JPS63195065A - Control valve for power steering device - Google Patents

Abstract

PURPOSE:To facilitate the valve curve setting of a demand steering feeling, by installing a cam member in an input shaft, while installing a projection part to be engaged with this member in a valve sleeve or a rotor, and displacing the rotor into relative rotation with the specified turning force. CONSTITUTION:When a steering wheel is rotated, a projection part 19 depresses a cam ring 18, moving from a lowermost end of a cam part 18a, whereby a valve sleeve is rotated. If so, a passage 16 and another passage 17 are circulated to flow each other by rotation of the valve sleeve 14 to a rotor 15, whereby an input shaft 11 is made so as to be easily rotated as subjected to power assist from a power cylinder, thus the rotor 15 keeps relative displacement with the valve sleeve 14. Here, a spring 22 and the cam ring 18 both act so as not to make the valve sleeve 14 relatively rotate unless there is manual steering effort of more than the specified one. Therefore, a valve curve can be freely set up by form of the cam part 18a and a spring constant 22 of the spring.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a control valve installed in, for example, a rack-and-binion type power steering device.

[Prior Art] Generally, in an automobile power steering device,
A control valve is provided on the shaft of the steering wheel to control the supply and discharge of oil from an oil source to the power cylinder.

Conventionally, as this type of control valve, one constructed as shown in FIG. 7, for example, is known. According to this, when the steering wheel is rotated, the rotor A rotates, and the fluid passage B of the rotor A is communicated with the fluid passage of the valve sleeve C, and the oil tank (not shown) connected to the fluid passage is connected to the fluid passage B of the rotor A. From step 1), oil is supplied to the power cylinder through the valve sleeve C and the fluid passage B of the rotor A, thereby boosting the steering output.

In Fig. 7, E is an input shaft (torsion bar), one end of which is connected to the binion F, and the other end connected to the rotor A. When the steering wheel is rotated, one end side is connected to the binion F. Since it is receiving ground resistance through engagement with the rack rod G, the other end is twisted,
This causes the rotor to rotate as described above.

[Problems to be Solved by the Invention] In the above control valve, in order to set the input pressure characteristics (valve curve) to provide the required steering feeling, the valve opening/closing portion of the input shaft (rotor and valve curve) must be Previously, the opening part of the fluid passage in the sleeve was chamfered, etc., but the machining was delicate and difficult, and there were certain limits to the valve curve settings, so it was difficult to fully satisfy the required steering feeling. There was a problem that could not be resolved.

Further, since the torsion bar E is used, even if an insensitive area is provided in the valve curve, the center feeling depends on the spring constant of the torsion bar, so there is a problem of lacking a sense of rigidity.

The purpose of the present invention is to relatively easily set a valve curve that provides the required steering feeling, expand the setting range, and provide a sense of rigidity in the center feel when driving in a straight line at medium and high speeds. To provide a control valve for a power steering device that can eliminate center play.

In order to achieve such an object, the present invention provides a cam member that is movable in the axial direction and is prevented from rotating in the circumferential direction on the input shaft that is integral with the rotor or separate from the rotor, and a cam member that is movable in the axial direction and prevented from rotating in the circumferential direction. A protrusion that engages with the cam portion of the cam member is provided on either side of the rotor, and a pressing member that presses the cam member against the protruding portion is provided on the input shaft to resist the pressing force of the pressing member. The structure is such that either the valve sleeve or the rotor rotates relative to the other when a rotational force is applied to remove the protrusion from the cam.

[Example] Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a first embodiment of the control valve of the present invention. According to this first embodiment, an input shaft 11 is installed in a hole 10a provided in the housing IO. A pinion 12 is provided at one end of the input shaft 11 (the lower part in FIG. 1), which meshes with a rack (not shown) provided on a rack rod. Note that wheels (not shown) are connected to both ends of the rack rod via a link mechanism (not shown), and this rack rod is power assisted by a power cylinder (not shown).

Further, a valve sleeve 14 is rotatably installed in the hole 10a via a bearing 13. A shaft portion 14 protruding from the housing 10 is provided at one end of the valve sleeve 14.
a is provided, and a shaft of a steering wheel (not shown) is connected to the shaft portion L4a (see FIG. 3a). Further, a rotor 15 provided at the other end of the input shaft 11 (upper part in FIG. 1) is rotatably inserted into the valve sleeve 14.

The valve sleeve 14 is provided with a plurality of fluid passages 16, and the rotor 15 is provided with a plurality of fluid passages 17 communicating with the fluid passages 16. These fluid passages 16.
17 cooperate with each other by the relative rotation of the valve sleeve 14 and rotor 15 to flow or stop the oil flow. That is, by rotating the steering wheel, the valve sleeve 14 and rotor 15 rotate relative to each other, and oil is transferred from the oil tank to the fluid passage 16 of the valve sleeve 14 and the fluid passage 17 of the rotor 15.
The oil is supplied to the power cylinder through the oil tank or returned to the oil tank. Since this operation is well known, detailed explanation thereof will be omitted.

Next, to explain the characteristic parts of the present invention, the input shaft 11
A cam ring 18 as a cam member is attached to the intermediate portion of the valve sleeve 18 so as to be movable in the axial direction, and the valve sleeve 14 engages with a cam portion 18a of the cam ring 18 that is recessed in a substantially V-shape. A protrusion 19 is integrally formed (see FIGS. 3a and 3b). In the middle part of this input shaft 11, there is shown in FIG. 2a.

As shown in b, for example, a portion of the circumferential surface is cut to form a flat collar portion 20 for preventing rotation, and the flat portion 20 prevents the cam ring 18 from rotating. Also, input
A flange portion 2 is provided at the intermediate portion of the shaft 11 on the side closer to the binion 12.
A spring 22 is interposed between the flange portion 21 and the cam ring 18 to press the cam ring 18' toward the protrusion 19 side.

In the state shown in FIG. 1, the spring 22 is preloaded, that is, it is pushed by the cam ring 18 and the flange portion 21, and the resulting elastic force acts on the cam ring 18, causing the cam ring 18 to move forward. 18a is pressed against the protrusion 19.

Therefore, the steering wheel is connected to the rotor 15, input shaft 11, and pinion 12 in the rotational direction through the engagement between the protrusion 19 and the cam 18a from the valve sleeve 14. Now, when trying to rotate the steering wheel from its neutral position, the mechanism consisting of the cam ring 18, the protrusion 19, and the spring 22 functions in the same way as the torsion bar of the prior art. That is, since there is ground resistance on the input shaft 11 due to the engagement between the pinion 12 and the rack, the input shaft 11 does not rotate easily, and the protrusion 19 pushes down the cam ring 18, causing the input shaft 11 to move from the lowest end of the cam portion 18a. When moved, the valve sleeve 14 rotates.

That is, similar to the case where the torsion bar is twisted in the prior art (see Figure 1), the valve sleeve 14 rotates relative to the rotor 15, and the fluid passage 16 of the valve sleeve 14 and the fluid passage 17 of the rotor 15 communicate with each other. , oil is supplied from the oil tank to the power cylinder. As a result, the input shaft 11 is easily rotated by power assisting the rack rod from the power cylinder, and as the steering wheel is steered, the input shaft 11 (rotor 15
) rotates while maintaining a relative displacement with the valve sleeve 14 to move the rack rod.

However, the spring 22 and the cam ring 18 are fixed so that the valve sleeve 14 does not rotate relative to the rotor 15 unless the steering force exceeds the -chamber. That is, since the steering wheel and pinion function to prevent relative phase shift in the rotational direction, unlike the case of a torsion bar, they function to create an insensitive region for the valve curve. Therefore, the shape of the cam portion 18a and the spring 22
By changing the spring constant of the valve, the valve curve can be freely set, and the valve opening/closing part (
There is no need to go through troublesome procedures such as removing the openings of the fluid passages 15 and 17, and only one type of valve opening/closing part is required, and the shape of the cam part 18a and the spring 2
A spring constant of 2 makes it possible to make a variety of valves.

In addition, since the elastic force of the spring 22 holds the cam part 18a and the protrusion 19 in an engaged state and fixes the steering wheel in its neutral position with no play, the center feeling is improved. It works to create a sense of rigidity. Therefore, the steering feeling is stabilized when driving straight at medium and high speeds.

Figures 6a to 6c show examples of valve curve settings for the control valve of the present invention. Figure a shows the angle-torque characteristics. That is, the spring constant, in this example,
Depending on the cam shape, the relative angles of the steering wheel to the pinion vary from 0 to θ and from θ to θ2, each with a different spring constant. Here, the cam portion 18
By changing the shape of a and the spring constant of the spring 22, it is possible to change the spring constant in many stages or to change the spring constant in a quadratic curve.

This is not possible with conventional torsion bars.

Moreover, the same figure shows angle-pressure characteristics.

Relative angle of steering wheel to pinion 0~
During θ3, the pressure in the power cylinder constantly increases, similar to the conventional valve, to reduce the steering force. In other words, the steering force becomes lighter as the steering progresses. Further, C in the same figure shows a valve curve. This is inevitably determined by the characteristics of a and d of the same figure. The flat part where the torque goes from 0 to 10 provides a sense of unity that is almost the same as manual steering.

In the conventional torsion bar one-way type, although the flat part from torque 0 to 10 is referred to as the "manual area", in reality it feels dull due to the torsion bar rigidity, but the present invention has improved this point. Problems can also be solved. In this example, the spring constant is set to 2 as shown in figure a.
By changing the valve curve in stages, the torque is 10-11 in the valve curve in the figure C, which provides a relatively heavy steering feel in the medium speed range, and the torque t14t2, which is very low speed, provides a relatively heavy steering feel.
In the stationary and stationary ranges, it provides a light steering feel. In this way, it is possible to significantly expand the range of "flavoring" the valve curve compared to conventional methods.

FIG. 4 shows a second embodiment of the invention. In this second embodiment, the rotor 15 of the input shaft 11 is different from the first embodiment, and one end of the rotor 15 is connected to the steering wheel, and the other end of the rotor 15 and the binion 12 are connected to the steering wheel. A cam block 23 as a cam member (see FIGS. 5a and 5b) and a protrusion 24 that engages with a substantially V-shaped recessed cam portion 23a of the cam block 23 are disposed between the input shaft 11 and the input shaft 11. and a spring 25 that presses the cam portion 23a toward the protrusion 24 and maintains the engaged state between the two. That is, the rotor 15
A protrusion 24 is integrally provided at the other end, and a cam block 23 is provided in a recess 26 provided at the other end of the human power shaft 11.
are fitted so as to be movable in the axial direction while being prevented from rotating, and a spring 25 is interposed between the cam block 23 and the bottom surface of the four parts 26 in a compressed state.

Therefore, similarly to the first embodiment, the cam block 2
3, the protrusion 24, and the spring 25 have the same function as a torsion bar, and the spring 25 and cam block 23 also function to fix the steering wheel so that it does not rotate unless the steering force exceeds a certain level. Therefore, it functions to create an insensitive area for the valve curve, and further, the elastic force of the spring 25 keeps the cam part 23a and the projection part 24 in the engaged state, so that the steering wheel is in its neutral position with no play. Since it works to fix it in place, it works to create a sense of rigidity in the center feeling.

This second embodiment has the advantage that valve sticking is less likely to occur compared to the first embodiment.

[Effects of the Invention] As explained above, according to the present invention, a cam member that is movable in the axial direction and prevented from rotating in the circumferential direction is provided on the input shaft that is integral with the rotor or separate from the rotor, and A protruding portion that engages with the cam portion of the cam member is provided on either the input shaft and the separate rotor, and a pressing member that presses the cam member against the protruding portion is provided on the input shaft. When a rotational force is applied to remove the protruding part from the cam part against the pressing force, either the valve sleeve or the rotor is configured to rotate relative to the other, thereby achieving the required steering feeling. The valve curve to be applied can be set relatively easily by changing the shape of the cam member and the pressing force of the pressing member.

In addition, since the cam member and the protrusion are held in an engaged state by the pressing force of the pressing member, and the steering wheel is fixed in its neutral position with no play, it provides a sense of rigidity in the center feel. It is possible to eliminate play in the center when driving straight at high speed.

Furthermore, since the torsion bar can be omitted, there is no need for valve balancing, and there is no risk of oil leaking from the torsion bar ring.

[Brief explanation of the drawing]

1 to 3 a and b show a first embodiment of the present invention, in which FIG. 1 is an overall sectional view, FIG. 2 a is a plan view of the input shaft, and the same figure is a front view of the same. , and also Figures 4 and 5a
, b shows a second embodiment of the present invention, FIG. 4 is an overall sectional view, FIG. 5 a is a plan view of the cam member (cam block), and FIG. Figure 6 a to c
is a graph showing an example of valve curve setting, and the seventh
The figure is a sectional view showing a conventional technique.

Claims (1)

[Claims] A rotor having a plurality of fluid passages communicating with the fluid passage is rotatably inserted into a valve sleeve having a plurality of fluid passages, and when the valve sleeve and the rotor rotate relative to each other, the fluid passage of the valve sleeve and the rotor are rotated. In a control valve for a power steering device that allows fluid to flow or stops fluid by cooperating with a fluid passage of the rotor, a control valve that is movable in the axial direction and that is movable in the circumferential direction is attached to the input shaft that is integral with or separate from the rotor. A cam member that is prevented from rotating is provided, and a protrusion that engages with a cam portion of the cam member is provided on either the valve sleeve or a rotor separate from the input shaft, and the cam member is provided on the input shaft. A pressing member is provided to press the protruding portion, and when a rotational force is applied to remove the protruding portion from the cam portion against the pressing force of the pressing member, either the valve sleeve or the rotor rotates relative to the other. A control valve for a power steering device, characterized in that it is configured as follows.