Interrelated power delivery controls – including engine control – Transmission control – Transmission controlled by engine
Patent
1997-10-09
1999-10-05
Ta, Khoi Q.
Interrelated power delivery controls, including engine control
Transmission control
Transmission controlled by engine
477905, 477115, F16H 6116, F16H 6102
Patent
active
059614200
DESCRIPTION:
BRIEF SUMMARY
This invention relates to vehicle transmission control systems and in particular to such systems for the control of multi ratio vehicle transmissions driven via a main drive clutch means and in which the ratios are engaged by syncromesh units (or similar clutching devices) operated by actuating means which may be fluid pressure operated. Such transmissions may be arranged to change their operative ratio automatically in response to variations in the operating conditions of the associated vehicle or may have an automatic selection mode as well as a manual selection mode. Examples of such transmissions are described in co-pending UK Patent Application Nos 95 05174.4, 95 05176.9 and 95 07462.1.
It is an object of the present invention to provide an improved form of vehicle transmission control system which automatically adapts to the style of the current vehicle driver and prevailing road conditions and environment.
Thus according to the present invention there is provided a vehicle transmission control system in which a central control unit issues signals to an associated main drive clutch actuator means and to ratio actuating means to effect changes in the operative ratio of an associated transmission in accordance with a predetermined shift point map, the system being characterised in that, when the shift point map indicates that a ratio shift is appropriate, the system tests for fluctuations in the position of an associated engine accelerator pedal and only actions the shift if the degree of fluctuation of the accelerator pedal position is judged acceptable.
The shift may only be actioned if the fluctuation in accelerator position does not exceed a predetermined level within a predetermined time period.
The acceptable level of fluctuation in accelerator position may vary with engine speed. The time period may also vary with engine speed. For example, the acceptable level of fluctuations in accelerator position preferably increases and the time period decreases with increasing engine speed and vice versa.
The acceptable level of fluctuation in accelerator pedal position is preferably defined as a range of angular movement of the accelerator pedal which increases with engine speed.
In an alternative form of the invention the shift is only actioned if the rate of movement of the accelerator pedal is less than a predetermined rate.
The control system preferably also includes the additional control that when a particular shift point is reached on the shift map a vehicle speed band is entered, within which the vehicle speed must remain for a predetermined period of time, or which must be exceeded, before the appropriate shift is actioned.
The vehicle speed band preferably varies with accelerator pedal position.
The shift point map may be modified during a given journey dependent on one or more of the following parameters: brakes; accelerator pedal position
If the average vehicle speed during a journey is high the control means may reduce the time taken to shift between operative ratios and vice versa.
One embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which:
FIG. 1 shows diagramatically a vehicle transmission control system with a control unit which operates in accordance with the present invention;
FIG. 2 shows diagrammatically the generation of a clutch engagement control signal used in the system of FIG. 1;
FIG. 3 is a flow diagram of the decision process employed in the control system of the present invention;
FIG. 4 shows a typical standard shift point map, and
FIGS. 5 and 6 show graphically the typical variation of the parameters "time period" and "fluctuation level" with engine speed used in the control system of the present invention.
Referring to FIG. 1 this shows an engine 10 with a starter and an associated starter circuit 10a which is coupled through a main drive friction clutch 14 with a five speed synchronised lay-shaft type gearbox 12 via a gearbox input shaft 15. In the example described, fuel is supplied to the e
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AP Kongsberg Limited
Ta Khoi Q.
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