Control method for achieving expected VCT actuation rate using set point rate limiter

• US 20030230262A1
• Filed: 11/25/2002
• Published: 12/18/2003
• Est. Priority Date: 06/17/2002
• Status: Active Grant

• Current Assignee: BorgWarner Incorporated
• Original Assignee: BorgWarner Incorporated
• Inventors: Quinn, Stanley B. Jr.
• Granted Patent: US 6,810,843 B2
• Time in Patent Office: Days
• US Class Current: 123/90.15
• CPC Class Codes: F01L 1/34 characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift
• CPC Class Codes: F01L 1/344 changing the angular relationship between crankshaft and camshaft, e.g. using helicoidal gear
• CPC Class Codes: F01L 1/3442 using hydraulic chambers with variable volume to transmit the rotating force
• CPC Class Codes: Y10T 74/2102 Adjustable

Abstract

In a VCT system having a feedback loop for controlling a phaser angular relationship, a control law disposed to receive a plurality of set point values and a plurality of feed back values is provided to include: a computation block for receiving the plurality of set point values as inputs, the computation block outputting a first output and a second output; a first summer for summing the first output and the plurality of feed back values to produce a first sum (e₀); a phase integrator and a phase compensator receiving the first sum (e₀) and derivatives (e₁) thereof outputting a processed value (e₂); a amplifier amplifying the second output by a predetermined scale (K_ff); and e) a second summer for summing the processed value (e₂) and the amplified second output to produce a second sum (e₃).

Claims

1. In a VCT system having a feedback loop for controlling a phaser angular relationship, said system including a controller having a control law disposed to receive a plurality of set point values and a plurality of feed back values, said control law comprising:

a) a computation block for receiving said plurality of set point values as inputs, said computation block outputting a first output and a second output;

b) a first summer for summing said first output and said plurality of feed back values to produce a first sum;

c) a phase integrator and a phase compensator receiving said first sum and derivatives thereof outputting a processed value;

d) a amplifier amplifying said second output by a predetermined scale; and

e) a second summer for summing said processed value and the amplified second output to produce a second sum.

2. The control law of claim 1, wherein said first output includes mode information.

3. The control law of claim 1, wherein said second output includes slope information of said plurality of set point values.

4. A VCT system, comprising:

sensors for receiving position information of cam and crank shafts respectively;

a phaser for adjusting small changes between said crank and cam shafts;

an actuator engaging said phaser;

a controller for controlling said actuator, said controller including a control law, wherein said control law includes;

a computation block for receiving said plurality of set point values as inputs, said computation block outputting a first output and a second output;

a first summer for summing said first output and said plurality of feed back values to produce a first sum;

a phase integrator and a phase compensator receiving said first sum and derivatives thereof outputting a processed value;

a amplifier amplifying said second output by a predetermined scale; and

a second summer for summing said processed value and the amplified second output to produce a second sum.

5. The VCT system of claim 4, wherein said first output includes mode information.

6. The VCT system of claim 4, wherein said second output includes slope information of said plurality of set point values.

7. The VCT system of claim 4, wherein said actuator is a solenoid.

8. In a VCT system having a feedback loop for controlling a phaser relationship, said system including a controller having a control law disposed to receive a plurality of set point values and a plurality of feed back values, said control law being disposed to perform a method comprising the steps of:

a) providing a set point change;

b) determining a mode of said VCT system among a set of four modes; and

c) selectively applying a filter upon said set point change, thereby reducing overshoot caused by set point change.

9. The method of claim 8 further comprising calculating feedforward signal.

10. The method of claim 8, wherein said set of four modes includes:

a first mode wherein there is no substantial change in set point values;

a second mode wherein there is a substantial increase in set point values;

a third mode wherein there is a substantial decrease in set point values; and

a fourth mode wherein the measured position of phaser is close to the set point.

11. The method of claim 10, wherein said filter is applied when said VCT system is under said fourth mode.