US 5,337,868 AGranted

Touch point identification for automatic clutch controller

AssigneeEaton Corporation

InventorsChia H. Liu, James M. Slicker

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 while idling the engine, with the transmission in neutral and an inertial brake applied. The clutch actuation controller engages the clutch so that the measured transmission input speed matches a reference speed signal preferably between 40% and 60% of the idle speed. This reliably provides the degree of clutch engagement at a small torque matching the braking torque. When the transmission input speed is within a predetermined amount of the reference speed signal, such as 4%, this invention determines the clutch touch point corresponding to the degree of clutch engagement. This degree of clutch engagement may be a clutch position signal or a clutch pressure signal produced by an existing sensor used in the automatic clutch control. If no measured clutch engagement signal is available, this degree of clutch engagement may be the clutch engagement signal used to control the degree of clutch engagement. The touch point is set as the difference between this degree of clutch engagement for the small torque and a clutch touch point offset. The determination may begin with the clutch fully engaged and gradually released according to control by the input and reference speeds. When the previous touch point is known, the clutch is preferably initially positioned just above the known touch point and then gradually released.

Claims26

Dependent claims

In a combination including a source of motive power having a predetermined idle speed, 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 clutch output shaft, a multi-speed transmission having an input shaft connected to the clutch output shaft and including a neutral position, at least one inertially-loaded traction wheel connected to the output shaft of the multi-speed transmission, and an automatic clutch controller for control of a degree of clutch engagement, a touch point determinator comprising:

a reference speed generator for generating a reference speed signal that corresponds to a predetermined fraction of idle speed of the source of motive power;
a transmission input speed sensor connected to the output shaft of the friction clutch for generating a transmission input speed signal corresponding to a rotational speed of the output shaft of the friction clutch;
an inertial brake selectively engagable for applying a predetermined braking torque to the output shaft of the friction clutch;
a clutch actuator connected to the friction clutch for controlling actuation of the friction clutch between disengaged and fully engaged according to a clutch engagement signal;
and
a controller connected to said reference speed generator, said transmission input speed sensor, said inertial brake, said clutch actuator and said clutch engagement sensor including
an inertial brake engager for engaging said inertial brake during touch point determination when the source of motive power is idling and the multi-speed transmission is in neutral,
a first algebraic summer connected to said reference speed generator and said transmission input speed sensor generating a first algebraic sum signal corresponding to the difference between (1) said reference speed signal and (2) said transmission input speed signal,
a compensator connected to said first algebraic summer for generating said clutch engagement signal for supplying to said clutch actuator for actuating the friction clutch to a degree to minimize said first algebraic sum signal, and
a decision logic unit connected to said reference speed generator, said transmission input speed sensor and said clutch engagement sensor for setting a clutch touch point signal equal to a measure of clutch engagement if said transmission input speed signal is within a predetermined amount of said reference speed signal when said inertial break is engaged and the multi-speed transmission is in the neutral position.

7 more elements

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

operating the source of motive power at idle speed;
selecting the neutral position of the multi-speed transmission;
applying a predetermined braking torque to the output shaft of the friction clutch;
generating a reference speed signal less than the idle speed;
sensing a rotational speed of the output shaft of the friction clutch;
determining the difference between said reference speed signal and the sensed rotational speed of the output shaft of the friction clutch;
actuating the friction clutch to a degree of clutch engagement to minimize said difference;
determining the clutch touch point signal corresponding to the degree of clutch engagement if the sensed rotational speed of the output shaft of the friction clutch is within a predetermined amount of the reference speed signal.

5 more elements

Dependencies are inferred from the claim text.

Facts

Application: 08/126,107Filed 23 Sep 1993 · continuation in part
Priority: 2 Jan 1992
Granted: 16 Aug 1994
Term ends: Not estimatedThe source records don’t support an estimate.

Classification29 codes

B60W 10/06
Including control of propulsion units: including control of combustion engines
B60W 10/02
Conjoint control of vehicle sub-units of different type or different function: including control of driveline clutches
B60W 10/04
Conjoint control of vehicle sub-units of different type or different function: including control of propulsion units
B60W 10/10
Conjoint control of vehicle sub-units of different type or different function: including control of change-speed gearings