JPH0224939Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a fuel injection device for an internal combustion engine, and in particular to a structure that suppresses the temperature rise of a fuel injection valve and prevents fuel from being injected in a vaporized state. This invention relates to a simple fuel injection device for an internal combustion engine.

[Technical background of the invention and its problems] A fuel injection valve used in an internal combustion engine is installed in an intake pipe, and injects fuel into the intake pipe to achieve mixture vaporization with intake air. The intake pipe is connected to the engine, which becomes hot during operation, and its temperature increases due to heat transfer from the engine. Therefore, fuel injection valves that are directly attached to the intake pipe, which is exposed to high temperatures, are susceptible to thermal effects and are heated and their temperature increases (approximately 100°C).

In particular, when the engine continues to idle at a high temperature or when the intake pipe is operated at low speed with a high temperature, such as when restarting after soaking, the injection interval of the fuel injector is long and Since the amount of fuel injected is also small, if part of the fuel is vaporized within the fuel injection valve, or if the temperature around the nozzle becomes particularly high, the fuel will be vaporized during injection, making it impossible to obtain a predetermined amount of fuel injected. As a result, the air-fuel mixture became extremely lean, and there was a risk of rough idling or engine stalling. Such a situation is remarkable when a highly volatile fuel is used.

By the way, various fuel injection devices have been proposed in the past. The device shown in FIG. 1 is disclosed in Japanese Utility Model Application Publication No. 57-148064. The invention is based on the throttle valve a
When supplying intake air on the upstream side to the nozzle part c of the fuel injection valve b, a first
It is equipped with an air introduction passage d and a second air introduction passage e through which intake air flows by controlling the opening degree of the throttle valve a, and supplies intake air to the nozzle part c over a wide rotation speed range to inject fuel. This promotes atomization of the particles.

The one shown in FIG. 2 is disclosed in Japanese Utility Model Publication No. 12810/1983. This invention provides a hanging protrusion g that surrounds the nozzle f, and forms a spray shape according to the air flow within the combustion chamber h, thereby promoting the generation of a good air-fuel mixture.

The one shown in FIG. 3 is disclosed in Japanese Utility Model Publication No. 46-35455. In this invention, a deflection plate i is provided to face the fuel injection direction, and the deflection plate i
By attaching and fixing a steel j to the injected fuel, the injected fuel is crushed by collision to promote mixture vaporization.

All of the inventions are based on the premise that a predetermined amount of fuel is injected in liquid form, and the temperature of the fuel injection valve is raised during low-speed operation as proposed in the present application.
It is considered that this method does not solve the problem of engine malfunction caused by the inability to obtain a predetermined injection amount because fuel is injected as steam.

[Purpose of invention]

The present invention was devised in view of the above-mentioned problems, and its purpose is to provide an internal combustion engine with a simple structure that suppresses the temperature rise of the fuel injection valve and prevents fuel from being injected in a vaporized state. It is in providing fuel injection equipment.

[Summary of the idea]

According to the present invention, the above object is achieved by the following configuration.

That is, a fuel passage is surrounded between the valve housing of the fuel injection valve, which has a fuel flow passage formed therein and a fuel injection port formed at its tip, and an intake pipe to which the valve housing is attached via a support member. In order to form a heat insulating space and radiate heat around the fuel nozzle between the tip of the valve housing and the support member,
A cylindrical heat radiating member is provided, one end of which surrounds the fuel nozzle and the other end of which extends into the intake pipe.

[Example of idea]

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

As shown in FIG. 4, reference numeral 1 denotes an intake pipe that is directly connected to the internal combustion engine and forms an intake passage 2. A fuel injection valve 3 is also provided.

This fuel injection valve 3 has a hollow cylindrical valve housing 4 forming an outer shell, and an annular support member 5, 6.
It is attached to the intake pipe 1 by being supported by the intake pipe 1 through the intake pipe 1 and fixed to a disc-shaped fixing member 7 that is bolted from outside the intake pipe 1.
Further, on the outer side of the valve housing 4 of the fuel injection valve 3, there is provided a fuel passage 20 formed inside the valve housing 4 between the fuel injection valve 3 and the intake pipe 1 to suppress heat transfer from the intake pipe 1. A heat insulating space 8 is formed.

In this embodiment, the fuel injection valve 3 is a so-called D-
Electronically controlled fuel injection valves employed in dietronics, L-dietronics, etc. are exemplified. This fuel injection valve 3 includes a movable needle valve 9 in a valve housing 4, and when an electric pulse is applied to a solenoid 10 and the needle valve 9 is reciprocated against a coil spring 11, the valve housing 4 is moved. Fuel is intermittently injected from a fuel nozzle 12 formed at the tip of the fuel injector. Valve housing 4
The fuel pressure inside is kept constant by a fuel pump and pressure regulator. Further, the time of the electric pulse is set by calculating a predetermined control detection target (for example, intake flow rate, engine speed, etc.) using a microcomputer or the like. Therefore, the fuel injection amount is set as the amount of fuel flowing out from the fuel nozzle 12 that is opened for a predetermined time under approximately constant pressure.

In such a fuel injection valve 3, when the fuel is vaporized during fuel injection, the density of the fuel decreases significantly, and the mass of the fuel flowing out from the fuel nozzle 12, which is opened for a predetermined time under a constant pressure, is significantly reduced. It becomes impossible to obtain a predetermined fuel injection amount.

In the present invention, a heat radiating member 13 is provided to radiate heat around the fuel injection valve 3, particularly the fuel nozzle 12. As shown in FIG. 4, the heat radiating member 13 is configured to extend from the valve housing 4 to the intake passage 2 inside the intake pipe 1 and radiate heat upon contact with the flowing intake air. The heat dissipation member 13 is made of a material such as aluminum or copper that has a high heat transfer coefficient. The heat dissipation member 13 is formed into a cylindrical shape, one end of which is formed like a flange, and is locked between the tip of the valve housing 4 and the support member 6 with a ring member 14 interposed therebetween. , which is attached at one end to surround the fuel nozzle 12. The other end extends into the intake pipe 1 and is formed to guide the injected fuel into the intake pipe 1.

The heat radiating member 13 has a portion covered between the ring member 14 and the valve housing 4 as a heat receiving portion 13a, and recovers heat near the fuel nozzle 12. On the other hand, the other end extending to the intake passage 2 is configured as a heat radiating portion 13b that is cooled by the circulating intake air and radiates heat. In the illustrated example, it is formed into a bellows shape in order to increase the heat dissipation area in order to improve the heat dissipation performance.

Next, the operation of the present invention will be described.

Heat from the internal combustion engine is transferred to the fuel injection valve 3 via the intake pipe 1 and the like, and the temperature around the injection port 12 is increased, so that the heat receiving portion 13a of the heat radiating member 13 is also at a relatively high temperature.

On the other hand, the heat radiating portion 13b of the heat radiating member 13 is brought into contact with the circulating intake air and is cooled to a relatively low temperature.
Therefore, the heat receiving part 13a of the heat radiating member 13 and the heat radiating part 1
3b, and the heat that tends to stay around the fuel nozzle 12 is sequentially transferred to the heat radiating part 13b and radiated. Therefore, temperature rise around the fuel injection valve 3, especially the fuel nozzle 12, can be suppressed.

As described above, according to the present invention, it is possible to suppress the rise in temperature around the fuel injection valve 3, especially the nozzle 12 where fuel is easily vaporized during injection, so that it is possible to suppress the rise in temperature around the fuel injection valve 3, especially around the nozzle 12 where fuel is easily vaporized during injection. A predetermined fuel injection amount can be ensured even when fuel is used for the engine, and stability can be improved even during continued idling, restarting after soaking, and idling. Further, since the heat insulating space 8 is formed by surrounding the fuel flow path 20 of the valve housing 4, heat transfer into the valve housing 4 can be restricted from this surface as well, and vaporization of the fuel can be suppressed.

If the ring member 14 is made of a heat insulating material such as ceramic, heat transfer from the intake pipe 1 to the vicinity of the nozzle 12 can be suppressed as much as possible. Further, in the present invention, the heat radiating member 13 is extended into the intake pipe 1. Although it is possible to extend the heat radiating member 13 to the outside of the intake pipe 1, this is done considering that the temperature inside the engine room is generally high, and since the vehicle is not running during idling, there is a problem with its heat radiating effect. It is something.

[Modification example]

Modifications of the above embodiment are shown in FIGS. 5-7.

In the one shown in FIG. 5, the heat receiving part 13a of the heat radiating member 13 covered between the ring member 14 and the valve housing 4 is formed thicker than the heat radiating part 13b. Increasing the plate thickness of the heat receiving part 13a in this way increases the heat capacity of the heat receiving part 13a and suppresses the temperature rise characteristic (solid line A) of that part compared to the case where the plate thickness is thin (double-dashed line B). The difference between the temperature around the nozzle 12 (dotted chain line C) can be increased (indicated by T and t in the figure), and the temperature gradient between them can be increased. That is, if the plate thickness is thin, the heat receiving portion 13a tends to reach a high temperature, and a sufficient temperature gradient cannot be ensured between the heat receiving portion 13a and the nozzle 12.
According to this modification, it is possible to accurately suppress the temperature rise around the nozzle 12.

What is shown in FIG. 6 is the heat radiation part 1 of the heat radiation member 13.
A large number of holes 15 for circulating intake air to 3b...
It has been established. As shown in the figure, the hole area is set to be larger on the distal end side, and is configured to ensure sufficient heat dissipation in the entire heat dissipation part 13b. With this configuration, the heat dissipation member 13
Not only can the cooling performance of the heat radiating portion 13b be improved by allowing intake air to flow inside, but also the present invention can promote atomization and vaporization of the fuel injected in a liquid state. Furthermore, this modification can also be combined with the bellows structure in the above embodiment.
As shown in FIG. 4, if the tip 9a of the needle valve 9 is extended within the heat radiating member 13, the hole 15...
It is also possible to further suppress vaporization of fuel during fuel injection by cooling the needle valve 9 itself with the intake air flowing in from the fuel injection valve. In this case, the needle valve tip 9
Grooves 16 may also be formed on the outer surface of a to expand the heat dissipation area.

In the one shown in FIG. 7, spiral fins 17 are provided on the outer peripheral side of the heat dissipating member 13 to improve heat dissipation.

Furthermore, although not shown in the drawings, in the above embodiments and the above modifications, the nozzle may be configured to face the heat radiating member or the heat radiating member may be opposed to the nozzle so that the injected fuel collides with the heat radiating member. good. With this configuration, the fuel can absorb the heat of vaporization from the heat radiating member, and the heat radiating member can also be cooled, so that the heat dissipation performance of the heat radiating member and the vaporization of the fuel can be promoted at the same time. can.

[Effect of idea]

In summary, the present invention provides the following effects.

(1) The heat-insulating space surrounding the fuel flow path and the heat dissipation member surrounding the fuel nozzle and extending into the intake pipe suppress the rise in temperature of the fuel injection valve and inject the fuel in a vaporized state. It is possible to prevent this from occurring and ensure a predetermined fuel injection amount.

(2) Therefore, engine malfunctions such as rough idle and engine stall can be prevented even when the engine is operated at low speed with a high intake pipe temperature or when highly volatile fuel is used.

(3) The structure is simple and can be easily adopted.

[Brief explanation of the drawing]

Figures 1 to 3 are side sectional views showing conventional examples;
The figure is a side sectional view showing a preferred embodiment of the present invention.
The figure is a side cross section of a modified embodiment in which the plate thickness of the heat radiating member adopted in the present invention is changed between the heat receiving part and the heat radiating part, and an explanation showing the relationship between the temperature distribution of the heat radiating member and the temperature near the nozzle due to the change. 6 and 7 are front views showing modified examples of the heat radiating member employed in the present invention. In the figure, 1 is an intake pipe, 3 is a fuel injection valve, 4 is a valve housing, 5 and 6 are support members, 8 is a heat insulation space, 1
2 is a fuel nozzle, 13 is a heat dissipation member, 15 is a hole, 2
0 is the fuel flow path.

Claims (1)

[Claims for Utility Model Registration] (1) A valve housing of a fuel injection valve having a fuel flow path formed therein and a fuel nozzle formed at its tip, and an intake pipe to which the valve housing is attached via a support member. In between, one end surrounds the fuel nozzle and the other end surrounds the fuel flow path to form a heat insulating space, and between the tip of the valve housing and the support member, in order to radiate heat around the fuel nozzle. A fuel injection device for an internal combustion engine that is provided with a cylindrical heat dissipating member that extends into an intake pipe. (2) The fuel injection device for an internal combustion engine according to claim 1, wherein the heat radiating member is formed in a bellows shape to enlarge its heat radiating area. (3) In order for the heat dissipation member to circulate the intake air,
The fuel injection device for an internal combustion engine according to claim 1 or 2, wherein the fuel injection device for an internal combustion engine is provided with a large number of holes having an opening area that gradually increases toward the other end on the intake pipe side.