Engine manifold valve control

Details Engine manifold valve control Engine manifold valve control

1999-06-17

2000-09-12

Yuen, Henry C.

Internal-combustion engines

Engine speed regulator

Open loop condition responsive

123361, F02D 900

Patent

active

061162167

DESCRIPTION:

BRIEF SUMMARY
FIELD OF THE INVENTION

The present invention relates to a method and apparatus for controlling the position of an engine manifold valve and relates particularly, though not exclusively, to such a method and controller for controlling throttle position in a gas fuelled internal combustion engine.


BACKGROUND TO THE INVENTION

The previous engine management systems developed by Transcom Gas Technologies Pty Ltd, such as that described in PCT/AU93/00649 (WO94/13946), employed a stepper motor based throttle actuator coupled via a gear box and linkages to a throttle valve. This mechanism proved to be unreliable and inaccurate due to the lack of feedback. The inaccuracy of this mechanism was further exacerbated by the open loop control strategies employed by the previous control systems, which required repeatable positioning of the valve. Furthermore, the complete stepper motor, gearbox and throttle valve assembly was bulky and connected via adjustable linkages which if varied affected the engine tuning.
This prior art stepper motor throttle actuator achieved variable resolutions using a lever and linkage mechanism. The transfer function between the number of 1.8.degree. stepper motor steps and throttle valve angle gave extremely high resolution at low step numbers which correspond to the engine's idle setting, where the greatest control is required. The step number at idle was approximately 30, while the throttle angle difference between step 30 and 31 was 0.000956 radians. The throttle travels through 1.202835 radians between its fully open and fully closed positions. Therefore the number of steps required to achieve the same resolution at idle for a fixed resolution is at least 1258 (1.202835/0.000956) steps.


SUMMARY OF THE INVENTION

The present invention was developed with a view to providing a controller and method for controlling the position of an engine manifold (throttle) valve which is more accurate than the previous throttle actuator control mechanism, and which can provide the same or better control resolution.
According to one aspect of the present invention there is provided a method for controlling the position of an engine manifold valve, the method comprising the steps of: and current velocity, wherein said rest position corresponds to a stationary position reached if the valve commenced deceleration from its current position and velocity; valve in order to determine whether the current position or the rest position exceeds the demanded position; and, based on said comparison.
Typically said step of accelerating/decelerating comprises calculating a motion trajectory that involves accelerating the valve to a maximum velocity, holding it at the maximum velocity and then decelerating the valve to a stop at the demanded position.
Preferably said motion trajectory is calculated such that if the valve is opening and the calculated rest position is less than the demanded position, and the maximum velocity has not yet been reached, then the valve is caused to continue to accelerate, whereas if the calculated rest position is equal to, or greater than the demanded position then the valve is caused to decelerate.
Preferably said motion trajectory is calculated such that if the current position exceeds the demanded position or the current velocity of the throttle is such that it cannot decelerate to a stop without passing the demanded position, then the valve is caused to decelerate to a stop and reverse to the demanded position.
According to another aspect of the present invention there is provided a manifold valve controller for controlling the position of an engine manifold valve the controller comprising: said sensed current position and current velocity, wherein said rest position corresponds to a stationary position reached if the valve commenced deceleration from its current position and velocity; comparing said calculated rest position with a demanded position in order to determine whether the current position or rest position exceeds the demanded position; and, generating a control signal for

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