192 clutches and power-stop control – Vortex-flow drive and clutch – Including drive-lockup clutch
Patent
1995-01-18
1996-08-27
Lorence, Richard M.
192 clutches and power-stop control
Vortex-flow drive and clutch
Including drive-lockup clutch
192 85R, 192109F, F16H 6114
Patent
active
055491847
DESCRIPTION:
BRIEF SUMMARY
The invention concerns a hydrodynamic converter according to the preamble of claim 1.
A hydrodynamic converter of that kind has been disclosed in DE-C1 39 15 186. In this kind it is advantageous that the converter's internal pressure is not dependent on the actuating pressure of the bridging coupling which is hydraulically actuated by an annular piston, but that the actuating pressure acts upon the annular piston in opposition to the converter's internal pressure and is controlled depending on the converter's internal pressure so as to form, from the converter intake pressure and the converter discharge pressure, a reference control pressure which acts upon a precontrolled regulating valve. The latter for its part is pressurized by a coupling control valve which, depending on the turbine speed and on the output speed of the transmission, connects a controlled pressure-fluid pipe with a main pressure pipe or a zero terminal. Thereby the actuating pressure drops to zero when the bridging coupling is open.
To be able to quickly apply closing pressure to the annular piston, a by-pass control valve is provided which makes possible an unthrottled connection to the closing-pressure chamber.
A hydrodynamic converter has also been disclosed in DE-C2 31 30 871 where a bridging coupling is pressurized in the closing direction by the converter's internal pressure. The latter is thus equal to the closing pressure and thus dependent thereon. The intake pressure of the pressurized fluid to the converter is adjusted depending on the suction pressure and the speed of a driving engine, which is the same as on the output speed and lube oil temperature. Since the converter's internal pressure changes with the load condition of the converter, temperature, viscosity, and depends on manufacturing tolerances, different closing pressures appear according to operating ratios despite an equal intake pressure.
Departing from said prior art, the invention is based on the problem of providing a hydrodynamic converter of the kind described above where, with a small expenditure of energy, the bridging coupling can be quickly and accurately controlled over broad operating ranges. According to the invention the problem is solved by the features stated in the characteristic part combined with the features of the preamble of claim 1.
According to the invention, the closing pressure of the coupling is not lowered to zero, but only by a given value so as to be lower than the converter's internal pressure and to sufficiently open the coupling. Thereby, the closing-pressure chamber on the annular piston is filled with pressurized fluid so that the bridging coupling quickly responds with a relatively small supply of fluid when again switched on.
Since the closing pressure is regulated depending on the converter's internal pressure, changes caused by the operation and manufacturing tolerances that appear in series production are taken into account and, to a great extent, automatically compensated for. The presettable pressure difference can be determined by the design of the regulating springs. Said difference is thus not dependent on the converter's variable internal pressure.
Since the internal pressure of the converter is difficult to detect, as such, other reference pressures can be used for the regulation, such as a reference control pressure formed by the converter intake pressure and the converter discharge pressure, or only the output pressure of the converter which gives a good approximation.
In many cases, for reasons of comfort and in order to dampen oscillations, it is not enough to switch on the bridging coupling with the same closing pressure under all operating conditions. Therefore, according to an embodiment of the invention, it is proposed that both the output pressure of the converter and a control pressure that is modulated in accordance with other operating parameters act as a precontrol pressure upon the precontrolled regulating valve. Said operating parameters are, among others, the engine speed, the output speed, the input
REFERENCES:
patent: 2965202 (1960-12-01), Christenson
patent: 3683618 (1972-08-01), Schacher et al.
patent: 3949847 (1976-04-01), Hoehn
patent: 4880091 (1989-11-01), Hasegawa et al.
patent: 5163540 (1992-11-01), Mainquist et al.
Patent Abstracts of Japan vol. 015, No. 129 (M-1098) 28 Mar. 1991 & JP, A, 03 014 965 (Mazda Motor Corp.) 23 Jan. 1991 see abstract.
Patent Abstracts of Japan vol. 013, No. 014 (M-784) 13 Jan. 1989 (Toyota Motor Corporation) see abstract.
Loffler Alfons
Schwarz Josef
Lorence Richard M.
ZF Friedrichshafen AG
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