JPH0575058U - Rack shaft of rack and pinion type steering device - Google Patents

Abstract

(57) [Summary] [Purpose] To simplify the manufacturing work of a rack and pinion type steering device using a rack shaft and reduce the cost. Prevents stress on the rack shaft. [Structure] A flat through hole 2 having a horizontal cross section extending in the axial direction is formed to be hollow. A pair of thick-walled portions 3 are formed on both sides in the width direction of the through hole 2 in the peripheral wall, and a pair of thin-walled portions 4 are formed on both sides in the same width direction. The rack 1a is formed on the outer surface of one of the thick portions 3. A screw hole 5 into which the universal joint 15 is screwed is formed at least at one end.
Set the root diameter D of the female thread of the screw hole 5 to the length L of the wide portion of the through hole 2.
Smaller than.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a rack shaft of a rack and pinion type steering device of an automobile or the like, and more particularly to a rack shaft having a circular cross section having a rack that meshes with a pinion of a pinion shaft connected to a steering wheel.

[0002]

[Prior Art]

 FIG. 3 shows a rack and pinion type steering device used in, for example, an automobile and equipped with a conventional rack shaft. In the following description, the left and right sides of FIG.

In FIG. 3, a housing (10) that is long in the left-right direction is fixed to the body of an automobile, and a rack shaft (11) extending in the left-right direction in the housing (10) does not rotate, but the left-right direction. It is supported so as to be movable in the (axial direction). The left and right ends of the rack shaft (11) project from the housing (10). In the gear box (12) formed near the left end of the housing (10), the pinion (14) of the pinion shaft (13) connected to the steering shaft (not shown) is the rack of the rack shaft (11). It meshes with (11a). Tie rods (16) are connected to the left and right ends of the housing (10) via universal joints such as ball joints (15). Dust boots (17) are attached to the housing (10) so as to cover the left and right ends of the rack shaft (11) protruding from the housing (10) and the ends of the tie rods (16).

As shown in FIG. 4, the rack shaft (11) is hollow and has a circular through hole (22) extending in the axial direction, and a flat portion (18) having a predetermined length is formed on the peripheral wall thereof. The rack (11a) is formed on the flat portion (18). In order to form the rack (11a), it is necessary to increase the wall thickness of the flat portion (18), and therefore the flat portion (18) is formed by cold forging. The rack shaft (11) has screw holes (19) in the left and right directions at both ends.The screw holes (19) have internal threads (15a) for the ball joint (15). Is screwed on. A cylindrical part (15c) is interposed between the male screw part (15a) of the ball joint (15) and the joint body part (15b), and this cylindrical part (15c) is attached to the rack shaft (11). It is located outside. In addition, a hole (20) extending from the tip of the external thread (15a) to the cylindrical portion (15c) in the axial direction is formed, and the cylindrical portion (20) is connected to the outer end of the hole (20) in the left-right direction. A hole (21) extending in the radial direction is formed in 15c). The left and right dust boots (17) are communicated with each other through these holes (20) (21) and through holes (22) extending in the axial direction of the rack shaft (11).

In such a configuration, when the driver turns the steering wheel to rotate the steering shaft, this rotation is transmitted to the pinion (14) via the pinion shaft (13) and the pinion (14) is rotated. The rotation causes the rack shaft (11) to move in the left-right direction to steer the wheels. When the rack shaft (11) moves, the air enclosed in the dust boots (17) on the side of the moving direction is trapped in the holes (20) (21) of the ball joint (15) and the rack shaft (11). It flows through the through hole (22) into the other dust boot (17), and as a result, the enclosed air in the dust boot (17) on the moving direction side hinders the movement of the rack shaft (11). It is supposed to be protected.

[0006]

[Problems to be solved by the device]

 However, the conventional rack shaft (11) requires a cold forging process to form the flat portion (18), and a universal joint (15) screwed to both ends of the rack shaft (11) is required. It is necessary to form holes (20) (21) for air circulation. Therefore, there is a problem that the manufacturing work of the steering device provided with the rack shaft (11) is troublesome and the cost becomes high. Moreover, there is a problem that stress is generated on the rack shaft during the cold forging.

An object of the present invention is to provide a rack shaft of a rack and pinion type steering device that solves the above problems.

[0008]

A rack shaft of a rack and pinion type steering device according to the present invention is used in a rack and pinion type steering device and is connected to a tie rod via a universal joint at least one end of which is screwed. At the same time, the rack shaft has a circular cross section having a rack that meshes with the pinion of the pinion shaft connected to the steering wheel. A pair of thick-walled parts is formed on both sides in the narrow width direction of the through hole and a pair of thin-walled parts is formed on both sides in the same width direction, and a rack is formed on the outer surface of either one of the thick-walled parts. At least one end is formed with a screw hole into which the universal joint is screwed. Is what

[0009]

[Action]

 A flat cross-section through hole extending in the axial direction is formed into a hollow shape, and a pair of thick-walled portions are formed on both sides in the narrow direction of the through hole in the peripheral wall, and one on both sides in the same wide direction. When a pair of thin parts is formed and a rack is formed on the outer surface of either one of the thick parts, cooling is performed in order to secure the wall thickness of the flat part for forming the rack as in the conventional case. There is no need for forging. Also, if a screw hole is formed at least at one end and the root diameter of the female thread of the screw hole is smaller than the length of the wide part of the through hole, when the universal joint is screwed into the screw hole, the flat shape Both ends on the wide side of the through hole are not blocked by the male thread of the joint and remain as a space, so the inside and outside of the rack shaft communicate with each other through this portion.

[0010]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings.

1 and 2 show a main part of a rack and pinion type steering device having a rack shaft according to the present invention. In the following description, the same parts and parts as those shown in FIGS. 3 and 4 are designated by the same reference numerals, and the description thereof will be omitted.

The rack shaft (1) passed through the housing (10) has an axially extending flat through hole (2) formed by plastic working or the like. A pair of thick wall portions (3) are formed on both sides of the flat through hole (2) in the peripheral wall of the rack shaft (1) in the narrow direction, and thin wall portions (4) are formed on both sides in the same width direction. Has been formed. A rack (1a) having a predetermined length is formed on the outer surface of the one thick portion (3).

The rack shaft (1) is formed with screw holes (5) in the left and right directions at both ends thereof. The root diameter (D) of the female thread of the screw hole (5) is smaller than the length (L) of the wide portion of the flat through hole (2). The male screw part (15a) of the ball joint (15) is screwed into the screw hole (5). Both ends of the wide part of the flat through hole (2) are not blocked by the male screw part (15a), and both ends of the outer peripheral surface of the male screw part (15a) and the wide part of the flat through hole (2). A space (6) exists between and. The left and right dust boots (17) are communicated with each other through the space (6) and the flat through hole (2).

As a result, when the rack shaft (1) is moved by turning the steering wheel, the dust boot (17) on the moving direction side (the left side when the rack shaft (1) is moved leftward is left). The air enclosed inside flows into the other dust boots (17) through the space (6) and the through hole (2), and as a result, the enclosed space inside the dust boot (17) on the above-mentioned moving direction side. Air is prevented from hindering the movement of the rack shaft (2).

In the above embodiment, since the ball joints (15) are attached to both ends of the rack shaft (2), the screw holes (5) are also formed at both ends. (2) is also applicable to a steering device of the type in which a tie rod is attached to only one end via a ball joint.In this case, a screw hole should be formed only in one end of the rack shaft. Good.

Further, the rack shaft of the present invention can be applied to a hydraulic or electric rack and pinion steering device.

[0017]

[Effect of the device]

 According to the rack shaft of the rack and pinion type steering device of the present invention, as described above, it is not necessary to perform cold forging on the rack shaft, and moreover, the joint for connecting the inside and outside of the rack shaft to the conventional connection is not required. Since it is not necessary to separately form the holes, the number of manufacturing steps of the steering device using the rack shaft is reduced, the work is simplified, and the cost is reduced. Further, since cold forging is not performed unlike the conventional rack shaft, no stress is generated in the rack shaft.

[Brief description of drawings]

FIG. 1 is a partially enlarged horizontal sectional view showing a main part of a rack and pinion type steering device having a rack shaft according to the present invention.

FIG. 2 is an enlarged sectional view taken along line II-II of FIG.

FIG. 3 is a partially cutaway rear view of a conventional rack and pinion steering device including a rack shaft.

FIG. 4 is a partially enlarged horizontal sectional view of the same.

[Explanation of symbols]

 1 Rack Shaft 1a Rack 2 Flat Through Hole 3 Thick Wall 4 Thin Wall 5 Screw Hole 13 Pinion Shaft 14 Pinion 15 Ball Joint (Universal Joint) 16 Tie Rod D Female Thread Root of Threaded Hole L Wide Through Hole length

Claims (1)

[Scope of utility model registration request] 1. A rack and pinion type steering device having a rack which is connected to a tie rod through a universal joint having at least one end screw-fitted and which meshes with a pinion of a pinion shaft connected to a steering wheel. A rack shaft having a circular cross section, having a flat cross section through hole extending in the axial direction to form a hollow shape, and a pair of thick wall portions are formed on both sides of the through hole in the peripheral wall in the narrow direction. With 1 on both sides in the same width direction
A pair of thin-walled parts is formed, a rack is formed on the outer surface of one of the thick-walled parts, a screw hole for screwing the universal joint is formed at least at one end, and the root diameter of the female thread of the screw hole is The rack shaft of a rack and pinion type steering device that is smaller than the length of the wide part.