EP3012463B1 - Hydraulic assembly - Google Patents

Description

The invention relates to a hydraulic unit with at least two pressure connections according to the preamble of claim 1.

Hydraulic units are already known from the prior art, to which one or more hydraulic devices can be connected, which are operated independently of one another and are also stressed with changing load resistances. For example, hydraulic units of this type are often used to drive hydraulic recovery devices, in particular with an internal combustion engine drive, since they allow mobile and independent use of such devices. Since, when two devices are operated simultaneously on one hydraulic circuit, only the device with the lower working resistance is driven, each pressure connection is assigned a separate hydraulic circuit with its own pump in such hydraulic units. In order to better utilize the drive power of a hydraulic unit and for the purpose of increasing the operating speed of a driven device, it is known to divert the volume flow of a hydraulic circuit, to which no or an inactive device is connected, to a device in use by means of manual valves. These switching processes are usually carried out by a dedicated operator in coordination with the operators of the devices. If human resources are scarce, a dedicated operator for the hydraulic unit may not be available and therefore the need-based diversion of the volume flows, which is advantageous when the devices are in intermittent operation, must be dispensed with.

The JP H1061608 A discloses a hydraulic system in which two hydraulic circuits are driven by a common drive motor. The first hydraulic circuit comprises a first variable displacement pump and a pressure line branching out from the variable displacement pump. Two consumers are connected to this pressure line via a directional valve each. Analogously to this, the second hydraulic circuit comprises a second variable displacement pump and a pressure line outgoing from the variable displacement pump. Two consumers are connected to this pressure line via a directional valve each. Depending on the pressure conditions in the first and second hydraulic circuit, connecting lines can be opened, whereby partial flows of the Volume flow branched off in the pressure lines and can be led to the other pressure line.

The object of the invention is to avoid the disadvantages of the prior art and to provide a hydraulic unit with reduced operating effort. The object of the invention is achieved by a hydraulic unit with the features of claim 1.

Because the directional control valves have a spring acting in the direction of a starting position and a first control line runs from the first hydraulic circuit or from the second hydraulic circuit to a first actuating element acting on the first directional control valve and a second control line runs from the second hydraulic circuit or from the first hydraulic circuit to one to the second Directional control valve acting second actuating member runs, the needs-based diversion of hydraulic fluid from one hydraulic circuit to a further hydraulic circuit without intervention of an operator is possible and thus the handling of such a hydraulic unit is much easier.

To use the hydraulic unit at different pressure levels, the invention provides that the first pump elements comprise at least one high pressure element with a smaller delivery rate and at least one low pressure element with a larger delivery rate and the second pump elements comprise at least one high pressure element with a smaller delivery rate and at least one low pressure element with a larger delivery rate and the directional control valves are arranged in the fluid lines going out from the low-pressure elements. If the pressure level rises in the connected devices, the volume flow supplied to them can be reduced and thus the required power can be adapted to the maximum power of the drive. As is known from the prior art, the switching over of the various pressure levels can take place by means of pressure-controlled directional control valves.

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

Additionally or alternatively, it is possible for the first and / or second control line to be designed as an electrical control line and to be operated 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 status of the connected devices can e.g. are actively selected or determined by switches or sensors arranged on them and used as a basis for switching processes. The switching signals can also be converted and further processed using a logic circuit.

In order to be able to achieve a high working 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 large volume flow can be made available at the pressure connections at a low pressure level.

One possible embodiment of the hydraulic unit consists in that, in the starting position of the directional control valves, a flow path from the respective fluid line of one hydraulic circuit to the connecting line to the other hydraulic circuit is opened by these. In this case, a volume flow of hydraulic fluid from one hydraulic circuit is diverted to another hydraulic circuit as standard and this volume flow is only brought back to a certain extent when the pressure rises.

Furthermore, it can be provided that the first connection line runs from the first directional control valve to the second directional control valve and the second connection line runs from the second directional control valve to the first directional control valve, the second directional control valve having a flow path from the first connection line in a first switching position to a second fluid line leading to the second pressure connection or can establish a flow path from the second connecting line in a first switching position to a first fluid line leading to the first pressure connection in a further switching position to the fluid container and the first directional control valve or can produce in a further switching position to the fluid container. This means that further options are available for controlling the fluid flows and the hydraulic unit can respond even better to the requirements of the devices.

In order to be able to use the volume flow of another hydraulic circuit that is not required even at a high pressure level in the hydraulic circuit of a work device, it can be provided that a hydraulic circuit comprises at least two high-pressure elements, at least one of which is connected directly to the pressure connection via a fluid line and at least one via the directional control valve can be connected to another hydraulic circuit. In this version, a demand-based and performance-optimized allocation of the volume flows can take place in the low-pressure range as well as in the high-pressure range.

Furthermore, it is possible to divert the entire volume flow of one hydraulic circuit to another hydraulic circuit if all first fluid lines by means of one or more first directional control 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 by means of one or more second directional control valves and can be connected to at least one first fluid line of the first hydraulic circuit by means of one or more second connecting lines or transition lines. The operating state or the pressure level of a device that is no longer supplied with hydraulic fluid can no longer be determined by simple means, e.g. a control line can be detected by the hydraulic unit, therefore suitable other measures must be taken to reset the volume flow diversion, e.g. a coordinated alternating operation of the devices, which can, however, also take place without a separate operator for the hydraulic unit. One possibility for switching the operating mode could be that the device not supplied with hydraulic fluid generates a signal for resetting the volume flow diversion by means of a switch and an electrical control line, which again results in a simultaneous supply of both devices.

One possibility to achieve operation with several pressure levels is that a pressure switch valve is arranged in one of the fluid lines of a hydraulic circuit downstream of a pump element, which is controlled via a pressure control line going out from another fluid line of the same hydraulic circuit, whereby when the pressure rises in the Another fluid line from the pressure switching valve a flow path from the pump element to the fluid container is established. The delivery rate, which is under high pressure, can thus be reduced in a simple manner as required and the power of the drive can be optimally used.

Structurally advantageous pump arrangements that have proven particularly useful for mobile use are obtained when the first pump elements and the second pump elements are arranged in relation to one another as in a radial piston pump.

Ensuring a sufficient oil supply to the pump assemblies is possible for the most varied of applications if suction lines lead from the pump elements into the fluid container. In this case, the shape and position of the fluid container is largely freely selectable and can be operated with smaller fill quantities.

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 can be implemented in such a way that in the hydraulic unit in a first hydraulic circuit with a first pump arrangement by means of first fluid lines, volume flows of at least two first Pump elements are combined and passed to a first pressure connection and in a second hydraulic circuit with a second pump arrangement by means of second fluid lines, the volume flows of at least two second pump elements are combined and directed to a second pressure connection, the first pump elements and the second pump elements being simultaneously from a common drive are driven and wherein for the needs-based allocation of the volume flows to the pressure connections by means of a first directional valve at least one of the first fluid lines ü Is connected via a first connection line to a second fluid line in the second hydraulic circuit and by means of a second directional valve at least one of the second fluid lines is connected via a second connection line to a first fluid line in the first hydraulic circuit, the directional control valves being brought into a starting position by means of a spring and a Switching operation of the first directional control valve is effected by a first actuating element which is controlled by a first control line emanating from the first hydraulic circuit or the second hydraulic circuit and extending to the first actuating element, and a switching operation of the second Directional control valve by a second actuating member which is controlled by a second control line proceeding from the second hydraulic circuit or from the first hydraulic circuit and extending to the second actuating member.

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

For a better understanding of the invention, it is 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.

They each show in a greatly simplified, schematic representation:

Fig. 1

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

Fig. 2

a hydraulic scheme of a further embodiment of a hydraulic unit;

Fig. 3

a hydraulic scheme of a further embodiment of a hydraulic unit;

Fig. 4

a hydraulic scheme of a further embodiment of a hydraulic unit;

Fig. 5

a hydraulic diagram of a further embodiment of a hydraulic unit and

Fig. 6

a hydraulic diagram of a further embodiment of a hydraulic unit.

Fig. 1 shows, in a greatly simplified and schematic manner, a hydraulic unit 1 for supplying two or more hydraulically driven devices as required. The hydraulic unit 1 has at least two pressure connections 2 and 3 and can be connected to the in Fig. 1 left pressure connection 2 a first device 4, for example in the form of a rescue shears, a spreader cylinder or a spreader device can be connected. In Fig. 1 a second device 5, which can be connected to the right pressure connection 3, is also shown with dashed lines. The devices 4, 5 each have a fluid supply 6 through which the volume flow provided by the pressure connections 2, 3 is supplied and furthermore each have a fluid return 7, with which a volume flow is supplied to the hydraulic unit 1 again. Details of the fluid return 7 on the devices 4, 5 and on the hydraulic unit 1 are not shown or explained in more detail at this point, only simple return lines are required for this. To control the volume flow at the devices 4, 5, these are equipped, for example, with 4/3-way valves with which the hydraulic fluid can circulate at a low pressure level when the valve is in the idle position and in the other valve positions two different directions of movement of the devices 4, 5 can be selected.

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

The pump elements 13, 14 of the first pump arrangement 12 and the pump elements 16, 17 of the second pump arrangement 15 are driven by a common drive 18, wherein the drive 18 can comprise an electric motor, for example. The use of an internal combustion engine 19 as a drive is also advantageous for mobile use, since there is great spatial independence from power sources. The volume flows generated by the first pump elements 13 and 14 are guided via first fluid lines 20 and 21 to the first pressure connection 2, the at least two first fluid lines 20 and 21 also being able to be combined in a first collecting line 22 upstream of the first pressure connection 2. Analogously to this, the volume flows generated by the second pump elements 16 and 17 are guided via second fluid lines 23 and 24 to the second pressure connection 3, whereby the second fluid lines 23 and 24 can also be brought together in front of the second pressure connection 3 to form a second collecting line 25. The fluid lines 20, 21 and 23, 24 are shown in the form of arrows to clarify the volume flows guided through them.

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

In principle, it is provided that the volume flow of the first pump arrangement 12, i.e. the first pump elements 13 and 14, is provided at the first pressure connection 2 for the first device 4 and, analogously, the volume flow of the second pump arrangement 15 is provided at the second pressure connection 3 for the second device 5, so the second pump elements 16 and 17 is provided. If no device 4, 5 is connected to one of the pressure connections 2, 3, measures known from the prior art must be used to ensure that the volume flows generated by the pump elements 13, 14, 16, 17 are returned to the fluid container without damaging the hydraulic unit 1 11 are fed. This can, for example, be a pressure relief valve arranged upstream of the pressure connections 2, 3, which is operated manually and the volume flows are only fed to the pressure connections 2, 3 after a device 4 or 5 has been connected.

The power converted in a hydraulic circuit 8 or 9 is proportional to the product of the size of the volume flow and the level of the fluid pressure. Since the power of the drive 18, for example an internal combustion engine 19 used in the hydraulic unit 1, is limited, the volume flow that can be made available at the pressure connections 2 or 3 is also limited at the top at a certain pressure. In the case of low counterpressure from 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 internal combustion engine 19. In practice, however, a largely constant drive speed can be assumed, which is why the pump arrangements 12, 15 deliver a largely constant total delivery rate and this must be divided into volume flows with different pressure levels, adapted to the available drive power.

From the prior art it is known to provide a possibility in a generic hydraulic unit 1 to at least partially divert the volume flow available in a hydraulic circuit 8 or 9 to the other hydraulic circuit 9 or 8, whereby the power of the drive 8 is better utilized and a volume flow can be used at a pressure connection 2 or 3, which goes beyond the volume flow provided by the respective pump arrangement 12 or 15. 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 is made available at the other pressure connection, whereby increased working 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 control valve 26 with which the first fluid line 21 can be connected via a first connection line 27 to a second fluid line 24 in the second hydraulic circuit 9. A second directional control valve 28 is also arranged in a second fluid line 24 in the second hydraulic circuit 9 and the second fluid line 24 can be connected to the first fluid line 21 via a second connecting line 29.

It is known from the prior art to use directional control valves which are operated manually and a manual switching process is necessary for the needs-based allocation of the volume flows. 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 a machinist on the hydraulic unit. In the prior art, a separate operator is therefore required for the needs-based allocation of the volume flows to the devices.

In the case of a hydraulic unit 1 according to the invention, no separate operator is required for the needs-based allocation of the volume flows, since the directional control valves 26 and 28 carry out automated switching operations.

The directional control valves 26, 28 have for this purpose a spring 30, 31 acting in the direction of a starting position and furthermore comprise an actuating member 32, 33 with which the volume flow is either fed to the respective pressure connection 2 or 3 or via the connecting line 27 or 29 respectively to the other hydraulic circuit 9 or 8 is diverted. The first actuating member 32 acting on the first directional valve 26 is controlled via a control line 34 which, in the exemplary embodiment shown, runs from the second hydraulic circuit 9 to the actuating member 32 and the second actuating member acting on the second directional valve 28 33 is activated via a control line 35 which, in this exemplary embodiment, runs from the first hydraulic circuit 8 to the actuating member 33.

In the embodiment shown, 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 is applied to the actuator of the directional control valve of the other hydraulic circuit is transmitted. With such a hydraulic unit 1, the volume flow provided at a pressure connection 2 or 3 can be increased by that of a pump 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 manual adjustment of the directional control valves 26, 28 would be required.

The control lines 34 and 35 can also be electrical control lines with which status information from the respective other hydraulic circuit 9 or 8, e.g. Pressure levels or switch positions on the devices 4, 5 can be transmitted to the actuating member 32 or 33 of the hydraulic circuit 8, 9 under consideration and the switching operations explained above can be effected.

If, for example, the device 4 connected to the hydraulic unit 1 is a hydraulically driven rescue cylinder, there are different operating states when it is used. When the rescue cylinder is idling, the hydraulic fluid 10 can be fed to the switching valve of the rescue cylinder and from there back to the fluid tank 11 at a low pressure level. When retracting or extending the rescue cylinder without a load, there is only a low working resistance, which is due to the internal friction of the rescue cylinder and line resistance, and this retraction and extension movement takes place at a comparatively low pressure level of up to about 30 bar. This retraction or extension movement should be able to be carried out at the highest possible speed in order to save time, and it is therefore advantageous to provide a large volume flow and, due to the relatively low pressure level, the drive 18 can also provide the necessary power.

When the rescue ram is externally loaded, it works against a higher working resistance and the required fluid pressure increases and this must also be provided by the hydraulic unit 1. The pressure level typically increases to up to 700 (1000) bar and, due to the limited power of the drive 18, the volume flow under high pressure must be reduced.

The in Fig. 1 Hydraulic unit 1 shown, this can be done, for example, in that when there is a pressure increase at pressure connection 2, only the volume flow of first pump element 13 is guided to pressure connection 2, while the volume flow of pump element 14 is guided via a pressure-controlled valve, for example at a switching pressure of 150 to 250 bar is returned to the fluid container 11. The pump element 14 thus only uses a comparatively small proportion of the drive power and a correspondingly higher proportion of the drive power is available for the pump element 13, which has to generate the high working pressure.

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

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

The actuators 32, 33 can, for. B. can be implemented as a control piston for hydraulic control lines 34, 35 or as solenoid valves for electrical control lines 34, 35 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 that have already been shown in FIG Fig. 1 described Embodiment are provided accordingly with the same reference numerals. and repetitions of the component descriptions are largely dispensed with.

The device 4 that can be connected to the hydraulic unit 1 is formed in the illustrated embodiment by a hydraulic recovery device 36 and comprises a double-acting hydraulic cylinder in which a piston separates two working spaces within the hydraulic cylinder. The direction of movement of the recovery device 36 depends on which of the working spaces the hydraulic fluid 10 supplied by the fluid supply 6 is directed by means of a switching valve 37. The hydraulic fluid 10 displaced from the respective other working space is returned to the hydraulic unit 1 via the fluid return 7. When device 4 is connected, the fluid circuit leads from pressure connection 2 via fluid supply 6, device 4 and fluid return 7 back to a return connection 38 and return line 39 on hydraulic unit 1 or directly back to fluid container 11.

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

The drive 18, the pump arrangements 12 and 15 as well as the fluid lines 20, 21, 23, 24 and collecting lines 22, 25 correspond to that based on FIG Fig. 1 described, but 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 that the directional control valves 26 and 28 are pressed by the springs 30 and 31 into an initial 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 open. In this embodiment, the volume flow supplied by the pump element 14 is thus diverted to the other hydraulic circuit 9 in the starting position of the directional control valve 26. Analogously to this, the starting position of the directional valve 28 in the second hydraulic circuit 9 is such that the volume flow supplied by the pump element 17 is diverted to the first hydraulic circuit 8.

Since the pump arrangements 12 and 15 usually have identical delivery rates, this “crossing” of volume flows between the two hydraulic circuits 8 and 9 is the result without any noticeable effect on the volume flows or pressures provided at the pressure connections 2 or 3.

The actuating member 32, with which the first directional valve 26 is switched from the initial position against the action of the spring 30, is in turn addressed by a first control line 34, which in this embodiment, however, originates from the first hydraulic circuit 8 itself, namely from the first fluid line 20, which leads from the pump element 13 to the first pressure connection 2.

With this embodiment, the first hydraulic circuit 8 retrieves the volume flow diverted from the pump element 14 to the second hydraulic circuit 9 to a certain extent for its own needs when there is a pressure increase in the fluid line 20. Likewise, the second hydraulic circuit 9 can retrieve the volume flow of the pump element 17 diverted to the first hydraulic circuit 8 in the initial position of the second directional valve 28 to its own pressure connection 3, if required.

As already explained, such a hydraulic unit 1 can be used to supply a device 4, 5 with different pressure levels of the hydraulic fluid 10, whereby a large volume flow can be provided at low pressure and only a small volume flow at high pressure due to the predetermined power of the drive 18. In order to make this possible, provision can be made for individual pump elements, for example pump elements 14 and / or 17, to be diverted directly to fluid container 11 by means of a valve (not shown) when the pressure level in the working device rises, thus reducing the proportion of the high-pressure delivery rate.

Furthermore, it is possible for the pump elements 13 and 14 of the pump arrangement 12 or the pump elements 16 and 17 of the pump arrangement 15 to have delivery capacities of different sizes. With a certain drive intensity of the drive 18, for example a reference speed, it can be provided that the pumping element 14 has a greater delivery rate than the pumping element 13 and is thus well suited for supplying a large volume flow at a comparatively low pressure level, while the smaller pumping element 13, with its smaller delivery rate, is ideally suited for providing a comparatively small volume flow at a high pressure level. About the interpretation For such multi-pressure stage pumps, reference is made to the prior art known in this regard.

A hydraulic unit 1 according to the invention has, for example, the following delivery rates, which are dependent on the respective operating situation. A speed of 3000 rpm is assumed as the reference intensity of the drive 18, for example. At this reference intensity, the two pump elements 13 and 16 of the hydraulic circuits 8, 9 each have a delivery rate of 0.7 l / min, for example, and the pump elements 14 and 17 have a delivery rate of 2.0 l / min, for example. The pump elements 13 and 16 can thus be referred to as high pressure elements 40 and 41 and the two larger pump 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 This results in the following flow rates when using two devices 4, 5. If two devices 4, 5 are connected to the pressure connections 2, 3, these are flown through in idle mode at a pressure level of up to about 20 bar. The volume flow delivered by the pump arrangement 12 of a total of 2.71 is available at the pressure connection 2 as the delivery rate. The second device 5 is also supplied from the pressure connection 3 with a volume flow of 2.7 l / min.

If, for example, an adjustment movement is initiated on the device 4 with little resistance, the pressure rises to over 20 bar, whereby a switching signal is sent to the second directional control valve 28 via the control line 35 and the volume flow of the pump element 17 is diverted to the first hydraulic circuit 8 and thereby A delivery rate of 4.7 l / min is available at the first pressure connection 2. As a result, if only one device is activated, it can achieve a significantly higher working speed. If, for example, the device 5 is now also activated with a low working resistance, a switching signal is transmitted to the first directional valve 26 via the control line 34 due to the pressure increase in the second fluid line 23, the switching process being effected by the actuating member 32. As a result, the volume flow supplied by the pumping element 14 is diverted to the second hydraulic circuit 9 and in this operating state the devices 4, 5 again have a delivery rate of 2.7 l / min, as in idle operation. The increased The operating speed of the devices 4 or 5 can therefore always be used automatically if only one of the devices 4, 5 is actuated.

If a high working resistance occurs at a device 4, the volume flow delivered by the pump element 14 is reduced by means of an in Fig. 2 Not shown valve is diverted to the fluid container 11 and the drive power of the drive 18 is predominantly available for the first pump element 13, with which a delivery rate of 0.7 l / min is made available at the pressure port 2 at the reference speed of 3000 rpm can. The pressure level is roughly between the switchover pressure of less than 250 bar, when the volume flow of the pump element 14 is exceeded, and the system pressure of about 750 bar to 1000 bar, which is limited upwards by a pressure limiting valve.

The great advantage of the hydraulic unit 1 according to the invention is that these switching processes for the needs-based allocation of the volume flows to the pressure connections 2 and / or 3 do not have to be carried out by an operator, but rather on the basis of the directional control valves 26, 28.

At the in Fig. 2 The illustrated embodiment, the device 4 is supplied from the pressure connection 2 in idle with a delivery rate of 2.7 l / min, which is made up of a partial amount of 0.7 l / min from the high pressure element 40 of the first hydraulic circuit 8 and a partial amount of 2.0 l / min composed of the low pressure element 43 of the second hydraulic circuit. When the pressure increases by activating the device 4 with a low working resistance, the volume flow of the low-pressure element 42 is also fed to the pressure port 2 with a delivery rate of 2.0 l / min, which means that a total of 4.7 l / min is available when there is no volume flow for a second device 5 is required.

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

In Fig. 3 a further and possibly independent embodiment of a hydraulic unit 1 is shown schematically, again with the same reference numerals for the same parts or component names as in the previous ones Fig. 1 and 2 be used. To avoid unnecessary repetition, refer to the description in the preceding Fig. 1 and 2 pointed out or referred to.

In this embodiment, the connecting line 27 outgoing from the first hydraulic circuit 8 at the first directional valve 26 leads to the second directional valve 28 and in this the volume flow delivered via the connecting line 27 is diverted into the fluid container 11 either via a return line 39 or via a, depending on the switching position of the directional valve 28 The flow path in the directional control valve 28 is combined with the volume flow supplied by the second pump element 17 in the second fluid line 24 and then made available to the second pressure connection 3 via the second collecting line 25.

Analogously to this, the connecting line 29 outgoing from the second hydraulic circuit 9 at the second directional valve 28 leads to the first directional valve in the first hydraulic circuit 8 and, depending on the switching position of the valve 26, the volume flow delivered via the connecting line 29 is either fed to the fluid container 11 via a return line 39 or to the from The volume flow supplied by the pump element 14 is summarized and made available in sequence via the collecting line 22 at the first pressure connection 2.

In addition, as shown, non-return valves 44 can be provided in the connecting lines 27, 29, with which an undesired reversal of flow direction or pressure propagation in an undesired direction can be prevented.

In the case of the pump elements 14 and 17 as well, which are provided with the symbol ND as low-pressure elements 42 and 43, check valves 44 can be provided in the fluid lines 21 and 24 outgoing therefrom. Furthermore, a check valve 44 can also be provided in the fluid lines between the directional control valves 26, 28 and the pressure connections 2, 3 so that no pressure propagation into the low pressure area can take place when the pressure level at the pressure connections 2, 3 increases.

The pumping elements 13, 14, 16, 17 in Fig. 3 are, as already with Fig. 1 and 2 described, provided with a drive, not shown, with which the pump elements are driven simultaneously. To adapt the pressure ports 2, 3 provided A pressure switch valve 45 is provided in the first hydraulic circuit 8, with which the volume flow supplied by the pump element 14, i.e. a low pressure element 42, is no longer directed to the pressure connection 2 but into the fluid container 11 when a switch pressure is exceeded. The switchover of the pressure switchover valve 45 is effected via a control line 46 going out from the first fluid line 20, with which the fluid pressure prevailing at the pressure connection 2 is passed to the pressure switchover valve 45 and this triggers a switchover process by means of an actuating element (not shown) if, due to an increasing pressure in the Control line 46 a spring 47 causing the initial position of the pressure switching valve 45 is overcome.

In the second hydraulic circuit 9, a pressure switching valve 48 is provided analogously, with which the volume flow supplied by the second pump element 17 is no longer passed to the second pressure connection 3, but into the fluid container 11 when a limit pressure is exceeded. A control line 49 causing the switchover picks up the pressure level existing between the second pump element 16, i.e. the high pressure element 41 and the second pressure connection 3, and when a restoring force caused by a spring 50 is exceeded, the volumetric flow of the pump element 17 is diverted to the fluid container 11. In these cases, the power of the drive is predominantly available for driving the high-pressure elements 40 and 41 and, with the connected devices 4, 5, even high work resistances can be overcome.

To protect the hydraulic unit 1, provision can also be made for each hydraulic circuit 8, 9 to be provided with a pressure limiting valve 51 which limits the maximum pressure provided at the pressure connections 2 and 3 and the maximum pressure is set in such a way that components of the hydraulic unit 1 cannot burst is avoided. An upper limit of 750 to 1000 bar, for example, is set as the maximum pressure.

The mode of operation of the directional control valves 26, 28 corresponds to Fig. 3 essentially that of the in Fig. 2 illustrated embodiment, since here in their initial position the volume flow supplied by the pump element 14, 15 is passed to the other hydraulic circuit and, when the directional control valve 26 or 28 is switched, the volume flow returns to the respectively considered due to an increasing pressure in the control line 34 or 35 Hydraulic circuit 8 or 9 is brought back and is routed to the respective pressure port 2 or 3.

In the exemplary embodiment shown, both directional control valves 26 and 28 are shown in their initial position and the volume flow diverted by the other hydraulic circuit 9 or 8 is returned directly from the valve to the fluid container 11 via a return line 39, essentially without pressure. If, for example, a device 4 is actuated at the pressure connection 2 and the fluid pressure rises as a result, a switching operation of the directional control valve 26 is effected via the control line 34 and the volume flows of the pump elements 13, 14 and 17 are fed to the pressure connection 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 a pressure increase is caused at both pressure connections 2 and 3 by actuating a connected device 4 or 5, no more hydraulic fluid is transmitted via the connecting lines 27 and 29 and each pressure connection 2, 3 is supplied by the associated hydraulic circuit 8, 9 alone.

In Fig. 4 a further and possibly independent embodiment of a hydraulic unit 1 is shown, again with the same reference numerals or component designations as in the preceding for the same parts Figs. 1 to 3 be used. To avoid unnecessary repetition, please refer to the detailed description in the preceding section Figs. 1 to 3 pointed out or referred to.

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 pump elements 14 and 17 are provided within their own hydraulic circuit 8 and 9 at the respective pressure connection 2 and 3 and only if the pressure rises in the other hydraulic circuit 9 or 8, a volume flow is diverted. The actuators activated by control lines 34 and 35 are shown in FIG Fig. 4 not shown for reasons of space.

Fig. 4 further shows that pressure relief valves 52 can optionally be provided in the hydraulic circuits 8 and 9 upstream of the pressure connections 2 or 3, with which a largely pressureless return of hydraulic fluid to the fluid container 11 can be established can be used in the event that no device is connected to the respective pressure port 2 or 3. These pressure relief valves 52, which can also be used in other embodiments of the hydraulic unit 1, can be operated manually or they can also be part of a coupling system in which both the fluid feed 6 and the fluid return 7 of the device (see FIG Fig. 1 ) get connected. The pressure relief valve 52 can in this case be designed as a by-pass valve in the pressure port 2 or 3.

In Fig. 4 It is also shown that the pump elements 14, 17, which can be designed as low-pressure elements 42 and 43, can each be followed by a pressure limiting valve (DBV) 53, which in the illustrated embodiment is effective when the hydraulic fluid from the directional control valves 26 and 28, respectively is diverted to the other hydraulic circuit 9 or 8 and a very high fluid pressure is present in this due to a high working resistance. In this case, the volume flow of the pump elements 42 and 43 can be diverted into the fluid container 11 via the pressure limiting valve 53. A pressure is selected as the limit pressure from which a pressure relief valve 53 opens which corresponds to the switching pressure of the pressure switching valves 45 or 48, since from this pressure level the volume flows of the low-pressure elements 42, 43 are no longer directed to the pressure connections 2 or 3. A pressure limiting valve 53 can structurally correspond to the pressure switchover valves 45, 48.

In Fig. 5 a further and possibly independent embodiment of a hydraulic unit 1 is shown, with the same reference numerals or component designations for the same parts as in the preceding Figs. 1 to 4 be used. In order to avoid unnecessary repetition, the detailed description in the preceding sections is referred to Figs. 1 to 4 pointed out or referred to.

In this exemplary embodiment, the mode of operation of the directional control valves 26 and 28 is as in FIG Fig. 3 described embodiment and is diverted from a hydraulic circuit 8, in which no device is connected to the pressure connection 2 or the connected device is idle, a part of the volume flow to the other hydraulic circuit 9. In this exemplary embodiment, the first fluid line 21 leading to the directional valve 26 not only carries the volume flow of the pump element 14, but also the volume flow of a further pump element 54 and can be diverted to the other hydraulic circuit 9 via the directional valve 26 become. While the pump element 14 is designed as a low-pressure element 42, which has a comparatively high delivery rate, the pump element 54 is designed as a high-pressure element 55, which has a comparatively small delivery rate. In the position of the directional control valve 26 shown, both volume flows of the pump 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 diverted delivery rate is discharged via the return line 39 to the fluid container 11. If the pressure in the second hydraulic circuit 9 increases, this volume flow is directed to the second pressure connection 3, since the second directional valve 28 is switched via the control line 35 of the second hydraulic circuit. The delivery rate of the second hydraulic circuit 9 is then available at the pressure connection 3, increased by the delivery rate of the pump elements 14 and 54. In the event of a further pressure increase in the second hydraulic circuit 9, which causes a transition to the high pressure area, the volume flow of the pump element 14, which is designed as a low pressure element 42, is diverted directly into the fluid container 11 via the pressure switch valve 45 and is only the volume flow of the pump element 54, which is designed as a high-pressure element 55, is diverted to the second hydraulic circuit 9. Thus, even in high pressure operation at the second pressure connection 3 of the hydraulic circuit 9, a delivery quantity increased by the volume flow of the high pressure element 55 is available.

Analogously to this, an additional pump element 56 is also arranged in the second hydraulic circuit 9, which is designed as a high pressure element 57 and can increase the volume flow provided at the pressure connection 2 of the first hydraulic circuit 8 by the delivery rate of this high pressure element 57 and possibly also by the volume flow of the low pressure element 43 in the second hydraulic circuit 9 can be increased. With this embodiment, in which a volume flow can be diverted from the non-active hydraulic circuit to the other hydraulic circuit even with high working resistance and high pressure level, the power of drive 18 can be optimally used even with high working resistance and the working speed of a device can be maximized even with high working resistance .

The pressure switching valves 45 and 48 are activated via control lines 46 and 49 with the fluid pressure acting on the high-pressure elements 55 and 57, respectively.

In Fig. 6 a further and possibly independent embodiment of a hydraulic unit 1 is shown, with the same reference numerals or component designations for the same parts as in the preceding Figs. 1 to 5 be used. In order to avoid unnecessary repetition, the detailed description in the preceding sections is referred to Figs. 1 to 5 pointed out or referred to.

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

In the embodiment according to Fig. 6 For example, the volume flow of the pump elements 13 and 14 can be diverted via the path element 26 to the second hydraulic circuit 9, with the control of the volume flow of the pump element 14, which can be designed as a low-pressure element 42, as in the previous embodiments. To divert the volume flow of the pump element 13, which is designed as a high-pressure element 40, a shut-off valve 58 arranged in the first fluid line 20 as well as a transition line 59 leading between the pump element 13 and shut-off valve 58 and leading to the further first fluid line 21 are used. The shut-off valve 58 is in its The initial position brought about by a spring 60 is open and the volume flow of the pump element 13 can reach the pressure connection 2 of the first hydraulic circuit 8. The shut-off valve 58 is shut off 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. When the pressure in the second hydraulic circuit 9 rises, the first fluid line 20 from the pump element 13 to the pressure connection 2 is shut off and the volume flow of the pump element 13 is guided via the transition line 59 to the directional control valve 26, from which it then passes via the first connection line 27 to the second hydraulic circuit 9 . By 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 pump element 16 can be diverted to the first hydraulic circuit 8 in an analogous manner.

In this way, the volume flows of other pump elements (not shown) can also be requested by the other hydraulic circuit in each case, and the delivery rate provided at the respective pressure connection can thereby be automatically increased.

Because both hydraulic circuits 8 and 9 have such a transition function or diversion function in the illustrated embodiment, only the hydraulic circuit that requests the volume flows of the other pump elements before the other hydraulic circuit can provide the increased delivery rate at the pressure connection. The shut-off valves 58, 62 are activated at a pressure below about 25 bar, which means that the required base pressure is available at both pressure connections when devices are not operated, i.e. in idle mode, and the device activated earlier receives the volume flow of all pump elements.

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

The hydraulic fluid 10 advantageously reaches the pump elements from the fluid container 11 via suction lines.

The exemplary embodiments show possible design variants of the hydraulic unit 1, whereby it should be noted at this point that the invention is not limited to the specially illustrated design variants of the same, but rather various combinations of the individual design variants with one another are possible and this possible variation based on the teaching on technical action The present invention is within the ability of those skilled in this technical field.

All information on value ranges in the objective description should be understood to include any and all sub-ranges, e.g. The indication 1 to 10 is to be understood in such a way that all sub-areas, starting from the lower limit 1 and the upper limit 10, are included, i.e. all subranges start 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 or the same component names, whereby the disclosures contained in the entire description can be transferred accordingly to the same parts with the same reference numerals or the same component names. The location details chosen in the description, such as above, below, to the side, etc., referring to the figure immediately described and shown, and if there is a change in position, these position details are to be transferred to the new position accordingly.

For the sake of clarity, 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 not to scale and / or enlarged and / or reduced. <b> List of reference symbols </b> 1 Hydraulic power pack 31 feather 2 Pressure connection 32 Actuator 3 Pressure connection 33 Actuator 4th device 34 Control line 5 device 35 Control line 6th Fluid supply 36 Recovery device 7th 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 arrangement 42 Low pressure element 13 Pumping element 43 Low pressure element 14th Pumping element 44 check valve 15th Pump arrangement 45 Pressure switching valve 16 Pumping element 46 Control line 17th Pumping element 47 feather 18th drive 48 Pressure switching valve 19th Internal combustion engine 49 Control line 20th First fluid line 50 feather 21st First fluid line 51 Pressure relief valve 22nd First collecting line 52 Pressure relief valve 23 Second fluid line 53 Pressure relief valve 24 Second fluid line 54 Pumping element 25th Second collecting line 55 High pressure element 26th First directional valve 56 Pumping element 27 First connection line 57 High pressure element 28 Second directional valve 58 Shut-off valve 29 Second connection line 59 Interim management 30th feather 60 feather 61 Control line 62 Shut-off valve 63 Interim management 64 feather 65 Throttle element 66 Throttle element

Claims (11)

1. A hydraulic unit (1) comprising at least two pressure connections (2, 3) for the required supply of one or more hydraulically driven 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) consisting of at least two first pump elements (13, 14) from which first fluid lines (20, 21) lead to a first pressure connection (2), at least one second hydraulic circuit (9) with a second pump arrangement (15) consisting of at least two second pump elements (16, 17) from which second fluid lines (23, 24) lead to a second pressure connection (3), wherein the first pump elements (13, 14) and the second pump elements (16, 17) are driven at the same time by a common drive (18), and wherein by means of a first directional valve (26) arranged in one of the first fluid lines (21), the volume flow of said first fluid line (21) can be diverted via a first connecting line (27) to a second fluid line (24) in the second hydraulic circuit (9), and by means of a second directional valve (28) arranged in one of the second fluid lines (24), the volume flow of said second fluid line (24) can be diverted via a second connecting line (29) to a first fluid line (21) in the first hydraulic circuit (8), wherein the directional valves (26, 28) comprise a spring (30, 31) acting in the direction of an initial position and a first control line (34) runs from the first hydraulic circuit (8) or from the second hydraulic circuit (9) to a first actuator (32) acting on the first directional valve (26) and a second control line (35) runs from the second hydraulic circuit (9) or from the first hydraulic circuit (8) to a second actuator (33) acting on the second directional valve (28), wherein the first pump elements (13, 14) comprise at least one high pressure element (40) with a lower flow rate at a reference intensity of the drive (18) and at least one low pressure element (42) with a higher flow rate at the reference intensity, and the second pump elements (16, 17) comprise at least one high pressure element (41) with a lower flow rate and at least one low pressure element (43) with a higher flow rate, and each of the first and second directional valves (26, 28) are arranged in the fluid lines (21, 24) leading away from the low pressure elements (42, 43).
2. The 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 and/or first directional valve (28, 26).
3. The hydraulic unit (1) according to claim 1, characterized in that the first and/or second control line (34, 35) is designed as an electric control line and, by means of an electromagnetic adjusting unit, acts directly or with a pilot element on the second directional valve and/or first directional valve (28, 26).
4. The hydraulic unit (1) according to claim 1, characterized in that the flow rate of the low pressure elements (42, 43) of a hydraulic circuit (8, 9) amounts to at least double the flow rate of the high pressure elements (40, 41) of the same hydraulic circuit (8, 9).
5. The hydraulic unit (1) according to one of claims 1 to 4, characterized in that, in the initial position of the directional valves (26, 28), a flow path is opened by said directional valves (26, 28), from the respective fluid line (21, 24) of one hydraulic circuit (8, 9) to the connecting line (27, 29) to the other hydraulic circuit (9, 8).
6. The hydraulic unit (1) according to one of claims 1 to 5 characterized in that the first connecting line (27) runs from the first directional valve (26) to the second directional valve (28) and the second connecting line (29) runs from the second directional valve (28) to the first directional valve (26), wherein the second directional valve (28) can form a flow path from the first connecting line (27) in a first switch position to a second fluid line (24) leading to a second pressure connection (3) and, in an additional switch position, to the fluid container (11), and the first directional valve (26) can form 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 connection (2) and, in an additional switching position, to the fluid container (11).
7. The hydraulic unit (1) according to claim 6, characterized in that a hydraulic circuit (8) comprises at least two high pressure elements (40, 55), at least one of which is connected via a fluid line (20) directly to the pressure connection (2), and at least one can be connected by the directional valve (26) to another hydraulic circuit (9).
8. The hydraulic unit (1) according to one of claims 1 to 7, characterized in that all first fluid lines (21, 22) can be connected by means of one or more first directional valves (26) and by means of one or more first connecting lines (27, 59) to at least one second fluid line (23, 24) of the second hydraulic circuit (9) and/or all second fluid lines (23, 24) can be connected by means of one or multiple second directional valves (28) and by means of one or more second connecting lines (29, 63) to at least one first fluid line (20, 21) of the first hydraulic circuit (8).
9. The hydraulic unit (1) according to one of claims 1 to 8, characterized in that in one of the fluid lines (21) of a hydraulic circuit (8), following a pump element (14), a pressure switching valve (45) is arranged, which is controlled by a pressure control line (46) coming from another fluid line (20) of the same hydraulic circuit (8), whereby with an increase in pressure in the other fluid line (20) a flow path from the pump element (14) to the fluid container (11) is created by the pressure switching valve (45).
10. The hydraulic unit (1) according to one of claims 1 to 9, characterized in that the first pump elements (13, 14) and the second pump elements (16, 17) are arranged relative to one another as in a radial piston pump.
11. The hydraulic unit (1) according to one of claims 1 to 10, characterized in that suction lines lead from the pump elements (13, 14, 16, 17, 40, 41, 42, 43, 54, 55, 56, 57) into the fluid container (11).

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