JPH0134825B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control valve that hydraulically supports the steering movement of a steering wheel when the control valve supplies working medium (pressurized fluid) to an unbalanced working cylinder.

In a hydraulic servo steering system, a single hydraulically actuated cylinder is used with a single piston rod extending from only one side of the piston.
May be desirable for structural and cost reasons. This results in different effective piston areas.

A servo steering device with such unbalanced actuating cylinders is known, for example, from West German Patent Publication No.
It is publicly known from Publication No. 1959020. However, this type of servo steering system has the disadvantage of producing asymmetrical steering forces due to the uneven piston areas. For example, if unequal pressures occur in both working chambers, the above-described defects in steering force, etc., will be further compounded. This means that when the driver obtains the same steering force on both the left and right sides, the magnitude of the steering force on the left and right sides is different.

The object of the present invention is to develop a servo steering method and a servo steering device that can prevent asymmetric steering forces from occurring during operation, despite the use of unbalanced actuating cylinders.

According to the present invention, when applying the same operating force to the left and right steering handles, different operations are performed on both piston sides of the operating cylinder so that the hydraulic support forces in the left and right steering directions are equal. The problem is solved by generating pressure.

Until now, equal pressure was always generated in the control valve in both steering directions. In this case, operation takes place with different operating pressures. However, according to the present invention, a non-symmetrical valve retention curve is obtained.

According to the invention, a working chamber with a larger effective piston surface is effectively subjected to a "lower working pressure", so that the resulting piston force is absorbed by the working chamber in the opposite working chamber. The magnitude is equivalent to the piston force.

The present invention includes a control valve having a plurality of control pistons movably disposed within a valve housing such that a control lip is formed intermediate the control pistons and the valve housing. Furthermore, the shapes of the inlet control edge and the return control edge for each working chamber of the working cylinder are formed to be different from each other, so that the control edge for controlling the servo pressure for the working chamber with a large piston area is located in the flow path. configured to exhibit greater aperture resistance.

In this way, the required different pressures for both working chambers can be created in a simple manner.

The method according to the invention can be used with a variety of control valve structures, for example rotary piston valves, axial slider valves, or rotary slider valves.

A configuration according to the invention with differently shaped control edges consists in that the control edge for the working chamber with the larger piston area of the control pistons has a smaller cutout than the control edge for the other working chamber.

Another method according to the invention is that in a rotary piston valve with hydraulic reaction, the piston inserts located at the respective ends of each control piston have different effective diameters. The piston insert disposed in the working chamber having a small piston area is configured to have a small effective diameter.

This method also produces different pressures in each working chamber.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in more detail with reference to embodiments shown in the drawings.

The control valve shown in FIG.
b. These pistons are provided with holes 5 and 6, respectively, into which pins (not shown) engage, which pins each piston 4a,
Operate 4b.

The valve body 2 is provided with a bore 7 through which a torsion rod transmits rotational movement to the rack via a pinion from a steering spin handle (not shown). Such a mechanical connection from the steering wheel to the wheels allows the vehicle to be steered using only manual power in the event of a failure of its hydraulic system. Duct 8
Working medium is introduced into the control valve 1 through. This working medium is supplied to the inlet control edge 9 of the control valve piston 4a.
and the inlet control edge 9' of the control valve piston 4b, and then through the ducts 10 and 10' into the working chambers 11 and 11' of the cylinder 12. As is clear from FIG. 1, the working chamber 11' has a larger effective piston area 110 than the working chamber 11. The working medium also flows back through the branch points 13 to 13', through the reflux control lip 14 of the control valve piston 4b and the reflux control lip 14' of the control valve piston 4a, and through the hole 15a in the valve body 2. It flows back into the duct 15.

Control edges 9' and 14 for controlling the pressure in the working chamber 11'
By having a predetermined notch (exaggeratedly illustrated for convenience), the control edge 9 of the working chamber 11 is
and 14' exhibit a greater throttling resistance and therefore result in less pressure within the duct 10'. By making suitable adjustments, therefore, a uniform hydraulic support in the working direction of both working chambers can be obtained, despite the difference in the piston end areas.

FIG. 2 shows another embodiment of the invention in which the control valve is configured in what is known as an axial spool.

In this control valve, each part corresponding to each part in the embodiment shown in FIG. 1 is designated by the same number.

In this embodiment, the rotational movement of the steering wheel is transmitted to an axially movable control valve piston 4.
In this embodiment as well, the control edges 9' and 14 are
The control edges 9 and 14' also have small recesses, which create a large throttling resistance, which causes the duct 10' to
The desired low pressure is created within.

FIG. 3 shows a reference example of the invention in which the control valve is configured as a rotating spool.

The working medium is introduced through the introduction ducts 8, 8a, 8
b, 8c and then reach the working chamber 11 with a small piston end surface area through three introduction control edges 9 or the working chamber 11' with a large piston end surface area through three introduction control edges 9'.
reach.

Circulation of the working medium takes place through three reflux control edges 14, 14' and three radial holes 15a, 15b, 15c of control valve piston 4 into reflux duct 15, respectively.

As in FIGS. 1 and 2, the control edges 9' and 14 have small recesses to accommodate the large piston area working chamber 11'.

FIG. 4 illustrates a hydraulic reaction rotary piston control valve. In this case, the same numbers were used for the same elements.

In this embodiment, both control valve pistons 4a and 4b are arranged axially displaceably in a cylinder bore, which is closed on one side by piston inserts 20 and 21. An annular chamber 22 and 23 is formed intermediate the two control pistons 4a, 4b and the piston inserts 20, 21, respectively. These annular chambers 22, 23 each have one hole 24 and 25.
are connected to the annular grooves 26 or 27, respectively. Also both control pistons 4a, 4
b is connected at the opposite end with an annular group 28 or 29, respectively. These annular grooves 26, 27 are connected to the pressure chamber 30 when each piston moves away from the piston insert. During a reverse movement of the piston, the annular grooves 28, 29 are closed off from this pressure chamber 30.

The annular chambers 22, 23 are each connected with an opposing annular group 29, 28 (not shown).
The two piston inserts 20 and 21 also have different diameters, as shown in FIG. Therefore, larger diameter piston inserts 20 offer greater resistance to manual forces. Since this insert 20 acts on a working chamber 11' having a large piston area 110, the manual force is converted into "less working pressure" for the large piston area 110.

In FIG. 5, a pressure/rotational moment diagram is shown to clarify the gist of the present invention. y
On the axis is shown the pressure in the cylinder, and on the x-axis is the rotational moment (leftward and rightward) relative to the steering wheel. 30 is a characteristic curve of the large diameter cylinder chamber 11', and 31 is a characteristic curve of the small diameter cylinder chamber 11. As is clear from FIG. 5, these characteristic curves differ in their reference lower portions. That is, with the same rotational moment relative to the steering wheel, the magnitude of the pressure in each cylinder chamber is different between leftward rotation and rightward rotation. That is, the pressure in the small diameter cylinder chamber 11 is increasing. In this way, according to the invention, the pressure difference or the shape of the characteristic curve is selected such that the hydraulic support in both steering directions is equal.

Similar characteristic curves are obtained for planar slide valves. In this case, in order to carry out the invention, it is only necessary to correspondingly design the reaction surface of the flat slide valve according to DE 28 25 006 A1.

[Brief explanation of drawings]

1 is a flow sheet of the device of the invention with a rotating piston type control valve (cross section); FIG. 2 is a similar view to FIG. 1 showing an axial spool type control valve (longitudinal section); FIG. 4 is a view similar to FIG. 1 showing a rotary spool type control valve (cross section), FIG. 4 is a view similar to FIG. 1 showing a hydraulically operated rotary piston type control valve (cross section), and FIG. The figure is a pressure/rotational moment diagram illustrating the operation of the device of the invention. 4a, 4b...control valve piston, 11, 11'
...Working chamber, 12...Working cylinder, 9,9'...
...Introduction control edge, 14, 14'...Recirculation control edge, 2
0, 21... Piston insert, 110... Side having a large piston area.

Claims (1)

[Claims] 1. Supplying pressurized fluid to both pressure chambers of an unbalanced working cylinder that is separated from each other by a piston and located opposite to each other and can supply different pressures, and is slidable within a valve casing. In a control valve for hydraulically supporting the steering movement of a handle, the control valve has a plurality of control pistons arranged in the working chamber of the working cylinder 12, and a control lip is formed between the control piston and the valve casing. The inlet control edge and the return control edge for 11, 11' are formed with different shapes on the control piston, resulting in a large piston area 11.
It is characterized in that the control edges 9', 14 for adjusting the servo pressure for the working chamber 11' with 0. control valve. 2. It is noted that the control edges 9', 14 for the working chamber 11' with the large piston area 110 of the control pistons 4a, 4b have smaller recesses than the control edges 9, 14' for the other working chamber 11. The control valve according to claim 1, characterized in that: 3. A plurality of pressure chambers arranged slidably within the valve casing for supplying pressurized fluid to both pressure chambers of an unbalanced actuating cylinder separated from each other by a piston and located opposite to each other and capable of supplying different pressures. It has a control piston and has a hydraulic return action, in which a control lip is formed between the control piston and the valve casing, and a piston insert 20, 21 is arranged at one end of both control pistons 4a, 4b, respectively. In a control valve for hydraulically supporting the steering movement of a handle with a piston valve, the piston inserts 20, 21 have different effective diameters, the piston insert 21 being associated with the working chamber 11 having a small piston area. A control valve characterized in that it has an effective diameter.