WO2018184663A1 - Procédé de commande d'un groupe motopropulseur - Google Patents

Procédé de commande d'un groupe motopropulseur Download PDF

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Publication number
WO2018184663A1
WO2018184663A1 PCT/EP2017/057968 EP2017057968W WO2018184663A1 WO 2018184663 A1 WO2018184663 A1 WO 2018184663A1 EP 2017057968 W EP2017057968 W EP 2017057968W WO 2018184663 A1 WO2018184663 A1 WO 2018184663A1
Authority
WO
WIPO (PCT)
Prior art keywords
engine speed
powertrain
output power
hydraulic flow
internal combustion
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/EP2017/057968
Other languages
English (en)
Inventor
Reno Filla
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Volvo Construction Equipment AB
Original Assignee
Volvo Construction Equipment AB
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Volvo Construction Equipment AB filed Critical Volvo Construction Equipment AB
Priority to PCT/EP2017/057968 priority Critical patent/WO2018184663A1/fr
Publication of WO2018184663A1 publication Critical patent/WO2018184663A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20—Drives; Control devices
    • E02F9/22—Hydraulic or pneumatic drives
    • E02F9/2278—Hydraulic circuits
    • E02F9/2296—Systems with a variable displacement pump
    • 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
    • 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
    • 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
    • B60W10/30—Conjoint control of vehicle sub-units of different type or different function including control of auxiliary equipment, e.g. air-conditioning compressors or oil pumps
    • 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
    • B60W30/18—Propelling the vehicle
    • B60W30/188—Controlling power parameters of the driveline, e.g. determining the required power
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20—Drives; Control devices
    • E02F9/2058—Electric or electro-mechanical or mechanical control devices of vehicle sub-units
    • E02F9/2062—Control of propulsion units
    • E02F9/2066—Control of propulsion units of the type combustion engines
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20—Drives; Control devices
    • E02F9/22—Hydraulic or pneumatic drives
    • E02F9/2221—Control of flow rate; Load sensing arrangements
    • E02F9/2232—Control of flow rate; Load sensing arrangements using one or more variable displacement pumps
    • E02F9/2235—Control of flow rate; Load sensing arrangements using one or more variable displacement pumps including an electronic controller
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20—Drives; Control devices
    • E02F9/22—Hydraulic or pneumatic drives
    • E02F9/2246—Control of prime movers, e.g. depending on the hydraulic load of work tools
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20—Drives; Control devices
    • E02F9/22—Hydraulic or pneumatic drives
    • E02F9/2253—Controlling the travelling speed of vehicles, e.g. adjusting travelling speed according to implement loads, control of hydrostatic transmission
    • 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
    • B60W2300/00—Indexing codes relating to the type of vehicle
    • B60W2300/17—Construction vehicles, e.g. graders, excavators

Definitions

  • the invention relates to a method for controlling a powertrain. Moreover, the present invention relates to a control unit for controlling a powertrain. Further, the present invention relates to a powertrain and/or a vehicle
  • the invention can in particular be applied in heavy-duty vehicles, such as trucks, buses and construction equipment.
  • heavy-duty vehicles such as trucks, buses and construction equipment.
  • the invention will be described with respect to a wheel loader, the invention is not restricted to this particular vehicle, but may also be used in other vehicles such as an articulated hauler or an excavator.
  • a powertrain comprising an internal combustion engine and a drivetrain may be adapted to produce a drivetrain output power, realized as rotational torque for a certain rotational speed.
  • a drivetrain for a vehicle such as a working machine, may be adapted to produce traction power in order to propel the vehicle by applying a traction force at a certain rotational speed.
  • the powertrain may further comprise a variable displacement hydraulic pump operably connected to the internal combustion engine and adapted to produce a hydraulic power, realized as a hydraulic flow with a certain hydraulic pressure.
  • variable displacement hydraulic pump of a working machine powertrain may be adapted to produce a hydraulic flow for steering the working machine and/or for operating an implement thereof.
  • the drivetrain output power and the hydraulic flow required at a certain time instant may require a specific power production by the internal combustion engine.
  • the internal combustion engine should preferably be controlled such that its produced power meets or exceeds the power being required for meeting the drivetrain output power and the hydraulic flow required.
  • the operating condition of the internal combustion engine may change significantly and rapidly. Such changes may have an influence on the fuel economy as well as the working life of the powertrain.
  • An object of the invention is to provide a method for controlling a powertrain comprising an internal combustion engine and a drivetrain, wherein the internal combustion engine is operated in an appropriate manner whilst still being able to produce power sufficient for meeting a drivetrain output power request as well as a hydraulic flow request.
  • the object is achieved by a method according to claim 1 .
  • the present invention relates to a method for controlling a powertrain comprising an internal combustion engine and a drivetrain.
  • the powertrain is adapted to produce drivetrain output power.
  • the powertrain further comprises a variable displacement hydraulic pump operably connected to the internal combustion engine and adapted to produce a hydraulic flow.
  • the method comprises:
  • the expression “drivetrain power” is intended to mean power being realized by the drivetrain as rotational torque at a certain rotational speed. Consequently, the expression “drivetrain output power request” is intended to mean a request for a certain drivetrain power obtained accordingly.
  • the method of the present invention proposes that the running internal combustion engine selectively operates at one of three predetermined engine speeds. This implies an appropriate fuel economy and/or appropriate operating conditions for the internal combustion engine since the internal combustion engine may be such that it has appropriate operating characteristics at the three predetermined engine speeds.
  • the sound of the engine may be perceived by the operator of the vehicle and the operator may be able to discern which one of the three discrete engine speeds that the internal combustion engine is operated at.
  • operating the internal combustion engine at one of the three predetermined speeds may provide appropriate feedback to the operator, for instance audio feed back from the sound of the engine indicative of a current load situation of the powertrain.
  • an available engine output power from the internal combustion engine is lowest for the first engine speed.
  • an absolute difference between the available engine output power for the second engine speed and the available engine output power for the third engine speed is less than 5% of the available engine output power for the second engine speed.
  • Having the difference between the output power for the second and the third engine speeds within the above range may enable configurations of the internal combustion engine for more efficient fuel combustions, leading to reduced fuel consumption and exhaust emissions of the engine.
  • the method comprises controlling the internal combustion engine such that the engine speed thereof assumes the lowest of the first, second and third engine speeds, by which speed it is possible to meet the drivetrain output power request as well as the hydraulic flow request.
  • the lowest engine speed is associated with the lowest fuel consumption.
  • a control towards the lowest engine speed implies a lowered fuel consumption.
  • the method comprises, upon detection that the hydraulic flow request implies a hydraulic flow exceeding the hydraulic flow obtainable when the internal combustion is running at the first engine speed, controlling the internal combustion engine such that the engine speed thereof assumes the third engine speed.
  • Going from the first engine speed directly to the third engine speed may be beneficial under certain circumstances. For instance, if the hydraulic flow request implies a high hydraulic flow (e.g. a hydraulic flow close to a maximum hydraulic flow obtainable), going directly from the first engine speed to the third engine speed may increase an operator's impression of the machine's responsiveness. Moreover, going directly from the first engine speed to the third engine speed may reduce the number of engine speed change occurrences which in turn implies advantageous energy efficiency.
  • a high hydraulic flow e.g. a hydraulic flow close to a maximum hydraulic flow obtainable
  • going directly from the first engine speed to the third engine speed may increase an operator's impression of the machine's responsiveness.
  • going directly from the first engine speed to the third engine speed may reduce the number of engine speed change occurrences which in turn implies advantageous energy efficiency.
  • the method may optionally comprise changing the engine speed from the third engine speed directly down to the first engine speed.
  • the method comprises controlling the internal combustion engine such that the engine speed is switched from a preceding engine speed to a different subsequent engine speed.
  • the method further comprises:
  • variable displacement hydraulic pump directly or indirectly controlling the displacement of the variable displacement hydraulic pump such that, when and while the engine speed changes to the subsequent engine speed, the variable displacement hydraulic pump produces a hydraulic flow rate change corresponding to the first hydraulic flow rate change.
  • the above features imply a smooth change from one engine speed to another of the three engine speeds. Moreover, the above features imply that a flow rate change is maintained during the engine speed change.
  • the method comprises controlling the internal combustion engine such that the engine speed is switched from a preceding engine speed to a different subsequent engine speed, the method further comprises: - determining a first hydraulic flow from the variable displacement hydraulic pump when the internal combustion engine is running at the preceding engine speed, and
  • variable displacement hydraulic pump directly or indirectly controlling the displacement of the variable displacement hydraulic pump such that, when and while the engine speed changes to the subsequent engine speed, the variable displacement hydraulic pump produces a hydraulic flow corresponding to the first hydraulic flow.
  • the above features imply a smooth change from one engine speed to another of the three engine speeds. Moreover, the above features imply that a hydraulic flow rate is maintained during the engine speed change.
  • the preceding engine speed is the third engine speed and the subsequent engine speed is the second engine speed.
  • the preceding engine speed is the first engine speed and the subsequent engine speed is the second engine speed.
  • the preceding engine speed is the second engine speed and the subsequent engine speed is the first engine speed.
  • the powertrain is a vehicle powertrain and the drivetrain output power is used as traction power.
  • the drivetrain output power request is a traction power request.
  • traction power may be realized as traction force at a certain vehicle speed.
  • the powertrain comprises an electric machine connected in series with the internal combustion engine.
  • the powertrain may be a hybrid powertrain featuring an electric series hybrid drivetrain.
  • the feature of determining a drivetrain output power request comprises predicting a future drivetrain output power requirement during a predetermined future time range. Such a prediction may further improve the operability of the powertrain since the prediction implies that engine speed changes need not necessarily be executed on a highly frequent basis.
  • the feature of predicting a future drivetrain output power requirement during a predetermined future time range comprises:
  • the feature of determining a hydraulic flow request comprises predicting a future hydraulic flow requirement during a predetermined future time range.
  • a prediction may further improve the operability of the powertrain since the prediction implies engine speed changes may be made on a less frequent basis.
  • the feature of predicting a future hydraulic flow requirement during a predetermined time range comprises:
  • the above feature of predicting a future hydraulic flow requirement implies that the future requirement may be determined with a relatively high degree of certainty.
  • the drivetrain output power requirement and/or the future hydraulic flow requirement may be determined at one or more discrete time instants within the future time range including the end of the future time range.
  • the one or more time instants may be evenly distributed over the future time range.
  • the maximum required drivetrain output power may be determined continuously over the future time range.
  • a second aspect of the present invention relates to a control unit for controlling a powertrain.
  • the powertrain comprises an internal combustion engine and a drivetrain.
  • the powertrain is adapted to produce drivetrain output power.
  • the powertrain further comprises a variable displacement hydraulic pump operably connected to the internal combustion engine and adapted to produce a hydraulic flow.
  • the control unit is adapted to:
  • control unit is adapted to perform a method for controlling a powertrain according to the first aspect of the present invention.
  • the powertrain comprises an electric machine connected in series with the internal combustion engine.
  • the powertrain may be a hybrid powertrain featuring an electric series hybrid drivetrain.
  • a third aspect of the present invention relates to a powertrain comprising an internal combustion engine and a drivetrain.
  • the powertrain is adapted to produce drivetrain output power.
  • the powertrain further comprises a variable displacement hydraulic pump operably connected to the internal combustion engine and adapted to produce a hydraulic flow.
  • the powertrain comprises a control unit according to the second aspect of the present invention.
  • the powertrain further comprises an electric machine connected in series with the internal combustion engine.
  • a fourth aspect of the present invention relates to a vehicle, preferably a working machine, comprising a control unit according to the second aspect of the present invention and/or a powertrain according to the third aspect of the present invention.
  • Fig. 1 is a side view of a wheel loader
  • Fig. 2 is a schematic view of a powertrain
  • Fig. 3 is a schematic view of another powertrain
  • Fig. 4 and 5 each show a graph illustrating the power producible by an internal combustion engine as a function of the engine speed
  • Fig. 6 is a flow chart of a method according to the present invention ;
  • Fig. 7 is a schematic top view illustrating a work cycle, and
  • Fig. 8 is a graph illustrating drivetrain output power and hydraulic flow required during the Fig. 7 work cycle.
  • Fig. 1 illustrates a vehicle exemplified as a wheel loader 10.
  • the body of the wheel loader 10 comprises a front body section 12 and a rear body section 14, which sections each has an axle 16, 18 for driving a pair of wheels 20, 22.
  • the body sections 12, 14 are connected to each other in such a way that they can pivot in relation to each other around a vertical axis by means of two first actuators in the form of hydraulic cylinders 24, 26 arranged between the two body sections 12, 14.
  • the hydraulic cylinders 24, 26 are thus arranged one on each side of a horizontal centreline of the wheel loader 10 in a vehicle traveling direction in order to turn the wheel loader 10.
  • a hydraulic motor may be used (not shown).
  • the wheel loader 10 comprises equipment 28 for handling objects or material.
  • the equipment 28 comprises a load-arm unit 30 and an implement 32, which in Fig. 1 is exemplified as a bucket, fitted on the load-arm unit 30.
  • a first end of the load-arm unit 30 is pivotally connected to the front vehicle section 12.
  • the implement 32 is pivotally connected to a second end of the load-arm unit 30.
  • the load-arm unit 30 can be raised and lowered relative to the front section 12 of the vehicle by means of two second actuators in the form of two hydraulic cylinders 34, 36, each one of which being connected at one end to the front vehicle section 12 and at the other end to the load-arm unit 30.
  • the implement 32 can be tilted relative to the load-arm unit 30 by means of a third actuator in the form of a hydraulic cylinder 38, which is connected at one end to the front vehicle section 12 and at the other end to the implement 32 via a link-arm system 40.
  • Fig. 2 illustrates an embodiment of a powertrain 42 according to the present invention.
  • the powertrain comprises an internal combustion engine 44 and a drivetrain 45.
  • the powertrain 42 is adapted to produce drivetrain output power.
  • the drivetrain output power is used as traction power.
  • the drivetrain 45 comprises axles 16, 18 each one driving a pair of wheels 20, 22.
  • the axles 16, 18 may be the axles presented hereinabove in relation to Fig. 1 .
  • the embodiments of the powertrain need not necessarily produce traction power for a vehicle.
  • embodiments of the powertrain are contemplated which produce drivetrain output power for another purpose.
  • embodiments of the powertrain may be adapted to be located in a factory (not shown) and may be adapted to produce drivetrain output power intended to be used by one or more machines (not shown) in the factory.
  • the Fig. 2 drivetrain 45 comprises a first electric machine 46, operably connected to the internal combustion engine 44.
  • the first electric machine 46 is mechanically connected to the internal combustion engine 44 by means of a first shaft 48.
  • the Fig. 2 drivetrain 45 comprises a second electric machine 50 electrically connected to the first electric machine 46.
  • the first and second electric machines 46, 50 are connected to one another via electric power conducting means 52 and form an electric drivetrain.
  • electric power conducting means 52 may comprise a cable (not shown).
  • the first and second electric machines 46, 50 are directly connected to one another.
  • embodiments of the power train may comprise energy storage means (not shown), such as a battery, electrically connected to one or both of the electric machines 46, 50.
  • the powertrain is a hybrid powertrain featuring an electric series hybrid drivetrain.
  • each one of the first and second electric machines 46, 50 may be adapted to function as an electric generator as well as an electric motor.
  • the second electric machine 50 is operatively connected to the axles 16, 18.
  • the second electric machine 50 is mechanically connected to a transmission arrangement 54 which in turn is connected to the axles 16, 18 via a drive shaft assembly 56.
  • such mechanical connection is obtained by virtue of a second shaft 58 mechanically connecting the second electric machine 50 to the transmission arrangement 54.
  • the drive shaft assembly 56 comprises a third shaft 60 mechanically connected to the transmission arrangement 54.
  • the transmission arrangement 54 may for instance be adapted to provide a fixed gear ratio between the second shaft 58 and the third shaft 60.
  • the transmission arrangement 54 may for instance be adapted to provide a variable gear ratio, e.g.
  • Fig. 2 illustrates that the powertrain 42 comprises a variable displacement hydraulic pump 62 operably connected to the internal combustion engine 44 and adapted to produce a hydraulic flow.
  • the powertrain 42 comprises a variable displacement hydraulic pump 62 operably connected to the internal combustion engine 44 and adapted to produce a hydraulic flow.
  • there is only one such variable displacement pump but it is easily conceivable to connect several such devices in order to increase the flow capacity and/or supply hydraulic flow to several hydraulic systems.
  • variable displacement hydraulic pump 62 is mechanically connected to the internal combustion engine 44 via a power take off unit for instance.
  • the powertrain may provide a fixed relation between the engine speed of the internal combustion engine 44 and the rotational speed at which the variable displacement hydraulic pump 62 rotates. It is conceivable that said power take off includes a clutch that can mechanically disengage pump 62 from engine 44 (not shown in Fig. 2).
  • variable displacement hydraulic pump 62 may be adapted to supply fluid to an actuator set 63 comprising at least one actuator.
  • the actuator set 63 may comprise one or more of the hydraulic cylinders 24, 26, 34, 36, 38 presented hereinabove with reference to the Fig. 1 working machine 10.
  • the powertrain 42 may comprise a pump actuator 64 adapted to control the displacement of the pump 62.
  • the powertrain 42 may comprise a control unit 66 for controlling the powertrain 42.
  • the control unit 66 may be in communication with the internal combustion engine 44 as well as the pump actuator 64.
  • the displacement of the pump 62 may be controlled by the pump actuator 64. However, it is also envisaged that the displacement may be controlled using other means. Purely by way of example, the displacement of the pump 62 may be controlled by reducing input signals from an operator or by limiting the pressure of a hydraulic signal to a displacement regulator (not shown) of the pump 62. Moreover, as indicated in Fig. 2, the control unit 66 may be in communication with request input means 68. Purely by way of example, the request input means 68 may comprise actuating means such as a lever, a knob, a button, a touch screen (not shown) or the like. 5 As a non-limiting example, an operator may employ the request input means 68 in order to transmit a drivetrain output power request and/or a hydraulic flow request to the control unit 66.
  • the control unit 66 may be in 10 communication with a sensor assembly 70 comprising one or more sensors.
  • the sensor assembly 70 may comprise a sensor adapted to determine the geographical position of the vehicle 10.
  • the sensor assembly 70 may comprise a global positioning system (not shown).
  • Fig. 3 illustrating a powertrain 42 comprising a drivetrain 45 in which each wheel 20, 22 is connected to an individual electric machine 50 via an individual transmission arrangement 54.
  • Each one of the Fig. 3 individual electric machine 20 50 is connected to the first electric machine 46, e.g. via a common electric power conducting means 52 or individual electric power conducting means 52.
  • embodiments of the powertrain 42 may comprise an individual electric machine 50 connected to each axle 16, 18 via an individual transmission arrangement 54.
  • Fig. 4 presents a curve 72 for the available engine output power P producible by an internal combustion engine as a function of the engine speed.
  • the internal combustion engine associated with the Fig. 4 graph may be the internal combustion engine illustrated in Fig. 2.
  • the internal combustion engine is associated with three predetermined engine speeds, wherein a first engine speed rii is lower than a second engine speed n 2 which in turn is lower than a third engine speed n 3 .
  • an available engine output power P from said internal combustion engine is lowest for the first engine speed rii .
  • an absolute difference between the available engine output power for the second engine speed n 2 and the available engine output power for the third engine speed n 3 is less than 5%, alternatively less than 2%, of the available engine output power for the second engine speed n 2 .
  • the available engine output power for the second engine speed n 2 is comparable to the available engine output power for the third engine speed n 3 .
  • the available engine output power for the second engine speed n 2 is greater than the available engine output power for the third engine speed n 3 .
  • the available engine output power for the third engine speed n 3 is greater than the available engine output power for the second engine speed n 2 .
  • Fig. 5 illustrating such a scenario.
  • Each one of Fig. 4 and 5 further presents a curve 74 showing that the available hydraulic flow Q from the variable displacement hydraulic pump 62 operably connected to the internal combustion engine is dependent on the engine speed when the displacement of said pump is constant (i.e. fixed).
  • the maximum available hydraulic flow increases with increasing engine speed.
  • the maximum available hydraulic flow for the third engine speed n 3 is greater than the maximum available hydraulic flow for the second engine speed n 2 which in turn is greater than the maximum available hydraulic flow for the first engine speed n,.
  • the hydraulic flow fed from the variable displacement hydraulic pump can be varied from a minimum flow to a first maximum flow Qmax,i -
  • the range of flows obtainable at the first engine speed rii is indicated by the solid line extending from zero flow to Q ma x, i in Fig. 4.
  • the range of flows obtainable at the first engine speed n-i may extend from a non-zero minimum flow to the first maximum flow Q max, i . Irrespective of the end points of the range of flows associated with the first engine speed rii , by controlling the displacement of the variable displacement hydraulic pump, a flow within the range may be produced by the variable displacement hydraulic pump 62.
  • the hydraulic flow fed from the variable displacement hydraulic pump can be varied from a minimum flow, e.g. a zero flow, to a second maximum flow Q max,2 -
  • the second maximum flow Q max,2 is greater than the first maximum flow Q max, i .
  • the hydraulic flow fed from the variable displacement hydraulic pump can be varied from a minimum flow, e.g. a zero flow, to a third maximum flow Q max,3 .
  • the third maximum flow Q max,3 is greater than the second maximum flow Q max,2 .
  • Fig. 6 illustrates a flow chart of a method according to the present invention.
  • the method may be carried out by a control unit 66 communicating with each one of the internal combustion engine 44 and the variable displacement hydraulic pump 62.
  • the method is for controlling a powertrain 42 comprising an internal combustion engine 44 and a drivetrain 45.
  • the powertrain 42 is adapted to produce drivetrain output power.
  • the powertrain 42 further comprises a variable displacement hydraulic pump 62 operably connected to the internal combustion engine 44 and adapted to produce a hydraulic flow.
  • the method according to the present invention comprises:
  • predetermined engine speeds n 1 ; n 2 , n 3 wherein a first engine speed n-, is lower than a second engine speed n 2 , which in turn is lower than a third engine speed n 3 .
  • the feature S14 may be implemented such that the internal combustion engine is controlled such that the running internal combustion engine always operates at one of three predetermined engine speeds rii , n 2 , n 3 .
  • the feature S10 of determining a drivetrain output power request and the feature S12 of determining a hydraulic flow request presented in sequence in the Fig. 6. However, it should be noted that embodiments of the method are contemplated in which the features S10, S12 are performed simultaneously and/or in which the feature S12 is carried out before feature S10.
  • the features S10, S12 may for instance comprise determining a current drivetrain output power request and/or a current hydraulic flow request.
  • a current drivetrain output power request and/or a current hydraulic flow request may be determined by receiving information from an operator, for instance via the request input means 68 presented hereinabove in relation to Fig. 2.
  • the features S10, S12 may for instance comprise predicting a future drivetrain output power requirement and/or a future hydraulic flow requirement during a predetermined future time range.
  • a future drivetrain output power requirement and/or a future hydraulic flow requirement may be determined by a control unit 66, for instance using information received from a sensor assembly 70 in communication with the control unit 66, see e.g. Fig. 2.
  • the engine speed may be controlled by controlling the fluid supply to the internal combustion engine 44.
  • the method may comprise controlling the internal combustion engine 44 such that the engine speed thereof assumes the lowest of the first, second and third engine speeds n 1 ; n 2 , n 3 , by which it is possible to meet the drivetrain output power request as well as the hydraulic flow request.
  • the method need not necessarily control the engine speed such that the engine speed is changed to an adjacent engine speed.
  • the embodiments of the method may comprise, upon detection that the hydraulic flow request implies a hydraulic flow exceeds the hydraulic flow obtainable when the internal combustion is running at the first engine speed r controlling the internal combustion engine such that the engine speed thereof assumes the third engine speed n 3 .
  • the displacement of the variable displacement hydraulic pump 62 may also be controlled in order to obtain a smooth change in the flow produced by the pump 62 during the transition between the engine speeds.
  • the displacement of the variable displacement hydraulic pump 62 may be controlled such that a hydraulic flow rate change (i.e. a decrease or an increase Q ' in the flow fed by the pump 62) present when the internal combustion engine is operated at the preceding engine speed is substantially maintained when the engine speed has been changed to the subsequent engine speed.
  • variable displacement hydraulic pump 62 is controlled so as to have a certain pump displacement change for a preceding engine speed and the engine speed is changed to a subsequent engine speed whilst the certain pump displacement change is maintained, a significant alteration of the hydraulic flow rate change may occur which may be undesired since such an alteration may affect the behaviour of components fed by the hydraulic flow. For instance, if an operator intends to perform an operation requiring a constant hydraulic flow rate change, such as raising the implement 32 at a relatively constant acceleration, it may be desired if the hydraulic flow rate change remains relatively constant even when the engine speed is changed. Any significant alteration of the hydraulic flow rate change may results in undesired jerks in the implement 32.
  • an embodiment of the method may comprise:
  • the method embodiment may comprise detecting that a first hydraulic flow rate change is requested by an operator and the method embodiment may also comprise determining that the flow rate change should be maintained as the engine speed changes.
  • an operator may request that that the flow rate change should be maintained over engine speed changes.
  • such a request may be entered as a general powertrain setting or alternatively as a setting associated with a specific operation of the powertrain.
  • the method embodiment further comprises directly or indirectly
  • variable displacement hydraulic pump 62 controlling the displacement of the variable displacement hydraulic pump 62 such that, when and while the engine speed changes to the subsequent engine speed, the variable displacement hydraulic pump produces a hydraulic flow rate change corresponding to the first hydraulic flow rate change Q As such, the flow rate change, which may be needed in order to perform a desired operation, is maintained as the engine speed changes.
  • the displacement of the variable displacement hydraulic pump 62 may be controlled such that a hydraulic flow present when the internal combustion engine is operated at the preceding engine speed is substantially maintained when the engine speed has been changed to the subsequent engine speed.
  • the method may comprise:
  • the method embodiment further comprises directly or indirectly
  • variable displacement hydraulic pump 62 controlling the displacement of the variable displacement hydraulic pump 62 such that, when and while the engine speed changes to the subsequent engine speed, the variable displacement hydraulic pump 62 produces a hydraulic flow
  • the preceding engine speed is the third engine speed n 3 and the subsequent engine speed is the second engine speed n 2 .
  • the preceding engine speed is the first engine speed ni and the subsequent engine speed is the second engine speed n 2 .
  • the preceding engine speed is the second engine speed n 2 and the subsequent engine speed is the first engine speed rii .
  • the drivetrain output power request and/or the hydraulic flow request may be a current drivetrain output power request and/or a current hydraulic flow request.
  • the feature of determining a drivetrain output power request and/or the hydraulic flow request comprises predicting a future drivetrain output power requirement and/or a future hydraulic flow requirement during a predetermined future time range.
  • a work cycle in the form of so-called short-cycle loading for a wheel loader 10, such as the wheel loader illustrated in Fig. 1 is shown.
  • the short-cycle loading is characterized in that the longest distance that the vehicle travels between a loading and an unloading position does not exceed a certain number of metres, for example in the order of 20 metres (depending on the workplace and the wheel loader size).
  • the wheel loader 10 is in Fig. 7 used to scoop up material from a loading position (excavating a natural ground 76) with the implement 32 - which implement in Fig. 7 is exemplified as a bucket - and unload it in the unloading position (onto a container of a dump truck 78 in the form of an articulated hauler).
  • FIG. 7 shows a driving pattern comprising a series of steps from excavation to loading onto the dump truck 78.
  • Fig. 8 illustrates the required drivetrain output power P R as well as the required hydraulic flow Q R during each one of the Fig. 7 steps.
  • the wheel loader 10 travels forward in a first step, indicated by arrow 80, to the natural ground 76.
  • the wheel loader 10 may as a non-limiting example be operated in a forward second speed gear during the first step.
  • the Fig. 7 driving pattern can be performed by a wheel loader 10 comprising a stepless transmission arrangement.
  • the wheel loader is in a straight position, wherein the front and rear vehicle parts are in line.
  • the first step 80 is associated with a relatively low required drivetrain output power as well as a relatively low required hydraulic flow.
  • the wheel loader 10 When the wheel loader 10 approaches the natural ground 76, in a second step, it thrusts into the natural ground in for example a forward first speed gear in order to increase tractive force, see arrow 82.
  • the lifting arm unit 30 is raised, wherein the bucket 30 is filled with material from the natural ground.
  • the second step is consequently associated with relatively a relatively large required drivetrain output power as well as a relatively large required hydraulic flow.
  • the wheel loader 10 is in a third step retreated from the excavating operation position at a high speed in for example a reverse second speed gear, see arrow 84, which may require a relatively large required drivetrain output power.
  • the wheel loader is thereafter turned to the right (or to the left) in a fourth step, see arrow 86 which turning operation may require a required hydraulic flow increase.
  • the wheel loader 10 then moves forward in a fifth step, see arrow 88, while turning hard to the left (or right), then straightens out the vehicle to travel to approach the dump truck 78 at a high speed (indicating an increase in required drivetrain output power) in a sixth step, see arrow 90.
  • the lifting arm unit 30 is raised, thus requiring a relatively large required hydraulic flow, the bucket 32 tilted and the material is deposited in the load receiver 78.
  • the wheel loader 10 moves away in reverse from the dump truck 78 at a high speed in a seventh step, see arrow 92, turns to a stop position and is driven forwards again, see arrow 94, towards the natural ground 76 in a first step of a new work cycle round.
  • the steps 80 and 94 coincide.
  • each one of the steps is associated with a specific required drivetrain output power as well as a specific required hydraulic flow.
  • the powertrain 42 forming part of the Fig. 7 wheel loader 10
  • the powertrain 42 is in the third step, indicated by reference numeral 84.
  • the determination that that the powertrain 42 is operated in a repeated work cycle may be based on a conclusion that the required drivetrain output power levels and/or the required hydraulic flow levels are repeated on a regular basis. In other words, upon detection of recurrent required drivetrain output power levels and/or required hydraulic flow levels, it may be determined that the powertrain 42 is operated in repeated work cycle. Instead of, or in addition to, basing the repeated work cycle determination on the required levels, if the powertrain is a vehicle powertrain, a determination that the powertrain 42 is operated in a repeated work cycle may be based on a conclusion that the vehicle is travelling along a recurrent travel path.
  • the determination of which portion of the repeated work cycle that the powertrain 42 currently is operated in may be determined by comparing the present required drivetrain output power and/or the present required hydraulic flow to the required levels detected for the work cycle to thereby determine which portion of the repeated work cycle having required levels corresponding to the present required drivetrain output power and/or the present required hydraulic flow.
  • the determination of which portion of the repeated work cycle that the powertrain 42 currently is operated in may be based on a determination of the current position of the vehicle and comparing that position to the positions along the recurrent travel path of the work cycle.
  • the future drivetrain output power requirement as well as the future hydraulic flow requirement may be predicted.
  • the future requirements may for instance be determined from the start T 0 to the end ⁇ of the future time range ⁇ .
  • the future drivetrain output power requirement may be set to correspond to the maximum required drivetrain output power during the future time range ⁇ .
  • the future hydraulic flow requirement may be set to correspond to the maximum required hydraulic flow during the future time range ⁇ .
  • the maximum required drivetrain output power may be determined for one or more discrete time instants within the future time range ⁇ including the end ⁇ of the future time range ⁇ .
  • the one or more discrete time instants may be evenly distributed over the future time range ⁇ . It is also envisaged that the maximum required drivetrain output power may be determined continuously over the future time range ⁇ .
  • the drivetrain output power request may be set using the future drivetrain output power requirement (for instance by setting the drivetrain output power request equal to the future drivetrain output power requirement) and the hydraulic flow request may be set using the future hydraulic flow requirement (for instance by setting the hydraulic flow request equal to the future hydraulic flow requirement).
  • the actual hydraulic flow fed by the variable displacement hydraulic pump 62 throughout the future time range ⁇ may then be controlled by controlling the pump's displacement.
  • the future hydraulic flow requirement may be indicative of the maximum flow required during the future time range ⁇ and the internal combustion engine may be controlled so as to assume the engine speed n 1 ; n 2 , n 3 for which the maximum required flow, in combination with the drivetrain output power request, can be met.
  • the above example with reference to Fig. 7 and Fig. 8 determines the drivetrain output power request as well as the hydraulic flow request by predicting future
  • embodiments of the present method may determine only one of the requests by predicting future requirements and for example determining the other request using input from an operator.
  • the requests may be used for controlling a powertrain according to the method of the present invention, viz by controlling the internal combustion engine so as to assume one of the three engine speeds n 1 ; n 2 , n 3 .

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  • Engineering & Computer Science (AREA)
  • Mining & Mineral Resources (AREA)
  • Combustion & Propulsion (AREA)
  • Chemical & Material Sciences (AREA)
  • Structural Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Civil Engineering (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
  • Fluid Mechanics (AREA)
  • Physics & Mathematics (AREA)
  • Automation & Control Theory (AREA)
  • Operation Control Of Excavators (AREA)

Abstract

La présente invention concerne un procédé de commande d'un groupe motopropulseur (42) comprenant un moteur à combustion interne (44) et une transmission (45), ledit groupe motopropulseur (42) étant conçu pour produire une puissance de sortie de transmission, ledit groupe motopropulseur (42) comprenant en outre une pompe hydraulique à cylindrée variable (62) fonctionnellement raccordée audit moteur à combustion interne (44) et conçue pour produire un flux hydraulique, ledit procédé comprenant : - la détermination d'une requête de puissance de sortie de transmission ; - la détermination d'une requête de flux hydraulique, et - sur la base de ladite requête de puissance de sortie de transmission et de ladite requête de flux hydraulique, la commande automatique dudit moteur à combustion interne (44) de sorte que le moteur à combustion interne en fonctionnement (44) fonctionne à une vitesse parmi trois vitesses de moteur prédéterminées (n1 ; n2, n3), une première vitesse de moteur (n1) étant inférieure à une deuxième vitesse de moteur (n2) qui est à son tour inférieure à une troisième vitesse de moteur (n3).
PCT/EP2017/057968 2017-04-04 2017-04-04 Procédé de commande d'un groupe motopropulseur Ceased WO2018184663A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/EP2017/057968 WO2018184663A1 (fr) 2017-04-04 2017-04-04 Procédé de commande d'un groupe motopropulseur

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/EP2017/057968 WO2018184663A1 (fr) 2017-04-04 2017-04-04 Procédé de commande d'un groupe motopropulseur

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WO2018184663A1 true WO2018184663A1 (fr) 2018-10-11

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1830053A1 (fr) * 2004-12-13 2007-09-05 Hitachi Construction Machinery Co., Ltd. Dispositif de commande pour un vehicule mobile en fonctionnement
WO2008100185A1 (fr) * 2007-02-13 2008-08-21 Volvo Construction Equipment Ab Procede et systeme permettant de reguler une puissance d'entree
EP2982849A1 (fr) * 2014-01-29 2016-02-10 Komatsu Ltd. Engin de chantier et son procédé de commande

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1830053A1 (fr) * 2004-12-13 2007-09-05 Hitachi Construction Machinery Co., Ltd. Dispositif de commande pour un vehicule mobile en fonctionnement
WO2008100185A1 (fr) * 2007-02-13 2008-08-21 Volvo Construction Equipment Ab Procede et systeme permettant de reguler une puissance d'entree
EP2982849A1 (fr) * 2014-01-29 2016-02-10 Komatsu Ltd. Engin de chantier et son procédé de commande

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