JPH0331571A - Fuel injector in cylinder - Google Patents

Abstract

PURPOSE:To prevent the rise of fuel temperature by forming the surface layer at least at a cylinder side edge part of a valve member which is opening- operated against a spring means by the excitation of an electromagnetic driving means. CONSTITUTION:An injector 2 has a half divided structure consisting of the first valve member 18 and the second valve member 20 in a housing 12, and each rod-shaped valve member 16 which is coaxially butt-joined each other is fitted. The first valve member 18 is guided by a guide member 8 and a seat member 10, and has a valve head 22 having a truncated cone shape at the top edge, and urged in the closing direction by a spring 32 installed between a stopper 30 installed at the rear edge part and the guide member 8. In such an injector 2, the part exposed into the combustion chamber of the first valve member 18 and the top edge part of the housing 12 are covered by the ceramics layers 97 and 98 having each prescribed thickness.

Description

Detailed Description of the Invention Industrial Field of Application The present invention relates to an internal fuel injection tJ4 device that injects fuel directly into the cylinder of an engine. Daily fuel injection S suitable for cycle engines! 1ii1.

<Conventional technology> Fuel is injected into the engine's intake pipe rJ4'! In contrast to the intake pipe self-injection 04 device, the in-cylinder injection device injects fuel directly into the engine cylinder Q4'! It is used, for example, in a two-stroke engine as shown in FIG.

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
A mechanical supercharger V-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, the piston 124
Ignition device W at top dead center! 1112 causes trouble, and as shown in the lower right, the piston 124 moves to 70-down in the latter half of the first stroke due to expansion, and the exhaust valve 106 becomes FJ<. In addition, the intake valve 104 also listens, and as shown in the lower part, air is forced into the cylinder from the supercharger 116, and this air causes the combustion gas (l) in the cylinder to increase.
Jt gas) is strongly t■-blown through the exhaust eyebrow 41-126. Further, fuel is injected into the cylinder by the in-cylinder fuel injection device 122, and the air-fuel mixture is compressed by f1, resulting in the above-mentioned N engine.

<Problems to be Solved by the Invention> By the way, the injector considered as such an internal fuel injection &i&
(Hold the external valve member that opens and closes the mouth from the outside, and pull the valve member into the housing using the spring means!) While holding the valve member in place, use the electromagnetic driving means such as a solenoid to pull the valve member into the housing. Normally, the injection port is opened and fuel is injected by pushing the injection port against the urging force of the intake pipe. While the valve member is pressed against the valve seat in the housing to maintain the port 1 state, the valve member is pulled in using an electromagnetic drive means to enter the 11 state. The reason for adopting the external valve system in which the movement is opposite to this is to prevent the valve portion 441fi whose end face is exposed inside the cylinder from becoming erratic due to the explosion pressure.

In this kind of local injection injector, the fuel injection port faces the cylinder combustion chamber, so it directly receives the heat of the combustion chamber, especially the tip part of the valve member exposed to the cylinder (combustion chamber) side. Exposure to considerable lagoon. and,
Since the valve portion 44W is generally made of metal, it has high thermal conductivity, and the fuel at the tip of the injector tends to rise to r-degrees due to heat from the combustion chamber. When the fuel 1N temperature rises, vapor (bubbles) is generated, resulting in unstable flow characteristics.

An object of the present invention is to provide an in-cylinder fuel injection device that can suppress the upper limit of fuel temperature at the tip of an injector, etc.

<Means for Solving 8 Problems 1> The in-cylinder fuel injection Vtri according to the present invention can be used, for example, in a two-stroke engine as described above, that is, in a cylinder head with gQ
It is equipped with a closed intake valve, a U air valve, and an ignition %=M, and a supercharger that sends air into the cylinder through the intake valve, and pressurization that is sent from the supercharger when both of these valves are in the m1 state. There is one that is suitably used in a two-stroke engine that performs strong Ufil air with air, and directly injects fuel into the cylinder, and is configured as follows.

That is, a housing in which a fuel passage is formed;
a valve member for moving the fuel injection port of the housing between closed positions and closed positions as infrequently from the outside of the housing; a spring means for always biasing the valve member in the closed position; The valve member includes an electromagnetic drive means for moving the valve member to the open position against force, and is characterized in that at least the surface layer of the cylinder side end (tip end) of the valve member is formed of ceramics.

Here, for example, the tip of the valve member (mainly the cylinder cylinder
A ceramic surface layer of a predetermined thickness can be formed by thermal spraying ceramics on the part exposed to the A chamber, or the valve member itself can be made of ceramics.

Furthermore, as in the invention described in claim 2, it is also possible to form a ceramic layer not only on the valve member but also on the housing surface layer at the injector tip (mainly the part exposed to the cylinder combustion chamber) by thermal spraying or the like. Furthermore, it is also possible to make the housing part itself corresponding to the injector tip part made of ceramics.

Function> As mentioned above, the tip of the valve member JW? By forming a ceramic layer on the JI or composing the entire JI with ceramics, the heat in the cylinder combustion chamber is transferred to the fuel in the injector through the valve member, since ceramics have a lower thermal conductivity than metals, for example, about half. As a result, the increase in fuel FIW is suppressed.

Further, if ceramic is used not only for the valve portion H but also for the housing as in the second aspect of the invention, the effect of suppressing the rise in fuel temperature will be even greater.

<Example> Hereinafter, one embodiment of the present invention will be explained with reference to the drawings.

Figure 1 shows an example of the n internal combustion separate injection neck (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 portion 44
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
The second housing member 6, the guide portion 448 and the seam 1' are caulked via the O ring 14.
, are welded together.

Inside such a housing 12 is a forest-shaped valve member 16.
is provided. This valve member 16 is the first valve 1
The valve member 8 and the second valve member 20 are made of a two-part M4 structure, and 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 has a valve head 22 at its tip.

The valve head 22 is formed in the shape of a truncated cone 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 to expand outward, and the valve head 22 is seated on this curved opening (valve seat). A liquid-tight seal portion 28 is thus formed.

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 portion 448, and the stopper 30 is held by the stopper 30. Spring retainer 32 and guide PIS 448
- A first spring 34 is arranged with a predetermined compression preload v4. This spring 34 functions as a first stage of spring, and the first valve member 18 is injected by the valve head 22.
Always energized in 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 rJu 18 moves forward by this stroke and the valve head 22 injects the fuel. It rises from the seat part of the mouth 26, and this becomes the open position.

Returning to FIG. 1, the aforementioned second valve portion vU20 extends toward the rear of the housing 12 and projects into the solenoid 36 that forms the main body of the Ti11 drive means. The solenoid 36 includes a flanged cylindrical core 38, and the core 38 has a cylindrical core 38.
The above-mentioned caulking η is sandwiched between the first housing member 4 and the second housing N1446 via the first housing member 40 at the portion of the lunge NS, and is fixed. A coil pobbin (hereinafter simply referred to as pobbin) 42 is fitted on the outside of the core 38, and a coil 44 is wound around this pobbin 42.

In addition, the pobbin 42 is connected to the
Terminals 48, 48 are attached, and an excitation vA current is supplied to the coil 44 from the outside via these terminals 48.48.

The second valve member 20 passes through the core 38 so as to be movable in the axial direction, and has an armature at the rear end protruding from the core 38.
A 50 is fixed. Eyagi 1 with this armature 50 and core 38? The knobs are aligned with the spacer 40, and when the coil 44 is energized, the armature 50 is aligned with the core 38. By being attracted by the second valve member 20, the second valve member 20 moves forward against the biasing force of the first spring 34, and pushes the first valve member 18 toward the same position F.

This second valve portion 1420 is always urged toward the first valve n1 material 18 by a second spring 52 as a second spring means. This second spring 52 is placed between the armature 50 and the spring-fitting pipe 54 with a compression preload i1, and therefore exerts an urging 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 horn of the first spring 34, and In4i! The second valve part 4420 always keeps the second valve part 4420 abutted against the first valve part 4418 located at the same position. As a result, the spring force biasing the first valve member 18 to the open position is the spring force of the first spring 34 minus that of the second spring 52, and conceptually, such external charge It can be considered that the spring means having . Note that the spring load I of the second spring 52
n can be adjusted by inserting the spring stopper pipe 54 into the first housing member 4, and then the first housing N1
The position of the pipe 54 is fixed by caulking the material 4 from the outside.

The rearward movement a of the second valve member 20 is stopped 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 distance between the two is not smaller than the valve stroke S of the first valve portion 4418. In other words, this back stopper 56 does not prevent the 1311 first production of the first valve member 18;
Second valve? It functions to prevent the JS4420 from moving away from the first valve member 18 and tui excessively.

A fuel passage 60 is formed within the housing 12 for guiding fuel from a feed port 58 formed at the rear end to a fuel injection port 26 at the front end, which will be described in more detail.

A strainer 62 is arranged inside the supply boat 58 to capture dust and the like in the fuel, and the fuel that has passed through this reaches the vicinity of the armadure 50 through a first VB section 64 . From here, the fuel passage bypasses the armadure 50 and passes between the core 38 and the bobbin 42. In other words, the 5th V! i and 6th
As shown, the first passage 64 of the first housing member 4
Four grooves 66 are formed in the axial direction on the inner peripheral surface forming the groove, and a ring 68 shorter than the groove 66 is press-fitted into this inner peripheral surface, so that fuel can pass through these four grooves 66. It has become. Furthermore, although the bobbin 42 is tightly fitted to the core 38, four holes 70 are formed on the inner peripheral surface of the bobbin 42 in parallel with the core 3B, as shown in FIG. It communicates with Man 66 of 4 trees. In other words, these four holes 70 form a fuel passage formed between the core 38 and the bobbin 42, and the fuel flows very close to the inside of the coil 44.

The four holes 70 of the bobbin 42 correspond to the central space of the second housing member 6 through the four communicating holes 72 formed in the pulling portion of the core 38 and the central hole 74 of the subway 40. As is clear from FIG. They communicate through a radial communication hole 80 with a diameter of 41 pJ.

Here, the first valve portion 4418 described above is connected to the guide rjA.
a rear valve guide portion 82 formed at the rear end of the material 8;
The movement in the axial direction is guided at two points, the front valve guide rA 84 formed at the rear end of the seat member 10, and the front valve guide P, 1s84 provides higher guidance accuracy, and this is the main guide function. is doing. A fuel passage bypasses this front valve guide portion 84. In other words, although the seat portion vi10 is liquid-tightly fitted into the front end portion of the guide member 8, the guide portion 44
On the inner peripheral surface of No. 8, the second f! i! ! As shown in FIG. 3, four grooves 86 are formed in the axial direction beyond the inner end of the sheet member 10, and these grooves 86 have a radial communication hole 88 of 41J on the tip (outer end) side. This communicates with the central hole 89 of the sheet member 10, and this portion of the first bulp FIS material 18 is defined as a small diameter portion 92. As a result, a bypass fuel passage (hereinafter referred to as l
A bypass passage (referred to as a bypass passage) 90 is formed in the tl. In addition, a total ω portion 94 provided with a gap of r&accuracy is formed immediately in front of the injection port 26, and the injection m per constant 1 is defined by the flow V8 cross-sectional phase here.

As shown in FIG. 1, the distal end of the housing 12 is composed of the guide section I8 and the seat I member 10 as described above, and the surfaces of the guide member 8 and the sheet member 10 are shown in FIG. As shown in FIG.
Also, the first valve [418 cylinder fuel 1'
i! The inside of the end and the outer peripheral surface of the tip exposed to the surface are also made of ceramic F! with a predetermined gap as shown in Fig. It is covered by A97. These ceramics H97 and H98 are formed by, for example, silicon nitride-based ceramics being subjected to wj-irradiation using a known method. In addition, in the sealing portion 28 of the first valve member 18, the full bends are in contact with each other, and the peripheral edge of the ceramic layer 98 corresponding to the opening edge of the injection port 26 is formed at an angle larger than the Taber angle of the injection port 26. A counterbore is formed so as to open, and the laminated layer 98 allows fuel injection (
g) It is made not to give the characteristics a benefit.

The injector as described above is used by being fixed to the cylinder head as shown in FIG. 8 using the screw 12I96 of the second housing member 6 shown in FIG.

When the armature 50 is attracted to the core 38 by energizing the solenoid 36 by energizing the coil 44,
The second valve portion 1120 advances by +Vi, and the first spring 3
The first valve member 18 is moved in the 51st position against the urging force of No. 4, whereby fuel is injected into the cylinder from the injection no. 4 [126]. When the solenoid 36 is demagnetized, the first valve member 18 returns to the closed position due to the spring force of the first spring 34, and with this return operation, the second valve member 2
0 is pushed back. Here, the first and second valve members 1
Due to the two-part structure of parts 8 and 20, the resistant structure of the first valve member 18 that defines the opening 26 is sufficiently small for the purchase of the entire flexible part. The bouncing when the first valve part @ 18 is seated on the seat member 10 is very small, and the viscosity of the fuel is improved, so that rear vibration is suppressed.
Even after the second valve member 20 has stopped at the n 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 the second valve member 20 from moving back excessively. Even if it is separated from the valve ffi+418, it immediately returns to the butted state. In other words, when the second valve member 20 retreats significantly, it is pushed back by the repulsive force of the second spring 52 and strongly collides with the first valve part 4418, causing the injection port 2
6 may open temporarily, but it will be turned on.

Further, the valve end face of the first valve part v118 faces the combustion chamber in the cylinder, but since the recess 24 is formed, even if the FFI material drips from the injection port 26, it will not become large droplets. Generation of soot is suppressed.

Furthermore, the cylinder of the first valve part 4418! ! The part exposed to the baking chamber is the ceramic layer 97, and the housing 12
Since the surface layer of the tip part (guide member 8, sheet member 10) is covered with ceramic F498, it is difficult to burntJl! temperature is difficult to conduct to the fuel at the tip of the injector, and its yAt! IIJ? is suppressed.

By the way, the thermal conductivity of stainless steel (5O843G) is about 22 cal/-・h・℃, while the thermal conductivity of ceramics (nitrate, silicon oxide) is half that, about 11K.
cal/+eh ・”C.

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

In addition, in the valve guide portion 84 of the first valve member 18, the fuel bypasses the bypass passage 90 with a sufficiently large flow area, and the road resistance is greater than that in the case where the fuel flows through the guide portion 84 into the fuel passage. small.

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 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 actual algae example, but can be applied to various modifications based on the common sense of those skilled in the art, such as application to diesel engine injectors. Of course, it can be implemented in a manner in which the following is applied.

<Effects of the Invention> According to the present invention, by using ceramics for the valve member, the heat of the cylinder combustion chamber is difficult to be transmitted to the injector tip, and the temperature of the fuel t1 there is
As a result, the generation of vapor is suppressed, which leads to stabilization of the flow characteristics.

In addition, as in the invention of claim 2, by using ceramics for the housing tip, etc., heat conduction from both the inside and the outside is suppressed, so to speak, and the upper t11 of the fuel temperature Iff and the generation of vapor are more effectively suppressed. It is suppressed to v1.

[Brief explanation of drawings]

FIG. 1 is an overall cross-sectional view of an in-cylinder fuel chanting device that is an embodiment of the present invention, FIG. 2 is a partial cross-sectional view of its tip side, FIG. 3 is an A-Ali plane view 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 cross-sectional view taken along line 8-B in Figure 5, and Figure 7 is also a C-Cl1 FIG. 8 is a sectional view showing an example of an engine in which the injection device of FIG. 1 is used in IB mode;
FIG. 9 is an explanatory diagram of the operation of the engine. 12... Housing 16... Valve member 18... First valve rA material 20... Second valve member 24... Four parts 2G... Fuel injection port 34... First spring 36... ... Solenoid 38 ... Fa 42 ... Coil bobbin 44 ... Coil 50 ... Armature 52 ... Second spring 5G ... Back stopper 60 ... Fuel passage 66, 70.86 ...Full 72.80.88...Communication hole 94...Total
Amount Part 97.98...Ceramics layer

Claims (2)

[Claims] (1) An in-cylinder fuel injection device that injects fuel directly into a cylinder, which includes a housing in which a fuel passage is formed inside, and 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 valve member that is moved to a closed position; spring means that constantly biases the valve member to a closed position; and electromagnetic drive means that moves the valve member to an open position against the biasing force of the spring means; An in-cylinder fuel injection device, wherein at least a surface layer of the cylinder-side end of the valve member is formed of ceramics. (2) The in-cylinder injection device according to claim 1, wherein at least a surface layer of the cylinder-side end of the housing is formed of ceramics.