# US 4,377,138 A · Glow plug control system for diesel engine

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- Number: US 4,377,138 A
- Document ID: US4377138A
- Status: Granted
- Kind: A
- Application number: 06/240,061
- Filed: 1981-03-03
- Granted: 1983-03-22
- Earliest claimed: 1980-03-03
- Assignees: Mitsubishi Denki Kabushiki Kaisha
- Inventors: Tateki Mitani; Akira Demizu
- Web page: https://patentgrep.com/patent/US4377138A

## CPC

- F02P 19/025: {with means for determining glow plug temperature or glow plug resistance}
- F02P 19/022: {using intermittent current supply}
- G05D 23/2401: {using a heating element as a sensing element}
- F02B 3/06: with compression ignition (compression ignition engines using air or gas for blowing fuel into compressed air in cylinder F02B13/02)
- 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)
- G05D: SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
- F02B: INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL (gas-turbine plants F02C; hot-gas or combustion-product positive-displacement engine plants F02G)

## Abstract

A glow plug control system which includes a controller connected to a battery through an ignition switch, an indicator lamp and a glow plug relay connected to the controller and a parallel combination of four glow plugs connected to the battery through normally open contacts of the relay. The controller includes a comparator having its two inputs connected across the parallel glow plugs, and a constant current circuit for supplying a constant current to the parallel combination of the glow plugs for sensing the resistance of the glow plugs. The controller senses the resistance of the glow plugs due to their temperature through the comparator and permits the battery to supply a current to the parallel combination of the glow plugs for a time determined in response to the sensed resistance.

## Claims

### Claim 1

A glow plug control system comprising a group of glow plugs, a timer means, a constant current circuit and a constant voltage circuit for supplying a current to said group of glow plugs, said constant current circuit and said constant voltage circuit controlled by said timer, a sensor means for sensing a magnitude of resistance of said glow plugs due to a change in temperature thereof, and a control means responsive to said magnitude of resistance sensed by said sensor circuit to control a time interval of heating said glow plugs to thereby control temperature thereof, wherein said timer means selectively causes only one of said constant current circuit and said constant voltage circuit to supply current to said group of glow plugs at any time instant.

### Claim 2 (depends on 1)

A glow plug control system as claimed in claim 1, wherein said control means includes means responsive to a difference between a temperature of said glow plugs corresponding to said magnitude of resistance sensed by said sensor means and the desired temperature to control said time interval of heating of said glow plugs.