JPS6115259Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for a continuously energized air heater provided in an intake passage of an internal combustion engine.

Internal combustion engines, especially compression ignition internal combustion engines such as diesel engines, are sometimes equipped with a continuously energized air heater in the engine's intake passage to improve startability in cold weather and drivability immediately after startup. .

In this type of electric air heater, the time for heating before engine startup (hereinafter referred to as preheat) and heating immediately after engine startup (hereinafter referred to as afterheating) are set appropriately using timers, etc. In order to prevent white smoke during operation, afterheating should be continued for an extremely long time (until the end of warm-up).
It is preferable to do this over several days.

However, since the capacity (power consumption) of the air heater is generally increased in order to shorten the preheating time, if the afterheating is performed for a long time using this air heater, overdischarging of the battery and overheating of the heater relay may occur. Conventionally, afterheating is interrupted during warm-up because there is a risk of overheating of the heating and power supply cables. For this reason, warm-up performance deteriorated, and in particular, there was a drawback that white smoke emission during warm-up operation could not be completely prevented.

The present invention was developed in view of the above-mentioned drawbacks.The air heater is automatically activated for a set period of time before and after the engine starts to heat the intake air, but after the engine starts, the current supplied to the air heater is reduced. The purpose of the present invention is to provide an air heater control device that enables long-term afterheating, thereby improving warm-up operability and preventing white smoke emission.

The present invention will be explained in detail below based on embodiments shown in the drawings.

Fig. 1 is a schematic plan view of the engine showing how the air heater is installed, Fig. 2 is an electric circuit diagram showing one embodiment of the invention, and Fig. 3 is an electric circuit diagram showing another embodiment of the invention. be.

In FIG. 1, first and second air heaters 3 and 4 are installed in series along the flow direction of intake air at a gathering part of an intake manifold 2 provided in an engine body 1. The first air heater 3 is connected to the battery 6 via the normally open contact 5a of the heater relay 5, as shown in FIG.
is connected to the battery 6 via the normally closed contact 7a of the relay 7 and the normally open contact 5a of the heater relay 5. The coil 5b of the heater relay 5 is connected to the battery 6 via a timer unit 8 equipped with a timer circuit and a main switch 9 which is switched and controlled in conjunction with a key switch (not shown), as in the conventional case. 7b is connected to an engine-driven generator 10 via a voltage regulator (not shown).

In such a configuration, when the engine is stopped, the generator 10 is stopped and the coil 7b of the relay 7 is not energized, so when the key switch is switched to the preheat position and the timer unit 8 is activated, the timer unit 8 is activated for a predetermined time or , the coil 5b of the heater relay 5 is energized for a predetermined time determined according to the engine temperature or outside temperature, etc., and its contact 5a is closed, so that the terminal voltage of the battery 6 is applied to both air heaters 3 and 4. Both of these air heaters 3 and 4 are electrically heated to perform preheating.

After confirming that preheating has been completed via a pilot lamp (not shown), etc., when the key switch is switched to the starting position, the main switch 9
continues to close and afterheating begins in the same way as for the plate. Even if the key switch is returned from the starting position to the operating position after the engine has been started, the coil 5b of the heater relay 5 continues to be energized by the operation of the timer unit 8, and both air heaters 3 and 4 attempt to be heated by electricity. However, when the engine is started, the generator 10 operates and excites the coil 7b of the relay 7, so that its contact 7a is opened. Therefore, after starting the engine, only the first air heater 3 continues to operate, and the second air heater 4 stops. When the second air heater 4 stops, the power consumption (current current) of the entire air heater is reduced, so even if after-heating is performed for a long period of time, over-discharge of the battery 6 and contact 5a of the heater relay 5 and air heater There is no risk of overheating of the power supply cable. Note that as the second air heater 4 stops, the temperature rise of the intake air becomes smaller, but after the engine starts, the rotational speed of the engine increases dramatically compared to before starting. Since the rate of temperature rise is higher, the combustibility of the engine can be maintained.

In the above embodiment, one of the air heaters is stopped at the same time as the engine starts.
As shown in FIG. 3, a relay 7 operates in the same manner as described above between both air heaters 3, 4 and heater relay 5.
By short-circuiting the contacts 7a of the relay 7 via the control resistor 11, even if the current flow to the air heaters 3 and 4 after startup is reduced, the power consumption can be reduced significantly. It may be reduced.

In addition, although the above embodiment uses two air heaters, it is possible to use a larger number of air heaters to finely control the amount of heat generated during afterheating and preheating, or to adjust the amount of heat generated during afterheating depending on external conditions. The amount of heat generated may be changed in stages. In general, as mentioned above, the preheat time may be determined depending on the temperature or the like, but the afterheat time may be determined depending on the preheat time or the warm-up state of the engine. Preferably, at the end of warm-up,
The timer unit may be set to continue afterheating at least until there is no possibility of white smoke being emitted.

As explained above, according to the present invention, even if a large-capacity air heater is installed in order to shorten the preheating time, the silencing power of the air heater is automatically reduced after the engine starts, so the silencing power of the air heater is automatically reduced until the warm-up operation is completed. Even if you try to continue intake air heating (afterheat),
This can prevent battery over-discharge or overheating of control equipment. As a result, it is possible not only to ensure the same startability as in the past, but also to improve warm-up performance, and at the same time, to reliably prevent white smoke that tends to be emitted during warm-up operation. Further, once the engine key switch is set to the preheat position, the air heater is automatically activated for the set time even if the key switch is operated thereafter, which has the advantage of being easy to operate.

[Brief explanation of the drawing]

The figures show a control device for an air heater according to the present invention, in which Fig. 1 is a schematic plan view of the engine showing how the air heater is installed, Fig. 2 is an electric circuit diagram of one embodiment, and Fig. 3 is a FIG. 6 is an electrical circuit diagram of another embodiment. 1...Engine body, 2...Intake manifold,
3, 4...Air heater, 5...Heater relay, 6
... battery, 7 ... relay, 8 ... timer unit, 9 ... main switch, 10 ... generator, 11 ... control resistor.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) In an internal combustion engine in which a continuously energized air heater provided in the intake passage is energized and heated before and after starting the engine, the air heater and the power source are connected to each other, and the engine key switch is preheated. The air heater is connected via a heater relay that is closed by a timer unit that operates for a set time after the engine is set in position, and the power consumption of the air heater after the engine has started is detected through the voltage generated by the generator driven by the engine. 1. A control device for an electric air heater for an internal combustion engine, characterized in that it is provided with a start sensing element that reduces the noise. (2) The control device for an electric air heater for an internal combustion engine according to claim 1, wherein the start sensing element detects the start of the engine and reduces the current flowing to the air heater.