DE102009052077A1 - Hydraulic control arrangement with variable via a LS-valve control pressure drop - Google Patents

Abstract

Disclosed is a hydraulic control arrangement with an inlet pressure balance consisting of a proportional directional control valve, one control side of which is subjected to a throttled consumer load pressure and a biasing spring and the other control side of which is throttled pump pressure, and a hydraulically controlled switching valve for selectively throttled connection of the two control sides of the proportional directional control valve. Furthermore, an additional, preferably electromagnetically actuated switching valve is provided, which optionally opens a bypass line to the hydraulically actuated switching valve in order to positively switch a throttled bypass connection between the two control sides of the proportional directional control valve.

Description

The present invention relates to a hydraulic control arrangement with variable control pressure gradient according to the preamble of patent claim 1.

In a hydraulic control arrangement of this type, a control or valve block of a constant or controllable pump is connected downstream, which includes a pressure compensator and a preferably adjustable pressure relief valve. An example of such a control block of a known control arrangement is in the appended 2 shown.

Accordingly, the control block of a generic control arrangement has a 2/2-way proportional valve whose input port is connected to the pump and whose output port is connected to a hydraulic tank. One control side of the proportional directional valve is acted upon by the pump pressure and the other control side is acted upon by two series-connected throttles with the load pressure of a consumer and a biasing spring. This structure forms a pressure compensator whose biasing spring determines a pressure gradient or pressure difference between the pump pressure and the load pressure, which is kept constant by the pressure compensator. In other words, if, for example, the control line is in the unloaded state (load pressure = 0), the pump pressure acting on the opposite control side causes the proportional valve to open, which consequently relaxes the pump pressure to the set pressure differential value. This condition is also called neutral circulation.

If the load pressure at the load increases, the pressure in the control line also increases, whereby the proportional valve for pressure build-up in the pump line is closed until the set differential pressure value is reached.

It is obvious that in such a control arrangement, depending on the level of the preset pressure gradient in the case of a neutral circulation, the energy loss is unacceptably high. For this reason, a control arrangement has been proposed in the prior art, which provides a pressure drop switching from a high value in the case of a consumer operation to a low value in the case of a neutral circulation. Such a control arrangement is exemplary in the 3 shown.

Accordingly, the biasing spring opposite control side of the pressure compensator is connected via a throttle to the pump pressure line, in parallel with a built-in pressure compensator 2/2 switching valve is arranged, which can connect the pump pressure line to the control line. In the case of a neutral circulation with a relieved control line, the 2/2-way valve blocks the connection line between the pump line and the control line, so that the pump spring pressure is applied to the control side of the pressure compensator opposite the pretension spring. As a result, a neutral circulation pressure corresponding to the control force of the biasing spring is established.

If the consumer is activated, the control pressure in the control line increases, whereby the 2/2-way valve opens and a corresponding control pressure acts in addition to the biasing spring on the pressure compensator. As a result, the pump pressure rises to a correspondingly higher pressure value, which is held by the pressure compensator.

Although in the control arrangement described last according to the 3 the loss energy in the neutral circulation relative to the control arrangement according to the 2 can be reduced, it still results in the pump pressure in the case of a consumer operation of the required for this control pressure differential. This means that when several consumers are to be operated with multiple control blocks, the control arrangement must always regulate to the highest required control pressure drop of all consumers. If, for example, only one of the several consumers is actuated in such a case and this is only a consumption with a low pressure drop requirement, the energy loss is limited to the max. Pressure gradient adjusted control arrangement in consumption mode enormously high.

In view of this problem, it is an object of the present invention to provide a control arrangement which can set different pressure gradients for several different consumers.

This object is achieved by a control arrangement having the features of patent claim 1. Further advantageous embodiments of the invention are the subject of the dependent claims.

The essence of the invention is therefore to equip the hydraulic control assembly with an inlet pressure compensator consisting of a proportional directional control valve whose one control side is acted upon by a throttled load load and a biasing spring and the other control side with a throttled pump pressure, wherein a hydraulically controlled switching valve is provided to the selected throttled connection of the two control sides of the proportional directional control valve. In that regard, this basic structure corresponds to that in the 3 shown known control arrangement. According to the invention is now however, another preferred electromagnetic switching valve selectively opens a bypass line to the hydraulically-operated switching valve to force-connect a throttled by-pass connection between the two control sides of the proportional directional control valve. This further switching valve is selectively actuated in order to start the preselected in neutral circulation low pressure gradient (only dependent on the biasing spring) to a predeterminable value (corresponding to the throttle setting in the bypass line), which allows a start of a further consumption via the (external) control block. This has the advantage that, when the further consumer is not activated, the neutral circulation pressure gradient can be kept low and can be increased as needed with further consumers to be activated. Thus, the loss energy can be kept at a low level.

According to a preferred embodiment of the invention, a preferably adjustable throttle in the bypass line is connected directly upstream of the electromagnetic switching valve. This throttle may thus have a different setting than the hydraulically actuated switching valve immediately upstream throttle, so that upon activation of the electromagnetic switching valve, a neutral circulation pressure differential is different from the pressure drop in the consumer operation with non-activated electromagnetic switching valve.

It is also advantageous if, according to a number of external control blocks, a number of hydraulically operated 2-position / 3-way switching valves are serially interposed in a connecting line between the electromagnetic switching valve and the pressure balance, whose output terminal in each case with the one input terminal of each connected downstream of the switching valve whose other input terminal is connected via a respective branch line to the pump-pressure-loaded control side of the pressure compensator and whose one control side is connected to the consumer pressure line of the respective associated control block. In this case, it is preferably provided to connect a further preferably adjustable throttle in each branch line to the respective hydraulically actuated switching valve. In this way, depending on the operation of one of the external consumers, the associated hydraulically actuated switching valve is activated, resulting in a different according to the setting of the respective upstream throttle differential pressure gradient in consumer operation.

This means that not only the neutral circulation pressure drop can be adjusted as needed, but also the pressure drop in consumer operation via the correspondingly arranged hydraulic switching valves is always set to the consumer with the highest pressure drop requirement currently. This also contributes to a significant reduction in energy loss.

The invention will be explained below with reference to a preferred embodiment with reference to the accompanying drawings.

1 shows a circuit diagram of a hydraulic control arrangement, in particular with an inlet pressure compensator with adjustable control pressure drop for multiple consumers according to a preferred embodiment of the invention,

2 shows a circuit diagram of a hydraulic control arrangement with a fixed pressure gradient according to a prior art and

3 shows a circuit diagram of a hydraulic control with switchable pressure gradient according to a prior art.

According to the 1 the control arrangement is integrated according to a preferred embodiment of the invention in an internal control block and has a pressure compensator forming 2-way / 2-position proportional directional control valve 1 , at whose input connection a pump 2 is connected and its output port to a pressure tank 4 leads. The one control side x of the proportional directional control valve 1 is via a second throttle D2 with the pump 2 connected. The other control side y of the proportional directional control valve 1 is spring loaded and via a first throttle D1 with a consumer pressure main 6 connected. From this consumer pressure main 6 goes a pressure relief line 8th in the tank 4 in which a preferably adjustable pressure relief valve 10 is interposed.

Furthermore, in the internal control block are a number of manually operated switching valves 12 integrated to activate each of a hydraulic consumer not shown further. Each of the manually operated switching valves 12 has a consumer pressure port, which has an internal consumer pressure branch line 14 with the consumer pressure main 6 connected upstream to the throttle D1, and a consumer pressure expansion port connected to the pressure tank 4 connected is.

The two control sides x, y of the pressure compensator forming proportional directional control valve 1 are via a short circuit line 16 hydraulically connectable to each other, in which a hydraulically controlled switching valve ZV1, in the present case a 2/2-way switching valve is interposed, whose one control side is spring-biased and whose other control side of Pressure on the spring-biased control side of the proportional directional control valve 1 is charged. This hydraulically controlled switching valve ZV1 is a preferably adjustable throttle / aperture D3 immediately upstream.

The hitherto described hydraulic structure of the preferred control arrangement of the invention substantially corresponds to the circuit construction of the control arrangement of 1 , Consequently, the functionality is identical, so at this point to the for 1 already explained technical explanations can be referenced.

Like from the 1 can still be found, the component combination consisting of the hydraulically controlled switching valve ZV1 and the immediately upstream throttle D3 with a bypass line bypassing this 18 provided upstream of the throttle D3 from the short-circuit line 16 branches off and downstream of the hydraulically controlled switching valve ZV1 back into the short-circuit line 16 empties. In the bypass line 18 is a electromagnetic 3-way / 2-position switching valve ZVA interposed, which is a directly adjustable throttle / diaphragm DA immediately upstream. This throttle DA is / can be set differently to the throttle D3. The electromagnetic switching valve ZVA connects in a first switching position (preferably not activated) the hydraulically controlled switching valve ZV1 with the spring-biased control side of the pressure compensator 1 , In a second switching position (preferably activated), the electromagnetic switching valve ZVA blocks the hydraulically controlled switching valve ZV1 and instead connects the short-circuit line 16 via the throttle DA with the spring-loaded control side of the pressure compensator 1 ,

Finally, in the 1 a number, in this case two, external control blocks 20 . 22 shown, which are arranged to control external (not shown) consumers. Every external control block 20 . 22 is via a pumping line 24 directly with the pump 2 connected and further has an external consumer pressure branch line 26 . 28 that has an external shuttle valve 30 into the consumer pressure main 6 opens. Every external control block 20 . 22 is an external hydraulically controlled 3-way / 2-position switching valve ZV2, ZV3 assigned and serial in the short-circuit line 16 downstream of the electromagnetic switching valve ZVA.

In the present embodiment, this is the first external control block 20 assigned hydraulically actuated switching valve ZV2 in the short-circuit line 16 the electromagnetic switching valve ZVA immediately downstream, wherein the one input terminal to the output terminal of the electromagnetic switching valve ZVA is connected and the second input terminal via an immediately upstream, preferably adjustable throttle D4 with the short-circuit line 16 connected upstream of the throttle D3 (ie directly with the pump pressure-loaded control side of the pressure compensator 1 ). Furthermore, this is the second external control block 22 assigned external hydraulically actuated switching valve ZV3 in the short-circuit line 16 the external hydraulically actuated switching valve ZV2 of the first external control block 20 immediately downstream, wherein the one input terminal to the output terminal of the external hydraulically actuated switching valve ZV2 of the first external control block 20 is connected and the second input terminal via an immediately upstream, preferably adjustable throttle D5 with the short-circuit line 16 connected upstream of the throttle D3 (ie directly with the pump pressure-loaded control side of the pressure compensator 1 ). The one control side of both external hydraulically actuated switching valves ZV2, ZV3 is spring-biased, wherein the other control side in each case with the consumption pressure of the first, and the second external control block 20 . 22 are charged.

It should be noted that the order of the serially arranged external hydraulically actuated switching valves ZV2, ZV3 is not arbitrary, but the required pressure drop of the external control blocks 20 . 22 in the consumer business corresponds. In other words, the hydraulically operated switching valve ZV2 of the first external control block 20 with the lower pressure gradient immediately downstream of the electromagnetic switching valve ZVA and is the hydraulically actuated switching valve Z3 of the second control block 22 followed by higher pressure gradient and so on.

The operation of the control arrangement according to the invention of the preferred embodiment is explained below:

1. Neutral circulation

• - All consumers are in neutral position.
•  The solenoid valve ZVA is not activated (preferably not energized).

In this control state, the consumer pressure main is 6 depressurized, since the control oil flow in the consumer pressure line 6 via the manually operated switching valves 12 in the pressure tank 4 is relaxed. Furthermore, the short circuit line 16 between the two control sides x, y of the pressure balance 1 locked because the intermediate hydraulically controlled switching valve ZV1 is not activated in the absence of a consumer pressure. In this case, the control pressure gradient is exclusive from the spring force of the preload spring on the pressure balance 1 depending on the selection of the spring force is set to a low value.

2. Consumer operated in the internal control block

• - ZVA solenoid valve not activated (not energized)
• - External consumers not actuated

When activating one or more (internal) consumers by manually actuating the corresponding internal switching valves 12 in the internal control block becomes the connection of the consumer pressure main 6 to the pressure tank 4 disabled and the consumer pressure signal on the selection of the shuttle valves (signal with the highest pressure value) via the throttle D1 to the spring-biased control side y of the pressure compensator 1 created. This closes the pressure balance 1 , whereby the pump pressure is no longer on the pressure compensator 1 in the tank 4 is relaxed, ie the system pressure increases.

Upon reaching a predetermined set pressure of the ΔP switching to be performed on the hydraulically controlled switching valve ZV1, the switching valve ZV1 opens the short-circuit line 16 , As a result, the control oil flow flows from the pump 2 to the spring-biased control side y of the pressure compensator 1 via the series connection of the chokes D2, D3. By a suitable diaphragm variation of the throttle D3, the pressurization of the spring-biased control side y of the pressure compensator changes 1 in such a way that the result is a spring reinforcement, ie a higher control pressure gradient. This in turn means that a larger flow of oil can be routed to the consumer.

3. Neutral circulation pressure increase for actuating external consumers

• - all consumers in neutral position
• - Magnet valve ZVA activated (energized)

According to the 1 is activated by activation of the solenoid valve ZVA, the short-circuit line 16 closed, creating a control oil flow from the pump 2 via a series connection of the throttles (diaphragms) D2 and DA and the pump-pressure-loaded control side x of the pressure compensator 1 flows to the spring-biased control side y. By a suitable diaphragm variation on the diaphragm DA can be the pressurization of the spring-biased control side y of the pressure compensator 1 change so that the desired control pressure increase over the standard neutral circulation described above is achieved.

The now increased neutral circulation pressure is required to control external consumers, such as solenoid valves with higher control pressure. Consequently, this pressure must be set so high that the external consumers switch safely, but as low as possible so that the pressure medium heating remains within a permissible range.

4. Activation of the external first control block

• - Solenoid valve ZVA activated (energized)
• - Internal consumers actuated / not actuated

By activating the solenoid valve ZVA is, as already described above under point 3, an increased neutral circulation pressure, which allows the switching of external consumers.

For the operation of these external consumers, an increased control pressure gradient may be required as the recirculation pressure differential described under point 2. This is realized by the switching of the hydraulically actuated switching valve ZV2, made possible by the consumer pressure of the external first control block 20 , the rest also via the switched external shuttle valve WSV-EX to the pressure compensator 1 (At the spring-biased control side y) passes. At the same time, this consumer or control pressure switches the switching valve ZV2. In this case, the series connection of the chokes D2 and D4 is active. By means of a suitable diaphragm variation at the diaphragm D4, it is thus possible to operate the external first control block 20 Set required control pressure increase.

5. Activation of the external second control block

• - solenoid valve ZVA activated (preferably by energization)
• - Internal consumers actuated / not actuated

To operate the external second control block 22 is essentially the same as described above under point 4, but with the proviso that the control pressure drop has been adjusted in this case to an even higher value. The required higher control pressure signal is selected at the shuttle valve WSV-EX and the pressure compensator 1 (passed to the spring-biased control side y). At the same time, the hydraulically actuated switching valve ZV3 switches by the supplied consumer pressure from the external second control block 22 and thus activates the diaphragm row D2 and D5. By means of a suitable diaphragm variation at the diaphragm D5, the even higher control pressure gradient for the external second control block 22 be set.

When disabling the external control blocks 20 . 22 the control pressure drop decreases to the increased neutral circulation pressure according to the description given in point 3. If now also the solenoid valve ZVA deactivated (de-energized), so this closes, ie it blocks the bypass line 18 and thus activates the diaphragm row D2 and D3. Thus, the neutral circulation pressure drops to the, set by means of the biasing spring lower neutral circulation pressure.

LIST OF REFERENCE NUMBERS

1

Proportional directional valve / pressure regulator

2

pump

4

tank

x

first control side of the pressure balance

Y

second control side of the pressure balance

D1

first throttle

D2

second throttle

6

Consumer pressure main pipe

8th

Pressure relief line

10

Pressure relief valve

12

internal switching valves

14

internal consumer pressure branch lines

16

Short-circuit line

ZV1

hydraulically controlled switching valve

D3

Orifice / throttle

18

bypass line

ZVA

magnetic valve

ZA

throttle

20

first ext. control block

22

second ext. control block

24

pump line

26, 28

ext. Consumer branch lines

30

ext. shuttle valve

ZV2, ZV3

ext. switching valves

D4

throttle

D5

throttle

Claims (8)

Hydraulic control arrangement with an inlet pressure compensator consisting of a proportional directional control valve ( 1 ), one control side (y) of which is supplied with a throttled consumer load pressure and a biasing spring and the other control side (x) with a throttled pump pressure and a hydraulically controlled switching valve (ZV1) for selectively throttling the two control sides (x, y) of the proportional directional control valve ( 1 ), characterized by an electromagnetic switching valve (ZVA), which optionally has a bypass line ( 18 ) to the hydraulically actuated switching valve (ZV1) opens to a throttled bypass connection between the two control sides (x, y) of the proportional directional valve ( 1 ) forcibly switch on. Hydraulic control arrangement according to claim 1, characterized in that the electromagnetic switching valve (ZVA) is a 2-position / 3-way switching valve with an output port connected to the spring-biased control side (y) of the proportional directional control valve (FIG. 1 ), a first input port which is connected to the hydraulically actuated switching valve (ZV1) and a second input port which is connected via the bypass line (ZV1). 18 ) with the controlled by the throttled pump pressure control side (x) of the proportional directional control valve ( 1 ), wherein the electromagnetic switching valve (ZVA) selectively connects its input terminals respectively to its output terminal. Hydraulic control arrangement according to one of the preceding claims, characterized in that the electromagnetic switching valve (ZVA) a preferably adjustable throttle (DA) in the bypass line ( 18 ) is connected upstream. Hydraulic control arrangement according to one of the preceding claims, characterized in that the hydraulically actuated switching valve (ZV1) a preferably adjustable throttle (D3) in one of the bypass line ( 18 ) bypassed line section is connected upstream. Hydraulic control arrangement according to one of the preceding claims, characterized by a number of consumers, each via an external control block ( 20 . 22 ), which are each connected to a pump pressure line ( 24 ) as well as a pressure compensator ( 1 ) leading consumer pressure line ( 26 . 28 ) via a shuttle valve ( 30 ) are connected. Hydraulic control arrangement according to claim 5, characterized in that according to the number of external control blocks ( 20 . 22 ) a number of hydraulically actuated 2-position / 3-way switching valves (ZV2, ZV3) serially into a short-circuit line ( 16 ) between the electromagnetic switching valve (ZVA) and the pressure compensator ( 1 ) whose output terminal is respectively connected to the one input terminal of the respective subsequent switching valve, the other input terminal via an external branch line to the acted upon by throttled pump pressure control side (x) of the pressure compensator ( 1 ) is connected and their respective one control side to the consumer pressure line ( 26 . 28 ) of the respectively assigned control block ( 20 . 22 ) connected. Hydraulic control arrangement according to claim 6, characterized in that in each external branch line a preferably adjustable throttle (D4, D5) is connected upstream of the respective hydraulically actuated switching valve (ZV2, ZV3). Hydraulic control arrangement according to one of the preceding claims, characterized that the pressure balance ( 1 ) is integrated in an internal control block in which a number of manually operable switching valves ( 12 ) are arranged for the activation of internal consumers, wherein each manually operable switching valve ( 12 ) a consumer pressure line ( 14 ) to the spring-biased control side (y) of the pressure compensator ( 1 ) leads, which is connected upstream of a throttle (D1) in the consumer line.

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