DE19542275A1 - Priority control for vehicle hydraulic system - Google Patents

Abstract

The hydraulic system has a priority valve (12) which splits the hydraulic flow from the pump to a first priority path, represented by a control valve (14) and a low priority hydraulic circuit (C). The control valve supplies the main priority brake system (A) and a second priority blower system (B). The brake system is backed by a pressure reservoir (16). The pressure reservoir, and the brake system are connected to the control valve by a flow limiter (20). Excess fluid is diverted to the second hydraulic circuit when there is sufficient flow to the brake system. The priority valve supplies the lowest priority circuits when the main priority systems have sufficient fluid.

Description

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

In working machines, such as wheel loaders or agricultural vehicles, several hydraulic consumers are controlled by a common pump, for example a constant pump system with a gear pump or a control pump system with a variable displacement pump. The consumers can be a steering circuit, a brake circuit, a fan circuit or directional valves of work units connected to the work machine. For safety and legal reasons, it is necessary that the steering circuit, the brake circuit and the fan circuit are preferably supplied with hydraulic fluid in this order. This means that the directional control valves are only supplied with hydraulic fluid when the consumers required for the operation of the working machine and for its safety are pressurized. In order to ensure such a supply, a so-called preferred current circuit is built up, in which the distribution among the different consumers in the preferred order is made via priority valves connected in series with one another. Such a preferred circuit is shown for example in the data sheet of the applicant RD sheet 66105, Figure 3 ge, whose basic circuit diagram for three consumers A, B, C is shown in Fig. 1, to which reference is already made here.

As shown in Fig. 1, for example supported by a regulating pump system hydraulic fluid stream is first passed to a first priority valve 2, which is biased in its basic position into a position in which the hydraulic fluid flow is passed to a second priority valve 4. In the basic position of the second priority valve 4 shown in FIG. 1, the consumer A, before it is drawn, is supplied with hydraulic fluid. The load pressure on the consumer is guided via a control line 6 to a control side of the second priority valve 4 , so that when the load pressure rises it is brought into a position in which the consumer B connected to the consumer A is supplied with hydraulic fluid. In this position, no hydraulic fluid is yet directed to consumer C with the lowest order.

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

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

By activating the first priority valve 2 and the second priority valve 4 with the load pressures on 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 be known preferred current circuit thus requires at least two consecutive priority valves for three consumers and thus requires considerable circuitry outlay, so that the preferred current circuit is relatively expensive to manufacture on the one hand and on the other hand requires considerable installation space.

The object of the invention is a preferred current to create circuit with minimal fixture tech a reasonable supply of the preferred guaranteed consumers of a machine.

This object is achieved by the features of patent claim 1 solved.

Due to the preferred current circuit according to the invention, a Device for supplying several consumers one Work machine provided, one of the Consumers prefer a braking system with a hydro memory that is supplied via a memory loading valve arrangement is controlled and being the control of another Consumer, such as a fan or the ways valves of an implement or another Priori titätsventils indirectly or directly via the Speicherla Deventilanordnung takes place, that of the hydraulic accumulator and the connected consumer, preferably the im Brake system not required hydraulic fluid flow to egg leads another consumer.

This measure makes it possible to arrange the accumulator charging valve assign a dual function, d. H. on the one hand the ver supply of the reservoir with pressure fluid and on the other hand the Supplying another consumer with the from the store hydraulic fluid flow not required. The store ladeven The valve arrangement essentially takes over the function a priority valve, so that the device tech African effort compared to conventional solutions can be reduced.

Let by the preferred current circuit according to the invention for example a braking system, a fan and the paths  Valves of a work machine with a priority valve and the accumulator loading valve arrangement required anyway perform so that a priority valve over conventional solutions can be saved.

Four are particularly advantageous in the subclaims 3 to 5 liable variants of the circuit according to the invention speaks.

Sub-claim 2 relates to an embodiment in which the accumulator charging valve with a first priority valve Hydraulic fluid is supplied so that the distribution on the two preferred consumers, for example the Bremssy stem and the fan over the accumulator valve assembly he follows.

In the alternative variant according to subclaim 3, the Accumulator charging valve arrangement also downstream of one arranged first priority valve over which the Hydrau likfluid one of the preferred consumers, for example the fan, is fed directly, and through which the of volume of hydraulic fluid not required by this consumer current is led to the accumulator charging valve arrangement which the other preferred consumer, for example that Braking system and then the downstream consumer ver are careful.

In the alternative embodiment according to subclaim 4 is a priority valve downstream of the storage tank charging tilanordnung provided, initially preferred over the Supply to the consumer provided with a memory he follows. The hydraulic fluid volume not required by this menstrom is led to the priority valve through which first the additional consumer and then the subsequent one switched consumers are available.  

While in the first two embodiments the consumer provided with the memory, d. H. for example always prefer the brake system with hydraulic fluid lumen flow has been supplied, is the last mentioned example a second consumer, at for example the fan and only then the storage charging valve arrangement and thus the one with the hydraulic accumulator Consumers, for example the braking system, are supplied. A such a division contradicts the conventional approach positions of operational security. By suitable ab coordination of the individual components, but can relatively easy to ensure that the Hydrospei cher is always sufficiently supplied with hydraulic fluid. The latter variant can be particularly advantageous if certain valve units are already in the modular system are present and the interconnection according to this variant with these elements with low investment costs is feasible.

Finally, an alternative embodiment is in sub-claim 5 Example explained in the parallel to the store valve a pressure control valve is switched, via which Fan motor can be supplied with hydraulic fluid, and wherein the accumulator loading valve assembly by the load pressure of the Fan is controlled, for example, the braking system and other downstream consumers with hydraulic fluid supply. Through the parallel connection of the pressure control tils and the accumulator loading valve arrangement is at corre Appropriate coordination of fan motor, hydraulic accumulator and pump a constant fan speed if sufficient guaranteed the boost pressure of the hydraulic accumulator.

A particularly simple storage charging valve arrangement You can get this with a 2-way proportional valve is designed as a pressure compensator, for example is switchable as a circulating pressure compensator, so that when exceeded supply of the desired storage pressure  downstream consumer via the 2-way proportional valve is done. Such accumulator loading valve arrangements are commonly used as an open center store drawer or print switching valve known.

The priority valve is also known per se Designed as a 2-way proportional valve, as with is described for example in DE-OS 38 21 115.

The preferred current circuit described above can be particularly ders advantageous in a work machine with a brake system, a fan and directional valves to control a Use work equipment, these three consumers ge according to one of the embodiments described above games are interconnected and this circuit a priority valve is connected upstream, so that a steering the machine preferred over the other Ver users with the hydraulic fluid volume flow from the pump pen system is available.

As already mentioned at the beginning, the system can be used with both a variable displacement pump with pressure flow control device can also be operated with a constant pump. In at In the cases, the Hy draulic fluid volume flow over the highest to the consumption (steering, braking system, fans, directional control valves, etc.) controlled load pressure.

Further preferred embodiments of the invention the explanations below using schematic drawings tert.

Show it:

Fig. 1 is a block circuit diagram of a conventional preferred current circuit;

Fig. 2 is a block diagram of a first game Ausführungsbei a preferred current scarf device;

FIG. 3 shows a specific embodiment of a circuit according to FIG. 2;

Fig. 4 is a block diagram of a second processing Ausführungsbei game according to the invention a preferred current switching;

FIG. 5 shows a concrete exemplary embodiment of a circuit according to FIG. 4;

Fig. 6 is a block diagram of a third processing Ausführungsbei game according to the invention a preferred current switching;

Fig. 7 shows a concrete embodiment of a circuit according to Fig. 6 and

Fig. 8 shows a concrete circuit of a fourth embodiment example of a preferred current circuit.

In Fig. 2 an embodiment of the preferred current circuit according to the invention is shown, in which three consumers, more precisely a braking system A, a fan B and Wegeven tile C of a work machine can be supplied with hydraulic fluid. The brake system A and the fan B should be supplied with preference over the directional valves C.

In the block diagram of FIG. 2, the pump arrangement and other consumers of the working machine hydraulic circuit are omitted for the sake of clarity. The scarf device has a first priority valve arrangement 12 , which is connected to the pump system via a pump working line (not shown in FIG. 2). The hydraulic fluid volumetric flow delivered by the pump is first led via the first priority valve arrangement 12 to the preferred consumers, ie the brake system A and the fan B ge. The brake system has an accumulator charging valve arrangement 14 , which is supplied with hydraulic fluid via the first priority valve arrangement 12 and via which a hydraulic accumulator 16 of the braking system can be loaded. In the supply line to the hydraulic accumulator 16 , a check valve 18 for preventing a backflow from the loaded hydraulic accumulator 16 and a fixed throttle 20 for setting the maximum storage charge hydraulic fluid volume flow is provided. The fan B is connected to another connection of the accumulator charging valve arrangement, the control of the system initially taking place in such a way that the hydraulic accumulator 16 can preferably be supplied with hydraulic fluid via the accumulator charging valve arrangement 14 . The hydraulic volume flow portion not required for charging the hydraulic accumulator 16 is branched off to the fan B, whereby it is ensured by the suitable coordination of the pump output, the output of the fan motor and the maximum accumulator hydraulic volume flow that the fan motor also operates during the charging process Hydraulic accumulator 16 is adequately supplied with hydraulic fluid, so that at any time a corresponding fan speed and thus the desired cooling capacity is available. The coordination 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.

The measure of supplying the fan with a sufficient hydraulic fluid volume flow at all times and choosing fans of engine load pressure and boost pressure of roughly the same order of magnitude ensures that the fan is adequately cooled even when the fan has a maximum power requirement. If the hydraulic accumulator 16 is charged accordingly and the fan motor also runs at its predetermined minimum speed, the hydraulic fluid volume flow which is not required is passed via the priority valve arrangement 12 to the downstream consumer, ie the directional control valves C. For Ansteue tion of the first priority valve assembly 12 , the hydraulic accumulator boost pressure and the load pressure on the fan motor B are guided to the two inputs of a shuttle valve, so that the larger of these two control pressures is guided to the control side of the priority valve assembly 12 . This circuit ensures that the downstream consumer C is only supplied when the boost pressure of the hydraulic accumulator and the load pressure on the fan motor have reached their predetermined minimum values.

In Fig. 3, a preferred current circuit of a wheel loader is shown, in which in addition to the three previously described United consumers: brake system A, fan B and directional control valves C, a steering system (not shown) is supplied with hydraulic fluid, this being compared to the other consumers A, B, C is preferred. That is, in this embodiment, the consumers A, B, C are switched downstream for steering.

The preferred flow circuit shown in Fig. 3 has a variable displacement pump 22 with a pressure-flow regulator (the individual components of the variable displacement pump 22 will be discussed in more detail below), through which hydraulic fluid is guided via a working line 24 to a second priority valve arrangement 26 , via the steering position shown in the slide is preferably supplied with hydraulic fluid bar. The hydraulic fluid volume flow not required by the steering is led via a pressure line 27 to a circuit part with the first priority valve arrangement 12 , which corresponds to the arrangement from FIG. 2.

In the position shown of the first Prioritätsventilanord voltage 12 , the hydraulic fluid via a working line 28 leads to the input of a storage charging valve arrangement 30 , the structure of which will be described in more detail below. A connection of the accumulator charging valve arrangement 30 is connected to the hydraulic accumulator 16 of a brake system 32 .

Another connection of the accumulator charging valve assembly 30 is connected to a working line 33 which leads to the fan assembly 34 , the fan motor 78 of which is driven by the hydraulic fluid volume flow.

A second output of the first priority valve arrangement 12 is connected via a working line 36 to a further downstream consumer 38 , which can include a plurality of directional valves, hydraulic cylinders, etc.

The variable displacement pump 22 comprises the actual variable displacement pump arrangement 40 of a known type, which is controlled by a pressure-feed current regulator 42 . This has a continuously adjustable flow control valve 44 , on the one side of which a control pressure is applied via a load pressure signaling line 45 to the load pressure of a consumer, and thereby the volume adjustment of the variable pump arrangement 40 is regulated such that a load pressure-independent volume flow flows to the consumer. Since in the present case a large number of consumers (steering, braking system 32 , fan arrangement 34 and further consumer 38 ) must be supplied, care must be taken to ensure that the largest load pressure prevailing at the aforementioned consumers is led to the flow control valve 44 . For this purpose, load pressure signaling lines of the individual consumers are connected cascade-like in a known manner via shuttle valves 48 to 50, so that the highest load pressure in each case is applied to the control side of the delivery flow control valve 44 .

If a preset maximum operating pressure is reached, the flow rate of the pump is limited via a pressure control valve 46 such that the preset maximum operating pressure is not exceeded. The system then works as a constant pressure system. A further description of the variable displacement pump 22 can be dispensed with at this point, since such a structure is known from the prior art.

The Prioritätsventilanordnun gene 12 , 24 used in the circuit have essentially the same structure, which will be described with reference to the priority valve for the second priority order 26 .

The priority valve arrangement 26 has a continuously adjustable 2-way valve 52 , also called a compensation valve, which is biased via a valve spring into a basic position in which the working line 24 is connected to a pressure line 54 leading to the steering. The load pressure in the pressure line 54 is guided via a control line 56 to the rear side of the 2-way valve 52 and via a control line 58 to the other control side of the 2-way valve. Nozzles are arranged in the control lines, via which the valve spool movement is to be damped. The nozzle located in the control line 58 can be bypassed via a bypass line, in which a check valve is arranged, which relieves the control side of the 2-way valve 52 and thus enables a faster actuating movement of the valve slide. In the control line 56 a pressure relief valve 60 is also 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, which are not provided for example in the first priority valve arrangement 12 .

If the pressure at the outlet of the priority valve arrangement, that is to say in the second priority valve arrangement 26 in the pressure line 54, increases, the valve slide of the 2-way valve 52 is moved out of its shown basic position and also a connection is established between the working line 24 and the pressure line 27 , so that hydraulic fluid is guided to the other consumers (brake system 32 , fan 34 , other consumers 38 ). In the present case, this means that the hydraulic fluid is guided to the input of the first priority arrangement 12 .

As already mentioned, the structure of the first priority valve arrangement 12 corresponds to that of the second priority arrangement 26 , the 2-way valve 52 'on its spring side being acted upon by a control line 56 ' with the pressure in the working line 28 and also having a throttle is provided in the controller 56 '. Furthermore, the pressure in the working line 28 via a Steuerlei device 58 'leads to the other control side of the 2-way valve 52 ge. That is, as soon as a predetermined pressure builds up in the working line 28 , the valve spool of the 2-way valve 52 is pressurized via the control pressure in the control line 58 ', so that the volume flow not required by the brake system 32 and the fan 34 towards the other consumers 38 is passed.

The brake charging system 32 associated with the storage charging valve arrangement 14 also has a structure which is known per se, as is used, for example, for charging a hydraulic accumulator with a constant pump. Accordingly, the SpeI cherladeventilanordnung 14 has a pressure compensator 62 , which is designed as ste tig adjustable 2-way valve. The pressure balance 62 is adjustable from a basic position in which the connection from the working line 28 to the pressure line 33 leading to the fan 34 is blocked, via the hydraulic fluid flow between the lines 28 and 66, throttling intermediate positions to an end position in which the connection to the fan 34 is fully turned on. From the working line 28 branches off a Speicherladelei device 68 , which leads to the brake system 32 and bypasses the pressure compensator 62 . In the storage charging line 68 , a fixed throttle 70 is provided, via which the maximum storage volume flow can be set. Furthermore, the accumulator charging line 68 has a check valve 72 , which only allows a hydraulic fluid flow towards the hydraulic accumulator 16 .

Between the check valve 72 and the fixed throttle 70 branches off from the accumulator charging line 68, a branch line which leads to a control valve 64, which is designed as a 2/2-way valve in the exemplary embodiment shown. In its spring-biased basic position, the fluid pressure prevailing in the accumulator charging line 68 downstream of the fixed throttle 70 leads via the control valve 64 and a control line 71 to the spring side of the pressure compensator 62 , while the prevailing pressure upstream of the fixed throttle 70 prevails in the accumulator charging line 68 to the other control side of the Pressure compensator is guided.

The pressure prevailing at the outlet of the control valve 64 is also leads to the two control sides of the control valve 64 . Furthermore, the control side of the control valve 64 removed from the spring-loaded control side is still acted upon via a control pressure line with the pressure prevailing downstream of the check valve 72 . When the pressure in this line section of the storage line 68 increases , the control valve 64 is moved into its other switching position, in which the control line 71 is connected to a tank T via a tank line 74 . That is, in the second switching position of the control valve 64 , the spring side of the pressure compensator 62 is relieved, so that the connection to the pressure line 33 is opened and the fan 34 is supplied with hydraulic fluid. This opening of the pressure compensator 62 takes place parallel to the loading of the hydraulic accumulator 16 , so that practically both consumers (here: braking system, fan) can be supplied with hydraulic fluid at the same time.

The brake system 32 includes the afore-execution for the hydraulic accumulator 16, which consists of two sub-memories 16 a and 16 b is associated with BR1 and BR2 in each case one of the brake circuits. The two hydraulic accumulators 16 a, 16 b are connected via a shuttle valve 74 to a Bremsventilanord voltage 76 , via which the hydraulic accumulators 16 a, 16 b can be connected to the brake circuits BR1 and BR2. The structure of the brake valve 76 is known per se, so that there is no description here and reference is made to the present literature.

A fan motor 78 is supplied with hydraulic fluid via the pressure line 33 . The control of the fan motor 78 takes place in the exemplary embodiment shown via a thermal valve arrangement 80 , which is arranged in a bypass line 82 to the fan motor 78 , which opens into the tank T, which is also connected to the output of the fan motor 78 . In the bypass line 82 , a fixed throttle 83 is provided for setting the bypass current. Via the thermoventilane arrangement 80 , the bypass volume flow can be set as a function of temperature via the bypass line 82 to the tank T, so that a corresponding dependency of the fan speed can be set.

As already explained in connection with FIG. 2, which shows the block diagram for the circuit mentioned above (except for the second priority valve arrangement 26 ), this exemplary embodiment first supplies the steering with hydraulic fluid as the preferred consumer and the hydraulic fluid volume flow to the first priority valve arrangement which is not required 12 and then forwarded to the Speicherladeven valve arrangement 14 , via which the hydraulic volume flow is divided among the other preferred consumers brake system 32 and fan 34 . Only when the three preferred consumers are adequately supplied with hydraulic fluid is the further consumers 38 actuated (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 use of the memory loading valve arrangement according to the invention, wherein a commercially available valve arrangement known in the art can be used for the storage valve arrangement 14 . However, this system has the disadvantage that when the vehicle is started up, the fan during charging of the hydraulic accumulators 16 a, 16 b runs at a comparatively high speed.

In order to overcome this disadvantage, the circuit shown in the following FIGS. 4 and 5 can be used, which again contains essentially the same components as the circuit from FIGS. 2 and 3.

Fig. 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 shown exemplary embodiments.

The hydraulic fluid volume flow not required by the steering is first led to the accumulator charging valve arrangement 14 , via which the control of the brake system A with the brake valve arrangement (not shown in FIG. 4) and the hydraulic accumulator 16 takes place. The maximum charging current of the hydraulic accumulator 16 is in turn limited by a fixed throttle 20 and a backflow through a check valve 18 is excluded. The unneeded from the brake valve A Hy draulikfluidvolumenstrom becomes the first priority valve arrangement led 12, which is thus in this Ausführungsbei game downstream of the accumulator charging valve arrangement 14 arranged. Via the first priority arrangement 12 , the hydraulic fluid volume flow is first divided into the fan B and then, when the load pressure at the fan B has become sufficiently high, the supply to the downstream further consumers C. To control the first priority valve arrangement 12 , the load pressure at the fan is B via a control line to the priority valve.

Fig. 5 shows a specific circuit associated with this embodiment for the consumers of a Arbeitsmaschi ne, the consumers in turn a steering, a brake system 32 , a fan 34 and other consumers, for example directional valves 38 are. The specific circuit again has a variable displacement pump 22 with a pressure flow regulator, with a corresponding cascade connection via shuttle valves 84 to 86 to ensure that the maximum load pressure present in the system is applied to the variable displacement pump 22 of the variable displacement pump. The hydraulic fluid volume flow conveyed by the variable displacement pump 22 is in turn guided to the second priority valve arrangement 26 , which is assigned to the steering circuit and from there to the storage loading valve arrangement 14 , via which the supply of the brake system 32 and - via the priority arrangement connected to the output of the storage loading valve arrangement 14 12 - the ventilation 34 and the other consumers 38 it follows. The structure of the individual components corresponds essentially to that of FIG. 3, so that a detailed description can be dispensed with. In this exemplary embodiment, the fan 34 is thus assigned its own pressure control valve, so that when the dimensions of the fan motor, storage charging current and Pumpenka capacity are correct, a constant fan speed is ensured even during the charging process of the hydraulic accumulator.

In FIGS. 6 and? Another embodiment of a preferred current circuit according to the invention is shown. In this variant, the hydraulic fluid volume flow not required by the steering is directed to the first priority arrangement 12 , with this supplying the fan B with hydraulic fluid being preferred. The unneeded hydraulic fluid volume flow is guided to the accumulator charging valve arrangement 14 , via which a preferred charging current is branched off to the hydraulic accumulator 16 of the braking system A, again a fixed throttle 20 and a check valve 18 to limit the maximum charging current or to prevent a backflow in the accumulator charging line are provided. The hydraulic fluid volume flow that is not required by the brake system A is directed via the accumulator charging valve arrangement 14 to the downstream consumers, for example directional control valves C.

As can be seen from the specific circuit according to FIG. 7, a hydraulic fluid volume flow is first led to the second priority valve arrangement 26 of the steering via the variable pump 22 and the hydraulic fluid volume flow not required by the latter is passed to the first priority valve arrangement 12 , via which the hydraulic fluid volume flow is divided to the fan 34 and to the accumulator valve assembly 14 . About the Speicherladeventilan order 14 , the hydraulic accumulator 16 a and 16 b of the brake system 32 and downstream the other United consumers, ie the directional control valves 38 are supplied.

This circuit contradicts conventional ideas of operational safety, since the fan is preferably supplied with hydraulic fluid practically over the brake system. By a suitable coordination and design of the fan motor, the accumulator charging current and the displacement pump capacity can be ensured at all times that the brake system is adequately supplied with hydraulic fluid so that the hydraulic accumulators 16 a, 16 b can be charged at any time. This variant offers the advantage that existing valve components can be used in a simple manner, if necessary, in a modular system, without modifications being necessary.

In FIG. 8 shows a further variant of the priority flow circuit of the invention is illustrated in which a pressure control valve is parallel to the cherladeventilanordnung SpeI connected 88 to the supply of the fan 34 12. That is, the hydraulic fluid volume flow conveyed by the variable displacement pump 22 and not required by the steering is guided via the second priority valve arrangement 26 to a node 90 , at which a line for connecting the pressure control valve 88 and a working line 92 are connected to one another. The latter is guided to the accumulator charging valve arrangement 14 , via which the hydraulic fluid volume flow is divided up to the brake system 32 and the directional control valves 38 .

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

The circuit section adjoining the working line 92 corresponds practically to that circuit section which connects to the first priority valve arrangement 12 according to FIG. 7, so that a further description can be dispensed with.

The pressure control valve 88 is designed as a continuously adjustable 3-way valve which can be actuated on a control side via an encoder which can be acted upon by the load pressure on the fan 34 . An output of the pressure control valve 88 is guided via a fan line 98 to the fan motor 78 of the fan 34 . From the fan line 98 branches a control line 100 , which is guided to the other control side of the pressure control valve 88 , so that it acts practically as a pressure reducing valve and regulates the pressure applied to the fan in proportion to the sensor pressure of the thermal valve 80 . A third port of the pressure control valve 88 is connected to the tank T.

In the event that the fan temperature is comparatively ge ring, the pressure control valve 88 is in a switch position in which the connection between the fan line 98 and the tank T is turned on. When the temperature rises, the speed of the fan 34 must also be increased so that the pressure control valve 88 is controlled via the transmitter such that the connection between the tank T and the fan line 98 is controlled and the fan line 98 is connected to the working line 27 via which the hydraulic fluid volume flow is directed from the second priority arrangement 26 towards the node 90 . That is, in the water position, the storage charge valve assembly 14 and the fan 34 are supplied in parallel with hydraulic fluid.

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

Due to the preferred current circuit according to the invention, a System provided that with minimal equipment technical effort to supply three consumptions cher, one of which is preferably a braking system with egg Hydraulic accumulator is enabled, the braking system and at least one other consumer about the Spei Cherladeventanordnung are controllable.

Claims (11)

1. Preferred current circuit for supplying several consumers of a working machine with hydraulic fluid from a hydraulic pump, 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 ge compared to other consumers with hydraulic fluid from egg Nem hydraulic accumulator can be supplied, to which a storage valve device arrangement is assigned, characterized in that the control of a further consumer ( 34 , 38 ) takes place via the storage charging valve arrangement ( 14 ), which supplies the hydraulic fluid flow not required by the first consumer ( 32 ) to the further consumer ( 34 , 38 ) forwards. 2. Preferred current circuit according to claim 1, characterized in that the accumulator charging valve arrangement ( 14 ) is arranged downstream of a first priority valve arrangement ( 12 ) via which a third consumer 838) can be supplied with hydraulic fluid if the supply of the preferred first and second consumers ( 32 , 34 ) via the accumulator charging valve arrangement ( 14 ) is guaranteed. 3. Preferred current circuit according to claim 1, characterized in that the accumulator charging valve arrangement ( 14 ) is arranged downstream of a first priority valve arrangement ( 12 ), via which a second consumer ( 34 ) can be supplied with the hydraulic fluid and via which the second consumer ( 34 ) Unneeded hydraulic fluid volume flow for supplying the first consumer ( 32 ) and a third consumer ( 38 ) to the accumulator charging valve arrangement ( 14 ) can be carried out. 4. Preferred current circuit according to claim 1, characterized in that downstream of the storage charging valve arrangement ( 14 ) a first priority valve arrangement ( 12 ) is provided, via which the second consumer ( 34 ) and a third consumer ( 38 ) can be supplied with hydraulic fluid and which the accumulator loading valve arrangement ( 14 ) can be supplied with the hydraulic fluid volume flow that is not required by the first consumer ( 32 ). 5. Preferred current circuit according to claim 1, characterized in that a pressure control valve ( 88 ) is connected in parallel with the accumulator charging valve arrangement ( 14 ), via which a fan motor ( 78 ) of a fan ( 34 ) can be supplied with hydraulic fluid and which depends on the fan load pressure a position connecting the fan line ( 98 ) to the fan ( 34 ) with a tank (T) can be brought into a position in which the fan line ( 98 ) is supplied with the hydraulic fluid, the fan load pressure also being used to control the accumulator charging valve arrangement ( 14 ) can be used in a position in which the third consumer ( 38 ) is acted upon by hydraulic fluid. 6. Preferred current circuit according to claims 1 to 4, characterized in that the storage charging valve arrangement ( 14 ) has a 2-way proportional valve as a pressure compensator ( 62 ), on the one hand with the system pressure applied to the storage charging system and on the other hand with the charging pressure of the hydraulic accumulator 16a, 16b is controlled so that it is interrupted when the pressure falls below a predetermined charge volume flow connect to the further consumer (34, 38) and that of the La devolumenstroms the fluid connection (34, 38) is openable upon exceeding to the further consumer. 7. Preferred current circuit characterized in that the priority valve arrangement has a 2-way proportional valve ( 52 ), via which, depending on the load pressure of a preferred consumer ( 32 , 34 ), a connection to the further consumer ( 38 ) can be opened. 8. Preferred flow circuit according to claims 1 to 7, characterized in that the priority valve arrangement ( 12 ) and the accumulator charging valve arrangement ( 14 ) is preceded by a second priority valve arrangement ( 26 ) via which the hydraulic fluid volume flow is guided to a steering system as the preferred consumer. 9. Preferred current circuit characterized in that the pump is a variable displacement pump ( 22 ) with a pressure-flow control device ( 44 , 46 ) which can be controlled as a function of the highest of the loads ( 32 , 34 , 38 ) at the consumers. 10. Preferred flow circuit according to claims 1 to 7, characterized in that the pump is a constant pump, the Hy draulikfluidvolumstrom given to the preferred flow circuit is adjustable by a pressure compensator which, depending on the highest of the consumers ( 32 , 34 , 38th ) applied excess pressure feeds an excess current back into a tank (T). 11. Preferred current circuit according to one of the preceding claims, characterized in that the first consumer cher a braking system ( 32 ) and the second consumer is a fan ( 34 ).