# US 2009/0268366 A1 · Method and an apparatus for controlling glow plugs in a diesel engine, particularly for motor-vehicles

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- Number: US 2009/0268366 A1
- Document ID: US20090268366A1
- Status: Published application
- Kind: A1
- Application number: 12/432,387
- Filed: 2009-04-29
- Published: 2009-10-29
- Earliest claimed: 2008-04-29
- Assignees: GM Global Technology Operations LLC
- Inventors: Paolo CASASSO; Angelo ARGENTO; Stefano NIEDDU
- Web page: https://patentgrep.com/patent/US20090268366A1

## CPC

- F02P 19/021: {characterised by power delivery controls}
- F02P 19/023: {Individual control of the glow plugs}
- F02P: IGNITION, OTHER THAN COMPRESSION IGNITION, FOR INTERNAL-COMBUSTION ENGINES; TESTING OF IGNITION TIMING IN COMPRESSION-IGNITION ENGINES ({anti-pollution means for internal-combustion engines F02B17/00}; specially adapted for rotary-piston or oscillating-piston engines F02B53/12; {ignition of gas turbine plants F02C7/26; ignition of jet propulsion plants F02K9/95; starting of combustion engines F02N9/00}; ignition of combustion apparatus in general, glowing plugs F23Q; measuring of physical variables in general G01; controlling in general G05; data processing in general G06; electrical components in general see Section H; {ignition coils H01F38/12}; sparking plugs H01T13/00)

## Abstract

A method is provided that includes, but is not limited to the steps of driving in an on-off manner in a period of time an electronic switch in series with a respective glow plug between the terminals of a d.c. voltage supply, sensing the glow plug voltage and the glow plug current, generating analogue sense signals representative of the time integral of the glow plug voltage and current, generating analogue reference signals corresponding to the digital values of corresponding control words, comparing the sense signals to the respective reference signals and modifying the corresponding control words so as to minimize the difference between the sense signals and the reference signals, calculating the average values of the sensed voltage and current on the basis of the values of the control words at the beginning and at the end of the “on” time of the electronic switch.

## Claims

### Claim 1

A method for controlling a glow plug associated with a cylinder chamber of a diesel engine, comprising the steps of:
driving in an on-off manner, in a period of time, an electronic switch connected essentially in series with the glow plug between terminals of a D.C. voltage supply;
sensing a voltage across the glow plug and a current flowing through the glow plug;
generating a first analog sense signal that is representative of a first time integral of a sensed current;
generating a second analog sense signal that is representative of a second time integral of a sensed voltage;
generating a first reference signal having a first analog value corresponding to a value of a first digital control word;
generating a second reference signal having a second analog value corresponding to a second digital control word;
comparing, while the electronic switch is in an on-state, the first analog sense signal and the second analog sense signal with the first reference signal and the second reference signal;
modifying a digital value of the first digital control word and the second digital control word to minimize a difference between the first analog sense signal and the second analog sense signal and the first reference signal and the second reference signal; and
calculating an average value of the sensed current and the sensed voltage over said period of time, as a function of the difference between the value of said first digital control word and the second digital control word at a beginning and at an end of the on-state or a conduction time of the electronic switch.

### Claim 2 (depends on 1)

The method of claim 1, wherein the average value of the sensed current over the period of time is computed by calculating a ratio of a second difference between the first digital control word at the beginning and at the end of the on-state or the conduction time of the electronic switch to a duration of the period of time.

### Claim 3 (depends on 1)

The method of claim 1, wherein the average value of the sensed voltage over the period of time is computed by calculating a ratio of the difference between values of the second digital control word at the beginning and at the end of the on-state or the conduction time of the electronic switch to a duration of said period of time.

### Claim 4 (depends on 1)

The method according to claim 1, wherein the electronic switch is driven by a PWM signal.

### Claim 5 (depends on 1)

The method according to claim 1, wherein the current flowing through the glow plug is sensed with a shunt resistor.

### Claim 6

An apparatus for controlling a glow plug associated with a cylinder chamber of a diesel engine, comprising:
an electronic switch connected essentially in series with the glow plug between terminals of a D.C. voltage supply;
a sensor adapted to provide a first analog sense signal and a second analog sense signal representative of a current flowing through the glow plug and a voltage across the glow plug; and
an electronic controller coupled to a control input of the electronic switch and to the sensor, the electronic controller adapted to:
drive in an on-off manner the electronic switch;
generate the first analog sense signal that is representative of a first time integral of a sensed current;
generate the second analog sense signal that is representative of a second time integral of a sensed voltage;
generate a first reference signal having a first analogue value corresponding to a value of a first digital control word;
generate a second reference signal having a second analogue value corresponding to a second digital control word;
compare, while the electronic switch is in an on-state, the first analog sense signal and the second analog sense signal with the first reference signal and the second reference signal;
modify a digital value of the first digital control word and the second digital control word to minimize a difference between the first analog sense signal and the second analog sense signal and the first reference signal and the second reference signal; and
calculate an average value of the sensed current and the sensed voltage over a period of time, as a function of the difference between the value of said first digital control word and the second digital control word at a beginning and at an end of the on-state or a conduction time of the electronic switch.

### Claim 7 (depends on 6)

The apparatus of claim 6, wherein the electronic controller is adapted to compute the average value of the sensed current over the period of time by calculating a ratio of the difference between values of said first digital control word at the beginning and at the end of the on-state or the conduction time of the electronic switch to a duration of said period of time.

### Claim 8 (depends on 6)

The apparatus according to claim 6, wherein the electronic controller is adapted to compute the average value of the sensed voltage over the period of time by calculating a ratio of the difference between values of said second digital control word at the beginning and at the end of the on-state or the conduction time of the electronic switch to a duration of the period of time.

### Claim 9 (depends on 6)

The apparatus according to claim 6, wherein the electronic controller is adapted to drive the electronic switch with a PWM signal.

### Claim 10 (depends on 6)

The apparatus according to claim 6, wherein the sensor comprises a shunt resistor.