JPH0222388Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rack shaft in a rack and pinion type steering device for a vehicle made of a steel tube.

As shown in FIG. 6, a rack shaft of this type of steering device has been proposed in which rack teeth are formed in a flat portion formed by plastic working on a portion of a steel pipe to reduce the weight. Similar to conventional solid-shaft rack shafts, such a rack shaft is coated with grease on the meshing contact portion with the pinion that meshes with the rack teeth to smooth the meshing. However, when used for a long period of time, the grease deteriorates and the meshing contact area between the rack teeth and the pinion becomes more worn, resulting in a problem in that the meshing becomes looser.

An object of the present invention is to provide a rack shaft that can lubricate the engagement between the rack teeth and the pinion over a long period of time.

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 shows the rack axis of the embodiment of the present invention. A groove 2 recessed in the direction of the outer peripheral flat part is formed approximately at the center of the flat part 1 of the approximately D-shaped inner hole of the steel pipe, and a passage 6 is formed that communicates the groove 2 with the tooth bottom 5 of the rack tooth 4. did. The groove portion 2 has a second
As shown in the figure, a thin-walled steel pipe is placed on a lower mold 8 having an arcuate groove 7, and a punch 9 is placed on top of the lower mold 8.
An upper mold 12 having a punch hole 10 that reciprocates and arcuate parts 11, 11 for pressing and fixing the steel pipe is placed, and the mandrel (Fig. (not shown). The passage 6 is formed by forming a rack tooth 4 on the flat part 13 by cutting, broaching, etc., and forming a recess in the bottom part 5 of the rack tooth 4 and the flat part 1 of the inner hole of the steel pipe. The groove portions 2 intersect with each other, and the steel pipe inner hole 3 and the tooth bottom portion 5 of the rack tooth 4 are formed in communication with each other. Further, as shown in FIGS. 3 and 4, the depth l of the groove portion 2 is made slightly smaller than the position of the tooth bottom portion 5 of the rack tooth 4 to be formed.
After the rack tooth 4 is formed, a thin wall portion t is left behind, and when the rack tooth 4 is induction hardened, the thin wall portion t is melted to form a passage 14 that communicates the tooth bottom portion 5 of the rack tooth 4 with the steel pipe inner hole 3. You may do so.

The passages 6 and 14 become grease passages for sending grease to the tooth surfaces by filling the steel pipe inner holes 3 and 3 with lubricating grease.

FIG. 5 shows the rack shaft of the present invention installed in a rack and pinion type steering device for a vehicle. The rack teeth 16 of the rack shaft 15 are meshed with a pinion 18 that is pivotally supported within the gear housing 17, and on the back side of the rack shaft 15, the rack shaft 15 is slidably supported by a rack guide 19.
Since the rack guide 19 is pressed by the spring 20, the meshing play between the rack teeth and the pinion is eliminated. The rack shaft 15 is moved in the axial direction by the rotation of the pinion 18,
Steering is performed by moving steering wheels (not shown) left and right.

By filling the inner hole of the rack shaft with grease and supplying the grease to the tooth surface of the rack from the passage at the bottom of the rack tooth, smooth meshing between the rack tooth and the pinion can be maintained for a long time.

As described above, the present invention provides a concave groove recessed toward the flat part of the outer periphery at approximately the center of the flat part of the inner hole of the steel pipe in the flat part forming the rack tooth, thereby forming a passage communicating with the bottom part of the rack tooth. Therefore, it is possible to mass produce a rack shaft having a passage communicating with the steel pipe inner hole at the bottom of the rack tooth formed in the steel pipe having a substantially D-shaped inner hole. Furthermore, by simply filling the inner hole of the steel pipe with grease, smooth engagement between the rack teeth and the pinion can be maintained for a long period of time.

[Brief explanation of drawings]

Fig. 1 is a sectional view at right angles to the axis of a rack shaft according to an embodiment of the present invention, Fig. 2 is a sectional view showing the molded state of the embodiment of the invention, and Fig. 3 is a sectional view at right angles to the axis of a rack shaft showing another embodiment. , FIG. 4 is a cross-sectional view at right angles to the axis of the rack shaft, showing the state in which the groove shown in FIG. , and FIG. 6 is a sectional view taken at right angles to the rack shaft of the prior art. Explanation of symbols, 1... Flat part of steel pipe inner hole, 2...
Concave groove portion, 3...Inner hole of steel pipe, 4...Rack tooth, 5...
...Tooth bottom, 6...passage, 14...passage.

Claims (1)

[Scope of utility model registration request] In a rack shaft of a rack and pinion type steering device for a vehicle in which a flat portion is provided in a part of the steel pipe, the inner hole thereof is formed in a substantially D shape, and rack teeth are formed in the flat portion, the approximately D shape is used. A vehicle, characterized in that a concave portion recessed toward the flat portion of the outer periphery is formed approximately in the center of the flat portion of the inner hole of the steel pipe, and a passage is formed that communicates the concave portion with the tooth bottom portion of the rack tooth. The rack shaft in the rack and pinion steering system.