EP3012463A1 - Hydraulic assembly - Google Patents

Abstract

The invention relates to a hydraulic unit (1) having two pressure connections (2, 3) for supplying a plurality of devices (4, 5), in particular hydraulic rescue devices, comprising a first hydraulic circuit (8) having a first pump arrangement (12) and a first pressure connection ( 2) and a second hydraulic circuit (9) having a second pump arrangement (15) and a second pressure connection (3), the pump arrangements (12, 15) being driven simultaneously by a common drive (18), and by means of a first directional control valve (15). 26) of the first hydraulic circuit (8) with the second hydraulic circuit (9) is connectable and by means of a second directional control valve (28) of the second hydraulic circuit (9) with the first hydraulic circuit (8) is connectable. The directional control valves (26, 28) have a spring (30, 31) acting in the direction of a starting position, and a first control line (34) extends from the first hydraulic circuit (8) or the second hydraulic circuit (9) to the first directional control valve (26) A second control line (35) extends from the second hydraulic circuit (9) or from the first hydraulic circuit (8) to the second directional control valve (28).

Description

The invention relates to a hydraulic unit with at least two pressure connections according to the preamble of claim 1 and a method for demand-based supply of one or more hydraulically drivable devices with hydraulic fluid by means of a hydraulic unit according to the preamble of claim 13.

Hydraulic power units are already known from the prior art, to which one or more hydraulic devices can be connected, which are operated independently of each other and are also claimed with varying working resistances. For example, such hydraulic units are often used to drive hydraulic recovery equipment, especially with internal combustion engine drive, as they allow a mobile and independent use of such devices. Since only the device with the lower working resistance is driven in a simultaneous operation of two devices on a hydraulic circuit, each hydraulic connection has its own hydraulic circuit with its own pump associated with such hydraulic units. In order to make better use of the drive power of a hydraulic unit and for the purpose of increasing the operating speed of a driven device, it is known to redirect, by means of manual valves, the volume flow of a hydraulic circuit to which no or one inactive device is connected to a device used. These switching operations are usually carried out by a separate operator in coordination with the operators of the devices. In the case of scarce personnel resources, a separate operator for the hydraulic unit may not be available and must therefore dispense with the advantageous diversion of the volume flows which is advantageous in the intermittent operation of the devices.

The object of the invention is to avoid the disadvantages of the prior art and to provide a hydraulic unit with reduced operating costs

The object of the invention is achieved by a hydraulic unit with the features of claim 1.

Characterized in that the directional control valves have a spring acting in the direction of a starting position and from the first hydraulic circuit or the second hydraulic circuit, a first control line to a first directional control valve acting on the first actuator and from the second hydraulic circuit or from the first hydraulic circuit, a second control line to one on the second Directional valve acting second actuator extends, the demand-based bypassing hydraulic fluid from a hydraulic circuit to another hydraulic circuit without intervention of an operator is possible and thereby greatly facilitates the handling of such a hydraulic unit.

An embodiment is advantageous in which the first and / or the second control line is designed as a hydraulic control line and acts directly or by means of an actuating member in the form of a pilot valve on the second or first directional control valve. The switching operations can be triggered in a reliable manner, since the pressure in the individual hydraulic circuits provides clues for the respective operating state of a device.

Additionally or alternatively, it is possible that the first and / or second control line is designed as an electrical control line and by means of an electromagnetic actuator, in particular a magnetic coil, directly or via a pilot control element, e.g. Pilot valve acts on the second or first directional control valve. In this case, the operating state of the connected devices may be e.g. be actively selected or determined by arranged at these switches or sensors and used as a basis for switching operations. The switching signals can also be converted and processed using a logic circuit.

To use the hydraulic unit at different pressure levels, it is advantageous if the first pumping elements comprise at least one high pressure element with smaller flow and at least one low pressure element with a larger flow rate and the second pumping elements comprise at least one high pressure element with smaller flow and at least one low pressure element with larger flow and the Directional valves are arranged in the outgoing of the low-pressure elements fluid lines. When the pressure level in the connected devices increases, the volume flow supplied to them can be reduced and thus the required power to the maximum power of the drive be adjusted. The switching of the various pressure stages can, as known from the prior art by means of pressure-controlled directional control valves.

In order to achieve a high operating speed with low working resistance on the devices, it can be provided that the delivery rate of the low pressure elements of a hydraulic circuit is at least twice the delivery rate of the high pressure elements of the same hydraulic circuit. As a result, a high volume flow at the pressure connections can be made available at a low pressure level.

A possible embodiment of the hydraulic unit is that in the initial position of the directional control valves of these a flow path from the respective fluid line of a hydraulic circuit is open to the connection line to the other hydraulic circuit. In this case, by default, a volume flow of hydraulic fluid from one hydraulic circuit is diverted to another hydraulic circuit and this volume flow is brought back to a certain extent only when the pressure rises.

It can further be provided that the first connecting line extends from the first directional control valve to the second directional control valve and the second connecting line extends from the second directional control valve to the first directional control valve, wherein the second directional control valve has a flow path from the first connecting line in a first switching position to a second fluid line leading to the second pressure connection or can produce in a further switching position to the fluid container and the first directional control valve can produce a flow path from the second connecting line in a first switching position to a first fluid line leading to the first pressure port or in a further switching position to the fluid container. For the control of the fluid flows are thus further options available and the hydraulic unit can respond even better to the requirements of the devices.

In order to use the unneeded volume flow of another hydraulic circuit even at high pressure level in the hydraulic circuit of a working device, it can be provided that a hydraulic circuit comprises at least two high-pressure elements, of which at least one is connected via a fluid line directly to the pressure port and at least one via the directional control valve can be connected to another hydraulic circuit. In this design can both In the low-pressure range as well as in the high-pressure range, demand-oriented and performance-optimized allocation of the volume flows takes place.

Furthermore, it is possible to redirect the entire volume flow of a hydraulic circuit to another hydraulic circuit, when all first fluid lines by means of one or more first-way valves and by means of one or more first connecting lines or transition lines with at least one second fluid line of the second hydraulic circuit and / or all second fluid lines one or more second directional valves and by means of one or more second connecting lines or transition lines with at least one first fluid line of the first hydraulic circuit are connectable. The operating state or the pressure level of a device no longer supplied with hydraulic fluid can no longer be determined by simple means, e.g. a control line are detected by the hydraulic unit, therefore, other measures must be taken for resetting the volume flow diversion, e.g. a coordinated alternate operation of the equipment, but can also be done without its own operator for the hydraulic unit. One possibility for a changeover of the operating mode could be that a signal for the resetting of the volume flow diversion is generated by the device not supplied with hydraulic fluid by means of a switch and an electrical control line, whereby a simultaneous supply of both devices is again provided.

One way to achieve an operation with multiple pressure levels is that in one of the fluid lines of a hydraulic circuit downstream of a pumping element, a pressure changeover valve is arranged, which is driven via an outgoing from another fluid line of the same hydraulic circuit pressure control line, thereby increasing pressure in the other Fluid line from the pressure changeover valve, a flow path from the pumping element to the fluid container is made. The high pressure flow rate can be reduced as needed in a simple manner and the power of the drive can be optimally utilized.

Structurally advantageous and proven especially for mobile use pump arrangements arise when the first pumping elements and the second pumping elements are arranged to each other as in a radial piston pump.

Ensuring adequate oil supply to the pump assemblies is possible for a wide variety of applications when suction lines lead into the fluid container from the pumping elements. The shape and position of the fluid container is in this case largely arbitrary and can be operated with smaller quantities.

The object of the invention is also achieved by a method for supplying one or more hydraulically driven devices, in particular hydraulic rescue devices, with hydraulic fluid by means of a hydraulic unit with at least two pressure connections according to claim 13, wherein in a first hydraulic circuit with a first pump arrangement by means of first fluid lines Volume flows of at least two first pumping elements are combined and directed to a first pressure port and in a second hydraulic circuit with second pumping means by second fluid lines, the volume flows of at least two second pumping elements combined and passed to a second pressure port, wherein the first pumping elements and the second pumping elements be driven by a common drive at the same time and wherein, if necessary, the allocation of the volume flows to the pressure ports by means of a first directional valve at least one of first fluid lines via a first connecting line to a second fluid line in the second hydraulic circuit is connected and by means of a second directional valve at least one of the second fluid lines via a second connecting line to a first fluid line in the first hydraulic circuit is connected, characterized in that the directional control valves by means of a spring in a Are brought home position and a switching operation of the first directional control valve by a first actuator, which is driven by an emanating from the first hydraulic circuit or from the second hydraulic circuit and extending to the first actuator first control line is effected, and a switching operation of the second directional control valve by a second actuator, the is triggered by a second control line emanating from the second hydraulic circuit or from the first hydraulic circuit and extending to the second actuating member.

If two or more devices are activated in a hydraulic unit according to the invention, each of the devices is automatically supplied with about half or a corresponding proportion of the total delivery volume, with only one activated device this is approximately supplied to the total delivery volume.

For a better understanding of the invention, this will be explained in more detail with reference to the following figures.

Fig. 1

ein Hydraulikschema eines erfindungsgemäßen Hydraulikaggregats;

Fig. 2

ein Hydraulikschema einer weiteren Ausführungsform eines Hydraulikaggregats;

Fig. 3

ein Hydraulikschema einer weiteren Ausführungsform eines Hydraulikaggregats;

Fig. 4

ein Hydraulikschema einer weiteren Ausführungsform eines Hydraulikaggregats;

Fig. 5

ein Hydraulikschema einer weiteren Ausführungsform eines Hydraulikaggregats und

Fig. 6

ein Hydraulikschema einer weiteren Ausführungsform eines Hydraulikaggregats.

In each case, in a highly simplified, schematic representation:

Fig. 1

a hydraulic diagram of a hydraulic unit according to the invention;

Fig. 2

a hydraulic diagram of another embodiment of a hydraulic unit;

Fig. 3

a hydraulic diagram of another embodiment of a hydraulic unit;

Fig. 4

a hydraulic diagram of another embodiment of a hydraulic unit;

Fig. 5

a hydraulic diagram of another embodiment of a hydraulic unit and

Fig. 6

a hydraulic diagram of another embodiment of a hydraulic unit.

Fig. 1 shows a simplified and schematic diagram of a hydraulic unit 1 for demand-based supply of two or more hydraulically driven devices. The hydraulic unit 1 has for this purpose at least two pressure ports 2 and 3 and can on the in Fig. 1 Left pressure port 2, a first device 4, for example in the form of a mountain scissors, a spreading cylinder or a spreading device to be connected. In Fig. 1 is shown with dashed lines and a second device 5, which can be connected to the right-hand pressure port 3. The devices 4, 5 each have a fluid supply 6, through which the supplied from the pressure ports 2, 3 volume flow is supplied and further each have a fluid return 7, with which a volume flow is again supplied to the hydraulic unit 1. Details of the fluid return 7 to the devices 4, 5 and the hydraulic unit 1 are not shown or explained at this point, there are only simple return lines required. To control the volume flow of the devices 4, 5, these are equipped with 4/3-way valves, for example, with which in the basic position of the valve at idle circulation of the hydraulic fluid at low pressure level is possible and in the other valve positions two different directions of movement of the devices 4, 5 can be selected.

To supply the pressure ports 2, 3, the hydraulic unit 1 comprises two indicated by dotted lines hydraulic circuits 8 and 9, of which hydraulic fluid 10 removed from a fluid container 11 and the pressure ports 2, 3 is supplied. The first hydraulic circuit 8 comprises a first pump arrangement 12, which consists of at least two pumping elements 13 and 14. Analogously, the second hydraulic circuit 9 comprises a second pump arrangement 15 which comprises at least two pumping elements 16 and 17. The pumping elements 13, 14, 16, 17 are based on the displacement principle and can thereby build very high pressures, for example up to 1000 bar. Furthermore, the pumping elements 13, 14, 16, 17 and possibly further pumping elements may be part of a hydraulic pump in the form of a radial piston pump, axial piston pump or similar pump types with a plurality of displacement elements.

The pumping elements 13, 14 of the first pump arrangement 12 and the pumping elements 16, 17 of the second pumping arrangement 15 are driven by a common drive 18, wherein the drive 18 may comprise, for example, an electric motor. For a mobile use as drive and the use of an internal combustion engine 19 is advantageous because a large spatial independence of power sources is given. The volume flows generated by the first pumping elements 13 and 14 are guided via first fluid lines 20 and 21 to the first pressure port 2, wherein the at least two first fluid lines 20 and 21 can be combined in a first manifold 22 before the first pressure port 2. Analogously, the volume flows generated by the second pumping elements 16 and 17 are led via second fluid lines 23 and 24 to the second pressure port 3, wherein here, the second fluid lines 23 and 24 may be performed before the second pressure port 3 to a second manifold 25 together. The fluid lines 20, 21 and 23, 24 are shown in the form of arrows to illustrate the guided through them volume flows.

To simplify the illustration are in Fig. 1 no fluid lines shown, in which the hydraulic fluid 10 within the hydraulic circuits 8 or 9 or by the devices 4 or 5 is largely returned without pressure to the fluid container 11.

In principle, it is provided that the volumetric flow of the first pump arrangement 12, ie the first pumping elements 13 and 14, is provided at the first pressure connection 2 for the first device 4 and, analogously, at the second pressure connection 3 for the second device 5 the volumetric flow of the second pump arrangement 15, So the second pumping elements 16 and 17 is provided. If no device 4, 5 is connected to one of the pressure ports 2, 3, it must be ensured by measures known from the prior art that the volume flows generated by the pumping elements 13, 14, 16, 17 return to the fluid reservoir without damaging the hydraulic unit 1 11 are supplied. This can be, for example, a pressure relief valve arranged upstream of the pressure connections 2, 3, which is actuated manually and the volume flows are supplied to the pressure connections 2, 3 only after connection of a device 4 or 5.

The power converted in a hydraulic circuit 8 or 9 is proportional to the product of the size of the volume flow and the height of the fluid pressure. Since the power of the drive 18, for example, an internal combustion engine used in the hydraulic unit 1 19 is limited, and the adjustable at the pressure ports 2 and 3 available flow at a certain pressure is limited upwards. At low back pressure by the connected device 4 or 5, the volume flow is additionally limited by the highest drive speed of the drive 18, for example by the maximum speed of the engine 19, upwards. In practice, however, a largely constant drive speed can be assumed, for which reason a largely constant total delivery quantity is supplied by the pump arrangements 12, 15 and, adapted to the available drive power, they have to be divided into volume flows with different pressure levels.

From the prior art, it is known to provide a possibility in a generic hydraulic unit 1 to at least partially redirect the available in a hydraulic circuit 8 or 9 volume flow in the other hydraulic circuit 9 and 8, whereby the power of the drive 8 better utilized can be used and at a pressure port 2 or 3, a volume flow can be used, which exceeds the provided by the respective pump assembly 12 and 15 flow rate. In this way, if no volume flow is required at one of the pressure ports 2 or 3, since no device is connected or the device is in an inactive state, an increased volume flow can be made available at the other pressure port, whereby increased operating speeds or effective forces can be achieved with a device connected to it.

For this, if necessary, diversion of a volume flow from the first hydraulic circuit 8 to the second hydraulic circuit 9, the first hydraulic circuit 8 has a first directional valve 26, with which the first fluid line 21 can be connected via a first connecting line 27 to a second fluid line 24 in the second hydraulic circuit 9. Likewise, a second directional control valve 28 is arranged in the second hydraulic circuit 9 in a second fluid line 24, and the second fluidic line 24 can be connected to the first fluid line 21 via a second connecting line 29.

From the prior art, it is known to use directional control valves, which are operated manually and is required for the appropriate allocation of the volume flows each a manual switching operation. In practice, hydraulic units known from the prior art are handled in such a way that an operator working with a recovery device issues appropriate commands to an operator on the hydraulic unit. For the needs-based allocation of the flow rates to the devices therefore a separate operator is required in the prior art.

In a hydraulic unit 1 according to the invention no own operator is required for the demand-based allocation of the volume flows by the directional valves 26 and 28 perform automated switching operations.

For this purpose, the directional control valves 26, 28 have a spring 30, 31 acting in the direction of a starting position and further comprise an actuating member 32, 33 with which the volumetric flow either fed to the respective pressure port 2 or 3 or via the connecting line 27 and 29, respectively other hydraulic circuit 9 or 8 is redirected. The acting on the first directional control valve 26 first actuator 32 is controlled by a control line 34 which extends in the illustrated embodiment of the second hydraulic circuit 9 to the actuator 32 and acting on the second directional control valve 28 second actuator 33 is controlled via a control line 35, which extends in this embodiment from the first hydraulic circuit 8 to the actuator 33.

In the illustrated embodiment, the switching position of the directional control valve 30 is determined by the pressure prevailing in the second hydraulic circuit 9, since the control lines 34 and 35 are hydraulic control lines in which the pressure in a fluid line of the other hydraulic circuit to the actuator of the directional control valve the other hydraulic circuit is transmitted. With such a hydraulic unit 1, the volumetric flow provided at a pressure port 2 or 3 can be increased by the one pumping element 17 or 14 of the other hydraulic circuit 9 or 8, whereby the operating speed of a connected device 4 or 5 can be increased without that a manual adjustment of the directional valves 26, 28 would be required.

The control lines 34 and 35 may also be electrical control lines with which status information from the other hydraulic circuit 9 or 8, e.g. Pressure levels or switch positions on the devices 4, 5 are transmitted to the actuator 32 and 33 of the considered hydraulic circuit 8, 9 and the previously described switching operations can be effected.

For example, if connected to the hydraulic unit 1 device 4 is a hydraulically powered rescue cylinder, there are different operating conditions when it is used. At idle the rescue cylinder, the hydraulic fluid 10 can be performed at low pressure level to the switching valve of the rescue cylinder and from this back to the fluid tank 11. When retracting or extending the rescue ram without load prevails only a low resistance to work, which is due to the internal friction of the rescue ram and in line resistance and this entry or exit movement takes place at a relatively low pressure level of up to about 30 bar. This retraction or extension movement should be able to be performed with the highest possible speed for reasons of saving time and is therefore the provision of a large volume flow of advantage and can due to the relatively low pressure levels and the drive 18 to apply the necessary power.

For external load of the rescue ram this works against a higher working resistance and thereby increases the required fluid pressure and this must also be provided by the hydraulic unit 1. The pressure level typically increases up to 700 (1000) bar and has to be reduced due to the limited power of the drive 18 of the high pressure volume flow.

At the in Fig. 1 This can be done, for example, characterized in that at a pressure increase at the pressure port 2, only the volume flow of the first pumping element 13 is guided to the pressure port 2, while the flow rate of the pumping element 14 via a pressure-controlled valve, for example, at a switching pressure of 150 to 250 bar is returned to the fluid container 11. The pumping element 14 thereby requires only a comparatively small proportion of the drive power and a correspondingly higher proportion of the drive power for the pumping element 13, which must generate the high working pressure, is available.

In Fig. 1 is the initial position of the directional control valves 26 and 28, which is effected by the springs 30 and 31, such that the volume flow of the pumping elements 14 and 17 respectively in the respective hydraulic circuit 8, 9 remains and is thus fed to the pressure port 2 and 3 respectively. However, there are also different embodiments possible.

The control lines 34 and 35 may also be electrical control lines with which electrical signals are transmitted from the respective other hydraulic circuit or from a device connected thereto to the actuator of the relevant hydraulic circuit. Electrical control signals can be generated by switching elements on the connected device or by pressure-voltage converter in the hydraulic circuit.

The actuators 32, 33 may, for. B. as a control piston for hydraulic control lines 34, 35 or as solenoid valves for electrical control lines 34, 35 may be realized in corresponding directional control valves.

Fig. 2 shows a diagram of a further embodiment of a hydraulic unit 1 according to the invention, wherein the components already described in the reference to Fig. 1 described Embodiment according to the same reference numerals. and is largely dispensed repetitions of component descriptions.

The connectable to the hydraulic unit 1 device 4 is formed in the illustrated embodiment by a hydraulic recovery device 36 and includes a double-acting hydraulic cylinder in which a piston separates two working spaces within the hydraulic cylinder from each other. The direction of movement of the recovery device 36 depends on in which of the working spaces the hydraulic fluid 10 supplied through the fluid supply 6 is conducted by means of a switching valve 37. The displaced from the respective other working space hydraulic fluid 10 is returned via the fluid return 7 back to the hydraulic unit 1. When connected device 4 so the fluid circuit from the pressure port 2 via fluid supply 6, device 4 and fluid return 7 leads back to a return port 38 and return line 39 to the hydraulic unit 1 or directly back to the fluid container eleventh

In dashed lines, a second device 5 is indicated, which can also be connected to the hydraulic unit 1.

The drive 18, the pump assemblies 12 and 15 and the fluid lines 20, 21, 23, 24 and manifolds 22, 25 correspond to the basis of Fig. 1 described embodiment, however, the lines are in Fig. 2 represented by dashes and not, as in Fig. 1 , by block arrows.

The embodiment according to Fig. 2 differs from that in Fig. 1 in that the directional control valves 26 and 28 are pressed by the springs 30 and 31 into a starting position in which a flow path from the first fluid line 21 of the first hydraulic circuit 8 to the connecting line 27 to the other hydraulic circuit 9 is opened. In this embodiment, therefore, the volume flow delivered by the pumping element 14 is diverted in the starting position of the directional control valve 26 to the other hydraulic circuit 9. Similarly, in the second hydraulic circuit 9, the starting position of the directional control valve 28 is such that the volume flow delivered by the pumping element 17 is diverted to the first hydraulic circuit 8.

Since the pump arrangements 12 and 15 usually have identical delivery rates, this is "crossing" of volume flows between the two hydraulic circuits 8 and 9 without appreciable effect for the volume flows or pressures provided at the pressure ports 2 and 3, respectively.

The actuator 32, with which the first directional control valve 26 is switched against the action of the spring 30 from the starting position, in turn is addressed by a first control line 34, but in this embodiment, starting from the first hydraulic circuit 8 itself by the first fluid line 20, which leads from the pumping element 13 to the first pressure port 2.

By this embodiment, the first hydraulic circuit 8 gets at a pressure increase in the fluid line 20, so to speak, the redirected from the pumping element 14 to the second hydraulic circuit 9 volume flow back for their own needs. Likewise, the second hydraulic circuit 9 can retrieve the in the initial position of the second directional valve 28 to the first hydraulic circuit 8 diverted volumetric flow of the pumping element 17, if necessary, to its own pressure port 3.

As already explained, can be supplied with different pressure levels of the hydraulic fluid 10 with such a hydraulic unit 1, a device 4, 5 due to the predetermined power of the drive 18 at low pressure, a large volume flow and high pressure only a small volume flow can be provided. To make this possible, it can be provided to redirect individual pumping elements, for example the pumping elements 14 and / or 17, directly to the fluid container 11 when the pressure level in the working device rises by means of a valve, not shown, and thus to reduce the proportion of the high-pressure delivery rate.

Furthermore, it is possible that the pumping elements 13 and 14 of the pump arrangement 12 or the pumping elements 16 and 17 of the pump arrangement 15 have different sized delivery rates. At a certain drive intensity of the drive 18, for example a reference speed, it can be provided that the pumping element 14 has a larger delivery capacity than the pumping element 13 and thus is well suited for the supply with a large volume flow at a comparatively low pressure level, while the smaller pumping element 13 with its smaller capacity for the provision of a relatively small volume flow at high pressure level is optimally suited. About the design Such multi-stage pumps are referred to the related art in this regard.

An inventive hydraulic unit 1 has, for example, the following flow rates, which are dependent on the respective operating situation. As a reference intensity of the drive 18, for example, a speed of 3000 / min is assumed. The two pumping elements 13 and 16 of the hydraulic circuits 8, 9 have at this reference intensity a flow rate of, for example, in each case 0.7 l / min and have the pumping elements 14 and 17, for example, a flow rate of 2.0 l / min. The pumping elements 13 and 16 can thus be referred to as high-pressure elements 40 and 41, respectively, and the two larger pumping elements 14 and 17 can be referred to as low-pressure elements 42 and 43, respectively.

In one embodiment of the hydraulic unit according to Fig. 1 If two devices 4, 5 are connected to the pressure ports 2, 3, they are flowed through at idle at a pressure level of up to about 20 bar. As flow rate stands at the pressure port 2 of the delivered from the pump assembly 12 volume flow of a total of 2.7 l available. Likewise, the second device 5 is supplied by the pressure port 3 with a flow rate of 2.7 l / min.

If, for example, an adjustment movement is initiated at low resistance on the device 4, the pressure increases to over 20 bar, whereby a switching signal is sent via the control line 35 to the second directional control valve 28 and the volume flow of the pumping element 17 is diverted to the first hydraulic circuit 8 and thereby at the first pressure port 2, a flow rate of 4.7 l / min is available. This can, if only one device is activated, this achieve a much higher operating speed. If, for example, the device 5 is also activated with a low load resistance, a changeover signal is transmitted to the first directional control valve 26 via the control line 34 due to the increase in pressure in the second fluid line 23, the changeover being effected by the actuator 32. As a result, the volumetric flow delivered by the pumping element 14 is diverted to the second hydraulic circuit 9 and, in turn, in this operating state are available to the devices 4, 5, as in idling mode, in each case 2.7 l / min of flow rate. The raised Operating speed of the devices 4 and 5 can therefore always be used automatically when only one of the devices 4, 5 is actuated.

If a high resistance to operation occurs on a device 4, the volume flow delivered by the pumping element 14 by means of an in Fig. 2 Not shown valve diverted to the fluid tank 11 and the drive power of the drive 18 is for the most part for the first pumping element 13 is available with which at the reference speed of 3000 / min, a flow rate of 0.7 l / min at the pressure port 2 are provided can. The pressure level is approximately between the switching pressure of less than 250 bar, at the exceeding of which the volume flow of the pumping element 14 is switched off and the limited by a pressure relief valve system pressure of about 750 to 1000 bar.

The great advantage of the hydraulic unit 1 according to the invention is that these switching operations for the demand-oriented allocation of the volume flows to the pressure ports 2 and / or 3 need not be performed by an operator, but due to the directional valves 26, 28th

At the in Fig. 2 illustrated embodiment, the device 4 is supplied from the pressure port 2 at idle with a flow rate of 2.7 l / min, which consists of a partial amount of 0.7 l / min from the high pressure element 40 of the first hydraulic circuit 8 and a subset of 2.0 l / min composed of the low pressure element 43 of the second hydraulic circuit. With a pressure increase by activating the device 4 with low resistance to work, the volume flow of the low-pressure element 42 is additionally conducted at a delivery rate of 2.0 l / min to the pressure port 2, which then in total 4.7 l / min are available, if no flow for a second device 5 is required.

In Fig. 1 and 2 are known from the prior art measures that allow a two-stage printing operation, for example, pressure relief valves, throttle valves, check valves, etc. are not shown or described in detail.

In Fig. 3 is a further and optionally independent embodiment of a hydraulic unit 1 shown schematically, again for like parts, the same reference numerals or component designations as in the preceding Fig. 1 and 2 be used. In order to avoid unnecessary repetition, the description in the previous Fig. 1 and 2 referred or referred.

In this embodiment, the outgoing from the first hydraulic circuit 8 at the first directional control valve 26 connecting line 27 to the second directional control valve 28 and is delivered in this the supplied via the connecting line 27 volume flow depending on the switching position of the directional valve 28 either via a return line 39 into the fluid tank 11 or via a Flow path in the directional control valve 28 with the volume flow delivered by the second pump element 17 in the second fluid line 24 and provided in sequence via the second manifold 25 at the second pressure port 3.

Similarly, the outgoing from the second hydraulic circuit 9 at the second directional control valve 28 connecting line 29 to the first directional control valve in the first hydraulic circuit 8 and we supplied via the connecting line 29 volume flow depending on the switching position of the valve 26 either via a return line 39 to the fluid tank 11 or supplied with the from Summed pumping 14 delivered volume flow and provided in sequence via the manifold 22 at the first pressure port 2.

In addition, as shown, check valves 44 may be provided in the connection lines 27, 29 to prevent undesired flow direction reversal or pressure propagation in an undesired direction.

Also in the pumping elements 14 and 17, which are provided as low-pressure elements 42 and 43 with the symbol ND, check valves 44 may be provided in the outgoing of these fluid lines 21 and 24. Furthermore, in the fluid lines between the directional control valves 26, 28 and the pressure ports 2, 3 also each a check valve 44 may be provided to take place at an increase in the pressure level at the pressure ports 2, 3 no pressure propagation in the low pressure region.

The pumping elements 13, 14, 16, 17 in Fig. 3 are, as already based on Fig. 1 and 2 described, provided with a drive, not shown, with which the pumping elements are driven simultaneously. To adapt the provided at the pressure ports 2, 3 Flow rates is provided in the first hydraulic circuit 8, a pressure changeover valve 45, with which the volume flow delivered by the pumping element 14, that is a low pressure element 42, when a switching pressure is exceeded is no longer passed to the pressure port 2, but into the fluid container 11. The switching of the pressure changeover valve 45 is effected via an outgoing from the first fluid line 20 control line 46, with which the pressure prevailing at the pressure port 2 fluid pressure is passed to the pressure changeover valve 45 and this triggers a switching operation by means of an actuator, not shown, when due to an increasing pressure in the Control line 46, a spring 47 causing the starting position of the pressure switching valve 45 is overcome.

In the second hydraulic circuit 9, a pressure changeover valve 48 is analogously provided, with which the volume flow delivered by the second pumping element 17 is no longer passed to the second pressure port 3, but into the fluid container 11 when a limiting pressure is exceeded. A control line 49 effecting the switchover acts on the pressure level existing between the second pumping element 16, that is to say the high pressure element 41 and the second pressure connection 3, and causes the volume flow of the pumping element 17 to be conveyed to the fluid reservoir 11 when a restoring force caused by a spring 50 is exceeded. The power of the drive is thus in these cases for the greater part for the drive of the high pressure elements 40 and 41 available and can be overcome with the connected devices 4, 5 and high Arbeitswiederstände.

To protect the hydraulic unit 1 may further be provided that each hydraulic circuit 8, 9 is provided with a pressure relief valve 51 which limits the maximum pressure provided at the pressure ports 2 and 3 and the maximum pressure is set such that bursting of components of the hydraulic unit. 1 is avoided. As maximum pressure, for example, an upper limit of 750 to 1000 bar is set.

The operation of the directional control valves 26, 28 corresponds to Fig. 3 essentially those of Fig. 2 illustrated embodiment, since here in the initial position of the pumping element 14, 15 supplied flow to the other hydraulic circuit is passed and at a switching operation of the directional control valve 26 and 28 due to an increasing pressure in the control line 34 and 35 of the flow again in each considered Hydraulic circuit 8 and 9 is retrieved and directed to the respective pressure port 2 and 3 respectively.

In the illustrated embodiment, both directional control valves 26 and 28 are shown in the initial position and is returned directly from the valve of the other hydraulic circuit 9 and 8 diverted volume flow via a return line 39 substantially without pressure in the fluid container 11. If, for example, a device 4 is actuated at the pressure port 2 and the fluid pressure rises as a result, a switching process of the directional valve 26 is effected via the control line 34 and the volume flows of the pumping elements 13, 14 and 17 are supplied to the pressure port 2 in this case. This means an increased operating speed of a device 4 compared to a supply by only one hydraulic circuit 8 alone.

If an increase in pressure is effected at both pressure ports 2 and 3 by actuation of a connected device 4 or 5, hydraulic fluid is no longer transmitted via the connecting lines 27 and 29 and each pressure port 2, 3 is supplied by the associated hydraulic circuit 8, 9 alone.

In Fig. 4 is a further and possibly independent embodiment of a hydraulic unit 1 is shown, again for like parts, the same reference numerals or component names as in the preceding Fig. 1 to 3 be used. In order to avoid unnecessary repetition, the detailed description in the previous ones will be used Fig. 1 to 3 referred or referred.

The hydraulic unit 1 according to Fig. 4 differs from the embodiment in Fig. 3 in the integration of the directional control valves 26 and 28, in which in the initial position caused by the springs 30 and 31, the volume flows supplied by the pumping elements 14 and 17 are provided within the own hydraulic circuit 8 and 9 at the respective pressure port 2 and 3 respectively and only at pressure increase in the other hydraulic circuit 9 and 8, a diversion of a flow occurs. The actuators that are activated by the control lines 34 and 35 are in Fig. 4 not shown for reasons of space.

Fig. 4 further shows that optionally in the hydraulic circuits 8 and 9 in each case before the pressure ports 2 and 3, pressure relief valves 52 may be provided with which a largely unpressurized return of hydraulic fluid to the fluid container 11 are produced can, in the event that no device is connected to the respective pressure port 2 or 3. These can also be used in other embodiments of the hydraulic unit 1 pressure relief valves 52 may be manually operated or else part of a clutch system, in which in a coupling operation both the fluid supply 6 and the fluid return 7 of the device (see Fig. 1 ) get connected. The pressure relief valve 52 may be formed in this case as a by-pass valve in the pressure port 2 and 3, respectively.

In Fig. 4 is further shown that the pump elements 14, 17, which may be formed as low pressure elements 42 and 43, respectively, a pressure relief valve (DBV) 53 may be downstream, which then becomes effective in the illustrated embodiment, when the hydraulic fluid from the directional control valves 26 and 28 respectively is redirected to the other hydraulic circuit 9 and 8 respectively and in this due to a high resistance to high pressure fluid is present. The volume flow of the pumping elements 42 and 43 can be derived in this case via the pressure relief valve 53 into the fluid container 11. As a limit pressure, from which a pressure relief valve 53 opens, a pressure is selected which corresponds to the switching pressure of the pressure changeover valves 45 and 48, since from this pressure level, the volume flows of the low pressure elements 42, 43 are no longer directed to the pressure ports 2 and 3 respectively. A pressure limiting valve 53 can structurally correspond to the pressure changeover valves 45, 48.

In Fig. 5 is a further and possibly independent embodiment of a hydraulic unit 1 is shown, again for like parts, the same reference numerals or component names as in the preceding Fig. 1 to 4 be used. In order to avoid unnecessary repetition, the detailed description in the preceding is preceded Fig. 1 to 4 referred or referred.

In this embodiment, the operation of the directional control valves 26 and 28 as in the reference to Fig. 3 described embodiment, and is bypassed by a hydraulic circuit 8, in which no device is connected to the pressure port 2 or the connected device is in idle, a part of the volume flow to the other hydraulic circuit 9. The leading to the directional control valve 26 first fluid line 21 leads in this embodiment, not only the volume flow of the pumping element 14, but also the flow of a further pumping element 54 and can be redirected via the directional control valve 26 to the other hydraulic circuit 9 become. While the pumping element 14 is designed as a low-pressure element 42 having a comparatively high delivery rate, the pumping element 54 is designed as a high-pressure element 55, which has a comparatively small delivery rate. In the illustrated position of the directional control valve 26, both volume flows of the pumping elements 14 and 54 are thus diverted via the first connecting line 27 to the second hydraulic circuit 9. If no increased volume flow is required in this, since the connected device is idling, this redirected flow is discharged via the return line 39 to the fluid tank 11. At a pressure increase in the second hydraulic circuit 9, this volume flow is conducted to the second pressure port 3, since the second directional control valve 28 is switched via the control line 35 of the second hydraulic circuit. At the pressure port 3, the delivery rate of the second hydraulic circuit 9 is thus increased by the delivery rate of the pumping elements 14 and 54. In a further increase in pressure in the second hydraulic circuit 9, which causes a transition to the high-pressure region, the volume flow of the pumping element 14, which is yes designed as a low pressure element 42, via the pressure switching valve 45 is discharged directly into the fluid container 11 and only the volume flow of the pumping element 54, which is designed as a high pressure element 55, redirected to the second hydraulic circuit 9. Thus, even in high-pressure operation at the second pressure port 3 of the hydraulic circuit 9, a flow rate increased by the volume flow of the high-pressure element 55 is available.

Similarly, in the second hydraulic circuit 9, an additional pumping element 56 is arranged, which is designed as a high pressure element 57 and the provided at the pressure port 2 of the first hydraulic circuit 8 volume flow to the delivery of this high pressure element 57 and optionally also to the flow of the low pressure element 43 in the second hydraulic circuit 9 are increased. By this embodiment, in which even at high working resistance and high pressure level, a flow from the non-active hydraulic circuit to the other hydraulic circuit can be redirected, the power of the drive 18 can be optimally utilized even at high load resistance and the operating speed of a device can be maximized even at high resistance ,

The control of the pressure changeover valves 45 and 48 takes place via control lines 46 and 49 with the fluid pressure acting on the high-pressure elements 55 and 57, respectively.

In Fig. 6 is a further and possibly independent embodiment of a hydraulic unit 1 is shown, again for like parts, the same reference numerals or component names as in the preceding Fig. 1 to 5 be used. In order to avoid unnecessary repetition, the detailed description in the preceding is preceded Fig. 1 to 5 referred or referred.

In this embodiment of the hydraulic unit 1, the volume flow provided at a pressure connection can, if required, be increased by the delivery rate of all pumping elements of another hydraulic circuit.

In the embodiment according to Fig. 6 For example, the volume flow of the pumping elements 13 and 14 can be diverted via the path element 26 to the second hydraulic circuit 9, wherein the control of the volume flow of the pumping element 14, which may be designed as a low pressure element 42, as is done with reference to the preceding embodiments. To divert the volume flow of the pumping element 13, which is designed as a high-pressure element 40, is arranged in the first fluid line 20 shut-off valve 58 and an outgoing between the pumping element 13 and shut-off valve 58 and the other first fluid line 21 leading transition line 59. The shut-off valve 58 is in his open position caused by a spring 60 and the volume flow of the pumping element 13 can reach the pressure port 2 of the first hydraulic circuit 8. A shut-off of the shut-off valve 58 by means of a control line 61, which leads from the second fluid line 23 in the second hydraulic circuit 9 to the shut-off valve 58. With a pressure increase in the second hydraulic circuit 9, therefore, the first fluid line 20 is shut off from the pumping element 13 to the pressure port 2 and the volume flow of the pumping element 13 via the transition line 59 to the directional control valve 26, from which it passes through the first connecting line 27 to the second hydraulic circuit 9 in a row , By an analogous design of the second hydraulic circuit 9 with a shut-off valve 62, a transition line 63 and a spring 64, the volume flow of the pumping element 16 can be redirected to the first hydraulic circuit 8 in analogy.

In this way, the volume flows of other unillustrated pumping elements can be requested from each other hydraulic circuit and thereby automatically increased the provided at the respective pressure port flow rate.

Due to the fact that both hydraulic circuits 8 and 9 have such a transition function or diversion function in the exemplary embodiment shown, only the hydraulic circuit that requests the volume flows of the other pump elements in time before the other hydraulic circuit can provide the increased flow rate at the pressure port. The activation of the shut-off valves 58, 62 takes place at a pressure below about 25 bar, which is at non-actuated devices, ie in idle mode, the required base pressure available at both pressure connections and the previously activated device gets the volume flow of all pumping elements available.

In the transition lines 59 and 60 are further advantageously throttle elements 65 and 66 respectively arranged, with which in the first fluid line 20 and the second fluid line 23, a back pressure is built up for the optionally required control of the directional valves 26, 28 and the shut-off valves 58th , 62 serves.

The hydraulic fluid 10 advantageously passes via suction lines from the fluid container 11 to the pumping elements.

The embodiments show possible embodiments of the hydraulic unit 1, wherein it should be noted at this point that the invention is not limited to the specifically illustrated embodiments thereof, but rather also various combinations of the individual embodiments are possible with each other and this possibility of variation due to the teaching of technical action representational invention in the skill of those skilled in this technical field.

Furthermore, individual features or combinations of features from the different exemplary embodiments shown and described can also represent independent, inventive or inventive solutions.

The task underlying the independent inventive solutions can be taken from the description.

All statements of value ranges in the present description should be understood to include any and all sub-ranges thereof, e.g. is the statement 1 to 10 to be understood that all sub-areas, starting from the lower limit 1 and the upper limit 10 are included, ie. all sub-areas begin with a lower limit of 1 or greater and end at an upper limit of 10 or less, e.g. 1 to 1.7, or 3.2 to 8.1, or 5.5 to 10.

Finally, it should be noted that in the differently described embodiments, the same parts are provided with the same reference numerals and the same component names, the disclosures contained throughout the description can be mutatis mutandis to the same parts with the same reference numerals or identical component names. Also, the location information chosen in the description, such as top, bottom, side, etc. related to the immediately described and illustrated figure and these position information in a change in position mutatis mutandis to transfer to the new location.

Above all, the individual in the Fig. 1 ; 2 ; 3 ; 4 ; 5 ; 6 shown embodiments form the subject of independent solutions according to the invention. The relevant objects and solutions according to the invention can be found in the detailed descriptions of these figures.

For the sake of order, it should finally be pointed out that for a better understanding of the structure of the hydraulic unit 1, this or its components have been shown partially unevenly and / or enlarged and / or reduced in size. <B> Reference Numbers </ b> 1 hydraulic power unit 31 feather 2 pressure connection 32 actuator 3 pressure connection 33 actuator 4 device 34 control line 5 device 35 control line 6 fluid supply 36 recovery equipment 7 Fluid return 37 switching valve 8th hydraulic circuit 38 Return connection 9 hydraulic circuit 39 Return line 10 hydraulic fluid 40 High-pressure element 11 fluid container 41 High-pressure element 12 pump assembly 42 Low pressure element 13 pumping element 43 Low pressure element 14 pumping element 44 check valve 15 pump assembly 45 pressure changeover 16 pumping element 46 control line 17 pumping element 47 feather 18 drive 48 pressure changeover 19 internal combustion engine 49 control line 20 First fluid line 50 feather 21 First fluid line 51 Pressure relief valve 22 First manifold 52 Pressure relief valve 23 Second fluid line 53 Pressure relief valve 24 Second fluid line 54 pumping element 25 Second bus 55 High-pressure element 26 First way valve 56 pumping element 27 First connection line 57 High-pressure element 28 Second way valve 58 shut-off valve 29 Second connection line 59 Transition management 30 feather 60 feather 61 control line 62 shut-off valve 63 Transition management 64 feather 65 throttle element 66 throttle element

Claims (13)

Hydraulic unit (1) with at least two pressure connections (2, 3) for the demand-oriented supply of one or more hydraulically drivable devices (4, 5), in particular hydraulic rescue devices, with hydraulic fluid (10) from a fluid container (11), comprising a first hydraulic circuit ( 8) with a first pump arrangement (12) comprising at least two first pump elements (13, 14), of which first fluid lines (20, 21) lead to a first pressure connection (2), at least one second hydraulic circuit (9) having a second pump arrangement (15 ) of at least two second pump elements (16, 17) of which second fluid conduits (23, 24) lead to a second pressure port (3), wherein the first pumping elements (13, 14) and the second pumping elements (16, 17) simultaneously from a at least one of the first fluid lines (21) via a first connecting line (27) with a second Fluidlei (24) in the second hydraulic circuit (9) connectable and by means of a second directional valve (28) at least one of the second fluid lines (24) via a second connecting line (29) with a first fluid line (21) in the first hydraulic circuit (8) is connectable characterized in that the directional control valves (26, 28) have a spring (30, 31) acting in the direction of a starting position and from the first hydraulic circuit (8) or the second hydraulic circuit (9) to a first control line (34) to one on the first directional control valve (26) acting first actuating member (32) extends and from the second hydraulic circuit (9) or from the first hydraulic circuit (8) a second control line (35) to a second directional valve (28) acting second actuating member (33). Hydraulic unit (1) according to claim 1, characterized in that the first and / or second control line (34, 35) is designed as a hydraulic control line and acts directly or by means of a pilot valve on the second or first directional control valve (28, 26). Hydraulic unit (1) according to claim 1, characterized in that the first and / or second control line (34, 35) is designed as an electrical control line and by means of an electromagnetic actuator directly or with pilot control member on the second directional control valve or first directional control valve (28, 26 ) acts. Hydraulic unit (1) according to one of claims 1 to 3, characterized in that the first pumping elements (13, 14) at least one high pressure element (40) with a smaller flow rate at a reference intensity of the drive (18) and at least one low pressure element (42) with larger Delivery amount comprise at the reference intensity and the second pumping elements (16, 17) at least one high pressure element (41) with smaller flow and at least one low pressure element (43) with a larger flow rate and the directional control valves (26, 28) in the of the low pressure elements (42, 43) outgoing fluid lines (21, 24) are arranged. Hydraulic unit (1) according to claim 4, characterized in that the delivery rate of the low pressure elements (42, 43) of a hydraulic circuit (8, 9) at least twice the delivery rate of the high pressure elements (40, 41) of the same hydraulic circuit (8, 9). Hydraulic unit (1) according to one of claims 1 to 5, characterized in that in the starting position of the directional control valves (26, 28) of these a flow path from the respective fluid line (21, 24) of the one hydraulic circuit (8, 9) to the connecting line (27 , 29) to the other hydraulic circuit (9, 8) is opened. Hydraulic unit (1) according to one of claims 1 to 6, characterized in that the first connecting line (27) from the first directional control valve (26) to the second directional control valve (28) and the second connecting line (29) from the second directional control valve (28) to the first Directional control valve (26) extends, wherein the second directional control valve (28) a flow path from the first connecting line (27) in a first switching position to a second pressure port (3) leading second fluid line (24) and in a further switching position to the fluid container (11) and the first directional control valve (26) can establish a flow path from the second connecting line (29) in a first switching position to a first fluid line (21) leading to the first pressure port (2) and to the fluid reservoir (11) in a further switching position Hydraulic unit (1) according to claim 7, characterized in that a hydraulic circuit (8) comprises at least two high-pressure elements (40, 55), of which at least one is connected via a fluid line (20) directly to the pressure port (2) and at least one via the directional control valve (26) with another hydraulic circuit (9) is connectable. Hydraulic unit (1) according to one of claims 1 to 8, characterized in that all the first fluid lines (21, 22) by means of one or more first directional valves (26) and by means of one or more first connecting lines (27, 59) with at least one second fluid line (23, 24) of the second hydraulic circuit (9) and / or all second fluid lines (23, 24) by means of one or more second directional control valves (28) and by means of one or more second connecting lines (29, 63) with at least one first fluid line (20 , 21) of the first hydraulic circuit (8) are connectable. Hydraulic unit (1) according to one of claims 1 to 9, characterized in that in one of the fluid lines (21) of a hydraulic circuit (8) following a pump element (14) a pressure changeover valve (45) is arranged, which via one of a other fluid line (20) of the same hydraulic circuit (8) outgoing pressure control line (46) is driven, whereby a pressure increase in the other fluid line (20) from the pressure changeover valve (45) a flow path from the pumping element (14) to the fluid container (11) is produced. Hydraulic unit (1) according to one of claims 1 to 10, characterized in that the first pumping elements (13, 14) and the second pumping elements (16, 17) are arranged to each other as in a radial piston pump. Hydraulic unit (1) according to any one of claims 1 to 11, characterized in that of the pumping elements (13, 14, 16, 17, 40, 41, 42, 43, 54, 55, 56, 57) suction lines in the fluid container ( 11). Method for supplying at least two hydraulically drivable devices (4, 5), in particular hydraulic rescue devices, with hydraulic fluid (10) by means of a hydraulic unit (1) with at least two pressure connections (2, 3), in which in a first hydraulic circuit (8) with a first pump arrangement (12) by means of first fluid lines (20, 21) volume flows of at least two first pump elements (13, 14) summarized and passed to a first pressure port (2) and in a second hydraulic circuit (9) with a second pump assembly (15) by means of second fluid lines (23, 24) summarizes the volume flows of at least two second pumping elements (16, 17) and to a second pressure port (3) are passed, wherein the first pumping elements (13, 14) and the second pumping elements (16, 17) are driven simultaneously by a common drive (18) and wherein as required allocation of the volume flows to the pressure ports (2, 3 ) is connected by means of a first directional valve (26) at least one of the first fluid lines (21) via a first connecting line (27) with a second fluid line (24) in the second hydraulic circuit (9) and by means of a second directional valve (28) at least one of the second Fluid lines (24) via a second connecting line (29) with a first fluid line (21) in the first hydraulic circuit (8) is connected, characterized gekennzei Chnet that the directional control valves (26, 28) by means of a spring (30, 31) are moved to an initial position and a switching operation of the first directional control valve (26) by a first actuator (32) of one of the first hydraulic circuit (8) or is effected, and a switching operation of the second directional control valve (28) by a second actuator (33) from one of the second hydraulic circuit (9) and the first actuator (32) extending first control line (34) is driven 9) or from the first hydraulic circuit (8) outgoing and to the second actuating member (33) extending second control line (35) is actuated, is effected.

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