Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60K—ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
  • B60K6/00—Arrangement or mounting of plural diverse prime-movers for mutual or common propulsion, e.g. hybrid propulsion systems comprising electric motors and internal combustion engines ; Control systems therefor, i.e. systems controlling two or more prime movers, or controlling one of these prime movers and any of the transmission, drive or drive units Informative references: mechanical gearings with secondary electric drive F16H3/72; arrangements for handling mechanical energy structurally associated with the dynamo-electric machine H02K7/00; machines comprising structurally interrelated motor and generator parts H02K51/00; dynamo-electric machines not otherwise provided for in H02K see H02K99/00
  • B60K6/20—Arrangement or mounting of plural diverse prime-movers for mutual or common propulsion, e.g. hybrid propulsion systems comprising electric motors and internal combustion engines ; Control systems therefor, i.e. systems controlling two or more prime movers, or controlling one of these prime movers and any of the transmission, drive or drive units Informative references: mechanical gearings with secondary electric drive F16H3/72; arrangements for handling mechanical energy structurally associated with the dynamo-electric machine H02K7/00; machines comprising structurally interrelated motor and generator parts H02K51/00; dynamo-electric machines not otherwise provided for in H02K see H02K99/00 the prime-movers consisting of electric motors and internal combustion engines, e.g. HEVs
  • B60K6/42—Arrangement or mounting of plural diverse prime-movers for mutual or common propulsion, e.g. hybrid propulsion systems comprising electric motors and internal combustion engines ; Control systems therefor, i.e. systems controlling two or more prime movers, or controlling one of these prime movers and any of the transmission, drive or drive units Informative references: mechanical gearings with secondary electric drive F16H3/72; arrangements for handling mechanical energy structurally associated with the dynamo-electric machine H02K7/00; machines comprising structurally interrelated motor and generator parts H02K51/00; dynamo-electric machines not otherwise provided for in H02K see H02K99/00 the prime-movers consisting of electric motors and internal combustion engines, e.g. HEVs characterised by the architecture of the hybrid electric vehicle
  • B60K6/48—Parallel type
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60K—ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
  • B60K6/00—Arrangement or mounting of plural diverse prime-movers for mutual or common propulsion, e.g. hybrid propulsion systems comprising electric motors and internal combustion engines ; Control systems therefor, i.e. systems controlling two or more prime movers, or controlling one of these prime movers and any of the transmission, drive or drive units Informative references: mechanical gearings with secondary electric drive F16H3/72; arrangements for handling mechanical energy structurally associated with the dynamo-electric machine H02K7/00; machines comprising structurally interrelated motor and generator parts H02K51/00; dynamo-electric machines not otherwise provided for in H02K see H02K99/00
  • B60K6/20—Arrangement or mounting of plural diverse prime-movers for mutual or common propulsion, e.g. hybrid propulsion systems comprising electric motors and internal combustion engines ; Control systems therefor, i.e. systems controlling two or more prime movers, or controlling one of these prime movers and any of the transmission, drive or drive units Informative references: mechanical gearings with secondary electric drive F16H3/72; arrangements for handling mechanical energy structurally associated with the dynamo-electric machine H02K7/00; machines comprising structurally interrelated motor and generator parts H02K51/00; dynamo-electric machines not otherwise provided for in H02K see H02K99/00 the prime-movers consisting of electric motors and internal combustion engines, e.g. HEVs
  • B60K6/50—Architecture of the driveline characterised by arrangement or kind of transmission units
  • B60K6/54—Transmission for changing ratio
  • B60K6/543—Transmission for changing ratio the transmission being a continuously variable transmission
• • 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
  • F16H57/00—General details of gearing
  • F16H57/04—Features relating to lubrication or cooling or heating
  • F16H57/0434—Features relating to lubrication or cooling or heating relating to lubrication supply, e.g. pumps ; Pressure control
  • F16H57/0435—Pressure control for supplying lubricant; Circuits or valves therefor
• • 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
  • F16H57/00—General details of gearing
  • F16H57/04—Features relating to lubrication or cooling or heating
  • F16H57/0434—Features relating to lubrication or cooling or heating relating to lubrication supply, e.g. pumps ; Pressure control
  • F16H57/0441—Arrangements of pumps
• • 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
  • F16H57/00—General details of gearing
  • F16H57/04—Features relating to lubrication or cooling or heating
  • F16H57/048—Type of gearings to be lubricated, cooled or heated
  • F16H57/0487—Friction gearings
  • F16H57/0489—Friction gearings with endless flexible members, e.g. belt CVTs
• • 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
  • F16H61/0021—Generation or control of line pressure
  • F16H61/0025—Supply of control fluid; Pumps therefore
• • 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
  • F16H61/0021—Generation or control of line pressure
  • F16H61/0025—Supply of control fluid; Pumps therefore
  • F16H61/0031—Supply of control fluid; Pumps therefore using auxiliary pumps, e.g. pump driven by a different power source than the engine
• • 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
  • F16H61/66—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 specially adapted for continuously variable gearings
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60K—ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
  • B60K6/00—Arrangement or mounting of plural diverse prime-movers for mutual or common propulsion, e.g. hybrid propulsion systems comprising electric motors and internal combustion engines ; Control systems therefor, i.e. systems controlling two or more prime movers, or controlling one of these prime movers and any of the transmission, drive or drive units Informative references: mechanical gearings with secondary electric drive F16H3/72; arrangements for handling mechanical energy structurally associated with the dynamo-electric machine H02K7/00; machines comprising structurally interrelated motor and generator parts H02K51/00; dynamo-electric machines not otherwise provided for in H02K see H02K99/00
  • B60K6/20—Arrangement or mounting of plural diverse prime-movers for mutual or common propulsion, e.g. hybrid propulsion systems comprising electric motors and internal combustion engines ; Control systems therefor, i.e. systems controlling two or more prime movers, or controlling one of these prime movers and any of the transmission, drive or drive units Informative references: mechanical gearings with secondary electric drive F16H3/72; arrangements for handling mechanical energy structurally associated with the dynamo-electric machine H02K7/00; machines comprising structurally interrelated motor and generator parts H02K51/00; dynamo-electric machines not otherwise provided for in H02K see H02K99/00 the prime-movers consisting of electric motors and internal combustion engines, e.g. HEVs
  • B60K6/42—Arrangement or mounting of plural diverse prime-movers for mutual or common propulsion, e.g. hybrid propulsion systems comprising electric motors and internal combustion engines ; Control systems therefor, i.e. systems controlling two or more prime movers, or controlling one of these prime movers and any of the transmission, drive or drive units Informative references: mechanical gearings with secondary electric drive F16H3/72; arrangements for handling mechanical energy structurally associated with the dynamo-electric machine H02K7/00; machines comprising structurally interrelated motor and generator parts H02K51/00; dynamo-electric machines not otherwise provided for in H02K see H02K99/00 the prime-movers consisting of electric motors and internal combustion engines, e.g. HEVs characterised by the architecture of the hybrid electric vehicle
  • B60K6/48—Parallel type
  • B60K2006/4808—Electric machine connected or connectable to gearbox output shaft
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60Y—INDEXING SCHEME RELATING TO ASPECTS CROSS-CUTTING VEHICLE TECHNOLOGY
  • B60Y2200/00—Type of vehicle
  • B60Y2200/90—Vehicles comprising electric prime movers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60Y—INDEXING SCHEME RELATING TO ASPECTS CROSS-CUTTING VEHICLE TECHNOLOGY
  • B60Y2200/00—Type of vehicle
  • B60Y2200/90—Vehicles comprising electric prime movers
  • B60Y2200/91—Electric vehicles
• • 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
  • F16H2061/0015—Transmission control for optimising fuel consumptions
• • 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
  • F16H61/0021—Generation or control of line pressure
  • F16H2061/0037—Generation or control of line pressure characterised by controlled fluid supply to lubrication circuits of the gearing
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
  • Y02T10/00—Road transport of goods or passengers
  • Y02T10/60—Other road transportation technologies with climate change mitigation effect
  • Y02T10/62—Hybrid vehicles

Definitions

• the present invention relates to a powertrain for or in an electric vehicle, in particular a passenger car, with an electric machine (EM), also known as a motor/generator device, a driven wheel or wheels and with a continuously variable transmission (CVT) that drivingly connects, i.e. rotationally couples, the EM to the driven wheel.
• EM electric machine
• CVT continuously variable transmission
• the term electric vehicle is to be understood as including only purely electric vehicles, such as battery electric vehicles (BEV) and fuel cell electric vehicles (FCEV).
• BEV battery electric vehicles
• FCEV fuel cell electric vehicles
• the presently considered electric vehicle powertrain includes only the electric machine as a prime mover and does, in particular, not include an internal combustion engine that is, or at least can be, connected to the driven wheels in addition to or instead of the electric machine.
• the CVT is mostly known from its widespread application in conventional motor vehicles that are powered by an internal combustion engine, but it can be beneficially applied in electric vehicles as well.
• the known CVT includes a primary pulley and a secondary pulley, as well as a flexible drive element that is wrapped around and in friction contact with the said pulleys.
• Each such pulley comprises two (frusto-)conical pulley discs arranged on a shaft, whereof at least one pulley disc is axially moveable and can be urged towards the pulley disc by an actuation system of the CVT, such as a set of electronically controlled and hydraulically operated piston/cylinder assemblies.
• the flexible drive element comes in several types such as a metal push belt, a metal drive chain or a fibre- reinforced rubber pull belt.
• the flexible drive element is clamped between the two pulley discs of each pulley by the said actuation system exerting a respective force on the moveable pulley disc towards the other one of the two pulley discs.
• a rotational speed and an accompanying torque can then be transmitted between the pulleys by means of friction between the flexible drive element and the pulleys.
• a radius of curvature of the flexible drive element at each pulley is controlled.
• these radii of curvature determine a speed ratio of the CVT, which speed ratio can be controlled by the actuation system to an arbitrary value within a speed ratio range provided by the CVT.
• the CVT thus allows the engine to be operated within a continuous range of rotational speeds -as determined by the speed ratio range of the CVT- in relation to a given vehicle speed, i.e. a given rotation speed of the driven wheel.
• the engine speed can for example controlled towards optimum fuel efficiency of the engine (typically a low engine speed), towards maximum vehicle acceleration (typically a high engine speed) or even towards emulating a geared, i.e. stepped transmission.
• a desired engine speed is typically determined based on several operating parameters including, at least, the current vehicle speed and an efficiency characteristic of the engine.
• the CVT speed ratio is then controlled such that the actual engine speed matches the desired engine speed as closely as possible.
• the accelerator pedal position is often interpreted as an acceleration that is instantaneously demanded by the driver (that can be zero).
• the engine fuel efficiency characteristic is in the form of a look up table that links the desired engine speed to the engine torque required for realising the demanded acceleration.
• the former, conventional engine speed control method can be easily converted to a vehicle that is powered by an EM, by replacing the engine fuel efficiency characteristic by a similar efficiency characteristic of the EM.
• the said look-up table links a desired EM speed (providing optimum EM electrical efficiency) to a vehicle speed.
• a significant efficiency improvement can in this case be realized.
• the present invention considers that the electrical efficiency of the EM is much higher than the fuel efficiency of the internal combustion engine, to such an extent even that the (mechanical and/or electrical) power efficiency of other components of the powertrain become a significant factor in the overall power efficiency of the powertrain.
• the combined power efficiencies of the EM and the CVT is favourably taken into account when determining a desired EM speed.
• an efficiency characteristic in particular a power efficiency characteristic, is predetermined for the combination of EM and CVT that is applied in the powertrain.
• the mechanical efficiency of a gear train that is applied in the powertrain between the EM and the CVT is also taken into account in the combined efficiency characteristic as well.
• the mechanical efficiency of any gears between the CVT and the driven wheels can be favourably disregarded.
• the electrical efficiency of a so-called inverter between the EM and a battery of the electric vehicle can be taken into account in the combined efficiency characteristic as well.
• the combined efficiency characteristic it is noted that it can be conveniently determined by mutually multiplying the individual efficiency maps of the powertrain components, such as at least the EM and the CVT, that map the power efficiency of the respective powertrain component against the operating parameters of torque or power, whether generated or transmitted by the respective powertrain component, and output speed of that respective powertrain component.
• the combined efficiency characteristic ultimately links any vehicle speed and EM power to a desired speed ratio for the CVT for providing maximum powertrain efficiency.
• the above, novel control method is preferably also applied during vehicle deceleration, i.e. for torque or power levels that are lower than what is required for constant vehicle speed.
• vehicle deceleration i.e. for torque or power levels that are lower than what is required for constant vehicle speed.
• the EM applies a negative torque and operates as a generator, e.g. to (re-)charge the battery of the electric vehicle (i.e. so-called regenerative braking).
• regenerative braking so-called regenerative braking
• most efficient operating points are available for the powertrain as a whole as a function of the instantaneous (reverse, i.e. braking) torque or power and (forward) speed of the electric vehicle.
• the present invention relies on a predetermined efficiency map that links the input parameters of the speed and torque at the drive wheels (or parameters representative thereof, such as vehicle speed and EM power respectively) to the CVT speed ratio and thus to the EM speed that provides such wheel torque at the highest power efficiency.
• the said predetermined efficiency map is prepared by measurement, or more conveniently by calculating the power loss in the system of, at least, the EM and the CVT, as a function of CVT speed ratio, EM power and vehicle speed.
• a further efficiency improvement can be realized in accordance with the present invention, by designing a component of the powertrain with an efficiency map that approaches the efficiency map of another component thereof, such that the said multiplying of the individual efficiency maps will yield the highest values. Additionally, these individual and combined efficiency maps preferably approach the most commonly occurring operating points of the electric vehicle, in particular the operating points corresponding to constant vehicle speed on a level road.
• the EM is provided with an individual efficiency characteristic in terms of combinations of EM torque and EM speed providing minimal power consumption, which characteristic is intersected by a steady state torque requirement curve when the CVT is in, so-called, Overdrive (i.e. the most accelerating CVT speed ratio).
• Overdrive i.e. the most accelerating CVT speed ratio
• Low i.e. the most decelerating CVT speed ratio
• the vehicle can also be efficiently operated steady state in a CVT speed ratio near Medium, where the component efficiency of the CVT is highest, or more towards Overdrive to achieve the highest vehicle speeds.
• the EM is provided with an individual efficiency characteristic that is intersected by the said steady state torque requirement curve in Overdrive between 30% and 50%, preferably around 35% of the maximum, i.e. peak, speed of the EM, e.g. as specified or as actually occurring during operation of the electric vehicle.
• FIG. 1 is a schematic representation of the functional arrangement of the main components of a known electric vehicle powertrain with an electric machine and a continuously variable transmission unit;
• FIG. 2 is a graph illustrating a torque vs rotational speed characteristic of three differently specified electric machines
• FIG. 3 illustrates an aspect of the present invention related to the design of an electric machine in a torque vs. speed graph thereof;
• FIG. 4 illustrates a first aspect of the present invention related to the design of the powertrain in an torque vs. speed graph of the electric machine
• FIG. 5 illustrates a second aspect of the present invention related to the design of the powertrain
• FIG. 6 illustrates a third aspect of the present invention related to the design of the powertrain by way of a map linking vehicle speed and electric machine power to continuously variable transmission speed ratio.
• FIG. 1 shows a basic example of a known powertrain for an electric vehicle such as a passenger car.
• the known electric vehicle powertrain comprises an electric machine (EM) 1 , also known as a motor/generator device, two driven wheels 2 of the electric vehicle and a gearing 3 that drivingly connects the EM 1 to the driven wheels 2.
• the known gearing 3 includes a continuously variable transmission (CVT) unit 40, providing a continuously variable speed ratio between an input shaft and an output shaft thereof, is included therein.
• the CVT unit 40 is as such well-known, in particular in the form comprising a drive belt 41 that is wrapped around and in frictional contact with both an input pulley 42 on the input shaft and an output pulley 43 on the output shaft of the CVT unit 40.
• An effective radius of the friction contact between the drive belt 41 and a pulley 42, 43 can be varied in mutually opposite directions between the two pulleys 42, 43 by means of a control and actuation system (not shown) of the CVT unit 40, such that a speed ratio provided by the CVT unit 40 between its input and output shafts can be continuously varied with a certain speed ratio range between a most decelerating CVT speed ratio, i.e. Low, and a most accelerating CVT speed ratio, i.e. Overdrive.
• the take-off acceleration and/or top speed of the electric vehicle can be increased thereby.
• these performance parameters of the vehicle can be maintained at the same level, but while applying a smaller, i.e. downsized EM 1 .
• EM 1 e.g. fig. 2, dashed line
• FIG 2 such downsizing relative to a reference EM 1 (e.g. fig. 2, dashed line) applied in a powertrain without CVT, can be in terms of the maximum, i.e. peak speed requirement of the EM 1 (e.g. fig. 2, lines EMs), the maximum, i.e. peak torque requirement of the EM 1 (not illustrated) or both (e.g. fig.
• the downsized EM 1 is preferably characterised by an at least essentially constant peak torque as a function of its rotational speed, at least in a predominant part of its speed range, i.e. from 0 up to at least 50% of its peak speed. More preferably, the peak torque of the downsized EM 1 is constant up to at least 80%, more preferably up to at least 90% or even up to 95% of its peak speed. Alternatively or additionally, the downsized EM 1 is preferably characterised by an essentially constant peak speed as a function of its torque, at least in a predominant part of its torque range, i.e. from 0 up to at least 50% of its peak torque. More preferably, the peak speed of the downsized EM is constant up to at least 80%, more preferably up to at least 90% or even up to 95% of its peak torque.
• the EM 1 is downsized in terms of its peak torque, a limitation occurs that is illustrated in figure 3. Namely, as the peak torque of the EM 1 is reduced, a so-called, torque-reserve Tr (as defined by the difference between such peak torque and an, instantaneous, actual torque) at a certain speed of the EM 1 .
• the torque reserve Tr relative to an efficiency characteristic curve r
• this limitation can, however, be favourably alleviated by designing the downsized EM 1 with an efficiency characteristic curve H max-EMt that remains below 50% of the EM peak torque Tmax up to, at least 50% and preferably up to around 70% of the EM peak speed Smax. More preferably, such efficiency characteristic curves q max-EMt of the downsized EM extends up to and thus includes the EM peak speed Smax.
• the CVT unit 40 and the EM 1 can be advantageously adapted mutually, as illustrated in figure 4.
• the speed ratio range provided by the CVT unit 40 and the efficiency characteristic curve q max of the EM 1 are preferably mutually adapted in such a manner that:
• a steady state i.e. constant vehicle speed, EM torque requirement in CVT speed ratio Low, indicated in figure 4 by the curve TR Low , is located below the efficiency characteristic q max of the EM 1 ;
• a steady state i.e. constant vehicle speed, EM torque requirement in CVT speed ratio Overdrive, indicated in figure 4 by the curve TRo verdrive , is located partly below and partly above the efficiency characteristic curve q max of the EM 1.
• these latter two curves intersect between 30% and 50%, preferably around 35% of the EM peak speed Smax.
• the respective efficiency characteristics thereof can also be taken into account in the control of the speed ratio of the CVT unit 40 in the electric vehicle powertrain.
• a combined efficiency characteristic is determined by mutually multiplying the individual efficiency maps of the EM 1 and the CVT unit 40, as is schematically illustrated in figure 5. It is, however, noted that figure 5 contains a simplification, namely that the speed ratio dependency of the CVT efficiency map is not illustrated therein, since that would require a third axis of CVT input speed.
• the CVT efficiency map of figure 5 is plotted for the CVT speed ratio providing the highest efficiency, which is Medium for a middle part MP of the CVT output speed range, which gradually changes towards Low for a low part LP of the CVT output speed range and which gradually changes towards Overdrive for a high part HP of the CVT output speed range.
• the resulting, combined efficiency characteristic links a desired CVT speed ratio to a EM power level providing maximum system power efficiency.
• the above concept of the combined efficiency characteristic of powertrain components is illustrated once more, however, including the vehicle speed as an input variable and the CVT speed ratio as an output variable.
• the three lines marked 2, 1 and 0.5 respectively represent the three CVT speed ratios -numerically defined as CVT input speed divided by CVT output speed- of Low, Medium and Overdrive.
• the combined efficiency characteristic is a continuous efficiency map, wherein intermediate CVT speed ratios fill-in the space between the said three lines. Therefore, based on such map and given a vehicle speed and an EM power, a desired CVT speed ratio providing optimum combined power efficiency of the EM 1 and the CVT unit 40 is obtained.
• continuous map will be approximated by an essentially, i.e. semi-continuous map, look-up table or (set of) mathematical equation(s) programmed into a logic unit of the electric vehicle.
• the top half of the graph of figure 6, i.e. the continuous efficiency map represented thereby, representing positive, i.e. driving EM torque or power levels, can also be applied for negative, i.e. braking EM torque or power levels.
• a further improvement can be obtained by measuring or calculating it specifically for such negative EM torque or power levels.
• most efficient operating points are available for the powertrain as a whole as a function of the instantaneous (reverse, i.e. braking) torque or power and (forward) speed of the electric vehicle.
• the said most efficient operating points are different between positive and negative EM torque or power levels.
• this asymmetry can be largely attributed to the CVT unit 40, in particular the presently illustrated belt-and- pulleys-type CVT unit 40.

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• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Transportation (AREA)
• Control Of Transmission Device (AREA)
• Hybrid Electric Vehicles (AREA)
• Arrangement Of Transmissions (AREA)
• Electric Propulsion And Braking For Vehicles (AREA)

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Publications (1)

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• 2019
  • 2019-12-05 CN CN201980093683.0A patent/CN113544413A/zh active Pending
  • 2019-12-05 EP EP19827624.8A patent/EP3935291A1/en not_active Withdrawn
  • 2019-12-05 WO PCT/EP2019/025436 patent/WO2020177833A1/en unknown
• 2020
  • 2020-03-06 WO PCT/EP2020/025117 patent/WO2020177931A1/en active Application Filing
  • 2020-03-06 CN CN202080019148.3A patent/CN113646200A/zh active Pending
  • 2020-03-06 JP JP2021552678A patent/JP2022525003A/ja active Pending

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