JP2512486B2 - Fuel lock prevention structure for fuel injection device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vapor lock prevention structure for a fuel injection device that supplies fuel to an engine.

(Prior Art) Conventionally, vapor generated from fuel at high temperature is, for example, as described in Japanese Patent Publication No. 61-24544.
The fuel outlet transmission passage 28b is positioned above the fuel inlet transmission passage 28a to prevent vapor or bubbles mixed in the fuel from reaching the fuel injection device.

(Problems to be solved by the invention) However, in this case, no consideration is given to the removal of steam or bubbles generated in the fuel injection device, and the amount of fuel staying in the fuel injection device is reduced as much as possible. However, there is a defect that the bubbles generated in the fuel injection device make the air-fuel mixture air-fuel ratio lean at the time of engine starting, and deteriorate the starting characteristics of the engine.

(Means for Solving the Problem) The present invention for solving the above problem is directed to fuel injection in which liquid fuel supplied from the side of the valve is intermittently injected from a nozzle at the tip of the valve by reciprocating movement of the valve driven by an actuator. A vapor lock prevention structure for the device,
A fuel reservoir upper portion of a valve rear end portion of the fuel injection device and a fuel passage formed at a side of the valve higher than the fuel reservoir upper portion communicate with each other so that the fuel reservoir upper portion can be removed by vapor; The fuel passage forms a passage in which the liquid fuel flows substantially tangentially to the side of the valve.

(Operation) In the vapor lock prevention structure of the fuel injection device configured as described above, the engine heat is confined in the engine room and the fuel temperature rises because the engine is not cooled immediately after the engine is stopped. Even if bubbles (vapor) are generated in the inside of the fuel, the bubbles are accumulated in the upper part of the fuel pool at the rear end of the valve, and pass through the communication part for vapor escape from the upper part of the fuel pool to the upper part of the fuel pool. As a result of passing through the high-position fuel passage, for example, bubbles generated in the fuel injection device at the time of engine restart are not mixed with the fuel supplied to the engine, and the engine can be restarted smoothly.

(Embodiment) Next, the configuration of the first embodiment of the present invention will be described with reference to FIGS.

A fuel rail 3 shown in FIG. 2, that is, a part of the intake manifold is formed between the cylinder head 1 of the engine and the intake manifold 2, and an injector 4 is provided for each of a plurality of cylinders, in this case, four cylinders. The fuel rail 3 integrally attached to the four cylinders, which are mounted and have fuel passages 5 for supplying fuel to the four injectors 4 for each cylinder, are kept in an airtight state via a gasket 6 and are not shown. It is installed with bolts. The fuel passage 5 has a second
As shown in the figure, injector mounting holes for each cylinder
A passage for flowing the liquid fuel is formed tangentially to 29.

The valve housing 9 attached to the tip of the body 7 of the injector 4 via the stopper 8 has a ball at the tip.
The valve 11 having the 10 attached thereto is attached so as to be movable in the axial direction in a state where the amount of movement is restricted between the end surface of the stopper 8 and the seat surface formed around the injection hole 12 at the tip of the valve housing 9, The valve 11 moves toward the injection hole 12
11 When the ball 10 at the tip end is in contact with the seat surface around the injection hole 12, the injection hole 12 is closed, fuel injection from the injection hole 12 is stopped, and the valve 11 moves toward the stopper 8 to form the valve 11. The injection hole 12 is opened in a state where the formed flange surface 13 is in contact with the end surface of the stopper 8, and from the injection hole 12, the fuel passage 14 from the fuel passage 5 of the fuel rail 3 to the fuel filter 14 at the outer peripheral position of the main body 7 of the injector 4 and the outer periphery of the main body 7. Fuel is injected through the fuel through holes 15 formed at equal intervals, the split groove (not shown) formed in the stopper 8 and the fuel passage 16 formed in the valve 11.

The injection hole 12 and its relation are as shown in detail in the specification and drawings attached to the Japanese Patent Application No. 61-193522 filed on Aug. 19, 1986 by the applicant of the present application.

On the side wall of the main body 7 of the injector 4, a fuel reservoir upper portion of the rear end of the valve 11 and a fuel passage 5 of the fuel rail 3 formed on the side of the valve 11 higher than the fuel reservoir upper portion are provided. The upper portion is communicated via a vapor escape hole 17 so that the vapor can be removed.

A solenoid coil 20 is attached to the main body 7 of the injector 4 via a connector 18 and a fuel leakage prevention O-ring 19, and a cylindrical fixed iron core 21 made of a ferromagnetic material is interposed via a fuel leakage prevention O-ring 22. An armature 23 that is attracted to the fixed iron core 21 by the excitation of the solenoid coil 20 is attached to the rear end portion of the valve 11, and the fuel leakage preventing O-ring 24 is inserted in the cylinder of the fixed iron core 21. Between the screw rod 25 and the armature 22, which are screwed in, the armature 23 is urged in the anti-suction direction to attach the ball 10 of the valve 11 to the injection hole 12 at the tip of the valve housing 9 and the coil spring 26 that presses against the seat surface. Solenoid coil
Reference numeral 19 is connected to an external circuit via a terminal 27, and the injector 4 is inserted into the injector mounting hole 29 for each cylinder formed in the fuel rail 3 through the grommet 28 at the tip of the main body 7 of the injector 4. Cover for 3
The rear end surface of the injector 4 is pressed by the screws 31 of 30 through the grommets 32, so that the fuel rail 3 is attached to each cylinder intake manifold position.

 Next, the operation of this embodiment will be described.

The fuel injection device 33 thus configured, that is, the pulse passage of the solenoid coil 19 by an electric control circuit (not shown) causes the valve 11 to reciprocate together with the armature 23, and the fuel passage of the fuel rail 3 located on the valve 11 side. In the case of a so-called bottom feed type fuel injection device 33 that intermittently injects the liquid fuel from No. 5 from the injection hole 12 at the tip of the valve 11 into the intake manifold, as a vapor lock prevention structure, it is provided on the side wall of the main body 7 of the injector 4 on the side of the valve 11 after the valve 11. Between the fuel reservoir upper portion of the end portion and the fuel passage 5 of the fuel rail 3 formed at a position higher than the fuel reservoir upper portion on the side of the valve 11, a fuel reservoir upper portion of the rear end portion of the valve 11 is provided. A vapor escape hole 17 capable of removing vapor is formed.

Therefore, immediately after the engine is stopped, the engine is no longer cooled, engine heat is trapped in the engine room and the fuel temperature rises, and as a result, even if bubbles (vapor) due to vapor are generated in the fuel injection device 33, Foam valve 11
As a result of accumulating in the fuel reservoir upper portion of the rear end portion and passing through the vapor escape hole 17 from the fuel reservoir upper portion to the fuel passage 5 of the fuel rail 3 at a position higher than the fuel reservoir upper portion, for example, when the engine is restarted The bubbles generated in the injection device 33 are not mixed with the fuel supplied to the engine, and the engine can be restarted smoothly.

Similarly, due to the fuel flow due to the operation of the fuel pump when the engine is restarted, bubbles are particularly likely to be generated from the fuel filter 14 portion of the fuel injection device 33, but the bubbles are also generated in the fuel pool upper portion of the valve 11 rear end portion. The fuel passage 5 of the fuel rail 3 at a position higher than the fuel reservoir upper portion through the vapor escape hole 17 from the fuel reservoir upper portion.
For example, the engine can be smoothly restarted.

By the way, since the fuel flowing through the fuel passage 5 flows substantially tangentially to the side of the valve, the flow of the fuel acts so as to draw out the bubbles in the upper portion of the fuel reservoir through the vapor escape hole 17, so that a high vapor discharging capacity can be obtained. To be

Next, FIG. 4 shows a second embodiment of the present invention. In this case, of the tubular fuel filter 14 attached to the outer peripheral position of the main body 7 of the injector 4 in the first embodiment, the fuel rail 3 By leaving a portion that interferes with the fuel passage 5 as a part of the main body 7 of the injector 4 (the portion has a reference numeral 34), a venturi negative pressure is generated in the peripheral portion of the portion 34 on the fuel passage 5 side, The venturi negative pressure generating portion and the fuel reservoir upper portion of the rear end portion of the valve 11 are communicated with each other by a vapor escape pipe 35 inserted into a vapor escape hole 17 capable of removing vapor, whereby the rear end portion of the valve 11 is connected. In addition to the fact that the bubbles accumulated in the upper part of the fuel pool are positively discharged to the fuel passage 5 of the fuel rail 3 by the Venturi negative pressure,
The configuration, operation, and effect are the same as in the first embodiment.

(Effects of the Invention) According to the present invention, even if the engine heat immediately after the engine is stopped stays in the engine room and the fuel temperature rises, and bubbles (vapor) due to steam are generated in the fuel injection device, the bubbles are removed from the fuel. Even if bubbles are generated in the fuel injection device when the fuel is discharged into the passage and the engine is restarted, for example, the engine can be smoothly started without leaning the air-fuel mixture supplied to the engine.

Further, according to the present invention, the fuel flowing through the fuel passage flows substantially tangentially to the side of the valve, so that the flow of the fuel acts so as to draw out the bubbles in the upper portion of the fuel pool, so that a high vapor discharging capacity can be obtained. .

[Brief description of drawings]

FIG. 1 is a cutaway side view of a first embodiment of the present invention, FIG. 2 is a cutaway plan view mainly showing a fuel passage 5 portion of the fuel rail 3, FIG. 3 is a plan view thereof, and FIG. It is a fracture | rupture side view of 2nd Example of invention. 3 ... Fuel rail, 4 ... Injector 5 ... Fuel passage, 7 ... Main body 11 ... Valve, 12 ... Injection hole 14 ... Filter, 15 ... Fuel through hole 17 ... Vapor escape hole, 20 ...... Solenoid coil 21 …… Fixed iron core, 23 …… Armature 26 …… Coil spring, 33 …… Fuel injection device

Claims (2)

(57) [Claims] 1. A vapor lock prevention structure for a fuel injection device, wherein a liquid fuel supplied from the side of the valve is intermittently injected from a nozzle at the tip of the valve by reciprocating the valve driven by an actuator. A fuel reservoir upper portion of the rear end portion and a fuel passage formed at the side of the valve at a position higher than the fuel reservoir upper portion communicate with each other so that vapor removal of the fuel reservoir upper portion is possible, and the fuel passage includes the liquid fuel. Forms a passage that flows substantially tangentially to the side of the valve. A vapor lock prevention structure for a fuel injection device. 2. A venturi negative pressure generating portion is formed in the fuel passage, and the venturi negative pressure generating portion and a fuel reservoir upper portion are connected by a vapor relief pipe capable of removing vapor. The vapor lock prevention structure for a fuel injection device according to item 1.