member can be simply realized by attaching the annular flange plate to the outer periphery of the sleeve by any one of welding, press-fitting, adhesion, and caulking.

  In the present invention, the lubricant scattering suppression member may include a blocking portion (53, 55) that closes the tooth groove (26e) of the idle gear at both ends (26f) in the tooth width direction (S2). In this case, the blocking portion can suppress the scattering of the lubricant from the meshing portion of the idle gear to the side of the idle gear. In addition, since the lubricant scattering suppression member is provided in the idle gear, it is possible to suppress the lubricant scattering in all the meshing portions of the idle gear and the plurality of other gears, and the structure for this can be simplified.

When the said obstruction | occlusion part (53) is integrally formed with the tooth | gear part and the single material (44), a number of parts can be reduced.
In the case where the closing portion (55) is made of a synthetic resin attached to both ends of the tooth gap, the manufacturing method of the closing portion is not easily restricted, so that the degree of freedom in designing the idle gear is increased.
In addition, although the alphanumeric characters in the parentheses indicate reference signs of corresponding components in the embodiments described later, the scope of the claims is not limited by these reference signs.

  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 that is provided between the steering shaft 4 and the steering mechanism 5 and transmits a rotation therebetween. 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. The steering wheel 3 is connected to one end of the steering shaft 4, and the 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 the left-right 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 intermediate shaft 6. In the steering mechanism 5, the rotation of the pinion shaft 13 is converted into linear movement of the rack bar 14 along the left-right 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.

  The rack housing 15 of the steering mechanism 5 has a first housing 20 and a second housing 21 and is attached to the vehicle body 9. The first housing 20 surrounds a part of the rack bar 14, supports the pinion shaft 13, and accommodates and supports the torque sensor 16. The second housing 21 is connected to the first housing 20, surrounds a part of the rack bar 14, supports the electric motor 18, and constitutes a part of the speed reducer 19.

  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 has a motor housing 18a and a rotating shaft 18b as an output shaft that is rotatably supported by the motor housing 18a via a bearing. The rotating shaft 18b of the electric motor 18 is disposed in parallel with the direction in which the rack bar 14 extends.
The speed reducer 19 is a parallel shaft gear mechanism 19 a for decelerating the output rotation of the steering assisting electric motor 18, and a motion conversion mechanism that converts the output rotation of the parallel shaft gear mechanism 19 a into linear movement of the rack bar 14. And a ball screw mechanism 19b. The parallel shaft gear mechanism 19 a and the ball screw mechanism 19 b are accommodated in the second housing 21. The second housing 21 is filled with grease G as a lubricant.

The parallel shaft gear mechanism 19 a has a drive gear 25 driven by the electric motor 18, an idle gear 26 as an intermediate gear driven by the drive gear 25, and a driven gear 27 driven by the idle gear 26. is doing.
The ball screw mechanism 19 b has a nut 28 driven by the driven gear 27 and a screw shaft 30 driven by the nut 28 via a plurality of balls 29. The ball screw mechanism 19 b 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 and the driven gear 27 are fixed to each other so that they can rotate together. The screw shaft 30 has a male screw. The screw shaft 30 and the rack bar 14 are fixed to each other so as to move together. A 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.

  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 the movement of the steering wheel 3 is also transmitted to the rack bar 14 along with this. As a result, the steering wheel 2 is steered and the steering is assisted.

  FIG. 2 is a cross-sectional view of a main part of the steering mechanism shown in FIG. Referring to FIG. 2, the electric power steering apparatus 1 is a first support shaft that supports the drive gear 25, and includes a drive gear support shaft 31 as an input shaft, and a plurality of support devices that rotatably support the drive gear 25. Bearings 32, 33, a fixing member 34 and a lock nut 35 for restricting axial movement of the bearings 32, 33, a shaft coupling 36 for connecting the drive gear support shaft 31 to the rotating shaft 18 b of the electric motor 18, have.

  The drive gear 25 is a bevel gear, and is formed in a substantially cylindrical shape from metal, for example, steel. A plurality of inclined teeth are formed on the outer periphery of the drive gear 25. The drive gear 25 is fixed to one end of the drive gear support shaft 31 so as to be integrally rotatable. Specifically, the drive gear 25 and the drive gear support shaft 31 are integrally formed as a single component by a single member. The drive gear support shaft 31 is rotatably supported by the second housing 21 via bearings 32 and 33, and the axial movement with respect to the second housing 21 is restricted.

  FIG. 3 is an enlarged view of a main part of FIG. 2, mainly showing the idle gear 26. 2 and 3, the electric power steering apparatus 1 includes an intermediate shaft 37 as a second support shaft that supports the idle gear 26, an end plate 38 provided on the intermediate shaft 37, and an intermediate shaft 37. A pair of rolling bearings 39 that are rotatably supported by the idle gear 26, and a fixing member 40 and a lock nut 41 for restricting the axial movement of the bearing 39 with respect to the intermediate shaft 37. And a fastening member 42 for fixing the intermediate shaft 37 to the second housing 21.

  The intermediate shaft 37 and the end plate 38 are integrally formed, constitute a single part as a support shaft, are supported by the second housing 21, and are fixed to the second housing 21 by a fastening member 42. Has been. The fastening member 42 has a female screw 42b. The female screw 42 b is screwed to the male screw 37 c at the end of the intermediate shaft 37. When the fastening member 42 is screwed onto the intermediate shaft 37, the end plate 38 and the fastening member 42 fasten the second housing 21 therebetween. Thereby, the intermediate shaft 37 is fixed to the second housing 21.

  An outer peripheral surface 37 d of the intermediate shaft 37 supports the idle gear 26 via a bearing 39 so as to be rotatable. Inner rings 39 b of two bearings 39 are fitted on the outer peripheral surface 37 d of the intermediate shaft 37. Further, the fixing member 40 and the lock nut 41 are screwed to the male screw 37a on the outer peripheral surface 37d. An inner ring 39 b of the two bearings 39 is sandwiched between the step portion 37 b of the intermediate shaft 37 and the fixing member 40. Thereby, the movement of the bearing 39 with respect to the intermediate shaft 37 in the axial direction is restricted.

Each bearing 39 has a single outer ring 39a, a single 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 idle gear 26 includes a sleeve 43 as a metal core bar having a cylindrical shape, and a synthetic resin member 44 that surrounds the sleeve 43 and is formed in an annular shape. The idle gear 26 has a tooth portion 26d.

  The sleeve 43 is rotatably supported on the outer peripheral surface 37 d of the intermediate shaft 37 via a bearing 39. That is, the inner peripheral surface of the sleeve 43 has a small diameter portion 43a and a large diameter portion 43b. The small diameter portion 43a and the large diameter portion 43b are connected via an annular end wall 43c. The large diameter portion 43b has a cylindrical shape and holds the outer periphery of the outer ring 39a of the bearing 39 in a fitted state. A circumferential groove extending in the circumferential direction of the sleeve 43 is formed at the end of the large-diameter portion 43b that is one end of the inner circumferential surface of the sleeve 43 in the axial direction S2. A retaining ring 45 is fitted in the circumferential groove. The outer rings 39a of the two bearings 39 are sandwiched between the end wall 43c and the retaining ring 45 in the axial direction S2 (corresponding to the direction in which the intermediate shaft 37 extends), and both sides in the axial direction S2 with respect to the sleeve 43. The movement to is regulated.

The outer periphery 43e of the sleeve 43 is a restricting portion that restricts relative movement between the sleeve 43 and the synthetic resin member 44, and has a convex portion 43d as a undulating portion.
The synthetic resin member 44 is formed in a cylindrical shape. The synthetic resin member 44 is shorter than the sleeve 43 in the axial direction S2. The inner peripheral surface of the synthetic resin member 44 is fixed so as to rotate integrally with the outer periphery 43 e of the sleeve 43. For example, the synthetic resin member 44 is formed by insert molding the sleeve 43. The sleeve 43 is inserted into the mold as a core metal when the synthetic resin member 44 is molded, and functions as a part of the resin mold. The synthetic resin member 44 has an outer periphery 44a as an annular portion having a predetermined thickness from the outer peripheral surface. The tooth part 26d is formed in the whole area of the outer periphery 44a regarding the axial direction S2.

The tooth portion 26d has a plurality of inclined teeth as gear teeth. A tooth groove 26e is formed between the gear teeth adjacent to each other. Each tooth groove 26e is open on both sides in the tooth width direction (corresponding to the axial direction S2).
Referring to FIG. 2, the electric power steering apparatus 1 is a third support shaft that supports the driven gear 27 and a driven gear support shaft 47 as an output shaft, and a plurality of support gears 27 that rotatably support the driven gear 27. Bearings 48 and 49 and two fixing members 50 and 51 for restricting axial movement of the bearings 48 and 49 are provided.

  The second housing 21 holds two bearings 48 and 49. The two bearings 48 and 49 support the driven gear support shaft 47 so as to be rotatable. The female screw of the fixing member 50 is screwed into the male screw of the driven gear support shaft 47, thereby restricting the axial movement of the bearing 49 with respect to the driven gear support shaft 47. Further, the fixing member 51 is screwed into the second housing 21, thereby restricting the axial movement of the bearing 49 with respect to the second housing 21. The driven gear support shaft 47 is connected to the driven gear 27 so as to rotate integrally therewith, and supports the driven gear 27. The driven gear support shaft 47 is connected to the nut 28 so as to rotate integrally therewith, and is formed integrally with the nut 28 in this embodiment.

The driven gear 27 is formed in an annular shape from metal, for example, steel. A plurality of inclined teeth as gear teeth are formed on the outer periphery of the cylindrical shape of the driven gear 27.
The rack bar 14, the screw shaft 30, the nut 28, the driven gear support shaft 47, the driven gear 27, and the pair of bearings 48 and 49 are arranged concentrically with each other and supported by the second housing 21.

  In the parallel shaft gear mechanism 19a of the present embodiment, the center axis 25a of the drive gear 25 and the center axis 26a of the idle gear 26 are arranged in parallel to each other. Further, the center axis 26a of the idle gear 26 and the center axis 27a of the driven gear 27 are arranged in parallel to each other. A predetermined distance is separated between the rotating shaft 18 b of the electric motor 18 and the rack bar 14. While the predetermined distance is set to a minimum value corresponding to the outer shape of the electric motor 18, a required reduction ratio can be realized while suppressing an increase in the size of the driven gear 27. Thereby, the external shape of the steering mechanism 5 can be reduced in size.

  In the present embodiment, the idle gear 26 includes a meshing portion 26 b that meshes with the meshing portion of the drive gear 25, and a meshing portion 26 c that meshes with the meshing portion of the driven gear 27. Further, the entire periphery of the idle gear 26 is filled with the grease G in the second housing 21. The grease G only needs to be filled in at least one of at least the meshing portions 26b and 26c of the idle gear 26 in the second housing 21, and more preferably, the meshing portions 26b and 26c are filled. It is good to be. The lubricant may be a lubricating oil in addition to the grease G.

  FIG. 4 is an exploded perspective view of the idle gear 26 shown in FIG. 2, and only a part of the gear teeth are shown. Referring to FIGS. 3 and 4, the electric power steering apparatus 1 of the present embodiment has a pair of annular flange plates 52 as opposed plates facing each other from the side of the meshing portions 26 b and 26 c of the idle gear 26. Yes. Each annular flange plate 52 functions as a lubricant scattering suppressing member that suppresses the scattering of the lubricant from the meshing portions 26 b and 26 c of the idle gear 26 to the side of the idle gear 26.

  The pair of annular flange plates 52 are disposed on both sides of the idle gear 26 with respect to the axial direction S2. The pair of annular flange plates 52 are made of a metal circular plate and are formed in the same shape. One plate surface of the pair of annular flange plates 52 is close to and opposed to the pair of side surfaces 44b of the synthetic resin member 44, and is in contact with the corresponding side surface 44b without a gap. Each annular flange plate 52 is provided so as to rotate integrally with the idle gear 26, and the inner periphery of the annular flange plate 52 is fixed to the outer periphery 43 e of the sleeve 43 in a fitted state. Various specific fixing modes regarding the annular flange plate 52 are considered as follows, and at least one of these fixing modes can be adopted.

FIG. 5 is an enlarged view of a main part of FIG. 6, FIG. 7 and FIG. 8 show first, second and third modifications of the fixing mode of the annular flange plate of the first embodiment, respectively, and correspond to the parts shown in FIG. FIG.
3 and 5, the inner periphery of the annular flange plate 52 is fixed to the outer periphery 43e of the sleeve 43 by caulking in a fitted state. That is, at least one of the inner periphery of the annular flange plate 52 and the outer periphery 43e of the sleeve 43 is plastically deformed, for example, to obtain plastic deformed portions 43f and 52f as caulked portions, and these plastically deformed portions 43f and 52f are obtained. Are engaged with each other to restrict the relative movement of both 43 and 52.

  3 and 6, the inner periphery of the annular flange plate 52 may be fixed to the outer periphery 43e of the sleeve 43 in a press-fit state. That is, the inner circumference of the annular flange plate 52 in an unconstrained state is formed to have a smaller diameter than the fitting portion of the outer periphery 43e of the sleeve 43, and is press-fitted into the fitting portion of the outer periphery 43e. The press-fitting portions 43g and 52g that are press-fitted are engaged with each other so that the relative movement of the both 43 and 52 is restricted.

With reference to FIGS. 3 and 7, the inner periphery of the annular flange plate 52 may be fixed to the outer periphery 43 e of the sleeve 43 by welding. That is, in a state where the inner periphery of the annular flange plate 52 is fitted to the outer periphery 43e of the sleeve 43, the both 43 and 52 are welded together. The relative movement of both 43 and 52 is regulated via a welded portion 52h that is welded.
3 and 8, the annular flange plate 52 and the synthetic resin member 44 may be fixed to each other by screwing. The inner periphery of the annular flange plate 52 is fitted to the outer periphery 43 e of the sleeve 43. The shaft portion of the fixing bolt 52j passes through the insertion holes 52i and 44i between the pair of annular flange plates 52 and the synthetic resin member 44, and the nut 52k is screwed to the thread portion at the tip of the shaft portion that has passed through. . A pair of annular flange plates 52 and the synthetic resin member 44 are clamped between the nut 52k and the head of the fixing bolt 52j. In this case, the inner periphery of the annular flange plate 52 and the outer periphery of the sleeve 43 may not be fitted. Alternatively, although not shown, the annular flange plate 52 and the synthetic resin member 44 may be bonded.

  FIG. 9 is a schematic diagram showing the relationship among the annular flange plate 52, the idle gear 26, and the drive gear 25. 3 and 9, the outer peripheral radius L0 of the annular flange plate 52 is formed larger than the radius R1 of the tip circle of the outer periphery 44a of the synthetic resin member 44 (L0> R1), and It is set to be equal to or greater than the minimum distance R2 (L0 ≧ R2) between the root circle of the drive gear 25 as the counterpart gear and the central axis 26a of the idle gear 26. In this case, both the gap G1 between the tooth tip of the drive gear 25 and the tooth bottom of the idle gear 26 and the gap G2 between the tooth bottom of the drive gear 25 and the tooth tip of the idle gear 26 are on the side. Can be reliably faced and covered.

  The radius L0 of the outer periphery of the annular flange plate 52 is an arbitrary value less than the above-described distance R2, and may be a value larger than the radius R3 of the root circle of the idle gear 26 (L0> R3). . Further, the radius L0 of the outer periphery of the annular flange plate 52 is preferably not less than the radius R1 of the tooth tip circle of the idle gear 26 (L0 ≧ R1). In this case, the escape of the grease G from the tooth groove 26e of the idle gear 26 to the side can be reliably suppressed.

  2 and 3, the drive gear 25 is prevented from protruding from the tooth portion 26d of the idle gear 26 in the axial direction S2. The tooth width of the drive gear 25 is shorter than the tooth width of the idle gear 26. The center positions of the drive gear 25 and the idle gear 26 with respect to the axial direction S2 are made to coincide with each other. The driven gear 27 is configured similarly to the drive gear 25 with respect to the idle gear 26.

  The electric power steering apparatus 1 according to the present embodiment includes (1) an idle gear 26 in which the tooth portion 26d is formed of a synthetic resin (corresponding to the synthetic resin member 44 in the present embodiment), and the steering assist electric motor 18. A parallel shaft gear mechanism 19a that decelerates the output rotation of the parallel shaft gear mechanism; (2) a rack housing 15 as a housing that accommodates the parallel shaft gear mechanism 19a; and (3) a meshing portion 26b of at least the idle gear 26 in the rack housing 15. , 26c and grease G as a lubricant, and (4) the grease G is prevented from scattering from the meshing portions 26b, 26c of the idle gear 26 to the side of the idle gear 26 (corresponding to the axial direction S2). And a lubricant scattering suppression member (in this embodiment, the annular flange plate 52 is equivalent).

  In the present embodiment, the following effects by the lubricant scattering suppression member can be obtained. That is, when the gears of the parallel shaft gear mechanism 19a mesh with each other, the lubricant is held by the meshing portions 26b and 26c of the idle gear 26, so that it is possible to suppress the occurrence of wear due to the lack of lubricant over a long period of time. As a result, the generation of abnormal noise can be suppressed. In other words, it is possible to reduce the amount of lubricant used for suppressing the occurrence of wear. In addition, there is no possibility that the accuracy of the tooth profile is reduced due to the formation of the groove for retaining the lubricant on the tooth surface.

  In the present embodiment, the lubricant scattering suppression member includes an annular flange plate 52 that is provided so as to rotate integrally with the idle gear 26 and is opposed to the side of the meshing portions 26b and 26c of the idle gear 26. It is out. Thereby, scattering of the lubricant from the meshing portions 26b, 26c of the idle gear 26 to the side of the idle gear 26 can be suppressed. Further, since the lubricant scattering suppression member is provided in the idle gear 26, the scattering of the lubricant in all the meshing portions 26b, 26c of the idle gear 26 and the plurality of other gears 25, 27 can be suppressed. Can be simplified.

  In the present embodiment, the idle gear 26 includes a metal sleeve 43 that is rotatably supported via a rolling bearing 39 on an outer peripheral surface 37d of an intermediate shaft 37 as a support shaft supported by the rack housing 15. An annular synthetic resin member 44 fitted to the outer periphery 43e of the sleeve 43 so as to be integrally rotatable is included. The opposing plate is attached to the outer periphery 43e of the sleeve 43 by welding, press-fitting, bonding, or caulking, and includes an annular flange plate 52 made of metal that faces the pair of side surfaces 44b of the synthetic resin member 44 in close proximity to each other. Yes. In this case, the annular flange plate 52 can suppress the scattering of the lubricant from the meshing portions 26 b and 26 c of the idle gear 26 to the side of the idle gear 26. Further, by attaching the annular flange plate 52 to the outer periphery 43e of the sleeve 43 by any one of welding, press-fitting, adhesion, and caulking, it is possible to easily realize the lubricant scattering suppression member.

Moreover, the following modifications can be considered about this embodiment. In the following description, differences from the base embodiment will be mainly described, and the same components are denoted by the same reference numerals and description thereof will be omitted.
For example, FIG. 10 is an enlarged sectional view of a main part of the steering mechanism 5 of the electric power steering apparatus 1 according to the second embodiment of the present invention, and mainly shows the idle gear 26. The present embodiment differs from the first embodiment in the following points. That is, the annular flange plate 52 and the entire side surface 44b of the synthetic resin member 44 of the idle gear 26 are opposed to each other with a predetermined amount of gap 56 therebetween. The gap 56 functions as an annular lubricant reservoir recess for storing the lubricant.

  The outer periphery 43e of the sleeve 43 has a stepped portion 43m for positioning the annular flange plate 52 in the axial direction S2. Further, the tooth width of the drive gear 25 is wider than the tooth width of the idle gear 26 and shorter than the distance between the pair of annular flange plates 52. The tooth width of the driven gear 27 is wider than the tooth width of the idle gear 26 and shorter than the distance between the pair of annular flange plates 52. The annular flange plate 52 is directly fixed to the sleeve 43 by any one of welding, press fitting, adhesion, and caulking.

In the present embodiment, the effects of the first embodiment can be obtained similarly. In addition to this, since the lubricant can be stored in the gap 56 as the lubricant storage recess, the lubricating action can be maintained for a longer period of time.
The radially inner portion of the synthetic resin member 44 may be formed wider than the radially outer portion with respect to the axial direction S2, and the radially inner portion and the annular flange plate 52 may be brought into contact with each other. In this case, the gap 56 described above can be formed between the radially outer portion of the synthetic resin member 44 and the annular flange plate 52. Further, the annular flange plate 52 is fixed to the synthetic resin member 44 or the sleeve 43 by the above-described fixing manner.

FIG. 11 is an enlarged cross-sectional view of the idle gear 26 as the main part of the steering mechanism 5 according to the third embodiment of the present invention. FIG. 12 is an exploded perspective view of the idle gear 26 of FIG. 11, and shows only some gear teeth. FIG. 13 is a schematic view of a manufacturing method of the idle gear 26 of FIG.
11 and 12, the idle gear 26 of the present embodiment has a sleeve 43 and a synthetic resin member 44A. The synthetic resin member 44A is different from the synthetic resin member 44 in the following points. The annular flange plate 52 is abolished.

The outer periphery 44a of the synthetic resin member 44A includes a tooth portion 26d as an intermediate portion in the axial direction S2, and two closed portions 53 that are annular portions at both end portions in the axial direction S2 and close the tooth groove 26e of the tooth portion 26d. have.
The closing portion 53 is provided at both end portions 26f of the tooth groove 26e in the tooth width direction (corresponding to the axial direction S2), and closes the entire tooth groove 26e at both ends 26f in the tooth width direction. Each closing portion 53 functions as a lubricant scattering suppressing member that suppresses the scattering of the lubricant from the meshing portions 26 b and 26 c of the idle gear 26 to the side of the idle gear 26.

  The closing part 53 is integrally formed with the tooth part 26d with a single material. The blocking portion 53 is formed as a portion left without being cut when the tooth portion 26d is formed by cutting, for example, cutting, in the synthetic resin member 44A. The closing part 53 has a first part 53a as an incomplete tooth part in which a plurality of grooves are formed, and a second part 53b as an unprocessed part in which no groove is formed. The 2nd part 53b is provided in the both ends of the outer periphery 44a regarding the axial direction S2. The first portion 53a is provided between the second portion 53b and the tooth portion 26d with respect to the axial direction S2.

  Referring to FIGS. 11 and 13, the first portion 53 a has a plurality of partial cylindrical surfaces and a plurality of grooves formed between the adjacent partial cylindrical surfaces. The outer diameter of the partial cylindrical surface is made equal to the tip circle diameter of the tooth portion 26d. The groove of the first portion 53a communicates with the tooth groove 26e of the tooth portion 26d, and gradually becomes shallower from the tooth portion 26d toward the second portion 53b. The groove of the first portion 53a is a tooth portion with respect to the axial direction S2 when the gear tooth of the tooth portion 26d is cut by a hob H as a gear cutting tool on a workpiece W (workpiece) as a single material. It is formed as a part of the incomplete tooth part produced on both sides of 26d. This incomplete tooth portion moves the hob H closer to or away from the workpiece W in the radial direction of the workpiece W before and after the hob H is moved parallel to the axial direction S2 of the workpiece W to form the tooth portion. Sometimes formed. Further, the outer diameter of the hob H is set according to the length of the closing portion 53 in the axial direction S2.

The second portion 53b has a circular shape when viewed from the axial direction S2, and the outer diameter thereof is equal to the diameter of the tip circle of the tooth portion 26d.
In the present embodiment, the occurrence of wear and abnormal noise can be suppressed over a long period of time by the lubricant scattering suppression member as in the first embodiment.
Moreover, in this embodiment, the lubricant scattering suppressing member includes a closing portion 53 that closes the tooth groove 26e of the idle gear 26 at both ends in the tooth width direction. In this case, the blocking portion 53 can suppress the scattering of the lubricant from the meshing portions 26 b and 26 c of the idle gear 26 to the side of the idle gear 26. In addition, since the lubricant scattering suppression member is provided in the idle gear 26, it is possible to suppress the lubricant scattering in all the meshing portions 26b, 26c of the idle gear 26 and a plurality of other gears. It can be simplified.

Moreover, in this embodiment, the obstruction | occlusion part 53 is integrally formed with the tooth | gear part 26d with the single material. In this case, the number of parts can be reduced.
FIG. 14 is an enlarged cross-sectional view of the main part of the steering mechanism of the electric power steering apparatus 1 according to the fourth embodiment of the present invention, mainly showing the idle gear 26. FIG. 15 is an exploded perspective view of the idle gear 26 and shows only a part of the gear teeth.

Referring to FIGS. 14 and 15, the present embodiment is different from the third embodiment in the following points. The idle gear 26 of the present embodiment includes a sleeve 43 and a synthetic resin member 44B. The synthetic resin member 44B has a gear main body 54 as a main portion, and a plurality of closing portions 55 fixed to both ends of the plurality of tooth grooves 54e of the gear main body 54.
The gear main body 54 has the same shape as the synthetic resin member 44 of the first embodiment, and is formed of synthetic resin. The gear main body 54 has a plurality of tooth grooves 54e. These tooth grooves 54e are open on both sides with respect to the axial direction S2. An intermediate portion of the gear body 54 as an intermediate portion of the synthetic resin member 44B with respect to the axial direction S2 is formed as a tooth portion 26d. Both end portions of the gear main body 54 in the axial direction S2 support the plurality of closing portions 55.

  The closing portion 55 is provided at both end portions 26f of the entire tooth groove 26e in the tooth width direction, and closes the tooth groove 26e of the idle gear 26 at both ends 26f in the tooth width direction. Each closing portion 55 functions as a lubricant scattering suppressing member that suppresses the scattering of the lubricant from the meshing portions 26 b and 26 c of the idle gear 26 to the side of the idle gear 26. The blocking part 55 is made of a synthetic resin member attached to both ends of the tooth gap 26e. The blocking portion 55 overlaps the tooth gap 54e when viewed along the axial direction S2. The blocking portion 55 attached to the tooth groove 26e forms the outer peripheral surface 44a, and the diameter thereof is equal to the outer diameter of the tip circle of the tooth portion 26d. The blocking part 55 forms a wall surface facing the tooth gap 26e and perpendicular to the tooth width direction.

The gear body 54 and the closing portion 55 are formed separately from each other. By attaching the closing portion 55 to the gear body 54, the gear body 54 and the closing portion 55 are integrated with each other to constitute a synthetic resin member 44B as a composite molded product.
Various modes of attaching the closing portion 55 to the gear main body 54 are considered as follows. For example, the gear body 54 and the plurality of closing portions 55 are formed separately, and the closing portions 55 are fixed to the tooth grooves 54 e of the gear body 54 in a press-fitted state. Alternatively, the gear body 54 and the plurality of closing portions 55 are formed separately, and the closing portions 55 are fixed to the tooth grooves 54e of the gear body 54 with an adhesive. Alternatively, a multiple molding method (also referred to as a double molding method or a two-time molding method) may be used. That is, the gear main body 54 as a primary molded body is molded with the first mold, and the molded gear main body 54 is attached to the second mold as an outsert. The closed portion 55 as a secondary molded body is directly molded on the surface. In this case, it is possible to simultaneously form the closing portion 55 and fix the closing portion 55 to the gear body 54.

In the present embodiment, similarly to the first embodiment, the occurrence of wear and abnormal noise can be suppressed over a long period of time by the lubricant scattering suppression member.
Further, in the present embodiment, the lubricant scattering suppression member includes a closing portion 55 that closes the tooth groove 26e of the idle gear 26 at both ends 26f in the tooth width direction. In this case, the blocking portion 55 can suppress the scattering of the lubricant from the meshing portions 26 b and 26 c of the idle gear 26 to the side of the idle gear 26. Further, since the lubricant scattering suppression member is provided in the idle gear 26, the lubricant scattering can be suppressed in all the meshing portions 26b, 26c of the idle gear 26 and a plurality of other gears, and the structure for this can be simplified. it can.

Moreover, in this embodiment, the obstruction | occlusion part 55 consists of a synthetic resin member attached to the both ends 26f of the tooth space 26e. In this case, since the closing portion 55 is not easily restricted by the molding method, the degree of freedom in designing the idle gear 26 can be increased. The attachment here includes attaching the molded blocking part 55 and attaching the blocking part 55 simultaneously with molding.
Further, when the annular flange plate 52 is formed of a member other than metal, for example, a synthetic resin, when a non-circular counter plate is provided, when the entire idle gear 26 is made of resin, When at least a part is formed integrally with each other, a case where the gear body 54 and the plurality of closing portions 55 are formed integrally may be considered.

  Further, when viewed from the axial direction S2, the annular flange plate 52 may cover at least a part of the tooth groove 26e at the meshing portions 26b and 26c. The annular flange plate 52 only needs to be provided at least in part. For example, the annular flange plate 52 may be provided in at least one end 26f of the tooth groove 26e with respect to the axial direction S2. It may be provided only in the groove 26e, may be provided so as to rotate integrally with the drive gear 25 instead of the idle gear 26, or may be provided so as to rotate integrally with the driven gear 27. The same applies to the blocking portions 53 and 55.

  Further, the drive gear 25, the idle gear 26, and the driven gear 27 may be spur gears. In addition, various design changes can be made within the scope of matters described in the claims.

It is a mimetic diagram of the electric power steering device of a 1st embodiment of the present invention. It is sectional drawing of the principal part of the steering mechanism shown in FIG. FIG. 3 is an enlarged view of a main part of FIG. 2. FIG. 3 is an exploded perspective view of the idle gear shown in FIG. 2. FIG. 5 is an enlarged view of a main part of FIG. FIG. 6 is an enlarged view of a portion corresponding to the portion illustrated in FIG. 5, showing a first modification of the fixing mode of the annular flange plate. FIG. 6 is an enlarged view of a portion corresponding to the portion illustrated in FIG. 5, showing a second modification of the fixing mode of the annular flange plate. FIG. 6 is an enlarged view of a portion corresponding to the portion illustrated in FIG. 5, showing a third modification of the fixing mode of the annular flange plate. It is a schematic diagram which shows the relationship between the annular flange board shown in FIG. 2, an idle gear, and a drive gear. It is an expanded sectional view of the principal part of the steering mechanism of the electric power steering device of the 2nd Embodiment of this invention, and mainly shows an idle gear. It is an expanded sectional view of the principal part of the steering mechanism of the electric power steering device of the 3rd Embodiment of this invention, and mainly shows an idle gear. It is a disassembled perspective view of the idle gear shown in FIG. It is a schematic diagram which shows the manufacturing method of the idle gear shown in FIG. It is an expanded sectional view of the principal part of the steering mechanism of the electric power steering device of the 4th Embodiment of this invention, and mainly shows an idle gear. It is a disassembled perspective view of the idle gear shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Electric power steering apparatus, 15 ... Rack housing (housing), 18 ... Electric motor, 19a ... Parallel shaft gear mechanism, 26 ... Idle gear, 26b, 26c ... Meshing part, 26d ... Tooth part, 26e ... Tooth groove, 26f ... both ends of (tooth groove), 37 ... intermediate shaft (support shaft), 37d ... outer peripheral surface (outer periphery of support shaft), 39 ... bearing (rolling bearing), 43 ... sleeve, 43e ... outer periphery of (sleeve), 44 ... Synthetic resin member (synthetic resin), 44b (side surface of synthetic resin member), 52 ... annular flange plate (opposite plate, lubricant scattering suppression member), 53 ... occlusion portion (integrally formed with tooth portion and single material) Occluded part, lubricant scattering suppression member), 55 ... occlusion part (synthetic resin and lubricant scattering suppression member attached to both ends of the tooth gap), G ... grease (lubricant), S2 axial direction (idle gear) Side, tooth width direction

Claims (6)

A parallel shaft gear mechanism that includes an idle gear whose tooth portion is formed of a synthetic resin and decelerates the output rotation of the steering assist electric motor;
A housing that houses the parallel shaft gear mechanism;
A lubricant filled in at least the meshing portion of the idle gear in the housing;
An electric power steering apparatus comprising: a lubricant scattering suppression member that suppresses scattering of the lubricant from the meshing portion of the idle gear to the side of the idle gear.   2. The electric power steering apparatus according to claim 1, wherein the lubricant scattering suppression member includes an opposing plate that is provided so as to rotate integrally with the idle gear and that faces the side of the meshing portion of the idle gear. In claim 2,
The idle gear includes a metal sleeve rotatably supported on the outer periphery of a support shaft supported by a housing via a rolling bearing, and an annular synthetic resin member fitted to the outer periphery of the sleeve so as to be integrally rotatable. Including
The above-mentioned opposing plate is attached to the outer periphery of the sleeve by welding, press-fitting, adhesion, or caulking, and includes a metal annular flange plate that is opposed to each other in close proximity to a pair of side surfaces of the synthetic resin member. apparatus.   2. The electric power steering apparatus according to claim 1, wherein the lubricant scattering suppressing member includes a closing portion that closes the tooth gap of the idle gear at both ends in the tooth width direction.   5. The electric power steering apparatus according to claim 4, wherein the closing portion is formed integrally with the tooth portion from a single material.   5. The electric power steering apparatus according to claim 4, wherein the closing portion is made of a synthetic resin attached to both ends of the tooth gap.

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