JP2000205080A - Injector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the size and power consumption of and improve the durability of injectors by using the magnetostrictive effect of a super-magnetostrictive material in opening and closing their nozzle. SOLUTION: A housing 14 having a nozzle 12 for fuel injection houses in its hollow a spool-shaped guide 16. The guide 16 is wound with an excitation coil 18 by a preset turn on its hollow cylinder portion 16a. In an axial bore 16c of the hollow cylinder portion 16a of the guide 16 is inserted a needle 22 consisting of a round driving rod 24 of a super-magnetostrictive material and a valve 26 located at the nozzle-pointing front end of the driving rod 24 to open and close the nozzle 12. The driving rod 24 has at the back end an externally threaded portion 24a that is meshed with an internally threaded portion 14a cut in the related back of the housing 14 to thus fix the back end of the needle 22 to the back end of the housing 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injector used for a high-pressure fuel injection device of an automobile engine, for example.

[0002]

2. Description of the Related Art In-cylinder direct injection of fuel has attracted attention as an effective method for improving fuel efficiency and purifying exhaust gas of automobile engines. In an injector of a fuel injection device used for this injection method, an excitation coil is provided inside a housing, and a needle is slidably provided inside the housing. The needle is always held at a closed position where the tip of the fuel injection nozzle formed on the housing is closed by the elastic force of the compression spring.
Then, by passing a current through the coil, the needle is magnetically attracted in a direction away from the nozzle against the elasticity of the compression spring, and the nozzle is opened.

[0003]

In order to effectively and completely burn a lean fuel mixture by the in-cylinder direct injection method, it is required to spray fuel into ultrafine particles. It is set to inject fuel at high pressure. Incidentally, the fuel injection pressure of the conventional in-cylinder fuel injection method reaches 3 atm, whereas the fuel injection pressure of the in-cylinder direct injection method reaches 100 to 120 atm. And
Such a high-pressure fuel injection device has a high magnetic attraction force and excellent magnetic responsiveness as a magnetic circuit for driving and controlling a needle for opening and closing a fuel injection nozzle in an injector so as to support high-pressure injection. Is needed. Therefore, magnetic attraction and magnetic responsiveness have been improved by increasing the number of turns of the coil or increasing the value of the current flowing through the coil.However, in this case, it has been pointed out that the injector becomes large and power consumption increases. You.

Further, in the injector, a compression spring is used to close the nozzle with a needle,
The spring must also be able to withstand high pressure, causing an increase in size and cost. Moreover, since the compression spring is used under high pressure, it is pointed out that the life of the compression spring is reduced and the durability of the injector itself is reduced.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned drawbacks inherent in the prior art, and has been proposed in order to solve the problem suitably. Accordingly, it is an object of the present invention to provide an injector that can be reduced in size and consume less power, and can also improve durability.

[0006]

SUMMARY OF THE INVENTION In order to overcome the above-mentioned problems and appropriately attain the initial purpose, an injector according to the present invention comprises a hollow housing having a nozzle formed at one end in an axial direction, and an interior of the housing. A drive rod made of a giant magnetostrictive material having one end fixed to the housing and separated from the nozzle and provided with a valve for opening and closing the nozzle at the other end, and disposed in the housing so as to surround the drive rod. And the nozzle is opened and closed by expansion and contraction of the driving rod in accordance with a magnetic field generated by passing a current through the coil.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an injector according to the present invention will be described in detail with reference to the accompanying drawings by way of preferred embodiments.

FIG. 1 is a sectional view showing a schematic configuration of an injector according to an embodiment.
A spool-shaped guide 16 is arranged concentrically inside a hollow interior of a housing 14 made of electromagnetic stainless steel having a fuel injection nozzle 12 formed at one axial end (front end). The guide 16 has flanges 16b protruding radially outward at a predetermined length at both axial ends of the hollow cylindrical portion 16a, and is formed of a nonmagnetic synthetic resin as a material. The exciting coil 18 is wound around the outer circumference of the hollow cylindrical portion 16a by a required number of turns.

The inner peripheral surface of the housing 14 is located at a position separated from the rear end opposite to the front end where the nozzle 12 is formed by a predetermined distance, and a restricting portion 20 projecting inside the housing 14 by a predetermined length.
The guide 16 is disposed between the restricting portion 20 and the rear end of the housing 14 in a sandwiched state. The protruding length of the restricting portion 20 is centered on a needle 22 to be described later.
Is set to a value at which a through hole that allows the insertion of a through hole is formed.

A guide 1 is provided inside the housing 14.
6 in the axial hole 16c in the hollow cylindrical portion 16a, the longitudinal direction
The needle 22 is inserted in a state in which expansion and contraction (in the axial direction of the housing 14) is allowed. The needle 22 includes a driving rod 24 made of a giant magnetostrictive material and having a round bar shape.
A valve 26 disposed at the front end (the other end) of the nozzle 12 in the longitudinal direction of the nozzle to open and close the nozzle 12
It is composed of A male screw portion 24a is formed at the rear end (one end) of the drive rod 24 in the longitudinal direction, and the male screw portion 24a is screwed into a female screw portion 14a formed corresponding to the rear portion of the housing 14. The rear end of the needle 22 is fixed to the rear end of the housing 14. A magnetic circuit is formed by the coil 18, the housing 14, and the driving rod 24, and the driving rod 24 is configured to expand and contract in the longitudinal direction in response to a magnetic field generated by applying a current to the coil 18.

In the needle 22 of the embodiment, the valve 26 is set so as to be separated from the nozzle 12 and opened when no magnetic field is applied (the state shown in FIG. 1). And
When a magnetic field is applied to the drive rod 24, the drive rod 24 having a rear end fixed to the housing 14 is elongated in the longitudinal direction by the magnetostrictive action of the giant magnetostrictive material, and the valve 26 is moved to the nozzle 1
2, the nozzle 12 is closed.

As the giant magnetostrictive material constituting the driving rod 24, a Tb _x Dy _{1 -x} Fe ₂ alloy (x is 0.1 to 0.9) or Tb _x S, which has a high response and a large magnetostriction in a low magnetic field range, is used.
m _1-x Fe ₂ alloy (x is 0.1 to 0.9) is preferably used,
A giant magnetostrictive alloy such as a Tb-Fe alloy having another composition may be employed. The material of the valve 26 is SUS44
0C is preferably used.

As shown in FIG. 1, the drive rod 24 is provided with a fuel supply through-hole 24b whose one end is open at the rear end. The other end of the through-hole 24b is The nozzle 12 which is defined between the
Is open at the position of the space S communicating with. Further, a through hole 14b communicating with the through hole 24b of the drive rod 24 is formed in the rear portion of the housing 14, and fuel supplied from a fuel pump (not shown) is supplied to the space S through the two through holes 14b, 24b. It is being supplied. That is, when the nozzle 12 is opened by the needle 22, the space S
Is injected at a high pressure to the outside through the nozzle 12.

In the injector 10 having the above-described configuration,
By supplying a predetermined pulse current to the coil 18 while supplying high pressure fuel from the fuel pump to the injector 10, the drive rod 24 is moved in the longitudinal direction in accordance with the magnetic field applied to the drive rod 24. To expand and contract. Thus, when the valve 26 opens the nozzle 12, the fuel is
From the high pressure, and when closed, the fuel injection stops.

That is, the drive rod 24 made of a giant magnetostrictive material
The opening and closing of the nozzle 12 is performed by expansion and contraction (magnetostriction effect) caused by applying a magnetic field to the coil 18. There is no need to increase the number of turns or increase the current value, and the injector 10 can be reduced in size and power consumption can be reduced. In addition, since no compression spring is used, the number of components can be reduced to simplify the structure, and the durability of the compression spring due to its service life does not decrease. That is, the injector 10 of the embodiment can be suitably adopted as an injector of a high-pressure fuel injection device that is required to spray fuel into ultrafine particles.

[0016]

[Test Example] A Tb _0.9 Sm _0.1 Fe ₂ alloy with a diameter of 8 mm and a length of 1 which is almost the same as the specification actually used.
A test device was manufactured in which a drive rod 24 of 00 mm was formed, and a coil 18 of 1200 turns was wound around the drive rod 24 with a slight gap. Then, 14V is applied to the coil 18.
A pulse current of × 1 A (at the peak) was passed. As a result, as shown in the graph of FIG.
An elongation of μm was obtained. That is, the moving length of the valve 26 required for opening and closing the nozzle 12 in the injector 10 is about 10 μm, and the drive rod 24 made of Tb _0.9 Sm _0.1 Fe ₂ alloy can be sufficiently used as a drive source of the valve 26. It was confirmed that there was. In addition, it has been confirmed that the current value flowing through the coil 18 is small, and that power consumption can be reduced.

In the embodiment, the injector for injecting fuel at a high pressure has been described. However, the injector using the expansion / contraction based on the magnetostriction of a driving rod made of a giant magnetostrictive material as a driving source is a conventional injector of a direct injection method. Can also be used. In this case, since a compression spring is not used, the number of parts can be reduced, the structure can be simplified, and an advantage that cost can be reduced can be expected.

[0018]

As described above, according to the injector of the present invention, the nozzle is opened and closed by expansion and contraction caused by applying a magnetic field to the driving rod made of giant magnetostrictive material. It is not necessary to increase the number of turns of the coil or increase the value of the current flowing through the coil in order to enhance the magnetic responsiveness, so that the injector can be downsized and the power consumption can be reduced. In addition, since no compression spring is used, the number of components can be reduced to simplify the structure, and the durability of the compression spring due to its service life does not decrease. That is, the injector of the present invention can be suitably used as an injector of a high-pressure fuel injection device particularly required to spray fuel into ultrafine particles.

[Brief description of the drawings]

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

FIG. 2 is a graph showing the results of a test example.

[Explanation of symbols]

 12 Nozzle 14 Housing 18 Coil 24 Drive rod 26 Valve

Claims (2)

[Claims] 1. A hollow housing (14) in which a nozzle (12) is formed at one end in an axial direction, and inside the housing (14),
A drive rod (24) made of a giant magnetostrictive material, having one end spaced from the nozzle (12) fixed to the housing (14) and having a valve (26) provided at the other end for opening and closing the nozzle (12). , The drive rod (24)
Coil (18) disposed in the housing (14) so as to surround the
An injector configured to open and close the nozzle (12) by expansion and contraction of the drive rod (24) in response to a magnetic field generated by applying a current to the coil (18). Wherein said super magnetostrictive _{material, Tb x Dy 1-x Fe} 2 alloy (x = 0.1 to 0.9) or Tb _x Sm _1-x Fe ₂ alloy (x = 0.1
2. The injector according to claim 1, wherein