JPS6113741Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for injecting and supplying a small amount of auxiliary fuel in advance of fuel injection into a combustion chamber at the end of the compression stroke in a compression ignition diesel engine.

In order to reduce the ignition delay of the injected fuel in a diesel engine, a small amount of auxiliary fuel is injected prior to the main fuel injection supply at the end of the compression stroke, that is, during or during the intake stroke. Conventionally, the injection of this auxiliary fuel has been performed by a auxiliary fuel injection pump that is separate from the main fuel injection pump.
Two high-pressure fuel supply systems and two fuel injection pumps are required, which not only makes the structure significantly more complicated and the engine larger, but also requires more power from the engine to drive the two fuel injection pumps. Losses would also increase.

Therefore, Japanese Patent Publication No. 40-9329, which is a prior art that improves this drawback, describes that when main fuel is injected and supplied to specific multi-cylinder diesel engines, the amount of secondary fuel is regulated to a small amount by orifices etc. to other cylinders. It has been proposed to inject fuel simultaneously. However, since the small amount of auxiliary fuel here is regulated by an orifice, when the amount of main fuel injected increases in proportion to the load and rotational speed of the engine, the amount of auxiliary fuel injected also increases. In other words, the amount of auxiliary fuel injected here is not constant with respect to the load and rotation speed, but increases in proportion to the load and rotation speed. If the amount of auxiliary fuel injected increases in the load/high rotation range, it may cause premature ignition and increase combustion noise. Therefore, the amount of auxiliary fuel should be adjusted to a level that does not cause premature ignition in the high load/high rotation range. If the orifice diameter was set to restrict the amount of fuel, the amount of secondary fuel would be insufficient in the low load/low rotation range.

The present invention is to inject auxiliary fuel into each cylinder in a multi-cylinder diesel engine using a pilot plunger pump that operates using the fuel injection pressure in other cylinders that inject main fuel at the timing of auxiliary fuel injection. This makes it possible to keep the amount of auxiliary fuel injected into each cylinder substantially constant regardless of the load and rotational speed of the diesel engine.

For this reason, the present invention provides a multi-cylinder diesel engine in which each cylinder is provided with an auxiliary fuel injection valve that is connected to a fuel injection pump via a fuel injection pipe. A pilot type plunger pump is connected to each of the auxiliary fuel injection valves, and the pilot type plunger pump is configured to pressurize and supply fuel from the fuel pump to the auxiliary fuel injection valve by the sliding movement of a piston. In the plunger pump, the pilot cylinder chamber for slidingly moving the piston and each of the fuel injection pipes are connected to each other via a pilot passage between cylinders in which the injection timing of the main fuel and the injection timing of the auxiliary fuel coincide. This is a connected configuration.

With this configuration, when the main fuel is injected into a certain cylinder, when the pressure in the fuel injection pipe of that cylinder increases, this pressure is transferred to the pilot plunger pump which communicates with the auxiliary fuel injection valve of the other cylinder via the pilot passage. Since the piston in the pilot plunger pump slides, an amount of subsidiary fuel corresponding to the stroke of the piston in the pilot plunger pump is injected into the other cylinder from the subsidiary fuel injection valve. will be supplied by injection.

In other words, since the amount of auxiliary fuel injected into each cylinder is equal to the amount equivalent to the stroke of the piston in the pilot plunger pump,
The amount of auxiliary fuel injected into each cylinder can be made substantially constant regardless of the load and rotational speed of the diesel engine.

The following describes the drawings of the embodiment. In the drawings, reference numeral 1 indicates a four-cylinder engine in which the explosion order is, for example, first cylinder 11 - third cylinder 13 - fourth cylinder 14 - second cylinder 12. A main fuel injection valve 15 and an auxiliary fuel injection valve 16 are provided, and a pilot plunger pump 17, which will be described in detail later, is connected to each auxiliary fuel injection valve 16 via an auxiliary fuel injection pipe 18. . Reference numeral 19 denotes a fuel injection pump rotationally driven by the engine 1, and the fuel injection pump 19 has main fuel injection pipes 21, 22, 23,
24, and supplies fuel under pressure to the main fuel injection valves 15 in each cylinder in accordance with the order of injection and explosion.Although the drawing shows an in-line type, a distribution type may also be used, and this fuel injection Fuel from a fuel tank (not shown) is continuously supplied to the pump 19 by a fuel pump 20 via a fuel supply pipe 20'.

Each of the pilot plunger pumps 17 includes:
The fuel from the fuel pump 20 is supplied under pressure to each of the auxiliary fuel injection valves 16, and as shown in FIG.
A piston 35, which is slidably inserted into the pilot cylinder chamber 34, is coupled to the plunger 32, while the plunger barrel 3
A stopper pin 36 protruding inwardly is provided to appropriately restrict the reciprocating movement of the plunger 32 to a stroke l, and a fuel chamber 38 is provided on the outer periphery of the plunger barrel 31 and communicates with the inside of the plunger barrel 31 via a through hole 37. The fuel supply pipe 20' from the fuel pump 20 is connected to the fuel chamber 38 via a check valve 39, and a pilot passage 41 is branched from the main fuel injection pipe 21 in the first cylinder 13. into the pilot cylinder chamber 34 of the plunger pump 17 in the third cylinder 13;
The pilot passage 43 branched from the main fuel injection pipe 23 in the fourth cylinder 14 is connected to the pilot cylinder chamber 34 of the plunger pump 17 in the fourth cylinder 14; In the pilot cylinder chamber 34 of the plunger pump 17,
The main fuel injection pipe 22 in the second cylinder 12
The pilot passage 42 branched from the first cylinder 11
These are connected to the pilot cylinder chambers 34 of the plunger pump 17, respectively.

In this configuration, when the first cylinder 11 is at the time of main fuel injection at the end of the compression stroke, the third cylinder 13 corresponds to the transition from the intake stroke to the compression stroke. When the pressure inside the main fuel injection pipe 21 increases, this pressure is transferred to the pilot cylinder chamber 3 of the plunger pump 17 in the third cylinder 13 via the pilot passage 41.
4, and the plunger 32 is moved forward by the piston 35 against the spring 33, so that the fuel in the plunger barrel 31 is transferred from the auxiliary fuel injection valve 16 to the third cylinder 13 as auxiliary fuel to the plunger 32. When the main fuel injection to the first cylinder 11 is finished and the pressure in the main fuel injection pipe 21 drops, the third
The plunger 32 of the plunger pump 17 in the cylinder 13 is moved backward by the force of the spring 33, and fuel from the fuel pump 20 is sucked into the plunger barrel 31.
When the main fuel is injected, the auxiliary fuel is injected into the fourth cylinder 14 by operating the plunger pump 17 in the fourth cylinder 14, and when the main fuel is injected in the fourth cylinder 14, the plunger pump in the second cylinder 12 operates. 17, auxiliary fuel is injected into the second cylinder 12, and when main fuel is injected into the second cylinder 12, auxiliary fuel is injected into the first cylinder 1 by the operation of the plunger pump 17 in the first cylinder 11. It is injected.

In this case, the injection amount of the auxiliary fuel is regulated by the stroke l of the plunger 32 in each pilot plunger pump 17, and
Since the stroke l is always constant regardless of the main fuel injection amount and the engine load and rotation speed,
The injection amount of the auxiliary fuel does not change depending on the load and rotation speed of the engine, and a constant amount of the auxiliary fuel can always be injected and supplied, and the injection amount of the auxiliary fuel can be adjusted by adjusting the stroke l of the plunger 32. It can be set arbitrarily by

In the case of the four-cylinder engine of the above embodiment, in order to inject the auxiliary fuel at the beginning of the intake stroke, the pilot passage 41 of the first cylinder 11 is connected to the plunger pump 17 of the fourth cylinder 14, and the pilot passage 41 of the first cylinder 11 is connected to the plunger pump 17 of the fourth cylinder 14.
The pilot passage 43 of the fourth cylinder 14 is connected to the pilot plunger pump 17 of the second cylinder 12, the pilot passage 44 of the fourth cylinder 14 is connected to the plunger pump 17 of the cylinder 11, and the pilot passage 4 of the second cylinder 12 is connected to the pilot passage 43 of the second cylinder 12.
2 may be connected to the plunger pump 17 of the third cylinder 13, and the present invention can be connected to the plunger pump 17 of the third cylinder 13.
Not limited to cylinders, the interval between each cylinder can be determined by crank angle.
Needless to say, the present invention can be similarly applied to multi-gas engines such as 3-cylinder or 6-cylinder engines at 120 degrees, and the auxiliary fuel injection valve 16 and pilot plunger pump 17 can also be integrated.

As described above, according to the present invention, it is possible to always inject a fixed amount of auxiliary fuel to each cylinder regardless of the load and rotation speed of the diesel engine, so there is no shortage of auxiliary fuel in the low load/low rotation range. The present invention has the effect of reliably achieving the effect of the injection of the auxiliary fuel without causing premature ignition due to an increase in the amount of the auxiliary fuel in a high load/high rotation range.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, with FIG. 1 being a schematic diagram of the device and FIG. 2 being a longitudinal sectional front view of a pilot plunger pump. 1... Engine, 11, 12, 13, 14... Cylinder, 15... Main fuel injection valve, 16... Sub-fuel injection valve, 19... Fuel injection pump, 20... Fuel pump, 21, 22, 23 , 24...main fuel injection pipe,
17...Pilot plunger pump, 31...
...Plunger barrel, 32...Plunger, 34
...Pilot cylinder chamber, 35...Piston,
41, 42, 43, 44... Pilot passage.

Claims (1)

[Scope of utility model registration request] In a multi-cylinder diesel engine in which each cylinder is provided with a main fuel injection valve connected to a fuel injection pump via a fuel injection pipe, each cylinder in the diesel engine is provided with an auxiliary fuel injection valve, and each auxiliary fuel injection valve is provided in each cylinder. A pilot type plunger pump is connected to each fuel injection valve, and the piston is connected to each pilot type plunger pump, which pressurizes and supplies fuel from the fuel pump to the auxiliary fuel injection valve by the sliding movement of the piston. A pilot cylinder chamber for sliding movement and each of the fuel injection pipes are connected to each other via a pilot passage for cylinders in which the injection time of the main fuel and the injection timing of the auxiliary fuel coincide. Auxiliary fuel injection device for diesel engines.