US20020026275A1 - Apparatus for controlling a drive system for an industrial truck - Google Patents
Apparatus for controlling a drive system for an industrial truck Download PDFInfo
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- US20020026275A1 US20020026275A1 US09/916,070 US91607001A US2002026275A1 US 20020026275 A1 US20020026275 A1 US 20020026275A1 US 91607001 A US91607001 A US 91607001A US 2002026275 A1 US2002026275 A1 US 2002026275A1
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
- B60W10/00—Conjoint control of vehicle sub-units of different type or different function
- B60W10/04—Conjoint control of vehicle sub-units of different type or different function including control of propulsion units
- B60W10/06—Conjoint control of vehicle sub-units of different type or different function including control of propulsion units including control of combustion engines
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
- B60W10/00—Conjoint control of vehicle sub-units of different type or different function
- B60W10/04—Conjoint control of vehicle sub-units of different type or different function including control of propulsion units
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
- B60W10/00—Conjoint control of vehicle sub-units of different type or different function
- B60W10/10—Conjoint control of vehicle sub-units of different type or different function including control of change-speed gearings
- B60W10/101—Infinitely variable gearings
- B60W10/103—Infinitely variable gearings of fluid type
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
- B60W30/00—Purposes of road vehicle drive control systems not related to the control of a particular sub-unit, e.g. of systems using conjoint control of vehicle sub-units, or advanced driver assistance systems for ensuring comfort, stability and safety or drive control systems for propelling or retarding the vehicle
- B60W30/18—Propelling the vehicle
- B60W30/188—Controlling power parameters of the driveline, e.g. determining the required power
- B60W30/1882—Controlling power parameters of the driveline, e.g. determining the required power characterised by the working point of the engine, e.g. by using engine output chart
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
- F16H61/38—Control of exclusively fluid gearing
- F16H61/40—Control of exclusively fluid gearing hydrostatic
- F16H61/46—Automatic regulation in accordance with output requirements
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
- F16H61/38—Control of exclusively fluid gearing
- F16H61/40—Control of exclusively fluid gearing hydrostatic
- F16H61/46—Automatic regulation in accordance with output requirements
- F16H61/468—Automatic regulation in accordance with output requirements for achieving a target input torque
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
- F16H61/38—Control of exclusively fluid gearing
- F16H61/40—Control of exclusively fluid gearing hydrostatic
- F16H61/46—Automatic regulation in accordance with output requirements
- F16H61/47—Automatic regulation in accordance with output requirements for achieving a target output speed
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
- B60W2510/00—Input parameters relating to a particular sub-units
- B60W2510/06—Combustion engines, Gas turbines
- B60W2510/0638—Engine speed
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
- B60W2520/00—Input parameters relating to overall vehicle dynamics
- B60W2520/10—Longitudinal speed
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
- B60W2710/00—Output or target parameters relating to a particular sub-units
- B60W2710/06—Combustion engines, Gas turbines
- B60W2710/0644—Engine speed
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
- B60W2710/00—Output or target parameters relating to a particular sub-units
- B60W2710/10—Change speed gearings
- B60W2710/105—Output torque
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
- B60W2720/00—Output or target parameters relating to overall vehicle dynamics
- B60W2720/10—Longitudinal speed
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H59/00—Control inputs to control units of change-speed-, or reversing-gearings for conveying rotary motion
- F16H59/68—Inputs being a function of gearing status
- F16H2059/683—Sensing pressure in control systems or in fluid controlled devices, e.g. by pressure sensors
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H59/00—Control inputs to control units of change-speed-, or reversing-gearings for conveying rotary motion
- F16H59/68—Inputs being a function of gearing status
- F16H2059/6838—Sensing gearing status of hydrostatic transmissions
- F16H2059/6861—Sensing gearing status of hydrostatic transmissions the pressures, e.g. high, low or differential pressures
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H59/00—Control inputs to control units of change-speed-, or reversing-gearings for conveying rotary motion
- F16H59/68—Inputs being a function of gearing status
- F16H2059/6838—Sensing gearing status of hydrostatic transmissions
- F16H2059/6876—Sensing gearing status of hydrostatic transmissions the motor speed
Definitions
- This invention relates to an apparatus for controlling a drive system for an industrial truck according to claim 1.
- a hydrostatic transmission usually comprises a hydraulic pump the delivery volume of which is variable and a hydraulic engine. If a differential mechanism is to be realized two hydraulic engines are used which, in turn, are variable in their delivery volumes, if required.
- the hydraulic pump usually is structured so as to allow four-quadrant operation, which means that powering and braking it is possible in the forward and backward directions.
- the electronic control which is known has the disadvantage that the number of revolutions of the internal combustion engine is dependent on the travelling speed.
- the measure which as is known makes it impossible for the internal combustion engine to get stalled is relatively sluggish and pressure-induced vibrations, a juddery motion of the vehicle, and a non-optimal utilization of the power potential of the internal combustion engine may readily occur.
- the inflexible delivery volume preset causes the vehicle to start up with a jerk and causes hydraulic vibrations if disturbing factors act on it.
- the inventive apparatus uses a cascaded control.
- the cascade comprises an overlying speed control circuit and an underlying pressure control circuit.
- the pressure controller compares a transmission pressure measured to a preset pressure (a desired-pressure value) with the pressure controller speedily varying the hydraulic pump delivery volume so as to cause the control error to disappear.
- the overlying speed controller compares the travelling speed desired to the one measured, calculating a desired motive force therefrom.
- the motive force which is desired is converted, in a way which yet is to be described, into a required pumping pressure which is imposed onto the pressure controller as a desired-pressure value.
- a characteristic which indicates an optimal-consumption speed for a given power, exists for each internal combustion engine.
- the driving power required may be calculated from the travelling speed and the motive force. This allows to preset a desired number of revolutions for an internal combustion engine from the characteristics stage in accordance with the characteristic chosen. This one will then be imposed onto a common speed controller for an internal combustion engine.
- the number of revolutions of the internal combustion engine requires to be chosen higher to achieve a sufficient lifting speed. As a result, the number of revolutions ceases to be completely at the minimum of consumption.
- the pressure controller automatically reduces the delivery volume in order not to increase the pressure.
- the engine's characteristics are derived from the rpm-torque-efficiency characteristic diagram of the internal combustion engine.
- an rpm-torque-efficiency characteristic diagram for the pump is stored in the characteristics stage for being taken into account in determining the desired rpm value.
- a travelling speed-torque-efficiency characteristic diagram for the hydraulic engine can be stored in the characteristics stage for being taken into account in determining the desired rpm value.
- a sensor may be disposed on the wheel or the hydraulic engine to determine the number of revolutions for the inventive apparatus and the speed transducer may determine the speed from the number of revolutions and the radius of the wheel.
- an rpm sensor may measure the number of revolutions of the internal combustion engine and calculate the speed therefrom and from the delivery volume of the pump (which corresponds to the transmission gear ratio) while taking into account the radius of the wheel.
- At least one pressure sensor may be provided, as a pressure transducer, at the outlet of the pump.
- the pump may have hydraulic variation inlets which are connected to the pressurized side of an auxiliary pressure source via a proportional valve each. The control input of the proportional valves is acted on by the desired value of the desired-value transducer.
- the characteristic which is employed may be different depending on the operating state of the inventive apparatus or internal combustion engine. Therefore, an aspect of the invention provides that the characteristics stage should have several sub-stages storing a characteristic each and a switch-over device is provided to change over to a sub-stage desired.
- the switch-over device may have a manually operable switch or may be actuated in dependence on the position of the accelerator or its speed of actuation.
- the number of revolutions of the internal combustion engine, the volume displaced by the hydraulic pump, and the number of revolutions of the driven wheel may be resorted to for a determination of the actual-pressure value in the hydrostatic transmission.
- the actual-pressure value may be determined from the torque of the internal combustion engine and the volume displaced by the hydraulic pump.
- the actual-pressure value may also be determined from the pressure in the servo-cylinder for adjusting the hydraulic pump and from the number of revolutions of the internal combustion engine.
- the way of determination may also be chosen different depending on the operating state which exists, e.g. depending on the number of revolutions.
- an aspect of the invention provides that a controllable limitation stage is interposed between the desired-value transducer and the desired-value and actual-value comparator of the pressure control circuit, a second characteristics stage in which an rpm-torque characteristic of the internal combustion engine is stored and provides an output signal to the pressure relief stage, and the inlet is connected to an rpm transducer such that the pressure relief stage presets a pressure signal corresponding to the admissible torque according to a momental value of the characteristics stage and the level of the varying signal for the pump.
- the characteristic in the second characteristics stage may be obtained from a conversion of the characteristic(s) in the first characteristics stage and the corresponding hydraulic pressure and the motive force may be calculated via the actual delivery volume of the hydraulic pump in order to avoid stalling the internal combustion engine.
- the desired-value and actual-value transducer determines the desired-pressure value for the pressure control circuit from the value desired for the motive force, the radius of the vehicle wheel, and the volume displaced by the hydraulic engine.
- the internal combustion engine may drive a second pump having a constant or variable delivery volume for a hydraulic circuit, this having no adverse effect on the efficiency of the inventive apparatus.
- FIG. 1 shows a circuit diagram for an apparatus according to the invention.
- FIG. 2 shows a circuit diagram for a hydraulic pressure control of the hydrostatic transmission of the apparatus of FIG. 1.
- FIG. 3 shows an alternative aspect of a hydraulic pressure control for the hydrostatic transmission of the apparatus of FIG. 1.
- FIG. 1 shows an internal combustion engine 10 which drives a hydraulic pump 12 having a variable delivery volume.
- the hydraulic pump 12 is suited for use with fourquadrant operation.
- the hydraulic pump 12 feeds a fluid to a hydraulic engine which drives a wheel 16 of an industrial truck 18 (not shown). Up to this point, it will be a drive of an industrial truck, which is known as such, by an internal combustion engine which has a hydrostatic transmission.
- the drive system diagrammatically shown in FIG. 1 comprises an underlying pressure control circuit 20 and an overlying speed control circuit 22 .
- a desired-value and actual-value comparator 24 of the pressure control circuit 20 receives a desired value ⁇ p Soll from a desired-value transducer 39 , and an actual value P ist .
- P ist corresponds to the differential pressure in the hydrostatic transmission and, for instance, may be determined by at least one pressure sensor or also by other parameters to be measured, e.g. from the number of revolutions of the internal combustion engine, the volume displaced by the hydraulic pump, and the number of revolutions of the wheel or from the number of revolutions of the internal combustion engine and the volume displaced by the hydraulic pump.
- a pressure controller 26 provides a corresponding signal ⁇ to the pump 12 .
- a desired-value and actual-value comparator 28 of the speed control circuit 22 receives a desired value V Soll for the speed of the industrial truck 18 , e.g. from an accelerator.
- a actual-value transducer 30 for the speed is connected to an rpm transducer where the rpm transducer measures the number of revolutions nm at the outlet of the hydrostatic transmission or on the wheel 16 of the industrial truck 18 .
- the actual-value transducer 30 determines the actual speed via the radius r Rad of the wheel 16 .
- a speed controller 32 determines a desired-value signal F Soll for the motive force of the drive system.
- a first characteristics stage 34 has stored therein a characteristics field which indicates an optimal-consumption number of revolutions. Alternative characteristics can optimize the dynamic behaviour of the internal combustion engine 10 or constitute a compromise.
- the characteristics stage 34 receives the signal F Soll and the signal V Ist and determines the power required and determines the optimal number of revolutions from the corresponding characteristic and provides a desired rpm value n Soll to a speed controller 36 of the internal combustion engine 10 . If the internal combustion engine 10 drives another pump (not shown), e.g. for a hydraulic circuit of the industrial truck, a number of revolutions which is higher than the optimal number of revolutions will possibly be required to allow a faster response of the hydraulic circuit or to influence the speed of variation operations in the hydraulic circuit. To this end, an appropriate signal is provided to the stage 40 MAX via the active-function line 38 , which increases the desired rpm value n Soll by a corresponding amount, but only up to a maximum value.
- the desired value F Soll is converted to a desired-pressure value ⁇ p Soll in the desired-value transducer 39 , namely from the volume displaced by the hydraulic engine 14 and the radius of the wheel 16 .
- the active-action line for the desired-pressure value ⁇ p Soll is acted on by the pressure relief stage 42 , which limits the desired pressure to a maximum admissible value ⁇ p zu understand .
- a second characteristics stage 44 is provided in which an rpm-and-torque characteristic of the internal combustion engine 10 is stored.
- the number of revolutions n v of the internal combustion engine is provided to the characteristics stage 44 and the maximum admissible momental value is determined therefrom in the characteristics stage 44 .
- This value is converted into an admissible pressure in the pressure relief stage 42 according to the variation signal ⁇ for the volume displaced by the pump 12 . This way avoids overloading the internal combustion engine as a result of too high a power requirement. This way can also limit the pressure in the hydrostatic transmission to a maximum value.
- FIG. 2 shows a hydraulic pressure control for the pump 12 and the engine 14 of the hydraulic transmission of FIG. 1.
- the hydraulic pressure is applied to the variation inlets 50 , 52 of the pump 14 via an auxiliary pump 54 .
- the auxiliary pump acts on the inlet of the sliding valve 56 which has electromagnetic control inputs 58 , 60 . They are acted on by the signal ⁇ p of the desired-value transducer 39 of FIG. 1.
- the sliding valve 56 has two hydraulic control inputs which connect with the hydraulic circuit of the hydrostatic transmission and apply the differential pressure to the sliding valve 56 , which corresponds to the real-pressure value.
- two proportional valves 62 , 64 are provided in lieu of one sliding valve, which valves are biased by a spring 66 to the neutral position.
- the two embodiments of FIGS. 2 and 3 provide a pressure control valve 68 to keep the pressure constant in the pump 54 .
- This pump may also be driven by the internal combustion engine.
Abstract
Description
- This invention relates to an apparatus for controlling a drive system for an industrial truck according to claim 1.
- Industrial trucks which are intended to be given a large radius of action or a high efficiency are powered by internal combustion engines. Diesel engines or spark ignition engines powered by fuel gas are mainly used for this purpose.
- It is known to adapt the number of revolutions and the torque of the internal combustion engine to the requirements made to the driving wheels by means of a hydrostatic transmission. A hydrostatic transmission usually comprises a hydraulic pump the delivery volume of which is variable and a hydraulic engine. If a differential mechanism is to be realized two hydraulic engines are used which, in turn, are variable in their delivery volumes, if required. The hydraulic pump usually is structured so as to allow four-quadrant operation, which means that powering and braking it is possible in the forward and backward directions.
- It is known from the company brochure “POCLAIN HYDRAULICS PH” of February, 1998 to employ an electronic control which coordinates the number of revolutions of the internal combustion engine and the delivery volume set for the hydraulic pump with the position of the accelerator and the brake pedal. The delivery volume is varied by a servo-cylinder by means of a lever. The servo-cylinder is acted on by hydraulic oil via two electrically operated proportional valves from two sides. The supply unit of the varing mechanism comprises the feed pump and a pressure relief valve.
- As a rule, monotonically increasing characteristics are preset which assign a number of revolutions of the internal combustion engine and a delivery volume and, hence, a volume flow to each accelerator position. For a flexible drivability, the target values are reached via ramps which limit the amounts of such variations. This also restricts the acceleration of the industrial truck to an admissible rate. Admissible rates are determined via the power potential of the internal combustion engine and the admissible pressure of the hydraulic system.
- If vehicles are loaded the hydrostatic transmission might happen to require the internal combustion engine to deliver a torque that it is unable to deliver. To prevent the internal combustion engine from being “stalled” it has become known from the company brochure “Elektronisch geregelter Fahrantrieb für Gabelstapler” by Peter Dschida of Brueninghaus Hydromatik GmbH to take appropriate counter-measures for an electronically controlled travelling mechanism for fork-lift trucks. It is detected here that the internal combustion engine is incapable of achieving the target number of revolutions. As a consequence, the delivery volume of the hydraulic pump is reduced, which relieves the internal combustion engine. A hydraulic pump having a constant delivery volume for the lifting and other functions of the industrial truck frequently is connected, in addition to a geared pump, to the shaft of the internal combustion engine. The electronic control presets a larger number of revolutions for the internal combustion engine if lifting speeds are larger. However, to prevent the vehicle from getting accelerated the delivery volume of the hydraulic pump of the travelling mechanism is reduced accordingly.
- The electronic control which is known has the disadvantage that the number of revolutions of the internal combustion engine is dependent on the travelling speed. The measure which as is known makes it impossible for the internal combustion engine to get stalled is relatively sluggish and pressure-induced vibrations, a juddery motion of the vehicle, and a non-optimal utilization of the power potential of the internal combustion engine may readily occur. The inflexible delivery volume preset causes the vehicle to start up with a jerk and causes hydraulic vibrations if disturbing factors act on it.
- It is the object of the invention to provide an apparatus for controlling a drive system for an industrial truck which leads to minimum fuel consumption, only applies admissible torques to the internal combustion engine, and improves its drivability.
- The object is attained by the features of claim 1.
- The inventive apparatus uses a cascaded control. The cascade comprises an overlying speed control circuit and an underlying pressure control circuit. The pressure controller compares a transmission pressure measured to a preset pressure (a desired-pressure value) with the pressure controller speedily varying the hydraulic pump delivery volume so as to cause the control error to disappear. The overlying speed controller compares the travelling speed desired to the one measured, calculating a desired motive force therefrom. The motive force which is desired is converted, in a way which yet is to be described, into a required pumping pressure which is imposed onto the pressure controller as a desired-pressure value.
- A characteristic, which indicates an optimal-consumption speed for a given power, exists for each internal combustion engine. The driving power required may be calculated from the travelling speed and the motive force. This allows to preset a desired number of revolutions for an internal combustion engine from the characteristics stage in accordance with the characteristic chosen. This one will then be imposed onto a common speed controller for an internal combustion engine.
- Since the number of revolutions of the internal combustion engine is chosen according to the power requirement an optimal-consumption operation may be ensured. Pressure can be limited to the values admitted by the components at any point of operation. This makes it possible to prevent the engine from getting stalled and to set the limitation to a maximum value for the transmission pressure. In addition, the inventive apparatus improves the drivability and levels out vibrations caused by pressure. The latter are avoided by dimensioning the pressure controller in a proper way.
- If the internal combustion engine drives another hydraulic pump, e.g. for the lifting system, the number of revolutions of the internal combustion engine requires to be chosen higher to achieve a sufficient lifting speed. As a result, the number of revolutions ceases to be completely at the minimum of consumption. However, an increase in travelling speed does not take place because this does not influence the presetting effected for of the motive force and the hydraulic pressure. The pressure controller automatically reduces the delivery volume in order not to increase the pressure.
- In the inventive apparatus, the engine's characteristics are derived from the rpm-torque-efficiency characteristic diagram of the internal combustion engine. In an aspect of the invention, an rpm-torque-efficiency characteristic diagram for the pump is stored in the characteristics stage for being taken into account in determining the desired rpm value. Similarly, in another aspect of the invention, a travelling speed-torque-efficiency characteristic diagram for the hydraulic engine can be stored in the characteristics stage for being taken into account in determining the desired rpm value.
- A sensor may be disposed on the wheel or the hydraulic engine to determine the number of revolutions for the inventive apparatus and the speed transducer may determine the speed from the number of revolutions and the radius of the wheel. Alternatively, an rpm sensor may measure the number of revolutions of the internal combustion engine and calculate the speed therefrom and from the delivery volume of the pump (which corresponds to the transmission gear ratio) while taking into account the radius of the wheel.
- At least one pressure sensor may be provided, as a pressure transducer, at the outlet of the pump. In another aspect of the invention, the pump may have hydraulic variation inlets which are connected to the pressurized side of an auxiliary pressure source via a proportional valve each. The control input of the proportional valves is acted on by the desired value of the desired-value transducer.
- The characteristic which is employed may be different depending on the operating state of the inventive apparatus or internal combustion engine. Therefore, an aspect of the invention provides that the characteristics stage should have several sub-stages storing a characteristic each and a switch-over device is provided to change over to a sub-stage desired. The switch-over device may have a manually operable switch or may be actuated in dependence on the position of the accelerator or its speed of actuation.
- In an aspect of the invention, the number of revolutions of the internal combustion engine, the volume displaced by the hydraulic pump, and the number of revolutions of the driven wheel may be resorted to for a determination of the actual-pressure value in the hydrostatic transmission. Alternatively, the actual-pressure value may be determined from the torque of the internal combustion engine and the volume displaced by the hydraulic pump.
- Finally, the actual-pressure value may also be determined from the pressure in the servo-cylinder for adjusting the hydraulic pump and from the number of revolutions of the internal combustion engine. The way of determination may also be chosen different depending on the operating state which exists, e.g. depending on the number of revolutions.
- As was already explained previously the inventive apparatus permits to limit the pressure in the hydrostatic transmission, thus avoiding an overload of the internal combustion engine. For instance, this is necessary if the internal combustion engine runs up and a relatively high motive force has been required already. In this respect, an aspect of the invention provides that a controllable limitation stage is interposed between the desired-value transducer and the desired-value and actual-value comparator of the pressure control circuit, a second characteristics stage in which an rpm-torque characteristic of the internal combustion engine is stored and provides an output signal to the pressure relief stage, and the inlet is connected to an rpm transducer such that the pressure relief stage presets a pressure signal corresponding to the admissible torque according to a momental value of the characteristics stage and the level of the varying signal for the pump. The characteristic in the second characteristics stage may be obtained from a conversion of the characteristic(s) in the first characteristics stage and the corresponding hydraulic pressure and the motive force may be calculated via the actual delivery volume of the hydraulic pump in order to avoid stalling the internal combustion engine. The desired-value and actual-value transducer, for instance, determines the desired-pressure value for the pressure control circuit from the value desired for the motive force, the radius of the vehicle wheel, and the volume displaced by the hydraulic engine.
- It also was set forth previously that the internal combustion engine may drive a second pump having a constant or variable delivery volume for a hydraulic circuit, this having no adverse effect on the efficiency of the inventive apparatus.
- The invention will now be explained in more detail with reference to an embodiment shown in the drawings.
- FIG. 1 shows a circuit diagram for an apparatus according to the invention.
- FIG. 2 shows a circuit diagram for a hydraulic pressure control of the hydrostatic transmission of the apparatus of FIG. 1.
- FIG. 3 shows an alternative aspect of a hydraulic pressure control for the hydrostatic transmission of the apparatus of FIG. 1.
- FIG. 1 shows an
internal combustion engine 10 which drives ahydraulic pump 12 having a variable delivery volume. Thehydraulic pump 12 is suited for use with fourquadrant operation. Thehydraulic pump 12 feeds a fluid to a hydraulic engine which drives awheel 16 of an industrial truck 18 (not shown). Up to this point, it will be a drive of an industrial truck, which is known as such, by an internal combustion engine which has a hydrostatic transmission. - The drive system diagrammatically shown in FIG. 1 comprises an underlying
pressure control circuit 20 and an overlyingspeed control circuit 22. A desired-value and actual-value comparator 24 of thepressure control circuit 20 receives a desired value ΔpSoll from a desired-value transducer 39, and an actual value Pist. Pist corresponds to the differential pressure in the hydrostatic transmission and, for instance, may be determined by at least one pressure sensor or also by other parameters to be measured, e.g. from the number of revolutions of the internal combustion engine, the volume displaced by the hydraulic pump, and the number of revolutions of the wheel or from the number of revolutions of the internal combustion engine and the volume displaced by the hydraulic pump. Apressure controller 26 provides a corresponding signal φ to thepump 12. - A desired-value and actual-
value comparator 28 of thespeed control circuit 22 receives a desired value VSoll for the speed of theindustrial truck 18, e.g. from an accelerator. A actual-value transducer 30 for the speed is connected to an rpm transducer where the rpm transducer measures the number of revolutions nm at the outlet of the hydrostatic transmission or on thewheel 16 of theindustrial truck 18. The actual-value transducer 30 determines the actual speed via the radius rRad of thewheel 16. Aspeed controller 32 determines a desired-value signal FSoll for the motive force of the drive system. - A
first characteristics stage 34 has stored therein a characteristics field which indicates an optimal-consumption number of revolutions. Alternative characteristics can optimize the dynamic behaviour of theinternal combustion engine 10 or constitute a compromise. The characteristics stage 34 receives the signal FSoll and the signal VIst and determines the power required and determines the optimal number of revolutions from the corresponding characteristic and provides a desired rpm value nSoll to aspeed controller 36 of theinternal combustion engine 10. If theinternal combustion engine 10 drives another pump (not shown), e.g. for a hydraulic circuit of the industrial truck, a number of revolutions which is higher than the optimal number of revolutions will possibly be required to allow a faster response of the hydraulic circuit or to influence the speed of variation operations in the hydraulic circuit. To this end, an appropriate signal is provided to thestage 40 MAX via the active-function line 38, which increases the desired rpm value nSoll by a corresponding amount, but only up to a maximum value. - The desired value FSoll is converted to a desired-pressure value ΔpSoll in the desired-
value transducer 39, namely from the volume displaced by thehydraulic engine 14 and the radius of thewheel 16. - The active-action line for the desired-pressure value ΔpSoll is acted on by the
pressure relief stage 42, which limits the desired pressure to a maximum admissible value Δpzulässig. To this end, asecond characteristics stage 44 is provided in which an rpm-and-torque characteristic of theinternal combustion engine 10 is stored. The number of revolutions nv of the internal combustion engine is provided to thecharacteristics stage 44 and the maximum admissible momental value is determined therefrom in thecharacteristics stage 44. This value is converted into an admissible pressure in thepressure relief stage 42 according to the variation signal φ for the volume displaced by thepump 12. This way avoids overloading the internal combustion engine as a result of too high a power requirement. This way can also limit the pressure in the hydrostatic transmission to a maximum value. - FIG. 2 shows a hydraulic pressure control for the
pump 12 and theengine 14 of the hydraulic transmission of FIG. 1. The hydraulic pressure is applied to thevariation inlets pump 14 via anauxiliary pump 54. The auxiliary pump acts on the inlet of the slidingvalve 56 which haselectromagnetic control inputs value transducer 39 of FIG. 1. Furthermore, the slidingvalve 56 has two hydraulic control inputs which connect with the hydraulic circuit of the hydrostatic transmission and apply the differential pressure to the slidingvalve 56, which corresponds to the real-pressure value. - In the embodiment of FIG. 3, two
proportional valves spring 66 to the neutral position. For the rest, the way of action corresponds to the one which was described for FIG. 2. The two embodiments of FIGS. 2 and 3 provide apressure control valve 68 to keep the pressure constant in thepump 54. This pump may also be driven by the internal combustion engine.
Claims (14)
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE10037676A DE10037676C1 (en) | 2000-07-26 | 2000-07-26 | Device for controlling a drive system for an industrial truck |
DE10037676 | 2000-07-26 | ||
DE10037676.2 | 2000-07-26 |
Publications (2)
Publication Number | Publication Date |
---|---|
US20020026275A1 true US20020026275A1 (en) | 2002-02-28 |
US6427110B1 US6427110B1 (en) | 2002-07-30 |
Family
ID=7651088
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US09/916,070 Expired - Lifetime US6427110B1 (en) | 2000-07-26 | 2001-07-26 | Apparatus for controlling a drive system for an industrial truck |
Country Status (4)
Country | Link |
---|---|
US (1) | US6427110B1 (en) |
DE (1) | DE10037676C1 (en) |
FR (1) | FR2812249B1 (en) |
GB (1) | GB2366876B (en) |
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US20040249537A1 (en) * | 2001-10-30 | 2004-12-09 | Jurgen Legner | Machine tool and method for operating machine tool |
US20080202112A1 (en) * | 2007-02-28 | 2008-08-28 | Caterpillar Inc. | Method and system for feedback pressure control |
US20090112414A1 (en) * | 2007-10-31 | 2009-04-30 | Briton Todd Eastman | Work Machine With Torque Limiting Control For An Infinitely Variable Transmssion |
CN102029888A (en) * | 2010-11-26 | 2011-04-27 | 北京工业大学 | Power system for mechanical-electrical-liquid hybrid-driven vehicle and control method thereof |
EP2767739A1 (en) * | 2013-02-19 | 2014-08-20 | Dana Rexroth Transmission Systems S.r.l. | Power-split transmission for a vehicle propulsion system, method for controlling the transmission |
CN106394246A (en) * | 2016-11-02 | 2017-02-15 | 贵州詹阳动力重工有限公司 | Control system and control method for synchronization of hydraulic motors, as well as dual-vehicle-body all-terrain vehicle |
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DE10211799A1 (en) * | 2002-03-16 | 2003-10-02 | Deere & Co | Drive system of a work vehicle |
DE10259423A1 (en) * | 2002-12-19 | 2004-07-01 | Zf Friedrichshafen Ag | Method for controlling and / or regulating a cruise control device, in particular for tractors with a continuously variable transmission |
DE10315297A1 (en) * | 2003-04-04 | 2004-10-28 | Jungheinrich Ag | Brake system for a battery-powered industrial truck |
US7146263B2 (en) * | 2003-09-30 | 2006-12-05 | Caterpillar Inc | Predictive load management system |
DE602004032510D1 (en) * | 2004-02-06 | 2011-06-16 | Caterpillar Inc | Working machine with steering control |
DE102005038905A1 (en) | 2005-08-17 | 2007-02-22 | Brueninghaus Hydromatik Gmbh | Method for controlling a drive system and electronic control unit |
DE102006017792B4 (en) * | 2006-04-18 | 2020-04-23 | Robert Bosch Gmbh | Method and computer program for controlling a drive |
US7678015B2 (en) | 2006-04-28 | 2010-03-16 | Caterpillar Inc. | Efficiency based integrated power train control system |
DE102006029904A1 (en) * | 2006-06-29 | 2008-01-03 | Brueninghaus Hydromatik Gmbh | Method and control unit for a traction drive |
CN101689056B (en) * | 2007-05-31 | 2014-03-05 | 卡特彼勒公司 | Gen-set control system having proactive load relief |
WO2008147357A1 (en) * | 2007-05-31 | 2008-12-04 | Caterpillar Inc. | System and method for engine load management |
US8554428B2 (en) | 2007-09-28 | 2013-10-08 | Caterpillar Inc. | CVT control system having variable power source speed |
DE102007047724A1 (en) * | 2007-10-05 | 2009-04-09 | Robert Bosch Gmbh | Method and device for controlling a hydraulic unit |
DE102007058535A1 (en) * | 2007-12-06 | 2009-06-10 | Deere & Company, Moline | Drive system of a work vehicle |
DE102008025683B4 (en) * | 2007-12-28 | 2022-12-29 | Robert Bosch Gmbh | Procedure for controlling a travel drive |
DE102008011719A1 (en) * | 2008-02-28 | 2009-09-03 | Jungheinrich Aktiengesellschaft | Braking system for a truck |
EP3351447A1 (en) | 2017-01-18 | 2018-07-25 | Deere & Company | Control arrangement for an engine and a hydrostatic transmission of a vehicle |
DE102021210117A1 (en) | 2021-09-14 | 2023-03-16 | Robert Bosch Gesellschaft mit beschränkter Haftung | Method for a hydraulic drive, control unit, computer program and machine-readable storage medium |
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GB1525861A (en) * | 1975-10-23 | 1978-09-20 | Mullard Ltd | Vehicle power transmission arrangements and electronic control means therefor |
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DE2843256A1 (en) * | 1978-10-04 | 1980-04-17 | Bosch Gmbh Robert | DEVICE FOR REGULATING A MOTOR VEHICLE DRIVE UNIT |
WO1982001396A1 (en) * | 1980-10-09 | 1982-04-29 | Izumi Eiki | Method and apparatus for controlling a hydraulic power system |
NZ205140A (en) * | 1983-08-04 | 1987-02-20 | H M Reid | Electronically controlled dual fuel system for diesel engines |
US4534707A (en) * | 1984-05-14 | 1985-08-13 | Caterpillar Tractor Co. | Hydrostatic vehicle control |
JPH023547A (en) * | 1988-06-16 | 1990-01-09 | Mitsubishi Heavy Ind Ltd | Control device for self-feed type hydraulic machine |
US5214916A (en) * | 1992-01-13 | 1993-06-01 | Caterpillar Inc. | Control system for a hydraulic work vehicle |
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-
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- 2000-07-26 DE DE10037676A patent/DE10037676C1/en not_active Expired - Fee Related
-
2001
- 2001-07-17 FR FR0109514A patent/FR2812249B1/en not_active Expired - Fee Related
- 2001-07-24 GB GB0118018A patent/GB2366876B/en not_active Expired - Fee Related
- 2001-07-26 US US09/916,070 patent/US6427110B1/en not_active Expired - Lifetime
Cited By (11)
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US20040249537A1 (en) * | 2001-10-30 | 2004-12-09 | Jurgen Legner | Machine tool and method for operating machine tool |
US20080202112A1 (en) * | 2007-02-28 | 2008-08-28 | Caterpillar Inc. | Method and system for feedback pressure control |
WO2008105999A1 (en) * | 2007-02-28 | 2008-09-04 | Caterpillar Inc. | Method and system for feedback pressure control |
US7788917B2 (en) | 2007-02-28 | 2010-09-07 | Caterpillar Inc | Method and system for feedback pressure control |
US20090112414A1 (en) * | 2007-10-31 | 2009-04-30 | Briton Todd Eastman | Work Machine With Torque Limiting Control For An Infinitely Variable Transmssion |
EP2055545A2 (en) * | 2007-10-31 | 2009-05-06 | Deere & Company | Work Machine and Method |
EP2055545A3 (en) * | 2007-10-31 | 2010-09-08 | Deere & Company | Work Machine and Method |
CN102029888A (en) * | 2010-11-26 | 2011-04-27 | 北京工业大学 | Power system for mechanical-electrical-liquid hybrid-driven vehicle and control method thereof |
EP2767739A1 (en) * | 2013-02-19 | 2014-08-20 | Dana Rexroth Transmission Systems S.r.l. | Power-split transmission for a vehicle propulsion system, method for controlling the transmission |
US9243701B2 (en) | 2013-02-19 | 2016-01-26 | Dana Rexroth Transmission Systems | Power-split transmission for a traction drive and method for controlling the transmission |
CN106394246A (en) * | 2016-11-02 | 2017-02-15 | 贵州詹阳动力重工有限公司 | Control system and control method for synchronization of hydraulic motors, as well as dual-vehicle-body all-terrain vehicle |
Also Published As
Publication number | Publication date |
---|---|
GB2366876A (en) | 2002-03-20 |
GB2366876B (en) | 2004-09-08 |
GB0118018D0 (en) | 2001-09-19 |
FR2812249A1 (en) | 2002-02-01 |
DE10037676C1 (en) | 2002-05-23 |
FR2812249B1 (en) | 2006-02-24 |
US6427110B1 (en) | 2002-07-30 |
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