AT522933A1 - Portable, battery-operated hydraulic power pack for hydraulic rescue tools - Google Patents

Abstract

The invention relates to a portable, battery-operated hydraulic unit (1) for hydraulic rescue tools (4), in particular for spreading and / or scissors tools, and a method for operating such a hydraulic unit (1). The invention comprises a control device (13), at least one hydraulic pump (11), at least a first and a second pressure line (16, 23) which are coupled to a pressure outlet (15) of the hydraulic pump (11), a hydraulic tank (21), at least one battery pack and at least one electric motor (12). Furthermore, a pressure-limiting valve (22) is designed so that, when a maximum pressure is reached in at least one of the pressure lines (16, 23), a hydraulic fluid (17) via the pressure-limiting valve (22) and a return flow line (27) coupled to it into the hydraulic tank ( 21) is returned. In addition, a pressure relief valve status detection (29) is designed to detect the response of the pressure relief valve (22). The control device (13) is designed to never reduce the motor speed of the electric motor (12) below a defined lower limit value as a result of the detection of the response of the pressure limiting valve (22).

Description

raulikaggregats, as indicated in the claims.

Hydraulic rescue tools are known in particular as spreading and / or scissor tools and are typically used by rescue organizations, such as the fire brigade or the technical support service,

but also used by special task forces. In order to achieve a rapid readiness for use of such rescue or deployment tools, efforts are made to make these technical aids portable or portable and thus to implement them as lightweight as possible. In order to enable operation that is independent of power generators or power supply networks, the hydraulic units for activating the hydraulic rescue tools can increasingly be operated by electrochemical energy stores, in particular by accumulators. Battery-operated hydraulic units of the generic type for hydraulic rescue tools, which hydraulic units are intended to be portable or operable by only one person, are available from the applicant in a number of designs. The respective hydraulically operated rescue tools are permanently or interchangeably attached or mounted on the portable, battery-operated hydraulic unit and thus form a one-piece unit or the portable, battery-operated hydraulic units are designed as separate devices and can be connected to the respective rescue tool via hydraulic hose connections. When the hydraulic retainer reaches an end position

management devices or in the event of a blockage due to the operating conditions or if

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Level are maintained.

The task of economical and efficient utilization of the battery life according to the state of the art is usually achieved by structurally complex and expensive load sensing systems. The hydraulic pump always delivers the volume flow that is currently required by the consumer. In addition to their technical complexity, these load-sensing systems also have the disadvantage of high waste heat or high energy consumption and are subject to signs of wear and an associated unsatisfactory service life. The structural complexity of these systems also has disadvantages in terms of weight, which affects their portability.

harms.

The basic technical structure of a generic, previously known hydraulic unit is disclosed, for example, in EP 1 598 555 B1. In this, the hydraulic power, which is made available by a hydraulic pump driven by an electric motor, is limited with electronic control means. A microprocessor calculates a maximum limit current and thus regulates the engine speed and, subsequently, that of the hydraulic pump

generated hydraulic pressure.

EP 2610528 A2 discloses that a control unit estimates a hydraulic pressure of the hydraulic fluid on the basis of a drive current for the engine and a rotational speed of the engine, and estimates it based on this

Hydraulic pressure value executes drive control for the engine.

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meter outside of the electronic control.

DE 102015214006 A1 discloses a method for measuring the pressure that is generated by an electric motor-driven compressor, the change in the mean motor current of the electric motor driving the compressor, which is dependent on the change in pressure at the compressor outlet, being determined and as a pressure-proportional variable for operating the compressor is provided or displayed to a control device in the form of an input variable. Furthermore, the pressure measurement carried out via the mean motor current can also be used to limit the maximum pressure by a control unit.

An additional mechanical pressure limitation is then no longer necessary.

The present invention is based on the object of creating a simple and improved, portable, battery-operated hydraulic unit, in particular to further optimize its running time, so that complex or long rescue operations

sentences can be processed efficiently.

This object of the invention is achieved by a generic hydraulic unit with the characterizing features of claim 1, as well as by a method for operating this hydraulic unit with the characterizing features

len of claim 8 solved.

The invention relates to a portable, battery-operated hydraulic unit for hydraulic rescue tools, in particular for spreading and / or scissor tools

- a control device;

- At least one hydraulic pump;

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- a hydraulic tank for a hydraulic fluid;

- at least one battery pack;

- An electromechanical interface for coupling and uncoupling as required from the at least one battery pack;

- a mechanical-hydraulic interface for connecting the hydraulic rescue tool

- and an electric motor for driving the at least one hydraulic pump. Furthermore, a pressure relief valve is designed, which is arranged in such a way that when a maximum pressure is reached in at least one of the pressure lines, the hydraulic fluid is returned to the hydraulic tank via the pressure relief valve and a return flow line coupled to it, and that a pressure relief valve status detection is designed in order to to detect the response of the pressure relief valve. The control device is designed in such a way that the motor speed of the electric motor

following the detection of the response of the pressure relief valve.

A pressure limiting valve state detection embodied in this way can advantageously contribute to detecting the response of the pressure limiting valve in order to counteract hydraulic power loss and noise and heat emissions. These measures improve the energy efficiency of the hydraulic unit. Rescue operations that are usually time-critical and also burdensome for operators or forensic operations can thus be carried out as professionally as possible. Furthermore, the long

liveliness of the hydraulic unit can be improved.

Furthermore, it can be expedient if a detection means is formed which can detect the response of the pressure limiting valve by detecting the position of a valve body. When a maximum pressure preset in the pressure relief valve via a compression spring is exceeded, a

To press the piston valve against the compression spring and thereby shifts the

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level detection can be achieved.

The position of the valve body can advantageously be detected using an optical motion sensor or Hall sensor. Alternatively, a change in position of the valve body can also be detected by measuring the pressure. With this design, the response of the pressure relief valve is advantageously recognized immediately and without a time delay. Since the detection means are arranged directly on the pressure relief valve according to this version, the detected measurement signals are not or only slightly affected by interfering signals.

influences.

Furthermore, it can be provided that a detection means is formed which can detect the response of the pressure limiting valve by detecting the power consumption of the electric motor. This has the particular advantage that no additional structural unit is required to detect the response of the pressure relief valve. The structural complexity and

the production costs can thus be kept as low as possible.

In particular, it can be provided that a detection means is formed which can detect the response of the pressure limiting valve by detecting the motor current. This detection device is structurally simple to implement, with the motor current usually already being detected in existing systems. In addition, in this special variant, no additional control line is required between the pressure limiting valve, control device and electric motor. Overall, no further components or detection means need to be added, so that the weight of the rescue device does not increase and its

structural complexity does not increase.

An embodiment is also advantageous, according to which it can be provided that a detection means is formed, which detects the response of the pressure relief valve by detecting the torque and the speed of the electric

engine and the engine power that can be calculated from it. This too

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Electric motor is required.

According to a further development, it is possible that a detection means is formed which can detect the response of the pressure relief valve by detecting the flow in the return line after the pressure relief valve. Flow meters are standard measuring devices and can easily be integrated into existing systems. Since the flow can be measured directly after the pressure relief valve, the measuring signal is not or

only slightly falsified by interfering signals.

It can also be useful if a signaling means is designed which can communicate the reduction in engine speed as a result of the response of the pressure relief valve to the operator of the hydraulic rescue tool by means of a signal, preferably an acoustic, optical and / or haptic signal. This further development can contribute to a reduction of the stress on the operator, since it can be communicated directly to him that the rescue device has reached an end position, is blocked, or the available force is no longer sufficient for a work movement. It can also be useful if the signal is repeated at periodic intervals as long as the pressure relief valve responds or the engine speed is reduced.

is adorned.

The invention further relates to a method for operating a portable, battery-operated hydraulic unit for hydraulic rescue tools, in particular for spreading and / or scissors tools, the hydraulic unit comprising the following components:

- a control device;

- At least one hydraulic pump;

- At least a first and a second pressure line, which are coupled to a pressure outlet of the hydraulic pump;

- a hydraulic tank for a hydraulic fluid;

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- An electromechanical interface for coupling and uncoupling as required from the at least one battery pack;

- a mechanical-hydraulic interface for connecting the hydraulic rescue tool

- and an electric motor for driving the at least one hydraulic pump. In addition, it is provided that when a maximum pressure is reached in at least one of the pressure lines, a pressure limiting valve responds, the hydraulic fluid being returned to the hydraulic tank via the pressure limiting valve and a return line coupled to it. The response of the pressure relief valve is detected by means of a pressure relief valve status detection and the engine speed of the electric motor is reduced as a result of the detection of the response of the pressure relief valve from the control line.

This reduction in the engine speed as a result of reaching a maximum pressure, the hydraulic power loss as well as noise and heat emissions are reduced at the same time. This increases the service life of the rescue device that can be achieved. Surprisingly, as an additional effect due to the lower maximum

noise level at the same time reduces the stress on the operator.

Furthermore, it can be provided that the response of the pressure limiting valve is detected by detecting the position of a valve body. If a maximum pressure preset in the pressure relief valve via a compression spring is exceeded, a piston slide begins to press against the compression spring.

This moves the valve body.

The position of the valve body can advantageously be detected using an optical motion sensor or Hall sensor. Alternatively, a change in position of the valve body can also be detected by measuring the pressure. With this design, the response of the pressure relief valve is advantageously recognized immediately and without delay and thus enables a

rapid response of the control device. Since the detection means according to

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the recorded measurement signals are not or only slightly influenced by interfering signals.

According to a special feature, it is possible that the response of the pressure relief valve by recording the power consumption of the electric

tors is detected.

According to an advantageous development, it can be provided that the response of the pressure limiting valve is detected by detecting the motor current. This acquisition method is easy to implement structurally, whereby the motor current is usually already recorded in existing systems. In addition, in this special variant, no additional control line is required between the pressure limiting valve, control device and electric motor. Overall, no further components or detection means have to be added, which means that the weight of the rescue device does not increase and its structural components

xity does not increase.

In particular, it can be advantageous if the response of the pressure limiting valve is detected by detecting the torque and the speed of the electric motor and the engine power that can be calculated therefrom. This detection device can also be implemented in a comparatively simple manner, since here, too, existing detection means can be used and there is no additional control line between the pressure limiting valve, control device and

Electric motor is required.

Furthermore, it can be provided that the response of the pressure limiting valve is detected by detecting the flow in the return line after the pressure limiting valve. Flow meters are standard measuring devices and can easily be integrated into existing systems. Since the flow can be measured directly after the pressure relief valve, the

Measurement signal not or only slightly falsified by interfering signals.

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Work performance leads.

A variant is also advantageous, according to which it can be provided that the defined duration until the engine speed is reduced in the control system.

direction is specified and / or is specified individually or can be specified by a user. This measure enables increased flexibility

quality or adaptability for the operator.

According to a further development, it is possible that the defined duration is preferably between 0.5 s and 2 s. A too rapid action of the control device on the engine speed is often undesirable in order not to restrict the availability of the rescue tool during rescue operations. A too sluggish reaction of the control device is also undesirable in order to react as quickly as possible.

to achieve the desired energy savings.

Furthermore, it can be expedient for the control device to reduce the engine speed by at least 10%, preferably by up to 50% of the previously applied engine speed. With the associated lower power consumption of the motor, energy savings are achieved, with the rescue device still being available with sufficient power for further work movements.

can return to their maximum work performance as quickly as possible.

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In addition, it can be provided that the control device cancels the reduction in the engine speed as soon as the pressure limiting valve no longer responds. This has the advantage that the rescue tool is suitable for rescue operations

is continuously and unrestrictedly available at full capacity.

In a preferred embodiment variant, it is advantageous that the control device never reduces the engine speed below a defined lower limit value, in particular never allows it to fall below 20% of the operating or load speed. This measure is of relevance to safety for the operator, since the engine or hydraulic noise always informs him that the hydraulic unit is running and ready for use. This avoids errors by the operator or even injuries to the operator. As an additional positive effect, this measure improves the response of the hydraulic

Rescue device.

Furthermore, it can be provided that the control device cancels the reduction in the engine speed after a defined period, in which defined period the pressure limiting valve no longer responds. This is advantageous insofar as the rescue tool is always available with full power for the rescue operation and at the same time it is avoided that short-term conditions in which the pressure relief valve does not respond are not incorrectly recognized and

the regulation or control intervenes too quickly.

According to a particular embodiment, it is possible that the defined duration is specified in the control device and / or is specified individually or can be specified by a user. This measure increases the

Ease of use and flexibility.

According to an advantageous development, it can be provided that the defined duration is at least 1 s, preferably at least 100 ms, in particular at least 50 ms. Premature cancellation of the speed reduction by the control device is thus advantageously prevented. So

an undesired renewed response of the pressure relief valve is

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bound. Build-ups with regard to the automatic reduction and increase of the engine speed can thus be kept at bay in a simple manner

will.

In particular, it can be advantageous if the control device is integrated into a control system which is also set up to reduce the speed of the motor when the hydraulic rescue tool is not actuated. As a result, both hydraulic power is saved when the rescue tool is in an idle or idle state or occurs

even if the rescue tool is operated at its performance limit.

For a better understanding of the invention, it will be based on the following

Figures explained in more detail. They each show in a greatly simplified, schematic representation:

Fig. 1 shows an embodiment of a portable, battery-operated hydraulic unit

gregats in perspective;

Fig. 2 shows a further embodiment of a portable, battery-operated hydraulic

raulikaggregats in plan view;

Fig. 3 is a circuit diagram of a first hydraulic scheme with an optical loading

movement sensor on the pressure relief valve;

4 shows a circuit diagram of a second hydraulic scheme with a Hall sensor

at the pressure relief valve;

5 is a circuit diagram of a third hydraulic scheme with an ammeter

for the electric motor;

Fig. 6 is a circuit diagram of a fourth hydraulic scheme with a speed and

Torque measuring device for the electric motor;

Fig. 7 is a circuit diagram of a fifth hydraulic scheme with a flow

knife after the pressure relief valve;

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8 shows a speed / pressure time diagram.

By way of introduction, it should be noted that in the differently described embodiments, the same parts are provided with the same reference symbols 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 symbols or the same component names. The position details chosen in the description, such as above, below, to the side, etc., also relate to the figure immediately described and shown and are these position-

to transfer information correspondingly to the new location in the event of a change in location.

Fig. 1 shows an embodiment of a portable, battery-operated hydraulic unit 1 in a perspective view. The hydraulic unit 1 is connected to a hydraulic rescue tool 4 via a mechanical-hydraulic interface 2, in the illustrated case via a hydraulic hose connection 3. Two battery packs 5 supply the hydraulic unit 1 with power via an electromechanical interface 6. An operator 7 handles the hydraulic rescue tool 4 while the hydraulic unit 1 is positioned in the vicinity. Hydraulic unit 1 and rescue tool 4 together form a retainer

device 8.

In Fig. 2, a further and possibly independent embodiment of a portable, battery-operated hydraulic unit 1 is shown in plan view. The hydraulic unit 1 is connected directly to a hydraulic rescue tool 4 via a mechanical-hydraulic interface 2. A battery pack 5 supplies the hydraulic unit 1 with power via an electromechanical interface 6. Hydraulic unit 1 and rescue tool 4 form a

one-piece rescue device 8.

The rescue tools 4 can be formed by scissors-like cutting or spreading tools or by combined cutting and spreading tools.

Hydraulic cylinders can also be used as rescue tools 4 for

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blocked or trapped people act. The rescue tools 4 or work elements 10 mentioned can also be used by emergency teams for safety

security operations or to fight crime.

A first, simplified circuit diagram with a hydraulic unit 1, an actuating element 9 and a working element 10 is shown in FIG. 3. A hydraulic pump 11 is supplied with power via an electric motor 12, the electric motor 12 being equipped or connected to a control device 13 or, as shown in FIG. 3, being connected to a control device 13 via a control line 31. The control device 13 can in turn be part of a

Control system 14 be.

The hydraulic pump 11 conveys a hydraulic fluid 17 in the direction of the working element 10 via a pressure outlet 15 which is connected to a first pressure line 16. The working element 10 can in particular be a hydraulic rescue tool 4. Between hydraulic pump 11 and working

element 10 is the adjusting element 9, in the illustrated special form of a 4/2

Directional valve 18 positioned. This adjusting element 9 can be designed as shown structurally outside of the hydraulic unit 1, or within the

Hydraulic unit 1 are positioned.

The hydraulic fluid is conducted from the actuating element 9 back into the hydraulic tank 21 via a first return line 19 and a return filter 20. A check valve 47 in a bypass line 48 enables, for example in the event of a blockage of the return filter 20, a brief flow around the return filter 20 in the direction of the hydraulic tank 21.

A mechanical pressure limiting valve 22 is connected to the hydraulic pump 11 via the pressure outlet 15, the first pressure line 16 and a second pressure line 23. When a maximum pressure preset in the pressure limiting valve 22 via a compression spring 24 is exceeded, a piston slide 25 begins to press against the compression spring 24 and thereby displaces a valve body 26.

As a result, the hydraulic fluid 17 is passed through the second pressure line 23

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the open pressure relief valve 22 passed and via a second return flow

line 27 returned to the hydraulic tank 21.

A sensor-based detection means 28 for detecting the state of the pressure limiting valve 29 in the special form of an optical movement sensor 30 is shown on the pressure limiting valve 22. This optical movement sensor 30 detects the response of the pressure relief valve 22 as a result of the displacement movement of the valve body 26. The signal is transmitted via a control line 31 between the movement sensor 30 and the control device 13. The speed of the electric motor 12 is consequently reduced by means of the control device 13. This state continues as long as the pressure limiting

trigger valve 22 responds.

A second, simplified circuit diagram is shown in FIG. 4, the same reference numerals or component designations being used for the same parts as in the previous FIG. 3. In order to avoid unnecessary repetitions, reference is made to the detailed description in the previous FIG.

Referenced.

As an alternative to the solution shown in FIG. 3, a Hall sensor 32 is used as detection means 28 in FIG. 4. This Hall sensor 32 detects the displacement movement of the valve body 26 and subsequently the response of the pressure limiting valve 22 as a result of a pressure change. The speed of the electric motor 12 is reduced via a control line 31 between Hall sensor 32 and control device 13. This state continues as long as the pressure limiting

trigger valve 22 responds.

A third, simplified circuit diagram is shown in FIG. 5, the same reference numerals or component designations being used for the same parts as in the previous FIG. 3. In order to avoid unnecessary repetitions, the detailed description in the preceding Fig. 3 is also referred to.

pointed or referred to.

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As an alternative to the solution shown in FIG. 3, an ammeter 33 is used as the detection means 28 in FIG. 5. The motor current is measured via the ammeter 33, which is arranged on the electric motor 12 or on its power supply lines, and when the pressure relief valve 22 responds, a detectable or characteristic current curve occurs which the control device 13 recognizes. As a result, the speed of the electric motor 12 is reduced by the control device 13. This condition

continues as long as the pressure relief valve 22 responds.

FIG. 6 shows a fourth, simplified circuit diagram, the same reference numerals or component designations being used for the same parts as in the previous FIG. 3. In order to avoid unnecessary repetition, reference is made to the detailed description in the preceding FIG. 3

taken.

As an alternative to the solution shown in FIG. 3, in FIG. 6 the speed and torque of the electric motor 12 are measured via a speed measuring device 34 and a torque measuring device 35. A response of the pressure limiting valve 22 through a characteristic change in output can be detected via the engine output that can be calculated therefrom. The speed of the electric motor 12 is then reduced by the control device 13. This condition

continues as long as the pressure relief valve 22 responds.

FIG. 7 also shows a fifth, simplified circuit diagram, the same reference numerals or component designations being used for the same parts as in the previous FIG. 3. In order to avoid unnecessary repetition, reference is made to the detailed description in the preceding FIG. 3

or referred to.

In the second return line 27, a detection means 28 for detecting the state of the pressure limiting valve 29 in the particular form of a flow meter 36 is formed. This flow meter 36 detects the response of the pressure relief valve 22 as a result of a flow of hydraulic

liquid 17 through this second return line 27. Via a control line 31

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The speed of the electric motor 12 is reduced between the flow meter 36 and the control device 13. This state continues as long as the pressure

limit valve 22 responds.

8 shows a simplified and exemplary speed / pressure time diagram of a possible control scenario. The time axis 38 is shown on the abscissa. The ordinate serves both as the pressure axis 39 and the speed axis 40. At the beginning of the rescue operation, i.e. when the hydraulic unit 1 is switched on, the pressure curve 41 and the speed curve 42 increase. In practice, it is a preferred embodiment if pressure curve 41 and speed curve 42 increase to a defined nominal speed when switched on, so that the required power is available to the operator as quickly as possible at the start of the work process with the hydraulic rescue tool 4. For the sake of simplicity, however, this approach ramp, which is advantageous in practice, has been used in the illustration in FIG.

renounces.

If the pressure curve 41 reaches a maximum pressure value 43 preset in the pressure limiting valve 22, the pressure limiting valve 22 opens. As a result of this opening, there is no further increase in the pressure curve 41. After a defined duration 44, the control device 13 intervenes and reduces the speed to a defined reduction speed 45. If the pressure curve 41 decreases again, for example as a result of a working movement of the rescue tool 4, or if the pressure limiting valve 22 no longer responds, the speed reduction is canceled again by the control device 13 after a further defined duration 46. If work continues to be performed via the rescue tool 4 and pressure is thus reduced, the pressure curve 41 can be increased when the

the speed curve 42 remain constant.

The exemplary embodiments show possible design variants, whereby it should be noted at this point that the invention is not restricted to the specifically illustrated design variants of the same, but rather diverse combinations of the individual design variants with one another are also possible and

this possibility of variation based on the teaching on technical action

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present invention in the ability to operate in this technical field

Specialist lies.

The scope of protection is determined by the claims. However, the description and the drawings are to be used to interpret the claims. Individual features or combinations of features from the different exemplary embodiments shown and described can represent independent inventive solutions. The independent inventive solutions

The basic task can be found in the description.

All information on value ranges in the present description are to be understood in such a way that they include any and all sub-areas thereof, e.g. the information 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 also included , ie all sub-ranges begin with a lower limit of 1 or greater and end at an upper limit of 10 or less, for example 1 to 1.7, or 3.2 to 8.1, or 5.5 to 10.

For the sake of clarity, it should finally be pointed out that, for a better understanding of the structure, some elements are not to scale and / or enlarged

and / or shown reduced.

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18th

List of reference symbols

Hydraulic unit, mechanical-hydraulic interface

hydraulic hose connection

hydraulic rescue tool

Battery pack electromechanical interface

operator

Rescue device

Control element

Working element hydraulic pump electric motor control device control system pressure outlet

first pressure line hydraulic fluid 4/2-way valve

first return line return filter

Hydraulic tank pressure relief valve second pressure line pressure spring

Piston valve

Valve body

27 28 29

30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48

second return line detection center | Pressure relief valve status detection

optical motion sensor control line

Hall sensor

Ammeter tachometer torque meter flow meter time monitoring device time axis

Pressure axis

Speed axis pressure curve Speed curve maximum pressure value

Duration

Reduction speed

Duration

check valve

Bypass line

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Claims (24)

Claims 1. Portable, battery-operated hydraulic unit (1) for hydraulic rescue tools (4), in particular for spreading and / or scissors tools, comprising - a control device (13); - At least one hydraulic pump (11); - At least one first and one second pressure line (16, 23) which are coupled to a pressure outlet (15) of the hydraulic pump (11); - A hydraulic tank (21) for a hydraulic fluid (17); - At least one battery pack (5); - An electromechanical interface (6) for coupling and uncoupling from the at least one battery pack (5) as required; - A mechanical-hydraulic interface (2) for connecting the hydraulic rescue tool (4); - and at least one electric motor (12) for driving the at least one hydraulic pump (11), characterized in that a pressure relief valve (22) is designed, which is arranged such that when a maximum pressure is reached in at least one of the pressure lines (16, 23) the hydraulic fluid (17) via the pressure relief valve (22) and a return flow line (27) coupled to this into the Hydraulic tank (21) is returned, and that a pressure relief valve status detection (29) is designed to detect the response of the pressure relief valve (22), and that the control device (13) is designed in such a way that the motor speed of the electric motor (12) as a result of the detection of the response of the pressure limit valve (22). N2019 / 23400-AT-00 2. Hydraulic unit (1) according to claim 1, characterized in that a detection means (28) is formed, which is arranged to respond to the pressure relief valve (22) by detecting the position of a valve to detect tilkörpers (26). 3. Hydraulic unit (1) according to claim 1, characterized in that a detection means (28) is formed, which is arranged to respond to the pressure relief valve (22) by detecting the power consumption detection of the acquisition of the electric motor (12). 4. Hydraulic unit (1) according to claim 3, characterized in that a detection means (28) is formed, which is arranged to respond to the pressure relief valve (22) by detecting the motor current detect. 5. Hydraulic unit (1) according to claim 1, characterized in that a detection means (28) is formed, which is arranged to respond to the pressure relief valve (22) by detecting the torque and the speed of the electric motor (12) and the motor calculable therefrom - detect performance. 6. Hydraulic unit (1) according to claim 1, characterized in that a detection means (28) is formed, which is arranged to respond to the pressure relief valve (22) by detecting the flow in to detect the return line (27) after the pressure relief valve (22). 7. Hydraulic unit (1) according to one of the preceding claims, characterized in that a signaling means is formed which is designed to reduce the engine speed as a result of the response 21735 N2019 / 23400-AT-00 of the pressure relief valve (22) to the operator (7) of the hydraulic rescue tool (4) by means of a signal, preferably an acoustic, visual one and / or haptic signal to communicate. 8. A method for operating a portable, battery-operated hydraulic unit (1) for hydraulic rescue tools (4), in particular for spreading and / or scissors tools, the hydraulic unit (1) comprising the following components: - a control device (13); - At least one hydraulic pump (11); - At least first and a second pressure line (16, 23) which are coupled to a pressure outlet (15) of the hydraulic pump (11); - A hydraulic tank (21) for a hydraulic fluid (17); - At least one battery pack (5); - An electromechanical interface (6) for coupling and uncoupling from the at least one battery pack (5) as required; - A mechanical-hydraulic interface (2) for connecting the hydraulic rescue tool (4); - and at least one electric motor (12) for driving the at least one hydraulic pump (11), characterized in that when a maximum pressure is reached in at least one of the pressure lines (16, 23), a pressure limiting valve (22) responds, the hydraulic fluid (17) being returned to the hydraulic tank (21) via the pressure limiting valve (22) and a return line (27) coupled to it , and that the response of the pressure relief valve (22) is detected by means of a pressure relief valve status detection (29), and that the motor speed of the electric motor (12) as a result of the detection of the response of the pressure relief valve (22) by the control device (13) is reduced. N2019 / 23400-AT-00 9. The method according to claim 8, characterized in that the response of the pressure relief valve (22) is detected by detecting the position of a valve body (26). 10. The method according to claim 8, characterized in that the response of the pressure relief valve (22) is detected by detecting the power consumption of the electric motor (12). 11. The method according to claim 10, characterized in that the response of the pressure relief valve (22) by detecting the motor current de- is tected. 12. The method according to claim 8, characterized in that the response of the pressure relief valve (22) is detected by detecting the torque and the speed of the electric motor (12) and the engine power that can be calculated therefrom. 13. The method according to claim 8, characterized in that the response of the pressure relief valve (22) by detecting the flow in the Return flow line (27) is detected after the pressure relief valve (22). 14. The method according to any one of claims 8 to 13, characterized in that a time monitoring device (37) in the control device (13) detects the duration (44) of the response of the pressure relief valve (22) and the engine speed is reduced via the control device (13), as soon as one de- defined duration (44) of this state is reached or exceeded. 15. The method according to claim 14, characterized in that the defined duration (44) up to the reduction of the engine speed is specified in the control device (13) and / or is specified individually by a user or can be specified. N2019 / 23400-AT-00 16. The method according to claim 14 or 15, characterized in that the defined duration (44) is between 0.5 s and 2 s. 17. The method according to any one of claims 8 to 16, characterized in that the control device (13) increases the engine speed by at least 10% before- admittedly reduced by up to 50% of the previously existing engine speed. 18. The method according to any one of claims 8 to 17, characterized in that the control device (13) cancels the reduction in the engine speed, so- soon the pressure relief valve (22) no longer responds. 19. The method according to any one of claims 8 to 18, characterized in that the control device (13) never reduces the engine speed below a defined lower limit value, in particular never below 20% of the operating or load speed drops. 20. The method according to any one of claims 8 to 19, characterized in that the control device (13) cancels the reduction of the engine speed after a defined duration (46), within which defined duration (46) the Pressure relief valve (22) has not responded. 21. The method according to claim 20, characterized in that the defined duration (46) is predetermined in the control device (13) and / or by is specified or can be specified individually for a user. 22. The method according to claim 20 or 21, characterized in that the defined duration (46) is at least 1 s, preferably at least 100 ms, ins- particular is at least 50 ms. 23. The method according to any one of the preceding claims, characterized indicates that the control device (13) in a control system (14) 24/35 N2019 / 23400-AT-00 is integrated, which is also set up to reduce the speed of the motor when no manual actuation of a switching or adjusting element (9) on the hydraulic rescue tool (4) or on the hydraulic unit (1) or no manual activation of the hydraulic rescue tool (4) takes place. N2019 / 23400-AT-00