JPH0117900B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved operating valve device for power steering, particularly to a spool type operating valve device.

Conventionally, this type of spool-type operating valve device has been disclosed in Japanese Patent Publication No. 49-8265.
This operating valve device has a valve operating pin extending in the radial direction of the torsion bar that rotates together with one end of the torsion bar that is twisted in response to a steering load, and the tip of the valve operating pin is attached to the torsion bar so as to rotate together with the other end of the torsion bar. The valve actuating pin engages with a notched groove in the valve spool that extends in the right angle direction, and strokes the spool in response to the torsion of the torsion bar, thereby generating assist pressure. Configure it so that it is possible.

In this configuration, during the stroke of the valve spool by the valve actuation pin, the tip of the valve actuation pin does not slide on the side wall of the notched groove in the circumferential direction of the valve spool, but only in the radial direction, so that the valve actuation This is advantageous because the pin does not exert a circumferential force on the valve spool and does not cause it to rotate.

However, when the valve spools are provided as a pair in order to increase the flow rate of the operating fluid in the operating valve device, the valve operating pin in the above configuration extends in the radial direction of the torsion bar, so the operating valve device becomes larger in the radial direction. I get used to it.

Therefore, in this case, it has been common practice to extend the valve actuating pin in a direction parallel to the torsion bar as shown in FIGS. 6 and 7. That is, in these figures, a is a torsion bar, whose one end (the left end in FIG. (right end in the figure)
are connected to a stub shaft c that rotates integrally with the steering wheel, and the steering force of the steering wheel is transmitted to the worm shaft b via the stub shaft c and the torsion bar a, thereby enabling steering. Therefore, the torsion bar a is twisted in a direction corresponding to the steering load, and the power steering operating valve device is provided with a pair of spool-type control valves d and e within the wormshaft b so as to respond to this twisting. , a valve actuation pin f for actuating these control valves on the stub shaft c,
g is implanted. The control valves d and e sandwich the torsion bar a, and a worm shaft b is placed on both sides of the torsion bar a.
Valve spools h and i are provided in the rotational circumferential direction of the valve spools h and i, each extending in a direction perpendicular to the torsion bar a.
have. Further, valve operating pins f, g are arranged to extend in a direction parallel to the torsion bar a, and are engaged with grooves j, k provided in the valve spools h, i.

Thus, when the torsion bar a is twisted in accordance with the steering load and the wormshaft b and stub shaft c rotate relative to each other by this amount of twist, both valve spools h and i are axially rotated in opposite directions by the valve operating pins f and g. When activated, it supplies pressure oil to one power cylinder chamber and simultaneously drains the other power cylinder chamber. As a result, the power steering provides power assist in the steering direction, allowing the steering wheel to be easily steered.

By the way, the valve spools h, i extend in a direction perpendicular to the torsion bar a, and the valve actuation pins f, g
In the case of a spool-type operated valve device having a structure in which the torsion bar a extends in a direction parallel to the torsion bar a, during the operation, the pins f and g move along the side walls of the grooves j and k around the circumference of the valve spools h and i. Because of the sliding contact in the direction, it is unavoidable to apply a component force in the circumferential direction to the valve spools, causing these valve spools h, i to rotate about their respective axes.

However, in the structure of the conventional operating valve device, the grooves j, k of the valve spools h, i, with which the valve operating pins f, g engage, are circumferential grooves.
is not constrained to rotate about its axis in any way. Therefore, during power steering, the valve spools h, i rotate freely, and the valve spools h, i, which control the flow rate,
The relative positions in the circumferential direction of the land peripheries h', h'' and i', i'' of i and the spool guides l, m finally change,
Due to the machining accuracy of the valve spools h, i and spool guides l, m, it was not possible to maintain accurate flow control at the time of manufacture.

That is, FIGS. 9a and 9b and FIG. 10 respectively show the relationship between the land peripheries h' and i' of the valve spools h and i and the inner holes of the spool guides l and m, and in particular, FIG. Figs. b and 10 are enlarged views of the land peripheries h', i' and the radial unevenness of the spool guide inner hole, respectively, due to machining errors. As shown by the solid lines in Fig. 9a and b, the machining accuracy is extremely high and the land circumference green h',
When the circumscribed circle α of i′ is made to exist inside the inscribed circle β of the spool guide inner hole, when the valve spools h and i are stroked to the left in FIG. 9a, the land peripheries h′ and i′ A gap δ = 10 to 15μ is created between the valve spools h and the spool guide inner hole, and exists over the entire circumference at any rotational position of the valve spools h and i, and is defined between the two as shown with hatching. A slight opening exists in any rotational position of the valve spool h,i. Therefore, the opening described above is approximately constant, regardless of the rotational position of the valve spools h, i.

However, manufacturing the valve spools h, i and spool guides l, m with extremely high precision in this way requires
It is impractical because it is extremely disadvantageous in terms of cost, and machining accuracy can only be improved within a range that does not cause a significant cost increase.

In this case, as shown in FIG. 10, the radial inner and outer positions of the circumscribed circle α and the inscribed circle β are reversed, and the ninth
As shown by dotted lines in Figures a and 10, the land peripheral edges h', i' of the valve spools h, i are partially located radially outward from the inner holes of the spool guides l, m, and as shown in Figure 9b. The gap (opening) δ no longer exists in the portion γ shown with hatching in the opposite direction to the hatching in . As the relative rotational position between the valve spools h, i and the spool guides l, m changes due to the rotation of the valve spools h, i, this portion γ becomes larger or smaller, and may even stop occurring depending on the relative rotational position. The opening area of the opening changes greatly depending on the rotation of the valve spool. Therefore, the rotation of the valve spools h and i makes it impossible to maintain the flow rate control characteristics that existed at the time the valve was manufactured.

This is because when the steering wheel is not operated and the operating valve device is in a neutral state, the amount of hydraulic fluid supplied and discharged to and from both power cylinder chambers becomes unbalanced, resulting in a state where the steering wheel is constantly being operated or when the operating valve device is in a neutral state. There was also the risk of causing problems such as the steering force being different when turning to the left and turning to the right.

Therefore, a technical concept has been proposed in which each valve spool is prevented from rotating by its operating pin, as shown in, for example, Japanese Patent Publication No. 50-28687. As shown in Fig. 8, this technical idea is based on the valve spool h,
i is provided with a hole n passing through it in the radial direction, and valve operating pins f and g are inserted into this hole.When the circumferential wall of hole n abuts against these pins, the valve spools h and i are rotation around the axis is prevented,
can achieve the purpose.

However, during the relative rotation between the worm shaft b and the stub shaft c, the pins f and g move in an arc in the direction of the arrow in the figure, causing the valve spools h and
When actuating pins i, it is necessary to form the shape shown in the figure with gaps o and p on both the upper and lower sides in the figure to allow the above-mentioned circular movement of pins f and g. This shaped hole n is
First, holes with approximately the same diameter as the pins f, g are inserted into the valve spools h, i.
It was common practice to drill a hole in the hole and then manually process the hole into a predetermined shape using a file or the like. However, this hole machining is extremely troublesome and difficult because the spacing between the flat surfaces q and r that are in close contact with the pins f and g requires accuracy on the order of microns.

The present invention forms a notched groove in the valve spool by cutting out a part of its circumference, engages the valve actuating pin with the notched groove, and the bottom surface of the notched groove collides with the tip of the valve actuating pin to prevent the valve spool from forming. From the viewpoint that if the notch groove is configured to prevent rotation, the notched groove can be machined by a simple and reliable method such as broaching or milling, no manual work is required at all, and the machining accuracy can be easily increased to a specified level. The present invention aims to provide a power steering valve device that embodies this idea.

Hereinafter, the present invention will be explained in detail with reference to illustrated embodiments.

1 to 4 show a power steering operating valve device improved according to the present invention. In FIG. 1, 1 is a steering gear box, 2 is a worm nut, and 3 is a sector gear. The worm nut 2 has a seal 4 inside the steering gear box 1.
They are fluid-tightly sealed and slidably fitted to function as a power piston, defining power cylinder chambers 5 and 6 on both sides thereof. A rack tooth 2a is formed on the worm nut 2, and a sector gear 3 is meshed with the rack tooth 2a, so that the sector gear 3 is rotated by the axial movement of the worm nut 2. The sector gear 3 is connected to a steering cage that includes a steering gear arm, a drag link, a knuckle arm, a tie rod, etc. fixedly attached to its shaft, and the above-mentioned rotation of the sector gear 3 steers the steered wheels.

A wormshaft 8 is screwed into the ball nut 2 via a recirculating ball 7 (only a portion of which is shown in the drawing), and this wormshaft passes through the end cover 9 of the steering gear box 1 and enters the valve housing 10. infiltrate the
A valve housing 10 is disposed opposite to an end cover 9, and together with it is fastened to a steering gear box 1. The extension portion 11 of the worm shaft 8 that enters the valve housing 10 is brought into sliding contact with the inner peripheral surface of the valve housing 10 at its rear end, and grooves 12 and 13 are formed on the outer peripheral surface of the extension portion 11 at this sliding contact portion. At the same time, a pressure oil supply chamber 14 is defined between the outer peripheral surface of the extension part 11 other than the sliding contact part and the valve housing 10. The grooves 12 and 13 are connected to the power cylinder chambers 6 and 5 through oil passages 15 and 16, respectively, and the pressure oil supply chamber 14 is connected to the discharge port of a pump 18 through an oil passage 17. It is assumed that hydraulic oil is constantly pressurized and supplied into the chamber 14.

A stepped blind hole is formed in the rear end surface (right end surface in FIG. 1) of the extension portion 11, and one end of the torsion bar 20 is inserted into the small diameter portion of the hole, and one end of the torsion bar is connected to the worm shaft 8 with a pin 21. The inner race 23 of the angular bearing 22 is tightly fitted into the large diameter hole until it reaches its limit position. A stub shaft 25 is rotatably supported within the inner race 23 via a radial bearing 24, and arms 26 and 27 are integrally provided at the left end of the stub shaft 25 in FIG. 29 is made to protrude in the axial direction. The other end of the stub shaft 25 is connected to the valve housing 10 under liquid-tight sealing by a seal 30.
The steering shaft 32 from the steering wheel 31 is connected to this projecting end. The stub shaft 25 is made hollow, the torsion bar 20 is passed through it, and the right end of the torsion bar in FIG.
Combine with 5.

The angular bearing 22 is fitted with its outer race 34 abutting against the step 35 in the valve housing 10, and applies forces in the thrust direction and the radial direction through the balls 36 provided between the inner race 23 and the outer race 34. It can simultaneously support the stub shaft 23 in the radial direction and support the rotating assembly inside the valve housing 10 by the extension part 11 and the end cover 9.
It is supported in the thrust direction together with a thrust bearing 37 inserted between them.

The extension part 11 has a pair of control valves 38 and 39 on both sides of the torsion bar 20.
Insert in the circumferential direction. These control valves 38, 39
have exactly the same structure, and as shown in FIG. 2, the spool guides 41, 41' and the valve spool 40,
40'. Spool guide 41, 4
1' is a retainer 43, an end cover 44,
The end covers 44, 4 are fixed by being pushed into the extension part 11 through the end covers 44'.
4' serves to close the opening at the left end in FIG. 2 of the spool guides 41, 41'. Spool guide 41, 4
The spools 40, 40' are slidably inserted into the spools 40, 40', and the lands 40a, 4 are inserted into the spools 40, 40'.
0'a, 40b, 40'b, 40c, 40'c, 4
0d, 40'd are provided, and the spool guide 41,
41' and chambers 45, 45', 46, 46', 4
7, 47', 48, 48'.

The chambers 45, 45' communicate with the drain passages 49, 49' to form pressureless chambers, thereby allowing the spools 40,
40' is allowed to move to the left in FIG.
46' communicates with the grooves 13, 12 through oil passages 50, 50', chambers 47, 47' communicate with a drain chamber to be described later, and chambers 48, 48' communicate with the grooves 12, 12 through oil passages 51, 51'. 13. Further, the spool lands 40b, 40'b and 40d, 40'd are connected to the spool guide 41 and the variable orifice 52, respectively.
52' and 53, 53' are formed, and the opening degrees of these orifices are reduced when the spools 40, 40' move to the left in FIG.

In the present invention, as shown in FIGS. 2 to 4, lands 40b, 40'b and 40c, 4
0'c, a part of the outer periphery of the spools 40, 40' is cut out in the circumferential direction by, for example, broaching to form notched grooves 54, 54' extending in a direction orthogonal to the torsion bar 20, The bottom surfaces 54a, 54'a are made flat. These notch grooves 5
In order to insert the valve operating pins 28, 29 into the spool guides 41, 41', holes 41a, 41'a are bored into the spool guides 41, 41', and the pins 28, 29 are loosely inserted into these holes. Fit each tip 28
a, 29a into the notch grooves 54, 54'.
Note that the holes 41a and 41'a are the chambers 47 and 4.
7' is also communicated with the drain chamber 55, and this drain chamber is communicated with the oil reservoir 19 through an oil passage 56.

As is clear from FIG. 2 and FIG.
The diameters of the tips 28a and 29a of 8 and 29 are set to be the same, and this interval is set to a high precision on the order of microns,
The pin tip 28 is inserted into the notch grooves 54, 54' as described above.
When a and 29a enter, the tips of these pins are driven into engagement with the spools 40 and 40' in the axial direction without any play. Also, pin tip 2
Ideally, the distance between the grooves 8a, 29a and the bottom surfaces 54a, 54'a of the notch grooves is 0, but in reality, the intersection 40e between both side surfaces of the grooves 54, 54' and the bottom surfaces 54a, 54'a. , 40'e cannot be squared at right angles due to machining, so the pin tips 28a,
29a is removed, the above-mentioned interval is set to a value as close to zero as possible, taking into account this fact and the error. Moreover, even if the above-mentioned interval is set to zero, the pin tips 28a and 29a are connected to the spools 40 and 4.
It is necessary to avoid applying stress in the radial direction to
It is better to keep it away from.

The operation of the operating valve device of the present invention having the above-mentioned structure will be explained next.

When the steering wheel 31 is operated,
This operating force is transmitted to the wormshaft 8 via the steering shaft 32, stub shaft 25, and torsion bar 20, and rotates the wormshaft in a corresponding direction. Therefore, the worm nut 2 is moved in the corresponding direction by the screw action via the ball 7, and the sector gear 3 is thereby rotated in the corresponding direction, thereby achieving steering.

By the way, if the steering load is large during this steering operation,
In response to this, the torsion bar 20 is twisted in the steering direction, and the wormshaft 8, and thus its extension portion 11 and stub shaft 25, rotate relative to each other in the corresponding direction. The operating valve device of the power steering operates as follows due to this relative rotation.

When the steering wheel 31 is steered to the right, the stub shaft 25 rotates relative to the extension portion 11 in the direction of the hour hand in FIG. 2, and the pin 28 moves the spool 40 to the right in the figure.
The pin 29 moves the spool 40' to the left in the figure.
Therefore, the opening degree of the orifices 52 and 53 is increased, and the opening degree of the orifices 52' and 53' is decreased. As a result, the pump pressure that had reached the chamber 14 via the oil passage 17 is reduced to the orifice 53, the oil passage 51, and the groove 1.
2. A large amount of oil is sent into the power cylinder chamber 6 through the oil passage 15, and from the groove 12 communicating with the power cylinder chamber 6, an oil passage 50', an orifice 52', a chamber 47',
Since the drain circuit of the power cylinder chamber 6 which reaches the drain chamber 55 through the hole 41'a (see FIG. 1) is greatly constricted by the orifice 52' as described above, the power cylinder chamber 6 is brought to a high pressure. On the other hand, room 14
The pump pressure supply circuit from the orifice 53' to the power cylinder chamber 5 via the orifice 53', the oil passage 51', the groove 13, and the oil passage 16 is greatly constricted by the orifice 53' as described above, and the line communicating with the power cylinder chamber 5 is Groove 13
From oil passage 50, orifice 52, chamber 47, hole 41
Since the drain circuit of the power cylinder chamber 5 leading to the drain chamber 55 through the drain chamber 55 via the drain circuit a (see FIG. 1) is widened by the above-mentioned increase in the opening of the orifice 52, the power cylinder chamber 5 maintains a neutral pressure-free state. Therefore, the ball nut 2 is power assisted in the steering direction by the pressure difference between the power cylinder chambers 5 and 6, and the steering operation of the steering wheel 31 can be easily performed.

Even when the steering wheel 31 is steered to the left, the stub shaft 25 rotates relative to the extension portion 11 in the opposite direction, and the pins 28 and 29 move the spools 40 and 40' in the opposite direction. By doing so, power assist in the steering direction of the ball nut 2 can be obtained in the same manner as described above, and the steering operation of the steering wheel 31 can be made easier.

By the way, in the present invention, when the spools 40, 40' try to rotate around their axes during the action of the power steering, the bottom surfaces 54a, 54'a of the notched grooves 54, 54' provided in the spools 40, 40' rotate as shown in FIG. 2
As shown by the dotted chain line, at the position where the spools 40, 40' collide with the pin tips 28a, 29a, further rotation is prevented by the pin tips 28a, 29a, making it possible to prevent the spools 40, 40' from rotating. . Note that due to the gaps between the pin tips 28a, 29a and the notch groove bottoms 54a, 54'a, the spools 40, 40' cannot avoid slight rotation;
Compared to the conventional structure in which the spools 40, 40' can freely rotate 360 degrees, the probability of the change in the opening area as described above in Figure 10 is significantly lower, and the flow control characteristics as originally manufactured by the valve can be maintained with a high probability. can do. Moreover, in the present invention, the grooves provided in the spools 40, 40' are notched grooves 54, 5 for this purpose.
4', machining such as broaching is sufficient for machining, and no manual work is required at all, making it possible to process easily and with high precision. Furthermore, the engagement of the spool pin tips can be achieved without any change in the basic arrangement of the spools 40, 40', the valve actuating pins 28, 29, and related parts, and without requiring any design changes. The above effects can be achieved by only slight changes in the shape of the parts.

In the above example, the notched grooves 54, 54' were formed by broaching or the like so that the bottom surfaces 54a, 54'a were flat, but as shown in FIG. 5, the bottom surfaces 54a, 54'a were formed by milling. Of course, the notched grooves 54, 54' may be formed to have curved surfaces concave at the center. In this case, due to the shape of the bottom surfaces 54a, 54'a, the rotation angle of the spools 40, 40' can be reduced as shown by the two-dot chain line, and the desired purpose can be achieved more reliably.

[Brief explanation of drawings]

Fig. 1 is a vertical sectional side view of the operating valve device of the present invention, Fig.
The figure is an enlarged cross-sectional view taken from line A-A in Figure 1 in the direction of the arrow, Figure 3 is a cross-sectional view taken along B-B in Figure 2, Figure 4 is a cross-sectional view taken along CC in Figure 3, FIG. 5 is a sectional view similar to FIG. 4 showing another example of the present invention, FIG. 6 is a sectional view of a main part of a conventional operating valve device, FIG. 7 is a detailed explanatory view of the same, and FIG. Detailed partial explanatory views of other conventional operating valve devices, FIGS. 9a and 9b, and FIG. 10 are explanatory views used to explain the adverse effects caused by rotation of the valve spool, respectively. 1... Steering gear box, 2... Ball nut, 3... Sector gear, 5, 6... Power cylinder chamber, 7... Recirculating ball, 8... Worm shaft, 9... End cover, 10... Valve Housing, 11... Extension part, 12, 13... Groove, 14... Pressure oil supply chamber, 18... Pump, 19... Oil reservoir, 20... Torsion bar, 21, 33... Pin, 22... ... Anguilla bearing, 24 ... Radial bearing, 25 ... Stub shaft, 2
6, 27... Arm, 28, 29... Valve operating pin, 28a, 29a... Pin tip, 31... Steering wheel, 32... Steering shaft, 37... Thrust bearing, 38, 39...
...Control valve, 40, 40'...Valve spool, 40a,
40a'...Pin through hole, 41, 41'...Spool guide, 42...Bolt, 43...Retainer,
44, 44'...End cover, 52, 52', 5
3,53'...variable orifice, 54,54'...
Notch grooves, 54a, 54a'...bottom surface, 55...drain chamber.

Claims (1)

[Scope of Claims] 1. A torsion bar that is twisted in accordance with a steering load is provided, and an extension part that is integrated with an input part of a steering gear that rotates together with one end of the torsion bar has a pair of extension parts that extend perpendicularly to the torsion bar. A control valve spool is provided respectively, and a pair of valve actuation pins rotating integrally with the other end of the torsion bar are respectively extended in a direction parallel to the torsion bar and drivingly engaged with the control valve spool, so as to respond to the torsion of the torsion bar. By moving the control valve spools in opposite directions using the valve actuation pin, pressure oil is supplied to one power cylinder chamber while simultaneously draining the other power cylinder chamber, providing power assistance during steering operations. In the power steering system, a part of the outer periphery of each of the control valve spools is cut in the circumferential direction to form notched grooves extending in a direction perpendicular to the torsion bar, and each of the control valve spools corresponds to the notched groove. A power steering system characterized in that the valve operating pin is drivingly engaged, and the distance between the bottom surface of each notched groove and the tip of the valve operating pin is set to a value as small as possible, including zero, in order to prevent rotation of the control valve spool. operating valve device.