(12) United States Patent
`Graf et al.
`
`I IIIII IIIIIIII Ill lllll lllll lllll lllll lllll lllll lllll lllll 111111111111111111
`US006188945Bl
`US 6,188,945 Bl
`Feb.13,2001
`
`(10) Patent No.:
`(45) Date of Patent:
`
`(54) DRIVE TRAIN CONTROL FOR A MOTOR
`VEHICLE
`
`(75)
`
`Inventors: Friedrich Graf, Regensburg; Gregor
`Probst, Landshut; Roman Strasser,
`Burgkirchen, all of (DE)
`
`(73) Assignee: Siemens Aktiengesellschaft, Munich
`(DE)
`
`( *) Notice:
`
`Under 35 U.S.C. 154(b), the term of this
`patent shall be extended for O days.
`
`(21) Appl. No.: 08/937,253
`
`(22) Filed:
`
`Sep. 12, 1997
`
`(30)
`
`Foreign Application Priority Data
`
`Sep. 12, 1996
`
`(DE) .............................................. 196 37 210
`
`Int. Cl.7 ............................ B60K 41/04; F02D 28/00
`(51)
`(52) U.S. Cl. ............................... 701/58; 701/54; 180/65.2
`(58) Field of Search .................................. 701/51, 58, 60,
`701/61, 54, 53, 48, 57; 180/65.2; 477/20,
`107, 109, 110
`
`(56)
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`4,853,720
`4,866,622 *
`5,012,418
`5,113,721 *
`5,150,635
`5,351,776
`5,450,324
`5,508,923 *
`5,521,823
`
`8/1989
`9/1989
`4/1991
`5/1992
`9/1992
`10/1994
`9/1995
`4/1996
`5/1996
`
`Onari et al. ..................... 364/431.07
`Dreher et al. .. ... ... ... ... .... ... ... 701/102
`Petzoid.
`Polly ...................................... 477/80
`Minowa et al.
`....................... 74/866
`Keller et al. ... ... ... ... ... .... ... .. 180/79 .1
`Cikanek .......................... 364/426.02
`Ibamoto et al.
`....................... 701/70
`Akita et al. ..................... 364/424.05
`
`FOREIGN PATENT DOCUMENTS
`
`4039005Al
`
`6/1991 (DE) .
`
`4401416Al
`0388107
`0576703Al
`2 031 822
`2240827
`2255057
`
`7/1995 (DE) .
`9 /1990 (EP) .
`1/1994 (EP) .
`4/1980 (GB) .
`8/1991 (GB) .
`10/1992 (GB) .
`
`OTHER PUBLICATIONS
`
`International Applicatio WO 90/03898 (Lang), dated Apr.
`19, 1990.
`"Systemvernetzung im Automobil", R. Leonhard, Stuttgart,
`Feinwerkstechnik im Fahrzeugbau, Munchen, 1993, pp.
`87-90.
`
`"Fahrzeugregelung und regelungstechnische Komponenten(cid:173)
`abstimmung", U. Zoelch et al., VDM Berichte No. 1225,
`1995, pp. 281-297, pertains to motor vehicle control and
`closed-loop/open-loop control adjustment.
`
`* cited by examiner
`
`Primary Examiner-Michael J. Zanelli
`(74) Attorney, Agent, or Firm-Herbert L. Lerner;
`Laurence A. Greenberg; Werner H. Sterner
`
`(57)
`
`ABSTRACT
`
`An integrated drive train control system for a motor vehicle
`interprets the position of the accelerator pedal and the brake
`pedal as a wheel torque desired by the driver. A calculating
`device receives signals representing the positions of the
`accelerator pedal and the brake pedal. Central control
`parameters for the drive sources and for the decelerating
`units of the drive train are generated on the basis of the
`position signals. A classification device evaluates the sensor
`signals from the drive train and classifies operating param(cid:173)
`eters of the motor vehicle.
`
`8 Claims, 5 Drawing Sheets
`
`,----------·-·-·-·-·-·
`I r
`/
`accelerator
`.
`.
`Conversion
`----/
`21 L . ___ ..._,
`6* /
`to nominal
`• . wheel torque
`.
`12
`I
`s
`.
`standard ---f--1
`7* I
`I
`transmission ratio !
`I~~-slalus _ _j
`
`sensors
`
`2*
`
`•
`4
`
`·
`
`·
`
`Torque wheel
`
`Choice of basic strategy
`
`Combined computation of
`basic operation parameters
`engine torque/
`transmission ratio
`
`Torque
`engine
`
`Detection and
`classification
`of driver, load
`Driving
`situation
`detection
`
`L.r·-------·
`
`1 *
`
`ETC
`
`engine
`(control)
`system
`
`9*
`
`transmission
`( control)
`system
`
`10*
`
`13*
`
`BMW1020
`Page 1 of 11
`
`

`

`U.S. Patent
`
`Feb.13,2001
`
`Sheet 1 of 5
`
`US 6,188,945 Bl
`
`FIG.1
`
`SENSORS
`
`1.01
`
`1.03
`
`CENTRAL CLASSIFICATION AND
`CRITERIA FORMATION
`
`ACCELERATOR
`PEDAL
`
`BRAKE
`
`DETERMINING CENTRAL
`---.. OPERATING
`PARAMETERS
`
`CHOICE OF DRIVING
`STRATEGY
`
`DECENTRALIZED CONTROL UNITS
`
`1_/
`
`ASSEMBLIES .....-....-
`
`1.06
`
`1.02
`
`1.05
`
`BMW1020
`Page 2 of 11
`
`

`

`FIG.2
`
`1.02
`CENTRAL
`CLASSIFICATION {
`AND CRITERIA
`FORMATION
`
`16
`s .,----.... -
`
`~ J
`
`...
`-
`
`s
`
`l<
`
`3
`
`I
`
`s
`
`i..
`
`4
`
`It
`
`5
`
`DETERMINING DRIVER
`TYPE AND DESIRE
`
`LOCALIZATION OF
`EVIRONMENT/ROAD
`TYPE (GPS)
`
`DRIVING MANEUVER,
`DRIVING SITUATION
`
`INFORMATION CHANNEL
`(CAR TELEPHONE,
`SATELLITE)
`
`15
`
`_ _ 17
`
`CHOICE OF BASIC DRIVING STRATEGY
`
`>
`
`I
`
`r
`
`l
`
`'
`
`< >
`
`< >
`
`6
`
`19
`
`,,.
`
`< >
`10
`
`1 ___.,,,-(cid:173)
`
`s
`
`DETERMINING BASIC
`OPERATING PARAMETERS
`
`7
`
`13 DECENTRALIZED {
`CONTROL
`UNITS
`
`•••••••
`
`FGR
`
`23
`
`20
`
`CALCULATING
`WHEEL
`1 TORQUE
`I DRIVER
`.. INFORMATION
`C
`
`21(S)
`
`16
`
`'
`
`11
`
`ABS-TCS-FSR
`
`S(1)
`
`24......,-
`
`13
`
`d •
`r:JJ.
`•
`~
`~ .....
`~ = .....
`
`"'!"j
`~
`?'
`"'"" ~~
`N
`C
`C
`"'""
`
`'Jl =(cid:173)~
`~ ....
`N
`0 ....,
`Ul
`
`e
`rJ'J.
`-..a-..
`i,(cid:173)
`~
`~
`\0
`,I;;..
`(It
`~
`i,-
`
`BMW1020
`Page 3 of 11
`
`

`

`accelerator
`--/
`L.
`
`21
`
`1r·-·-·-·-·-·-·-·-·-·-·---,
`I
`·
`Conversion
`to nominal
`Torque wheel
`6* .
`I
`.
`12* · wheel torque
`I
`Combined computation o f · I
`basic operation parameters
`7*
`engine torque/
`transmission ratio
`
`Choice of basic strategy
`
`,·
`
`d •
`r:JJ.
`•
`~
`~ .....
`~ = .....
`
`"'!"j
`~
`?'
`"'"" ~
`N
`C
`C
`"'""
`
`'JJ. =(cid:173)~
`~ ....
`0 ....,
`Ul
`
`~
`
`e
`rJ'J.
`O'I
`1-
`
`~
`~
`\0
`,I;;..
`(It
`~
`i,-
`
`S ~ Detection and
`standard
`.
`classification
`sensors
`·
`of driver, load
`
`2*
`
`t\~~~
`;fo~'\)
`Driving
`situation
`4 * ~ ;;~·t;~·ii~·~
`L~-----
`.T
`
`ETC
`
`1 *
`
`FIG 3
`
`Torque
`engine
`
`transmission ratio !
`lock up status _J
`· - · - ·
`
`transmission
`(control)
`system
`
`1
`
`, )
`
`10*
`
`(9)
`
`13*
`
`engine
`( control)
`system
`
`9*
`
`BMW1020
`Page 4 of 11
`
`

`

`U.S. Patent
`
`Feb.13,2001
`
`Sheet 4 of 5
`
`US 6,188,945 Bl
`
`FIG.4
`
`ACTIVATE CRUISE CONTROL (IF DESIRED}
`
`S1
`
`CONVERT ACCELERATOR PEDAL/BRAKE TO
`DESIRED WHEEL MOMENT (BLOCK 12}, INCLUDE
`CRUISE CONTROL
`
`r---...,_----,
`
`S2
`
`CLASSIFY OR DETECT DRIVER, ENVIRONMENT,
`DRIVING MANEUVERS (BLOCKS 1,3,4}
`
`INTERROGATE INFORMATION CONDUIT (BLOCK 5}
`
`CHOOSE BASIC DRIVING STRATEGY (BLOCK 6)
`
`S3
`
`S4
`
`ss
`
`CHOOSE BASIC OPERATING PARAMETERS FOR THE DRIVE TRAIN
`(BLOCK 7): DRIVE/DECELERATION SOURCE, CALCULATION OF
`OPERATING POINTS FOR DRIVE/DECELERATION SOURCE,
`CALCULATE OPERATING POINT FOR TRANSMISSION (BLOCK 8)
`
`S6
`
`MONITOR DRIVING STABILITY: ABS, TCS, FCR
`ADJUST DESIRED BRAKING MOMENT
`
`S7
`
`S8
`
`S10
`
`S9
`
`DRIVE TORQUE OR BRAKE TORQUE
`CORRECTED IN DRIVE (BLOCK 7 OR 9)
`
`S11
`
`INCREASE DRIVING PERFORMANCE
`
`END
`
`BMW1020
`Page 5 of 11
`
`

`

`U.S. Patent
`
`Feb.13,2001
`
`Sheet 5 of 5
`
`US 6,188,945 Bl
`
`FIG 5
`
`Step 6
`
`1
`
`Calculate stationary parameters for drivel
`transmission (based on performance graphs,
`algorithm, fuzzy system, strategy specification)
`
`-S6.1
`
`, I
`
`Calculate temporary intervention into drivel
`transmission (depending on driving situation, f---'
`driving maneuver) 1)
`
`S6 2
`
`·
`
`1) Such as: gear lockup in overrunning, brake assistance
`
`BMW1020
`Page 6 of 11
`
`

`

`US 6,188,945 Bl
`
`1
`DRIVE TRAIN CONTROL FOR A MOTOR
`VEHICLE
`
`BACKGROUND OF THE INVENTION
`
`Field of the Invention
`The invention relates to a drive train control system for a
`motor vehicle, by which the position of the accelerator pedal
`is interpreted as a wheel torque or transmission output
`torque desired by the driver and used for calculating desired 10
`values for the engine and transmission of the motor vehicle.
`Prior art control systems for the engine, for the
`transmission, and for the secondary assemblies of a motor
`vehicle operate largely independently; that is, they establish
`the operating point and operating mode of the controlled 15
`assembly largely independently of one another. Means are
`also available for communication among the various com(cid:173)
`ponents of the drive train of a motor vehicle, for instance in
`the form of a CAN bus or the like, but these means are
`predominantly used only for exchanging sensor data in the 20
`course of multiple utilization. Moreover, the control systems
`affect one another by means of communication in certain
`operations, for instance to make for smoother shifting by
`reducing the engine torque upon a change of transmission
`ratio in the transmission.
`Other examples are engine drag torque control during
`braking and braking intervention or torque reduction if drive
`slip arises in the traction control context. A system for
`linking together systems in the automobile has become
`known heretofore that seeks an integrated drive train control 30
`system for a motor vehicle by means of which the position
`of the accelerator pedal is interpreted as a wheel torque
`desired by the driver and used for calculating desired values
`for the engine and transmission of the motor vehicle (F & M
`101 (1993) 3, pp. 87-90). The goal of the overriding 35
`optimization, proposed in this publication, of the parts of the
`system embodied by the engine control unit, electronic
`accelerator pedal and transmission control unit, is to reduce
`fuel consumption and improve the drivability, in particular
`with regard to the spontaneous reaction to movements of the 40
`accelerator pedal.
`
`5
`
`25
`
`2
`interpreting the position of the accelerator pedal as a
`wheel torque or transmission output torque desired by
`a driver of the motor vehicle and calculating therefrom
`setpoint values for the engine and the transmission of
`the motor vehicle;
`a classification device connected to receive sensor signals
`from the drive train, the classification device being
`programmed to evaluate the sensor signals and to
`classify operating parameters of the motor vehicle; and
`the calculating device combining the position signals and
`the classified operating parameters and generating
`therefrom central control parameters for drive sources
`and decelerating units of the drive train of the motor
`vehicle.
`In accordance with an added feature of the invention, the
`calculating device is programmed to adjust a transmission
`ratio in the transmission.
`In accordance with an additional feature of the invention,
`the calculating device adjusts the engine output torque.
`In accordance with another feature of the invention, the
`calculating device defines a type of drive source of the motor
`vehicle. Where the engine is a hybrid drive, the calculating
`device defines and adjusts individual operating points of the
`hybrid drive.
`In accordance with a further feature of the invention, the
`calculating device adjusts the engine torque as a function of
`the transmission ratio of the hybrid drive.
`In accordance with again a further feature of the
`invention, the system further includes:
`a selection circuit connected to receive output signals of
`the classification circuit, the selection circuit selecting
`a driving strategy based on the output signals of the
`classification circuit; and decentralized control units
`connected to receive output signals of the calculating
`device and of the selection circuit, the decentralized
`control units generating control signals for the engine,
`the transmission and a brake system of the motor
`vehicle.
`In accordance with a concomitant feature of the invention,
`a data exchange among the control units is effected in a
`torque-based manner.
`Other features which are considered as characteristic for
`the invention are set forth in the appended claims.
`Although the invention is illustrated and described herein
`45 as embodied in a drive train control system for a motor
`vehicle, it is nevertheless not intended to be limited to the
`details shown, since various modifications and structural
`changes may be made therein without departing from the
`spirit of the invention and within the scope and range of
`50 equivalents of the claims.
`The construction and method of operation of the
`invention, however, together with additional objects and
`advantages thereof will be best understood from the follow(cid:173)
`ing description of specific embodiments when read in con-
`55 nection with the accompanying drawings.
`
`SUMMARY OF THE INVENTION
`
`It is accordingly an object of the invention to provide a
`drive train control for a motor vehicle, which overcomes the
`above-mentioned disadvantages of the heretofore-known
`devices and methods of this general type and which globally
`improves the operation of the motor vehicle. Emissions
`(hydrocarbons, nitrogen oxides, etc.) are to be minimized by
`centrally defining a strategy for the engine control, engine
`performance adjuster and transmission control, that mini(cid:173)
`mizes the emission of pollutants, especially in urban areas.
`The central strategy may also have as its goal a performance(cid:173)
`oriented mode of the motor vehicle. In such a strategy, all the
`decentralized function units are adjusted in such a way that
`the best possible acceleration and rapid response of the drive
`to driver demands are available. Such a mode is required in
`a sporty driving mode and in driving uphill.
`With the foregoing and other objects in view there is
`provided, in accordance with the invention, a drive train
`control system for a motor vehicle having an engine, a
`transmission, wheels, an accelerator pedal, and a brake
`pedal, the drive train control system comprising:
`a calculating device connected to receive position signals
`representing a position of the accelerator pedal and a
`position of the brake pedal, the calculating device
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`FIG. 1 is a block diagram showing the hierarchical
`structure or architecture of an integrated drive train control
`60 system according to the invention;
`FIG. 2 is a diagrammatic/schematic view of an integrated
`drive train control system according to the invention;
`FIG. 3 is a block diagram showing the control of the
`engine and transmission with another embodiment of the
`65 drive train control system;
`FIG. 4 is a flowchart of the program processed by the
`drive train control system of FIG. 2; and
`
`BMW1020
`Page 7 of 11
`
`

`

`US 6,188,945 Bl
`
`20
`
`30
`
`3
`FIG. 5 is a partial flow chart of a subroutine in the process
`of the flowchart of FIG. 4.
`
`4
`sion ratio. This increases the drivability of the motor vehicle,
`since the driver on upshifting no longer has to compensate
`for a loss of output torque. In addition, and quite
`DESCRIPTION OF THE PREFERRED
`importantly, pollutant emissions can be effectively reduced
`EMBODIMENTS
`5 as well ( as will be explained later herein).
`Referring now to the figures of the drawing in detail and
`The coordinated definition of the operating parameters of
`first, particularly, to FIG. 1 thereof, there is seen an inte(cid:173)
`the engine and transmission takes place not only in a steady
`grated drive train control system 1. For the sake of better
`state, i.e., not only at a constant wheel torque demand from
`readability, the terms "circuit" or "block" will often be
`block 12. Information on dynamic events, such as cornering
`omitted for the individual circuit or program components 10
`or a transition to the overrunning mode (the vehicle speed is
`(for example, selector rather than selection circuit).
`reduced), is taken into account by the block 7 as well, in
`order to coordinate the function units 8-11 that follow it. For
`The components are as follows: sensors 1.01, combined
`instance, in the case of overrunning, the current transmission
`symbolically into one block; a central unit for classification
`ratio can be retained and at the same time the overrunning
`and criteria formation 1.02; a central unit for determining
`operating parameters 1.03, which receives the signals from 15
`shutoff can be activated. In cornering on extremely sharp
`curves, it is appropriate, in order to maintain driving
`the accelerator pedal and the brake pedal of the motor
`stability, that the transmission ratio be fixed (see EGS) and
`vehicle; a driving strategy selector 1.04; decentralized con(cid:173)
`that load changes in the drive train be damped or made to
`trol units 1.05 combined in a block; and the assemblies 1.06
`proceed more slowly (see EMS/ETC).
`of the drive train to be controlled, for example the engine,
`the transmission, and the brakes of the motor vehicle.
`The centralization along the lines of drive mode manage(cid:173)
`ment and emissions management should be done only as
`The function and the mode of operation of the compo(cid:173)
`nents of FIG. 1 will now be described in conjunction with
`much as necessary, however (strategy specification and/or
`delegation). All the other functions (such as functions for
`the description of the other drawing figures.
`driving stability) proceed as much as possible at the level of
`The integrated drive train control system 1 is shown in 25
`the decentralized control units.
`more detail in FIG. 2. It has the following components in the
`The control circuits or units 8-11 produce adjusting
`central classification and criteria formation block 1.02: a
`driver type and driver demand determining circuit 2, an
`signals with which the individual assemblies or components
`of the drive train 24 of the motor vehicle are controlled, that
`environment type and road type localization unit 3 (for
`is, the engine via its throttle valve, the transmission, and the
`example via GPS), a driving maneuver and driving situation
`brakes of the motor vehicle. The adjusting signals pass over
`detection unit 4, and an information channel 5 (for instance,
`lines A from the circuits 9-11 to the assemblies of the drive
`a car phone or a satellite receiver). The circuits 2-5 and other
`train; sensor signals S are carried over corresponding lines
`circuit components to be described below in the drive train
`control system 1 are supplied with the signals from various
`to the aforementioned circuits. The control circuits or units
`8-11 may, however, also be put together as so-called on-site
`sensors in the motor vehicle, here symbolically represented 35
`units with whichever assembly is to be controlled, or can be
`by the letter S, over suitable signals lines. The signal lines
`integrated with it. For instance, it is appropriate for the
`are shown in the drawing as multiple lines but may also be
`controller 11, especially in the case of an electrical brake
`embodied as a data bus (such as a CAN bus).
`actuator, to be combined with the brake actuator. This
`A basic driving strategy selector 6, via lines 14-18,
`changes nothing in terms of the control function.
`receives output signals from the aforementioned circuits 40
`The individual components of the drive train itself are
`2-5. Via a line 19, it receives the output signal of a wheel
`shown toward the bottom of FIG. 2 and will not be explained
`torque calculation device 12, which in turn receives signals
`further here because they are well known. In the case of a
`from a brake pedal 20 and an accelerator pedal or gas pedal
`hybrid drive-that is, an internal combustion engine com-
`21.
`Output signals from the basic driving strategy selector 6 45 bined with an electric motor-the former is coupled to an
`electric motor and a generator G. One such hybrid drive is
`are delivered to a basic operating parameters determining
`known, for instance, from VDI-Bericht [VDI Report; VDI=
`unit 7 and to an electronic engine controller and engine
`Association of German Engineers] No. 1225, 1995, pp. 281,
`performance adjusting unit 9. (The term "unit" as used
`297.
`herein does not necessarily require a separate component,
`Examples of a global or combined drive train control
`but it also encompasses functional subroutines and circuit 50
`system according to the invention are as follows:
`components.) The output signals of the unit 7 proceed to a
`driver information block or display 16, an electrical power
`1. A minimized emissions mode (HC, NOx):
`steering system (EPAS) 8, an electronic engine control
`The basic driving strategy selector 6 defines the oper(cid:173)
`system (EMS/ETC) 9, an electronic transmission control
`ating mode of the entire drive train for minimized
`(EGS) 10, and a brake controller 11, which can include an 55
`pollutant emissions.
`ABS system, a traction control system TCS, and a driving
`From this specification, a central "decider", that is, the
`stability control system FSR.
`basic driving strategy selector 6, defines the essential
`operating parameters of circuits 9, 10 (EMS, ETC,
`The basic operating parameters determining unit ( or
`block) 7 now, in accordance with the strategy specification
`EGS) such that pollutant emissions are minimized
`from block 6, carries out a coordinated calculation of the 60
`(for instance in urban areas). This specification can
`central operating parameters of the entire drive train. In the
`be converted by the following function units as
`block 6, the transmission ratios and the desired engine
`follows:
`torque are for instance defined, but also the drive type and
`ETC ( electronic engine performance controller):
`in the case of a hybrid drive its individual operating points
`load changes of the engine are damped ( demanded
`by unit 12), or the operating range is restricted. By
`as well. This enables a substantially more comprehensive 65
`avoiding non-steady-state events, closed- and
`control of the engine and transmission than before. Thus the
`open-looped control systems that seek a reduction
`engine torque can be adjusted as a function of the transmis-
`
`BMW1020
`Page 8 of 11
`
`

`

`US 6,188,945 Bl
`
`5
`in emissions can operate without error. Operating
`ranges with quantitatively or qualitatively undes(cid:173)
`ired emissions composition are avoided.
`EMS ( electronic engine control): activation of a
`low-emissions mode, for instance in the engine by 5
`reducing fuel enrichment upon acceleration, or
`changing the drive type (for instance to electric
`motor, hydrogen drive)
`EGS ( electronic transmission control): brings about
`the most steady-state operation mode possible for 10
`the engine in a range with minimum emissions, for
`instance with CVT or in a many-geared transmis(cid:173)
`sion;
`adaptation if there is a change of drive type (such as
`electric motor, hydrogen drive, coordinated by
`unit 7): particularly in this function, good coop(cid:173)
`eration of engine and transmission is important,
`because the driver demand with regard to accel(cid:173)
`eration and speed allows more combinations of
`resultant engine torque and transmission ratio. An
`adapted course of the change over time in the two
`controlling variables is also necessary.
`2. A performance-oriented mode.
`Analogously to the minimized emissions mode, all the
`decentralized function units are adjusted such that the
`best possible acceleration and rapid response of the
`drive train to driver demands (unrestricted drive type)
`are available. This is necessary in the sporty driving
`mode or in driving uphill.
`FIG. 1 shows the architecture of such a functional layout.
`However, decisions at lower control levels that affect
`higher specifications are signaled as much as necessary to
`the higher control levels. But this will also be explained in
`conjunction with FIG. 2, whose function will now be
`explained in detail.
`The block ( or circuit) 2 serves to determine the driver
`type, that is, to make a classification expressing a distinction
`between performance-oriented and economy modes. One
`example of such a function is described in European Patent
`Disclosure EP O 576 703 Al. A signal characterizing the
`driving style of the driver is delivered to a basic driving
`strategy selector 6 via a line 14.
`Block 3 ascertains the road type ( city/expressway/
`highway/country road), but also can determine the general
`degree of air pollution, for instance, via additional sensors.
`If the specific location of the vehicle is known by GPS
`(global positioning system) in conjunction with a digital
`card (on CD ROM), then this information on the local air
`pollution can be made available to the block 6.
`A detection, performed in block 4, of individual driving 50
`maneuvers, such as cornering, an uphill grade, drive and
`brake slip, and information on longitudinal and transverse
`stability can also be utilized to ascertain the driving strategy
`choice. This information can also be made available to block
`7, so that by way of the medium-term operating strategy it
`is also possible in the short term to achieve a suitable
`operating mode of the drive train. This information for
`blocks 6 and 7 can also originate in decentralized control
`units (for instance, information on the dynamic driving
`stability from the ABS/TCS/FSR control unit 11) or from the
`information channel 5. Block 5 furnishes information that is
`supplied by a central "control point", such as a traffic
`monitoring agency. This makes regional, centralized control
`of low-emissions operating modes possible.
`Block 6 serves to ascertain the choice of basic driving
`strategy for the following unit 7, which in turn in coordi(cid:173)
`nated fashion ascertains the central operating parameters for
`
`6
`the decentralized control units. The information on the lines
`14, 15, 17 and 18 is compared with a fixed set of rules. This
`is accomplished with a fuzzy system, mathematically for-
`mulated algorithms, or a neural network.
`The sensors S furnish necessary signals both for forming
`the classification and criteria in the top most layer of the
`drive train control system 1, that is, in the units 2-5, and for
`the decentralized control units for the individual assemblies.
`The location of the sensors with regard to the function
`blocks plays a subsidiary role, as long as communications
`between the sensor signal processing in the respective
`control unit (ECU) and the information sink are assured. Nor
`does it matter, with regard to the functional architecture,
`which function units are physically located in which ECU
`15 and combined with it. Thus it is entirely possible to integrate
`the driver type and driver demand determining unit in the
`transmission control system (EGS) 10, while the environ(cid:173)
`mental and road type classification can be accommodated in
`block 11 (regulation of longitudinal and transverse
`20 dynamics).
`A central computer can also contain the units 12, 6, 7.
`What is essential is the virtual architecture, as shown in FIG.
`2, for attaining overall improved function. An important role
`is played here by the communications between the physical
`25 units, which are expediently embodied in the form of fast
`serial bus communication (for instance via a CAN bus).
`The specifications by the driver expressed through the
`accelerator pedal or gas pedal are converted in block 12 into
`a desired wheel torque specification, that is, the torque that
`30 is to be transmitted from the drive wheels to the roadway.
`The influence of environmentally dictated factors, such as
`additional driving resistance (mountain driving, vehicle
`load), are not meant to be taken into account here, so as not
`to alienate the driver from the physical reality.
`Block 12 is shown separately in FIG. 2, but it can also be
`accommodated physically in the decentralized control units
`8-11 or 16 (for instance in EMS/ETC). The same is true for
`locks 1-7. The signal on line 19 can be output as a wheel
`torque desired by the driver, or as a desired circumferential
`40 wheel force or a desired transmission output torque. By
`means of continuous information via the brake pedal 20, it
`is also possible to specify negative desired wheel torques or
`desired circumferential wheel forces. Hence integrated man(cid:173)
`agement of driving units (such as the engine, electric motor,
`45 rotating flywheel) or decelerating units that absorb energy
`(such as the service brake, generator, or a flywheel not in
`motion) are possible. As an alternative to driver specification
`of the wheel torque, this wheel torque can also be specified
`by a cruise control 23 (FGR for short).
`The information channels between block 7 ("basic oper-
`ating parameter determination") and the units 9, 10 and 11
`can be used bidirectionally. The reason for this is the
`necessity, in the calculation of the basic operating
`parameters, of using not only such external conditions as
`55 driver type, environment and driving maneuvers as the basis
`but also of taking into account internal specified operating
`states of the controlled units in the drive train. For instance,
`it is important after a cold start to run the engine at elevated
`rpm in order to reinforce the warmup of the catalytic
`60 converter. Moreover, additional heat sources (such as an
`electrically heated catalytic converter) represent an addi(cid:173)
`tional load on the engine output. Adjusting the ignition
`timing toward "late" after a cold start ( optionally blowing in
`secondary air) for the same purpose changes the character-
`65 is tics of the drive train and must be taken into account by the
`unit 7 (for instance, by postponing gear shifting points to
`higher engine rpm levels).
`
`35
`
`BMW1020
`Page 9 of 11
`
`

`

`US 6,188,945 Bl
`
`7
`A particular operating state in the transmission can like(cid:173)
`wise affect the calculation of the transmission ratio (such as
`cold transmission fluid when the torque converter lock up is
`turned on; at excess transmission temperature, it is appro(cid:173)
`priate to shift engine rpm levels to ranges that increase the 5
`volumetric throughput of the oil pump of the transmission
`through the oil cooler). Other interventions in the engine
`torque, such as increasing it in order to compensate for the
`loss of torque by the air conditioning compressor or losses
`of efficiency in the transmission ( CVT: adjusting the trans- 10
`mission ratio dictates a greater pumping power), take place
`on the control level represented by blocks 8-11, unless they
`also have to be supported by other provisions in block 7.
`By means of the drive train control system of the
`invention, it is thus possible not only for the gear shifting 15
`behavior, when driving uphill and downhill or if perfor(cid:173)
`mance demands oriented to driving style and driving situ(cid:173)
`ation are made, but also the control of the entire drive train,
`including the drive sources, to be subjected to different
`criteria and adapted to them.
`For instance it may be appropriate and necessary, in
`critical situations and driving maneuvers, to adapt the cur(cid:173)
`rent transmission ratio (keep it unchanged) in a situation(cid:173)
`oriented way, specifically regardless of whatever general
`strategy has just been set. Such dynamic corrections are 25
`functionally combined, in the control concept of the
`invention, with the control of the engine ( one example is the
`coordinated lock up of a gear and activation of the engine
`overrunning shutoff).
`It is appropriate not yet to include engine-specific param- 30
`eters in block 12 (wheel torque calculation), because after
`all, in a hybrid drive, for instance, the choice of driving type
`is not yet fixed at this decision level. However, it is useful
`to include such conditions as traction conditions (winter
`driving, a gravel road) and above all in highly motorized 35
`vehicles preventively to reduce the sensitivity of the system
`somewhat (to generate less wheel torque with the accelerator
`pedal in the same position). In general, the conversion of the
`accelerator pedal position into a wheel torque can be done
`with a fuzzy system, which combines the multiple depen- 40
`dencies into a desired wheel torque.
`The advantages of the invention also reside in an inte(cid:173)
`grated wheel torque management, which processes the
`wheel torque as a negative value as well and that influences
`both drive sources and the units that slow down the vehicle. 45
`It is especially simple to couple it with brake systems that
`have electrical brake actuation ("brake by wire").
`In block 7, not only the transmission ratios and the
`respective desired engine torque but also the driving type
`and the individual operating points thereof are defined. Not 50
`only is a strictly wheel torque-oriented mode by driver
`specification possible, but by centralized specifications in
`terms of pollutant emissions, the real wheel torque can also
`be varied or limited. However, such interventions must be
`displayed to the driver through block 16 and must be done 55
`as much as possible without restrictions to drive mode
`selection.
`Blocks 2-7 and 12-16 may be accommodated in inde(cid:173)
`pendent physical units ( control units) or can be integrated
`with the units 8-11. This flexibility is yet another advantage 60
`of the invention.
`The data exchange among the individual control units is
`done in torque-based fashion. The term "torque-based" is
`understood as follows: If the