JPH053424Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to a rack and pinion mechanism for a power steering device.

(Prior Art) In general, rack-and-pinion type steering devices have a problem in that backlash occurs due to the gear gap between the rack and pinion. Therefore, in order to solve this problem, conventional structures have been constructed in which the rack is pressed against the pinion using a spring or the hydraulic pressure of engine oil. (As for those using hydraulic pressure, Japanese Patent Application Laid-Open No. 54-138239 and
There is one shown in Publication No. 59-8586. ) (Problem to be solved by the invention) However, with the above structure, regardless of the state of the steering (that is, even when the steering is turned off), there is always a load in the direction that pushes the pinion. There was a problem in that this caused the steering wheel's return characteristics to deteriorate.

(Means for Solving the Problems) Therefore, in view of the above-mentioned problems, the present invention is equipped with a power steering device of the type that uses hydraulic power to assist, and further includes a rack guide for pressing the rack against the pinion. and a pre-pressure chamber for generating pressure for pressing the rack guide against the rack by hydraulic pressure, the rack-and-pinion mechanism for a power steering device of the type having: Provide a communication hole that leads to
Furthermore, the rack is provided with a pre-pressure chamber to a low pressure chamber that communicates with the communication hole at a predetermined position on the side that contacts the rack guide, excluding the area where the rack contacts the rack guide when the steering is in the neutral position. We have created a rack-and-pinion mechanism for a power steering device, which is characterized by having a hydraulic pressure release groove of a predetermined width formed in the axial direction to leak hydraulic pressure.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

First, in FIG. 2, reference numeral 4 indicates a rotatably provided pinion, and the pinion 4 is connected to a steering main shaft (not shown) via a pinion shaft 10 provided above.

Reference numeral 3 indicates a rack engaged with the pinion 4, which is provided so as to be movable in the front-rear direction in FIG. 2 (in the left-right direction in FIG. 1). By rotating the rack 3, the rack 3 can be moved back and forth in the drawing.

On the other hand, a cylindrical casing 11 is provided on the left side of the rack housing 2 in the drawing. A rack guide 6 formed in a substantially cylindrical shape is inserted into the inner periphery of the casing 11 so as to be movable in the left-right direction in the figure.

The right end surface of the rack guide 6 in the drawing is formed in a concave shape that can match the left end surface of the rack 3 in the drawing. Further, a ring-shaped seal 7 is attached to the outer periphery of the rack guide 6 to maintain oil tightness with the casing 11.

The left end of the casing 11 is fitted with an end plug 9
A spring 8 for applying a predetermined preload to the rack 3 is provided between the right end face of this end plug 9 and the left end face of the rack guide 6 as shown in the drawing.

In this example, the preload chamber 5 is mainly composed of the above-mentioned rack guide 6, end plug 9, and casing 11. Moreover, by adding a spring 8 to this, in this example, the preload mechanism 22
It consists of

Next, a port 12 is provided in the upper part of the casing 11 in the drawing, and an end of a hydraulic pressure supply pipe 13 is press-fitted into this port. The other end of the hydraulic pressure supply pipe 13 is connected to a high pressure side pipe 20 shown in FIG.

On the other hand, the high pressure side pipe 20 to which the hydraulic pressure supply pipe 13 is connected is connected to the discharge side of the vane pump 18, and the low pressure side pipe 19 is connected to the reservoir tank 17.
It is connected to the suction side of the vane pump 18 via.

Next, the main parts of the present invention will be explained.

The rack guide 6 is provided with a communication hole 23 communicating from the preload chamber 5 to the rack 3, as shown in FIG.

On the other hand, the rack 3 has respective sides on both sides except for a neutral region of a predetermined width in the center (when this part is in contact with the rack guide 6, the steering wheel (not shown) is in the vicinity of neutral). A hydraulic release groove 24 having a predetermined length is formed along the axial direction. This hydraulic release groove 24 is connected to the rack 3 as shown in FIG.
It communicates with the hydraulic pressure opening hole 25 inside.

Therefore, when the handle (not shown) is turned at a predetermined angle or more and the rack 3 moves forward or backward as shown in FIG. 2, the communication hole 23 and the hydraulic release groove 24
communicate. Therefore, the oil pressure in the preload chamber 5 passes through the communication hole 23, the oil pressure release groove 24, and the oil pressure release hole 25, and then reaches the communication hole 26 provided in the pinion shaft 10.
This means that pressure leaks to the low pressure chamber 27 through the low pressure chamber 27.

Next, the action and effect will be explained. First, the rack 3 is pressed against the pinion 4 by the spring force of the spring 8.

On the other hand, when an engine (not shown) is driven, the vane pump 18 is driven by the engine, and hydraulic pressure comes to act on the high pressure side pipe 20. This oil pressure acts on the preload chamber 5 via the oil pressure supply pipe 13.

Therefore, the rack 3 is pressed against the pinion 4 by the spring force of the spring 8 and the hydraulic pressure from the high pressure side piping 20 mentioned above, reducing gear backlash etc. and ensuring steering rigidity. .

In this example, the communication hole 23 is formed for the rack guide 6, and the hydraulic pressure release groove 24 and the hydraulic pressure release hole 25 are formed for the rack 3, so that when the handle is in the almost neutral position, Since the vicinity of the neutral region shown in FIG. 3 is in contact with the rack guide 6, the hydraulic pressure from the preload chamber 5 cannot leak to the outside through the communication hole 23, and therefore a relatively high preload acts on the rack 3. It turns out.

On the other hand, when the steering wheel is turned to the right or left by a predetermined amount, the communication hole 23 of the rack guide 6 communicates with the oil pressure release groove 24 of the rack 3, and the oil pressure in the preload chamber 5 is transferred to the communication hole 23, the oil pressure release groove 24, and the oil pressure release groove 24. Since it leaks to the low pressure chamber 27 through the open hole 25 and the communication hole 26, the preload applied to the rack 3 by the rack guide 6 becomes low. Therefore, easy 3
Since it becomes easier to move in the left-right direction (in the front-rear direction in FIG. 2), the return characteristic of the handle becomes better.

The return characteristic of the handle can be easily adjusted by increasing or decreasing the diameter of the communication hole 23.

Further, in this example, the spring 8 is provided in the preload chamber 5, but it is of course possible to use another structure in which the rack 3 is pressed against the pinion 4 only by hydraulic pressure.

(Effect of the invention) As explained above, in the present invention, a part of the rack guide is provided with a communication hole that communicates easily from the preload chamber, and the communication hole is provided at a predetermined position on the side of the rack that contacts the rack guide. By providing a hydraulic release groove that communicates and leaks hydraulic pressure, the present invention has an excellent feature that improves the return characteristics when the handle is turned.

Further, since the rack is pressed against the pinion by hydraulic pressure, unlike a case where preload is applied only by a spring, it is possible to save time and effort for preload adjustment.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention; FIG. 1 is a perspective view showing the overall structure of the embodiment, FIG. 2 is a partially cutaway sectional view showing the main parts of the embodiment, and FIG. 4 is a side view showing how the hydraulic pressure release groove is formed in the rack, and FIG. 4 is a sectional view taken along the line A--A in FIG. 3. DESCRIPTION OF SYMBOLS 1... Steering device, 2... Rack housing, 3... Rack, 4... Pinion, 5... Preload chamber, 6... Rack guide, 7... Seal, 8...
... Spring, 9 ... End plug, 10 ... Pinion shaft, 11 ... Casing, 12 ...
Port, 13...Hydraulic pressure supply piping, 17...Reservoir tank, 18...Vane pump, 19...Low pressure side piping, 20...High pressure side piping, 22...Preload mechanism, 23...Communication hole, 24...Hydraulic pressure open groove, 25
...Hydraulic pressure release hole, 26...Communication hole, 27...Low pressure chamber.

Claims (1)

[Scope of utility model registration request] It is equipped with a power steering device of the type that uses hydraulic power to assist, and further includes a rack guide for pressing the rack against the pinion, and a preload chamber that generates pressure for pressing the rack guide against the rack using hydraulic pressure. A rack and pinion mechanism for a power steering device of the type having: the rack guide is provided with a communication hole communicating from the preload chamber to the rack;
Furthermore, the rack has a pre-pressure chamber connected to a low pressure chamber in communication with the communication hole at a predetermined position on the side in contact with the rack guide, except for the area where the rack contacts the rack guide when the steering is in the neutral position. A rack-and-pinion mechanism for a power steering device, characterized in that a hydraulic release groove of a predetermined width is formed in the axial direction to leak hydraulic pressure.