JP2012001050A - Electric power steering device - Google Patents

Abstract

An object of the present invention is to make it possible to adjust an axis between a driven rotating body and a driving rotating body with a simple device.
A rack tooth 20a and a ball screw portion 20b are formed on a rack shaft 20, a pinion shaft 21 meshing with the rack tooth 20a is rotatably supported on a gear housing 11, and a ball nut 50 meshing with the ball screw portion 20b is provided. In the electric power steering apparatus in which the driven rotating body 54 that rotates integrally with the gear housing 11 is rotatably supported on the gear housing 11 and the driving rotating body 71 is rotationally connected to the driving shaft 70 a of the electric motor 70. The body 54 is provided so as to be movable in a radial direction so that the distance between the driven rotating body 54 and the driving rotating body 71 changes according to the gear housing 11, and a sliding bearing 73 that guides and supports the rack shaft 20 is provided. Adjustment is provided in the gear housing 11 so as to be movable in the radial direction, and the sliding bearing 73 is moved in the radial direction and held in that position. The lifting device 78 is provided in the gear housing 11.
[Selection] Figure 1

Description

  The present invention relates to an electric power steering device that transmits an assist force of an electric motor to a rack shaft via a ball screw.

As an electric power steering device using a conventional ball screw, there is one disclosed in Patent Document 1.

  The electric power steering apparatus 100 shown in FIG. 7 is configured to transmit the assist force of the electric motor 101 to the rack shaft 110 via the drive pulley 102, the timing belt 103, the driven pulley 104, and the ball screw 105. Both ends of the rack shaft 110 are connected to the wheels via a ball joint (not shown), and the direction of the wheels can be changed by the axial movement of the rack shaft 110. An unillustrated handle is rotationally connected to rack teeth formed on the rack shaft 110 via an unillustrated pinion shaft, and the rotation of the handle is converted into an axial movement of the rack shaft 110.

In order for the assist force of the electric motor 101 to be smoothly transmitted to the rack shaft 110, it is necessary to apply an optimum belt tension to the timing belt 103. The drive pulley 102 is rotatably supported on the adjustment collar 111 at a position eccentric to the axis of the adjustment collar 111. When the adjustment collar 111 is turned and the belt tension of the timing belt 103 becomes optimum, the lock nut 112 is screwed into the male thread 111a of the adjusting collar 111, and the adjusting collar 111 is fixed to the gear housing 113 while maintaining the angle thereof.

JP 2005-145431 A

The above-described apparatus requires not only the adjustment collar 111 but also a rotating shaft 114 that is coaxially connected to the drive shaft 113 of the electric motor 101, and a bearing 115 that rotatably supports the rotating shaft 114. In many cases, the structure is complicated and it takes time to assemble.

According to the first aspect of the present invention, the rack shaft is inserted into the gear housing so as to be movable in the axial direction, rack teeth are formed on one end side of the rack shaft, and a ball screw portion is formed on the other end side. A pinion shaft formed with meshing pinion teeth is rotatably supported on the gear housing around an axis intersecting the rack shaft, and a ball nut meshing with the ball screw portion and a driven rotating body rotating integrally therewith are connected to the gear housing. An electric power steering system in which a drive rotating body that is rotatably supported on a shaft, transmits a rotation with a driven rotating body, and rotates around an axis parallel to the driven rotating body is rotationally connected to a driving shaft of the electric motor, and the electric motor is attached to the gear housing. In the apparatus, the ball nut and the driven rotator are determined so that an inter-axis distance between the driven rotator and the drive rotator changes in the gear housing. A sliding bearing provided so as to be movable in the radial direction and slidably guiding and supporting the rack shaft is provided in the gear housing so as to be movable in the radial direction, and the sliding bearing is moved in the radial direction and held at the position. The adjustment holding device is provided in the gear housing.

According to this configuration, since the rack shaft is tilted with the meshing point of the rack shaft and pinion shaft as a fulcrum, the ball nut, driven rotor, and slide bearing can be moved in the radial direction defined in the gear housing. This can be achieved with a simple configuration provided in the above. The number of parts is small, the structure is simple, and the assembly is easy.

According to a second aspect of the present invention, in the electric power steering apparatus according to the first aspect, the driven rotating body is a driven pulley, the driving rotating body is a driving pulley, and a timing belt is provided between the driven pulley and the driving pulley. It is the one that was handed over.

According to this configuration, by adjusting the length of the timing belt, the drive pulley can be installed at an arbitrary position with respect to the driven pulley. That is, the electric motor can be installed at an arbitrary place. Most of the timing belts are made of rubber, and the engagement noise between the timing belt and the pulley is small.

According to a third aspect of the present invention, in the electric power steering apparatus according to the first aspect, the driven rotary body is a driven gear, the drive rotary body is a drive gear, and the driven gear and the drive gear mesh with each other. Is.

According to this configuration, it is not necessary to apply tension to the meshing between the gears, and the possibility that the gear teeth are broken is very low and the reliability is high.

According to a fourth aspect of the present invention, in the electric power steering apparatus according to the first, second, and third aspects, a guide surface is provided in the gear housing for guiding and supporting the sliding bearing so as to be movable in the radial direction.

According to this configuration, since the sliding of the guide surface is used, the number of parts is reduced, the structure becomes simpler, and the assembly becomes easier.

According to a fifth aspect of the present invention, in the electric power steering apparatus according to the first, second, and third aspects, the adjustment holding means is screwed into the gear housing on both sides of the sliding bearing so that the sliding bearing can advance and retreat. A pair of adjusting screws in contact with each other.

According to this configuration, the sliding bearing can be moved in the radial direction and held at that position simply by screwing the pair of adjusting screws into the gear housing. The number of parts is reduced, the structure is simpler, and the assembly is easier.

According to a sixth aspect of the present invention, in the electric power steering apparatus according to the first aspect, a rolling bearing is disposed between the ball nut and the gear housing in order to pivotally support the ball nut on the gear housing. The rolling bearing comprises an inner ring that is attached to the ball nut so as not to move in the axial direction, an outer ring that is fitted to the gear housing, and a rolling element that rolls between the inner ring and the outer ring. A guide surface for guiding the outer ring in the radial direction is provided in the gear housing so as to be movable in the radial direction in the housing.

According to this configuration, the ball nut and the driven rotating body can be smoothly rotated with a very simple configuration, and can be moved in the radial direction.

According to a seventh aspect of the present invention, in the electric power steering device according to the sixth aspect, after the adjustment of the radial movement of the outer ring, the guide surface is held in a state where an axial elastic force is applied to the outer ring. An elastic holding device was provided in the gear housing.

According to this structure, it can support in the state which provided the elastic force of the axial direction with respect to the ball nut, the driven rotary body, and the rack shaft, and the support rigidity of the rack shaft is increased.

According to an eighth aspect of the present invention, in the electric power steering device according to the seventh aspect, rubber spacers are arranged on both sides in the axial direction of the outer ring as the elastic holding device, and a guide surface is formed on the outer ring side of the spacer. .

According to this structure, since the friction coefficient of the spacer is high, the frictional force between the guide surface of the spacer and the outer ring is increased, and the support rigidity in the radial direction of the rack shaft is increased.

According to the present invention, since the rack shaft is tilted with the meshing point of the rack shaft and pinion shaft as a fulcrum, the ball nut, driven rotor, and slide bearing can be moved in the radial direction defined in the gear housing. This can be achieved with a simple configuration provided in the above. As a result, the number of parts is small, the structure is simple, and the assembly is simple.

1 is an overall configuration diagram of an electric power steering apparatus according to an embodiment of the present invention. It is an AA line expanded sectional view of Drawing 1 in an embodiment of the present invention. It is a B arrow enlarged view of FIG. 1 in embodiment of this invention. FIG. 2 is a partially enlarged view of FIG. 1 in the embodiment of the present invention. FIG. 2 is an enlarged sectional view taken along the line CC of FIG. 1 in the embodiment of the present invention. FIG. 2 is an enlarged sectional view taken along line DD of FIG. 1 in the embodiment of the present invention. It is sectional drawing of the conventional electric power steering apparatus.

An embodiment of the present invention will be described with reference to FIGS. 1 is an overall configuration diagram of the electric power steering apparatus, FIG. 2 is an enlarged cross-sectional view taken along line AA in FIG. 1, FIG. 3 is an enlarged view taken along arrow B in FIG. 1, and FIG. 5 is a partially enlarged view, FIG. 5 is an enlarged sectional view taken along the line CC in FIG. 1, and FIG. 6 is an enlarged sectional view taken along the line DD in FIG.

In FIG. 1, the electric power steering apparatus 10 has a gear housing 11, and a rack shaft 20 is inserted into a cylindrical cylindrical portion 12 of the gear housing 11. One end of a ball joint (not shown) is connected to both ends of the rack shaft 20, and a wheel (not shown) is connected to the other end of the ball joint so that the direction of the wheel can be changed by movement of the rack shaft 20 in the axial direction. It has become.

In FIG. 2, rack teeth 20a are formed at one end of the rack shaft 20, and the pinion teeth 21a of the pinion shaft 21 mesh with the rack teeth 20a. One end of the gear housing 11 has a gear portion 13 extending in a direction crossing the longitudinal direction of the gear housing 11. The pinion shaft 21 is rotatably supported by a gear portion 13 of the gear housing 11 via a roller bearing 22 and a ball bearing 23 around an axis intersecting the rack shaft 20. A guide hole 16 is formed in the gear portion 13 of the gear housing 11 in a direction crossing both the axis of the rack shaft 20 and the axis of the pinion shaft 21, and a rack guide 24 is slidably fitted into the guide hole 16. Yes. A female screw 16a is formed on the opening side of the guide hole 16, and a lid 25 is screwed onto the female screw 16a. A coil spring 26 is inserted between the lid 25 and the rack guide 24, and this coil spring 26 serves to press the rack shaft 20 against the pinion shaft 21. A rack shaft sheet 27 is attached to the rack shaft 20 side of the rack guide 24, and the rack shaft sheet 27 is in sliding contact with the back surface of the rack shaft 20 opposite to the rack teeth 20 a.

A connection shaft 30 is disposed coaxially with one end of the pinion shaft 20, and the connection shaft 30 is rotatably supported on the pinion shaft 20 via a roller bearing 31, and the connection shaft 30 is interposed via a ball bearing 32. And is rotatably supported by the gear portion 13 of the gear housing 11. A torsion bar 33 is disposed coaxially with the inner periphery of the connecting shaft 30, one end of the torsion bar 33 is connected to the connecting shaft 30, and the other end of the torsion bar 33 is connected to the pinion shaft 21. The rotation of the connecting shaft 30 is transmitted to the pinion shaft 21 via the torsion bar 33. The connecting shaft 30 is connected to the handle via a steering column (not shown).

A torque sensor 40 is installed in the gear housing 11, and this torque sensor 40 acts on the connecting shaft 30 by observing the relative rotation amount of the pinion shaft 21 and the connecting shaft 30, that is, the twist amount of the torsion bar 33. Torque is detected.

In FIG. 1, a ball screw portion 20b is formed at the other end of the rack shaft 20, and a ball nut 50 is screwed to the ball screw portion 20b via a large number of balls. The ball screw portion 20b and the ball nut 50 constitute a ball screw 51. A cylindrical collar 52 is fitted on the outer periphery of the ball nut 50. The collar 52 has a large diameter portion 52a at one end and a small diameter portion 52b at the other end, and the large diameter portion 52a and the small diameter portion 52b. A step 52c is provided between them. A female screw 52d is formed on the inner periphery of the large-diameter portion 52a, and a clasp 53 is screwed to the female screw 52d. The ball nut 50 has a flange portion 50 a on the outer periphery of one end, and the flange portion 50 a is sandwiched between the step portion 52 c and the clasp 53. As a result, the ball nut 50 can rotate integrally with the collar 52.

A driven pulley 54 is inserted into the outer periphery of the collar 52. The driven pulley 54 includes a large diameter portion 54a that is inserted into the large diameter portion 52a of the collar 52, and a small diameter portion 54b that is inserted into the small diameter portion 52b of the collar 52. The step portion 54c is provided between the large diameter portion 54a and the small diameter portion 54b. A ball bearing 55 is fitted on the outer periphery of the collar 52, and a screw 52 e is formed on one end outer periphery of the collar 52. A nut 56 is screwed onto the male screw 52e, and the shaft 52 with respect to the collar 52 of the driven pulley 54 and the ball bearing 55 is sandwiched between the small diameter portion 54b of the driven pulley 54 and the ball bearing 55 by the step portion 52c of the collar 52 and the nut 56. Constrain direction position. The ball bearing 55 includes an inner ring 55a fixed to the collar 52, an outer ring 55b fitted to a support surface 61 of the support portion 14 of the gear housing 11 described later, and a rolling element that rolls between the inner ring and the outer ring. (Ball) 55c.

The other end of the gear housing 11 has a support portion 14 and a lid portion 15 that are expanded in the radial direction, and the lid portion 15 is fixed to the support portion 14 with a bolt 60. A cylindrical support surface 61 is formed coaxially with the rack shaft 20 on the inner periphery of the support portion 14, and the outer ring 55 b of the ball bearing 55 is fitted to the support surface 61. Since the inner diameter of the support surface 61 is slightly larger than the outer ring 55 b of the ball bearing 55, a gap a as shown in FIG. 4 exists between the support surface 61 and the outer ring 55 b of the ball bearing 55. A first spacer 62 and a second spacer 63 are inserted between the outer ring of the lid 15 and the ball bearing 55, and a third spacer 65 is inserted between the step part 64 of the support unit 14 and the outer ring of the ball bearing 55. Has been. The second spacer 63 and the third spacer 65 are made of rubber and can be elastically deformed. The first spacer 62 is made of aluminum, which is the same material as the gear housing 11, and is press-fitted and fixed to the support surface 61. The first spacer 62 has a function of temporarily fixing the second spacer 63 and the ball bearing 55 so that the second spacer 63 and the ball bearing 55 are not removed from the support portion 14. In this state, the ball bearings of the second spacer 63 and the third spacer 65 are used. The side surface of 55 on the outer ring 55b side functions as guide surfaces 63a and 65a for guiding the outer ring 55b of the ball bearing 55 in the radial direction.

When the lid portion 15 is fixed to the support portion 14 with the bolt 60, the first spacer 62 is further press-fitted to the outer ring 55 b side of the ball bearing 55, and the second spacer 63 and the third spacer 65 are in close contact with the ball bearing 55. The outer ring of the ball bearing 55 is sandwiched between the lid portion 15 and the step portion 64 via the first spacer 62, the second spacer 63, and the third spacer 65. The guide surfaces 63a and 65a function as a pressing surface that presses against the outer ring 55b of the ball bearing 55, and the second spacer 63 and the third spacer 65 function as an elastic body that applies an elastic force in the axial direction.

As a result, the ball nut 50, the driven pulley 54, and the rack shaft 20 can be supported in a state where an axial elastic force is applied, and the support rigidity of the rack shaft 20 in the axial direction is increased. Further, since the second spacer 63 and the third spacer 65 are made of rubber, the friction coefficient between the guide surface 63a of the second spacer 63 and the guide surface 65a of the third spacer 65 is high. The frictional force between the guide surface 63a of the spacer 63 and the outer ring 55b and between the guide surface 65a of the third spacer 65 and the outer ring 55b increases, and the support rigidity in the radial direction of the rack shaft 20 increases. An axial elastic force is applied to the ball nut 50, the driven pulley 54, and the rack shaft 20 by the lid portion 15, the first spacer 62, the second spacer 63, the third spacer 65, the step portion 64, and the bolt 60. An elastic holding device 80 is configured.

As shown in FIG. 4, two ring-shaped grooves 66 and 67 are formed on the support surface 61, and O-rings 68 and 69 are fitted into the grooves 66 and 67. These O-rings 68 and 69 elastically support the ball nut 50 in the radial direction so as to fill the gap a.

In FIG. 1, a motor insertion hole 14 a is formed in the support portion 14 in parallel with the support surface 61, and the electric motor 70 is attached to the support portion 14 with the drive shaft 70 a of the electric motor 70 inserted in the motor insertion hole 14 a. It has been. A driving pulley 71 is attached to a driving shaft 70 a of the electric motor 70, and a timing belt 72 is stretched between the driven pulley 54 and the driving pulley 71. The electric motor 70 is attached to the support portion 14 so that the driven pulley 54 and the drive pulley 71 are parallel to each other.

The rack shaft 20 has a round solid part 20c between the rack teeth 20a and the ball screw part 20b, and a sliding bearing 73 is slidably fitted to the round solid part 20c. As shown in FIG. 5, the cylindrical portion 12 is formed with a sliding hole 12b and a large-diameter hole 12c in addition to the insertion hole 12a. As shown in FIG. 6, the sliding hole 12b is formed so that the cross section has a track shape. Has been. That is, the sliding hole 12 b is formed in a shape in which a circle is extended in the same direction as the guide hole 14.

A direction parallel to the guide hole 14 corresponds to a predetermined radial direction in the cylindrical portion 12. Screw holes 12d and 12e are formed in the cylindrical portion 12 on both sides in the radial direction determined with the slide bearing 73 interposed therebetween, and adjusting screws 74 and 75 are screwed into the screw holes 12d and 12e, respectively. Lock nuts 76 and 77 are screwed into the adjusting screws 74 and 75, respectively. The screw holes 12d and 12e are formed in the predetermined radial direction, and the adjusting screws 74 and 75 are screwed to the sliding bearing 73 in the predetermined radial direction. The screw holes 12d and 12e, the adjustment screws 74 and 75, and the lock nuts 76 and 77 constitute an adjustment holding device 78 that moves the slide bearing 73 in a predetermined radial direction and holds it in that position.

In FIG. 5, the large-diameter hole 12c has a press-fitting hole 12f on the sliding hole 12b side, and a slip-off preventing member 79 is press-fitted into the press-fitting hole 12f. The side surface of the sliding hole 12b corresponding to the sliding bearing 73 and the side surface of the slip-off preventing member 79 on the sliding bearing 73 side guide the sliding bearing 73 so that the rack shaft 20 cannot move in the axial direction and can move in a predetermined radial direction. Function as guide surfaces 12g and 79a.

The gear housing 11 is mainly made of an aluminum material, and an insertion hole 12a, a sliding hole 12b, a large-diameter hole 12c, and a press-fitting hole 12f are simultaneously formed when the gear housing 11 is made by a die-cast die. Thereafter, the screw holes 12d and 12e are processed by a threading tap. The cylindrical support surface 61 is processed into a predetermined dimension by cutting.

Next, the assembly operation of the electric power steering apparatus will be described.

The state where the pinion shaft 21, the connecting shaft 30, and the torque sensor 40 are assembled to the gear portion 13 of the gear housing 11 will be described.

A sliding bearing 73 is fitted into the sliding hole 12 b of the cylindrical portion 12 of the gear housing 11, and a slip prevention member 79 is press-fitted into the press-fitting hole 12 f of the cylindrical portion 12 of the gear housing 11. A ball nut 50 is screwed to the ball screw portion 20b of the rack shaft 20 in a separate assembly line, and a collar 52, a driven pulley 54, a ball bearing 55, and a nut 56 are assembled to the ball nut 50. The third spacer 65 is fitted into the support surface 61 of the support portion 14 of the gear housing 11, and the O-rings 68 and 69 are fitted into the grooves 66 and 67. In this state, the rack shaft 20 in which the ball nut 50, the collar 52, the driven pulley 54, the ball bearing 55, and the nut 56 are assembled is inserted into the insertion hole 12a of the cylindrical portion 12 of the gear housing 11, and further The slide bearing 73 and the large-diameter hole 12 c are inserted, and the rack teeth 20 a of the rack shaft 20 are engaged with the pinion teeth 21 a of the pinion shaft 21. Further, the outer ring of the ball bearing 55 is fitted into the support surface 61 of the support portion 14 of the gear housing 11, and at this time, the O-rings 68 and 69 are elastically deformed radially outward and the O-rings 68 and 69 are inserted into the O-rings 68 and 69. Fit the outer ring.

Next, the first spacer 62 is fitted into the support surface 61 of the support portion 14 of the gear housing 11, the second spacer 63 is press-fitted into the support surface 61, and the second spacer 63 and the ball bearing 55 are removed from the support portion 14. Temporarily fix so that there is no. However, the first spacer 62 is pressed into the support surface 61 to such an extent that the ball bearing 55 can move in the radial direction. A timing belt 72 is put on the driven pulley 52.

A drive pulley 71 is attached in advance to the drive shaft 70a of the electric motor 70 in another assembly line. The drive shaft 70a and the drive pulley 71 are inserted into the motor insertion hole 14a, and the timing belt 72 is put on the drive pulley 71. The electric motor 70 is fixed to the support portion 14 with bolts.

The adjustment screws 74 and 75 are screwed into the screw holes 12d and 12e, and then only the adjustment screw 74 is screwed in the direction of arrow F until the optimum belt tension is applied to the timing belt 72. By this operation, the slide bearing 73 is guided by the guide surface 12g of the slide hole 12b and the guide surface 79a of the slip-off preventing member 79 and moves in a predetermined radial direction (arrow F direction) parallel to the guide hole 14 and the rack. The rack shaft 20 is tilted with the meshing point of the teeth 20a and the pinion teeth 21a as a fulcrum, and the ball nut 50, the collar 52, the driven pulley 54, the ball bearing 55, and the nut 56 are also connected to the guide surface 63a of the second spacer 63 and the third It is guided by the guide surface 65a of the spacer 65 and moves in a predetermined radial direction. That is, in FIG. 3, the driven pulley 54 moves in the direction of arrow F, the distance between the axis P of the drive pulley 71 and the axis Q of the driven pulley 54 increases, the timing belt 72 is extended, and the belt tension is applied to the drive pulley 71. And the driven pulley 54.

In order to hold the belt tension, the adjustment screw 75 is screwed to bring the tip of the adjustment screw 74 into contact with the slide bearing 73, and the lock nuts 76 and 77 are screwed to the adjustment screws 74 and 75. , 77 is brought into contact with the cylindrical portion 12. Next, the lid portion 15 is fixed to the support portion 14 with a bolt 60. By fixing the bolt 60, the outer ring of the ball bearing 55 is sandwiched between the lid part 15 and the step part 64 via the first spacer 62, the second spacer 63, and the third spacer 64, and the outer ring 55b of the ball bearing 55 is The guide surface 63a of the second spacer 63 and the guide surface 65a of the third spacer 65 are elastically sandwiched.

Next, the operation of the electric power steering device will be described. When the driver rotates the handle, the rotation of the handle is transmitted to the pinion shaft 20 via the connecting shaft 30 and the torsion bar 33, and the rotation of the pinion shaft 20 by the rack teeth 20a and the pinion teeth 21a is the axis of the rack shaft 20. Converted to directional movement. When rotational torque is generated, the torsion bar 33 is twisted and relative rotation occurs between the connecting shaft 30 and the pinion shaft 20. When this relative rotation is detected by the torque sensor 40, the electric motor 70 is activated, and the force of the electric motor 70 is transmitted to the drive pulley 71, the timing belt 72, the driven pulley 52, the ball nut 50, and the rack shaft 20. As a result, the electric motor 70 assists in the direction in which the driver wants to turn the steering wheel. The external force applied from the wheel to the rack shaft 20 is mainly received by the pinion shaft 21 and the rack guide 24 and simultaneously received by the sliding bearing 73. The external force applied to the rack shaft 20 is supplementarily received by the elastic force of the second spacer 63, the third spacer 65, and the O-rings 68 and 69.

The present invention is not limited to these embodiments, and can of course be implemented in various modes without departing from the gist of the present invention.

In the above-described embodiment, the driven pulley is used as the driven rotator and the driving pulley is used as the driving rotator. However, the driven gear is used as the driven rotator, and the driving gear is used as the driving rotator. May be. In this case, the driven gear and the drive gear mesh with each other, and the force of the electric motor is transmitted to the ball nut through the drive gear and the driven gear. By optimizing the inter-shaft distance between the driven gear and the drive gear, it is possible to reduce the noise and vibration caused by the meshing between the gears, and to reduce backlash in the rotational direction of the gear.

11: gear housing, 12: cylindrical portion, 12g: guide surface, 20: rack shaft, 20a: rack teeth, 20b: ball screw portion, 21: pinion shaft, 21a: pinion teeth, 50: ball nut, 54: driven pulley ( Driven rotor), 55: ball bearing, 63: second spacer, 63a: guide surface, 65: third spacer, 65a: guide surface, 70: electric motor, 70a: drive shaft, 71: drive pulley (drive) Rotating body), 72: Timing belt, 73: Sliding bearing, 74: Adjustment screw, 75: Adjustment screw, 76: Lock nut, 77: Lock nut, 78: Adjustment holding device, 79: Preventing member, 79a: Guide surface 80: Elastic holding device

Claims (8)

A rack shaft is inserted into the gear housing so as to be movable in the axial direction, a rack tooth is formed on one end side of the rack shaft, a ball screw portion is formed on the other end side, and a pinion shaft is formed to mesh with the rack teeth. Is rotatably supported on the gear housing about an axis intersecting the rack shaft, and a ball nut meshing with the ball screw portion and a driven rotating body rotating integrally therewith are rotatably supported on the gear housing, and driven. In the electric power steering apparatus in which the drive rotating body that transmits the rotation with the rotating body and rotates about the axis parallel to the rotating body is rotationally connected to the drive shaft of the electric motor, and the electric motor is attached to the gear housing.
The ball nut and the driven rotating body are provided so as to be movable in a radial direction so that a distance between the driven rotating body and the driving rotating body of the gear housing changes, and the rack shaft is slidably guided and supported. An electric power steering device, wherein a sliding bearing is provided in the gear housing so as to be movable in the radial direction, and an adjustment holding device is provided in the gear housing for moving the sliding bearing in the radial direction and holding the sliding bearing in its position. The electric power steering apparatus according to claim 1, wherein
An electric power steering apparatus, wherein the driven rotating body is a driven pulley, the driving rotating body is a driving pulley, and a timing belt is stretched between the driven pulley and the driving pulley. The electric power steering apparatus according to claim 1, wherein
An electric power steering apparatus, wherein the driven rotator is a driven gear, the drive rotator is a drive gear, and the driven gear and the drive gear mesh with each other. In the electric power steering device according to claim 1, 2, 3,
An electric power steering device characterized in that a guide surface is provided in the gear housing for guiding and supporting the sliding bearing so as to be movable in the radial direction. In the electric power steering device according to claim 1, 2, 3,
The electric power steering device according to claim 1, wherein the adjusting and holding device is a pair of adjusting screws that are screwed into the gear housing on both sides of the sliding bearing and abut against the sliding bearing so as to be able to advance and retract. The electric power steering apparatus according to claim 1, wherein
In order to rotatably support the ball nut on the gear housing, a rolling bearing is disposed between the ball nut and the gear housing, and the rolling bearing is attached to the ball nut and the inner ring attached to the ball nut so as not to move in the axial direction. An outer ring to be fitted and a rolling element that rolls between an inner ring and an outer ring, and the outer ring is arranged in the gear housing in the radial direction so that the ball nut and the driven rotating body are provided in the gear housing so as to be movable in the radial direction. An electric power steering device characterized in that a guide surface for guiding is provided. The electric power steering apparatus according to claim 6,
An electric power steering apparatus according to claim 1, wherein an elastic holding device is provided in the gear housing for holding the guide surface in a state where an axial elastic force is applied to the outer ring after adjustment of the radial movement of the outer ring. The electric power steering apparatus according to claim 7,
2. An electric power steering apparatus according to claim 1, wherein a rubber spacer is disposed on both axial sides of the outer ring as the elastic holding device, and a guide surface is formed on the outer ring side of the spacer.

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