SWITCH VALVE BLOCK FOR A HYDRAULICALLY ACTUATABLE WORKING MACHINE

Abstract

The present invention relates to a switching valve block for a hydraulically actuable work machine that comprises a plurality of valve block inputs for a respective connection to a pressure output of one or more hydraulic fluid pumps, a plurality of valve block outputs for outputting a pressurized hydraulic fluid, and at least one valve that is arranged between valve block inputs and valve block outputs and is adapted to selectively produce a fluid connection between a first valve block input and a first valve block output or between a first valve block input and a second valve block output. The invention is characterized in that the first valve block output furthermore already has a fixed fluid connection to a second valve block input.

Claims

1. A switching valve block for a hydraulically actuable work machine comprising: a plurality of valve block inputs for a respective connection to a pressure output of one or more hydraulic fluid pumps; a plurality of valve block outputs for outputting a pressurized hydraulic fluid; and at least one valve that is arranged between valve block inputs and valve block outputs and that is adapted to selectively produce a fluid connection between a first valve block input and a first valve block output or between a first valve block input and a second valve block output, wherein the first valve block output furthermore already has a fixed fluid connection, preferably a fixed exclusive fluid connection, to a second valve block input.

2. A switching valve block in accordance with claim 1, wherein the at least one valve is a switching valve that exclusively connects one valve block input to one of the plurality of valve block outputs.

3. A switching valve block in accordance with claim 1, wherein the at least one valve is adapted to be connected at any time during a switching procedure to one or even to both of the valve block outputs to be switched over to avoid pressure peaks during the switching over of the hydraulic fluid.

4. A switching valve block in accordance with claim 1, wherein the second valve block input furthermore already has a fixed fluid connection to a third valve block input.

5. A switching valve block in accordance with claim 1, wherein every valve block output already has a fixed, in particular exclusive, fluid connection to a respective valve block input and furthermore at least one additional fluid connection can be connected to a valve block input via the at least one valve, in dependence on its switching position.

6. A hydraulic system having a valve switching block in accordance with claim 1, further comprising: a plurality of pressure sources, preferably a plurality of separately controllable pressure sources of which each one is connected to a respective valve block input; and a plurality of hydraulic consumers of which each one is connected to a respective valve block output.

7. A hydraulic system in accordance with claim 6, wherein the plurality of pressure sources are a plurality of hydraulic fluid pumps that are independent of one another and/or a plurality of pressure outputs of one or more hydraulic fluid pumps, with preferably the plurality of pressure sources being controllable separately from one another.

8. A hydraulic system in accordance with claim 6, wherein the hydraulic consumers comprise a steering cylinder for steering a work machine, a tilt cylinder for tilting a work machine part, and/or a lifting cylinder for lifting a work machine part, and provision is preferably made for at least one further control circuit for a hydraulic consumer that fluidically starts at a control circuit for the steering cylinder or for the tilt cylinder.

9. A hydraulic system in accordance with claim 6, further comprising a control unit for switching the at least one valve and/or the hydraulic fluid delivery rate of the plurality of pressure outputs.

10. A hydraulic system in accordance with claim 9, wherein the control unit is adapted to set the switching position of the at least one valve and/or the hydraulic fluid delivery rate of the plurality of pressure outputs in dependence on an operator input for actuating one of the plurality of hydraulic consumers.

11. A work machine, in particular a wheeled loader, having a switching valve block in accordance with claim 1.

12. A work machine in accordance with claim 11 that is adapted to actuate each of the at least two hydraulic consumers, in particular tilting and lifting, and the steering by hydraulic fluid that flows through a respective valve block output.

13. A work machine in accordance with claim 11, wherein the fluid current present at the valve block output corresponds to the sum of the individual volume flows of the plurality of valve block inputs that have a fluid connection to the valve block output, with the high pressure that is applied to the plurality of valve block outputs preferably corresponding at the valve block output.

14. A work machine in accordance with claim 11, further comprising an engine for driving the one or the plurality of hydraulic fluid pumps, with a transfer case preferably being provided between the engine and the one or the plurality of hydraulic fluid pumps.

15. A work machine in accordance with claim 11, further having two pumps in a tandem arrangement that respectively has four pressure outputs, preferably four pressure outputs controllable separately from one another.

16. A switching valve block in accordance with claim 2, wherein the at least one valve is adapted to be connected at any time during a switching procedure to one or even to both of the valve block outputs to be switched over to avoid pressure peaks during the switching over of the hydraulic fluid.

17. A switching valve block in accordance with claim 16, wherein the second valve block input furthermore already has a fixed fluid connection to a third valve block input.

18. A switching valve block in accordance with claim 3, wherein the second valve block input furthermore already has a fixed fluid connection to a third valve block input.

19. A switching valve block in accordance with claim 2, wherein the second valve block input furthermore already has a fixed fluid connection to a third valve block input.

20. A switching valve block in accordance with claim 17, wherein every valve block output already has a fixed, in particular exclusive, fluid connection to a respective valve block input and furthermore at least one additional fluid connection can be connected to a valve block input via the at least one valve, in dependence on its switching position.

Description

[0044] Further features, details and advantages of the invention will become clear with reference to the following description of the Figures. There are shown:

[0045] FIG. 1: a schematic representation of a hydraulic system in accordance with the prior art;

[0046] FIG. 2: a schematic representation of a hydraulic system in accordance with the invention;

[0047] FIG. 3: a schematic representation of a further embodiment of the hydraulic system in accordance with the invention;

[0048] FIG. 4: a schematic representation of a further embodiment of the hydraulic system in accordance with the invention;

[0049] FIG. 5: a schematic representation of a further embodiment of the hydraulic system in accordance with the invention;

[0050] FIG. 6: a schematic representation of a further embodiment of the hydraulic system in accordance with the invention; and

[0051] FIG. 7 a schematic representation of a valve of the switching valve block.

[0052] FIG. 1 shows a schematic representation of a hydraulic system in accordance with the prior art. An engine 1 can be recognized that drives two pumps 3 via a transfer case 2. One of the two pumps 3 is here connected to a steering control 4 that distributes the fluid pressure provided by the pump 3 and the provided fluid amount for actuating the steering cylinder 6.

[0053] The other one of the two pumps 3 is in contact with a tilting and lifting control 5 that controls the actuation of a tilt cylinder 7 and of two lifting cylinders 8. It was already initially mentioned that it is disadvantageous if a pump (the lower of the two pumps 3 in FIG. 1) has to provide the fluid capacity for a plurality of consumers, here the tilting and the lifting, since this represent an inefficient operation.

[0054] Although a valve block input and a valve block output are consistently spoken of in the claims, it is clear to the skilled person that a direct connection, for example from the pressure source P1, while bypassing a physically formed switching valve block, to a hydraulic consumer is likewise covered by the protective scope of the present invention. The switching block and also the valve block input and output are structures that are to be defined in the abstract so that a direct connection of a pressure source to a hydraulic consumer, in particular to a steering control, also falls within the protective scope of the present application. The direct switching through via a (physical) switching valve block does not necessarily have to take place. It is important for the invention that the hydraulic consumer is linked to a direct connection of a pressure source so that fluid flowing out thereof is directly available.

[0055] FIG. 2 shows an embodiment of the present invention. An engine 2 is likewise provided there having a corresponding transfer case 2 and a shaft projecting therefrom at which a plurality of pressure sources 31-38 are arranged that are controllable independently of one another. In the present case, these eight pressure source 31-38 operable independently of one another are implemented by two pumps 3, 3 arranged in tandem operation, of which each one has a plurality (four in the present case) of separately controllable pressure fluid outputs. Each of the total of eight pressure fluid outputs is here connected to its own, associated valve block input 11 that is either directly linked to a valve block output 12 or is guided to a valve (=also switching valve).

[0056] In the present FIG. 2, all the pressure fluid outputs 32-38 of the pumps 3, 3 except for one are connected to a switching valve 10. Only the pressure fluid output 31 is directly connected, without a switch, to a valve block output 12 that is guided to the steering control 4. In other words, it is thus ensured that the steering control 4 has the pump capacity of the pressure source 31 permanently and independently of a switching position of the switching valves 10 in the switching valve block 9. If a pump capacity going beyond this is required by the steering control, the switching valves V1 and V2 can be switched such that their associated pressure sources 32, 33 likewise provide their power to the steering control. Three pump sources 31, 32, 33 are thus available in total as required to perform the steering control 4.

[0057] The control valve block 5 in which the hydraulic consumers tilting 51 and lifting 52, as well as further consumers 53, 54 not mentioned by name, are arranged are arranged beside the switching valve block 9 on the right side of FIG. 2. With a corresponding valve setting of the switching valves V1 to V7 in the switching valve block 9, the tilt control 51 can be linked to all the pressure sources 31 to 38 so that sufficient power is present for the tilt function for the actuation of the tilt cylinders 7.

[0058] The situation is similar with the lifting control 52 that is likewise connectable to the associated pressure sources 33 to 38 with a corresponding position of the valves V2 to V7. The lifting control 52 can here also forward pump capacity to the further consumers 53, 54 that are not shown in detail for reasons of a simplified illustration.

[0059] The pump capacity of the plurality of pressure sources can accordingly also be guided to a respective consumer 6, 7, 8 by the invention in dependence on a current demand, with the disadvantages of a poor response behavior typically accompanying this being alleviated in that particularly sensitive consumers, for example the steering, are permanently and exclusively connected to a pressure source (the pressure source 31 here).

[0060] FIG. 3 shows a further embodiment of the present invention in which not only the steering control 4 has an exclusive pump capacity, but also the lifting control 52. In this respect, the pumps P7 and P8 are exclusively and unchangeably associated with the hydraulic consumer “lifting” to actuate the lifting cylinders 8. In a similar manner as in FIG. 2, is it also possible to add four further pressure sources P3 to P6 via a corresponding switching of the valves V3 to V5 so that challenging lifting work can also be accomplished.

[0061] The tilt control 51 can be connected to a total of four pressure sources P2 to P4 and P6 with a corresponding valve position of the valves V1-V3 and V5. It is likewise possible that the further consumers 53 and 54 are supplied via the tilting control 51 (and not, as shown in FIG. 2, via the lifting control 52).

[0062] FIG. 4 shows a modification of FIG. 3 in which the pressure source P7 is no longer fixedly connected to the lifting control, but rather supplies the pressure power of the pressure source P7 to the lifting control 52 or to the tilting control 52 depending on the position of the valve V6.

[0063] FIG. 5 shows a further modification of the invention, wherein now each of the three hydraulic consumes of steering control, tilting, and lifting is fixedly connected to their own pressure sources. The steering control is thus connected to the pressure source P1, the tilting control is connected to the pressure source P2, and the lifting control is connected to the pressure sources P7 and P8. Three of the plurality of valve block outputs are thus now directly and fixedly linked or connected to a valve block input so that no switch or the like is arranged in a fluid connection between the valve block input and the valve block output.

[0064] FIG. 6 shows a further embodiment of the invention in which the pressure source P1 is associated with the steering control 4, the pressure source P2 is associated with the tilting control, and the pressure source P8 is associated with the lifting control The other still remaining pressure sources P3 to P7 can here be respectively assigned to one of two hydraulic consumers with the aid of a switching valve V2 to V6. In the present case, the valves, V2, V3, V5, and V6 are connected such that the associated pressure sources P3, P4, P6, and P7 can selectively support the function of tilting or the function of lifting. The pressure source P5 can allow selectively allow the power to be assigned to the lifting function or to the steering function via the valve V4.

[0065] FIG. 7 shows a schematic representation of a valve 10 of the switching valve block.

[0066] The input 101 that is connected to the valve block input 11 or to the pressure source is fluidically connected to the output 102 or 103. A movable valve element is provided around the connection to one of the two outputs 102 and 103 that has two piston elements that are spaced apart from one another and that are connected to one another via the rod. These piston elements are sealingly arranged in a housing and have such a distance from one another that the input 101 arranged between the two outputs 102 and 103 is fluidically connected to only one of the two outputs 102 or 103 on a corresponding position of the valve element. To move the valve element, a control pressure can be introduced into the housing from above or from below so that the valve element moves in the desired direction. A spring 104 can here be provided for a preload. A switchover via a control valve can be provided for an opposite movement of the valve element, with said control valve selectively connecting the control lines 105, 106 to high pressure or to the low pressure side.

[0067] It is of particular advantage if the valve 10 does not have a position in which the input 101 is not connected to an output 102, 103 on a switchover of the fluid connection from one of the two outputs 102, 103 to the other output. It is thus prevented that pressure peaks arise that may occur on a brief closing of the input 101. Provision can be made on a change of the switching position of the valve 10 in the present case that a negative overlap arises, that is the input 101 is connected to both outputs 102, 103 for a brief movement and delivers pressurized fluid to both outputs 102, 103. This temporary state ensures that no blocking of the valve occurs due to a valve position change.

[0068] It is not necessarily the case here that pressurized fluid is delivered to both outputs 102, 103; the conveying amount could also be reduced/stopped during the switchover procedure so that no fluid is delivered.