JP2012081945A - Steering device - Google Patents

Abstract

Provided is a steering device that allows a driver to detect that a roller bearing is in a replacement period when an excessive input is input to a roller bearing of the steering device to generate an indentation.
An outer ring of a roller bearing 17 that rotatably supports the pinion shaft in a rack and pinion type steering device that steers a wheel by transmitting a steering force of a steering shaft to a rack via a pinion shaft pinion 15a. The breaking strength of 17a was made lower than that of the rack, the pinion shaft, and the housing 11 that accommodates them.
[Selection] Figure 3

Description

  The present invention relates to a steering device for a vehicle.

In the gear of a rack and pinion type steering device, the lower side of the pinion is supported by a needle bearing (hereinafter referred to as a roller bearing). If an unexpected excessive input enters the steering gear due to reverse input from the tire, an indentation may be formed in the roller bearing. If indentations are formed on the roller bearing, it may cause a strange feeling during steering or cause abnormal noise. When such a sense of incongruity or noise occurs, it is desirable to replace the roller bearing, but in reality, it is left to the driver's sense, and there is no effective technology.
Patent Document 1 discloses a rolling bearing in which a coloring agent leaks out before the bearing is seized, thereby notifying the malfunction of the bearing.

JP 2007-290447 A

  Therefore, it is an object to provide a steering device that allows the driver to detect that the roller bearing is in the replacement period when an excessive input is input to the roller bearing of the steering device and an indentation is generated.

  In order to solve the above-mentioned problems, the invention according to claim 1 is directed to a rack and pinion type steering device that steers a wheel by transmitting a steering force of a steering shaft to a rack via a pinion of a pinion shaft. The gist is that the fracture strength of the outer ring of the roller bearing that rotatably supports the shaft is lower than that of the rack, the pinion shaft, and the housing that houses them.

  According to the above configuration, indentation is generated in the outer ring of the roller bearing at an input lower than the damage strength of the rack and pinion and the housing with respect to an excessive input, so that the roller before the main part of the steering gear is damaged. Since the impression generated on the bearing generates a sense of incongruity due to a sense of inconvenience, the user can sense when to change the steering gear.

The gist of the invention described in claim 2 is that the surface pressure of the outer ring of the roller bearing is set to 4000 to 6000 MPa and the depth of the impression of the outer ring is set to 1 to 60 μm.
In other words, the outer ring of the roller bearing is more likely to generate indentations than the roller, so that it is possible to reliably generate indentations in the outer ring of the roller bearing in response to excessive input, so that the driver can feel a sense of discomfort and discomfort. Can do.

The gist of the invention described in claim 3 is that the material of the roller of the roller bearing is high carbon steel, the material of the outer ring is SPB, and the hardness is Vickers hardness (Hv) 700-800.
That is, by providing a difference between the material of the outer ring and the internal hardness, it is possible to reliably generate an indentation, so that the driver can feel a sense of crunch.

  As described above, according to the present invention, when an excessive input is input to the roller bearing of the steering device and an indentation is generated, the driver can be notified that the roller bearing is in the replacement period.

Front view of vehicle rack and pinion type steering device Cross section of rack bar support device Enlarged view of the area near the roller bearing Figure showing the relationship between contact pressure and indentation depth Diagram showing the relationship between indentation depth and torque fluctuation

Hereinafter, an embodiment of a steering device of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the vehicle rack and pinion type steering device includes a housing 11, a rack bar 12 (rack), a tie rod 13, a rack guide housing part 14, a pinion shaft 15 (pinion), and a rack bar support device 20. ing.

  The housing 11 extends in the left-right direction (left-right direction in FIG. 1) of the vehicle (not shown) and is assembled to the vehicle. The rack bar 12 is assembled to the housing 11 so as to be slidable in the rack axial direction (left-right direction in FIG. 1).

The base ends of the tie rods 13 are assembled to both ends of the rack bar 12, respectively.
Each other end of the tie rod 13 is connected to each knuckle arm (not shown) of a steering wheel (for example, left and right front wheels). Thereby, since the movement of the rack bar 12 is transmitted to the knuckle arm via the tie rod 13, the vehicle can be steered according to the steering operation.

The rack guide housing part 14 is formed in the housing 11 so as to be orthogonal to the rack bar 12.
As shown in FIG. 2, the rack guide housing part 14 has a receiving hole 14a having a circular cross section. A rack guide 21 is slidably assembled in the accommodation hole 14a.

  The pinion shaft 15 is rotatably assembled to the housing 11 via a ball bearing 16 and a roller bearing 17. The pinion shaft 15 is connected to a steering shaft (not shown). A pinion 15 a is formed on the pinion shaft 15. The pinion 15a is formed with helical teeth and meshes with the rack 12a of the rack bar 12.

A roller bearing 17 is interposed between the outer peripheral surface of one (end portion) of the pinion 15 a of the pinion shaft 15 and the inner peripheral surface of the rack guide housing portion 14, and the pinion shaft 15 is inserted by this roller bearing 17. It is supported only in the radial direction. Further, the other of the pinions 15 a of the pinion shaft 15 is supported in the radial direction by the rack guide housing portion 14 via the ball bearings 16.
As shown in FIG. 3, the roller 17 b of the roller bearing 17 is restricted from axial movement and circumferential movement with respect to the pinion shaft 15. The outer ring 17 a of the roller bearing 17 is accommodated in a bearing holding space formed in the rack guide housing portion 14.

  The rack bar support device 20 includes a rack guide 21, an adjustment screw 24, and a spring 25.

  The adjusting screw 24 is disposed on the back side of the rack guide 21 and closes the accommodation hole 14 a of the rack guide housing portion 14. The adjusting screw 24 is screwed into the opening end of the accommodation hole 14a. The spring 25 is disposed between the rack guide 21 and the adjusting screw 24 in a compressed state, and is accommodated in the back recess 21 a of the rack guide 21. Thereby, the rack guide 21 presses the rack bar 12 against the pinion shaft 15 by the urging force of the spring 25. That is, the rack bar 12 is supported by the rack bar support device 20 so as to be slidable in the rack axis direction while being pressed toward the pinion 15a.

The rack bar 12 is made of a carbon steel material (JIS S45C, etc.), the pinion shaft 15 is made of a heat-hardening material such as a case-hardened steel (JIS SCM420, etc.) or a carbon steel material (JIS S45C, etc.), and the roller bearing 17 is shown in Table 1. As described above, the roller 17b of the roller bearing 17 is made of SUJ2 high carbon bearing steel, and the outer ring 17a is made of SPB material.
Next, the result of measuring the indentation depth between the roller 17b and the outer ring 17a is shown in FIG.

  As shown in FIG. 4, it was found that the indentation increased in proportion to the surface pressure of 4000 MPa or more, and the roller 17b was broken at 7000 MPa or more. Further, as shown in FIG. 5, it has been found that the abnormality can be detected when the torque fluctuation occurs in proportion to the size of the indentation on the outer ring 17a and the indentation is generated.

  Therefore, in the case of the roller bearing 17 shown in Table 1, it is possible to generate a sense of dust by setting the surface pressure in the range of 4000 to 7000 MPa. Therefore, it is possible to make the driver sense the discomfort when the roller bearing 17 is replaced. it can.

  DESCRIPTION OF SYMBOLS 11 ... Housing, 12 ... Rack bar, 13 ... Tie rod, 14 ... Rack guide housing part, 15 ... Pinion shaft, 15a ... Pinion, 16 ... Ball bearing, 17 ... Roller bearing, 17a ... Outer ring, 17b ... Roller, 20 ... Rack Bar support device, 21 ... rack guide, 24 ... adjust screw, 25 ... spring.

Claims (3)

In a rack and pinion type steering device that steers a wheel by transmitting a steering force of a steering shaft to a rack through a pinion of a pinion shaft, the breaking strength of an outer ring of a roller bearing that rotatably supports the pinion shaft is A steering device characterized by being lower than a rack, the pinion shaft, and a housing for housing them. 2. The steering apparatus according to claim 1, wherein the surface pressure of the outer ring of the roller bearing is set to 4000 to 6000 MPa and the depth of the indentation of the outer ring is set to 1 to 60 [mu] m. The steering device according to claim 1 or 2, wherein a material of the roller of the roller bearing is high carbon steel, a material of the outer ring is SPB, and each hardness is Vickers hardness (Hv) 700 to 800.