192 clutches and power-stop control – Clutches – Progressive engagement
Patent
1982-08-04
1985-12-24
Bonck, Rodney H.
192 clutches and power-stop control
Clutches
Progressive engagement
13759616, 13762564, 192 85AA, 192109F, F16D 2514
Patent
active
045600473
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to the hydraulic control circuit of an automatic transmission and more particularly to such a control circuit for quickly pressurizing and quickly venting the cylinder of a clutch or servo through operation of a solenoid operated control valve.
2. Prior Art
It is known in the art that fluid capacity modulator valves and accumulators can operate together to smooth gear ratio upshift changes by controlling the rate at which the associated clutch is applied. When the upshift begins the capacity modulator valve produces a reduced or regulated pressure, which is applied to the operative clutch and to the spring of an accumulator. The accumulator is filled and pressure regulation continues until it is fully filled. Thereafter, regulation ceases and line pressure is directly applied to the clutch cylinder to complete the engagement. Such hydraulic systems provide gradual or rapid pressure build-up depending upon the conditions and the requirements indicated by movement of a control valve.
A desirable control feature of solenoid operated hydraulic control systems is optimized shift quality. It is undesirable to have a shift between gear ratios that extends for a very short time because it produces a noticable and objectionable rapid change in vehicle acceleration producing a harsh shift. On the other hand, if the period for engagement of the selected clutch or servo extends for too long, excessive heat and wear on the friction elements used to produce the desired coupling or braking of the gear elements results. Accordingly, the preferred engagement of a clutch or servo of an automatic transmission is long enough to avoid the objectionable harsh shifting that results when the engagement is too fast yet short enough to avoid excessive heat and wear that results if the engagement is unduly protracted.
SUMMARY OF THE INVENTION
The hydraulic cylinder within which the actuating piston of a hydraulic clutch moves is pressurized selectively in order for the piston to apply a variable hydraulic force to friction discs, which are mechanically joined alternately to one or the other of two elements of the torque delivery path of the transmission. The early portion of the period during which the cylinder is pressurized is used to take up design clearances and tolerances, component deflections and the clearances that result due to wear of the thickness of the clutch discs and brake bands. Preferably, this initial pressurization phase should occur rapidly and at low pressure so that the cylinder of the clutch is filled quickly and the piston moved rapidly until the clutch discs are brought into abutting contact with one another or until the brake band engages the brake drum. The hydraulic force applied to the piston of the servo or clutch should not be sufficient to prevent relative movement between the elements of the torque delivery path to be coupled. After the piston has moved the friction elements into contact, a larger pressure force must be applied to the piston so that the clutch or servo can complete its engagement. Preferably this should be controlled to avoid harsh engagement as the hydraulic pressure in the cylinder increases at a rate sufficient to couple the drive elements quickly but without impact or excessive noise.
In order to disengage the clutch or servo the cylinder should be rapidly vented. This permits the spring to return the piston to the opposite end of its travel as rapidly as hydraulic forces remaining within the piston will permit without abrupt contact and noise.
It is therefore an object of this invention to provide a hydraulic control system for pressurizing or depressurizing friction clutches and servos of an automatic transmission to produce smooth engagement of the coupled elements without causing excessive noise, wear and impact. A more specific object of this invention is to provide a solenoid operated valve for modulating the rate at which high pressure is applied to the clutch cylinder during the period when t
REFERENCES:
patent: 2807968 (1957-10-01), Forster
patent: 3215236 (1965-11-01), Pensa
patent: 3351170 (1967-11-01), Hengstler
patent: 3680410 (1972-08-01), Sumiyoshi et al.
patent: 3727487 (1973-04-01), Forster et al.
patent: 3754482 (1973-08-01), Sanders et al.
patent: 3935793 (1976-02-01), Murakami
patent: 3948146 (1976-04-01), Maurer et al.
patent: 3964506 (1976-06-01), Grundman
patent: 3991865 (1976-11-01), Komatsu
patent: 4086994 (1978-05-01), Hirosawa et al.
Byler Richard E.
McCarthy James P.
Bonck Rodney H.
Ford Motor Company
Harrington Donald J.
McKenzie Frank G.
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