WO2022128044A1 - Procédé d'actionnement d'un groupe motopropulseur de véhicule électrique comprenant une transmission à variation continue - Google Patents

Procédé d'actionnement d'un groupe motopropulseur de véhicule électrique comprenant une transmission à variation continue Download PDF

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Publication number
WO2022128044A1
WO2022128044A1 PCT/EP2020/025592 EP2020025592W WO2022128044A1 WO 2022128044 A1 WO2022128044 A1 WO 2022128044A1 EP 2020025592 W EP2020025592 W EP 2020025592W WO 2022128044 A1 WO2022128044 A1 WO 2022128044A1
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WO
WIPO (PCT)
Prior art keywords
speed
vehicle
speed ratio
continuously variable
electric machine
Prior art date
Application number
PCT/EP2020/025592
Other languages
English (en)
Inventor
Ingmar HUPKES
Original Assignee
Robert Bosch Gmbh
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 Robert Bosch Gmbh filed Critical Robert Bosch Gmbh
Priority to PCT/EP2020/025592 priority Critical patent/WO2022128044A1/fr
Publication of WO2022128044A1 publication Critical patent/WO2022128044A1/fr

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Classifications

    • 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
    • F16H61/662—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 with endless flexible members
    • F16H61/66254—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 with endless flexible members controlling of shifting being influenced by a signal derived from the engine and the main coupling
    • F16H61/66259—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 with endless flexible members controlling of shifting being influenced by a signal derived from the engine and the main coupling using electrical or electronical sensing or control means
    • 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
    • F16H57/02—Gearboxes; Mounting gearing therein
    • F16H57/028—Gearboxes; Mounting gearing therein characterised by means for reducing vibration or noise
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60Y—INDEXING SCHEME RELATING TO ASPECTS CROSS-CUTTING VEHICLE TECHNOLOGY
    • B60Y2300/00—Purposes or special features of road vehicle drive control systems
    • B60Y2300/18—Propelling the vehicle
    • B60Y2300/20—Reducing vibrations in the driveline

Definitions

  • the present invention relates to a powertrain for an electric vehicle, in particular a passenger vehicle, with an electric machine that is also known as a motor/generator unit, a driven wheel and with a continuously variable transmission (CVT) that drivingly connects, i.e. rotationally couples, the electric machine to the driven wheel.
  • an electric vehicle is to be understood as referring to a vehicle with an electric powertrain, such as battery electric vehicles (BEV) and fuel cell electric vehicles (FCEV), which electric powertrain includes the electric machine as a prime mover of the said driven wheel, but does, in particular, not include an internal combustion engine that is, or at least can be, connected to the said two driven wheels in addition to or instead of the electric machine.
  • BEV battery electric vehicles
  • FCEV fuel cell electric vehicles
  • 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 mainstream CVT design 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 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 composite 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 axially 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. In turn, 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 electric machine to be operated within a continuous range of rotational speeds -as determined by the speed ratio range of the CVT- in relation to a constant vehicle speed.
  • the electric machine (rotational) speed can for example be controlled -by controlling the speed ratio of CVT- towards the maximum energy efficiency of (at least) the electric machine.
  • a desired rotational speed of the electric machine is typically determined by an electronic control unit (ECU) of the vehicle based on several operating parameters including, at least, the current vehicle speed and an (energy) efficiency versus generated power characteristic of (at least) the electric machine.
  • the CVT speed ratio is adjusted via the CVT actuation system under the control of the ECU to match the actual speed of the electric machine as closely as possible with the said desired speed thereof.
  • CVT speed ratio control methods are employed that take into account not only the efficiency of the electric machine, but also the efficiency of other powertrain components, such as a so-called inverter connecting the electric machine to a battery pack of the vehicle, and that, moreover, not only rely on the current vehicle speed, but also on other operating parameters, such as the position of the accelerator pedal of the vehicle.
  • the accelerator pedal position is often interpreted as an instantaneous acceleration demand (that can be zero or negative) introduced by the driver.
  • the ECU is typically pre-programmed with a characteristic curve, look-up table, or the like, wherein the desired electric machine speed is linked to the electric machine torque required for realising the demanded acceleration at the (instantaneous) vehicle speed.
  • the powertrain is automatically operated, such as by a cruise control system or an autonomous driving system, such system will generate the said instantaneous acceleration demand in lieu of the driver.
  • the known CVT speed ratio control method can be improved upon, in particular in terms of the comfort of the occupants of the electric vehicle.
  • the invention departs from the notion that the so-called NVH (noise, vibration and harshness) characteristics of the electric powertrain are superior to those of an ICE powertrain. Although favourable per se, this also has the effect that, generally speaking, lower noise and/or vibration levels are noticeable to the occupants of an electric vehicle than to the occupants of an ICE vehicle.
  • the variability of the CVT is in this respect favourably put to use in the electric vehicle, by controlling the CVT speed ratio to avoid specific rotational speeds of the electric machine, in particular those rotational speeds that are related to the highest noise and/or vibration levels in the electric vehicle, in particular in the vehicle cabin.
  • These specific electric machine speeds typically correspond to resonant frequencies of certain parts of the powertrain, the vehicle body and/or of its interior.
  • the rotational speeds of the electric machine to be avoided can be predetermined for a certain vehicle/vehicle type by its manufacturer and can thus be pre-programmed into the ECU.
  • these specific electric machine speeds are related to one or more (other) operating parameters of the electric powertrain such as a torque generated by the electric machine and/or a speed of the vehicle.
  • the noise and/or vibration level is measured during operation of the electric vehicle and the CVT speed ratio is controlled in relation to such measured level.
  • a so-called minimum-seeking algorithm can be employed by the ECU as part of the CVT speed ratio control.
  • the ECU imposes small perturbations on the CVT speed ratio, the resulting perturbations in the measured noise and/or vibration level are measured and, based on the relationship between these two types of perturbations, the average/middle value of the perturbed CVT speed ratio is adjusted (increased, decreased or maintained) to reduce the noise and/or vibration level.
  • this minimum-seeking control algorithm is employed only when the measured noise and/or vibration level exceeds a certain threshold such that the CVT speed ratio is not adjusted unnecessarily.
  • the ECU can store the measured noise or vibration-level versus, at least, the electric machine speed in a memory and (subsequently) take such memorised values into account when determining the desired electric machine speed in relation to the said one or more (other) operating parameters of the electric powertrain.
  • the adjustment of the CVT speed ratio in relation to the noise and/or vibration level in the electric vehicle is preferably confined to within a range around the CVT speed ratio that would be controlled by the ECU without taking the noise and/or vibration level in the electric vehicle into account as an operating parameter.
  • FIG. 1 is a schematic representation of the basic functional arrangement of the main components of a known electric vehicle powertrain with an electric machine and a continuously variable transmission;
  • FIG. 2 is a graph illustrating a known control method for controlling the speed ratio of the continuously variable transmission in relation to the vehicle speed, both in a steady- state/constant vehicle speed operating condition and in a dynamic operating condition of vehicle acceleration;
  • FIG. 3 provides a graph plotting the noise level in a cabin of the electric vehicle in relation to a rotational speed of the electric machine.
  • FIG. 4 is a graph illustrating the speed ratio control method according to the present invention, both at constant vehicle speed and during vehicle acceleration.
  • FIG 1 shows a basic example of a known powertrain for an electric vehicle such as a passenger vehicle.
  • the known electric powertrain comprises an electric machine (EM) 1 , two driven wheels 2 of the electric vehicle and a gearing 3 that drivingly connects the EM 1 to the driven wheels 2.
  • the gearing 3 includes a continuously variable transmission (CVT) 40, providing a continuously variable speed ratio between an input shaft and an output shaft thereof.
  • the known gearing 3 further includes a differential 37, allowing the driven wheels 2 to rotate at different speeds, as well as two geared speed reductions 31 , 32, increasing the operating speed of the EM 1 relative to the driven wheels 2.
  • the CVT 40 as such is 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 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 40 to vary the said speed ratio provided thereby, between a most decelerating CVT ratio from the input shaft to the output shaft, i.e. Low ratio, and a most accelerating CVT ratio, i.e. Overdrive ratio.
  • CVT 40 By including the CVT 40 in the electric powertrain several advantages and/or optimisation strategies are unlocked. For example, its (energy) efficiency can be improved, or the acceleration at take-off and/or the top speed of the electric vehicle can be increased thereby. Alternatively, these latter two performance parameters of the vehicle can be maintained at the same level, while applying a downsized EM 1 .
  • the basic operation of the known electric powertrain with CVT 40 is illustrated in the form of a so-called variogram that provides the relationship between the vehicle speed and the rotational speed of the EM 1 .
  • the CVT 40 provides that such relationship is represented by any such line located in the area defined by and between a lowermost boundary line that is applicable when the CVT 40 is in Low-ratio and an uppermost boundary line that is applicable when the CVT 40 is in Overdrive ratio.
  • the EM speed can be controlled to any value between approximately 3000 and 9000 rpm by adjusting the speed ratio of the CVT 40 between Overdrive-ratio and Low-ratio respectively.
  • the contour line Es represents an example of such a control strategy for steady state or so-called “road load” conditions, i.e. for constant vehicle speed on a flat surface and windless (only driving wind load), whereas the contour line Ed defines the optimum EM speed in terms of energy efficiency for vehicle acceleration.
  • the specific contour line Ed illustrated in figure 2 is determined for a power excess of 20 kW relative to the power required to be generated by the EM 1 to maintain the said constant vehicle speed.
  • the variogram of figure 2 yields a desired value or set-point for the EM speed of -7350 rpm that is as indicated in figure 2 by the circle A.
  • a straight line draw through this point A and the origin of the variogram then defines the desired, likewise constant CVT speed ratio.
  • the desired CVT speed ratio is the Low ratio until the EM speed reaches -6000 rpm at a vehicle speed of -30 km/h.
  • the CVT speed ratio is changed as a function of the vehicle speed, until the EM speed reaches -8000 rpm at a vehicle speed of -90 km/h. Above 8000 rpm, the CVT speed ratio according to the contour line Ed is again more or less constant, i.e. is independent of the vehicle speed.
  • both the frequency and the level of the noise generated by the powertrain during operation increases with an increasing speed of the EM 1 .
  • This (increasing) noise level is schematically illustrated in figure 3 by the solid line that represents the noise level in the vehicle cabin and by the dashed line T that represents the averaged trend of such noise level.
  • one or more local peaks P1 , P2 can occur in the noise level relative to the trend line T thereof, in particular due to resonance of certain components of the vehicle.
  • the variability of the CVT can be favourably put to use in the electric vehicle to avoid such local peak P1 ; P2 in the noise level during operation, in particular by limiting the time that the EM 1 is operated at an EM speed corresponding to such local peak P1 ; P2.
  • the CVT speed ratio is thereto controlled such that an EM speed related to the highest noise and/or vibration levels in the electric vehicle is largely avoided.
  • the practical implementation of the CVT speed ratio control method according to the present invention is discussed in more detail below with reference to figure 4.
  • Figure 4 represents a close-up of a section of the variogram depicted in figure 2, however, with the addition of a range R of EM speeds corresponding to an increased noise level compared to the noise level that occurs just outside such range R.
  • an alternative desired CVT speed ratio is determined in relation to the vehicle speed, corresponding to an EM speed outside the said range R, e.g. either in point B in figure 4 by specifying a desired CVT speed ratio that offset towards Overdrive ratio or in point C in figure 4 by specifying a desired CVT speed ratio that offset towards Low ratio.
  • the energy efficiency of the electric powertrain will be less in the said operating points B or C than in operating point A, this difference will typically be very small, in particular if the contour line Es has only a small inclination in the variogram, which is generally the case in the operating points prescribed by the WLTC or other regulatory vehicle test cycles. Moreover, between the said operating points B or C, the most efficient one can be selected as part of the CVT speed ratio control method according to the present invention.
  • the present invention also concerns the dynamic accelerating/deceleration, operation of the vehicle.
  • vehicle acceleration can, for example, take place according to the contour line Ed in the variogram of figure 4. It can be seen that, during such vehicle acceleration, the EM 1 is operated in the said EM speed range R as the vehicle speed increases from (approximately) 62 to 73 km/h. According to the present invention, however, when the operating point D on the contour line Ed is reached, i.e. just before the EM speed enters the said range R, the CVT speed ratio is controlled to keep the EM speed essentially constant in relation to an increasing vehicle speed.
  • This constant EM speed CVT speed ratio control is maintained until the vehicle speed has reached a value in operating point E for which the contour line Ed defines an EM speed just beyond the said range R.
  • the CVT speed ratio is controlled to increase the EM speed in relation to an essentially constant vehicle speed.
  • This constant vehicle speed CVT speed ratio control is maintained until the EM speed has reached a value in operating point F that again lies on the contour line Ed, however, outside the said range R. It is noted that, when following the contour line Ed between the operating points D and F, i.e. while accelerating the vehicle, crossing the said EM speed range R takes considerably more time than crossing such range R at an essentially constant vehicle speed between the operating points E and F, while accelerating only the EM 1 .

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Control Of Driving Devices And Active Controlling Of Vehicle (AREA)
  • Control Of Transmission Device (AREA)
  • Hybrid Electric Vehicles (AREA)

Abstract

L'invention concerne un procédé pour faire fonctionner un groupe motopropulseur de véhicule électrique, en particulier dans un véhicule de tourisme, lequel groupe propulseur comprend une machine électrique (1), une roue entraînée (2) et une transmission à variation continue (40) qui est disposée entre la machine électrique (1) et la roue entraînée (2), fournissant une liaison d'entraînement entre celles-ci à un rapport de vitesse variable en continu, pendant le fonctionnement du groupe motopropulseur, le rapport de vitesse de la transmission à variation continue (40) étant commandé au moyen d'une unité de commande électronique par rapport à, au moins, la vitesse du véhicule. Selon l'invention, le rapport de vitesse de la transmission à variation continue (40) est en outre commandé par rapport à un niveau de bruit ou de vibration généré par le groupe motopropulseur ou dans le véhicule dans lequel il est appliqué.
PCT/EP2020/025592 2020-12-19 2020-12-19 Procédé d'actionnement d'un groupe motopropulseur de véhicule électrique comprenant une transmission à variation continue WO2022128044A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/EP2020/025592 WO2022128044A1 (fr) 2020-12-19 2020-12-19 Procédé d'actionnement d'un groupe motopropulseur de véhicule électrique comprenant une transmission à variation continue

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Application Number Priority Date Filing Date Title
PCT/EP2020/025592 WO2022128044A1 (fr) 2020-12-19 2020-12-19 Procédé d'actionnement d'un groupe motopropulseur de véhicule électrique comprenant une transmission à variation continue

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4593582A (en) * 1982-10-15 1986-06-10 Toyota Jidosha Kabushiki Kaisha Continuously variable transmission means for use in vehicles
EP2873893A1 (fr) * 2012-07-12 2015-05-20 Nissan Motor Co., Ltd Dispositif de commande pour véhicule
WO2020057712A1 (fr) * 2018-09-18 2020-03-26 Robert Bosch Gmbh Groupe motopropulseur doté d'une transmission à variation continue pour un véhicule électrique et procédé de fonctionnement d'un véhicule électrique

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4593582A (en) * 1982-10-15 1986-06-10 Toyota Jidosha Kabushiki Kaisha Continuously variable transmission means for use in vehicles
EP2873893A1 (fr) * 2012-07-12 2015-05-20 Nissan Motor Co., Ltd Dispositif de commande pour véhicule
WO2020057712A1 (fr) * 2018-09-18 2020-03-26 Robert Bosch Gmbh Groupe motopropulseur doté d'une transmission à variation continue pour un véhicule électrique et procédé de fonctionnement d'un véhicule électrique

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