AT524855B1 - Hydraulic unit for supplying hydraulically driven rescue equipment - Google Patents

Abstract

The invention relates to a hydraulic unit (1) with a first and at least one further pressure outlet (2, 3) for selectively supplying an individual hydraulically drivable rescue device (4; 5) at one of the pressure outlets (2, 3) with pressurized hydraulic fluid, or for simultaneous Supply of several hydraulically drivable rescue devices (4, 5) at the pressure outlets (2, 3) with pressurized hydraulic fluid. An electronic control device (44) of the hydraulic unit (1) is connected to at least one temperature sensor (50) and pressure sensors (40, 41). The electronic control device (44) is set up to (i) suppress a pressure-dependent controlled accumulation and cumulative supply of delivery quantities of a first and second pump arrangement (12, 15) of the hydraulic unit (1) to a common, individual pressure outlet (2; 3). or to set it inactive and (ii) to prevent or set inactive a hydraulically or electrically controlled, automated speed increase of the drive motor (18) if the temperature value of the hydraulic fluid detected by the at least one temperature sensor (50) is below a predetermined temperature threshold value for the hydraulic fluid and if, in addition, the pressure detected by the at least one pressure sensor (40, 41) at each of the pressure outlets (2, 3) is below a predetermined pressure threshold value.

Description

description

The invention relates to a hydraulic unit with a first and at least one further pressure outlet. In particular, a hydraulic unit with at least two hydraulic interfaces or connections is specified, which is suitable for selectively supplying a single hydraulically drivable rescue device at one of the pressure outlets with pressurized hydraulic fluid, and which is also suitable for the simultaneous supply of a plurality of hydraulically drivable rescue devices at one of the pressure outlets each pressurized hydraulic fluid is suitable. Such hydraulically driven rescue devices can be used for example by spreading, scissors or pressure cylinder tools for salvage or. Rescue operations be formed.

The AT516181B1, which goes back to the applicant, relates to a hydraulic unit with two pressure ports for supplying multiple devices, especially hydraulic rescue equipment. The hydraulic unit comprises a first hydraulic circuit with a first pump arrangement and a first pressure connection and a second hydraulic circuit with a second pump arrangement and a second pressure connection, the pump arrangements being driven simultaneously by a common drive, and the first hydraulic circuit being connected to the second by means of a first directional control valve Hydraulic circuit can be connected and the second hydraulic circuit can be connected to the first hydraulic circuit by means of a second directional control valve. The directional valves have a spring acting in the direction of an initial position and a first control line runs from the first hydraulic circuit or from the second hydraulic circuit to the first directional valve and a second control line runs from the second hydraulic circuit or from the first hydraulic circuit to the second directional valve. This enables automated cumulation and separation of volume flows of the first and second hydraulic circuits, so that the volume flows and hydraulic pressures at the pressure connections are automatically adjusted as required, without an operator being required for this. However, this automatic function is only partially satisfactory for individual operating states.

[0003] EP2260210B1, which also goes back to the applicant, describes a pressure-dependent control device for automated speed change of the internal combustion engine of hydraulic units with two hydraulic pressure outlets or two hydraulic interfaces for hydraulically operated rescue equipment. Such a speed setting device can adequately cover a certain range of uses for hydraulic units.

The object of the present invention was to overcome the disadvantages of the prior art and to provide a hydraulic unit with which rescue operations using hydraulic rescue equipment under a wide range of operating conditions can be carried out as energy-efficiently as possible and yet as comfortably as possible for the rescue workers.

[0005] This object is achieved by a hydraulic unit according to the claims.

The hydraulic unit according to the invention includes

- a first hydraulic circuit with a first pump arrangement comprising at least one high-pressure pump element and at least one low-pressure pump element with mutually different flow rates and different maximum pump pressures, from which first pump arrangement fluid lines lead to the first pressure outlet,

- a second hydraulic circuit with a second pump arrangement comprising at least one high-pressure pump element and at least one low-pressure pump element with mutually different flow rates and different maximum pump pressures, from which second pump arrangement fluid lines lead to the at least one further pressure outlet,

- a controlled, variable-speed drive motor in the form of an internal combustion engine or an electric motor for jointly coupled driving of the first and second pump arrangement,

- At least one hydraulic switching device with at least one directional valve for control

bare or automatically controlled cumulation of flow rates or volume flows of the first and second pump assembly and for controllable or automatically controlled separation or separation of cumulative flow rates of the first and second pump assembly.

Such a hydraulic unit also includes at least one temperature sensor, which is provided for detecting the temperature of the hydraulic fluid. At least one pressure sensor is provided for detecting hydraulic pressure conditions at the first and at least one further pressure outlet, with an electronic control device being configured which is connected to the at least one temperature sensor and the at least one pressure sensor.

The electronic control device is set up to (i) suppress or prevent or inactive a pressure-dependent controlled, in particular an automated accumulation and cumulative supply of delivery quantities of the first and second pump arrangement to a common pressure outlet or to an individual hydraulic interface and (ii) to prevent a hydraulically or electrically controlled, automated speed increase of the drive motor, in particular of an internal combustion engine or an electric motor, if the temperature value of the hydraulic fluid detected by the at least one temperature sensor is below a predetermined temperature threshold value for the hydraulic fluid and if at the same time or in addition, the pressure detected by the at least one pressure sensor at each of the pressure outlets is below a predetermined pressure threshold value. Typically, mineral or biodegradable hydraulic oil is provided as the hydraulic fluid. The predetermined temperature threshold value can be approximately 10° C., in particular approximately 5° C., typically 0° C., primarily depending on the type of hydraulic fluid used.

On the one hand, the speed of the drive motor is only automatically increased by the technical measures according to the invention when there is actually a power or pressure requirement starting from a rescue device connected to the hydraulic unit. A cold and therefore relatively highly viscous or viscous hydraulic fluid has no falsifying influence on an automatic speed increase of the drive motor as a result of an alleged power or pressure requirement of a connected hydraulic rescue device. In particular, a higher dynamic pressure at the pressure outlets as a result of a hydraulic fluid that is relatively viscous due to the cold does not lead to an inadequate, automatic speed increase of the electric motor and/or does not lead to an inadequate diversion of volume flows between the hydraulic circuits.

An automatic increase in the speed of the drive motor, in particular in connection with a hydraulically actuated or fluidically controlled drive speed setting device, therefore also works effectively when the hydraulic fluid is relatively cold, i.e. after the hydraulic unit has been stored and put into operation outdoors, especially when sub-zero temperatures. The speed of the drive motor is only automatically increased by the measures according to the invention or the hydraulic switching device is only switched over to accumulate or increase volume flows at one of the pressure outlets when there is actually a power or pressure request from a rescue device connected to the hydraulic unit present. As a result, unnecessary noise pollution for the emergency services and also for the people to be rescued can be avoided. In addition, unsettling of the emergency services as a result of mysterious, automatic switching processes or speed increases of the hydraulic unit can be avoided.

[0011] In addition, the most energy-efficient operation of the hydraulic unit is thereby achieved. This is of particular advantage in the case of mobile hydraulic units with a limited amount of drive energy available, in particular a limited battery capacity or quantity of fuel. In this context, improved availability of the performance or function of the hydraulic unit according to the claims can also be achieved, which can be of particular advantage in connection with often time-critical rescue operations. The improved energy efficiency is achieved because the speed of the drive motor only then

is automatically raised or an accumulation of volume flows is only automatically initiated when there is actually a power or pressure requirement from a rescue device connected to the hydraulic unit or is requested by an operator.

Below the predetermined pressure threshold value, which is preferably stored in the control device in terms of data technology, there is no express power or pressure requirement from a rescue device at any of the pressure outlets. The predetermined pressure threshold is set higher than the free circulation pressure at the pressure outlets, which free circulation pressure prevails in the state of pressureless circulation of the hydraulic fluid at the pressure outlets. However, the predetermined pressure threshold is chosen such that it is higher in value than the free circulation pressure. In particular, the free circulation pressure is significantly or clearly exceeded when there is a demand for power from one of the rescue devices, in particular as a result of a hydraulic piston movement in a cylinder of a rescue device. The predetermined pressure threshold value is therefore above the pressure value during a so-called pressureless circulation of the hydraulic fluid and below a pressure value of the hydraulic fluid which is required in order to be able to carry out an idling adjustment movement with a connected rescue device, i.e. a movement without movement resistance starting from an external object . This predetermined pressure threshold value can be between 10-70 bar, in particular around 50 bar, primarily depending on the size or capacity of the hydraulic cylinder arrangement of the rescue device. In typical, hand-held rescue devices, this is a common value range or threshold value for a load-free adjustment movement of the tool or for a so-called idle movement in the course of a resistance-free opening or closing movement, for example of a scissor tool of the rescue device.

Furthermore, it can be expedient if the at least one temperature sensor is provided for detecting the temperature of the hydraulic fluid located within a fluid container. The amount of liquid in the fluid container or hydraulic tank has the greatest heat or cold energy and the tank is therefore the system-relevant section for temperature measurement. In particular, this makes it possible to achieve a functionally optimized, temperature-dependent control of the hydraulic unit.

Furthermore, it can be provided that a drive speed setting device for the drive motor comprises an electric actuator for changing a fuel delivery rate or fuel intake rate of the drive motor. As a result, an easily controllable change or functionally stable adjustment of the drive speed of the drive motor is possible. If necessary, a sensitive or stepless change in the drive speed of the drive motor can also be carried out as a function of the respective performance or speed requirements of the at least one hydraulic rescue device. In particular, it is possible in this way to implement a demand-adapted speed change between the idle speed of the internal combustion engine and the nominal or maximum speed of the internal combustion engine.

Alternatively, it can be provided that a drive speed setting device for the drive motor comprises a power electronic speed controller, in particular a frequency converter, which is provided for changing the drive speed of a drive motor designed as an electric motor as required. As a result, the most energy-efficient operation possible can be achieved, especially in the case of a battery-powered hydraulic unit. In addition, starting from a minimum volume flow during a standby or idling operation of the hydraulic unit, it is thereby possible to switch relatively rapidly to a performance or work operating state—and vice versa.

Also advantageous is an embodiment according to which the at least one directional valve of the hydraulic switching device is formed by at least one electrically controllable solenoid valve, which or which are connected to the control device. As a result, an electrically controlled switchover device is created in relation to the hydraulic circuits of the hydraulic unit and an optimized automatic switchover or actuation of the hydraulic

mechanical switching device can be achieved. In particular, in addition to the temperature and pressure parameters, other operating parameters can also flow into the automatic, hydraulic shifting processes in a simple manner.

According to one embodiment, it is possible for the control device to be set up to detect an actuation or inactive state of a rescue device connected to the hydraulic unit, in that the control device detects the presence of the idle or active switching state of the hydraulic switching device and pressure signals from the evaluates at least one electrical pressure sensor. This makes it possible to reliably detect whether a rescue device connected to the hydraulic unit is actually activated or actuated by an operator, without an electrical switching signal or any other feedback signal from the rescue devices being required for this. Separate signaling or control lines to the hydraulic unit can thus advantageously be dispensed with. This evaluation or determination of the operating status of a connected rescue device is reliable because the included switching status of the hydraulic switching device also has an influence on the dynamic pressure at the pressure outlets of the hydraulic unit. In particular, the dynamic pressure at the pressure outlets is dependent on the delivery quantities or the volume flows at the pressure outlets, ie whether or not there is an accumulation of delivery quantities of the individual hydraulic circuits.

It can also be useful if the at least one pressure sensor is formed by at least one pressure-voltage or pressure-current converter.

[0019] As a result, a reliable or standardized sensor system for detecting the respective pressure states is implemented. Such a pressure sensor system also enables simple electrical connection and evaluation by the control device.

According to an advantageous embodiment it can be provided that each of the pump assemblies has at least one high-pressure, medium-pressure and low-pressure pump element. Such an at least three-stage pump arrangement is robust and enables good utilization of the torque curve of the drive device. In particular, rapid approach or return movements of the tool of a rescue device can be achieved in this way and at the same time high or powerful work performance, for example spreading or cutting forces, can be achieved. Compared to relatively complex variable pumps, pump arrangements with at least three predefined pressure stages are robust and reliable, and can be implemented in the hydraulic unit in a simple and compact manner.

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

[0022] In each case, in a highly simplified, schematic representation:

1 shows a hydraulic diagram of a hydraulic unit known from the prior art;

[0024] FIG. 2 shows a schematic of a hydraulic unit according to the invention with two pressure outlets for operating up to two rescue devices that can be connected to it;

[0025] FIG. 3 shows a schematic of a hydraulic unit according to the invention with two pump arrangements and three pressure levels each.

First of all, it should be noted that in the differently described embodiments, the same parts are provided with the same reference numbers or the same component designations, and the disclosures contained throughout the description can be transferred analogously to the same parts with the same reference numbers or the same component designations. The position information selected in the description, such as top, bottom, side, etc., is related to the figure directly described and shown and these position information are to be transferred to the new position in the event of a change of position.

Fig. 1 shows a highly simplified and schematized from the prior art known hydraulic unit 1 for needs-based supply of up to two hydraulically driven

The hydraulic unit 1 has two pressure connections or outlets 2 and 3 and can have a first rescue device 4, for example in the form of a rescue shears, on the left in FIG Spreading cylinder or a spreading device. In Fig. 1, a second rescue device 5 is shown with dashed lines, which can be connected to the right-hand pressure outlet 3. The rescue devices 4, 5 each have a fluid supply 6, through which the volume flow provided by the pressure connections 2, 3 is fed in, and each also has a fluid return line 7, with which a volume flow is fed back to the hydraulic unit 1. Details of the fluid return 7 on the rescue equipment 4, 5 and on the hydraulic unit 1 are not shown or explained in detail at this point; only simple return lines are required for this. To control the volume flow at the rescue devices 4, 5, these are equipped, for example, with 4/3-way valves, with which circulation of the hydraulic fluid at a low pressure level is possible in the basic position of the valve when the valve is idling, and two different directions of movement of the rescue devices 4 in the other valve positions , 5 can be selected.

To supply the pressure connections or outlets 2, 3, the hydraulic unit 1 comprises two hydraulic circuits 8 and 9, indicated by dot-dash lines, from which hydraulic fluid 10 is removed from a fluid container 11 and fed to the pressure outlets 2, 3. The first hydraulic circuit 8 includes a first pump assembly 12, which consists of at least two pump elements 13 and 14. Similarly, the second hydraulic circuit 9 includes a second pump arrangement 15 which includes 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 pumping elements 13, 14, 16, 17 and possibly further pumping elements can be designed as part of a hydraulic pump in the form of a radial piston pump, axial piston pump or similar types of pump with several displacement elements.

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

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

Basically, 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 outlet 2 for the first rescue device 4, and analogously at the second pressure outlet 3 for the second rescue device 5 the volume flow of the second Pump assembly 15, so the second pumping elements 16 and 17 is provided. If no rescue device 4, 5 is connected to one of the pressure outlets 2, 3, it must be ensured by measures known from the prior art that the volume flows generated by the pump elements 13, 14, 16, 17 can be returned to the fluid container without damaging the hydraulic unit 1 11 are supplied. This can be, for example, a pressure relief valve upstream of the pressure connections 2, 3, which is actuated manually or automatically and the volume flows are fed to the pressure outlets 2, 3 only after a rescue device 4 or 5 has been connected to it or these.

The converted in a hydraulic circuit 8 or 9 power 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 motor 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 subject to an upper limit at a specific pressure. If there is little back pressure from the connected rescue device 4 or 5 , the volume flow is additionally limited by the maximum drive speed of the drive motor 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 assemblies 12, 15 deliver a largely constant total flow rate and this must be divided into volume flows with different pressure levels, adapted to the available drive power.

It is known from the prior art to provide a possibility in a generic hydraulic unit 1 to divert the volume flow available in one hydraulic circuit 8 or 9 at least partially into the other hydraulic circuit 9 or 8, whereby the power of the drive motor 18 can be better utilized and a volume flow can be used at a pressure outlet 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 outlets 2 or 3 because no rescue device is connected or the rescue device is in an inactive state, an increased volume flow can be made available at the other pressure outlet, which means that with a rescue device connected to it increased working speeds or effective forces can be achieved.

For this 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 is connected via a first connecting line 27 to a second fluid line 24 in the second hydraulic circuit 9 can be. A second directional valve 28 is also arranged in the second hydraulic circuit 9 in a second fluid line 24 and the second fluid 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 valves that are manually operated and a manual switching process is required for the needs-based assignment of the volume flows. In practice, hydraulic units known from the prior art are handled in such a way that an operator handling a rescue device issues appropriate commands to a machine operator on the hydraulic unit. In the prior art, therefore, a separate operator is required for the need-based allocation of the volume flows to the rescue equipment.

In a hydraulic unit 1 according to the invention no separate operator is required for the needs-based allocation of flow rates after the directional control valves 26 and 28 perform automated switching operations.

For this purpose, the directional valves 26, 28 have a spring 30, 31 acting in the direction of an initial position and also include an actuating element 32, 33, with which the volume flow is either fed to the respective pressure outlet 2 or 3 or via the connecting line 27 or 29 is diverted to the other hydraulic circuit 9 or 8 respectively. The first actuating member 32, which acts on the first directional valve 26, is actuated 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 33, which acts on the second directional valve 28, is actuated via a control line 35, which in in this exemplary embodiment runs from the first hydraulic circuit 8 to the actuating element 33 .

In the illustrated embodiment, the switching position of the directional control valve 26 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 respective other hydraulic circuit is transmitted to the actuator of the directional control valve of the other hydraulic circuit. With such a hydraulic unit 1, the volume flow provided at a pressure outlet 2 or 3 can be increased by the volume flow of a pump element 17 or 14 of the other hydraulic circuit 9 or 8, whereby the working speed of a connected rescue device 4 or 5 can be increased. without a manual adjustment of the directional 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. 9 are transmitted and the switching operations explained above can be effected.

If, for example, the rescue 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 routed at a low pressure level to the switching valve of the rescue cylinder and from there back to the fluid tank 11 . When the rescue ram is retracted or extended without a load, there is only a small working resistance, which is due to the internal friction of the rescue ram and line resistance, and this retraction or extension movement can take place at a comparatively low pressure level of up to around 30 bar. To save time, it should be possible to carry out this retraction or extension movement at the greatest possible speed, and therefore the provision of a large volume flow is advantageous and, due to the relatively low pressure level, the drive motor 18 can also muster the power required for this.

With an external load on the rescue cylinder, 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 rises to up to 700 (1000) bar and the volume flow, which is under high pressure, has to be reduced due to the limited power of the drive motor 18 .

In the case of the hydraulic unit 1 shown in Fig. 1, this can be done, for example, in that when the pressure rises at the pressure outlet 2, only the volume flow of the first pump element 13 is routed to the pressure outlet 2, while the volume flow of the pump element 14 is increased via a pressure-controlled valve to the Example, at a switching pressure of 150 to 250 bar to the fluid container 11 is returned. As a result, the pump element 14 requires only a comparatively small proportion of the drive power of the drive motor 18 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, the initial position of the directional valves 26 and 28, which is brought about by the springs 30 and 31, is such that the volume flow of the pump elements 14 and 17 remains in the respective hydraulic circuit 8, 9 and thus to the pressure outlet 2 or 3 is performed. However, embodiments deviating from this are also possible, as also described below.

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

The actuators 32, 33 can, for. B. 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.

2 shows a schematic of a hydraulic unit 1 designed according to the invention, with those components which are already contained in the embodiment described with reference to FIG. 1 being provided with the same reference symbols. On repetitions of the construction

parts descriptions are therefore largely omitted.

The connectable to the hydraulic unit 1 rescue device 4 is formed in the illustrated embodiment by a hydraulic cutter 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 cutting device 36 depends on which of the working spaces the hydraulic fluid 10 supplied through the fluid supply 6 is routed to by means of a switching valve 37 . The hydraulic fluid 10 displaced from the respective other working chamber is fed back to the hydraulic unit 1 via the fluid return line 7 . When the rescue device 4 is connected, the fluid circuit leads from the pressure outlet 2 via the fluid supply 6 to the rescue device 4 and via the fluid return line 7 back to a return connection 38 and from there via a return line 39 on the hydraulic unit 1 or directly back to the fluid tank 11.

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

The drive motor 18, the pump assemblies 12 and 15 and the fluid lines 20, 21, 23, 24 and the collecting lines 22, 25 correspond to the embodiment described with reference to FIG. 1, but the lines in FIG. 2 are broken lines shown and not, as in Fig. 1, by block arrows.

The embodiment of 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 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 delivered by the pump element 14 is thus diverted to the other hydraulic circuit 9 in the starting position of the directional control valve 26 . Similarly, in the second hydraulic circuit 9 the initial position of the directional control valve 28 is such that the volume flow delivered by the pump element 17 is diverted to the first hydraulic circuit 8 .

Since the pump assemblies 12 and 15 usually have identical delivery rates, this "crossing" of volume flows between the two hydraulic circuits 8 and 9 has no noticeable effect on the volume flows or pressures provided at the pressure outlets 2 or 3 .

The actuating element 32, with which the first directional valve 26 is switched over from the starting position against the action of the spring 30, is in turn activated by a first control line 34, which in this embodiment is however influenced by the prevailing pressure levels in the first hydraulic circuit 8 and namely from the pressure levels in the first collecting line 22 or from the pressure levels in the first fluid line 20, which leads from the pump element 13 to the first pressure outlet 2.

With this embodiment, the first hydraulic circuit 8 fetches the volumetric flow diverted from the pump element 14 to the second hydraulic circuit 9 at a predetermined first pressure increase in the fluid line 20 or collecting line 22 for its own use. 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 control valve 28, if necessary, to its own pressure outlet 3.

In the embodiment according to Fig. 2, the pressure-dependent diversion of the volume flow of the pump element 14 occurs when a predetermined increase in pressure is detected in the first collecting line 22 or at the pressure outlet 2, or alternatively in the first fluid line 20, or a predetermined first pressure threshold is exceeded. In such a case, the actuating element 32 is activated via the first control line 34, in particular is supplied with electrical energy. Analogously, the second actuating element 33 is activated, in particular via the control line 35 with electrical energy, when in the second collecting line 25 or at the second pressure outlet 3, or alternatively in the second fluid line 23, a predetermined pressure rise or a predetermined first

Pressure threshold is detected.

The actuators 32, 33 are here formed by magnetic coils of electromagnetically actuated directional control valves 26, 28. The respectively prevailing pressure levels in the hydraulic circuits 8, 9 or at their pressure outlets 2, 3 are recorded by pressure sensors 40, 41 with electrical sensor interfaces. Each pressure sensor 40, 41 is connected via at least one electrical sensor line 42, 43 to an electronic control device 44 for detecting or evaluating the electrical, pressure-representing signals of the pressure sensors 40, 41. As a result, the control device 44 can detect or determine the hydraulic pressure conditions present in the hydraulic circuits 8, 9 or the hydraulic pressure conditions prevailing at the pressure sensors 40, 41 in each case. Based on an evaluation or control logic implemented in the control device 44 or implemented by the control device 44, as described in detail below, the actuating elements 32, 33 are then controlled, in particular activated or deactivated, via the control lines 34, 35.

As already explained, such a hydraulic unit 1 can be used to supply a rescue device 4, 5 with different pressure levels of the hydraulic fluid 10, with a large volume flow being provided at low pressure and only a small volume flow at high pressure due to the specified power of the drive motor 18 can be. 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 the fluid container 11 by means of a valve (not shown) when the pressure level in the rescue device rises, and thus to reduce the proportion of the delivery volume which is under high pressure.

It is also 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 delivery capacities. At a certain drive intensity of the drive motor 18, for example a reference speed, it can be provided that the pump element 14 has a greater delivery capacity than the pump element 13 and is therefore well suited for supplying a large volume flow at a comparatively low pressure level, while the smaller pump element 13, with its smaller delivery capacity, is optimally suited to providing a comparatively small volume flow at a high pressure level. With regard to the design of such multi-pressure stage pumps, reference is made to the relevant prior art.

A hydraulic unit 1 according to the invention has, for example, the following flow rates, which depend on the respective operating situation. A speed of 3000 rpm, for example, is assumed to be the reference intensity of the drive motor 18 . At this reference intensity, the two pump elements 13 and 16 of the hydraulic circuits 8, 9 each have a flow rate of 0.7 l/min, for example, and the pump elements 14 and 17 each have a flow rate of 2.0 l/min, for example. The pumping elements 13 and 16 can thus be referred to as high-pressure elements 45 and 46, respectively, and the two larger pumping elements 14 and 17 can be referred to as low-pressure elements 47 and 48, respectively.

In one embodiment of the hydraulic unit according to FIG. 2, the following flow rates result when using two rescue devices 4, 5. If two rescue devices 4, 5 are each connected to one of the pressure connections 2, 3, they are idle at one Flows through a pressure level of, for example, up to about 20 bar. The volume flow delivered by the pump elements 13, 17 totaling 2.7 | to disposal. The second rescue device 5 is also supplied with a volume flow of 2.7 l/min from the pressure outlet 3 .

If, for example, an adjustment movement is initiated on the rescue device 4 with little resistance, the pressure rises to over 20 bar, as a result of which a switching signal is sent to the first directional control valve 26 via the control line 34 and the volume flow of the pump element 14 is diverted to the first hydraulic circuit 8 or retrieved, and as a result a flow rate of 4.7 l/min is available at the first pressure outlet 2. As a result, if only the rescue device 4 is activated, this can achieve a significantly higher working speed. If, for example, the rescue device 5 is also activated when the working resistance is low,

due to the increase in pressure in the second fluid line 23 or in the collecting line 25, a switching signal is transmitted to the second directional control valve 28 via the control line 35, as a result of which the switching process is effected by the actuating member 33. As a result, the volume flow supplied by the pump element 17 is diverted or retrieved to the second hydraulic circuit 9 and, in this operating state, the rescue devices 4, 5 in turn have 2.7 l/min of flow rate available, as in idling operation. The increased working speed of the rescue devices 4 and 5 can therefore always be used automatically if only one of the rescue devices 4, 5 is actuated.

If an even higher working resistance occurs on the rescue device 4, the volumetric flow delivered by the pump element 14 is diverted to the fluid container 11 by means of a valve, not shown in FIG Available with which a flow rate of 0.7 l/min can be made available at pressure outlet 2 at a reference speed of 3000 rpm. The pressure level lies approximately between the changeover pressure of less than 250 bar, which when exceeded causes the volume flow of the pump element 14 to be switched off, and the system pressure of approximately 750 bar to 1000 bar, which is limited upwards by a pressure relief valve.

The great advantage of the specified hydraulic unit 1 is that these switching processes for the need-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 automatically due to the pressure-dependent controlled, electromagnetically actuated directional control valves 26, 28 to be executed.

In the embodiment shown in FIG. 2, the rescue device 4 is supplied with a flow rate of 2.7 l/min from the pressure outlet 2 when idling, which results from a subset of 0.7 l/min from the high-pressure element 45 of the first hydraulic circuit 8 and a partial quantity of 2.0 l/min from the low-pressure element 48 of the second hydraulic circuit 9 . In the event of a pressure increase due to activation of the rescue device 4 with low working resistance, the volume flow of the low-pressure element 47 is also directed to the pressure outlet 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 rescue device 5 is required.

Accordingly, at least one electrohydraulic switching device 49 is configured in the hydraulic unit 1, which has at least one directional control valve 26, 28 for the controllable or automatically controlled accumulation of delivery quantities or volume flows of the first and second pump assemblies 12, 15 and for the controllable or automatically controlled separation or separation of cumulated delivery quantities of the first and second pump arrangement 12 , 15 .

Based on a control logic of the control device 44, this electrohydraulic switching device 49 can be converted into the respective switching states, in particular into idle or initial states and active or actuating states. In addition to the at least one hydraulic-electric pressure sensor 40, 41, this control logic is also influenced by at least one temperature sensor 50 for detecting the respective temperature of the hydraulic fluid 10.

The at least one temperature sensor 50 preferably detects the temperature of the hydraulic fluid located in the fluid container 11, in particular of the hydraulic oil stored therein. However, the at least one temperature sensor 50 can alternatively or additionally also be positioned at other points of the hydraulic unit 1, for example in the area of the lines 20, 23; 22, 25 and/or in the area of the pressure outlets 2, 3. Alternatively or additionally, the at least one temperature sensor 50 for detecting the ambient or air temperature in the area of the hydraulic unit 1 can be provided.

The electronic or electrical control device 44 is connected to the at least one temperature sensor 50 via at least one sensor line 51, so that the temperature values recorded by the temperature sensor 50 are sent to the

Control device 44 are transferrable. As already described above, the control device 44 is also line-connected to the at least one pressure sensor 40, 41.

The electronic control device 44 is set up on the basis of its control logic to (i) a pressure-dependent controlled, in particular an automatically controlled accumulation and cumulative supply of delivery quantities of the first and second pump arrangement 12, 15 to a common pressure outlet 2 or 3, i.e. to one individual hydraulic interface of the hydraulic unit 1, to suppress or prevent or to set inactive and (ii) to suppress or to prevent. Such a suppression or avoidance of a volume flow accumulation between the pump arrangements 12, 15 or an automatic suppression of a volume flow diversion between the two hydraulic circuits 8, 9 and/or an avoidance or suppression of a speed increase of the drive motor 18 takes place by means of the control logic of the Control device 44 above all when the temperature value of the hydraulic fluid detected by the at least one temperature sensor 50 is below a predetermined temperature threshold value for the hydraulic fluid and when at the same time the pressure detected by the at least one pressure sensor 40, 41 at each of the pressure outlets 2, 3 is below a predetermined one Pressure threshold is.

This creates an advantageous, control-technical condition discrimination, which prevents the speed of the drive motor 18 from being automatically increased when the hydraulic fluid is relatively cold, thus having a relatively high viscosity and consequently a relatively high or increased Dynamic pressure in the fluid lines 20, 21; 23, 24 or at the pressure outlets 2, 3. An automatic increase in the speed of the drive motor 18 only takes place when an increased dynamic pressure occurs at one of the pressure outlets 2, 3 or the predetermined pressure threshold value is determined because a connected rescue device 4, 5 is actually actuated by an operator and thus becomes involved increased working resistance results after the hydraulic rescue device 4, 5, a piston must be moved hydraulically within a hydraulic cylinder. In particular, it can be concluded with increased reliability whether at least one rescue device 4, 5 has actually been activated or whether an actuating or working movement is actually required. This increased reliability of the detection can also be achieved under relatively cold ambient conditions, in particular at sub-zero temperatures.

Due to this indirect detection of the activation or actuation state of a rescue device 4, 5, based on the pressure and temperature states of the hydraulic fluid, it is advantageously not necessary to use separate control or signal lines or radio signals from the rescue device 4, 5 to lead towards the hydraulic unit 1 or to transfer and evaluate the hydraulic unit 1. Accordingly, it is sufficient if each of the rescue devices 4, 5 that can be connected to the hydraulic unit 1 is exclusively hydraulically connected to the hydraulic unit 1 or can be exclusively hydraulically coupled to the hydraulic unit 1. This simplifies the construction and reduces the costs of the hydraulic unit 1 and the rescue equipment 4, 5 to be connected to it. In particular, it is not absolutely necessary to provide electrical coupling devices for signal lines and cable connections between the rescue equipment 4, 5 and the hydraulic unit 1 in order to provide status information and/or Transfer power requirements between said entity.

A drive speed adjusting device 52 is formed on the hydraulic unit 1 for automated change, in particular for increasing and reducing the speed of the drive motor 18 as required. This drive speed setting device 52 can be hydraulically actuated or controlled, as is explained, for example, in EP2260210B1. In connection with the electronic control device 44 of the hydraulic unit 1, however, it is expedient if the drive speed adjusting device 52 for the drive motor 18 has an electric actuator for changing a fuel delivery rate or fuel intake rate

of the drive motor 18 includes. However, if the drive motor 18 of the hydraulic unit 1 is formed by an electric motor, the drive speed setting device 52 includes a power-electronic speed controller, in particular a frequency converter.

If the temperature of the hydraulic fluid 11 that can be continuously detected by the temperature sensor 50 is above the predetermined temperature threshold value gradually or from the start, i.e. is relatively warm or sufficiently warm and therefore relatively low-viscosity, the predetermined pressure threshold value can be used for an automatically initiated cumulation of delivery quantities or Volume flows between the pump arrangements 12, 15 can be reduced. Instead of individual threshold values with regard to temperature and/or hydraulic pressure, it is of course also possible within the scope of the invention to provide characteristic diagrams or value ranges in the control logic of control device 44 and to implement them in the switching or evaluation logic of control device 44. In particular, the control logic can also include fuzzy algorithms and/or trend analyses.

The electrical pressure sensors 40, 41 are preferably formed by pressure-voltage converters or by pressure-current converters 53. The current or output value provided by such sensors is a measure of the hydraulic pressures present in each case.

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

3 shows a further and possibly independent embodiment of a hydraulic unit 1, the same reference numbers or component designations as in the previous FIGS. 1 and 2 being used again for the same parts. In order to avoid unnecessary repetitions, reference is made to the description in the previous FIGS. 1 and 2.

In this embodiment, each of the pump assemblies 12, 15 driven by the common drive motor 18 has at least one high-pressure element 45, 46, at least one medium-pressure pump element 54, 55 and at least one low-pressure element 47, 48. Accordingly, the hydraulic unit 1 comprises a three-stage pump assembly 12, 15 for each of the two hydraulic circuits 8, 9.

The electro-hydraulic switching device 49 comprises an electromagnetically actuable directional valve 26 or 28 in each hydraulic circuit 8 or 9. The control device 44, the pressure sensors 40, 41 and the at least one temperature sensor 50 are designed and arranged analogously to FIG .

The drive motor 18 of the hydraulic unit 1 is formed here by a frequency-dependent controllable, speed-variable electric motor 56. The electrical drive energy is provided to the electric motor 56 via a power-electronic drive speed setting device 52, in particular via a frequency converter. The electrical drive energy is preferably provided by an electrochemical accumulator or battery, by a fuel-operated power generator, or by an electrical power supply network. The electronic power control device 52 is line-connected to the control device 44 via at least one control line 57 and thus receives the operating commands or speed specifications for the electric motor 56.

The pump assemblies 12, 15 and the hydraulic switching device 49 are associated with individual check valves 58 in a manner known per se. The hydraulic circuits 8, 9 also include pressure relief valves 59, known per se, for limiting maximum pressures in the hydraulic unit 1 and pressure cut-off valves 60 for implementing predetermined pressure levels within the pump assemblies 12, 15.

The exemplary embodiments show possible variants, it being noted at this point that the invention is not restricted to the specifically illustrated variant embodiments of the same.

Finally, for the sake of order, it should be pointed out that, in order to better understand the structure, some elements are shown not to scale and/or enlarged and/or reduced.

REFERENCE LIST

1 hydraulic unit 31 spring

2 pressure outlet 32 actuator

3 pressure outlet 33 actuator

4 rescue device 34 control line

5 _ rescue device 35 control line

6 fluid supply 36 cutter

7 fluid return 37 switching valve

8 hydraulic circuit 38 return connection

9 hydraulic circuit 39 return line

10 hydraulic fluid 40 pressure sensor

11 fluid reservoir 41 pressure sensor

12 pump assembly 42 sensor line

13 pump element 43 sensor line

14 pump element 44 control device

15 pump assembly 45 high pressure element

16 pumping element 46 high-pressure element

17 pumping element 47 low-pressure element

18 drive motor 48 low pressure element

19 internal combustion engine 49 switching device

20 First fluid line 50 _Temperature sensor

21 First fluid line 51 Sensor line

22 First Manifold 52 Input Speed Adjuster 23 Second Fluid Line 53 — Pressure Current Transducer

24 Second fluid line 54 Medium-pressure pump element 25 Second collecting line 55 _Medium-pressure pump element 26 First directional control valve 56 Electric motor

27 First connection line 57 Control line

28 Second directional control valve 58 Check valve

29 second connecting line 59 _pressure relief valve 30 spring 60 pressure cut-off valve

Claims (8)

patent claims 1. Hydraulic unit (1) with a first and at least one further pressure outlet (2, 3) for selectively supplying an individual hydraulically drivable rescue device (4; 5) at one of the pressure outlets (2, 3) with pressurized hydraulic fluid, or for the simultaneous supply of several hydraulically drivable rescue devices (4, 5) at the pressure outlets (2, 3) with pressurized hydraulic fluid, comprising - a first hydraulic circuit (8) with a first pump arrangement (12) comprising at least one high-pressure pump element (13) and at least one low-pressure pump element (14) with mutually different delivery rates, from which first pump arrangement (12) fluid lines lead to the first pressure outlet (2), - a second hydraulic circuit (9) with a second pump arrangement (15) comprising at least one high-pressure pump element (16) and at least one low-pressure pump element (17) with mutually different delivery rates, from which second pump arrangement (15) there are fluid lines to the at least one other Lead pressure outlet (3), - A drive motor (18) with variable speed in the form of an internal combustion engine (19) or an electric motor (56) for jointly coupled driving of the first and second pump arrangement (12, 15), - at least one hydraulic switching device (49) with at least one directional control valve (26, 28) for the controllable cumulation of delivery quantities of the first and second pump arrangement (12, 15) and for the controllable separation of cumulative delivery quantities of the first and second pump arrangement (12, 15), characterized in that at least one temperature sensor (50) for detecting the temperature of the hydraulic fluid ability is trained that at least one pressure sensor (40, 41) for detecting hydraulic pressure conditions are formed on the first and the at least one further pressure outlet (2, 3). is, and that an electronic control device (44) is formed, which with the at least one Temperature sensor (50) and the pressure sensors (40, 41) is connected, the electronic cal control device (44) is set up to (i) to suppress or to set inactive a pressure-dependent controlled accumulation and cumulative supply of delivery quantities of the first and second pump arrangement (12, 15) to a common, individual pressure outlet (2; 3) and (ii) to prevent or disable a hydraulically or electrically controlled, automated speed increase of the drive motor (18), if the temperature value detected by the at least one temperature sensor (50). Hydraulic fluid below a predetermined temperature threshold for the hydraulic liquid and if, in addition, the pressure detected by the at least one pressure sensor (40, 41). Pressure at each of the pressure outlets (2, 3) is below a predetermined pressure threshold. 2. Hydraulic unit according to claim 1, characterized in that the at least one temperature sensor (50) for detecting the temperature of the hydraulic fluid located within a fluid container (11) is provided. 3. Hydraulic unit according to claim 1 or 2, characterized in that a drive speed adjusting device (52) for the drive motor (18) comprises an electric actuator for changing a fuel delivery rate or fuel intake rate of the drive motor (18). 4. Hydraulic unit according to Claim 1 or 2, characterized in that a drive speed setting device (52) for the drive motor (18) comprises a power electronic speed controller, in particular a frequency converter, for a drive motor (18) designed as an electric motor (56). 5. Hydraulic unit according to one of the preceding claims, characterized in that the at least one directional valve (26, 28) of the hydraulic switching device (49) is formed by an electrically controllable solenoid valve which is connected to the control device (44). 6. Hydraulic unit according to Claim 5, characterized in that the control device (44) is set up to detect an activated or inactive state of a rescue device (4, 5) connected to the hydraulic unit (1) in that the control device (44) detects the presence evaluates the idle or active switching state of the hydraulic switching device (49) and pressure signals from the at least one electrical pressure sensor (40, 41). 7. Hydraulic unit according to one of the preceding claims, characterized in that the pressure sensors (40, 41) are each formed by a pressure-voltage or pressure-current converter (53). 8. Hydraulic unit according to one of the preceding claims, characterized in that each of the pump assemblies (12, 15) has at least one high-pressure, one medium-pressure and one low-pressure pump element (45, 46; 54, 55; 47, 48). 3 sheets of drawings