JP2007001511A - Steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steering device in which a rattle sound is prevented and a steering feeling is improved by eliminating the fit clearance between a shaft body and a roller to pivot the roller of a rolling rack guide. <P>SOLUTION: Crowning is applied to a needle roller 88 which is shaped to be the maximum diameter in the axial length of the central part of the needle roller 88, and to be a curvedly smaller diameter toward both sides. Thereby, even when eliminating the fit clearance between the outside diameter of the needle roller 88 inserted between an outer peripheral surface 83 of the shaft body 83 and the inner peripheral surface 811 of the roller 81, the needle roller 88 can be easily assembled, because the fit clearance is absent only for the central part of the axial length of the needle roller 88. The rattle sound trouble or vibration due to the fit clearance does not occur, and the steering feeling is improved. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a steering apparatus, and more particularly, to a steering apparatus in which a rear surface of a rack shaft of a rack and pinion type steering apparatus is supported by a rolling rack guide.

  As a rack and pinion type steering apparatus having such a rolling rack guide, there is a steering apparatus disclosed in Patent Document 1. 2 and 3 show an electric power steering device of a steering device having such a rolling rack guide, FIG. 2 is a longitudinal sectional view of the electric power steering device, and FIG. 3 is an alternate long and short dash line in FIG. It is an expanded sectional view of a rolling rack guide surrounded by a circle.

  In the pinion assist type electric power steering apparatus shown in FIGS. 2 and 3, the lower end portion of the pinion shaft 1 is pivotally supported by a four-point contact ball bearing 21, and the male screw 11 at the lower end portion of the pinion shaft 1 is attached to the pinion shaft 1. The lock nut 22 is screwed. The lock nut 22 fixes the lower end of the pinion shaft 1 to the inner ring of the ball bearing 21.

  The outer ring of the ball bearing 21 is press-fitted into a bearing hole 32 formed in the lower housing 31. The outer ring of the ball bearing 21 is pressed by the end cover 23 screwed into the female screw 33 formed on the opening side of the bearing hole 32, and the ball bearing 21 is fixed to the lower housing 31. Thus, the pinion shaft 1 is fixedly supported by the lower housing 31 in the thrust direction and the radial direction by the ball bearing 21.

  A cored bar 43 of a worm wheel 42 that meshes with a worm 41 of the worm reduction mechanism 4 is press-fitted into the upper end portion of the pinion shaft 1. The worm 41 is connected to an output shaft of a steering assist electric motor (not shown). The pinion shaft 1 is supported only in the radial direction by a ball bearing 24 immediately below the worm wheel 42.

  An input shaft 5 connected to a steering wheel via a steering shaft (not shown) is rotatably supported by a ball bearing 25 on an upper housing 34 fixed to the upper end surface of the lower housing 31 with a bolt (not shown). . The torsion bar 52, whose upper end is connected to the input shaft 5 by a pin 51, has its lower end pivotally supported on the lower end of the input shaft 5 by a bush 53, and is press-fitted into the upper end of the pinion shaft 1 below the bush 53. It is connected by.

  The torque sensor 6 that detects torque acting on the torsion bar 52 includes a sensor shaft portion 61, detection coils 62 and 63, and a cylindrical member 64. The sensor shaft portion 61 is formed at the lower end of the input shaft 5, and the detection coils 62 and 63 are disposed inside a yoke 65 press-fitted inside the upper housing 34. The cylindrical member 64 is disposed between the sensor shaft portion 61 and the detection coils 62 and 63. The cylindrical member 64 is fixed to the upper end of the pinion shaft 1, and a plurality of ridges extending in the axial direction are formed at equal intervals in the circumferential direction on the sensor shaft portion 61. The cylindrical member 64 is formed with a plurality of rectangular windows at equal intervals in the circumferential direction at positions facing the detection coils 62 and 63.

  When the input shaft 5 rotates by operating the steering wheel, the rotational force is transmitted to the pinion shaft 1 via the torsion bar 52. At this time, the torsion bar 52 that connects the input shaft 5 and the pinion shaft 1 is twisted due to the resistance on the steering wheel side, and relative rotation occurs between the protrusion on the surface of the sensor shaft portion 61 and the window of the cylindrical member 64. .

  Due to this relative rotation, the magnetic flux generated in the sensor shaft portion 61 is increased or decreased. The increase and decrease in the magnetic flux is detected by the detection coils 62 and 63 as a change in inductance, and the torque acting on the torsion bar 52 is detected. Driven to rotate the worm 41 with a required steering assist force. The rotation of the worm 41 is transmitted to the rack shaft 7 through the worm wheel 42, the pinion shaft 1, and the pinion 12, and changes the direction of the steered wheels through a tie rod (steering device) (not shown) connected to the rack shaft 7. .

  As shown in FIGS. 2 and 3, in the rolling rack guide 8, the roller 81 is pressed against the outer peripheral surface 72 on the back side of the rack teeth 71 of the rack shaft 7 by an adjustment cover 82. The roller 81 is rotatably supported on a cylindrical shaft 83 by a plurality of needle rollers 84. The shaft 83 is accommodated in the groove 851 of the cylindrical holder 85. The needle roller 84 is inserted between the outer peripheral surface 831 of the shaft body 83 and the inner peripheral surface 811 of the roller 81 so as to be able to roll.

  A guide hole 35 having a circular cross section is formed in the lower housing 31, and a holder 85 is fitted into the guide hole 35 so as to be slidable in the left-right direction in FIGS. A female screw 351 is formed in the opening on the left side of the guide hole 35, and a male screw 821 formed on the outer periphery of the adjustment cover 82 is screwed into the female screw 351. The adjustment cover 82 is rotated to adjust the screwing distance appropriately, and the adjustment cover 82 is prevented from loosening with the lock nut 87, so that the holder 85 is pressed against the rack shaft 7 via the disc spring 86. A roller 81 is pressed against the outer peripheral surface 72. Thereby, the backlash of the meshing part between the pinion 12 and the rack shaft 7 is eliminated, and the rack shaft 7 moves smoothly.

  The conventional rolling rack guide 8 described above has a cylindrical shape in which the outer diameter of the needle roller 84 is constant over the entire length in the axial direction. Therefore, in order to fit the needle roller 84 between the outer peripheral surface 831 of the shaft body 83 and the inner peripheral surface 811 of the roller 81 without a gap, the outer diameter of the outer peripheral surface 831 of the shaft body 83, the roller 81 Processing accuracy of the inner diameter of the inner peripheral surface 811 and the outer diameter of the needle roller 84 must be increased, and an increase in manufacturing cost is inevitable.

  Further, in order to fit the needle roller 84 with no gap, it becomes difficult to assemble, so the outer diameter of the needle roller 84 inserted between the outer peripheral surface 831 of the shaft body 83 and the inner peripheral surface 811 of the roller 81 There is a problem that a fitting gap is easily formed between the two, and this fitting gap causes a rattle noise to make the driver uncomfortable, or a vibration occurs and the steering feeling is lowered. It was.

Japanese Utility Model Publication No. 61-18976

  It is an object of the present invention to provide a steering apparatus that eliminates a fitting gap between a shaft body that supports a roller of a rolling rack guide, prevents rattle noise, and improves steering feeling. Let it be an issue.

  The above problem is solved by the following means. That is, the first invention is a housing, a rack shaft supported by the housing so as to be reciprocable, coupled to a steering device, coupled to a steering wheel, meshed with rack teeth of the rack shaft, and A pinion that transmits rotation to the rack shaft, a roller that is in rolling contact with the outer peripheral surface of the rack teeth on the back side of the rack shaft and presses the rack teeth of the rack shaft against the pinion, and a shaft body that rotatably supports the roller, A plurality of rollers provided so as to be able to roll between the outer peripheral surface of the shaft body and the inner peripheral surface of the roller, and provided with a crowning formed on the outer peripheral surface of the roller and having both ends in the axial direction having a small diameter. A steering apparatus characterized by the above.

  A second aspect of the steering apparatus according to the first aspect of the present invention is the steering apparatus according to the first aspect, further comprising a power steering device that reduces the steering force by applying auxiliary power to the steering force applied to the steering wheel. Device.

  In the steering device of the present invention, the crowning is formed on the outer peripheral surface of the roller so that both ends in the axial direction of the roller have a small diameter. Therefore, the assembly can be easily performed even without a fitting gap, and between the shaft body where the roller is pivotally supported. Therefore, the generation of rattle noise can be prevented and the steering feeling can be improved.

  Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1A is an enlarged cross-sectional view of a rolling rack guide according to an embodiment of the present invention. FIG. 1 (2) is an enlarged view of the needle roller. In the following description, the same parts as those in the prior art are denoted by the same reference numerals, and redundant description is omitted.

  As shown in FIG. 1, in the rolling rack guide 8 according to the embodiment of the present invention, a roller 81 is pressed against an outer peripheral surface 72 on the back side of the rack teeth 71 of the rack shaft 7 by an adjustment cover 82. The roller 81 is rotatably supported on a cylindrical shaft 83 by a plurality of needle rollers 88. The shaft 83 is accommodated in the groove 851 of the cylindrical holder 85. The needle roller 88 is inserted between the outer peripheral surface 831 of the shaft body 83 and the inner peripheral surface 811 of the roller 81 so as to be able to roll.

  A guide hole 35 having a circular cross section is formed in the lower housing 31, and a holder 85 is fitted into the guide hole 35 so as to be slidable in the left-right direction in FIG. A female screw 351 is formed in the left opening of the guide hole 35, and a male screw 821 formed on the outer periphery of the adjustment cover 82 is screwed into the female screw 351.

  The adjustment cover 82 is rotated to adjust the screwing distance appropriately, and the adjustment cover 82 is prevented from loosening with a lock nut 87, so that the holder 85 is pressed against the rack shaft 7 via the disc spring 86, and the rack shaft 7 A roller 81 is pressed against the outer peripheral surface 72. As shown in FIG. 1 (2), the needle roller 88 according to the embodiment of the present invention has a shape in which the central part of the axial length of the needle roller 88 has a maximum diameter and becomes a small diameter in a curved manner toward both ends. The crowning is given.

  Thereby, even if there is no fitting gap between the outer diameter of the needle roller 88 inserted between the outer peripheral surface 831 of the shaft body 83 and the inner peripheral surface 811 of the roller 81, the axial direction of the needle roller 88 is reduced. Since only the center part of the length is in a state where there is no fitting gap, it can be easily assembled, and there is no rattle noise or vibration caused by the fitting gap, and the steering feeling is improved.

  In the above embodiment, the crowning of the needle roller 88 is a full crowning shape in which the central portion of the axial length has the maximum diameter and becomes a small diameter in a curved manner toward both ends, but only a narrow region at both ends. A trapezoidal crowning shape having a smaller diameter at the front end and a predetermined area in the central portion of the axial length having a constant diameter may be used.

(1) is an enlarged sectional view of a rolling rack guide according to an embodiment of the present invention, and (2) is an enlarged view of a needle roller. It is a longitudinal cross-sectional view of an electric power steering apparatus having a conventional rolling rack guide. FIG. 3 is an enlarged sectional view of a rolling rack guide surrounded by a one-dot chain line circle in FIG. 2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pinion shaft 11 Male screw 12 Pinion 21 Ball bearing 22 Lock nut 23 End cover 24 Ball bearing 25 Ball bearing 31 Lower housing 32 Bearing hole 33 Female screw 34 Upper housing 35 Guide hole 351 Female screw 4 Worm speed reduction mechanism 41 Worm 42 Worm wheel 43 Core Bar 5 Input Shaft 51 Pin 52 Torsion Bar 53 Bush 6 Torque Sensor 61 Sensor Shaft 62, 63 Detection Coil 64 Cylindrical Member 65 Yoke 7 Rack Shaft 71 Rack Teeth 72 Outer Peripheral Surface 8 Rolling Rack Guide 81 Roller 811 Inner Peripheral Surface 82 Adjust cover 821 Male thread 83 Shaft body 831 Outer peripheral surface 84 Needle roller 85 Holder 851 Groove 86 Belleville spring 87 Lock nut 88 Needle roller

Claims (2)

housing,
A rack shaft supported by the housing so as to be reciprocally movable and coupled to a steering device;
A pinion connected to the steering wheel and meshing with the rack teeth of the rack shaft to transmit the rotation of the steering wheel to the rack shaft;
A roller that is in rolling contact with the outer peripheral surface of the rack teeth of the rack shaft and presses the rack teeth of the rack shaft against the pinion;
A shaft that rotatably supports the roller;
A plurality of rollers provided in a rollable manner between the outer peripheral surface of the shaft body and the inner peripheral surface of the roller;
A steering device comprising a crowning formed on an outer peripheral surface of the roller and having a small diameter at both axial ends of the roller. The steering apparatus according to claim 1, wherein
A steering apparatus comprising a power steering device that reduces the steering force by applying auxiliary power to the steering force applied to the steering wheel.

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