DE19542275B4 - Priority flow circuit - Google Patents

Abstract

Priority flow circuit to supply several consumers of a work machine with Hydraulic fluid from a hydraulic pump, wherein the division of the hydraulic fluid flow to consumers over at least one priority valve arrangement takes place and a first consumer, preferably a braking system, preferred over other consumers with hydraulic fluid from a hydraulic accumulator can be supplied, which is associated with a storage loading valve assembly is, characterized in that the control of another Consumer (34, 38) over the accumulator charging valve assembly (14) takes place that of the first Consumer (32) not needed Hydraulic fluid flow to the other consumer (34, 38) passes.

Description

The The invention relates to a preferred current circuit according to the preamble of claim 1

In working machines, such as wheel loaders or agricultural utility vehicles, several hydraulic consumers are driven by a common pump, for example a constant pump system with gear pump or a control pump system with a variable displacement pump. The consumers may be a steering circuit, a brake circuit, a fan circuit or directional control valves connected to the working machine working units. For safety and legal reasons, it is necessary that the steering circuit, the brake circuit and the fan circuit are preferably supplied in this order with hydraulic fluid. That is, the supply of the directional valves with hydraulic fluid takes place only when required for the operation of the machine and for their safety consumers are subjected to the required pressure. In order to ensure such a supply, a so-called preferred circuit is constructed, in which the distribution to the different consumers in the preferred order is carried out via series-connected priority valves. Such a preferred circuit is shown for example in the data sheet of the Applicant RD sheet 66105, Figure 3, whose principle circuit diagram for three consumers A, B, C in 1 is already referred to here.

As shown in 1 is the, for example, funded by a control pump system hydraulic fluid flow first to a first priority valve 2 which is biased in its home position to a position in which the hydraulic fluid flow to a second priority valve 4 is guided. In the in 1 illustrated basic position of the second priority valve 4 the preferred consumer A is supplied with hydraulic fluid. The load pressure at the consumer is via a control line 6 to a control side of the second priority valve 4 guided, so that this is brought to the increase in the load pressure in a position in which the consumer A downstream consumer B is supplied with hydraulic fluid. In this position, no hydraulic fluid is directed to the consumer C with the lowest ranking.

The load pressures at the consumer A and the consumer B are via a shuttle valve 8th and a control line 10 to a control side of the first priority valve 2 guided, so that the larger of the load pressures at the load A and the consumer B is applied to this control line.

If the two consumers A, B are sufficiently supplied with hydraulic fluid, the first priority valve 2 brought into a position in which the consumers A, B downstream consumer C can be supplied with hydraulic fluid from the pump system. This means that the supply of the downstream consumer C takes place only when the two preferred consumers A and B, for example, the steering and the brake system are supplied with hydraulic fluid.

By controlling the first priority valve 2 and the second priority valve 4 With the load pressures at the consumers A and B, these two priority valves also act as pressure control valves which keep the pressure drop across the consumers A and B constant. Such a known preferred current circuit thus requires for three consumers at least two series-connected priority valves and thus requires a considerable circuit complexity, so that the preferred circuit on the one hand is relatively expensive to manufacture and on the other hand requires considerable space.

From the DE 38 21 415 A1 a hydraulic control circuit for a trailer brake valve is known, which is supplied via a priority valve by a pump, which is used to supply an additional auxiliary consumers.

From the DE 35 07 122 A1 is a priority control for hydraulic consumers known in which the inflow to the subordinate consumer is set by a designed as a pressure compensator flow control valve, which acted upon by the control pressure of the subordinate consumer control chamber via a proportional valve can be relieved of pressure.

From the DE 22 36 484 C2 a storage charging valve assembly is known, which is connected between a charge pump, a memory and a pressure medium container to separate the pump from the memory and to connect to the container upon reaching a predetermined storage pressure.

The The object of the invention is to provide a preferred current circuit create, with minimal device engineering effort a adequate supply of the preferred consumers of a work machine guaranteed.

These The object is solved by the features of claim 1.

By the preferred circuit according to the invention becomes a facility for supplying multiple consumers Work machine available one of the consumers preferably a braking system with a hydraulic accumulator over a storage charging valve arrangement is controlled and wherein the control of another consumer, such as one Fan or the directional valves of a working device or another priority valve directly or indirectly via the accumulator charging valve arrangement takes place that of the hydraulic accumulator and the consumer connected thereto, preferably in the brake system not needed Hydraulic fluid flow passes to another consumer.

By This measure let yourself allocate a dual function to the accumulator charging valve assembly, i. H. on the one hand the supply of the memory with pressurized fluid and on the other the supply of another consumer with those from the store not needed Hydraulic fluid flow. The accumulator charging valve arrangement takes over thus essentially the function of a priority valve, so that the device-technical Effort compared usual solutions can be reduced considerably.

By the preferred circuit according to the invention can be, for example, a brake system, a fan and the We ge valves a work machine with a priority valve and the anyway needed Carry out storage loading valve arrangement, so that a priority valve across from Saved conventional solutions can be.

In the dependent claims 3 to 5 are four particularly advantageous variants of the circuit according to the invention claimed.

dependent claim 2 relates to an embodiment, where the accumulator charging valve over a first priority valve supplied with hydraulic fluid, so that the division of the two preferred consumers, such as the brake system and the fan on the Storage loading valve arrangement takes place.

In the alternative variant according to dependent claim 3, the accumulator charging valve assembly is also downstream of first priority valve arranged over the hydraulic fluid is one of the preferred consumers, for example the fan, directly supplied is, and by the hydraulic fluid flow not required by this consumer led to the accumulator charging valve assembly, over which the further preferred Consumers, for example, the brake system and then the downstream Consumers are supplied.

at the alternative embodiment according to dependent claim 4 is a priority valve downstream the accumulator charging valve arrangement provided over the first preferred supply of the consumer provided with a memory. The of this unneeded Hydraulic fluid volume flow is directed to the priority valve via which first the other consumer and then the downstream consumer are available.

While at the first two embodiments the consumer provided with the memory, i. for example the brake system always preferably supplied with hydraulic fluid volume flow is in the latter embodiment, a first second consumer, for example, the fan and then only the accumulator charging valve assembly and thus the consumer provided with the hydraulic accumulator, for example the braking system, supplied. Such a division contradicts while conventional Ideas about operational safety. By suitable vote of the individual components, but can be relatively easily ensured be that the hydraulic accumulator always sufficiently supplied with hydraulic fluid. The latter Variant may be particularly advantageous if already certain valve units are available in the modular system and the interconnection after this Variant with these elements with low investment costs is feasible.

in the Unteranspruch 5 is finally an alternative embodiment explains connected in parallel to the accumulator charging valve, a pressure control valve is over this is a fan motor is supplied with hydraulic fluid, and wherein the accumulator charging valve assembly by the load pressure of the fan is controlled, for example, the brake system and more supply downstream consumers with hydraulic fluid. By the parallel connection of the pressure control valve and the accumulator charging valve assembly is with appropriate coordination of fan motor, hydraulic accumulator and pump capacity a constant fan speed ensured at sufficient charge pressure of the hydraulic accumulator.

A a particularly simple structured accumulator charging valve arrangement is obtained, if designed with a 2-way proportional valve as a pressure compensator is, which is switchable, for example, as a circulation pressure balance, so that when exceeding the desired Memory pressure a supply of the downstream consumer over the 2-way proportional valve takes place. Such storage charging valve arrangements commonly referred to as an open-center memory loading or pressure switching valve known.

The priority valve is also in a conventional manner as a 2-way proportional valve executed as described for example in DE-OS 38 21 115.

The The above-described preferred current circuit can be particularly advantageous in a work machine with a brake system, a fan and directional valves to control a working device, these three consumers according to a the previously described embodiments with each other are interconnected and this circuit a priority valve upstream, so that a Steering the work machine preferred over the other consumers be supplied with the hydraulic fluid flow from the pump system is.

As already mentioned at the beginning, The system can be equipped both with a variable displacement pump with pressure flow control device be operated as well with a constant pump. In both cases, the discharged from the pump systems hydraulic fluid flow over the highest at the consumers (steering, brake system, fans, directional valves, etc.) Load pressure activated.

Further preferred embodiments of The invention will be explained below with reference to schematic drawings.

It demonstrate:

1 a block diagram of a conventional preferred power circuit;

2 a block diagram of a first embodiment of a preferred current circuit according to the invention;

3 a concrete embodiment of a circuit according to 2 ;

4 a block diagram of a second embodiment of a preferred circuit according to the invention;

5 a concrete embodiment of a circuit according to 4 ;

6 a block diagram of a third embodiment of a preferred circuit according to the invention;

7 a concrete embodiment of a circuit according to 6 and

8th a concrete circuit of a fourth embodiment of a preferred current circuit.

In 2 an embodiment of the preferred circuit according to the invention is shown, in which three consumers, more precisely a brake system A, a fan B and directional control valves C of a working machine with hydraulic fluid can be supplied. The brake system A, and the fan B should preferably be supplied to the directional control valves C.

In the block diagram according to 2 For the sake of clarity, the pump arrangement and other consumers of the working machine hydraulic circuit have been omitted. The circuit has a first priority valve arrangement 12 , which is connected via a pump working line to the pump system (not shown in 2 ). The funded by the pump derge hydraulic fluid flow is first on the first priority valve assembly 12 towards the preferred consumers, ie the brake system A and the fan B out. The brake system has a reservoir charging valve assembly 14 that has the first priority valve arrangement 12 is supplied with hydraulic fluid and via a hydraulic accumulator 16 of the brake system can be loaded. In the supply line to the hydraulic accumulator 16 is a check valve 18 to prevent backflow from the charged hydraulic accumulator 16 and a stare 20 to set the maximum accumulator hydraulic fluid flow rate. To another terminal of the accumulator charging valve assembly of the fan B is connected, wherein the control of the system initially takes place such that preferably the hydraulic accumulator 16 via the accumulator charging valve arrangement 14 can be supplied with hydraulic fluid. The for charging the hydraulic accumulator 16 Unused hydraulic volume flow component is diverted to the fan B, which is ensured by the appropriate tuning of the flow rate of the pump, the power of the fan motor and the maximum storage tank hydraulic volume flow, that the fan motor during the charging process of the hydraulic accumulator 16 is sufficiently supplied with hydraulic fluid, so that at any time a corresponding fan speed and thus the desired cooling capacity is provided. The vote of the components is essentially that the set boost pressure for the hydraulic accumulator corresponds approximately to the maximum load pressure on the fan motor.

By the measure to supply the fan at any time with a sufficient hydraulic fluid volume flow and fan motor load pressure and boost pressure to select about the same order of magnitude, a sufficient cooling is guaranteed even with a maximum power requirement of the fan. When the hydraulic accumulator 16 is charged accordingly and the fan motor runs at its predetermined minimum speed, is on the priority valve assembly 12 the unused hydraulic fluid flow to the downstream consumer, ie the directional control valves C passed. For controlling the first priority valve arrangement 12 are the Hydraulic accumulator boost pressure and the load pressure on the fan motor B led to the two inputs of a shuttle valve, so that the larger of these two control pressures to the control side of the priority valve assembly 12 to be led. This interconnection ensures that the downstream consumer C is only supplied when the charge pressure of the hydraulic accumulator and the load pressure at the fan motor have reached their predetermined minimum values.

In 3 a preferred power circuit of a wheel loader is shown, in addition to the above three consumers: brake system A, fan B and directional control valves C still a steering (not shown) is supplied with hydraulic fluid, which is preferred over the other consumers A, B, C. That is, in this embodiment, the consumers A, B, C are connected downstream to the steering.

In the 3 shown preferred circuit has a variable displacement pump 22 with a pressure flow regulator (on the individual components of the variable displacement pump 22 will be discussed in more detail below), by the hydraulic fluid via a working line 24 towards a second priority valve arrangement 26 is guided over which in the slider position shown, the steering is preferably supplied with hydraulic fluid. The hydraulic fluid volume flow not required by the steering is transmitted via a pressure line 27 to a circuit part having the first priority valve arrangement 12 led out of the arrangement 2 equivalent.

In the illustrated position of the first priority valve arrangement 12 the hydraulic fluid is via a working line 28 towards the entrance of a storage loading valve assembly 30 guided, whose structure will be described in more detail below. A connection of the accumulator charging valve assembly 30 is with the hydraulic accumulator 16 a braking system 32 connected.

Another connection of the accumulator charging valve assembly 30 is with a work administration 33 connected to the fan assembly 34 leads, whose fan motor 78 is driven by the hydraulic fluid volume flow.

A second output of the first priority valve arrangement 12 is about a work line 36 with another downstream consumer 38 connected, which may include a variety of directional control valves, hydraulic cylinders, etc.

The variable pump 22 includes the actual variable displacement pump assembly 40 known design, which has a pressure flow regulator 42 is controlled. This has a continuously adjustable flow control valve 44 , on one of its control side via a load pressure signaling line 45 the load pressure of a consumer rests and thereby the volume setting of the variable displacement pump assembly 40 is regulated so that a load pressure independent flow rate flows to the consumer. As in the present case a large number of consumers (steering, braking system 32 , Fan assembly 34 and other consumers 38 ) must be provided, it must be ensured that the respective largest prevailing at the aforementioned consumers load pressure to the flow control valve 44 is guided. These are load pressure signaling lines of the individual consumers on wax valves 48 to 50 connected in cascade manner in a known manner so that the respective highest load pressure at said control side of the flow control valve 44 is applied.

If a preset maximum operating pressure is reached, then via a pressure control valve 46 the flow rate of the pump is limited so that the preset maximum operating pressure is not exceeded. The system then works as a constant pressure system. For a more detailed description of the variable displacement pump 22 can be omitted here, since such a structure is known from the prior art.

The priority valve assemblies used in the circuit 12 . 24 have substantially the same structure, based on the priority valve for the second priority arrangement 26 should be described.

The priority valve arrangement 26 has a continuously adjustable 2-way valve 52 , Also called compensating valve, which is biased by a valve spring into a basic position in which the working line 24 with a pressure pipe leading to the steering 54 connected is. The load pressure in the pressure line 54 is via a control line 56 to the spring side of the 2-way valve 52 and via a control line 58 led to the other control side of the 2-way valve. In the control lines nozzles are arranged, via which the valve spool movement is to be damped. The in the control line 58 lying nozzle is bypassed via a bypass line in which a check valve is arranged, which is a relief of the control side of the 2-way valve 52 and thus allows a faster adjusting movement of the valve spool. In the control line 56 is also a pressure relief valve 60 provided via which the pressure in the control line 56 can be limited to a predetermined maximum value. The pressure relief valve 60 , the nozzle in the control line 58 and also the bypass line of this nozzle are optional components of the priority valve arrangement, for example in the first priority valve arrangement 12 are not provided.

When the pressure at the output of priority valve arrangement, ie in the second priority valve arrangement 26 in the pressure line 54 increases, the valve spool of the 2-way valve 52 moved out of his shown basic position and also a connection between the work line 24 and the pressure line 27 made so that hydraulic fluid to the other consumer (brake system 32 , Fan 34 , more consumers 38 ) is guided. In the present case, this means that the hydraulic fluid to the input of the first priority arrangement 12 is guided.

As already mentioned, the construction corresponds to the first priority valve arrangement 12 that of the second priority arrangement 26 , where the 2-way valve 52 ' on its spring side via a control line 56 ' with the pressure in the working line 28 is acted upon and where also a throttle in the controller 56 ' is provided. Furthermore, the pressure in the working line 28 via a control line 58 ' to the other control side of the 2-Wegevantils 52 guided. That is, as soon as in the work line 28 builds up a predetermined pressure is above the control pressure in the control line 58 ' the valve spool of the 2-way valve 52 pressurized so that the brake system 32 and the fan 34 Unused volume flow to the other consumers 38 is directed.

The brake system 32 associated storage loading valve assembly 14 also has a known structure, as used for example for loading a hydraulic accumulator with a constant pump. Accordingly, the accumulator charging valve assembly 14 a pressure balance 62 , which is designed as a continuously adjustable 2-way valve. The pressure balance 62 is adjustable from a basic position in which the connection from the working line 28 towards the fan 34 leading pressure line 33 is shut off, via the hydraulic fluid flow between the lines 28 and 66 throttling intermediate positions up to a final position in which the connection to the fan 34 is completely turned on. From the work management 28 branches a storage charging line 68 down to the brake system 32 is guided and the pressure balance 62 bypasses. In the store loading line 68 is a stuck throttle 70 provided, over which the maximum Spei cherladevolumenstrom is adjustable. Furthermore, the storage charging line has 68 a check valve 72 , the only hydraulic fluid flow to the hydraulic accumulator 16 allowed.

Between the check valve 72 and the stager 70 branches from the storage charging line 68 a branch line leading to a control valve 64 is performed, which is executed in the embodiment shown as a 2/2-way valve. In its spring-biased basic position of the in the storage charging line 68 downstream of the fixed throttle 70 prevailing fluid pressure via the control valve 64 and a control line 71 to the spring side of the pressure balance 62 guided, while the upstream of the fixed throttle 70 prevailing pressure in the storage charging line 68 led to the other control side of the pressure compensator.

The at the output of the control valve 64 prevailing pressure is also to the two control sides of the control valve 64 guided. Further, the control side of the control valve remote from the spring-biased control side is 64 still via a control pressure line with the downstream of the check valve 72 prevailing pressure applied. When the pressure in this line section of the storage charging line increases 68 becomes the control valve 64 moved to its other switching position in which the control line 71 via a tank line 74 connected to a tank T. That is, in the second switching position of the control valve 64 becomes the spring side of the pressure balance 62 Relieved, so that the connection to the pressure line 33 turned on and the fan 34 is supplied with hydraulic fluid. This control of the pressure balance 62 takes place parallel to the loading of the hydraulic accumulator 16 so that practically both consumers (here: brake system, fan) can be supplied simultaneously with hydraulic fluid.

The brake system 32 includes in the above-described embodiment, the hydraulic accumulator 16 consisting of two partial stores 16a and 16b exists, which are each assigned to one of the brake circuits BR1 and BR2. The two hydraulic accumulators 16a . 16b are via a shuttle valve 74 with a brake valve assembly 76 connected via the hydraulic accumulators 16a . 16b can be connected to the brake circuits BR1 and BR2. The construction of the brake valve 76 is known per se, so that omitted here to a description and reference is made to the present literature.

Via the pressure line 33 becomes a fan motor 78 supplied with hydraulic fluid. The activation of the fan motor 78 takes place in the embodiment shown via a thermo valve arrangement 80 in a bypass line 82 to the fan motor 78 is arranged, which opens in the tank T, which also with the output of the fan motor 78 connected is. In the bypass line 82 is a stuck throttle 83 provided for adjusting the bypass current. About the thermo valve arrangement 80 can the bypass flow rate through the bypass line 82 towards the tank T are set temperature-dependent, so that it is possible to set a corresponding dependence of the fan speed.

As already related to 2 which illustrates the block diagram of the above circuit (except for the second priority valve arrangement 26 ) is shown by this Ausfüh For example, first supply the steering system as a preferred consumer with hydraulic fluid and the unused hydraulic fluid flow to the first priority valve assembly 12 and then to the accumulator charging valve assembly 14 forwarded via the one division of the hydraulic volume flow to the other preferred consumer brake system 32 and fans 34 he follows. Only when the three preferred consumers are sufficiently supplied with hydraulic fluid, there is a control of the other consumers 38 (For example, directional control valves of a working device).

This variant has the advantage over conventional solutions that a priority valve is saved by the inventive use of the accumulator charging valve arrangement, wherein for the accumulator charging valve arrangement 14 a commercially available, known in the art valve assembly may be used. However, this system has the disadvantage that when starting the vehicle, the fan during charging of the hydraulic accumulator 16a . 16b running at a comparatively high speed.

To overcome this disadvantage, the following can be used 4 and 5 shown circuit, which is essentially the same components as the circuit of the 2 and 3 contains.

4 shows a block diagram of this circuit variant, again for the sake of clarity, the control of the steering has been omitted, which is identical in all the embodiments shown.

The hydraulic fluid volume flow not required by the steering initially becomes the accumulator charging valve arrangement 14 guided, via which the control of the brake system A with the brake valve assembly (in 4 not shown) and the hydraulic accumulator 16 he follows. The maximum charging current of the hydraulic accumulator 16 is again through a fixed throttle 20 limited and a return flow through a check valve 18 locked out. The hydraulic fluid volume flow not required by the brake valve A becomes the first priority valve arrangement 12 thus, in this embodiment, downstream of the accumulator charging valve assembly 14 is arranged. About the first priority order 12 the distribution of the hydraulic fluid volume flow is first on the fan B and then, when the load pressure at the fan B has become sufficiently high, the supply of the downstream further consumer C. To control the first priority valve assembly 12 the load pressure on the fan B is guided via a control line to the priority valve.

5 shows a belonging to this embodiment concrete circuit for the consumers of a work machine, the consumer turn a steering, a braking system 32 , a fan 34 and other consumers, such as directional control valves 38 are. The concrete circuit again has a variable displacement pump 22 with pressure-flow regulator, whereby by a corresponding cascade connection via shuttle valves 84 to 86 it is ensured that the maximum load in the system at the pressure-flow regulator of the variable displacement pump 22 is applied. The of the variable displacement pump 22 delivered hydraulic fluid volume flow in turn becomes the second priority valve arrangement 26 guided, which is assigned to the steering circuit and from there to the accumulator charging valve assembly 14 about the supply of the braking system 32 and - via the with the output of the Speicherladeventilanordnunq 14 associated priority arrangement 12 - ventilation 34 and the other consumer 38 he follows. The structure of the individual components essentially corresponds to that 3 , so that can be dispensed with a detailed description. In this embodiment, the fan 34 thus associated with its own pressure control valve, so that with proper sizing of fan motor, storage charging current and pump capacity a constant fan speed is ensured even during the charging of the hydraulic accumulator.

In the 6 and 7 a further embodiment of a preferred circuit according to the invention is shown. In this variant, the hydraulic fluid volume flow not required by the steering becomes the first priority arrangement 12 passed, over which a preferred supply of the fan B with hydraulic fluid. The unnecessary hydraulic fluid volume flow becomes the accumulator charging valve arrangement 14 out, over which a preferred charging current to the hydraulic accumulator 16 of the brake system A is branched off, again a fixed throttle 20 and a check valve 18 are provided to limit the maximum charging current or to prevent backflow in the storage charging line. The hydraulic fluid volume flow not required by the brake system A is transmitted via the accumulator charging valve arrangement 14 towards the downstream consumers, for example directional valves C headed.

As from the concrete circuit according to 7 shows, is about the variable displacement pump 22 a hydraulic fluid volume flow first to the second priority valve arrangement 26 guided the steering and the hydraulic fluid flow not required by the latter to the first priority valve arrangement 12 via which a distribution of the hydraulic fluid volume flow towards the fan 34 and the accumulator charging valve assembly 14 he follows. About the accumulator charging valve assembly 14 First, the hydraulic accumulators 16a and 16b of the brake system 32 and downstream of the other consumers, ie the directional control valves 38 provided.

This circuit contradicts conventional ideas of reliability, since the fan is practically supplied with hydraulic fluid compared to the brake system. By a suitable vote and design of the fan motor, the accumulator charging current and the Verstellpumpenkapazität can still ensure at any time that the brake system is sufficiently supplied with hydraulic fluid, so that the hydraulic accumulator 16a . 16b can be loaded at any time. This variant has the advantage that possibly already existing in a modular system valve components can be used in a simple manner, without modifications are required.

In 8th a further variant of the preferred circuit according to the invention is shown, in which a pressure control valve 88 to supply the fan 34 parallel to the SpeI cherladeventilanordnung 12 is switched. That is, that of the variable displacement pump 22 funded and not required by the steering hydraulic fluid flow is via the second priority valve assembly 26 towards a node 90 guided, on which a line for connection of the pressure control valve 88 and a work management 92 connected to each other. The latter is to the accumulator charging valve assembly 14 guided, via the division of the hydraulic fluid flow to the brake system 32 and to the directional valves 38 he follows.

The delivery rate of the variable displacement pump 22 is determined by a control pressure corresponding to the maximum, applied to the load load pressure, in turn via a cascade circuit with shuttle valves 94 to 96 to the variable displacement pump 22 is guided.

He joined the work management 92 subsequent circuit section corresponds in practice to that circuit section which is connected to the first priority valve arrangement 12 according to 7 connects, so that can be dispensed with a further description.

The pressure control valve 88 is designed as a continuously adjustable 3-way valve that can be controlled on a control side via a sensor, with the load pressure on the fan 34 can be acted upon. An output of the pressure control valve 88 is via a fan line 98 to the fan motor 78 of the fan 34 guided. From the fan line 98 branches a control line 100 from that to the other control side of the pressure control valve 88 is guided so that this practically acts as a pressure reducing valve and the pressure applied to the fan pressure proportional to the pressure of the thermo valve 80 regulates. A third port of the pressure control valve 88 is connected to the tank T.

In the event that the fan temperature is comparatively low, there is the pressure control valve 88 in a switching position in which the connection between the fan line 98 and the tank T is turned on. As the temperature rises, so must the fan speed 34 be increased, that via the encoder, the pressure control valve 88 is controlled such that the connection between the tank T and the fan line 98 controlled and the fan line 98 with the work management 27 via which the hydraulic fluid volume flow from the second priority arrangement 26 to the node 90 is directed. That is, in this position, the storage charge valve assembly 14 and the fan 34 supplied in parallel with hydraulic fluid.

From the bypass line 82 of the fan 34 branches a control line 99 off, via the shuttle valve 94 with the spring-loaded control side of the pressure balance 62 is connected so that it at a high load pressure on the fan 34 is moved in the direction of its closed position, and thus on the load pressure of the fan 34 always at least to the needs of the fan motor 78 is throttled. For storage loading may be higher. This circuit also ensures that the fan 34 at any time sufficiently supplied with hydraulic fluid. The adequate supply of the brake system and the other downstream consumers is in turn made possible by a suitable coordination and design of the variable displacement pump capacity, the storage charging current and the fan motor.

By the preferred circuit according to the invention will be a system available placed, with minimal device complexity a Supplying three consumers, one of which is preferably a Braking system with a hydraulic accumulator is made possible, taking the brake system and at least one other consumer via the accumulator charging valve assembly are controllable.

Claims (11)

Preference power circuit for supplying several consumers of a work machine with hydraulic fluid from a hydraulic pump, wherein the distribution of the hydraulic fluid flow to the consumer via at least one priority valve arrangement and a first consumer, preferably a brake system, preferably over other consumers with hydraulic fluid from a hydraulic accumulator can be supplied, the one Memory charging valve assembly is associated, characterized in that the control of another consumer ( 34 . 38 ) via the accumulator charging valve arrangement ( 14 ), which corresponds to that of the first consumer ( 32 ) not required hydraulic fluid flow to the other consumer ( 34 . 38 ). A preferred current circuit according to claim 1, characterized in that the accumulator charging valve arrangement ( 14 ) downstream of a first priority valve arrangement ( 12 ) on which a third consumer ( 38 ) is supplied with hydraulic fluid, when the supply of the preferred first and second consumers ( 32 . 34 ) via the accumulator charging valve arrangement ( 14 ) is guaranteed. A preferred current circuit according to claim 1, characterized in that the accumulator charging valve arrangement ( 14 ) downstream of a first priority valve arrangement ( 12 ), via which a second consumer ( 34 ) is supplied with the hydraulic fluid and on the second consumer ( 34 ) Unused hydraulic fluid volume flow for supplying the first consumer ( 32 ) and a third consumer ( 38 ) to the storage loading valve arrangement ( 14 ) is feasible. A preferred circuit according to claim 1, characterized in that downstream of the accumulator charging valve arrangement ( 14 ) a first priority valve arrangement ( 12 ), on which the second consumer ( 34 ) and a third consumer ( 38 ) are supplied with hydraulic fluid and via the accumulator charging valve arrangement ( 14 ) with that of the first consumer ( 32 ) Unnecessary hydraulic fluid volume flow can be supplied. A preferred current circuit according to claim 1, characterized in that parallel to the accumulator charging valve arrangement ( 14 ) a pressure control valve ( 88 ), via which a fan motor ( 78 ) of a fan ( 34 ) is supplied with hydraulic fluid and depending on the fan load pressure from a the fan line ( 98 ) to the fan ( 34 ) with a tank (T) connecting position can be brought into a position in which the fan line ( 98 ) is supplied with the hydraulic fluid, wherein the fan load pressure for controlling the accumulator charging valve arrangement ( 14 ) into a position where the third consumer ( 38 ) is acted upon with hydraulic fluid. Preference circuit according to one of claims 1 to 4, characterized in that the accumulator charging valve arrangement ( 14 ) a 2-way proportional valve as a pressure compensator ( 62 ), on the one hand with the voltage applied to the storage system system pressure and on the other hand with the boost pressure of the hydraulic accumulator ( 16a . 16b ) is controllable, so that falls below a predetermined load volume flow, a connection to the other consumer ( 34 . 38 ) is interrupted and that when the loading volume flow is exceeded, the fluid connection to the further consumer ( 34 . 38 ) is aufsteuerbar. Preference circuit according to one of claims 1 to 4, characterized in that the priority valve arrangement is a 2-way proportional valve ( 52 ), depending on the load pressure of a preferred consumer ( 32 . 34 ) connect to the other consumer ( 38 ) is aufsteuerbar. Preference circuit according to one of claims 1 to 7, characterized in that the priority valve arrangement ( 12 ) and the accumulator charging valve assembly ( 14 ) a second priority valve arrangement ( 26 ), via which the hydraulic fluid volume flow is guided to a steering as a preferred consumer. Preference circuit according to one of claims 1 to 8, characterized in that the hydraulic pump is a variable displacement pump ( 22 ) with a pressure-flow control device ( 44 . 46 ), which, depending on the highest of consumers ( 32 . 34 . 38 ) applied load pressures can be controlled. Preference circuit according to one of claims 1 to 7, characterized in that the pump is a fixed displacement pump whose output to the preferential current circuit hydraulic fluid flow is adjustable by a pressure compensator, which depends on the highest of the consumers ( 32 . 34 . 38 ) applied load pressures an excess current in a tank (T) returns. Preference circuit according to one of the preceding claims, characterized in that the first load is a braking system ( 32 ) and the second consumer a fan ( 34 ).