US 5,393,274 AGranted

Touch point identification algorithm for automatic clutch controller

AssigneeEaton Corporation

InventorDaniel G. Smedley

Life of this patent

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Abstract

This invention provides automatic and reliable determination of the touch point of a clutch controlled by an automatic clutch actuation controller. This invention determines the touch point upon power-up while idling the engine, with the transmission in neutral and an input shaft brake applied. The clutch actuation controller gradually engages the clutch so that the measured transmission input speed matches a reference speed signal preferably between 40 and 60% of the idle speed. If the actuation is slow enough, this reliably provides the degree of clutch engagement at a small torque matching the braking torque which is the touch point. If there is no previous knowledge of the touch point, the clutch is applied at a fast rate and an approximate touch point is determined, then the clutch is positioned below the approximate touch point and is again applied at a slow rate to more accurately ascertain the touch point. If there is previous knowledge of the touch point, the clutch is positioned just below the old touch point and is applied at a slow rate to determine a new touch point. The new and old touch points may be combined to determine the updated touch point.

Claims12

Dependent claims

In a combination including a source of motive power having a predetermined idle speed, a friction clutch for controllably transferring torque from the source of motive power to a transmission input shaft, a multi-speed transmission having an output shaft and including a neutral position, at least one traction wheel connected to the output shaft of the transmission, and an automatic clutch controller for control of the degree of clutch engagement, a method of determining the touch point of the friction clutch comprising the steps of:

operating the source of motive power at the idle speed;
selecting the neutral position of the transmission;
applying a predetermined braking torque to the transmission input shaft;
selecting a reference speed less than the idle speed;
sensing the rotational speed of the transmission input shaft;
applying the friction clutch at a first rate of application;
sensing a first degree of clutch engagement when the transmission input speed attains the reference speed;
releasing the clutch by changing the degree of clutch engagement by a first offset amount from the first degree of clutch engagement;
applying the friction clutch at a second rate of application which is less than the first rate;
and
sensing the clutch touch point when the transmission input speed attains the reference speed during application at the second rate.

8 more elements

Dependencies are inferred from the claim text.

Facts

Application: 08/094,874Filed 19 Jul 1993
Granted: 28 Feb 1995
Term ends: Not estimatedThe source records don’t support an estimate.

Classification20 codes

F16H 63/46
Comprising signals other than signals for actuating the final output mechanisms: signals to a clutch outside the gearbox
B60W 10/02
Conjoint control of vehicle sub-units of different type or different function: including control of driveline clutches
B60W 10/10
Conjoint control of vehicle sub-units of different type or different function: including control of change-speed gearings
B60W 30/1819
Propelling the vehicle: propulsion control with control means using analogue circuits, relays or mechanical links