EP1565658A1

EP1565658A1 - Hydraulic dual circuit system

Info

Publication number: EP1565658A1
Application number: EP03782096A
Authority: EP
Inventors: Werner Herfs; Günter FERTIG
Original assignee: Bosch Rexroth AG
Current assignee: Bosch Rexroth AG
Priority date: 2002-11-29
Filing date: 2003-11-19
Publication date: 2005-08-24
Anticipated expiration: 2023-11-19
Also published as: AU2003289805A1; DE10354022A1; JP2006508311A; DE50309431D1; KR20050086826A; EP1565658B1; ATE389813T1; CN1314904C; WO2004051092A1; CN1711426A

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

description

Hydraulic two-circuit system

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

US Pat. No. 6,170,261 B1 discloses a hydraulic two-circuit system for 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 are also possible for hydraulic dual-circuit systems, e.g. Wheel excavators or cranes, conceivable.

To avoid a pressure medium shortage, it is possible to add both hydraulic circuits. In the solution disclosed in US Pat. No. 6,170,261 B1, this summation of the two hydraulic ones takes place

Circles via a summing valve arrangement, via which the pressure lines connected to the two pumps and the load pressure signaling lines of the two circuits are summed. The summing valve arrangement is controlled as a function of the pressure medium supply to additional consumers. In addition, the operator can intervene manually and add up the two circles.

The applicant's post-published application DE 102 52 241 describes an improved solution compared to US Pat. No. 6,160,261 B1, in which the summing valve arrangement is designed such that when the circles are summed up, a higher load pressure with low pressure medium requirement in one of the circles, not in the other circle is reported with lower load pressure.

A disadvantage of these solutions, however, is that the proportional directional control valves with metering orifices and downstream pressure compensators, which are upstream of the consumers in LUDV systems, must be designed for the volume flow that can be conveyed to the assigned consumer by the maximum of two circuits. This means that when the system is operated in two circuits, the proportional directional control valves arranged in the respective main axes, in particular their measuring orifices, are oversized.

Another disadvantage is that in the known

Solutions is switched to a single-circuit system very early on, since the summing valve arrangement already sums the circuits when more pressure medium is requested than can be supplied by the pump.

In contrast, the invention is based on the object of creating a two-circuit system in which the metering orifices required for triggering the consumers to be summed independently of the load pressure are optimally adapted to the two-circuit operating state, and in which premature summation can be prevented. This object is achieved by a two-circuit system with the features of patent claim 1 or 13.

According to the invention, the pressure medium flows are not summed - as in the prior art described at the beginning - in front of the orifice plate of the main axis assigned to the consumer, but only after this orifice plate and a pressure compensator, so that it is only adapted to the pump volume of the assigned circuit must become. Since the summation takes place only after the metering orifice of the summed consumer, all metering orifices of the summed main axes can be matched to the pump quantity of the respective pump. This measure greatly improves controllability because the degree of undersaturation (Δp) between pump pressure and load pressure does not drop too much when several consumers are superimposed. When the control pressure is reduced, the speed of the individual consumers changes with a higher amplification, so that the control signals specified by an encoder device, for example a joystick, are implemented more quickly and precisely.

The early switchover to a single circuit can be prevented further by selecting the control signal actuating the summing valve arrangement so that summation only occurs when the consumer in the dual-circuit system has already been activated, for example accelerated, via its consumer valve axis.

In a particularly preferred embodiment, a is assigned to the main axis assigned to each consumer

Proportional directional control valve with a metering orifice and a directional part used, the metering orifice using a LUDV

Pressure compensator is connected downstream. This measure leaves a load flow-independent volume flow to the consumer is 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. This summation proportional valve can be controlled electrically, mechanically or hydraulically. With a suitable setting of the control signals, the opening 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.

When the summation proportional valve is actuated hydraulically, the control pressure can be dependent on the actuation of a transmitter device, for example one

Pilot devices are applied to the summation proportional valve.

According to an advantageous further development of the invention, the summing valve arrangement has an LS signaling valve, via which the respective LS signal is fed to the LUDV pressure compensator of the summing axis during summation. If the highest load pressure in the quantity-receiving circuit is lower than in the quantity-dispensing circuit, the pump pressure in the receiving circuit is not increased.

Conversely, the pump pressure in the quantity-dispensing circuit is raised if the receiving circuit has a higher load pressure than the dispensing circuit.

A control valve can also be assigned to the summing valve arrangement, via which the pump pressure-carrying lines and the load pressure-carrying lines can be connected to one another. This control valve is activated, for example, via a control pressure which is emitted on the basis of a manual control signal specified by the operator. That is, this control valve enables the dual-circuit system to be switched to a single-circuit system regardless of undersaturation in the circuits. This can be necessary, for example, if the crawler track is controlled in a superposition with other consumers.

The function of the control valve and the LS signaling valve can also be integrated in the summation proportional valve. In a preferred variant, this is carried out with an additional switching position in which the two lines of the two circuits carrying the pump pressure are connected to one another. This can be achieved, for example, by designing the control spring arrangement that biases a valve slide of the summing proportional valve into its basic position (blocking position) in such a way that the control spring preload can be reduced on one side and the valve slide is then shifted into said switch position due to the reduced forces on one side.

To change this spring preload, a control spring of the summation proportional valve can be hydraulically preloaded by means of a control pressure, a control line carrying this control pressure being connectable to the tank by means of an override valve, so that this control pressure is reduced and the preload of the control spring is correspondingly reduced.

When adding up the two circuits and controlling several consumers in parallel, the system can Work under saturation so that no control of the respective consumer is guaranteed, regardless of load pressure. In order to alleviate these effects, nozzles can be connected upstream at the summing points of usually low-pressure consumers, so that the desired distribution of the supplied quantity between low-pressure and high-pressure consumers can be obtained for the quantity supplied from the other circuit.

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

Other advantageous developments of the invention are the subject of other dependent claims.

Preferred exemplary embodiments of the invention are explained in more detail below with the aid of schematic drawings. Show it:

Figure 1 is a schematic diagram of the basic functions of the dual-circuit system according to the invention; Figure 2 is a circuit diagram of an inventive

Dual circuit system for a caterpillar device;

FIG. 3 shows an enlarged illustration of a summing valve arrangement from FIG. 2,

4, 4a a summing valve arrangement of a further exemplary embodiment, Figure 5 shows a third embodiment in which the LS pressures of both circles are always the same when summing, and

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

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

If more pressure medium is requested than the assigned variable displacement pump by triggering the consumer 8

6 can deliver, the consumer 8 is operated with undersaturation. To avoid such undersaturation, a summing valve arrangement 12 is provided, via which a predeterminable amount of pressure medium can be supplied to the consumer 8 by the variable pump 7.

In the case of such excavator controls, the load 8, 10,... Is supplied independently of the load pressure, with an adjustable one in each consumer valve axis

Orifice plate 14 and a pressure compensator 16 arranged downstream of it. This is acted upon in the opening direction by the pressure downstream of the measuring orifice 14 and in the closing direction by the highest load pressure in the respective circuit 2, 4. This highest load pressure of each circuit 2, 4 is present in LS lines 18, 20. The Pressure balance piston sets itself in a control position in which the pressure drop across the measuring orifice 14 is kept constant regardless of the load pressure. A load holding valve 21 is arranged between the pressure compensator and the consumer. 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 selected by an additional control edge on the pressure compensators 16 (for example US 5,305,789).

A summing line 24 branches off from a pump line 22 carrying the pump pressure, which leads to the summing valve arrangement 12. This has a totalizing orifice 26, which is followed by an LUDV totalizing pressure compensator 28. Like the pressure compensators 16 of the consumer valve axes, this is acted upon in the opening direction by the pressure downstream of the measuring orifice 26 and in the closing direction by the load pressure which is present in the circuit 4.

In the present case, this load pressure is reported to the pressure compensator 28 via the LS line 18. The pressure compensator 28 is also followed by a load holding valve 21.

The summing line 24 opens downstream of the pressure compensator 16, the load holding valve 21 and the consumer valve axis assigned to the consumer 8 into the working line 30 leading to the consumer 8. That is, the summation takes place only after the orifice 14, the pressure compensator 16 and the load holding valve 21, so that their

Cross sections only have to be adapted to the maximum pressure medium volume flow supplied by the pump 6.

The summing valve arrangement 12 also has an LS signaling valve 32. In its spring-biased

Basic position, the LS signaling valve 32 blocks the connection the LS line 18 to the pressure compensator 28. By switching to the open position, the LS line 18 is connected to the pressure compensator 28. The LS signaling valve 32 can be switched over, for example, as a function of the control of the variable measuring orifice 14. In the exemplary embodiment described above, it is only provided that pressure medium is fed from circuit 4 into circuit 2. With such a one-sided supply, the LS signaling valve 32 itself can be omitted and the one control side of the pressure compensator 28 can be permanently connected to the LS line 18. Of course, by a suitable configuration of the summing valve arrangement 12, summation can also take place in the opposite direction, so that pressure medium is fed from the circuit 2 into the circuit 4. Because an LS signaling valve is then necessary, this is also shown in FIG. 1.

Such an embodiment is explained with reference to Figures 2 and 3.

FIG. 2 shows part of a circuit diagram of a two-circuit control system of an excavator with a caterpillar drive. The two-circuit control in turn has two circuits 2, 4, which can be connected to one another by means of a summing valve arrangement 12. Each of the circles 2, 4 supplies some consumers, the circle 2 for example supplying the left caterpillar, the bucket and the boom, while the circuit 4 supplies the right caterpillar, the stick, the slewing gear (not shown) and an optional consumer Pressure medium supplied. A variable displacement pump 6, 7 is assigned to each circuit 2, 4 and is controlled as a function of the highest load pressure present in the respective circuit 2, 4. Each of the consumers (undercarriage, bucket, boom, stick, slewing gear, option) is assigned a consumer valve axis, which is proportional includes adjustable directional valve 34, through which a speed part (LUDV measuring orifice 14) and a directional part are formed. Downstream of the speed section (LUDV measuring orifice 14), the LUDV pressure compensator 16 is provided, which, as in the previously described exemplary embodiment, is acted upon in the opening direction by the pressure downstream of the measuring orifice of the proportional valve 34 and in the closing direction by the highest load pressure in this circuit. The consumer valve axes assigned to the other consumers have a similar structure.

The summing axis of the summing valve arrangement 12 has a summing proportional valve 36, which forms the summing measuring orifice 26. Downstream of the summation proportional valve 36, the summation pressure compensator 28 is provided, by means of which the pressure drop across the summation measuring orifice 26 can be kept constant independently of the load pressure.

In this exemplary embodiment, the summing valve arrangement 12 is likewise designed with an LS signaling valve 32, via which the LS line 18 or the LS line 20 can be switched to the pressure compensator 28.

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 ensure an adequate and uniform supply of pressure medium to the chassis and thus straight-ahead driving. This switching to a single-circuit system can take place in the exemplary embodiment according to FIG. 2 via a control valve 38 which, in its spring-preloaded basic position, the pump lines 40, 42 of the circuits 2, 4 carrying the pump pressure and the two LS lines 18, 20 connects together. The control valve 38 can be switched into its passage division by means of a control pressure, this control pressure being tapped as a function of the control signals generated by the operator.

In the solution shown in FIG. 2, the summing proportional valve 36 of the summing axis is controlled hydraulically. The excavator has a large number of pilot control devices in its driver's cab, with example pilot operated control devices 44, 46 being provided in FIG. 2 for actuating the arm and the slewing gear (pilot control device 44) and the boom and bucket (pilot control device 46). The travel drive is controlled via two foot-operated pilot devices 48, 50, the pilot device 48 being associated with the left caterpillar and the pilot device 50 with the right caterpillar.

The pilot control devices 44, 46, 48, 50 operate 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. In the exemplary embodiment shown in FIG. 2, the one supplied by the pilot control device 44 for controlling the handle

Control pressure tapped via a pilot line 52 and led to a control side of the summing proportional valve 36. The highest of the control pressures emitted by the pilot device 46 for actuating the boom or the bucket is via a shuttle valve and a tapped further pilot line 54 and led to the other control surface of the summation proportional valve 36.

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

In its basic position, the switching valve 62 connects the control channel 60 to the tank, so that the control valve 38, when the pilot control devices 48, 50 are not actuated, only by the control pressure applied from the outside - for example, by switching a "single-circuit system" switch into its connecting the two circuits 2, 4 Switch position can be switched. The switching valve 62 is actuated by means of the highest control pressure which is output by the two foot-operated control units 48, 50 and which is tapped via a shuttle valve arrangement 58. That is, if the two travel drives are controlled via the control units 48, 50 and the equipment is also operated at the same time, the switching valve 62 is switched to its open position in which the highest control pressure emitted by the control unit 44, 46 via the control channel 60 and that Changeover valve ^■ 64 is guided to the control valve 38, so that it can be switched over independently of the control pressure difference applied to the summing proportional valve 36 to connect the two circuits 2, 4. 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 summing axis and the consumer valve axes are explained on the basis of the enlarged illustration in FIG. 3.

The summation proportional valve 36 has two pressure connections Pl, P2, which are connected to the pump lines 40 and 42 of the circuits 2, 4. Between the two pressure connections Pl, P2 two summing connections S1, S2 are provided, which are connected to the summing line 24 of the circuit 2 and a summing line 66 of the circuit 4.

The summation proportional valve 36 also has an output connection P ″ and a return connection P ′. The output port P ¹ 'is connected to the input port P and the return port P' is connected to the output port A of the accumulator 28. The pressure in a channel between the connections P ″ and P is tapped via a control line and led to a control surface which is effective in the opening direction of the summing pressure compensator 28. The summing pressure compensator 28 is biased in its closing direction by a weak spring that is often present, but not absolutely necessary, and by the load pressure. This load pressure is tapped via the LS signaling valve 32, which is designed as a proportionally adjustable directional valve. The LS signaling valve 32 has two input connections LSI and LS2 and an output connection X. The two input connections LSI, LS2 are connected to the LS line 20 of the circuit 2 and the LS line 18 of the circuit 4. The output connection X is connected via a control channel to a connection LS of the summing pressure compensator 28 and further to the control surface of this pressure compensator which is effective in the closing direction. The LS signaling valve 32 is activated by tapping on the Pilot lines 52, 54 are present

Control pressure difference. In other words, the LS signaling valve 32 is operated with the same control pressure difference as that

Valve slide of the summation proportional valve 36 acted upon.

As already mentioned above, the measuring orifice 14 and a directional part 72 are formed by the proportional valve 34. The proportional valve 34 has a pressure port P and an output port P ', which is connected to the input port P of the pressure compensator 16. The pressure present at the port P 'is led via a control line to a control surface of the pressure compensator 16 which is effective in the opening direction. In the opposite direction, ie in the closing direction, the pressure compensator 16 is acted upon by a spring and by the load pressure present in the LS line 20. The pressure compensator 16 also has an output connection A and a control connection LS which is connected to the LS line 20. The output connection A of the pressure compensator 16 is connected to two connections P ' ¹ and P ¹ ''via a branching pressure channel. A tank connection T of the proportional valve 14 is connected to a tank channel 74 common to both circuits 2, 4. The proportional valve 34 is controlled via control pressures which are guided to the control surfaces of the proportional valve 34 via control connections a5, b5. In the basic position shown, the connections A, B, P ', P' ^{1 are} connected to the tank connection T, the connections P ''', P are shut off.

As can also be seen in FIG. 3, 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 Figure 1 fulfilled, connected to the branching part of the connecting channel 76. This branches into two subchannels 80, 78, in each of which a load holding valve 82 or 84 is arranged. The summing channel 68 opens into the branch channel 80 between the load holding valve 82 and the associated port P ″.

To control a consumer, for example the boom of an excavator, a higher control pressure is applied to the connection a5 than to the connection b5, so that the valve spool of the proportional valve 84 is shifted upwards, as shown in FIG. As a result of this displacement, the connections P and P ′ are connected to one another and a corresponding opening of the measuring aperture 14 is 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 sets itself in a control position in which the pressure drop across the measuring orifice 14 can be kept constant regardless of the load pressure. That is, in this control position, the valve slide of the pressure compensator 16 is pushed upwards in the illustration according to FIG. 3, so that the connection between the connections P and A of the pressure compensator is opened. The pressure medium then flows via the connecting duct 76 and the branch duct 80 and the load holding valve 82 to the connection P ″ and from there via the working connection A to the boom. The returning pressure medium is returned to the tank via the working connection B, the tank connection T and the tank channel 74. In the case of boom sinks, a higher control pressure is correspondingly applied to the control connection b5, so that the valve slide in the illustration according to FIG. 3 is shifted downward 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 consumer valve axes of the bucket and the boom being connected in circuit 2 in the exemplary embodiment shown in FIG. 2, and the consumer valve axis of the arm in circuit 4 being connected to summing line 24 or 66. In this case, the consumer valve axes are not connected to the summing lines 24, 66 in both directions of action, but only in the direction in which there is a greater pressure medium requirement, that is to say, for example, in 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.

If, for example, the boom of the excavator is actuated by actuating the control device 46, the higher control pressure in the pilot control line 54 shifts the proportioning valve 36 into the positions marked (b) and opens the summing orifice 26. The input port P2 of the summing proportional valve 36 connected to the pump line 42 of the circuit 4 is then connected via the measuring orifice 26 to the output port P ″, which in turn is connected to the input port P of the summing pressure compensator 28. The pressure downstream of the summing orifice 26 acts in the opening direction on the pressure compensating piston, so that it is shifted 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 the port P 'and the directional part of the summation proportional valve 36 to the summing port S1, which is connected to the summing line 24 of the circuit 2, so that the total to be summed Consumer valve axis, ie in the present case the boom in circuit 2 is additionally supplied with pressure medium from circuit 4. When the boom is actuated, the piston of the LS signaling valve 32 in the illustration according to FIG. 3 is shifted to the right by the higher control pressure in the pilot line 54, so that the LS pressure of the circuit 4 via the LS signaling valve 32 is effective in the closing direction Control surface of the totalizer 28 is performed.

When summing a consumer of the circuit 4, the slide of the summing proportional valve 36 is in the

(a) marked positions moved - the

Summation takes place in the manner described above for the axis to be summed in circle 4.

In the case in which the pressure downstream of the summing orifice 26 is greater than the load pressure in the LS line 18 or 20, the pressure compensating piston of the summing pressure compensator 28 is moved into the control position identified by b), in which this higher pressure in the LS Line 18 or 20 is fed (the connections P and LS of the summing pressure compensator 28 are connected to one another and the latter in turn to the connection 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, i.e. the summed consumer, is higher than the highest load pressure of the second circuit, the summing pressure compensator 28 opens completely and reports the higher load pressure of the summed consumer 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 that the load pressure of the totalized Consumer demands. 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 28 is in the control position and throttles the summation 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.

Appropriate control of the summing axis 12 allows the summation to be out of phase with the respective one

Consumer valve axis are carried out. Such a phase shift can be set, for example, by setting the control range of the summing axis to an upwardly shifted range between, for example, 17 to 24 bar, while the control range of the consumer valve axes is, for example, 6 to 24 bar by suitable selection of the bias of the control springs. 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 at control pressure differences of less than 17 bar, the system works as a two-circuit system and can only be changed over into a single-circuit system by actuating the control valve 38. In the exemplary embodiment described above, the control valve 38 and the LS signaling valve 32 are formed separately from the summation proportional valve 36.

In the exemplary embodiment shown in FIG. 4, the functions of the LS signaling valve 32 and the control valve 38 are integrated in the summing proportional valve 36. In the exemplary embodiment shown in FIG. 4, the consumer valve axes are designed as in the previously described exemplary embodiment, i.e. , Each axis is designed with an LUDV orifice plate 14 and a downstream LUDV pressure compensator 16, whereby some of the consumer valve axes (undercarriage, bucket, boom (circle 2) and stick can be summed up.

The summing valve arrangement 12 in turn contains a summing proportional valve 136 with a summing orifice 26 and a downstream summing pressure compensator 28. The valve spool of the summing proportional valve 136 is in turn acted upon by the control connections a4 and b4, the pilot line 52, 54 and the control units 44, 46 with a control pressure difference, by which Initiate summation. For the sake of clarity, the circuit symbol of the summation proportional valve 136 is shown enlarged in FIG. 4a. Accordingly, the summation proportional valve 136 has the two pressure connections Pl, 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 LSI and LS2 and a further control connection LS are provided. The two connections LS] _ and LS ₂ are connected to the LS lines 20 and 18, the summing connections S1, S2 to the summing lines 24, 66 and the two pump connections P1, P2 to the pump lines 40, 42. As in the exemplary embodiment described above, the connection P ' ¹ leads to the input connection P of the summing pressure compensator 28, the output A of which is connected to the return connection P' via a connecting channel. The further LS connection LS of the summation proportional valve 136 is connected to the LS connection LS of the summation pressure compensator 28, the control pressure applied to the connection LS acting together with a weak spring in the closing direction on the pressure compensator piston. The pressure prevailing downstream of the orifice plate 26 is conducted via a further control line to a control surface of the pressure compensating piston which is effective in the opening direction.

The summation 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 are determined. In this respect, the function of the summation proportional valve 136 corresponds to that of the exemplary embodiment described in more detail in FIG. 2.

In addition to these rule positions, the

Totaling proportional valve 136 a fourth switching position

(c), in which the two connections Pl and P2 and LSI and

LS2 connected to each other and all other connections are blocked.

According to Figure 4, the valve spool of

Totaling proportional valve 136 over two

Control spring assemblies 86, 88 biased. These are for setting the basic position

Control spring assemblies preloaded, the preload - As explained above - can be chosen so that there is a phase shift between the consumer valve axes and the summing axis when the consumers and the summing axis are actuated. The summation proportional valve 136 has a fourth position (c). A piston 90 is held at a stop via a control channel 92 and an overload valve 94 with a high control pressure of, for example, 30 bar. In this stop position, the control spring arrangement 88 is subjected to its basic pretension, in which the valve slide is in its basic position (0). The override valve 94 is activated via a shuttle valve 96, the function of which corresponds to the shuttle valve 64 from FIG. In other words, the input connections of the shuttle valve 96 are connected to the control channel 60 (see FIG. 2) and to a control line leading to a control device (not shown), via which a control pressure can be generated manually by the operator. The greater of these two control pressures (maximum control pressure emitted by the control units 47, 46, 50 48 or manually specified control pressure) is placed on the control surface of the control valve 94 via the shuttle valve 96, so that it acts against the force of a return spring in its (a) marked switching position is movable, in which the control channel 92 is connected to the tank T. The control line 98 carrying the high control pressure is connected in the switching position (a) of the override valve 94 to a further control channel 100, which, as shown in FIG. 4 below, leads to a shuttle valve 102, the other input connection of which is connected to the pilot line 52. That is, the larger of the two control pressures present in the further control channel 100 or the pilot line 52 is led via the shuttle valve 102 to the connection a4 and acts on the control slide of the Totaling proportional valve 136 in the direction of the fourth switching position (c).

When the override valve 94 is switched to the switching position (a), the piston 90 is relieved and moved to a rear stop, and the pretension of the control spring arrangement 88 is correspondingly reduced. The control pressure in the control line 98 is reported by means of the control valve 94 in the further control channel 100 and is led to the shuttle valve 102. Due to the relief of the control spring arrangement 88 and the control pressure present at the connection a4 (control pressure in 100 or control pressure in 52), the valve slide is then moved into the fourth switching position (c), in which the two pump connections P1, P2 and correspondingly also the pump lines 40 , 42 as well as LSI 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. That is, this switching position (c) integrates the function of the control valve 38 from FIG. 2 into the summation proportional valve.

For the summation of a consumer valve axis, the summation proportional valve 136 is placed in one of the (a) or

(b) Move to marked positions. When summing, for example, the one assigned to the handle (see FIG. 2)

Consumer valve axis is activated by pressing the

Pilot control device 44 a comparatively high control pressure is applied to the connection a4, so that the valve slide is moved into one of the positions marked with (a). The axial displacement of the

The valve slide specifies the opening of the measuring orifice 26, via which the pump connection P1 and the output connection P ″ are connected to one another. Due to the pressure downstream of the orifice plate, the summing pressure compensator 28 is converted into a Brought 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 further to the consumer to be summed (stick). As in the exemplary embodiment shown in FIG. 3, the pressure medium flow to be summed is in turn fed via summing ducts 68, which are connected via a check valve 70 to the branch ducts 78 or 80 leading to the directional part of a proportional valve 34, with summation usually only taking place in the direction, in which there is an increased pressure medium requirement.

In positions (a) of the summation proportional valve 136, the two connections LSI and LS are also connected to one another, so that the LS pressure of the summing circuit 2 is present on the pressure compensator 28. In the event that the pressure downstream of the orifice 26 is greater than the load pressure in the LS line 20, the pressure compensator 28 is moved into its end position in which its LS connection is connected to the connection P, so that this pressure is higher than new maximum load pressure is reported in the LS line 20.

The summation of a consumer in circuit 2 is carried out by applying the higher control pressure to port b4 in a corresponding manner, the summing proportional valve then being marked with (b)

Control positions is moved.

If several consumers are controlled in circuit 2, it can happen that the pump flow supplied from circuit 4 is no longer distributed between the consumers to be summed, regardless of the load pressure. To one To ensure optimum control even of the higher-load summed consumers, it is possible to connect nozzles 138 or other throttling devices in the summing channel 68 of the proportional valves 34 to the usually lower-load consumers, so that a simpler oil distribution can be achieved via the directional grooves in the proportional valve 34.

For a better understanding of the valve arrangement, some operating states are explained.

It is. assumed that the bias of the

Valve slide of the summation proportional valve 36, 136 is selected such 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 extended excavator equipment, the pilot devices 44 and 46 are used to set the functions stick-on and

Boom lift actuated in such a way that the maximum control pressure is applied - that is, the metering orifices in the consumer valve axes are fully opened. Since approximately the same control pressure is then present in the two pilot lines 52, 54, 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 no mutual influence of the individual consumers is possible, 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 which results from the different setting of the pilot devices 44, 46. From a control pressure difference of more than 17 bar, the summation then takes place, the pressure medium released being fed out of the boom circuit (circuit 2) via the summation axis into the summation line 66 and from there to the stick, so that a maximum stick speed is ensured.

In the event that the slewing gear is actuated and the boom lift function is activated, two cases are conceivable:

a) The summing axis is acted upon by the control pressure set via the pilot control device 46, the control pressure difference acting on the summing proportional valve 36 being> 17 bar - the summing axis connects the circuit 4 to the circuit 2, so that the quantity of pressure medium not taken up by the rotating mechanism with priority is additionally downstream the orifice plate 34 and the pressure compensator 16 of the boom axis is fed. This takes place during the acceleration phase of the slewing gear. The LS line 18 is connected to the pressure compensator 28 either via the LS signaling valve 32 of the exemplary embodiment according to FIGS. 2 and 3 or via the LS connections of the summing proportional valve 136 of the example according to FIG.

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 circuits 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 actuated, the two circles 2, 4 remain even at very different control pressures, e.g. when cornering in difficult terrain, since no control signal is emitted to the summation axis via the pilot devices 48, 50 for controlling the caterpillars.

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 exemplary embodiment according to FIG. 2, the switching valve 62 is switched over via the control pressure emitted by the pilot control devices 48, 50 for controlling the caterpillars, so that the control valve 38 is controlled by the control pressure generated by the pilot control devices 44, 46 via the line 60 or by connecting one external control pressure is switched to its open position, in which both circuits 2, 4 are connected to the single circuit.

In the exemplary embodiment according to FIG. 4, this connection to the single circuit takes place in that the control pressure emitted by the pilot control units 44, 46 over the control channel 60 and the shuttle valve 96, the override valve 94 is switched so that the piston 90 is relieved and the valve spool of the summing proportional valve 136 is moved into the fourth switching position (c), in which both circuits 2, 4 are summed. As mentioned at the outset, the override valve 94 can also be switched over by applying an external control signal.

The exemplary embodiment according to FIG. 5 differs from that according to FIGS. 2 and 3 only by a different design of the LS signaling valve 32. While the LS signaling valve 32 according to FIGS. 2 and 3, the two LS lines 18 and 20 are separated when summing leaves one another and, depending on the direction of summation, connects the LS line 18 or the LS line 20 to one control side of the pressure compensator 28, the LS signaling valve 32 according to FIG. 5 provides a connection between the two LS lines 18 and 20 and between these two lines 18, 20 and one control side of the pressure compensator 28. Thus, when summing, the two circuits 2 and 4 are always at the same pressure level, which is determined by the highest load pressure of all hydraulic consumers actuated in the two circuits 2, 4. Since the pressure level in the quantity-absorbing circle is thus raised when the highest load pressure is lower than in the quantity-releasing circle, the exemplary embodiment according to FIG. 5 does not appear to be as favorable in terms of energy balance as the exemplary embodiments according to FIGS. 2 to 4.

FIGS. 6a and 6b show two alternatives for reporting the load pressure from one circuit to the other circuit for an exemplary embodiment in which the selection of the highest load pressure does not involve an additional one

Control edge equipped pressure compensator, but for example via a shuttle valve chain or, as shown, via check valves 139. 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 FIG. 6a, in the two lateral switching positions of the LS signaling valve 32, a check valve 140 is connected between the two LS lines 18, 20, which blocks from the LS line 18 of the second circuit to the LS line 20 of the first circuit. 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 according to FIG. 6b, the functions "connecting one control side of the pressure compensator 28 to the LS line of the second circuit" and "reporting a higher LS pressure of the first circuit in the second circuit" are divided between two valves 32, 33. The LS signaling valve 32 is identical to that of the exemplary embodiment according to FIGS. 2 and 3. An LS switching valve 33 is actuated at the same time as the LS signaling valve 32 and switches one or the other check valve 140 between the two LS lines 18 depending on the direction of summation , 20th

In the two alternatives according to FIGS. 6a and 6b, the LS pressure of the first circuit is also reported to the second circuit if the load pressure of the consumer (s) or the summed consumers is lower, but the LS pressure of the first circuit is higher than the LS -Print the second circle. As in the exemplary embodiments according to FIGS. 2 to 4, it should only be a comparison of FIGS If the load pressures of the summed consumers arrive with the LS pressure of the second circuit, then the highest load pressure of the summed consumers should be able to be selected separately and be present in lines 18, 20 of FIGS. 6a and 6b independently of the LS lines leading to the variable displacement pumps.

Disclosed is a hydraulic two-circuit system for controlling consumers of a mobile device, in particular a chain device, the two circuits being summable for selected consumers by means of a summing valve arrangement. The consumer is supplied with pressure medium via a LUDV measuring orifice and a LUDV pressure compensator. The summing valve arrangement is designed in such a way that the summed volume flow from the summed circuit downstream of the metering orifice is fed into the other circuit and / or that the summation takes place relatively late, ie out of phase with the summed consumer.

LIST OF REFERENCES

1 . District 2. Circuit variable pump variable pump consumer consumer summing valve arrangement measuring orifice pressure balance LS line LS line load holding valve pump line summing line summing orifice summing pressure balance working line LS signaling valve LS switching valve proportional valve summing proportional valve control valve pump line pump line manually operated pilot valve manual control valve unit foot-operated pilot valve change-over valve Switching valve summing line summing channel check valve directional part tank channel connecting channel branch channel branch channel load holding valve load holding valve control spring arrangement control spring arrangement piston control channel override valve shuttle valve control line additional control channel totaling proportional valve nozzle check valve check valve

Claims

Expectations

1. Hydraulic two-circuit system for controlling consumers of a mobile device, in particular one

Chain device, whereby each hydraulic circuit (2, 4) is assigned a variable displacement pump (6, 7) that is controlled as a function of the highest load pressure, via which the assigned consumers can be supplied with pressure medium, and the two circuits (2, 4) have a summing valve arrangement ( 12) can be connected to one another in such a way that the pump (6, 7) of one circuit (2, 4) conveys pressure medium into the other circuit (4, 2), so that at least one consumer connected to this circuit (4, 2) Both pumps (6, 7) can be supplied with pressure medium and the consumer is assigned an LUDV valve arrangement with an orifice plate (14) and pressure compensator (16), characterized in that the pressure medium from the one connected circuit () 2, 4) is fed via a summing line (24, 66) downstream of the measuring orifice (14) and the pressure compensator (16) of the summed consumer.

2. Two-circuit system according to claim 1, wherein the summing line (24, 66) opens downstream of the measuring orifice (14) and upstream of a directional part of a measuring valve (14) forming proportional valve (34).

3. Two-circuit system according to claim 1 or 2, wherein the summing valve arrangement (12) has a summing proportional valve (36) with a downstream summing pressure compensator (28).

4. Two-circuit system according to claim 3, wherein the activation of the summation proportional valve (36) is carried out hydraulically by application of a control pressure.

5. Two-circuit system according to claim 4, wherein the control pressure depending on the actuation of a ballast (44, 46, 48, 50) or depending on other logic is applied to the summing proportional valve (36).

6. Two-circuit system according to one of claims 3 to

5, the summing valve arrangement (12) having an LS signaling valve (32), via which a control side of the summing pressure compensator (28) can be acted upon by the highest load pressure of a circuit (2, 4).

7. Two-circuit system according to one of claims 3 to

6, wherein the summing valve arrangement (12) has, in addition to the summing proportional valve (36), a control valve (38) via which lines (40, 42; 18, 20) of the two circuits (2, 2) carrying the pump pressure and the load pressure as a function of a control signal. 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) are integrated in the summation proportional valve (136).

9. Two-circuit system according to one of claims 3 to 8, wherein a main slide of the proportional valve (34) assigned to the consumer and the summing proportional valve (36) are biased by means of control springs into a basic position, the bias of the summing proportional valve (36) assigned control spring is greater than that of the proportional valve (34) assigned to the consumer.

10. Two-circuit system according to one of the preceding claims, wherein the feed for at least one summed consumer (8, 10) via a throttle device (138).

11. Two-circuit system according to claim 8, with an override valve (24) via which the summing 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 circuits (2, 4 ) are connected.

12. Two-circuit system according to one of the claims 3 to 11, wherein the load load valves (82, 84) are connected upstream and the summing line (24, 66) opens between the load holding valve (82, 84) and a directional part of the proportional valve (34).

13. Hydraulic two-circuit system for controlling consumers of a mobile device, in particular one

Chain device, whereby each hydraulic circuit (2, 4) is assigned a variable displacement pump (6, 7) that is controlled as a function of the highest load pressure, via which the assigned consumers can be supplied with pressure medium, and the two circuits (2, 4) have a summing valve arrangement ( 12) can be connected to one another in such a way that the pump (6, 7) of one circuit (2, 4) conveys pressure medium into the other circuit (4, 2), so that at least one consumer connected to this circuit (4, 2) two pumps (6, 7) can be supplied with pressure medium and wherein the consumer is assigned an LUDV valve arrangement with orifice plate (14) and pressure compensator (16), characterized in that the summing valve arrangement (12) is generated as a function of that of a control unit (44, 46; 50, 48) for controlling the consumer Control signals and can be controlled arbitrarily via a logic.

1 . Dual circuit system according to claim 13, wherein the summing valve arrangement (12) is a summing orifice

(26) and a totalizer (28), the

Totalizing orifice (26) for initiating totalizing by means of a control pressure one

Control pressure difference is displaceable in an open position.