DE102012203387A1 - Valve assembly for hydraulic drive system in mobile working machine, has separate drain valve controlling fluid stream from working connections to tank line, and circulation valve provided for disconnecting and/or releasing pump line - Google Patents

Abstract

The assembly (30) has load assemblies (50) provided with working connections (51, 52) for connecting hydraulic loads (12) i.e. double acting cylinders. A pump line (31) and a tank line (32) are interconnected such that a fluid stream flows from a pump (20) to a tank (11). Separate inlet valves (53, 54) control the fluid stream from the pump line to the working connections. A separate drain valve (57) controls the fluid stream from the connections to the tank line. A separate circulation valve (60) i.e. steady adjustable seat valve, is provided for disconnecting and/or releasing the pump line. The load assemblies are designed in a form of a whole mountable unit.

Description

The invention relates to a valve assembly according to the preamble of claim 1.

From the publication "Hydraulics in Mobile Work Machines" by Bosch Rexroth AG; Issue 05/2001; Chapter 10.2 a hydraulic drive system is known with a valve assembly with a neutral circulation. According to Figure 10.2, the hydraulic drive system comprises three hydraulic consumers in the form of double-acting cylinders. The consumers are connected to a first and a second working port of an associated consumer assembly, which is part of a valve assembly. The consumer assemblies form as a whole mountable units, which are referred to as valve disks due to their external shape.

The valve assembly includes a pump line that passes through all valve assemblies. The pump line is connected to a pump which can deliver hydraulic fluid from a tank into the pump line. Further, the valve assembly includes a tank line, which passes through all consumer assemblies, being connected to the tank.

Each valve assembly provides a continuously variable proportional directional valve with a single valve spool. The proportional directional control valve is connected to the pump and tank lines and to the first and second working ports. By moving the valve spool, the fluid flow to the associated consumer and thus its direction of movement and speed can be controlled. Further, in the proportional directional control valve, a circulation pressure passage is provided which can selectively interrupt or release the pump line in such a manner that the pump line is open when no fluid flow to the associated load, being closed when a fluid flow to the consumers flows , The proportional directional control valves are designed so that the volume flow delivered by the pump remains essentially constant regardless of the position of the proportional directional control valves.

The advantage of this circuit is that it is particularly cost-effective. Further, the user, especially in manual control of the proportional directional valves, well perceive the load acting on the consumers. The disadvantage is that the control notches on the valve spools of the proportional directional control valves must be optimized separately for each application. As a result, the serial production of the valve or the consumer modules is much more difficult.

The object of the invention is to overcome the aforementioned disadvantage. In particular, a valve assembly is to be created, which can be inexpensively manufactured in large quantities.

According to the independent claim, this object is achieved in that at least one consumer module, preferably all consumer modules, a separate first inlet valve for controlling the fluid flow from the pump line to the first working port, a separate second inlet valve for controlling the fluid flow from the pump line to the second working port, a a separate first drain valve for controlling the fluid flow from the first working port to the tank line, a separate second drain valve for controlling the fluid flow from the second working port to the tank line and a separate circulation valve for interrupting or releasing the pump line. Thus, a separate valve is provided for each possible flow path in the consumer assembly. This eliminates the need to match the control notches of the various valves, since each valve can be operated separately from the other valves. As a result, the valve assembly can be manufactured inexpensively in large quantities.

In the dependent claims advantageous refinements and improvements of the invention are given.

The first and the second inlet valve and / or the first and the second drain valve and / or the circulation valve can be designed as a continuously adjustable seat valve. The consumer assemblies each have a blocking position in which no hydraulic fluid flows to the consumers and from these back into the tank. In this blocking position, the consumer should remain in his position. In the known slide valves, however, it comes to leaks, so that the consumers slowly lower by gravity. To avoid this, separate load-holding valves in the form of seat valves are known, which shut off the working connections leak-free. In the valve assembly according to the invention can be dispensed with the separate load-holding valves, as readily all valves of the consumer module can be designed as a seat valve, so that leaks are excluded.

The pump line can be connected via the first inlet valve directly to the first working port, which via the first drain valve is connected directly to the tank line, which is connected via the second drain valve directly to the second working port, which is connected via the second inlet valve directly to the pump line. The inlet and outlet valves are thus interconnected in the form of a bridge circuit. Thus, each of these valves are designed as a 2-way valve, which can be particularly easily formed as a seat valve.

The first and the second inlet valve and the first and the second drain valve can be installed so that their valve seats are pressed by the respective consumer side pressure applied to them in the closed position. This allows a leak-free locking position of the consumer module without the need for additional valves in addition to the valves that are required in any case.

The first and the second inlet valve may be connected on the pump side with respect to the associated circulation valve to the pump line. Thus, the incoming from the pump line fluid flow flows either through the circulation valve or through one of the two inlet valves. By suitable control of said valves, it can thus be achieved that said incoming fluid volume flow can be kept substantially constant. As a consequence, the volume of fluid delivered by the pump can also be kept substantially constant.

The first drain valve can be opened by the consumer-side pressure at the second inlet valve, wherein the second drain valve can be opened by the consumer-side pressure at the first inlet valve. Accordingly, the drain valves open automatically when the inlet valves are operated. The user of the valve assembly must therefore operate as in the known valve assembly only the inlet valve, so that the drain valves are opened accordingly.

The first and second supply valves may have a load pressure port which is disabled when the associated supply valve is closed, being connected to the consumer-side pressure at the associated supply valve when it is opened, the load pressure port thus communicating with the second and the first Drain valve is connected, that it can be actuated by the pressure at the load pressure port. This is then at the load pressure port, when the associated inlet valve is closed, no pressure. The associated drain valve thus remains closed so that the consumer is immovably clamped. The drain valves are preferably pressed by a spring in the closed position.

The load pressure connection can be connected to the tank line via an associated relief throttle. The interconnection of the load pressure port can be realized in a simple manner only in slide construction, wherein the valve stem of the main seat valve acts as a valve spool, which closes the load pressure port or not. Thus, the closed connection to the load pressure connection is not completely leak-free. The leakage currents can flow via the discharge throttle into the tank line, so that no pressure builds up. To increase the reliability of a separate auxiliary tank line may be provided, to which the relief throttles are connected, the auxiliary tank line as the tank line passes through all consumer assemblies and can be connected to the tank.

The valve assembly may be configured to connect the pump and tank at a first end of the valve assembly to the pump and tank conduits, respectively, with the pump and tank conduits connected to one another at the opposite second end of the valve assembly. Thus, the hydraulic fluid fed into the pump line at the first end can flow back into the tank via the tank line if no fluid flows to any consumer. In this case, it is ensured that this circulating fluid flow flows through all the consumer assemblies, so that if necessary, each consumer can be set in motion by controlling the inlet valves without a time offset.

The valve assembly according to the invention is preferably part of a hydraulic drive system, wherein a pump with preferably adjustable displacement volume is connected to the pump line, wherein a tank is connected to the tank line, wherein a consumer is connected to at least one consumer module, preferably to all consumer modules.

The invention will be explained in more detail below with reference to the accompanying drawings. It shows:

1 a circuit diagram of a first embodiment of the invention; and

2 a circuit diagram of a second embodiment of the invention.

1 shows a circuit diagram of a first embodiment of the invention. The hydraulic drive system 10 includes a valve assembly 30 , which consist of two identical consumer modules 50 and an end module 37 is composed. In the valve assembly 30 is a pump line 31 ; a tank line 32 and an auxiliary tanker 33 provided, which all consumer modules 50 push through. At the first end 35 the valve assembly is a pump 20 to the pump line 31 connected, with a tank 11 to the tank and the auxiliary tank line 32 ; 33 connected. At the opposite second end 36 is the final assembly 37 arranged, which the pump line 31 directly with the tank line 32 connects, taking the auxiliary tank line 33 closes tightly at the end.

Each consumer module 50 is designed in the form of a unit that can be assembled as a whole. It has a first and a second work connection 51 ; 52 to which an associated hydraulic consumer 12 can be connected. The consumer 12 is purely exemplified as a double-acting cylinder, wherein a hydraulic motor can be provided.

In the consumer module 50 are a separate first and a separate second inlet valve 53 ; 54 , a separate first and a separate second drain valve 57 ; 58 and a separate circulation valve 60 intended. The inlet and outlet valves 53 ; 54 ; 57 ; 58 are designed as seat valves and are of an associated spring 59 pressed into the closed position. The circulation valve 60 can optionally be designed as a slide or seat valve, wherein it is pressed by a spring in the open position.

The inlet and outlet valves 53 ; 54 ; 57 ; 58 are interconnected in the form of a bridge circuit. Ie that the pump line 31 via the first inlet valve 53 directly to the first work connection 51 connected via the first drain valve 57 directly to the tank line 32 connected via the second drain valve 58 directly to the second work connection 52 connected via the second inlet valve 54 directly to the pump line 31 connected. The inlet and outlet valves 53 ; 54 ; 57 ; 58 are installed so that they each from the consumer-side pressure, ie the pressure at the first and at the second work connection 51 ; 52 be pressed into the closed position, so that the associated consumer 12 immovably clamped. In particular, there is a slow movement of the consumer 12 excluded by leakage currents.

The two inlet valves 53 ; 54 are electromagnetically actuated and have a load pressure connection 55 on. If the inlet valve 53 ; 54 is closed, is also the associated load pressure connection 55 blocked. As soon as the inlet valve 53 ; 54 is also minimally open, is the load pressure connection 55 with the consumer-side pressure at the respective inlet valve 53 ; 54 connected.

The load pressure connection 55 of the first inlet valve 53 is so with the second drain valve 58 connected so that it is opened when at the load pressure port 55 a pressure is applied. The first drain valve 58 is provided with a pilot control, so that the valve tappet against the pressure at the second working port 52 can be safely moved to the open position. The second inlet valve 54 and the first drain valve 57 are connected analog.

So that in the at the load pressure connection 55 Connected connecting lines by leaks no pressure builds up, is any load pressure connection 55 via a discharge throttle 56 with the auxiliary tanker 33 connected. The relief throttle 56 could also with the tank line 32 be connected. However, this has the disadvantage that the large volume flows flowing there create a pressure build-up in the connection between the load pressure connection 55 and associated drain valve 57 ; 58 could cause. This problem occurs in conjunction with the auxiliary fuel line 33 not up.

Now, for example, the first inlet valve 53 opened, so may at first the consumer 12 do not move as the second drain valve 58 is still closed. The pressure in the pump line 31 causes that at the first work connection 51 also builds up a pressure. This pressure in turn opens the second drain valve 58 , In this case, the throttle cross section increases in the second drain valve 58 steadily with the control pressure to a maximum throttle cross-section. Opening the second drain valve 58 In this case, it is preferably at a pressure slightly above zero. This ensures that even when pulling loads on the consumer 12 act, no cavitation in the inlet at the first work connection 51 occurs. The second inlet valve 54 and the first drain valve 57 work analogously, the consumer 12 is moved in the opposite direction.

With the circulation valve 60 can the pump line 31 optionally be enabled or interrupted, the circulation valve 60 is pressed by a spring in the open position. The circulation valve 60 is electromagnetically controlled and in the simplest case with the same signal as the first and the second inlet valve 53 ; 54 , It should be noted that the two inlet valves 53 ; 54 never open at the same time. The first and second inlet valves 53 ; 54 are with respect to the circulation valve 60 Pump side to the pump line 31 connected. This causes the volume flow arriving from the pump line optionally via one of the inlet valves 53 ; 54 to the consumer 12 or via the circulation valve 60 to the next consumer module 50 or to the tank 11 flows. The remains of the pump 20 delivered volume flow independent of the control signals at the various consumer modules 50 essentially constant.

The pump can be a pump with a constant displacement volume, for example an external gear pump. In the first embodiment of the invention, however, one has for a pump 20 With adjustable displacement volume decided to save energy. The displacement volume of the pump 20 is doing by electromagnetic control of the adjustment 23 set. An increase in the drive signal causes an increase in the displacement of the pump 20 and vice versa. In the simplest case, the control signal of the adjustment valve 23 equal to the sum of the amounts of the control signals of the inlet valves 53 ; 54 all consumer modules 50 , This causes the pump when no consumer 12 is moved, has a low displacement volume, so that only a small volume flow in the neutral circulation flows. Once one of the consumers 12 is moved, increases the flow rate of the pump 20 so that the consumer 12 can be moved with the desired movement speed.

The displacement volume of the pump 20 is by means of a single-acting adjusting cylinder 21 adjusted. The from the adjustment valve 23 on the adjusting cylinder 21 set pressure causes an increase in the displacement of the pump 20 while the return spring in the adjusting cylinder 21 causes a reduction of the displacement volume. The adjustment valve 23 connects the adjusting cylinder 21 optionally with the tank or with the delivery pressure of an auxiliary pump 13 , The auxiliary pump 13 with constant displacement volume is thereby from the same drive motor 24 driven like the pump 20 , The delivery pressure of the auxiliary pump is provided with a pressure relief valve 14 set to the desired value. It should be noted that the auxiliary pump 13 in comparison to the pump 20 has a very small flow rate.

2 shows a circuit diagram of a second embodiment of the invention. Apart from the differences described below, the second embodiment is formed identical to the first embodiment, so that in this regard to the comments on 1 is referenced. The same parts are identified by the same reference numerals.

In the final assembly 37 is in the connecting line between pump and tank line 31 ; 32 a circulation throttle 38 built-in. The pump side on the circulation throttle 38 applied pressure is via a control line 34 which covers the entire valve assembly 30 penetrated, with the spring opposite side of the valve spool of the adjusting valve 23 connected. The valve spool of the adjustment valve 23 is pressed by a spring in a first position, in which the adjusting cylinder 21 with the tank 11 connected is. In the second switching position of the adjusting valve 23 that of the pressure in the control line 34 can be adjusted, is the delivery pressure of the pump 20 with the adjusting cylinder 21 connected. The adjusting cylinder 21 is designed as a single-acting cylinder. The from the adjustment valve 23 on the adjusting cylinder 21 provided pressure causes but in contrast to the first embodiment, a reduction of the displacement volume of the pump 20 , The return spring 22 on the adjusting cylinder 21 accordingly causes an increase in the displacement of the pump 20 ,

If none of the consumers 12 is actuated, a pressure drop occurs at the circulation throttle, so that there is also a pressure in the control line. This in turn causes the adjustment valve 23 is switched to the second position, so that the displacement volume of the pump 20 is set small. Once one of the consumers 12 is moved, the associated circulation valve 60 at least partially closed. The delivery pressure of the pump thus falls on the circulation valve 60 and at the circulation throttle 38 As a result, the pressure in the control line 34 sinks. This will be the adjustment valve 23 adjusted to the first position, so that the displacement volume of the pump 20 increases and indeed until the pressure in the control line 34 again the pressure equivalent of the spring on the adjusting valve 23 corresponds, so the adjustment valve 23 is switched back to the second position. The adjustment valve 23 is continuously adjustable, the entire arrangement has an integral control behavior.

LIST OF REFERENCE NUMBERS

10

hydraulic drive system

11

tank

12

consumer

13

auxiliary pump

14

Pressure relief valve

20

pump

21

adjusting cylinder

22

Return spring

23

adjusting valve

24

drive motor

30

valve assembly

31

pump line

32

tank line

33

Auxiliary tank line

34

control line

35

first end of the valve assembly

36

second end of the valve assembly

37

end assembly

38

circulation reactor

50

consumers assembly

51

first work connection

52

second work connection

53

first inlet valve

54

second inlet valve

55

Load pressure connection of an inlet valve

56

relief throttle

57

first drain valve

58

second drain valve

59

Spring on drain valve

60

circulation valve

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited non-patent literature

• "Hydraulics in Mobile Work Machines" by Bosch Rexroth AG; Issue 05/2001; Chapter 10.2 [0002]

Claims (10)

Valve assembly ( 30 ) with a pump line ( 31 ) for connection to a pump ( 20 ) and a tank line ( 32 ) for connection to a tank ( 11 ), wherein the valve assembly ( 30 ) at least one, preferably a plurality of, as a whole mountable consumer modules ( 50 ) with a first and a second working connection ( 51 ; 52 ) for connecting a hydraulic consumer ( 50 ), wherein the pump and the tank line ( 31 ; 32 ) all consumer modules ( 50 ), whereby each consumer assembly ( 50 ) is adapted to remove the fluid flow from the pump line ( 31 ) to the assigned consumer ( 12 ) and from this back to the tank line ( 32 ), whereby the pump and tank line ( 31 ; 32 ) are connected together so that a fluid flow from the pump ( 20 ) to the tank ( 11 ) can flow if to no consumer ( 12 ) flows a fluid stream, characterized in that at least one consumer assembly ( 50 ), preferably all consumer assemblies ( 50 ), a separate first inlet valve ( 53 ) for controlling the fluid flow from the pump line ( 31 ) to the first work connection ( 51 ), a separate second inlet valve ( 54 ) for controlling the fluid flow from the pump line ( 31 ) to the second work connection ( 52 ), a separate first drain valve ( 57 ) for controlling the fluid flow from the first working port ( 51 ) to the tank line ( 32 ), a separate second drain valve ( 58 ) for controlling the fluid flow from the second working port ( 52 ) to the tank line ( 32 ), and a separate circulation valve ( 60 ) for interrupting or releasing the pump line ( 31 ) exhibit. Valve assembly according to claim 1, characterized in that the first and the second inlet valve ( 53 ; 54 ) and / or the first and the second drain valve ( 57 ; 58 ) and / or the circulation valve ( 60 ) are designed as a continuously adjustable seat valve. Valve assembly according to one of the preceding claims, characterized in that the pump line ( 31 ) via the first inlet valve ( 57 ) directly to the first work connection ( 51 ) connected via the first drain valve ( 57 ) directly to the tank line ( 32 ) connected via the second drain valve ( 58 ) directly to the second work connection ( 52 ) connected via the second inlet valve ( 54 ) directly to the pump line ( 31 ) connected. Valve assembly according to claim 3, referring back to claim 2, characterized in that the first and the second inlet valve ( 53 ; 54 ) and the first and the second drain valve ( 57 ; 58 ) are installed so that their valve seats are pressed by the respective consumer side pressure applied to them in the closed position. Valve assembly according to one of the preceding claims, characterized in that the first and the second inlet valve ( 53 ; 54 ) pump side with respect to the associated circulation valve ( 60 ) to the pump line ( 31 ) are connected. Valve assembly according to one of the preceding claims, characterized in that the first drain valve ( 57 ) of the consumer-side pressure at the second inlet valve ( 54 ) can be opened, wherein the second drain valve ( 58 ) of the consumer-side pressure at the first inlet valve ( 53 ) can be opened. Valve assembly according to claim 6, characterized in that the first and the second inlet valve ( 53 ; 54 ) a load pressure port ( 55 ), which is locked when the associated inlet valve ( 53 ; 54 ) is closed, whereby he with the consumer-side pressure on the associated inlet valve ( 53 ; 54 ) is connected when it is open, wherein the load pressure connection ( 55 ) so with the second and the first drain valve ( 58 ; 57 ) is connected by the pressure at the load pressure connection ( 55 ) can be operated. Valve assembly according to claim 7, characterized in that the load pressure connection ( 55 ) via an associated relief throttle ( 56 ) with the tank line ( 32 ) connected is. Valve assembly according to one of the preceding claims, characterized in that the valve assembly ( 30 ) is set up so that the pump ( 20 ) and the tank ( 11 ) at a first end ( 35 ) of the valve assembly ( 30 ) can be connected to the pump or the tank line, the pump and the tank line ( 31 ; 32 ) at the opposite second end ( 36 ) of the valve assembly ( 30 ) are interconnected. Hydraulic drive system ( 10 ) with a valve assembly ( 30 ) according to one of the preceding claims, wherein a pump ( 20 ) with preferably adjustable displacement volume to the pump line ( 31 ), whereby a tank ( 11 ) to the tank line ( 32 ) is connected, wherein at least one consumer module ( 50 ), preferably to all consumer assemblies ( 50 ) a consumer ( 12 ) connected.

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