JP2003049738A - Fuel injection valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection valve capable of facilitating assemblage while improving heating efficiency in preheating fuel. SOLUTION: This fuel injection valve is provided with guide holes 14d, 29d, etc., a plurality of nozzle holes 28 formed at tip parts of the guide holes, valve bodies 29 and 14 having a valve seat 29a in the upstream of the nozzle hole 28, a valve member 26 contained in the guide hole to be capable of reciprocating, having an abutment part 26c to be abutted onto/separated from the valve seat 29a, and to be closed and opened by abutment/separation between the valve seat 29a and the abutment part 26c, and a heating member 50 to heat fuel in a fuel passage surrounded by the guide hole and the valve member 26. A ceramic heater 51 as the heating member is circularly disposed close to an outer circumference of a cylindrical member 14 as the valve body. An outer circumference of the ceramic heater 51 is supported by a containing member 52 abutted on the outer circumference of the valve body.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection valve, and more particularly to a fuel injection valve for injecting fuel into an intake pipe of an internal combustion engine.

[0002]

2. Description of the Related Art As a fuel injection valve, for example, a fuel injection valve which is attached to an intake pipe of an internal combustion engine to inject fuel is known. Due to the requirement for cleaning, it is necessary to atomize the injected fuel spray, especially in order to promote the vaporization of the fuel.

As one of the countermeasures, there is a method in which heated fuel is injected into an intake pipe to boil the fuel under reduced pressure to promote atomization of the fuel.

As a structure for heating the fuel in the fuel injection valve for injecting fuel into the internal combustion engine, there is a valve seat and the outside of the valve body that accommodates the valve member that can abut and separate from the valve seat. There is a heating member for heating the fuel in the valve body or a heating member for directly heating the fuel disposed between the valve member and the valve body.

[0005]

In any of the conventional constructions, consideration for facilitating assembly while improving heating efficiency is not sufficient.

That is, in the case where the heating member as the heating means is provided outside the valve body, the heat capacity is large and the heating efficiency is poor. On the other hand, in the case of directly heating the fuel, the heating efficiency can be improved, but the structure for sealing the heating member and the electric wiring connected to the heating member is difficult, and the assembly structure becomes complicated.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a fuel injection valve capable of facilitating assembly while improving heating efficiency for preheating fuel. It is in.

[0008]

According to claim 1 of the present invention, a guide hole, a plurality of injection holes formed at the tip of the guide hole,
And a valve body having a valve seat on the upstream side of the injection hole, and a contact portion that is housed in the guide hole so as to be able to reciprocate and has contact with and separation from the valve seat. , Valve separation due to separation,
A valve member to be opened and a heating member for heating the fuel in the fuel passage surrounded by the guide hole and the valve member are provided, and the heating member is arranged in an annular shape near the outer periphery of the valve body, The outer circumference of the heating member is supported by a housing member that abuts the outer circumference of the valve body.

Therefore, the inner peripheral side of the heating member arranged in an annular shape can be brought close to the outer periphery of the valve body so that the gap between the heating member and the valve body becomes small. On the other hand, the outer peripheral side of the heating member can come into contact with the outer periphery of the valve body via the housing member.

As a result, the heating member can heat the valve body from the inside of the heating member by heat transfer while suppressing the gap between the heating member and the valve body, and the heat transfer of the heating member by the heat transfer through the housing member. The valve body can be heated from the outside.

Therefore, in the heating member, the heat conducted to the inside and the outside from the heating member together heats the valve body, so that the fuel in the fuel passage inside the valve body can be efficiently heated.

According to the second aspect of the present invention, the heating member and the containing member are covered with a protective member forming an air layer,
The protective member is provided with a seal member that prevents breathing action with the outside due to expansion and contraction of the air layer.

Therefore, the heating member and the containing member are solid,
Since the air layer, which is a gas whose thermal conductivity is smaller than that of the liquid, is covered with the protective member that hermetically forms, it is possible to suppress heat radiation to other than the fuel in the valve body. Therefore, the heating efficiency of the heating member can be improved.

Although the heat conducted to the inside of the heating member heats the valve body through the air layer having a small thermal conductivity, the gap between the heating member and the valve body, that is, the thickness of the air layer is Since it can be kept small, the influence of the air layer formed in the gap is small.

According to a third aspect of the present invention, the heating member is a ceramic heater, and the ceramic heater is formed in a cylindrical shape and fixed in contact with the inner circumference of the housing member.

Generally, a ceramic heater can quickly raise its temperature after being energized, but its mechanical characteristic is that it has a weaker mechanical strength against a tensile force than a compressive force. For this reason, it is desirable that the inner circumference of the ceramic heater is brought into close contact with the outer circumference of the valve body to directly heat the ceramic heater. However, since a tensile force may act on the ceramic heater that contacts the outer circumference of the valve body, Configuration is difficult.

On the other hand, in the fuel injection valve of the present invention,
Since the outer circumference of the ceramic heater is in contact with and fixed to the inner circumference of the housing member, a compressive force may act on the ceramic heater, but a tensile force may not be received. Moreover, since the ceramic heater is fixed in contact with the inner circumference of the housing member that is in contact with the outer circumference of the valve body, the heat generated by the energization of the ceramic heater is efficiently conducted to the valve body through the directly-housing housing member. be able to.

According to claim 4 of the present invention, the accommodating member comprises:
It is a substantially cylindrical shape having a slit in the axial direction, and an arcuate slit is provided in the circumferential direction in the vicinity of the end of the heating member in the axial direction.

Since the accommodating member has slits in the axial direction, the accommodating member can adjust the holding force for supporting the outer periphery of the heating member, and since the arcuate slits are provided in the circumferential direction, the accommodating member is The holding force for supporting the outer circumference of the heating member and the holding force for abutting and fixing the outer circumference of the valve body can be independently set.

According to claim 5 of the present invention, the heating member comprises:
Equipped with an electrical connection that receives power from an external power source,
The electrical connection portion is arranged inside the housing member side which is made airtight by the seal member.

Therefore, it is possible to prevent the adhesion of moisture or the like from the outside, which causes disconnection or short circuit, to the electrical connection portion which receives power from an external power source, without separately providing a seal member.

According to claim 6 of the present invention, the heating member comprises:
A locking member that locks the position of the electrical connection portion in the fuel injection valve circumferential direction is provided, and the electrical connection portion can be assembled in the axial direction of the fuel injection valve together with the housing member.

In terms of wiring work, it is desirable that the electrical connection portion of the heating member arranged on the outer periphery of the valve body be expanded in the radial direction rather than the axial direction of the fuel injection valve. The fuel injection valve of the present invention is provided with the locking member that locks the position of the electrical connection portion in the circumferential direction of the fuel injection valve with respect to the electrical connection portion having the portion extending in the radial direction. In addition to facilitating the wiring work when assembling to the internal combustion engine, etc., when assembling the fuel injection valve parts such as the heating member and the containing member,
It is possible to facilitate the assembly by axially assembling the parts of the fuel injection valve.

According to claim 7 of the present invention, the electrical connection portion includes a first shaft portion extending radially outward from the heating member, and a second shaft portion connected to the first shaft portion and extending in the axial direction. The locking member is formed of a resin molded member that is divided into two parts so as to sandwich the first shaft part and the second shaft part.

Therefore, since the locking member is divided into two in the axial direction of the fuel injection valve so as to sandwich at least the first shaft portion extending outward in the radial direction, the assembling property by the axial assembly of the fuel injection valve is obtained. Can be further improved.

As described in claim 8 of the present invention, the two-part resin forming member is arranged so as to form a predetermined gap between the resin forming member and the accommodating member that supports the heating member.

For this reason, the heat generated by the heating member is not directly conducted to the two-divided resin forming member, but is eased by the heat insulating effect of the air layer forming the gap, for example, and the heat resistance is excellent. An inexpensive resin molding material can be used without using a resin molding material.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the fuel injection valve of the present invention will be described below with reference to the drawings.

(First Embodiment) FIG. 1 is a sectional view showing a schematic structure of a fuel injection valve according to an embodiment of the present invention. Figure 2
FIG. 2 is a cross-sectional view showing a configuration around a valve portion in FIG. 1.

(Schematic Structure of the Present Embodiment Applied to Fuel Injection Valve of Internal Combustion Engine) As shown in FIGS. 1 and 2, the fuel injection valve 1 is used for an internal combustion engine 100, particularly for a gasoline engine. Intake pipe 200 of internal combustion engine 100
The fuel is supplied to the combustion chamber 100a of the internal combustion engine 100 by being attached to the fuel injection chamber. The fuel injection valve 1 has a substantially cylindrical shape, and has a valve body 29 as a valve portion B and a valve member (hereinafter referred to as a nozzle needle) 2
6, a coil 31 wound around a spool 30 as an electromagnetic drive unit S, a cylindrical member 14 forming a magnetic circuit in which a magnetic flux due to an electromagnetic force generated by energizing the coil 31 flows, and an attractive force due to the magnetic flux causes an axial force in the axial direction. The movable armature 25 and the compression spring 24 for urging the armature 25 toward the valve body so that the nozzle needle 26 contacts the valve body 29 to close the valve when the coil 31 is not energized, and the heating means H Ceramic heater part 50 and locking member 6 for locking the ceramic heater part 50
0, and a protective member 70 that covers the ceramic heater portion 50 with an air layer.

The heating means H preheats the fuel injected from the valve section B, and depressurizes the fuel injected into the intake pipe 200 by the negative pressure of the intake pipe 200, thereby
It is intended to atomize the injected fuel. The configuration and operation of this heating means H will be described later.

The fuel injection valve 1 equipped with the heating means H
The valve section B and the electromagnetic drive section S may be of known configurations, and an example of the valve section B and the electromagnetic drive section S suitable for the fuel injection valve 1 equipped with the heating means H will be described below.

First, the valve body 29 serving as the valve portion B, the nozzle needle 26, the injection hole plate 28 formed at the tip of the valve body for injecting fuel as a fuel outlet, and the like will be described below.

The valve body 29 is fixed to the inner wall of the cylindrical member 14 by welding. Specifically, as shown in FIG. 2, the valve body 29 can be press-fitted or inserted into the magnetic cylindrical portion 14c of the cylindrical member 14. This magnetic cylinder member 1
4c is inserted into the inner wall of the valve body 29, the magnetic cylindrical portion 14
Weld the entire circumference from the outer peripheral side of c.

On the inner peripheral side of the valve body 29, there is formed a valve seat 29a with which the nozzle needle 26 abuts and separates. More specifically, as shown in FIG. 2, a fuel passage for fuel to be injected into the internal combustion engine is formed on the inner peripheral side of the valve body 29, and the valve seat is disposed from the downstream side of the internal combustion engine side toward the upstream side of the fuel. Slope 29a, large-diameter cylindrical wall surface 29
b, a conical inclined surface 29c, a small-diameter cylindrical wall surface 29d slidably supporting the nozzle needle 26, and a conical inclined surface 29e are sequentially formed. This conical inclined surface, that is, the valve seat 29a
Are reduced in diameter in the fuel injection direction, and the nozzle needle 2 described later
The contact portion 26c of 6 contacts and separates from the contact portion 26c.
And the valve seat 29a are arranged so that they can be seated. As a result, so-called valve opening and closing can be performed as a valve portion that connects and disconnects the fuel to be injected. Further, the large-diameter cylindrical wall surface 29b forms a fuel reservoir hole, that is, a fuel reservoir chamber 29f surrounded by the nozzle needle 26, and the small-diameter cylindrical wall surface 29d forms a needle support hole for slidably supporting the nozzle needle 26. Is forming. The needle support hole formed by the small-diameter cylindrical wall surface 29d has a smaller diameter than the fuel reservoir hole formed by the large-diameter cylindrical wall surface 29b.
The conical slope surface 29e has a diameter that increases toward the upstream side of the fuel.

The valve seat 29a, the large-diameter cylindrical wall surface 29b,
Conical inclined surface 29c, small diameter cylindrical wall surface 29d, conical inclined surface 29
e forms a guide hole for accommodating the nozzle needle 26 together with the inner circumference of the cylindrical member 14 described later.

The nozzle needle 26 as a valve member is a bottomed cylindrical body made of stainless steel, and a tip end portion of the nozzle needle 26 is formed with a contact portion 26c capable of contacting with and separating from the valve seat 29a. ing. More specifically, as shown in FIG. 2, the nozzle needle 26 includes a small-diameter columnar portion 26d formed in a cylindrical shape having a smaller diameter at the tip portion, that is, the fuel injection side than the fuel upstream side, and the inner circumference of the valve body 29 (in detail. Is a large-diameter cylindrical body portion 26 slidably supported on a small-diameter cylindrical wall surface 29d).
The end surface on the fuel injection side of the small-diameter columnar portion 26d is chamfered to form a conical inclined surface, which constitutes the contact portion 26c. Thereby, the contact portion 26
The size of the diameter of c, that is, the sheet diameter, is determined by the small diameter cylindrical wall surface 29.
It is formed to be smaller than the diameter of the needle support hole of d.
It is possible to achieve both the ease of precision machining of the valve seat 29a with which the contact portion 26c abuts and separates, and the securing of the valve tightness when the valve seat 29a and the abutment portion 26c abut each other when the valve is fully closed. That is, since the seat diameter is smaller than the hole diameter of the needle supporting hole formed by the small-diameter cylindrical wall surface 29d of the valve body 29, for example, the small-diameter cylindrical wall surface 29d as the inner circumference of the valve body 29, the conical inclined surface 29c, and the large-diameter cylinder. After the wall surface 29b and the valve seat 29a are formed by cutting, the valve seat 2 is formed by inserting a blade from the fuel upstream side into the fuel reservoir chamber 29f to secure the valve tightness.
Precise processing of the sheet portion 9a can be easily performed.

On the other hand, the large-diameter column portion 26e is arranged on the fuel upstream side of the nozzle needle 26, and is slightly larger than the inner diameter of the small-diameter cylindrical wall surface 29d so as to be slidably accommodated in the small-diameter cylindrical wall surface 29d of the valve body 29. It is formed in a cylindrical shape with a small outer diameter. As a result, a predetermined minute gap is formed between the outer peripheral wall surface of the large-diameter columnar portion 26e and the small-diameter cylindrical wall surface 29d so that they are in sliding contact with each other.

Most of the large-diameter columnar portion 26e is formed in a thin cylindrical shape, and as shown in FIG. 2, the inner peripheral wall surface 26a thereof has an internal passage 2 for the fuel flowing downstream of the fuel injection side.
6f is formed. The internal passage 26f is formed by punching the end surface of the large-diameter columnar portion 26e on the fuel upstream side, and the depth of the punching is the valve seat 29.
The depth is set so that the bottom portion of the nozzle needle 26 can withstand the impact generated when sitting on a.

As a result, it is possible to reduce the weight of the nozzle needle 26 and to secure the strength against the impact generated when the nozzle needle 26 abuts on the valve seat 29a.

Incidentally, on the downstream side of the internal passage of the large-diameter columnar portion 26e, to the valve seat 29a on the downstream side, that is, the fuel sump chamber 2
At least one outlet hole 26b so as to communicate with 9f.
Is provided. On the other hand, on the upstream side of the internal passage of the large-diameter columnar portion 26e, the fuel heated by the ceramic heater portion 50, which will be described later, flows through the inlet hole 26g. The details of the fuel path of the fuel heated by the ceramic heater unit 50 will be described later.

The injection hole plate 28 is formed in a thin plate shape on the tip side of the fuel injection valve 1 and has a plurality of injection holes 2 in the center thereof.
8 is formed. This injection hole 28a determines the injection direction by the injection hole axis line, the injection hole arrangement, and the like, and measures the fuel injection amount injected from the injection hole by the opening area of the injection hole and the valve opening period of the valve portion by the electromagnetic drive unit described later. You can

Next, the coil 31 as the electromagnetic drive section S,
The cylindrical member 14, the armature 25, the compression spring 24, etc. will be described below. It should be noted that the electromagnetic drive unit S may be one that opens and closes the valve portion of the fuel injection valve 9 by energizing and de-energizing.

As shown in FIG. 1, the coil 31 is wound around the outer circumference of a resin spool 30.
A terminal 12 that is electrically connected is provided at one end of the terminal 1. The spool 30 is mounted on the outer periphery of the cylindrical member 14 described later, and the connector portion 16 is provided so as to project from the outer wall of the resin mold 13 formed on the outer periphery of the cylindrical member 14. The terminal 12 is embedded in the connector portion 16.

The cylindrical member 14 is a pipe material having a magnetic portion and a non-magnetic portion, and is made of, for example, a composite magnetic material. By heating a part of the cylindrical member 14 to make it non-magnetic, the cylindrical member 14 shown in FIG.
b and the magnetic cylinder portion 14a are formed in this order. In addition,
An armature housing hole 14e is provided on the inner circumference of the cylindrical member 14, and an armature 25 described later is housed near the boundary between the non-magnetic cylinder portion 14b and the magnetic cylinder portion 14c.

Further, as shown in FIG. 1, a magnetic member 23 and a magnetic member 18 are provided on the outer periphery of the cylindrical member 14 forming a magnetic circuit in which a magnetic flux due to an electromagnetic force generated by energizing the coil 31 flows. . As a result, the magnetic flux generated by the electromagnetic force generated by energizing the coil 31 causes the magnetic cylinder portion 14a, the attraction member 22 described later, the armature 25 described later, and the magnetic cylinder portion 1 to be generated.
4c, the magnetic member 23, and the magnetic member 18 constitute a magnetic circuit that flows in this order.

The armature 25 is a stepped tubular body made of a ferromagnetic material such as magnetic stainless steel, and is fixed to the nozzle needle 26. As a result, the coil 31
When the coil is energized, the magnetic flux generated by the electromagnetic force generated in the coil 31 acts on the armature 25 via the suction member 22, so that the nozzle needle 26 as well as the armature 25.
Can be moved in the axial direction on the side of the suction member 22, that is, in the direction away from the valve seat 29a. The internal space 25e of the armature 25 is configured to communicate with the internal passage 26f of the nozzle needle 26.

A throttle hole 25f is formed on the fuel injection side of the armature 25, and a plurality of fuel connecting holes 25g are formed on the fuel upstream side of the throttle hole 25f. Regarding the throttle hole 25f and the fuel communication hole 25g, the valve member 26
The flow of fuel formed in cooperation with the outlet hole 26b and the inlet hole 26g will be described in detail.

The suction member 22 is a cylindrical body made of a ferromagnetic material such as magnetic stainless steel, and is fixed to the inner circumference of the cylindrical member 14 by press fitting or the like.

The compression spring 24 has an end surface of the adjusting pipe 21 arranged on the inner circumference of the suction member 22,
When the coil 31 is not energized by being sandwiched between the armature 25 and the spring seat 25c, which is a stepped portion that forms the internal space 25e, the armature 25
The armature 25 is applied with a predetermined biasing force to the valve body 29 side so that the nozzle needle 26 fixed to the valve body 29 is brought into contact with the valve body 29 (specifically, the contact portion 26c is brought into contact with the valve seat 29a) to close the valve. Force.

The adjusting pipe 21 is press-fitted and fixed to the inner periphery of the suction member 22, and the biasing force of the compression spring 24 can be adjusted to a predetermined biasing force by the amount of press-fitting of the adjusting pipe 21.

A valve body 29 and an injection hole plate 28 are liquid-tightly accommodated on the fuel injection side of the cylindrical member 14. The injection hole plate 28 may be liquid-tightly welded to the valve body 29 so that the valve body 29 is liquid-tightly accommodated in the cylindrical member 14. On the other hand, a filter 11 as shown in FIG. 1 is attached above the cylindrical member 14, and this filter 11 can remove foreign matters contained in the fuel flowing from the fuel upstream of the fuel injection valve 1. is there.

Here, the cylindrical member 14 which is oil-tightly fixed to the valve body 29 forms a guide hole for accommodating the nozzle needle 26 together with the valve body 29, and therefore is also a part of the valve body 29.

When the fuel injection valve is mounted on the intake pipe 200, as shown in FIG. 1, an air cleaner 300 is provided on the upstream side of the intake pipe 200 and on the downstream side thereof.
A throttle valve (not shown) for changing the amount of intake air flowing through the intake passage 200a of the intake pipe 200 is provided. On the other hand, an intake manifold (not shown) that introduces intake air into each cylinder of the internal combustion engine is connected to the downstream side of the intake pipe 200, and the fuel injected from the fuel injection valve is intaken through this intake manifold. Together with this, it is supplied to the combustion chamber 100a. It should be noted that the intake pipe 200 here may include an intake manifold, and the fuel injection valve may be mounted on an intake manifold provided in the internal combustion engine 100.

On the other hand, the fuel stored in a fuel tank (not shown) or the like is pumped up by a fuel pump (not shown) and, as shown in FIG. 1, through the delivery pipe 400 from the fuel inflow side in the arrow direction. The pressurized fuel is supplied to the fuel injection valve. Therefore, the fuel injection valve, especially the valve portion B,
The pressure force of this fuel is applied to the fuel injection side.

Here, the fuel injection valve 1 having the above-mentioned structure
The operation of will be described below.

When the coil 31 of the electromagnetic drive section is energized, an electromagnetic force is generated in the coil 31. At this time, in the armature 25 and the suction member 22 which form the magnetic circuit, a suction force for sucking the armature 25 is generated in the suction portion 25. As a result, the nozzle needle 26 fixed to the armature 25 is separated from the valve seat 29a of the valve body 29. Therefore, the valve body 29 and the nozzle needle 26 are opened, and the fuel flowing from the upstream side of the fuel injection valve 1 is
Via the armature accommodation hole 14e, the internal passage 26f, etc.,
Through the injection hole 28a, the intake pipe 200, that is, the internal combustion engine 1
It is injected to 00.

(Main parts of this embodiment and detailed description thereof)
The fuel injection into the internal combustion engine described above is performed by the fuel injection pressure injected from the fuel injection valve 1, in other words, the fuel pressure supplied to the upstream side of the fuel injection valve 1 and the intake pressure negative pressure flowing in the intake pipe 200. The fuel is atomized by the pressure difference between and. On the other hand, if the preheated fuel is depressurized and boiled by utilizing the negative pressure of intake air, the atomization of the fuel can be further improved. Therefore, in particular, the fuel injected at the cold start of the internal combustion engine 100 is atomized by the depressurization boiling. Is desirable. Therefore, the present embodiment aims to improve the heating efficiency of the injected fuel to be boiled under reduced pressure by the following configuration.

First, the ceramic heater portion 50 as the heating means H, the locking member 60 for locking the ceramic heater portion 50, the protective member 70 for covering the ceramic heater portion 50 with an air layer, and the like will be described.

The ceramic heater section 50 includes a ceramic heater 51 as a heating member and the ceramic heater 5.
It comprises a housing member 52 for supporting 1 and an electrical connection portion 53 for receiving power supply to the ceramic heater 51 from the outside.

The ceramic heater 51 is formed by sintering a heating resistor with ceramic. PTC (Posi
live Temperature Coeffici
ent) The heater is also considered as a part of the ceramic heater. As shown in FIG. 1, the ceramic heater 51 is formed in a cylindrical shape and is arranged near the outer periphery of the cylindrical member 14 (as a part of the valve body 29) on the fuel upstream side of the valve seat 29a. ing.

As shown in FIGS. 1 and 2, the ceramic heater 51 disposed near the outer periphery of the cylindrical member 14 as the valve body is supported by the accommodating member 52 on the outer periphery thereof, and the cylindrical member is interposed via the accommodating member 52. It is fixed to the outer circumference of 14. It should be noted that the ceramic heater 51 may be divided into a plurality of pieces and have a circular arc cross section and be arranged in an annular shape.
Specifically, the housing member 52 has a large-diameter cylindrical portion 52a and a small-diameter cylindrical portion 52b, and is integrally formed of a material having a high thermal conductivity, such as copper or brass. This large-diameter cylindrical portion 52
A ceramic heater 51 is formed on the inner periphery of a by, for example, press fitting.
On the other hand, the inner circumference of the small diameter cylindrical portion 52b is fixed on the outer circumference of the cylindrical member 14 by press fitting or the like.

Therefore, the inner peripheral side of the ceramic heater 51 can be arranged on the outer periphery of the cylindrical member 14 so that the gap between the ceramic heater 51 and the cylindrical member 14 becomes small. On the other hand, the outer peripheral side of the ceramic heater 51 can heat the cylindrical member 14, that is, the valve body 29 from the outer peripheral side of the ceramic heater 51 by heat transfer via the housing member 52.

Therefore, in the ceramic heater 51, the heat conducted from the ceramic heater 51 to the inner peripheral side and the outer peripheral side together heats the cylindrical member 14, that is, the valve body 29, so that the fuel inside the valve body 29 is efficiently heated. be able to.

Moreover, since the ceramic heater 51 is fixed in contact with the inner periphery of the housing member 52, the mechanical characteristics of the ceramic heater 51 are advantageous as follows in terms of the assembly structure. Generally, as a mechanical material characteristic of the ceramic of the ceramic heater 51, mechanical strength against tensile force is weaker than compressive force. On the other hand, the present embodiment has a configuration in which contact fixing is not performed on the inner circumference of the ceramic heater 51 to which a tensile acting force is easily applied, but contact fixing is performed on the outer circumference of the ceramic heater 51 to which a compressive acting force is easily applied. The heating means H by the ceramic heater 51 having improved mechanical characteristics can be provided.

Further, the ceramic heater 51 and the containing member 5
2, as shown in FIG. 1, it is covered with a protective member 70 forming an air layer 80 on the outer periphery thereof.
No. 0 is provided with at least one seal member 92 for preventing breathing action with the outside due to expansion and contraction of the air layer. The protective member 70 is resin-molded by insert-molding the protective cover member 71. In the resin mold 72 formed by resin molding, the electrical connection portion 53 is embedded in the connector portion 72a together with the protective cover member 71. (In other words, the resin mold 72 forms the locking member 60 that locks the ceramic heater 51 as the ceramic heater portion 50). Therefore, in order to prevent the mold resin 72 from flowing into the ceramic heater 51 to which the electrical connection portion 53 is connected, that is, the protective cover member 71, the sealing member 73 closes the opening of the protective cover member 71. ing.

As a result, the ceramic heater 51 and the containing member 52 are covered with the protective member 70 that hermetically forms the air layer 80, which is a gas having a smaller thermal conductivity than solid or liquid, so that the ceramic heater 51 is contained. It is possible to suppress the heat radiation to other than the fuel in the valve body 29 (specifically, the cylindrical tube portion 14 and the valve body 29) among the heat radiation by the. Therefore, the ceramic heater 5 as the heating means H
The heating efficiency of 1 can be improved.

The heat conducted to the inner peripheral side of the ceramic heater 51 heats the valve body 29 through the air layer 80 having a small thermal conductivity, but the gap between the ceramic heater 51 and the air layer 80. Since the thickness of the air layer can be kept small, the air layer 80 formed in the gap is
Has a small effect.

The airtightness of the lower side of the protective member 70 is determined by the fuel injection valve hole 20 of the intake pipe 200 for accommodating the fuel injection valve 1.
It is kept by the seal member 91 sandwiched between the bottom portion of 0b and the protective cover member 71 of the protective member 70. Specifically, fuel stored in a fuel tank (not shown) or the like is pumped up by a fuel pump (not shown),
The pressurized fuel is supplied to the fuel injection valve 1 from the fuel inflow side indicated by the arrow. Therefore, the fuel injection pressure is applied to the fuel injection valve 1, particularly the valve portion B, toward the fuel injection side. Therefore, the pressure applied by this fuel causes the fuel injection valve, that is, the protective cover member 71 to cause the seal member 91 and the fuel injection valve hole 2
Airtightness can be maintained by pressing the bottom of 00b.

Here, in the connector portion 72a of the protective member 70 in which the electrical connection portion 53 is embedded, as shown in FIG. 1, a terminal holder 54 having both female shaft ends is provided. The drive unit S is arranged so that it can be assembled in the axial direction to the terminal 19 embedded in the resin mold 13. The terminal 19 of the resin mold 13
A seal member 73 is provided on the base portion 13a of the above to keep the connector portion 72a airtight. As a result, a short circuit due to intrusion of water droplets or the like from the outside into the electrical connection portion 53,
Problems such as disconnection can be prevented.

In order to further improve the heating efficiency of the fuel in the valve body 29 (specifically, the cylindrical member 14 and the valve body 29) by the ceramic heater 51 of the heating means H having the above-mentioned structure, the valve portion B is used. Preferably has the following characteristics.

First, the valve body 29 is inserted through the cylindrical member 14.
When heating the fuel in the cylindrical member 14, it is desirable that the flow of the fuel to be heated be distributed unevenly in the vicinity of the inner circumference 14d of the cylindrical member 14.

Therefore, as shown in FIG. 1 and FIG.
In the fuel flowing between the nozzle needle 26 and the armature 25 fixed to the nozzle needle 26 and the cylindrical member 14, the flow passage area of the throttle hole 25f formed in the armature 25 is smaller than the flow passage area of the fuel communication hole 25g. Has been done. As a result, the fuel that has flowed in from the upstream of the fuel injection valve 1 can mainly flow through the outer periphery of the nozzle needle 26 through the fuel communication hole 25g. Therefore, the ceramic heater 51 can efficiently heat the fuel that is biased near the inner circumference 14 d of the cylindrical member 14 through the cylindrical member 14.

Further, as shown in FIG. 2, the cylindrical heat transfer pipe 1 is provided on the inner circumference 14d of the cylindrical member 14 to which the heat conducted to the inner circumference side and the outer circumference side of the ceramic heater 51 is directly transferred.
4h is provided. As a result, the flow passage area of the fuel flow biased near the inner circumference 14d of the cylindrical member 14 can be reduced, so that the fuel heated by the ceramic heater 51 can be heated in a shorter time. The flow passage area of the fuel flow by the heat transfer pipe 14h is determined by the contact portion 26c and the valve seat 2 when the nozzle needle 26 is fully lifted.
It is desirable to secure a flow passage area larger than the opening area formed between the opening 9a and 9a. Thus, the fuel flowing in from the upstream side of the fuel injection valve 1 can be injected from the injection hole 28 arranged on the downstream side of the valve seat 29a without causing fluid loss.

In this embodiment, as shown in FIG. 2, the heat transfer pipe 14h is provided to reduce the inner peripheral diameter of the cylindrical member 14 to reduce the flow passage area.
In place of the configuration in which the above is added, the diameter of the outer peripheral portion of the nozzle needle 26 corresponding to the heat transfer pipe 14h may be increased.

On the other hand, the ceramic heater 51 has a valve seat 29.
Since it is arranged near the outer periphery of the cylindrical member 14 (as a part of the valve body 29) on the fuel upstream side with respect to a through the accommodating member 52, the axial length of the ceramic heater 51 or the accommodating member 52 is a cylinder. Member 14 and nozzle needle 2
You will need to 6. In the solid nozzle needle 26, the weight of the nozzle needle 26 becomes heavy, and the open / close responsiveness of the fuel injection valve 1 may deteriorate. On the other hand, in this embodiment, as shown in FIG. 1, the nozzle needle 26 is formed in a bottomed tubular shape having a bottom portion 26d on the valve seat 29a side. As a result, the weight of the nozzle needle 26 can be reduced, and the open / close response can be improved.

Generally, the fuel is the ceramic heater 5
There is a risk that fuel vapor (so-called vapor) will be generated in the fuel by being heated by the first and the like. In some cases, if the amount of the fuel vapor accumulated in the fuel becomes large, the reciprocating movement of the nozzle needle 26 may be hindered by the damper effect of the fuel vapor. On the other hand, in the present embodiment, the main flow of fuel flowing around the outer periphery of the nozzle needle 26 flows in through the fuel communication hole 25g fixed to the upper portion of the nozzle needle 26, so that the cylindrical member 14, that is, the heat transfer pipe 14h. Even if the fuel flowing through the fuel heater generates fuel vapor due to heating of the ceramic heater 51, the generated fuel vapor passes through the fuel communication hole 25g of the armature 25 disposed upstream of the valve portion B, that is, the nozzle needle 26, and the generated fuel vapor of the fuel injection valve 1 is discharged. It is discharged upstream. Further, even if this fuel vapor may flow into the inlet hole 26g arranged on the downstream side of the nozzle needle 26, the fuel is discharged from the throttle hole 25f of the armature 25 arranged at a position corresponding to the ceiling of the nozzle needle 26. Steam can be discharged. Therefore, the reciprocating movement of the nozzle needle 26, that is, the responsiveness can be secured.

Here, when the internal combustion engine 100 is started by turning on the ignition key, the ceramic heater 51 is supplied with electric power for a certain period of time from the start of the start.
When this power supply is started, the ceramic heater 51 instantly heats up. The electric power is supplied to the coil 31 of the electromagnetic drive section S while the ceramic heater 51 is being supplied with electric power, and the nozzle needle 26 is separated from the valve seat 29a. The fuel flowing from the fuel communication hole 25g of the armature 25 through the outer circumference of the nozzle needle 26 to the inner circumference of the nozzle needle 26 through the inlet hole 26g flows into the cylindrical member 14 (specifically, the heat transfer pipe 14).
It is heated by the ceramic heater 51 via h). When the heated fuel is injected from the injection hole 28, the fuel is boiled under reduced pressure and atomized.

Therefore, the ceramic heater 51, the containing member 52, etc., which do not come into direct contact with the fuel, become hot due to the temperature rise of the ceramic heater 51. Therefore, in the present embodiment, the ceramic heater 51 and the containing member 5 which become high temperature when the protective member 70 is molded by the resin mold 72.
Secondly, there is a need for a configuration in which the opening of the protective cover member 71 of the protective member 70 is closed by the sealing member 73 so that the resin mold 72 does not adhere. Therefore, as the protection member 70, it was possible to make the fuel injection valve 1 easy to assemble in the so-called main body portion of the fuel injection valve 1 of the electromagnetic drive portion S and the valve portion B in the axial direction. , Protection member 70
The assembly of the respective parts for completing the process itself is a little complicated due to the addition of the sealing member 73 at the time of molding and the contact fixing of the housing member 52 after molding to the cylindrical member 14.

(Second Embodiment) Therefore, in the second embodiment, the ceramic heater section 5 constituting the heating means H is used.
It is an object of the present invention to provide a fuel injection valve 1 capable of improving the assemblability of 0, the locking member 60, and the protection member 70.

That is, in the protection member 70 described in the first embodiment, the protection cover member 71 is insert-molded in the resin mold 72 as the locking member 60 for locking the ceramic heater 51 via the electrical connection portion 53. Instead of the configuration, in the second embodiment, as shown in FIGS. 3 and 4, the protective member 70 and the locking member are separately formed, and each can be assembled in the axial direction of the fuel injection valve 1. Characterized by the configuration.

Here, FIG. 3 is a cross-sectional view showing the structure of the fuel injection valve of the second embodiment, and FIG. 4 is an exploded view showing the structure around the heating member in FIG. 5 is a cross-sectional view showing the relationship between the heating member and the locking member in FIG. 4, and FIG. 6 is a cross-sectional view taken along the line VV in FIG.

First, as shown in FIGS. 3 and 4, the ceramic heater section 50 is fixed to the ceramic heater 51 and the cylindrical member 14 by contacting them with the same ceramic heater 51 and electrical connection section 53 as in the first embodiment. The housing member 52 has improved ease of assembly.

As shown in FIG. 4, the accommodating member 52 is provided on the upper side of the large-diameter cylindrical portion 52a so that the electric connection portion 53 electrically connected to the ceramic heater 51 can be easily extended to the outside in the radial direction of the accommodating member 52. A cutout portion 52c is provided. Thereby, even if the connection position of the electrical connection portion 53 of the ceramic heater 51 moves with respect to the large-diameter cylindrical portion 52a of the housing member 52, it is possible to prevent a short circuit problem with the housing member 52. Therefore, the ceramic heater 51 and the large-diameter cylindrical portion 52a can be fixed in contact with each other by, for example, light press fitting. Therefore,
It is possible to reduce the compressive force by the housing member 52 that affects the mechanical characteristics of the ceramic heater 51.

More specifically, as shown in FIG. 4, an annular containing member 52 is provided with an axial slit 52d. Thus, when a press-fitting load more than necessary is applied to the ceramic heater 51, the width of the slit 52d is widened to prevent an excessive press-fitting load from occurring, and thus the press-fitting load applied to the ceramic heater 51 can be suppressed to a necessary load. it can. In other words, this slit 52d enables adjustment of the holding force with which the housing member 52 supports the outer periphery of the ceramic heater 51.

Further, the large diameter tubular portion 52a and the small diameter tubular portion 52b.
Between, that is, the axial end portion 51 of the ceramic heater 51.
It is desirable to provide an arcuate slit 52e in the circumferential direction near b. As a result, the ceramic heater 51
The holding force for supporting the outer periphery of the cylindrical member 14 and the holding force for contacting and fixing the outer periphery of the cylindrical member 14 can be set independently.

If the accommodating member 52 is formed of a material having a spring characteristic and high thermal conductivity by pressing or the like, it can be manufactured at a low cost.

Next, the locking member 60 for locking the ceramic heater portion 50 is the same as in the first embodiment.
By locking the circumferential position of No. 3, the ceramic heater 51
Is formed of resin molded members 61 and 62 which are axially divided into two parts corresponding to the shape of the electrical connection portion 53 so as to sandwich the electrical connection portion 53.

Generally, the fuel injection valve 1 is housed in the fuel injection valve hole 200b of the intake pipe 200 and mounted on the internal combustion engine 100. Therefore, in order to heat the fuel in the valve portion B, the ceramic heater portion 50 provided under the fuel injection valve 1
It is desirable that the electrical connection portion 53 that receives power supply from the outside be axially extended inside the fuel injection valve 1 and be radially extended on the upper side of the fuel injection valve 1 from the viewpoint of wiring work during mounting. .

Therefore, as shown in FIGS. 4 to 6, the electrical connection portion 53 of the embodiment of the present invention includes a first shaft portion 53a extending radially outward from the ceramic heater 51 and a first shaft portion 53a thereof. Intermediate shaft portion 53b extending in the circumferential direction from the shaft portion 53a.
And a second shaft portion 53c extending from the intermediate shaft portion 53.

On the other hand, of the resin molding members 61 and 62 serving as the locking member 60 for sandwiching the electrical connection portion 53, the resin molding member 62 includes the first resin molding member 62 as shown in FIGS.
A groove 61a corresponding to the shapes of the shaft portion 53a and the intermediate shaft portion 53b is provided. This groove has shaft portions 53a, 53
The groove width and groove depth are larger than the shaft diameter of b. This allows
Since the locking member 60 sandwiches at least the first shaft portion 53a extending in the radial direction, the circumferential position of the electrical connection portion 53 can be limited. Moreover, the locking member 60 is used for the second shaft portion 5
Since the intermediate shaft portion 53b extending in the circumferential direction connected to 3c is also sandwiched, the axial runout of the ceramic heater portion 50 connected to the electrical connection portion 53 in the axial direction of the fuel injection valve can be limited (in other words, the ceramic heater portion 50). Axis adjustment is possible). Therefore, when the accommodation member 52 of the ceramic heater portion 50 is fixed in contact with the cylindrical member 14, the locking member 60 is used.
When assembling the fuel injection valve 1 by assembling the ceramic heater part 50 and the ceramic heater part 50 in the axial direction, the work of the axial direction assembling in which the housing member 52 of the ceramic heater part 50 is fixed in contact with the cylindrical member 14 becomes easy. Therefore, it is possible to facilitate the assembly by assembling the parts of the fuel injection valve 1 in the axial direction.

Further, the protective member 70 does not have the resin mold 73 in which the protective cover member 71 is inserted as in the first embodiment, but as shown in FIG. The housing member 52 of 50 is fixed to the cylindrical member 14 so as to cover the fixed ceramic heater portion 50 and the locking member 60. As a result, as shown in FIG. 3, the airtightness of the air layer 80 covering the ceramic heater portion 50 and the electrical connection portion 53 can be maintained by the single sealing member (specifically, the O-ring) 92. That is, the seal member 93 dedicated to the electrical connection portion 53 described in the first embodiment is unnecessary, and the number of parts of the seal member can be reduced.

As shown in FIGS. 3 and 4, when the fuel injection valve 1 is assembled, the ceramic heater portion 50, the locking member 60, and the protection member 70 can be sequentially assembled in the axial direction in this order. The assembling property of the axial assembly of No. 1 can be further improved.

Since the electrical connection portion 53 is not embedded in the resin mold 72 as in the first embodiment, the terminal holders 54 for both females shown in FIG. 1 are unnecessary and the assembly structure of the fuel injection valve is simple. Can be converted.

As shown in FIGS. 3 and 5, the resin molded member 61 of the locking member 60 has an inner circumference larger than the outer diameter of the large-diameter cylindrical portion 52a forming the outer circumference of the ceramic heater portion 50. To do. For this reason, the locking member 60 is separated from the ceramic heater 51 and the housing member 52, which have high temperature, via the air layer 80, and thus the ceramic heater 5
The heat generation of No. 1 is not directly conducted, and the heat influence is mitigated by the heat insulation effect of the air layer 80. Therefore,
The locking member 60 can be formed of an inexpensive resin molding material without using a resin molding material having excellent heat resistance.

(Modification) In the second embodiment, the resin molding members 61 and 6 which constitute the locking member 60 are divided into two.
Of the two, the groove 61 is formed on the split surface on the side of one resin molding member 61.
Although the configuration in which a is provided has been described, as a modification, as shown in FIG. 7, a similar groove 62a may be provided on the divided surface on the other resin molding member 61 side.

As a result, the locking member 60 and the ceramic heater 70 can be easily inserted into the groove 61 regardless of the vertical direction in FIG.
Axial assembling can be easily performed along a or the groove 62a.

[Brief description of drawings]

FIG. 1 is a sectional view showing a configuration of a fuel injection valve according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a configuration around a valve section in FIG.

FIG. 3 is a cross-sectional view showing a configuration of a fuel injection valve of a second embodiment.

FIG. 4 is an exploded view showing the assembly structure around the heating member in FIG. 3, particularly, the locking member.

5 is a cross-sectional view showing the relationship between the heating member and the locking member in FIG.

6 is a cross-sectional view as seen from a VV cross section in FIG.

FIG. 7 is a plan view showing a modification example of the locking member viewed from the VI direction in FIG.

[Explanation of symbols]

1 Fuel Injection Valve 11 Filter 14 Cylindrical Member (Part of Valve Body) 14d Inner Circumference (Part of Guide Hole of Valve Body) 25 Armature 25f Throttle Hole 25g Fuel Communication Hole 26 Nozzle Needle (Valve Member) 26b, 26g Outlet Hole , Inlet hole 26c abutting portion 26e large diameter columnar portion (thin cylindrical body) 28, 28a injection hole plate, injection hole 29 valve body 29a valve seats 29b, 29c, 29d, 29e Diameter cylindrical wall surface, conical inclined surface, small diameter cylindrical wall surface (needle support hole), conical inclined surfaces 29f, 14e (fuel passage in the valve body) fuel reservoir chamber, needle accommodating hole 31 coil 50 ceramic heater portion 51 ceramic heater (heating member) ) 51b Axial end portion 52 Housing members 52a, 52b Large diameter tubular portion, Small diameter tubular portion 52c Cutting corner portions 52d, 52e Axial slits, Circumferential direction of the circular slit 53 electrical connections 53a, 53b, 53c first shaft portion, middle shaft portion, the second
Shaft 60 Locking members 61, 62 Resin molded members 61a, 62a (Holding electrical connection portion 53) Groove 70 Protective member 71 Protective cover member 72 Resin mold 92 O-ring (seal member) 100 Internal combustion engine (combustion of Chamber) 200 intake pipe 200a fuel injection valve hole 300 air cleaner 400 delivery pipe B valve section S electromagnetic drive section H heating means

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F02M 51/06 F02M 69/00 310T 51/02 F 69/00 310 31/12 321E 321G F term (reference) 3G066 AA01 AB02 AD10 BA03 BA23 BA31 BA41 BA47 BA50 BA56 BA61 CC00 CC06U CC14 CC18 CC20 CC26 CD04 CD10 CD14 CD15 CD17 CD18 CD22 CD24 CE22 CE30 CE31 DB01

Claims (8)

[Claims] 1. A guide hole, a plurality of injection holes formed at the tip of the guide hole, and a valve body having a valve seat upstream of the injection hole; and a reciprocally housed in the guide hole, A valve member that has an abutting portion that can come into contact with and separate from the valve seat, and that is closed and opened by abutting and separating between the valve seat and the corresponding contact portion, and is surrounded by the guide hole and the valve member. A heating member for heating the fuel in the fuel passage, the heating member being annularly arranged near the outer periphery of the valve body, and the outer periphery of the heating member abuts the outer periphery of the valve body. A fuel injection valve, which is supported by a housing member. 2. The heating member and the containing member are covered with a protective member that forms an air layer, and the protective member prevents a breathing action with the outside due to expansion and contraction of the air layer. The fuel injection valve according to claim 1, wherein the fuel injection valve is provided. 3. The heating member is a ceramic heater, and the ceramic heater is formed in a cylindrical shape and is fixed in contact with the inner circumference of the accommodating member. The fuel injection valve described in 1. 4. The accommodating member is a substantially cylinder having a slit in the axial direction, and an arcuate slit is provided in the circumferential direction in the vicinity of an end portion in the axial direction of the heating member. The fuel injection valve according to any one of claims 1 to 3, which is characterized. 5. The heating member includes an electrical connection portion that receives power from an external power source, and the electrical connection portion is disposed inside the housing member side that is made airtight by the sealing member. The fuel injection valve according to any one of claims 1 to 4, wherein 6. The heating member includes a locking member for locking the position of the electrical connection portion in the circumferential direction of the fuel injection valve, and can be assembled in the axial direction of the fuel injection valve together with the housing member. The fuel injection valve according to claim 5. 7. The electrical connecting portion includes a first shaft portion that extends radially outward from the heating member, and a second shaft portion that is connected to the first shaft portion and extends in the axial direction. 7. The locking member is formed of a resin molding member that is divided into two so as to sandwich the first shaft portion and the second shaft portion. The fuel injection valve according to any one of claims. 8. The resin-formed member divided into two is arranged so as to form a predetermined gap between the divided resin-formed member and the housing member that supports the heating member. 2. The fuel injection valve according to item 1.