JPH0610810A - Engine intake air heating device - Google Patents

Abstract

(57) [Summary] [Purpose] To reliably prevent burnout of the glow plug relay device due to a failure of the key switch. A glow plug, which is energized by operating a key switch to an engine starting position to heat intake air, a glow plug relay device interposed in a biasing circuit of the glow plug, and a glow plug relay device. The switch device installed in the control solenoid energizing circuit and the output signal of the alternator driven in conjunction with the engine are received and compared with the reference value indicating the self-sustaining operation of the engine. A safety relay device is provided which has a comparator which closes the device and opens the switch device after self-sustaining operation of the engine.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake air heating device for improving cold startability of an engine, especially a diesel engine.

[0002]

As is well known in the art, in diesel engines for vehicles and various industrial applications, a glow plug for heating intake air to each cylinder of the engine in order to improve startability especially in cold weather. Many are equipped with.

The glow plug has a heat generating member that is energized by operating the engine operation control key switch to a starting position and a glow plug operating position. A glow plug relay device is installed because the initial current when energized is large.

The glow plug relay device includes a relay contact for connecting or disconnecting a power source and a glow plug, and a control solenoid for opening and closing the relay contact. The solenoid has one terminal thereof for starting the key switch. Position and the glow plug operating position, and the other terminal is grounded. Then, by operating the key switch to the starting position or the glow plug operating position, the solenoid is energized to close the relay contact, and a current flows through the glow plug to heat the intake air. In addition, the key switch is in an O position other than the starting position and glow plug operating position.
When operated to the FF position or the like, the solenoid is deenergized and the relay contact is opened so that no current flows through the glow plug.

However, conventionally, when the key switch is operated to the starting position to start the engine and then the key is turned off, the glow is caused by a key return failure or an internal contact failure of the key switch, which is extremely rare. The plug relay device may remain energized. In this case, in a relatively short time (usually about 10 minutes)
Due to the continuous energization, the glow plug relay device is burned.

[0006]

SUMMARY OF THE INVENTION The present invention was devised in view of the above circumstances, and automatically interrupts the energization of the glow plug relay device when the engine is successfully started and brought into a self-sustaining operation state. It is an object of the present invention to provide an intake air heating device for an engine, which is capable of reliably preventing burnout of the relay device.

[0007]

In order to achieve the above object, the present invention provides a glow plug which is energized by operating a key switch to an engine starting position to heat intake air, and an energizing circuit of the glow plug. An intervening glow plug relay device, and a switch device interposed in a control solenoid energizing circuit of the glow plug relay device;
It receives the output signal of the alternator driven in conjunction with the engine and compares it with the reference value that indicates the engine's self-sustaining operation.
An intake air heating device for an engine is proposed, which is equipped with a safety relay device having a comparator that closes the switch device when the engine is started and opens the switch device after the engine is operated independently. It is a thing.

[0008]

Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. In the figure, reference numeral 10 is a key switch for controlling the operation of a diesel engine (not shown), 12 is a glow plug attached to each cylinder of the engine, 14 is a battery as a power source, 16 is a glow plug relay device,
18 is an alternator driven in conjunction with the engine, 2
Reference numeral 0 indicates a safety relay device, 22 indicates a starter device of the engine as a whole, and the starter device 22 has a normal structure including a starter and a starter relay.

The key switch 10 is, as shown in the drawing,
A B terminal connected to the battery 14 and one relay contact 24a of the glow plug relay device 16, and a control solenoid 26 in the glow plug relay device 16.
A glow plug actuating contact R ₁ , connected to one terminal of
And an AC terminal connected to the regulator terminal R of the alternator 18 and a C terminal connected to the starter device 22. And the key of the switch is (H
When it is operated to the EAT position, the B terminal and the R ₁ terminal are connected, and when the key is in the (ON) position, the above B
The terminal and AC terminal are connected, and the same key
When T) is operated to the position, B terminal is connected to R ₁ terminal, the AC terminal and the C terminal.

The other relay contact 24b connected to the glow plug 12 of the glow plug relay device 16 and the one relay contact 24a are opened and closed by a movable contact 24C driven by a solenoid 26. That is,
The relay contacts 24a and 24b are the same as the solenoid 26.
When the solenoid 26 is deenergized, the circuit is opened, and when the solenoid 26 is energized, the circuit is closed.

The other terminal of the solenoid 26 is connected to the ground terminal E through the transistor switch device 28 of the safety relay device 20. The same switch device 2
Opening / closing of 8 is controlled by a comparator or a comparator 30 provided in the safety relay device 20. The comparator 30 receives an output signal indicating the number of revolutions of the alternator supplied from the terminal P of the alternator 18, and compares the output signal with a reference value indicating a state in which the engine has been successfully started and can be operated independently. , To provide a control output to the switch device 28.

The output signal of the alternator 18 is taken into the safety relay device 20 as a pulse output indicating the number of revolutions and then converted into a voltage, which is a reference voltage indicating the self-sustained operation of the engine built in the relay device 20. Is preferably compared with. Further, the switch device 28 is closed until the engine is successfully started and shifts to the self-sustaining operation, grounds the other terminal of the solenoid 26, and when the engine shifts to the self-sustaining operation, the output of the comparator 30 is generated. It is opened.

In the above structure, when the key switch 10 is operated to the START position when the engine is started, one terminal of the control solenoid 26 in the glow plug relay device 16 is connected to the power source 14 and the other terminal is safe. Since it is grounded through the switch device 28 of the relay device 20, the solenoid 26 is energized. Since the movable contact 24c is driven by the bias of the solenoid 26 and the relay contacts 24a and 24b are connected,
A large current is supplied from the power supply 14 to the glow plug 12.
When the glow plug 12 is energized, the intake air supplied into each cylinder of the engine is heated, and the startability is improved especially at low temperature starting.

On the other hand, the starter device 22 operates in a known manner to start the engine. When the engine successfully starts and shifts to the self-sustaining operation, the switch device 28 is opened by the output of the comparator 30 in the safety relay device 20 which receives the output signal of the alternator 18 which is driven in conjunction with the engine. When the switch device 28 is opened, the solenoid 26 is deenergized and the relay contacts 24a and 24
Since the connection of b is cut off, the energization of the glow plug 12 is stopped.

Therefore, the start of the key switch 10 (STA
Even if the B terminal and the R ₁ terminal are electrically connected even though the key is returned due to a poor return from the (RT) position or a failure inside the switch, the solenoid is activated by the operation of the safety relay device 20. Since 26 is surely deenergized, the glow plug relay device 16 can be prevented from being burned.

[0016]

As described above, in the intake air heating apparatus for an engine according to the present invention, the glow plug which energizes the intake air by operating the key switch to the engine starting position, and the bias circuit of the glow plug. A relay device for a glow plug interposed in the interior, and a switch device interposed in a control solenoid energizing circuit of the relay device for the glow plug,
It receives the output signal of the alternator driven in conjunction with the engine and compares it with the reference value that indicates the engine's self-sustaining operation.
A glow plug based on a key switch failure or the like, comprising a safety relay device having a comparator that closes the switch device when the engine is started and opens the switch device after the engine is operated independently. Since it is possible to reliably prevent the relay device from burning out,
Industrially beneficial.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention.

[Explanation of symbols]

10 ... Key switch, 12 ... Glow plug, 14 ... Power supply, 16 ... Glow plug relay device, 18 ... Alternator, 20 ... Safety relay device

Claims (1)

[Claims] 1. A glow plug that is energized by operating a key switch to an engine starting position to heat intake air, a glow plug relay device interposed in a biasing circuit of the glow plug, and a glow plug. A switch device interposed in the control solenoid energizing circuit of the relay device,
It receives the output signal of the alternator driven in conjunction with the engine and compares it with the reference value that indicates the engine's self-sustaining operation.
An intake air heating device for an engine, comprising a safety relay device having a comparator that closes the switch device when the engine is started and opens the switch device after the engine is operated independently.