throbber
PROVISIONAL PATENT APPLICATION
`
`of
`
`ALEX J. SEVERINSKY
`
`for
`
`IMPROVEMENTS IN HYBRID VEHICLES
`
`Field of the Invention
`
`This application relates to improvements in hybrid vehicles,
`
`that is, vehicles in which both an internal combustion engine and
`one or more electric motors are provided to supply torque to the
`driving wheels of the vehicle.
`
`Background of the Invention
`
`This application discloses a number of improvements over and
`
`enhancements to the hybrid vehicles disclosed in the inventor's
`
`U.S. patent 5,343,970 (the
`
`"'970 patent"), which is incorporated
`
`herein by this reference. Where differences are not mentioned, it
`
`is to be understood that the specifics of the vehicle design shown
`
`in the '970 patent are applicable to the vehicles shown herein as
`
`well. Discussion of the '970 patent herein is not to be construed
`
`to limit the scope of its claims.
`
`5:
`'
`
`
`
`Generally speaking,
`
`the '970 patent discloses hybrid vehicles
`
`wherein a controllable torque transfer unit is provided capable of
`
`transferring torque between an internal combustion. engine,
`
`an
`
`20
`
`electric motor, and the drive wheels of the vehicle.
`
`The direction
`
`of torque transfer is controlled by a microprocessor responsive to
`
`the mode of operation of the vehicle, to provide highly efficient
`
`operation over a wide variety of operating conditions, and while
`
`providing good performance.
`
`25
`
`The flow of energy - either electrical energy stored in a
`
`substantial battery bank, or chemical energy stored as combustible
`
`fuel - is similarly controlled by the microprocessor.
`
`For example,
`
`Page 1 of 23
`Page 1 of 23
`
`FMC 1038
`FMC 1038
`
`

`

`in low—speed city driving,
`
`the electric motor provides all torque
`
`needed responsive to energy flowing from the battery.
`
`In high—
`
`speed highway driving, where the internal—combustion engine can be
`
`operated efficiently, it typically provides all torque; additional
`
`torque may be provided by the electric motor as needed for
`
`acceleration, hill—climbing, or passing.
`
`The electric motor is
`
`also used to start the internal-combustion engine,
`
`and can be
`
`operated as a generator by appropriate connection of its windings
`
`by a solid'state, microprocessor—controlled inverter.
`
`For example,
`
`when the state of charge of
`
`the battery bank is relatively
`
`depleted, e.g., after a lengthy period of battery-only operation in
`
`city traffic, the internal combustion engine is started and drives
`
`the motor at between 50 and 100% of its maximum torque output, for
`
`efficient charging of the battery bank. Similarly, during braking
`or hill descent,
`the kinetic energy of the vehicle can be turned
`
`into stored electrical energy by regenerative braking.
`
`The hybrid drive train shown in the '970 patent has many
`
`aspects and advantages with respect
`
`to the prior art which are
`
`retained by the present invention.
`
`For example, the electric drive
`
`motor
`
`is selected to be of relatively high power, specifically,
`
`equal to or greater than that of the internal combustion engine,
`
`and to have high torque output characteristics at low speeds; this
`
`allows the conventional multi-speed vehicle transmission to be
`
`eliminated.
`
`As compared to the prior art,
`
`the battery bank,
`
`motor/generator, and associated power circuitry are operated at
`
`relatively high voltage and relatively low current, reducing losses
`
`due to resistive heating and simplifying component selection and
`connection.
`
`Objects of the Invention
`
`It is an object of the present
`invention to provide further
`improvements over the hybrid vehicle shown in the '970 patent.
`It is a more specific object of
`the present
`invention to
`provide a hybrid drive system for vehicles that does not require
`the controllable torque-transfer unit shown in the '970 patent,
`
`2
`
`10
`
`
`
`25
`
`30
`
`35
`
`Page 2 of 23
`Page 2 of 23
`
`FMC 1038
`FMC 1038
`
`I
`
`

`

`while providing the functional advantages of the hybrid vehicle
`
`shown in the '970 patent.
`
`Other aspects of and improvements provided by the present
`
`invention will appear below.
`
`Summary of the Invention
`
`According to the present invention,
`
`the controllable torque-
`
`transfer unit shown in the '970 patent is eliminated by replacing
`
`the single electric motor shown therein by two separate motors,
`
`10
`
`both operable as generators when appropriate,
`
`connected by a
`
`functionally-conventional clutch or mechanical interlock operated
`
`by the microprocessor responsive to the vehicle's mode of operation
`
`and to input commands provided by the operator of the vehicle.
`
`As
`
`in the '970 patent, an internal combustion engine is provided,
`
` vehicle when needed. This second motor is connected directly to
`
`sized to provide sufficient torque for the maximum cruising speed
`
`desired, and is used for battery charging as needed.
`
`A relatively
`
`high-powered "traction" motor is connected directly to the output
`
`shaft of the vehicle; the traction motor provides torque to propel
`
`the vehicle in low—speed situations, and provides additional torque
`
`when required, e.g., for acceleration, passing, or hill—climbing
`during high-speed driving.
`A relatively low-powered starting motor
`is also provided, and can be used to provide torque propelling the
`
`the internal combustion engine for starting the engine. Unlike a
`
`25
`
`conventional starter motor, which rotates an internal combustion
`
`engine at low speed for starting, necessitating provision of a rich
`
`the starter motor according to the
`fuel/air mixture for starting,
`invention spins the engine at relatively high speeds for starting;
`this allows starting the engine with a near-stoichiometric mixture,
`significantly reducing undesirable emissions and improving fuel
`
`30
`
`economy at start-up.
`
`As noted,
`the two motors are separated by a functionally-
`conventional clutch, that is, a clutch which either joins the two
`
`motors together for rotation at the same speed, or separates them
`
`35
`
`completely.
`
`As the motor shafts can be controlled to rotate at
`
`3
`
`Page 3 of 23
`Page 3 of 23
`
`FMC 1038
`FMC 1038
`
`

`

`essentially the same speed when the clutch is engaged,
`
`the clutch
`
`need not allow for slip therebetween. Accordingly,
`a friction
`clutch, as normally provided for road vehicles,
`is not required,
`and a less-expensive simple mechanical interlock can alternatively
`be employed.
`Engagement of
`the clutch is controlled by the
`microprocessor, e.g., by a hydraulic actuator, responsive to the
`state of operation of the vehicle and the current operator input.
`For example, during low—speed operation,
`the clutch will be
`disengaged, so that the traction motor is disconnected from the
`engine;
`the vehicle is then operated as a simple electric car,
`i.e., power is drawn from the battery bank and supplied to the
`traction motor.
`If the batteries become depleted,
`the starter
`motor is used to start the internal combustion engine, which is
`then runs at relatively high torque output (e.g.,
`between about 50
`
`- 100% of its maximum torque), for efficient use of fuel, and the
`starting motor is operated as a high-output generator to recharge
`the battery bank.
`If the operator calls for more power
`than
`available from the traction motor alone, e.g.,
`in accelerating onto
`a highway,
`the starter motor starts the internal combustion engine,
`and the clutch is engaged, so that the engine and starter motor can
`provide additional torque. The engine is sized so that it provides
`sufficient power
`to maintain a suitable highway cruising speed
`while being operated in a
`torque range providing good fuel
`efficiency; if additional power is then needed, e.g.,
`for hill-
`climbing or passing,
`the traction and/or starter motors can be
`
`Both motors can be operated as generators,
`engaged as needed.
`e.g.,
`to transform the vehicle's kinetic energy ito electrical
`power during descent or deceleration.
`
`5
`
`10
`
`
`
`25
`
`In each of these aspects of the operation of the vehicle, and
`as
`in the '970 patent,
`the operator of
`the vehicle need not
`consider the hybrid nature of the vehicle during its operation, but
`simply provides control inputs by operation of the accelerator and
`brake pedals.
`The microprocessor determines the proper state of
`operation of
`the vehicle based on these and other
`inputs and
`controls
`the various
`components
`of
`the hybrid drive train
`
`30
`
`35
`
`4
`
`Page 4 of 23
`Page 4 of 23
`
`FMC 1038
`FMC 1038
`
`

`

`accordingly.
`
`In the preferred embodiment,
`
`the engine and the two motors all
`
`the same speed when the clutch is engaged, avoiding
`rotate at
`intermediate gear trains or
`like mechanical components and the
`
`5
`
`attendant cost, complexity, weight, audible noise, and frictional
`
`It is nonetheless within the scope
`losses occasioned by their use.
`of the invention to operate one or more of these components at
`differing rotational speeds; for example,
`the starter motor might
`drive the engine through a small pinion geared to a relatively
`large toothed flywheel, as conventional. Similarly, it might be
`desirable to provide the traction motor as a relatively high-speed
`unit, driving the road wheels through a belt or gear reduction
`unit. However,
`in all cases,
`the rotational speeds of
`the two
`
`motors and the engine, and of
`
`the road wheels, are fixed with
`
`respect to one another;
`
`no multi-speed transmissions between the
`
`motors and engine and the road wheels are required by the hybrid
`power train of the invention.
`
`other improvements provided according to the invention include
`
`providing the batteries in two series-connected battery banks, with
`the vehicle chassis connected to the batteries at a central point,
`between the banks. This "center—point-chassis" connection reduces
`
`the voltage between various circuit components and the vehicle
`
`chassis by half, significantly reducing the electrical insulation
`
`issues as Iheat-sinking' of power
`required, and simplifying such.
`semiconductors used in the inverter circuitry.
`Providing dual
`battery banks and dual electric motors, as above, also provides a
`degree of redundancy, permitting certain component failures without
`loss of vehicle function.
`
`In the preferred embodiment, both the traction and starting
`motors are AC induction motors of
`four or more poles and the
`accompanying power circuitry provides current of three or more,
`preferably five, phases, allowing the vehicle to function even
`
`after failure of one or more components.
`
`During substantially steady-state operation, e.g., during
`highway cruising,
`the control system operates the engine at varying
`
`5
`
`10
`
`
`
`25
`
`30
`
`35
`
`Page 5 of 23
`Page 5 of 23
`
`FMC 1038
`FMC 1038
`
`

`

`torque output levels, responsive to the operator's commands.
`
`The
`
`range of permissible engine torque output levels is constrained to
`
`the range in which the engine provides good fuel efficiency. Where
`
`the vehicle's torque requirements exceed.
`
`the engine's maximum
`
`5
`
`efficient torque output, e.g., during passing or hill-climbing, one
`
`or both of the electric motors are energized to provide additional
`
`torque; where the vehicle's torque requirements are less than the
`
`minimum torque efficiently provided by the engine, e.g., during
`
`coasting, on downhills or during braking,
`
`the excess engine torque
`
`10
`
`is used to charge the batteries. Regenerative charging may be
`
`performed simultaneously,
`
`as
`
`torque from the engine and the
`
`vehicle's kinetic energy both drive either or both motors
`
`in
`
`generator mode.
`
`The rate of change of torque output by the engine
`
`may be controlled in accordance
`
`vdth the batteries' state of
`
`charge.
`
`Brief Description of the Drawings
`
`The invention will be better understood if reference is made
`
` to the accompanying drawings,
` the drive system of the invention,
`
`in which:
`
`Fig.
`
`1 shows a schematic diagram of the principal components
`
`of the hybrid vehicle drive system according to the invention;
`
`Fig.
`
`2 shows a block diagram of the principal components of
`
`illustrating various control
`
`signals provided;
`
`25
`
`Fig.
`
`3 shows a partial schematic diagram of the battery bank,
`
`inverter, and motor circuitry;
`
`Fig.
`
`4 is a diagram illustrating a typical control strategy
`
`employed during highway driving; and
`
`Fig.
`
`5 is a generally similar diagram illustrating a typical
`
`30
`
`control strategy employed during low-speed city driving.
`
`Description of the Preferred Embodiments
`
`As
`
`indicated above,
`
`this application discloses certain
`
`modifications,
`
`improvements,
`
`and
`
`enhancements
`
`of
`
`the hybrid
`
`35
`
`vehicles shown in the inventor's U.S. patent 5,343,970; where not
`
`6
`
`Page 6 of 23
`Page 6 of 23
`
`FMC 1038
`FMC 1038
`
`

`

`otherwise stated,
`
`the design of
`
`the vehicle of
`
`the present
`
`invention is similar to that shown in the '970 patent. Components
`
`commonly numbered in this application and the '970 patent are
`
`functionally similar in the corresponding systems, with detail
`
`5
`
`differences as noted. The
`
`advantages of the system shown in the
`
`'970 patent with respect to the prior art are provided by that of
`
`the present invention, with further improvements provided by the
`
`latter, as detailed herein.
`
`As shown in the '970 patent with reference to Figs.
`
`1 and 2
`
`10
`
`thereof, typical modern automobiles operate at very low efficiency,
`
`due principally to the fact that internal combustion engines are
`
`very inefficient except when operating at near peak torque output;
`
`this condition is only rarely met.
`
`(The same is true, to greater
`
`or
`
`lesser degree, of other
`
`road vehicles powered by internal
`
`combustion engines.)
`
`According to an important aspect of
`
`the
`
`invention of the '970 patent, substantially improved efficiency is
`
`afforded. by operating’
`
`the internal combustion engine only' at
`
`relatively high torque output levels,
`
`typically at least 35% and
`
`preferably at least 50% of peak torque. When the vehicle operating
`
`conditions require torque of this appoximate magnitude,
`
`the engine
`
`is used to propel the vehicle; when less torque is required,
`
`an
`
`electric motor powered by electrical energy stored in a substantial
`
`battery bank drives the vehicle; when more power is required than
`
`provided by either the engine or
`
`the motor, both are operated
`
`
`
`25
`
`simultaneously.
`
`The same advantages are provided by the system of
`
`the present invention, with further improvements and enhancements
`
`described in detail below.
`
`In the system of the '970 patent,
`
`torque from either or both
`
`the engine and motor is transferred to the drive wheels of the
`
`30
`
`vehicle by a controllable torque-transfer unit.
`
`This unit also
`
`allows torque to be transferred between the motor and engine, for
`
`starting the engine,
`
`and between the wheels
`
`and motor,
`
`for
`
`regenerative battery charging during deceleration of the vehicle.
`
`This unit, while entirely practical, comprises gears for power
`
`35
`
`transfer, which, are inevitably' a source of audible noise and
`
`7
`
`Page 7 of 23
`Page 7 of 23
`
`FMC 1038
`FMC 1038
`
`

`

`frictional
`
`losses.
`
`According to the present
`
`invention,
`
`the
`
`controllable torque—transfer unit
`
`is eliminated.
`
`Instead,
`
`two
`
`electric motors are provided,
`
`each separately controlled by a
`
`microprocessor controller responsive to operator
`
`commands
`
`and
`
`5
`
`sensed operating conditions.
`
`As
`
`shown in Fig.
`
`1 of the present application, a traction
`
`motor 25 is connected directly to the vehicle differential 32, and
`
`thence to the road wheels 34.
`
`A starting motor 21 is connected
`
`directly to the internal combustion engine 40.
`
`The motors 21 and
`
`10
`
`25 are functional as motors or generators by appropriate operation
`
`of corresponding inverter/charger units 23 and 27, respectively.
`
`The two motors are controllably connected for torque transfer by a
`
`clutch 51, conventional
`
`in the sense that it is either engaged,
`
`wherein the shafts of motors 21 and 25 are connected and rotate
`
`together, or disengaged, wherein the shafts may rotate separately.
`
`(The respective positions of motor 21 and engine 40 with respect to
`
`clutch 51 could be reversed as compared to their positions in Figs.
`
` 1 and 2 without affecting the function of the system, although as
` the system,
`
`engine 40 would then require torque transmitting connection at both
`
`ends of its crankshaft,
`
`some additional complexity would result.)
`
`The clutch 51 is operated by microprocessor 48, e.g.,
`
`through a
`
`known hydraulic actuator 53,
`
`together with the other components of
`
`in accordance with the operational state of the vehicle
`
`and the operator's input commands.
`
`25
`
`As in the case of the hybrid vehicle system shown in the '970
`
`patent, and as indicated above,
`
`the vehicle of the invention is
`
`operated in different modes depending on the torque required,
`
`the
`
`state of charge of
`
`the batteries,
`
`and other variables.
`
`For
`
`example, during low—speed operation, such as in city traffic, the
`
`30
`
`vehicle is operated as a simple electric car, where all power is
`
`provided to road wheels 34 by traction motor 25; engine 40 is run
`
`only
`
`as
`
`needed
`
`to charge battery bank
`
`22.
`
`Under
`
`these
`
`circumstances,
`
`the charging current is provided by starting motor
`
`21,
`
`operated
`
`as
`
`a generator
`
`by
`
`appropriate operation of
`
`35
`
`inverter/charger 23. Accordingly, clutch 51 is disengaged, so that
`
`8
`
`Page 8 of 23
`Page 8 of 23
`
`FMC 1038
`FMC 1038
`
`

`

`the road speed of the vehicle is independent of the speed of engine
`
`40; engine 40 can thus be operated at high torque,
`
`for
`
`fuel
`
`efficiency.
`
`As shown in Fig. 2, shaft encoders 18 and 19 may be mounted on
`
`5
`
`the shafts 15 and 16 of starting motor 21 and traction motor 25,
`
`respectively,
`
`to provide signals to microprocessor controller 48
`
`indicative of the relative rotational speeds of the shafts, and
`
`their respective rotational positions.
`
`Such shaft encoders are
`
`well—known and commercially available. Alternatively,
`
`signals
`
`10
`
`indicative of the rotational speeds of the shafts may be derived
`
`from the inverter control signals,
`
`in accordance with well-known
`
`principles of control of "sensorless" motor drives
`
`(see,
`
`for
`
`example, Bose, "Power Electronics and Variable Frequency Drives",
`
`IEEE, 1996). However, provision of encoders 18 and 19 will allow
`
`better low—speed torque characteristics of motor 21 and 25, and
`
`thus reduction in cost.
`
`In either embodiment,
`
`the microprocessor controller 48 is
`
`provided with signals indicative of the rotational speeds of shafts
`
`15 and 16, and controls operation of engine 40, motor 21, and motor
`
`25
`
`as necessary to ensure that
`
`the shafts are rotating at
`
`substantially the same speed before engaging clutch 51; therefore,
`
`clutch 51 need not be an ordinary automotive friction clutch (as
`
`illustrated schematically in Fig. 1), provided to allow slipping
`
`before the shafts are fully engaged. Alternatively, clutch 51 may
`
`
`
`25
`
`be a simple self-aligning nmchanical
`
`interlock (as illustrated
`
`schematically in Fig. 2), wherein positive mechanical connection is
`
`made between the shafts
`
`15
`
`and 16 upon engagement;
`
`such a
`
`interlock is much simpler and less expensive than a
`mechanical
`friction clutch.
`
`30
`
`Additional signals input to microprocessor controller 48, as
`
`shown
`
`in Fig.
`
`2,
`
`include operator
`
`input
`
`commands,
`
`typically
`
`acceleration, direction,
`
`and deceleration commands. Position-
`
`sensing encoders 71 and 72 (which could be configured as rheostats,
`
`Hall-effect
`
`sensors,
`
`or
`
`otherwise)
`
`provide
`
`signals
`
`to
`
`35
`
`microprocessor controller 48 over lines 67 and 68 upon motion of
`
`9
`
`Page 9 of 23
`Page 9 of 23
`
`FMC 1038
`FMC 1038
`
`

`

`accelerator and brake pedals 69 and 70 (Fig. 1) respectively. The
`
`microprocessor monitors the rate at which the operator depresses
`
`pedals 69 and 70 as well as the degree to which pedals 69 and 70
`
`are depressed. The microprocessor uses this information to make
`
`5
`
`decisions concerning the proper operation of the vehicle according
`
`to the invention.
`
`For example,
`
`suppose the vehicle has been operated in city
`
`traffic for
`
`some
`
`time,
`
`that
`
`is,
`
`under battery power only.
`
`Typically the operator will only depress the accelerator slightly
`
`10
`
`to drive in traffic.
`
`If the operator then depresses accelerator
`
`pedal 69 significantly farther than he or she had, for example,
`
`the
`
`prior few times acceleration was required, this may be taken as an
`
`indication that more torque will be required, and so starting motor
`
`21 will be used to start engine 40.
`
`If the operator does not
`
`depress pedal 69 rapidly, a heater 63 will be used to preheat a
`
`catalytic converter 64 provided in the engine exhaust system 62, so
`
`that any fuel that is not combusted during starting of the engine
`
`40 will be catalytically combusted; however,
`
`if the operator
`
`depresses the pedal 69 rapidly,
`
`indicating an immediate need for
`
`full acceleration,
`
`the preheating step may be omitted. Similarly,
`
`if the operator depresses the brake pedal 70 relatively gently, all
`
`braking may be provided by regenerative charging of the batteries;
`
`if the operator instead presses rapidly on brake pedal 70, both
`
`mechanical and regenerative braking will be provided. Mechanical
`
`
`
`25
`
`braking is also provided on long downhills when the batteries are
`
`fully charged.
`
`In addition to engine and starting motor speed and traction
`
`motor speed, monitored by shaft encoders 18 and 19 as discussed
`
`above,
`
`battery voltage, battery charge
`
`level,
`
`and
`
`ambient
`
`30
`
`temperature are also either monitored directly or derived from
`
`monitored variables.
`
`In response to these inputs, and the operator
`
`inputs, microprocessor controller 48 operates a control program and
`
`provides output control signals to engine 40, by commands provided
`
`to its electronic fuel
`
`injection unit
`
`(EFI)
`
`56 and electronic
`
`35
`
`engine management system (EEM) 55, and to starting motor 21, clutch
`
`10
`
`Page 10 of 23
`Page 10 of 23
`
`FMC 1038
`FMC 1038
`
`

`

`51, traction motor 25,
`
`inverter/charger units 23 and 27, and other
`
`components.
`
`As
`
`indicated,
`
`the control
`
`signals provided to
`
`inverter/chargers 23 and 27 allow control of the current
`
`to be
`
`provided, of direction of rotation of
`
`the motor 25, allowing
`
`5
`
`reversing of the vehicle, as well as control of operation of the
`
`motors 21 and 25 in motor or generator mode.
`
`Inverter/chargers 23
`
`and 27 are separately controlled to allow independent operation of
`
`motors 21 and 25, although the duplicate control lines required are
`
`not illustrated in Fig. 2.
`
`Inverter/charger operation is discussed
`
`10
`
`further below in connection with Fig. 3.
`
`other elements of the system as illustrated in Figs. 1 and 2
`
`are generally as discussed in the '970 patent,
`
`including supply of
`
`fuel 36 from tank 38, air filter 60, and throttle 61.
`
`As
`
`in the '970 patent, engine 40 is sized so that its full
`
`torque output is adequate to drive the vehicle at a desired top
`
`speed, so that the engine is operated at high efficiency during
`
`highway cruising. During highway cruising, therefore, clutch 51 is
`
` recharging of battery bank
`
`engaged; engine 40 then drives road wheels
`
`of motors
`
`21
`
`and 25.
`
`If extra power
`
`34 through the shafts
`
`is needed, e.g.,
`
`for
`
`acceleration or hill-climbing, either or both of motors 21 and 25
`
`can be powered. Similarly, under deceleration, either or both of
`
`motors 21 and 25 are operated as generators, proving regenerative
`
`22.
`
`Fig.
`
`4,
`
`discussed below,
`
`illustrates operation in this mode in further detail.
`
`25
`
`When the microprocessor controller 48 detects a continued
`
`operator
`requirement
`for
`additional
`power,
`such
`as during
`transition from slow-speed to highway operation, or by measuring
`
`the rate at which the operator depresses accelerator pedal 70,
`
`engine 40 is started using starter motor 21 and brought up to speed
`
`30
`
`before clutch 51 is engaged,
`
`to ensure a smooth transition.
`
`As
`
`cruising speed is reached, power
`
`to traction motor 25
`
`(and to
`
`starter motor 21,
`
`if also used to accelerate the vehicle)
`
`is
`
`gradually reduced. Provision of the clutch 51 and separate starter
`
`motor 21, as compared to using the single traction motor to start
`
`35
`
`engine 40 while simultaneously accelerating the vehicle as in the
`
`11
`
`Page 11 of 23
`Page 11 of 23
`
`FMC 1038
`FMC 1038
`
`

`

`'970 patent, provides much simpler operation.
`
`In a particularly
`
`preferred embodiment, both motors 21 and 25 and clutch 51 may be
`
`provided in a single sealed housing, possibly bathed in oil for
`
`cooling and protection from dust and the like. Connection of the
`
`5
`
`engine 40 to the drive wheels through motors 21 and 25 also serves
`
`to damp out any vibration of engine 40.
`
`Provision of the clutch 51 and separate starter motor 21 also
`
`allows another important improvement to be provided according to
`
`the present
`
`invention, namely starting engine 40 at high speed,
`
`10
`
`e.g., between about 500 and 2000 rpm,
`
`as compared to the 60 - 200
`
`rpm starts conventionally' provided.
`
`High-rpm starting allows
`
`elimination of
`
`the usual necessity of providing a
`
`fuel-rich
`
`air/fuel mixture to start engine 40, reducing emission of unburned
`
`fuel and improving fuel economy at start-up. More specifically,
`
`in
`
`conventional
`
`low-rpm starts, a rich mixture must be provided to
`
` to a conventional engine at starting is immediately exhausted
`
`ensure that some fraction of the fuel is in the vapor phase;
`
`only
`
`fuel
`
`in the vapor phase can be ignited by a spark.
`
`At high
`
`starting speeds,
`
`turbulence in the combustion chamber is sufficient
`
`to ensure the presence of vapor,
`
`so that a near-stoichiometric
`
`mixture can be provided to engine 40 during the starting phase. As
`
`noted,
`
`the avoidance of rich mixtures at starting significantly
`
`reduces emission of unburned fuel - since most of the fuel provided
`
`unburnt - and provides some improvement in fuel efficiency.
`
`25
`
`More specifically,
`
`in normal
`
`low-rpm starting,
`
`a fuel/air
`
`mixture comprising on the order of 6 to 7 times the stoichiometric
`
`amount of fuel is provided; most of the excess fuel is immediately
`
`emitted unburned. According to the invention a mixture typically
`
`including only 1.2 times the stoichiometric amount of fuel
`
`is
`
`30
`
`provided for starting, greatly reducing these emissions. As noted
`
`above, whenever possible - that is, whenever the engine is started
`
`except when immediate full torque is required by the operator - a
`
`catalytic converter 64 is preheated before starting the engine,
`
`to
`
`prevent even this relatively small emission of unburned fuel.
`
`35
`
`Thus,
`
`the primary consideration in selecting the torque of
`
`12
`
`Page 12 of 23
`Page 12 of 23
`
`FMC 1038
`FMC 1038
`
`

`

`starting motor 21 is that it be capable of rotating the engine 40
`
`at about 500 - 2000 rpm for starting;
`
`the main consideration in
`
`specification of
`
`the torque of engine 40
`
`is that it provide
`
`sufficient power for highway cruising at high efficiency,
`
`i.e.,
`
`5
`
`that
`
`its maximum power output be approximately equal
`
`to that
`
`required to naintain maximum vehicle speed;
`
`and the principal
`
`consideration defining the power required of the traction motor 25
`
`is
`
`that
`
`it
`
`be
`
`sufficiently powerful
`
`to provide
`
`adequate
`
`acceleration in combination with the engine 40 and starting motor
`
`10
`
`21. Stated differently,
`
`the total power available provided by all
`
`of these torque—producing components should be at least equal to
`
`and preferably exceeds the peak power provided by the internal
`
`combustion engines of conventional vehicles of similar intended
`
`use, both as measured at the wheels. Moreover, as set forth in the
`
`'970 patent,
`
`the total torque provided by motors 21 and 25 should
`
`be at least equal to that produced by engine 40.
`
` relatively large fraction of the total energy required,
`
`At
`
`the same time, motors 21 and 25 are also sized to be
`
`capable of recovering 65 - 90% of the vehicle's kinetic energy when
`
`operated as generators
`
`in the regenerative braking mode.
`
`A
`
`particularly high fraction of the vehicle's kinetic energy can be
`
`recovered during low-speed operation; as compared to high-speed
`
`operation, where air resistance and road friction consume
`
`a
`
`in low
`
`speed operation much energy is lost by conventional vehicles as
`
`25
`
`heat released during braking.
`
`Given the above considerations,
`
`the following are typical
`
`power specifications for the engine 40, starting motor 21 and
`
`traction motor 25 of
`
`a 3000 pound vehicle having performance
`
`approximately equivalent to that of a "mid-size" sedan of United
`
`30
`
`States manufacture;
`
`it
`
`should be understood that
`
`in these
`
`specifications,
`
`reference is made to rated peak power of
`
`the
`
`various components,
`
`that
`
`is,
`
`the components are rated at
`
`the
`
`combination of torque and rpm yielding the maximum torque produced
`
`per unit time.
`
`35
`
`Engine 40: 40 to 50 horsepower at 6000 rpm
`
`13
`
`Page 13 of 23
`Page 13 of 23
`
`FMC 1038
`FMC 1038
`
`

`

`Starting motor 21: 10 — 15 horsepower at approximately 1500
`
`rpm and higher speeds
`
`Traction motor 25: 50 - 60 horsepower from 1500 to 6000 rpm.
`
`The same starting motor would be satisfactory for a larger,
`
`5
`
`4000 pound sedan, but the engine would typically provide 70 - 90
`
`horsepower at 6000 rpm and the traction motor 75 - 100 horsepower.
`
`In both cases,
`
`the total power available from the electric
`
`motors should equal,
`
`and preferably exceeds,
`
`the maximum power
`
`available from the engine.
`
`10
`
`These components would provide acceleration much superior to
`
`that of
`
`typical similarly~sized automobiles of United States
`
`manufacture.
`
`It will be apparent that these specifications may
`
`vary over relatively wide ranges depending on the intended use of
`
`the vehicle of the invention, and should not be construed to limit
`
`the scope of the invention.
`
` typically 1500 - 2000 rpm, and should produce constant power at
`
`As
`
`indicated above,
`
`in the preferred embodiment, both the
`
`starting and traction motors are AC induction motors, although
`
`other
`
`types may also be
`
`employed.
`
`These motors,
`
`and the
`
`inverter/chargers driving them, should be chosen and operated such
`
`that the motors have torque output characteristics varying as a
`
`function of rpm as illustrated in Fig. 14 of the '970 patent; that
`
`is,
`
`the motors should produce constant torque up to a base speed,
`
`higher speeds.
`
`The ratio of the base to maximum speed can vary
`
`25
`
`between about 3 to 1 and about 6 to 1.
`
`By comparison,
`
`the series-
`
`wound DC nmtors conventionally used as engine starting motors
`
`provide very high torque, but only at very low speeds; their torque
`
`output drops precipitously at higher speeds.
`
`Such conventional
`
`starter motors would be unsatisfactory in the present system.
`
`30
`
`As noted, each of the torque-producing components (that is,
`
`engine 40 and starting and traction motors 21 and 25) preferably
`
`operate at
`
`the same speed,
`
`so that no gear-reduction units or
`
`similar heavy and power-dissipating intermediate components are
`
`needed.
`
`A maximum speed of approximately 6000 rpm is preferred, as
`
`35
`
`this represents a good compromise between cost, weight, and size of
`
`14
`
`Page 14 of 23
`Page 14 of 23
`
`FMC 1038
`FMC 1038
`
`

`

`the key components.
`
`However, as noted above, it is within the
`
`scope of
`
`the invention to operate the starter motor,
`
`traction
`
`motor, and engine at differing rotational speeds, and connect these
`
`torque-producing components to one another and to the road wheels
`
`5
`
`by fixed-ratio gear or belt drives.
`
`In each case, no variable
`
`speed transmission between the torque-producing components and the
`
`road wheels is provided.
`
`The speed of rotation of the torque—
`
`producing components is reduced to a suitable speed for the road
`
`wheels by gear or belt drive reduction in (or incorporated with)
`
`10
`
`differential 32;
`
`the reduction ratio can be chosen to provide
`
`substantially any desired top speed.
`
`As discussed above, it is preferred that motors 21 and 25 have
`
`more than two poles, and be operated by current applied over more
`
`than three phases, so that failure of some components - such as the
`
`power
`
`semiconductors used in the inverter/charger units,
`
`as
`
`discussed below — can be tolerated without total failure of the
`
`vehicle. It is also desired that the battery bank be divided into
`
`two, with the vehicle chassis connected between them, halving the
`
`voltage between given components and the vehicle chassis, and thus
`
`simplifying their construction,
`
`insulation, and connection. Fig.
`
`3 shows a partial schematic diagram of a circuit providing these
`
`attributes.
`
`
` The functions of the inverter/chargers 23 and 27
`
`(separate
`
`inverter/chargers being required to allow independent operation of
`
`25
`
`motors 21 and 25)
`
`include control of motors 21 and 25 to operate as
`
`motors or as generators; operation of traction motor 25 in the
`
`opposite direction for reversing the vehicle; conversion of DC
`
`stored by the battery bank to AC
`
`for motor operation;
`
`and
`
`conversion of AC induced in the motors when operated as generators
`
`30
`
`to DC for battery charging. Essentially similar functions were
`
`provided by the solid-state switching AC/DC converter 44 in the
`
`'970 patent; where not specified to the contrary,
`
`the discussion
`
`there

This document is available on Docket Alarm but you must sign up to view it.


Or .

Accessing this document will incur an additional charge of $.

After purchase, you can access this document again without charge.

Accept $ Charge
throbber

Still Working On It

This document is taking longer than usual to download. This can happen if we need to contact the court directly to obtain the document and their servers are running slowly.

Give it another minute or two to complete, and then try the refresh button.

throbber

A few More Minutes ... Still Working

It can take up to 5 minutes for us to download a document if the court servers are running slowly.

Thank you for your continued patience.

This document could not be displayed.

We could not find this document within its docket. Please go back to the docket page and check the link. If that does not work, go back to the docket and refresh it to pull the newest information.

Your account does not support viewing this document.

You need a Paid Account to view this document. Click here to change your account type.

Your account does not support viewing this document.

Set your membership status to view this document.

With a Docket Alarm membership, you'll get a whole lot more, including:

  • Up-to-date information for this case.
  • Email alerts whenever there is an update.
  • Full text search for other cases.
  • Get email alerts whenever a new case matches your search.

Become a Member

One Moment Please

The filing “” is large (MB) and is being downloaded.

Please refresh this page in a few minutes to see if the filing has been downloaded. The filing will also be emailed to you when the download completes.

Your document is on its way!

If you do not receive the document in five minutes, contact support at support@docketalarm.com.

Sealed Document

We are unable to display this document, it may be under a court ordered seal.

If you have proper credentials to access the file, you may proceed directly to the court's system using your government issued username and password.


Access Government Site

We are redirecting you
to a mobile optimized page.





Document Unreadable or Corrupt

Refresh this Document
Go to the Docket

We are unable to display this document.

Refresh this Document
Go to the Docket