JP2006182048A - Electric power steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To joint a second housing to a first housing without attaching a flange. <P>SOLUTION: This device includes a rotating shaft 4 which moves in a longitudinal direction of the shaft in accordance with a steering operation, a driving gear 10 interlocked with an output shaft 5a of an electric motor 5, a rotating sleeve 12 disposed around the outside of a spiral groove 4b of the rotating shaft 4 and has a driven gear 11 engaged with the driving gear 10, a first housing 7 which supports the rotating sleeve 12 so as to be rotated freely, a second housing 8 which rotatably supports the driving gear 10 and to which the electric motor 5 is attached, a bolt 18 which joints the second housing 8 to the first housing 7, and a power conversion mechanism A which converts a rotating force of the rotating sleeve 12 into a moving force of the rotating shaft 4 in the longitudinal direction of the shaft to transmit it to the rotating shaft 4. The bolt 18 is disposed in the second housing 8. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electric power steering apparatus that transmits a rotational force of an electric motor used as a generation source of a steering assist force to a steered shaft and moves the steered shaft in the axial length direction to assist steering.

  An electric power steering apparatus for a vehicle has a spiral groove and a steering shaft that moves in the axial length direction in response to a steering operation, and a steering wheel that is arranged so that an output shaft intersects the axis of the steering shaft. An auxiliary electric motor; a drive gear linked to the output shaft via a drive shaft; a rotary cylinder having a driven gear arranged around the spiral groove and meshing with the drive gear; and the rotation A cylindrical first housing that rotatably accommodates and supports the cylinder, a cylindrical second housing that rotatably supports the drive gear and to which the electric motor is attached, and the second housing that is the first housing. A bolt coupled to the housing, and a power conversion mechanism that converts the rotational force of the rotating cylinder into a moving force in the axial length direction of the steered shaft and transmits it to the steered shaft (for example, Patent Document 1). .)

  On one side of the first housing, a pedestal portion having a support hole penetrating in a direction intersecting with the axis of the steered shaft is projected, and two first flanges having a first screw hole project on the pedestal portion. It is installed.

  The second housing has a small tube portion that accommodates and supports the drive gear and the drive shaft, and a large tube portion that is connected to the small tube portion and to which a motor case of the electric motor is attached. Two second flanges provided with first through holes corresponding to the screw holes of the first flange are protruded on one side in the longitudinal direction, and the second screw holes are provided on the other side in the longitudinal direction of the large tube portion. Two third flanges having protrusions are provided.

In the electric motor, two fourth flanges provided with second through holes corresponding to the second screw holes project from a motor case that accommodates and supports the rotor and the stator.
The second housing is coupled to the first housing by tightening a bolt inserted into the first through hole into the first screw hole, and the motor is tightened into the second screw hole by tightening the bolt inserted into the second through hole. A case is coupled to the second housing.
JP 2004-175239 A

  However, in the electric power steering apparatus configured as described above, the first flange and the second flange for coupling the second housing to the first housing are projected outward, and further, the electric motor A third flange and a fourth flange for mounting and mounting the second housing on the second housing protrude from the outside, and the first flange and the second flange, and the third flange and the fourth flange are axes of the output shaft. The second housing is disposed at a position that is not opposed to the direction, in other words, at a position displaced from each other in the circumferential direction of the output shaft, and can be coupled to the first housing without being obstructed by the third flange. As a result, the number of flanges projecting outside the second housing increases, and the entire electric power steering apparatus becomes large. Will be installed is impaired, improvement has been desired.

  The present invention has been made in view of such circumstances, and an object thereof is to provide an electric power steering apparatus capable of coupling the second housing to the first housing without providing a flange.

  An electric power steering device according to a first aspect of the present invention includes a steered shaft that has a spiral groove and moves in the axial length direction in response to a steering operation, a drive gear that is interlocked with an output shaft of an electric motor, and the spiral A rotating cylinder having a driven gear disposed around the groove and meshing with the driving gear; a first housing that rotatably supports the rotating cylinder; and the electric gear that rotatably supports the driving gear. A second housing to be attached, a coupling member that couples the second housing to the first housing, and a rotational force of the rotating cylinder is converted into a moving force in the axial length direction of the steered shaft to convert the rolling shaft. In the electric power steering apparatus including a power conversion mechanism for transmitting to the rudder shaft, the coupling member is disposed in the second housing.

  In the electric power steering apparatus according to a second aspect of the present invention, the second housing connects the small tube portion that accommodates and supports the drive gear, the large tube portion to which the electric motor is attached, the small tube portion and the large tube portion, A connecting portion provided with a plurality of through holes, the first housing has a screw hole corresponding to the through hole, and the coupling member is screwed into the screw hole. It is characterized by.

  The electric power steering apparatus according to a third aspect of the present invention is characterized in that the first housing has a fitting hole into which the small tube portion is loosely fitted.

  According to the first invention, since the coupling member that couples the second housing to the first housing is disposed in the second housing, the flange for coupling the second housing to the first housing can be eliminated. . Therefore, the periphery of the second housing can be reduced in size, and thus the entire electric power steering apparatus can be reduced in size, and the mountability on the vehicle can be improved.

  According to the second invention, the connecting member is inserted into the through hole provided in the connecting portion that connects the small tube portion and the large tube portion of the second housing, and the connecting member is screwed into the screw hole of the first housing. Thus, the second housing can be coupled. Accordingly, a bolt can be used as the connecting member, and the second housing can be easily coupled by tightening the bolt.

  According to the third invention, the small cylinder portion of the second housing is loosely inserted into the insertion hole of the first housing, and the support rigidity of the drive gear by the small cylinder portion is lowered, so that the meshing portion of the drive gear and the driven gear When a load is applied, the teeth of the drive gear and the driven gear and the small cylinder portion are bent, and an appropriate tooth contact can be obtained, and the occurrence of abnormal sliding noise can be improved.

Hereinafter, the present invention will be described in detail with reference to the drawings showing embodiments thereof.
Embodiment 1
FIG. 1 is a schematic diagram showing the overall configuration of an electric power steering apparatus according to the present invention, FIGS. 2 and 3 are enlarged sectional views showing the configuration of essential parts, and FIG. 4 is a side view of the electric motor side.

  The electric power steering apparatus shown in FIGS. 1 to 4 has one end connected to a steering wheel via a universal joint 1 and a steering shaft 2 and meshes with a transmission shaft 3 having a pinion 3a at the other end and the pinion 3a. The rack teeth 4a and the rack teeth 4a and the spiral grooves 4b at positions separated from the rack teeth 4a in the axial length direction, and the output shaft 5a of the steered shaft 4 can be moved in the axial length direction. A steering assisting electric motor 5 disposed so as to intersect the axis, a drive gear 10 linked to the output shaft 5a via the drive shaft 6, and a periphery of the spiral groove 4b. A rotating cylinder 12 having a driven gear 11 that meshes with the rotating cylinder 12, a cylindrical first housing 7 that rotatably accommodates and supports the rotating cylinder 12, a driving shaft 6 and a driving gear 10 that rotatably support the electric motor 5 Is attached It has a cylindrical second housing 8 and a ball 13 as an engaging body that engages with the spiral groove 4b. The rotational force of the rotating cylinder 12 is converted into a moving force in the axial length direction of the steered shaft 4, and the rolling is performed. And a power conversion mechanism A for transmitting to the rudder shaft 4.

  The power conversion mechanism A includes a female screw 12a provided inside the rotary cylinder 12 corresponding to the spiral groove 4b, a plurality of balls 13 engaged with the female screw 12a and the spiral groove 4b, and a female screw 12a of the rotary cylinder 12. Two circulation holes (not shown) penetrating in a radial direction at a facing position, and a circulator 14 for circulating a plurality of balls 13 between the two circulation holes. A circulator 14 is attached to the outer periphery of the rotating cylinder 12 by a holder 15.

  The first housing 7 is coupled to the second housing 8, and includes a first cylinder 71 having a first shaft support portion 7 a that supports the rack tooth 4 a side of the steered shaft 4, and the first cylinder 71. And a second cylinder 72 having a second shaft support portion 7b that is connected by a connecting means such as a bolt and supports the spiral groove 4b side of the steered shaft 4.

  The connecting side of the first cylinder 71 with the second cylinder 72 includes a housing part 7d that houses and supports the rotating cylinder 12 and a support part 7e that has a support hole 7d that penetrates in the direction intersecting the axis of the turning shaft 4. The non-connecting side of the first cylinder 71 has a first shaft support portion 7a and a first attachment portion 7f attached to the vehicle body. Rolling bearings 16 and 26 that support both end portions of the rotary cylinder 12 are fitted on both sides in the longitudinal direction of the accommodating portion 7c, and two circumferential positions of the pedestal portion 7e correspond to first through holes 8d described later. Two first screw holes 7g are provided.

  The second cylindrical body 72 is formed to have a relatively short length, and a sliding bearing as a second shaft support portion 7b is fitted and fixed on the inner side. The second mounting is attached to the vehicle body on the outer side. A portion 7h is provided.

  The second housing 8 is fitted and supported in the support hole 7d, and the small cylinder portion 8a for accommodating and supporting the drive gear 10 composed of the drive shaft 6 and the bevel gear via the rolling bearings 17 and 17 and the electric motor 5 are attached. It has a large tube portion 8b and a disk-shaped connecting portion 8c that connects the small tube portion 8a and the large tube portion 8b, and corresponds to the first screw hole 7g at two locations in the circumferential direction of the connecting portion 8c. A first through hole 8d is provided, and a bolt 18 as a coupling member is inserted into the through hole 8d, and the second housing 8 is coupled by screwing the bolt 18 into the first screw hole 7g. Has been. In addition, two first flanges 8f having second screw holes 8e protrude from two locations in the circumferential direction on the opposite side to the small tube portion 8a of the large tube portion 8b.

  The electric motor 5 has a motor case 51, and two second flanges 5c provided with second through holes 5b corresponding to the second screw holes 8e at two circumferential directions of the motor case 51. Is protruded, and a bolt 19 as a connecting member is inserted into the second through-hole 5b, and the bolt 19 is screwed into the second screw hole 8e, whereby the motor case 53 and thus the electric motor 5 are Coupled to the second housing 8.

  The drive gear 10 is formed integrally with the drive shaft 6. The driven gear 11 includes an annular tooth body 11a made of a synthetic resin having teeth on the outer peripheral portion, and a metal annular core body 11b fitted into the annular tooth body 11a. A non-rotating convex portion that prohibits relative rotation with the annular tooth body 11a is provided on the outer peripheral portion of the core body 11b.

  In the electric power steering apparatus configured as described above, when the second housing 8 is coupled to the first housing 7, the drive shaft 6 and the drive gear 10 are supported by the small tube portion 8a via the rolling bearings 17 and 17. The small housing portion 8a of the second housing 8 is fitted into the support hole 7d, and a bolt 18 to be inserted into the first through hole 8d is screwed into the first screw hole 7g to thereby attach the second housing 8 to the first housing. 7 can be combined. When the electric motor 5 is attached to the second housing 8, the motor case 53 is attached to the second housing 8 by screwing the bolt 19 inserted into the second through hole 5b into the second screw hole 8e. Can be worn. In the above configuration, the first through hole 8d is in the second housing 8, and there is no flange projecting outside at the position where the second housing 8 is coupled to the first housing 7, and the electric motor 5 is installed. Since the first and second flanges 8f and 5c project outside only at the attachment location, the periphery of the second housing 8 can be made small, and the entire electric power steering device can be made small, so that it can be mounted on a vehicle. Can be improved.

Embodiment 2
FIG. 5 is an enlarged cross-sectional view showing a configuration of a main part of the second embodiment.
In this electric power steering apparatus, the small cylindrical portion 8a of the second housing 8 fitted and supported in the support hole 7d as the fitting hole has a smaller diameter than the support hole 7d, and a gap is formed between the peripheral surfaces of the support hole 7d and the small cylindrical portion 8a. And the small tube portion 8a is configured to be able to bend in the radial direction.

The electric power steering apparatus in which the electric motor 5 is arranged outside the first housing 7 so that the output shaft 5a intersects the axis of the steered shaft 4 is driven by a load applied to the meshing portion of the drive gear 10 and the driven gear 11. The teeth of the gear 10 and the driven gear 11 and the drive shaft 6 are bent, the tooth contact of the meshing portion is deteriorated, and an abnormal sliding noise is generated. In the second embodiment, the meshing portion Since the teeth of the drive gear 10 and the driven gear 11 and the small tube portion 8a are bent by the applied load, it is possible to maintain an appropriate tooth contact of the meshing portion and improve the occurrence of meshing sliding noise.
Since other configurations and operations are the same as those of the first embodiment, the same components are denoted by the same reference numerals, and detailed description thereof and description of operations and effects are omitted.

  In the embodiment described above, the ball screw mechanism is used as the power conversion mechanism A that converts the rotational force of the output shaft 5a into the moving force in the axial length direction. A plurality of power transmission rings each including an inner ring member having an engaging annular ring portion on its inner peripheral portion and an outer ring member that rotatably holds the outer peripheral portion of the inner ring member via a plurality of balls. A mechanism that is biased with respect to the axis of the steered shaft 4 and is held in the rotary cylinder 12 may be used.

  In addition, the electric power steering apparatus according to the present invention has a configuration in which the electric motor 5 is disposed at a position intersecting the axis of the steered shaft 4, and the electric motor 5 is disposed in parallel with the steered shaft 4. It may be a configuration. In this case, the small gear 7 and the large gear 8 may be spur gears as well as bevel gears.

1 is a schematic diagram showing an overall configuration of an electric power steering apparatus according to the present invention. It is an expanded sectional view showing the composition of the important section of the electric power steering device concerning the present invention. It is an expanded sectional view showing the composition of the important section of the electric power steering device concerning the present invention. It is a side view by the side of the electric motor of the electric power steering apparatus which concerns on this invention. It is an expanded sectional view which shows the structure of the principal part of Embodiment 2 of the electric power steering apparatus which concerns on this invention.

Explanation of symbols

4 Steering shaft 4b Spiral groove 5 Electric motor 5a Output shaft 7 First housing 7d Support hole (insertion hole)
7g First screw hole (screw hole)
8 Second housing 8a Small tube portion 8b Large tube portion 8c Connection portion 8d First through hole (through hole)
DESCRIPTION OF SYMBOLS 10 Drive gear 11 Driven gear 12 Rotating cylinder 18 Bolt (coupling member)
A Power conversion mechanism

Claims (3)

  A steered shaft that has a spiral groove and moves in the axial length direction in response to a steering operation, a drive gear that is interlocked and connected to the output shaft of the electric motor, and the drive gear that is disposed around the outer periphery of the spiral groove. A rotating cylinder having a driven gear meshing with the rotating cylinder; a first housing that rotatably supports the rotating cylinder; a second housing that rotatably supports the driving gear and to which the electric motor is attached; A coupling member that couples the two housings to the first housing, and a power conversion mechanism that converts the rotational force of the rotating cylinder into a moving force in the axial length direction of the steered shaft and transmits it to the steered shaft. In the electric power steering apparatus, the coupling member is disposed in the second housing.   The second housing includes a small cylindrical portion that accommodates and supports the drive gear, a large cylindrical portion to which the electric motor is attached, a small cylindrical portion and a large cylindrical portion, and a connecting portion provided with a plurality of through holes. The electric power steering apparatus according to claim 1, wherein the first housing has a screw hole corresponding to the through hole, and the coupling member is screwed into the screw hole. The electric power steering apparatus according to claim 2, wherein the first housing has a fitting hole into which the small tube portion is loosely fitted.

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