JPH0455250Y2 - - Google Patents

Description

[Detailed explanation of the idea] [Industrial application field] The present invention relates to a dual fuel supply device.

[Conventional technology]

Traditionally, diesel engines have used distribution-type or in-line fuel injection pumps. Light oil is generally used as fuel, but there are attempts to use alcohol in diesel engines. However, since alcohol has poor self-ignition properties, it is difficult to use alcohol alone, and it has been proposed to inject a small amount of light oil to ignite it, and then inject alcohol as the main fuel. In this case, light oil is used as a fuel. Thus, a dual fuel supply system capable of injecting two types of fuel has become necessary.

In this case, since only a small amount of diesel oil needs to be injected, it is not economical to have two fuel injection pumps, so a conventional fuel injection pump is used for the main fuel, and another for the auxiliary fuel. It is advantageous to use simple injection means. Japanese Unexamined Patent Publication 1983-
Japanese Patent No. 206867 discloses a small fuel pump that injects main fuel from a conventional fuel injection pump and operates by utilizing the pressure of the main fuel during injection. This fuel pump is a simple device with almost only a piston, and because it uses the injection pressure of the main fuel, it can automatically synchronize with the engine. According to this publication, the auxiliary fuel supplied by the fuel pump has a lower injection pressure than the main fuel injection pressure, and is directed to a cylinder different from the main fuel cylinder at the injection timing, and is not at the actual injection timing. It is supplied to the tip of the cylinder. The supply pressure of this auxiliary fuel is lower than the valve opening pressure of the fuel injection nozzle, so it enters the tip of the fuel injection valve and waits for the main fuel to be injected.

[Problem that the invention attempts to solve]

By using a fuel pressure feeder such as that described in the above-mentioned Japanese Patent Application Laid-Open No. 58-206867, a simple dual fuel supply system can be constructed. however,
Since the injection pressure of the main fuel is used to operate the fuel pump, the space occupied by the main fuel expands to push the piston of the fuel pump, causing a pressure increase at the beginning of main fuel injection. There was a problem that the injection was delayed and sharp injection was not performed, which adversely affected combustion. Particularly when the load is light and the amount of fuel injected is small, the operation becomes unstable. still,
In order to solve this problem, Japanese Patent Application No. 60-223791, which is an earlier application of the present application, is designed to drive a similar fuel pump by mechanically connecting it to a fuel injection pump.

[Means for solving problems]

The dual fuel supply device according to the present invention includes a cam attached to a drive shaft, a plunger that is reciprocated by the cam and can pump a first fuel, and is arranged at a position on substantially the same cross section as the plunger. a fuel injection pump having a piston that can be reciprocated by the cam to pump a second fuel, and first and second fuel injection pumps that are internally connected;
a first conduit for supplying the first fuel pumped by the plunger to the first fuel passage of the fuel injection nozzle; A second conduit for supplying the second fuel to the second fuel passage of the fuel injection nozzle, and a check valve disposed in the second conduit or the second fuel passage. That is.

〔Example〕

Referring to FIGS. 1 and 2, the dual fuel supply device according to the present invention includes an in-line fuel injection pump 10, a fuel pump 12 attached to the in-line fuel injection pump 10, and a fuel injection nozzle 14. configured. Furthermore, there is a first fuel tank 16 containing a main fuel such as alcohol, and a second fuel tank 18 containing a secondary fuel such as light oil. Also, a feed pump 20 for supplying main fuel such as alcohol from the first fuel tank 16 to the fuel injection pump 10.
A feed pump 22 is provided for supplying auxiliary fuel such as light oil from the second fuel tank 18 to the fuel pressure feeder 12, and the feed pump 20 can be built into the fuel injection pump 10.

The in-line fuel injection pump 10 has a drive shaft 26 extending longitudinally within the housing 24, and cams 28 of the same number as the number of cylinders are attached to the drive shaft 26. Above each cam 28 is a roller 3.
0 is arranged, and a tapepet 32 is placed on the roller 30.
is placed. A plunger 34 is positioned vertically above the tappet 32 and a spring 36 biases the leaded plunger 34 downwardly so that the roller 30 can contact the cam 28. The plunger 34 is slidably inserted into the plunger barrel 38, and its upper portion performs a pumping action by moving up and down relative to the oil reservoir 40 of the plunger barrel 38, and has a discharge port in which a delivery valve 42 is disposed. Fuel is discharged from 44. The main fuel in the first fuel tank 16 is supplied to this oil reservoir 40 and is then supplied to the fuel injection nozzle 14 from the discharge port 44 under high pressure. There is also a control sleeve 46 around the plunger barrel 38, which is rotated by a control rack 48 to regulate the rotational position of the plunger 34 and adjust the fuel injection amount.

The above is the configuration of the known in-line fuel injection pump 10, and the bottom of the housing 24 has a plunger 34.
There is a hole 50 for pulling out. In this invention,
The fuel pump 12 is fitted into the hole 50 and fixed by suitable means such as bolts. The fuel pump 12 is disposed on the same cross-section as the plunger 34 and in opposing relation to the plunger 34 . The fuel pump 12 has a housing 52 that fits into the hole 50, and a piston 54 that is slidably disposed within a cylinder bore formed in the housing 52. As with the plunger 34, the piston 54 is connected to a roller 56 and a tappet 5.
It is adapted to be actuated by the same cam 28 which actuates the plunger 34 via 8.
A working chamber 60 is formed on the distal end side of the piston 54 within the cylinder bore of the housing 52 of the fuel pump 12, and a spring 62 is disposed within the working chamber 60 to bias the piston 54 toward the cam 28. . Additionally, a second fuel tank 18 is provided in the working chamber 60.
an auxiliary fuel inlet 64 leading to the fuel injection nozzle 1;
An auxiliary fuel outlet 66 is formed which leads to 4. A check valve 68 is arranged at the auxiliary fuel inlet 64, and a check valve 70 is arranged at the auxiliary fuel outlet 66.

As shown in FIG.
a nozzle body 74 having a nozzle 72 formed at its tip;
It consists of a needle valve 76 inserted into a nozzle body 74, and the needle valve 76 can open and close the spout 72, and is biased in the valve closing direction by a spring (not shown). A first fuel passage 78 passes through the nozzle body 74 and is then formed as an annular space between the inner wall of the nozzle body 74 and the outer circumferential surface of the needle valve 76 . The needle valve 76 is formed hollow along the central axis, and has a small hole that opens radially outward from the central hollow near the nozzle 72. A second fuel passage 80 is formed through the nozzle body 74 and then through the central hollow of the needle valve 76 and into the first fuel passage 78 by an eyelet opening radially outward near the nozzle 72 . Concatenated.

As shown in FIG.
Each discharge port 44 that supplies main fuel from the pipe 8
2 of the fuel injection nozzle 14 respectively.
It is connected to the fuel passage 78 of. On the other hand, the auxiliary fuel outlet 66 that supplies auxiliary fuel from each fuel pumper 12 is
It is connected to a collecting pipe 84 which is collected into a single pipe.
The single pipe of the collecting pipe 84 is then connected to each fuel injection nozzle 1 by branch pipes 86, 88 having the same flow resistance.
It is connected to the second fuel passage 80 of No. 4. A check valve 90 is arranged in the last branch pipe 88 or in the second fuel passage 80 of each fuel injection nozzle 14 .

Next, the operation will be explained with reference to FIG.

FIG. 3 shows an example of a four-cylinder engine in which the fuel injection order is performed in the order of 1st, 3rd, 4th, and 2nd cylinders, and A indicates that the plunger 34 operates to pump the main fuel,
B indicates that the piston 54 operates to supply auxiliary fuel. Since the piston 54 is positioned opposite the plunger 34, the operations of the piston 54 and the plunger 34 actuated by the same cam 28 are offset by 360 crank angles. Therefore, when the plunger 34 of the first cylinder operates, the piston 54 of the fourth cylinder operates simultaneously.

The valve opening pressure of the needle valve 76 of the fuel injection nozzle 14 is set by the spring described above, and the injection pressure of the main fuel is naturally higher than the valve opening pressure of the needle valve 76, but the supply pressure of the auxiliary fuel is set by the valve opening pressure of the needle valve 76. It is set to a value lower than the valve opening pressure. Therefore, when the main fuel is supplied by the operation of the plunger 34, injection is performed from the fuel injection nozzle 14, but even if auxiliary fuel is supplied by the operation of the piston 54, no injection is performed from the fuel injection nozzle 14. . However, when the auxiliary fuel is supplied by the actuation of the piston 54, the auxiliary fuel enters the first fuel passage 78 from the second fuel passage 80 and pushes back the main fuel in the first fuel passage 78. This will replace the main fuel at the tip. That is, in a specific cylinder, the auxiliary fuel is filled into the tip of the fuel injection nozzle 14 when it is not the injection timing, and is injected together with the main fuel when the main fuel of that cylinder is injected. At this time, since the auxiliary fuel was filled at the tip of the fuel injection nozzle 14, the auxiliary fuel is injected first, and then the main fuel is injected. The first auxiliary fuel injected is light oil with excellent ignitability and immediately ignites by itself. The alcohol main fuel, which has poor ignitability, can be ignited with the aid of the light oil that ignites first.

As shown in FIG. 1, when each fuel pump 12 is connected to the collecting pipe 84 and then branched again to each fuel injection nozzle 14, the following will occur. For example, when the crank angle is 0 degrees, the plunger 34 of the first cylinder is activated, and at the same time the piston 5 of the fourth cylinder is activated.
Consider when 4 is activated. The fuel injection nozzle 14 of the first cylinder injects fuel as described above.
At this time, the second fuel injection nozzle 14 of the first cylinder
A check valve 90 located in the second fuel passage 80 prevents high pressure main fuel from flowing back through the second fuel passage 80. The fuel supplied by the piston 54 of the fourth cylinder passes through the collecting pipe 84 and then through the branch pipes 86 and 88, so that it is directed to the fuel injection nozzles 14 of all cylinders. However, since the pressure of the main fuel in the second cylinder, which is currently being injected, is high, the auxiliary fuel does not enter the fuel injection nozzle 14 of the first cylinder. The fuel is filled into the tip of the first fuel passage 78 through the second fuel passage 80 of the fuel injection nozzle 14 of the cylinder. Such filling of auxiliary fuel is performed for each injection, and for one cylinder, it is performed three times, one-third of the fuel at each time. This makes it possible to fill the fuel with an average amount of auxiliary fuel and eliminate individual differences in the fuel pumps 12.

[Effect of idea]

As explained above, according to the present invention, by sharing the drive shaft and cam of the fuel injection pump, different types of fuel can be reliably supplied to each fuel injection pump with a very simple configuration. Furthermore, it is possible to inject different fuels in layers from one fuel injection nozzle. If the auxiliary fuel pump is installed in the plunger hole of the fuel injection pump, a dual fuel supply device can be realized without changing the structure of the conventional fuel injection pump.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing a dual fuel supply device according to the present invention, FIG. 2 is an enlarged cross-sectional view of the fuel injection pump shown in FIG. 1, and FIG. 3 is an operational explanation for explaining the function of the dual fuel supply device. It is a diagram. 10... Fuel injection pump, 12... Fuel pressure feeder, 14... Fuel injection nozzle, 26... Drive shaft,
34...Plunger, 54...Piston, 78,
80...Fuel passage, 90...Check valve.

Claims (1)

[Scope of utility model registration request] a cam attached to the drive shaft; a plunger that is reciprocally operated by the cam to force-feed a first fuel; a fuel injection pump having a first piston capable of pumping fuel;
and a fuel injection nozzle having a second fuel passage;
a first conduit for supplying the first fuel pumped by the plunger to the first fuel passage of the fuel injection nozzle; and a first conduit for supplying the second fuel pumped by the piston to the first fuel passage of the fuel injection nozzle. A dual fuel supply device comprising a second conduit for supplying a second fuel passage and a check valve disposed in the second conduit or the second fuel passage.