Method for controlling clutch in vehicle transmission system equipped with friction type stepless speed changer

Abstract

The invention relates to a method for controlling a friction clutch (3) in a vehicular drive line further provided with an engine (1), a friction-type continuously variable transmission (2) and a driven wheel (5), which method comprises the steps of controlling a slip value (Cs) of the clutch (3), of detecting the occurrence of a torque jolt (block A) and, if no such torque jolt is detected, of performing the clutch slip (Cs) control closed-loop (block B), or, if a torque jolt is detected, of performing the clutch slip (Cs) control open-loop (block C).

Description

technical field

[0001] The present invention relates to a method for controlling a friction clutch in a vehicle drive train provided with a frictional continuously variable transmission. Such a control method is well known, for example US-A-4606446 describes a transmission having two variable pulleys and a drive belt wound around and in frictional contact with the two pulleys. Background technique

[0002] A common problem encountered in friction transmissions is slip between friction components, such as between a drive belt and a pulley, which needs to be avoided because excessive slip can cause excessive wear and tear on these components Or at least it can happen within a limited confines. To prevent these slippages, a sufficient normal force is applied between the friction components, which is usually determined based on the engine torque delivered by the transmission plus a safety margin. This safety margin is introduced because engine torque is not precisely available...

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