JPH02305362A - Fuel injection system in cylinder of two-cycle engine - Google Patents

Abstract

PURPOSE:To improve cooling efficiency of a coil by forming an electromagnetic driving means by which a valve member is driven in an opening direction, so as for a fuel passing in a housing to pass slightly touching a coil inner circumferential surface until it reaches an injection port of lower flow. 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, 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. The solenoid 36 is formed in such a way that it is introduced from a fuel supply port 58, and the fuel passing through a straightener 62 passes a fuel passage between the core 38 and a bobbin 42, and that a coil 44 is cooled.

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, and particularly to a two-cycle fuel injection device that performs forced scavenging by forcing pressurized air. This invention relates to an in-cylinder fuel injection device for an engine.

<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 manifold 114
The mechanical supercharger 116 is used as a supercharger.
is provided, and air is forced into the cylinder 100 based on the rotation of two cocoon-shaped rotors 120 driven by the crankshaft 118. Further, the cylinder head 102 is provided with an in-cylinder fuel injection device 122 that injects fuel directly into the cylinder 100.

Then, as shown in the upper part of Fig. 9, an explosion occurs due to the ignition device @112 at the top dead center of the piston 124, and as shown in the lower right, blowdown occurs in the latter half of the descent of the piston 124 due to expansion, and the exhaust valve 106 opens. Furthermore, the intake valve 104 also opens, and as shown in the lower part, air is forced into the cylinder from the supercharger 116, and this air forces the combustion gas (exhaust gas) in the cylinder to be scavenged through the Exis 1 manifold 126. be done. 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-cycle engine can be fully utilized.

<Problems to be Solved by the Invention> Incidentally, the in-cylinder fuel injection device 122 used in such a two-stroke engine preferably has a structure that has good atomization characteristics and can quickly diffuse the fuel. If the penetration force during fuel injection is strong, oil jet l-128
This has the disadvantage that the oil deposited on the inner peripheral surface of the cylinder is 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 a spring means and held in the closed position, and the valve member is pushed out against the biasing force of the spring means by an electromagnetic drive means such as a solenoid, thereby opening the injection port and injecting fuel. It is common to use injection. Intake pipe injectors generally have an internal valve, which maintains the closed state by pressing the valve member against the valve seat in the housing with a spring means, and opens the valve member by pulling it in with an electromagnetic drive means. On the other hand, the in-cylinder injector for two-cycle engines mentioned above adopts an outer valve system in which the movement is reversed, because the valve member whose end face is exposed inside the cylinder is opened by the explosion pressure. This is to ensure that you don't give up.

In such an outward-opening valve structure, when opening is performed by advancing the valve member using an electromagnetic drive means, the electromagnetic drive means generally includes a solenoid constituted by a core and a coil surrounding the core. Usually, a valve member is inserted inside the valve member, and an armature fixed to the rear end of the valve member is electromagnetically attracted to a solenoid.

Although the above-mentioned coil is wound around the core via a coil bobbin, it is inevitable that the coil generates heat due to the supply of excitation current, and the electromagnetic attraction force decreases due to the heat generation.

Here, it would be advantageous if the coil could be cooled by the fuel flowing inside the housing, but the fuel passage of the above-mentioned injector is generally formed in the axial direction between the valve member and the core, and the fuel flows between the valve member and the core. Either the fuel is guided to the injection port through the core, or it is supplied into the housing from an intermediate portion between the injection port and the solenoid and guided to the injection port, and cooling of the coil by fuel can hardly be expected.

The present invention has been made with the object of effectively cooling a coil.

<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 There is a two-cycle engine that injects fuel into the cylinder, which is equipped with a supercharger that pumps air into the cylinder, and where forced exhaust is performed by pressurized air sent from the supercharger when both valves are open. , is constructed as follows.

That is, a housing in which a fuel passage is formed;
A valve member that is moved between an open position and a closed position to open and close the fuel injection port of the housing from the outside of the housing, a spring means that always biases the valve member to the closed position, and a biasing force of the spring means. and an electromagnetic drive means for moving the valve member from a closed position to an open position against a force, the electromagnetic drive means comprising: a fixed core through which the valve member movably passes; combined coil bobbin,
The fuel passage includes a coil wound around the coil bobbin and an armature integrally provided at an end of the valve member that passes through the core, and is located between the coil bobbin and the core and guides fuel to the injection port. It is characterized by the formation of

Effects and Effects> With the above configuration, the fuel flowing in the housing passes through the inner circumferential surface of the coil in the electromagnetic driving means portion, and reaches the downstream injection port. Therefore, the coil of the electromagnetic driving means is effectively cooled by this flow of fuel, and a decrease in electromagnetic attraction force due to overheating of the coil is effectively suppressed.

<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 two-stroke 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 one housing 12 as a whole.

The first housing member 4 and the second housing member 6 are caulked together via an O-ring 14, and the second housing member 6, guide member 8, and seat member 10 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 is guided by the guide member 8 and the seat member 10, is held movably in the axial direction, and is provided with 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 tips of the seats 1 to 10, a fuel nozzle 26 with a slightly smaller taper ratio than the valve head 22 is formed to widen outward, and the valve is inserted into this opening (valve seat). head 22
is seated to form a liquid-tight seal portion 28.

As shown in FIGS. 1 and 2, a stopper 30 is attached to the rear end (inner end) of the first valve member 18 that protrudes rearward from the guide member 8, and a spring held by the stopper 30 A first spring 34 is disposed between the retainer 32 and the guide member 8 with a predetermined compressive preload. This spring 34 functions as a first spring means, and always urges the first valve member 18 to the closed position where the valve head 22 closes the injection port 26.

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 by this stroke, and the valve head 22 moves forward. It lifts up from the seat part of the injection port 26, and this becomes the open position.

Returning to FIG. 1, the aforementioned second valve member 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 solenoid 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. ing. 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 the armature 5o 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 when the armature 50 is attracted to the core 38 by energizing the coil 44, the second valve member 20 moves forward against the biasing force of the first spring 34. and moves the first valve member 18 to the closed 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. The second spring 52 is installed with a compressive preload between the armature 50 and the spring stopper pipe 54, and therefore exerts a biasing 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 has the role of always keeping the second valve member 20 abutted against the first valve member 18 in the closed position. It is something that we fulfill. As a result, the spring force biasing the first valve member 18 to the closed position is
This is the spring force of the first spring 34 minus that of the second spring 52, and conceptually it can be considered that the spring means having such a difference in load pulls the first valve member 18 in the closing direction. I can do it. Note that the spring load of the second spring 52 is applied to the spring stopper pipe 54.
The position of the pipe 54 is fixed by caulking the first housing member 4 from the outside.

The amount of rearward movement of the second valve member 20 is regulated by a stopper (hereinafter referred to as a backstopper) 56. Although the back stopper 56 is fixed to the first housing member 4 facing the armature 50, 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 boat 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 50 through the second passage section 64. From here, the fuel passage bypasses armature 50 and passes between core 38 and 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. A ring 68 shorter than the groove 66 is press-fitted so that fuel can pass 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 four 66's. In other words, these four grooves 70 are connected to the core 38 and bobbin 42.
A fuel passage is formed between the coil 44 and the fuel, 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.
They communicate through four radial communication holes 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 axial movement is guided at two locations, 4 and 4, but the front valve guide section 84 provides higher guidance accuracy and is the main guide function. A fuel passage bypasses this front valve guide portion 84. In other words,
The sheet member 10 is liquid-tightly fitted into the opening on the distal end side of the guide member 8, and the inner peripheral surface of the guide member 8 has four grooves 86 as shown in FIGS. 2 and 3. are formed in the axial direction beyond the inner end of the seat member 10, and these grooves 86 are connected to the central hole 89 of the seat member 10 by four radial communication holes 88 on the tip (outer end) side. 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 guide portion 84. A metering section 94 provided with a highly accurate gap is formed immediately in front of the injection port 26, and the amount of injection 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 at the threaded portion 96 of the second housing member 6 shown in FIG. 1 as shown in FIG. 8.

When the armature 50 is attracted to the core 38 by energizing the solenoid 36 by energizing the coil 44,
The second valve part IJ20 moves forward and pushes the first valve member 18 to the open position against the biasing force of the first spring 34, whereby fuel is injected 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 members 18 and 20
Because of the two-part structure, the inertial mass of the first valve member 18 that closes the injection port 26 is sufficiently small compared to the mass of the movable parts as a whole, so that the first valve member 18 is the seat part'! There is very little bouncing when sitting on the A10, which improves the accuracy of fuel cutoff and suppresses dripping. Furthermore, even after the first valve member 18 has stopped at the closed position,
The second valve member 20 tries to retreat while compressing the second spring 52 due to inertia, but the back stopper 56 prevents the second valve member 20 from retreating excessively, and once the first valve member 18
Even if you move away from it, it will immediately return to the butting state. In other words, if the second valve member 20 moves back significantly, it will be pushed back by the repulsive force of the second spring 52 and collide strongly with the first valve member 18, which may cause the injection port 26 to open temporarily, but this is avoided. .

Further, since the valve end face of the first valve member 18 faces the combustion chamber in the cylinder and has a recess 24 formed therein, even if fuel drips from the injection port 26, it does not turn into large droplets. , soot generation is suppressed.

Although the fuel flows through the aforementioned fuel passage 60, the solenoid 3
In the portion 6, a portion 70 of the fluid flows 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 portion 84 and the cut portion 94 are separated, the first valve member 18 in the valve guide portion 84 is
Processing is performed with the main focus on coaxiality with the flow path, and processing is performed with the main focus on the cross-sectional area of the flow path in the measuring section 94, so the processing is easier than when forced to perform processing that satisfies the requirements of both sides. Become.

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, FIG. 3 is a sectional view taken along line A-A in FIG. 2, and FIG. The figure is an enlarged cross-sectional view of the tip part in Figure 2, Figure 5 is a partial cross-sectional view of the central part in Figure 1, Figure 6 is a BB-B cross-sectional view in Figure 5, and Figure 7 is a partial cross-sectional view of the central part in Figure 1.
8 is a sectional view showing an example of an engine in which the injection device shown in FIG. 1 is suitably used, and FIG. 9 is an explanatory view 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 44: coil 50: armature 52: first Spring 56: Back stopper 60: Fuel passage 66, 70, 86: Groove 72, 80, 88: 1 Through 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 spring means that constantly biases the valve member to a closed position, and a spring means that resists the biasing force of the spring means. an electromagnetic drive means for moving the valve member from a closed position to an open position, the electromagnetic drive means comprising: a fixed core through which the valve member movably passes; and a core fitted to the outside of the core; The valve member includes a coil bobbin, a coil wound around the coil bobbin, and an armature that is integrally provided at an end of the valve member passing through the core, and between the bobbin and the core, fuel is supplied to the injection port. An in-cylinder fuel injection device for a two-stroke engine, characterized in that the fuel passage for guiding the fuel is formed therein.