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Touch Point Adaption for Clutch

IP.com Disclosure Number: IPCOM000242219D
Publication Date: 2015-Jun-26
Document File: 5 page(s) / 237K

Publishing Venue

The IP.com Prior Art Database

Abstract

This invention discloses a method for determining the touch point of a clutch. During this determination, the clutch is opened and thereafter closed while the gearbox is in a neutral position. If the oil in the gearbox is very viscous, torque may be transferred through the gearbox to the drive wheels when closing the clutch even if the gearbox is in neutral. According to this invention, this problem is solved by either refraining from making the touch point determination if the oil is very viscous or applying a brake during the determination.

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Touch Point Adaption for Clutch

Abstract

This invention discloses a method for determining the touch point of a clutch. During this determination, the clutch is opened and thereafter closed while the gearbox is in a neutral position. If the oil in the gearbox is very viscous, torque may be transferred through the gearbox to the drive wheels when closing the clutch even if the gearbox is in neutral. According to this invention, this problem is solved by either refraining from making the touch point determination if the oil is very viscous or applying a brake during the determination.

Description of the invention

Herein improvements of certain aspects of touch point adaptation for a clutch are discussed.

In a dry type clutch that is used in connection with e.g. an automated manual transmission (AMT) gearbox of a vehicle, it is important to keep track of the touch point of the clutch. A clutch automatically connects/disconnects, by means of an actuator, an engine of the vehicle with the AMT gearbox and further parts of the powertrain of the vehicle. The touch point is a point where the clutch starts engaging. The touch point is changed by a temperature change or wear of the clutch, so that it is necessary to appropriately adjust the touch point over time in order to keep stable operability of the clutch. This is referred to as touch point adaptation. Such touch point adaptation is performed automatically at suitable instances during operation of the vehicle.

FIG. 1 illustrates a graph showing features of clutch torque for a stroke of a clutch actuator, which shows that when a stroke increasing meets a touch point, the clutch torque starts increasing, so that if the status of the clutch is stable, it is possible to transmit maximum clutch torque designed to be larger than the maximum engine torque that the engine can transmit at the maximum stroke, but if the touch point is moved by temperature change or wear of the clutch, the maximum engine torque cannot be fully transmitted even at the maximum stroke.

As described above, the touch point is a main factor that keeps an appropriate control relationship between the clutch actuator and the clutch stable. FIG. 2 illustrates a method of searching and setting the touch point of a clutch, which is used when the gearbox is in a neutral position during operation of the vehicle, e.g. at start-up of the vehicle, during coasting downhill, when breaking the vehicle to a halt, etc. That is, a clutch actuator is operated such that a clutch that is not engaged is engaged (A), the position of the clutch actuator is determined as the touch point at the point of time when the clutch starts rotating (B), the position is adjusted as a new touch point (C), and then the clutch actuator is operated with respect to the newly set touch point.

As mentioned above, during touch point adaptation, the gearbox connected to the clutch is in a neutral position, i.e. no torque is transmitted from an input shaft of the gearbox to...