EP2496843B1 - Hydraulic control arrangement with a regulating pressure gradient which can be varied via an ls-valve - Google Patents

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 Fig. 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 pre-tensioning 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 difference 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 unacceptable is 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 Fig. 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 Fig. 3 the loss energy in the neutral circulation relative to the control arrangement according to the Fig. 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.

Another example is in DE 10011936 to find.

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 FIG. 3 shown known control arrangement. According to the invention, however, a further preferably electromagnetic switching valve is now arranged which selectively opens a bypass line to the hydraulically actuated switching valve to force-connect a throttled bypass 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 respective 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.

• Fig. 1 zeigt ein Schaltbild einer hydraulischen Steueranordnung insbesondere mit einer Eingangsdruckwaage mit einstellbarem Regeldruckgefälle für mehrere Verbraucher gemäß einem bevorzugten Ausführungsbeispiel der Erfindung,
• Fig. 2 zeigt ein Schaltbild einer hydraulischen Steueranordnung mit fixem Druckgefälle gemäß einem Stand der Technik und
• Fig. 3 zeigt ein Schaltbild einer hydraulischen Steuerung mit umschaltbarem Druckgefälle gemäß einem Stand der Technik.

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

• Fig. 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,
• Fig. 2 shows a circuit diagram of a hydraulic control arrangement with a fixed pressure gradient according to a prior art and
• Fig. 3 shows a circuit diagram of a hydraulic control with switchable pressure gradient according to a prior art.

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

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

The two control sides x, y of the pressure compensator forming proportional directional control valve 1 are hydraulically connected to each other via a short line 16, in which a hydraulically controlled switching valve ZV1, in the present case a 2/2-switching valve is interposed, whose one control side is spring-biased and the other control side of the pressure is acted upon by the spring-biased control side of the proportional directional valve 1. 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 Fig. 1 , Consequently, the functionality is identical, so at this point to the for Fig. 1 already explained technical explanations can be referenced.

Like from the Fig. 1 can be taken, the component combination consisting of the hydraulically controlled switching valve ZV1 and the immediately upstream throttle D3 is provided with a bypass line 18 bypassing this, the upstream of the throttle D3 branches off from the short-circuit line 16 and downstream to the hydraulically controlled switching valve ZV1 back in the short-circuit line 16 opens. In the bypass line 18, an electromagnetic 3-way / 2-position switching valve ZVA is interposed, a preferably adjustable throttle / aperture DA is connected 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) blocks the electromagnetic switching valve ZVA 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 Fig. 1 a number, in the present case two, external control blocks 20, 22 are shown, which are arranged to control external (not shown) consumers. Each external control block 20, 22 is connected via a pump line 24 directly to the pump 2 and further has an external consumer pressure branch line 26, 28, which opens via an external shuttle valve 30 in the consumer pressure main line 6. Each external control block 20, 22 is an external hydraulically controlled 3-way / 2-position switching valve ZV2, ZV3 assigned and connected in series in the short-circuit line 16 to the electromagnetic switching valve ZVA.

In the present exemplary embodiment, the hydraulically actuated switching valve ZV2 assigned to the first external control block 20 is immediately downstream of the electromagnetic switching valve ZVA, wherein one of its input terminals is connected to the output terminal of the electromagnetic switching valve ZVA and its second input terminal is connected via an immediately upstream, preferably adjustable Throttle D4 with the short-circuit line 16 upstream is connected to the throttle D3 (ie directly with the pump-pressure-loaded control side of the pressure compensator 1). Further, the external hydraulically-operated switching valve ZV3 associated with the second external control block 22 is immediately connected in the short-circuit line 16 to the external hydraulically operated switching valve ZV2 of the first external control block 20, and its one input port is connected to the output port of the external hydraulically-operated switching valve ZV2 of the first external control block 20 is and whose second input terminal is connected via an immediately upstream, preferably adjustable throttle D5 with the short-circuit line 16 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 acted upon.

It should be noted at this point that the order of the serially arranged external hydraulically actuated switching valves ZV2, ZV3 is not arbitrary, but corresponds to the required pressure drop of the external control blocks 20, 22 in the consumer mode. In other words, the hydraulically operated switching valve ZV2 of the first external pressure control block 20 is immediately downstream of the electromagnetic switching valve ZVA and is followed by the hydraulically operated switching valve Z3 of the second higher pressure differential control block 22 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 line 6 is depressurized, since the control oil flow in the consumer pressure line 6 via the manually operable Switching valves 12 is relaxed in the pressure medium tank 4. Furthermore, the short-circuit line 16 between the two control sides x, y of the pressure compensator 1 is locked, since the interposed hydraulically controlled switching valve ZV1 is not activated in the absence of a consumer pressure. In this case, the control pressure gradient depends solely on the spring force of the biasing spring on the pressure compensator 1, which is set according to the selection of the spring force to a low value.

2. Consumer operated in the internal control block

• Solenoid valve ZVA not activated (not energized)
• External consumers not actuated

When one or more (internal) consumers are activated by manual actuation of the corresponding internal switching valves 12 in the internal control block, the connection of the consumer pressure main line 6 to the pressure medium tank 4 is blocked and the consumer pressure signal via the selection of the shuttle valves (signal with the highest pressure value) on the Throttle D1 applied to the spring-biased control side y of the pressure compensator 1. This closes the pressure compensator 1, whereby the pump pressure is no longer released via the pressure compensator 1 in the tank 4, i. the system pressure increases.

Upon reaching a predetermined set pressure of the to be performed on the hydraulically controlled switching valve ZV 1 ΔP switching the switching valve ZV1 opens the short-circuit line 16. Thus, the control oil flow from the pump 2 to the spring-biased control side y of the pressure compensator 1 via the series circuit of the restrictors (aperture) D2, D3. By a suitable diaphragm variation of the throttle D3, the pressurization of the spring-biased control side y of the pressure compensator 1 changes, so that as a result a spring gain, i. a higher control pressure gradient arises. 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
• Magnetic valve ZVA activated (energized)

According to the Fig. 1 is closed by activating the solenoid valve ZVA, the short-circuit line 16, whereby a control oil flow from the pump 2 via a series circuit of the restrictors (orifices) D2 and DA and the pump-pressure-loaded control side x of the pressure compensator 1 to the spring-biased control side y flows. By a suitable aperture variation on the diaphragm DA, the pressurization of the spring-biased control side y of the pressure compensator 1 can be changed 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, which also passes via the switched external shuttle valve WSV-EX to the pressure compensator 1 (to the spring-biased control side y). 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, the control pressure increase required for operating the external first control block 20 can thus be set.

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, essentially the same applies, as described above under point 4, but with the proviso that the control pressure gradient 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 passed to the pressure compensator 1 (at 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 can be set.

When deactivating the external control blocks 20, 22, the control pressure drop decreases to the increased neutral circulation pressure according to the description given under point 3. If now also the solenoid valve ZVA deactivated (de-energized), so this includes, i. 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.

Claims (8)

1. Hydraulic control arrangement having an inlet pressure balance composed of a proportional directional valve (1), one control side (y) of which is acted on with a throttled consumer load pressure and by a preload spring, and the other control side (x) of which is acted on with a throttled pump pressure, and having a hydraulically controlled switching valve (ZV1) for the selected throttled connection of the two control sides (x, y) of the proportional directional valve (1), characterized by an electromagnetic switching valve (ZVA) which selectively opens a bypass line (18) past the hydraulically actuated switching valve (ZV1) in order to forcibly activate a throttled bypass connection between the two control sides (x, y) of the proportional directional valve (1).
2. 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 outlet port, which is connected to the spring-preloaded control side (y) of the proportional directional valve (1), with a first inlet port, which is connected to the hydraulically actuated switching valve (ZV1), and with a second inlet port, which is connected via the bypass line (18) to the control side (x), which is acted on by the throttled pump pressure, of the proportional directional valve (1), wherein the electromagnetic switching valve (ZVA) selectively connects its inlet ports in each case to its outlet port.
3. Hydraulic control arrangement according to one of the preceding claims, characterized in that a preferably adjustable throttle (DA) is connected upstream of the electromagnetic switching valve (ZVA) in the bypass line (18).
4. Hydraulic control arrangement according to one of the preceding claims, characterized in that a preferably adjustable throttle (D3) is connected upstream of the hydraulically actuated switching valve (ZV1) in a line portion which is bypassed by the bypass line (18).
5. Hydraulic control arrangement according to one of the preceding claims, characterized by a number of consumers which can be actuated in each case by means of an external control block (20, 22), said external control blocks being connected in each case to a pump pressure line (24) and to a consumer pressure line (26, 28), which leads to the pressure balance (1), via a shuttle valve (30).
6. Hydraulic control arrangement according to Claim 5, characterized in that, corresponding to the number of external control blocks (20, 22), a number of hydraulically actuated 2-position/3-way switching valves (ZV2, ZV3) are interconnected in series in a short-circuit line (16) between the electromagnetic switching valve (ZVA) and the pressure balance (1), the outlet port of said switching valves being connected in each case to one inlet port of the respectively subsequent switching valve, the other inlet port of said switching valves being connected via in each case one external branch line to the control side (x), which is acted on with throttled pump pressure, of the pressure balance (1), and in each case one control side of which switching valves being connected to the consumer pressure line (26, 28) of the respectively associated control block (20, 22).
7. 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).
8. Hydraulic control arrangement according to one of the preceding claims, characterized in that the pressure balance (1) is integrated into an internal control block in which there are arranged a number of manually actuable switching valves (12) for the activation of internal consumers, wherein, from each manually actuable switching valve (12), a consumer pressure line (14) leads to the springpreloaded control side (y) of the pressure balance (1), directly upstream of which in the consumer line there is connected a throttle (D1).

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