EP2820301A1

EP2820301A1 - Method for operating a hydraulic pump arrangement, and hydraulic pump arrangement

Info

Publication number: EP2820301A1
Application number: EP12708798.9A
Authority: EP
Inventors: Dietmar Lindner; Carsten Sauerbier
Original assignee: Lukas Hydraulik GmbH
Current assignee: Lukas Hydraulik GmbH
Priority date: 2012-02-29
Filing date: 2012-02-29
Publication date: 2015-01-07
Also published as: WO2013127452A1; US20150017021A1; CN104081053A

Abstract

The invention relates to a method for operating a hydraulic pump arrangement of a hydraulic tool that is in particular portable and operates by means of an autonomous power supply or depending on the network, wherein the hydraulic pump arrangement is releasably connected to the hydraulic tool by means of a hose connection and is driven by an electrical power source powered, and a load-dependent control of the hydraulic pump takes place by switching from a loaded state to a non-loaded state and vice versa, wherein furthermore a first higher electrical power supply is implemented for the loaded state and a second lower electrical power supply is implemented for the non-loaded state. In order to achieve the aim of providing a novel method for operating a hydraulic pump arrangement and a novel hydraulic pump arrangement which ensures a saving of energy and problem-free operation even in different system pressure conditions, the invention relates to a method that is characterised in that a control variable (S) is fixed for the load-dependent control of the hydraulic pump arrangement, which variable is dependent as an input value on the work to be performed by the motor of the hydraulic pump arrangement, a first threshold value (W1) at which switching from the non-loaded state to the loaded state takes place is assigned to the control variable (S), and a second threshold value (W2) at which switching from the loaded state to the non-loaded state takes place is assigned to the control variable (S).

Description

Method for operating a hydraulic pump arrangement and hydraulic pump arrangement

The present invention relates to a method for operating a hydraulic pump arrangement according to the preamble of claim 1 and to a hydraulic pump arrangement according to the preamble of claim 9.

Technological background

Hydraulic pump assemblies of the type previously described are used for a variety of applications. They are usually portable and therefore equipped with a self-sufficient power source such as a battery or the like. On the one hand, they serve as part of hydraulically driven rescue tools such as so-called spreaders or cutting tools, which are used by emergency personnel to rescue people trapped or spilled in vehicle wrecks. On the other hand, you will also find application in the tool technology z. B. for crushing scrap parts, etc. In general, the switching valves for operating the hydraulically driven tools are located directly on the tool, so that the operator can control the tool via the switching valve as needed directly. The necessary for the drive hydraulic pump assemblies are therefore usually associated with the individual tools via flexible hydraulic hoses in connection. Depending on the application situation, hydraulic hoses may have different lengths and thus create different pressure conditions. Furthermore, there are different rescue tools for different situations of use, which may need to be changed on site if the situation requires it. Different rescue tools in turn establish different energy levels z. For example, different idle pressures. To extend the operating times of the tools like, one strives to extend the service life of the energy source as possible. Therefore, in the past, it has been adopted to provide energy-saving modes. Such an energy-saving mode takes place, for example, by switching over from a load state to a non-load state (switching of the operating state), as long as the tool no longer has to carry out any work.

PRIOR ART US Pat. No. 5,678,982 discloses a portable hydraulic system according to the preamble of claim 1. This hydraulic system already has a control of the operation in a load state or non-load state with the aid of a switch, which switches depending on a pressure threshold between the load state and non-load state. This pressure threshold is set by an absolute pressure and by a pressure sensor, which picks up the pressure at the pump outlet and activates a changeover switch. Depending on the absolute pressure detected by the pressure sensor at the output of the pump, the changeover switch is actuated and the system is switched from a non-load state to a load state or vice versa. This known hydraulic system worked well as long as long as its constituent parts, namely the hydraulic pump arrangement, the hose line and the tool, are matched to one another. When replacing tools with different idle pressures and / or when using different hose lengths but it comes to malfunction.

Object of the present invention

The object of the present invention is to provide a new method for operating a hydraulic pump arrangement as well as a new hydraulic pump arrangement. On the one hand to provide a saving of energy on the other hand ensures trouble-free operation even under different system pressure conditions.

Solution of the task

The present object is achieved in the generic method by the features of the characterizing part of claim 1 and in the generic hydraulic pump order by the features of the characterizing part of claim 9. Advantageous embodiments of the inventive method and the hydraulic pump assembly according to the invention are claimed in the dependent claims. Characterized in that as control variable S at least one input variable is set for the control, which is dependent on the work to be done by the motor of the hydraulic pump assembly malfunctions due to changing pressure conditions with variation of the hose length, when changing tools, with temperature fluctuations, etc. effectively excluded, because the relevant control variable is directly dependent on the work to be performed by the engine. First and second thresholds Wl and W2 are different. In particular, the first threshold value Wl is lower than the second threshold value W2. The control makes it possible even when stopping the movement of the tool under load, for example, when the emergency physician in a vehicle trapped person still needs a little more space for care and the rescue tool (for example, a spreader) must therefore be implemented again, Change from the load state to the non-load state and make a subsequent switch from the non-load state to the load state in a further movement of the tool under load. Advantageously, for load-dependent control of the hydraulic pump assembly in particular also two control variables Sl and S2, z. As the motor current and the pressure to be set, both of which are dependent on the inputs to be performed by the engine of the hydraulic pump assembly, the first control variable Sl (motor current) is assigned a first threshold value Wl, wherein a switch from the non-load state in the load state takes place and the control variable S2 is assigned a second threshold value W2, at which a changeover from the load state to the no-load state takes place. As a result, in the case of signal resolution problems of one control variable, the other control variable can be used as an auxiliary variable and vice versa. This allows a more precise switching.

In that the second threshold is preferably a variable value that continuously updates during operation of the hydraulic pump assembly, i. is overwritten in a memory, the operation of the hydraulic pump assembly adapts to multiple operating situations.

According to an expedient embodiment of the method according to the invention, the control variable S is preferably also associated with a third threshold value W3, with a changeover from the load state to the non-load state as a function of both the second threshold value W2 and the third threshold value W3. This avoids switching too quickly from the load state to the no-load state.

The third threshold value W3 is preferably a fixed value of the control variable S.

Appropriately, as the control variable S, the motor current is used, ie the power consumption of the motor of the hydraulic pump, which is a measure of the from Engine represents the hydraulic pump assembly to be performed work. The determination of the motor current can be done in different ways.

As an alternative, the pressure or the engine torque can also be used as control variable S.

In all cases, these are preferably time-related values, ie values that represent the change in the control variable S over a predetermined time interval.

Appropriately, the hydraulic pump device according to the invention detects the motor current by measuring a voltage drop across a resistor, whereupon the value of the motor current can be concluded. Alternatively, a current measuring device, such as an ammeter or the like may be provided for measuring the current in the motor line.

The memory is expediently a rewritable memory of the type RAM or EEPROM.

When load is reduced, the speed of the motor is reduced by changing the motor voltage in its speed. For this purpose, a voltage is applied to the motor as a voltage pulse, preferably with a constant pulse height, ie intensity, but different pulse width. The voltage is thus modulated. The current adjusts due to the external load. Description of the invention with reference to embodiments

Advantageous embodiments of the invention are explained below with reference to drawing figures. Show it:

Fig. 1 is a schematic representation of a first embodiment of the present invention; Fig. 2 is a flowchart of the control of the hydraulic pump assembly according to the embodiment of Fig. 1;

Fig. 3 is a diagrammatic representation of the course of the motor current of the hydraulic pump assembly of FIG. 1;

4 shows a further diagrammatic representation of the course of the motor current of the hydraulic pump arrangement according to FIG. 1 with a break in work;

5 shows a schematic illustration of a further embodiment of the present invention;

Fig. 6 is a schematic representation of the use of the hydraulic pump assembly according to the invention at different hose lengths and Fig. 7 is a schematic representation of the use of the hydraulic pump assembly according to the invention in various types of hydraulic tools.

The reference numeral 1 denotes the hydraulic pump arrangement according to the invention in its entirety. It is portable and is preferably flexible Hose lines 15 with a replaceable hydraulic tool 18 in conjunction. For a quick coupling or decoupling of the hydraulic pump assembly clutches 14 bzw.16 may be provided at the output of the hydraulic pump assembly 1 and at the input of the hydraulic tool 18.

The hydraulic pump arrangement 1 comprises a pump 2 and an electric motor 4 which drives the pump 2. The electric motor 4 is supplied with electrical energy by a battery 19 or a power supply unit. The pump 2 has a tank 3 for the hydraulic fluid. From the pump 2, a pressure line and from the tank 3, the tank line from the hydraulic pump assembly 1 leads to the respective clutch 14th

The reference numeral 10, a control device for sequential control of the hydraulic pump assembly 1 is characterized. In particular, it comprises a microcontroller 6, a memory 7, a pulse width modulation generator 8 and an analog / digital converter 9. The abovementioned components are accommodated on a printed circuit board. The microcontroller 6 is preferably connected to a main switch 5 in connection. With the latter, the circuit from the battery 19 to the microcontroller 6 is closed or interrupted. The electric motor 4 may be connected directly to the main switch 5, so that the former is supplied with electrical energy from the battery 19 when turning on the main switch 5.

In particular, according to the present invention, the motor current, that is, the current consumed by the electric motor 4 during the operation of the hydraulic pump assembly is measured as the control variable S for the load switching (switching of the operating state). This was done in the embodiment shown in Fig. 1 expediently with the aid of a resistor 13. The resistor 13 is connected to a signal line 23 to the analog / digital converter 9 in combination. The latter converts the analog signals into digital signals for further signal evaluation. The current detection is preferably carried out indirectly via the voltage drop across the resistor 13. This voltage drop is amplified by the subsequent amplifier 21 and goes through the signal line 23 as an input to the analog-to-digital converter 9. The digital data is processed by the microcontroller 6 and the data in Memory 7 (thresholds from the control logic) matched. From this, the corresponding pulse width is output in the generator 8 for pulse-width modulation and the power transistor 11 (eg, a MOSFET transistor) is switched accordingly. When the power transistor 11 is turned off, the current flows through the freewheeling diode 12 connected in parallel with the motor 4. As it were, the negative pole of the motor 4 is clocked. However, it is also possible that the positive pole is clocked.

The above-described embodiment of the present invention has two operating states namely a load operation and a non-load operation. In load operation, the full electric power (e.g., 24V) is supplied to the electric motor 4, and a reduced electric power (e.g., 2V) under no-load operation. Switching takes place by the control unit 10 by means of the pulse width modulation generator 8, which cooperates with the power transistor 11 as described. The pulse width modulation generator 8 together with the power transistor 11 preferably form continuous, periodic current signals which differ only in their pulse width as a function of the respective load state. In the load state, the pulse width is greater in terms of a unit of time, the pulse width is smaller in the no-load condition.

The respective hydraulic tool 18 comprises a hydraulic cylinder 20, which is connected via a switching valve 17 with the hose lines 15. The switching valve 17 is preferably a so-called 4/3 way switching valve, with which it is possible, the two directions of movement (forward and backward) of the hydraulic cylinder 20 and an idle position (center position the switching valve 17) set. The switching valve 17 is provided for example in the form of a so-called star grip directly on the tool 18.

The functional sequence of the hydraulic pump arrangement 1 according to the invention will be explained in more detail below with reference to FIG. If the hydraulic pump arrangement 1 according to the invention is put into operation by switching on the main switch 5, the electric motor 4 is supplied with electrical energy (in this case, for example, 2V) in the non-load range. At the same time, the current which is consumed by the electric motor 4 is permanently determined in the manner described in the introduction. In this case, a differential current is determined, ie a current difference over a fixed period of time. In the control device 10, a first threshold value Wl is deposited. In the logic of the microcontroller 6, the determined value of the current consumption of the electric motor 4 is compared with the first threshold value Wl. If the determined value of the power consumption is smaller than the first threshold value Wl, the hydraulic pump arrangement remains in the non-load range. If the determined value of the power consumption becomes greater than the first threshold value Wl, the hydraulic pump arrangement switches into the load range. In the load range of the electric motor 4 with a voltage of z. B. 24 V operated. Immediately after the upshift into the load range, the current is determined and stored as a threshold value W2 in memory 7. This overwrites the last value in memory. An individual value, dependent on the actual conditions (temperature, connected hose length, type of rescue device), is thus always stored in the memory 7 after switching to the load range.

In addition, a third threshold W3 is preset in the controller, which represents a fixed value. If the permanently measured, consumed current of the electric motor 4 remains greater than the second threshold value W2 or third threshold value W3, the control remains in load operation. Unless the permanent measured consumed current of the electric motor 4 becomes smaller than the second threshold W2 as well as becomes smaller than the third threshold W3, the controller switches to the non-load operation (2 V). In Fig. 3, the control of the motor drive is plotted against the time axis t plotted against a current curve I. When operating the main switch 5, the electric motor is first supplied with a voltage of 2 volts. After a certain period of time, the control valve 17 is actuated by the operator, whereupon the hydraulic cylinder 20 of the tool 18 moves forward without any external load. Here, the measured current I exceeds the first threshold value Wl, so that the controller 10 switches the operation from 2 V to 24 V. As long as there is no external load on the movement of the tool, the electric motor 4 only needs a substantially constant current (after a certain transient response). As soon as an external load acts on the tool movement, the current required by the electric motor 4 increases sharply until a relaxation due to the completed deformation or the cutting of an object or component or the like occurs. After the control valve 17 has been brought into the neutral position (idle), the current required by the electric motor 4 drops sharply again. As soon as the current becomes smaller than the third threshold value W3 and also becomes smaller than the second threshold value W2, the controller switches to the non-load operation (2 V).

The illustration according to FIG. 4 differs from that according to FIG. 3 in that a work break is set during operation. The break as in Fig.4 can z. B. occur when the operator is unsure, briefly lets go of the star grip, and then continue. -Hereby the control valve 17 is brought by the operator in the neutral position (idle position). The power required by the electric motor 4 drops rapidly. If the power consumption has fallen below both the third threshold value W3 and the second threshold value W2, the controller switches from load mode to the non-ast status. Once the work cycle is resumed, the operator actuates the control valve 17 again, so that the electric motor 4 again draws power. Due to the work break condition, the non-load state is switched back to the load mode, whereby a new threshold value W2 is determined and stored in the memory 7. Since the break in work took place near the vertex of the current curve, a very high threshold value W2 is stored. To avoid immediate switching, the third threshold W3 is provided. Only when the determined motor current has also fallen below the third threshold value W3 does the control switch from the load mode to the non-load state.

From Figure 5, an alternative embodiment of the present invention is known. In contrast to the embodiment according to FIG. 1, this embodiment of the invention has instead of an electrical resistance a current measuring device 22, for example in the form of an ammeter. This current measuring device measures the current in the motor cable. The current measuring device 22 is also connected via a signal line 23 to the analog / digital converter 9 in connection. In the embodiment according to FIG. 5, two further connections T and P are provided.

In addition, in the control of the load and the pressure and / or temperature can be used as an additional control variable z. B is the pressure as a leading variable and the current as an auxiliary to ensure more accurate switching through higher signal resolution. The recording of the temperature allows the use of an additional decision criterion to evaluate the main size. In Fig. 5, this is the inputs T (temperature) and P (pressure) on the analog / digital converter 9 marked.

As shown in FIG. 6, the hydraulic pump arrangement 1 can, depending on the purpose of use, be provided via the clutches 14 or 16 as well as variable hose lengths 15a or 15b may be connected to the same tool 18. By using different hose lengths, the existing pressure conditions in the system change. However, this change in the pressure conditions does not lead to malfunctions, as according to the invention the control of the operation of the hydraulic pump arrangement 1 via the motor current is provided as control variable S and this variable is directly dependent on the work to be performed by the motor of the hydraulic pump arrangement 1.

If the pressure conditions change due to a comparatively longer hose line 15, the motor current also changes. However, this motor current is compared with at least partially variable current thresholds (adaptive control).

The same applies to a replacement of the tools 18a to 18c, as shown in Fig. 7. Again, the operating pressure conditions change. For example, a tool 18a in the form of a cutter has a different idling power consumption than a spreader (tool 1b). These differences are thus included in the control of the hydraulic pump assembly 1 with a. The same applies to a change in the length of the hose lines while changing the type of tool la to lc.

Alternatively, instead of the motor current, the pressure and / or the torque can also be used as control variable S ie control variable. LIST OF REFERENCE NUMBERS

1 hydraulic pump arrangement

2 pump

3 tank

4 engine

5 main switch

6 microcontrollers

7 memory

8 Pulse width modulation generator

9 Anal og / Digital wandl

10 Control information

11 power transistor

12 freewheeling diode

13 resistance

14 clutch

15 hose line

16 clutch

17 switching valve

18 tool

19 battery or power supply

20 hydraulic cylinders

21 amplifiers

22 current measuring device

23 signal line

Claims

PATEN TAN SPRU HE

A method of operating a hydraulic pump assembly of a particular portable, self-powered energy hydraulic tool, wherein the hydraulic pump assembly via a hose connection to the hydraulic tool is detachably connected, is driven by an electric power source and a load-dependent control of the hydraulic pump assembly takes place by a load state in a non-load state and vice versa, wherein further for the load state, a first higher electrical power supply and the Nichtlastzu- state a second lower electrical power supply is made, characterized in that for load-dependent control of the hydraulic pump assembly at least one control variable S is set, which is dependent as an input from the work to be done by the engine of the hydraulic pump assembly,

the control variable S is assigned a first threshold value Wl, at which a switchover from the non-load state to the load state occurs and

optionally the control variable S, a second threshold value W2 is assigned, in which a switchover from the load state to the non-load state.

Method according to claim 1, characterized in that for the load-dependent control of the hydraulic pump arrangement two control variables S 1 and S 2 are defined, which are dependent on the quantities to be performed by the motor of the hydraulic pump arrangement,

the first control variable Sl a first threshold value Wl is assigned, in which a switchover from the non-load state takes place in the load state and

the control variable S2 is assigned a second threshold value W2, at which a changeover from the load state to the non-load state takes place.

A method according to claim 1 or 2, characterized in that after switching on the hydraulic pump assembly but still without movement of the tool, the controller keeps the supply of the motor with energy from the electric power source on the second lower electrical power supply,

the controller switches the supply of the motor with energy from the electrical energy source to the first higher electrical power supply at the beginning of the movement of the tool without external load action, Method according to at least one of the preceding claims, characterized in that when stopping the movement of the tool under load, a switchover from the load state to the non-load state and in continuation of the movement of the tool in turn takes place a switch from the non-load state to the load state.

Method according to at least one of the preceding claims, characterized in that the second threshold value W2 is a variable value and is updated during operation.

Method according to at least one of the preceding claims, characterized in that the control variable S is assigned a third threshold value W3, and a changeover from the load state to the non-load state occurs as a function of the second threshold value W2 and the third threshold value W3.

Method according to at least one of the preceding claims, characterized in that the control variable S is the motor current.

Method according to at least one of the preceding claims, characterized in that the control variable S is the pressure and / or the engine torque.

Method according to at least one of the preceding claims, characterized in that the control variable S is a time-related value.

10. Hydraulic pump device for driving a particular portable hydraulic tool (10) comprising:

a housing (3),

a hydraulic pump (2),

an electric motor (4) for driving the hydraulic pump (2), a coupling device (7) for connecting the hydraulic pump device (1) with flexible connecting lines (8) for supplying the hydraulic tool (10) with hydraulic fluid,

a control device (5) for load-dependent control of the rotational speed of the motor (4), in particular for carrying out the method according to at least one of the preceding claims marked by

Means for detecting at least one control variable S, which is an input variable dependent on the work to be performed by the engine (4) of the hydraulic pump arrangement (1),

Means for comparing the detected control variables S with a first threshold Wl,

optionally means for comparing the detected control variables S with a second threshold W2,

Means for switching the power supply of the motor (4) for a load state or non-load state depending on the detected control variable S.

Hydraulic pump device according to claim 10, characterized in that the control variable S is the motor current and / or the pressure and / or the motor torque.

Hydraulic pump device according to claim 11, characterized in that the means for detecting the motor current, the determination of the voltage drop across a resistor (13) is provided.

13. Hydraulic pump device according to claim 11, characterized in that as means for detecting the motor current, a current measuring device (22) is provided

Hydraulic pump device according to at least one of claims 10 - 13, characterized in that a memory (7) is provided, in which the second threshold value W2 is updated continuously.

15. Hydraulic pump device according to at least one of the claims

10 - 14, characterized in that the control variable S is measured over a time interval.

16. Hydraulic pump device according to at least one of the claims

10 - 15, characterized in that the load state switching of the hydraulic pump assembly is effected by pulse width modulation of the motor voltage.