JP5133736B2 - Power steering device - Google Patents

Description

  The present invention relates to a power steering device such as an electric power steering device and a hydraulic power steering device.

  The power steering apparatus includes a rack and pinion mechanism in which a pinion shaft connected to a steering shaft via a torsion bar is supported by a gear box, and the rack shaft is engaged with the pinion shaft.

  In the electric power steering device, when the steering torque applied to the steering shaft by the steering wheel elastically twists and deforms the torsion bar between the steering shaft and the pinion shaft, the steering torque detection device calculates the steering torque based on the elastic torsion deformation amount. The steering assist force is generated by detecting and driving the electric motor according to the detected steering torque.

  In the hydraulic power steering system, when the steering torque applied to the steering shaft by the steering wheel elastically deforms the torsion bar between the steering shaft and the pinion shaft, the control valve operates on the power cylinder according to the elastic torsional deformation amount. Controls fluid supply and discharge to generate steering assist force.

In the power steering device described in Patent Document 1, a press-fit portion provided at one end of a torsion bar is press-fitted into a press-fit hole provided in a pinion shaft, and then a protrusion provided on an inner peripheral portion of the press-fit hole is caulked and cured. The torsion bar is fixed to the pinion shaft by caulking so as to be pressed against the upper surface of the press-fitting portion of the torsion bar with a tool.
JP-A-9-249141

  The power steering device described in Patent Document 1 presses the protrusion provided on the inner peripheral portion of the press-fit hole of the pinion shaft against the upper surface of the press-fit portion of the torsion bar press-fitted into the press-fit hole. The press-fitting part is controlled to come out from the press-fitting hole of the piston shaft. However, there is no place where the press-fitting portion of the torsion bar is pushed into the press-fitting hole of the pinion shaft, and the torsion bar may be displaced in the axial direction with respect to the pinion shaft.

  In the power steering apparatus, when the torsion bar is displaced in the axial direction with respect to the pinion shaft, the elastic torsional characteristics of the torsion bar vary. As a result, the detected torque of the steering torque detecting device varies in the electric power steering device, and the control amount of the control valve varies in the hydraulic power steering device, resulting in unstable steering assist characteristics.

  In addition, the power steering device described in Patent Document 1 is a product that performs caulking work by inserting a caulking jig into the inner peripheral portion of a narrow press-fitting hole of the pinion shaft, and has poor workability.

  An object of the present invention is to easily connect a torsion bar without shifting in the axial direction with respect to a pinion shaft in a power steering device, and to stabilize steering assist characteristics.

The invention of claim 1 includes a rack and pinion mechanism in which a pinion shaft coupled to a steering shaft via a torsion bar is supported by a gear box, and the rack shaft is engaged with the pinion shaft, and is provided at one end of the torsion bar. The press-fitting portion of the pinion shaft is press-fitted into a press-fitting hole provided in the pinion shaft, the periphery of the press-fitting hole of the pinion shaft is caulked, and the projection of the pinion shaft protruding to the inner periphery of the press-fitting hole is provided in the press-fitting portion of the torsion bar In the power steering device fixed to the groove, the bearing that supports the pinion shaft to the gear box is held by a stopper ring that is engaged around the press-fitting hole of the pinion shaft, and the stopper ring is provided on the pinion shaft. The pinion shaft protrusion protruding to the inner periphery of the press-fitting hole is fixed by crimping around the press-fitting hole. Is obtained so as to be fixed in an annular groove is provided on the part.

The invention of claim 2 includes a rack and pinion mechanism in which a pinion shaft connected to a steering shaft via a torsion bar is supported by a gear box, and the rack shaft is engaged with the pinion shaft, and is provided at one end of the torsion bar. The press-fitting portion of the pinion shaft is press-fitted into a press-fitting hole provided in the pinion shaft, the periphery of the press-fitting hole of the pinion shaft is caulked, and the projection of the pinion shaft protruding to the inner periphery of the press-fitting hole is provided in the press-fitting portion of the torsion bar In the power steering device fixed to the groove, a ring groove is provided around the press-fitting hole of the pinion shaft, and the protrusion of the pinion shaft protruding to the inner periphery of the press-fitting hole by crimping the groove bottom of the ring groove fixed in an annular groove is provided on the press-fit portion of the bar, a bearing for supporting the pinion shaft to the gear box is held by a stopper ring is engaged with the ring groove It is obtained by the.

(Claims 1 and 2 )
(a) The press-fitted portion provided at one end of the torsion bar is press-fitted into the press-fitted hole provided in the pinion shaft, the periphery of the press-fitted hole of the pinion shaft is swaged, and the projection of the pinion shaft protruding to the inner periphery of the press-fitted hole is the torsion It was fixed to the annular groove provided in the press-fitting part of the bar. The protrusion that is crimped from the outer periphery of the pinion shaft and protrudes to the inner periphery is inserted into the entire area in the groove width direction of the annular groove of the press-fitting portion of the torsion bar without gaps. The protrusion of the pinion shaft is the torsion bar. The press-fitting portion of the pinion shaft is prevented from being removed from the press-fitting hole of the pinion shaft, and the push-in is restricted. The torsion bar is coupled to the pinion shaft without shifting in the axial direction, the elastic torsion characteristic of the torsion bar is stabilized, and the steering assist characteristic of the power steering apparatus is stabilized.

  (b) Since the caulking jig performs caulking work from the outer periphery widely open to the outside of the pinion shaft, workability is good.

(Claim 1 )
(c) A stopper ring for holding the pinion shaft bearing in the gear box is caulked and fixed around the press-fitting hole of the pinion shaft, and by this caulking, the protrusion of the pinion shaft protrudes to the inner periphery of the press-fitting hole. Is fixed in an annular groove provided in the press-fitting portion of the torsion bar. Therefore, the stopper ring crimping process for the pinion shaft and the torsion bar crimping process for the pinion shaft can be made into a single process, and the productivity of the power steering apparatus can be improved.

(Claim 2 )
(d) The pinion shaft protrusion protruding to the inner periphery of the press-fitting hole by caulking the groove bottom of the ring groove provided on the pinion shaft is fixed to the annular groove provided in the press-fitting portion of the torsion bar. Accordingly, it is possible to simplify the caulking process by reducing the caulking force of the torsion bar with respect to the pinion shaft. Further, this ring groove can be used as a locking groove for the stopper ring.

  1 is an overall view showing an electric power steering apparatus, FIG. 2 is a sectional view taken along line II-II in FIG. 1, FIG. 3 is a sectional view showing a torsion bar and pinion shaft assembly, and FIG. 4 is a pinion shaft of the torsion bar. FIG. 5 is a schematic diagram showing a press-fitting and fixing process for the pinion shaft of the torsion bar, and FIG. 6 is a schematic diagram showing a modification of the press-fitting and fixing process for the pinion shaft of the torsion bar.

  As shown in FIGS. 1 and 2, the electric power steering apparatus 10 includes a gear box 11 (first to second gear boxes 11 </ b> A to 11 </ b> B) fixed to a vehicle body frame or the like by a bracket (not shown). Then, a pinion shaft 14 is connected to a steering shaft 12 to which a steering wheel is coupled via a torsion bar 13, a pinion 15 is provided on the pinion shaft 14, and a rack shaft 16 having a rack 16 A meshing with the pinion 15 is provided. The first gear box 11A is supported so as to be movable left and right. Both ends of the rack shaft 16 protrude to the left and right of the first housing 11A, and tie rods 17A and 17B are connected to these ends, and the left and right wheels can be steered via the tie rods 17A and 17B by the left and right movement of the rack shaft 16. To. The steering shaft 12 and the pinion shaft 14 are supported by the gear box 11 via bearings 12A, 14A, and 14B.

  As shown in FIG. 2, the electric power steering device 10 inserts a rack guide 20 into a cylinder portion 18 provided in a portion facing the pinion 15 with one end of the rack shaft 16 sandwiched in the first housing 11A. . The rack guide 20 (bush 21) is springed toward the rack shaft 16 by a compression spring 23 supported on the back surface by an adjustment bolt 22 screwed to the cylinder portion 18, and presses the rack 16A of the rack shaft 16 against the pinion 15. The one end of the rack shaft 16 is slidably supported. Reference numeral 24 denotes a lock nut for the bolt 22. The other end of the rack shaft 16 is supported by the first housing 11A by a bearing (not shown).

  In the electric power steering device 10, a steering torque detection device 30 is provided between the steering shaft 12 and the pinion shaft 14. As shown in FIG. 2, the steering torque detection device 30 is provided with two detection coils 31 and 32 surrounding the cylindrical core 33 engaged with the steering shaft 12 and the pinion shaft 14 in the second housing 11B. . The core 33 includes a vertical groove 35 that engages with the guide pin 34 of the pinion shaft 14 so as to be movable only in the axial direction, and includes a spiral groove 37 that engages with the slider pin 36 of the steering shaft 12. As a result, a steering torque applied to the steering wheel is applied to the steering shaft 12, and when a relative displacement in the rotational direction occurs between the steering shaft 12 and the pinion shaft 14 due to elastic torsional deformation of the torsion bar 13, The displacement in the rotational direction of the pinion shaft 14 causes the core 33 to be displaced in the axial direction, and the inductance of the detection coils 31 and 32 due to the magnetic change around the detection coils 31 and 32 due to the displacement of the core 33 changes. . That is, when the core 33 moves to the steering shaft 12 side, the inductance of the detection coil 31 that is closer to the core 33 is increased, and the inductance of the detection coil 32 that is moved away from the core 33 is decreased. Can be detected.

  The electric power steering apparatus 10 has a motor housing 41 of the electric motor 40 interposed at one end side of the first housing 11A. The electric motor 40 includes a stator (not shown) that is incorporated and fixed on the inner periphery of the motor housing 41 and a rotor (not shown) that is rotatably arranged on the inner periphery side of the stator. The rotor has a hollow rotating shaft (not shown) disposed around the rack shaft 16 over the longitudinal direction of the motor housing 41, and a ball nut (not shown) fixed to one end of the rotating shaft is attached to the rack shaft 16. A steel ball is held between a ball screw (not shown) provided. The electric motor 40 converts the rotation of the ball nut into a linear motion of the rack shaft 16 by a ball screw.

Therefore, the electric power steering device 10 operates as follows.
(1) When the steering torque detected by the steering torque detection device 30 is lower than a predetermined value, the steering assist force is unnecessary and the electric motor 40 is not driven.

  (2) Since the steering assist force is required when the steering torque detected by the steering torque detection device 30 exceeds a predetermined value, the electric motor 40 is driven. In the electric motor 40, the stator coil is energized so as to generate a necessary steering assist force, and the rotor is driven to rotate by a magnetic field generated in the stator. The torque generated by the motor 40 is transmitted from the rotor to the ball nut via the rotation shaft, and the rotation of the ball nut is converted into a linear motion of the rack shaft 16 by the ball screw, and applied to the wheels interlocking with the rack shaft 16 as a steering assist force. The

  Hereinafter, the structure for connecting the torsion bar 13 to the pinion shaft 14 without shifting in the axial direction and stabilizing the steering assist characteristic of the electric power steering apparatus 10 will be described in detail. The torsion bar 13 and the pinion shaft 14 are the torsion bar and pinion shaft assembly shown in FIG. 3 in which the torsion bar 13 is press-fitted and fixed to the pinion shaft 14, and the guide pin 34, the bearing 14A, and the stopper ring 14C are assembled to the pinion shaft 14. The solid 50 is assembled in the gear box 11 (first gear box 11A). The inner ring of the bearing 14 </ b> A that supports the pinion shaft 14 on the gear box 11 is held on the pinion shaft 14 by a stopper ring 14 </ b> C that is engaged with the outer periphery of the pinion shaft 14. The stopper ring 14 </ b> C may be an annular body that is continuous over the entire circumference, or a C-shaped ring that is cut at one place in the circumferential direction.

  In the torsion bar and pinion shaft assembly 50, as shown in FIG. 4, a serration-fitted press-fit portion 51 provided at one end of the torsion bar 13 is opened to the upper end side where the guide pin 34 of the pinion shaft 14 is provided. It press-fits into the press-fitting hole 52 following a certain opening 52A. Then, a projecting portion 53 of the pinion shaft 14 that is caulked around the press-fit hole 52 of the pinion shaft 14 and protrudes to the inner periphery of the press-fit hole 52 is provided in the annular intermediate portion of the press-fit portion 51 of the torsion bar 13. It is fixed to the groove 54. The protrusion 53 protrudes radially from a plurality of positions in the circumferential direction on the inner periphery of the press-fitting hole 52, and engages with the full width (substantially full) of the annular groove 54 of the press-fitting part 51. The press-fitting portion 51 of the torsion bar 13 and the press-fitting hole 52 of the pinion shaft 14 provide a firm fixing structure that does not shift both in the vertical direction along the axial direction due to the above-described engagement of the protrusion 53 with the annular groove 54. Is done.

According to the present embodiment, the following operational effects can be obtained.
(a) A press-fit portion 51 provided at one end of the torsion bar 13 is press-fitted into a press-fit hole 52 provided in the pinion shaft 14, and the periphery of the press-fit hole 52 of the pinion shaft 14 is swaged so as to protrude to the inner periphery of the press-fit hole 52. The protrusion 53 of the pinion shaft 14 is fixed to an annular groove 54 provided in the press-fit portion 51 of the torsion bar 13. The protrusion 53 that is crimped from the outer periphery of the pinion shaft 14 and protrudes toward the inner periphery is engaged with the pinion shaft 14 in a substantially entire region in the groove width direction of the annular groove 54 of the press-fitting portion 51 of the torsion bar 13. The protrusion 53 prevents the press-fitting portion 51 of the torsion bar 13 from coming off into the press-fitting hole 52 of the pinion shaft 14 and restricts the push-in. The torsion bar 13 is coupled to the pinion shaft 14 without being displaced in the axial direction, the elastic torsion characteristic of the torsion bar 13 is stabilized, and the steering assist characteristic of the electric power steering device 10 is stabilized.

  (b) The caulking jig performs caulking work from the outer periphery widely open to the outside of the pinion shaft 14, and the workability is good.

The assembly procedure of the torsion bar and pinion shaft assembly 50 is as follows (FIG. 5).
(1) An annular groove 54 is provided in the press-fit portion 51 of the torsion bar 13, and a press-fit hole 52 is provided in the pinion shaft 14. At this time, a ring groove 55 is provided on the outer periphery of the pinion shaft 14 around the press-fitting hole 52 (FIG. 5A).

  (2) The press-fitting portion 51 of the torsion bar 13 is press-fitted into the press-fitting hole 52 of the pinion shaft 14 (FIG. 5B).

  (3) The inner ring of the bearing 14A is inserted into the outer periphery of the pinion shaft 14 (FIG. 5C). At this time, the ring groove 55 is located on the outer periphery of the pinion shaft 14 and immediately below the inner ring of the bearing 14A inserted into the outer periphery of the pinion shaft 14.

  (4) A stopper ring 14C for the inner ring of the bearing 14A is aligned with a ring groove 55 provided around the press-fit hole 52 of the pinion shaft 14. The stopper ring 14C is caulked and fixed in the groove of the ring groove 55 from the outside of the pinion shaft 14 using a caulking jig, and further, the groove bottom of the ring groove 55 is pushed in by this caulking, whereby a press fit hole A protrusion 53 of the pinion shaft 14 projecting radially inward from the inner periphery of 52 is generated, and this protrusion 53 is engaged with the full groove width of the annular groove 54 provided in the press-fit portion 51 of the torsion bar 13. (FIG. 5D). At this time, the caulking jig may fix the entire circumference of the stopper ring 14 </ b> C in the circumferential direction in the ring groove 55. The protrusions 53 can be generated at a plurality of positions in the circumferential direction on the inner periphery of the press-fitting hole 52 by pressing the groove bottom 55.

  According to the above (1) to (4), the crimping process of the stopper ring 14C with respect to the pinion shaft 14 and the crimping process of the torsion bar 13 with respect to the pinion shaft 14 can be made into a single process, and the electric power steering device 10 is produced. Can be improved. However, the ring groove 55 of the above (1) is not essential.

  The assembling procedure of the torsion bar and pinion shaft assembly 50 can be modified as follows (FIG. 6).

  (1) An annular groove 54 is provided in the press-fit portion 51 of the torsion bar 13, and a press-fit hole 52 is provided in the pinion shaft 14. At this time, a ring groove 55 is provided on the outer periphery of the pinion shaft 14 around the press-fitting hole 52 (FIG. 6A).

  (2) The press-fitting portion 51 of the torsion bar 13 is press-fitted into the press-fitting hole 52 of the pinion shaft 14 (FIG. 6B).

  (3) The inner ring of the bearing 14A is inserted into the outer periphery of the pinion shaft 14 (FIG. 6C). At this time, the ring groove 55 is located on the outer periphery of the pinion shaft 14 and immediately below the inner ring of the bearing 14A inserted into the outer periphery of the pinion shaft 14.

  (4) Using a caulking jig from the outside of the pinion shaft 14, the groove bottom of the ring groove 55 provided around the press-fit hole 52 of the pinion shaft 14 is caulked. A protrusion 53 of the pinion shaft 14 protruding in a bulge shape from the circumference in the radial direction is generated, and this protrusion 53 is engaged with the full groove width of the annular groove 54 provided in the press-fit portion 51 of the torsion bar 13 (FIG. 6). (D)). At this time, the caulking jig can push in the groove bottoms at a plurality of positions in the circumferential direction of the ring groove 55 to generate the protrusions 53 at a plurality of circumferential positions on the inner periphery of the press-fit hole 52.

  (5) The stopper ring 14C for the inner ring of the bearing 14A is engaged with the ring groove 55 (FIG. 6E).

  According to the above (1) to (5), the ring groove 55 is provided in the crimped portion of the torsion bar 13 with respect to the pinion shaft 14 and the thickness of the crimped portion is reduced. The caulking process can be simplified by reducing the tightening force. The ring groove 55 can be used as a locking groove for the stopper ring 14C.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration of the present invention is not limited to this embodiment, and even if there is a design change or the like without departing from the gist of the present invention. It is included in the present invention. For example, the present invention can be applied to a hydraulic power steering apparatus.

FIG. 1 is an overall view showing an electric power steering apparatus. FIG. 2 is a sectional view taken along line II-II in FIG. FIG. 3 is a cross-sectional view showing the torsion bar and pinion shaft assembly. FIG. 4 is a cross-sectional view showing a press-fit fixing structure for the pinion shaft of the torsion bar. FIG. 5 is a schematic diagram showing a press-fitting and fixing process for the pinion shaft of the torsion bar. FIG. 6 is a schematic diagram showing a modification of the press-fitting and fixing process with respect to the pinion shaft of the torsion bar.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Electric power steering apparatus 11 Gear box 12 Steering shaft 13 Torsion bar 14 Pinion shaft 14A Bearing 14C Stopper ring 16 Rack shaft 51 Press-fit part 52 Press-fit hole 53 Projection part 54 Annular groove 55 Ring groove

Claims (2)

A rack and pinion mechanism in which a pinion shaft connected to a steering shaft via a torsion bar is supported by a gear box, and the rack shaft is engaged with the pinion shaft ,
The press-fitting part provided at one end of the torsion bar is press-fitted into the press-fitting hole provided in the pinion shaft, the periphery of the press-fitting hole of the pinion shaft is swaged, and the protrusion of the pinion shaft protruding into the inner periphery of the press-fitting hole is the press-fitting of the torsion bar In the power steering device fixed to the annular groove provided in the part ,
The bearing that supports the pinion shaft in the gear box is held by a stopper ring that is engaged around the press-fitting hole of the pinion shaft,
The stopper ring is fixed by caulking around the press-fitting hole of the pinion shaft, and the pinion shaft protrusion protruding to the inner periphery of the press-fitting hole is fixed to the annular groove provided in the press-fitting portion of the torsion bar. power steering apparatus characterized by being. A rack and pinion mechanism in which a pinion shaft connected to a steering shaft via a torsion bar is supported by a gear box, and the rack shaft is engaged with the pinion shaft,
The press-fitting part provided at one end of the torsion bar is press-fitted into the press-fitting hole provided in the pinion shaft, the periphery of the press-fitting hole of the pinion shaft is swaged, and the protrusion of the pinion shaft protruding into the inner periphery of the press-fitting hole is the press-fitting of the torsion bar In the power steering device fixed to the annular groove provided in the part,
An annular groove in which a ring groove is provided around the press-fitting hole of the pinion shaft, and a protrusion of the pinion shaft protruding to the inner periphery of the press-fitting hole by caulking the groove bottom of the ring groove is provided in the press-fitting portion of the torsion bar Fixed to
A power steering device characterized in that a bearing for supporting the pinion shaft on a gear box is held by a stopper ring engaged with the ring groove.

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