JP2551639B2 - Intake air heating device for engine - Google Patents

Description

TECHNICAL FIELD The present invention relates to an intake air heating device for heating intake air of a diesel engine mounted on a vehicle or the like.

[Prior Art] In a diesel engine mounted on a vehicle or the like, a heater is provided in an intake passage to the engine to improve ignition performance when the engine is started in cold weather, and intake air is heated for a certain time before starting. To be done.

Further, there is an intake air heating device that heats intake air in order to stabilize the engine even after the engine is started.

The heating (after-heat) after starting this engine must be performed for a long time in cold weather, and in the conventional intake air heating device, a timer that starts the operation when the key switch is switched from the ST position to the ON position is provided. The heater is energized when the timer is operating and the L terminal of the regulator is open. In this afterheat, the timer automatically starts operating when the key switch is switched from the ST position to the ON position, so the intake air is heated when the temperature of the cooling water of the engine is equal to or higher than the predetermined temperature. In order to prevent this, a water temperature detection circuit that detects the cooling water temperature is provided, and the timer is not activated when the temperature is equal to or higher than a predetermined water temperature.

[Problems to be Solved by the Invention] As described above, in the conventional intake air heating device, afterheating is performed in conjunction with normal operation of the key switch, so that afterheating is not performed when unnecessary. Therefore, the water temperature detection circuit was required. Therefore, there is a problem that the circuit configuration becomes complicated and the price of the intake air heating device becomes high.

An object of the present invention is to provide an intake air heating device for an engine, which has a simple circuit configuration and is capable of afterheating for a long time.

[Means for Solving the Problems] The present invention relates to a heater provided for heating intake air in an intake passage to an engine, and a switch operated by a user without opening / closing a contact by a starting operation of the engine. A first timer that starts operation when the switch is operated and operates for a first predetermined time, and an operation that starts when the L terminal of the regulator opens during operation of the first timer, The technical means including a second timer that operates for a predetermined time of 2 and an energizing circuit that energizes the heater during operation of the first timer or the second timer is adopted.

[Operation] In the intake air heating device for an engine of the present invention, when preheating before starting the engine is required in cold weather or the like, the first timer starts operating when the switch is operated by the user, The intake circuit preheats the intake air.

While the heater is energized for the first predetermined time with the operation of the first timer, the engine is started and the engine is started, and when the L terminal of the regulator is opened, the second timer is activated. Start operation.

Therefore, the heater is energized for the second predetermined time thereafter, and afterheating is performed.

[Advantages of the Invention] In the present invention, when preheating and afterheating are necessary, afterheating can be performed only when the user arbitrarily operates the switch to start the engine.

Therefore, with a simple circuit configuration, afterheating can be performed for a long time depending on the setting of the second predetermined time.

Further, afterheat is limited to when the engine is started, and therefore the heater is not energized and overheated when the engine is not inhaled and is not started.

EXAMPLES Next, the present invention will be described based on examples.

The intake air heating device 1 of the present embodiment shown in FIG. 1 is disposed in an intake pipe (not shown) of a direct injection diesel engine for a large truck and is connected in series with three heating elements 2, 3, 4 for heating intake air. The controller H includes a heater H, a relay 5 for energizing the heater H, and a controller 10.
Reference numeral 10 drives and controls the relay 5 based on the operation state of the key switch 6 and a signal from the L terminal 7 of the regulator which notifies the start of the engine.

When the battery switch 8 is closed, the control device 10
The battery B (power supply voltage 24V) mounted on the vehicle operates by the electric power applied to and supplied to the terminal 10a and the terminal 10b.
Is grounded.

The heater H connected in series is connected between the contact 5a of the relay 5 and the ground electrode E, and when the relay 5 is driven to close the contact 5a, the current from the battery B is supplied to the heater H.

The control device 10 includes a first timer 11 and a second timer 12 for setting operating conditions of the relay 5, a relay drive circuit 13 for driving the relay 5, each timer 11, 12 and an L terminal 7 of the regulator. Relay drive circuit 13 according to the signal from
It is composed of a plurality of logic circuits for controlling.

The first timer 11 is a preheat before starting the engine.
A timer for setting the time, HEAT of the key switch 6
When the signal from the position is input and the key switch 6 is once switched from the OFF position to the HEAT position, a high level is output, and thereafter, even if the key switch 6 is switched to another position, the first preset value is set. High level is output continuously for a predetermined time T1.

The output terminal of the first timer 11 is connected to one input terminal of the AND circuit 20 and one input terminal of the OR circuit 21.

The other input terminal of the AND circuit 20 is L of the regulator.
It is connected to the power source side of the terminal 7 via a charge lamp for notifying the start of the engine, and when the engine is started, a high level signal is input.

The L terminal 7 of the regulator is also connected to one input terminal of the AND circuit 22. The output terminal of the AND circuit 20 is connected to the input of the second timer 12.

The second timer 12 outputs a high-level signal once the high-level signal is input from the AND circuit 20, and thereafter, even if the signal from the AND circuit 20 is inverted to the low level, the preset second timer 12 is output. The high level is continuously output for a predetermined time T2 of 2. The output terminal of the second timer 12 is connected to the other input terminal of the AND circuit 22.

The AND circuit 22 outputs its output from a high level to a low level when the engine is stopped and the L terminal 7 of the regulator is closed in order to stop the energization of the heater H when the engine once started is stopped. Invert to level. The output terminal of the AND circuit 22 is connected to the other input terminal of the OR circuit 21.

The OR circuit 21 outputs a high level when either the output signal of the first timer 11 or the output signal of the AND circuit 22 is at a high level. The output terminal of the OR circuit 21 is connected to the input terminal of the relay drive circuit 13.

The relay drive circuit 13 drives the relay 5 according to the output signal from the OR circuit 21, and closes the contact 5a when the output signal of the OR circuit 21 is at a high level.

Next, the operation of the intake air heating device 1 of the present embodiment having the above configuration will be described based on FIG. 2 and FIG.

In cold weather, heating of the intake air is required, so time t1
Then, the driver switches the key switch 6 to the HEAT position.

Then, the first timer 11 starts operating and its output signal is inverted from low level to high level.

In response to this, the relay 5 is driven, the contact 5a is closed, the heater H is energized, and preheating is performed.

After that, the key switch 6 is pushed by the driver to the CFF position, O
The ST position is switched via the N position, and the engine is cranked.

At time t2 during operation of the first timer 11, when the engine is started and the L terminal 7 of the regulator is opened, the signal is an AND circuit.
The second timer 12 starts to operate when input to 20.

At time t3, even if the output signal of the first timer 11 is inverted to the low level after the lapse of the first predetermined time T1 which is the operating time of the first timer 11, the output signal of the second timer 12 is set to the high level. Therefore, the relay 5 is continuously driven, the heater H is continuously energized, and the time t4 when the second predetermined time T2 elapses.
Heat the intake air up to.

When the engine is stopped while the heater H is being energized by the second timer 12, the L terminal 7 of the regulator is closed as shown by the alternate long and short dash line, and the AND circuit 22
Since a low level signal is input, the output signal of the AND circuit 22 becomes low level, the driving of the relay 5 is stopped, and the energization of the heater H is stopped. Therefore, since the heater H is not continuously energized when the engine is stopped and there is no intake air into the engine, damage to the heater H and consumption of the battery B can be eliminated.

As a method of stopping the energization by the second timer 12 when the engine is stopped, other than the method by the AND circuit 22,
The operation itself of the second timer 12 may be ended.

When the key switch 6 that has been switched to the HEAT position by the driver is left in the HEAT position as it is, only the preheating is performed for the first predetermined time T1 as shown by the broken line.

When the cooling water temperature of the engine is 0 ° C. or higher, heating of the intake air is not normally required, so as shown in FIG. 3, the key switch 6 is not set to the HEAT position and the engine is cranked. It Therefore, since the first timer 11 and the second timer 12 do not operate, the relay 5 does not operate and the heater H is not energized.

As described above, in the present invention, only by performing the preheating operation before the engine is started, the long-time afterheating required in cold weather is automatically performed by the driver by a simple circuit configuration, regardless of the operation. Can be terminated. Therefore, startability can be significantly improved.

In the present embodiment, the switch that is arbitrarily operated by the driver is provided in a part of the key switch, but a normally open type switch may be provided separately.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of an intake air heating apparatus for an engine of the present invention, and FIGS. 2 and 3 are time charts for explaining the operation of this embodiment. In the figure, H ... Heater, 6 ... Key switch (switch), 11 ... First timer (first timer), 12 ... Second
Timer (second timer), 13 ... Relay drive circuit (energization circuit).

Claims (1)

(57) [Claims] Claim: What is claimed is: 1. A heater provided for heating intake air in an intake passage to an engine, a switch which is not opened and closed by a starting operation of the engine and is operated by a user, and the switch is operated. A first timer which starts operation when the first timer operates for a first predetermined time, and a second timer which starts operation when the L terminal of the regulator opens during the operation of the first timer and operates for a second predetermined time. And an energizing circuit that energizes the heater during operation of the first timer or the second timer.