EP3663253B1 - Electrically operated industrial truck - Google Patents

Electrically operated industrial truck Download PDF

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Publication number
EP3663253B1
EP3663253B1 EP19212025.1A EP19212025A EP3663253B1 EP 3663253 B1 EP3663253 B1 EP 3663253B1 EP 19212025 A EP19212025 A EP 19212025A EP 3663253 B1 EP3663253 B1 EP 3663253B1
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EP
European Patent Office
Prior art keywords
electrical
industrial truck
hydraulic
hydraulic fluid
hydraulic liquid
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EP19212025.1A
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German (de)
French (fr)
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EP3663253A1 (en
Inventor
Rainer Hübner
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STILL GmbH
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STILL GmbH
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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
    • 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
    • B66F9/24—Electrical devices or systems

Definitions

  • the invention relates to an electrically, in particular battery-powered, industrial truck with at least one electrical unit that can be operated as a generator and is electrically connected to at least one electrical resistor for converting electrical energy into heat energy, and with a working and/or Control hydraulics, which has a hydraulic fluid circuit, with the electrical resistance being in operative connection with the hydraulic fluid circuit for transferring the thermal energy to the hydraulic fluid of the hydraulic fluid circuit, with the electrical unit being formed by an electric drive motor of the industrial truck, and with the industrial truck having a traction battery which is electrically connected to the electrical unit and to the electrical resistance.
  • Electrically operated industrial trucks can have internal combustion engine-electric or battery-electric drive systems.
  • electrical units are coupled to the internal combustion engine.
  • at least one electrical generator is provided, which is driven by an internal combustion engine.
  • the electrical energy generated by the generator is forwarded by means of power electronics to one or more electric traction motors, which are in driving connection with the driven wheels of the industrial truck.
  • Such industrial trucks are braked as a generator.
  • the drive motor or motors are operated as generators, which convert the kinetic energy of the industrial truck into electrical energy during the braking phase.
  • this electrical energy is supplied to the generator, which operates as a motor in this operating state.
  • a here acting on a rotor of the generator torque is based on a crankshaft of the engine, whereby the speed of the internal combustion engine increases. This results in increased noise generation by the combustion engine and also increased mechanical wear.
  • the electrical units are electrically connected to a traction battery.
  • the electrical energy made available by the traction battery is forwarded by means of power electronics to one or more electric traction motors, which are in driving connection with the driven wheels of the industrial truck.
  • Regenerative braking of the industrial truck is also common in industrial trucks with battery-electric drive systems.
  • the drive motor or motors are operated as generators, which convert the kinetic energy of the industrial truck into electrical energy during the braking phase. This electrical energy is fed back into the traction battery. In this way, braking energy can be recovered, which is generally referred to as recuperation.
  • the hydraulic fluid circuit is often also specially filled with a hydraulic fluid of low viscosity.
  • the CN 203 580 677 U discloses a generic battery-powered industrial truck with a lithium-ion battery that supplies an electric traction motor, an electric steering motor and an electric pump motor.
  • the battery also powers a heating resistor that heats the oil in the hydraulic tank. Depending on the temperature of the hydraulic oil, the heating resistor can be energized.
  • the present invention is based on the object of designing an industrial truck of the type mentioned at the outset in such a way that vehicle safety and the functionality of the working and/or control hydraulics are ensured even at low operating temperatures.
  • an electronic vehicle control device which is in operative connection with the electric traction motor, the traction battery and a temperature sensor in the hydraulic fluid circuit and feeds the electrical energy generated in the electric traction motor when the industrial truck brakes electrically into the Traction battery and / or allows in the electrical resistance depending on the state of charge of the traction battery and allows energization of the electrical resistance with energy from the traction battery depending on the temperature of the hydraulic fluid.
  • the electrical resistance is in operative connection with the hydraulic fluid circuit for the transmission of thermal energy to the hydraulic fluid of the hydraulic fluid circuit.
  • the recuperation energy generated when braking the industrial truck due to the generator operation of the electric traction motor(s), which cannot be absorbed by a cold and/or fully charged traction battery, for example, can be reliably dissipated with the electrical resistance. This ensures that the industrial truck is safe to drive under all operating conditions.
  • the hydraulic fluid of the hydraulic fluid circuit can be heated up in a targeted manner by means of the electrical resistance in order to avoid the operating and wear problems that occur at low ambient temperatures due to the high viscosity of the hydraulic fluid.
  • the electrical resistance By heating up the cold hydraulic fluid with the electrical resistance, all hydraulic functions are fully available more quickly.
  • the electrical resistor thus has the function of a braking resistor, with which the electrical energy generated when the industrial truck brakes in generator mode of the traction motor(s) can be absorbed, and the function of a heating resistor, with which the hydraulic fluid of the hydraulic fluid circuit can be heated at low ambient temperatures can.
  • the electrical resistance thus forms a combined heating/braking resistance.
  • the invention is suitable both for industrial trucks with an internal combustion engine-electric drive system and for industrial trucks with a battery-electric drive system.
  • the electrical resistance arranged in the hydraulic fluid circuit can reliably dissipate the excess energy generated when the industrial truck brakes and at the same time the hydraulic fluid of the working and/or control hydraulics of the industrial truck can be heated to favorable operating temperatures.
  • an electronic vehicle control device is provided according to the invention, which is operatively connected to the electric traction motor, the traction battery and the temperature sensor in the hydraulic fluid circuit.
  • the vehicle control device is designed in such a way that the electrical energy generated in the electric traction motor when the industrial truck is electrically braked is fed into the traction battery and/or into the electrical resistor, depending on the charging status of the traction battery, and the electrical resistor is supplied with energy from the traction battery is carried out depending on the temperature of the hydraulic fluid.
  • the traction battery is a lithium-ion battery.
  • the electrical resistance can be easily operated with electrical energy from the traction battery in order to achieve the function as a heating resistor, with which the hydraulic fluid of the hydraulic fluid circuit can be heated at low ambient temperatures.
  • the electrical resistance also achieves the function of the braking resistor, which can absorb the electrical energy generated during braking in generator mode of the electrical unit.
  • the electrical energy generated during the braking phase by the electrical unit operated as a generator, for example the electrical traction motor can be at least partially fed back into the traction battery and the traction battery can thus be charged.
  • Excess energy that cannot be absorbed by the traction battery is supplied to the electrical resistance, which is expediently arranged directly in the hydraulic fluid circuit, and is released to the hydraulic fluid surrounding the electrical resistance in the form of heat energy.
  • An expedient embodiment of the invention is that the electrical resistance is arranged in a hydraulic fluid tank of the hydraulic fluid circuit.
  • the electrical resistance can be retrofitted from the outside in a conventional hydraulic fluid tank.
  • the hydraulic fluid tank is preferably provided with a mounting flange for the electrical resistance.
  • the electrical resistance can also be arranged in a hydraulic line of the hydraulic fluid circuit.
  • the electrical resistance for heat exchange thus comes into contact with the hydraulic fluid of the hydraulic fluid circuit flowing through the hydraulic line.
  • the electrical resistance is arranged in a hydraulic component of the hydraulic fluid circuit, in particular in a hydraulic filter and/or in a hydraulic valve and/or in a hydraulic pump.
  • An arrangement of the electrical resistance in the suction region of a suction filter provided in a hydraulic fluid tank is particularly advantageous. On the one hand, this ensures that the electrical resistance is surrounded on all sides by hydraulic fluid in the hydraulic fluid tank for effective heat exchange and, on the other hand, continuous removal of the excess heat energy is ensured due to the intake flow.
  • the electrical resistance is expediently designed as a resistance coil.
  • This can be, for example, a coiled metal wire through which an electric current flows.
  • This configuration has the advantage that it saves space and can be easily installed both in hydraulic fluid tanks and in hydraulic lines and hydraulic components.
  • the electrical resistance can also be in the form of a circle or a simple loop due to the more generous space available.
  • the temperature sensor that detects the temperature of the hydraulic fluid is provided in the hydraulic fluid circuit and is connected to the electrical control device in Active connection is that allows control of the temperature of the hydraulic fluid by means of energizing the electrical resistance with electricity from the traction battery, which is connected to the electrical resistance.
  • the temperature of the hydraulic fluid can be specifically heated to a desired temperature and/or kept within a predetermined temperature range with the electrical resistor and its function as a heating resistor.
  • An optimum viscosity range for the hydraulic fluid can thus be set. This also makes it easy to heat up the hydraulic fluid at low ambient temperatures, so that the hydraulic functions are fully available in a short time.
  • the electric traction motor is an asynchronous motor.
  • the electric drive motor is operated as a generator and converts the kinetic energy of the truck into electrical energy.
  • the electrical resistance integrated in the hydraulic fluid circuit with its function as a braking resistor, the electrical energy generated by the traction motor operated as a generator can be released as thermal energy into the hydraulic fluid with little construction effort and without additional space requirements.
  • the invention offers a whole range of advantages: With the help of the invention, faster availability of the full range of functions of the cold industrial truck can be achieved. The safety requirement for braking a cold, fully loaded battery-powered vehicle, for example on a ramp, can be guaranteed at low cost.
  • the solution can also be retrofitted and is suitable as an option for series vehicles.
  • the proposed technical solution is inexpensive and solves two problems at the same time. Additional savings result from the elimination of the braking resistor in the traction battery and the elimination of the otherwise necessary special filling with a low-viscosity hydraulic fluid.
  • an industrial truck 1 is shown with a battery-electric drive.
  • the industrial truck 1 is designed as a counterbalanced forklift truck. It turns out that the industrial truck 1 can alternatively be designed as a reach truck or warehouse truck.
  • a traction battery 2 for the electric drive is housed in the industrial truck 1 .
  • At least one electrical unit 3 is electrically connected to the traction battery 2 .
  • the electrical unit 3 is in the form of an electric traction motor 3 which drives at least one drive wheel 4 of the industrial truck 1 .
  • the provided by the traction battery 2 electrical energy is using a in the figure 1 Power electronics, not shown, forwarded to the electric drive motor 3, which is in driving connection with the at least one drive wheel 4 of the industrial truck 1.
  • the traction motor 3 When braking the industrial truck 1 as a generator, the traction motor 3 is operated as a generator, which converts the kinetic energy of the industrial truck 1 into electrical energy during the braking phase. At least part of this electrical energy is fed back into the traction battery 2 . In this way, braking energy can be recovered, ie recuperation.
  • the truck 1 is equipped with a working and control hydraulics, which has a in the figure 1 Hydraulic fluid circuit not shown in detail supplies the control hydraulics of a hydraulic steering of the steered wheels 5 and/or the working hydraulics of a lifting mast 6 with hydraulic fluid.
  • a hydraulic fluid tank 7 is part of the hydraulic fluid circuit figure 1 is in the hydraulic fluid tank 7, an electrical resistor 8 is arranged, which is designed for example as a resistance coil. The electrical resistance 8 is electrically connected to the traction battery 2 and to the electric traction motor 3 .
  • the traction battery 2 is not able to absorb the electrical recuperation energy that arises when the industrial truck 1 is braked due to the generator operation of the electric traction motor 3 .
  • This can be the case in particular with a cold, fully charged traction battery 2 .
  • at least part of the electrical energy generated by the electric traction motor 3 in generator mode is supplied to the electrical resistor 8, which has the function of a braking resistor.
  • the generated in the generator operation of the electric traction motor 3 is electrical energy converted into heat energy and transferred to the surrounding hydraulic fluid in the hydraulic fluid tank 7.
  • the hydraulic fluid circuit is also provided with a temperature sensor 10 with which the temperature of the hydraulic fluid in the hydraulic fluid circuit can be detected.
  • the electrical resistor 8 also has the function of a heating resistor, with which the hydraulic fluid can be heated when the hydraulic fluid is cold. In its function as a heating resistor, the electrical resistor is operated with electrical energy from the traction battery 2 .
  • the electrical resistor 8 designed as a combined heating and braking resistor, the following two problems that occur at low operating temperatures can be solved simultaneously: On the one hand, the recuperation energy generated when braking the industrial truck 1 and which cannot be absorbed by the cold, fully charged traction battery 2 can be reliably dissipated with the electrical resistor 8 in its function as a braking resistor. This ensures that the industrial truck 1 is safe to drive under all operating conditions.
  • the hydraulic fluid in the hydraulic fluid tank 7 can be specifically heated with the electrical resistor 8 in its function as a heating resistor in order to avoid the operating and wear problems occurring at low ambient temperatures due to the high viscosity.
  • the heating of the cold hydraulic fluid in the hydraulic fluid tank 7 with the electrical resistance 8 means that all hydraulic functions are fully available more quickly.
  • an electronic vehicle control device 9 is provided, which is in operative connection with the traction motor 3, the traction battery 2 and the temperature sensor 10 in the hydraulic fluid tank 7.
  • the vehicle control device 9 is designed such that a feed of when the industrial truck 1 is electrically braked in the electric traction motor 3, the electrical energy generated is fed into the traction battery 2 and/or into the electrical resistor 8 depending on the state of charge of the traction battery 2, and the electrical resistor 8 is supplied with electrical energy from the traction battery 2 as a function is carried out based on the temperature of the hydraulic fluid measured at the temperature sensor 10 .
  • the figure 2 shows the hydraulic fluid tank 7 from FIG figure 1 in detail.
  • the hydraulic fluid 11 is located in the hydraulic fluid tank 7 .
  • a fastening flange 12 is mounted on the bottom or on another surface of the hydraulic fluid tank 7 .
  • the electrical resistor 8 can be built into the hydraulic fluid tank 7 by means of the fastening flange 12 .
  • the electrical resistor 8 can be designed as a resistance coil 8a in the form of a coiled metal wire or as a resistance ring 8b in the form of an annular metal wire. In the figure 2 Both variants are shown together for illustration.
  • the electrical resistance 8 is supplied from the outside via electrical supply lines 13 with the electrical recuperation energy in the generator mode of the traction motor 3 or with electrical energy from the traction battery 2 . In the electrical resistor 8, the electrical energy is converted into thermal energy, which is released to the surrounding hydraulic fluid.
  • the electrical resistance 8 designed as a resistance coil 8a is installed in a hydraulic line 14 of the working and/or control hydraulics.
  • the resistance coil 8a is supplied from the outside via electrical supply lines 13 with the electrical recuperation energy when the traction motor 3 is in generator operation or with electrical energy from the traction battery 2 .
  • the hydraulic fluid 11 flowing in the hydraulic line 14 flows around the resistance coil 8a and absorbs the thermal energy emitted by the resistance coil 8a.
  • the figure 4 shows a further embodiment, in which the electrical resistance 8 designed as a resistance coil 8a is mounted in the suction area 16 of a suction filter 15 arranged in the hydraulic fluid tank 7 .
  • the hydraulic fluid 11 in the hydraulic fluid tank 7 is sucked in in the intake area 16 of the suction filter 15 and via an outlet port 17 to a Hydraulic line 18 of the hydraulic circuit released.
  • the resistance coil 8a is supplied from the outside via electrical supply lines 13 with the electrical recuperation energy when the traction motor 3 is in generator operation or with electrical energy from the traction battery 2 .
  • the hydraulic fluid 11 flowing in the suction region 16 of the suction filter 15 flows around the resistance coil 8a and absorbs the thermal energy emitted by the resistance coil 8a.

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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)
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Description

Die Erfindung betrifft ein elektrisch, insbesondere batterie-elektrisch, betriebenes Flurförderzeug mit mindestens einem elektrischen Aggregat, das als Generator betreibbar ist und das mit mindestens einem elektrischen Widerstand zum Umwandeln von elektrischer Energie in Wärmeenergie elektrisch verbunden ist, und mit einer Arbeits- und/oder Steuerungshydraulik, die einen Hydraulikflüssigkeitskreislauf aufweist, wobei der elektrische Widerstand mit dem Hydraulikflüssigkeitskreislauf zur Übertragung der Wärmeenergie auf die Hydraulikflüssigkeit des Hydraulikflüssigkeitskreislaufs in Wirkverbindung steht, wobei das elektrische Aggregat von einem elektrischen Fahrmotor des Flurförderzeugs gebildet ist und wobei das Flurförderzeug über eine Traktionsbatterie verfügt, die mit dem elektrischen Aggregat und mit dem elektrischen Widerstand elektrisch verbunden ist.The invention relates to an electrically, in particular battery-powered, industrial truck with at least one electrical unit that can be operated as a generator and is electrically connected to at least one electrical resistor for converting electrical energy into heat energy, and with a working and/or Control hydraulics, which has a hydraulic fluid circuit, with the electrical resistance being in operative connection with the hydraulic fluid circuit for transferring the thermal energy to the hydraulic fluid of the hydraulic fluid circuit, with the electrical unit being formed by an electric drive motor of the industrial truck, and with the industrial truck having a traction battery which is is electrically connected to the electrical unit and to the electrical resistance.

Elektrisch betriebene Flurförderzeuge können über verbrennungsmotorisch-elektrische oder batterie-elektrische Antriebssysteme verfügen.Electrically operated industrial trucks can have internal combustion engine-electric or battery-electric drive systems.

Bei Flurförderzeugen mit einem verbrennungsmotorisch-elektrischen Antriebssystem sind elektrische Aggregate an den Verbrennungsmotor gekoppelt. Hierzu ist mindestens ein elektrischer Generator vorgesehen, der von einem Verbrennungsmotor angetrieben wird. Die von dem Generator erzeugte elektrische Energie wird mittels einer Leistungselektronik an einen oder mehrere elektrische Fahrmotoren weitergeleitet, die mit den angetriebenen Rädern des Flurförderzeugs in trieblicher Verbindung stehen.In industrial trucks with an internal combustion engine-electric drive system, electrical units are coupled to the internal combustion engine. For this purpose, at least one electrical generator is provided, which is driven by an internal combustion engine. The electrical energy generated by the generator is forwarded by means of power electronics to one or more electric traction motors, which are in driving connection with the driven wheels of the industrial truck.

Derartige Flurförderzeuge werden generatorisch abgebremst. Der bzw. die Fahrmotoren werden hierbei als Generatoren betrieben, welche die kinetische Energie des Flurförderzeugs in der Bremsphase in elektrische Energie umwandelt. Diese elektrische Energie wird bei Flurförderzeugen mit einem verbrennungsmotorisch-elektrischen Antriebssystem dem in diesem Betriebszustand als Motor arbeitenden Generator zugeführt. Ein hierbei auf einen Rotor des Generators wirkendes Drehmoment stützt sich an einer Kurbelwelle des Verbrennungsmotors ab, wodurch sich die Drehzahl des Verbrennungsmotors erhöht. Hieraus resultiert eine verstärkte Lärmerzeugung durch den Verbrennungsmotor und darüber hinaus eine erhöhte mechanische Abnutzung.Such industrial trucks are braked as a generator. The drive motor or motors are operated as generators, which convert the kinetic energy of the industrial truck into electrical energy during the braking phase. In industrial trucks with an internal combustion engine-electric drive system, this electrical energy is supplied to the generator, which operates as a motor in this operating state. A here acting on a rotor of the generator torque is based on a crankshaft of the engine, whereby the speed of the internal combustion engine increases. This results in increased noise generation by the combustion engine and also increased mechanical wear.

Um das oben beschriebene Hochdrehen des Verbrennungsmotors ganz oder teilweise zu verhindern, ist es bekannt, die während eines Bremsens des Flurförderzeugs im Generatorbetrieb des bzw. der Fahrmotore erzeugte Energie ganz oder teilweise mittels eines elektrischen Widerstands in Wärmeenergie umzuwandeln. Eine Kühlung dieses elektrischen Widerstands erfolgt bei bekannten Flurförderzeugen durch Luft oder die Kühlflüssigkeit einer Flüssigkeitskühlung des Verbrennungsmotors.In order to completely or partially prevent the above-described revving up of the internal combustion engine, it is known to convert the energy generated during braking of the industrial truck in generator mode of the traction motor(s) in whole or in part by means of an electrical resistor into thermal energy. In known industrial trucks, this electrical resistance is cooled by air or the coolant of a liquid cooling system for the internal combustion engine.

Bei einer Kühlung des elektrischen Widerstands mittels der Kühlflüssigkeit der Flüssigkeitskühlung des Verbrennungsmotors ist es bekannt, den elektrischen Widerstand in einem separaten Gehäuse anzuordnen, das mittels entsprechender Kühlflüssigkeitsleitungen an den Kühlflüssigkeitskreislauf der Flüssigkeitskühlung des Verbrennungsmotors angeschlossen ist.When cooling the electrical resistance by means of the cooling liquid of the liquid cooling of the internal combustion engine, it is known to arrange the electrical resistance in a separate housing which is connected to the cooling liquid circuit of the liquid cooling of the internal combustion engine by means of corresponding cooling liquid lines.

Ein derartiges separates Gehäuse verursacht jedoch einen zusätzlichen Bauraumbedarf im Aggregateraum des Flurförderzeugs. Zudem verursacht der Anschluss des Gehäuses an den Kühlflüssigkeitskreislauf der Flüssigkeitskühlung des Verbrennungsmotors eine hohe Anzahl von Kühlflüssigkeitsleitungen und somit einen hohen Verrohrungsaufwand, der zudem einen hohen Montageaufwand des Flurförderzeugs zur Folge hat.However, such a separate housing requires additional space in the unit compartment of the industrial truck. In addition, the connection of the housing to the coolant circuit of the liquid cooling system of the internal combustion engine causes a large number of coolant lines and thus a high level of piping complexity, which also results in high assembly costs for the industrial truck.

Aus der EP 2 058 269 B1 ist ein Flurförderzeug mit einem verbrennungsmotorisch-elektrischen Antriebssystem bekannt, bei dem die Flüssigkeitskühlung des Verbrennungsmotors einen Flüssigkeitskühler aufweist, der von einem zwischen Kühlerseitenkästen angeordneten Kühlernetz gebildet ist, wobei der elektrische Widerstand in einen Kühlerseitenkasten des Flüssigkeitskühlers integriert ist.From the EP 2 058 269 B1 an industrial truck with an internal combustion engine-electric drive system is known, in which the liquid cooling of the internal combustion engine has a liquid cooler, which is formed by a cooler network arranged between cooler side boxes, the electrical resistance being integrated in a cooler side box of the liquid cooler.

Diese aus der EP 2 058 269 B1 bekannte Lösung zur Abgabe der Wärmeenergie des elektrischen Widerstands eignet sich allerdings nur für Flurförderzeuge mit einem flüssigkeitsgekühlten, verbrennungsmotorisch-elektrischen Antriebssystem. Für Flurförderzeuge mit batterie-elektrischem Antriebssystem kann diese Lösung nicht verwendet werden, da hier kein Verbrennungsmotor mit einer Flüssigkeitskühlung vorhanden ist.This from the EP 2 058 269 B1 However, the known solution for dissipating the thermal energy of the electrical resistance is only suitable for industrial trucks with a liquid-cooled, internal combustion engine-electric drive system. This solution cannot be used for industrial trucks with a battery-electric drive system be used because there is no internal combustion engine with liquid cooling.

Bei Flurförderzeugen mit einem batterie-elektrischen Antriebssystem sind die elektrischen Aggregate mit einer Traktionsbatterie elektrisch verbunden. Die von der Traktionsbatterie zur Verfügung gestellte elektrische Energie wird mittels einer Leistungselektronik an einen oder mehrere elektrische Fahrmotoren weitergeleitet, die mit den angetriebenen Rädern des Flurförderzeugs in trieblicher Verbindung stehen.In industrial trucks with a battery-electric drive system, the electrical units are electrically connected to a traction battery. The electrical energy made available by the traction battery is forwarded by means of power electronics to one or more electric traction motors, which are in driving connection with the driven wheels of the industrial truck.

Auch bei Flurförderzeugen mit batterie-elektrischen Antriebssystemen ist ein generatorisches Abbremsen des Flurförderzeugs üblich. Dabei werden der bzw. die Fahrmotoren als Generatoren betrieben, welche die kinetische Energie des Flurförderzeugs in der Bremsphase in elektrische Energie umwandeln. Diese elektrische Energie wird in die Traktionsbatterie zurückgespeist. Auf diese Weise kann eine Bremsenergierückgewinnung erfolgen, die allgemein als Rekuperation bezeichnet wird.Regenerative braking of the industrial truck is also common in industrial trucks with battery-electric drive systems. The drive motor or motors are operated as generators, which convert the kinetic energy of the industrial truck into electrical energy during the braking phase. This electrical energy is fed back into the traction battery. In this way, braking energy can be recovered, which is generally referred to as recuperation.

Insbesondere bei modernen Traktionsbatterien mit niedrigen Innenwiderständen, beispielsweise einer Lithium-Ionen-Traktionsbatterie, stellt sich in bestimmten Betriebszuständen das Problem, dass die Traktionsbatterie nicht in der Lage ist, die Rekuperationsenergie, die beim Abbremsen des Flurförderzeugs im Generatorbetrieb des bzw. der Fahrmotore entsteht, aufzunehmen. Dies kann besonders bei einer kalten, vollgeladenen Traktionsbatterie der Fall sein.In particular with modern traction batteries with low internal resistances, for example a lithium-ion traction battery, the problem arises in certain operating states that the traction battery is not able to use the recuperation energy that occurs when the industrial truck brakes in generator mode of the traction motor or motors. record. This can especially be the case with a cold, fully charged traction battery.

Besonders problematisch kann beispielsweise eine Situation sein, bei der das Flurförderzeug mit einer kalten und vollgeladenen Traktionsbatterie mit voller Last und gegebenenfalls mit einem angehängten Anhänger auf einer langen Rampe abwärtsfährt. Eine derartige Situation muss mit einer Sicherheitsschaltung beherrscht werden. Die bei Flurförderzeugen üblicherweise vorhandene, mechanische Betriebsbremse ist hierfür nicht ausgelegt.For example, a situation in which the industrial truck with a cold and fully charged traction battery is driving down a long ramp with a full load and possibly with a trailer attached can be particularly problematic. Such a situation must be controlled with a safety circuit. The mechanical service brake usually found on industrial trucks is not designed for this.

Bei niedrigen Betriebstemperaturen stellt sich für Flurförderzeuge mit einer Arbeits- und/oder Steuerungshydraulik ein weiteres Problem. Die Hydraulikfunktionen stehen bei kalter Hydraulikflüssigkeit nicht voll zur Verfügung. Dadurch kann beispielsweise bei hydraulischen Lenksystemen des Flurförderzeugs die Lenkfähigkeit eingeschränkt sein. Außerdem können beim Heben und Senken einer Last mit hydraulisch betätigten Hubzylindern Hubfolgefehler entstehen. Dabei können beispielsweise Hubzylinder aufgrund der hohen Viskosität der Hydraulikflüssigkeit nicht in der richtigen Reihenfolge ausgefahren werden. Die hohe Viskosität der Hydraulikflüssigeit kann bei geringen Betriebstemperaturen weiter dazu führen, dass die Last nur langsam gehoben werden kann. Ohne Last funktioniert das Senken des Hubzylinders gegebenenfalls gar nicht oder nur langsam. Darüber hinaus ist der Verschleiß von Hydraulikkomponenten, z.B. Pumpen und Filtern, bei niedrigen Betriebstemperaturen erhöht.At low operating temperatures, another problem arises for industrial trucks with working and/or control hydraulics. The hydraulic functions are not fully available when the hydraulic fluid is cold. As a result, the ability to steer can be restricted, for example, in the case of hydraulic steering systems of the industrial truck being. Lifting sequence errors can also occur when lifting and lowering a load with hydraulically operated lifting cylinders. In this case, for example, lifting cylinders cannot be extended in the correct order due to the high viscosity of the hydraulic fluid. At low operating temperatures, the high viscosity of the hydraulic fluid can also mean that the load can only be lifted slowly. Without a load, the lowering of the lifting cylinder may not work at all or only slowly. In addition, wear and tear on hydraulic components, such as pumps and filters, increases at low operating temperatures.

Bisher wird versucht, diese Probleme dadurch zu mildern, dass die Temperatur der Hydraulikflüssigkeit über Drosselverluste in einem Druckbegrenzungsventil bei hoher Pumpendrehzahl erhöht wird. Die hohe Pumpendrehzahl führt allerdings zu einem hohen Verschleiß der Pumpe, solange die Hydraulikflüssigkeit noch kalt ist.Attempts have been made to alleviate these problems by increasing the temperature of the hydraulic fluid via throttling losses in a pressure-limiting valve at high pump speeds. However, the high pump speed leads to high wear on the pump as long as the hydraulic fluid is still cold.

Häufig wird für den Einsatz eines Flurförderzeugs bei kalten Umgebungstemperaturen, beispielsweise in einem Kühlhaus, auch eine Sonderbefüllung des Hydraulikflüssigkeitskreislaufs mit einer Hydraulikflüssigkeit mit geringer Viskosität durchgeführt.When using an industrial truck in cold ambient temperatures, for example in a cold store, the hydraulic fluid circuit is often also specially filled with a hydraulic fluid of low viscosity.

Die CN 203 580 677 U offenbart ein gattungsgemäßes batterie-elektrisch betriebenes Flurförderzeug mit einer Lithium-Ionen-Batterie, die einen elektrischen Fahrmotor, einen elektrischen Lenkmotor und einen elektrischen Pumpenmotor versorgt. Die Batterie versorgt weiter einen Heizwiderstand, der das Öl im Hydrauliktank aufheizt. In Abhängigkeit von der Temperatur des Hydrauliköls wird die Bestromung des Heizwiderstands ermöglicht.the CN 203 580 677 U discloses a generic battery-powered industrial truck with a lithium-ion battery that supplies an electric traction motor, an electric steering motor and an electric pump motor. The battery also powers a heating resistor that heats the oil in the hydraulic tank. Depending on the temperature of the hydraulic oil, the heating resistor can be energized.

Der vorliegenden Erfindung liegt die Aufgabe zugrunde, ein Flurförderzeug der eingangs genannten Art so auszugestalten, dass auch bei niedrigen Betriebstemperaturen die Fahrzeugsicherheit und die Funktionsfähigkeit der Arbeits- und/oder Steuerungshydraulik gewährleistet sind.The present invention is based on the object of designing an industrial truck of the type mentioned at the outset in such a way that vehicle safety and the functionality of the working and/or control hydraulics are ensured even at low operating temperatures.

Diese Aufgabe wird erfindungsgemäß dadurch gelöst, dass eine elektronische Fahrzeugsteuerungseinrichtung vorgesehen ist, die mit dem elektrischen Fahrmotor, der Traktionsbatterie und einem Temperatursensor im Hydraulikflüssigkeitskreislauf in Wirkverbindung steht und eine Einspeisung der beim elektrischen Abbremsen des Flurförderzeugs im elektrischen Fahrmotor erzeugten elektrischen Energie in die Traktionsbatterie und/oder in den elektrischen Widerstand in Abhängigkeit vom Ladezustand der Traktionsbatterie ermöglicht sowie eine Bestromung des elektrischen Widerstand mit Energie aus der Traktionsbatterie in Abhängigkeit von der Temperatur der Hydraulikflüssigkeit ermöglicht.This object is achieved according to the invention in that an electronic vehicle control device is provided which is in operative connection with the electric traction motor, the traction battery and a temperature sensor in the hydraulic fluid circuit and feeds the electrical energy generated in the electric traction motor when the industrial truck brakes electrically into the Traction battery and / or allows in the electrical resistance depending on the state of charge of the traction battery and allows energization of the electrical resistance with energy from the traction battery depending on the temperature of the hydraulic fluid.

Bei der Erfindung steht der elektrische Widerstand mit dem Hydraulikflüssigkeitskreislauf zur Übertragung der Wärmeenergie auf die Hydraulikflüssigkeit des Hydraulikflüssigkeitskreislaufs in Wirkverbindung.In the case of the invention, the electrical resistance is in operative connection with the hydraulic fluid circuit for the transmission of thermal energy to the hydraulic fluid of the hydraulic fluid circuit.

Auf diese Weise können zwei Probleme, die bei niedrigen Betriebstemperaturen auftreten, gleichzeitig gelöst werden.In this way, two problems that occur at low operating temperatures can be solved simultaneously.

Einerseits kann die beim Bremsen des Flurförderzeugs durch den Generatorbetrieb des bzw. der elektrischen Fahrmotore entstehende Rekuperationsenergie, die beispielsweise von einer kalten und/oder vollgeladenen Traktionsbatterie nicht aufgenommen werden kann, mit dem elektrischen Widerstand zuverlässig abgeführt werden. Dadurch ist die Fahrsicherheit des Flurförderzeugs unter allen Betriebsbedingungen gewährleistet.On the one hand, the recuperation energy generated when braking the industrial truck due to the generator operation of the electric traction motor(s), which cannot be absorbed by a cold and/or fully charged traction battery, for example, can be reliably dissipated with the electrical resistance. This ensures that the industrial truck is safe to drive under all operating conditions.

Andererseits kann die Hydraulikflüssigkeit des Hydraulikflüssigkeitskreislaufs mittels des elektrischen Widerstands gezielt aufgewärmt werden, um die bei niedrigen Umgebungstemperaturen aufgrund der hohen Viskosität der Hydraulikflüssigkeit auftretenden Betriebs- und Verschleißprobleme zu vermeiden. Durch das Aufheizen der kalten Hydraulikflüssigkeit mit dem elektrischen Widerstand wird erreicht, dass alle hydraulischen Funktionen schneller vollumfänglich zur Verfügung stehen.On the other hand, the hydraulic fluid of the hydraulic fluid circuit can be heated up in a targeted manner by means of the electrical resistance in order to avoid the operating and wear problems that occur at low ambient temperatures due to the high viscosity of the hydraulic fluid. By heating up the cold hydraulic fluid with the electrical resistance, all hydraulic functions are fully available more quickly.

Der elektrische Widerstand weist somit die Funktion eines Bremswiderstands auf, mit dem die beim Abbremsen des Flurförderzeugs im Generatorbetrieb des bzw. der Fahrmotore erzeugte elektrische Energie aufgenommen werden kann, und die Funktion eines Heizwiderstandes auf, mit dem bei niedrigen Umgebungstemperaturen die Hydraulikflüssigkeit des Hydraulikflüssigkeitskreislaufs aufgeheizt werden kann. Der elektrische Widerstand bildet somit einen kombinierten Heiz-/Bremswiderstand.The electrical resistor thus has the function of a braking resistor, with which the electrical energy generated when the industrial truck brakes in generator mode of the traction motor(s) can be absorbed, and the function of a heating resistor, with which the hydraulic fluid of the hydraulic fluid circuit can be heated at low ambient temperatures can. The electrical resistance thus forms a combined heating/braking resistance.

Dabei eignet sich die Erfindung sowohl für Flurförderzeuge mit einem verbrennungsmotorisch-elektrischen Antriebsystem als auch für Flurförderzeuge mit einem batterie-elektrische Antriebssystem. In beiden Fällen ergeben sich die kombinierten Vorteile, dass mit dem im Hydraulikflüssigkeitskreislauf angeordneten elektrischen Widerstand die beim Bremsen des Flurförderzeugs erzeugte, überschüssige Energie zuverlässig abgeführt werden kann und gleichzeitig die Hydraulikflüssigkeit der Arbeits- und/oder Steuerungshydraulik des Flurförderzeugs auf günstige Betriebstemperaturen aufgewärmt werden kann.The invention is suitable both for industrial trucks with an internal combustion engine-electric drive system and for industrial trucks with a battery-electric drive system. In both cases, there are the combined advantages that the electrical resistance arranged in the hydraulic fluid circuit can reliably dissipate the excess energy generated when the industrial truck brakes and at the same time the hydraulic fluid of the working and/or control hydraulics of the industrial truck can be heated to favorable operating temperatures.

Bei einem verbrennungsmotorisch-elektrisch betriebenen Flurförderzeug ist aus dem Stand der Technik ( EP 2 058 269 B1 ) zwar eine Konstruktion bekannt, bei der die überschüssige Bremsenergie an die Kühlflüssigkeit des Verbrennungsmotors abgegeben wird. Die bei niedrigen Umgebungstemperaturen auftretenden Probleme beim Betrieb der Arbeits- und/oder Steuerungshydraulik werden dabei aber nicht berücksichtigt. Die Erfindung bietet hier eine elegante Lösung für Flurförderzeuge mit verbrennungsmotorisch-elektrischen Antriebssystemen, die auch über eine Arbeits- und/oder Steuerungshydraulik verfügen.In the case of an internal combustion engine-electrically operated industrial truck, the prior art ( EP 2 058 269 B1 ) Although a construction is known in which the excess braking energy is released to the coolant of the internal combustion engine. However, the problems that occur when operating the working and/or control hydraulics at low ambient temperatures are not taken into account. The invention offers an elegant solution for industrial trucks with internal combustion engine-electric drive systems that also have working and/or control hydraulics.

Besondere Vorteile ergeben sich mit der Erfindung bei batterie-elektrisch betriebenen Flurförderzeugen, weil hier insbesondere bei modernen Batteriesystemen mit niedrigen Innenwiderständen, z.B. Lithium-Ionen-Batterien, die Probleme des generatorischen Abbremsens bei kalter Traktionsbatterie und/oder vollgeladener Traktionsbatterie zuverlässig gelöst werden können.Particular advantages result from the invention in battery-powered industrial trucks, because here, especially in modern battery systems with low internal resistances, e.g. lithium-ion batteries, the problems of regenerative braking when the traction battery is cold and/or the traction battery is fully charged can be reliably solved.

Um eine weitgehende Optimierung aller relevanten Betriebszustände des Flurförderzeugs insbesondere bei niedrigen Umgebungstemperaturen zu ermöglichen, ist erfindungsgemäß eine elektronische Fahrzeugsteuerungseinrichtung vorgesehen, die mit dem elektrischen Fahrmotor, der Traktionsbatterie und dem Temperatursensor im Hydraulikflüssigkeitskreislauf in Wirkverbindung steht. Die Fahrzeugsteuerungseinrichtung ist derart ausgebildet, dass eine Einspeisung der beim elektrischen Abbremsen des Flurförderzeugs im elektrischen Fahrmotor erzeugten elektrischen Energie in die Traktionsbatterie und/oder in den elektrischen Widerstand in Abhängigkeit vom Ladezustand der Traktionsbatterie durchgeführt wird sowie eine Bestromung des elektrischen Widerstandes mit Energie aus der Traktionsbatterie in Abhängigkeit von der Temperatur der Hydraulikflüssigkeit durchgeführt wird. Hierdurch kann auf einfache Weise erzielt werden, dass in Betriebszuständen, in denen die Traktionsbatterie die beim Abbremsen im Generatorbetrieb des Fahrmotors erzeugte elektrische Energie nicht aufnehmen kann, beispielsweise bei kalter und/oder vollgeladener Traktionsbatterie, die beim Abbremsen im Generatorbetrieb des Fahrmotors erzeugte elektrische Energie an dem elektrischen Widerstand in dessen Funktion als Bremswiderstand abgeführt werden kann, und dass kalte Hydraulikflüssigkeit mittels des elektrischen Widerstands in dessen Funktion als Heizwiderstand, in der der elektrische Widerstand mit Strom aus der Traktionsbatterie betrieben wird, aufgeheizt werden kann.In order to enable extensive optimization of all relevant operating states of the industrial truck, especially at low ambient temperatures, an electronic vehicle control device is provided according to the invention, which is operatively connected to the electric traction motor, the traction battery and the temperature sensor in the hydraulic fluid circuit. The vehicle control device is designed in such a way that the electrical energy generated in the electric traction motor when the industrial truck is electrically braked is fed into the traction battery and/or into the electrical resistor, depending on the charging status of the traction battery, and the electrical resistor is supplied with energy from the traction battery is carried out depending on the temperature of the hydraulic fluid. This can be achieved in a simple manner that in operating states in which the traction battery generated during braking in the generator mode of the traction motor cannot absorb electrical energy, for example when the traction battery is cold and/or fully charged, the electrical energy generated when braking in generator mode of the traction motor can be dissipated at the electrical resistor in its function as a braking resistor, and that cold hydraulic fluid can be drained by means of the electrical resistor in its function as Heating resistance, in which the electrical resistance is operated with electricity from the traction battery, can be heated.

Gemäß einer vorteilhaften Ausführungsform ist die Traktionsbatterie eine Lithium-Ionen-Batterie. Bei einem Flurförderzeug mit einem batterie-elektrischen Antriebssystem, dessen Traktionsbatterie mit dem elektrischen Aggregat und mit dem elektrischen Widerstand elektrisch verbunden ist, kann der elektrische Widerstand auf einfache Weise mit elektrischer Energie aus der Traktionsbatterie betrieben werden, um die Funktion als Heizwiderstand zu erzielen, mit dem bei niedrigen Umgebungstemperaturen die Hydraulikflüssigkeit des Hydraulikflüssigkeitskreislaufs aufgeheizt werden kann. Dadurch dass der elektrische Widerstand weiterhin mit dem elektrischen Aggregat elektrisch verbunden ist, wird mit dem elektrischen Widerstand auch die Funktion des Bremswiderstands erzielt, der die beim Bremsen im Generatorbetrieb des elektrischen Aggregats entstehende elektrische Energie aufnehmen kann. Die von dem als Generator betriebenen elektrischen Aggregat, beispielsweise dem elektrischen Fahrmotor, in der Bremsphase erzeugte elektrische Energie kann hierbei zumindest teilweise in die Traktionsbatterie rückgespeist und damit die Traktionsbatterie geladen. Von der Traktionsbatterie nicht aufnehmbare überschüssige Energie wird dem zweckmäßigerweise direkt im Hydraulikflüssigkeitskreislauf angeordneten elektrischen Widerstand zugeführt und in Form von Wärmeenergie an die den elektrischen Widerstand umgebende Hydraulikflüssigkeit abgegeben.According to an advantageous embodiment, the traction battery is a lithium-ion battery. In an industrial truck with a battery-electric drive system whose traction battery is electrically connected to the electrical unit and to the electrical resistance, the electrical resistance can be easily operated with electrical energy from the traction battery in order to achieve the function as a heating resistor, with which the hydraulic fluid of the hydraulic fluid circuit can be heated at low ambient temperatures. Because the electrical resistance is still electrically connected to the electrical unit, the electrical resistance also achieves the function of the braking resistor, which can absorb the electrical energy generated during braking in generator mode of the electrical unit. The electrical energy generated during the braking phase by the electrical unit operated as a generator, for example the electrical traction motor, can be at least partially fed back into the traction battery and the traction battery can thus be charged. Excess energy that cannot be absorbed by the traction battery is supplied to the electrical resistance, which is expediently arranged directly in the hydraulic fluid circuit, and is released to the hydraulic fluid surrounding the electrical resistance in the form of heat energy.

Eine zweckmäßige Ausführungsform der Erfindung besteht darin, dass der elektrische Widerstand in einem Hydraulikflüssigkeitstank des Hydraulikflüssigkeitskreislaufs angeordnet ist. Hierzu kann der elektrische Widerstand nachträglich von außen in einen herkömmlichen Hydraulikflüssigkeitstank montiert werden.An expedient embodiment of the invention is that the electrical resistance is arranged in a hydraulic fluid tank of the hydraulic fluid circuit. For this purpose, the electrical resistance can be retrofitted from the outside in a conventional hydraulic fluid tank.

Zur Erleichterung der Montage des elektrischen Widerstands ist der Hydraulikflüssigkeitstank vorzugsweise mit einem Befestigungsflansch für den elektrischen Widerstand versehen.In order to facilitate the assembly of the electrical resistance, the hydraulic fluid tank is preferably provided with a mounting flange for the electrical resistance.

Alternativ oder zusätzlich kann der elektrische Widerstand auch in einer Hydraulikleitung des Hydraulikflüssigkeitskreislaufs angeordnet sein. Somit kommt der elektrische Widerstand für einen Wärmeaustausch mit der die Hydraulikleitung durchströmenden Hydraulikflüssigkeit des Hydraulikflüssigkeitskreislaufs in Kontakt.Alternatively or additionally, the electrical resistance can also be arranged in a hydraulic line of the hydraulic fluid circuit. The electrical resistance for heat exchange thus comes into contact with the hydraulic fluid of the hydraulic fluid circuit flowing through the hydraulic line.

Eine weitere bevorzugte Möglichkeit besteht darin, dass der elektrische Widerstand in einer Hydraulikkomponente des Hydraulikflüssigkeitskreislaufs, insbesondere in einem Hydraulikfilter und/oder in einem Hydraulikventil und/oder in einer Hydraulikpumpe, angeordnet ist.A further preferred possibility is that the electrical resistance is arranged in a hydraulic component of the hydraulic fluid circuit, in particular in a hydraulic filter and/or in a hydraulic valve and/or in a hydraulic pump.

Besonders vorteilhaft ist eine Anordnung des elektrischen Widerstands im Ansaugbereich eines in einem Hydraulikflüssigkeitstank vorgesehenen Saugfilters. Hier ist einerseits gewährleistet, dass der elektrische Widerstand für einen wirkungsvollen Wärmeaustausch allseits von Hydraulikflüssigkeit im Hydraulikflüssigkeitstank umgeben ist und andererseits aufgrund der Ansaugströmung ein kontinuierlicher Abtransport der überschüssigen Wärmeenergie gewährleistet ist.An arrangement of the electrical resistance in the suction region of a suction filter provided in a hydraulic fluid tank is particularly advantageous. On the one hand, this ensures that the electrical resistance is surrounded on all sides by hydraulic fluid in the hydraulic fluid tank for effective heat exchange and, on the other hand, continuous removal of the excess heat energy is ensured due to the intake flow.

Der elektrische Widerstand ist zweckmäßigerweise als Widerstandswendel ausgebildet. Dabei kann es sich beispielsweise um einen gewendelten Metalldraht handeln, der von elektrischem Strom durchflossen wird. Diese Ausgestaltung hat den Vorteil, dass sie platzsparend ist und auf einfache Weise sowohl in Hydraulikflüssigkeitstanks als auch in Hydraulikleitungen und Hydraulikkomponenten installiert werden kann.The electrical resistance is expediently designed as a resistance coil. This can be, for example, a coiled metal wire through which an electric current flows. This configuration has the advantage that it saves space and can be easily installed both in hydraulic fluid tanks and in hydraulic lines and hydraulic components.

Insbesondere beim Einbau des elektrischen Widerstands in den Hydraulikflüssigkeitstank kann der elektrische Widerstand aufgrund der großzügigeren Platzverhältnisse auch in Kreisform oder als einfache Schlinge ausgebildet sein.In particular when installing the electrical resistance in the hydraulic fluid tank, the electrical resistance can also be in the form of a circle or a simple loop due to the more generous space available.

Gemäß einer bevorzugten Weiterbildung der Erfindung ist im Hydraulikflüssigkeitskreislauf der die Temperatur der Hydraulikflüssigkeit erfassender Temperatursensor vorgesehen, der mit der elektrischen Steuerungseinrichtung in Wirkverbindung steht, die eine Steuerung der Temperatur der Hydraulikflüssigkeit mittels Bestromung des elektrischen Widerstands mit Strom aus der Traktionsbatterie ermöglicht, die mit dem elektrischen Widerstand verbunden ist. Auf diese Weise kann mit dem elektrischen Widerstand und dessen Funktion als Heizwiderstand die Temperatur der Hydraulikflüssigkeit gezielt auf eine gewünschte Temperatur aufgeheizt und/oder in einem vorbestimmten Temperaturbereich gehalten werden. Somit kann ein optimaler Viskositätsbereich der Hydraulikflüssigkeit eingestellt werden. Dies ermöglicht es auch auf einfache Weise, bei niedrigen Umgebungstemperaturen die Hydraulikflüssigkeit aufzuheizen, so dass die hydraulischen Funktionen in einer kurzen Zeit vollumfänglich zur Verfügung stehen.According to a preferred development of the invention, the temperature sensor that detects the temperature of the hydraulic fluid is provided in the hydraulic fluid circuit and is connected to the electrical control device in Active connection is that allows control of the temperature of the hydraulic fluid by means of energizing the electrical resistance with electricity from the traction battery, which is connected to the electrical resistance. In this way, the temperature of the hydraulic fluid can be specifically heated to a desired temperature and/or kept within a predetermined temperature range with the electrical resistor and its function as a heating resistor. An optimum viscosity range for the hydraulic fluid can thus be set. This also makes it easy to heat up the hydraulic fluid at low ambient temperatures, so that the hydraulic functions are fully available in a short time.

Der elektrische Fahrmotor ist gemäß einer bevorzugten Ausführungsform der Erfindung ein Asynchronmotor. In der Bremsphase des Flurförderzeugs wird der elektrische Fahrmotor als Generator betrieben und wandelt die kinetische Energie des Flurförderzeugs in elektrische Energie um. Mittels des in den Hydraulikflüssigkeitskreislauf integrierten elektrischen Widerstands kann hierbei mit dessen Funktion als Bremswiderstand die von dem als Generator betriebenen Fahrmotor erzeugte elektrische Energie mit geringem Bauaufwand und ohne zusätzlichen Bauraumbedarf als Wärmenergie in die Hydraulikflüssigkeit abgegeben werden.According to a preferred embodiment of the invention, the electric traction motor is an asynchronous motor. When the truck is braking, the electric drive motor is operated as a generator and converts the kinetic energy of the truck into electrical energy. By means of the electrical resistance integrated in the hydraulic fluid circuit, with its function as a braking resistor, the electrical energy generated by the traction motor operated as a generator can be released as thermal energy into the hydraulic fluid with little construction effort and without additional space requirements.

Die Erfindung bietet eine ganze Reihe von Vorteilen:
Mit Hilfe der Erfindung kann eine schnellere Verfügbarkeit des vollen Funktionsumfangs des kalten Flurförderzeugs erreicht werden. Die Sicherheitsanforderung für das Abbremsen eines kalten, voll beladenen batterie-elektrisch betriebenen Fahrzeugs beispielsweise an einer Rampe kann kostengünstig gewährleistet werden. Außerdem ist die Lösung nachrüstbar und als Option für Serienfahrzeuge geeignet. Darüber hinaus ist die vorgeschlagene technische Lösung kostengünstig und löst zwei Problemstellungen gleichzeitig. Einsparungen ergeben sich zusätzlich durch Entfall des Bremswiderstands in der Traktionsbatterie sowie durch Entfall einer sonst notwendigen Sonderbefüllung mit einer Hydraulikflüssigkeit mit niedriger Viskosität.The invention offers a whole range of advantages:
With the help of the invention, faster availability of the full range of functions of the cold industrial truck can be achieved. The safety requirement for braking a cold, fully loaded battery-powered vehicle, for example on a ramp, can be guaranteed at low cost. The solution can also be retrofitted and is suitable as an option for series vehicles. In addition, the proposed technical solution is inexpensive and solves two problems at the same time. Additional savings result from the elimination of the braking resistor in the traction battery and the elimination of the otherwise necessary special filling with a low-viscosity hydraulic fluid.

Weitere Vorteile und Einzelheiten der Erfindung werden anhand der in den schematischen Figuren dargestellten Ausführungsbeispiele näher erläutert. Hierbei zeigen

Figur 1
ein erfindungsgemäßes batterie-elektrisch betriebenes Flurförderzeug,
Figur 2
die Anordnung des elektrischen Widerstands im Hydraulikflüssigkeitstank,
Figur 3
die Anordnung des elektrischen Widerstands in der Hydraulikleitung und
Figur 4
die Anordnung des elektrischen Widerstands vor dem Saugfilter.
Further advantages and details of the invention are explained in more detail with reference to the exemplary embodiments illustrated in the schematic figures. show here
figure 1
a battery-powered industrial truck according to the invention,
figure 2
the arrangement of the electrical resistance in the hydraulic fluid tank,
figure 3
the arrangement of the electrical resistance in the hydraulic line and
figure 4
the arrangement of the electrical resistance in front of the suction filter.

In der Figur 1 ist ein Flurförderzeug 1 mit einem batterie-elektrischem Antrieb dargestellt. Das Flurförderzeug 1 ist im dargestellten Ausführungsbeispiel als Gegengewichtsgabelstapler ausgebildet. Es ersteht sich, dass das Flurförderzeug 1 alternativ als Schubmaststapler oder Lagertechnikflurförderzeug ausgebildet sein kann.In the figure 1 an industrial truck 1 is shown with a battery-electric drive. In the exemplary embodiment shown, the industrial truck 1 is designed as a counterbalanced forklift truck. It turns out that the industrial truck 1 can alternatively be designed as a reach truck or warehouse truck.

Eine Traktionsbatterie 2 für den elektrischen Antrieb ist im Flurförderzeug 1 untergebracht. Mit der Traktionsbatterie 2 ist mindestens ein elektrische Aggregat 3 elektrisch verbunden. Das elektrische Aggregat 3 ist im dargestellten Ausführungsbeispiel als elektrischer Fahrmotor 3 ausgebildet, der mindestens ein Antriebsrad 4 des Flurförderzeugs 1 antreibt. Die von der Traktionsbatterie 2 zur Verfügung gestellte elektrische Energie wird mittels einer in der Figur 1 nicht dargestellten Leistungselektronik an den elektrischen Fahrmotor 3 weitergeleitet, der mit dem mindestens einen Antriebsrad 4 des Flurförderzeugs 1 in trieblicher Verbindung steht.A traction battery 2 for the electric drive is housed in the industrial truck 1 . At least one electrical unit 3 is electrically connected to the traction battery 2 . In the exemplary embodiment shown, the electrical unit 3 is in the form of an electric traction motor 3 which drives at least one drive wheel 4 of the industrial truck 1 . The provided by the traction battery 2 electrical energy is using a in the figure 1 Power electronics, not shown, forwarded to the electric drive motor 3, which is in driving connection with the at least one drive wheel 4 of the industrial truck 1.

Beim generatorischen Abbremsen des Flurförderzeugs 1 wird der Fahrmotor 3 als Generator betrieben, welcher die kinetische Energie des Flurförderzeugs 1 in der Bremsphase in elektrische Energie umwandelt. Diese elektrische Energie wird zumindest teilweise in die Traktionsbatterie 2 rückgespeist. Auf diese Weise kann eine Bremsenergierückgewinnung, also eine Rekuperation, erfolgen.When braking the industrial truck 1 as a generator, the traction motor 3 is operated as a generator, which converts the kinetic energy of the industrial truck 1 into electrical energy during the braking phase. At least part of this electrical energy is fed back into the traction battery 2 . In this way, braking energy can be recovered, ie recuperation.

Das Flurförderzeug 1 ist mit einer Arbeits- und Steuerungshydraulik ausgestattet, die über einen in der Figur 1 nicht näher dargestellten Hydraulikflüssigkeitskreislauf die Steuerungshydraulik einer hydraulischen Lenkung der gelenkten Räder 5 und/oder die Arbeitshydraulik eines Hubmastes 6 mit Hydraulikflüssigkeit versorgt. Bestandteil des Hydraulikflüssigkeitskreislaufs ist ein Hydraulikflüssigkeitstank 7. In der Figur 1 ist in dem Hydraulikflüssigkeitstank 7 ein elektrischer Widerstand 8 angeordnet, der beispielsweise als Widerstandswendel ausgebildet ist. Der elektrische Widerstand 8 ist mit der Traktionsbatterie 2 sowie mit dem elektrischen Fahrmotor 3 elektrisch verbunden.The truck 1 is equipped with a working and control hydraulics, which has a in the figure 1 Hydraulic fluid circuit not shown in detail supplies the control hydraulics of a hydraulic steering of the steered wheels 5 and/or the working hydraulics of a lifting mast 6 with hydraulic fluid. A hydraulic fluid tank 7 is part of the hydraulic fluid circuit figure 1 is in the hydraulic fluid tank 7, an electrical resistor 8 is arranged, which is designed for example as a resistance coil. The electrical resistance 8 is electrically connected to the traction battery 2 and to the electric traction motor 3 .

In bestimmten Betriebszuständen ist die Traktionsbatterie 2 nicht in der Lage, die elektrische Rekuperationsenergie, die beim Abbremsen des Flurförderzeugs 1 durch einen Generatorbetrieb des elektrischen Fahrmotors 3 entsteht, aufzunehmen. Dies kann besonders bei einer kalten, vollgeladenen Traktionsbatterie 2 der Fall sein. In diesen Fällen wird zumindest ein Teil der von dem elektrischen Fahrmotor 3 im Generatorbetrieb erzeugten elektrischen Energie dem elektrische Widerstand 8 zugeführt, der die Funktion eines Bremswiderstands aufweist. Im elektrischen Widerstand 8 wird die im Generatorbetrieb des elektrischen Fahrmotors 3 erzeugten elektrischen Energie in Wärmeenergie umgewandelt und an die umgebende Hydraulikflüssigkeit im Hydraulikflüssigkeitstank 7 übertragen.In certain operating states, the traction battery 2 is not able to absorb the electrical recuperation energy that arises when the industrial truck 1 is braked due to the generator operation of the electric traction motor 3 . This can be the case in particular with a cold, fully charged traction battery 2 . In these cases, at least part of the electrical energy generated by the electric traction motor 3 in generator mode is supplied to the electrical resistor 8, which has the function of a braking resistor. In the electrical resistance 8, the generated in the generator operation of the electric traction motor 3 is electrical energy converted into heat energy and transferred to the surrounding hydraulic fluid in the hydraulic fluid tank 7.

Der Hydraulikflüssigkeitskreislauf ist weiterhin mit einem Temperatursensor 10 versehen, mit dem die Temperatur der Hydraulikflüssigkeit des Hydraulikflüssigkeitskreislaufs erfasst werden kann. Der elektrische Widerstand 8 weist weiterhin die Funktion eines Heizwiderstands auf, mit dem bei kalter Hydraulikflüssigkeit die Hydraulikflüssigkeit aufgeheizt werden kann. In der Funktion als Heizwiderstand wird der elektrische Widerstand mit elektrischer Energie aus der Traktionsbatterie 2 betrieben.The hydraulic fluid circuit is also provided with a temperature sensor 10 with which the temperature of the hydraulic fluid in the hydraulic fluid circuit can be detected. The electrical resistor 8 also has the function of a heating resistor, with which the hydraulic fluid can be heated when the hydraulic fluid is cold. In its function as a heating resistor, the electrical resistor is operated with electrical energy from the traction battery 2 .

Mit dem als kombinierten Heiz-/und Bremswiderstand ausgebildeten elektrischen Widerstand 8 können die folgenden zwei Probleme, die bei niedrigen Betriebstemperaturen auftreten, gleichzeitig gelöst werden:
Einerseits kann mit dem elektrischen Widerstand 8 in dessen Funktion als Bremswiderstand die beim Bremsen des Flurförderzeugs 1 entstehende Rekuperationsenergie, die von der kalten, vollgeladenen Traktionsbatterie 2 nicht aufgenommen werden kann, zuverlässig abgeführt werden. Dadurch ist die Fahrsicherheit des Flurförderzeugs 1 unter allen Betriebsbedingungen gewährleistet.With the electrical resistor 8 designed as a combined heating and braking resistor, the following two problems that occur at low operating temperatures can be solved simultaneously:
On the one hand, the recuperation energy generated when braking the industrial truck 1 and which cannot be absorbed by the cold, fully charged traction battery 2 can be reliably dissipated with the electrical resistor 8 in its function as a braking resistor. This ensures that the industrial truck 1 is safe to drive under all operating conditions.

Andererseits kann mit dem elektrischen Widerstand 8 in dessen Funktion als Heizwiderstand die Hydraulikflüssigkeit im Hydraulikflüssigkeitstank 7 gezielt aufgewärmt werden, um die bei niedrigen Umgebungstemperaturen aufgrund der hohen Viskosität auftretenden Betriebs- und Verschleißprobleme zu vermeiden. Durch das Aufheizen der kalten Hydraulikflüssigkeit im Hydraulikflüssigkeitstank 7 mit dem elektrischen Widerstand 8 wird erreicht, dass alle hydraulischen Funktionen schneller vollumfänglich zur Verfügung stehen.On the other hand, the hydraulic fluid in the hydraulic fluid tank 7 can be specifically heated with the electrical resistor 8 in its function as a heating resistor in order to avoid the operating and wear problems occurring at low ambient temperatures due to the high viscosity. The heating of the cold hydraulic fluid in the hydraulic fluid tank 7 with the electrical resistance 8 means that all hydraulic functions are fully available more quickly.

Um eine weitgehende Optimierung aller relevanten Betriebszustände des Flurförderzeugs 1, insbesondere bei niedrigen Umgebungstemperaturen, zu ermöglichen, ist eine elektronische Fahrzeugsteuerungseinrichtung 9 vorgesehen, die mit dem Fahrmotor 3, der Traktionsbatterie 2 und dem Temperatursensor 10 im Hydraulikflüssigkeitstank 7 in Wirkverbindung steht. Die Fahrzeugsteuerungseinrichtung 9 ist derart ausgebildet, dass eine Einspeisung der beim elektrischen Abbremsen des Flurförderzeugs 1 im elektrischen Fahrmotor 3 erzeugten elektrischen Energie in die Traktionsbatterie 2 und/oder in den elektrischen Widerstand 8 in Abhängigkeit vom Ladezustand der Traktionsbatterie 2 durchgeführt wird sowie eine Bestromung des elektrischen Widerstands 8 mit elektrischer Energie aus der Traktionsbatterie 2 in Abhängigkeit von der am Temperatursensor 10 gemessenen Temperatur der Hydraulikflüssigkeit durchgeführt wird.In order to enable extensive optimization of all relevant operating states of the industrial truck 1, especially at low ambient temperatures, an electronic vehicle control device 9 is provided, which is in operative connection with the traction motor 3, the traction battery 2 and the temperature sensor 10 in the hydraulic fluid tank 7. The vehicle control device 9 is designed such that a feed of when the industrial truck 1 is electrically braked in the electric traction motor 3, the electrical energy generated is fed into the traction battery 2 and/or into the electrical resistor 8 depending on the state of charge of the traction battery 2, and the electrical resistor 8 is supplied with electrical energy from the traction battery 2 as a function is carried out based on the temperature of the hydraulic fluid measured at the temperature sensor 10 .

Die Figur 2 zeigt den Hydraulikflüssigkeitstank 7 aus der Figur 1 im Detail. Im Hydraulikflüssigkeitstank 7 befindet sich die Hydraulikflüssigkeit 11. Am Boden oder einer anderen Fläche des Hydraulikflüssigkeitstanks 7 ist ein Befestigungsflansch 12 montiert. Mittels des Befestigungsflansches 12 kann der elektrische Widerstand 8 in den Hydraulikflüssigkeitstank 7 eingebaut werden. Der elektrische Widerstand 8 kann als Widerstandswendel 8a in Form eines gewendelten Metalldrahtes oder als Widerstandsring 8b in Form eines ringförmigen Metalldrahtes ausgebildet sein. In der Figur 2 sind beide Varianten zur Veranschaulichung gemeinsam gezeigt. Der elektrische Widerstand 8 wird von außen über elektrische Zuleitungen 13 mit der elektrischen Rekuperationsenergie im Generatorbetrieb des Fahrmotors 3 oder mit elektrischer Energie aus der Traktionsbatterie 2 versorgt. Im elektrischen Widerstand 8 wird die elektrische Energie in Wärmeenergie umgewandelt, die an die umgebende Hydraulikflüssigkeit abgegeben wird.the figure 2 shows the hydraulic fluid tank 7 from FIG figure 1 in detail. The hydraulic fluid 11 is located in the hydraulic fluid tank 7 . A fastening flange 12 is mounted on the bottom or on another surface of the hydraulic fluid tank 7 . The electrical resistor 8 can be built into the hydraulic fluid tank 7 by means of the fastening flange 12 . The electrical resistor 8 can be designed as a resistance coil 8a in the form of a coiled metal wire or as a resistance ring 8b in the form of an annular metal wire. In the figure 2 Both variants are shown together for illustration. The electrical resistance 8 is supplied from the outside via electrical supply lines 13 with the electrical recuperation energy in the generator mode of the traction motor 3 or with electrical energy from the traction battery 2 . In the electrical resistor 8, the electrical energy is converted into thermal energy, which is released to the surrounding hydraulic fluid.

In der Figur 3 ist eine Variante dargestellt, bei der der als Widerstandswendel 8a ausgebildete elektrische Widerstand 8 in eine Hydraulikleitung 14 der Arbeits- und/oder Steuerungshydraulik eingebaut ist. Die Widerstandswendel 8a wird von außen über elektrische Zuleitungen 13 mit der elektrischen Rekuperationsenergie im Generatorbetrieb des Fahrmotors 3 oder mit elektrischer Energie aus der Traktionsbatterie 2 versorgt. Die in der Hydraulikleitung 14 strömende Hydraulikflüssigkeit 11 umströmt die Widerstandswendel 8a und nimmt die von der Widerstandswendel 8a abgegebene Wärmeenergie auf.In the figure 3 a variant is shown in which the electrical resistance 8 designed as a resistance coil 8a is installed in a hydraulic line 14 of the working and/or control hydraulics. The resistance coil 8a is supplied from the outside via electrical supply lines 13 with the electrical recuperation energy when the traction motor 3 is in generator operation or with electrical energy from the traction battery 2 . The hydraulic fluid 11 flowing in the hydraulic line 14 flows around the resistance coil 8a and absorbs the thermal energy emitted by the resistance coil 8a.

Die Figur 4 zeigt eine weitere Ausgestaltung, bei der der als Widerstandswendel 8a ausgebildete elektrische Widerstand 8 im Ansaugbereich 16 eines im Hydraulikflüssigkeitstank 7 angeordneten Saugfilters 15 montiert ist. Die im Hydraulikflüssigkeitstank 7 befindliche Hydraulikflüssigkeit 11 wird im Ansaugbereich 16 des Saugfilters 15 angesaugt und über einen Ablaufstutzen 17 an eine Hydraulikleitung 18 des Hydraulikkreislaufs abgegeben. Die Widerstandswendel 8a wird von außen über elektrische Zuleitungen 13 mit der elektrischen Rekuperationsenergie im Generatorbetrieb des Fahrmotors 3 oder mit elektrischer Energie aus der Traktionsbatterie 2 versorgt. Die im Ansaugbereich 16 des Saugfilters 15 strömende Hydraulikflüssigkeit 11 umströmt die Widerstandswendel 8a und nimmt die von der Widerstandswendel 8a abgegebene Wärmeenergie auf.the figure 4 shows a further embodiment, in which the electrical resistance 8 designed as a resistance coil 8a is mounted in the suction area 16 of a suction filter 15 arranged in the hydraulic fluid tank 7 . The hydraulic fluid 11 in the hydraulic fluid tank 7 is sucked in in the intake area 16 of the suction filter 15 and via an outlet port 17 to a Hydraulic line 18 of the hydraulic circuit released. The resistance coil 8a is supplied from the outside via electrical supply lines 13 with the electrical recuperation energy when the traction motor 3 is in generator operation or with electrical energy from the traction battery 2 . The hydraulic fluid 11 flowing in the suction region 16 of the suction filter 15 flows around the resistance coil 8a and absorbs the thermal energy emitted by the resistance coil 8a.

Claims (10)

  1. Electrically, in particular battery-electrically, operated industrial truck (1) having at least one electrical assembly (3) which can be operated as a generator and which is electrically connected to at least one electrical resistor (8) for converting electrical energy into thermal energy, and having a working and/or control hydraulics system which has a hydraulic liquid circuit, wherein the electrical resistor (8) is operatively connected to the hydraulic liquid circuit for transferring the thermal energy to the hydraulic liquid (11) of the hydraulic liquid circuit, wherein the electrical assembly (3) is formed by an electric traction motor (3) of the industrial truck (1) and wherein the industrial truck (1) has a traction battery (2) which is electrically connected to the electrical assembly (3) and to the electrical resistor (8), wherein an electronic vehicle control device (9) is provided, which is operatively connected to the electric traction motor (3), the traction battery (2) and a temperature sensor (10) in the hydraulic liquid circuit and allows the electrical energy generated in the electric traction motor (3) during electrical braking of the industrial truck (1) to be fed into the traction battery (2) and/or into the electrical resistor (8) depending on the state of charge of the traction battery (2) and allows the electrical resistor (8) to be energized with energy from the traction battery (2) depending on the temperature of the hydraulic liquid (11).
  2. Industrial truck according to Claim 1, characterized in that the traction battery (2) is a lithium-ion battery.
  3. Industrial truck according to Claim 1 or 2, characterized in that the electrical resistor (8) is arranged in a hydraulic liquid tank (7) of the hydraulic liquid circuit.
  4. Industrial truck according to Claim 3, characterized in that the hydraulic liquid tank (7) is provided with a fastening flange (12) for the electrical resistor (8).
  5. Industrial truck according to one of Claims 1 to 4, characterized in that the electrical resistor (8) is arranged in a hydraulic line (14) of the hydraulic liquid circuit.
  6. Industrial truck according to one of Claims 1 to 5, characterized in that the electrical resistor (8) is arranged in a hydraulic component of the hydraulic liquid circuit, in particular in a hydraulic filter and/or in a hydraulic valve and/or in a hydraulic pump.
  7. Industrial truck according to one of Claims 1 to 6, characterized in that the electrical resistor (8) is arranged in the intake region (16) of a suction filter (15) which is provided in a hydraulic liquid tank (7).
  8. Industrial truck according to one of Claims 1 to 7, characterized in that the electrical resistor (8) is configured as a resistor coil (8a).
  9. Industrial truck according to one of Claims 1 to 8, characterized in that the temperature sensor (10) is provided in the hydraulic liquid circuit and is operatively connected to the electrical control device which allows the temperature of the hydraulic liquid (11) to be controlled by means of energizing the electrical resistor (8) with power from the traction battery which is electrically connected to the electrical resistor (8) .
  10. Industrial truck according to one of Claims 1 to 9, characterized in that the electric traction motor (3) is an asynchronous motor.
EP19212025.1A 2018-12-07 2019-11-28 Electrically operated industrial truck Active EP3663253B1 (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE102018131384.5A DE102018131384A1 (en) 2018-12-07 2018-12-07 Electrically powered industrial truck

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EP3663253A1 EP3663253A1 (en) 2020-06-10
EP3663253B1 true EP3663253B1 (en) 2023-01-11

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EP19212025.1A Active EP3663253B1 (en) 2018-12-07 2019-11-28 Electrically operated industrial truck

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EP (1) EP3663253B1 (en)
DE (1) DE102018131384A1 (en)

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19721526A1 (en) * 1997-05-22 1998-11-26 Still Gmbh Industrial truck with an electrical unit
DE102007053842A1 (en) 2007-11-12 2009-05-14 Still Gmbh Industrial truck with an internal combustion engine and an electrical unit
CN203580677U (en) * 2013-10-16 2014-05-07 雷雯 Cold chain electric fork-lift truck

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DE102018131384A1 (en) 2020-06-10

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