JPH051642Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial technical field] The present invention is a nitrogen oxide suppression mechanism for a diesel engine, and more specifically, a nitrogen oxide suppression mechanism for a diesel engine that can suppress the generation of nitrogen oxides (NOx) in a diesel engine. It concerns the oxide suppression mechanism.

[Traditional background of the invention]

As a method to reduce the amount of nitrogen oxides (hereinafter referred to as NOx) in the exhaust gas of diesel engines,
Conventionally, there is a known method of preventing the generation of NOx by slightly retarding the fuel injection timing of diesel engines to allow the fuel to burn (so-called timing retard). In other words, since a large amount of NOx is generated when fuel burns at high temperatures, by performing timing retard as described above,
The aim is to burn fuel at a lower temperature and suppress the generation of NOx.

However, although this timing retard method suppresses the generation of NOx, it has the drawbacks of not only deteriorating the combustion efficiency but also increasing the generation of black smoke.

In addition, as a method of removing NOx, there is a method to remove NOx that is once generated by a catalyst like in a gasoline engine.
Although it is possible to reduce and remove the oxygen, this method has not been put to practical use in diesel engines due to the generation of black smoke and the high concentration of residual oxygen.

Therefore, in a diesel engine,
Currently, there is a need for a method of suppressing the amount of NOx in exhaust gas without performing timing retard or using a catalyst.

[Purpose of invention]

This invention was made in view of the above points,
An object of the present invention is to provide a NOx suppression mechanism for a diesel engine that can reduce the amount of NOx in exhaust gas without using a timing retard method, that is, without reducing combustion efficiency or using a catalyst.

[Structure of the invention] In order to achieve the above object, the nitrogen oxide suppression mechanism for a diesel engine according to the invention includes a heat exchanger connected to the exhaust pipe of the diesel engine, and water that is converted into steam by the heat exchanger. a water tank for storing water vapor, an accumulating pressure chamber for storing the water vapor generated in the heat exchanger, a means for introducing the water vapor in the accumulating pressure chamber into the air supply pipe, and an engine rotation Based on at least one of the following data: number, accelerator depression amount, and fuel injection amount of the injection pump,
A computer that controls the amount of water vapor supplied to the air supply pipe.

〔Example〕

Figure 1 shows the NOx of the diesel engine of this invention.
FIG. 2 is a block diagram showing one embodiment of a suppression mechanism;
As is clear from Fig. 1, the present invention
According to the NOx suppression mechanism, diesel engine 1
A heat exchanger 3 is provided in the exhaust pipe 2 . This heat exchanger 3 is for converting water into steam using the amount of heat of the exhaust gas passing through the exhaust pipe 2. Therefore, the heat exchanger 3 is connected to a water tank 5 via a solenoid valve 4 for adjusting the flow rate, and the water stored in the water tank 5 is turned into steam by the calorific value of the exhaust gas. It's summery.

The water vapor generated by the heat exchanger 3 is stored in the pressure accumulator 6. This pressure accumulation chamber 6 is connected to an air supply pipe 8 via a flow rate regulating valve 7.
The water vapor in the pressure accumulating chamber 6 can be supplied to the air supply pipe 8.

Furthermore, the flow rate adjustment valve 7 is controlled by a computer 9, and the computer 9 controls the flow rate adjustment valve 7 based on data such as the engine rotation speed, the amount of accelerator pedal depression, and the fuel injection amount of the injection pump. The amount of water vapor supplied to the air supply pipe 8 is controlled.

According to the nitrogen oxide suppression mechanism according to the present invention, which has the above configuration, exhaust gas from the diesel engine 1 is routed through the exhaust pipe 2 to the heat exchanger 3.
to go into. On the other hand, water in the water tank 5 similarly enters the heat exchanger 3 via the electromagnetic valve 4, and the water becomes steam by heat exchange with the exhaust gas. This water vapor is stored in the pressure accumulation chamber 6. The water vapor thus stored is introduced into the air supply pipe 8 through a flow rate regulating valve 7 controlled by a signal from a computer 9.

It is clear that the amount of water vapor introduced into the air supply pipe 8 is preferably large when the amount of NOx generated in the diesel engine 1 is considered to be large, and preferably at a relatively low concentration when the amount of NOx generated in the diesel engine 1 is considered to be small. . Considering that a large amount of NOx is generated when the diesel engine 1 is under high load, and relatively small when the load is low, in this embodiment, the engine speed, the amount of accelerator pedal depression, and the injection pump fuel The injection amount or the like is monitored and controlled by a computer 9 so that water vapor corresponding to the load of the engine 1 is introduced into the air supply pipe 8.

When water vapor is introduced into the air supply pipe 8 in this way,
This water vapor, along with air,
The fuel is introduced into a combustion chamber, compressed, and combusted by fuel injection. At this time, the combustion of fuel in the combustion chamber is cooled by water vapor, and combustion occurs at a relatively low temperature. As mentioned above, a large amount of NOx is generated when fuel burns at high temperatures, so the addition of this water vapor suppresses the generation of NOx.

[Effect of idea]

As explained above, according to the nitrogen oxide suppression mechanism of the diesel engine according to the present invention, the heat value of exhaust gas is used to generate water vapor, and this water vapor is introduced into the air supply pipe, thereby reducing the combustion temperature. This has the advantage that the amount of NOx in the exhaust gas can be suppressed without delaying the injection timing and without using a reduction catalyst.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of a nitrogen oxide suppression mechanism for a diesel engine according to the present invention. 1... Diesel engine, 2... Exhaust pipe, 3
... Heat exchanger, 5 ... Water tank, 6 ... Pressure accumulator,
8...Air supply pipe.

Claims (1)

[Scope of utility model registration request] A heat exchanger connected to the exhaust pipe of the diesel engine, a water tank for storing the water turned into steam by the heat exchanger, and a water tank for storing the steam generated by the heat exchanger. an accumulating pressure chamber, a means for introducing water vapor in the accumulating pressure chamber into the air supply pipe, and a means for introducing water vapor from the accumulation pressure chamber into the air supply pipe based on at least one data of engine speed, accelerator depression amount, and fuel injection amount of the injection pump. A nitrogen oxide suppression mechanism for a diesel engine, comprising a computer that controls the amount of water vapor to be supplied.