EP0574737A1 - Vehicle with battery operated drive, in particular lift truck - Google Patents

Vehicle with battery operated drive, in particular lift truck Download PDF

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Publication number
EP0574737A1
EP0574737A1 EP93108385A EP93108385A EP0574737A1 EP 0574737 A1 EP0574737 A1 EP 0574737A1 EP 93108385 A EP93108385 A EP 93108385A EP 93108385 A EP93108385 A EP 93108385A EP 0574737 A1 EP0574737 A1 EP 0574737A1
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EP
European Patent Office
Prior art keywords
pump
pressure
control valve
differential pressure
control
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Granted
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EP93108385A
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German (de)
French (fr)
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EP0574737B1 (en
Inventor
Peter Dipl.-Ing. Dibbern (Fh)
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Jungheinrich AG
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Jungheinrich AG
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B66—HOISTING; LIFTING; HAULING
    • B66F—HOISTING, LIFTING, HAULING OR PUSHING, NOT OTHERWISE PROVIDED FOR, e.g. DEVICES WHICH APPLY A LIFTING OR PUSHING FORCE DIRECTLY TO THE SURFACE OF A LOAD
    • B66F9/00—Devices for lifting or lowering bulky or heavy goods for loading or unloading purposes
    • B66F9/06—Devices for lifting or lowering bulky or heavy goods for loading or unloading purposes movable, with their loads, on wheels or the like, e.g. fork-lift trucks
    • B66F9/075—Constructional features or details
    • B66F9/20—Means for actuating or controlling masts, platforms, or forks
    • B66F9/22—Hydraulic devices or systems

Definitions

  • the invention relates to a vehicle with a battery-electric traction drive, in particular a loader, according to the preamble of claim 1.
  • the battery feeds both the travel drive and the drive for at least one hydraulic pump that supplies the hydraulic systems.
  • this can also include a power steering assist device.
  • a hydraulic consumer is usually supplied from the pump via a directional valve, via which the volume flow flowing to the consumer is set.
  • the pump is to be driven so that a desired volume flow is actually achieved. If no special control is provided, the pump must be operated at maximum speed or maximum output. However, if the directional control valve is only partially open, considerable throttling losses occur. For secondary functions, i.e. with smaller hydraulic consumers, the throttling losses are very high due to the very low delivery rate required.
  • a load sensing signal corresponds to the pressure e.g. behind the steering valve or the directional control valve, which in turn is manually operated and represents the operator's requirement for the hydraulic system.
  • EP-A-0 251 290 has also disclosed a Signal, based on a hydraulic steering device, which is dependent on the pressure carried in a control signal line behind the steering valve, to give a signal to the pulse control of an electric motor that drives the pump.
  • Electric motors for the traction drive and / or the hydraulic pump are usually direct current motors which are controlled via a pulsed operation.
  • a good speed control can be carried out with the aid of the pulse control.
  • a constant feed pump can therefore be used to regulate the volume flow, the volume flow then being dependent on the engine speed.
  • the invention has for its object to provide a vehicle with battery-electric traction drive, in particular rear loader, in which the efficiency of the working hydraulic circuit is improved.
  • the delivery rate is adjusted to the required volume flow. Throttle losses do not occur because disturbance variables are also recorded.
  • the pressure adjusts to the pressure of the consumer plus the pressure loss. This is done according to the invention in that a pressure difference is determined from the outlet pressure of the pump and the pressure behind the control valve. This differential pressure, which is measured with the help of a suitable sensor, is converted into an actual value signal, which together is given to a controller with a predetermined setpoint. The control signal from the controller is then switched to pulse control. For a given setting of the valve, the pressure difference depends on the volume flow coming from the pump. If this is low, the pressure difference is also small and a relatively high control deviation arises in the controller, which has the consequence that the speed of the pump motor is increased via the pulse control.
  • the invention provides a control system that controls the pump only on the power that is actually queried. Excess output is no longer generated. Losses only occur as pressure losses in the lines and the valves. The invention thus enables the operation of a hydraulic system with optimal efficiency.
  • a pressure compensator is preferably assigned to the valve, which responds whenever the pump pressure is too high compared to the load pressure. This can be done, for example, by suddenly closing the directional control valve because of the pump speed cannot be reduced quickly enough.
  • a movable element acted upon by both pressures is provided, the position of which is detected and converted into an electrical differential pressure signal.
  • the movable element can e.g. be a piston which is held in a neutral position in a cylinder by means of springs. It is also possible to provide a membrane or the like which is pressurized from both sides.
  • the embodiment described below relates a battery-operated lift truck, the mast of which has at least one lift cylinder. It is designated by 10 in FIG. 3. It is used to lift a load, represented by arrow 12, for example with the aid of a suitable load handler. For example, a load is stacked on a shelf or removed from the shelf.
  • the hydraulic cylinder is supplied by a motor pump unit 14, which consists of a pulse-controlled direct current motor and a constant feed pump. Such units are known.
  • the impulse control is represented by block 16.
  • a control valve 18 is connected between the pump 14 and the lifting cylinder 10 and can be actuated, for example, by means of a hand lever on the lift truck. This is indicated by the arrow 20.
  • Fig. 1 the pressure is plotted against the delivery rate of the hydraulic pump. Due to losses in lines and valves, a reduced pressure p load occurs on the load, for example the hydraulic cylinder 10. The delivery rate actually required corresponds to Q erf . Since the disturbances such as load pressure, friction, etc. can not be readily detect the flow rate Q is control selected higher than the required flow rate Q erf. There is therefore a more or less large area in which throttle losses occur. They are only minimized when the valve 18 is fully open and the pump delivers with a maximum delivery rate Q max .
  • a differential pressure meter 22 is provided, which is connected to the outlet of the pump 14 and to the line behind the valve 18.
  • the pressure meter 22 which has, for example, a differential pressure piston or a differential pressure membrane, the displacement of the piston or the membrane being converted into an electrical signal, measures the pressure drop across the more or less open valve 18.
  • the differential pressure is compared with a setpoint 24, according to which a controller 26 outputs a control signal to the pulse controller 16 in accordance with the control deviation.
  • the setpoint is constant and corresponds, for example, to the pressure difference of the valve when the position is fully open and the maximum pump volume flow. It can be seen that the delivery rate of the pump 14 is adjusted to the required volume flow Q erf . Throttle losses do not arise because the disturbance variables are also recorded.
  • the pump pressure adjusts itself to the load pressure plus the pressure losses. In the control described, the delivery rate requested by the valve position is a system parameter. A change in the valve position is treated like a disturbance variable.

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  • Engineering & Computer Science (AREA)
  • Transportation (AREA)
  • Structural Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Civil Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Geology (AREA)
  • Mechanical Engineering (AREA)
  • Fluid-Pressure Circuits (AREA)
  • Operation Control Of Excavators (AREA)

Abstract

Vehicle with battery-operated drive, in particular a lift truck, with a lifting-cylinder arrangement (10) for a lifting frame, a hydraulic pump (14), an electric motor for the pump, the speed of which is controlled via a pulse control (16), and a control valve (18) between pump and lifting-cylinder arrangement, a differential-pressure gauge (22) forming a differential-pressure signal from the pressure at the outlet of the pump (14) and behind the control valve (18), and a controller (26) forming a regulated quantity for the pulse control (16) from the comparison of the differential-pressure signal with a preset desired value. <IMAGE>

Description

Die Erfindung bezieht sich auf ein Fahrzeug mit batterieelektrischem Fahrantrieb, insbesondere Hublader, nach dem Oberbegriff des Patentanspruchs 1.The invention relates to a vehicle with a battery-electric traction drive, in particular a loader, according to the preamble of claim 1.

Derartige Fahrzeuge sind in zahlreichen unterschiedlichen Ausführungsformen bekannt geworden. Es sei u.a. auf die EP-A-0 072 233 verwiesen. Die Batterie speist sowohl den Fahrantrieb als auch den Antrieb für mindestens eine Hydraulikpumpe, welche die hydraulischen Systeme versorgt. Hierzu gehört mindestens eine hydraulische Arbeitseinrichtung, beispielsweise eine Hubzylinderanordnung für ein Hubgerüst. Hierzu kann jedoch auch eine Lenkhilfskraftunterstützungseinrichtung gehören.Such vehicles have become known in numerous different embodiments. Reference is made inter alia to EP-A-0 072 233. The battery feeds both the travel drive and the drive for at least one hydraulic pump that supplies the hydraulic systems. This includes at least one hydraulic working device, for example a lifting cylinder arrangement for a Mast. However, this can also include a power steering assist device.

Die Versorgung eines hydraulischen Verbrauchers von der Pumpe aus erfolgt üblicherweise über ein Wegeventil, über das der zum Verbraucher fließende Volumenstrom eingestellt wird. Die Pumpe ist dabei so anzutreiben, daß ein gewünschter Volumenstrom auch tatsächlich erreicht wird. Falls keine besondere Steuerung vorgesehen ist, ist erforderlich, die Pumpe mit maximaler Drehzahl bzw. maximaler Leistung zu betreiben. Ist das Wegeventil jedoch nur teilweise geöffnet, entstehen erhebliche Drosselverluste. Bei Nebenfunktionen, d.h. bei kleineren hydraulischen Verbrauchern, sind die Drosselverluste infolge der sehr geringen erforderlichen Fördermenge sehr hoch.A hydraulic consumer is usually supplied from the pump via a directional valve, via which the volume flow flowing to the consumer is set. The pump is to be driven so that a desired volume flow is actually achieved. If no special control is provided, the pump must be operated at maximum speed or maximum output. However, if the directional control valve is only partially open, considerable throttling losses occur. For secondary functions, i.e. with smaller hydraulic consumers, the throttling losses are very high due to the very low delivery rate required.

Aus dem Prospekt "DANFOSS Hydraulische Lenkungskomponenten" ist bereits bekannt geworden, eine elektromotorisch angetriebene Verstellpumpe über ein sogenanntes Load sensing-Signal zu steuern. Ein Load sensing-Signal entspricht dem Druck z.B. hinter dem Lenkventil oder dem Wegeventil, das seinerseits manuell betätigt ist und die Anforderung des Bedieners an das Hydrauliksystem darstellt.From the brochure "DANFOSS Hydraulic Steering Components" it has already become known to control an electric motor-driven variable displacement pump via a so-called load sensing signal. A load sensing signal corresponds to the pressure e.g. behind the steering valve or the directional control valve, which in turn is manually operated and represents the operator's requirement for the hydraulic system.

Aus der EP-A-0 251 290 ist ferner bekannt geworden, ein Signal, ausgehend von einer hydraulischen Lenkeinrichtung, das abhängig ist von dem in einer Steuersignalleitung hinter dem Lenkventil geführten Druck, Signal auf die Impulssteuerung eines elektrischen, die Pumpe antreibenden Motors zu geben. Elektromotoren für den Fahrantrieb und/oder die Hydraulikpumpe sind üblicherweise Gleichstrommotoren, die über einen Impulsbetrieb gesteuert werden. Mit Hilfe der Impulssteuerung läßt sich eine gute Drehzahlregelung vornehmen. Daher kann zur Regelung des Volumenstroms eine Konstantförderpumpe verwendet werden, wobei der Volumenstrom dann abhängig ist von der Motordrehzahl. Es ist im übrigen auch bereits bekannt, bei derartigen Impulssteuerungen bei Nebenhydraulikantrieben die Pumpe konstant anzusteuern, d.h. auf einen maximal erforderlichen Volumenstrom, wobei eine Feinsteuerung über die Drosselung im Wegeventil erfolgt. Bei einer Hubzylinderanordnung erfolgt deren Ansteuerung in Abhängigkeit von der Ventilhebelstellung. Auch bei derartigen Hydrauliksystemen lassen sich Drosselverluste nicht vermeiden. Bei den bereits erwähnten Nebenantrieben richtet sich die konstante Teilmenge der Pumpe nach der für den jeweiligen Antrieb maximalen Geschwindigkeit. Niedrigere Geschwindigkeiten werden über Drosselung der überflüssigen Fördermenge realisiert. Bei dem hydraulischen Antrieb eines Arbeitszylinders, beispielsweise eine Hubzylinderanordnung, richtet sich die Fördermenge der Pumpe nach der Ventilhebelstellung. Der Ventilhebel ist z.B. mit einem Potentiometer gekoppelt, dessen Signal auf die Impulssteuerung gegeben wird. Weil jedoch die Störgrößen, wie Lastdruck, Reibung usw., nicht erfaßt werden, muß die Fördermenge größer sein als der tatsächlich benötigte Volumenstrom. Überschüssiger Volumenstrom wird daher im Wegeventil gedrosselt.EP-A-0 251 290 has also disclosed a Signal, based on a hydraulic steering device, which is dependent on the pressure carried in a control signal line behind the steering valve, to give a signal to the pulse control of an electric motor that drives the pump. Electric motors for the traction drive and / or the hydraulic pump are usually direct current motors which are controlled via a pulsed operation. A good speed control can be carried out with the aid of the pulse control. A constant feed pump can therefore be used to regulate the volume flow, the volume flow then being dependent on the engine speed. Furthermore, it is also known to control the pump constantly in the case of such pulse controls in the case of auxiliary hydraulic drives, that is to say to a maximum required volume flow, with fine control via the throttling in the directional control valve. In the case of a lifting cylinder arrangement, they are controlled as a function of the valve lever position. Throttling losses cannot be avoided even with such hydraulic systems. With the auxiliary drives already mentioned, the constant partial quantity of the pump depends on the maximum speed for the respective drive. Lower speeds are achieved by throttling the excess flow. In the case of the hydraulic drive of a working cylinder, for example a lifting cylinder arrangement, this is directed Flow rate of the pump after the valve lever position. The valve lever is, for example, coupled to a potentiometer, the signal of which is given to the pulse control. However, because the disturbance variables such as load pressure, friction etc. are not recorded, the delivery rate must be greater than the volume flow actually required. Excess volume flow is therefore throttled in the directional control valve.

Der Erfindung liegt die Aufgabe zugrunde, ein Fahrzeug mit batterie-elektrischem Fahrantrieb, insbesondere Hublader, zu schaffen, bei dem der Wirkungsgrad des Arbeitshydraulikkreises verbessert ist.The invention has for its object to provide a vehicle with battery-electric traction drive, in particular rear loader, in which the efficiency of the working hydraulic circuit is improved.

Diese Aufgabe wird gelöst durch die Merkmale des Patentanspruchs 1.This object is achieved by the features of patent claim 1.

Bei der Erfindung wird die Fördermenge auf den erforderlichen Volumenstrom eingeregelt. Drosselverluste entstehen nicht, weil Störgrößen mit erfaßt werden. Der Druck stellt sich auf den Druck des Verbrauchers plus dem Druckverlust ein. Dies geschieht erfinderungsgemäß dadurch, daß eine Druckdifferenz ermittelt wird aus dem Ausgangsdruck der Pumpe und dem Druck hinter dem Steuerventil. Dieser Differenzdruck, der mit Hilfe eines geeigneten Sensors gemessen wird, wird umgewandelt in ein Istwertsignal, das zusammen mit einem vorgegebenen Sollwert auf einen Regler gegeben wird. Das Stellsignal des Reglers wird dann auf die Impulssteuerung geschaltet. Bei einer vorgegebenen Einstellung des Ventils hängt die Druckdifferenz von dem von der Pumpe kommenden Volumenstrom ab. Ist dieser gering, ist auch die Druckdifferenz gering und im Regler entsteht eine relativ hohe Regelabweichung die zur Folge hat, daß über die Impulssteuerung die Drehzahl des Pumpenmotors erhöht wird. Die Drehzahl wird solange erhöht, bis Ist- und Sollwert gleich sind, d.h. die gemessene Druckdifferenz einen Mindestwert erreicht. Ändert sich nunmehr die Ventilstellung, wird diese als Störgröße behandelt, welche nunmehr auszuregeln ist. Mit anderen Worten, mit der Erfindung wird ein Regelsystem zur Verfügung gestellt, das die Pumpe nur auf diejenige Leistung steuert, die tatsächlich abgefragt wird. Eine überschüssige Fördermenge wird nicht mehr erzeugt. Verluste treten nur noch als Druckverluste in den Leitungen und den Ventilen auf. Die Erfindung ermöglicht mithin den Betrieb eines Hydrauliksystems mit optimalem Wirkungsgrad.In the invention, the delivery rate is adjusted to the required volume flow. Throttle losses do not occur because disturbance variables are also recorded. The pressure adjusts to the pressure of the consumer plus the pressure loss. This is done according to the invention in that a pressure difference is determined from the outlet pressure of the pump and the pressure behind the control valve. This differential pressure, which is measured with the help of a suitable sensor, is converted into an actual value signal, which together is given to a controller with a predetermined setpoint. The control signal from the controller is then switched to pulse control. For a given setting of the valve, the pressure difference depends on the volume flow coming from the pump. If this is low, the pressure difference is also small and a relatively high control deviation arises in the controller, which has the consequence that the speed of the pump motor is increased via the pulse control. The speed is increased until the actual and target values are the same, ie the measured pressure difference reaches a minimum value. If the valve position changes now, it is treated as a disturbance variable which must now be corrected. In other words, the invention provides a control system that controls the pump only on the power that is actually queried. Excess output is no longer generated. Losses only occur as pressure losses in the lines and the valves. The invention thus enables the operation of a hydraulic system with optimal efficiency.

Dem Ventil ist vorzugsweise eine Druckwaage zuzuordnen, die immer dann anspricht, wenn der Pumpendruck gegenüber dem Lastdruck zu hoch ist. Das kann z.B. durch schlagartiges Schließen des Wegeventils erfolgen, weil die Pumpendrehzahl nicht schnell genug heruntergeregelt werden kann.A pressure compensator is preferably assigned to the valve, which responds whenever the pump pressure is too high compared to the load pressure. This can be done, for example, by suddenly closing the directional control valve because of the pump speed cannot be reduced quickly enough.

Für die Differenzdruckmessung bieten sich verschiedene Lösungen an. Eine besteht erfindungsgemäß darin, daß ein von beiden Drücken beaufschlagtes bewegliches Element vorgesehen ist, dessen Position erfaßt und in ein elektrisches Differenzdrucksignal umgewandelt wird. Das bewegliche Element kann z.B. ein Kolben sein, der in einem Zylinder mittels Federn in einer Neutralstellung gehalten wird. Es ist auch möglich, eine von beiden Seiten mit Druck beaufschlagte Membran oder dergleichen vorzusehen.Various solutions are available for differential pressure measurement. According to the invention, one is that a movable element acted upon by both pressures is provided, the position of which is detected and converted into an electrical differential pressure signal. The movable element can e.g. be a piston which is held in a neutral position in a cylinder by means of springs. It is also possible to provide a membrane or the like which is pressurized from both sides.

Die Erfindung wird nachfolgend anhand von Zeichnungen näher erläutert.

Fig. 1
zeigt ein Diagramm zur Erläuterung des Betriebs bekannter Pumpensteuerungen.
Fig. 2
zeigt ein Diagramm mit einem Hydrauliksystem nach der Erfindung.
Fig. 3
zeigt ein Blockschaltbild eines Hydrauliksystems nach der Erfindung.
The invention is explained in more detail below with reference to drawings.
Fig. 1
shows a diagram for explaining the operation of known pump controls.
Fig. 2
shows a diagram with a hydraulic system according to the invention.
Fig. 3
shows a block diagram of a hydraulic system according to the invention.

Das nachfolgend beschriebene Ausführungsbeispiel betrifft einen batteriebetriebenen Hublader, dessen Hubgerüst mindestens einen Hubzylinder aufweist. Er ist in Fig. 3 mit 10 bezeichnet. Er dient zum Anheben einer Last, dargestellt durch Pfeil 12, z.B. mit Hilfe eines geeigneten Lastaufnahmemittels. So wird z.B. eine Last in ein Regal eingestapelt oder aus dem Regal herausgeholt. Die Versorgung des Hydraulikzylinders erfolgt durch eine Motorpumpeneinheit 14, welche aus einem impulsgesteuerten Gleichstrommotor und einer Konstantförderpumpe besteht. Derartige Einheiten sind bekannt. Die Impulssteuerung wird durch den Block 16 repräsentiert. Zwischen der Pumpe 14 und dem Hubzylinder 10 ist ein Steuerventil 18 geschaltet, das z.B. durch einen Handhebel am Hublader betätigbar ist. Dies ist angedeutet durch den Pfeil 20. Durch Betätigung des Ventils 18 erfolgt mithin eine Verstellung des Hubzylinders 10, wobei das Ausmaß der Verstellung des Ventils 18 die Geschwindigkeit bestimmt, mit der der Hubzylinder die Last 12 bewegt. Es versteht sich, daß in einem Hublader auch andere hydraulische Verbraucher vorgesehen sind, die entsprechend versorgt werden. Daher gilt die Beschreibung zu den Figuren 1 bis 3 exemplarisch für alle anderen Hydrauliksysteme eines Hubladers.The embodiment described below relates a battery-operated lift truck, the mast of which has at least one lift cylinder. It is designated by 10 in FIG. 3. It is used to lift a load, represented by arrow 12, for example with the aid of a suitable load handler. For example, a load is stacked on a shelf or removed from the shelf. The hydraulic cylinder is supplied by a motor pump unit 14, which consists of a pulse-controlled direct current motor and a constant feed pump. Such units are known. The impulse control is represented by block 16. A control valve 18 is connected between the pump 14 and the lifting cylinder 10 and can be actuated, for example, by means of a hand lever on the lift truck. This is indicated by the arrow 20. By actuation of the valve 18 there is therefore an adjustment of the lifting cylinder 10, the extent of the adjustment of the valve 18 determining the speed at which the lifting cylinder moves the load 12. It goes without saying that other hydraulic consumers are also provided in a lift truck, which are supplied accordingly. The description of FIGS. 1 to 3 therefore applies to all other hydraulic systems of a lift truck as an example.

Es wurde bereits erläutert, daß bekannt ist, die Impulssteuerung des Pumpenmotors abhängig zu machen von der Stellung des Ventilhebels. Da jedoch sichergestellt werden muß, daß die eingestellte Leistung der Pumpe tatsächlich erreicht wird, wird ein entsprechend höherer Volumenstrom gewählt. Dies ist in Fig. 1 zu erkennen. In Fig. 1 ist der Druck über der Fördermenge der Hydraulikpumpe aufgetragen. Aufgrund von Verlusten in Leitungen und Ventilen stellt sich an der Last, z.B. dem Hydraulikzylinder 10 ein verminderter Druck pLast ein. Die tatsächlich benötigte Fördermenge entspricht Qerf. Da sich die Störgrößen, wie Lastdruck, Reibung usw. nicht ohne weiteres erfassen lassen, wird die Fördermenge QSteuer höher gewählt als der erforderliche Volumenstrom Qerf. Mithin liegt ein mehr oder weniger großer Bereich vor, in dem Drosselverluste auftreten. Sie werden nur dann minimiert, wenn das Ventil 18 voll geöffnet ist und die Pumpe mit maximaler Fördermenge Qmax fördert.It has already been explained that it is known to make the pulse control of the pump motor dependent on the Position of the valve lever. However, since it must be ensured that the set pump output is actually achieved, a correspondingly higher volume flow is selected. This can be seen in Fig. 1. In Fig. 1 the pressure is plotted against the delivery rate of the hydraulic pump. Due to losses in lines and valves, a reduced pressure p load occurs on the load, for example the hydraulic cylinder 10. The delivery rate actually required corresponds to Q erf . Since the disturbances such as load pressure, friction, etc. can not be readily detect the flow rate Q is control selected higher than the required flow rate Q erf. There is therefore a more or less large area in which throttle losses occur. They are only minimized when the valve 18 is fully open and the pump delivers with a maximum delivery rate Q max .

In Fig. 3 ist ein Differenzdruckmesser 22 vorgesehen, der mit dem Ausgang der Pumpe 14 und mit der Leitung hinter dem Ventil 18 verbunden ist. Der Druckmesser 22, der beispielsweise einen Differenzdruckkolben oder eine Differenzdruckmembran aufweist, wobei die Verstellung des Kolbens bzw. der Membran in ein elektrisches Signal umgewandelt wird, mißt den Druckabfall über das mehr oder weniger geöffnete Ventil 18. Der Differenzdruck wird verglichen mit einem Sollwert 24, wonach ein Regler 26 nach Maßgabe der Regelabweichung ein Stellsignal auf die Impulssteuerung 16 gibt. Der Sollwert ist konstant und entspricht z.B. der Druckdifferenz des Ventils bei vollständig geöffneter Stellung und maximalem Pumpenvolumenstrom. Es ist erkennbar, daß die Fördermenge der Pumpe 14 auf den erforderlichen Volumenstrom Qerf eingeregelt wird. Drosselverluste entstehen nicht, weil die Störgrößen mit erfaßt werden. Der Pumpendruck stellt sich auf den Lastdruck plus den Druckverlusten ein. Bei der beschriebenen Regelung ist die durch die Ventilstellung angeforderte Fördermenge ein Systemparameter. Eine Änderung der Ventilstellung wird wie eine Störgröße behandelt.In Fig. 3, a differential pressure meter 22 is provided, which is connected to the outlet of the pump 14 and to the line behind the valve 18. The pressure meter 22, which has, for example, a differential pressure piston or a differential pressure membrane, the displacement of the piston or the membrane being converted into an electrical signal, measures the pressure drop across the more or less open valve 18. The differential pressure is compared with a setpoint 24, according to which a controller 26 outputs a control signal to the pulse controller 16 in accordance with the control deviation. The setpoint is constant and corresponds, for example, to the pressure difference of the valve when the position is fully open and the maximum pump volume flow. It can be seen that the delivery rate of the pump 14 is adjusted to the required volume flow Q erf . Throttle losses do not arise because the disturbance variables are also recorded. The pump pressure adjusts itself to the load pressure plus the pressure losses. In the control described, the delivery rate requested by the valve position is a system parameter. A change in the valve position is treated like a disturbance variable.

Aus Fig. 2 ergibt sich, daß die Druckverluste des Hydrauliksystems insgesamt minimal sind.From Fig. 2 it follows that the pressure losses of the hydraulic system are minimal overall.

Claims (4)

Fahrzeug mit batterie-elektrischem Fahrantrieb, insbesondere Hublader, mit einer Hubzylinder-Anordnung für ein Hubgerüst, einer Hydraulikpumpe, einem Elektromotor für die Pumpe, dessen Drehzahl über eine Impulssteuerung gesteuert wird und einem Steuerventil zwischen Pumpe und Hubzylinderanordnung, dadurch gekennzeichnet, daß ein Differenzdruckmesser aus dem Druck am Ausgang der Pumpe (14) und hinter dem Steuerventil (18) ein Differenzdrucksignal bildet und ein Regler (26) aus dem Vergleich des Differenzdrucksignals mit einem vorgegebenen Sollwert (24) eine Stellgröße für die Impulssteuerung (16) bildet.Vehicle with a battery-electric drive, in particular a lift loader, with a lifting cylinder arrangement for a lifting frame, a hydraulic pump, an electric motor for the pump, the speed of which is controlled by a pulse control and a control valve between the pump and the lifting cylinder arrangement, characterized in that a differential pressure meter consists of the pressure at the outlet of the pump (14) and behind the control valve (18) forms a differential pressure signal and a controller (26) forms a manipulated variable for the pulse control (16) from the comparison of the differential pressure signal with a predetermined target value (24). Fahrzeug nach Anspruch 1, dadurch gekennzeichnet, daß der Sollwert (24) konstant ist.Vehicle according to claim 1, characterized in that the target value (24) is constant. Fahrzeug nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß der Sollwert (24) der Druckdifferenz entspricht, die bei voll geöffnetem Steuerventil (18) über dem Steuerventil (18) bei vollem Pumpenvolumenstrom (Qmax) herrscht.Vehicle according to claim 1 or 2, characterized in that the target value (24) corresponds to the pressure difference which prevails when the control valve (18) is fully open above the control valve (18) when the pump volume flow (Q max ) is full. Fahrzeug nach einem der Ansprüche 1 bis 3, dadurch gekennzeichnet, daß der Differenzdruckmesser (22) ein von beiden Drücken beaufschlagtes bewegliches Element enthält, dessen Position erfaßt und in ein elektrisches Differenzdrucksignal umgewandelt wird.Vehicle according to one of claims 1 to 3, characterized in that that the differential pressure meter (22) contains a movable element acted upon by both pressures, the position of which is detected and converted into an electrical differential pressure signal.
EP93108385A 1992-06-17 1993-05-25 Vehicle with battery operated drive, in particular lift truck Expired - Lifetime EP0574737B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE4219787 1992-06-17
DE4219787A DE4219787C1 (en) 1992-06-17 1992-06-17 Vehicle with a battery-electric drive, especially a rear loader

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EP0574737A1 true EP0574737A1 (en) 1993-12-22
EP0574737B1 EP0574737B1 (en) 1996-09-04

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EP93108385A Expired - Lifetime EP0574737B1 (en) 1992-06-17 1993-05-25 Vehicle with battery operated drive, in particular lift truck

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DE (2) DE4219787C1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
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EP0669281A1 (en) * 1994-01-29 1995-08-30 Jungheinrich Aktiengesellschaft Hydraulic lifting device for battery-actuated load handling trucks

Families Citing this family (3)

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Publication number Priority date Publication date Assignee Title
DE19612582A1 (en) * 1996-03-29 1997-10-02 Miag Fahrzeugbau Gmbh Drive unit for vehicle e.g forklift truck
DE19744429A1 (en) * 1997-10-08 1999-04-22 Still Wagner Gmbh & Co Kg Industrial truck with a load suspension device and method for lowering the load suspension device
DE10033223A1 (en) * 2000-07-07 2002-01-17 Dambach Lagersysteme Gmbh Orderpicker drive control system converts pressure difference across line throttle into electrical signal passed to drive motor speed regulator.

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EP0379595A1 (en) * 1988-07-08 1990-08-01 Hitachi Construction Machinery Co., Ltd. Hydraulic driving apparatus
DE4026695A1 (en) * 1989-08-25 1991-03-14 Toyoda Automatic Loom Works Hydraulic fluid flow control for industrial vehicle - has coupling on=off sensor allowing required discharge capacitance of hydraulic fluid to be maintained
DE4036860A1 (en) * 1989-11-20 1991-07-04 Toyoda Automatic Loom Works LOAD / RELIEF CONTROL DEVICE FOR A HYDRAULIC CIRCUIT
EP0462589A2 (en) * 1990-06-19 1991-12-27 Hitachi Construction Machinery Co., Ltd. Control system for load sensing hydraulic drive circuit
WO1992010684A1 (en) * 1990-12-15 1992-06-25 Barmag Ag Hydraulic system
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EP0190703A1 (en) * 1985-02-04 1986-08-13 Hitachi Construction Machinery Co., Ltd. Control system for hydraulic circuit
EP0379595A1 (en) * 1988-07-08 1990-08-01 Hitachi Construction Machinery Co., Ltd. Hydraulic driving apparatus
DE4026695A1 (en) * 1989-08-25 1991-03-14 Toyoda Automatic Loom Works Hydraulic fluid flow control for industrial vehicle - has coupling on=off sensor allowing required discharge capacitance of hydraulic fluid to be maintained
DE4036860A1 (en) * 1989-11-20 1991-07-04 Toyoda Automatic Loom Works LOAD / RELIEF CONTROL DEVICE FOR A HYDRAULIC CIRCUIT
EP0462589A2 (en) * 1990-06-19 1991-12-27 Hitachi Construction Machinery Co., Ltd. Control system for load sensing hydraulic drive circuit
WO1992010684A1 (en) * 1990-12-15 1992-06-25 Barmag Ag Hydraulic system
WO1992014944A1 (en) * 1991-02-15 1992-09-03 Caterpillar Inc. Hydraulic circuit and control system therefor

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0669281A1 (en) * 1994-01-29 1995-08-30 Jungheinrich Aktiengesellschaft Hydraulic lifting device for battery-actuated load handling trucks

Also Published As

Publication number Publication date
EP0574737B1 (en) 1996-09-04
DE4219787C1 (en) 1994-01-05
DE59303622D1 (en) 1996-10-10

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