Motor vehicles – Power – Electric
Reexamination Certificate
2000-05-19
2003-01-21
Olszewski, Robert P. (Department: 3627)
Motor vehicles
Power
Electric
C180S065230, C180S065600
Reexamination Certificate
active
06508321
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to invention is relative to a drive arrangement for a vehicle, especially a non-railborne vehicle, with at least one internal combustion engine, at least one generator, at least one electric drive motor and at least one torque converter arranged between the drive motor and a driven shaft as well as to a method for increasing the torque transferred onto the vehicle axles of a non-railborne vehicle with diesel-electric drive.
2. Description of the Related Art
The use of drives in which an internal combustion engine is connected to a generator for the production of current and in which the drive is brought about by an electromotor fed by said generator is currently being increasingly discussed, especially for street vehicles. Particular attention is to be called here to the so-called diesel-electric drives.
Such a diesel-electric drive is known for a non-railborne vehicle, for example, from European patent EP 0,527,145 B1. The vehicle known from this publication is distinguished in that the internal combustion engine and the generator are combined to a so-called internal combustion engine-generator subassembly.
Special drive concepts for vehicles with an internal combustion engine and a generator in which so-called permanent-magnet motors are used as drive motors are known from “Drive Systems with Permanent Magnet Synchronous Motors” in Automotive Engineering, February, 1995, pp. 75-81.
The use of diesel-electric drives, especially in commercial vehicles, is described in the publication, “An Electrical Individual-Wheel Drive for City Busses of the Future”, B. Wüst, R. Müller, A. Lange in Local Service, June/1994, Alba Fachverlag, Dusseldorf, pp. 1-7. The disclosed content of all previously cited publications is included herewith to its complete extent in the present application.
The drive motors and traction motors were always arranged close to the wheels in the drive arrangements known from the state of the art, especially in the form of the last-cited publication. This entailed a great number of disadvantages. For example, such drive arrangements were quite heavy and the vehicles deviated significantly in their design from traditional vehicles with conventional drive so that there was no compatibility.
SUMMARY OF THE INVENTION
These disadvantages can be overcome by a central drive in which the traction motors are not mounted on the axle close to the wheels or in the same axle, but rather are coupled to the axis via a summation transmission. In such an arrangement the traction motor can be attached in the chassis of, e.g., a city bus and drive a customary mechanical low-platform axle by means of a universal-joint shaft. This can reduce to a minimum the construction differences of a vehicle with a diesel-electric drive in comparison to a vehicle with an automatic transmission, which brings about significant logistic advantages.
A further disadvantage of the previous drive concepts was the fact that more than one traction motor always had to be used, e.g., two traction motors attached close to the wheels using the concept known from B. Wüst, R. Müller, A. Lange: An Electrical Individual-Wheel Drive for City Busses of the Future, Der Nahverkehr, June/1994, pp. 1-7, Aba Fachverlag Dusseldorf. This was disadvantageous in particular in the case of permanently excited traction motors, which also include the transversal flux machines used as a motor. When two traction motors were used, very great no-load losses had to be overcome, which appear on account of the permanent excitation of the traction motors. A minimizing of the no-load losses might be possible if only one central traction motor is provided instead of, e.g., two traction motors.
The problem of the central drive concepts addressed is the fact that when only a single, central traction or drive motor is used during starting, only an insufficient torque is made available on the axles from the traction motor.
This problem is solved in accordance with the invention in that the drive motor or traction motor is coupled to a torque converter for magnifying the torque delivered from the drive motor onto the vehicle axles.
The torque output from the drive motor can be converted and magnified by connecting in a torque converter between the drive motor and the driven shaft. This is especially necessary during the starting of the vehicle in order to make available the required torques and starting traction. The same applies to use on inclines.
It is especially advantageous if the drive motor is not constantly connected to the converter but rather can be coupled to the converter and decoupled from it as required with the aid of a coupling. Any type of coupling is suitable for this purpose, e.g., those shown in Dubbel, “Pocket Book for Machine Construction”, 18
th
edition, pages G63-G74. The disclosed content of the previously cited publication is included to its full extent in this application. Converter bridge couplings and so-called lock-up couplings, which couple the converter to the traction motor as required and, when a torque conversion is no longer required, bridge the torque converter. Such converter bridge couplings or lock-up couplings are known in particular for hydrodynamic torque converters and shown, e.g., in Gerigk, Bruhn, Danner, Endruschat, Gobert, Gross, Komoll, Motor Vehicle Technology, Westermann Verlag, 2
nd
edition, 1994, pp. 349-352, the disclosed content of which is completely included in this application. In a hydrodynamic torque converter with bridge coupling or lock-up coupling, the converter operates with open coupling, that is, the converter is connected into the power flow from the drive motor to the driven shaft, whereas, on the other hand, when the coupling is closed the converter is bridged, so that the drive motor acts directly on the driven shaft.
A special embodiment provides that the drive arrangement comprises a control with whose aid it is possible that the converter is coupled to the drive motor when starting procedures are detected and when a set travel speed and/or starting acceleration is exceeded the control bridges the torque converter and separates it from the drive motor so that the drive motor then acts directly on the driven shaft and drives the vehicle. Thus, the torque converter operates only in the lower speed range and compensates, by means of the achievable magnifying of the torque, the disadvantage of the too slight torque of the electrical drive machine in this operating state. As a result of the monitoring of the starting acceleration by means of the control of the invention, the converter is only utilized for a rather long time period in very few instances of starting procedures. A torque conversion for a rather long time period is required in particular when starting on inclines, e.g., on inclines greater than 6 percent, with a fully occupied vehicle. In all other starting instances, the lock-up coupling is already closed in a short time so that losses, which can occur as a consequence of the converter output, remain without noticeable effects on the fuel consumption of the vehicle equipped with a torque converter. I this manner, it is achieved that the consumption advantage which can be achieved with a diesel-electric vehicle is preserved.
A hydrodynamic torque converter like the one disclosed, e.g., in “Hydrodynamic Transmissions, Couplings and Brakes”, Krausskopf-Verlag GmbH, Mainz, 1970 on pages 28-37 is used with preference as a torque converter. A hydrodynamic torque converter comprises, in addition to a pump impeller and a turbine wheel, a guide wheel, which is also designated as a reaction component. Since the guide wheel of a torque converter must receive a moment as a reaction component and since the sum of the moments in the circuit must be equal to zero, the turbine moment can be greater than, equal to or less than the pump moment, depending on the magnitude and direction of rotation of the guide-wheel moment, that is, the pump moment can therefore be converted.
A drive arrangement i
Knuth Randall J.
McClellan James S.
Olszewski Robert P.
Voith Turbo GmbH & Co. KG
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