JPS6029663Y2 - Diesel engine intake air heating device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an intake air heating device for a diesel engine, particularly an automotive diesel engine.

When diesel engines are operated at high altitudes, the reduced air density reduces the final pressure and temperature due to compression in the combustion chamber, increasing the ignition delay time and causing fuel to be ejected unburned without complete combustion. There is a problem in that a so-called half-misfire phenomenon occurs.

In order to solve this problem, conventionally, for example,
As disclosed in Japanese Patent No. 4824, a device has been proposed that corrects the fuel injection timing of a fuel injection pump to the advanced side when going to a high altitude, but it has not been put into practical use due to problems such as a complicated mechanism. It has not yet reached the point where it is possible.

The present invention attempts to solve the problem of half-misfire due to the increase in ignition delay time at high altitudes by shortening the ignition delay time.The ignition delay time is determined by the compression temperature and pressure in the combustion chamber. This was done based on the fact that the ignition delay time can be shortened by increasing the temperature, and the compression temperature can be increased by increasing the temperature of the intake air drawn into the combustion chamber.

Specifically, the present invention includes a heating device that heats air introduced into an engine combustion chamber, and a control device that controls the operation of the heating device that is equipped with an atmospheric pressure sensing device that senses changes in atmospheric pressure. However, when the atmospheric pressure decreases, the control device operates the heating device to increase the temperature of the intake air so that heated air is supplied to the combustion chamber of the engine.

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

In FIG. 1, 1 is the main body of a diesel engine, cylinder 2. Cylinder head 3. A combustion chamber 5 is basically constituted by a piston 4 and includes a swirl chamber 5a having a fuel injection nozzle 6 therein and a main combustion chamber 5b.

7 is an intake passage that introduces air into the combustion chamber 5, and 8 is an exhaust passage that discharges exhaust gas generated in the combustion chamber 5.

The intake passage 7 branches upstream of an air cleaner (not shown) into a passage 9 that directly takes in outside air, and a passage 11 that has an intake air heating section 10 in the middle and is open to the atmosphere at its tip. The intake passage 7 is provided with a switching valve 12 for selectively connecting the two passages 9 and 11 to the intake passage 7.

In this embodiment, the intake air heating section 10, the passage 11, and the switching valve 12 constitute a heating device.

In addition, the intake air heating section 10 provided in the middle of the passage 11 is
It is configured as a cover surrounding the exhaust manifold of the exhaust passage 8, and is located at a position where the switching valve 12 closes the passage 9 side and opens the passage 11 when the heating device is activated, as shown by the dashed line in FIG. when the intake air heating section 10 is heated by the exhaust gas flowing through the exhaust passage 8.
of air is drawn into the combustion chamber 5 through the passage 11 and the intake passage 7.

The control device is configured according to the following requirements.

That is, 13 is a lever 14 fixed to the switching valve 12.
This is a diaphragm device that switches and operates the switching valve 12 via a rod 15, and is defined by a diaphragm 13a to which the rod 15 is connected into a negative pressure chamber 13b and an atmospheric chamber 13c open to the atmosphere.

The negative pressure chamber 13b of the diaphragm device 13 communicates with a vacuum pump 18 driven by the engine 1 through a negative pressure passage 17 equipped with a three-way solenoid valve 16 in the middle, and a diaphragm 13a is installed inside the negative pressure chamber 13b so that the switching valve 12 is connected to the passage 1.
A spring 19 that urges the opening 1 to close is compressed.

The three-way solenoid valve 16 closes the vacuum pump side of the negative pressure passage 17 when it is not excited and is not activated, and the negative pressure chamber 13b is closed.
is opened to the atmosphere through the atmospheric hole 16a, and when activated, the atmospheric hole 16a is closed and the negative pressure chamber 13b and the vacuum pump 18 are communicated with each other.

20 is a battery with one end grounded, and includes a key switch 21 that closes when the engine 1 is operated, an altitude switch 22 that closes when the atmospheric pressure decreases, and a normal switch that opens when the engine 1 is operated under high load, for example near full load. It is connected to the solenoid 16b of the three-way solenoid valve 16 via a closed load switch 23.

The high altitude switch 22 is controlled to open and close by a bellows 24 whose interior is filled with vacuum or inert gas. When the atmospheric pressure introduced to the outside of the bellows 24 decreases, the bellows expands and closes the switch 22.

With the above configuration, when the engine is operated on a level ground where the atmospheric pressure is normal, the high altitude switch 22 is open, so the three-way solenoid valve 16 is not excited, and the diaphragm device 13
The negative pressure chamber 13b is open to the atmosphere via the atmospheric hole 16a.

Therefore, the diaphragm 13a is pushed toward the atmospheric chamber 13c by the force of the spring 19, and the switching valve 12 connected to the diaphragm 13a via the rod 15 and lever 14 opens the passage 11 as shown by the solid line in FIG. Closed.

Therefore, unheated air is drawn into the combustion chamber 5 via the passage 9 and the intake passage 7.

Next, when operating the engine at high altitudes where atmospheric pressure has decreased, the bellows 24 extends and closes the high altitude switch 22. Therefore, in the low and medium load range of the engine when the load switch 23 is closed, the three-way solenoid valve 16 is closed. Excited.

Therefore, the negative pressure of the vacuum pump 18 is introduced into the negative pressure chamber 13b of the diaphragm device 13 via the negative pressure passage 17, and the diaphragm 13a is pulled toward the negative pressure chamber 13b against the force of the spring 19, and the rod 15 and lever 14
As a result, the switching valve 12 closes the passage 9 and communicates the passage 11 with the intake passage 7.

Therefore, air heated and heated by the exhaust gas from the intake heating section 10 is introduced into the engine combustion chamber 5 through the passage 11 and the intake passage 7, and combustion occurs when the piston 4 is located near the compression top dead center. Compared to the case where unheated air is introduced, the compression temperature in the chamber 5 rises, and the time required for the fuel injected from the fuel injection nozzle 6 to ignite, that is, the ignition delay time, is shortened, resulting in a half-misfire. is prevented.

When the engine is operated at high load, load switch 2
3 is open, the switching valve 12 is connected to the passage 11 as in the case of flat land.
is closed, passage 9 is opened, and unheated air is introduced into combustion chamber 5.

This means that heating the intake air during high loads with a large amount of injected fuel not only reduces the air density due to a decrease in atmospheric pressure, but also reduces the substantial amount of air introduced into the combustion chamber 5. This is because this results in a decrease in output.

In the embodiment shown in FIG. 1, the switching valve 12 closes the passage 9 and opens the passage 11 when the atmospheric pressure becomes lower than the set value, so that only heated air is introduced into the combustion chamber. As shown in FIG. 2, the switching valve 12 changes the opening area of the passages 9 and 11 to the intake passage 7 depending on the degree of decrease in atmospheric pressure, thereby changing the proportion of unheated air and heated air introduced into the combustion chamber, i.e. , the degree of heating of all the air introduced into the combustion chamber may be controlled.

FIG. 2 shows another embodiment of the control device for the switching valve shown in FIG. A bellows 24 similar to that in Figure 1 that senses and expands when atmospheric pressure decreases.
' is in direct contact with .

In a flat area where the atmospheric pressure is normal, the bellows 24' is contracted, and the switching valve 12 is connected to the passage 1, as shown by the solid line in FIG.
1 is closed, and only unheated air from the passage 9 is introduced into the combustion chamber of the engine.

As altitude increases and atmospheric pressure decreases, bellows 2
4' extends and pushes the rod 15', so that the switching valve 12 opens the passage 11 and increases the opening area to the intake passage 7, and at the same time reduces the opening area of the passage 9 to the intake passage 7.

Therefore, as the atmospheric pressure decreases, the proportion of heated air introduced from the passage 11 increases, increasing the temperature of the air introduced into the combustion chamber.

As a result, a substantially constant ignition delay time can be maintained regardless of altitude changes, and half-misfires can be prevented.

In addition, in the embodiment shown in FIGS. 1 and 2 described above, exhaust gas was used as a means for heating the intake air, but other means,
For example, engine cooling water may be used.

As described above, according to the present invention, it is possible to solve the problem of half-misfire caused by a decrease in atmospheric pressure at high altitudes and the emission of harmful components associated with it.

[Brief explanation of the drawing]

FIG. 1 is a schematic explanatory diagram showing one embodiment of the present invention, and FIG. 2 is a structural diagram of main parts showing another aspect of the embodiment of FIG. 1. 1: engine, 5: combustion chamber, 7: intake passage, 8: exhaust passage, 9: passage, 10: intake air heating section, 11: passage, 12;
Switching valve, 13: Diaphragm device, 14 Nilever, 1
5, 15': Rod, 16: Three-way solenoid valve, 17: Negative pressure passage, 18: Vacuum pump, 22: Altitude switch, 2
3: Load switch, 24/24': Bellows.

Claims (1)

[Scope of utility model registration request] A heating device that heats the air introduced into the engine combustion chamber, and a control device that includes an atmospheric pressure sensing device that senses changes in atmospheric pressure and controls the operation of the heating device, and the control device controls the atmospheric pressure. An intake air heating device for a diesel engine, characterized in that the heating device is configured to operate so that heated air is supplied to the engine combustion chamber when the intake air temperature decreases.