JPS6210436Y2 - - Google Patents

Description

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

Conventionally, in diesel engines, an auxiliary fuel intake system has been used that supplies a small amount of fuel to both the intake air and the intake air during the intake process, shortens the ignition delay, improves the utilization of intake air, and eliminates noise and smoke emissions. Are known.

As a method of supplying this auxiliary fuel to the intake passage,
Various methods have been used, such as a carburetor method and an injection method, but in either case, the particle size of the fuel is large, making it impossible to obtain a good air-fuel mixture. Therefore, some methods use ultrasonic vibrators to atomize fuel, but
In this case, there is a drawback that the device becomes complicated and costs increase. For this reason, conventionally, many fuel injection systems have adopted an injection method in which the fuel particle size is large but the fuel injection amount can be controlled relatively easily, and there is a demand for a supply device that uses an injection method and is capable of atomizing fuel particles.

Furthermore, in order to supply the auxiliary fuel by injection, the structure can be improved by installing the auxiliary fuel injection pump in parallel with the main fuel injection pump, and by forming the cam of the auxiliary fuel injection pump coaxially with the cam of the main fuel injection pump. A simplified fuel supply device is known from Japanese Patent Laid-Open No. 140717/1983.

However, in general, if auxiliary fuel is injected at low loads, ignition will occur prematurely and thermal efficiency will decrease, so auxiliary fuel must be injected only at high loads. It is not possible to adjust the injection of auxiliary fuel according to fluctuations.

The present invention was made in view of such conventional problems, and while it is possible to atomize the auxiliary fuel using an injection pump, a main fuel injection pump and an auxiliary fuel injection pump are provided in one row type pump. It is an object of the present invention to provide a fuel supply device for an engine in which the auxiliary fuel injection pump injects auxiliary fuel only when the load is high.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the accompanying drawings, which are examples of the present invention.

FIG. 1 shows a four-cylinder diesel engine as an example of an engine according to the present invention, where 1 indicates a combustion chamber;
2 is a main injection valve that supplies main fuel to the combustion chamber, 3 is an intake valve, 4 is an exhaust valve, 5 is an intake passage, 6 is an air cleaner, 7 is a sub-injection valve that supplies auxiliary fuel to the intake passage, 12 is a fuel The injection pumps 20 and 21 are supply pipes that supply fuel from the fuel injection pump to the main injection valve and the sub injection valve.

The sub-injection valve 7 has a valve chamber 8 as shown in FIG.
It has a valve stem 9, an auxiliary fuel supply hole 10, and a nozzle hole part 11 made of ceramic material.The auxiliary fuel that flows from the supply pipe 21 through the auxiliary fuel supply hole 10 temporarily accumulates in the valve chamber 8, and then Pressure pushes up the valve stem 9,
The water is ejected from radial nozzle holes 11a formed in the nozzle hole portion 11. Incidentally, pores formed in ceramic materials generally have the property of shrinking during firing. In this invention, taking advantage of this property,
A nozzle hole 11a having a predetermined diameter is formed in the nozzle hole portion 11 made of ceramic material, and the nozzle hole 11a is formed by firing.
By reducing the diameter of the nozzle hole 11a, it is possible to easily form a minute nozzle hole 11a. Thereby, the auxiliary fuel can be atomized to 4 microns or less and injected.

The sub-injection valve 7 has an intake passage 5 in order to utilize dynamic pressure.
The nozzle hole 11a is opened to the upstream side of the fuel, which helps atomize the fuel and improves its mixing with air. Further, a gathering portion 5a is formed behind the sub-injection valve 7 in the intake passage 5, and the air-fuel mixture is divided into the combustion chamber 1 of each cylinder here.

The number of fuel injection pumps 12 is 1 based on the number of cylinders in the engine.
It consists of a row-type injection pump with five pump parts, of which four pump parts are for main injection,
The other one is for sub-injection. FIG. 3 shows the internal structure of this fuel injection pump 12, and as in the conventional case,
A cam 13, a tappet roller 14, a plunger 15, a sill 16, a rack 17, a delivery valve 18, etc. are provided from below. By moving the rack 17 in conjunction with the accelerator pedal in the horizontal direction, the cylinder 16 is rotated relative to the plunger 15, and the positional relationship between the lead 15a formed at the upper end of the plunger 15 and the feed hole 16a of the cylinder 16 is adjusted. It's starting to change. Thereby, the effective stroke of the plunger 15 changes, and the amount of fuel injection can be changed.

Note that FIG. 3 shows a sub-injection pump section, which differs from the main injection pump section in the shape of the upper end of the plunger 15 and the shape of the cam 13. That is, as shown in FIG.
The lead 15a is cut out so that the width is narrower than the upper end 19b of the main injection plunger 19, and the auxiliary fuel is pumped only under high load, and the injection amount is 5 to 20% of the injection amount of the main fuel. It is set to be a percentage. Moreover, four protrusions are formed on the sub-injection cam 13, and the sub-injection plunger 15 is configured to reciprocate four times while the four main injection plungers 19 reciprocate once. There is.

As is clear from the above explanation, according to the present invention, since the nozzle hole portion of the sub-injector is made of ceramic material, it is possible to form a minute nozzle hole by taking advantage of the property that the nozzle hole shrinks during firing. Fuel can be atomized. In addition, as a fuel injection pump, we used an in-line pump with more plungers than the number of engine cylinders, and the extra plungers were used for auxiliary fuel, making it possible to perform auxiliary injection with an extremely simple configuration, making existing fuel injection pumps much easier to use. It can be used without modification. Furthermore, since the sub-injection plunger is configured to supply sub-fuel only when the load is high, ignition does not occur prematurely and thermal efficiency can be improved.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram of the engine fuel supply system according to the present invention, Fig. 2 is an enlarged sectional view of the sub-injection valve, Fig. 3 is a longitudinal sectional view of the fuel injection pump, and Fig. 4 is a part of it. It is an enlarged explanatory diagram. DESCRIPTION OF SYMBOLS 1...Combustion chamber, 2...Main injection valve, 5...Intake passage, 7...Sub-injection valve, 11...Nozzle hole portion, 12...
Fuel injection pump, 13...cam, 15, 19...
Plungiya, 15a... lead.

Claims (1)

[Scope of utility model registration request] 1. A fuel supply system for an engine which supplies main fuel to a combustion chamber from a main injection valve disposed adjacent to the combustion chamber and supplies secondary fuel to an intake passage from a secondary injection valve disposed in an intake passage, characterized in that the fuel injection pump is composed of an in-line injection pump having a main injection cam and plunger which supply fuel to the main injection valve, and a secondary injection cam and plunger which supply fuel to the secondary injection valve, the secondary injection plunger being configured to pump fuel only under high load, and at least the nozzle hole of the secondary injection valve being made of ceramic material.