Control apparatus for glow plugs provided for a diesel engine

• US 4,300,491 A
• Filed: 06/29/1979
• Issued: 11/17/1981
• Est. Priority Date: 06/30/1978
• Status: Expired due to Term

• Current Assignee: Diesel Japan Company Limited (Renzo Rosso)
• Original Assignee: Diesel Japan Company Limited (Renzo Rosso)
• Inventors: Yamada, Tsutomu, Hara, Toshizo
• Primary Examiner(s): Myhre, Charles J.
• Assistant Examiner(s): Dolinar, Andrew M.
• Application Number:
  US06/053,422
• Time in Patent Office: 872 Days
• Field of Search: 123/179 BG, 123/179 B, 123/179 H, 123/145 A
• US Class Current: 123/179.6
• 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 19/02 electric, e.g. layout of circuits of apparatus having glowing plugs

Abstract

A control apparatus for glow plugs provided for a diesel engine is disclosed, in which the time for preheating of glow plugs prior to starting of the engine, that is, the time for applying an electric current to the glow plugs from a battery, is controlled according to such factors as engine temperature and battery voltage. When the engine is cold, control is carried out so that as the engine temperature is lower or the battery voltage is lower, the preheating time is more prolonged. Accordingly, an optimum preheating time is ensured. When the engine is warmed up, control is carried out so that even is a key switch is set at a preheating position, preheating is not effected whatsoever.

Claims

1. Control apparatus for glow plugs of a preheating device provided for preheating a diesel engine comprising:

a power supply;

a first relay having an ON-OFF relay switch for applying a voltage from said power supply to the glow plugs;

a key switch connected to said power supply and having an OFF position, an ON position in which a preheating contact is closed for preheating, and a START position in which the preheating contact and a starter contact are both closed for starting the diesel engine;

a second relay connected to said preheating contact and having an ON-OFF relay switch connected to the first relay;

a thermistor for generating a temperature voltage which corresponds to a temperature of diesel engine cooling water;

a first resistor and a zener diode connected to said preheating contact;

a first transistor receiving a zener voltage of the zener diode to a base terminal thereof;

a second and a third resistor for dividing said zener voltage;

a condenser connected between a collector terminal of the first transistor and a connection point of the second and the third resistors;

a comparator having two input terminals, a first one of said terminals being connected to said thermistor and a second one of said terminals being connected to said condenser, said preheating contact being connected to said second one of said terminals through a fourth resistor, said starter contact being connected to said second one of said terminals through a first diode and fifth resistor, respectively;

a second diode connected between said starter contact and an output of said comparator;

a sixth and a seventh resistor connected to the output of said comparator;

a second transistor for exciting said second relay by inputting a dividing voltage of the sixth and the seventh resistors;

a third diode and an eighth resistor connected between an emitter terminal of the first transistor and the glow plugs;

a fourth diode and a ninth resistor connected between the collector terminal of the first transistor and a collector terminal of the second transistor; and

a pilot lamp connected in parallel to the glow plugs;

wherein the first relay is ON-OFF controlled by the ON-OFF relay switch of the second relay, and the ON-OFF relay switch of the first relay ON-OFF controls to apply voltage of the power supply to the glow plugs, thereby to control a preheating time of the glow plugs depending on the temperature of said diesel engine cooling water and a terminal voltage of the glow plugs when said key switch is operated at the ON position or the START position.