DE10354022A1 - Hydraulic dual-circuit system e.g. for crawler-track appliances, has pressure device supplied via summation valve arrangement over summation line downstream from orifice plate and pressure maintaining valve - Google Patents

Abstract

A hydraulic dual-circuit system for controlling consumer loads of a mobile appliance, in which each hydraulic circuit (2,4) is provided with an adjustment pump (6,7) depending on the highest load pressure and via which the associated load can be supplied with pressure and in which the two circuits (2,4) are interconnected via a summation valve arrangement (12), which is used to feed the pressure from one of the connected circuits via a summation line (24) downstream from the orifice plate (14) and from the pressure maintaining valve (16) of the summed consumer load.

Description

The invention relates to a hydraulic Dual circuit system for controlling consumers of a mobile device, in particular of a caterpillar device according to the generic term of claims 1 and 13.

In the US 6,170,261 B1 discloses a hydraulic two-circuit system of a mobile device, for example a chain or caterpillar device. In such caterpillar devices, the undercarriage has two caterpillars, each of which can be controlled separately from one another via one of the hydraulic circuits. To the two hydraulic circuits of the chain device, a slewing gear and aggregates of the equipment, such as the boom, the stick and the bucket, are also connected. Each of the two hydraulic circuits is supplied with pressure medium by a variable displacement pump, which is controlled as a function of the highest load pressure of the consumers in the respective assigned circuit. However, other applications, such as wheel excavators or cranes, are also conceivable for hydraulic dual-circuit systems.

To avoid a pressure medium shortage, it is possible to add both hydraulic circuits. At the in the US 6,170,261 B1 disclosed solution, this summation of the two hydraulic circuits takes place via a summing valve arrangement, via which the pressure lines connected to the two pumps and the load pressure reporting lines of the two circuits are summed. The summation valve arrangement is controlled as a function of the pressure medium supply to the additional consumer. In addition, the operator can intervene manually and add up the two circles.

In the post-published application DE 102 52 241 the applicant becomes one against the US 6,160,261 B1 Improved solution described, in which the summing valve arrangement is designed such that when the circuits are summed, a higher load pressure with a low pressure medium requirement in one of the circuits, not in the other circuit with a lower load pressure, is reported.

The disadvantage of these solutions is however, that the upstream of the LUDV systems to the consumers Proportional directional control valves with orifice plate and downstream pressure compensator must be designed for the volume flow which is the sum of in both districts to the maximum assigned to the assigned consumer can. This means, in the case of dual-circuit operation of the system, these are in the respective Proportional directional control valves arranged in the main axes, in particular their oversize orifice plates.

Another disadvantage is that with the known solutions very early is switched to a single-circuit system, since the summing valve arrangement Circles already summed up when more pressure medium is requested, than can be delivered by the pump.

In contrast, the invention is the Task to create a two-circuit system in which the for a load pressure independent control of the required orifices to be summed in optimal Are adapted to the dual-circuit operating state, and in which premature summation can be prevented.

This task is carried out by a two-circuit system solved with the features of claim 1 or 13.

According to the invention, the summation of the Pressure medium flows not how in the prior art described at the beginning - in front of the orifice plate of the Consumer assigned main axis, but only after this orifice and a pressure compensator, so that this only depends on the pump volume of the assigned circle must be adjusted. Because the summation thus only takes place after the metering orifice of the summed consumer, everyone can Measuring orifices of the summed main axes on the pump quantity of the respective Pump can be matched. This measure makes controllability greatly improved because of the overlay of several consumers the degree of undersaturation (Δp) between pump pressure and Load pressure does not drop too much. When the control pressure is reduced, the speed changes of individual consumers with a higher gain, so that of one Encoder device - for example a joystick - given Control signals can be implemented faster and more precisely.

The early switch to one Single circle leaves prevent themselves further by the actuating the summing valve arrangement Control signal selected in this way is that there is only a summation when the consumer in the dual circuit system its consumer valve axis has already been actuated, for example accelerated is.

In a particularly preferred embodiment becomes a proportional directional control valve in the main axis assigned to each consumer used with an orifice plate and a directional part, the Orifice plate downstream of an LUDV pressure compensator is. By this measure can be one load pressure independent Volume flow to the consumer maintained.

In a particularly preferred exemplary embodiment, the summing valve arrangement has a summing proportional valve which forms a summing measuring orifice, which is followed by a summing pressure compensator. The control of this summation proportional valve can be electrical, mechanical or hydraulically. With a suitable setting of the control signals, the control of the summation proportional valve can thus control the connection of the dual-circuit system to a single-circuit system in such a way that two circuits are operated in the operating range for as long as possible, so that the controllability of the hydraulic consumers and the energy balance are optimized.

With hydraulic control of the proportional valve, the control pressure can be dependent from the actuation an encoder device, for example, a pilot control unit to the summing proportional valve be created.

According to an advantageous development of the invention, the summing valve arrangement has an LS signaling valve via which when summing the respective LS signal on the LUDV pressure compensator the summing axis is guided. Should the highest load pressure be lower in the receiving circle than in the giving circle Circle, the pump pressure in the receiving circle is not raised. Conversely, the pump pressure in the quantity dispensing circuit is raised, if the receiving circuit has a higher load pressure than the releasing one Circle.

The summing valve arrangement can A control valve can also be assigned, via which the pressure of the pumps leading and leading the load pressure Lines are interconnectable. The control of this control valve takes place for example via a control pressure, which is based on one specified by the operator manual control signal is given. That is, by means of this control valve let yourself the dual-circuit system independently from under-saturation switch to a one-circuit system in the circles. For example then be required when the crawler track is overlapping is controlled with other consumers.

The function of the control valve and of the LS signaling valve can also be integrated in the summation proportional valve. at a preferred variant is this with an additional Switching position executed, in which the two lines carrying the pump pressure of the two Circles are connected. This can be achieved, for example, by that a valve spool of the summing proportional valve in its basic position (locking position) prestressing control spring arrangement so executed is that the control spring preload can be reduced on one side and the valve spool then reduced due to the one-sided personnel is shifted into said switch position.

To change this spring preload can a control spring of the summing proportional valve hydraulically of a control pressure, a control pressure leading control line by means of an override valve is connectable to the tank so that this control pressure is reduced and the bias of the control spring is reduced accordingly.

When adding up the two circles and the parallel control of several consumers, the system can in undersaturation work so that no load pressure-independent control of the respective consumer guaranteed is. To mitigate these effects, you can use the summation points from usual load pressure-low consumers nozzles, whereby for the fed from the other circle Quantity rather the desired Distribution of the fed Quantity between low-pressure and high-pressure consumers can be obtained.

According to the invention, it may be sufficient if the above-described summation only in one, from the proportional valve the pressure valve flow direction given the consumer valve axis done while no summation is provided in the opposite direction. It will particularly preferred if the pressure medium flow from the connected circuit in a line section between a load holding valve of the consumer valve axis and a directional part of the proportional valve opens.

Other advantageous further training the invention is the subject of other dependent claims.

Below are preferred embodiments the invention with reference to schematic drawings. It demonstrate:

1 a schematic representation of the basic functions of the dual-circuit system according to the invention;

2 a circuit diagram of a dual-circuit system according to the invention for a caterpillar device;

3 an enlarged view of a summing valve assembly 2 .

4 . 4a a summing valve arrangement of a further exemplary embodiment,

5 a third embodiment in which the LS pressures of both circles are always the same when summing, and

6a . 6b two alternatives of a fourth embodiment.

1 shows a basic diagram of an excavator control system as a two-circuit system with two hydraulic circuits 2 . 4 is constructed. Consumers can be identified via the two circles 8th . 10 of the excavator, such as for example driving the drives of a chassis with two caterpillars or the equipment of the excavator, such as for example a slewing gear, a stick, a bucket or a boom. The pressure supply of the two circles 2 . 4 takes place via a variable pump 6 . 7 , which are preferably controlled as a function of the maximum load pressure in the respective circuit.

is controlled by the consumer 8th more pressure medium requested than the assigned one variable 6 can deliver, so will the consumer 8th operated with undersaturation. A summation valve arrangement is to avoid such undersaturation 12 provided, via which a predetermined amount of pressure medium from the variable displacement pump 7 to the consumer 8th can be supplied.

In such excavator controls, the load is supplied to the consumers independently of the load pressure 8th . 10 , ..., with an adjustable orifice in each consumer valve axis 14 and one of these downstream pressure compensators 16 are arranged. This is in the opening direction from the pressure downstream of the orifice 14 and in the closing direction from the highest load pressure in the respective circuit 2 . 4 applied. This highest load pressure of every circuit 2 . 4 is in LS lines 18 . 20 on. The pressure compensator piston adjusts itself to a control position in which the pressure drop across the orifice plate 14 is kept constant regardless of load pressure. There is a load holding valve between the pressure compensator and the consumer 21 arranged. Such LS controls are well known, so that a further description of the functioning of the valve axis can be dispensed with. In particular, it is known that the highest load pressure is due to an additional control edge on the pressure compensators 16 is selected (e.g. US 5,305,789 ).

From a pump line carrying the pump pressure 22 branches a summing line 24 from that to the summing valve arrangement 12 leads. This has a total measuring aperture 26 who has a LUDV totalizing pressure compensator 28 is connected downstream. This becomes like the pressure compensators 16 the consumer valve axes in the opening direction from the pressure downstream of the orifice 26 and acted upon in the closing direction by the load pressure in the circuit 4 is applied. This load pressure is in the present case via the LS line 18 to the pressure compensator 28 reported. Even the pressure compensator 28 is a load holding valve 21 downstream.

The summing line 24 flows downstream of the pressure compensator 16 , of the load holding valve 21 and the consumer 8th assigned consumer valve axis in the consumer 8th leading work management 30 on. This means that the summation takes place after the orifice plate 14 , the pressure compensator 16 and the load holding valve 21 , so that their cross sections are only at the maximum, by the pump 6 delivered pressure medium volume flow are to be adjusted.

The summing valve arrangement 12 also has an LS signaling valve 32 , The LS signaling valve is locked in its spring-loaded basic position 32 the connection of the LS line 18 to the pressure compensator 28 from. By switching to the open position, the LS line 18 with the pressure compensator 28 connected. The changeover of the LS signaling valve 32 can, for example, depending on the control of the variable orifice 14 respectively. In the embodiment described above, it is only provided that pressure medium from the circle 4 in the circle 2 is fed. With such a one-sided supply, the LS signaling valve 32 per se and one control side of the pressure compensator 28 continuously with the LS line 18 be connected. Of course, by a suitable design of the summing valve arrangement 12 also a summation in the opposite direction, so that pressure medium from the circle 2 in the circle 4 is fed. Because an LS signaling valve is then necessary, this is also in 1 located.

Such an embodiment is based on the 2 and 3 explained.

In 2 is a part of a circuit diagram of a two-circuit control of an excavator with caterpillar drive shown. The dual circuit control has two circuits 2 . 4 using a summing valve arrangement 12 are interconnectable. Each of the circles 2 . 4 supplied some consumers, the circle 2 for example, the left caterpillar, the spoon and the boom are supplied while the circle 4 the right caterpillar, the stick, the slewing gear (not shown) and an optional consumer supplied with pressure medium. Every circle 2 . 4 is a variable displacement pump 6 . 7 assigned, depending on the highest in the respective circle 2 . 4 applied load pressure is controlled. Each consumer (chassis, bucket, boom, stick, slewing gear, option) is assigned a consumer valve axis, which is a proportionally adjustable directional valve 34 contains a speed component (LUDV orifice plate 14 ) and a directional part are formed. Downstream of the speed section (LUDV orifice plate 14 ) is the LUDV pressure compensator 16 provided that, as in the previously described embodiment, in the opening direction from the pressure downstream of the orifice of the proportional valve 34 and is acted upon by the highest load pressure in this circuit in the closing direction. The consumer valve axes assigned to the other consumers have a similar structure.

The summing axis of the summing valve assembly 12 has a summation proportional valve 36 which is the total measuring aperture 26 formed. Downstream of the summation proportional valve 36 is the totalizer 28 provided over which the pressure drop across the summation orifice 26 can be kept constant regardless of load pressure.

In this embodiment, the summing valve arrangement 12 also with an LS signaling valve 32 trained through which the LS line 18 or the LS line 20 on the pressure compensator 28 can be switched.

In special operating conditions, for example when the excavator is moving and one or more other consumers are actuated, it is advantageous if the dual-circuit system is switched manually to a single-circuit system in order to provide an adequate and uniform supply of pressure medium to the undercarriage and thus straight-ahead driving währleisten. This switching over to a single-circuit system can be carried out in accordance with the exemplary embodiment 2 via a control valve 38 take place, the pump lines carrying the pump pressure in its spring-loaded basic position 40 . 42 of the circles 2 . 4 as well as the two LS lines 18 . 20 connects with each other. The control valve 38 can be switched to its open position by means of a control pressure, this control pressure being tapped as a function of the control signals generated by the operator.

At the in 2 solution shown is the summation proportional valve 36 the summing axis is hydraulically controlled. The excavator has a large number of pilot devices in its driver's cab, whereby in 2 exemplary hand-operated pilot control devices 44 . 46 for actuating the arm and the slewing gear (pilot control unit 44 ) and the boom and the bucket (pilot control unit 46 ) are provided. The travel drive is controlled via two foot-operated pilot devices 48 . 50 being the pilot control unit 48 the left caterpillar and the pilot control unit 50 is assigned to the right caterpillar.

The pilot control units 44 . 46 . 48 . 50 work on the basis of directly controlled pressure reducing valves. With regard to the function of these control units, reference is made to the literature, for example to the Bosch Rexroth data sheet RE 64 552.

By deflecting a control lever of the pilot devices, a control pressure is emitted corresponding to the deflection, which is used to control the assigned consumers. At the in 2 The embodiment shown is that of the pilot control device 44 Control pressure delivered via a pilot line to control the stick 52 tapped and to a control side of the summation proportional valve 36 guided. The highest one from the pilot control unit 46 Control pressures delivered to actuate the boom or the bucket are transferred via a shuttle valve and another pilot line 54 tapped and to the other control surface of the summation proportional valve 36 guided.

Via a shuttle valve arrangement 56 becomes the highest of the control units 44 . 46 delivered control pressure tapped and via a control channel 60 and a switching valve 62 to a shuttle valve 64 led, at the other input a comparatively high, manually preselected control pressure can be applied. The higher of these two pressures then becomes a control surface of the control valve which is effective in the opening direction 38 guided.

The switching valve 62 connects the control channel in its basic position 60 with the tank so that the control valve 38 with unactuated pilot control units 48 . 50 only by the control pressure applied from the outside - for example, by switching a switch "single-circuit system" in its two circles 2 . 4 connecting switching position can be switched. The actuation of the switching valve 62 is carried out using the highest of the two foot-operated control units 48 . 50 emitted control pressure, via a shuttle valve arrangement 58 is tapped. Ie, if the two travel drives via the control units 48 . 50 can be controlled and at the same time the equipment is actuated, so the switching valve 62 switched to its open position, in the highest of the control unit 44 . 46 delivered control pressure via the control channel 60 and the shuttle valve 64 to the control valve 38 is performed so that this is independent of that on the summation proportional valve 36 control pressure difference to connect the two circuits 2 . 4 can be switched. This switchover can take place in the above-described operating state or manually by giving in the required control pressure from the outside.

Further details of the summation axis and the consumer valve axes are shown in the enlarged view in 3 explained.

The total proportional valve 36 has two pressure connections P1, P2, which are connected to the pump lines 40 respectively. 42 of the circles 2 . 4 are connected. Two summing connections S1, S2 are provided between the two pressure connections P1, P2, which are connected to the summing line 24 of the circle 2 and a summing line 66 of the circle 4 are connected.

The total proportional valve 36 also has an output port P '' and a return port P '. The output port P '' is with the input port P and the return port P 'is with the output port A of the totalizer 28 connected. The pressure in a channel between the connections P '' and P is tapped via a control line and to one in the opening direction of the summing pressure compensator 28 effective control surface. The total pressure compensator 28 is biased in its closing direction by an often existing, but not absolutely necessary, weak spring and by the load pressure. This load pressure is via the LS signaling valve 32 tapped, which is designed as a proportionally adjustable directional valve. The LS signaling valve 32 has two input connections LS1 and LS2 and one output connection X. The two input connections LS1, LS2 are with the LS line 20 of the circle 2 or the LS line 18 of the circle 4 connected. The output connection X is via a control channel with a connection LS of the summing pressure compensator 28 and further connected to the control surface of this pressure compensator which is effective in the closing direction. The control of the LS signaling valve 32 is done by tapping on the pilot lines 52 . 54 applied control pressure difference. That is, the LS signaling valve 32 with the same control pressure difference as the valve spool of the summing proportional valve 36 applied.

As already mentioned above, the proportional valve 34 the orifice plate 14 as well as a directional part 72 educated. The proportional valve 34 has a pressure port P and a Output port P ', that with the input port P of the pressure compensator 16 connected is. The pressure at port P 'becomes a control surface of the pressure compensator that is effective in the opening direction via a control line 16 guided. The pressure compensator is in the opposite direction, ie in the closing direction 16 by a spring and by the one in the LS line 20 applied load pressure. The pressure compensator 16 also has an output connection A and a control connection LS with the LS line 20 connected is. Output port A of the pressure compensator 16 is connected to two ports P '' and P '''via a branching pressure channel. A tank connection T of the proportional valve 14 is with one for both circles 2 . 4 common tank channel 74 connected. The control of the proportional valve 34 takes place via control pressures, which via control connections a5, b5 to the control surfaces of the proportional valve 34 be performed. In the basic position shown, the connections A, B, P ', P''are connected to the tank connection T, the connections P''', P are shut off.

How 3 is still removable, is the summing line 24 via a summing channel 68 and a check valve 70 which is also the function of the pressure compensator 28 downstream load holding valve 21 out

1 met with the branching part of the connecting channel 76 connected. This branches into two subchannels 80 . 78 on, each with a load holding valve 82 respectively. 84 is arranged. The summing channel 68 flows into the branch channel 80 between the load holding valve 82 and the assigned port P ''.

To control a consumer, eg the boom of an excavator, a higher control pressure is applied to port a5 than to port b5, so that the valve spool of the proportional valve 84 as shown in 3 is moved upwards. As a result of this displacement, the connections P and P 'are connected to one another and a corresponding opening of the measuring orifice 14 set. The pressure medium then flows through connection P 'to connection P of the pressure compensator and acts on it in the opening direction. The pressure compensator 16 adjusts itself to a control position in which the pressure drop across the orifice 14 can be kept constant regardless of load pressure. This means that the valve slide of the pressure compensator is in this control position 16 in the representation according to 3 pushed upwards, so that the connection between the ports P and A of the pressure compensator is opened. The pressure medium then flows over the connecting channel 76 and the branch channel 80 as well as the load holding valve 82 to connection P '' and from there via working connection A to the boom. The returning pressure medium is via the working connection B, the tank connection T and the tank channel 74 returned to the tank. In the case of boom sinks, a higher control pressure is applied to control port b5, so that the valve spool is shown in the illustration 3 is shifted downwards and the direction of movement of the boom is changed accordingly.

The basic function of an LUDV consumer valve axis is known, so that further explanations are unnecessary. The other consumer valve axes are designed accordingly, with the in 2 illustrated embodiment in a circle 2 the consumer valve axes of the bucket and the boom as well as in a circle 4 the consumer valve axis of the stem with the summing line 24 respectively. 66 connected is. The consumer valve axes are not in both directions of action with the summing lines 24 . 66 connected, but only in the direction in which the greater pressure medium is required, for example in the case of the boom in the direction of lifting. In general, in the case of consumers actuated by hydraulic cylinders, summation is preferably carried out only for the pressure medium flow leading to the cylinder space.

Now, for example, the boom of the excavator by actuating the control unit 46 is controlled by the higher control pressure in the pilot line 54 the summation proportional valve 36 in the positions marked with (b) and the total measuring aperture 26 open. The one with the pump line 42 of the circle 4 connected input port P2 of the summation proportional valve 36 is then over the orifice plate 26 connected to the output port P '', which in turn is connected to the input port P of the totalizer 28 connected is. The pressure downstream of the metering orifice 26 acts on the pressure compensating piston in the opening direction so that it is moved into a control position in which the input port P is connected to the output port A. The pressure medium then flows from this output port A via port P 'and the directional part of the summing proportional valve 36 to the summing connection S1, the one with the summing line 24 of the circle 2 is connected so that the consumer valve axis to be summed, ie in the present case the boom in a circle 2 additionally with pressure medium from the circle 4 is supplied. When the boom is actuated, the higher control pressure in the pilot line 54 the piston of the LS signaling valve 32 in the representation according to 3 shifted to the right so that the LS pressure of the circle 4 via the LS signaling valve 32 to the effective control surface of the totalizing pressure compensator in the closing direction 28 to be led.

When adding up a consumer of the district 4 becomes the slide of the totalizing proportional valve 36 shifted to the positions marked with (a) - the summation takes place in the circle according to the above-described way to the axis to be summed 4 ,

In the case where the pressure is downstream of the metering orifice 26 is greater than the load pressure in the LS line 18 respectively. 20 becomes the pressure compensator piston of the summing pressure compensator 28 Move to the control position marked with b) in which this higher pressure in the LS line 18 respectively. 20 is fed in (connections P and LS of the totalizing pressure compensator 28 are connected to each other and the latter in turn to port X of the LS signaling valve 32 ).

In general, the following can be said:
If the load pressure of the consumer in a first circuit, to which the quantity from the second circuit is to be supplied, that is to say the summed consumer, is higher than the highest load pressure of the second circuit, the summation pressure compensator does so 28 fully open and reports the higher load pressure of the summed consumer in the LS line of the second circuit, so that its pump pressure goes up. So summation is possible. The pump pressure only rises to the extent required by the load pressure of the total consumer. If at the same time another consumer that cannot be totalized and whose load pressure is higher than the load pressure of the totalized consumer is actuated in the first circuit, the higher load pressure is in the LS line of the first circuit, but not in that of the second Circuit and therefore has no influence on the pump pressure of the second circuit. Conversely, if the load pressure of the summed consumer in the first circuit is lower than the highest load pressure in the second circuit, the pressure compensator is located 28 in control position and throttles the total current accordingly. The LS pressure in the LS line of the first circuit is determined solely by the load pressures of the actuated consumers of the first circuit and does not go to the possibly higher level of the LS pressure of the second circuit. Unnecessary energy losses are avoided.

By suitable control of the summing axis 12 the summation can be carried out out of phase with the respective consumer valve axis. Such a phase shift can be set, for example, by adjusting the control range of the summing axis to a range shifted upwards between, for example, 17 to 24 bar by suitable selection of the bias of the control springs, while the control range of the consumer valve axes is, for example, 6 to 24 bar. This means that the summation takes place only when the control pressure difference at ports a4 and b4 is greater than 17 bar. Up to this threshold, ie with control pressure differences of less than 17 bar, the system works as a two-circuit system and can only be operated by operating the control valve 38 be reversed into a one-circuit system.

In the embodiment described above, the control valve 38 and the LS signaling valve 32 separate from the totalizing proportional valve 36 educated.

At the in 4 The exemplary embodiment shown are the functions of the LS signaling valve 32 and the control valve 38 into the summing proportional valve 36 integrated. The consumer valve axes are in the 4 Embodiment shown as executed in the above-described embodiment, that is, each axis is with an LUDV orifice 14 and a downstream LUDV pressure compensator 16 with some of the consumer valve axes (undercarriage, bucket, boom (circle 2 ) and stem can be summed.

The summing valve arrangement 12 again contains a proportional valve 136 with a total measuring aperture 26 and a downstream totalizing pressure compensator 28 , The valve spool of the totalizing proportional valve 136 is in turn via the control connections a4 and b4, the pilot line 52 . 54 and the control units 44 . 46 with a control pressure difference to initiate the summation. For the sake of clarity, the circuit symbol of the total proportional valve 136 in 4a shown enlarged. Accordingly, the summation proportional valve 136 the two pressure connections P1, P2, the summing connections S1, S2 and the connection P ″ arranged downstream of the measuring orifice and the return connection P ′ arranged upstream of the directional part. In addition, two LS connections LS1 and LS2 and a further control connection LS are provided. The two connections LS1 and LS2 are with the LS lines 20 respectively. 18 connected, the summing connections S1, S2 to the summing lines 24 . 66 and the two pump connections P1, P2 with the pump lines 40 . 42 connected.

As in the exemplary embodiment described above, the port P '' leads to the input port P of the summing pressure compensator 28 whose output A is connected to the return port P 'via a connecting channel. The further LS connection LS of the summation proportional valve 136 is with the LS connection LS of the summing pressure compensator 28 connected, the control pressure applied to the connection LS acting together with a weak spring in the closing direction on the pressure compensating piston. The downstream of the orifice 26 the prevailing pressure is led via a further control line to a control surface of the pressure compensating piston which is effective in the opening direction.

The total proportional valve 136 is biased into its basic position (0) by a control spring arrangement. In this basic position, all connections are blocked. By applying a control pressure, the valve slide can be moved into the control positions marked with (a), (b), through which the opening of the measuring orifice 26 and the direction of the pressure medium flow is determined. In this respect, the function of the summation proportional valve corresponds 136 that of the in 2 embodiment described in more detail. In addition to these control positions, the totalizing valve has 136 a fourth switching position (c), in which the two connections P1 and P2 and LS1 and LS2 with each other connected and all other connections are blocked.

According to 4 becomes the valve slide of the summation proportional valve 136 via two control spring arrangements 86 . 88 biased. These control spring arrangements are pretensioned for setting the basic position, the pretensioning - as explained above - can be selected such that there is a phase shift between the consumer valve axes and the summing axis when the consumers and the summation axis are actuated. The total proportional valve 136 has a fourth position (c). Via a control channel 92 and an override valve 94 A piston is pressurized with a high control pressure of 30 bar, for example 90 held at a stop. The control spring arrangement is in this stop position 88 with its basic preload, in which the valve spool is in its basic position ( 0 ) is located. The control of the override valve 94 takes place via a shuttle valve 96 whose function is the shuttle valve 64 out 2 equivalent. Ie, the input connections of the shuttle valve 96 are on the control channel 60 (please refer 2 ) and connected to a control line leading to a control unit, not shown, via which a control pressure can be generated manually by the operator. The larger of these two control pressures (maximum, from the control units 47 . 46 . 50 48 output control pressure or manually specified control pressure) is via the shuttle valve 96 on the control surface of the override valve 94 placed so that it can be moved against the force of a return spring into its (a) marked switching position, in which the control channel 92 is connected to the tank T. The control line carrying the high control pressure 98 is in the switch position (a) of the override valve 94 with another control channel 100 connected who like in 4 shown below, to a shuttle valve 102 is led, whose other input connection with the pilot line 52 connected is. That is, the larger of the two in the further control channel 100 or the pilot line 52 control pressure is applied via the shuttle valve 102 led to connection a4 and acts on the control spool of the totalizing proportional valve 136 towards the fourth switching position (c).

When switching the override valve 94 the piston is in switch position (a) 90 relieved and moved to a rear stop and accordingly the bias of the control spring assembly 88 reduced. The control pressure in the control line 98 is by means of the override valve 94 in the further control channel 100 reported and to the shuttle valve 1a2 guided. Due to the relief of the control spring arrangement 88 ' and of the control pressure present at connection a4 (control pressure in 100 or control pressure in 52), the valve slide is then moved to the fourth switching position (c), in which the two pump connections P1, P2 and correspondingly also the pump lines 40 . 42 as well as LS1 and LS2 are connected to one another - the arrangement is then switched over to a single-circuit system and this mode is required, for example, when driving and simultaneously operating the equipment. Ie, through this switching position (c) the function of the control valve 38 out 2 integrated in the totalizing proportional valve.

The summation proportional valve is used to sum a consumer valve axis 136 move to one of the positions marked with (a) or (b). When summing, for example, the stem (see 2 ) assigned consumer valve axis is activated by actuating the pilot control unit 44 a comparatively high control pressure is applied to port a4 so that the valve spool is moved to one of the positions marked with (a). The axial displacement of the valve slide gives the opening of the orifice plate 26 via which the pump connection P1 and output connection P '' are connected to each other. The summing pressure compensator becomes the pressure downstream of the orifice plate 28 brought into a control position so that its input port P is connected to the output port A. The pressure medium flows via this output port A of the summing pressure compensator back to the return port P 'and from there via the summing port S2 into the summing line 66 and on to the consumer to be summed (stem). The pressure medium flow to be summed is fed in as in the 3 illustrated embodiment again via summing channels 68 that have a check valve 70 to the directional part of a proportional valve 34 leading branch channels 78 or 80 are connected, usually summing only taking place in the direction in which the increased pressure medium requirement is present.

In positions (a) of the summation proportional valve 136 Furthermore, the two connections LS1 and LS are connected to each other, so that on the pressure compensator 28 the LS pressure of the summing circle 2 is applied. In the event that the pressure is downstream of the orifice 26 is greater than the load pressure in the LS line 20 becomes the pressure compensator 28 move to their end position in which their LS connection is connected to connection P, so that this higher pressure than the new maximum load pressure in the LS line 20 is reported.

The sum of a consumer in a circle 2 takes place by applying the higher control pressure to port b4 in a corresponding manner, the summing proportional valve then being moved into the control positions marked with (b).

When controlling several consumers in a circuit 2 It can happen that the pump current supplied from the circuit 4 is no longer divided between the loads to be summed independently of the load pressure. For optimal control To ensure even the higher-load summed consumers, it is possible in the summing channel 68 of proportional valves 34 the usually lower load consumers nozzles 138 or other throttling devices upstream, so that a simpler oil distribution over the directional grooves in the proportional valve 34 can be achieved.

To better understand the Some operating states are explained in the valve arrangement.

It is assumed that the bias of the valve spool of the summing proportional valve 36 . 136 is selected so that its control range is approximately in the range between 17 and 24 bar, while the control range of the main axes is selected between 6 and 24 bar.

• 1.) When leveling quickly with stretched excavator equipment, the pilot control devices 44 and 46 for setting the stick-in and boom-lift functions so that the maximum control pressure is applied - ie, the orifices in the consumer valve axes are fully opened. Because in the two pilot lines 52 . 54 then approximately the same control pressure is applied, the summation axis remains in its central position. The two circles 2 . 4 are separated from each other, there is a two-circuit system so that there is no mutual interference between the individual consumers, which is particularly important when the spoon is used critically. As soon as both consumers (stick, boom) have picked up speed, the boom lifting setting must be continuously reduced to 0 due to the stick kinematics of the speed. That is, on the control surfaces of the summation proportional valve 36 . 136 then there is a control pressure difference resulting from the different setting of the pilot control units 44 . 46 results. From a control pressure difference of more than 17 bar, the summation then takes place, whereby the pressure medium released from the boom circuit (circuit 2 ) over the summation axis into the summation line 66 and from there to the handle, so that a maximum handle speed is guaranteed.
• 2.) In the event that the slewing gear is actuated and the boom lifting function is activated, two cases are conceivable: a) The totalizing axis is adjusted with the one on the pilot control unit 46 set control pressure, which is the totalizing proportional valve 36 control pressure difference ≥ 17 bar - the summing axis connects the circuit 4 with the circle 2 , so that the quantity of pressure medium not picked up by the rotating mechanism with priority is additionally downstream of the orifice plate 34 and the pressure compensator 16 the boom axis is fed. This takes place during the acceleration phase of the slewing gear. The LS line 18 is either via the LS signaling valve 32 of the embodiment according to the 2 and 3 or via the LS connections of the summation proportional valve 136 according to the example 4 to the pressure compensator 28 connected. b) In the event that no summation for the cantilever axis is desired, the control pressure signal of the slewing gear or another suitable control signal can be tapped via its own logic (not shown) and applied to connection a4 of the summation axis, so that initially no summation takes place and both circles for controlling the slewing gear and the boom can work independently of each other. Only when the difference between the two control pressures at ports a4 and b4 is greater than 17 bar are the two circuits connected via the summing axis. In other words, in the latter possibility, a control pressure signal is deliberately sent to the summing axis via the logic, which allows the summation only when the predetermined control pressure difference is exceeded.
• 3. In the case where only the two caterpillars are controlled, the two circles remain 2 . 4 even when the control pressures are very different, e.g. when cornering in difficult terrain, separately because of the pilot control units 48 . 50 to control the caterpillars, no control signal is emitted to the summation axis.
• 4. In the event that other consumers are also activated in addition to the travel drive, straight-ahead driving must still be guaranteed. In the embodiment according to 2 is over that of the pilot control units 48 . 50 the control valve to control the caterpillars 62 switched so that the control valve 38 through the over the pilot devices 44 . 46 generated control pressure via the line 60 or by switching an external control pressure to its open position, in which both circuits 2, 4 are connected to the single circuit.

In the embodiment according to 4 This connection to the single-circuit is made by the fact that the pilot control devices 44 . 46 emitted control pressure via the control channel 60 and the shuttle valve 96 the override valve 94 is switched so that the piston 90 relieved and the valve slide of the summation proportional valve 136 is moved into the fourth switching position (c), in which both circles 2 . 4 be summed up. As mentioned at the outset, the override valve can be switched 94 also by applying an external control signal.

The embodiment according to 5 differs from that after 2 and 3 only through a different design of the LS signaling valve 32 , During the LS signaling valve 32 after the 2 and 3 in a summation the two LS-lines 18 and 20 leaves the LS line separately and depending on the direction of summation 18 or the LS line 20 with one control side of the pressure compensator 28 connects, the LS signaling valve 32 to 5 in the case of a summation, a connection between the two LS lines 18 and 20 and between these two lines 18 . 20 and the one control side of the pressure compensator 28 ago. Thus, the two circles are at summation 2 and 4 always at the same pressure level as the highest load pressure of all in the two circles 2 . 4 actuated hydraulic consumer is determined. Since the pressure level in the quantity-absorbing circle is thus increased when the highest load pressure there is lower than in the quantity-releasing circle, the exemplary embodiment appears after 5 from the energy balance not as cheap as the embodiments according to the 2 to 4 ,

In the 6a and 6b Two alternatives for the load pressure message from one circuit to the other circuit are shown for an exemplary embodiment in which the selection of the highest load pressure is not provided with a pressure compensator equipped with an additional control edge, but for example via a shuttle valve chain or, as shown, via check valves 139 he follows. It is necessary to report the highest load pressure from the first circle receiving the quantity to the second circle delivering the quantity if the highest load pressure (= LS pressure) of the first circle is higher than the highest load pressure of the second circle. According to 6a is in the two switch positions of the LS signaling valve on the side 32 between the two LS lines 18 . 20 one check valve each 140 switched by the LS line 18 of the second circle to the LS line 20 locks the first circle. If the LS pressure in this first circuit is lower than in the second circuit, the pressure in the first circuit remains at the low level. If, on the other hand, the LS pressure in the first circuit is higher than in the second circuit, this higher LS pressure can be reported in the second circuit.

In the alternative after 6b are the functions "connecting one control side of the pressure compensator 28 with the LS line of the second circuit "and" reporting a higher LS pressure of the first circuit in the second circuit "on two valves 32 . 33 divided up. The LS signaling valve 32 is the same as that of the embodiment according to FIGS 2 and 3 , An LS switching valve 33 is also used with the LS signaling valve 32 controlled and switches one or the other check valve depending on the direction of summation 140 between the two LS lines 18 . 20 ,

With the two alternatives after the 6a and 6b the LS pressure of the first circuit is also reported to the second circuit if the load pressure of the totalized consumer or loads is lower, but the LS pressure of the first circuit is higher than the LS pressure of the second circuit. Should it be here as in the embodiments according to the 2 to 4 Only the comparison of the load pressures of the summed consumers with the LS pressure of the second circuit is important, so that the highest load pressure of the summed consumers should be able to be selected separately and independently of the LS lines in the lines leading to the variable displacement pumps 18 . 20 the 6a and 6b queue.

A hydraulic dual-circuit system is disclosed to control consumers of a mobile device, in particular a chain device, the two circles by means of a summing valve arrangement for selected Consumers can be summed. The pressure medium supply for consumers takes place via an LUDV orifice plate and an LUDV pressure compensator. The summing valve arrangement is designed such that the summed volume flow from the summed circle downstream the orifice plate is fed into the other circuit and / or that the summation is relatively late, i.e. out of phase with the summed consumer.

2

1. circle

4

Second circle

6

variable

7

variable

8th

consumer

10

consumer

12

 Summierventilanordnung

14

orifice

16

pressure compensator

18

LS line

20

LS line

21

Load-holding valve

22

pump line

24

summing

26

Summiermessblende

28

Summierdruckwaage

30

working line

32

LS-sensing valve

33

LS-through valve

34

proportional valve

36

Summierproportionalventil

38

control valve

40

pump line

42

pump line

44

 manually operated pilot control device

46

manually operated pilot control device

48

foot operated pilot control unit

50

foot operated pilot control unit

52

pilot line

54

pilot line

56

Changer valve assembly

58

Changer valve assembly

60

control channel

62

switching valve

66

summing

68

Summierkanal

70

check valve

72

direction part

74

tank channel

76

connecting channel

78

Zweigkanal

80

Zweigkanal

82

Load-holding valve

84

Load-holding valve

86

Control spring assembly

88

Control spring assembly

90

piston

92

control channel

94

About control valve

96

shuttle valve

98

control line

100

Another control channel

136

Summierproportionalventil

138

jet

139

check valve

140

check valve

Claims (14)

Hydraulic two-circuit system for controlling consumers of a mobile device, in particular a chain device, with each hydraulic circuit ( 2 . 4 ) a variable displacement pump controlled depending on the highest load pressure ( 6 . 7 ) is assigned, via which the assigned consumers can be supplied with pressure medium and the two circles ( 2 . 4 ) via a summing valve arrangement ( 12 ) can be connected to each other in such a way that the pump ( 6 . 7 ) of a circle ( 2 . 4 ) Pressure medium in the other circle ( 4 . 2 ) promotes, so that at least one in this circle ( 4 . 2 ) connected consumer of both pumps ( 6 . 7 ) can be supplied with pressure medium and the consumer is provided with an LUDV valve arrangement with an orifice plate ( 14 ) and pressure compensator ( 16 ) is assigned, characterized in that via the summing valve arrangement ( 12 ) the pressure medium from the one connected circuit ( 2 . 4 ) via a summing line ( 24 . 66 ) downstream of the orifice ( 14 ) and the pressure compensator ( 16 ) of the summed consumer is fed. Dual circuit system according to claim 1, wherein the summing line ( 24 . 66 ) downstream of the orifice plate ( 14 ) and upstream of a directional part of the orifice ( 14 ) forming proportional valve ( 34 ) flows into. Dual circuit system according to claim 1 or 2, wherein the summing valve arrangement ( 12 ) a totalizing proportional valve ( 36 ) with downstream totalizing pressure compensator ( 28 ) Has. Dual circuit system according to claim 3, wherein the control of the summation proportional valve ( 36 ) hydraulically by applying a control pressure. Dual circuit system according to claim 4, the control pressure depending on the actuation of a ballast ( 44 . 46 . 48 . 50 ) or depending on other logic to the summing proportional valve ( 36 ) is created. Dual circuit system according to one of the claims 3 to 5 , the summing valve arrangement ( 12 ) an LS signaling valve ( 32 ) over which a control side of the totalizing pressure compensator ( 28 ) with the highest load pressure of a circle ( 2 . 4 ) can be acted upon. Dual circuit system according to one of the claims 3 to 6 , the summing valve arrangement ( 12 ) except the total proportional valve ( 36 ) a control valve ( 38 ) via which lines depending on a control signal carry the pump pressure and the load pressure ( 40 . 42 ; 18 . 20 ) of the two circles ( 2 . 4 ) can be connected to each other. Dual circuit system according to claims 6 and 7, wherein the functions of the LS signaling valve ( 32 ) and / or the control valve ( 38 ) in the totalizing proportional valve ( 136 ) are integrated. Dual circuit system according to one of the claims 3 to 8th , wherein a main slide of the proportional valve assigned to the consumer ( 34 ) and the totalizing proportional valve ( 36 ) are pretensioned into a basic position by means of control springs, the pretensioning of the summation proportional valve ( 36 ) assigned control spring is greater than that of the proportional valve assigned to the consumer ( 34 ). Dual circuit system according to one of the preceding claims, wherein the feed for at least one summed consumer ( 8th . 10 ) via a throttle device ( 138 ) he follows. Dual circuit system according to claim 8, with an override valve ( 24 ), via which the totalizing proportional valve ( 136 ) can be acted upon with a control signal such that its valve slide can be moved into a predetermined end position (c) in which the two circles ( 2 . 4 ) are connected. Dual circuit system according to one of the claims 3 to 11 , where consumers are using load holding valves ( 82 . 84 ) are connected upstream and the summing line ( 24 . 66 ) between the load holding valve ( 82 . 84 ) and a directional part of the proportional valve ( 34 ) flows into. Hydraulic two-circuit system for controlling consumers of a mobile device, in particular a chain device, each hydrauli circle ( 2 . 4 ) a variable displacement pump controlled depending on the highest load pressure ( 6 . 7 ) is assigned, via which the assigned consumers can be supplied with pressure medium and the two circles ( 2 . 4 ) via a summing valve arrangement ( 12 ) can be connected to each other in such a way that the pump ( 6 . 7 ) of a circle ( 2 . 4 ) Pressure medium in the other circle ( 4 . 2 ) promotes, so that at least one in this circle ( 4 . 2 ) connected consumer of both pumps ( 6 . 7 ) can be supplied with pressure medium and the consumer is provided with an LUDV valve arrangement with an orifice plate ( 14 ) and pressure compensator ( 16 ) is assigned, characterized in that the summing valve arrangement ( 12 ) depending on the control unit ( 44 . 46 ; 50 . 48 ) to control the consumer generated control signals and can be controlled arbitrarily via a logic. Dual circuit system according to claim 13, wherein the summing valve arrangement ( 12 ) a totalizing aperture ( 26 ) and a total pressure compensator ( 28 ), with the total measuring aperture ( 26 ) to initiate the summation by means of a control pressure or a control pressure difference in an open position.