Interrelated power delivery controls – including engine control – Plural engines – Electric engine
Reexamination Certificate
2000-01-18
2001-07-03
Wright, Dirk (Department: 3681)
Interrelated power delivery controls, including engine control
Plural engines
Electric engine
Reexamination Certificate
active
06254507
ABSTRACT:
TECHNICAL FIELD
This invention relates to torque converters and more particularly to torque converters for use in parallel hybrid engine applications to prevent engine stall due to overdrive torque transfer to the engine during vehicle coasting maneuvers and regenerative braking.
BACKGROUND OF THE INVENTION
In a standard vehicle drive system it is well known to provide a torque converter between the crankshaft of an internal combustion engine and a transmission to control torque so as to smooth drive speed changes in response to operator selected drive modes made by manual or electrical setting of gear shift consoles operatively coupled to a multi-speed transmission. Examples of such prior art torque converters are shown in U.S. Pat. Nos. 3,497,043; 4,951,788 and 5,129,493. Typically, such torque converters include a lock-up clutch to produce a direct drive connection between the engine and the transmission. Furthermore, such torque converters include a damper assembly to absorb torque fluctuations from the input drive once the impeller and turbine of the torque converter are interconnected by known torque lock-up clutches.
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 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.
SUMMARY OF THE INVENTION
Accordingly, an object of the invention is to provide an improved torque converter having a mechanical one-way clutch connected between the pump and turbine of the torque converter that free wheels in the input drive direction so that the engine can be started by an electric motor that is directly connected to the crankshaft of the engine and wherein the one-way clutch locks to directly connect the torque converter turbine and impeller during any back drive produced during vehicle coasting to prevent engine stall when fuel is cutoff in accordance with an aggressive fuel control algorithm.
A further feature of the invention is to provide such a one-way clutch connection wherein the one-way clutch is connected in series with a spring damper to smooth any back drive coupling between the transmission and the internal combustion engine.
A still further feature of the invention is to provide such a one-way clutch connection wherein the one-way clutch has an outer race connected to the impeller housing at an inner surface thereof and has sprag clutch elements supported with respect to an inner race that is coupled to a spring damper plate that is connected through a series of damping springs to the turbine output shaft of a torque converter.
Still another object of the present invention is to provide an improved hybrid vehicle having an internal combustion engine; a torque converter and one-way clutch connection as set forth herein and an electric motor generator connected to the crankshaft of the internal combustion engine by a direct drive belt and wherein the electric motor is utilized to charge batteries during vehicle deceleration/coasting operation and wherein the controller is programmed to be responsive to vehicle braking and coasting to provide an aggressive fuel flow cut-off while the torque converter is operative to synchronize overdrive of the vehicle during coasting with the engine speed to prevent the internal combustion engine from stalling upon fuel flow cut-off during such coasting operation.
REFERENCES:
patent: 2574573 (1951-11-01), Libby
patent: 3497043 (1970-02-01), Leonard
patent: 4304107 (1981-12-01), Fall et al.
patent: 4410071 (1983-10-01), Osterman
patent: 4509389 (1985-04-01), Vahratian et al.
patent: 4951788 (1990-08-01), Martin
patent: 5129493 (1992-07-01), Edmunds
patent: 5637987 (1997-06-01), Fattic et al.
patent: 5698905 (1997-12-01), Ruthlein et al.
patent: 5789823 (1998-08-01), Sherman
General Motors Corporation
Simon Anthony Luke
Wright Dirk
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