JPS6320840Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a fuel injection device for a diesel engine.

BACKGROUND ART Conventionally, there has been a phenomenon in diesel engines in which a large amount of white smoke is emitted during a cold start, and as a countermeasure to this phenomenon, reduced-cylinder operation is generally performed.

The purpose of the present invention is to provide a means for reducing cylinder operation as a measure against the white smoke mentioned above.

The present invention will be explained in detail below.

A fuel injection device for a diesel engine according to the present invention is a fuel injection device for a diesel engine that can perform cylinder reduction operation for some of the n (n≧2) cylinders that make up the diesel engine. An injection pump that supplies high-pressure fuel is connected to the fuel inlet port of the injection nozzle in each cylinder, and the leak-off port of the non-reduced cylinder nozzle is connected directly to the fuel tank, and the leak-off port of the reduced-cylinder nozzle is connected through a hydraulic piston. a pneumatic piston connected to the hydraulic piston;
The air cylinder of the pneumatic piston was connected to an air tank via a three-way solenoid valve.

Examples will be explained below.

FIG. 1 shows an example of application of the present invention to a six-cylinder engine.

In the figure, the symbols N ₁ , N ₂ ...N ₆ indicate well-known automatic opening/closing injection nozzles, and for example, the internal structure is
It is as shown in the figure. Among these injection nozzles, assuming that injection nozzles N ₁ to _{N 3} are non-reduced cylinder nozzles and nozzles N ₄ to N ₆ are reduced cylinder nozzles, the fuel inlet ports J ₁ to _{J 6} of these injection nozzles are for injection, respectively. Outlet port 3 of fuel tank 2 and piping 5 via pump P
0, and each leak-off port K ₁ to _{K 3} of the non-reduced cylinder nozzle is connected to the inlet port 4 of the fuel tank 2.
and is connected by piping 60. Further, each of the leak-off ports K ₄ to _{K 6} of the reduced-cylinder nozzle is connected to the inlet port 4 of the fuel tank 2 by a pipe 70 via a switching valve 5 as an example of pressurization switching means. Looking in detail, the switching valve 5 has a pneumatic piston 5c that operates depending on the strength of the force between the pressurized air flowing in from the air port 5a and the spring 5b, and a hydraulic piston 5d that is integrated with the pneumatic piston 5c. are doing. The first port 5f formed at the compression side stroke end of the hydraulic cylinder 5e housing the hydraulic piston 5d and the leak-off ports _K4 to _K6 are connected by piping, and are provided on the side of the hydraulic cylinder 5e. The second port 5g and the inlet port 4 are connected by piping. Further, the air port 5a formed in the air cylinder 5h is connected to the intermediate port 6a of the three-way solenoid valve 6, and the right port 6b of the three-way solenoid valve 6 is connected to the air tank 7 or air compressor containing high-pressure air. Piping is connected, and the left port 6c of the three-way solenoid valve 6 is open to the atmosphere. Above 3
Switching of the solenoid valve 6 is performed by the strength relationship between the magnetic force in the solenoid 8 and the force of the spring 9, and specifically, by turning on/off the energization of the solenoid 8.

In the above configuration, the solenoid 8 is energized when executing the cylinder reduction mode in which the cylinder reduction operation is performed. Then, due to the magnetic repulsion force, the spring 9
The piston 6d moves to the left against the stretching force of , the port 6e opens, and the right port 6b and the intermediate port 6a are brought into communication. Therefore, high pressure air in the air tank 7 flows into the air cylinder 5h, and the pneumatic piston 5c is pushed up against the force of the extensible spring 5b. At the same time, the hydraulic piston 5d integrated with the pneumatic piston 5c is also pushed up.
Fuel in hydraulic cylinder 5e leaks off port
The pressure is transmitted through K ₄ , K ₅ , K ₆ to the spring chamber 10 in the holder of each nozzle N ₄ , N ₅ , N ₆ (see Figure 2), increasing the back pressure of the nozzle needle 11 and limiting its lift. do. The fuel injection start pressure of the injection nozzle is generally determined by the spring force of the nozzle spring, but
When the fuel in the hydraulic cylinder 5e is forced into the spring chamber 10 as in this example, this pressure acts to reinforce the spring force of the nozzle spring, thereby suppressing the lift of the nozzle needle 11. When the lift of the nozzle needle 11 is suppressed in this way, fuel injection from each nozzle N ₄ , N ₅ , and N ₆ is not performed, and thus a reduced-cylinder operation is performed.

When such reduced-cylinder operation is performed during a cold start, the total output of the engine is reduced by the number of operating cylinders, and the governor operates accordingly to increase the amount of fuel supplied to the non-reduced-cylinder nozzles. Combustion in the cylinder corresponding to each nozzle is promoted, and the white smoke phenomenon is quickly eliminated. Further, as for cylinders with reduced cylinders, the surroundings of the engine, cooling water temperature, etc. related to cylinders with reduced cylinders are also warmed up as a result of the above-mentioned operation of cylinders without cylinders with reduced cylinders, so that preparations for operation can be made at an early stage.

When the operating conditions for the cylinders with reduced cylinders, etc. are established, turn off the power to the solenoid 8, switch the three-way solenoid valve 6 so that the port 6e is closed, and set it to leak-off mode, which will open the air cylinder 5h to the atmosphere. , the hydraulic piston 5d is lowered by the force of the spring 5b, the first port 5f and the second port 5g are brought into communication, the normal leak-off path is restored, and the cylinder reduction operation is canceled.

As described above, according to the present invention, it is possible to easily switch between cylinder reduction operation and non-cylinder reduction operation by switching the three-way solenoid valve 6, and it is possible to effectively deal with white smoke during a cold start.

Furthermore, in this example, the hydraulic cylinder 5e of the hydraulic piston 5d is connected to the leak-off ports _K4 to _K6 , which are low pressure systems.
Since it is connected to the switching control means, problems with sealing properties are less likely to occur, and cavitation and erosion are also less likely to occur.Furthermore, the three-way solenoid valve 6 only needs to have a small capacity, and the amount of heat generated is small, improving durability. be able to.

[Brief explanation of the drawing]

FIG. 1 is a diagram illustrating an embodiment in which three cylinders are reduced from a six-cylinder engine, and FIG. 2 is a sectional view of an injection nozzle. N ₄ , N ₅ , N ₆ ... Injection nozzle (of reduced cylinder engine),
5...Switching valve (as pressurization switching means), 6
...3-way solenoid valve (as pressurization switching means), 10
...Spring chamber inside the nozzle holder.

Claims (1)

[Claims for Utility Model Registration] In a fuel injection system for a diesel engine that can perform cylinder reduction operation for some of the n (n≧2) cylinders that achieve a diesel engine, An injection pump that supplies high-pressure fuel is connected to the fuel inlet port of the injection nozzle, and the leak-off port of the non-reduced cylinder nozzle is connected directly to the fuel tank, and the leak-off port of the reduced-cylinder nozzle is connected to the fuel tank via a hydraulic piston. a pneumatic piston connected to the hydraulic piston;
A fuel injection device for a diesel engine, characterized in that an air cylinder of the pneumatic piston is communicated with an air tank via a three-way solenoid valve.