KR20130124432A - Hydraulic control device with load pressure reduction and hydraulic valve block therefor - Google Patents

Abstract

Disclosed is a hydraulic control device having a controllable hydraulic pump which supplies pressure media to one or more hydraulic consumers. The control device comprises: a pump controller which controls the volume flow of an adjustment device of the hydraulic pump according to the transmission pressure or the maximum load pressure of the hydraulic consumers; and a pressure reducing device for the maximum load pressure, which can be controlled according to the volume flow of the adjustment device.

Description

HYDRAULIC CONTROL DEVICE WITH LOAD PRESSURE REDUCTION AND HYDRAULIC VALVE BLOCK THEREFOR}

The present invention relates to a hydraulic control device comprising a load reducing part according to the preamble of claim 1 and a hydraulic valve block for the control device according to the preamble of claim 15.

In the working machine, in particular in a compact mobile design, for example a compact or compact excavator, a backhoe loader or a telescopic handler, the hydraulic consumer is supplied with a discharge volume which is preferably adjustable by a hydraulic pump. . Distribution of the volume flow is made by control valves, which must ensure a balanced sequence of movements even in the operation of multiple consumers. The adjustment of the delivery volume flow of the hydraulic pump is made by a pump regulator in the case of a load sensing system, in which the maximum load pressure of the consumer on the one hand and the delivery pressure of the hydraulic pump on the other hand are transmitted. For load pressure compensation pressure medium distribution (LUDV) with a hydraulic consumer, individual pressure retention valves can be connected to the rear of the control valves, respectively, and all the individual pressure retention valves are supplied with the maximum load pressure of the consumer in the closing direction. . On the contrary, in the load sensing principle LS, the individual pressure holding valves are connected in front of the control valve, and all the individual pressure holding valves are supplied with the load pressure of the corresponding consumer in the open direction.

In general, since the delivery volume flow of the hydraulic pump is controlled during such load sensing control, the operator can adjust the speed of the hydraulic consumer (s). The delivery pressure of the hydraulic pump is automatically controlled in accordance with the resistance of the consumer (s). The pressure is limited to the maximum system pressure. Therefore, since the pressure in the cylinder is not controlled, the acceleration of the cylinder force and the working motion is not controlled. This property makes the working movements, especially those associated with mass, such as rotation or boom rattle and cause vibration. This reduces the controllability of the working movement of the machine, undesirably affects the structure of the operating machine, and can cause breakage and failure.

In order to eliminate this drawback, it is known in the prior art to provide pressure dependent leakage to the maximum load pressure involved in volume flow control, for example via a throttle, to influence the pressure rise behavior in the system. This may damp the pressure rise in the acceleration phase of the consumer. However, since leakage flow is load-dependent in this simple solution and exists even at standstill, i.e. without acceleration, this undesirably causes the hydraulic pump to permanently compensate for the leakage flow, which causes The total pump output is not available for operation and the efficiency is lowered.

In order to better use the control area of the control valve which has a measuring opening and can regulate the pressure medium volume flow to the consumer, DE 10 2004 061 555 A1 discloses a hydraulic control device comprising an adjustable LS-pump device. have. Maximum pressure is transmitted via the LS-line to the individual pressure retention valve connected behind the measuring opening. The LS-line is connected to the pressure medium sink via a flow regulator, in which case the flow regulator can be adjusted according to the pump speed. The regulation is such that the leakage decreases as the speed of the pump increases. In this case, the load reduction acting on the pump adjustment is not relevant. Instead, the leakage produced as intended by the LS-line reduces the effective pressure differential in the measuring opening of the control valve. Therefore, the volume flow sent to the consumer is smaller.

Even in this solution, the disadvantage is that a permanent leakage flow is provided from the load transmission line which has to be replaced by a hydraulic pump. This prevents the full use of the pump output and reduces the efficiency.

An object of the present invention is to provide a hydraulic control device having an increased efficiency and a control block therefor.

The problem is solved by a hydraulic control device having a load pressure reducing section comprising the features of claim 1 and a hydraulic valve block for this comprising the features of claim 15.

Preferred refinements of the hydraulic control device are described in claims 2 to 14.

In particular, hydraulic control devices for mobile work machines such as, for example, compact or compact excavators, backhoe loaders or telescopic handlers, comprise a hydraulic pump, through which the pressure medium is supplied to at least one hydraulic consumer via the delivery line of the pump. Can be. In addition, the control device includes a pump regulator, which is limited in time by the pump regulator in accordance with the delivery pressure and the maximum load pressure of the hydraulic consumer (s), in particular with respect to the adjustment of the hydraulic pump. The regulating volume flow can be adjusted. The hydraulic control device also includes a pressure reducing device for maximum load pressure. According to the invention the pressure reduction device can be adjusted according to the control volume flow.

This allows the leakage of the maximum load pressure, or the leakage flow from the volume with the maximum load pressure ("bleed-off"), unlike the prior art, is not the level of the output volume flow or load pressure of the hydraulic pump, but rather the level of the hydraulic pump. May be involved, in particular related. In other words, the load pressure is reduced only when the regulating volume flow is provided, and accordingly the delivery volume of the hydraulic pump is changed. In this case the already existing "signal" of the pump regulator (regulating volume flow) is used. Unlike the prior art, decompression offers the advantage of being directly related to the operating state in which the hydraulic consumer (s) is accelerated (negative or positive). This allows the decompression to be omitted in the stationary state of the hydraulic consumer (s), ie when it does not need to be accelerated. Thus, an unreduced pump output is provided, which increases the efficiency of the hydraulic consumer and enables higher working speeds.

In a preferred and particularly preferred refinement of the invention, the decompression device can be adjusted such that the greater the depressurization of the maximum load pressure, the greater the control volume flow for increasing the delivery volume of the hydraulic pump. This allows smooth acceleration or shock-free starting of one or more hydraulic consumers. In addition, vibration is reduced. This is particularly desirable when a load with a large mass of hydraulic consumer is to be accelerated.

In another particularly preferred and preferred refinement, the decompression device can be adjusted such that the decompression of the maximum load pressure is approximately O when the regulating volume flow for increasing the delivery volume of the hydraulic pump is zero. This is preferably the case where no consumer requires a fluctuation in the delivery volume, so that no adjustment of the hydraulic pump is necessary. The hydraulic pump is in a regulated fixed state. That is, the adjusting volume flow chart of the pump regulator is zero except for a slight leakage. If the maximum load pressure does not decrease in this regulated state or if the leakage flow (“bleed off”) is zero from the volume with the maximum load pressure, this results in the hydraulic pressure supplying the leakage flow in a preferably regulated state. The output of the pump is close to zero. Thus, the total pump output can be provided to the hydraulic consumer (s). This allows higher movement speeds of the hydraulic consumer (s) to be achieved in the adjusted state. Therefore, the efficiency of the hydraulic control device is increased.

In a preferred refinement, the pressure reducing device comprises a proportional directional valve having a load pressure connection and a low pressure connection. In this case, the load pressure connection and the low pressure connection having a load transmission line capable of supplying the maximum load pressure can be connected to the pressure medium sink, in particular the tank, in particular via the low pressure line. The implementation as a proportional directional valve is device technically simple and enables metered decompression of the maximum load pressure.

In a preferred refinement, the hydraulic control device comprises a discharge line, through which the discharge connection of the pump regulator can be connected to a pressure medium sink, in particular a tank.

In another preferred refinement the proportional directional valve of the pressure reducing device comprises a throttle end position as well as one throttle end position capable of connecting the load pressure connection to the low pressure connection of the proportional directional valve. The valve body of the proportional valve, in particular the valve piston or valve slide, can be supplied with a discharge pressure of the discharge line in the direction of the throttle end position. Preferably the proportional directional valve has a blocking position under spring prestressing, by which the load pressure connection can be separated from the low pressure connection in particular substantially without leakage. Particularly preferably, the proportional directional valve of the pressure reducing device is formed as a 2/2 proportional directional valve.

In a particularly preferred refinement the discharge line is arranged with a throttle device, in particular a throttle having a constant or adjustable cross section. The valve body of the proportional directional valve of the pressure reducing device can be supplied with a discharge pressure in the direction of the throttle end position via a control line connected to the discharge line upstream of the throttle device. As such, the regulating volume flow of the pump regulator, ie in this case the pressure medium sink discharge volume flow from the pump regulator, can be used as a regulating signal generator for the proportional directional valve of the pressure reducing device. The larger the discharge volume flow of the pump regulator, the greater the pressure in the control line, which moves the valve body of the proportional valve of the pressure reducing device from the shutoff position toward the throttle end position of the proportional valve.

In a preferred refinement the pump regulator comprises a proportional directional valve, the valve comprising a delivery line connection, through which the proportional direction valve can be connected to the delivery line. The valve also comprises a discharge connection of a pump regulator, through which the valve can be connected to a pressure medium sink, in particular a tank. In addition, the valve may include a regulating connection, through which the valve may be connected to a regulating device. In addition, the proportional directional valve of the pump regulator comprises an inlet position and an inlet end position, through which the outlet line can in particular be connected to a regulating device to form an inlet volume flow. In addition, the proportional directional valve of the pump regulator includes a discharge position and a discharge end position, through which the regulating device can be connected in particular to the pressure medium sink to form a discharge volume flow.

In a particularly preferred refinement, the valve body of the proportional valve of the pump regulator can be supplied with the maximum load pressure in the direction of the discharge end position and the spring equivalent of the regulating spring, and the discharge pressure of the hydraulic pump in the direction of the inlet end position. Can be. Particularly preferably the proportional directional valve of the pump regulator is a 3/2 proportional directional valve.

In order to damp the switching vibrations when the discharge volume flow decreases while the proportional directional valve of the depressurization device is moved in the direction of its blocking position, a preferred refinement of the invention is connected to the throttle device or the throttle device and parallel to the control line And a check valve opened by the discharge pressure. This solution allows for delayed switch off or deactivation of the decompression, thus enabling adjustment to system dynamics.

In order to be able to stop the decompression of the maximum load pressure as intended, the throttle device disposed in the discharge line is formed as a directional valve having a spring prestressed throttle shift position and an actuated through flow shift position. If the perfusion diverting position is not activated and therefore the throttle base position is provided, immediately enough flow volume of discharge volume flows from the pump regulator through the discharge line into the discharge line to regulate the discharge pressure and the maximum load pressure is reduced as described above. . In contrast, when the directional valve of the throttle device of the discharge line is operated to occupy the perfusion switching position, the decompression device does not operate since no discharge pressure can be formed in the discharge line, and preferably no reduction in the maximum load pressure is achieved. .

This refinement is particularly preferred when the hydraulic control device comprises a hydraulically operable hydraulic consumer and the consumer is dynamically operated. A control valve is assigned to the consumer and the control valve is connected to the delivery line of the hydraulic pump. This refinement of the hydraulic control also includes an operation unit, which is connected to a control valve for control of the first working position via the first control signal line. Further, since the first control signal line is connected to the directional valve of the throttle device of the discharge line, the perfusion switching position of the directional valve can be switched via the first control signal line. In the case where the dynamically actuated hydraulic consumer is controlled by the operation unit and the first control signal line, at the same time, since the directional valve of the throttle device is controlled to the perfusion switching position, the decompression of the maximum load pressure is deactivated during the operation time.

In the case where the dynamically operable hydraulic consumer has two directions of movement, the operation unit is preferably connected to a control valve for control of the second working position via the second control signal line. Since the second control signal line is also connected to the directional valve of the throttle device of the discharge line, the perfusion switching position of the directional valve can also be controlled by the second control signal line. This allows the decompression of the maximum load pressure for the dynamic operation of the hydraulic consumer to be deactivated in two working directions.

In the case where the control valve of the dynamic actuated hydraulic consumer is controlled by the control pressure through the operation unit, the first and second control signal lines are control pressure lines. The control pressure lines are connected to the input of the shuttle valve, in which case the output of the shuttle valve is connected to the control pressure input of the directional valve of the throttle device of the discharge line. This ensures that the maximum control pressure of the dynamic hydraulic consumer is always connected to the control pressure input of the directional valve.

Preferably the hydraulic pump is formed as an axial piston or radial piston or vane pump.

Preferably the hydraulic pump operates at a constant speed. Alternatively, the hydraulic pump may operate at variable speeds.

The above-mentioned decompression of the maximum load pressure in the hydraulic control device constructed in accordance with the load sensing principle LS or the load pressure compensation pressure medium distribution (LUDV) principle proves to be particularly desirable. In the former case, one measuring opening is assigned to each hydraulic consumer in the delivery line of the hydraulic pump, and one individual pressure retention valve is allocated upstream of the measuring opening. In this case, the load pressure of the hydraulic consumer assigned in the opening direction is supplied to the individual pressure retention valve, and the pressure between the individual pressure retention valve and the measurement opening is supplied in the closing direction. In the latter case (LUDV) in the delivery line of the hydraulic pump, one measuring opening and a separate pressure retention valve are each assigned to each hydraulic consumer. The individual pressure holding valves are arranged downstream of the measuring openings, in which case each individual pressure holding valve is supplied with the maximum load pressure of the hydraulic consumer (s) in the closing direction-in contrast to the LS principle-and in the opening direction. And pressure between the individual pressure retention valves is supplied.

The above-mentioned decompression part according to the present invention of the maximum load pressure by the hydraulic valve block can be implemented in device technically particularly compactly. For control of an adjustable hydraulic pump having a delivery line capable of supplying pressure medium to at least one hydraulic consumer, the hydraulic valve block comprises a pump regulator, and by means of the pump regulator the delivery pressure and hydraulic consumer of the hydraulic pump ( The regulating volume flow for the regulating device of the hydraulic pump can be regulated in accordance with the maximum load pressure in particular. The valve block also includes a pressure reducing device for maximum load pressure. According to the invention the pressure reduction device can be adjusted according to the control volume flow. Hydraulic pumps, hydraulic consumer (s), pump regulators, regulating volume flow, regulators of hydraulic pumps, pressure reducing devices, preferred ways of their operation and interaction correspond to the foregoing description.

In the following three embodiments of a hydraulic control apparatus according to the invention are described with reference to three circuit diagrams and one diagram.

1 shows a first embodiment of a hydraulic control device including a load reducing unit.
FIG. 2 shows a second embodiment of a hydraulic control device including damping of a load reducing part. FIG.
FIG. 3 shows a third embodiment of a hydraulic control device comprising blocking of the load pressure reducing part and damping according to FIG. 2.
4 shows a control diagram of a pump regulator of three embodiments.

The hydraulic control device 1 of the compact type excavator according to FIG. 1 comprises a hydraulic pump 2 having an adjustable delivery volume. A pressure medium can be supplied to a plurality of hydraulic consumers (see FIG. 3) via the delivery line 4 of the hydraulic pump 2. Of the hydraulic consumers, only the first hydraulic consumer 6 is shown according to FIG. 1, which is formed by a double rod cylinder comprising a piston rod on one side for control of the boom of a compact excavator. A control valve 8 is assigned to the consumer for control of the first hydraulic consumer 6. The control valve 8 is formed as a 6/3 proportional directional valve with a spring centered shut off position. The control valve 8 is connected to the delivery line 4 of the hydraulic pump 2 via the work line 10, and the working chamber 16, of the first hydraulic consumer 6, via the work lines 12, 14. 18). For operation of the control valve 8 the hydraulic control device 1 comprises an operation unit 20 formed of a joystick. The operating unit 20 is connected to two control pressure lines 22, 24, through which the valve slide 26 of the control valve 8 can be controlled to its perfusion positions 8a, 8b. Can be. In order to discharge the pressure medium from the hydraulic consumer 6 in the direction of the tank T, the control valve 8 comprises a tank connection T, which is connected to the tank T via the tank line 28. To the pressure medium is connected.

The hydraulic control device 1 is based on the load sensing principle. For this purpose the control device comprises a load transmission line 30 in which the maximum load pressure of the hydraulic consumer 6 is generated. The maximum load pressure is involved in the adjustment of the hydraulic pump 2. The hydraulic pump comprises a pump regulator 32, which is formed as a proportional directional valve having three connections and two end positions. The pump regulator 32 is connected via a pressure medium line 34 to the regulating device 36 of the hydraulic pump 2 which is simply formed as a hydraulic cylinder. In addition, the pressure connection P of the pressure regulator 32 is connected to the delivery line 4 of the hydraulic pump 2 via the pressure line 38. The tank connection T of the pump regulator 32 is also connected to the pressure medium to the tank T via the discharge line 40. The pump regulator 32 has an inlet end needle value 32a and an outlet end position 32b. The valve piston 33 of the pump regulator 32 is supplied with the delivery pressure in the delivery line 4 in the direction of the inflow position 32a of the pump regulator, and the load transmission line 30 in the direction of the discharge position 32b. The maximum load pressure in the chamber and the pressure equivalent of the adjustment spring 32c are supplied. The pump regulator can be continuously adjusted between the end positions.

Three load pressure lines 44, 46, 48 diverge from the load transmission line 30. In the load pressure line 44 an adjustable pressure limiting valve 50 for limiting the maximum load pressure is arranged. The pressure limiting valve 50 depressurizes the load transmission line 30 to the tank T. The flow regulator 52 is disposed in the load reducing line 46. The flow regulator prevents the hydraulic pump from supplying high pressure in this idle state of the consumer, since the load pressure is reduced when the hydraulic consumer does not require a pressure medium and the assigned control valves have their shut off position. This contributes to the energy efficiency of the control device 1. The flow regulator 52 discharges 0.7 l / m constantly from the load transmission line irrespective of the maximum load pressure, ie even under load. In order to prevent blockage or damage of the flow regulator 52, a filter 54 is connected in front of the flow regulator 52.

In the load pressure line 48 a pressure reducing device 56 according to the invention is arranged for the reduction of the maximum load pressure in the load transmission line 30. The depressurization device 56 is formed as a 2/2 proportional directional valve which is spring prestressed in the shutoff position 56a. The directional valve has a throttle end position 56b in addition to the shutoff position 56a. The proportional directional valve of the pressure reducing device 56 comprises a tank connection T, which is connected to the tank T via a low pressure line 58. The pressure in the tank line 58 and the pressure equivalent of the spring 56c are supplied in the direction of the shutoff position 56a of the proportional valve. The proportional direction valve of the decompression device 56 is supplied with a discharge pressure upstream of the discharge line 40 and the throttle device 42 in the direction of its throttle end position 56b. To this end the proportional directional valve of the pressure reducing device 56 is connected via a control line 60 to the discharge line 40 upstream of the throttle device 42.

The load sensing hydraulic control device 1 according to the first embodiment of FIG. 1 comprises a load pressure compensated pressure medium distribution LUDV. For this purpose the control device 1 has a separate pressure retention valve 62 formed as a 3/3 proportional directional valve downstream of the control valve 8. The pressure retention valve has a closed end position 62a, one or more adjustment positions 62b and an open end position 62c. The valve slide 64 of the individual pressure retention valve 62 is supplied with the maximum load pressure in the load transmission line 30 in the direction of the cutoff end position 62a. The pressure of the measuring opening 66a or the control valve 8 downstream is supplied to the valve slide 64 of the individual pressure holding valve 62 in the direction of the open end position 62c. The individual pressure retention valves comprise a pressure connection P connecting the pressure retention valve to the pressure connection P 'of the control valve 8 and a load transmission connection L connecting the pressure retention valve to the load transmission line 30. ) And a pressure connection P 'connecting the individual pressure retention valve to the inlet connection Z of the control valve 8 via an inlet line 68. In the inlet line 68 a check valve 70 is arranged which opens towards the consumer 6 in order to prevent the load reduction of the hydraulic consumer 6.

The mode of operation of the pressure reducing part according to the invention of the maximum load pressure is described. A stationary operating state of the control device 1 is assumed, in which the hydraulic consumer 6 supports the load and therefore should not be accelerated. At this point, the hydraulic pump 2 rotates at a constant speed. The load on the hydraulic consumer 6 is now lifted. For this purpose, the operator uses the operating unit 20, the joystick of the operating unit being regulated so that the control pressure is supplied via the control pressure line 24 to the valve piston 26 of the control valve 8. The valve piston 26 of FIG. 1 is then moved downwards in the direction of the perfusion position 8b from the cut off position shown. This causes the pressure medium to pass through the measuring opening 66b via the pressure connection P of the delivery line 4, the work line 10 and the control valve 8, and the pressure connection P of the individual pressure retention valve 62. Begin to flow. The valve piston 64a of the individual pressure retention valve 62 is supplied with the maximum load pressure in the load transmission line 30 in the direction of the closed position 62a at this time, and the measurement opening (in the direction of the open end position 62c). 66b) The back pressure is supplied. In the case where the hydraulic consumer 6 shown is a hydraulic consumer with a maximum load pressure, the individual pressure retention valve 62 is opened at the open end position of the valve piston 64 via the adjustment position 62b within a few thousandths of a second. Switch to 62c). At this moment, the pressure connection P of the individual pressure retention valve 62 is connected to the load pressure connection L or the load transmission line 30 on the one hand, and to the inlet line 68 on the other hand, and The inflow line is connected to the connecting portion Z of the control valve 8. The pressure medium flows through work line 12 into work chamber 16 of hydraulic consumer 6 via direction 67b of perfusion position 8b of control valve 8. At the same time the load pressure of the hydraulic consumer 6 is transmitted to the pump regulator 32 via the load transmission line 30. This is made such that the load pressure and the pressure equivalent of the regulating spring 32c are supplied to the valve piston 33 of the pump regulator 32 in the direction of the discharge position 32b. The sum of the load pressure transmitted in this acceleration state of the hydraulic consumer 6 and the pressure equivalent of the regulating spring 32c is greater than the delivery pressure in the delivery line 4, and the flow pressure is introduced into the valve piston 33 at the inflow position ( Supplied in the direction of 32a). According to the degree of acceleration of the hydraulic consumer 6 required by the operation unit 20, the discharge cross section which opens to some extent in the discharge position 32b in the pump regulator 32 is adjusted. Pressure medium flows through the pressure medium line 34 from the working chamber 35 of the hydraulic cylinder of the regulating device 36 into the discharge line 40 toward the tank T. The throttle device 42 disposed in the line raises the discharge pressure in the discharge line, the discharge pressure being the valve of the pressure reducing device 56 formed as a 2/2 proportional valve via the control line 60. Acts on the control surface of the piston. The pressure reduction device is thereby adjusted in the direction of the throttle position 56b from the blocking position 56a. The load pressure is reduced.

The greater the discharge pressure in the control line 60, the faster the pressure reducing device 56 is adjusted to its throttle position 56b. Since the discharge pressure increases as the discharge volume flow in the discharge line 40 increases, the greater the difference between the maximum load pressure transmitted and the delivery pressure of the hydraulic pump 2 reduced by the pressure equivalent of the regulating spring 32c, the greater the difference. , The load reduction becomes bigger.

In this case, the response behavior of the pressure reducing device 56 is determined by the strength of the spring 56c of the device and the cross section of the throttle device 42. The weaker the spring and / or the smaller the throttle cross section, the smaller the discharge volume flow can be, and the adjustment is effected from the discharge volume flow to the throttle position 56b of the decompression device 56. Conversely, the discharge volume flow should increase for the activation of the throat position 56b as the spring is stronger and / or the throttle cross section is larger.

When the load of the hydraulic consumer 6 is no longer accelerated or lifted, the operation unit 20 is set to the neutral position. The control valve 8 then returns to its blocking position, again centered by the spring. As a result, the pressure medium is no longer supplied to the individual pressure maintaining valve 62 by the control valve 8. By means of a flow regulator 52 which permanently discharges 0.7 l / m pressure medium volumetric flow from the load transmission line 30 irrespective of the operating state of the control device, the hydraulic consumer 6 in the load transmission line 30 The maximum load pressure transmitted first decreases. The force balance is moved in the pump regulator 32 so that the valve piston 33 is adjusted in the direction of the inflow position 32a. Along with this, the discharge volume flow in the discharge line 40 continues to decrease, and the delivery volume of the hydraulic pump 2 decreases. As a result, the discharge pressure in the control line 60 is also reduced, so that as soon as the force of the spring prevails, the spring 56c of the pressure reducing device 56 again adjusts the valve piston in the direction of the shutoff position 56a. The maximum load pressure applied to the load transmission line 30 upon reaching the blocking position 56a no longer decreases.

 As set forth in the foregoing description, the positive speed change or acceleration or working movement of the consumer 6 is caused by the expansion of the delivery volume of the hydraulic pump 2. The working chamber 35 of the hydraulic cylinder of the regulating device 36 is connected to the tank T via the pump regulator 32 in the manner described in order to enlarge the delivery volume. The resulting discharge volume flow provides a pressure drop by the throttle device 42, which activates the throttle position 56b. As soon as the delivery volume flow of the hydraulic pump 2 has achieved the required working speed or position of the load to be lifted, the pressure drop by the throttle device 42 no longer flows because the regulating volume flow or discharge volume flow no longer flows. Not enough, and the decompression device 56 takes the blocking position 56a.

In order to damp this blocking process of the decompression section, a second embodiment of the hydraulic control device 101 according to FIG. 2 is connected to the throttle device 170 and parallel thereto to the control line 60 and inside the discharge line 40. It includes a check valve 172 that opens at the discharge pressure of. The second embodiment according to FIG. 2 corresponds to the first embodiment according to FIG. 1 except for the two complements.

The third embodiment according to FIG. 3 shows a hydraulic control device 201, which corresponds substantially to the second embodiment according to FIG. 2. The following description illustrates the difference from the two one embodiments.

3 shows hydraulic consumers 206, 306, 406 not shown in FIGS. 1 and 2. The consumer 206 is a hydraulic motor for the movement of the rotary unit, the hydraulic consumer 306 is a differential hydraulic cylinder for the movement of the shovel arm, and the hydraulic consumer 406 is a differential cylinder for the movement of the shovel of the compact excavator. The hydraulic consumers 6, 206, 306 are controlled by the operation unit 220, which corresponds to the operation units of the two first embodiments. 3 further shows control pressure lines 222, 224 and 322, 324, by which the consumer 206, 306 or the control valves 208, 308 of the consumer can be controlled. The operating unit 420 thus comprises control pressure lines 422, 424 for the control of the control valve 408. The control valves 208, 308, 408 correspond to the control valve 8 according to the first two embodiments. Separate pressure retention valves 262, 362, 462 are connected behind each control valve 208, 308, 408. The individual pressure retention valves correspond to the individual pressure retention valves 62 according to the first and second embodiments. In addition, the integration of the individual pressure retention valves 262, 362, 462 and the control valves 208, 308, 408 into the hydraulic control device, the control valve 8 and the individual pressure retention according to the first and second embodiments Corresponds to the integration of the valve 62. Thus, load pressure compensated pressure medium distribution (LUDV) is implemented for all consumers 6, 206, 306, 406.

The hydraulic consumer 406, which can move the excavator of the compact excavator, must be able to be dynamically adjusted under certain operating conditions. This is particularly related to the vibration or shaking of the shovel. Since this vibration is related to the strong acceleration of the shovel, a high load pressure occurs in accordance with the above description, which can cause a strong adjustment of the hydraulic pump 2 in the direction of a larger delivery volume, which leads to a discharge line ( It is possible to increase the discharge volume flow in 40). The above-mentioned decompression portion of the maximum load pressure can be activated without other measures, which can inhibit the predetermined dynamic operation of the shovel.

Nevertheless, in order to enable dynamic operation of the hydraulic consumer 406, the hydraulic control device 201 is switchable instead of a constant throttle device 42 in the discharge line 40 and subjected to spring prestress in the throttle position 276. Directional valve 274. The directional valve also has an actuation through flow position 278. The control device 201 also includes a shuttle valve 280, the inputs of which are controlled pressure lines 222, 224 of the operation unit 420 of the dynamically actuated hydraulic consumer 406. Is connected to. The output of the shuttle valve 280 is connected to the directional valve 274 such that the passing control pressure moves the valve piston of the directional valve 274 in the direction of the perfusion switching position 278. By means of the apparatus described above, it is possible to block the decompression unit according to the invention of the maximum load pressure in the load transmission line 30 during the dynamic operation of the hydraulic consumer 406.

4 shows the pump regulator in cross section on the left side of FIG. 4 to illustrate the behavior of the pump regulator 32 and the corresponding control diagram is shown on the right side in FIG. 4. According to FIG. 4, the pump regulator is shown in the discharge position or the discharge end position 32b, in which the pressure medium line 34, the connection A, by means of an unshown hydraulic cylinder or an unshown adjusting device of the hydraulic pump. And discharge volume flow through the connection T into the discharge line 40. This corresponds to the aforementioned enlargement of the delivery volume of the hydraulic pump. The pump regulator 32 is fully open. In the control diagram shown on the right, the control position corresponds to point 1. At the same time, the connecting portion P connected to the delivery line of the hydraulic pump is separated from the connecting portion A. FIG.

When the valve piston 33 of the pump regulator 32 is moved in the direction of its adjustment distance S, the aforementioned discharge volume flow decreases the control cross section of the pump regulator 32 from the connection A to the connection T. Is gradually throttled. This relationship between the adjustment distance S of the pump regulator 32 and the open cross section is shown by the curve A → T on the right side of FIG. 4. As the maximum load pressure generated in the load transmission line 30 is closer to the delivery pressure reduced by the pressure equivalent of the adjustment spring 32c, the valve piston 33 moves the inflow position A in the direction of the adjustment distance S thereof. More towards). In the intermediate shut-off position of the valve piston 33 shown at point 2 in the diagram, the two connections P, T of the pump regulator 32 are separated from the connection A. FIG. When the load pressure generated in the load transmission line 30 is smaller than the delivery pressure reduced by the pressure equivalent of the adjustment spring 32c, the valve piston 33 is further moved in the direction of the adjustment distance S, so that the connection portion The connection between them P and A is controlled. At the same time the connection between the connections T, A is kept closed. The controlled connection thus causes a pressure medium flow from the pump delivery line to the working chamber of the hydraulic cylinder of the hydraulic pump's regulating device, which changes the delivery volume of the hydraulic pump.

Unlike the embodiment shown, the control device according to the invention comprising a load pressure reducing part is also suitable for a closed circuit.

A hydraulic control device with an adjustable hydraulic pump is disclosed, in which a pressure medium can be supplied to at least one hydraulic consumer. The control device includes a pump regulator, by which the adjustable volume flow of the regulating device of the hydraulic pump can be adjusted according to the delivery pressure or the maximum load pressure of the hydraulic consumer (s). The control device also includes a decompression device for maximum load pressure. In this case, the decompression device may be adjusted according to the control volume flow of the control device.

1; 101; 102 hydraulic control
2 hydraulic pump
4 sending lines
6; 206; 306; 406 Hydraulic Consumer
8; 208; 308; 408 Control Valve
8a, 8b perfusion position
10, 12, 14; Work line
210, 310, 410,
212, 312, 412,
214, 314, 414
16, 18 working chamber
20; 220, 420 operation unit
22, 24; Control pressure line
222, 322, 422,
224, 324, 422
26 valve slide
28 tank lines
30 load transmission line
32 pump regulator
32a inlet position
32b discharge position
32c adjustable spring
33 valve piston
34 pressure medium lines
35 working chamber
36 regulator
38 pressure lines
40 discharge lines
42 throttle gear
44, 46, 48 load pressure line
50 pressure limiting valve
52 Flow Regulator
54 filters
56 decompression device
56a blocking position
56b throttle position
56c spring
58 low pressure line
60 control lines
62; 262, 362, 462 Individual Pressure Retention Valves
62a blocking position
62b adjustable position
62c open end position
64 valve slide
66a, 66b; Measuring aperture
266a, 266b, 366a
366b, 466b, 466b
67a, 67b direction
68 supply lines
170 throttle gear
172 check valve
274 directional valve
276 throttle shift position
278 perfusion switching position
280 shuttle valve

Claims (15)

A hydraulic control comprising an adjustable hydraulic pump (2), a pump regulator (32) and a decompression device (56) for maximum load pressure, wherein at least one hydraulic consumer (6) is via the delivery line (4) of the hydraulic pump. A pressure medium may be supplied to the 206, 306, 406, and the hydraulic pump 2 depends on the delivery pressure and the maximum load pressure of the hydraulic consumer (s) 6; 206, 306, 406 by the pump regulator. In the hydraulic control device in which the control volume flow of the adjusting device 36 of the
The pressure reducing device (56) is a hydraulic control device, characterized in that can be adjusted according to the control volume flow. The hydraulic pressure control device according to claim 1, wherein the pressure reduction device (56) can be adjusted so that the pressure reduction becomes larger as the control volume flow for increasing the delivery volume of the hydraulic pump (2) is larger. 3. The pressure reducing device (56) according to claim 1 or 2, wherein the pressure reducing device (56) can be adjusted so that the decompression is approximately zero when the regulating volume flow for increasing the delivery volume of the hydraulic pump (2) is zero. Hydraulic control device characterized in that. 4. The load reducing device according to any one of claims 1 to 3, wherein the decompression device includes a proportional directional valve 56 having a load pressure connection and a low pressure connection, wherein the load pressure connection is capable of supplying a maximum load pressure. Hydraulic connection, characterized in that the low pressure connection can be connected to a pressure medium sink. 5. The hydraulic pressure according to claim 1, wherein a discharge line 40 is provided, through which the discharge connection of the pump regulator 32 can be connected to a pressure medium sink. 6. Control unit. 6. The proportional directional valve 56 according to claim 4 and 5, wherein the proportional directional valve 56 of the decompression device has a throttle position 56b, through which the load pressure connection is connected to the low pressure of the proportional directional valve 56. And a discharge pressure of the discharge line (40) in the direction of the throttle position (56b) to the valve body of the proportional valve (56). A throttle device (42; 274) is arranged in the discharge line (40), and the valve body of the proportional valve (56) of the decompression device is upstream of the throttle device (42; 274). Hydraulic control device, characterized in that the discharge pressure can be supplied in the direction of the throttle position (56b) through a control line (60) connected to the discharge line (40). 8. The pump regulator according to any one of claims 5 to 7, wherein the pump regulator comprises a proportional directional valve 32, wherein the valve comprises a delivery line connection of the pump regulator, a discharge connection of the pump regulator, a regulating connection, an inlet. A position 32a and a discharge position 32b, wherein the valve can be connected to the discharge line 4 via the discharge line connection, and the valve can be connected to a pressure medium sink through the discharge connection, Through the regulating connection the valve can be connected to the regulating device 36, through the inlet position the outgoing line 4 can be connected to the regulating device 36, and through the outlet position the regulating device (36) can be connected to the pressure medium sink. 9. The valve body 33 of the proportional directional valve 32 of the pump regulator can be supplied with a maximum load pressure and a spring equivalent of the regulating spring 32c in the direction of the discharge position 32b. Hydraulic pressure control device, characterized in that the discharge pressure can be supplied in the direction of the inflow position (32a). 10. A throttle device (170) is arranged in the control line (60) or in parallel with the throttle device (170) and the throttle device in the control line and the discharge pressure. Hydraulic control device, characterized in that the check valve 172 is opened by the arrangement. The throttle device according to any one of claims 7 to 10, wherein the throttle device disposed in the discharge line 40 is a directional valve 274, the directional valve being spring prestressed throttle switching position 276 and actuating. Hydraulic control device characterized in that it comprises a possible perfusion switching position (278). 12. A hydraulically operable hydraulic consumer 406, a control valve 408 and an operation unit 420 are provided, through which the hydraulic consumer receives the delivery line of the hydraulic pump 2 (12). 4), the operation unit is connected to the control valve 408 for switching of the first working position 408a via a first control signal line 422, and the first control signal line 422 ) Is connected to the directional valve 274 of the throttle device of the discharge line 40, so that the perfusion switching position 278 of the directional valve 274 is switched by the first control signal line 422. Hydraulic control device, characterized in that. 13. The control unit 420 of claim 12, wherein the operation unit 420 is connected to the control valve 408 for switching of the second working position 408b via a second control signal line 424, and the second control signal line 424 is connected to the directional valve 274 of the throttle device of the discharge line 40, so that the perfusion switching position 278 of the directional valve 274 is connected to the second control signal line 424. Hydraulic control device which can be switched by. 14. A measuring opening according to any one of the preceding claims, wherein one measuring opening is assigned to each hydraulic consumer in the delivery line of the hydraulic pump, and one individual pressure retention valve is respectively upstream of the measuring opening. The individual pressure holding valve is supplied with the load pressure of the hydraulic consumer assigned in the opening direction, and the pressure between the individual pressure holding valve and the measuring opening in the closing direction is supplied, or the pressure of the hydraulic pump 2 One measuring opening 66a, 66b; 266a, 266b, 366a, 366b, 466a, 466b is assigned to each hydraulic consumer 6; 206, 306, 406 in the delivery line 4, Downstream, each individual pressure retention valve 62; 262; 362; 462 is assigned, and each individual pressure retention valve 62; 262; 362; 462 is assigned the hydraulic consumer (s) 6 in the closing direction; The maximum load pressure of 206, 306, 406 is supplied, Hydraulic control, characterized in that the pressure is supplied between the measuring openings 66a, 66b; 266a, 266b, 366a, 366b, 466a, 466b and the individual pressure retention valves 62; 262; 362; 462 in the open direction. Device. 15. A hydraulic valve block for the control device (1; 101; 201) according to any one of claims 1 to 14, wherein the delivery pressure of the adjustable hydraulic pump (2) and one or more hydraulic consumers (6; 206) , A pump regulator 32 capable of regulating the regulating volume flow of the regulating device 36 of the hydraulic pump 2 in accordance with the maximum load pressure of 306, 406 and a pressure reducing device 56 for the maximum load pressure. In the hydraulic valve block,
The pressure reducing device (56) is a hydraulic valve block, characterized in that can be adjusted according to the control volume flow.

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