DE102010040754A1 - Hydraulic drive arrangement - Google Patents

Abstract

A hydraulic drive arrangement is proposed with at least one linear drive for carrying out work movements in a work machine, the linear drive being connected to a hydraulic circuit (1) for supplying pressure medium. According to the invention, a closed hydraulic circuit (1) with at least one controllable pump (2) is assigned to the linear drive.

Description

The present invention relates to a hydraulic drive assembly according to the closer defined in the preamble of claim 1. Art.

It is known from vehicle technology that hydraulic systems are used in working machines, such as, for example, in wheeled excavators or the like, in order, for example, to drive traction drives, hydraulic part-turn drives and also hydraulic linear drives, such as working arm drives. The required pressure medium is provided by hydraulic pumps. In hydraulic circuits for linear drives to perform working movements only working hydraulic circuits are used in working machines. This means that the pressure fluid flows from a reservoir to the pump and then passed to the consumer or to the linear drive. Subsequently, the pressure medium is returned to the reservoir.

For example, from the document DE 699 20 452 T2 Such a mobile working machine is known, which has an open hydraulic circuit. The hydraulic circuit includes a lift cylinder disposed in a lift of the work machine adapted to handle a load. Furthermore, the circuit comprises an accumulator for recovering or returning decreasing load energy.

In the known hydraulic drive arrangements with an open hydraulic circuit for supplying pressure medium to the linear drive for carrying out the movements, for example, of a working arm of a working machine, a plurality of linear drives are usually driven by means of a common pump. This has the disadvantage that the pressure provided by the pump is determined by the linear drive, which requires the highest pressure in order to deliver the requested mechanical force. The other linear actuators, even if they require a lower pressure, nevertheless supplied with a volume flow from the higher pressure level. The total delivery rate or the total volume flow of the pump is thus generated at the higher pressure level, which requires only one of the cylinders. As a result, the efficiency is reduced disadvantageously.

The present invention is based on the object to propose a hydraulic drive arrangement of the type described above, in which the overall efficiency is increased.

This object is achieved by the features of claim 1, wherein further advantageous embodiments of the dependent claims and the drawings.

Accordingly, a hydraulic drive arrangement with at least one linear drive for carrying out working movements in a work machine, such as a wheeled excavator, a backhoe loader, a wheel loader, a telehandler, a forklift or the like is proposed, wherein the linear drive is connected to the pressure medium supply or oil supply to a hydraulic circuit , According to the invention, a closed hydraulic circuit with at least one separately controllable pump or the like is assigned to each linear drive.

By using a separate pump for each linear drive, there is the advantage that the power losses occurring in the known hydraulic drive assemblies are avoided and the overall efficiency is increased because each pump promotes exactly the pressure medium required for the linear actuator pressure on each required level. Furthermore, by the use of the closed hydraulic circuit all otherwise required directional valves or the like control elements can be omitted. The throttle losses on the otherwise required directional valves thus eliminated, so that the efficiency is further improved. In addition, there is an advantage of the regenerative capacity of services in the mechanical drive of the pump when z. B. reverses the power flow in the closed hydraulic circuit. This can occur, for example, when operating arms on the work machine by lowering the load. As a result, the use of closed circuits in the work machine can significantly increase the usefulness of the hybrid components. For example, the recovered power can be passed into an energy store and is then available, for example for a drive at any point of the machine again.

In order to minimize the feed amount in a closed hydraulic circuit, may be provided in an advantageous embodiment of the invention that each designed as a linear actuator cylinder is designed so that the respective volume flows for carrying out a working movement in the two associated with the pump sub-strands of the hydraulic circuit almost identical are. This is to ensure that the same amount of oil is passed from and to the linear consumer or to the working cylinder in a closed circuit.

According to one embodiment of the invention, this can be achieved in that the resulting active surfaces and thus the displaced or supplied pressure medium volume on both sides of the piston or in the piston rod side pressure chamber and in the bottom-side pressure chamber of each working cylinder are about the same size. This can be done by appropriate design adaptation of the piston rod side pressure chamber to the bottom pressure chamber or vice versa.

In the context of a further possible embodiment, the flow equalization between the two sub-strands in the closed hydraulic circuit by the use of at least one compensating cylinder or the like, which is hydraulically connected to the working cylinder, wherein the compensating cylinder mechanically so with the working cylinder or with the element to be actuated is arranged that the movement of the compensating cylinder relative to its piston by the mechanical coupling with the working cylinder ensures a volume flow, which ensures a balance between the displaced and the supplied pressure medium volume. If several cylinders are provided, each cylinder can be assigned a balancing cylinder. For cylinder pairs, as z. B. are used in excavators for the movement of the main arm, preferably only one compensating cylinder can be selected for both master cylinder.

A next variant embodiment of the invention can realize the volume flow compensation between the partial strands in the closed hydraulic circuit in that, when using a plurality of working cylinders, at least one reaction cylinder operating in the opposite direction to the other working cylinders, in the manner of an antagonist, as used in the human musculature, is used. The mechanical translation and the selected piston surfaces are adjusted so that in the sum always the same pressure fluid volume are moved in the circulation.

Preferably, the proposed hydraulic drive arrangement can be used in hydraulic excavators but also in other work machines and vehicles.

Hereinafter, the present invention with reference to the drawings, which represent three possible embodiments, explained in more detail. Show it:

1 a schematic view of a first possible embodiment of a hydraulic drive assembly for a linear drive of a working machine;

1A a side view of the drive assembly according to 1 ;

2 a schematic view of a second possible embodiment of the hydraulic drive assembly; and

3 a schematic view of a third possible embodiment of the hydraulic drive assembly.

In the figures are partially greatly simplified various possible embodiments of a hydraulic drive assembly with at least one linear drive in the form of a hydraulic cylinder for carrying out working movements z. B. a working arm of a working machine. In the embodiments shown, a closed hydraulic circuit according to the invention for pressure medium supply 1 with a separately controllable pump 2 assigned to each linear drive.

When the as a working cylinder 3 trained linear actuators is provided that every working cylinder 3 is designed such that the respective volume flows for carrying out a working movement in the two partial strands T1 and T2 of the hydraulic circuit assigned to the pump 1 as identical as possible. In this way, in addition to the effect optimization by the separate control and the feed amount in the closed hydraulic circuit 1 reduced to a minimum.

The inventive compensation of the volume flows in the sub-strands T1 and T2 is at the in 1 and 1A represented realized by the fact that the size of the resulting active surfaces of the piston 4 of the working cylinder 3 in the two sides of the piston 4 associated pressure chambers 5 and 6 is approximately identical, each with an associated sub-string T1, T2 of the closed hydraulic circuit 1 are connected.

In terms of design, this is achieved by using a piston rod 7 with an in 1 not shown working arm 19 connected pistons 4 of the working cylinder 3 also at the bottom pressure chamber 6 associated side of the piston 4 a second piston rod 8th having. The second piston rod 8th is identical in terms of dimensions with the piston rod 7 executed, wherein the second piston rod 8th no force transfers, but only from the housing of the working cylinder 3 protrudes and sealed against the housing. Using the second identically designed piston rod 8th is thus the displaced or supplied pressure fluid volume on both sides of the piston 4 identical.

In 2 a second embodiment is shown, in which in addition to the working cylinder connected to the operating arm to be actuated 3 a balancing cylinder 9 is provided, the hydraulically and mechanically with the working cylinder 3 connected or coupled. For mechanical coupling is the compensation cylinder 9 with the working cylinder 3 on the element to be actuated or on the working arm 19 attached. As a result, the working cylinder 3 and the balance cylinder 9 simultaneous movements off when the working arm 19 should be pressed.

The one with the sub-string T1 of the closed hydraulic circuit 1 connected rod side pressure chamber 5 of the working cylinder 3 is with the piston rod side pressure chamber 10 the compensating cylinder 9 hydraulically connected, wherein the bottom pressure chamber 11 the compensating cylinder 9 with the air side of a hydraulic tank 12 is connected and wherein the bottom pressure chamber 6 of the working cylinder 3 with the sub-string T2 of the closed hydraulic circuit 1 connected is. As a result, a corrosion protection is guaranteed and flow losses of a pressure medium filling are thus avoided. Optionally, the bottom pressure chamber 11 be exposed to air or oil at atmospheric pressure.

Furthermore, it is also possible in the context of a variant not shown that the with the sub-string T1 of the closed hydraulic circuit 1 connected rod side pressure chamber 5 of the working cylinder 3 with the bottom pressure chamber 11 the compensating cylinder 9 is connected, wherein the piston rod-side pressure chamber 10 the compensating cylinder 9 with the air side of the hydraulic tank 12 and the bottom pressure chamber 6 of the working cylinder 3 again with the sub-string T2 of the closed hydraulic circuit 1 connected is. In addition to the corrosion protection and the avoidance of flow losses could be reduced to the advantageously the dimensions of the compensating cylinder.

By the above-described mechanical and hydraulic coupling between the working cylinder 3 and the associated balancing cylinder 9 is a compensation of the flow rates in the pump 2 associated sub-strands T1 and T2 ensured as a balance between on the one hand, the flow rate of the sub-string T1, comprising the pressure fluid volume of the piston rod-side pressure chamber 5 of the working cylinder 3 and the piston rod side pressure chamber 10 the compensating cylinder 9 , and on the other hand, the volume flow of the partial strand T2, comprising the pressure medium volume of the bottom pressure chamber 6 of the working cylinder 3 , consists.

A third embodiment is in 3 shown in the case of a working arm to be actuated 19 a first as an action cylinder 13 trained hydraulic cylinder and a second as a reaction cylinder 14 are assigned trained hydraulic cylinder. Here is the mechanical linkage of the action cylinder 13 and the reaction cylinder 14 chosen so that no simultaneous but an opposite movement is achieved. The mechanical translation and the dimensions of the pressure chambers or the active surfaces of the associated pistons are adjusted so that the sum of the same quantities of pressure medium in the partial strands T1 and T2 of the closed hydraulic circuit 1 to be moved.

This is the piston rod side pressure chamber 15 of the action cylinder 13 with the bottom pressure chamber 16 of the reaction cylinder 14 connected, wherein the bottom pressure chamber 17 of the action cylinder 13 with the piston rod side pressure chamber 18 of the reaction cylinder 14 connected is.

LIST OF REFERENCE NUMBERS

1

closed hydraulic circuit

2

pump

3

working cylinder

4

piston

5

piston-side pressure chamber

6

bottom pressure chamber

7

piston rod

8th

additional piston rod

9

compensating cylinder

10

piston-side pressure chamber of the compensating cylinder

11

bottom-side pressure chamber of the compensating cylinder

12

hydraulic tank

13

action cylinder

14

reaction cylinder

15

piston rod side pressure chamber of the action cylinder

16

bottom-side pressure chamber of the reaction cylinder

17

bottom-side pressure chamber of the action cylinder

18

piston rod side pressure chamber of the reaction cylinder

19

Working arm of the working machine

T1

first sub-string between pump and cylinder

T2

second sub-string between cylinder and pump

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 patent literature

• DE 69920452 T2 [0003]

Claims (11)

Hydraulic drive arrangement with at least one linear drive for carrying out working movements in a work machine, wherein the linear drive for supplying pressure medium with a hydraulic circuit ( 1 ), characterized in that the linear drive a closed hydraulic circuit ( 1 ) with at least one controllable pump ( 2 ) assigned. Hydraulic drive arrangement according to claim 1, characterized in that as a linear drive at least one connected to an actuatable element of the working machine working cylinder ( 3 ) is provided, which is designed such that the respective volume flows for carrying out a working movement in the two of the pump ( 2 ) associated partial strands (T1, T2) of the closed hydraulic circuit ( 1 ) are almost identical. Hydraulic drive arrangement according to claim 2, characterized in that the size of the resulting active surfaces of the piston ( 4 ) of the working cylinder ( 3 ) in the two sides of the piston ( 4 ) associated pressure chambers ( 5 . 6 ) is almost identical. Hydraulic drive arrangement according to claim 2 or 3, characterized in that the piston ( 4 ) of the working cylinder ( 3 ) via a piston rod ( 7 ) is connected to the element to be actuated, wherein the piston ( 4 ) in addition to the bottom pressure chamber ( 6 ) side facing a roughly identical to the piston rod ( 7 ) executed second piston rod ( 8th ), so that about the one hand, supplied pressure medium volume in the pressure chamber ( 5 ) on the other hand discharged pressure medium volume from the other pressure chamber ( 6 ) corresponds. Hydraulic drive arrangement according to one of the preceding claims, characterized in that in addition to the working cylinder designed as a linear drive ( 3 ) at least one with the working cylinder ( 3 ) hydraulically connected compensating cylinder ( 9 ) to equalize the flow rates in the pump ( 2 ) associated partial strands (T1, T2) is provided, wherein the working cylinder ( 3 ) and the compensating cylinder ( 9 ) are mechanically coupled together. Hydraulic drive arrangement according to claim 5, characterized in that with the first sub-string (T1) of the closed hydraulic circuit ( 1 ) connected piston rod side pressure chamber ( 5 ) of the working cylinder ( 3 ) with one of the pressure chambers ( 10 . 11 ) of the compensating cylinder ( 9 ) and that the bottom pressure chamber ( 6 ) of the working cylinder ( 3 ) with the second sub-string (T2) of the closed hydraulic circuit ( 1 ), the other pressure space ( 10 . 11 ) of the compensating cylinder ( 9 ) is subjected to ambient pressure. Hydraulic drive arrangement according to claim 6, characterized in that the bottom-side pressure chamber ( 11 ) of the compensating cylinder ( 9 ) with the piston-side pressure chamber ( 5 ) of the working cylinder ( 3 ), and that the rod-side pressure chamber ( 10 ) of the compensating cylinder ( 9 ) with the air side of a hydraulic tank ( 12 ) connected is. Hydraulic drive arrangement according to one of the preceding claims, characterized in that at least one action cylinder designed as a working cylinder ( 13 ) for carrying out a working movement at least one reaction cylinder ( 14 ) for performing an opposite movement is assigned such that the respective volume flows in the action cylinder ( 13 ) and the reaction cylinder ( 14 ) in the two of the pump ( 2 ) associated partial strands (T1, T2) of the closed hydraulic circuit ( 1 ) are almost identical. Hydraulic drive arrangement according to claim 8, characterized in that the action cylinder ( 13 ) and the reaction cylinder ( 14 ) are assigned to the same element to be actuated of the working machine, wherein by the respective articulation of action cylinder ( 13 ) and reaction cylinder ( 14 ) the volume flow compensation in the closed hydraulic circuit ( 1 ) is feasible. Hydraulic drive arrangement according to claim 8 or 9, characterized in that the piston rod-side pressure chamber ( 15 ) of the action cylinder ( 13 ) with the bottom-side pressure chamber ( 16 ) of the reaction cylinder ( 14 ) and that the bottom pressure chamber ( 17 ) of the action cylinder ( 13 ) with the piston-side pressure chamber ( 18 ) of the reaction cylinder ( 14 ), wherein the active surfaces of the pistons of action cylinder ( 13 ) and reaction cylinder ( 14 ) are selected so that during each working movement in both partial strands (T1, T2) of the closed hydraulic circuit ( 1 ) the same amount of pressure medium is movable. Hydraulic drive arrangement according to one of claims 8 to 10, characterized in that for carrying out working movements in different elements of the working machine each element as a working cylinder executed action cylinder ( 13 ), wherein at least one of these working cylinders as a reaction cylinder ( 14 ) and the remaining as action cylinders ( 13 ) are executed.

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