Prime-mover dynamo plants – Electric control – Engine control
Reexamination Certificate
2000-01-18
2002-04-23
Enad, Elvin (Department: 2834)
Prime-mover dynamo plants
Electric control
Engine control
C290S031000, C290S032000, C290S04000F, C290S04000F, C290S04000F, C290S04000F
Reexamination Certificate
active
06376927
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to hybrid electric vehicles and more particularly to drive systems and fuel controllers for such systems.
2. Description of the Prior Art
U.S. Pat. No. 5,789,823 has an engine and/or the electric motor operated to power the vehicle. In order to provide for a desired control of power, a one-way clutch is connected between a lock-up clutch and a start clutch. The arrangement is operative to provide a high torque input from the electric motor through the torque converter turbine to the engine. Once the engine starts, the start clutch is disengaged and the engine drive is directly connected through the one-way clutch that is operative to lock in the direct drive direction so as to power the torque converter impeller or pump. Once full power is transmitted through the torque converter to the transmission, the lock-up clutch is operated to produce a 1:1 drive to the transmission in bypassing relation with the torque converter. In this configuration the one-way clutch is locked up in the drive direction during initial torque converter operation and is operative to free wheel in the drive direction when the electric drive rotor is rotating faster than the engine speed so as to permit overrunning or free-wheeling between the engine and the rotor of an electric motor. Hence, the location of the one-way clutch and its operation is predicated upon an arrangement in which the stator of the electric motor is directly connected to the input housing of the torque converter for propelling the vehicle during various modes of highway operation. There is no provision for lock-up by the one-way clutch during vehicle coasting or during regenerative braking.
While suitable for its intended purpose the arrangement of the one-way clutch in the torque converter of the '823 patent does not provide for a continuous free-wheel connection between the engine and the impeller or pump of a torque converter in the drive direction and it is not operative to lock upon overdrive from the transmission to the engine during vehicle coasting.
One example operating characteristic of certain prior art torque converters including the combination shown in the '823 patent is that in operating modes in which the transmission selector is in a forward drive and the accelerator and brake are operated such that the vehicle is coasting down in speed and fuel flow to the engine is reduced to idle speed requirements, the engine can stall or its speed can fall off or droop. In such cases the vehicle driver may feel the pull of the engine when it is restarted in the case of stall or when it is operated to pull back from the drooped speed to the coasting speed of the vehicle as manifested by the vehicle wheels back driving the transmission through the output shaft of the vehicle drive system. Furthermore, advantages of regenerative braking and charging of a battery pack are lost if the engine must be restarted.
Other hybrid electric motor and internal combustion engine drive systems in a hybrid electric vehicle (HEV)are shown in U.S. Pat. Nos. 5,637,987 and 5,698,905. The '987 system includes an energy management control that selects either gas engine or electric motor drive depending upon the vehicle drive mode. The control for the '987 patent does not control the HEV by sensing vehicle speed in a brake start speed range; a hysteresis speed range and a “regen-able” speed range by use of a brake pedal position and pressure sensing sequence. The term “regen-able” is coined to indicate that regenerative braking is possible. Additionally the '987 patent requires a gear set interposed between an engine and a transmission to manage the energy provided to drive the vehicle. The '905 system includes a gas engine but it is used to power a generator for producing a source of electric current for driving an electric motor that constitutes the drive for the vehicle. Neither system provides for an aggressive management of fuel flow to a gas engine during vehicle coasting operations in order to improve total fuel consumption. Furthermore, neither system discloses or suggests that the internal combustion engine be directly coupled to a transmission drive that is operative to supply primary power to a wheeled vehicle above a predetermined vehicle speed.
Additionally, the prior art systems do not provide a method for controlling fuel flow in a system that is configured to prevent engine stall so as to avoid the need for electric motor restart of an engine following a coasting mode of forward speed operation when the engine speed falls below a selected drop-to-neutral speed.
Furthermore, the prior art systems do not provide an internal combustion engine and electric motor combination that is normally coupled in parallel driving relationship to a drive transmission of a wheeled vehicle and wherein the electric motor can be used to start the engine and can be conditioned in response to brake pedal pressure to cause a proportional regenerative braking for charging a battery pack that can be used when the vehicle is stopped to operate the electric motor for starting the internal combustion engine.
SUMMARY OF THE INVENTION
The present invention includes a hybrid-electric vehicle (HEV) that has an internal combustion engine connected to drive a multi-speed automatic transmission that can if desired include a torque converter.
Additionally the HEV includes an electric machine having a rotor connected to the crankshaft of the engine and a stator and a controller for selectively controlling the electric machine to serve as an electric starter or as a generator for regenerative braking during vehicle drive so as to charge an associated battery pack. A fuel controller is provided that is operative in response to vehicle braking and further is operative to respond to vehicle speeds in different ranges to improve fuel consumption characteristics of the vehicle.
The advantage of such a drive arrangement is that a fuel control can be provided that will entirely cut off fuel flow during vehicle decelerations and stops. The integration of an electric motor directly connected to the crankshaft of the internal combustion engine allow the shut off of fuel and restart of the gas engine to be conducted virtually transparent to the driver.
The control of the gas engine and the electric motor is according to routines that operated in conjunction with the usual operation of an engine driven automatic transmission system for driving the wheels of a vehicle. In such systems the engine is driven by an electric motor starter and fuel is supplied during an engine startup mode. The transmission is placed in a drive mode and the vehicle is accelerated by depressing an accelerator pedal for supplying more fuel and air to the engine. When the vehicle is up to speed the torque converter lock-up clutch is applied and the transmission is, for example, in a forward speed selection position such that the vehicle cruises under the power of the gasoline engine and if desired, a portion of the cruise power can be supplied by the electric motor (especially at lower startup speeds).
In such systems, when the accelerator pedal is released, the fuel can be cut depending on vehicle speed and gear setting. Above a prescribed vehicle speed, if the torque converter clutch is locked or if a reverse locking one-way clutch is operable to lock the turbine and impeller of a torque converter as set-forth in copending U.S. Ser. No. 09/483,987, office file H-204481, the electric motor can be controlled to deliver regenerative braking during decelerations to recharge a battery pack.
Under one control routine, when the brake pedal is depressed a brake sensor is operative to produce a signal that is processed by a microprocessor to maintain the fuel fully cut-off for the entire deceleration of the vehicle while in the regen-able speed range of operation.
In a lower speed range of vehicle speeds in the brake-start range of operation, if the brake pedal is released during deceleration, the engine can be r
Downs Robert Charles
Hoang Tony T.
Tamai Goro
Enad Elvin
Saturn Corporation
Simon Anthony Luke
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