JP2017206122A - Electric power steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric power steering device that can suppress invasion of moisture into a decelerating mechanism from a torque sensor side.SOLUTION: A torque sensor 4 is housed in a housing part 25 of a column jacket 3 housing a steering shaft 2. A decelerating mechanism 5 having a worm wheel 40 connected to a part 2C closer to a front side X2 than the torque sensor 4 in the steering shaft 2 is housed in a gear housing 7. In a housing spacer 8, an outer tube part 60 is pressed into an opening part 7B of the gear housing 7 and an inner tube part 61 is pressed into an inner peripheral surface 25B of a front end part 25D of the housing part 25. In a first bearing 9 with a seal arranged between the worm wheel 40 and the torque sensor 4, an inner wheel 65 is pressed into the steering shaft 2 and an outer wheel 66 is internally fitted to the inner tube part 61. A sensor spacer 11 blocks a gap 90 between the outer wheel 66 and the inner tube part 61 from a front side X1.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an electric power steering apparatus.

  An electric power steering device disclosed in Patent Document 1 includes a steering shaft coupled to a steering member such as a steering wheel, a reduction mechanism that decelerates the output rotation of an electric motor for steering assistance and transmits the steering rotation to the steering shaft, and a steering A torque sensor that is externally fitted to the shaft to detect steering torque and a steering column that rotatably supports the steering shaft are included. The speed reduction mechanism includes a worm that is rotationally driven by an electric motor, and a worm wheel that is coupled to the steering shaft and meshes with the worm. The steering column includes a column tube that houses a part of the steering shaft, and a gear housing that houses a speed reduction mechanism.

  The lower part of the column tube constitutes a sensor housing that houses the torque sensor, and is connected to the gear housing. The sensor housing is formed with an insertion hole for drawing the wiring of the torque sensor to the outside. The gear housing includes a lower housing that accommodates the worm and the worm wheel, and an upper housing disposed between the worm wheel and the torque sensor. The upper housing includes an outer cylinder, an inner cylinder, and a connecting wall that connects the outer cylinder and the inner cylinder. The outer cylinder is press-fitted into the inner periphery of the upper part of the lower housing, and the inner cylinder is press-fitted into the inner periphery of the lower part of the sensor housing.

  An upper bearing constituted by a rolling bearing is fitted on a portion of the steering shaft between the worm wheel and the torque sensor. In the upper bearing, the inner ring is fitted to the steering shaft by a tightening spring, and the outer ring is held by the inner cylinder. Further, a spacer constituted by an elastic member or the like is interposed between the inner cylinder and the torque sensor, and elastically biases the torque sensor toward the positioning portion of the sensor housing. Thereby, the torque sensor is positioned in the axial direction of the sensor housing.

International Publication No. 2010/013490

  When the electric power steering device disclosed in Patent Document 1 is placed in a high humidity environment, external moisture enters the sensor housing from, for example, an insertion hole of the sensor housing, and the outer ring and the inner ring of the upper bearing It is assumed that the gear housing enters the gap housing through the gap or the gap between the outer ring and the inner cylinder of the upper housing. When the worm wheel in the gear housing is made of resin, the expansion of the worm wheel due to moisture absorption progresses, and the meshing between the worm wheel and the worm becomes tight, which may increase the steering of the steering member.

  The present invention has been made under such a background, and an object of the present invention is to provide an electric power steering apparatus that can suppress moisture from entering the speed reduction mechanism from the torque sensor side.

  The invention according to claim 1 includes a steering shaft (2) in which a steering member (12) is connected to an end (2A) on one side (X1) in the axial direction (X), and the other side in the axial direction ( A cylindrical housing part (25) is formed at the end (3B) of X2), a column jacket (3) housing the steering shaft, and a torque that is housed in the housing part and detects the steering torque of the steering member A sensor (4), a worm wheel (41) connected to the other side (2C) of the steering shaft on the other side of the torque sensor, and an electric motor (6) meshing with the worm wheel ) And a reduction mechanism (5) having a worm (41) driven to rotate, an accommodation space (7A) accommodating the reduction mechanism, and a front communicating with the accommodation space. An opening (7B) that opens toward the torque sensor is formed, and a gear housing (7) in which the steering shaft is inserted into the housing space and the opening, and an outer cylinder portion that is press-fitted into the opening ( 60), an inner cylinder part (61) surrounded by the outer cylinder part and press-fitted into an inner peripheral surface (25B) of the other end part (25D) of the housing part, the outer cylinder part and the A housing spacer (8) having a connecting portion (62) connecting between the inner cylinder portions, and an inner ring (pressed into the steering shaft) disposed between the worm wheel and the torque sensor in the axial direction. 65) and a bearing (9) with a seal having an outer ring (66) fitted inside the inner cylinder portion, and the torque sensor and the inner cylinder portion sandwiched from both sides in the axial direction. The outer ring to contain the other hand a plugged from the side sensor spacer (11) a gap (90) between the inner cylinder part, an electric power steering device (1).

  According to a second aspect of the present invention, in the electric power steering apparatus according to the first aspect, the sensor spacer includes a rubber contact portion (85) that is in close contact with the outer ring and the inner cylinder portion from the one side. is there.

  The invention according to claim 3 is the electric power steering apparatus according to claim 2, wherein the sensor spacer includes a metal skeleton (83).

  According to a fourth aspect of the present invention, the sensor spacer includes an annular main body (80) surrounding the steering shaft, and an annular first protrusion projecting from the other end of the main body toward the steering shaft. 1 overhang portion (81) and an annular second overhang portion (82) projecting from the one end portion of the main body portion to the opposite side of the steering shaft side, An annular first contact portion (85A) that is provided on the other end surface (81A) of the first overhang portion and is in close contact with the outer ring, and the other end surface (82A) of the second overhang portion. It is an electric power steering device of Claim 3 including the cyclic | annular 2nd close_contact | adherence part (85B) provided in this and closely_contact | adhered to the said inner cylinder part.

  The numbers in parentheses above represent reference numerals of corresponding components in the embodiments described later, but the scope of the claims is not limited by these reference numerals.

According to the first aspect of the present invention, in the electric power steering apparatus, the torque sensor is accommodated in the accommodating portion formed at the other end portion in the axial direction of the column jacket. And the worm wheel of the speed reduction mechanism accommodated in the accommodation space of the gear housing is connected to the other side of the torque sensor on the steering shaft.
In this configuration, the outer cylindrical portion of the housing spacer is press-fitted into an opening portion that opens toward the torque sensor in the gear housing, and the inner cylindrical portion of the housing spacer is press-fitted into the inner peripheral surface of the other end of the housing portion. Has been. Further, the bearing disposed between the worm wheel and the torque sensor is a bearing with a seal, and an inner ring thereof is press-fitted into the steering shaft. Therefore, as a moisture intrusion path from the torque sensor side accommodation portion to the reduction mechanism side accommodation space, a gap between the outer ring fitted into the inner cylinder portion in the sealed bearing and the inner cylinder portion is assumed. However, this gap is closed from one side, that is, the torque sensor side by the sensor spacer. As a result, moisture can be prevented from entering the speed reduction mechanism from the torque sensor side.

  According to the second aspect of the present invention, the rubber contact portion of the sensor spacer is in close contact with the outer ring and the inner cylinder portion from one side, thereby reliably closing the gap between the outer ring and the inner cylinder portion from the one side. Therefore, it is possible to reliably suppress moisture from entering the speed reduction mechanism from the torque sensor side.

  According to the third aspect of the invention, the sensor spacer including the metal skeleton can reliably close the gap between the outer ring and the inner cylinder portion from one side by maintaining a stable shape. Intrusion of moisture from the torque sensor side to the speed reduction mechanism can be reliably suppressed.

  According to the fourth aspect of the present invention, in the sensor spacer, the first contact portion in the first overhang portion is in close contact with the outer ring, and the second contact portion in the second overhang portion is in close contact with the inner cylinder portion. Since the gap between the outer ring and the inner cylinder part can be reliably closed from one side, moisture can be reliably prevented from entering the speed reduction mechanism from the torque sensor side.

FIG. 1 is a schematic cross-sectional view showing a schematic configuration of an electric power steering apparatus according to an embodiment of the present invention. FIG. 2 is a sectional view of a sensor spacer used in the electric power steering apparatus. FIG. 3 is an enlarged view of a main part in FIG.

  Preferred embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a schematic cross-sectional view showing a schematic configuration of an electric power steering apparatus 1 according to an embodiment of the present invention. The electric power steering apparatus 1 includes a steering shaft 2, a column jacket 3, a torque sensor 4, a speed reduction mechanism 5, an electric motor 6, a gear housing 7, a housing spacer 8, a first bearing 9, and a second bearing. A bearing 10 and a sensor spacer 11 are included.

  Although the steering shaft 2 extends while being inclined with respect to the horizontal direction in FIG. 1, the steering shaft 2 may extend along the horizontal direction. A direction in which the steering shaft 2 extends is referred to as an axial direction X. The left-right direction in FIG. 1 is the front-rear direction of a vehicle (not shown) on which the electric power steering device 1 is mounted. In the following, one side X1 of the axial direction X is set in accordance with the front-rear direction of the vehicle. It is referred to as a rear side X1, and the other side X2 is referred to as a front side X2. A steering member 12 such as a steering wheel is connected to the rear end 2A of the steering shaft 2. A steering mechanism 13 constituted by a rack and pinion mechanism or the like is connected to the front end portion 2B of the steering shaft 2 via an intermediate shaft 14. When the steering member 12 is steered and the steering shaft 2 rotates, this rotation is converted into a linear movement in the vehicle width direction of a rack shaft (not shown) in the steering mechanism 13. Thereby, the turning of the turning rod (not shown) connected with the rack shaft is achieved.

  The steering shaft 2 includes an input shaft 15 directly connected to the steering member 12, an output shaft 16 directly connected to the intermediate shaft 14, and a torsion bar 17 that coaxially connects the input shaft 15 and the output shaft 16. . The rear end portion 16A of the output shaft 16 is inserted into a recess 15A formed on the front end surface of the input shaft 15, and in this state, the output shaft 16 is not in contact with the input shaft 15. The output shaft 16 is hollow, and a torsion bar 17 is accommodated in the output shaft 16. The output shaft 16 and the front end portions of the torsion bar 17 are connected to each other by a connecting pin 18, and the rear end portion 17A of the torsion bar 17 protrudes from the output shaft 16 to the rear side X1. The rear end portion 17A is inserted into a concave portion 15B that is further recessed from the bottom of the concave portion 15A of the input shaft 15 to the rear side X1, and is connected to the input shaft 15 by serration fitting or the like. When the steering member 12 is steered, the torsion bar 17 is elastically twisted and deformed, whereby the input shaft 15 and the output shaft 16 are relatively rotated.

  The column jacket 3 is formed in a tubular shape (specifically, a circular tubular shape) extending in the axial direction X, and accommodates a portion of the steering shaft 2 between the rear end portion 2A and the front end portion 2B. In this state, the steering shaft 2 and the column jacket 3 are arranged coaxially. Between the rear end 3 </ b> A of the column jacket 3 and the steering shaft 2, for example, a bearing 19 constituted by a rolling bearing is interposed, and the column jacket 3 supports the steering shaft 2 rotatably by the bearing 19. ing. In the steering shaft 2, an annular seal member 20 is externally fitted to a portion on the rear side X <b> 1 from the bearing 19. The seal member 20 is an oil seal, for example, and closes the gap between the rear end 3A of the column jacket 3 and the steering shaft 2 from the rear side X1, so that water, dust, or the like enters the column jacket 3 from the gap. Is preventing. The column jacket 3 is fixed to a vehicle body 22 of a vehicle (not shown) via a bracket 21.

  A cylindrical (specifically cylindrical) accommodating portion 25 is formed at the front end 3 </ b> B of the column jacket 3. The accommodating portion 25 is integrally formed with the column jacket 3 by expanding the front end portion 3B by one step, and accommodates the steering shaft 2, specifically, the boundary portion between the input shaft 15 and the output shaft 16. The rear end portion 25A of the accommodating portion 25 is formed in a tapered shape that increases in diameter toward the front side X2. A positioning portion 26 that protrudes toward the steering shaft 2 is provided at a position adjacent to the rear end portion 25A from the front side X2 on the inner peripheral surface 25B of the housing portion 25. The positioning portion 26 is formed integrally with the housing portion 25 by, for example, denting the housing portion 25 toward the steering shaft 2 side. There may be a plurality of positioning portions 26, in which case they are arranged side by side in the circumferential direction of the inner peripheral surface 25B. A through hole 25 </ b> C is formed at a position shifted in the housing portion 25 toward the front side X <b> 2 from the positioning portion 26.

  The torque sensor 4 is a sensor that detects a steering torque when the driver steers the steering member 12. Torque sensor 4 includes a main body 30 and a wiring 31 extending from main body 30. The main body 30 is disposed in the housing portion 25 and surrounds a boundary portion between the input shaft 15 and the output shaft 16. Since the accommodating portion 25 that is a part of the column jacket 3 also serves as a housing that accommodates the torque sensor 4, the number of parts can be reduced and the size can be reduced. The main body 30 has a cylindrical permanent magnet 32 which is externally fitted and fixed to the output shaft 16, and a cylindrical shape which is externally fitted and fixed to the input shaft 15 while surrounding the permanent magnet 32 in a non-contact manner. A cylindrical portion 33. The permanent magnet 32 has N and S poles alternately arranged in the circumferential direction. The cylindrical portion 33 is made of resin, and includes a pair of front and rear annular magnetic yokes 34 surrounding the permanent magnet 32 and a pair of front and rear annular magnetic collecting rings surrounding the magnetic yokes 34 one by one. 35 and a magnetic sensor (not shown) connected to the wiring 31 are provided. Each magnetic yoke 34 is provided with the same number of claws 36 as the set of N poles and S poles in the permanent magnets 32 arranged at equal intervals along the circumferential direction of the magnetic yoke 34.

  In a state where the steering member 12 is not steered, the tip of each claw 36 coincides with the boundary between the N pole and the S pole in the permanent magnet 32, so that no magnetic flux is generated between the pair of magnetic yokes 34. . On the other hand, when the input shaft 15 and the output shaft 16 are rotated relative to each other by the steering of the steering member 12, the tips of the claws 36 deviate from the boundary between the N pole and the S pole in the permanent magnet 32. As a result, a magnetic flux having a density corresponding to the amount of relative rotation between the input shaft 15 and the output shaft 16 is generated between the pair of magnetic yokes 34, and this magnetic flux is taken out by the magnetism collecting ring 35. Is detected by a magnetic sensor (not shown) as steering torque. The wiring 31 is drawn out of the column jacket 3 from the through hole 25 </ b> C of the housing portion 25.

  The speed reduction mechanism 5 includes a disk-shaped worm wheel 40 and a worm 41. A portion 2C of the steering shaft 2, more specifically, the front side X2 of the output shaft 16 from the torque sensor 4, passes through the circular center portion of the worm wheel 40 and is connected to the worm wheel 40 so as to be integrally rotatable by press-fitting or spline coupling. Has been. In the worm wheel 40, the inner peripheral portion 40A connected to the steering shaft 2 is made of metal, but the outer peripheral portion 40B surrounding the inner peripheral portion 40A is made of, for example, resin for weight reduction or the like. A plurality of tooth grooves 40C that mesh with the worm 41 are formed at equal intervals along the circumferential direction of the outer peripheral portion 40B on the outer peripheral surface of the outer peripheral portion 40B. The worm 41 is disposed, for example, on the lower side of the worm wheel 40 and is connected to an output shaft (not shown) of the electric motor 6.

  In association with the torque sensor 4 and the speed reduction mechanism 5, there are a vehicle speed sensor 45 that detects the speed of a vehicle (not shown) and an ECU (Electronic Control Unit) 46. The vehicle speed sensor 45 and the ECU 46 may be a part of the electric power steering device 1 or may be a device different from the electric power steering device 1. The wiring 31 of the torque sensor 4 is connected to the ECU 46. The ECU 46 calculates a necessary steering assist force based on the steering torque detected by the torque sensor 4 and the vehicle speed detected by the vehicle speed sensor 45, and controls the drive of the electric motor 6 so as to generate this steering assist force. To do. As a result, the driving force generated by the electric motor 6 is transmitted to the worm 41 so that the worm 41 is driven to rotate, and the worm wheel 40 engaged with the worm 41 rotates at a lower rotational speed than the worm 41. The rotation of the worm wheel 40 assists the rotation of the steering shaft 2, that is, the steering of the steering member 12.

  The gear housing 7 is a component that houses the speed reduction mechanism 5 and to which the electric motor 6 is fixed. The gear housing 7 has a substantially cylindrical first cylindrical portion 51 having a center axis (not shown) coinciding with the steering shaft 2 and a center axis (not shown) extending in a direction orthogonal to the steering shaft 2. A cylindrical second cylindrical portion 52 is integrally included. The first cylindrical portion 51 integrally includes a large diameter portion 53 and a small diameter portion 54 that is continuous with the large diameter portion 53 from the front side X2 and has a smaller diameter than the large diameter portion 53. The gear housing 7 is fixed to the vehicle body 22 via the bracket 55.

  The second cylindrical portion 52 is disposed, for example, below the first cylindrical portion 51, and the internal space of the second cylindrical portion 52 is relative to the internal space surrounded by the large diameter portion 53 in the first cylindrical portion 51. And communicate from below. The substantially front half region in the internal space of the large-diameter portion 53 and the internal space of the second cylindrical portion 52 constitute an accommodation space 7 </ b> A in which the reduction mechanism 5 is accommodated in the gear housing 7. Specifically, a part of the steering shaft 2 and the worm wheel 40 connected to the part are accommodated in a substantially front half region in the internal space of the large diameter part 53, and the second cylindrical part 52 A worm 41 is accommodated in the internal space. A region corresponding to substantially the latter half of the internal space of the large-diameter portion 53 constitutes a circular opening 7B that communicates with the accommodation space 7A in the gear housing 7 and extends to the rear side X1 and opens toward the torque sensor 4. Yes. A front end 25D of the accommodating portion 25 of the column jacket 3 is inserted into the opening 7B from the rear side X1. A portion of the front side X2 of the steering shaft 2 is inserted into the accommodation space 7A and the opening 7B, and the front end portion 2B of the steering shaft 2 protrudes from the small diameter portion 54 of the first cylindrical portion 51 to the front side X2.

  The housing spacer 8 is an annular component that closes the gap (gap in the radial direction R around the steering shaft 2) between the gear housing 7 and the accommodating portion 25 in the opening 7B and holds the front end 3B of the column jacket 3. is there. The housing spacer 8 integrally includes an outer cylinder part 60, an inner cylinder part 61, and a connecting part 62. Each of the outer cylinder part 60 and the inner cylinder part 61 is formed in a cylindrical shape having a plate thickness direction coinciding with the radial direction R, and the inner cylinder part 61 is smaller in diameter than the outer cylinder part 60, and the outer cylinder part 60. The connecting portion 62 is formed in an annular shape having a plate thickness direction that coincides with the axial direction X, and is laid between the front end portions of the outer cylindrical portion 60 and the inner cylindrical portion 61, whereby the outer cylindrical portion 60 and the inner cylindrical portion The parts 61 are connected. In this state, all of the outer cylinder part 60, the inner cylinder part 61 and the connecting part 62 are arranged coaxially.

  The outer cylinder portion 60 is press-fitted into the opening 7 </ b> B of the gear housing 7 by being fitted into the large diameter portion 53 of the first cylindrical portion 51 of the gear housing 7. The inner cylinder portion 61 is press-fitted into the inner peripheral surface 25B of the front end portion 25D of the accommodating portion 25 and press-contacted from the inner side in the radial direction R in a state of surrounding the steering shaft 2, specifically the output shaft 16. The connecting portion 62 faces the worm wheel 40 from the rear side X1. The front end portion 25 </ b> D of the housing portion 25 is in contact with the connecting portion 62 from the rear side X <b> 1 in a state where the front end portion 25 </ b> D overlaps the inner cylinder portion 61 from the outside in the radial direction R.

  The first bearing 9 is disposed between the worm wheel 40 and the torque sensor 4 in the axial direction X. The first bearing 9 is a rolling bearing with a seal, and an inner ring 65, an outer ring 66, a plurality of spherical rolling elements 67 disposed between the inner ring 65 and the outer ring 66, and these rolling elements 67 are equally spaced. And a pair of seal members 68. The inner ring 65 is fitted on the output shaft 16 of the steering shaft 2 in a press-fit state. The outer ring 66 is fitted into the inner cylinder portion 61 of the housing spacer 8. The outer ring 66 may be press-fitted into the inner cylinder portion 61. The pair of seal members 68 seals the space in which the rolling elements 67 are disposed between the inner ring 65 and the outer ring 66 from both sides in the axial direction X. In the first bearing 9, the inner ring 65 may contact the inner peripheral portion 40 </ b> A of the worm wheel 40 from the rear side X <b> 1, but the outer ring 66 is not in contact with the worm wheel 40.

  The second bearing 10 is a rolling bearing with a seal having the same configuration as the first bearing 9. In the second bearing 10, the inner ring 75 is externally fitted in a press-fit state with respect to the portion of the output shaft 16 on the front side X <b> 2 from the worm wheel 40, and the outer ring 76 is a small diameter portion 54 of the first cylindrical portion 51 of the gear housing 7. Are fitted in a press-fitted state. This prevents moisture from entering the gear housing 7 from the front side X2. A stepped portion 16B whose diameter is increased by one step outward in the radial direction R on the outer peripheral surface of the output shaft 16 and an annular plug 77 screwed to the output shaft 16 from the front side X2 are formed from both sides in the axial direction X. The inner ring 75 is sandwiched between the second bearing 10 and the second bearing 10 in the axial direction X. The steering shaft 2 rotatably supported by the column jacket 3 via the bearing 19 on the rear end portion 2A side, the gear housing 7 and the housing spacer via the first bearing 9 and the second bearing 10 on the front end portion 2B side. 8 is rotatably supported.

  The sensor spacer 11 is a component that closes the gap in the axial direction X between the torque sensor 4 and the first bearing 9 and the housing spacer 8 that are components around the sensor. The sensor spacer 11 has an annular overall shape surrounding the output shaft 16 in the steering shaft 2. Referring to FIG. 2, the sensor spacer 11 includes an annular main body 80 that surrounds the output shaft 16, and an annular first body that protrudes from the front end of the main body 80 to the output shaft 16 side (that is, the inside in the radial direction R). The first overhanging portion 81 and an annular second overhanging portion 82 projecting from the rear end portion of the main body portion 80 to the side opposite to the output shaft 16 side (that is, the outside in the radial direction R) are integrally included. The cross section at one place on the circumference of such a sensor spacer 11 is formed in a crank shape.

  The sensor spacer 11 includes a metal skeleton 83 and a rubber portion 84 that covers the entire surface of the skeleton 83. The skeleton 83 has a crank-shaped cross section similar to the cross section of the sensor spacer 11. Therefore, the skeleton 83 includes an annular first portion 83A constituting the main body portion 80, and an annular second portion constituting the first overhanging portion 81 by projecting inward in the radial direction R from the front end portion of the first portion 83A. 83B and an annular third portion 83C that protrudes outward in the radial direction R from the rear end portion of the first portion 83A and constitutes the second protruding portion 82 are integrally included.

  A contact portion 85 is provided on the surface of the sensor spacer 11. Since the surface of the sensor spacer 11 is the rubber portion 84, the contact portion 85 is a part of the rubber portion 84 and is made of rubber. The contact portion 85 is provided on the front end surface 81A of the first overhang portion 81 and protrudes toward the front side X2, and is provided on the front end surface 82A of the second overhang portion 82 and toward the front side X2. And a protruding annular second contact portion 85B. The second contact portion 85B has a larger diameter than the first contact portion 85A.

  With reference to FIG. 3, the sensor spacer 11 is sandwiched from both sides in the axial direction X by the torque sensor 4 and the inner cylinder portion 61 of the housing spacer 8. Specifically, in the sensor spacer 11, the main body 80 and the first overhang 81 are disposed in the gap 87 between the torque sensor 4 and the outer ring 66 of the first bearing 9 in the axial direction X, and the second overhang 82 is provided. The axial direction X is disposed in the gap 88 between the main body 30 of the torque sensor 4 and the inner cylinder portion 61. The rubber portion 84 in the second overhang portion 82 is compressed by the main body 30 and the inner cylinder portion 61, and urges the main body 30 to the rear side X1 by returning to the original state. As a result, the main body 30 is pressed against the positioning portion 26 (see FIG. 1) of the housing portion 25, so that the torque sensor 4 in the housing portion 25 is positioned in the axial direction X.

  When the electric power steering apparatus 1 is assembled, the housing spacer 8 is press-fitted into the opening 7B of the gear housing 7 that houses the speed reduction mechanism 5 and the steering shaft 2, and the first bearing 9 is assembled to the steering shaft 2, and the sensor spacer 11 is temporarily assembled to the inner cylinder portion 61 such that the main body portion 80 is fitted into the inner cylinder portion 61 of the housing spacer 8. Thereafter, the accommodating portion 25 of the column jacket 3 is press-fitted into the inner cylinder portion 61 from the rear side X1. Then, the front end face 30 </ b> A of the main body 30 of the torque sensor 4 accommodated in the accommodating portion 25 comes into contact with the second projecting portion 82 of the sensor spacer 11 from the rear side X <b> 1. Accordingly, the first contact portion 85A provided in the first overhanging portion 81 of the sensor spacer 11 is pressed against the rear end surface 66A of the outer ring 66 of the first bearing 9 and is crushed, and the outer ring 66 is against the rear end surface 66A. It adheres from the rear side X1 over the whole area in the circumferential direction. Further, in the sensor spacer 11, the second contact portion 85B provided on the second projecting portion 82 is crushed by being pressed against the rear end surface 61A of the inner cylinder portion 61, and the circumference of the inner cylinder portion 61 is made against the rear end surface 61A. It adheres from the rear side X1 over the whole area in the direction. Therefore, in the completed electric power steering apparatus 1, the gap 90 between the outer ring 66 and the inner cylinder portion 61 in the radial direction R is caused by the portion between the first contact portion 85 </ b> A and the second contact portion 85 </ b> B in the sensor spacer 11. It is closed from the side X <b> 1 and is blocked from the inside of the housing portion 25.

  As described above, the outer cylindrical portion 60 of the housing spacer 8 is press-fitted into the opening 7B of the gear housing 7, and the inner cylindrical portion 61 of the housing spacer 8 is press-fitted into the inner peripheral surface 25B of the front end portion 25D of the accommodating portion 25. The first bearing 9 between the worm wheel 40 and the torque sensor 4 is a bearing with a seal, and an inner ring 65 thereof is press-fitted into the steering shaft 2. In this case, for example, as a moisture intrusion path from the accommodation portion 25 on the torque sensor 4 side to the accommodation space 7A on the reduction mechanism 5 side through the through hole 25C (see FIG. 1), A gap 90 between the outer ring 66 fitted to the inner cylinder portion 61 and the inner cylinder portion 61 in one bearing 9 is assumed. However, the gap 90 is blocked by the sensor spacer 11 from the rear side X1, that is, the torque sensor 4 side. Therefore, it is possible to suppress moisture from entering the speed reduction mechanism 5 from the torque sensor 4 side.

  In particular, the rubber contact portion 85 in the sensor spacer 11 is in close contact with the outer ring 66 and the inner cylinder portion 61 from the rear side X1. Specifically, the first contact portion 85A in the first overhang portion 81 is in close contact with the outer ring 66. The second contact portion 85 </ b> B in the second overhang portion 82 is in close contact with the inner cylinder portion 61. Furthermore, the sensor spacer 11 including the metal skeleton 83 can maintain a stable shape. Therefore, since the gap 90 between the outer ring 66 and the inner cylinder portion 61 can be reliably closed from the rear side X1 by the sensor spacer 11, the intrusion of moisture from the torque sensor 4 side to the speed reduction mechanism 5 can be reliably suppressed.

  Thus, the sensor spacer 11 not only has a function of positioning the torque sensor 4 in the axial direction X, but also has a function of suppressing moisture from entering the gap 90 between the outer ring 66 and the inner cylinder portion 61. Therefore, it is possible to suppress expansion of the resin-made outer peripheral portion 40B of the worm wheel 40 due to moisture absorption due to moisture entering from the gap 90 into the accommodation space 7A. Accordingly, it is possible to suppress an increase in steering of the steering member 12 due to the tight engagement between the outer peripheral portion 40B and the worm 41 (that is, an increase in rotational torque necessary for steering of the steering member 12). Conventionally, in order to prevent moisture from entering the accommodating space 7A from the gap 90, liquid packing such as grease is applied to the gap 90. However, by using the sensor spacer 11 of this time, the liquid packing is used. Therefore, the cycle time for manufacturing the electric power steering apparatus 1 can be shortened.

  Further, in the sensor spacer 11 having the crank-shaped cross section described above, the outer peripheral surface 80A having no step in the main body portion 80 is internally fitted to the inner peripheral surface 61B of the inner cylindrical portion 61 of the housing spacer 8. The inner circumferential surface 61B of the cylindrical portion 61 can be a circumferential surface without a step. Thereby, the shape of the housing spacer 8 can be simplified, and the material cost and the processing cost can be reduced by eliminating the step on the inner peripheral surface 61B of the inner cylindrical portion 61.

  The present invention is not limited to the embodiments described above, and various modifications can be made within the scope of the claims.

DESCRIPTION OF SYMBOLS 1 ... Electric power steering device, 2 ... Steering shaft, 2A ... Rear end part, 2C ... part, 3 ... Column jacket, 3B ... Front end part, 4 ... Torque sensor, 5 ... Reduction mechanism, 6 ... Electric motor, 7 ... Gear Housing, 7A ... accommodating space, 7B ... opening, 8 ... housing spacer, 9 ... first bearing, 11 ... sensor spacer, 12 ... steering member, 25 ... accommodating part, 25B ... inner peripheral surface, 25D ... front end, 40 ... Worm wheel, 41 ... Worm, 60 ... Outer cylinder part, 61 ... Inner cylinder part, 62 ... Connection part, 65 ... Inner ring, 66 ... Outer ring, 80 ... Main body part, 81 ... First overhang part, 81A ... Front end face , 82 ... second overhanging part, 82A ... front end face, 83 ... skeleton, 85 ... contact part, 85A ... first contact part, 85B ... second contact part, 90 ... gap, X ... axial direction, X1 ... one side (Rear side), X2 ... the other side (front side)

Claims (4)

A steering shaft to which a steering member is coupled to an end portion on one side in the axial direction;
A column-shaped housing portion in which a tubular housing portion is formed at the other end portion in the axial direction and houses the steering shaft;
A torque sensor housed in the housing portion for detecting a steering torque of a steering member;
A speed reduction mechanism including a worm wheel coupled to the steering shaft so as to be integrally rotatable with respect to the other side of the torque sensor; and a worm meshed with the worm wheel and driven and rotated by an electric motor;
A gear housing in which a housing space housing the speed reduction mechanism and an opening communicating with the housing space and opening toward the torque sensor are formed, and the steering shaft is inserted into the housing space and the opening; ,
An outer cylinder part press-fitted into the opening, an inner cylinder part surrounded by the outer cylinder part and press-fitted into an inner peripheral surface of the other end of the housing part, the outer cylinder part and the inner part A housing spacer having a connecting portion connecting the cylindrical portions;
A sealed bearing having an inner ring that is disposed between the worm wheel and the torque sensor in the axial direction and is press-fitted into the steering shaft; and an outer ring that is fitted into the inner cylinder portion;
An electric power steering apparatus comprising: a sensor spacer sandwiched from both sides in the axial direction by the torque sensor and the inner cylinder portion and closing a gap between the outer ring and the inner cylinder portion from the one side.   The electric power steering apparatus according to claim 1, wherein the sensor spacer includes a rubber contact portion that is in close contact with the outer ring and the inner cylinder portion from the one side.   The electric power steering apparatus according to claim 2, wherein the sensor spacer includes a metal skeleton. The sensor spacer includes an annular main body that surrounds the steering shaft, an annular first projecting portion that projects from the other end of the main body toward the steering shaft, and the one of the main body. An annular second projecting portion projecting from the end portion on the side to the side opposite to the steering shaft side,
The close contact portion is provided on an end surface on the other side of the first overhanging portion and closely attached to the outer ring, and provided on an end surface on the other side of the second overhanging portion. The electric power steering device according to claim 3, further comprising an annular second close contact portion that is in close contact with the inner cylinder portion.

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