Electric variable cam timing control device
AssigneeDenso Corporation
InventorYoshiki Kato
Life of this patent
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Abstract
When an EDU determines that a motor is in a control unstable state where the motor cannot be controlled to a target rotation speed due to a drive voltage output duty value being smaller than a threshold value, the EDU performs a control point shifting operation to shift a control point between a first control point, which is in the control unstable state, and a second control point, which is a control stable state outside the control unstable state. Thus, even when the motor is in a stepping rotation state, it is possible to control the target rotation speed regardless of influence of a cogging torque, and appropriately control the cam phase of the intake camshaft to a target phase when the engine is stopped.
Claims9
An electric variable cam timing control device for controlling a cam phase of a cam shaft of an engine to a target phase by controlling a motor to a target rotation speed, the electric variable cam timing control device comprising a rotational torque increase unit configured to execute processing of:
- checking whether the motor is in a control unstable state in which the motor is disabled to be controlled to the target rotation speed;
- and
- performing, when the motor is determined to be in the control unstable state, a control point shifting operation for shifting a control point between a first control point and a second control point to increase a rotational torque of the motor, the first control point being a point at which the motor is in the control unstable state, and the second control point being a point at which the motor is in a control stable state outside the control unstable state wherein:
- the rotational torque increase unit determines that the motor is in the control unstable state when a rotation speed of the motor is smaller than a predetermined threshold value, and
- the rotational torque increase unit executes the processing of checking on condition that a control parameter used for controlling the motor is smaller than a predetermined threshold value.
An electric variable cam timing control device for controlling a cam phase of a cam shaft of an engine to a target phase by controlling a motor to a target rotation speed, the electric variable cam timing control device comprising:
- a motor rotation speed detection unit configured to detect an actual rotation speed of the motor;
- and
- a control unit configured to control the motor so that the actual rotation speed of the motor attains a target rotation speed during a period following stopping of fuel supply, wherein the control unit is configured to execute processing of:
- calculating a control value of the motor based on a speed difference between the target rotation speed and the actual rotation speed;
- checking whether the control value of the motor is smaller than a predetermined value;
- checking whether the target rotation speed of the motor is substantially zero;
- checking whether the actual rotation speed is smaller than a predetermined rotation speed;
- and
- changing the control value of the motor to a larger value, when the control value calculated based on the speed difference is smaller than the predetermined value, the target rotation speed of the motor is substantially other than zero and the actual rotation speed is smaller than the predetermined rotation speed.
Dependencies are inferred from the claim text.