EP2601416B1 - Pressure medium system, in particular hydraulic system - Google Patents
Pressure medium system, in particular hydraulic system Download PDFInfo
- Publication number
- EP2601416B1 EP2601416B1 EP12728408.1A EP12728408A EP2601416B1 EP 2601416 B1 EP2601416 B1 EP 2601416B1 EP 12728408 A EP12728408 A EP 12728408A EP 2601416 B1 EP2601416 B1 EP 2601416B1
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- European Patent Office
- Prior art keywords
- pressure
- fluid
- ist
- fluid pump
- control unit
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B21/00—Common features of fluid actuator systems; Fluid-pressure actuator systems or details thereof, not covered by any other group of this subclass
- F15B21/08—Servomotor systems incorporating electrically operated control means
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
- F15B2211/205—Systems with pumps
- F15B2211/2053—Type of pump
- F15B2211/20546—Type of pump variable capacity
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
- F15B2211/25—Pressure control functions
- F15B2211/251—High pressure control
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
- F15B2211/26—Power control functions
Definitions
- the invention relates to a pressure medium system, in particular a hydraulic system of a clamping device for the mechanical clamping of workpieces or workpiece holders, such as workpiece pallets.
- tensioning devices with a hydraulic system are for example out DE 31 36 177 A1 known and include a hydraulic pump, a pressure sensor and a pressure relief valve and a control unit.
- the hydraulic pump generates the hydraulic pressure required for operating the tensioning device, wherein the hydraulic pump can be driven, for example, by an electric motor.
- the pressure relief valve is arranged between the hydraulic pump and the hydraulic consumer of the tensioning device and returns the hydraulic oil when a predetermined maximum value is exceeded in a hydraulic oil tank to limit the hydraulic pressure to the maximum permitted value.
- This pressure limitation may be required, for example, if the hydraulic pump delivers a larger volume flow due to a disturbance than is required to maintain a predetermined desired value.
- this pressure limitation may also be required if the hydraulic oil trapped in the hydraulic system expands due to heating, which is associated with a corresponding increase in pressure.
- the control unit measures the hydraulic pressure generated by the hydraulic pump by means of the pressure sensor and turns on the hydraulic pump when the hydraulic pressure falls below a predetermined minimum value (cut-in pressure). In the subsequent pressure build-up, the control unit continuously measures the current hydraulic pressure by means of the pressure sensor and switches off the hydraulic pump when the hydraulic pressure measured by the pressure sensor exceeds the predetermined desired value (switch-off pressure). In this way, the hydraulic pressure is maintained in the operation of the clamping system between the minimum value and the desired value.
- FIGS. 5A to 5D show for such a conventional hydraulic system the time profile of the hydraulic pressure ( FIG. 5A ), the on or off state of the hydraulic pump ( FIG. 5B ), the on or off state of the consumer ( FIG. 5C ) and the on or off state of the pressure relief valve ( FIG. 5D ).
- part of the volume flow conveyed by the hydraulic pump has to be discharged via the pressure limiting valve when the hydraulic pressure exceeds the predetermined desired value.
- this pressure limitation is associated with a corresponding power loss of the pressure relief valve.
- the hydraulic pump is usually operated at a high hydraulic pressure near the target value, which is associated with a correspondingly high load on the hydraulic pump and with a correspondingly high energy consumption.
- the hydraulic pump must be turned on again when the hydraulic pressure has dropped below a predetermined minimum pressure.
- the problem here is the fact that this so-called downstream switching of the hydraulic pump does not immediately lead to a pressure increase, which has different causes.
- the motor relay of the hydraulic pump to a certain dead time, whereby the start of the hydraulic pump is delayed.
- the hydraulic pump requires a certain start-up time.
- the hydraulic pressure in the hydraulic system has a time constant and increases linearly after the start of the hydraulic pump. This time delay may cause the downstream of the hydraulic pump to fall below the predetermined minimum pressure.
- the invention is therefore based on the object to provide a correspondingly improved hydraulic system that avoids these disadvantages as much as possible.
- the invention is based on the technical realization that the fluid pump (for example hydraulic pump) still has an inertia-related overrun even after its drive has been switched off, so that the fluid pressure (for example hydraulic pressure) rises somewhat even after the fluid pump has been switched off during the overrun of the fluid pump.
- the fluid pump for example hydraulic pump
- the fluid pressure for example hydraulic pressure
- the invention therefore provides that the fluid pump is already switched off during pressure build-up before the fluid pressure has reached the predetermined desired value. During the subsequent overrun of the fluid pump, the fluid pressure then still rises from the switch-off pressure with a specific follow-up pressure increase in the direction of the predetermined desired value.
- the invention thus utilizes the kinetic energy of the fluid pump, the drive of the fluid pump and / or the fluid column conveyed by the fluid pump.
- this offers the advantage that the fluid pump is less often operated at high fluid pressures near the target value, whereby the fluid pump is spared and consumes less drive energy.
- the invention also offers the advantage that less fluid (for example hydraulic oil) has to be removed via the pressure-limiting valve, whereby the pressure limiting valve is spared and less power loss occurs.
- less fluid for example hydraulic oil
- the cut-off pressure is so dimensioned that the pressure difference between the predetermined desired value and the cut-off pressure is smaller than the caster pressure increase. This means that the fluid pressure after switching off the fluid pump at least still rises up to the predetermined desired value.
- the caster pressure increase should therefore preferably be sufficiently large be to bridge the pressure difference between the cut-off pressure and the target value.
- the cut-off pressure is therefore such that the caster pressure rise exceeds the pressure difference between the cut-off pressure and the predetermined target value by at least 1%, 2%, 5%, 10%, 20%, 50%, 100% or 200% ,
- This offers the advantage that, to bridge the pressure difference between the cut-off pressure and the predetermined target value, the relatively steep initial pressure increase during the overrun is utilized, so that the predetermined setpoint value is established relatively quickly after the fluid pump is switched off.
- the cut-off pressure is therefore preferably such that the lag pressure increase exceeds the pressure difference between the cut-off pressure and the predetermined target value by at most 200%, 100%, 50%, 20%, 10%, 5%, 2% or 1% , This offers the advantage that during the wake of the fluid pump only little excess fluid is obtained, which then has to be removed via the pressure relief valve.
- the invention is not fixed to fixed values. Depending on the stability and characteristics of the hydraulic system There are different values. Preferably, however, the smallest possible value is used within the scope of the invention. This depends on the quality of the calculation, the constancy of the parameters of the hydraulic system and in particular on the rigidity of the system, the reaction rate of the controller and the drive. Desirable values are below 5%.
- the shutdown and / or the connection of the fluid pump or the drive of the fluid pump is pressure-controlled.
- the control unit measures the fluid pressure by means of the pressure sensor.
- the control unit switches off the fluid pump during pressure build-up when the measured fluid pressure exceeds the predetermined cut-off pressure.
- the control unit can turn on the fluid pump again when the measured fluid pressure falls below the predetermined switch-on pressure.
- the caster pressure rise depends not only on the inertia of the fluid pump and its drive, but also on the currently delivered and discharged flow rate. For example, if a large flow rate flows through the consumer, the caster pressure increase is very low. In determining the cut-off pressure, therefore, the current outflow of the fluid pump is preferably taken into account.
- One way to determine the current flow rate of the fluid pump is to measure the pump speed of the fluid pump or derived from the engine control, the flow can then be derived at least approximately from the pump speed.
- Another possibility for determining the current flow rate of the fluid pump is the measurement by means of a volume flow sensor.
- the inertia of the system of fluid pump and its drive is reflected in operation in the time pressure change during pressure build-up, i. in the first time derivative of the fluid pressure.
- a rapid rise in pressure during pressure build-up points to a correspondingly high inertia and a high after-run pressure increase.
- the temporal pressure change is measured during pressure build-up and taken into account as a measure of the inertia of the fluid pump.
- the cut-off pressure during operation of the pressure medium system according to the invention is preferably adapted dynamically to the current operating state. This means that the cut-off pressure is continuously adjusted to the current operating condition (e.g., speed, fluid pressure, pressure rise, etc.).
- the invention is not limited to the above-mentioned formula with regard to the calculation of the switch-off pressure, but in principle can also be implemented with other formulas for calculating the switch-off pressure.
- control unit is structurally integrated into the pressure sensor and generates a shutdown signal for the engine control.
- control unit it is also possible for the control unit to be structurally separate from the pressure sensor and for the pressure sensor to receive a pressure signal as an analog signal.
- the pressure medium system is a hydraulic system.
- the invention can also be implemented in other pressure medium systems, such as in pneumatic systems. All that is decisive is that the fluid pump after its shutdown still has a lag caused by inertia, during which the fluid pressure is still increasing.
- the pressure medium system preferably comprises a consumer which is supplied with pressurized fluid.
- the consumer is preferably a clamping system for the mechanical clamping of workpieces or workpiece holders, such as workpiece pallets.
- clamping systems are known per se and, for example, in DE 31 36 177 A1 described, so that the content of this publication is fully attributable to the present specification.
- the invention also claims protection for fluid systems with other types of consumers.
- Another aspect of the invention is concerned with the problem that the fluid pump at start-up (inertia) has an inertia-related flow, so that the fluid pressure during the flow of the fluid pump does not rise significantly, although the fluid pump is already turned on.
- the reasons for this flow are - as already briefly explained above - on the one hand in the dead time of the motor relay of the fluid pump and on the other in the delayed pressure build-up in the pressure fluid system.
- the invention preferably also provides that the control unit already switches the fluid pump back on when the fluid pressure drops in the switched-off state of the fluid pump, before the fluid pressure has fallen to a predetermined minimum pressure (eg 5% below target pressure), which should not be fallen below ,
- the switch-on pressure (downstream pressure) of the fluid pump is thus preferably greater than the predetermined minimum pressure which should not be undershot.
- the control unit detects the control unit in the off state of the fluid pump by means of a pressure sensor, the temporal change of the fluid pressure.
- the switch-on pressure is then by the control unit preferably in response to the time change of the fluid pressure in the off state of the fluid pump, the
- the switch-on pressure (downstream pressure) is therefore preferably dimensioned such that the fluid pressure does not drop below the predetermined minimum pressure after the fluid pump has been switched on during the flow of the fluid pump.
- FIG. 1 shows a hydraulic system according to the invention with a hydraulic pump 1, which is driven by an electric motor 2 and supplies a mechanical clamping system 3 with the hydraulic pressure required for operation.
- the hydraulic pump 1 is connected on the input side to a hydraulic oil tank 4, from which the hydraulic pump 1 extracts hydraulic oil and pumps it via a check valve RV into a high-pressure region 5, to which the clamping system 3 is connected.
- the hydraulic system has a pressure limiting valve 6, which connects the high-pressure region 5 with the hydraulic oil tank 4.
- the pressure limiting valve 6 is closed in the normal state and opens when the current hydraulic pressure P IST in the high-pressure region 5 exceeds a predetermined maximum value P MAX .
- the hydraulic system has a pressure sensor 7, which measures the current hydraulic pressure P IST in the high-pressure region 5 and forwards it to a control unit 8, which activates a motor control 9 as a function of the measured hydraulic pressure P IST , the control unit 8 selectively switching on the electric motor 2 or turns off.
- control unit 8 When controlling the electric motor 2, the control unit 8 also takes into account the current flow rate Q of the hydraulic pump 1, since the current flow rate Q influences the wake pressure increase. For this purpose, the control unit 8 with a Speed sensor 10 is connected, which detects the rotational speed n of the electric motor 2 and thus also the pump speed. From the pump speed n, the spreader unit 8 then calculates the current flow rate Q of the hydraulic pump 1.
- a pressure reducing valve 11 is provided which branches off between the hydraulic pump 1 and the check valve RV and in the opened state recirculates hydraulic oil into the hydraulic oil tank 4, wherein the pressure reducing valve 11 is actuated by the control unit 8.
- the control unit 8 opens the pressure reducing valve 11 when the target value P SOLL is lowered. This is useful so that the hydraulic pressure P IST quickly drops to the new, lower target value P SOLL.
- the device-specific constants K1, K2 can be determined beforehand in a calibration procedure.
- control unit 8 continuously measures the hydraulic pressure P IST in the high-pressure area 5 by means of the pressure sensor 7 (compare step S2 in FIG. 2 ).
- the control unit 8 then continuously checks whether the measured hydraulic pressure P IST falls below a predetermined switch-on pressure P IN (compare S3 in FIG. 2 ).
- control unit 8 transmits a turn-on signal to the engine controller 9, which turns on the electric motor 2 to increase the hydraulic pressure P IST (see step S4 in FIG. 2 ).
- control unit 8 then continuously checks whether the current hydraulic pressure P IST exceeds the switch-off pressure P OFF (compare step S5).
- control unit 8 sends a switch-off signal to the motor control 9, which subsequently shuts off the electric motor 2 (see step S6).
- the pressure limiting valve 6 continuously checks whether the hydraulic pressure P IST exceeds a predefined maximum value P MAX (compare step S7 in FIG. 2 ).
- the pressure relief valve 6 opens automatically and returns the excess hydraulic oil from the high-pressure area 5 into the hydraulic oil tank 4 in order to prevent a further pressure increase beyond the maximum value P MAX (see step S8 in FIG. 2 ).
- the pressure limiting valve 6 continuously checks whether the hydraulic pressure P IST has fallen below the predetermined desired value P SOLL (compare step S9 in FIG. 2 ).
- the pressure relief valve 6 automatically closes in order to prevent further outflow of hydraulic oil from the high-pressure region 5 into the hydraulic oil tank 4, since the hydraulic pressure P IST would thereby fall further below the predetermined desired value P SOLL ( FIG. see step S10 in FIG. 2 ).
- control unit 8 is arranged in a common housing 11 with the pressure sensor 7.
- FIGS. 6 and 7 illustrate an aspect of the invention, which is based on the problem of inertia-related timing of the hydraulic pump 1.
- the hydraulic pressure P IST after switching on (aftershifting) of the hydraulic pump 1 at the time t ON does not increase again immediately, since the pressure increase is delayed by the dead time of the motor relay of the hydraulic pump 1 and the pressure rise itself requires a certain lead time.
- the invention therefore provides, in this aspect, for the hydraulic pump 1 to be switched on again at a switch-on pressure P ON , which is above the predetermined minimum pressure P MIN , so that the predetermined minimum pressure P MIN is not undershot despite the inertia-related flow of the hydraulic pump 1 ,
- a first step S1 device-specific constants K1, K2 are determined for this purpose, which characterize the pressure rise after switching on the hydraulic pump 1 during the flow of the hydraulic pump 1.
- the minimum pressure P MIN is set, which should not be undershot.
- step S3 the cut-off pressure P OUT is calculated, which leads to a shutdown of the hydraulic pump 1 when the fluid pressure P IST is raised.
- the calculation of the switch-off pressure P OUT has already been explained in detail above, so that in this regard reference is made to the above statements to avoid repetition.
- the fluid pressure P IST is first measured in a step S4.
- the time variation dP / dt is the fluid pressure P IST.
- step S7 is then checked in the loop, whether the measured fluid pressure P IST the calculated Anschalttik P A drops below. If so, the hydraulic pump 1 is turned on in a step S8. Otherwise, the above-mentioned steps S4-S7 are repeated in a loop.
- the subsequent switching in the proposed manner is advantageous because again the kinetic energy of the pump motor unit is utilized and no substantially higher pressure than the target pressure is established.
- a pressure value can be set without too much oil volume was pumped through the pump, which must be removed via a limiting valve again.
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Description
Die Erfindung betrifft ein Druckmittelsystem, insbesondere ein Hydrauliksystem einer Spannvorrichtung zum mechanischen Spannen von Werkstücken oder Werkstückhaltern, wie beispielsweise Werkstückpaletten.The invention relates to a pressure medium system, in particular a hydraulic system of a clamping device for the mechanical clamping of workpieces or workpiece holders, such as workpiece pallets.
Derartige Spannvorrichtungen mit einem Hydrauliksystem sind beispielsweise aus
Die Hydraulikpumpe erzeugt den zum Betrieb der Spannvorrichtung erforderlichen Hydraulikdruck, wobei die Hydraulikpumpe beispielsweise von einem Elektromotor angetrieben werden kann.The hydraulic pump generates the hydraulic pressure required for operating the tensioning device, wherein the hydraulic pump can be driven, for example, by an electric motor.
Das Druckbegrenzungsventil ist zwischen der Hydraulikpumpe und dem hydraulischen Verbraucher der Spannvorrichtung angeordnet und führt das Hydrauliköl beim Überschreiten eines vorgegebenen Maximalwerts in einen Hydrauliköltank zurück, um den Hydraulikdruck auf den zugelassenen Maximalwert zu begrenzen.The pressure relief valve is arranged between the hydraulic pump and the hydraulic consumer of the tensioning device and returns the hydraulic oil when a predetermined maximum value is exceeded in a hydraulic oil tank to limit the hydraulic pressure to the maximum permitted value.
Diese Druckbegrenzung kann beispielsweise erforderlich sein, wenn die Hydraulikpumpe aufgrund einer Störung einen größeren Volumenstrom fördert als zur Aufrechterhaltung eines vorgegebenen Soll-Werts erforderlich ist.This pressure limitation may be required, for example, if the hydraulic pump delivers a larger volume flow due to a disturbance than is required to maintain a predetermined desired value.
Darüber hinaus kann diese Druckbegrenzung aber auch erforderlich sein, wenn sich das in dem Hydrauliksystem eingeschlossene Hydrauliköl aufgrund einer Erwärmung ausdehnt, was mit einem entsprechenden Druckanstieg verbunden ist.In addition, this pressure limitation may also be required if the hydraulic oil trapped in the hydraulic system expands due to heating, which is associated with a corresponding increase in pressure.
Die Steuereinheit misst mittels des Drucksensors den von der Hydraulikpumpe erzeugten Hydraulikdruck und schaltet die Hydraulikpumpe ein, wenn der Hydraulikdruck einen vorgegebenen Mindestwert (Einschaltdruck) unterschreitet. Bei dem anschließenden Druckaufbau misst die Steuereinheit mittels des Drucksensors laufend den aktuellen Hydraulikdruck und schaltet die Hydraulikpumpe aus, wenn der von dem Drucksensor gemessene Hydraulikdruck den vorgegebenen Soll-Wert (Ausschaltdruck) überschreitet. Auf diese Weise wird der Hydraulikdruck im Betrieb des Spannsystems zwischen dem Mindestwert und dem Soll-Wert gehalten.The control unit measures the hydraulic pressure generated by the hydraulic pump by means of the pressure sensor and turns on the hydraulic pump when the hydraulic pressure falls below a predetermined minimum value (cut-in pressure). In the subsequent pressure build-up, the control unit continuously measures the current hydraulic pressure by means of the pressure sensor and switches off the hydraulic pump when the hydraulic pressure measured by the pressure sensor exceeds the predetermined desired value (switch-off pressure). In this way, the hydraulic pressure is maintained in the operation of the clamping system between the minimum value and the desired value.
Die
Dieses bekannte Hydrauliksystem weist verschiedene Nachteile auf, die im Folgenden kurz beschrieben werden.This known hydraulic system has several disadvantages, which will be briefly described below.
Zum Einen muss ein Teil des von der Hydraulikpumpe geförderten Volumenstroms über das Druckbegrenzungsventil abgeführt werden, wenn der Hydraulikdruck den vorgegebenen Soll-Wert überschreitet. Diese Druckbegrenzung ist jedoch mit einer entsprechenden Verlustleistung des Druckbegrenzungsventils verbunden.On the one hand, part of the volume flow conveyed by the hydraulic pump has to be discharged via the pressure limiting valve when the hydraulic pressure exceeds the predetermined desired value. However, this pressure limitation is associated with a corresponding power loss of the pressure relief valve.
Zum Anderen wird die Hydraulikpumpe meist bei einem hohen Hydraulikdruck nahe dem Soll-Wert betrieben, was mit einer entsprechend hohen Belastung der Hydraulikpumpe und mit einem entsprechend hohen Energieaufwand verbunden ist.On the other hand, the hydraulic pump is usually operated at a high hydraulic pressure near the target value, which is associated with a correspondingly high load on the hydraulic pump and with a correspondingly high energy consumption.
Weiterhin besteht das Problem, dass die Hydraulikpumpe wieder eingeschaltet werden muss, wenn der Hydraulikdruck unter einen vorgegebenen Minimaldruck abgefallen ist. Problematisch hierbei ist die Tatsache, dass dieses sogenannte Nachschalten der Hydraulikpumpe nicht sofort zu einem Druckanstieg führt, was verschiedene Ursachen hat. Zum einen weist das Motorrelais der Hydraulikpumpe eine bestimmte Totzeit auf, wodurch sich das Anlaufen der Hydraulikpumpe verzögert. Darüber hinaus benötigt die Hydraulikpumpe aufgrund ihrer Massenträgheit eine bestimmte Anlaufzeit. Zum anderen weist aber auch der Hydraulikdruck in dem Hydrauliksystem eine Zeitkonstante auf und steigt nach dem Anlaufen der Hydraulikpumpe linear an. Diese zeitliche Verzögerung kann beim Nachschalten der Hydraulikpumpe dazu führen, dass der vorgegebene Minimaldruck unterschritten wird.Furthermore, there is the problem that the hydraulic pump must be turned on again when the hydraulic pressure has dropped below a predetermined minimum pressure. The problem here is the fact that this so-called downstream switching of the hydraulic pump does not immediately lead to a pressure increase, which has different causes. On the one hand, the motor relay of the hydraulic pump to a certain dead time, whereby the start of the hydraulic pump is delayed. In addition, due to its inertia, the hydraulic pump requires a certain start-up time. On the other hand, however, also the hydraulic pressure in the hydraulic system has a time constant and increases linearly after the start of the hydraulic pump. This time delay may cause the downstream of the hydraulic pump to fall below the predetermined minimum pressure.
Aus
Ferner ist zum Stand der Technik aus anderen technischen Gebieten hinzuweisen auf
Schließlich ist zum Stand der Technik noch hinzuweisen auf
Der Erfindung liegt deshalb die Aufgabe zugrunde, ein entsprechend verbessertes Hydrauliksystem zu schaffen, das diese Nachteile möglichst weitgehend vermeidet.The invention is therefore based on the object to provide a correspondingly improved hydraulic system that avoids these disadvantages as much as possible.
Die Erfindung beruht auf der technischen Erkenntnis, dass die Fluidpumpe (z.B. Hydraulikpumpe) auch nach dem Abschalten ihres Antriebs noch einen trägheitsbedingten Nachlauf aufweist, so dass der Fluiddruck (z.B. Hydraulikdruck) auch noch nach dem Abschalten der Fluidpumpe während des Nachlaufs der Fluidpumpe etwas ansteigt.The invention is based on the technical realization that the fluid pump (for example hydraulic pump) still has an inertia-related overrun even after its drive has been switched off, so that the fluid pressure (for example hydraulic pressure) rises somewhat even after the fluid pump has been switched off during the overrun of the fluid pump.
Die Erfindung sieht deshalb vor, dass die Fluidpumpe beim Druckaufbau bereits abgeschaltet wird, bevor der Fluiddruck den vorgegebenen Soll-Wert erreicht hat. Während des anschließenden Nachlaufs der Fluidpumpe steigt der Fluiddruck dann noch von dem Abschaltdruck mit einem bestimmten Nachlauf-Druckanstieg in Richtung des vorgegebenen Soll-Werts an. Die Erfindung nutzt also die kinetische Energie der Fluidpumpe, des Antriebs der Fluidpumpe und/oder der von der Fluidpumpe geförderten Flüssigkeitssäule aus.The invention therefore provides that the fluid pump is already switched off during pressure build-up before the fluid pressure has reached the predetermined desired value. During the subsequent overrun of the fluid pump, the fluid pressure then still rises from the switch-off pressure with a specific follow-up pressure increase in the direction of the predetermined desired value. The invention thus utilizes the kinetic energy of the fluid pump, the drive of the fluid pump and / or the fluid column conveyed by the fluid pump.
Zum Einen bietet das den Vorteil, dass die Fluidpumpe weniger oft bei hohen Fluiddrücken nahe dem Soll-Wert betrieben wird, wodurch die Fluidpumpe geschont wird und weniger Antriebsenergie verbraucht.On the one hand, this offers the advantage that the fluid pump is less often operated at high fluid pressures near the target value, whereby the fluid pump is spared and consumes less drive energy.
Zum Anderen bietet die Erfindung aber auch den Vorteil, dass weniger Fluid (z.B. Hydrauliköl) über das Druckbegrenzungsventil abgeführt werden muss, wodurch das Druckbegrenzungsventil geschont wird und weniger Verlustleistung anfällt.On the other hand, however, the invention also offers the advantage that less fluid (for example hydraulic oil) has to be removed via the pressure-limiting valve, whereby the pressure limiting valve is spared and less power loss occurs.
In einem bevorzugten Ausführungsbeispiel der Erfindung ist der Abschaltdruck so bemessen, dass die Druckdifferenz zwischen dem vorgegebenen Soll-Wert und dem Abschaltdruck kleiner ist als der Nachlauf-Druckanstieg. Dies bedeutet, dass der Fluiddruck nach dem Abschalten der Fluidpumpe zumindest noch bis auf den vorgegebenen Soll-Wert ansteigt. Der Nachlauf-Druckanstieg sollte also vorzugsweise hinreichend groß sein, um die Druckdifferenz zwischen dem Abschaltdruck und dem Soll-Wert zu überbrücken.In a preferred embodiment of the invention, the cut-off pressure is so dimensioned that the pressure difference between the predetermined desired value and the cut-off pressure is smaller than the caster pressure increase. This means that the fluid pressure after switching off the fluid pump at least still rises up to the predetermined desired value. The caster pressure increase should therefore preferably be sufficiently large be to bridge the pressure difference between the cut-off pressure and the target value.
Hierbei ist zu berücksichtigen, dass der Druckanstieg während des Nachlaufs der Fluidpumpe asymptotisch bis auf einen Endwert verläuft, so dass der Druckanstieg im oberen Druckbereich zu dem Endwert hin immer langsamer erfolgt. Es ist jedoch in der Regel wünschenswert, dass sich der vorgegebene Soll-Wert des Fluiddrucks während des Nachlaufs möglichst schnell einstellt. Vorzugsweise ist der Abschaltdruck deshalb so bemessen, dass der Nachlauf-Druckanstieg die Druckdifferenz zwischen dem Abschaltdruck und dem vorgegebenen Soll-Wert um mindestens 1%, 2%, 5%, 10%, 20%, 50%, 100% oder 200% übersteigt. Dies bietet den Vorteil, dass zur Überbrückung der Druckdifferenz zwischen dem Abschaltdruck und dem vorgegebenen Soll-Wert der relativ steil verlaufende anfängliche Druckanstieg während des Nachlaufs ausgenutzt wird, so dass sich der vorgegebene Soll-Wert nach dem Abschalten der Fluidpumpe relativ schnell einstellt.It should be noted that the pressure increase during the wake of the fluid pump asymptotic runs to a final value, so that the pressure increase in the upper pressure range to the end value takes place behind slower and slower. However, it is usually desirable that the predetermined target value of the fluid pressure during the caster set as quickly as possible. Preferably, the cut-off pressure is therefore such that the caster pressure rise exceeds the pressure difference between the cut-off pressure and the predetermined target value by at least 1%, 2%, 5%, 10%, 20%, 50%, 100% or 200% , This offers the advantage that, to bridge the pressure difference between the cut-off pressure and the predetermined target value, the relatively steep initial pressure increase during the overrun is utilized, so that the predetermined setpoint value is established relatively quickly after the fluid pump is switched off.
Andererseits ist es nicht nötig, dass der Fluiddruck nach dem Abschalten der Fluidpumpe während des Nachlaufs noch wesentlich weiter ansteigt als bis auf den gewünschten Soll-Wert. Der Abschaltdruck ist deshalb vorzugsweise so bemessen, dass der Nachlauf-Druckanstieg die Druckdifferenz zwischen dem Abschaltdruck und dem vorgegebenen Soll-Wert um höchstens 200%, 100%, 50%, 20%, 10%, 5%, 2% oder 1% übersteigt. Dies bietet den Vorteil, dass während des Nachlaufs der Fluidpumpe nur wenig überschüssiges Fluid anfällt, das dann über das Druckbegrenzungsventil abgeführt werden muss.On the other hand, it is not necessary that the fluid pressure after the shutdown of the fluid pump during the caster even further increases as to the desired target value. The cut-off pressure is therefore preferably such that the lag pressure increase exceeds the pressure difference between the cut-off pressure and the predetermined target value by at most 200%, 100%, 50%, 20%, 10%, 5%, 2% or 1% , This offers the advantage that during the wake of the fluid pump only little excess fluid is obtained, which then has to be removed via the pressure relief valve.
Die vorstehend genannten prozentualen Werts sind möglich, wenn man bestimmte Faktoren bei der Berechnung verwendet. Allerdings ist die Erfindung nicht auf feste Werte festgelegt. Je nach Stabilität und Charakteristik des Hydrauliksystems gibt es verschiedene Werte. Vorzugsweise wird im Rahmen der Erfindung jedoch der kleinste mögliche Wert verwendet. Dies richtet sich nach der Güte der Berechnung, der Konstanz der Parameter des Hydrauliksystems und hier insbesondere nach der Steifheit des Systems, der Reaktionsgeschwindigkeit der Steuerung und des Antriebs. Wünschenswert sind Werte unter 5 %.The above percentages are possible when using certain factors in the calculation. However, the invention is not fixed to fixed values. Depending on the stability and characteristics of the hydraulic system There are different values. Preferably, however, the smallest possible value is used within the scope of the invention. This depends on the quality of the calculation, the constancy of the parameters of the hydraulic system and in particular on the rigidity of the system, the reaction rate of the controller and the drive. Desirable values are below 5%.
In dem bevorzugten Ausführungsbeispiel der Erfindung erfolgt die Abschaltung und/oder die Anschaltung der Fluidpumpe bzw. des Antriebs der Fluidpumpe druckgesteuert. Dies bedeutet, dass die Steuereinheit mittels des Drucksensors den Fluiddruck misst. Die Steuereinheit schaltet die Fluidpumpe dann beim Druckaufbau ab, wenn der gemessene Fluiddruck den vorgegebenen Abschaltdruck überschreitet. Darüber hinaus kann die Steuereinheit die Fluidpumpe wieder einschalten, wenn der gemessenen Fluiddruck den vorgegebenen Einschaltdruck unterschreitet.In the preferred embodiment of the invention, the shutdown and / or the connection of the fluid pump or the drive of the fluid pump is pressure-controlled. This means that the control unit measures the fluid pressure by means of the pressure sensor. The control unit switches off the fluid pump during pressure build-up when the measured fluid pressure exceeds the predetermined cut-off pressure. In addition, the control unit can turn on the fluid pump again when the measured fluid pressure falls below the predetermined switch-on pressure.
Bei der Festlegung des Abschaltdrucks ist zu berücksichtigen, dass der Nachlauf-Druckanstieg nicht nur von der Trägheit der Fluidpumpe und ihres Antriebs abhängt, sondern auch von dem aktuell geförderten und abfließenden Förderstrom. Falls beispielsweise ein großer Förderstrom über den Verbraucher abfließt, so ist der Nachlauf-Druckanstieg nur sehr gering. Bei der Festlegung des Abschaltdrucks wird deshalb vorzugsweise der aktuell abfließende Förderstrom der Fluidpumpe berücksichtigt.When determining the cut-off pressure, it must be taken into account that the caster pressure rise depends not only on the inertia of the fluid pump and its drive, but also on the currently delivered and discharged flow rate. For example, if a large flow rate flows through the consumer, the caster pressure increase is very low. In determining the cut-off pressure, therefore, the current outflow of the fluid pump is preferably taken into account.
Eine Möglichkeit zur Ermittlung des aktuellen Förderstroms der Fluidpumpe besteht darin, die Pumpendrehzahl der Fluidpumpe zu messen oder aus der Motorsteuerung abzuleiten, wobei der Förderstrom dann zumindest näherungsweise aus der Pumpendrehzahl abgeleitet werden kann.One way to determine the current flow rate of the fluid pump is to measure the pump speed of the fluid pump or derived from the engine control, the flow can then be derived at least approximately from the pump speed.
Eine andere Möglichkeit zur Ermittlung des aktuellen Förderstroms der Fluidpumpe besteht in der Messung mittels eines Volumenstromsensors.Another possibility for determining the current flow rate of the fluid pump is the measurement by means of a volume flow sensor.
Eine weitere Möglichkeit sieht dagegen vor, dass der Förderstrom der Fluidpumpe als bekannt vorausgesetzt wird.On the other hand, another possibility provides that the flow rate of the fluid pump is assumed to be known.
Die Trägheit des Systems aus Fluidpumpe und deren Antrieb spiegelt sich im Betrieb in der zeitlichen Druckänderung beim Druckaufbau wieder, d.h. in der ersten zeitlichen Ableitung des Fluiddrucks. So deutet ein schneller Druckanstieg während des Druckaufbaus auf eine entsprechend hohe Trägheit und einen hohen Nachlauf-Druckanstieg hin. Vorzugsweise wird deshalb die zeitliche Druckänderung beim Druckaufbau gemessen und als Maß für die Trägheit der Fluidpumpe berücksichtigt.The inertia of the system of fluid pump and its drive is reflected in operation in the time pressure change during pressure build-up, i. in the first time derivative of the fluid pressure. Thus, a rapid rise in pressure during pressure build-up points to a correspondingly high inertia and a high after-run pressure increase. Preferably, therefore, the temporal pressure change is measured during pressure build-up and taken into account as a measure of the inertia of the fluid pump.
Weiterhin ist zu erwähnen, dass der Abschaltdruck im Betrieb des erfindungsgemäßen Druckmittelsystems vorzugsweise dynamisch an den aktuellen Betriebszustand angepasst wird. Dies bedeutet, dass der Abschaltdruck laufend an den aktuellen Betriebszustand (z.B. Drehzahl, Fluiddruck, Druckanstieg, etc.) angepasst wird.It should also be mentioned that the cut-off pressure during operation of the pressure medium system according to the invention is preferably adapted dynamically to the current operating state. This means that the cut-off pressure is continuously adjusted to the current operating condition (e.g., speed, fluid pressure, pressure rise, etc.).
Bei dieser dynamischen Anpassung des Abschaltdruck werden vorzugsweise die folgenden Randbedingungen bzw. Optimierungsziele berücksichtigt:
- Während des Nachlaufs soll der Fluiddruck auf jeden Fall bis auf den vorgegebenen Soll-Wert ansteigen.
- Nach dem Abschalten der Fluidpumpe soll sich der vorgegebene Soll-Wert für den Fluiddruck möglichst schnell einstellen.
- Während des Nachlaufs soll möglichst wenig überschüssiges Fluid-gefördert werden, das zum Erreichen des Soll-Werts nicht erforderlich ist und über das Druckbegrenzungsventil abgeführt werden muss.
- During the overrun, the fluid pressure should in any case rise to the specified target value.
- After switching off the fluid pump, the predetermined target value for the fluid pressure should set as quickly as possible.
- During the overrun, as little excess fluid as possible should be pumped, which is not required to reach the setpoint value and has to be dissipated via the pressure relief valve.
In dem bevorzugten Ausführungsbeispiel der Erfindung wird der Abschaltdruck deshalb nach folgender Formel berechnet und während des Betriebs laufend angepasst:
mit:
- PAUS:
- Abschaltdruck.
- PSOLL:
- Soll-Wert für den Fluiddruck.
- K1:
- Geräteabhängige Konstante, die die Trägheit von Fluidpumpe und Antriebsmotor wiedergibt.
- K2:
- Geräteabhängige Konstante, die Tot- und Verzögerungszeiten von Pumpe, Motor und Steuereinheit wiedergibt.
- PIST:
- Aktueller Fluiddruck.
- dPIST/dt:
- Zeitlicher Druckanstieg.
- Q:
- Förderstrom der Fluidpumpe.
With:
- P OFF :
- Cut-off.
- P SOLL :
- Target value for the fluid pressure.
- K1:
- Device-dependent constant representing the inertia of fluid pump and drive motor.
- K2:
- Device-dependent constant representing dead and delay times of pump, motor and control unit.
- P IS:
- Current fluid pressure.
- dP ist / dt:
- Time pressure increase.
- Q:
- Flow of the fluid pump.
Die Erfindung ist jedoch hinsichtlich der Berechnung des Abschaltdrucks nicht auf die vorstehend genannte Formel beschränkt, sondern grundsätzlich auch mit anderen Formeln zur Berechnung des Abschaltdrucks realisierbar.However, the invention is not limited to the above-mentioned formula with regard to the calculation of the switch-off pressure, but in principle can also be implemented with other formulas for calculating the switch-off pressure.
In einer Variante der Erfindung ist die Steuereinheit baulich in den Drucksensor integriert und erzeugt ein Abschaltsignal für die Motorsteuerung. Es ist aber alternativ auch möglich, dass die Steuereinheit baulich von dem Drucksensor getrennt ist und von dem Drucksensor ein Drucksignal als analoges Signal erhält.In a variant of the invention, the control unit is structurally integrated into the pressure sensor and generates a shutdown signal for the engine control. Alternatively, however, it is also possible for the control unit to be structurally separate from the pressure sensor and for the pressure sensor to receive a pressure signal as an analog signal.
Bei einem Verbraucher kann es notwendig sein, dass der Druck noch einmal nachgeschaltet wird, zum Beispiel, dass sich mit zeitlicher Verzögerung ein Nachsetzen ergibt oder ein kleines Leck auftritt oder dass durch eine starke Abkühlung der Druck sich etwas reduzieren kann. Ein derartiger Nachschaltdruck liegt typischerweise 5-10 % unter dem vorgegebenen Soll-Wert PSOLL, aber über dem Abschaltdruck PAUS. In diesem Fall darf nur eine ganz kleine Fördermenge in das System eingespeist werden und bedarf einer weiteren Ansteuerung, wenn nicht eine überschüssige Ölmenge über das Druckbegrenzungsventil abgelassen werden soll. Für diesen Fall wird die Einschaltdauer des Antriebsmotors der Fluidpumpe ("Druckmotor") so weit reduziert, dass nur die Drehzahl erreicht wird, um einen geringeren Druckaufbau durch Nachlauf zu erzielen. Dies geschieht durch eine Reduzierung der Konstante K1 des Fördervolumens Q und einer proportional dazu reduzierte Anlaufzeit des Pumpenmotorantriebs.In the case of a consumer, it may be necessary for the pressure to be switched on again, for example, that there is a delay or a small leak occurs with a time lag or that the pressure can be reduced somewhat due to a strong cooling down. Such a Nachschaltdruck is typically 5-10% below the predetermined target value P SOLL , but above the cut-off pressure P OUT . In this case, only a very small flow rate may be fed into the system and needs further control, if not an excess amount of oil to be drained through the pressure relief valve. For this case, the duty cycle of the drive motor of the fluid pump ("pressure motor") is reduced so that only the speed is reached to achieve a lower pressure build-up by caster. This is done by reducing the constant K1 of the delivery volume Q and a proportionally reduced startup time of the pump motor drive.
Die im Rahmen der Erfindung verwendeten Begriffe des Ein-bzw. Ausschaltens der Fluidpumpe stellen vorzugsweise darauf ab, dass der Antrieb der Fluidpumpe vollständig an- bzw. abgeschaltet wird. Die Erfindung beansprucht jedoch auch Schutz für Varianten, bei denen der Antrieb der Fluidpumpe lediglich hoch- oder heruntergefahren wird.The terms used in the invention of the input and. Turning Off the fluid pump preferably make sure that the drive of the fluid pump is fully switched on or off. However, the invention also claims protection for variants in which the drive of the fluid pump is merely raised or lowered.
In dem bevorzugten Ausführungsbeispiel der Erfindung handelt es sich bei dem Druckmittelsystem um ein Hydrauliksystem. Die Erfindung ist jedoch auch bei anderen Druckmittelsystemen realisierbar, wie beispielsweise bei Pneumatiksystemen. Entscheidend ist lediglich, dass die Fluidpumpe nach ihrem Abschalten noch einen trägheitsbedingten Nachlauf aufweist, während dessen der Fluiddruck noch ansteigt.In the preferred embodiment of the invention, the pressure medium system is a hydraulic system. However, the invention can also be implemented in other pressure medium systems, such as in pneumatic systems. All that is decisive is that the fluid pump after its shutdown still has a lag caused by inertia, during which the fluid pressure is still increasing.
Weiterhin ist zu erwähnen, dass das erfindungsgemäße Druckmittelsystem vorzugsweise einen Verbraucher umfasst, der mit unter Druck stehendem Fluid versorgt wird. Bei dem Verbraucher handelt es sich vorzugsweise um ein Spannsystem zum mechanischen Spannen von Werkstücken oder Werkstückhaltern wie beispielsweise Werkstückpaletten. Derartige Spannsysteme sind an sich bekannt und beispielsweise in
Ein anderer Aspekt der Erfindung befasst sich mit dem Problem, dass die Fluidpumpe beim Anschalten (Nachschalten) einen trägheitsbedingten Vorlauf aufweist, so dass der Fluiddruck während des Vorlaufs der Fluidpumpe noch nicht wesentlich ansteigt, obwohl die Fluidpumpe bereits angeschaltet ist. Die Gründe für diesen Vorlauf bestehen - wie schon eingangs kurz erläutert - zum einen in der Totzeit des Motorrelais der Fluidpumpe und zum anderen in dem verzögerten Druckaufbau in dem Druckmittelsystem.Another aspect of the invention is concerned with the problem that the fluid pump at start-up (inertia) has an inertia-related flow, so that the fluid pressure during the flow of the fluid pump does not rise significantly, although the fluid pump is already turned on. The reasons for this flow are - as already briefly explained above - on the one hand in the dead time of the motor relay of the fluid pump and on the other in the delayed pressure build-up in the pressure fluid system.
Die Erfindung sieht deshalb vorzugsweise auch vor, dass die Steuereinheit beim Absinken des Fluiddrucks im ausgeschalteten Zustand der Fluidpumpe die Fluidpumpe bereits wieder einschaltet, bevor der Fluiddruck auf einen vorgegebenen Minimaldruck (z.B. 5% unter Soll-Druck) gefallen ist, der nicht unterschritten werden soll. Der Einschaltdruck (Nachschaltdruck) der Fluidpumpe ist also vorzugsweise größer als der vorgegebene Minimaldruck, der nicht unterschritten werden soll. Dies bietet den Vorteil, dass der möglicherweise auftretende weitere Druckabfall während des trägheitsbedingten Vorlaufs der Fluidpumpe nicht dazu führt, dass der vorgegebene Minimaldruck unterschritten wird.Therefore, the invention preferably also provides that the control unit already switches the fluid pump back on when the fluid pressure drops in the switched-off state of the fluid pump, before the fluid pressure has fallen to a predetermined minimum pressure (eg 5% below target pressure), which should not be fallen below , The switch-on pressure (downstream pressure) of the fluid pump is thus preferably greater than the predetermined minimum pressure which should not be undershot. This offers the advantage that the possibly occurring further pressure drop during the inertia-related flow of the fluid pump does not lead to the predetermined minimum pressure being exceeded.
In einem bevorzugten Ausführungsbeispiel der Erfindung erfasst die Steuereinheit im ausgeschalteten Zustand der Fluidpumpe mittels eines Drucksensors die zeitliche Änderung des Fluiddrucks. Der Einschaltdruck wird dann von der Steuereinheit vorzugsweise in Abhängigkeit von der zeitlichen Änderung des Fluiddrucks im abgeschalteten Zustand der Fluidpumpe, demIn a preferred embodiment of the invention detects the control unit in the off state of the fluid pump by means of a pressure sensor, the temporal change of the fluid pressure. The switch-on pressure is then by the control unit preferably in response to the time change of the fluid pressure in the off state of the fluid pump, the
Abschaltdruck und dem vorgegebenen Minimaldruck berechnet, wobei die Berechnung nach folgender Formel erfolgen kann:
mit:
- k1, k2:
- Konstanten, die den Druckverlauf während des Anlaufs der Fluidpumpe beim Nachschalten charakterisieren.
- PAUS:
- Abschaltdruck, der unter Berücksichtigung des Nachlaufs beim Hochfahren des Drucks dazu führt, dass der Drucksollwert PSOLL erreicht wird.
- dP/dt:
- Zeitliche Änderung des Fluiddrucks nach Erreichen des Maximalwertes. Die Steigung ist hierbei negativ, so dass der Nachschaltdruck PEIN größer ist als der vorgegebene Minimaldruck PMIN.
With:
- k1, k2:
- Constants that characterize the pressure curve during startup of the fluid pump when downstream.
- P OFF :
- Cut-off, which leads taking into account the lag during start-up of the pressure to the desired pressure value P SOLL is achieved.
- dP / dt:
- Time change of the fluid pressure after reaching the maximum value. The slope in this case is negative, so that the Nachschaltdruck P ON is greater than the predetermined minimum pressure P MIN.
Der Einschaltdruck (Nachschaltdruck) ist also vorzugsweise so bemessen, dass der Fluiddruck nach dem Anschalten der Fluidpumpe während des Vorlaufs der Fluidpumpe nicht unter den vorgegebenen Minimaldruck abfällt.The switch-on pressure (downstream pressure) is therefore preferably dimensioned such that the fluid pressure does not drop below the predetermined minimum pressure after the fluid pump has been switched on during the flow of the fluid pump.
Ferner ist zu erwähnen, dass die Erfindung auch ein entsprechendes Betriebsverfahren umfasst, wie sich bereits aus der vorstehenden Beschreibung ergibt.It should also be mentioned that the invention also encompasses a corresponding operating method, as already evident from the above description.
Andere vorteilhafte Weiterbildungen der Erfindung sind in den Unteransprüchen gekennzeichnet oder werden nachstehend zusammen mit der Beschreibung der bevorzugten Ausführungsbeispiele der Erfindung anhand der Figuren näher erläutert. Es zeigen:
- Figur 1
- eine schematische Darstellung eines erfindungsgemäßen Hydrauliksystems zur Hydraulikversorgung einer Spannvorrichtung.
Figur 2- das Betriebsverfahren des Hydrauliksystems aus Figur 1 in Form eines Flussdiagramms.
- Figur 3A
- den zeitlichen Verlauf des Hydraulikdrucks in dem Hydrauliksystem gemäß
Figur 1 . - Figur 3B
- den zeitlichen Verlauf des Ein- bzw. Ausschaltzustands der Hydraulikpumpe.
- Figur 3C
- den zeitlichen Verlauf des Ein- bzw. Ausschaltzustands des Spannsystems.
- Figur 3D
- eine vergrößerte Darstellung des Druckverlaufs während des Nachlaufs der Hydraulikpumpe.
- Figur 4
- eine Abwandlung des Hydrauliksystems gemäß
Figur 1 , wobei die Steuereinheit in den Drucksensor integriert ist. - Figur 5A
- den zeitlichen Verlauf des Hydraulikdrucks in einem herkömmlichen Hydrauliksystem.
- Figur 5B
- den zeitlichen Verlauf des Ein- bzw. Ausschaltzustands der Hydraulikpumpe in dem herkömmlichen Hydrauliksystem.
- Figur 5C
- den zeitlichen Verlauf des Ein- bzw. Ausschaltzustands des Spannsystems in dem herkömmlichen Hydrauliksystem.
- Figur 5D
- den zeitlichen Verlauf des Ein- bzw. Ausschaltzustands des Druckbegrenzungsventils in dem herkömmlichen Hydrauliksystem,
Figur 6- den zeitlichen Verlauf des Fluiddrucks in einem erfindungsgemäßen Druckmittelsystem, wobei der trägheitsbedingte Vorlauf der Hydraulikpumpe beim Nachschalten berücksichtigt wird, sowie
Figur 7- ein Flussdiagramm zur Verdeutlichung des Nachschaltens der Hydraulikpumpe zur Berücksichtigung des trägheitsbedingten Vorlaufs der Hydraulikpumpe.
- FIG. 1
- a schematic representation of a hydraulic system according to the invention for the hydraulic supply of a clamping device.
- FIG. 2
- the operating method of the hydraulic system of Figure 1 in the form of a flow chart.
- FIG. 3A
- the time course of the hydraulic pressure in the hydraulic system according to
FIG. 1 , - FIG. 3B
- the time course of the on or off state of the hydraulic pump.
- FIG. 3C
- the time course of the on or off state of the clamping system.
- Figure 3D
- an enlarged view of the pressure curve during the wake of the hydraulic pump.
- FIG. 4
- a modification of the hydraulic system according to
FIG. 1 , wherein the control unit is integrated in the pressure sensor. - FIG. 5A
- the time course of the hydraulic pressure in a conventional hydraulic system.
- FIG. 5B
- the timing of the on or off state of the hydraulic pump in the conventional hydraulic system.
- FIG. 5C
- the timing of the on or off state of the clamping system in the conventional hydraulic system.
- FIG. 5D
- the timing of the on and off states of the pressure relief valve in the conventional hydraulic system,
- FIG. 6
- the time course of the fluid pressure in a pressure medium system according to the invention, wherein the inertia-related Flow of the hydraulic pump is considered when downstream, as well
- FIG. 7
- a flowchart for illustrating the subsequent switching of the hydraulic pump to take into account the inertia-related flow of the hydraulic pump.
Die Hydraulikpumpe 1 ist eingangsseitig mit einem Hydrauliköltank 4 verbunden, aus dem die Hydraulikpumpe 1 Hydrauliköl entnimmt und über ein Rückschlagventil RV in einen Hochdruckbereich 5 pumpt, an den das Spannsystem 3 angeschlossen ist.The hydraulic pump 1 is connected on the input side to a hydraulic oil tank 4, from which the hydraulic pump 1 extracts hydraulic oil and pumps it via a check valve RV into a high-
Darüber hinaus weist das Hydrauliksystem ein Druckbegrenzungsventil 6 auf, das den Hochdruckbereich 5 mit dem Hydrauliköltank 4 verbindet. Das Druckbegrenzungsventil 6 ist im Normalzustand geschlossen und öffnet, wenn der aktuelle Hydraulikdruck PIST in dem Hochdruckbereich 5 einen vorgegebenen Maximalwert PMAX überschreitet.In addition, the hydraulic system has a
Ferner weist das Hydrauliksystem einen Drucksensor 7 auf, der den aktuellen Hydraulikdruck PIST in dem Hochdruckbereich 5 misst und an eine Steuereinheit 8 weiterleitet, die eine Motorsteuerung 9 in Abhängigkeit von dem gemessenen Hydraulikdruck PIST ansteuert, wobei die Steuereinheit 8 den Elektromotor 2 wahlweise anschaltet oder abschaltet.Furthermore, the hydraulic system has a
Bei der Ansteuerung des Elektromotors 2 berücksichtigt die Steuereinheit 8 auch den aktuellen Förderstrom Q der Hydraulikpumpe 1, da der aktuelle Förderstrom Q den Nachlauf-Druckanstieg beeinflusst. Hierzu ist die Steuereinheit 8 mit einem Drehzahlsensor 10 verbunden, der die Drehzahl n des Elektromotors 2 und damit auch die Pumpendrehzahl erfasst. Aus der Pumpendrehzahl n berechnet die Streuereinheit 8 dann den aktuellen Förderstrom Q der Hydraulikpumpe 1.When controlling the
Darüber hinaus ist ein Druckreduzierventil 11 vorgesehen, dass zwischen der Hydraulikpumpe 1 und dem Rückschlagventil RV abzweigt und im geöffneten Zustand Hydrauliköl in den Hydrauliktölank 4 zurückführt, wobei das Druckreduzierventil 11 von der Steuereinheit 8 angesteuert wird. Die Steuereinheit 8 öffnet das Druckreduzierventil 11, wenn der Soll-Wert PSOLL abgesenkt wird. Dies ist sinnvoll, damit der Hydraulikdruck PIST möglichst schnell auf den neuen, geringeren Soll-Wert PSOLL absinkt.In addition, a
Die Steuereinheit 8 berechnet dann während des Betriebs laufend (vgl. Schritt S1 in
mit:
- PAUS
- Abschaltdruck.
- PSOLL:
- Soll-Wert für den Fluiddruck.
- K1:
- Geräteabhängige Konstante, die die Trägheit von Fluidpumpe und Antriebsmotor wiedergibt.
- K2:
- Geräteabhängige Konstante, die Tot- und Verzögerungszeiten von Pumpe, Motor und Steuereinheit wiedergibt.
- PIST:
- Aktueller Fluiddruck.
- dPIST/dt:
- Zeitlicher Druckanstieg.
- Q:
- Förderstrom der Fluidpumpe.
With:
- P OFF
- Cut-off.
- P SOLL :
- Target value for the fluid pressure.
- K1:
- Device-dependent constant representing the inertia of fluid pump and drive motor.
- K2:
- Device-dependent constant representing dead and delay times of pump, motor and control unit.
- P IST :
- Current fluid pressure.
- dP / dt:
- Time pressure increase.
- Q:
- Flow of the fluid pump.
Die gerätespezifischen Konstanten K1, K2 können zuvor in einem Kalibrierungsverfahren ermittelt werden.The device-specific constants K1, K2 can be determined beforehand in a calibration procedure.
Im ausgeschalteten Zustand der Hydraulikpumpe misst die Steuereinheit 8 mittels des Drucksensors 7 laufend den Hydraulikdruck PIST in dem Hochdruckbereich 5 (vgl. Schritt S2 in
Die Steuereinheit 8 prüft dann laufend, ob der gemessene Hydraulikdruck PIST einen vorgegebenen Einschaltdruck PEIN unterschreitet (vgl. S3 in
Falls dies der Fall ist, so sendet die Steuereinheit 8 ein Einschaltsignal an die Motorsteuerung 9, die darauf hin den Elektromotor 2 einschaltet, um den Hydraulikdruck PIST zu erhöhen (vgl. Schritt S4 in
Bei dem anschließenden Druckaufbau prüft die Steuereinheit 8 dann laufend, ob der aktuelle Hydraulikdruck PIST den Abschaltdruck PAUS überschreitet (vgl. Schritt S5).In the subsequent pressure build-up, the
Falls dies der Fall ist, so sendet die Steuereinheit 8 ein Abschaltsignal an die Motorsteuerung 9, die darauf hin den Elektromotor 2 abschaltet (vgl. Schritt S6).If this is the case, the
Bei dem anschließenden trägheitsbedingten Nachlauf der Hydraulikpumpe 1 steigt der Hydraulikdruck PIST trotz des ausgeschalteten Elektromotors 2 noch trägheitsbedingt an, wobei der Nachlauf-Druckanstieg ΔPNACHLAUF (vgl.
Während des Nachlaufs prüft das Druckbegrenzungsventil 6 laufend, ob der Hydraulikdruck PIST einen vorgegebenen Maximalwert PMAX übersteigt (vgl. Schritt S7 in
Falls dies der Fall ist, so öffnet das Druckbegrenzungsventil 6 automatisch und leitet das überschüssige Hydrauliköl aus dem Hochdruckbereich 5 in den Hydrauliköltank 4 zurück, um einen weiteren Druckanstieg über den Maximalwert PMAX hinaus zu verhindern (vgl. Schritt S8 in
Darüber hinaus prüft das Druckbegrenzungsventil 6 laufend, ob der Hydraulikdruck PIST unter den vorgegebenen Soll-Wert PSOLL gefallen ist (vgl. Schritt S9 in
Falls dies der Fall sein sollte, so schließt das Druckbegrenzungsventil 6 selbsttätig, um ein weiteres Abfließen von Hydrauliköl aus dem Hochdruckbereich 5 in den Hydrauliköltank 4 zu verhindern, da der Hydraulikdruck PIST dadurch noch weiter unter den vorgegebenen Soll-Wert PSOLL abfallen würde (vgl. Schritt S10 in
Aus
Das Ausführungsbeispiel gemäß
Eine Besonderheit dieses Ausführungsbeispiels besteht darin, dass die Steuereinheit 8 in einem gemeinsamen Gehäuse 11 mit dem Drucksensor 7 angeordnet ist.A special feature of this embodiment is that the
Die
In einem ersten Schritt S1 werden hierzu gerätespezifische Konstanten K1, K2 ermittelt, die den Druckanstieg nach dem Anschalten der Hydraulikpumpe 1 während des Vorlaufs der Hydraulikpumpe 1 kennzeichnen.In a first step S1, device-specific constants K1, K2 are determined for this purpose, which characterize the pressure rise after switching on the hydraulic pump 1 during the flow of the hydraulic pump 1.
In einem weiteren Schritt S2 wird der Minimaldruck PMIN vorgegeben, der nicht unterschritten werden soll.In a further step S2, the minimum pressure P MIN is set, which should not be undershot.
Darüber hinaus wird in einem Schritt S3 der Abschaltdruck PAUS berechnet, der beim Hochfahren des Fluiddrucks PIST zu einem Abschalten der Hydraulikpumpe 1 führt. Die Berechnung des Abschaltdrucks PAUS wurde bereits vorstehend ausführlich erläutert, so dass diesbezüglich zur Vermeidung von Wiederholungen auf die vorstehenden Ausführungen verwiesen wird.In addition, in a step S3, the cut-off pressure P OUT is calculated, which leads to a shutdown of the hydraulic pump 1 when the fluid pressure P IST is raised. The calculation of the switch-off pressure P OUT has already been explained in detail above, so that in this regard reference is made to the above statements to avoid repetition.
In einer Schleife wird zunächst in einem Schritt S4 der Fluiddruck PIST gemessen.In a loop, the fluid pressure P IST is first measured in a step S4.
Darüber hinaus wird in der Schleife dann in einem Schritt S5 die zeitliche Änderung dPIST/dt des Fluiddrucks PIST berechnet.Moreover, is then computed in the loop in a step S5, the time variation dP / dt is the fluid pressure P IST.
In einem weiteren Schritt S6 wird dann nach folgender Formel der Anschaltdruck PEIN berechnet:
In einem Schritt S7 wird dann in der Schleife geprüft, ob der gemessene Fluiddruck PIST den berechneten Anschaltdruck PEIN unterschreitet. Falls dies der Fall ist, so wird die Hydraulikpumpe 1 in einem Schritt S8 eingeschaltet. Andernfalls werden die vorstehend genannten Schritte S4-S7 in einer Schleife wiederholt.In step S7 is then checked in the loop, whether the measured fluid pressure P IST the calculated Anschaltdruck P A drops below. If so, the hydraulic pump 1 is turned on in a step S8. Otherwise, the above-mentioned steps S4-S7 are repeated in a loop.
Auf diese Weise wird sichergestellt, dass der Fluiddruck PIST trotz des trägheitsbedingten Vorlaufs der Hydraulikpumpe 1 nicht unter den vorgegebenen Minimaldruck PMIN abfällt, der nicht unterschritten werden soll.In this way, it is ensured that the fluid pressure P IST does not fall below the predetermined minimum pressure P MIN despite the inertia-related flow of the hydraulic pump 1, which should not be fallen below.
Das Nachschalten in der vorgeschlagenen Weise ist vorteilhaft, weil wieder die kinetische Energie der Pumpen-MotorEinheit ausgenutzt wird und sich kein wesentlich höherer Druck als der Solldruck einstellt. Somit kann mit einer derartigen Einrichtung ein Druckwert eingestellt werden, ohne dass zuviel Ölvolumen durch die Pumpe gefördert wurde, welches über ein Begrenzungsventil wieder abgeführt werden muss.The subsequent switching in the proposed manner is advantageous because again the kinetic energy of the pump motor unit is utilized and no substantially higher pressure than the target pressure is established. Thus, with such a device, a pressure value can be set without too much oil volume was pumped through the pump, which must be removed via a limiting valve again.
In Kombination mit dem erfindungsgemäßen Abschalten der Pumpe bereits vor Erreichen des Soll-Werts PSOLL ergibt sich ein Druckeinstellsystem, bei dem das Druckbegrenzungsventil 6 nur noch der Sicherheit dient. Die Druckeinstellung wird durch die Veränderung des Soll-Wertes PSOLL vorgenommen.In combination with the switching off of the pump according to the invention, even before the setpoint value P SOLL is reached, a pressure adjustment system results, in which the
Durch die Verwendung des Abschaltdrucks PAUS aus dem erstmaligen Druckanstieg wird etwas mehr Energie in das Hydrauliksystem gegeben, da der Druck nur im System aus der Hydraulikpumpe 1 und dem Druckrohr aufgebaut werden muss und erst nach dem Öffnen des Rückschlagventils RV das gesamte Hydrauliksystem angeschlossen ist.By using the cut-off pressure P OFF from the initial pressure rise slightly more energy is added to the hydraulic system, as the pressure only in the system from the hydraulic pump 1 and the pressure pipe has to be established, and only after the opening of the check valve RV the entire hydraulic system is connected.
Die Erfindung ist nicht auf die vorstehend beschriebenen bevorzugten Ausführungsbeispiele beschränkt. Vielmehr ist eine Vielzahl von Varianten und Abwandlungen möglich, die ebenfalls von dem Erfindungsgedanken Gebrauch machen und deshalb in den Schutzbereich fallen. Darüber hinaus beansprucht die Erfindung auch Schutz für den Gegenstand und die Merkmale der Unteransprüche unabhängig von den in Bezug genommenen Ansprüchen.The invention is not limited to the preferred embodiments described above. Rather, a variety of variants and modifications are possible, which also make use of the concept of the invention and therefore fall within the scope. Moreover, the invention also claims protection for the subject matter and the features of the subclaims independently of the claims referred to.
- 11
- Hydraulikpumpehydraulic pump
- 22
- Elektromotorelectric motor
- 33
- Spannsystemclamping system
- 44
- HydrauliköltankHydraulic oil tank
- 55
- HochdruckbereichHigh pressure area
- 66
- DruckbegrenzungsventilPressure relief valve
- 77
- Drucksensorpressure sensor
- 88th
- Steuereinheitcontrol unit
- 99
- Motorsteuerungmotor control
- 1010
- DrehzahlsensorSpeed sensor
- 1111
- DruckreduzierventilPressure reducing valve
- k1, k2k1, k2
- Konstanten, die den Druckverlauf während des Anlaufs der Fluidpumpe beim Nachschalten charakterisierenConstants that characterize the pressure curve during start-up of the fluid pump when downstream
- K1K1
- Geräteabhängige Konstante, die die Trägheit von Fluidpumpe und Antriebsmotor wiedergibtDevice-dependent constant representing the inertia of fluid pump and drive motor
- K2K2
- Geräteabhängige Konstante, die Tot- und Verzögerungszeiten von Pumpe, Motor und Steuereinheit wiedergibtDevice-dependent constant representing dead and delay times of pump, motor and control unit
- nn
- Drehzahl des ElektromotorsSpeed of the electric motor
- PAUS P OFF
- AbschaltdruckCut-off
- PEIN P ON
- EinschaltdruckCut-in
- PIST P IS
- Hydraulikdruckhydraulic pressure
- PMIN P MIN
- MinimalMinimal
- PMAX P MAX
- Maximaldruckmaximum pressure
- PSOLL P SOLL
- Soll-WertTarget value
- ΔP.DELTA.P
- Druckdifferenz zwischen Abschaltdruck und Soll-WertPressure difference between cut-off pressure and setpoint value
- ΔPNACHLAUF ΔP RUNNING
- Nachlauf-DruckanstiegTrailing-pressure rise
- RVRV
- Rückschlagventilcheck valve
- Förderstrom der HydraulikpumpeFlow rate of the hydraulic pump
- dPIST/dtdP ist / dt
- zeitliche Änderung des Hydraulikdruckstemporal change of the hydraulic pressure
Claims (13)
- A pressure means system, in particular a hydraulic system, witha) a fluid pump (1) for conveying a drive fluid with a certain discharge flow (Q) and a certain fluid pressure (PIST),b) a control unit (8), which switches the fluid pump (1) on or off to adjust a predefined target value (PSOLL) of the fluid pressure (PIST),c) wherein the fluid pump (1) has an inertia-induced overrun during shut-off, so that the fluid pressure still rises during the overrun of the fluid pump (1), while the fluid pump (1) is already switched off,d) while the fluid pump (1) has an inertia-induced pre-run during switching-on, so that the fluid pressure does not yet substantially rises during the pre-run of the fluid pump (1), while the fluid pump (1) is already switched on,
characterized ine) that the control unit (8) switches off the fluid pump (1) when increasing the fluid pressure (PIST) to the predefined target value (PSOLL) before the fluid pressure (PIST) has reached the target value (PSOLL), and/orf) that the control unit (8) switches on the fluid pump (1) again at the drop of fluid pressure (PIST) when the fluid pump (1) is switched off before the fluid pressure (PIST) has fallen to a predefined minimum pressure (PMIN). - The pressure means system according to claim 1, characterized in thata) the fluid pressure (PIST) still rises during the overrun after switching off of the fluid pump (1) without any pressure limitation by a certain maximum possible overrun pressure rise (ΔPNACHLAUF), andb) the control unit (8) switches off the fluid pump (1) when the fluid pressure (PIST) exceeds a certain switch-off pressure (PAUS).
- The pressure means system according to claim 2, characterized in thata) the pressure difference (ΔP) between the predefined target value (PSOLL) of the fluid pressure (PIST) and the switch-off pressure (PAUS) is smaller than the maximum possible overrun pressure rise (ΔPNACHLAUF), so that the fluid pressure (PIST) during the overrun still rises at least up to the predefined target value (PSOLL), and/orb) the maximum possible overrun pressure rise (ΔPNACHLAUF) exceeds the pressure difference (ΔP) between the predefined target value (PSOLL) of the fluid pressure (PIST) and the switch-off pressure (PAUS) by at least 10%, 20%, 50%, 100% or 200%, and/orc) the maximum possible overrun pressure rise (ΔPNACHLAUF) exceeds the pressure difference (ΔP) between the predefined target value (PSOLL) of the fluid pressure (PIST) and the switch-off pressure (PAUS) by at most 200%, 100%, 50%, 20% or 10%.
- The pressure means system according to any one of the preceding claims, characterized in thata) a pressure sensor (7) is provided, which measures the fluid pressure (PIST) and forwards the measured fluid pressure (PIST) to the control unit (8), andb) the control unit (8) switches off the fluid pump (1) depending on the measured fluid pressure (PIST) and/orc) the control unit (8) switches on the fluid pump (1) depending on the measured fluid pressure (PIST) and/ord) the control unit (8) switches off the fluid pump (1) when the measured fluid pressure (PIST) exceeds a certain switch-off pressure (PAUS), and/ore) the control unit (8) switches on the fluid pump (1) when the measured fluid pressure (PIST) falls below a certain switch-on pressure (PEIN).
- The pressure means system according to claim 4, characterized in thata) the control unit (8) determines the discharge flow (Q) of the fluid pump (1),b) the control unit (8) determines the switch-off pressure (PAUS) depending on the discharge flow (Q) of the fluid pump (1) and the predefined target value (PSOLL) of the fluid pressure (PIST).
- The pressure means system according to claim 5, characterized in thata) the fluid pump (1) is driven by a drive motor (2), in particular an electric drive motor (2), with a certain rotational speed, andb) the control unit (8) calculates the discharge flow of the fluid pump (1) from the rotational speed of the drive pump.
- The pressure means system according to any one of the claims 4 to 6, characterized in that the control unit (8) adapts the switch-off pressure dynamically during operation, in particular depending on at least one of the following values:- the discharge flow (Q) of the fluid pump (1),- the predefined target value (PSOLL) for the fluid pressure (PIST),- the temporal pressure rise (dP/dt) of the fluid pressure (PIST).
- The pressure means system according to any one of the claims 3 to 7, characterized in thata) the fluid pump (1) is driven by a drive motor (2), in particular by an electric drive motor (2),b) the drive motor (2) is controlled by a motor control unit,c) the control unit (8) transmits a switch-off signal to the motor control unit for switching off the fluid pump (1).
- The pressure means system according to claim 8, characterized in thata) the control unit (8) is constructionally integrated into the pressure sensor (7), orb) the control unit (8) is constructionally separate from the pressure sensor (7).
- The pressure means system according to any one of the preceding claims, characterized in thata) the drive fluid is a hydraulic fluid, in particular a hydraulic oil, and that the fluid pump (1) is a hydraulic pump, and/orb) the fluid pump (1) supplies a consumer (3) with the drive fluid, and/orc) the consumer (3) is a mechanical clamping system (3), which clamps a workpiece or a workpiece holder detachably.
- The pressure means system according to claim 4 and claim 10, characterized in thata) the control unit (8) determines the temporal change (dp/dt) of the fluid pressure (PIST) when the fluid pump (1) is in the switched-off state, by means of the pressure sensor (7), andb) the control unit (8) determines the switch-on pressure (PEIN) depending on at least one of the following values:- the temporal change (dPIST/dt) of the fluid pressure (PIST) when the fluid pump (1) is in the switched-off state,- the switch-off pressure (PAUS),- the predefined minimum pressure (PMIN).
- The pressure means system according to claim 11, characterized in thata) the switch-on pressure (PEIN) is greater than the predefined minimum pressure (PMIN), and/orb) the switch-on pressure (PEIN) is preferably dimensioned such that the fluid pressure (PIST) after switching on the fluid pump (1) does not fall below the predefined minimum pressure (PMIN) during the pre-run of the fluid pump (1).
- An operating method for a pressure means system havinga) a fluid pump (1) for conveying a drive fluid with a certain discharge flow (Q) and a certain fluid pressure (PIST),b) a control unit (8), which switches the fluid pump (1) on or off to adjust a predefined target value (PSOLL) of the fluid pressure (PIST),c) wherein the fluid pump (1) has an inertia-induced overrun during shut-off, so that the fluid pressure still rises during the overrun of the fluid pump (1), while the fluid pump (1) is already switched off,d) while the fluid pump (1) has an inertia-induced pre-run during switching-on, so that the fluid pressure does not yet rise substantially during the pre-run of the fluid pump (1), although the fluid pump (1) is already switched on,
characterized ine) that he control unit (8) switches off the fluid pump (1) when increasing the fluid pressure (PIST) to the predefined target value (PSOLL) before the fluid pressure (PIST) has reached the target value (PSOLL), and/orf) that the control unit (8) switches on the fluid pump (1) again at the drop of fluid pressure (PIST) when the fluid pump (1) is switched off before the fluid pressure (PIST) has fallen to a predefined minimum pressure (PMIN).
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE102011105584.7A DE102011105584B4 (en) | 2011-06-27 | 2011-06-27 | Pressure medium system, in particular hydraulic system |
DE102011112701.5A DE102011112701B4 (en) | 2011-09-05 | 2011-09-05 | Pressure medium system, in particular hydraulic system |
PCT/EP2012/002598 WO2013000549A2 (en) | 2011-06-27 | 2012-06-20 | Pressure medium system, in particular hydraulic system |
Publications (2)
Publication Number | Publication Date |
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EP2601416A2 EP2601416A2 (en) | 2013-06-12 |
EP2601416B1 true EP2601416B1 (en) | 2015-04-15 |
Family
ID=46320885
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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EP12728408.1A Not-in-force EP2601416B1 (en) | 2011-06-27 | 2012-06-20 | Pressure medium system, in particular hydraulic system |
Country Status (4)
Country | Link |
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US (1) | US9279434B2 (en) |
EP (1) | EP2601416B1 (en) |
ES (1) | ES2540221T3 (en) |
WO (1) | WO2013000549A2 (en) |
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KR101816432B1 (en) * | 2016-08-26 | 2018-01-08 | 현대자동차주식회사 | Method for controlling Air-conditioner compressor |
DE102022116812A1 (en) | 2022-07-06 | 2024-01-11 | Voith Patent Gmbh | Pressure maintenance function for machine presses |
Family Cites Families (14)
Publication number | Priority date | Publication date | Assignee | Title |
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DE3136177A1 (en) | 1981-09-12 | 1983-03-31 | A. Römheld GmbH & Co KG, 6312 Laubach | Tightening pump unit |
US4842244A (en) * | 1987-11-10 | 1989-06-27 | Niagara Mohawk Power Corporation | Valve control system for power generating plants |
JP2582003B2 (en) * | 1991-05-22 | 1997-02-19 | 本田技研工業株式会社 | Pressure source for pressure equipment |
US5829335A (en) * | 1993-05-11 | 1998-11-03 | Mannesmann Rexroth Gmbh | Control for hydraulic drive or actuator |
US5669055A (en) | 1996-03-29 | 1997-09-16 | Xerox Corporation | Dual brush cleaner retraction mechanism and variable inertia drift controller for retractable cleaner |
AT409949B (en) * | 1997-03-07 | 2002-12-27 | Weber Gisela | CONTROL DEVICE FOR HYDRAULIC WORK CYLINDERS |
DE19713576A1 (en) | 1997-04-02 | 1998-10-08 | Bosch Gmbh Robert | Method and device for operating a steering system for a motor vehicle |
DE19959706B4 (en) * | 1999-12-10 | 2010-11-18 | Robert Bosch Gmbh | Method and device for controlling the braking torque of a brake force regulator on at least one wheel of a motor vehicle |
US20040098984A1 (en) * | 2002-11-26 | 2004-05-27 | Duell Charles A. | Combination hydraulic system and electronically controlled vehicle and method of operating same |
DE102005002443B4 (en) * | 2005-01-19 | 2006-12-21 | Robert Bosch Gmbh | Method for controlling a hydraulic actuator and control unit |
DE102005060321A1 (en) | 2005-12-16 | 2007-06-21 | Robert Bosch Gmbh | Method and device for reducible production of a predefinable final pressure in a brake system |
JP4629747B2 (en) * | 2008-02-26 | 2011-02-09 | 日精樹脂工業株式会社 | Method for controlling mold clamping device |
NO328603B1 (en) * | 2008-05-14 | 2010-03-29 | Vetco Gray Scandinavia As | Underwater hybrid valve actuator system and method. |
DE202008011507U1 (en) | 2008-08-29 | 2010-01-07 | Gea Westfaliasurge Gmbh | Safety switching device for a milking carousel |
-
2012
- 2012-06-20 ES ES12728408.1T patent/ES2540221T3/en active Active
- 2012-06-20 US US14/128,173 patent/US9279434B2/en not_active Expired - Fee Related
- 2012-06-20 WO PCT/EP2012/002598 patent/WO2013000549A2/en active Application Filing
- 2012-06-20 EP EP12728408.1A patent/EP2601416B1/en not_active Not-in-force
Also Published As
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US20140130484A1 (en) | 2014-05-15 |
WO2013000549A2 (en) | 2013-01-03 |
WO2013000549A3 (en) | 2013-02-28 |
ES2540221T3 (en) | 2015-07-09 |
EP2601416A2 (en) | 2013-06-12 |
US9279434B2 (en) | 2016-03-08 |
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