# US 7,464,676 B2 · Air dynamic steady state and transient detection method for cam phaser movement

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- Number: US 7,464,676 B2
- Document ID: US7464676B2
- Status: Granted
- Kind: B2
- Application number: 11/434,378
- Filed: 2006-05-15
- Published: 2007-01-25
- Granted: 2008-12-16
- Earliest claimed: 2005-07-22
- Assignees: GM Global Technology Operations LLC
- Inventors: Layne K. Wiggins; Gregory P. Matthews
- Web page: https://patentgrep.com/patent/US7464676B2

## CPC

- F01L 1/344: changing the angular relationship between crankshaft and camshaft, e.g. using helicoidal gear
- F01L 2800/00: Methods of operation using a variable valve timing mechanism
- F01L 2820/041: Camshafts position or phase sensors
- F01L: CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES

## Abstract

An air dynamic steady state detection system for movement of a cam phaser of an internal combustion engine includes a cam position sensing device and a control module. The cam position sensing device generates a position signal based on a position of the cam phaser of the engine. The control module receives the position signal and applies first and second filters to the position signal to select either a transient or steady state condition. The control module also calculates an estimated air value based on the selection of the transient or steady state condition.

## Claims

### Claim 1

An air dynamic steady state detection system for movement of a cam phaser of an internal combustion engine, comprising:
a cam position sensing device that generates a position signal based on a position of said cam phaser of said engine; and
a control module that receives said position signal and that applies first and second filters to said position signal to select one of a transient condition and a steady state condition, and wherein said control module calculates an estimated air value based on said selection of said transient condition and said steady state condition.

### Claim 2 (depends on 1)

The system of claim 1 wherein said cam phaser is coupled to an intake camshaft of said engine.

### Claim 3 (depends on 1)

The system of claim 1 wherein said cam phaser is coupled to an exhaust camshaft of said engine.

### Claim 4 (depends on 1)

The system of claim 1 further comprising a second cam position sensing device that generates a second position signal of a second cam phaser of said engine, wherein said cam phaser is coupled to an intake camshaft of said engine and wherein said second cam phaser is coupled to an exhaust camshaft of said engine.

### Claim 5 (depends on 4)

The system of claim 4 wherein said control module applies third and fourth filters to said second position signal and selects one of said steady state condition and said transient condition based on a difference between said first and second filters and a difference between said third and fourth filters.

### Claim 6 (depends on 1)

The system of claim 1 wherein said control module calculates said estimated air value based on a speed density calculation when said control module determines said transient condition.

### Claim 7 (depends on 1)

The system of claim 1 wherein said control module calculates said estimated air value based on a mass airflow sensor signal and an engine speed when said control module determines said steady state condition.

### Claim 8 (depends on 1)

The system of claim 1 wherein said control module controls a fuel injector of said engine according to said estimated air value.

### Claim 9

An air dynamic steady state detection method for cam phaser movement, comprising:
receiving a cam phaser position signal;
applying a first filter to said cam phaser position signal;
applying a second filter to said cam phaser position signal;
calculating a difference between an output of said first filter and an output of said second filter;
selecting a steady state condition when an absolute value of said difference is less than a predetermined value;
selecting a transient condition when said absolute value of said difference is greater than or equal to said predetermined value; and
selecting a method for calculating an estimated air value based on said steady state condition and said transient condition.

### Claim 10 (depends on 9)

The method of claim 9 further comprising controlling fuel delivery based on said estimated air value.

### Claim 11 (depends on 9)

The method of claim 9 further comprising calculating said estimated air value based on a mass airflow sensor input and engine speed when said steady state condition is determined.

### Claim 12 (depends on 9)

The method of claim 9 wherein said step of calculating said estimated air value includes calculating said estimated air value from an absolute pressure of an intake manifold, an engine speed, an intake cam phaser position, an exhaust cam phaser position, and an estimated air temperature per cylinder.

### Claim 13 (depends on 9)

The method of claim 9 wherein said first filter has a faster time constant than said second filter.

### Claim 14

An air dynamic steady state detection system, comprising:
a first cam position sensing device that generates an intake position signal based on a position of a first cam phaser associated with an intake camshaft;
a second cam position sensing device that generates an exhaust position signal based on a position of a second cam phaser associated with an exhaust camshaft;
a state determination module that selects one of a transient condition and a steady state condition of said intake camshaft and said exhaust camshaft; and
an air estimation module that calculates an estimated air value based on said transient condition and said steady state condition of said intake camshaft and said exhaust camshaft.

### Claim 15 (depends on 14)

The system of claim 14 wherein said state determination module applies first and second filters to said intake position signal and said exhaust position signal, determines a difference between said first and second filters, and wherein said transient condition and said steady state condition are determined based on said difference.

### Claim 16 (depends on 14)

The system of claim 14 wherein said state determination module determines said transient condition when an absolute value of at least one of said difference of said intake camshaft and said difference of said exhaust camshaft is greater than or equal to a predetermined value.

### Claim 17 (depends on 15)

The system of claim 15 wherein said state determination module determines a steady state condition when an absolute value of at least one of said difference of said exhaust camshaft and said difference of said intake camshaft is less than said predetermined value.

### Claim 18 (depends on 14)

The system of claim 14 wherein said air estimation module calculates said estimated air value based on an absolute pressure of an intake manifold, an engine speed, an intake cam phaser position, an exhaust cam phaser position, and an estimated air temperature per cylinder when said transient condition is determined.

### Claim 19 (depends on 14)

The system of claim 14 wherein said air estimation module calculates said estimated air value based on a mass airflow sensor value and an engine speed when said steady state condition is determined.