JP2555626B2 - Fuel injection device for internal combustion engine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection device for an internal combustion engine used in a vehicle such as an automobile, and more particularly to a fuel injection device for injecting liquid fuel such as gasoline.

2. Description of the Related Art A fuel injection device for an internal combustion engine generally has a needle valve type fuel injection valve, and the fuel injection valve is designed to inject liquid fuel such as gasoline from an injection hole opened and closed by a needle valve element. Has become. This type of fuel injection device is disclosed, for example, in Japanese Utility Model Publication Nos. 57-136864 and 61-73069.

The fuel injection valve has a valve seat member having an injection hole and a valve seat surface extending around the injection hole, and a needle receiving hole having the valve seat surface as a bottom surface, and the needle receiving hole having the valve seat member. A needle valve element that is movably inserted in the axial direction and that closes the injection hole by seating on the valve seat surface at the tip, and the needle valve element is separated from the valve seat surface When the hole is opened, a gap between the needle valve element and the needle receiving hole, or in the case where the needle valve element has a hollow structure, a hollow portion and a penetrating hole provided in the vicinity of the tip of the needle valve element. Liquid fuel flows through the holes and is ejected from the injection holes.

Problems to be Solved by the Invention In the conventional fuel injection valve, when the needle valve element is seated on the valve seat surface and the injection hole is closed, a gap between the needle valve element and the needle receiving hole is formed. When the needle valve element has a hollow structure, the hollow portion and the through hole provided in the vicinity of the tip of the needle valve element, and further, the vicinity of the injection hole becomes a blind alley and stays in the liquid fuel in these portions. Come to do. Therefore, when the closed state of the fuel injection valve continues for a long time at high temperature due to engine stop or the like, the liquid fuel staying in the fuel passage in the fuel injection valve as described above is vaporized and the above-mentioned liquid fuel in the fuel injection valve is evaporated. Bubbles are generated in the fuel passage as described above, and a so-called vapor lock state is generated. When the above-described state occurs, the liquid fuel is not promptly injected from the fuel injection valve, so that a restart failure occurs at the time of high temperature restart, and there is a problem that the idle stability after the start becomes poor.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an improved fuel injection device for an internal combustion engine which solves the above problems.

Means for Solving the Problems According to the present invention, the above object is to provide a nozzle hole, a valve seat surface extending around the nozzle hole, and a needle receiving surface having the valve seat surface as a bottom surface. A valve seat member having a hole, and a needle seat hole in which the fuel is allowed to flow, and a peripheral edge gap is left between the seat member and the needle seat hole so as to be movable in the axial direction thereof, and the tip end is seated on the valve seat surface to form the injection hole. In the fuel injection device for an internal combustion engine, the needle valve is configured as a hollow structure and has a through hole through which fuel is supplied into the hollow portion and flows out to the nozzle hole near the tip. The valve seat member has a lateral through opening that crosses the axis of the needle receiving hole substantially vertically and exposes a part of the needle valve mounted in the needle receiving hole to the outside of the valve seat member. Having the needle valve in the lateral direction A fuel intake hole that communicates the hollow portion of the needle valve with the lateral through-opening is provided at a portion exposed in the through-hole, and the inside of the lateral through-opening is changed from one end to the other end. An impingement wall is provided for guiding a fuel flow flowing toward the fuel intake hole of the needle valve, and a fuel passage for feeding pressurized fuel and the fuel passage are crossed substantially vertically. A delivery member having a fuel injection device mounting hole, wherein the lateral through opening is aligned with the fuel passage into the fuel injection device mounting hole, and a fuel flow flowing in the fuel passage is directed to the fuel of the needle valve by the impact wall. This is achieved by a fuel injector characterized in that it is adapted to be mounted towards the intake hole.

According to the above-described structure, the fuel intake hole of the needle valve allows the fuel to be introduced by the abutment wall as long as pressurized fuel is fed through the fuel passage of the delivery member. In addition to the static pressure, some dynamic pressure is constantly exerted. When the needle valve is pulled up from the valve seat surface in this state and the injection hole is opened, the fuel mainly enters into the hollow of the needle valve through the fuel intake hole due to its static pressure, and the fuel near the tip of the needle valve is The fuel reaches the fuel chamber around the valve seat surface outside the needle valve through the injection hole, and then is injected through the injection hole. When the tip of the needle valve is seated on the valve seat surface and the needle valve is in the closed state, the static pressure of fuel acting on the fuel intake hole of the needle valve and the lateral gap of the peripheral edge between the needle receiving hole and the needle valve. It is the same as the static pressure of the fuel that acts on the end exposed in the directional through opening, but some dynamic pressure is applied to the fuel intake hole of the needle valve due to the attraction of the fuel flow by the abutment wall. Therefore, the dynamic pressure causes the hollow part of the needle valve from the fuel intake hole of the needle valve, the injection hole near the tip of the needle valve, the fuel chamber around the valve seat surface, and the peripheral clearance between the needle receiving hole and the needle valve. A slight fuel flow occurs via the path through to the lateral through opening. Even with such a slight flow of fuel, if there are air bubbles of fuel in these spaces, the air bubbles will not stay at those positions and will eventually cause a peripheral gap between the needle receiving hole and the needle valve. Through which it is discharged into the lateral through opening.

Example Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1 and 2 show one embodiment of a fuel injection device for an internal combustion engine according to the present invention. In the figure, 10 is a delivery member and 20 is a fuel injection valve.

The fuel injection valve 20 has a cylindrical housing 22, and the housing 22 houses a valve seat member 24 therein. The valve seat member 24 is inserted into the tubular portion 46 of the housing 22 together with the nozzle adapter 40 and the stopper member 44, and is fixed to the housing 22 by caulking the tip portion of the tubular portion 46. Valve seat member
The nozzle 24 has an injection hole 26, a conical valve seat surface 28 provided around the injection hole 26, and a needle receiving hole 30 having the valve seat surface 28 as a bottom surface.

The nozzle adapter 40 is attached to the tip of the housing 22, and has two jet flow guide holes 42 for changing the jet flow of the liquid fuel ejected from the jet holes 26 into two jet flows.

A needle valve element 50 is inserted into the needle receiving hole 30 so as to be movable in the axial direction. The needle valve element 50 is composed of a hollow needle valve body 52 and a steel ball 54 fixed to the tip of the hollow needle valve body by an appropriate means such as welding,
The steel ball 54 closes the tip of the hollow portion 56 of the hollow needle valve body 52 and selectively sits on the valve seat surface 28 to control the opening and closing of the injection hole 26.

The hollow needle valve body 52 has a plurality of fuel intake holes 58 for taking in the liquid fuel into the hollow portion 56 in the vicinity of the end opposite to the mounting end of the steel ball 54. A plurality of fuel ejection holes (through holes) 60 for letting out the liquid fuel from the hollow portion 56 to the fuel chamber 62 formed at the bottom of the needle receiving hole 30 are provided near the mounting end portion of 54, that is, near the tip. There is. The fuel intake hole 58 is open to a notch portion 45 provided as a fuel passage in the stopper member 44, and the notch portion 45 communicates with a fuel flow hole 64 provided in the tubular portion 46 of the housing 22. There is.

The stopper member 44 is sandwiched between the land portion 25 projectingly formed on the end surface portion of the valve seat member 24 and the intermediate partition wall 47 of the housing 22 and fixed to the housing 22, and is axially spaced from each other in the hollow needle valve body 56. It is adapted to engage between two stopper flanges 53 and 55 provided so as to regulate the axial movement amount of the needle valve element 50 to a predetermined amount.

Inside the other tubular portion 66 of the housing 22, a cylindrical electromagnetic coil member 68 is provided with a flange portion 70 as an end cap.
Is integrally fixed to the housing 22 by caulking at the end of the tubular portion 66 together with the pipe-shaped core member 72.

A shaft body 80 is inserted and fixed in the hollow portion 71 of the core member 70, and a compression coil spring 82 is mounted between the shaft body 80 and the needle valve element 50. The compression coil spring 82 biases the needle valve element 50 downward in the drawing, that is, in the direction in which the steel ball 54 is seated on the valve seat surface 28, in other words, in the valve closing direction.

The core member 72 faces the cylindrical armature member 76 fixed to the needle valve element 50 at its tip 74, and is selectively excited by the electromagnetic coil member 68 to generate a compression coil spring.
The needle valve element 50 is moved upward in the figure against the spring force of 82,
That is, the steel ball 54 is moved in the direction in which it is separated from the valve seat surface 28, in other words, in the valve opening direction.

An energizing connection terminal member 84 for energizing the electromagnetic coil member 68 is attached to the flange portion 70 of the core member 72.

The outer diameter of the hollow needle valve element 52 of the needle valve element 50 is smaller than the inner diameter of the needle receiving hole 30 by a predetermined amount, whereby a gap 90 through which liquid fuel can flow is formed between the hollow needle valve element 52 and the receiving hole 30. ing. The gap 90 extends over the entire axial direction of the needle receiving hole 30 and has a fuel chamber 62 at one end.
And communicates at the other end with a gap 92 formed between the valve seat member 24 and the stopper member 44. As shown in FIG. 2, the gap 92 is formed by intermittently providing the land portion 25 around the circumference of the valve seat member 24.
It communicates with the fuel flow hole 64 through a gap 94 therebetween.

The entire fuel injection valve 20 is inserted into a fuel injection valve receiving hole 12 formed in the delivery member 10 and held by the delivery member 10. Fuel injection valve receiving hole 12
Although only one is shown in the drawing, it is provided in the same number as the number of cylinders because the fuel injection valve 20 is provided for each cylinder. Delivery material
Each of the fuel injection valve receiving holes 12 has a cylindrical portion 46 of the fuel injection valve 20.
Has a ring-shaped fuel passage 14 that annularly extends around and communicates with the fuel flow hole 46, and a fuel passage 16 that connects and connects the ring-shaped fuel passages 14 to each other. It is connected to a fuel pump (not shown) at the right end, and communicates with the fuel return passage through a pressure regulator for fuel pressure setting (not shown) at the left end in the figure.

As is often shown in FIG. 2, a plurality of fuel circulation holes 64 of the fuel injection valve 20 are provided around the circumference of the cylindrical portion 46, and among the fuel circulation holes 64, the upstream side of the delivery member 10 is provided. Of the fuel passage 16, that is, the one on the right side in the drawing acts as a fuel inlet, while the side of the fuel passage 16 on the downstream side, that is, the one on the left side in the drawing acts as a fuel outlet. .

In this type of fuel injection device, fuel pressurized by a fuel injection pump (not shown) flows through the fuel passage 16 regardless of whether the needle valve is open or closed during engine operation. The notch 45 of the stopper member 44 has the function of guiding the fuel flow flowing across the fuel passage 16 and the fuel passage hole 64 in the middle toward the fuel intake hole 58 of the needle valve even when the needle valve is closed. None, so that some fuel dynamic pressure is constantly acting on the fuel intake hole 58 during operation of the fuel pump. Therefore, when the needle valve is closed, the fuel intake pressure 58, the hollow portion 56,
A slight fuel flow is generated through the fuel outlet hole 60, the fuel chamber 62, the gaps 90, 92, 94 to the fuel flow hole 64 located on the downstream side of the needle valve. Due to the fuel flow generated when the needle valve is closed, when bubbles of fuel are present in these spaces, the bubbles are sequentially discharged into the fuel flow hole 64 on the downstream side, and pass through the fuel passage 16 on the downstream side. Is discharged.

Incidentally, between the valve seat member 24 and the tubular portion 46 of the fuel injection valve 20, between the tubular portion 66 and the electromagnetic coil member 68, between the electromagnetic coil member 68 and the core member 72, the core member 72 and the shaft. O-rings 100, 102, 104, 106 for preventing the liquid fuel from leaking to the outside are provided between the member 80 and the member 80. In order to prevent liquid fuel from leaking to the outside between the delivery member 10 and the tubular portion 46 of the fuel injection valve 20 and between the delivery member 10 and the tubular portion 66 of the fuel injection valve 20, respectively. O-ring 108
And 110 are provided.

Liquid fuel such as gasoline supplied to the fuel passage 16 of the delivery member 10 from a fuel pump (not shown) flows through the annular fuel passage 14 into the tubular portion 46 through the fuel flow hole 64 of the fuel injection valve 20, Further, it passes through the cutout portion 45 of the stopper member 44 and enters the hollow portion 56 through the fuel intake hole 58 of the needle valve element 50, flows through the hollow portion 56, and passes through the fuel extraction hole 60 and the needle receiving hole.
Enter the fuel chamber 62 at the bottom of 30.

The electromagnetic coil member 68 is energized and the needle valve element 50
Is moved upward in the figure and the steel ball 54 is in the valve open position separated by the valve seat surface 28, the liquid fuel in the fuel chamber 62 is filled with the injection holes 26.
It jets out toward the jet flow guide hole 42.

The electromagnetic coil member 68 is not energized, the needle valve element 50 is urged downward in the figure by the spring force of the compression coil spring 82, and the steel ball 54 is seated on the valve seat surface 28. In the position, the liquid fuel in the fuel chamber 62 is connected to the needle valve element 50.
Between the needle receiving hole 30 and the needle receiving hole 30.
Flows in the axial direction to reach the gap 92, and
Excess fuel from the fuel flow hole 64 via 94 and delivery member 10
Is sent to the fuel passage 16 and flows toward the downstream side.

As described above, even if the fuel injection valve 20 is in the closed state, there is no portion where the liquid fuel stays in the fuel injection valve 20, so that vapor lock is prevented from occurring in the fuel injection valve 20. become. Further, even if bubbles are generated in the fuel injection valve 20, the bubbles are promptly discharged to the outside of the fuel injection because the liquid fuel is flowing even when the valve is closed during engine operation as described above. become.

Although the specific embodiments of the present invention have been described in detail above, the present invention is not limited to these.
It will be apparent to those skilled in the art that various embodiments are possible within the scope of the invention.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing one embodiment of a fuel injection device for an internal combustion engine according to the present invention, and FIG. 2 is an enlarged sectional view taken along the line II-II in FIG. 10 ... Delivery member, 12 ... Fuel injection valve receiving hole, 14 ... Annular fuel passage, 16 ... Fuel passage, 16a ... Fuel supply passage, 16b
...... Fuel return passage, 20 ...... Fuel injection valve, 22 ...... Housing, 24 ...... Valve seat member, 25 ...... Land part, 26 ...... Injection hole, 28 ......
Valve seat surface, 30 …… needle receiving hole, 40 …… nozzle adapter,
42 …… Jet flow guide hole, 44 …… Stopper member, 45 …… Notch, 4
6 …… Cylindrical part, 47 …… Intermediate bulkhead, 50 …… Needle valve element, 52
...... Hollow needle valve body, 53 ...... Stopper flange, 54 ......
Steel ball, 55 …… Stopper flange, 56 …… Hollow part, 58 …… Fuel intake hole, 60 …… Fuel outflow hole, 62 …… Fuel chamber, 64 …… Fuel flow hole, 66 …… Cylindrical part, 68 ...... electromagnetic coil member, 69 ...... fuel passage hole, 70 ...... flange portion, 71 ...... hollow portion, 72 ...... core member, 73 ...... fuel passage hole, 74 ...... tip portion, 76 ...... armature, 77 …… Hollow part, 80 …… Shaft, 81 …… Fuel passage hole, 82…
… Compression coil spring, 84 …… energizing connection terminal, 85 …… connector housing, 90, 92, 94 …… gap, 96 …… fuel inlet, 9
8 ... Fuel passage, 100, 102, 104, 106, 108, 110, 112 ...
… O-ring

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-57-171073 (JP, A) JP-A-62-129566 (JP, A) Actually open 61-73069 (JP, U) Actual-open Sho 61- 167472 (JP, U)

Claims (1)

(57) [Claims] 1. A valve seat member having an injection hole, a valve seat surface extending around the injection hole, and a needle receiving hole having the valve seat surface as a bottom surface, and a fuel in the needle receiving hole. A needle valve that is inserted movably in the axial direction of the valve while leaving a peripheral gap such that the needle valve closes the injection hole by seating on the valve seat surface at the tip, and the needle valve has a hollow structure. In a fuel injection device for an internal combustion engine having a through hole through which fuel is supplied to the hollow portion and fuel flows out to the injection hole, the valve seat member substantially defines the axis of the needle receiving hole. Has a lateral through opening for exposing a part of the needle valve mounted in the needle receiving hole to the outside of the valve seat member, and the needle valve is exposed in the lateral through opening. Hollow part of the needle valve A fuel intake hole communicating with the lateral through-opening is provided, and a fuel flow flowing in the lateral through-opening from the one end toward the other end is supplied to the fuel intake hole of the needle valve. The fuel injection device mounting of the delivery member is provided with an impingement wall for guiding the fuel toward it, and has a fuel passage for feeding pressurized fuel and a fuel injection device mounting hole that crosses the fuel passage substantially vertically. The lateral through opening is aligned with the fuel passage into the hole, and is mounted so that the fuel flow flowing in the fuel passage is directed toward the fuel intake hole of the needle valve by the impact wall. A fuel injection device characterized by the above.