JP2003293899A - Fuel injection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection device wherein a cylindrical member is easily mounted to a fixed core. <P>SOLUTION: The cylindrical member 12 has a first magnetic member 13, a non-magnetic member 14 as a magnetic resisting member, and a second magnetic member 15 successively arranged from an fuel injection side. A valve member 20 is a bottomed cylindrical hollow, and seatable on a valve seat 18a formed on an inner peripheral wall of a valve body 18. When the valve member 20 is separated from the valve seat 18a, the fuel is injected from an injection hole 19a. The fixed core 30 is cylindrical, and mounted and fixed to the cylindrical member by being press-fitted inside of the non-magnetic member 14 and the second magnetic member 15 of the cylindrical member 12. The fixed core 30 is mounted at a side contrary to the injection side with respect to the movable core 22, and faced to the movable core 22. The fixed core 30 also acts as a locking member for locking the movable core 22. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection device (hereinafter referred to as an injector) for an internal combustion engine (hereinafter referred to as an engine).

[0002]

2. Description of the Related Art As shown in FIG. 4, a cylindrical tubular member 20.
An injector 200 is known in which a valve member 210, a movable core 212, and a fixed core 214 are housed in the inside. The tubular member 202 includes the first magnetic member 2 from the injection hole 208 side.
03, a magnetic resistance member 204, and a second magnetic member 205 in this order. The movable core 212 reciprocates together with the valve member 210 that interrupts fuel injection from the injection hole 208.
The fixed core 214 is installed on the side opposite to the injection hole of the movable core 212 and faces the movable core 212. The fixed core 214 is attached to the tubular member 202 by welding 220.

[0003]

However, the work of positioning the fixed core 214 with respect to the tubular member 202 and attaching the fixed core 214 to the tubular member 202 by welding is complicated. Further, when welding the tubular member 202 and the fixed core 214, the position of the fixed core 214 may shift in the reciprocating direction of the valve member 210. When the position of the fixed core 214 shifts in the reciprocating direction of the valve member 210, the fixed core 21
4 and the maximum gap formed between the movable core 212 change. Since the injection rate varies from injector to injector for the same control current waveform, the number of steps for adjusting the injection amount for each injector increases.

An object of the present invention is to provide an injector that easily attaches a fixed core to a tubular member. Another object of the present invention is to provide an injector whose fuel injection amount can be easily adjusted. Another object of the present invention is to provide an injector that reduces the number of parts.

[0005]

According to the injector of claim 1 of the present invention, since the fixed core is mounted in the tubular member by press fitting, the mounting of the fixed core is easy. Moreover, since the fixed core is positioned by press fitting into the tubular member, the fixed core can be positioned with high accuracy with respect to the tubular member. Since the maximum gap formed between the movable core and the fixed core does not vary from injector to injector, it is easy to adjust the injection amount of the injector.

According to the injector of the second or third aspect of the present invention, the fixed core or the locking member positioned by the fixed core locks the movable core to define the lift amount of the valve member. Since the fixed core is positioned with high accuracy with respect to the tubular member and the mounting position does not vary from injector to injector, the maximum lift amount of the valve member that reciprocates together with the movable core can be made uniform in each injector. Further, according to the injector of the second aspect of the present invention, since the fixed core also serves as the locking member that locks the movable core, the number of parts is reduced.

In addition to the structure of the injector according to claim 2 or 3 of the present invention, according to the injector according to claim 4, since the valve member is made hollow and the weight is reduced, the fixed core is retained when the movable core is locked. The impact received is small. Therefore, the displacement of the fixed core can be prevented. According to the injector of claim 5 of the present invention, the thickness of the fixed core is thicker than the thickness of the tubular member at the press-fitting location where the fixed core is attached to the tubular member. The core is not deformed, and the tubular member is deformed.
It is possible to prevent the magnetic attraction force acting between the fixed core and the movable core from changing due to the change in shape of the fixed core.

According to the injector of claim 6 of the present invention, the fixed core is press-fitted into the inner peripheral wall of the tubular member at a portion of the axial length in the press-fitting direction. Since the length of the fixed core press-fitted into the tubular member becomes shorter, the press-fitting force when press-fitting the fixed core into the tubular member becomes smaller. Therefore, it is easy to press fit the fixed core.

According to the injector of claim 7 of the present invention, the press-fitting portion press-fitted into the inner peripheral wall of the tubular member and the press-fitting portion which has a smaller outer diameter than the press-fitting portion and is not in contact with the inner peripheral wall of the tubular member. On the other hand, a small-diameter portion located in at least one of the reciprocating direction of the valve member is formed in the fixed core, and the press-fitting portion of the fixed core is press-fitted in the tubular member. Since the outer peripheral wall of the fixed core is processed to form the press-fitting portion and the small diameter portion,
Easy to press-fit and small diameter parts.

According to the injector of claim 8 of the present invention, the tubular member is provided in the space formed between the outer peripheral wall of the small diameter portion located between the press-fitting portion and the large diameter portion and the inner peripheral wall of the tubular member. The press-fitting debris generated when the fixed core is press-fitted in is accommodated. It is possible to prevent the press-fitting debris from moving toward the injection hole side and being caught between the valve member and the valve seat.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A plurality of examples showing an embodiment of the present invention will be described below with reference to the drawings. (First Embodiment) FIG. 1 shows an injector according to the first embodiment of the present invention. The tubular member 11 is formed in a cylindrical shape including a magnetic member and a non-magnetic member. A fuel passage 100 is formed in the tubular member 12, and the valve body 18, the valve member 20, the movable core 22, the spring 24 as a biasing member, the fixed core 30, and the adjusting pipe 36 are accommodated in the fuel passage 100. Has been done.

The cylindrical member 12 has a first magnetic member 13, a non-magnetic member 14 as a magnetic resistance member, and a second magnetic member 15 in this order from the lower fuel injection side in FIG.
The first magnetic member 13 and the non-magnetic member 14, and the non-magnetic member 14 and the second magnetic member 15 are joined by welding. Welding is performed by laser welding, for example. Non-magnetic member 1
4 prevents the magnetic flux from being short-circuited between the first magnetic member 13 and the second magnetic member 15. The valve body 18 is fixed to the inside of the injection hole side of the first magnetic member 13 by welding. As shown in FIG. 2, the second magnetic member 15 has a joining portion 16 welded to the non-magnetic member 14, and a housing portion 17 located on the opposite side of the joining portion 16 from the non-magnetic member 14. ing. The inner diameter of the housing portion 17 is larger than the inner diameter of the coupling portion 16. Figure 1
As shown in, the cup-shaped injection hole plate 19 is fixed to the outer peripheral wall of the valve body 18 by welding. The injection hole plate 19 is formed in a thin plate shape, and a plurality of injection holes 19a are formed in the central portion.

The valve member 20 has a hollow cylindrical shape with a bottom, and a contact portion 21 is formed on the bottom side of the valve member 20. The abutting portion 21 is formed on the inner peripheral wall of the valve body 18
Can be seated on a. When the contact portion 21 is seated on the valve seat 18a, the injection hole 19a is closed and fuel injection is blocked. The movable core 22 is fixed to the side opposite to the injection hole of the valve member 20 by welding or the like. A plurality of fuel holes 20a penetrating the side wall of the valve member 20 are formed on the upstream side of the contact portion 21. Valve member 2
The fuel that has flowed into 0 passes through the fuel hole 20a from the inside to the outside, and goes to the valve portion formed by the contact portion 21 and the valve seat 18a.

The fixed core 30 is formed in a cylindrical shape.
The fixed core 30 is press-fitted into the non-magnetic member 14 and the second magnetic member 15 of the tubular member 12 so that the tubular member 1
It is attached to 2 and fixed. The direction in which the fixed core 30 is press-fitted into the tubular member 12 is the same as one of the reciprocating movement directions of the valve member 20. The fixed core 30 is installed on the side opposite to the injection hole with respect to the movable core 22, and faces the movable core 22. A non-magnetic material is applied to the end surface of the fixed core 30 facing the movable core 22. The fixed core 30 also serves as a locking member that locks the movable core 22.

As shown in FIG. 2, the fixed core 30 has the structure shown in FIG.
The first small diameter portion 31, the press-fitting portion 32, the second small diameter portion 33, and the large diameter portion 34 are provided in this order from the movable core 22 side which is the lower side of the. The press-fitting portion 32 and the large diameter portion 34 have the same outer diameter. The outer diameters of the first small diameter portion 31 and the second small diameter portion 33 are the press fitting portions 32.
And smaller than the outer diameter of the large diameter portion 34, the first small diameter portion 31
The second small diameter portion 33 is not in contact with the inner peripheral wall of the tubular member 12.

The press-fitting portion 32 is press-fitted into the inner peripheral wall of the non-magnetic member 14 and the inner peripheral wall of the coupling portion 16 of the second magnetic member 15. The thickness of the press-fitting portion 32 is the connecting portion 1 of the non-magnetic member 14 and the second magnetic member 15 which is the press-fitting portion with the press-fitting portion 32.
Thicker than 6. The outer diameter of the press-fitting portion 32 is larger than the inner diameter of the non-magnetic member 14 and the inner diameter of the coupling portion 16 of the second magnetic member 15 before the fixed core 30 is press-fitted into the tubular member 12. An annular space 110 is formed between the outer peripheral wall of the second small diameter portion 33 and the inner peripheral wall of the second magnetic member 15. The large diameter portion 34 has the same outer diameter as the press-fitting portion 32, but the large diameter portion 34
And the housing portion 1 of the second magnetic member 15 which faces each other in the radial direction.
Since the inner diameter of 7 is larger than the inner diameter of the coupling portion 16, the large diameter portion 34 is not press-fitted into the housing portion 17 and forms a minute gap with the housing portion 17. The large diameter portion 34 is the accommodating portion 17
The minute gap formed between and is such a gap that press-fitting debris described later cannot pass through. The large-diameter portion 34 and the accommodating portion 17 may be lightly contacted with each other, not with a force of press fitting.

As shown in FIG. 1, the adjusting pipe 36 is press-fitted into the fixed core 30. The spring 24 has one end locked to the adjusting pipe 36 and the other end locked to the movable core 22. The load of the spring 24 can be changed by adjusting the press-fitting amount of the adjusting pipe 36. Spring 24
Urges the valve member 20 toward the valve seat 18a.

The magnetic members 40 and 42 are magnetically connected to each other and are installed on the outer peripheral side of the coil 44. Magnetic member 4
0 is magnetically connected to the first magnetic member 13, and the magnetic member 42
Are magnetically connected to the second magnetic member 15. Fixed core 30, movable core 22, first magnetic member 13, magnetic member 4
0, 42 and the second magnetic member 15 form a magnetic circuit. The spool 46 around which the coil 44 is wound is attached to the outer circumference of the tubular member 12. The terminal 48 is electrically connected to the coil 44 and supplies a drive current to the coil 44. The resin housing 50 covers the outer periphery of the tubular member 12 and the coil 44.

The fuel that has flowed into the fuel passage 100 from above the tubular member 12 in FIG. 1 is adjusted by the adjusting pipe 3.
6, a fuel passage in the fixed core 30, a fuel passage in the movable core 22, a fuel passage in the valve member 20, a fuel hole 2
0a, when the contact portion 21 is separated from the valve seat 18a, it passes through an opening formed between the contact portion 21 and the valve seat 18a, and is injected from the injection hole 19a. In the fuel injection device 10 configured as above, when the coil 44 is de-energized, the spring 24 causes the valve member 20 to move downward in FIG.
That is, the contact portion 21 of the valve member 20 is seated on the valve seat 18a by moving in the valve closing direction, the injection hole 19a is closed, and the fuel injection is blocked.

When the coil 44 is energized, the fixed core 30, the movable core 22, the first magnetic member 13, and the magnetic member 4 are turned on.
A magnetic flux flows through a magnetic circuit including 0, 42 and the second magnetic member 15, and a magnetic attraction force is generated between the fixed core 30 and the movable core 22. Then, the valve member 20 moves to the fixed core 30 side together with the movable core 22, and the contact portion 21 moves the valve seat 18
Move away from a. As a result, fuel is injected from the injection hole 19a. The maximum lift amount of the valve member 20 is the movable core 22.
Is fixed to the fixed core 30.

In the first embodiment, the fixed core 30 has a press-fitting portion 32 and an outer diameter smaller than that of the press-fitting portion 32 and is not in contact with the inner peripheral wall of the tubular member 12, and the valve member 20 reciprocates with respect to the press-fitting portion 32. The first small diameter portion 31 and the second portion that are located on both sides in the direction.
It has a small diameter portion 33. That is, the fixed core 30 is press-fitted into the inner peripheral wall of the tubular member 12 by the press-fitting portion 32 which is a part of the axial length in the press-fitting direction. Since the axial length of the fixed core 30 press-fitted into the tubular member 12 becomes short, the press-fitting force when press-fitting the fixed core 30 into the tubular member 12 becomes small. Therefore, the fixed core 30 can be easily press-fitted. Further, since the outer peripheral wall of the fixed core 30 which is easier to process than the inner peripheral wall is processed to form the press-fitting portion 32, the fixed core 30 can be processed easily.

The press-fitting portion 32 and the large-diameter portion 3 of the second magnetic member 15
Since the annular space 110 is formed between the outer peripheral wall of the small diameter portion 33 located between the inner peripheral wall and the inner peripheral wall of the second magnetic member 15, this occurs when the fixed core 30 is press-fitted into the tubular member 12. The press-fitting waste that remains remains in the space 110. Since the press-fitting waste is prevented from moving to the valve portion constituted by the valve seat 18a and the valve member 20, the press-fitting waste can be prevented from being caught in the valve portion.

(Second Embodiment) A second embodiment of the present invention is shown in FIG.
Shown in. The same reference numerals are given to substantially the same components as those in the first embodiment. The fixed core 80 is attached and fixed to the tubular member 70 by press fitting. The fixed core 80 locks the movable core 22 and defines the maximum lift amount of the valve member 20. Tubular member 7
The non-magnetic member 71 and the second magnetic member 74 forming 0 are joined by welding. The non-magnetic member 71 has a small diameter portion 72 and a connecting portion 73 that is connected to the connecting portion 75 of the second magnetic member 74 in this order from the injection hole side. The inner diameter of the connecting portion 73 is smaller than the inner diameter of the small diameter portion 72.

The second magnetic member 74 is connected to the connecting portion 73 of the non-magnetic member 71 from the non-magnetic member 71 side.
5, and the accommodating portion 76 having an inner diameter larger than that of the coupling portion 75 is provided in this order. Since the outer diameter of the fixed core 80 is equal to the reciprocating direction of the valve member 20, the fixed core 80 is fixed to the connecting portions 73, 7
In FIG. 5, the cylindrical member 70 is press-fitted. The thickness of the fixed core 80 at the portion press-fitted into the tubular member 70 is thicker than the thickness of the connecting portions 73, 75 into which the fixed core 80 is press-fitted.

In the above-mentioned plurality of embodiments of the present invention, the fixed core is attached and fixed to the tubular member by press fitting, so that the fixed core can be attached more easily than when the fixed core is attached to the tubular member by welding. is there. Further, since the position of the fixed core is determined by press fitting, the fixed core can be positioned with high accuracy. Since the maximum gap formed between the movable core and the fixed core can be determined with high precision, the magnetic attraction force acting between the fixed core and the movable core is prevented from varying from injector to injector. Therefore, it is easy to adjust the fuel injection amount for each injector.

Since the fixed core positioned with high precision locks the movable core, the maximum lift amount of the valve member is prevented from varying from injector to injector. Therefore, it is easy to adjust the fuel injection amount for each injector. Furthermore, since the fixed core also serves as the locking member that locks the movable core, the number of parts can be reduced. Since the valve member 20 is made hollow to reduce the weight in the above-described embodiments, the movable core 2
The impact that the fixed core receives when locking 2 is small. Therefore, the displacement of the fixed core can be prevented.

Further, in the above-described embodiments, the thickness of the fixed core is thicker than the thickness of the tubular member at the press-fitting position where the fixed core is attached to the tubular member, so that the tubular member is deformed instead of the fixed core. It is possible to prevent the magnetic attraction force acting between the fixed core and the movable core from changing due to the change in shape of the fixed core. In the present invention, it is possible to make the thickness of the fixed core equal to or thinner than the thickness of the tubular member at the press-fitting location where the fixed core is attached to the tubular member.

In the above-described embodiments, the fixed core also serves as the locking member for the movable core, but the movable core may be locked by a locking member that is positioned by the fixed core separately from the fixed core. Further, the movable core may be locked by a locking member that is positioned by a member different from the fixed core. Further, in the above-described embodiments, the tubular member is formed by joining the plurality of members to each other. However, by heating a part of the composite magnetic material to form the non-magnetic portion as the magnetic resistance member, the first magnetic portion is formed. , Non-magnetic part,
The second magnetic part may be integrally formed of a composite magnetic material.

[Brief description of drawings]

FIG. 1 is a sectional view showing an injector according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a press-fitting portion where a fixed core is fixed to a tubular member in the first embodiment.

FIG. 3 is a cross-sectional view showing a press-fitting portion where a fixed core is fixed to a tubular member in the second embodiment.

FIG. 4 is a sectional view showing a conventional injector.

[Explanation of symbols]

10 Fuel injection device 12,70 Cylindrical member 13 First magnetic member 14, 71 Non-magnetic material (magneto-resistive material) 15,74 Second magnetic member 18 valve body 18a valve seat 19 nozzle plate 19a injection hole 20 valve members 21 Contact part 22 Movable core 24 Spring (biasing member) 30,80 Fixed core 31 1st small diameter part 32 Press-fitting section 33 Second small diameter part 34 Large diameter part 44 coils

Claims (8)

[Claims] 1. A tubular member having a first magnetic member, a magnetoresistive member, and a second magnetic member in this order from the fuel injection side, and an injection hole provided on the first magnetic member side of the tubular member. And a valve body having a valve seat on the fuel upstream side, and a contact portion reciprocally housed in the tubular member and seatable on the valve seat, and the contact portion seats on the valve seat. A valve member that closes the injection hole and opens the injection hole by separating from the valve seat; and a movable core that is installed on the side opposite to the injection hole of the valve member and that reciprocates together with the valve member. A fixed core installed in the tubular member on the side opposite to the injection hole with respect to the movable core and facing the movable core; and a fixed core installed on the outer peripheral side of the tubular member and energized to move the movable core to the fixed core side. And a coil for generating a magnetic attraction force for attracting The fuel injection device, wherein the core is attached inside the tubular member by press fitting. 2. The fuel injection device according to claim 1, wherein the fixed core locks the movable core to define a lift amount of the valve member. 3. The fuel injection device according to claim 1, further comprising: a locking member that defines a lift amount of the valve member by locking the movable core and is positioned by the fixed core. 4. The fuel injection device according to claim 2, wherein the valve member is hollow. 5. The thickness of the fixed core is thicker than the thickness of the tubular member at a press-fitting location where the fixed core is attached to the tubular member. The fuel injection device described. 6. The fuel injection device according to claim 1, wherein the fixed core is press-fitted into the inner peripheral wall of the tubular member at a part of the axial length in the press-fitting direction. 7. The fixed core has a press-fitting portion press-fitted into the inner peripheral wall of the tubular member and an outer diameter smaller than that of the press-fitting portion, and is not in contact with the inner peripheral wall of the tubular member. The fuel injection device according to claim 6, further comprising a small diameter portion located in at least one of reciprocating directions of the valve member. 8. The fixed core has the small diameter portion on the side opposite to the press-fitting direction of the press-fitting portion, and has a larger diameter than the small diameter portion on the side opposite to the press-fitting direction of the small diameter portion and an inner peripheral wall of the tubular member. The fuel injection device according to claim 7, wherein the fuel injection device has a large diameter portion forming a minute gap.