JPH0120307B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an injection device for dissimilar liquids for an internal combustion engine, which injects dissimilar liquids, such as alcohol and light oil, into a combustion chamber without mixing them.

This type of liquid injection device can be used, for example, as an injection device for a diesel engine that uses alcohol as the main fuel and light oil as the auxiliary fuel. Generally, there is a method of mixing two types of fuel, such as alcohol with poor ignitability, and light oil with good ignitability, and injecting the mixture, but in this method, there is a limit value for the mixing ratio from the viewpoint of the ignitability of the mixed fuel. It is known that there is. Therefore, in order to solve this problem, it is necessary to inject the two fuels separately so as not to mix them as much as possible, or to inject the light oil in a layered manner before the alcohol.

Conventionally, this type of injection device includes, for example, the following:
There are various proposals as shown in (a) to (c).

That is, (a) One that uses two injection pumps, (a) Those that utilize the negative pressure of the delivery valve; (c) It utilizes the pulsating effect of the injection system.

For example, for example (a), for two types of fuel,
There are examples of research reports in various fields on methods that each include a dedicated injection pump and injection nozzle.

Next, as an example of (a), there is Special Publication No. 13806, 1973. In this example, a dissimilar liquid source is connected via a check valve to any position from the delivery valve of the fuel injection system to the fuel injection nozzle, and the dissimilar liquid is supplied to the fuel injection system by the negative pressure generated by the delivery valve. It is introduced and injected along with fuel from the nozzle. In this example, it is theoretically necessary to increase the suction and return amount of the delivery valve, which increases the cavitation strength and causes a problem in durability. Furthermore, since cavitation occurs in the injection system due to suction, in other words, the amount of second liquid sucked varies irregularly depending on the movement speed and load, it is necessary to accurately control the amount of absorbed liquid. There is a drawback that it cannot be done.

An example of (c) is Japanese Patent Publication No. 50-23455. In this example, two injection nozzles are separately provided per cylinder. One injection nozzle is connected to a fuel pump via a pipe, and the other injection nozzle is connected via separate pipes to a water tank and a stepped piston, etc., which are actuated by the pressure of the fuel pumped by the pump. ing. In addition, the above two pipes are 1
An example is disclosed in which the book is coupled to a double needle nozzle. However, such an example has the drawback that the structure is complicated as described above.

In addition, as an example of the method (c), there is a method in which the fuel mixes within the injection nozzle, and in order to avoid this drawback, it is necessary to provide two nozzles per cylinder, etc. There is.

An object of the present invention is to provide a liquid injection device for an internal combustion engine that eliminates the above-mentioned drawbacks, has a simple structure, and can inject two types of liquids in a layered manner into a combustion chamber without mixing.

That is, the injection device according to the present invention supplies two types of liquids in a fixed order to an injection nozzle provided with a space on the outer periphery of a needle valve, using the pulsating pressure of one liquid to feed the other liquid. The present invention is characterized in that the two liquids can be sprayed in a layered state without mixing.

An embodiment of the present invention will be described in detail below with reference to the drawings.

This embodiment is applied to a diesel engine that uses alcohol as the main fuel and light oil as the auxiliary fuel. In Figure 1,
A main tank 10 storing alcohol and a sub tank 11 storing light oil are provided, and these tanks 1
0 and 11, the respective fuels are supplied to a main fuel injection pump 14 and a pressure feeder 15 by oil feed pumps 12 and 13, respectively. This injection pump 14 is a known one, and has the same number of injection ports as the number of cylinders of the internal combustion engine used (four in this example). Similarly, although it is necessary to provide the auxiliary fuel pump 15 for several cylinders, only one is shown for simplicity. This pressure feeder 15 has a communication passage 18 for feeding the main fuel, and this inlet 17 communicates with the injection pump 14 . Further, a communication passage 20 for feeding auxiliary fuel is provided, and this inlet 16 communicates with the pump 13. The main fuel communication passage 18 and the auxiliary fuel communication passage 20 are communicated through a cylinder portion, and a piston 22 is slidably provided within the cylinder portion. This piston 22 is provided with a spring 23 that always urges it in the direction of the communication path 18 (downward in the figure), and the lower surface of the piston 22 is normally pressed against the stepped portion 26 of the cylinder portion by this spring 23. There is. On the other hand, the auxiliary fuel communication passage 20 has spaces near its inlet 16 and outlet 21 in which check valves 24 and 25 are provided. One of the check valves 24 has a function of introducing light oil into the auxiliary fuel pipe 20, so that a predetermined spring pressure is always applied in the left direction in the drawing, and the other check valve 25 has the function of introducing light oil into the auxiliary fuel pipe 20. A predetermined spring pressure is always applied in the left direction in the drawing so as to have the function of feeding the light oil introduced therein from the outlet 21 to the injection nozzle. The number of fuel injection nozzles 30 is the same as the number of cylinders. Here, for convenience, the four nozzles 30 are numbered from the left side of the drawing, and these numbers correspond to the numbers of the injection ports of the injection pump 14 described above (this relationship will be explained later). do). This injection nozzle 30 is provided with a needle valve 31 in the center thereof so as to be able to slide up and down, and a main fuel passage 32 and an auxiliary fuel passage 33 are formed approximately parallel to the center line of the needle valve 31 at spaced apart positions around the needle valve 31. Ru. The upper end openings of these passages 32 and 33 are connected to the pressure feeder 1 through connection pipes 40 and 41.
5, respectively. The tip of the needle valve 31 is composed of a tapered part 34, and a cavity 35 having a volume of about 1/2 to 1 times the volume of auxiliary fuel required for one injection is formed in the outer peripheral part of this tapered part 34. do. The lower end openings of the fuel passages 32 and 33 are communicated with this space 35. Here, the opening of this main fuel passage 32 is an auxiliary fuel passage 33.
It is formed so as to be farther away from the injection port 36 than the position where the opening is formed.

What should be noted here is that the main fuel that is pumped from the injection port of the injection pump 14 through the communication passage 18 is fed to the main fuel passage 32 of the injection nozzle 30-, but the auxiliary fuel is 30-, but rather to connect the fuel to the auxiliary fuel passage 37 of the injection nozzle 30- of the next injection stroke.

That is, the fuel injection pump 14 and the injection nozzle 3
The connection relationship with 0 is shown in FIG. This example is for a four-cylinder internal combustion engine, and is a connection example when the injection order is ---. Here, since the auxiliary fuel pump 15 is directly connected to the injection nozzle 30, the connecting pipe 41 in FIG. 1 is omitted. In the fuel injection device shown in FIG. 2, each injection port of the injection pump 14,
and 15- to the injection nozzles 30-, 3
0-, 30- and 30-, respectively.

FIG. 3 is for explaining the operating state of each injection pump and nozzle as a whole system. In the figure, the horizontal axis represents the angle of the pump cam, and the vertical axis represents the combination of each pump and nozzle. Here, the cam angle of 0° means the point at which the injection port of the pump 14 starts pumping.

The overall operation of the fuel injection system shown in FIG. 1 will be explained with reference to FIGS. 2 and 3. Alcohol as the main fuel is fed from the main tank 10 to the injection pump 14 via the pump 12. Here, high pressure is applied to the alcohol and the alcohol is jetted out from the injection port. This alcohol is forced into the main fuel passage 32 of the injection nozzle 30 through the pipe 18 of the pressure feeder 15, and at the same time the pressure is applied to the lower surface of the piston 22 of the pressure feeder 15. On the other hand, the check valve 24 is opened to introduce light oil as auxiliary fuel into the pipe 20 of the auxiliary fuel pump 15 via the pump 13. However, under the feeding pressure in this state, the check valve 25 on the outlet side does not open, so that a predetermined amount of light oil is filled in the communication passage 20. In this state, when the high-pressure alcohol passes through the pressure feeder, the piston 22 rises against the force of the compression spring 23. This rise generates pressure in the communication passage 20 filled with light oil, and this pressure causes the check valve 25 to open for the first time, allowing the light oil to flow from the outlet 21 through the connecting pipe 41 to the injection nozzle 30-. The fuel is supplied to the auxiliary fuel passage 37. Here, it is assumed that the injection port of the needle valve of the nozzle 30- is closed by the force of a spring (not shown). The pumped light oil thus compresses the alcohol that had already been injected into the cavity 38 of this nozzle in the previous injection stroke, while pushing it back a little towards its passage 39. In this case, as described above, the fuel injection nozzle 3 at the opening of the passage 37 and the passage 39 into the cavity 38
Since the height positions in the direction of the center axis of the fuel oil differ, the light oil flows out from the opening of the light oil passage 37 into the space 38, and further flows into the alcohol passage 39 with a certain directionality, so as a result, The amount of alcohol remaining in the space 38 as the main fuel is very small. In particular, the area near the injection port becomes almost 100% filled with light oil. Here, there is also the advantage that the value of this amount to the nozzle 30- can be precisely defined. The reason for this is that the upper surface of the piston 22 comes into contact with the upper step of the cylinder communication portion, and is therefore restricted from rising any further to pump light oil.
At this time, the fuel pressure inside the nozzle 30- increases slightly due to the inflow of light oil, but since the fuel pressure does not reach the valve opening pressure, no fuel is injected from the nozzle 30-.

On the other hand, even after the filling of the nozzle 30- with light oil is completed, as described above, since alcohol continues to be fed under pressure to the nozzle 30-, the internal pressure of the alcohol passage 32 increases, causing the nozzle 30- to open. The valve pressure is reached, and light oil is injected from this injection port 36 first, followed by alcohol. This injection continues until the end of the pumping period of alcohol into this nozzle. In this case, as can be seen from FIG. 3, the injected light oil has been filled in advance when the alcohol is being pumped into the nozzle 30-, and the filling amount and filling state are clear from the above explanation. be. After this injection is completed, the alcohol pressure decreases and the piston 22 is lowered by the force of the spring 23 to the rest position shown. This causes the check valve 24 to open slightly, allowing a small amount of light oil to be introduced from the tank 11. Next, when the cam angle of the pump 14 reaches 90 degrees, the injection nozzle 30-
Pressure feeding of alcohol begins, the same operations as described above are performed, and when the injection stroke of this nozzle is completed, the injection strokes of the nozzle 30- and then the nozzle 30- are completed in sequence, and this system This means that one cycle has been completed.

It is clear that the present invention is not limited to the embodiments described above, and that various modifications can be made.

First, in the above embodiment, the injection device for a diesel engine is a combination of alcohol and light oil, but the invention is not limited to this. For example, light oil is stored in the main tank 10 and water is stored in the auxiliary tank 11, and this water is injected into the light oil. It is also possible to use the fuel in a so-called pollution prevention engine that lowers the combustion temperature by injecting the fuel in a stratified manner into the combustion chamber prior to combustion. It can also be applied as an injection device for internal combustion engines that can use a variety of fuels, such as using a fuel with poor ignitability such as eucalyptus oil as the main fuel instead of alcohol fuel, and combining it with a fuel with good ignitability as an auxiliary fuel. It is clear that it can be done. Furthermore, the injection device of the present invention is applicable to all diesel engines having two or more cylinders.

In the embodiment, the main fuel communication passage 18 is provided in the pressure feeder 15.
However, it is also possible to provide this communication passage separately, connect a branch pipe to a part of it, and connect it to the communication part in which the piston is housed.

As described above in detail, the injection device of the present invention has the advantage of being able to accurately regulate the amount of auxiliary fuel fed to the injection nozzle. Also,
Fuel with good ignitability can be injected into the combustion chamber in a stratified manner prior to fuel with poor ignitability, and in this case there is an advantage that mixing of both fuels hardly occurs. Furthermore, there is an advantage that the structure of the device is simpler than that of conventional devices.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram for explaining an embodiment of a dissimilar liquid injection device for an internal combustion engine according to the present invention, and Fig. 2 is a diagram for explaining the connection relationship when the above embodiment device is applied to a four-cylinder engine. The connection diagram and FIG. 3 are also explanatory diagrams showing the operating state of the above-mentioned device in each stroke. DESCRIPTION OF SYMBOLS 10... Main tank, 11... Sub tank, 14... Injection pump, 15... Auxiliary fuel pressure feeder, 18, 20... Communication path, 22... Piston, 24, 25... Check valve, 3
0...Fuel injection nozzle, 31...Needle valve, 32,
39...Main fuel passage, 33, 37...Auxiliary fuel passage,
35, 38...vacancy, 36...injection port.

Claims (1)

[Claims] 1 an injection pump that delivers the first liquid at high pressure;
The second liquid receives the pulsating pressure of the first liquid delivered at high pressure.
A plurality of pressure feeders corresponding to the number of cylinders that deliver a predetermined amount of liquid at a relatively low pressure, and a first passage for supplying the first liquid and a second passage on the outer periphery of the needle valve.
and a plurality of injection nozzles corresponding to the number of cylinders each forming a cavity in which a second passage for liquid supply opens, and the pulsating pressure of the first liquid supplied to the first liquid passage of a certain injection nozzle. A dissimilar liquid injection device for a multi-cylinder internal combustion engine, characterized in that a second liquid is supplied to a second liquid passage of another injection nozzle by an actuated pressure feeder.