Machine element or mechanism – Rotary member or shaft indexing – e.g. – tool or work turret – Preselected indexed position
Patent
1985-12-31
1987-07-21
Bonck, Rodney H.
Machine element or mechanism
Rotary member or shaft indexing, e.g., tool or work turret
Preselected indexed position
74572, 74661, 74731, 180165, B60K 4128, B60K 904
Patent
active
046809864
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a drive unit system including a flywheel which assists braking by storing energy during braking and from which energy is recovered at all other times. The drive unit system includes a drive engine, a gear shift transmission, and a flywheel accumulator. The flywheel accumulator helps accelerate a vehicle, as it is discharged, i.e. giving off rotational energy. Furthermore, the flywheel accumulator is used to brake the vehicle, whereby it is charged, i.e. takes up rotational energy. The braking energy is thus usefully recovered. Such drive units are intended, in particular, for city buses but are also suitable for short-haul rail vehicles.
PRIOR ART
1. Article: "Infinitely Variable Transmission for the Daimler-Benz Gyrobus" by S. Hainmuller
2. Federal Republic of Germany Pat. No. 629 771
3. Federal Republic of Germany Pat. No. 30 13 024
4. Federal Republic of Germany Pat. No. 26 14 476 (corresponding to U.S. Pat. No. 4,073,139)
The invention is an improvement on one of the drive units which have become known from Reference 1. The closest prior embodiment is the embodiment designated B1 in FIG. 2. For an infinitely variable speed converter there is used in Reference 1 a hydrostatic transmission having means for the continuous variation of the transmission ratio. Each charging or discharging of the flywheel accumulator requires a continuous variation of the transmission ratio. The speed or force of variation selected (together with other factors) determines the rate of acceleration or deceleration of the vehicle.
Infinitely variable hydrostatic transmissions always had the inherent disadvantage of being relatively heavy, of complicated construction and subject to wear. As a rule, they also produce disturbing noises. In known drive units, the hydrostatic transmission is connected to the output shaft via a multi-step shift transmission. Due to the foregoing observation and to the control arrangement which requires that whenever the transmission ratio of a speed converter approaches a transmission range limit a control device must change the transmission ratio of the speed converter to maintain it within a given range certain problems are encountered. For example, upon acceleration and braking, when the flywheel is, respectively, charged and discharged the most efficient operating points of the hydrostatic transmission are passed through several times, one after another. This approach, which in principle is very favorable, sets high standards for the device used for setting the transmission ratio in the hydrostatic transmission. The result is that whenever a shifting of the gearshift transmission is necessary when the transmission ratio approaches one of the limits of the transmission range, a precise change in the transmission ratio of the hydrostatic transmission which corresponds to the step-wise jump in the gear-shift transmission must also take place within a very short time. Otherwise, expensive hydroaccumulators and the corresponding auxiliary devices are necessary.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a drive unit which dispenses with a hydrostatic transmission. This enables transmission operation, as free of wear and noise as possible. Furthermore, it is an object of the invention to enable use of the invention with existing, mass-produced transmissions.
It is known from the literature (Reference 2) to use a hydrodynamic coupling for the charging and discharging of a flywheel accumulator; see, for instance, the coupling K with variable degree of filling in FIG. 5 of Reference 2. One disadvantage of this arrangement is that during a full charging or discharging process (i.e. upon passage through the entire speed range of the flywheel accumulator) the transmission range of the coupling--and thus also the range of good efficiency--is passed through only once. Therefore, the hydrodynamic coupling suffers from high conversion losses over large parts of its operating range. Furthermore, the hydrodynamic
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Bonck Rodney H.
J.M. Voith & GmbH
Lorence Richard M.
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