Method and system for controlling the energization of at least one glow plug in an internal combustion engine

• US 5,158,050 A
• Filed: 09/11/1991
• Issued: 10/27/1992
• Est. Priority Date: 09/11/1991
• Status: Expired due to Term

• Current Assignee: Detroit Diesel Corporation (Daimler Truck Holding AG)
• Original Assignee: Detroit Diesel Corporation (Daimler Truck Holding AG)
• Inventors: Hawkins, Jeffrey S., Tasky, David P., Telmet, Juhan
• Primary Examiner(s): WOLFE JR, WILLIS RAY
• Application Number:
  US07/757,724
• Time in Patent Office: 412 Days
• Field of Search: 123/179.21, 123/145 A, 219/497, 219/507, 219/508, 219/509
• US Class Current: 123/145.00A
• CPC Class Codes: F02B 3/06 with compression ignition compression ignition engines using air or gas for blowing fuel into compressed air in cylinder F02B13/02
• CPC Class Codes: F02P 19/022 using intermittent current supply
• CPC Class Codes: F02P 19/023 Individual control of the glow plugs
• CPC Class Codes: F02P 19/027 Safety devices, e.g. for diagnosing the glow plugs or the related circuits

Abstract

A method and system are provided for controlling the energization of at least one glow plug in an internal combustion engine wherein a solid state drive circuit, including a semiconductor switch, is utilized for applying an energizing current to the at least one glow plug from a voltage source based on a control signal to electrically heat the at least one glow plug. The control signal is preferably a 50 Hz switched ground duty cycle signal from an electronic control module (ECM). Based on the duty cycle input, the drive circuit for each of the glow plugs supplies current from a main feed bus. A glow plug current monitoring circuit is provided for each of the glow plugs to detect whenever an open or short circuit condition appears in any of the glow plugs. The semiconductor device preferable is a current sensing type of MOSFET called a SENSEFET. Each SENSEFET internally monitors individual current draw of its respective glow plug to verify its proper operation. Upon detecting an out-of-limit condition of a glow plug, the drive circuit for the particular glow plug is disabled to protect the drive circuit and a diagnostic circuit in enabled to indicate this fault mode through an indicator lamp and starter inhibit relay driver circuit. Because the drive circuit for that particular glow plug is disabled, it does not sustain damage and resumes proper operation when a "good" glow plug is installed for the "bad" glow plug.

Claims

1. A method for controlling the energization of at least one glow plug in an internal combustion engine of a vehicle including a voltage source having a predetermined voltage, the method comprising the steps of:

monitoring the temperature of the engine;

generating an input control signal based on the temperature of the engine;

providing a semiconductor switch to apply an energizing current to the at least one glow plug from the voltage source based on the control signal to thereby electrically heat the at least one glow plug;

generating a feedback signal as a function of the energizing current;

determining an electrical property of the at least one glow plug based on the feedback signal; and

preventing the application of the energizing current to the at least one glow plug in an out-of-limit condition of the electrical property.

2. The method of claim 1 further comprising the steps of conditioning the input control signal to obtain a conditioned control signal, the energizing current being based on the conditioned control signal;

and providing a signal indicating the out-of-limit condition of the electrical property.

3. The method of claim 1 wherein the step of generating the feedback signal is accomplished by the semiconductor switch.

4. The method of claim 3 wherein the semiconductor switch is a metal oxide silicon field effect transistor.

5. The method of claim 4 wherein the metal oxide silicon field effect transistor is a SENSEFET for providing the feedback signal.

6. The method of claim 1 wherein a plurality of glow plugs are controlled and wherein the step of sensing includes the step of sensing the energizing current to each of the plurality of glow plugs.

7. The method of claim 1 wherein the input control signal has a duty cycle.

8. The method of claim 7 further comprising the step of determining the predetermined voltage of the voltage source and wherein the duty cycle of the input control signal is based on the predetermined voltage.

9. The method of claim 8 wherein the duty cycle of the input control signal is substantially constant.

10. A system for controlling the energization of at least one glow plug in an internal combustion engine of a vehicle including a voltage source having a predetermined voltage, the system comprising:

means for monitoring the temperature of the engine;

means for generating an input control signal based on the temperature of the engine;

a drive circuit including a semiconductor switch for applying an energizing current to the at least one glow plug from the voltage source based on the control signal to electrically heat the at least one glow plug;

means for generating a feedback signal as a function of the energizing current;

means for determining an electrical property of the at least one glow plug based on the feedback signal; and

means for disabling the drive circuit to prevent the application of the energizing current to the at least one glow plug in an out-of-limit condition of the electrical property.

11. The system of claim 10 further comprising means for conditioning the input control signal to obtain a conditioned control signal, the energizing current being based on the conditioned control signal;

and means for generating a signal indicating the out-of-limit condition of the electrical property.

12. The system of claim 10 wherein the means for generating the feedback signal is defined by the semiconductor switch.

13. The system of claim 12 wherein the semiconductor switch is a metal oxide silicon field effect transistor.

14. The system of claim 13 wherein the metal oxide silicon field effect transistor is a SENSEFET for providing the feedback signal.

15. The system of claim 10 wherein a plurality of glow plugs are controlled.

16. The system of claim 10 wherein the input control signal has a duty cycle.

17. The system of claim 16 further comprising means for determining the predetermined voltage of the voltage source and wherein the duty cycle of the input control signal is based on the predetermined voltage.

18. The system of claim 17 wherein the duty cycle of the input control signal is substantially constant.