EP2126371B1 - Valve arrangement - Google Patents

Abstract

The invention relates to a valve arrangement having an adjustable control valve (10), comprising a control slide (12) for actuating at least one consumer connection (A,B), and having an LS control line, wherein the differential pressure of two actuating pressures (Xa, Xb) serves for the actuation of the control slide (12). Due to the fact that the actuating pressures (Xa, Xb) also actuate a logic valve, which in turn influences an additional valve, and/or actuates a pressure scale that is connected upstream to the control valve (10) having the control slide (12), the difference of the two actuating pressures (Xa, Xb) initially displaces the control slide of the control valve, wherein the higher or the lower of the two actuating pressures (Xa, Xb) either actuate the further valve in the form of the additional valve, and/or influences the pressure scale.

Description

The invention relates to a valve arrangement having an adjustable directional control valve with a control slide for driving at least one load connection and with a LS control line, wherein the differential pressure of two control pressures x _a , x _b is used to drive the control slide, wherein the control pressures additionally control a logic valve, which in turn acts on an additional valve and / or controls a pressure compensator, wherein the pressure compensator is connected upstream of the directional control valve with a control slide between a pressure supply and an input side of the directional control valve and connected on its one control input side to a pertinent supply line.

Such a valve arrangement is made US 5,134,853 A such as DE 689 10 940 T2 known. The known valve arrangement is part of a hydraulic drive unit for construction machines with a plurality of hydraulic actuators, which are operated by a pumped by the hydraulic pump hydraulic fluid. For example, a first flow control valve for controlling the flow of hydraulic fluid supplied to a swing motor and a second flow control valve for controlling the flow of the hydraulic fluid supplied to a boom cylinder at predetermined pilot pressures are used.

In operation, the discharge amount of the hydraulic pump for keeping constant the differential pressure between the pump discharge pressure and the maximum load pressure is controlled by a load detection control, so that the swinging motor and the boom cylinder obtains a delivery rate corresponding to the opening degree of the flow control valve. In the combined operation of swivel body and boom cylinder, the pilot pressure for driving the oscillating motor associated first flow control valve is connected via a shuttle valve with a multi-way valve, whereby the multi-way valve is switched to another position and in this other position, the distribution cylinder associated with the distribution compensating valve with a control force such is that both hydraulic actuators are connected in parallel.

Valve arrangements are increasingly being realized in the form of modular valve construction kits, which open up the possibility, in addition to the realization of standard variants, to record a certain number of special variants with. As a rule, the pertinent special variants not only increase the design cost of construction for the variant itself, but also the volume of space available within the standard valve assembly for this purpose.

A typical case with electrically controlled valves is the user's desire to be able to perform a pressure or independent switching function in addition to the control of the directional control valve. For example, the function "quantity cutoff" is desired, in which, by limiting the pressure in the feedforward control of a section pressure balance, the standard cross section of the pressure compensator in the inflow to the gate valve of the directional control valve is closed. Solutions today are common in which such valves are offered with screws, by means of which the maximum inlet pressure to the two service connections (pipe connection) A or B or A and B can be set. The adjustment of the screws is done regularly by hand, which is associated with interruptions in work on the machine.

An electrical adjustment by adjusting a potentiometer would thus already be a desirable improvement, to the extent known in the art mobile valves series, but need to implement such an electrical adjustment function, a third proportional solenoid, in turn, takes a lot of installation space on the respective work machine. Furthermore, this adds an additional wiring effort for the realization of the required bus technology.

By the EP 0 935 713 B1 a valve arrangement for controlling a consumer is known with a feed throttle acting as a continuously adjustable directional control valve, via which a pump connection with consumer connections A, B is connected, wherein the respective consumer is connected via working lines to the directional control valve and in each working line a throttle device is arranged over the drain volume flow of the hydraulic oil is adjustable by the consumer. Characterized in that in the known solution in each case a control side of the throttle means and a control side of the directional control valve via a control channel, each having a control unit, wherein by means of the two control units, the control pressures in the two control channels are independently adjustable so that when adjusting the inlet flow both Control pressures are greater than zero and the drain-side throttle device is completely aufsteuerbar regardless of a valve spool position of the directional control valve, a valve assembly is provided in which the energy losses in the flow of a consumer can be reduced to a minimum with minimal device complexity. The hydraulic volume flow is set via a directional valve acting as inlet throttle.

The throttle device thus has in the known solution to two return throttles, which are each assigned to a user port A or B. Each pertinent return throttle is provided with a tank port T and there is a permanent connection between the return throttles and the respective assignable control pressures x _a , x _b , which act as a control pressure in the opposite direction to the spool with inlet orifice of the directional control valve. The pertinent way valve has so far no tank connection T. Thus, in the known solution in addition to the spool of the directional control valve, the respective return throttle is controlled via a total of two independent proportional magnets, which provide the said control pressures x _a , x _b available. The summarized in a valve block known valve assembly in turn is relatively large.

By the DE 10 2005 050 169 A1 a LS control arrangement with a directional control valve is known, via its valve slide when set in one direction, a first consumer port A and setting in the other direction, a second consumer port B with a supply port P and the other consumer port to a drain port T are connectable, wherein via an inlet control edge, an opening cross-section of a Zulaufmeßblende is determined, which in turn is associated with an individual pressure compensator to keep the pressure drop across the Zulaufmeßblende, and with a LS Steuerölströmungspfad through which the load pressure downstream of Zulaufmeßblende tapped and through the valve spool into a LS control chamber of the Directional valve is signalable, wherein a maximum pressure in the LS control oil flow path can be limited via a pressure relief valve. In that, in the known solution, the LS control oil flow path during adjustment of the valve spool in one direction successively or overlapping with two pressure limiting chambers is connected to each of which a pressure relief valve is assigned to the LS-pressure limitation, a multi-stage supply pressure limit is possible and the load pressure can be limited to different values in different Hubbereichen the valve spool, which for certain tasks in mobile Working equipment is advantageous; stepless adjustment operations are not possible with the known solution.

Based on this prior art, the invention is based on the object to further improve the known solutions to the effect that a continuous adjustment of the valve assembly is possible and that this requires little installation space. A related object solves a valve assembly with the features of claim 1 in its entirety.

According to the characterizing part of patent claim 1, a valve arrangement according to the invention is characterized in that the pressure compensator on the counter-acting control input side is connected to the additional valve such that it is connected to a junction in which the LS control line opens and a fluid connection for the Additional valve in the form of a LS pressure relief valve, wherein the LS control line is provided with a throttle or a diaphragm (variant 1), or that it is connected via a connecting line to the additional valve in the form of a LS pressure control valve, wherein in an additional supply line of the supply line to the connecting line an additional orifice or throttle is inserted and the LS control line is connected via a pressure sensor to a valve electronics (variant 2), and that the logic valve is designed as an inverted acting shuttle valve. Characterized in that the control pressures x _a , x _b additionally control a logic valve, which in turn acts on an additional valve and / or controls a pressure compensator, which is connected upstream of the directional control valve with spool, the difference of the two control pressures x _a , x _b moves first the Spool of the directional control valve, wherein the lower of the two control pressures x _a , x _b either the further valve activates in the form of the additional valve and / or acting on the pressure compensator. The two proportional solenoids, which are preferably provided for providing the actuation pressures x _a , x _b , are operated simultaneously, wherein the selection of the higher or lower pilot pressure as actuation pressure x _a , x _{b is} effected by a logic valve which is embodied according to the invention in the manner of an inverted shuttle valve.

In a first variant of the valve arrangement according to the invention, the additional valve is an LS pressure limiting valve LS-DBV in the valve section. Since the control of a high-pressure pressure relief valve is carried out with low pressure, preferably a pressure booster stage is interposed.

With the solution according to the invention can save space and with only a few functionally reliable components, the so-called. "Mengenabschneidung" electrically make and set. Another application is the so-called. Pad pressure control, in which the bearing force of a working device can be reduced, which plays a role in mowing bar of slope mowers, winch guides of combines and so-called. Packers on tractors etc ..

Further advantageous embodiments are the subject of the other dependent claims.

Fig.1 bis 4

vier voneinander verschiedene Ausführungsformen der erfindungsgemäßen Ventilanordnung, wobei die Fig.1 den prinzipiellen grundsätzlichen Aufbau der Ventilanordnung betrifft.

In the following the valve assembly according to the invention will be explained with reference to various embodiments according to the drawings. This show in a schematic representation in the manner of schematics the

Fig.1 to 4

four different embodiments of the valve assembly according to the invention, wherein the Fig.1 concerns the basic basic structure of the valve assembly.

That's how it shows Fig.1 a valve arrangement with an adjustable directional control valve 10 with a control slide 12 (FIG. Fig.2 ff) for driving two consumer connections A, B. The structure of such adjustable directional control valves 10 with spool 12 is in the prior art ( EP 0 935 713 B1 . DE 10 2005 050 169 A1 ) is well known, so that will not be discussed here at this point. The directional control valve 10 is further connected to a pressure supply source P, for example in the form of a constant pressure pump, which withdraws from a reservoir, for example in the form of a tank, hydraulic medium, which flows back through a tank port T after passing through the hydraulic circuit back into said reservoir. In the present exemplary embodiments of the valve arrangement according to the invention, inter alia, there is a special feature in that the directional control valve 10 has a tank connection T that is provided.

Furthermore, the directional control valve 10 has an LS control line, which is shown in the figures with LS. For driving the spool 12, the differential pressure of two control pressures x _a , x _{b is} provided, in the usual and therefore unspecified manner via two pilot valves 14,16 are given. The pilot valves 14,16 are in the Fig. 2ff shown, wherein the connection ST the control pressure (usually 20 to 40 bar) referred to in the control oil circuit, which serves in particular the supply of unspecified low-pressure consumer. Furthermore, the LS control line is according to Fig.1 to 3 provided with a throttle or aperture 18.

As the Fig.1 further shows, the two driving pressures x _a , x _b not only in the opposite direction to the spool 12 of the directional control valve 10, but are also connected in opposite direction of action to a logic valve 20, which acts as a shuttle valve and according to the present embodiments as inverted Shuttle valve is formed. The control pressure acting on the spool 12 x _a allows the fluid-conducting connection between the terminals P and A and the control pressure x _b acts on the spool 12 in the opening direction of the ports P and B to be interconnected. Does not apply a triggering pressure x _a , x _b or cancel the Actuation pressures x _a , x _b from each other on their differential pressure, the spool 12 assumes its spring-centered position, as in the Fig.2ff represented, which is also referred to the neutral position of the directional control valve 10.

To the logic valve another valve in the form of an additional valve 22 is connected, which is designed as a pressure relief valve DBV. Prior to the pressure relief valve DBV the input side, a pressure booster stage 24 is connected, which makes it possible to bring the input pressure from the output side of the logic valve 20 to a higher pressure relative to the input side of the additional valve 22. In this way, in order to obtain improved drive efficiency, it is possible to use the lower pilot pressure x _a or x _b for driving the additional valve 22. With the basic circuit after the Fig.1 In principle, it is possible to carry out the "quantity cut" described in the introduction in a stepless manner and / or to achieve a perceptible contact pressure control for a working equipment, connected to the user or consumer connections A, B. According to the invention, however, is provided, in addition to the logic valve 20 and the additional valve 22 as shown in the Fig.2 on the pump input side of the directional valve 10 between the pressure supply source P and the pertinent input of the directional control valve 10 to connect a pressure compensator 26 which is connected on its one control input side to the pertinent supply line 28 and on the counter-acting control input side this is according to the first embodiment (variant 1 ) connected to a node 30, in which the LS control line opens and a fluid connection for the additional valve 22 in the form of a pressure relief valve with connected pressure translation stage 24. According to the circuit diagram of the Fig.2 is achieved with the pertinent valve assembly, an electrically controllable "Mengenabschneidung" with two simultaneously operated proportional pilot valves 14,16.

In the present embodiment, the additional valve 22 is designed as a so-called. LS-pressure relief valve (LS-DBV) and is fed by the LS-pressure of the LS control line and controls, as stated, so far the the control spool 12 of the directional control valve 10 upstream section pressure compensator 26 at , The LS-DBV is driven by the lower of the two driving pressures x _a , x _b on its spring side, again selecting the driving pressures x _a , x _b by the inverted shuttle valve as a logic valve 20. Since usually the spool 12 is deflected with a lower control pressure x _a , x _b , this low pressure must also control the high-pressure LS-DBV as an additional valve 22. Serves for this purpose the pressure booster stage 24, which is connected between control pressure and so-called spring chamber of the LS-DBV, wherein the pressure booster piston (not shown) is designed such that it rests with its large area at the control pressure and the small area abuts against the spring chamber of the LS-DBV. With the pertinent structure, the electrically adjustable Mengenabschneidung is possible in an advantageous manner.

The following embodiments will be explained only insofar as they differ significantly from the preceding embodiments. In this case, the same reference numerals are used for the same components of the valve assembly and the previously made statements apply also to that extent for the still to be presented embodiments of the Fig. 3 and 4 ,

For a contact pressure control, the valve assembly according to the Figure 3 for the section pressure compensator 26, a tank connection T on. The pertinent T-port of the pressure compensator 26 can only be opened when the pressure compensator piston 32 has already almost closed the supply channel P (supply line 28) or just closed or already closed when moving against the control spring 34. This can not only a pressure relief in the inlet to the respective pipe connection (user port A, B) can be achieved, but also a pressure control. In such a case, the contact force of a work implement, not shown, a work machine can be reduced to the ground by the open-ended spool 12, the section pressure compensator 26 on the one hand a volume flow to the respective Nutzanschluß A, B but also from the respective Nutzanschluß A, B can control to the tank port T. , With the embodiment of the Figure 3 So is an electrically controllable Mengenabschneidung possible with pad pressure control.

In the second embodiment of the Figure 4 (Variant 2) eliminates the node 30 with throttle or fixed orifice 18 and the LS control line is connected via a pressure sensor 36 to a microprocessor or microcontroller MC a valve electronics not shown. However, the control input sides are the pressure compensator 26 connected to the supply line 28, wherein in one of the supply lines, an additional aperture or throttle 38 is inserted. About said throttle 38, the said supply line opens into a connecting line 40 between the additional valve 22 and a drive side of the pressure compensator 26. Accordingly, the further valve is designed as an additional valve 22 in the form of a so-called. LS pressure control valve, which is not the LS pressure in the LS Control line, but is fed by the pressure of the pressure supply source P and thus generates an artificial load pressure in the spring chamber of the section pressure compensator 26, which can be varied from zero to Pmax. Regardless of the actual load pressure, the pressure difference can thus be adjusted almost arbitrarily by electrical means. In this way, an extreme fine control at low pressure difference and maximum pumping amount via the section at maximum pressure difference is possible. The measurement of the load pressure is carried out via a pressure sensor 36, which forwards the pressure value to a microprocessor or microcontroller MC as part of an unspecified valve electronics. The valve electronics then control the low control pressure after specification of an external setpoint and simultaneously corrects the higher control pressure by the zero-point correction of the lower control pressure.

A further advantageous application of the pertinent solution is to provide a control block not shown in detail of a specific nominal diameter, in which only a single consumer connection (user port A, B) requires a larger nominal diameter. Then, for cost-saving reasons, the smaller control block can be maintained, because the necessary large amount can be achieved via a high pressure difference across the metering orifice formed by the inlet side of the valve spool 12 (input of the supply line 28).

Claims (6)

1. A valve arrangement

   - comprising an adjustable directional control valve (10) comprising a control slide (12) for actuating at least one consumer connection (A, V), and

   - comprising an LS control line, a logic valve (20), an additional valve (22) and a pressure compensator (26),

   - the pressure difference of two actuating pressures (x_a, x_b) being used to actuate the control slide (12),

   - the actuating pressures (x_a, x_b) additionally actuating the logic valve (20) which in turn acts on the additional valve (22) and/or actuates the pressure compensator (26),

   - the pressure compensator (26) being connected upstream from the directional control valve (10) with a control slide (12) between a pressure supply (P) and an input side of the directional control valve (10) and being connected on its one control input side to a supply line to this effect (28),

   - characterised in that the pressure compensator (26) on the control input side acting in the opposite direction is connected to the additional valve (22) such that

   - said control input side is connected at a nodal point (30) into which the LS control line discharges and a fluid connection for the additional valve (22) in the form of an LS pressure limitation valve, the LS control line being provided with a throttle or a diaphragm (18), or that the valve arrangement further comprises a pressure sensor (36) and valve electronics and

   - that the pressure compensator (26) is connected by means of a connection line (40) to the additional valve (22) in the form of an LS pressure regulating valve, an additional diaphragm or throttle (38) being inserted into an additional delivery line from the supply line (28) to the connection line (40), and the LS control line being connected to the valve electronics by the pressure sensor (36), and

   - that the logic valve (20) is in the form of a selector valve acting in an inverted manner.
2. The valve arrangement according to Claim 1, characterised in that the additional valve (22) can be actuated by means of a pressure intensification stage (24) which acquires its input pressure from the output side of the logic valve (20).
3. The valve arrangement according to any of the preceding claims, characterised in that the LS control line is connected by means of the pressure sensor (36) to a microprocessor (MC) of the valve control electronics.
4. The valve arrangement according to any of the preceding claims, characterised in that the actuating pressures (x_a, x_b) can be dictated by one separately acting pilot valve (14, 16) at a time.
5. The valve arrangement according to Claim 3 or 4, characterised in that the microprocessor (MC) of the valve control electronics actuates the two pilot valves (14, 16).
6. The valve arrangement according to any of the preceding Claims, characterised in that the adjustable directional control valve (10) has at least one tank connection (T).

Images