JPS6355473B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in rack-and-pinion power steering devices used primarily in automobiles.

A steering device that transmits the rotation of the steering wheel to the wheel steering arm via a mechanism consisting of a pinion and a rack is characterized by a simple structure and excellent operational response. As a power steering device in which a pinion type steering device is hydraulically power assisted, for example, the one shown in FIG. 1 has been proposed.

In the figure, 1 is a rack linked to a steering link (tie rod etc. not shown), 2 is a pinion, 3 is a spool valve, and 4 is a main body housing these.

A pinion 2 that meshes with the rack 1 is formed integrally with a pinion shaft 5 and is supported by the main body 4 via bearings 6 and 7 provided before and after the pinion 2.

The bearings 6 and 7 have, for example, an outer race 9 inserted into an oval play hole 8 whose long axis is parallel to the rack 1, and are formed so that the pinion shaft 5 can be displaced by a predetermined distance left and right. be.

On the other hand, the spool valve 3 has a sleeve portion 10 formed in the main body 4 in a direction perpendicular to the pinion shaft 5.
It is slidably housed in the

The spool valve 3 is provided with an annular groove that forms a pressure oil passage with the sleeve portion 10, and the sleeve portion 10 cooperates with these annular grooves to connect the hydraulic chamber of a power cylinder (not shown) to the pump side or A control port is formed that selectively communicates with the tank side, and when the spool valve 3 moves from the neutral position shown in the figure to the right or left, the direction of pressure oil to the power cylinder changes depending on the direction of movement. ,
Since these belong to well-known techniques, they will not be described in detail.

A centering spring 13 is secured to a snap ring 14 through a washer 12 and tensioned on the small diameter portion 11 of the spool valve 3 . This centering spring 13 is connected to the spool valve 3
is displaced to the left (rightward in FIG. 2) or rightward, the washers 12 move toward the plugs 15, respectively.
Alternatively, it is latched to a part of the main body and compressed, urging the spool valve 3 to return to the neutral position.

A pin hole 16 is bored in the spool valve 3, and a drive lever 17 that links the pin hole 16 and the pinion shaft 5 is swingably supported by a part of the main body.

The drive lever 17 has a support pin 19 and a drive pin 20 protrudingly provided at symmetrical positions passing through the center of a ring portion 18 that fits into the pinion shaft 5, and the support pin 19 is connected to the main body 4.
The drive pin 20 is inserted into the pin hole 16 of the spool valve 3, and the drive pin 20 moves in an arc around the support pin 19 as the pinion shaft 5 moves from side to side. Switch valve 3.

Therefore, when the pinion shaft 5 is rotated, for example, to the left by operating a handle (not shown), the resistance of the rack 1 linked to the steering link is large, so that the play hole 8 is rotated along the rack 1 in this rotation direction. The pinion 2 is displaced by the amount allowed by . As a result, the drive lever 17 rotates around the support pin 19, and the drive pin 20, which moves in an arc, displaces the spool valve 3 to the left and switches the spool valve 3. Accordingly, pressure oil is sent to the power cylinder, and the hydraulic pressure is Rack 1 moves under the power assist from the wheel and changes the direction of the wheels. By the way, when switching this valve, the drive pin 20 is connected to the spool valve 3.
Since the pinion shaft 5 receives a reaction force from the centering spring 13 which attempts to return the pinion to the right neutral position, the pinion shaft 5 also receives a reaction force F to the right via the drive lever 20 as shown in FIG. As a result, the pinion shaft 5 is subjected to prying M as shown by the arrow around the center P of engagement with the rack 1, and the outer races 9 of the bearings 6 and 7 come into contact with the left and right edges of the play hole 8, respectively, and the pinion Axis 5 and rack 1 are no longer orthogonal. For this reason, there is a problem in that the meshing becomes irregular, the tooth surfaces become tight, and the steering operation becomes unstable.

The present invention is intended to solve this problem.The present invention is provided with a spring that applies a load in a direction parallel to the centering spring at the tip of the pinion shaft, and cancels out the reaction force of the centering spring when the handle is operated. To provide a power steering device that operates smoothly and allows shafts to maintain regular engagement easily.

The present invention will be described below based on the embodiments shown in the drawings, in which the same reference numerals will be used for substantially the same parts as in FIGS. 1 and 2.

As shown in FIG. 3, a center hole 22 is bored at the tip of the pinion shaft 5, and a small diameter portion 23 of the center hole 22 is formed at the tip of the pinion shaft 5.
One end of the bending bar 24 is press-fitted and fixed.

This bending bar 24 forms a clearance with the large diameter portion 25 of the center hole 22, and the other end is rotatably supported by a spherical seat 28 formed into a spherical portion 26 and fixed to the plug 27. be done.

Next, the effect will be explained. When the pinion shaft 5 is displaced, for example, toward the front of the paper, the bending bar 24 can rotate about the spherical seat 28, but since the other end is fixed to the pinion shaft 5, the bending bar 24 It can be bent to the right using the boundary between the large diameter hole 25 and the small diameter hole 23 of the center hole 22 as a fulcrum. Therefore, the pinion shaft 5 receives a rightward reaction force F' at the press-fitted portion of the bending bar 24. This reaction force F' causes a twist M' on the pinion shaft 5, as shown in FIG.

Since this reaction force F' is set according to the specifications of the bending bar 22 so that the prying force M' cancels out the prying force M, the pinion shaft 5 is not twisted by the reaction forces F and F'. It is displaced to the left while perpendicular to rack 1. Therefore, the engagement between the rack 1 and the pinion 2 is maintained in a normal state, so that the steering operation is performed smoothly.

Next, the embodiment shown in FIG. 4 will be described. A pin 29 protruding from the tip of the pinion shaft 5 is sandwiched from both sides by a pair of leaf springs 30 in a direction orthogonal to the spool valve 3. The leaf spring 30 has an initial inward curvature, and both ends thereof are inserted into grooves 31 formed in the plug 27 and are held and tensioned by the grooves 31 . Note that above and below the pin 29, a pin 32 with the same diameter as the pin 29 is connected to the plug 27.
It is set more protrudingly.

In this configuration, when the pin 29 along with the pinion shaft 5 is displaced, for example, to the left (to the front in the paper in FIG. 4a, and to the left in FIG. deforms into a curve. For this reason, the pinion shaft 5 is
The rightward reaction force F' of the leaf spring 30 is received via the pin 29.

Therefore, the pinion shaft 5 is not twisted by the reaction forces F and F' as shown in FIG.
It is perpendicular to Rack 1 and maintains regular engagement.

Further, the initial load of the leaf spring 30 is changed by changing the initial inward curvature of the leaf spring 30 and the position of the pin 32 in the radial direction,
The magnitude of the reaction force F′ can be changed.

Next, the embodiment shown in FIG. 5 will be described. A pair of coil springs 33 are disposed parallel to the spool valve 3 and abut on both sides of a pin 29 protruding from the tip of the pinion shaft 5. The coil spring 33 has an inner end secured by a pin 34 having the same diameter as the pin 29 protruding from the upper and lower walls of the plug 27, and an outer end secured by the left and right walls of the plug 27, respectively.

In this configuration, when the pin 29 is displaced, for example, to the left together with the pinion shaft 5, the left coil spring 33 is pressed and compressed by the pin 29. Therefore, the pinion shaft 5 receives the rightward reaction force F' of the coil spring 33 via the pin 29.

Therefore, the pinion shaft 5 is not twisted by the reaction forces F and F' as shown in FIG.
It is perpendicular to Rack 1 to maintain normal meshing.

Furthermore, the magnitude of the reaction force F' can be changed by changing the coil spring 33 to one with a different spring constant and locking it with the pin 34 to change the initial load.

Next, to explain the embodiment shown in FIG.
7 is supported in a direction parallel to the spool valve 3. A flange 37 is formed at one end of the rod 35, and a snap ring 38 is attached to the other end.
A coil spring 36 is stretched across a washer 39. The outer side of each of the washers 39 is in contact with a step 40 formed on the inner wall of the plug 27 when in the neutral state.

In this configuration, when the rod 35 is displaced, for example, to the left together with the pinion shaft 5, the coil spring 36 is pressed against the snap spring 38 via the washer 39 on the right side, and is locked to the stepped portion 40 via the washer 39 on the left side. and compressed. Therefore, the pinion shaft 5 receives a rightward reaction force F' of the coil spring 36 via the rod 35 and the snap spring 38.

Therefore, the pinion shaft 5 is not twisted by the reaction forces F and F' as shown in FIG.
It is perpendicular to Rack 1 and maintains regular engagement.

As explained above, according to the present invention, since the spring that applies a load in a direction parallel to the centering spring is disposed at the tip of the pinion shaft, the reaction force of the centering spring when the handle is operated is canceled out, and the pinion shaft and The spool valve is orthogonal to the spool valve to maintain proper engagement, smoothing the steering operation, and dispersing the centering force of the spool valve, allowing the centering spring to be made more compact.

[Brief explanation of drawings]

Fig. 1 shows a conventional device, in which Fig. 1a is a longitudinal sectional view, Fig. 2b is a sectional view taken along the line -A in Fig. 2, Fig. 2 is a perspective view showing the relationship between the pinion shaft and the rack, and Fig. 3 is a longitudinal sectional view. Figures 6 to 6 each show an embodiment of the present invention, and in each drawing, a is a vertical cross-sectional view of a main part, and b is a cross-sectional view taken along the line a. 1...Rack, 2...Pinion, 3...Spool valve, 4...Body, 5...Pinion shaft, 6,
7...bearing, 8...play hole, 9...outer race,
13... Centering spring, 17... Drive lever, 24... Bending bar, 27... Plug, 29... Pin, 30... Leaf spring, 33, 36... Coil spring, 35...
Rod.

Claims (1)

[Claims] 1. A rack linked to a steering link, a pinion shaft that engages with this rack and moves in parallel along the rack during steering, a spool valve that is switched via an intermediate member as the pinion shaft moves in parallel, and A power steering device equipped with a centering spring that biases a spool valve to a neutral position, the power steering device comprising a spring that applies a load in a direction parallel to the centering spring at the tip of the pinion shaft.