Borgwarner Inc.

Zhenyu Jiang

Philip J Mott

Earl Ekdahl

Andrew Mott

A VCT phaser having a mechanical feedback in which no elaborate sensors and its concomitant electronic control loop is required. The phaser has center mounted spool valve controlling the flow of control fluid such that when a command positions the same at a predetermined position, passages within the phaser adjusts to a desired position through the mechanical feedback.

Control mechanism for cam phaser

In a VCT system having a feedback loop including a sensed signal and a set point, a method is provided, which includes the steps of: determining a switch variable which is related to the sensed signal and the set point; computing the switch variable; and according to the value of the switch variable, controlling the operation of an on/off two position solenoid that controls the flow of a control fluid flowing within a VCT phaser. Thereby the control fluid either flows in one direction or another direction by means of using a two-position ON/OFF solenoid for actuating a spool valve which controls the flow direction with the VCT phaser.

VCT closed-loop control using a two-position on/off solenoid

A VCT phaser for an internal combustion engine with at least one camshaft comprising a housing, a rotor, a spool valve and a ring-shaped reservoir. The housing having at least one chamber and the rotor having at least one vane dividing the chambers into advance and retard. The spool valve is comprised of a spool mounted within a bore of the rotor. The reservoir is defined within the bore by an oil dam and at least one of the spool lands. The spool has a first position in which a chamber is coupled to the supply and the other chamber is exhausting fluid and a second position in which a chamber is coupled to the supply and the other chamber is coupled to the reservoir. When a torque reversal occurs, hydraulic fluid pooled in the reservoir is drawn into the other chamber when the spool is in the second position.

Avoid drawing air into VCT chamber by exhausting oil into an oil ring

Known method suitable for implementation in a computer program product for VCT closed-loop control system generally includes an integrator to eliminate the steady state error. A novel method suitable for implementation in a computer program product includes a set point filter as well to reduce the closed-loop control overshoot. Low cam torque frequency can reduce the stability of a closed-loop control system when combined with the integral action, and it can also compromise the effect of set point filter. This novel method addresses these two issues by identifying the cam torque direction and pausing control updating when there is no torque available at the desired direction.

System and method for improving VCT closed-loop response at low cam torque frequency

In a VCT system, a method uses a controller to automatically determine a state of a phaser based on an identifier. The identifier identifies a filtered signal of the crank shaft and cam shaft and uses the same to identify the phaser state. A reset signal is generated by the identifier to reset the VCT system, specifically to reset a control law whereby the unnecessary information retained by the VCT system is cleared. Therefore, the controller is able to promptly and accurately determine the phaser position and state.

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Ithaca, NY, United States of America

Zhenyu Jiang