JPS6235947B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates in particular to a valve mechanism of a hydraulic power steering system for an automobile or the like.

Generally, in a torsion bar reaction force type power steering device, the hydraulic control valve is usually disposed coaxially with the steering shaft. Therefore, if the vehicle body has limited space in the direction of the steering axis, it may be difficult to secure space for the hydraulic control valve.

On the other hand, Japanese Patent Application Laid-open No. 4736340 and Japanese Patent Publication No. 36
According to Publication No. 20451, the steering shaft and the control valve are arranged in parallel, and a mechanism is provided to convert the rotational motion of the steering shaft into the axial motion of the control valve and transmit it, thereby shortening the length in the axial direction. There are some proposals, but in all of these cases, the mechanism for converting rotational motion into axial motion is complex, and even if it is possible to shorten the length in the axial direction, it creates a new problem of increasing the size in the radial direction. occured.

The present invention aims to solve such problems.

Therefore, the present invention connects an output shaft coaxially with the steering shaft via a torsion bar, and arranges a spool valve in parallel thereto, with a spur gear on one of the steering shaft and the output shaft, and a helical gear on the other. and a valve shaft that moves in the axial direction integrally with the spool valve has gears meshing with both gears, and the spool valve is moved axially in response to the torsional phase angle of the torsion bar. be.

Embodiments of the present invention will be described below with reference to the accompanying drawings.

The figure shows an example in which the present invention is applied to a rack-and-pinion type power steering device, in which a steering shaft 3 is disposed coaxially with a pinion gear 2 that is rotatably supported inside a housing 1 and is also rotatably supported. Both 2, 3
are the torsion bars 4 received inside them
are connected.

A spur gear 2a and a helical gear 3a are respectively carved adjacent to each other in the overlapping enlarged diameter portions of both 2 and 3, and have the same number of teeth.

A rack 5 meshes with the pinion gear 2, and the rack 5 is connected to the running wheels via a known link mechanism.

Therefore, when the steering shaft 3 is rotated via a steering handle (not shown), the rotation is transmitted with a slight delay by the torsion bar 4 and the pinion gear 2 rotates, and the rack 5 meshed with the gear 2 rotates. The running wheels are turned by moving in a direction perpendicular to the axis.

In order to reduce the steering force at this time by hydraulic assist, a power cylinder 6 is attached to a part of the linkage. A valve mechanism for selectively supplying oil in accordance with the direction of rotation of the steering handle is incorporated inside the housing 1.

That is, a valve shaft 9 rotatably and axially slidably supported by the housing 1 is arranged parallel to the axis of the pinion gear 2, and a spool valve 10 is fitted to one side of the shaft so as to be relatively rotatable. The spool valve 10 is configured to move integrally with the valve shaft 9 in the axial direction.

Therefore, the spool valve 1 is located on the sliding surface of the housing 1 and the spool valve 10 through a group of annular ports formed in both 1 and 10, respectively.
0 slides in the left-right direction in the figure, pressure oil is selectively supplied to the pressure chambers A and B of the power cylinder 6.

On the other hand, on the other side of the valve shaft 9, a spur gear 11 and a helical gear 12 are integrally carved, corresponding to the aforementioned spur gear 2a and helical gear 3a, respectively. 12, the valve shaft 9 can be displaced in the axial direction in response to the torsional phase of the torsion bar 4 generated based on the steering input.

In the figure, 13 is an oil tank, 14 is a return spring, 15 is a retainer, and 16 is a retainer spring.

Next, the operation of the present invention configured as described above will be explained.

Now, there is no ground resistance on the running wheels and pinion gear 2
When there is no load, the pinion gear 2 also rotates as the steering shaft 3 rotates. Therefore, the helical gear 3a and the spur gear 2a also rotate, and the rotation is transmitted to the helical gear 12 and the spur gear 11 of the valve shaft 9. However, in this case, the helical gear 3a and the spur gear 2
Since a rotates integrally, the valve shaft 9 only rotates, and the spool valve 10 maintains the neutral position as shown in the figure and does not displace. (Therefore, the booster does not work in this state.) Next, if there is a load on the pinion gear 2, the rotation of the steering shaft 3 twists the torsion bar 4 according to the load, and the steering shaft 3 and pinion gear 2
A rotational phase difference occurs between the two. This relative displacement directly becomes the rotational phase of the helical gear 3a and spur gear 2a and is transmitted to the helical gear 12 and spur gear 11 of the valve shaft 9. However, these helical gears 12
Since the and spur gear 11 are integral, they cannot be displaced relative to each other. Therefore, an axial thrust force is generated in the helical gear 12 according to the rotational phase, and the valve shaft 9, which is integral with this, is moved in the axial direction. Displaced to.

This axial displacement of the valve shaft 9 absorbs the relative displacement between the helical gear 3a and the spur gear 2a, and when the relative displacement between both 3a and 2a is eliminated, the axial displacement of the valve shaft 9 stops, and the position Rotate with. Incidentally, the spur gears 2a and 11 do not undergo any rotational deviation, but are allowed to be displaced from each other in the axial direction. Further, the valve spool 10 may be configured to rotate integrally with the valve shaft 9.

Therefore, the rotational phase difference between the steering shaft 3 and the pinion gear 2 is proportional to the axial displacement of the spool valve 10, and the hydraulic circuit is switched in response to the rotation of the steering shaft 3. The wheels change direction by expanding and contracting in response to the movement of the wheel.

Then, when the load on the pinion gear 2 is reduced (or released) from the above state and the steering shaft 3
When the input to is reduced (or canceled)
The restoring force of the torsion bar 4 causes an operation opposite to that described above (an operation such that the phase between the steering shaft 3 and the pinion gear 2 becomes zero), and the valve shaft 9
is displaced in the axial direction, and the spool valve 10 returns to the neutral position. At this time, the pseudo reaction force of the steering shaft 3 is obtained by the torsion bar 4 in proportion to the phase angle between the steering shaft 3 and the pinion gear 2.

Although the above embodiment is an example in which the present invention is applied to a rack and pinion type power steering device, it can also be applied to a recirculating ball type power steering device by using a wormshaft as the pinion gear 2. is also possible.

As explained above, according to the present invention, the valve shaft is disposed parallel to the steering shaft, and is linked so that the rotational phase corresponding to the steering input is converted into the axial displacement of the valve shaft. The axial length (including the axial length of the housing) is shortened, so that it can be easily assembled even in vehicles with limited space in the direction of the steering axis. As a conversion mechanism for displacing the spool valve in the axial direction in response to the rotational input of the steering shaft, a spur gear and a helical gear are formed on the valve shaft, and a spur gear and a helical gear that mesh with these are formed on the steering shaft and the output shaft. Since the structure is made up of only gears, the valve switching structure is extremely simple, and has the effect of reducing weight, size, and cost.

[Brief explanation of the drawing]

The figure is a sectional view of a main part of the present invention. 2...Pinion gear, 4...Torsion bar,
3... Steering shaft, 2a... Spur gear, 3a... Helical gear, 11... Spur gear, 12... Helical gear, 1
0...Spool valve, 9...Valve shaft.

Claims (1)

[Claims] 1. An output shaft is connected coaxially with the steering shaft via a torsion bar, and a spool valve is arranged parallel to these, and a spur gear is formed on one of the steering shaft and the output shaft, and a helical gear is formed on the other. , gears meshing with these gears are formed on a valve shaft that moves in the axial direction integrally with the spool valve, and the spool valve is moved axially in response to the torsional phase angle of the torsion bar. Power steering device.