JPH02305360A - Fuel injection system in cylinder of two-cycle engine - Google Patents

Abstract

PURPOSE:To reduce channel resistance of a fuel, and to facilitate process of a valve guide part by providing a bypass fuel passage by routing around the valve guide part that guides movement of a valve member along axis, and by introducing the fuel to an injection port through the passage. CONSTITUTION:In a housing 12 that is formed by integrating first and second housing members 4, 6, a guiding member 8, and a sheet member 10 together, a rod-shaped valve member 16 that is constructed in two division, first and second valves 18, 20 is fitted. The first valve 18 is energized in a closing direction by letting a stopper 30 provided on the rear edge, hold an edge of a first spring means 34. In the second valve 20, a core 38 of a solenoid 36 being penetrated, an armature 50 is fixed to the rear edge projected from the core 38, and the valve is maintained as it is opposed to the first valve 18 in closing position by the force of a second spring means 52. A bypass fuel passage 90 is then formed on the guiding member 8 so as to introduce the fuel to a fuel injection port 26 routing around a valve guide part 84.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to an in-cylinder fuel injection device that injects fuel into the cylinder of an engine, particularly for a two-stroke engine that performs forced scavenging by forcing pressurized air. This invention relates to an in-cylinder injection device.

<Prior Art> As a new two-stroke engine that is an improvement on a conventional two-stroke engine, the one shown in FIG. 8, for example, has been proposed.

This includes two intake valves 104 and two exhaust valves 106 in a cylinder head 102 of a cylinder 100, and an ignition device 112 including an ignition coil 108 and an ignition plug 110. Intake Mayu 1Js-rudo 1
14 has a mechanical supercharge +7 using a supercharger etc.
116 is provided, and air is forced into the cylinder 100 based on the rotation of two cocoon-shaped rotors 120 driven by a crankshaft 118. Furthermore, the cylinder head 102 is provided with an in-cylinder fuel injection device 122 that directly injects fuel into the cylinder 100.

Then, as shown in the upper part of FIG. 9, an explosion occurs by the ignition device 112 at the top dead center of the piston 124, and as shown in the lower right, the blowdown occurs in the latter half of the downward movement of the piston 124, which begins to expand. , the exhaust valve 106 opens. Furthermore, the intake valve 104 is opened, and as shown in the lower part, air is forced into the cylinder from the supercharger 116, and this air forcibly scavenges the combustion gas (exhaust gas) in the cylinder through the exhaust manifold 126. Ru. Further, fuel is injected into the cylinder by the in-cylinder fuel injection device 122, and the air-fuel mixture is compressed, resulting in the above-mentioned explosion.

Since such a two-stroke engine can produce twice as many explosions as a four-stroke engine, the inherent advantages of a two-stroke engine can be fully utilized.

<Problems to be Solved by the Invention> By the way, it is desirable that the in-cylinder fuel injection device 122 used in this Jζ 2-cycle engine has a structure that has good atomization characteristics and can quickly diffuse the fuel.

If the penetration force during fuel injection is strong, the oil jet 128
This causes the problem that the oil adhering to the inner peripheral surface of the cylinder gets washed away by the injected fuel.

The injector proposed as an in-cylinder fuel injection device for the above-mentioned two-stroke engine generally includes an outward-opening valve member that opens and closes the fuel injection port of the housing from the outside.
The valve member is pulled into the housing by the spring means and held in the closed position, and the injection port is opened by pushing out the valve member against the biasing horn of the spring means by the electromagnetic driving means such as a solenoid. The person who injects the fuel as part of the process is Shutong. Intake pipe injectors generally have an internal valve, which maintains the open state by pressing the valve member against the valve seat in the housing with a spring means, and maintains the open state by retracting the valve member with an electromagnetic drive means. On the other hand, the in-cylinder injector for the 2-cycle engine mentioned above uses an outer valve method, which moves in the opposite direction, because the valve member whose end face is exposed inside the cylinder opens due to explosion pressure. This is to ensure that you don't give up.

In such a valve structure, the axial opening/closing operation of the valve member is generally carried out within the housing of the injector, and the valve guide portion thereof often also serves as a fuel passage. For example, the guide inner circumferential surface of the housing is formed as a cylindrical surface, while the cylindrical outer circumferential surface of the valve member is partially cut into planes at multiple locations (4
A fuel passage is formed by the gap between the cylindrical inner circumferential surface and the flat surface, and a repulp guide section is formed between the cylindrical inner circumferential surface and the cylindrical surface. Therefore, in order for this part to function as a sufficient fuel passage, a sufficient cross-sectional area (
In addition, in order to fulfill the role of the valve guide part, a certain area of the valve guide part is required to increase the coaxiality between the guide inner peripheral surface of the housing and the valve member. It is not easy to process the valve guide portion in such a way as to maintain high coaxiality while ensuring a sufficient flow path cross-sectional area (gap). - The present invention was made with the object of facilitating the processing of the valve guide portion and reducing the flow path resistance.

<Means for Solving the Problems> The in-cylinder fuel injection device according to the present invention has a two-stroke engine as described above, that is, an intake valve, an exhaust valve, and an ignition device provided in the cylinder head, and In a two-stroke engine that is equipped with a supercharger that sends air into the cylinder, and in which forced scavenging is performed by pressurized air sent from the supercharger when both pulps are in an open state, fuel is injected into the cylinder. OA? It consists of the following:

Of course, there is a housing with a fuel passage formed inside,
A valve member that moves between a closed position and a closed position to open and close the fuel injection port of the housing from the outside of the housing, a valve guide portion that guides the opening and closing movement of the valve member in the axial direction, and a valve guide portion that guides the opening and closing movement of the valve member in the axial direction. a spring means that always biases the valve member in the closed position; an electromagnetic drive means that moves the valve member to the closed position against a spring horn of the spring means; The guide portion includes a bypass fuel passage that communicates the upstream side and the downstream side of the fuel passage.

<Function/Effect> As described above, by providing a bypass fuel passage that bypasses the valve guide section, the fuel is guided to the injection port through this bypass fuel passage, which reduces the fuel flow resistance. can do.

In addition, when processing the valve guide part, it is sufficient to process it to make it coaxial with the valve member, and to provide a sufficient cross-sectional area for the bypass fuel passage.
In terms of machining, the two precision requirements of flow passage cross-sectional area and coaxiality are separated, making machining of the valve guide part easier.

<Example> Hereinafter, one embodiment of the present invention will be described based on the drawings.

Figure 1 shows an example of an in-cylinder fuel injection system (hereinafter referred to as
2 is a cross-sectional view showing the entire injector 2. FIG. This injector 2 is fixed at a position 122 for a 21-no-cycle engine as shown in FIG.

As is clear from FIG. 1, this injector 2 includes a first housing member 4. Second housing member 6° guide member 8
and a sheet member 10, which are mutually integrated to constitute -C1 housings 12 as a whole. The first housing member 4 and the second housing member 6 are O
The second housing member 6, guide member 8, and seam 1 member 10 are crimped together via a ring 14, and are fixed to each other by welding.

Inside such a housing 12 is a rod-shaped valve member 16.
is provided. This valve member 16 is the first valve 1
8 and the second valve member 20, which are coaxially abutted against each other.

The first valve member 18 includes the guide member 8 and the seat portion IJIO.
It is guided by and held movably in the axial direction, and has a valve head 22 at its tip.

The valve head 22 is formed into a truncated cone shape that becomes larger toward the tip, and a shallow conical recess 24 is formed on the end face (valve end face) as shown in FIGS. 2 and 4. The flat surface only remains in an annular shape on the outer periphery of the valve end face. Such a valve end face is exposed to the cylinder combustion chamber of the engine. At the tip of the seat member 10, a fuel injection port 26 with a slightly smaller taper ratio than the valve head 22 is formed in a J shape that widens outward, and the valve head 22 is seated in this opening (valve seat). A liquid-tight seal portion 28 is formed.

As shown in FIGS. 1 and 2, the rear end (inner end) of the first valve member 18 protruding rearward from the guide member 8 has station names 1 to 30, and this stopper 30 between the spring reinner 32 and the guide member 8 held in the
Six first springs 34 are arranged with a predetermined compressive preload. This spring 34 functions as a first spring means and is capable of pulling the first valve member 18 against the valve head 22.
constantly biases the injection port 26 to the closed position.

The movement stroke S (Fig. 2) of the first valve member 18 is given by the gap between the stopper 30 and the guide member 8, and during fuel injection, the first valve member 18 moves forward. Then, the valve head 22 lifts up from the seat part of the injection port 26, and this becomes the closed position.

Returning to FIG. 1, the aforementioned second valve material 20 extends toward the rear of the housing 12 and projects into the solenoid 36 that forms the main body of the electromagnetic drive means. The trenoid 36 includes a flanged cylindrical core 38, and the core 38 is sandwiched and fixed between the first housing member 4 and the second housing member 6 by the aforementioned caulking via the spacer 40 at the flange portion. There is. A coil bobbin (hereinafter simply referred to as bobbin) 42 is fitted onto the outside of the core 38, and a coil 44 is wound around this bobbin 42. Further, terminals 48 and 48 are attached to the bobbin 42 via adapters 46 and 46, and excitation current is supplied to the coil 44 from the outside via these terminals 48 and 48.

The second valve member 20 passes through the core 38 so as to be movable in the axial direction, and an armature 50 is fixed to the rear end portion protruding from the core 38 . This armature 50 and core 3
8 is adjusted by the spacer 40, and as the armature 50 is attracted to the core 38 by energizing the valve 44, the second valve member 20 resists the biasing force of the first spring 34. The first valve member 18 is moved forward to the open position.

This second valve member 20 is always urged toward the first valve member 18 by a second spring 52 serving as a second spring means. This second spring 52 is installed with a compressive preload between the armature 50 and the spring stopper pipe 54, and thus exerts a force on the first valve member 18 in the opposite direction to that of the first spring 34. . However, the spring force of the second spring 52 is much weaker than the spring force of the first spring 34, and the second valve member 20 is always butted against the first valve member 18 in the closed position, resulting in a U-state. Plays the role of keeping it safe.

It is something. The spring force that biases this binding and first valve member 18 to the closed position is equal to the spring force of the first spring 34 minus that of the second spring 52, and conceptually the load of such a difference is It can be considered that the spring means having the first valve member 18 is pulling the first valve member 18 in the closing direction. The spring load of the second spring 52 can be adjusted by adjusting the insertion amount of the spring stopper pipe 54 into the first housing member 4, and then the position of the pipe 54 is fixed by caulking the first housing member 4 from the outside. Ru.

The amount of rearward movement of the second valve member 20 is regulated by a stopper (hereinafter referred to as a backstopper) 56. This back stopper 56 is fixed to the first housing member 4 facing the armadure 50, but the gap therebetween is not smaller than the valve stroke S of the first valve member 18. In other words, the back stopper 56 does not prevent the closing operation of the first valve member 18, but functions to prevent the second valve member 20 from moving away from the first valve member 18 and retreating excessively.

A fuel passage 60 is formed in the housing 12 to guide fuel from a fuel supply boat 58 formed at the rear end to the fuel injection port 26 at the front end, and this will be described in more detail.

A strainer 62 is provided inside the supply port 58 to capture dust and the like in the fuel, and the fuel that has passed through the strainer reaches the vicinity of the armature 5° through a second passage portion 64. From here, the fuel passage bypasses the armature 50 and passes between the 1-a 38 and the bobbin 42. That is, as shown in FIGS. 5 and 6, four grooves 66 are formed in the axial direction on the inner peripheral surface forming the first passage 64 of the first housing member 4. The ring 68, which is shorter than the groove 66, is press-fitted so that the fuel r1 passes through these four grooves 66. Further, although the bobbin 42 is tightly fitted to the core 38, four grooves 70 are formed in the inner circumferential surface of the bobbin 42 in parallel with the core 38, as shown in FIG. It communicates with the four grooves 66. In other words, these four grooves 70 serve as fuel passages formed between the core 38 and the bobbin 42, and the fuel flows very close to the inner circumference of the coil 44.

The four grooves 70 of the bobbin 42 are connected to the four communication holes 72 formed in the flange portion of the core 38 and the spacer 4.
It communicates with a second passage 76 corresponding to the central space of the second housing member 6 through a central hole 74 of 0 . As is clear from FIG.
8 through a single radial communication hole 80 formed in the radial direction.

Here, the first valve member 18 described above is a guide member 18.
A rear valve guide portion 82 formed at the rear end portion and a front valve guide portion 8 formed at the rear end portion of the seat member 10.
The movement in the axial direction is guided at two locations, 2 and 2, but the front valve guide section 84 provides higher guidance accuracy and plays the main role in the guide function. Then, the first combustion passage passes by bypassing this front valve guide portion 84.゛That is, the sheet member 10 is fluid-tightly fitted into the opening on the distal end side of the guide member 8, but the inner peripheral surface of the guide member 8 has four wires as shown in FIGS. 2 and 3. grooves 86 are formed in the axial direction beyond the inner end of the sheet member 10, and these grooves 86 are further connected to the center hole 89 of the sheet member 10 by four radial communicating holes 88 on the tip (outer end) side. familiar with
This portion of the first valve member 18 is a small diameter portion 92. As a result, a bypass fuel passage (hereinafter simply referred to as a bypass passage) 90 is formed from the third passage 78 on the upstream side to the injection port 26 side, bypassing the front valve portion id portion 84. In addition, a gauge part 94 provided with a highly polished gap is formed immediately in front of the injection port 26, and the amount of sprayed OA per injection is determined by the cross-sectional area of the flow path here.

The injector as described above is used by being fixed to the cylinder head as shown in FIG. 8 at the threaded portion 96 of the second housing member 6 whose dimensions are shown in FIG.

When the armature 50 is attracted to the core 38 by energizing the solenoid 36 by energizing the coil 4/I, the second valve member 20 moves forward and the first spring 3/I
The first valve member 18 is moved to the closed position against the urging force of the fuel injection port 26, thereby injecting fuel into the cylinder from the injection port 26. When the solenoid 36 is demagnetized, the first valve member 18 is returned to the closed position by the spring force of the first spring 34, and the second valve member 20 is pushed back with this return operation. Here, the first and second valve materials 18 and 2
Due to the two-part structure of 0, the first valve part jtA18 which closes the injection port 26 with respect to the entire movable part ω
The inertial mass of the first valve member 18 is sufficiently small, so the bouncing when this first valve member 18 is seated on the seats 1 to 1o is small, and the fuel cut-off accuracy is improved and dripping is suppressed. Even after the first valve member 18 stops at the closed position, the second valve member 20 tries to move back while compressing the second spring 52 due to inertia, but the back stopper 56 prevents it from moving back too much. Even if it separates from the first valve member 18, it returns to the first abutting state.In other words, when the second valve part IJ20 retreats greatly, it is pushed back by the repulsive force of the second spring 52, and the first valve member 1
Although there is a possibility that the injection port 26 will collide strongly with the injection port 8 and the injection port 26 will temporarily open, this is avoided.

In addition, the valve end face of the first valve member 18 faces the combustion chamber in the cylinder, and since the four parts 24 are formed, even if fuel drips from the injection port 26, it does not turn into large droplets and becomes soot. The occurrence of is suppressed.

The fuel flows through the aforementioned fuel passage 60, but the solenoid 3
In the section 6, a portion 70 is passed between the core 38 and the bobbin 42. Since this fuel cools the coil 44, a decrease in electromagnetic attractive force caused by an increase in electrical resistance due to heat generation is suppressed.

Further, in the valve guide portion 84 of the first valve member 18, the fuel detours through the bypass passage 90 having a sufficiently large flow passage cross-sectional area, and the flow resistance is lower than that in the case where the guide portion 84 is also used as a fuel passage. ,.

Further, since the valve guide section 84 and the measuring section 94 are separated, the first valve member 18 in the valve guide section 84
The machining is performed with the main focus on coaxiality with the flow path, and the machining is performed with the main focus on the cross-sectional area of the flow path in the wetting section 94, so the machining is faster than when the requirements of both parties are not met and the machining is forced. becomes easier.

Note that the above description is literally an illustration, and the present invention is not limited to the description of this embodiment, and it goes without saying that the present invention can be implemented in various modified forms based on the common knowledge of those skilled in the art.

[Brief explanation of the drawing]

FIG. 1 is an overall sectional view of an in-cylinder fuel injection device that is an embodiment of the present invention, FIG. 2 is a partial sectional view of its tip side, and FIG. 3 is a Δ-A sectional view taken from FIG. 2. Fig. 4 is an enlarged sectional view of the tip portion in Fig. 2, Fig. 5 is a partial sectional view of the central portion in Fig. 1, Fig. 6 is a sectional view taken along line B-8 in Fig.
The figure is also a CC sectional view, FIG. 8 is a u' sectional view showing an example of an engine in which the injection device of FIG.
The figure is an explanatory diagram of the operation of the engine. 12: Housing 16: Valve member 18: First/valve member 20: Second valve member 24: Recess 26: Fuel injection port 34: First spring 36: Solenoid 38: Core 42: Coil bobbin 4/1: Coil 50: Armature 52: Second spring 56 Second back 1 to collar 60: Fuel passage 66, 70', 86: Groove 72.80.88: Communication hole 94: Measuring section

Claims (1)

[Scope of Claims] The cylinder head is provided with an intake valve, an exhaust valve, an ignition device, and a supercharger that feeds air into the cylinder through the intake valve. It is an in-cylinder fuel injection device that injects fuel into the cylinder and is used in two-stroke engines that perform forced scavenging using pressurized air sent from an aircraft.It is an in-cylinder fuel injection device that injects fuel into the cylinder. A valve member that is moved between an open position and a closed position to open and close a fuel injection port from the outside of the housing, a valve guide portion that guides the opening and closing movement of the valve member in the axial direction, and a valve member that is always kept in the closed position. spring means for biasing; electromagnetic drive means for moving the valve member from the closed position to the open position against the biasing force of the spring means; An in-cylinder fuel injection device for a two-stroke engine, comprising a bypass fuel passage that communicates an upstream side and a downstream side of the fuel passage with respect to the fuel passage.