EP2600012B1 - Hydrauliksystem - Google Patents

Description

The present invention relates to a hydraulic system with at least two main control valves and with a hydraulic pilot control system for controlling the main control valves.

If multi-circuit hydraulic systems are supplied with high pressure from a common hydraulic supply or if several hydraulic supplies supply a common consumer, this requires complex coordination of the main control valves with the output control of the pressure supply. For this reason, expensive electronic controls are usually used in the prior art. The object of the present invention is to provide a simpler and more reliable system.

This object is achieved by a hydraulic system according to claim 1 or claim 2.

A hydraulic system according to the upper handle of claims 1 and 2 is from CN 201513115 U known.

The hydraulic system according to the invention comprises at least two main control valves and a hydraulic pilot control system for controlling the main control systems. According to the invention, it is provided that the hydraulic pilot control system and / or the main control valves are constructed in such a way that the at least two main control valves open one after the other. According to the invention, the hydraulic or mechanical design of the hydraulic system can be used to open the main control valves in a certain sequence and thus to implement a cascade connection. In particular, the system can be constructed in such a way that the at least two main control valves open at different control pressures of a common control transmitter. This also makes it possible to implement a cascade connection in a hydraulically pilot-controlled multi-circuit system in which the main control valves open in a certain sequence. The main control valves can be used to control one or more consumers.

In a first variant, the cascade connection can be implemented using mechanically and / or hydraulically different main control valves.

In particular, the at least two main control valves can be equipped with springs of different spring force, so that the main control valves open at different control pressures due to the different spring force. For example, the spring of a first main control valve can open in a first control pressure range, while the spring of a second main control valve opens in a second control pressure range. Otherwise, the main control valves can be constructed identically.

Alternatively or additionally, the at least two main control valves can have different valve rods and / or valve housings, which lead to an opening of the at least two main control valves with different strokes. In this variant, the opening starts of the main control valves are mechanically defined differently on the valve rods or the valve housings. This can be done, for example, in the form of grooves or holes on the valve rods.

In this way, a cascade connection can be created using corresponding valve logic using valve hardware. The valves open at different strokes and thus at different control pressures.

Furthermore, it can be provided according to the invention that at least one of the main control valves is acted on by a counter pressure which counteracts the control pressure. In this way, the same effect can be achieved as with an increased spring strength, since the counter pressure is added to the spring pressure and must first be overcome by the control pressure in order to open the main control valve. In particular, the back pressure can be constant. A corresponding pressure source is advantageously provided for this.

Furthermore, the cascade connection can also be implemented by a corresponding configuration of the pilot control unit. This means that identical main control valves can also be used.

In particular, it can be provided that at least one of the main control valves is controlled via a pressure reducing valve, the output pressure of which is controlled via the control pressure for another main control valve. As a result, another control pressure for the one main control valve can be generated via the pressure reducing valve. In particular, the pressure reducing valve can have a pressure ratio unequal to 1 between the control pressure and the outlet pressure, so that the outlet pressure for controlling the one main control valve is in a fixed ratio to the control pressure for the other main control valve.

As an alternative or in addition, it can be provided that at least one of the main control valves is acted on by a pressure cut-off valve with a counter-control pressure which counteracts the control pressure. The pressure cut-off valve is advantageously acted upon by the control pressure, so that the counter-control pressure up to a cut-off pressure increases with the control pressure. This also enables the main control valve, which is acted upon by the counter-control pressure, to be opened later.

Of course, combinations of the possibilities described above are also conceivable. In particular, a first main control valve can be activated via a pressure reducing valve, while a second main control valve is acted upon by a counter-control pressure via a pressure cut-off valve.

Furthermore, the options described above can of course also be used with more than two main control valves.

In the variants described first, which work with mechanically and / or hydraulically different main control valves, correspondingly different spring strengths or correspondingly differently processed valve rods or valve housings can be used.

Furthermore, in a cascade connection via the pilot control unit, more than one pressure reducing valve or more than one pressure cut-off valve can be used, which then operate accordingly with different pressure ratios or with different cut-off pressures.

The hydraulic system according to the invention advantageously has a common control transmitter, via which the at least two main control valves can be actuated. In particular, this control transmitter can generate a control pressure for actuating the at least two main control valves. The design of the main control valves or the pilot control unit according to the invention then ensures different opening starts of the main control valves despite the common control transmitter.

In a first embodiment variant, the hydraulic system according to the invention also has a common high-pressure supply for supplying the at least one two main control valves with hydraulic pressure. The high-pressure supply advantageously includes a variable displacement pump, which is controlled depending on the needs of the connected consumer or consumers. The cascading of the opening starts according to the invention allows the use of such a pressure supply despite hydraulic pilot control.

According to the invention, the variable displacement pump is advantageously controlled via a load-sensing arrangement. In particular, the variable displacement pump is controlled in such a way that a certain pressure drop is maintained across all main control valves and, at the same time, a maximum pressure is not exceeded. Advantageously, a subsequent summation for controlling the load-sensing arrangement takes place.

In a second embodiment variant, the at least two main control valves can be supplied with hydraulic pressure via at least two separate high-pressure supplies, in particular via separate variable pumps.

The cascade control according to the invention ensures that at low required flow rates only one of the two main control valves opens and thus only one of the two hydraulic pumps is used to supply the consumer or consumers. If more power is required, the other main control valve also opens, so that the second hydraulic pump is also used for the supply.

Here, too, it can advantageously be provided that the variable displacement pumps are each controlled via a load-sensing arrangement.

Of course, the system according to the invention can also be used with more than two main control valves and / or more than two separate high-pressure supplies.

In a first variant of the hydraulic system according to the invention, the at least two main control valves control separate consumers.

For example, two hydraulic cylinders can be controlled via the two control valves. E.g. the two hydraulic cylinders can be used to successively extend or retract different elements, e.g. for telescoping telescopic drawers out or in.

As described above, one or more hydraulic pumps can be used to supply pressure.

In a second embodiment, the at least two main control valves control the same consumer. This is particularly advantageous if the maximum control amount required is not made available via a single main control valve.

As described above, the two main control valves are particularly advantageously supplied with hydraulic fluid via separate hydraulic pumps. Alternatively, however, the pressure supply can also take place here via only one hydraulic pump.

The present invention further includes a hydraulically powered implement having a hydraulic system as described above. In particular, it is a mobile work device. The present invention is particularly preferably used in construction, earthmoving and / or handling equipment. In particular, the present invention comprises a hydraulic excavator with a hydraulic system according to the invention.

In particular, the working device can comprise at least two separate hydraulic pumps for supplying consumers of the working device with hydraulic fluid, the at least two main control valves being supplied with hydraulic pressure separately from the at least two separate hydraulic pumps. The two main control valves advantageously supply the same consumer with hydraulic fluid.

The consumer who is supplied with hydraulic pressure by both main control valves can be a slewing gear, a running gear and / or a hydraulic cylinder, in particular for lifting and / or moving a boom or tool.

However, the two main control valves can also be used to supply two separate consumers with hydraulic fluid.

The at least two consumers can be, for example, a slewing gear, a running gear and / or hydraulic cylinders for lifting and / or moving a boom or tool.

Figur 1:

ein erstes Ausführungsbeispiel eines erfindungsgemäßen Hydrauliksystems mit Hauptsteuerventilen mit unterschiedlichen Federstärken,

Figur 2:

ein zweites Ausführungsbeispiel eines erfindungsgemäßen Hydrauliksystems mit Hauptsteuerventilen mit unterschiedlich gearbeiteten Ventilstangen,

Figur 3:

ein drittes Ausführungsbeispiel eines erfindungsgemäßen Hydrauliksystems mit einer über die Vorsteuereinheit realisierten Kaskadierung,

Figuren 4a bis 4d:

vier Ausführungsbeispiele für den Einsatz der erfindungsgemäßen Kaskadenschaltung mit einer oder mehreren Hydraulikpumpen und/oder einem oder mehreren Verbrauchern,

Figur 5:

ein Ausführungsbeispiele für den Einsatz der erfindungsgemäßen Kaskadenschaltung mit mehr als zwei Hauptsteuerventilen und/oder Pumpen.

The present invention is now illustrated in more detail by means of exemplary embodiments and drawings. Show:

Figure 1:

a first embodiment of a hydraulic system according to the invention with main control valves with different spring strengths,

Figure 2:

A second embodiment of a hydraulic system according to the invention with main control valves with differently worked valve rods,

Figure 3:

A third embodiment of a hydraulic system according to the invention with a cascading implemented via the pilot control unit,

Figures 4a to 4d:

four exemplary embodiments for the use of the cascade circuit according to the invention with one or more hydraulic pumps and / or one or more consumers,

Figure 5:

an exemplary embodiments for the use of the cascade circuit according to the invention with more than two main control valves and / or pumps.

The exemplary embodiments of the present invention relate to a hydraulic system with two main control valves, in particular as part of an LS multi-circuit system with downstream summation, which are operated hydraulically in a pilot-controlled manner. According to the invention, a cascade connection is provided, by means of which the hydraulic control slides used as main control valves are opened in a certain sequence.

The system is controlled via a common pilot transmitter 2, in particular a control handle, via which a desired control pressure for pilot control is generated. The pilot control transmitter can be, for example, a joystick. The pilot control transmitter 1 can be controlled via a pilot control pressure source 15, as shown, for example, in Figure 3 is shown, are subjected to a constant pilot pressure and reduces this to the desired control pressure. The constant pilot pressure can be 35 bar, for example.

Thanks to its mechanical or hydraulic construction, the hydraulic system according to the invention now allows the opening times to be cascaded despite this common control. On the one hand, the cascade connection can be implemented via different valve springs of the main control valves or via different slide opening starts of the main control valves. A hydraulic cascade pilot control unit can also be provided, so that the cascade connection takes place via the pilot control. These three alternatives should now be used again in the Figures 1 to 3 Exemplary embodiments shown are explained in more detail.

In Figure 1 Two main control valves 2 and 3 are shown, which are each acted upon at their control pressure connections 4 and 5 by the same control pressure of the pilot control transmitter 1. According to the valve springs 6 and 7 of the two main spools 2 and 3 are selected so that, for. B. the spring of the slide 2 in a first pressure range and the spring of the slide 3 in a second pressure range. For example, the spring 6 of the slide 2 can be selected so that it responds in a pressure range between 0 and 20 bar, while the spring 7 of the slide 3 responds from 20 to 35 bar. Different opening starts are achieved through the different valve springs.

Alternatively or additionally, one of the slides (in Fig. 1 the slide 3) a pressure source or corresponding circuit 9 can be provided, which this with a back pressure. In this way, the same effect is achieved as by the mechanical strengthening of the spring strength of the slide 3. In this case, the valve 3 is acted upon by a counter-control pressure from the circuit 9 via the counter-control pressure connection 8, the counter-pressure advantageously being constant.

As a result, the same spring strength can be used as for the slide 2, which is now amplified via the pressure source 9, since the counter pressure is added to the spring pressure. For example, the spring strength for the valve 3 can also be between 0 and 20 bar and be increased by 10 bar from the pressure source 9.

At the in Figure 2 shown variant, the opening starts of the main slide 2 'and 3', on the other hand, are mechanically defined differently on the valve rods 10 and 11. Depending on the manufacturer of the basic slide, this can take the form of grooves or holes. As a result, a cascade connection can be created using the slide hardware without corresponding circuit logic.

As in Figure 2 shown, both pistons 10 and 11 thus have the same stroke 12, but the piston of the main control valve 2 'opens after a short distance, while the piston of the main control valve 3' only opens by the stroke 13 later. In the exemplary embodiment, this is achieved in that the groove 14 on the valve rod 11 of the main control valve 3 'is shorter than the groove 14' on the valve rod 10 of the main control valve 2 ', and thus the pressure supply P with the one leading to the consumer only with a larger stroke Opening A or A 'connects.

In this exemplary embodiment, the valve springs 6 'and 7' can also be designed identically, so that the different opening starts occur solely through the mechanical configuration of the valve rods. Alternatively, this could also be done by a different mechanical configuration of the valve housing. At the in Figure 3 shown variant, however, the cascade connection is implemented via a corresponding configuration of the pilot valve unit. In particular, the main control slide 2 'and 3' can be used unchanged. Here are in Figure 3 again two different variants combined, which can also be used individually.

On the one hand, a pressure reducing valve 16 can be provided which is acted upon by the constant pilot pressure from the pilot pressure source 15. The pressure reducing valve 16 is acted upon by the control pressure 17 of the pilot control transmitter 1 and has a specific pressure ratio x, so that x times the control pressure 17 is present at the pressure outlet 18 of the pressure reducing valve 16. The first main control valve 2 'is acted upon by the actual control pressure 17, the second main control valve 3' by the changed control pressure 18 of the pressure reducing valve. The piston control 5 of the main control valve 3 'thus acts x times the control pressure specified by the control transmitter, while the piston control 4 of the main control valve 2' is affected by the simple control pressure specified on the control transmitter 1.

As an alternative or in addition, a pressure cut-off valve 19 can be provided which is acted upon by the control pressure from the pilot pressure transmitter 1 and has a defined cut-off pressure. A counter pressure is exerted on the piston 4 of the main control valve 2 'via the pressure from the pressure cut-off valve 19. As long as the control pressure is below the cut-off pressure of the cut-off valve 19, the same pressure acts on both sides a and b of the main control valve 2 ', so that it remains in the neutral position. If the control pressure specified on the control transmitter 1 now rises above the cut-off pressure set in the pressure cut-off valve 19, the pressure on the piston 4 only increases on the a-side, while on the b-side the pressure set in the cut-off valve 19 remains, so that the piston 4 now also deflected over the pressure difference between a and b. As in Figure 3 shown, both variants can also be combined, so that one valve is acted on by the pressure cut-off valve with back pressure, while the other valve is actuated by the pressure reducing valve.

It would also be conceivable to use several pressure reducing valves with different pressure ratios and / or several pressure cut-off valves with different cut-off pressures in the case of several valves.

Furthermore, the pressure for both main control valves could also be achieved only with two main control valves, in each case via pressure reducing valves with different pressure ratios, or via pressure cut-off valves with different cut-off pressures.

In Figures 4a to 4d Four exemplary embodiments for the use of the cascade circuit according to the invention with one or more hydraulic pumps and / or one or more consumers are shown.

In Fig. 4a the two main control valves 2 and 3 are completely connected in parallel. They are supplied by a common hydraulic pump 30 and control the same consumer 40.

In Fig. 4b the two main control valves 2 and 3 are only connected in parallel with regard to the pump side. They are therefore supplied by a common hydraulic pump 30, but control separate consumers 41 and 42.

In Fig. 4c the two main control valves 2 and 3 are connected in parallel only with regard to the consumer side. They are therefore supplied by two separate hydraulic pumps 31 and 32, but control the same consumer 40.

In Fig. 4d the two main control valves 2 and 3 are connected in parallel neither with regard to the consumer side nor with regard to the pump side. you will be therefore supplied by two separate hydraulic pumps 31 and 32 and control separate consumers 41 and 42.

In Fig. 5 An exemplary embodiment is shown in which more than two main control valves 50 to 53 are supplied separately from hydraulic pumps 31 to 34 on the pump side, but control the same consumer 40.

The hydraulic system is advantageously designed such that the more than two main control valves 50 to 53 open or close in a defined sequence.

The present invention makes it possible, in particular in the case of a high-pressure supply to a multi-circuit system, to operate the main control valves hydraulically in a pilot-controlled manner by means of a load-sensing control with a subsequent summation, and yet to achieve a cascade connection.

Hydraulic systems according to the invention can be used in particular in the case of mobile work machines, such as, for example, a hydraulic excavator.

Claims (13)

1. A hydraulic system with at least two main control valves (2, 3; 2', 3'; 2", 3") and with a hydraulic pilot control system for actuating the main control valves (2, 3; 2', 3'; 2", 3"), wherein the hydraulic pilot control system and/or the main control valves (2, 3; 2', 3'; 2", 3") are constructed such that the at least two main control valves (2, 3; 2', 3'; 2", 3") open one after the other,
   characterized in
   that the hydraulic pilot control system is hydraulically connected with all main control valves (2, 3; 2', 3'; 2", 3") via a common pilot control line branching towards the main control valves (2, 3; 2', 3'; 2", 3").
2. A hydraulic system with at least two main control valves (2, 3; 2', 3'; 2", 3") and with a hydraulic pilot control system for actuating the main control valves (2, 3; 2', 3'; 2", 3"), wherein the hydraulic pilot control system and/or the main control valves (2, 3; 2', 3'; 2", 3") are constructed such that the at least two main control valves (2, 3; 2', 3'; 2", 3") open one after the other, characterized in that at least one of the main control valves (2, 3; 2', 3'; 2", 3") is actuated via a pressure reducing valve (16) whose outlet pressure (18) is actuated via the control pressure (17) of another main control valve (2, 3; 2', 3'; 2", 3"), wherein the pressure reducing valve (16) advantageously includes a pressure ratio (x) between control pressure (17) and outlet pressure (18) unequal to 1, and/or characterized in that via a pressure shut-off valve (19) at least one of the main control valves (2, 3; 2', 3'; 2", 3") is charged with a counter control pressure which counteracts the control pressure (17) and rises with the control pressure (17) up to a shut-off pressure.
3. The hydraulic system according to claim 1 or 2, wherein the at least two main control valves (2, 3; 2', 3'; 2", 3") include springs (6, 7) with a different spring force, which lead to an opening of the at least two main control valves (2, 3; 2', 3'; 2", 3") at different control pressures (17).
4. The hydraulic system according to any of the preceding claims, wherein the at least two main control valves (2, 3; 2', 3'; 2", 3") include different valve rods (10, 11) and/or valve housings, which lead to an opening of the at least two main control valves (2, 3; 2', 3'; 2", 3") at different strokes.
5. The hydraulic system according to any of the preceding claims, wherein at least one of the main control valves (2, 3; 2', 3'; 2", 3") is charged with a counterpressure which counteracts the control pressure (17), wherein the counterpressure advantageously is constant.
6. The hydraulic system according to any of the preceding claims, wherein the at least two main control valves (2, 3; 2', 3'; 2", 3") can be actuated via a common control transmitter (1), wherein the control transmitter (1) advantageously generates a pilot pressure for actuating the at least two main control valves (2, 3; 2', 3'; 2", 3").
7. The hydraulic system according to any of the preceding claims, wherein the at least two main control valves (2, 3; 2', 3'; 2", 3") are supplied with hydraulic pressure via a common high-pressure supply, in particular via a common variable displacement pump (30, 31, 32, 33), wherein the variable displacement pump (30, 31, 32, 33) advantageously is actuated via a load sensing arrangement, wherein furthermore advantageously a downstream summation is effected.
8. The hydraulic system according to any of claims 1 to 6, wherein the at least two main control valves (2, 3; 2', 3'; 2", 3") are supplied with hydraulic pressure via at least two separate high-pressure sources, in particular via separate variable displacement pumps (30, 31, 32, 33), wherein the variable displacement pumps (30, 31, 32, 33) advantageously each are actuated via a load sensing arrangement.
9. The hydraulic system according to any of the preceding claims, wherein the at least two main control valves (2, 3; 2', 3'; 2", 3") actuate different loads (40, 41).
10. The hydraulic system according to any of claims 1 to 8, wherein the at least two main control valves (2, 3; 2', 3'; 2", 3") actuate the same load (40, 41).
11. A hydraulically driven implement with a hydraulic system according to any of the claims 1 to 10, in particular a mobile implement, in particular a construction, earth-moving and/or material-handling machine, in particular a hydraulic excavator.
12. The hydraulically driven implement according to claim 11, comprising at least two separate hydraulic pumps for supplying loads (40, 41) of the implement with hydraulic fluid, wherein the at least two main control valves (2, 3; 2', 3'; 2", 3") are separately supplied with hydraulic pressure by the at least two separate hydraulic pumps and advantageously supply the same load (40, 41) with hydraulic fluid.
13. The hydraulically driven implement according to claim 12, wherein the load (40, 41) which is charged with hydraulic pressure by the two main control valves (2, 3; 2', 3'; 2", 3") is a slewing gear, a traveling gear and/or a hydraulic cylinder for lifting and/or moving a boom or tool.

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