Machine element or mechanism – Rotary member or shaft indexing – e.g. – tool or work turret – Preselected indexed position
Patent
1982-09-20
1985-07-02
Krizmanich, George H.
Machine element or mechanism
Rotary member or shaft indexing, e.g., tool or work turret
Preselected indexed position
74867, 74868, B60K 4116
Patent
active
045260656
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to automatic power transmission mechanisms for automotive vehicle drivelines. It relates more particularly to a control valve circuit that controls the engagement and disengagement of a forward drive clutch in the gearing for the driveline to interrupt the torque delivery connection between the engine and the traction wheels when the vehicle brakes are applied and the vehicle is either standing or operating at a speed less than a predetermined value.
BACKGROUND ART
Our invention is adapted to be used in automatic transmission for automotive vehicles employing a hydrokinetic torque converter and multiple ratio gearing. Such converter and gearing arrangements may be disposed in either an inline arrangement wherein the output shaft is coaxially disposed with respect to the axis of the converter and with respect to the crankshaft of the engine or in a transaxle arrangement wherein the engine and converter are located on one axis and the output elements of the gearing are mounted for rotation about a transverse axis. In either case engine torque is delivered to the impeller of the converter and the turbine of the converter acts as a driver for the torque input elements of the gearing. Fluid pressure operated brakes are employed for establishing reaction points for the gearing and multiple fluid operated clutches are employed for establishing a connection between the turbine and selected torque input elements of the gearing.
Such control systems employ a fluid pressure pump driven by the engine and a control circuit that responds to engine torque and vehicle speed to effect engagement and disengagement of the clutches and brakes. It is usual practice for the turbine to remain connected to the torque input element that establishes a low speed ratio condition in the gearing when the vehicle is brought to a stop by applying the vehicle brakes although the magnitude of the torque delivered through the converter is low when the vehicle is stopped and the engine is idling, a minimal torque delivery to the traction wheels nevertheless is established which tends to cause the vehicle to creep. The engine, furthermore, must overcome the load imposed on it because of this residual torque transfer; and this is done at the expense of engine fuel economy and the quality of engine exhaust gas emissions.
The improvement of our invention makes it possible to disconnect the turbine from the torque input elements of the gearing when the engine is idling and the vehicle is stopped or when the vehicle is braked while the vehicle is traveling at a speed less than the selected minimum value. This is accomplished by the use of valve components that disengage the friction clutch between the turbine and the torque input element of the gearing but that allows for a threshold pressure to remain in the servo for the clutch so that a subsequent engagement of the clutch will occur instantaneously upon depression of the engine carburetor throttle during vehicle startup.
We are aware of various prior art teachings that relate to the general concept of establishing a neutral-idle condition in a vehicle driveline. Examples of these are shown in U.S. Pat. No. 2,608,880 (Flinn) wherein a transmission control functions to interrupt torque delivery through a powertrain when the vehicle brakes are applied and the speed of the transmission tailshaft is below a certain value. Provision is made by Flinn for maintaining the powertrain in a torque delivery condition even though the accelerator is returned to its closed position without reference to application of the brakes when the speed is above the designed value.
Another example of prior art having a neutral-idle condition is the circuit shown in U.S. Pat. No. 4,298,109 (Dorpmund et al). That reference shows a main control valve between an automatic transmission low speed ratio clutch which responds to governor pressure and to a torque dependent pressure to deliver control pressure directly to the clutch when the governor pressure and the torque dependent pres
REFERENCES:
patent: 2608880 (1952-09-01), Flinn
patent: 3667322 (1972-06-01), Noguchi et al.
patent: 4105101 (1978-08-01), Forster et al.
patent: 4298109 (1981-11-01), Dorpmund et al.
patent: 4313353 (1982-02-01), Honig
patent: 4331045 (1982-05-01), Piech et al.
Rosen Stanley D.
Ross William D.
Ford Motor Company
Harrington Donald J.
Krizmanich George H.
Wright Dirk
Zerschling Keith L.
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