JPH0454832B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an energization control device for a glow plug used to assist in starting an engine.

[Prior Art] As shown in Fig. 2, a conventional glow plug energization control device includes a battery BAT as a power source, a glow plug G for rapid temperature increase installed in a sub-combustion chamber,
Provided between the battery BAT and the glow plug G for rapid temperature rise, there is a non-energized OFF terminal, an ON terminal for energizing the glow plug G, and a glow plug G.
and a key switch S having an ST terminal for energizing the starter motor, and a relay 1 for rapid temperature increase consisting of a normally open contact 1a and a coil 1b for supplying a large current for the purpose of rapidly increasing the temperature of the glow plug G. , a temperature maintenance device consisting of a normally open contact 2a and a coil 2b for passing a limited current through a current limiting resistor 3 in order to maintain the temperature after the glow plug G has risen to a predetermined temperature. The energization control device 4 includes an energization relay 2 and a energization control device 4 for the glow plug G for controlling the relay 1 and the relay 2. The energization control device 4 includes an energization control timer 5 for controlling the energization of the relay 1, and The energization control timer 5 has a key switch S.
The voltage applied from the glow plug detection terminal A, which detects the voltage of the glow plug G, is charged to the capacitor C1 for determining the timer operation time, and during charging, the comparator Cp is Generates a high level output and energizes coil 1b of relay 1 to glow plug G.
When charging of the capacitor C1 is completed, the output of the comparator Cp is set to low level, the coil 1b of the relay 1 is de-energized, and the supply of large current to the glow plug G is stopped. If the lead wire A1 connecting the glow plug G and the glow plug detection terminal A to detect the voltage of the glow plug G is not input due to a poor contact of the coupler or a disconnection of the wire harness, the capacitor C1 will not be charged. Conventionally, voltage is constantly applied to glow plug detection terminal A through resistor Ra and lead wire Rb, and when glow plug detection terminal A is open, voltage is applied to glow plug detection terminal A through resistor Ra. A voltage is applied and the capacitor C1 is charged with the power supply voltage,
This prevents the glow plug G from melting.

[Problems to be solved by the invention] In the conventional technology shown above, the key switch S is
Since the glow plug detection terminal A and the power supply are always energized through the resistor Ra while the ON terminal is being turned on, after the energization control timer 5 times up (relay 1
(When not energized) Resistor Ra always consumes power. In addition, since the resistor Ra is constantly energized while the ON terminal is turned on, it is necessary to increase the power capacity so that the resistor Ra does not generate heat, and as a result, the shape of the resistor Ra has been made large.

The purpose of the present invention is to enable the resistor Ra to be rated for a short time, to be small in size, and to
The purpose of the present invention is to provide a glow plug energization control device that solves problems such as Ra heat generation.

[Means for Solving the Problems] In order to solve the above problems, the present invention provides a capacitor, a glow plug terminal voltage input terminal connected to a terminal portion of the glow plug by a lead wire,
a charging circuit connected from the terminal to the capacitor via a resistor and charging the capacitor in a glow plug terminal voltage-dependent manner; and a resistor dividing point voltage between the input voltage of the capacitor and the output voltage of the constant voltage circuit. a comparator that inputs the voltage, an amplifier that amplifies the output of the comparator, and an output terminal of the amplifier and the glow plug terminal voltage input terminal,
A configuration including a detection terminal voltage application circuit connected via a diode and a resistor was adopted.

[Operations and Effects of the Invention] The glow plug energization control device of the present invention having the above configuration can be used in the event of an accident such as disconnection of the lead wire connecting the terminal portion of the glow plug and the glow plug terminal voltage input terminal. Also, the output terminal of the amplifier and the glow plug terminal voltage input terminal are connected via a diode and a resistor so that appropriate current can be applied to the glow plug.

Therefore, the resistor consumes power only during the glow plug energization signal generation period, can be rated for a short time, and can be made smaller.

[Embodiment] Next, a glow plug energization control device of the present invention will be described based on an embodiment shown in the drawings.

FIG. 1 is an electric circuit diagram showing an embodiment of the glow plug energization control device of the present invention.

BAT is the battery that is the power source, G is the glow plug for rapid temperature rise installed in the auxiliary combustion chamber, and S is the battery.
Inserted between BAT and glow plug G, OFF
a key switch having a terminal, an ON terminal for energizing the glow plug G, and an ST terminal for energizing the glow plug G and the starter motor;
1 is a normally open contact 1a and a coil 1b for supplying a large current for the purpose of rapidly raising the temperature of the glow plug G.
2 is a glow plug G.
A temperature maintenance energizing relay 4 consisting of a normally open contact 2a and a coil 2b for passing a limited current through a current limiting resistor 3 in order to maintain the temperature after the temperature has risen to a predetermined temperature. is the relay 1
and glow plug G to control relay 2
This is an energization control device.

The energization control device 4 turns on the relay 1 for a set time after the key switch S is turned on to the ON terminal.
The energization control timer 5 and the relay 2 are turned on under specified conditions even after the engine has started, reducing exhaust smoke,
It consists of an afterglow timer 6 that performs so-called afterglow for the purpose of rotational stability, and the energization control timer 5 has a glow plug detection terminal A that detects the voltage applied to the glow plug G. a capacitor C1, a comparator Cp inputting the charging voltage of the capacitor C1;
A time-limiting circuit 51, which consists of resistors R1 to R10, diodes D1 to D4, and Zener diodes Z1 to Z3, generates a high-level output for a certain period of time while the capacitor C1 is being charged after the key switch S is turned on to the ON terminal, and an amplifier. AMP1, resistor R11,
Transistor Tr, diodes D5, D6, coil Co1 which is interrupted by the operation of transistor Tr
A relay energizing circuit 52 that energizes the relay 1 only when receiving the high level output of the time limit circuit 51, which is composed of a relay R1 consisting of a normally open contact J1, and the output position of the amplifier AMP1 of the relay energizing circuit 52 and the glow plug detection terminal. A and resistor Ra, diode
Detection terminal voltage application circuit 53 connected via Da
The afterglow timer 6 produces a low level output while discharging the battery BAT,
A charge detection terminal 61 of the regulator that generates a high level output during charging, a water temperature sensor switch 62 that turns off when the engine coolant temperature is below a predetermined temperature, and a vehicle speed sensor switch 63 that turns off when the vehicle is stopped. As an input, for example, a logic circuit 64 that operates the relay 2 when the coolant temperature is below a predetermined temperature, the vehicle speed is below a predetermined vehicle speed, and the voltage applied to the glow plug G is below a predetermined value, and the output of the logic circuit 64 are input. It consists of an amplifier AMP2 that amplifies the signal and activates the relay 2.

The above operation will be explained.

When the key switch S is connected from the OFF terminal to the ON terminal, the time limit circuit 51 of the energization control timer 5 has the capacitor C1, which determines the time constant, discharged, and the charging voltage V1 of the capacitor C1 and the resistor R.
A comparator Cp compares the reference voltage V2 determined by R7 and R8, and produces a high level output while the capacitor C1 is being charged. As a result, the output of the comparator Cp applies a voltage to the base of the transistor Tr of the relay energizing circuit 52 via the amplifier AMP1, energizing the collector and emitter of the transistor Tr, energizing the coil Co1, and closing the normally open contact J1. Relay 1 is turned ON to raise the temperature of glow plug G to a predetermined temperature range required for smooth engine starting, thereby facilitating engine starting.

Afterglow timer 6 is controlled by relay 2.
Current limiting resistor 3 is used to stabilize combustion immediately after engine startup, stabilize rotation, reduce smoke emissions, etc.
Turn on relay 2 via and energize the glow plug.

Here, if the glow plug voltage is not input to the glow plug detection terminal A due to poor contact of the coupler of the lead wire A1 applied to the glow plug detection terminal A, disconnection of the wire harness, etc., the time limit circuit 51 of the energization control timer 5 The output of the amplifier AMP1, which is output only during the timer operation time, is sent to the glow plug detection terminal A by the detection terminal voltage application circuit 53.
This charge causes the capacitor C1 to
After charging of capacitor C1 is completed,
Since the output of the amplifier AMP1 via the comparator Cp is set to a low level, it is not output to the glow plug detection terminal A.

[Brief explanation of the drawing]

FIG. 1 is an electric circuit diagram showing a glow plug energization control device of the present invention, and FIG. 2 is an electric circuit diagram showing a conventional glow plug energization control device. In the diagram, C1... Capacitor, Cp... Comparator, G... Glow plug, A1... Lead wire,
A...Glow plug detection terminal, R2...Resistor,
Ra...Resistor, Da...Diode.

Claims (1)

[Scope of Claims] 1. A capacitor, a glow plug terminal voltage input terminal connected to a terminal portion of the glow plug by a lead wire, and a voltage input terminal connected from the terminal to the capacitor via a resistor, and a a charging circuit that performs glow plug terminal voltage-dependent charging; a comparator that inputs the input voltage of the capacitor and a resistance division point voltage of the output voltage of the constant voltage circuit; and an amplifier that amplifies the output of the comparator; A glow plug energization control device comprising a detection terminal voltage application circuit that connects an output terminal of an amplifier and the glow plug terminal voltage input terminal via a diode and a resistor.