JPS60240866A - Fuel injecting device for internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent evaporation of fuel present at the interior of a fuel branch pipe, to smooth the feed of fuel to a fuel injecting valve, and to ensure sufficient strength of the fuel branch pipe, by a method wherein the fuel branch pipe is of a laminar structure of a resin pipe and a metallic pipe. CONSTITUTION:Fuel is forcibly fed from a tank 1 with the aid of a pump 2, and after the fuel is introduded to a branch pipe 3 through an inlet 7, it is distributed to each injecting valve 5 through an outlet 9. In which case, the branch pipe 3 is formed by a cylindrical pipe 3a and a resin pipe 3b, and the inner size of the metallic pipe 3a coincides with the outer size of the resin pipe 3b. In this constitution, the resin pipe 3b, forming the inner side of the branch pipe 3, serves as a heat insulation material, and this causes the heat of an internal combustion engine to be difficult to transfer to fuel present at the interior of the branch pipe 3, resulting in the possibility to prevent the occurrence of a trouble resulting from an increase in the temperature of the fuel. Further, the metallic pipe 3a, forming the outer side of the branch pipe 3, enables improvement of strength of the branch pipe 3.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fuel injection device for an internal combustion engine that supplies fuel to the engine.

[Prior art]

In conventional fuel injection systems for internal combustion engines, the fuel distribution pipe for distributing fuel pressure-fed from the fuel pump to each fuel injection valve is composed of a single metal pipe made of a metal material such as aluminum. It is difficult to say that a single metal pipe has good insulation properties, and there is a risk that some of the fuel may vaporize inside the fuel distribution pipe due to heat conduction from the internal combustion engine, and this fuel vaporization may cause hepa- raise the lock,
There is a risk that the injection efficiency from the fuel injection valve will decrease, and the output of the internal combustion engine will decrease accordingly.For example, if you try to restart the internal combustion engine when it is warmed up, , the problem is that it won't start.

[Purpose of the invention]

The purpose of the present invention is to suppress fuel vaporization inside the fuel distribution pipe, to ensure smooth fuel supply to the fuel injection valve, to prevent a decrease in the output of the internal combustion engine, and to ensure sufficient strength of the fuel distribution pipe. An object of the present invention is to provide a fuel injection device for an internal combustion engine.

In order to achieve the above object, in the present invention, the fuel distribution pipe has a layered structure of a resin pipe and a metal pipe.

〔Example〕

A first embodiment of the present invention will be described below with reference to FIG.

Fuel is pumped from a fuel pump 1 via an unillustrated fuel filter by an electric fuel injection pump 2. This pressure-fed fuel is introduced into the fuel distribution pipe 3 from the fuel lower,
The fuel is distributed to each fuel injection valve 5 from each fuel outlet 9 of this fuel distribution pipe 3 . Then, fuel is injected from the fuel injection valve 5 into an engine (not shown).

At the opposite end of the fuel distribution pipe 3 from the fuel lower, a pressure control valve 6 is connected to the gasket I by bolts at the flange portion of both 3.6.
One end of the fuel inlet 6a extending from the lower end of the pressure control valve 6 projects into the interior of the fuel distribution pipe 3. Note that an O-ring 6b is provided between the fuel inlet 6a and the fuel distribution pipe 3 to maintain liquid tightness.

A spring 6C is provided in the air chamber inside the pressure control valve 6, and this spring 6C biases the diaphragm 6d of the pressure control valve 6, and the spherical valve 6e provided on the diaphragm 6C when the fuel population 6a is activated. The other end is biased to close. When the fuel pressure inside the fuel distribution pipe 3 becomes larger than a predetermined value, this pressure is transmitted to the spherical valve 6e through the fuel inlet 6a, and the spherical valve 6e is moved by the spring 6.
The excess fuel is lifted against the urging force of C and returned to the fuel tank 1 via the fuel outlet 6f of the pressure control valve 6. Note that the intake pipe negative pressure (2) of the internal combustion engine is introduced into the air chamber of the pressure control valve 6.

The fuel distribution pipe 3 is made of a cylindrical metal pipe 3a formed from a metal material such as aluminum, and a synthetic resin such as nylon 66 (trade name) or polysalen sulfite, or a reinforcing material such as glass fiber or the like. or a cylindrical resin pipe 3b formed from a synthetic resin composite material mixed with an inorganic filler such as plate-shaped silica, and the inner diameter of the metal pipe 3a and the outer diameter of the resin pipe 3b are the same. We are doing so. The metal pipe 3a has flange portions 3al and 3a2 at both ends, and the flange portion 3al at one end is fixed to the flange portion of the pressure control valve 6 with bolts via a packing 11a. A hole 3a3 in which the fuel inlet 6a of the pressure control valve 6 is provided is formed at the center in the axial direction of the vibrator. Further, connection portions 3a4 where fuel injection valves 5 are provided are formed at multiple locations on the side of the metal pipe 3a, and O
The fuel injection valve 5 is fixed by a ring 5a to maintain liquid tightness.The resin pipe 3b is fitted inside the metal pipe 3a so that the inner wall of the metal pipe 3a and the outer wall of the resin pipe 3b are in close contact with each other. The tip thereof is in contact with the inner wall of the fixed end of the pressure control valve 6 of the metal pipe 3a, and a flange is formed in the vibrator radial direction at one end of the resin pipe 3b so as to face the flange portion 3a'2 of the metal pipe 3a. A portion 3bl is provided, and both flange portions 3a2.3al are attached to the packing 1.
It is fixed with a bolt via 1b. Further, one end of the resin pipe 3b is provided with the fuel lower, and a hole is provided in the side of the resin pipe 3b that corresponds to the connection part 3a4 of the metal pipe 3a, so that the fuel injection valve 5 can be inserted through the hole. A fuel outlet 9 is formed for injecting fuel.

Therefore, a substantial passage portion of the fuel pumped by the fuel pump 2 from the fuel pump 1 is inside the resin pipe 3b.

In the above configuration, fuel is pumped from the fuel pump 1 into the fuel pipe 3b of the fuel distribution pipe 3 through the fuel lower part formed in the resin pipe 3b, and is sent to the fuel outlet 9 leading to each fuel injection valve 5. . Then, an electronic control device (not shown) executes fuel injection according to the injection timing and injection time determined according to the load condition of the internal combustion engine, and when the pressure of the pumped fuel is higher than a predetermined value, the pressure control valve 6 Excess fuel is returned to the fuel tank 11 via.

Incidentally, the fuel distribution pipe 3 described above is installed near the internal combustion engine, and as the temperature of the internal combustion engine increases, the fuel distribution pipe 3 is heated. However, since the resin pipe 3b constituting the inside of the fuel distribution pipe 3 is made of synthetic resin or synthetic resin composite material, this serves as a heat insulator, and the heat of the internal combustion engine is transferred to the inside of the fuel distribution pipe 3, that is, the resin pipe. Therefore, the temperature of the fuel in the fuel distribution pipe 3 can be prevented from rising, and the fuel will not become so hot that a part of it will vaporize, resulting in vaporization. It is possible to suppress a drop in injection efficiency due to vapor lock and vapor lock.

Furthermore, the metal pipe 3a constituting the outside of the fuel distribution pipe 3 guarantees the strength of the fuel distribution pipe 3, which is much stronger than, for example, a structure made of a single resin material.

Note that this metal pipe 3a also prevents heat transfer from the internal combustion engine.

Next, a second embodiment of the present invention will be described based on FIG.

In this embodiment, an annular cavity 3C is provided between the metal pipe 3a and the resin pipe 3b constituting the fuel distribution pipe 3, through which excess fuel returned from the pressure control valve 6 to the fuel tank 1 flows. There is. On the side wall of the metal pipe 3a constituting the outside of the fuel distribution pipe 3, there is a pipe 3a through which excess fuel sent out from the fuel outlet 6f of the pressure control valve 6 is introduced into the cavity 3C via the pipe 12.
5 is provided, and an outlet 3a6 for sending fuel from the cavity 3C to the fuel tank 1 is also provided on the side wall of the metal pipe 3a.

At both ends of the portion of the resin pipe 3b that is accommodated in the metal pipe 3a, a contact portion 3b that contacts the inner wall of the metal pipe 3a is provided.
2 is provided along the outer periphery of the resin pipe 3b, and the resin pipe 3b is fixed in the metal pipe 3a by bringing the contact portion 3b2 and the metal pipe 3a into close contact via an O-ring 3b3.

Further, the tip of the fuel inlet 6a of the pressure control valve 6 is fitted to the inner wall of the resin pipe 3b via the QIJ song b, and the tip of the resin pipe 3b is in contact with the flange of the pressure control valve 6. ing. A connecting pipe 3d is provided between the inner wall of the connecting portion 3a4 provided on the metal pipe 3a and the fuel injection valve 5.
One end of the connecting pipe 3d is connected to a hole in the resin pipe 3b, and a rubber sleeve 3dl is provided along the outer periphery of the connecting pipe 3d at this connecting portion to maintain liquid tightness. Furthermore, a sleeve 3dl is similarly provided at a portion that contacts the cavity 3C between the metal pipe 3a and the connecting pipe 3d.

Therefore, the inside of the connecting pipe 3d becomes the fuel outlet 9, and the connecting pipe 3d prevents excess fuel in the cavity 3C from entering the inside of the fuel outlet 9.

In the above configuration, the fuel pressure-fed from the fuel lower into the resin pipe "7'3b" of the fuel distribution pipe 3 is fed to the fuel injection valve 5 from the fuel outlet 9, and the pressure control valve 6,
Excess fuel is returned to the fuel tank 1 via the cavity 3C.

The fuel distribution pipe 3 is affected by the heat of the internal combustion engine,
Similar to the first embodiment described above, the resin pipe 3b functions as a heat insulating material. Furthermore, in this second embodiment, the resin pipe, 3
A cavity 3C is provided between the metal pipe 3a and the metal pipe 3a, and excess fuel or air or both in this cavity 3C acts as a heat insulating material.

Therefore, the configuration of the second embodiment has a much better heat insulating effect than the first embodiment, preventing fuel vaporization, and suppressing the occurrence of vapor lock and a decrease in injection efficiency. can.

In each of the embodiments described above, the fuel distribution pipe 3 has a resin pipe 3b on the inside and a metal pipe 3a on the outside, but it may also have a metal pipe 3a on the inside and a resin pipe 3b on the outside.

Further, in each of the above-mentioned embodiments, the outer metal pipe 3a was provided with a connection portion 3a4 for installing a fuel injection valve in advance;
A hole having a predetermined size may be provided in advance in the metal pipe 3a and the resin pipe 3b, and a connecting pipe for providing the fuel injection valve 5 may be press-fitted into this hole. In this case, it is necessary to ensure liquid tightness between the connecting pipe and both pipes 3a and 3b.

〔Effect of the invention〕

As described above, in the present invention, since the fuel distribution pipe has a layered structure of a resin pipe and a metal pipe,
The heat insulating effect of the resin pipe makes it difficult for the temperature of the internal combustion engine to be transmitted to the fuel in the fuel distribution pipe, suppressing fuel vaporization, which prevents a decrease in injection efficiency, and therefore prevents a decrease in the output of the internal combustion engine. The metal pipe has the excellent effect of ensuring sufficient strength for the fuel distribution pipe.

[Brief explanation of the drawing]

FIG. 1 is a partial sectional view showing the first embodiment of the present invention, and the second embodiment is a partial sectional view showing the first embodiment of the present invention.
The figure is a partial sectional view showing a second embodiment of the present invention. 1...Fuel tank, 2...Electric fuel pump, 3.
...Fuel distribution pipe, 3a...Metal pipe, 3b...Resin vibrator, 5...Fuel injection valve, 6...Pressure control valve. Representative Patent Attorney Takashi Okabe

Claims (1)

[Scope of Claims] A fuel pump that pumps fuel from a fuel tank; a fuel distribution pipe that distributes the fuel pumped from the fuel pump to each fuel injection valve; A fuel injection device for an internal combustion engine, comprising: a pressure control valve that controls pressure; A fuel injection device for an internal combustion engine characterized by a layered structure.