JP2002048031A - Fuel injector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small fuel injector for shortening valve opening time and valve closing time and highly accurately controlling a fuel injection quantity. SOLUTION: In the reciprocating direction of a valve member 20, when the length of a coil 40 is La, a distance between a nozzle port side end surface of the coil 40 and a nozzle port side end surface of a nonmagnetic part 13 is Lb, a distance between the nozzle port side end surface of the coil 40 and a nozzle port side end surface of a fixed core 30 is Lc, the length of the nonmagnetic part 13 is Ld and the thickness of a second magnetic part 14 is Le, 5<=La<=10, 0<=Lb<=1.0, Lb<Lc, 0<=Lc<=1.0, 0.5<=Ld/La<=1.5 and 0.5<=Le<=2.0 are realized. Arrangement and the length of the nonmagnetic part 13, a movable core 22, the fixed core 30 and the coil 40 are adjusted to shorten valve opening time and valve closing time of the fuel injector.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electromagnetic fuel injection device for an internal combustion engine (hereinafter referred to as an engine).

[0002]

2. Description of the Related Art In an electromagnetic fuel injection device, it is desirable that the fuel injection amount can be controlled in proportion to the length of a pulse signal applied to a coil from an engine control device or the like. For that purpose, it is required that the injection rate characteristics of the fuel injection device approach the pulse waveform applied to the coil. That is, it is necessary to shorten the valve opening time of the fuel injection device when energization of the coil is turned on, and to shorten the valve closing time of the fuel injection device when energization of the coil is turned off.

If the magnetic attraction force for attracting the movable core reciprocating with the valve member to the fixed core side is increased, the valve opening speed is increased and the valve opening time is shortened. However, when the number of turns of the coil is increased to increase the magnetic attraction, there is a problem that the fuel injection device becomes large.

When the spring load for urging the valve member in the valve closing direction is increased, the valve closing speed is increased and the valve closing time is shortened. However, when the spring load is increased, there is a problem that the valve opening speed of the movable core and the valve member sucked toward the fixed core side against the spring load decreases.

[0005]

Problems to be Solved by the Invention Japanese Patent Application Laid-Open No. H11-1484
In the fuel injection valve disclosed in Japanese Patent Publication No. 37, the magnetic attraction force is increased by adjusting the arrangement of the movable core, the fixed core, and the coil without increasing the number of turns of the coil and without increasing the size of the fuel injection valve. Attempts to increase valve opening speed and shorten valve opening time.

However, when the magnetic attraction force increases, the time for which the magnetic attraction force decreases when the power supply to the coil is turned off becomes longer. That is, the valve closing time becomes longer. As described above, increasing the spring load increases the valve closing speed and shortens the valve closing time. However, as described above, when the spring load is increased, it is necessary to increase the magnetic attraction force to attract the movable core against the spring load.
It is difficult to increase the valve opening speed because a part of the magnetic attraction increased by adjusting the arrangement of the movable core, the fixed core and the coil is used to offset the increase in the spring load.

When the valve opening time or the valve closing time becomes longer, the characteristics of the fuel injection rate and the drive signal applied to the coil, for example, the signal width of the pulse signal are not proportional, and the fuel injection amount increases and decreases. Becomes difficult. In particular, when the drive signal width applied to the coil is short, such as during idle operation, it becomes difficult to control the fuel injection amount. Therefore, in order to secure a required amount of fuel injection, the drive signal width is increased and fuel is excessively injected. As a result, fuel efficiency is reduced and harmful substances contained in exhaust gas are increased. An object of the present invention is to provide a small-sized fuel injection device that shortens a valve opening time and a valve closing time and controls a fuel injection amount with high accuracy.

[0008]

According to the fuel injection device of the present invention, in the reciprocating direction of the valve member, the length of the coil is La, the end face of the coil on the side of the injection hole and the injection of the magnetic resistance portion. Assuming that the distance from the hole-side end surface is Lb, the distance between the nozzle-hole-side end surface of the coil and the nozzle-hole-side end surface of the fixed core is Lc, and the length of the magnetic resistance portion is Ld, 5 ≦ La ≦ 10 and 0 ≦ Lb ≦
1.0 and Lb <Lc and 0.5 ≦ Ld / La ≦ 1.5
It is.

Since 0.5.ltoreq.Ld / La.ltoreq.1.5, the length of the magnetoresistive portion located in the coil is longer than half of the coil length. With this configuration, the inductance of the coil is reduced, so that when the power supply to the coil is turned on, the value of the current flowing through the coil rapidly increases, and the valve member separates from the valve seat. Further, when the power supply to the coil is turned off, the value of the current flowing through the coil rapidly decreases, so that the valve member quickly sits on the valve seat without increasing the urging force of the urging means. Furthermore, since the coil length is shortened, the length of the magnetic circuit surrounding the coil is shortened and the magnetic loss is small. The value of the current flowing through the coil rapidly increases, and the current flowing through the coil rapidly decreases.

When the valve opening time and valve closing time of the fuel injection device become short, the characteristic of the fuel injection rate approaches the waveform of the drive signal applied to the coil, so that the signal width of the drive signal and the fuel injection amount are almost proportional. In addition, the fuel injection amount can be controlled with high accuracy. In particular, when the fuel injection amount is small as in the idle operation, it is not necessary to inject the fuel excessively. Therefore, fuel efficiency is improved and the amount of harmful substances contained in the exhaust gas is reduced.

According to the second aspect of the present invention, since 0 ≦ Lc ≦ 1.0 is set, the air between the fixed core and the movable core for which it is desired to increase the magnetic flux density and increase the magnetic attraction force. The gap position approaches the end of the coil on the injection hole side. With this configuration, the inductance of the coil is reduced, so that the value of the current flowing through the coil rapidly increases, and the value of the current flowing through the coil rapidly decreases. Therefore, the valve opening time and the valve closing time of the fuel injection device are shortened.

[0012]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of the present invention. FIG. 2 shows a fuel injection device according to one embodiment of the present invention. The valve housing 11 is formed in a cylindrical shape including a magnetic part and a non-magnetic part, and is formed of, for example, a composite magnetic material. A fuel passage 50 is formed in the valve housing 11.
A valve body 15, a valve member 20, a spring 25 as a biasing means, a fixed core 30, an adjusting pipe 31,
A filter 39 is housed.

The valve housing 11 is formed integrally with a first magnetic part 12, a non-magnetic part 13 as a magnetic resistance part, and a second magnetic part 14 in this order from the lower fuel injection side in FIG. The first magnetic part 12 and the second magnetic part 14 are magnetized, and the non-magnetic part 13 heats a part of the valve housing 11 to be non-magnetic. The non-magnetic part 13 is the first magnetic part 1
A short circuit of magnetic flux between the second magnetic section 14 and the second magnetic section 14 is prevented. As shown in FIG. 1, a valve body 15 and an injection hole plate 16 are housed inside the injection hole side of the first magnetic portion 12.

The cup-shaped injection hole plate 16 is fixed to the outer peripheral wall of the valve body 15 together with the cup-shaped support member 17 by laser welding, and is sandwiched between the valve body 15 and the support member 17. The injection hole plate 16 is formed in a thin plate shape, and has a plurality of injection holes 16a in the center.

The valve member 20 is formed in a cylindrical shape with a bottom, and a contact portion 21 is formed on the bottom side of the valve member 20.
The contact portion 21 can be seated on a valve seat 15 a formed on the inner peripheral wall of the valve body 15. When the contact portion 21 is seated on the valve seat 15a, the injection hole 16a is closed and fuel injection is shut off. A movable core 22 is fixed to the valve member 20 on the side opposite to the injection hole by laser welding or the like. A plurality of fuel holes 20 a penetrating the side wall of the valve member 20 are formed on the upstream side of the contact portion 21. The fuel that has flowed into the valve member 20 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 15a.

The fixed core 30 is formed in a cylindrical shape.
Housed inside the non-magnetic portion 13 and the second magnetic portion 14,
The movable core 22 faces the movable core 22 on the side opposite to the injection hole. The adjusting pipe 31 is pressed into the fixed core 30. One end of the spring 25 as the urging means is locked by the adjusting pipe 31, and the other end is locked by the movable core 22. The load on the spring 25 can be changed by adjusting the amount of press-fit of the adjusting pipe 31. Spring 25 is valve seat 15
The valve member 20 is biased toward “a”.

The magnetic members 35 and 36 are arranged on the outer peripheral side of the coil 40, and respectively have the first magnetic portion 12 and the second magnetic portion 14.
And is in contact with. Fixed core 30, movable core 22, first
Magnetic part 12, second magnetic part 14, and magnetic members 35 and 36
Constitutes a magnetic circuit. The filter 39 is mounted on the upstream side of the valve housing 11 in FIG. 2 and removes foreign matter in the fuel.

The spool 41 around which the coil 40 is wound is mounted on the outer periphery of the valve housing 11. The resin-molded connector 45 includes the coil 40 and the spool 41.
The outer circumference is covered. The terminal 46 is embedded in the connector 45 and is electrically connected to the coil 40.
Fuel flowing into the fuel passage 50 of the valve housing 11 through the filter 39 is supplied to the fuel passage in the adjusting pipe 31, the fuel passage in the fixed core 30, the fuel passage in the valve member 20, the fuel hole 20 a, the contact portion 21. Is ejected from the injection hole 16a through an opening formed between the contact portion 21 and the valve seat 15a when the user separates from the valve seat 15a.

In the fuel injection device 10 configured as described above, when the power to the coil 40 is turned off, the spring 25 moves the valve member 20 downward in FIG. The contact portion 21 is seated on the valve seat 15a, the injection hole 16a is closed, and the fuel injection is shut off.

When energization of the coil 40 is turned on, the magnetic flux generated in the coil 40 flows through a magnetic circuit surrounding the coil 40, and a magnetic attraction is generated between the fixed core 30 and the movable core 22. Then, the valve member 20 is fixed to the fixed core 30.
The contact portion 21 is separated from the valve seat 15a.
Thereby, fuel is injected from the injection hole.

Next, the position where the non-magnetic portion 13, the movable core 22, the fixed core 30, and the coil 40 are disposed and the set value of the length will be described. In the reciprocating direction of the valve member 20, the length of the coil 40 is La, the distance between the injection hole side end surface of the coil 40 and the injection hole side end surface of the non-magnetic portion 13 is Lb, and the injection hole side end surface of the coil 40 and the fixed core. Assuming that the distance from the injection hole side end face 30 to Lc, the length of the non-magnetic portion 13 is Ld, and the thickness of the fixed core 30 is Le, 5 ≦ La ≦ 10 and 0 ≦ Lb ≦
1.0 and Lb <Lc and 0 ≦ Lc ≦ 1.0 and 0.5
≦ Ld / La ≦ 1.5 and 0.5 ≦ Le ≦ 2.0.

By setting 0.5 ≦ Ld / La ≦ 1.5, the length of the non-magnetic portion 13 in the coil 40 is increased, so that the inductance of the coil 40 is small. Therefore, as shown in FIGS. 3 and 4, when the pulse signal applied to the coil 40 is turned on, the value of the current flowing through the coil 40 and the attraction force increase quickly, and the valve opening time is shortened. When the pulse signal applied to the coil 40 is turned off, the value of the current flowing through the coil 40 and the attraction force decrease quickly, and the valve closing time is shortened. Furthermore, since the valve closing time is shortened and the arc extinguishing energy is reduced, the power consumption of the drive circuit can be reduced, and the engine can be used up to a high rotation range.

Since the length of the coil 40 is shortened by setting 5 ≦ La ≦ 10, the length of the magnetic circuit is shortened and the magnetic loss is reduced. With this configuration, the value of the current flowing through the coil 40 and the attraction force increase quickly and decrease quickly. Further, by setting 0 ≦ Lc ≦ 1.0, the position of the air gap between the movable core 22 and the fixed core 30 whose magnetic flux density is to be increased is made as close to the end of the coil 40 as possible. Since the inductance of the coil 40 is reduced, the value of the current flowing through the coil 40 and the attraction force increase quickly and decrease rapidly.

When the value of the current flowing through the coil 40 and the attraction force increase rapidly and decrease rapidly, the fuel injection device 1
Since the valve opening time and the valve closing time of 0 become shorter, the characteristic of the fuel injection rate of the fuel injection device 10 approaches the waveform of the pulse signal applied to the coil 40. Therefore, the pulse time applied to the coil 40 is approximately proportional to the fuel injection amount, and the injection amount control can be performed with high accuracy. In particular, when the fuel injection amount is small as in the idle operation, it is not necessary to inject the fuel excessively. Therefore, fuel efficiency is improved and the amount of harmful substances contained in the exhaust gas is reduced. Of the above settings,
Even if 0 ≦ Lc ≦ 1.0 and 0.5 ≦ Le ≦ 2.0 are not satisfied, the valve opening time and valve closing time of the fuel injection device can be reduced.

In the above-described embodiment of the present invention, the valve opening time is shortened by adjusting the arrangement of the non-magnetic portion 13, the movable core 22, the fixed core 30, and the coil 40.
Further, the valve closing time is shortened without increasing the urging force of the spring. Further, since the biasing force of the spring is not increased, and it is not necessary to increase the magnetic attraction force by increasing the number of turns of the coil in order to resist the biasing force of the spring, the fuel injection device can be downsized. In this embodiment, a part of the composite magnetic material is heated to form the non-magnetic portion 13 as the magnetic resistance portion. Alternatively, the magnetic resistance may be formed by reducing the thickness of the magnetic material.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view showing a periphery of a coil of a fuel injection device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing the fuel injection device according to the embodiment.

FIG. 3 is a characteristic diagram showing a relationship between a pulse signal and a coil current.

FIG. 4 is a characteristic diagram showing a relationship between a pulse signal and a suction force.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Fuel injection device 11 Valve housing (valve body) 12 1st magnetic part 13 Non-magnetic part (magnetic resistance part) 14 2nd magnetic part 15 Valve body 15a Valve seat 16 Injection plate 16a Injection hole 20 Valve member 21 Contact part 22 Movable core 25 Spring (biasing means) 30 Fixed core 40 Coil

Continued on the front page (72) Inventor Yoshinori Yamashita 1-1-1, Showa-cho, Kariya-shi, Aichi F-term in DENSO Corporation (reference) 3G066 BA06 BA09 BA17 BA19 BA26 BA67 CC06U CC14 CC20 CC24 CC26 CC51 CD30 CE23 CE24 CE25 CE26 DB07

Claims (2)

[Claims] 1. A cylindrical member having a first magnetic portion, a magnetic resistance portion, and a second magnetic portion in this order from a fuel injection side, and an injection hole disposed on the first magnetic portion side of the cylindrical member. A valve body having a valve seat on the fuel upstream side of the fuel cell; and a contact portion accommodated in the cylindrical member so as to be able to reciprocate and seat on the valve seat, and the contact portion is seated on the valve seat. A valve member that closes the injection hole and opens the injection hole by moving away from the valve seat; and a movable core that is disposed on the side opposite to the injection hole of the valve member and reciprocates with the valve member. A fixed core disposed in the cylinder member on the side opposite to the injection hole of the movable core so as to face the movable core; an urging means for urging the valve member toward the valve seat; and an outer periphery of the cylinder member And a magnetic force that attracts the movable core to the fixed core side when energized. In the reciprocating movement direction of the valve member, the length of the coil is La, the distance between the injection hole side end surface of the coil and the injection hole side end surface of the magnetic resistance portion is Lb, Assuming that the distance between the injection hole side end face and the injection hole side end face of the fixed core is Lc, and the length of the magnetic resistance portion is Ld, 5 ≦ La ≦ 10 and 0 ≦ Lb
≦ 1.0 and Lb <Lc and 0.5 ≦ Ld / La ≦ 1.
5. The fuel injection device according to item 5, wherein 2. The fixed core is formed in a cylindrical shape,
When the thickness of the fixed core is Le, 0.5 ≦ Le ≦
2. The fuel injection device according to claim 1, wherein 2.0 and 0 ≦ Lc ≦ 1.0.