JPH07310630A - Fuel injection device - Google Patents

Abstract

PURPOSE:To reduce cost, to ensure fastening of a fuel injection valve body and an atomizer against each other, to reduce the weight and the cost of a material of which an adapter body is formed by a method wherein a mass- production finish product of a fuel injection valve body not needing an assist air type can be applied as it is without additional processing. CONSTITUTION:Formation of an assist air type fuel injection valve is such that an air fuel mixing means 7 having a mixture passage 8 for fuel and air is arranged at the tip of a nozzle part 4 arranged downstream from the moving valve 3 of an injection valve body 1 to intermittently meter a fuel flow rate and fuel is atomized. In the assist air type fuel injection valve, a lock auxiliary member 10 provided with an escape part 25 to introduce assist air is fixed and the air fuel mixing means 7 is secured to the nozzle part 4 through the lock auxiliary member 10 by welding at 11 and formed of a synthetic resin member.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a fuel injection device,
In particular, the present invention relates to an assist air type fuel injection device that atomizes fuel with air.

[0002]

2. Description of the Related Art In recent years, there have been increasing demands for improving exhaust gas purifying performance and fuel consumption of internal combustion engines. As one of the methods to satisfy these requirements at the same time, it is effective to improve the vaporization rate of the fuel, and for this purpose, the fuel injected from the fuel injection valve collides with the air flow and is mixed to form fine particles. There is known an assist air type fuel injection valve for performing the conversion (for example, see Japanese Utility Model Laid-Open No. 5-17164).

In such a conventional fuel injection valve,
There is a nozzle tip on the downstream side from the fuel injection port, and
Since the fuel is a side-feed type in which the fuel flows in from the radial direction of the central portion of the injection valve body, an O-ring groove for fuel sealing is provided on the outer periphery of the nozzle, and the O-ring groove position is located closer to the tip side than the injection port portion. There is. In the case of adopting such a nozzle configuration, in order to attach the adapter that mixes the fuel and the air, the bag-shaped space formed by the nozzle injection port and the nozzle inner diameter is used for installation and fastening. There is. If this is done by press fitting the outer diameter of the adapter and the inner diameter of the nozzle, not only precision processing is required for the outer diameter of the adapter and the inner diameter of the nozzle, but also because the nozzle is heat treated, additional machining is required. However, there is a problem in that the mass production of injectors that do not require assist air cannot be diverted and a dedicated nozzle must be used.

[0004]

In the conventional assist air type fuel injection valve as described above, when the outer diameter of the adapter and the inner diameter of the nozzle are fastened by press fitting, the outer diameter of the adapter and the inner diameter of the nozzle are precisely machined. Not only is it necessary, but it is difficult to perform additional machining because the nozzle is heat-treated. Therefore, it is not possible to use mass-produced injectors that do not require assist air, and high precision suitable for fitting before and after heat treatment. There is a problem that it is necessary to use a dedicated nozzle that has been processed.

Further, when fastening the adapter and the nozzle by press fitting, it is necessary to reduce the difference in the coefficient of thermal expansion between the adapter and the nozzle in consideration of the influence of the temperature, which causes a problem that the degree of freedom in selecting the material is small. It was. These have been obstacles to the provision of inexpensive assist air fuel injection valves. The present invention has been made in view of such a problem, and an object thereof is to allow a mass-produced finished product of a fuel injection valve body that does not require an assist air type to be diverted as it is without additional work. It is possible to reduce costs,
Moreover, it is an object of the present invention to provide an assist air type fuel injection valve which can secure the fastening of the fuel injection valve main body and the atomizer and can make the material of the adapter main body lightweight and inexpensive.

[0006]

In order to achieve the above-mentioned object, a fuel injection device according to the present invention has a tip of a nozzle portion provided downstream of a movable valve of an injection valve body for intermittently measuring a fuel flow rate. In an assist air type fuel injection valve for atomizing fuel by providing an air / fuel mixing means having a fuel / air mixing passage, the air / fuel mixing means is provided with a relief portion for introducing assist air. The locking auxiliary member is fixed and is a synthetic resin member fixed to the nozzle portion by welding via the locking auxiliary member.

As a more specific example, the locking assist member is integrally fixed to the air / fuel mixing means by insert molding, the welding is laser welding, The contact surface between the locking assisting member and the nozzle portion is a surface that is substantially perpendicular or parallel to the axial direction of the injection valve body, and is a member that is integrally fixed to the air / fuel mixing means by the insert molding. The anti-welding side of the stop assist member is exposed near the fuel injection port, and the like.

According to another aspect of the present invention, an air / fuel mixture passage having a mixture of fuel and air is provided at a tip of a nozzle portion provided downstream of a movable valve of an injection valve body for intermittently measuring a fuel flow rate. In an assist air type fuel injection valve for providing fuel mixing means for atomizing fuel, in the air / fuel mixing means, a locking auxiliary member provided with a relief portion for introducing assist air is fixed, It is characterized in that it is fixed to the nozzle portion by a fitting structure through the locking auxiliary member.

In this case, the fitting structure has a portion that restricts mutual rotation of the air / fuel mixing means and the locking auxiliary member, or the locking auxiliary member is the air / fuel. The ratio of the thermal expansion coefficient of the locking auxiliary member locked to the mixing means and the thermal expansion coefficient of the nozzle is 1/3 to
It is preferably selected to be in the range of 3.0.

[0010]

In the fuel injection valve according to the present invention constructed as described above, the fitting tolerance for maintaining the strength between the adapter and the inner diameter portion of the nozzle is unnecessary, and the secure fastening without additional machining such as the inner diameter of the nozzle. You can secure power. Further, since the injection valve main body can use a mass-produced finished product that does not require the assist air type, it is possible to aim at cost reduction together with a sure measure for preventing the adapter from falling off.

Furthermore, since the fastening force can be secured by welding the locking assisting member and the nozzle, the adapter body can be made of synthetic resin, and a lightweight and low cost assist air fuel injection valve can be constructed. it can.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In the drawings for explaining the respective embodiments, the portions corresponding to the respective portions are designated by the same reference numerals, and their duplicate description will be omitted. FIG. 1 is an enlarged sectional view of a main part of a fuel injection device according to an embodiment of the present invention. The main body of a fuel injection valve (hereinafter referred to as an injector) 1 of the illustrated example is a side feed type in which fuel is introduced from a lateral surface of a substantially central portion of the injector main body 1, and the fuel enters an injector holder 18 from a fuel pipe 17. The fuel is passed through the fuel filter 2 locked by the injector 1 to enter the inside of the injector 1. This fuel is controlled and metered by the movable valve 3 which moves up and down by an electromagnetic force and the orifice 5 provided in the nozzle 4. Next, the fuel measured by the orifice 5 is branched into two directions by a branch space 6 integrally formed with the nozzle 4, is made of synthetic resin, and is air / fuel mixing means for mixing air and fuel. Internal space 8 of the adapter (hereinafter referred to as atomizer) 7
It is designed to be ejected to the outside through the.

At this time, the fuel and air are mixed in the internal space 8 to promote atomization of the fuel. The air passes through the air introducing pipe 19 welded and fixed to the injector holder 18, and then the intake manifold. An air seal 20 provided on the upper surface of 12 and a space 22 closed by an O-ring 16 (which also serves as a fuel seal and an air seal) pass through the assist air passage 9 to reach the internal space 8.

The assist air passage 9 is composed of a vertical groove 9a and a lateral hole 9b provided in the outer diameter portion of the atomizer 7, and is used for connecting the air passage 9 with the space 22. It is necessary to provide a relief portion 25 in the locking assist member 10. In this embodiment, in order to fasten the atomizer 7 to the injector 1, the fastening assisting member 10 for fastening, which is made of metal such as stainless steel, is insert-molded integrally with the atomizer 7 made of synthetic resin, The welding portion 11 separated from the locking assist member 10 and the orifice 5 of the nozzle 4 by a predetermined dimension or more, for example,
It is welded and fixed by laser welding or the like to prevent the atomizer 7 from falling off. Here, the predetermined dimension is necessary to avoid deformation in the vicinity of the orifice 5 due to heat during welding, and it has been experimentally found that it is 2 mm or more.

As described above, since the material of the locking assisting member 10 is the stainless material having the ratio of the thermal expansion number to the nozzle is 3 times or less, the stress on the welded portion due to the temperature change becomes excessive. It does not add and there are no problems such as cracks. Further, it is possible to prevent the reliability of the welded part from being lowered due to the generation of strain due to the cold heat cycle in the use state. As described above, the additional work to the injector body 1 only requires the atomizer 7 to be inserted, the positioning to be performed by an appropriate method, and welding with the locking assisting member 10. Therefore, the injector body 1 is of the assist air type. It is possible to use a mass-produced finished product that does not require, and to produce an excellent effect that the cost can be reduced because the production process is not changed.
Further, since the atomizer can also be a plastic molded product, the goal of light weight and low cost can be achieved.

FIG. 2 shows another embodiment of the present invention, in which a mass-produced finished product of a top feed type injector in which fuel is introduced from the axially upper end portion of the injector body is diverted to be an assist air injector, which is used in an automobile. FIG. 3 is an enlarged cross-sectional view of a main part near a nozzle part in a state where the nozzle part is mounted on a commercial engine.
In this embodiment, the shape of the mass production nozzle 4 of the injector 1 is different from that of FIG. 1, and the welded portion 1 is formed on the outer peripheral surface of the nozzle 4.
1 is provided (that is, the contact surface between the locking assisting member and the nozzle portion is a surface substantially parallel to the axial direction of the injection valve body).
The difference is that the atomizer 7 is provided with a radial O-ring groove for air seal.

The locking assisting member 10 is insert-molded on the atomizer 7, and the fuel atomizing air passes through the air passage 13 communicating with each cylinder of the intake manifold 12 of the engine and the insulator 14 and the O-ring 15. This is an example in which the structure is introduced to the space 22 that is sealed by, and reaches the assist air passage 9b via the assist air introduction escape portion 25 provided in the locking assist member 10. However, in the present embodiment, since welding is performed in the cylindrical inner diameter of the locking auxiliary member and the outer diameter direction of the nozzle 4, it is necessary to improve the inner diameter accuracy of the locking auxiliary member or insert a slit or the like to provide elasticity. is there. Further, since the locking auxiliary member 10 is provided outside the outer diameter of the nozzle 4 and the welded portion 11 is further formed on the outer side thereof, this locking is performed when there is no space in the outer diameter direction of the nozzle. There remains a problem that the method of locking the auxiliary member and the nozzle is disadvantageous.

FIG. 3 is another embodiment of the present invention and is an enlarged cross-sectional view of the main part near the nozzle part. In this embodiment, the O-ring 15 is air-sealed by providing a groove in the outer diameter direction of the atomizer 7. Further, in the welded portion 11, the locking assisting member 10 and the tip of the nozzle 4 are abutted with each other in a substantially vertical plane of the injection valve axis, as in FIG. Since the amount of protrusion can be reduced, the air supply passage around the atomizer 7 can be easily configured. That is, by providing the intake manifold 21 with the air passage 13 and the air distribution passage 23, the air pipe 1 of FIG.
9 can be eliminated. Furthermore, in this illustrated example, a side feed type injector is used, and an injector holder 18 is also provided in the intake manifold 21,
The injector holder 18 can also be omitted, and an inexpensive assist air injector with the minimum number of parts can be constructed.

4 and 5 show another embodiment of the present invention.
4 is an enlarged cross-sectional view of the main part near the nozzle, and FIG.
FIG. 5 is an enlarged side view of an essential part viewed from the arrow V direction of FIG. The present embodiment is the same in that the locking assisting member 10 used for fastening the nozzle 4 and the atomizer 7 is used, but the atomizer 7 and the locking assisting member 10 are separate bodies, and a fitting structure is provided. Has been adopted. Further, a notch 19 is provided in a portion that restricts mutual rotation of the atomizer 7 and the locking auxiliary member 10, and a projection 18 is provided on the atomizer 7 to combine them. The long hole 25 is an escape groove for letting in air. According to this embodiment, a mass-produced injector that does not require an assist type can be used without using an insert mold, and a lightweight and low cost can be achieved by an atomizer of a plastic molded product.

FIG. 6 is another embodiment of the present invention, and is an enlarged cross-sectional view of the main portion around the nozzle portion. In this embodiment, the locking auxiliary member 10 that is insert-molded in the atomizer 7 is used.
And the nozzle 4 are fastened at the welded portion 11, and the end face 23 of the locking assisting member 10 in the direction opposite to the welded portion 11 side is exposed from the mold in the vicinity of the jet 24 of the mixed spray of fuel and air. take. Here, the internal fuel wall flow of the atomizer 7 is dammed by the end face 23 of the locking assist member from radially flowing from the ejection port 24, and the dammed fuel is ejected together with the spray before the end fuel is crossed over the end face 23. By doing so, it is possible to also serve to reduce the dripping of the injected fuel.

[0021]

As can be understood from the above description, according to the present invention, a mass-produced finished product of a fuel injection valve body which does not require an assist air type can be diverted as it is without any additional work or the like. Cost can be reduced, and moreover,
The fastening of the fuel injector main body and the atomizer can be ensured, and the material of the adapter main body can be made lightweight and inexpensive.

[Brief description of drawings]

FIG. 1 is an enlarged cross-sectional view of a main part of a fuel injection device according to an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view of a main part in the vicinity of a nozzle part, which is another embodiment in which the present invention is applied to a top feed type injection valve.

FIG. 3 is another embodiment of the present invention, which is an enlarged cross-sectional view of a main part in the vicinity of a nozzle part showing an example of the cheapest system configuration.

FIG. 4 is an enlarged cross-sectional view of a main part in the vicinity of a nozzle part showing another example of the present invention, in which a press fit is used for locking the atomizer and the locking auxiliary member.

5 is an enlarged side view of an essential part as seen from the direction of arrow V in FIG.

FIG. 6 is an enlarged cross-sectional view of a main part in the vicinity of a nozzle part showing another example of the present invention, which is a configuration example in which a dripping fuel drop reduction function is added.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Fuel injection valve (injector) main body 2 ... Fuel filter 3 ... Movable valve 4 ... Nozzle 5 ... Fuel metering orifice 6 ... Fuel spray branch space 7 ... Fuel atomization adapter (atomizer) main body 8 ... Air and fuel Internal space of atomizer for mixing 9 ... Assist air passage 9a ... Vertical groove (assist air passage) 9b ... Horizontal hole (assist air passage) 10 ... Atomizer fastening locking auxiliary member 11 ... Nozzle and atomizer weld 12 ... Intake Manifold 13 ... Assist air supply passage 14 ... Insulator (for air seal) 15 ... O ring (for air seal) 16 ... O ring (for air seal and fuel seal) 17 ... Fuel pipe 18 ... Injector holder 19 ... Air pipe 20 ... Insulator (intake pipe Negative pressure and assist air seal) 21 ... Integrated intake manifold Hold (injector holder and air passage integrated) 22 ... Space closed by air seal 23 ... Air distribution passage 24 ... Mixed spray jet 25 ... Assist air introduction escape portion

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kiichi Hoshi 2520 Takaba, Katsuta City, Ibaraki Prefecture, Hitachi Automotive Systems Division (72) Inventor Morio Kuwano 2520, Takata, Katsuta, Ibaraki Hitachi, Ltd. Mfg. Co., Ltd. Automotive Equipment Division (72) Inventor, Kyori Yamamoto 2520 Takaba, Katsuta, Ibaraki Prefecture Hitachi, Ltd. Automotive Equipment Division (72) Osamu Sandai 2520, Takata, Katsuta City, Ibaraki Hitachi, Ltd. Equipment Division

Claims (9)

[Claims] 1. An air / fuel mixing means having a mixing passage for fuel and air is provided at the tip of a nozzle portion provided downstream of a movable valve of an injection valve main body for intermittently measuring a fuel flow rate, and fine particles of fuel are provided. In the assist air type fuel injection valve for performing air-conditioning, the air / fuel mixing means is fixed to a locking auxiliary member provided with a relief portion for introducing assist air, A fuel injection device characterized by being a synthetic resin member fixed to a nozzle portion by welding. 2. The fuel injection device according to claim 1, wherein the locking assisting member is integrally fixed to the air / fuel mixing means by insert molding. 3. The fuel injection device according to claim 1, wherein the welding is laser welding. 4. The fuel injection device according to claim 1, wherein a contact surface between the locking assisting member and the nozzle portion is a surface substantially perpendicular to the axial direction of the injection valve body. 5. The fuel injection device according to claim 1, wherein a contact surface between the locking assisting member and the nozzle portion is a surface substantially parallel to an axial direction of the injection valve body. 6. The anti-welding side of the locking auxiliary member integrally fixed to the air / fuel mixing means by the insert molding is exposed near the fuel injection port. Fuel injector. 7. An air / fuel mixing means having a fuel / air mixing passage is provided at the tip of a nozzle portion provided downstream of a movable valve of an injection valve body for intermittently measuring a fuel flow rate, and fine particles of fuel are provided. In the assist air type fuel injection valve for performing air-conditioning, the air / fuel mixing means is fixed to a locking auxiliary member provided with a relief portion for introducing assist air, A fuel injection device, characterized in that the fuel injection device is fixed to the nozzle portion by a fitting structure. 8. The fuel injection device according to claim 7, wherein the fitting structure has a portion that restricts mutual rotation of the air / fuel mixing means and the locking auxiliary member. 9. The locking auxiliary member has a ratio of a thermal expansion coefficient of the locking auxiliary member locked to the air / fuel mixing means to a thermal expansion coefficient of the nozzle in a range of 1/3 to 3.0. The fuel injection device according to claim 1 or 7, wherein the fuel injection device is selected as follows.