Interrelated power delivery controls – including engine control – Plural engines – Electric engine
Reexamination Certificate
2001-12-12
2003-10-14
Pang, Roger (Department: 3681)
Interrelated power delivery controls, including engine control
Plural engines
Electric engine
C180S065230
Reexamination Certificate
active
06632155
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a drive system, for motor vehicles in particular, and to a process for operation of a motor vehicle with such a drive system.
BACKGROUND OF THE INVENTION
A generic drive system is disclosed in DE 197 37 791 A1; this system has an internal combustion engine as first power source, an electric motor as second power source, and a gear box with four speed gears as speed change mechanism. The internal combustion engine acts by way of a clutch on a countershaft of the transmission, while the electric motor is connected directly to the countershaft. This drive system may be used, for example, to start and drive in the lower speed range by way of the electric motor. Through engagement of the clutch on the internal combustion engine side the internal combustion engine as well may then be engaged and optionally the electric motor switched to operate as a generator. The same speed ratios of the speed change gears of the speed change mechanism are used in the both modes of operation; hence four gears are available in the drive system in question.
DE 195 30233 A1 discloses another drive system, one with an internal combustion engine as a power source, an electric motor as another power source, and a gear box with five sets of gears as speed change mechanism. The internal combustion engine propels the front end of the drive shaft of the transmission (gear change box) by way of the engaging and disengaging clutch, while the electric motor is rigidly connected to the rear end of the drive shaft by way of a gear stage. In this instance as well the electric motor may be engaged as a generator. Consequently, in both modes of operation, as in the case of DE 197 37 791 A1 the same transmission ratios of the speed change gear set of the speed change may be used. Accordingly, five gears are available.
SUMMARY OF THE INVENTION
The object of this invention is to design the generic drive system at low additional cost and much more favorably and so as to possess greater versatility with respect to gear ratio spread a number of speeds.
It is claimed for this invention that this object is attained by means of the characteristics provided in the claims.
It is a further object of this invention to provide a drive system for a vehicle which operates using an internal combustion engine and an electric power source of which a comfortable, optionally acceleration optimized operation of the vehicle can be achieved.
Application of the measures claimed for the invention yields the particular advantage that the gearbox is used as speed change mechanism in both directions of power flow with respect to the speed change gear sets of the first or the second power source, designated in what follows as internal combustion engine and electric motor, the following functions being possible through simple engagement and disengagement of clutches:
1. Power by way of the electric motor only for starting and for forward or reverse driving in an urban area;
2. Power by way of the internal combustion engine only, but with gear step-up or reduction at higher speeds, but optionally also for starting (emergency operation);
3. Drive by way of both power sources in the event of extreme acceleration;
4. Starting the internal combustion engine by means of the electric motor;
5. Engagement of the electric motor as generator to supply the vehicle electrical system in operation of the internal combustion engine and optionally in operation of the brake of the motor vehicle; and
6. Brief propulsion by the electric motor between gearshift stages to prevent or reduce interruption of tractive power in internal combustion engine operation.
Consequently, application of the solution proposed results in doubling of the speed ranges, so that in theory eight speeds or transmission stages may be used with four speed-change gear sets. It is also of particular advantage if power connections differing from the viewpoint of their transmission ratios, such as gears, chains, etc. are provided. In the process the connection engaging the electric motor, preferably a first spur pinion, may be designed for higher starting torque and lower speed range, while the power connection engaging the internal combustion engine or the pertinent gear set may be designed optimally for higher vehicle speeds, up to fuel conserving overdrive operation.
The engaging and disengaging clutches may be positive locking jaw clutches, synchronous clutches, and/or friction clutches which are mounted on the driven shaft and/or the other two gear shafts, depending on the structural relationships. A clutch which may also be used as starting clutch (single-disk dry clutch or multiple-disk clutch) should also be provided in the power flow on the internal combustion engine side in order to make starting of the vehicle by way of the internal combustion engine possible at least in emergency operation.
A drive system particularly well suited for front-wheel drive or all-wheel drive is provided in another embodiment such that the driven shaft is power-connected by a chain to one of the gear shafts. This permits spatially favorable mounting of the drive shafts and, in particular, makes possible an integrated differential for the front axle of the motor vehicle.
According to another embodiment, the drive system described is to be operated as follows:
First the electric motor is started by an electronic control unit with set transmitter power value on the gas pedal, as a function of speed and/or power, when the gas pedal is actuated, and the starting torque and the speed are controlled by appropriate current regulation. Shifting through the first gears may be effected by manual or automatic shifting. Starting at a definite speed or higher power demand (full throttle or optionally kickdown actuation) the internal combustion engine is connected and activation (by ignition) and its power output adjusted upward, optionally with simultaneous switching from electric motor operation to internal combustion engine operation (shifting of connectable drive connections accompanied by reversal of power flow in the transmission). In the process it may be advantageous to feed additional power to the electric motor or, in the event of lower power requirement for supplying the vehicle electric network, to switch to generator operation.
By preference the different transmission ratios of the drive connections are designed so that a vehicle is driven only by the electric motor over traffic stretches with speed limits, such as 30 km/hr, in operation more or less at this speed stages of operation of the internal combustion engine involving partial load areas unfavorable to efficiency and release of noise and exhaust gas emissions are thereby largely avoided.
In addition, during internal combustion engine operation the electric motor may also be engaged for short periods in gear shift phases on the basis of its direct coupling in order to prevent interruptions of tractive power. Since this engagement is for a very brief period only, the possibility exists of operating the electric motor without damage in the overload area and thus also that of adding high drive torque.
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patent: 6491602 (2002-12-01), Hohn
patent: 195 30 233 (1997-02-01), None
patent: 492152 (1992-07-01), None
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Pang Roger
Stevens Davis Miller & Mosher LLP
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