EP1369596B1 - Hydraulic valve arrangement - Google Patents

Abstract

Hydraulic valve arrangement (1) comprises a supply connection arrangement having a high pressure connection (P) and a low pressure connection, a working connection arrangement having two working connections (A, B), a control valve (3) arranged between the supply connection arrangement and the working connection arrangement, and a shut-off valve (24, 28) for each working connection which is arranged between the control valve and the working connection and has a valve element (25, 29) that is mechanically controlled with the aid of a tappet (36). The tappet ends on its side facing away from the valve element in a pressurized pressure chamber. Preferred Features: The pressure chamber of the tappet for one shut-off valve is defined by the valve element of the other shut-off valve. Both shut-off valves are provided with a common tappet. The tappet is shorter than the distance between the valve elements of the two shut-off valves.

Description

The invention relates to a hydraulic valve arrangement with the features of the preamble of claim 1.

Such a valve arrangement is known from DE 28 01 689 A1. There, a pilot-operated twin check valve is shown, which in each case has a check valve in both working ports. Each check valve has a ball element designed as a valve element, which bears against a valve seat and is held there by the force of a spring. When the pressure on the other side of the valve seat rises and a control valve directs hydraulic fluid under pressure, the ball is lifted off the valve seat and the check valve opens. At the same time a piston is acted upon, which is moved in a different direction. The piston has an extension which lifts the ball of the check valve of the other working line from the valve seat.

Another hydraulic valve assembly is known from DE 40 28 887 A1. There, the plunger is actuated to open the respective check valve via an inclined surface on the slide of the control valve. The opening of the check valve, a return of the motor in a non-deflected or extended state is also possible when the motor acts only a small load, such as its own weight, and this load is so low that they over to the control of the check valve any auxiliary valves can not muster necessary pressure.

A hydraulic valve assembly with check valves is intended primarily for mounting on tractors or other machinery. The check valves should To ensure a possible drip-proof behavior, ie they should keep the motor connected to the working port arrangement in a certain position, if this is so set by the control valve. The check valves are opened by means of a pilot pressure. This is apparent, for example, from DE 199 31 142 A1 or 199 19 015 A1. However, this requires that the engine can produce sufficient pilot pressure.

For double-acting engines (or other consumers), this is usually not a problem, because the motor when it is moved by the pressure at a working port in one direction, automatically generates a correspondingly large pressure at the other working port, which in turn Can open check valves. This does not apply to single-acting engines. As there is only liquid on one side of the engine, it can only be activated in one direction. In order to be able to return to a starting position, it must be influenced in the opposite direction by a load.

One never knows in advance which consumer should be connected to the valve arrangement. The valve assembly must therefore be able to open the check valves in both bidirectional motors as well as unidirectional motors. If, for example, in a tractor the track rail is actuated via the valve arrangement, but no weight rests on the track rail, then there is hardly any load to lower the track rail. The pressure in the tank line should be close to 0 bar, which is usually relatively difficult to implement.

It has therefore been provided in DE 40 28 887 A1 a positive opening of the check valves. When the spool of the control valve is moved in one direction, it provides the necessary hydraulic connections in order to operate the motor in one direction. At the same time, the check valve is opened via the plunger and the slide to allow drainage of the liquid from the opposite pressure chamber of the engine.

However, this training has some disadvantages. First, a relatively large friction between the slide of the control valve and the plunger of the check valve is generated, which is disadvantageous, for example, when the slide is to be electrically operated. In addition, in this embodiment, a partially significant wear is observed, which brings with it the danger that the valve assembly is permanently inoperative.

US 3 795 178 A shows a further hydraulic valve arrangement in which a check valve is arranged in each working line, which has a conical valve element. Again, an actuating piston is provided between the two valve elements having two extensions, each of which cooperates with a valve element of a check valve.

DE 44 36 548 A1 shows a valve arrangement for actuating a hydraulic consumer, in which in both Working lines each a check valve is arranged. The valve elements of the check valves can be pushed open by a piston, which is located between the two check valves. The piston is divided into two parts. With a corresponding pressurization, the two parts can be moved in opposite directions to open both check valves simultaneously and to allow a floating operation.

The invention is based on the object when using a single-acting motor to control the supply serving shut-off valve reliably.

This object is achieved in a hydraulic valve assembly of the type mentioned above with the features of the characterizing part of claim 1.

By the pressurization of the pressure chamber, the plunger is moved and thereby controls the valve element of the check valve. This Aufsteuern therefore no longer requires a deflection of mechanically acting forces. The application of the plunger is hydraulic. However, hydraulic pressures can act largely wear-free on the plunger. Accordingly, the wear is kept small and the check valve can be reliably controlled in the long term. The generation of a pressure on the plunger is comparatively easy. Increased pressure is available in the system anyway. It is necessary to direct this pressure only with suitable measures to the corresponding end face of the plunger.

It is preferred that the pressure chamber of the plunger is limited for a check valve by the valve element of the respective other check valve. With this embodiment, it is achieved that the slide of the control valve (or a corresponding valve element) only needs to be actuated so that the pressure is passed to the second check valve when the first check valve is to be opened. With this embodiment, it is possible to operate the valve assembly optionally with a motor which is arranged on both working ports, or with a motor which is arranged on only one working port and accordingly acts on one side. The free working connection must only be closed in this embodiment. If you now with the help of the control valve, the pressure to se leads closed working port, then although the check valve is opened there. However, the plunger is moved accordingly to also aufzusteuern the check valve at the other working port. The control of the check valve at the closed working port is not critical, because the hydraulic fluid can not escape anyway, regardless of whether the check valve is open or not.

It is particularly preferred that a common plunger is provided for both check valves. The plunger can then open both the one and the other check valve when the pressure is applied to the respective other check valve. The use of a single plunger simplifies the construction. It also has the advantage that you can connect the single-acting engine basically at each of the two working ports, without the function of the valve assembly is adversely affected.

Preferably, the plunger is shorter than the distance between the valve elements of the two check valves. In a mode of operation in which both working connections are connected to the motor, the plunger then does not interfere. While it may be biased to open a check valve when the other check valve is opened by the pressure at the high pressure port routed there through the control valve. In this case, opening the other shut-off valve is required anyway. If the plunger is shorter than the distance between the valve elements of the two check valves, There is definitely a position in which he does not act on both check valves.

Preferably, the valve element and / or the plunger at its common contact surface on at least one formation, which allows the penetration of liquid between the plunger and the valve element. This ensures that the pressure can also act on the corresponding end face of the plunger to relocate the plunger. The plunger can be relatively thin otherwise. The force acting on the plunger need only be sufficient to overcome a force exerted by a closing spring on the valve element of the check valve, for example. Such a configuration may for example be a groove which is arranged in the surface of the valve element of the check valve. It can also be a projection on the front side of the plunger. Other embodiments are conceivable and easily findable for the skilled person.

Preferably, the plunger and the valve elements of the two check valves on a common axis of movement. The plunger and the two valve elements thus move along a straight line. This keeps the wear small. The plunger is loaded only along its direction of movement. The leadership of the plunger in the housing is therefore not burdened by laterally acting forces.

Preferably, the working connection can be connected to a leakage oil removal device. In normal operation, the plunger will have no influence on the valve function. However, to fully ensure that is not unintentional a pressure at the working ports can be established, which then again affects the plunger, the Leckölabführeinrichtung is provided, via which a corresponding excess amount of hydraulic fluid can be removed before the pressure is too high. When the control valve is in the neutral position, then the Leckölabführeinrichtung ensures that a leak can not lead to a pressure build-up at the Arbeitsanschlüssen.

In this case, it is preferred that the leakage oil discharge device has an orifice which forms a connection to the low-pressure connection. By the aperture prevents too much hydraulic fluid can flow at a desired increase in pressure in the corresponding pressure chamber.

Preferably, the diaphragm is arranged in a load-sensing line, which is connected in the neutral position of the control valve to the low-pressure connection. This is a relatively simple design. The load-sensing line is in any case connected to the working connections. This is necessary in order to report the highest pressure occurring in the system to the pump or an associated control device. Now you can give this load-sensing line a second function. It serves namely to dissipate smaller amounts of leakage of hydraulic fluid.

The valve element can be controlled both mechanically with the plunger and hydraulically. The hydraulic opening of the valves typically becomes used at high pressures, for example 10 bar to 400 bar, and large flow rates, whereas where the mechanical solution is used at lower pressures, for example between 0 and 10 bar and small flow rates.

einzige Fig.

einen schematischen Querschnitt durch eine hydraulische Ventilanordnung.

The invention will be described below with reference to a preferred embodiment in conjunction with the drawings. Herein shows the

only Fig.

a schematic cross section through a hydraulic valve assembly.

A hydraulic valve arrangement 1 has a housing 2. In the housing 2, two working ports A, B are provided, which together form a working connection arrangement. Furthermore, there is a high-pressure port P and a low-pressure port, not shown, which together form a supply terminal arrangement. Between the working port arrangement A, B and the supply port P, a control valve 3 is arranged, which has a slide 4 shown only schematically, which is displaceable in a bore 5 in the housing 2 under the action of a drive 6. The bore 5 has a series of circumferential grooves 7-13. The slider 4 has a series of circumferential grooves 14-19. By a displacement of the slider 4, the circumferential grooves 14-19 can be positioned so that certain adjacent circumferential grooves 7-13 are connected in the bore 5 with each other. The representation of the slider 4 with its grooves 14-19 is not to scale. But since the formation of such a control valve 3 is known per se with a slide 4 in a bore, will be omitted for a more detailed explanation.

The circumferential groove 7 is connected via a channel 20 to the output of a compensation valve 21 in connection. The input of the compensation valve 21 is connected to the high pressure port P. The compensation valve 21, which can also be referred to as a pressure compensator or pressure regulator, ensures that the same pressure drop prevails over the control valve 3.

The control valve 3 is connected via a first working line 22 to the working port A in communication and via a second working line 23 to the working port B. In the first working line 22, a first check valve 24 is arranged, which has a valve element 25 which by a compression spring 26 in System is held on a valve seat 27. The check valve 24 can be opened by a pressure prevailing in the working line 22. The prerequisite is that the pressure in the working line 22 is so great that it overcomes the force of the compression spring 26. Of course, there are several different possibilities for the opening of the valves 24 and 28. It is also possible to connect part of the area of the check valve on the load side to low pressure (on the spring side) and at the same time over a range of differences (50) the remaining spring force by means of the load pressure overcome.

Similarly, in the working line 23, a check valve 28 is arranged, which has a valve element 29 which by a compression spring 30 against a valve seat 31 is pressed. The valve member 29 can be lifted from the valve seat 31 when the pressure in the second working line 23 is large enough. The pressure in the two working lines 22, 23 is controlled by the slide 4 of the control valve 3.

Shown is now an operating situation in which only a single-acting motor 32 is connected at the working port A. The engine 32 has a pressure chamber 33 which is bounded by a movable piston 34. If the working line 22 is pressurized by a corresponding position of the slider 4 of the control valve 3, then the check valve 24 is opened and the hydraulic fluid from the working line 22 can flow via the working port A in the pressure chamber 33 of the motor 32.

The other working port B is closed. This is symbolized by a check valve 35.

A return movement of the piston 34 while reducing the pressure chamber 33 is not possible without further measures. When the pressure in the working line 22 drops, then closes the check valve 24 and the working port A is shut off.

For this reason, a plunger 36 is disposed between the two valve elements 25, 29, which is displaceable in a bore 37 in the housing. The axis of the bore and thus also the axis of the plunger 36 coincides with the axis 48 of the valve elements 25, 29 of the check valves 24, 28th

The working line 22 has a first pressure chamber 38 upstream of the check valve 24. The pressure in the first pressure chamber 38 controls the opening movement of the valve element 25 of the first check valve 24. In a similar manner, the second working line 23 before the check valve 28 to a pressure chamber 39. The pressure in the pressure chamber 39 controls the opening movement of the valve element 29 of the second shut-off valve 28.

The plunger 36 now ends in the two pressure chambers 38, 39. The plunger 36 is acted upon by the pressure in the two pressure chambers 38, 39. If the pressure in the second pressure chamber 39 is greater than the pressure in the first pressure chamber 38, then the plunger 36 is displaced in the direction of the valve element 25 of the first check valve 24. If the pressure in the second pressure chamber 39 is sufficient to generate a force greater than the force exerted by the compression spring 26 on the valve element 25 of the first stop valve 24, then the plunger 36 is capable of the valve element 25 from the valve seat 27 and accordingly release a connection from the working port A to the first working line 22.

This can now be exploited to lower the piston 34 of the motor 32.

The slide 4 of the control valve 3 is displaced so that the channel 20 is connected by the compensation valve 21 with the second working line 23. Accordingly, a pressure builds up in the second pressure chamber 39, which displaces the plunger 36 in the direction of the valve element 25 of the first stop valve 24, ie in the drawing to the left, and the valve element 25 lifts off from the valve seat 27 against the force of the compression spring 26. At the same time, the slide 4 has a connection between the first working line 22 and the low-pressure connection, not shown, which may be connected, for example, with the two grooves 10, 11, so that the hydraulic fluid from the pressure chamber 33 of the motor 32 can flow.

The plunger 36 is in the illustrated rest position on the valve member 29 of the second stop valve 28 at. To ensure that hydraulic fluid can pass between the valve member 29 and the plunger 36, the valve member 29 has a formation 40, in the present case a groove, in its surface. This formation 40 does not have to be large. It only needs to be sufficient to exert a pressure on the plunger 36, which is sufficient to lift the plunger 36 from the valve element 29. Thereafter, the entire end face of the plunger 36 is available for pressurization.

The length of the plunger 36 is shorter than the distance between the two valve elements 25, 29. In the rest position so it is quite possible and also provided that the two check valves 24, 28 are closed.

If the terminal arrangement is changed, for example, a two-way motor is connected to the two working ports A, B, then the Plunger 36 is able to open each of the check valve 24, 28, in the pressure chamber 38, 39 is not enough pressure applied to open it. For example, if the working port A is to be pressurized, then a corresponding pressure in the first working line 22 is under the control of the slider 4 of the control valve 3. This pressure is able to open the check valve 24. Simultaneously, the plunger 36 is moved to the right and opens the second check valve 28 so that liquid can flow from the working port B via the working line 23.

The valve assembly 1 is therefore usable without any further conversion measures when a single-acting motor is connected, as well as when a double-acting motor is connected.

In normal operation, the plunger 36 will have no influence on the valve function. However, to completely ensure against the fact that a pressure in the working lines 22, 23 or the working ports A, B can not build up unintentionally, which could open the check valves 24, 28, the working ports A, B via lines 41, 42 with a Load sensing connection LS connected. However, an aperture 43, 44 is provided for each working port A, B in this connection. Via these diaphragms 43, 44, a leakage fluid, which in the neutral position of the slide 4 in the housing 2 into one or both of the working lines 22, 23 flows, drain. The LS line is connected in the neutral position of the slide 4 to the low pressure port.

Of course, other ways of leakage liquid discharge are possible, provided that it is ensured that in the deflected position of the slide 4, in which a corresponding amount of hydraulic fluid to flow under pressure to one of the two working ports A, B, not too much liquid unused flows.

Claims (9)

1. Hydraulic valve arrangement (1) with a supply connection arrangement, having a high-pressure connection (P) and a low-pressure connection, with a working connection arrangement, having two working connections (A, B), with a control valve (3), which is arranged between the supply connection arrangement and the working connection arrangement, and with a non-return valve (24, 28) for each working connection (A, B), said valve being arranged between the control valve (3) and the working connection (A, B), the opening of the valve element of said valve being performed mechanically by means of a tappet (36) against the force of a spring (26, 30) acting upon a spring side, the side of the tappet (36) facing away from the valve element (25, 29) ending in a pressure chamber (38, 39), which can be acted upon by a pressure, characterised in that the spring side of the valve element (25, 29) can be connected to low pressure and a differential area (50) can be acted upon by a load pressure acting against the spring force, so that with small pressures the valve element is opened mechanically by the tappet (36) and with high pressures the valve element is opened hydraulically.
2. Valve arrangement according to claim 1, characterised in that the pressure chamber (38, 39) of the tappet (36) for one non-return valve (24, 28) is limited by the valve element (29, 25) of the other non-return valve (28, 24).
3. Valve arrangement according to claim 1 or 2, characterised in that a common tappet (36) is provided for both non-return valves (24, 28).
4. Valve arrangement according to claim 3, characterised in that the tappet (36) is shorter than the distance between the valve elements (25, 29) of the two non-return valves (24, 28).
5. Valve arrangement according to claim 3 or 4, characterised in that the valve element (25, 29) and/or the tappet (36) have on their common contact face at least one recess (40), which permits the penetration of fluid between the tappet (36) and the valve element (25, 29).
6. Valve arrangement according to one of the claims 1 to 5, characterised in that the tappet (36) and the valve elements (25, 29) of the two non-return valves have a common movement axis (48).
7. Valve arrangement according to one of the claims 1 to 6, characterised in that the working connection (A, B) can be connected to a leakage oil discharge arrangement (41 to 44).
8. Valve arrangement according to claim 7, characterised in that the leakage oil discharge arrangement (41 to 44) has a bleed (43, 44), which creates a connection to the low-pressure connection.
9. Valve arrangement according to claim 8, characterised in that the bleed (43, 44) is arranged in a load-sensing line (LS), which is connected to the low-pressure connection in the neutral position of the control valve (3).

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