JPH07259690A - Super magneto-striction type actuator - Google Patents

Abstract

PURPOSE:To prevent the displacement amount of a driving object from changing even if a super magneto-striction shaft or a shaft holder is thermally expanded by an increase in a circumferential temperature. CONSTITUTION:A shaft holder 11 for housing a super magneto-striction shaft 10 is formed by a first holder cylinder 12 whose flange part 12A on its low end side is fixed to a casing 1, and a second holder cylinder 13 which is formed of a material whose thermal expansion rate is different from that of the holder cylinder 12, and whose an upper end side is formed as an engaging part 13A engaged with the top end side end surface 10A of the super magneto-striction shaft 10, the holder cylinders 12, 13 are joined together in axial direction, and both holder cylinders 12, 13 are integrated with each other. Each material and length size of the holder cylinders 12, 13 are selected appropriately, so that thermal expansion of the whole shaft holder 11 is made to approach the thermal expansion of the super magneto-striction shaft 10. It is thus possible to prevent the lift amount of a valve body 5 from changing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a giant magnetostrictive actuator suitable for use in, for example, a giant magnetostrictive injection valve, an on-off valve and the like, and more particularly to a giant magnetostrictive actuator for preventing characteristic changes due to thermal expansion. .

[0002]

2. Description of the Related Art Generally, in order to drive a tubular casing and an object to be driven provided on one end side of the casing, the casing is extended in the axial direction in the casing, and one end side is attached to the object to be driven. A supermagnetostrictive shaft, and an electromagnetic coil which is provided in the casing around the supermagnetostrictive shaft and which expands and contracts the supermagnetostrictive shaft in the axial direction by applying a magnetic field to the supermagnetostrictive shaft. A fuel injection valve using a magnetostrictive actuator is known, for example, from Japanese Patent Application Laid-Open No. 3-243174.

In this type of prior art fuel injection valve,
A valve seat having a fuel injection port is provided on one end side of the casing, and the valve body is configured by a valve spring so that the valve seat, which is an inward-opening type or an outward-opening type, is separated from and seated on the valve seat. While normally energizing in the valve closing direction, one end side of the giant magnetostrictive shaft is fixed to the valve body, and when the giant magnetostrictive shaft is contracted or expanded by the magnetic field from the electromagnetic coil, the giant magnetostrictive shaft causes the valve body to move. The valve spring is lifted against the valve spring to inject the fuel in the casing from the injection port to the outside.

Further, in the externally opened type fuel injection valve, a lid body that abuts on the other end side end surface of the super magnetostrictive shaft is provided on the other end side of the casing, and the supermagnetostrictive shaft is valved together with the valve body by the lid body. The spring load of the valve spring is adjusted by pressing it toward the seat side. When the giant magnetostrictive shaft is stretched and deformed by the magnetic field from the electromagnetic coil, the other end of the giant magnetostrictive shaft is restricted from being displaced toward the lid side, and the one end is displaced against the valve spring. The valve body can be reliably lifted from the valve seat against the valve spring.

[0005]

By the way, in the above-mentioned fuel injection valve of the outside open type according to the prior art, a valve body to be driven is provided on one end side of the casing, and a lid body is provided on the other end side of the casing. Since the giant magnetostrictive shaft is positioned in the casing between the lid and the valve body, when the electromagnetic coil provided around the giant magnetostrictive shaft generates heat due to external power supply, the heat generated at this time is generated. The giant magnetostrictive shaft may thermally expand in the axial direction between the lid body and the valve body due to influence or the like. Further, in this case, since the lid body is integrally fixed to the casing, the giant magnetostrictive shaft extends toward the valve body side during thermal expansion, and thermal expansion of the giant magnetostrictive shaft causes the valve body to open in the valve opening direction. There is a problem in that it may be displaced and separated from the valve seat, causing a defective seal or the like.

[0006] Therefore, the present applicant previously filed Japanese Patent Application No. 4-14.
In No. 3175 (hereinafter referred to as prior art), etc., a shaft holder (stopper cylinder) having a lid shape is provided between the giant magnetostrictive shaft and the electromagnetic coil, and the opening side of the shaft holder is fixed to one end side of the casing. , A giant magnetostrictive actuator having a structure in which the lid of the shaft holder is engaged with the other end of the giant magnetostrictive shaft and can be thermally expanded toward the other end of the casing.

In the giant magnetostrictive actuator according to this prior art, the shaft holder is made of a non-magnetic material having a coefficient of thermal expansion corresponding to the coefficient of thermal expansion of the giant magnetostrictive shaft, and is formed into a tubular shape. The size corresponds to the entire length of the giant magnetostrictive shaft, and the giant magnetostrictive shaft is positioned in the shaft holder in a state where the lid portion is engaged with the end face of the other end of the giant magnetostrictive shaft. As a result, when the giant magnetostrictive shaft thermally expands, the tubular portion of the shaft holder also thermally expands, so that the thermal expansion component of the giant magnetostrictive shaft can be absorbed and offset on the lid side of the shaft holder.

However, in this prior art, the shaft holder is made of a single material (member), and the coefficient of thermal expansion of the shaft holder is made to correspond to the coefficient of thermal expansion of the giant magnetostrictive shaft. There is an unsolved problem that it is difficult to match the thermal expansions of the shaft holder and the giant magnetostrictive shaft because the choices (selection widths) of the materials constituting the are greatly limited.

Further, when the shaft holder thermally expands before the giant magnetostrictive shaft due to the heat from the electromagnetic coil, the lid portion of the shaft holder separates from the other end side of the giant magnetostrictive shaft, and the giant magnetostrictive shaft. When the valve is driven by the magnetic field from the electromagnetic coil, the lift amount of the valve element may decrease.

The present invention has been made in view of the above-mentioned problems of the prior art. The present invention can greatly expand the choices of the material forming the shaft holder, and the shaft holder and the giant magnetostrictive shaft can be operated together with the increase in ambient temperature. It is an object of the present invention to provide a giant magnetostrictive actuator capable of preventing the displacement amount of a driven object from changing even if it thermally expands.

[0011]

In order to solve the above-mentioned problems, the structure adopted by the invention according to claim 1 is a cylindrical casing and a magnetic field provided in the casing extending in the axial direction. A super-magnetostrictive shaft that expands and contracts by the action of, a drive target that is displaceably provided on one end side of the casing so as to be axially driven by the super-magnetostrictive shaft, and a super-magnetostrictive shaft in the casing. A shaft holder that extends in the axial direction for positioning, one end side is fixed to the casing, and the other end side is engaged with the other end side of the giant magnetostrictive shaft, and is provided between the shaft holder and the casing. An electromagnetic coil that applies a magnetic field to the magnetostrictive shaft is provided, and the shaft holder absorbs displacement due to thermal expansion of the giant magnetostrictive shaft.
It is configured by combining a plurality of members having different thermal expansion coefficients.

In this case, as in the second aspect of the present invention, the shaft holder has a first holder cylinder fixed to the casing with one end side being an open end and one end side being the first holder cylinder. It is preferable that the second holder cylinder is joined to the other end side of the above, and the other end side becomes a closed end and is engaged with the other end side of the giant magnetostrictive shaft by a second member having a different coefficient of thermal expansion.

According to a third aspect of the present invention, the shaft holder has an engaging portion at one end that is a fixing portion fixed to the casing and at the other end that engages with the other end of the giant magnetostrictive shaft. Is formed of a material having a coefficient of thermal expansion smaller than that of the first holder member, one end side of which is a fixing portion fixed to the casing, and the other end side of which is the first holder member. The second holder member may be a stopper portion that comes into contact with the engaging portion from the outside.

Further, as in the invention of claim 4, a flow path of a pressurized fluid is formed between the casing and the giant magnetostrictive shaft, and the object to be driven is moved to the casing in order to discharge the fluid out of the casing. You may comprise by the valve body of an open type which protrudes outside.

[0015]

With the above construction, in the invention described in claim 1,
Since the shaft holder can be configured by combining a member having a larger coefficient of thermal expansion and a member having a smaller coefficient of thermal expansion than the giant magnetostrictive shaft, the thermal expansion of the entire shaft holder can be easily matched with the thermal expansion of the giant magnetostrictive shaft. This makes it possible to select the material of each member constituting the shaft holder with a relatively large selection. When the giant magnetostrictive shaft thermally expands in the axial direction, the shaft holder also thermally expands in the same manner. Therefore, the axial displacement due to the thermal expansion of the giant magnetostrictive shaft can be offset by the thermal expansion of the shaft holder. it can.

In this case, according to the second aspect of the invention, since the first and second holder cylinders are joined together in the axial direction, the thermal expansion of the respective materials forming the first and second holder cylinders. By selecting the length dimension of each holder cylinder according to the ratio, the thermal expansion of the entire shaft holder can be adjusted appropriately, and the thermal expansion of the giant magnetostrictive shaft can be accommodated.

According to the third aspect of the present invention, the first holder member is made of a material having a coefficient of thermal expansion larger than that of the giant magnetostrictive shaft, and the second holder member has a coefficient of thermal expansion greater than that of the giant magnetostrictive shaft. By forming with a small material, the thermal expansion of the first holder member can be regulated by the second holder member, and the thermal expansion of the entire shaft holder can be suppressed between the first holder member and the second holder member. It can be set to an intermediate value of thermal expansion, and can correspond to the thermal expansion of the giant magnetostrictive shaft.

Further, according to the invention of claim 4,
It becomes possible to cool the electromagnetic coil, the shaft holder and the giant magnetostrictive shaft together with the casing by circulating a pressurized fluid in the casing, and it is possible to suppress the thermal expansion of the shaft holder and the giant magnetostrictive shaft to be small, It is possible to open the outward-opening valve body, which is an object to be driven, with a substantially constant lift amount, and reliably prevent the injection amount of the pressurized fluid from fluctuating.

[0019]

Embodiments of the present invention will be described below with reference to FIGS. 1 to 9 by taking a giant magnetostrictive injection valve as an example.

First, FIGS. 1 to 4 show a first embodiment of the present invention.

In the figure, reference numeral 1 denotes a cylindrical casing formed of a magnetic material such as electromagnetic stainless steel in a stepped cylindrical shape, and the casing 1 has caulked portions 1 at both upper and lower ends thereof.
A and 1B are provided, and an annular protrusion 1C is provided on the inner peripheral side and is located above the caulking portion 1B by a predetermined dimension.
Further, an annular step portion 1D is formed on the inner periphery of the upper end side of the casing 1 so as to be located below the caulking portion 1A by a predetermined dimension, and the annular step portion 1D is formed between the caulking portion 1A and a seal retainer described later. 19 is positioned with the lid 17. Further, the casing 1 is located between the annular protrusion 1C and the annular step portion 1D, and the fuel flow holes 1E, 1E, ...
Are pierced in the radial direction, and the respective circulation holes 1E are adapted to allow the fuel as a pressurized fluid to flow in the casing 1 from a fuel pump (none of which is shown) via a fuel pipe or the like.

Reference numeral 2 denotes a bottomed cylindrical valve guide which is a part of the casing 1 and is provided on the inner peripheral side of the lower portion of the casing 1. The valve guide 2 has an outer diameter corresponding to the inner diameter of the casing 1. Spacer cylinder 3 formed into a cylindrical shape
And a valve seat member 4, which will be described later, provided on the lower end side of the spacer cylinder 3.

Reference numeral 4 denotes a valve seat member provided on the lower end side of the casing 1, and a cylindrical protrusion 4 is provided at the center of the upper side of the valve seat member 4.
A is integrally formed, and the inner peripheral side of the cylindrical protrusion 4A is a stepped valve shaft insertion hole 4B that extends in the axial direction. Also,
Fuel inflow holes 4C, 4C, ... Are bored obliquely downward from the radially outer side toward the inside of the valve shaft insertion hole 4B in the cylindrical protrusion 4A, and the fuel from each of the fuel inflow holes 4C is a valve shaft described later. 5A and a valve shaft insertion hole 4B through a gap between the valve seat portion 4E described later.
Flows into the side. An annular holding groove 4D is formed around the cylindrical protrusion 4A.

On the other hand, on the lower surface side of the valve seat member 4, a valve seat portion 4E is formed at the lower end side of the valve shaft insertion hole 4B, and a valve body 5 described later is separated from the valve seat portion 4E. Sit down. The valve guide 2 is fitted into the casing 1 from the lower end side, and the upper end of the spacer cylinder 3 is attached to a shaft holder 11 described later.
The outer peripheral side lower surface of the valve seat member 4 is fixed by the caulking portion 1B in a state of being brought into contact with the annular projection 1C via the flange portion 12A, so that the valve seat member 4 is integrated in the casing 1.

Reference numeral 5 denotes an outward-opening type valve body which is provided on the valve seat member 4 so as to be displaceable in the axial direction and serves as a driving object.
The valve body 5 includes a valve shaft 5A extending axially in the valve shaft insertion hole 4B of the valve seat member 4, a disc-shaped spring receiving plate 5B provided on the upper end side of the valve shaft 5A, It is composed of a hemispherical valve portion 5C integrally formed on the lower end side of the spring receiving plate 5B. The valve shaft 5A of the valve body 5 is inserted into the valve shaft insertion hole 4B of the valve seat member 4, and the spherical upper surface side of the valve portion 5C is separated from and seated on the valve seat portion 4E. Further, a valve spring 6 is disposed between the spring receiving plate 5B of the valve body 5 and the holding groove 4D of the valve seat member 4 around the cylindrical protrusion 4A. The valve body 5 is always urged upward in the valve closing direction. The valve body 5 is the later-described giant magnetostrictive shaft 1
When the valve is opened by 0 against the valve spring 6, the fuel that has flowed into the valve guide 2 is passed between the valve seat portion 4E and the valve portion 5C via the respective fuel inflow holes 4C of the cylindrical protrusion 4A. It is jetted to the outside.

Reference numeral 7 denotes a spring receiving member movably provided in the valve guide 2. The spring receiving member 7 has a cylindrical convex portion 7A projecting downward from the center thereof, and the diameter of the cylindrical convex portion 7A. A flanged spring receiving portion 7B is formed on the outer side in the direction. Further, the fuel receiving holes 7C, 7C, ...
Has been drilled. Then, on the upper side of the spring receiving member 7, the giant magnetostrictive shaft 1 is inserted through the spacer 8 in the cylindrical convex portion 7A.
The lower end side of 0 abuts, and the lower end side of the cylindrical convex portion 7A is connected to the valve shaft 5A of the valve body 5 via a minute gap S (5 μm before and after).
And the valve portion 5C when the giant magnetostrictive shaft 10 thermally expands.
Is prevented from being inadvertently separated from the valve seat portion 4E. Here, the spacer 8 is formed of a magnetic material in a columnar shape with a required thickness, for example, the giant magnetostrictive shaft 10
The size of the gap S is adjusted by adjusting the total size of (and the total size after the giant magnetostrictive shaft 10 is contracted by the initial load).

Reference numeral 9 denotes a setting spring located around the cylindrical convex portion 7A of the spring receiving member 7 and arranged between the spring receiving member 7 and the valve seat member 4 of the valve guide 2 for setting an initial load. The setting spring 9 constantly biases the giant magnetostrictive shaft 10 upward via the spring bearing member 7 or the like to apply an initial load to the giant magnetostrictive shaft 10 together with a shaft holder 11 described later. .

Reference numeral 10 denotes a giant magnetostrictive shaft provided in the casing 1 so as to extend in the axial direction.
0 is formed as a rod with a total length L1 in the form of a slender columnar shape from a giant magnetostrictive material such as neodymium (Nd) -iron master alloy or dysprosium (Dy) -iron, terbium (Tb) -iron master alloy, and the electromagnetic wave described later. By the magnetic field from the coil 14, for example, at room temperature (25 ° C.), a magnetic field of 1 kOe (kilo-oersted) is applied, and the total length L1 is 1000 PPM.
It is stretched and deformed in the axial direction at a ratio of (1000 × 10 ⁻⁶ ).
Further, the giant magnetostrictive shaft 10 is, for example, 1 × 10 ⁻⁵ / ° C.
It has a coefficient of thermal expansion α 1 (coefficient of linear expansion) of about 1 degree, and every time the ambient temperature rises by 1 ° C., the total length L 1 is thermally expanded by the dimension (L 1 × α 1) in the axial direction, as shown in the equation (1). .

Reference numeral 11 denotes a giant magnetostrictive shaft 1 in the casing 1.
A shaft holder in which 0 is positioned is shown, and the shaft holder 11 is formed of a non-magnetic metal material or the like into an elongated cylindrical shape and has a length dimension for accommodating the giant magnetostrictive shaft 10 in the axial direction. As shown in FIG. 2, the shaft holder 11 has a first holder cylinder 12 formed with a flange portion 12A having an open end on the lower end side and protruding radially outward, and an upper end side of the holder cylinder 12. The second magneto-strictive shaft 1 is composed of a second holder cylinder 13 which will be described later and which is joined to the coil bobbin 15 which will be described later.
It is inserted together with 0.

Here, the first holder cylinder 12 is, for example, A
It is formed of an aluminum alloy such as 5052 with a coefficient of thermal expansion α2 (α2> α1) larger than that of the giant magnetostrictive shaft 10, and the flange portion 12A is provided with a downward and upward direction at a portion facing each flow hole 7C of the spring receiving member 7. Circulation holes 12B, 1
2B, ... Are drilled. The length dimension L2 of the holder tube 12 is formed so as to occupy, for example, 66% of the length dimension of the entire shaft holder 11, and the length dimension L2 is a number which will be described later each time the ambient temperature rises by 1 ° C. As indicated by the equation (2), the material thermally expands in the axial direction by the dimension (L2 x α2).
Further, the holder cylinder 12 is fixed to the casing 1 by sandwiching the outer peripheral side of the flange portion 12A between the annular projection 1C of the casing 1 and the upper end of the spacer cylinder 3 of the valve guide 2.

Reference numeral 13 denotes a second holder cylinder which constitutes the shaft holder 11 together with the holder cylinder 12, and the holder cylinder 13
Is made of stainless steel such as SUS303 and has a coefficient of thermal expansion α3 (α3 <α1 smaller than that of the giant magnetostrictive shaft 10).
) Is formed into a cylindrical shape with a lid, and the end surface on the lower end side is joined to the end surface on the upper end side of the holder cylinder 12 by means such as laser welding. Then, the length dimension L of the holder cylinder 13
3 is formed so as to occupy, for example, 34% of the length dimension of the entire shaft holder 11, and as shown in the equation (3) to be described later, the length dimension L3 of the shaft holder 11 increases with the increase of the ambient temperature by 1 ° C. Thermally expands in the direction by the dimension (L3 x α3).

Further, the upper end side of the holder tube 13 is a closed end to form an engaging portion 13A having a flat inner surface, and the upper end side end surface 10A of the giant magnetostrictive shaft 10 abuts on the engaging portion 13A. It is engaged in the state. The giant magnetostrictive shaft 10 is axially positioned in the shaft holder 11, the lower end side thereof projects slightly downward from the opening end (flange portion 12A) side of the holder cylinder 12, and the spring receiving member 7 is interposed via the spacer 8.
It is fitted in the cylindrical convex portion 7A. Further, an axial space A is formed between the engaging portion 13A of the holder cylinder 13 and a seal retainer 19 described later, and this space A allows the entire shaft holder 11 to thermally expand in the axial direction. Has become.

Reference numeral 14 denotes an electromagnetic coil provided between the shaft holder 11 and the casing 1. The electromagnetic coil 14 is wound around a cylindrical coil bobbin 15 with a collar and is erected on the upper end side of the coil bobbin 15. Terminal pins 16, 16
It is excited by being supplied with electric power from the outside via. Then, the electromagnetic coil 14 applies a magnetic field to the giant magnetostrictive shaft 10 to axially expand and transform the giant magnetostrictive shaft 10 against the set spring 9, thereby causing the valve body 5 to move toward the valve spring 6 and the valve spring 6.
Drive in the valve opening direction against. Also, the coil bobbin 15
A sliding hole 15A extending in the axial direction is formed on the inner peripheral side of the shaft holder 11, and the shaft holder 11 is inserted into the sliding hole 15A.

Reference numeral 17 denotes the casing 1 by the caulking portion 1A.
The lid 17 is positioned on the upper end side of the inside, and the lid 17 is made of a magnetic material in the shape of a thick disk and forms a magnetic path together with the casing 1. Here, small diameter insulating cylinders 18 and 18 are mounted around the respective terminal pins 16 on the lid body 17, and the respective insulating cylinders 18 insulate the terminal pins 16 from the lid body 17, and the casing 1 The internal fuel is prevented from leaking to the outside together with the sealing member 20 described later.

Reference numeral 19 denotes a seal retainer provided in contact with the lower end surface of the lid body 17. The seal retainer 19 is formed in a substantially disc shape, and is composed of an annular step portion 1D and a caulking portion 1A of the casing 1. It is fixed together with the lid 17. further,
Reference numerals 20 and 20 denote seal members arranged around the terminal pins 16 between the lid body 17 and the seal retainer 19, and the seal members 20 are located below the insulating cylinder 18.
By sealing the gap between the lid 17 and each terminal pin 16, the fuel in the casing 1 is prevented from leaking to the outside.

The giant magnetostrictive injection valve according to this embodiment has the above-mentioned structure, and its operation will be described below.

First, when a magnetic field is applied to the giant magnetostrictive shaft 10 by exciting the electromagnetic coil 14 by supplying an injection pulse to the electromagnetic coil 14 as indicated by a solid line 21 in FIG. 3, the giant magnetostrictive shaft 10 is excited. 10 expands and deforms according to the strength of the magnetic field at this time, and displaces the spring receiving member 7 together with the spacer 8 downward against the setting spring 9. And
When the valve body 5 is stretched and deformed by the giant magnetostrictive shaft 10, as shown in FIG.
By displacing the valve portion 5C downward with a lift amount as indicated by a characteristic line 22 indicated by a solid line, and separating the valve portion 5C from the valve seat portion 4E, the fuel in the casing 1 is transferred to the valve seat portion 4E and the valve portion 5C.
It is jetted to the outside from between.

In this case, since the upper end face 10A of the giant magnetostrictive shaft 10 abuts on the engaging portion 13C of the shaft holder 11 and the upward displacement is restricted, the giant magnetostrictive shaft 10 is controlled by the magnetic field from the electromagnetic coil 14. The valve body 5 is stretched and deformed downward to open the valve body 5 against the set spring 9 and the valve spring 6. When the electromagnetic coil 14 is demagnetized, the giant magnetostrictive shaft 10 contracts, the spring receiving member 7 is pushed upward by the setting spring 9, and the valve portion 5C of the valve body 5 is pushed by the valve spring 6. It comes to sit on the valve seat portion 4E.

Further, since the valve body 5 is an outwardly opening type valve body, when the super magnetostrictive injection valve is used as an in-cylinder direct injection type injection valve, the pressure in the combustion chamber (not shown) is increased. Is the valve body 5
Even when an external force is applied to the valve body 5, the valve body 5 is pressed against the valve seat portion 4E and continues to be seated, and it is possible to prevent the valve body 5 from being opened accidentally until the injection pulse is supplied to the electromagnetic coil 14.

By the way, the upper end face 10A of the giant magnetostrictive shaft 10 is replaced with the engaging portion 13C of the shaft holder 11, and the casing 1 is provided via a lid or the like as described in the prior art.
When it is fixed to, the heat from the combustion chamber and the electromagnetic coil 14
The giant magnetostrictive shaft 10 thermally expands due to the heat generation of the above. When the thermal expansion of the giant magnetostrictive shaft 10 is larger than that of the casing 1, the upward extension of the giant magnetostrictive shaft 10 due to the thermal expansion is restricted by the lid or the like and extends downward. The shaft 10 comes to thermally expand downward, which pushes the valve body 5 downward, and in the worst case, the valve portion 5C of the valve body 5 separates from the valve seat portion 4E and causes a seal failure. Becomes

Further, as shown in FIG. 3, when the injection pulse is supplied to the electromagnetic coil 14 to expand and deform the giant magnetostrictive shaft 10 to open and close the valve body 5, the thermal expansion component of the giant magnetostrictive shaft 10 is released. In addition to the displacement of the body 5, the lift amount of the valve body 5 becomes larger than the normal lift amount (characteristic line 22) as shown by a characteristic line 23 shown by a virtual line in FIG. 3, and the fuel injection amount is excessive. Will be.

Therefore, in this embodiment, the lower end side is the first holder cylinder 12 fixed to the casing 1 as the open end having the flange portion 12A, and the lower end side is the upper end side of the first holder cylinder 12. The shaft holder 11 is composed of the second holder cylinder 13 that is joined to and engages with the upper end side end surface 10A of the giant magnetostrictive shaft 10 as the engaging portion 13A. With the coil bobbin 15 inserted in the sliding hole 15A,
Since the axial space A is interposed between the engagement portion 13A of the holder cylinder 13 and the seal retainer 19, the following operational effects can be obtained.

That is, when the ambient temperature rises by, for example, t ° C., the giant magnetostrictive shaft 10 is

[0044]

## EQU1 ## A thermal expansion ΔL1 of ΔL1 = L1 × α1 × t occurs. Also, the holder tubes 12, 13
The thermal expansion ΔL of the entire shaft cover 11 consisting of

[0045]

## EQU2 ## ΔL = (L2 × α2 + L3 × α3) × t. Then, the thermal expansion of the entire shaft holder 11 ΔL
Equal to the thermal expansion ΔL1 of the giant magnetostrictive shaft 10,

[0046]

[Equation 3] ΔL1 = ΔL L1 × α1 = L2 × α2 + L3 × α3, so that the thermal expansion coefficients α2, α3 and the length dimension L2 of the holder cylinders 12, 13 constituting the shaft holder 11 are:
By determining L3 as described above, the thermal expansion ΔL1 of the giant magnetostrictive shaft 10 and the thermal expansion ΔL of the entire shaft holder 11 can be made equal.

As a result, even if the giant magnetostrictive shaft 10 thermally expands in the axial direction due to the heat generation of the electromagnetic coil 14 or the like, the thermal expansion of the entire shaft holder 11 can be made to correspond to the thermal expansion of the giant magnetostrictive shaft 10. Since the thermal expansion of the entire holder 11 can be offset so as to absorb the expansion due to the thermal expansion of the giant magnetostrictive shaft 10, it is possible to effectively prevent the lift amount of the valve body 5 from changing due to the thermal expansion of the giant magnetostrictive shaft 10. The valve body 5 can be opened and closed with a proper lift amount as indicated by the characteristic line 22 in FIG.

In this case, the entire shaft holder 11 is set to the first
When the holder cylinder 12 is made of a single member made of an aluminum alloy such as A5052,
The thermal expansion of the entire shaft holder 11 becomes larger than the thermal expansion of the giant magnetostrictive shaft 10 in accordance with the driving time as shown by the characteristic line 24 in FIG. It becomes smaller according to. The lift amount at this time is as shown by a characteristic line 25 shown by a virtual line in FIG.

On the other hand, when the entire shaft holder 11 is composed of a single member made of stainless steel such as SUS303 like the second holder cylinder 13, the driving time is as shown by the characteristic line 26 shown in FIG. According to the giant magnetostrictive shaft 1
The thermal expansion of 0 is larger than the thermal expansion of the entire shaft holder 11, and the lift amount of the valve element 5 is 60 μm before and after 30 μm.
It becomes large up to about μm depending on the driving time.

On the other hand, in this embodiment, for example, A50
First holder cylinder 12 made of aluminum alloy such as 52
And a second made of stainless steel such as SUS303
Of the holder cylinder 13 is joined in the axial direction to the holder cylinder 12,
Since the length dimensions L2 and L3 are appropriately selected according to the thermal expansion coefficients α2 and α3 of the respective materials composing 13, the thermal expansion of the entire shaft holder 11 corresponds to the thermal expansion of the giant magnetostrictive shaft. As shown by a characteristic line 27 shown in FIG. 4, the lift amount of the valve body 5 is maintained 30 μm before and after, and the lift amount of the valve body 5 becomes excessive or decreases according to the driving time. Can be reliably prevented.

Further, the giant magnetostrictive shaft 10 having a coefficient of thermal expansion α1
Holder cylinder 12 having a larger coefficient of thermal expansion α2 than
Shaft holder 1 combined with holder tube 13 with a small 3
1, the thermal expansion of the entire shaft holder 11 can be easily matched with the thermal expansion of the giant magnetostrictive shaft 10, and the holder cylinder 1 constituting the shaft holder 11
It is possible to select the materials and lengths of 2 and 13 with a relatively large selection (selection width). Further, the electromagnetic coil 14 can be cooled by the fuel flowing in the casing 1, and the shaft holder 11 and the giant magnetostrictive shaft 10 can be cooled.
The temperature difference between and can be reliably reduced.

On the other hand, the valve body 5 is heated by heat from the combustion chamber.
Even when the heat expands, due to the minute gap S formed between the upper end of the valve shaft 5A of the valve body 5 and the spring receiving member 7,
The amount of thermal expansion of the valve body 5 can be absorbed, and the valve portion 5C can be prevented from being inadvertently separated from the valve seat portion 4E due to the influence of heat from the outside. Then, when the injection pulse is supplied to the electromagnetic coil 14 to open the valve element 5 and the giant magnetostrictive shaft 10 is stretched and deformed by the magnetic field at this time, the spring bearing member 7 moves downward against the setting spring 9. Although it displaces and collides with the upper end of the valve shaft 5A of the valve body 5 so as to eliminate the gap S, the impact at this time can be prevented from being directly transmitted to the giant magnetostrictive shaft 10 by the spacer 8, and the impact of the giant magnetostrictive shaft 10 can be prevented. The durability can be improved.

Therefore, according to the present embodiment, the choices of the materials and length dimensions of the holder cylinders 12 and 13 constituting the shaft holder 11 can be greatly expanded, and the supermagnetostrictive shaft 10 can be operated by the increase of the ambient temperature. At the time of thermal expansion, the thermal expansion of the giant magnetostrictive shaft 10 can be absorbed and canceled by the thermal expansion of the shaft holder 11, which ensures that the displacement amount of the valve body 5 to be driven changes. This can be prevented, and the fuel injection amount of the super magnetostrictive injection valve can be stabilized and reliability can be improved.

Further, when there is a temperature difference between the shaft holder 11 that directly receives heat from the electromagnetic coil 14 and the giant magnetostrictive shaft 10 that indirectly receives the heat, the holder cylinder 12, which constitutes the shaft holder 11, By appropriately selecting the material and length of 13 and making the thermal expansion ΔL of the entire shaft holder 11 slightly smaller than the thermal expansion ΔL1 of the giant magnetostrictive shaft 10, the lift amount of the valve body 5 is kept constant. Therefore, various effects such as stability and reliability of the giant magnetostrictive injection valve can be improved.

Next, FIGS. 5 to 9 show a second embodiment of the present invention. The feature of this embodiment is that the shaft holder is constituted by first and second holder members having different thermal expansion coefficients. By combining these so as to overlap each other and limiting the thermal expansion of the first holder member by the second holder member, the thermal expansion of the entire shaft holder is made to approach the thermal expansion of the giant magnetostrictive shaft. is there. In this embodiment, the same components as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

In the figure, 31 is a shaft holder used in this embodiment, and the shaft holder 31 is constructed by combining holder frames 32 and 33, which will be described later, with each other as shown in FIGS.

Reference numeral 32 denotes a holder frame constituting the first holder member, and the holder frame 32 has a coefficient of thermal expansion α4 larger than that of the giant magnetostrictive shaft 10 (coefficient of thermal expansion α1) (α4> α1).
), A pair of arms 32A, 32A formed of an aluminum alloy such as A5052 or another metal material with a total length L4 and extending substantially in the shape of a letter L, and the arms 32A are connected at the upper end side. Engagement portion 3 having a substantially U shape
2B and. Then, a pair of fixing portions 32C, 32C, which project in the left-right direction from the lower end side and are sandwiched between the annular projection 1C of the casing 1 and the upper end of the spacer cylinder 3, are integrally formed on each arm portion 32A of the holder frame 32. Has been done. Further, the holder frame 32 includes the arm portions 32A and the engaging portion 3
The space surrounded by 2B is a housing space 32D for housing the giant magnetostrictive shaft 10.

Reference numeral 33 denotes a holder frame which constitutes the second holder member, and the holder frame 33 has a coefficient of thermal expansion α5 smaller than that of the giant magnetostrictive shaft 10 (coefficient of thermal expansion α1) (α5 <α1).
), For example, made of stainless steel such as SUS303 or other metal material with a total length L5, and similar to the holder frame 32, a pair of arm portions 33A, 33A and the arm portions 33A are connected at the upper end side. It is composed of a U-shaped stopper portion 33B and fixing portions 33C and 33C integrally formed on the lower end side of each arm portion 33A. As shown in FIG. 7, the holder frame 33 has a total length L5 corresponding to the thickness dimension T of the stopper portion 33B and a total length L4 of the holder frame 32.
The space that is formed to be longer than that and is surrounded by each arm portion 33A and the stopper portion 33B is a storage space 33D.

Here, the holder frames 32 and 33 form the shaft holder 31 by inserting the holder frame 32 into the holder frame 33 so as to overlap with each other and combining them in a cross shape as shown by the arrow in FIG. , The fixed parts 32C, 3 on the lower end side
3C is flush, and the stopper portion 33B is in contact with the upper surface side of the engaging portion 32B at the upper end side. Also, the holder frame 3
As illustrated in FIG. 8, the giant magnetostrictive shaft 10 is housed in an inscribed state in the rectangular parallelepiped space formed by the housing spaces 32D and 33D in the Nos. 2 and 33.

The shaft holder 31 used in this embodiment is configured as described above, and the fixing portion 32 of the holder frames 32 and 33 is used.
The shaft holder 31 is fixed to the casing 1 by sandwiching C and 33C between the annular protrusion 1C of the casing 1 and the upper end of the spacer cylinder 3.

Here, when the giant magnetostrictive shaft 10 and the shaft holder 31 thermally expand due to heat generation of the electromagnetic coil 14, the engaging portion 32B of the holder frame 32 is made of a material having a smaller coefficient of thermal expansion than the holder frame 32. Since the holder frame 32 is in contact with the stopper portion 33B of the holder frame 33, the thermal expansion of the holder frame 32 in the axial direction is restricted by the holder frame 33, and the thermal expansion ΔLT of the entire shaft holder 31 is equal to that of the holder frame 32. Expansion ΔL4 and thermal expansion of holder frame 33 ΔL
It takes an intermediate value with 5.

That is, when the ambient temperature rises, for example, t ° C., the holder frame 32 is

[0063]

## EQU4 ## A thermal expansion ΔL4 of ΔL4 = L4 × α4 × t occurs. The thermal expansion ΔL5 of the holder frame 33 is

[0064]

## EQU5 ## ΔL5 = L5 × α5 × t, and the thermal expansion ΔLT of the entire shaft holder 31 is

[0065]

## EQU6 ## The holder frame 32 is elastically compressed so that the holder frame 33 is elastically expanded and deformed so that ΔL4>ΔLT> ΔL5, and the thermal expansion ΔLT of the entire shaft holder 31 is It takes an intermediate value between the thermal expansion ΔL4 of the frame 32 and the thermal expansion ΔL5 of the holder frame 33.

In this case, the thermal expansion ΔLT of the entire shaft holder 31 can be obtained by appropriately combining the materials of the holder frames 32 and 33 (coefficients of thermal expansion α4 and α5 and elastic coefficient).
Can be approximated or matched with the thermal expansion .DELTA.L1 (see the equation of the above-mentioned equation 1) of the giant magnetostrictive shaft 10.

Thus, the present embodiment having such a structure can obtain substantially the same effects as the first embodiment, but particularly in this embodiment, the holder frames 32, 33 are provided.
Since the space (accommodation spaces 32D and 33D) into which the fuel flows out and enters is formed between the supermagnetostrictive shaft 10 and the giant magnetostrictive shaft 10, the electromagnetic coil 14 can be cooled from the inside by circulating the fuel in this space. It is possible to more effectively prevent the temperature difference between the holder 31 and the giant magnetostrictive shaft 10.

In the first embodiment described above, the first holder cylinder 12 and the second holder cylinder 13 are joined by laser welding, but the present invention is not limited to this. For example, the first holder cylinder The second holder cylinder and the second holder cylinder may be joined by using a fastening means such as a screw. Further, the first and second holder cylinders do not necessarily have to be formed of a metal material, and may be configured by combining, for example, a metal material and a ceramic material or a resin material, and a shaft holder having three or more holders. It may be configured by joining the tubes to each other in the axial direction.

In the second embodiment, the holder frame 3
Although the case where both 2 and 33 are made of a metal material is illustrated, also in this case, a combination of a metal material and a ceramic material or a resin material or the like is possible.

Further, in each of the above embodiments, the giant magnetostrictive injection valve using the valve element 5 of the outward opening type has been described as an example.
The present invention is not limited to this, and may be applied to, for example, a giant magnetostrictive injection valve using an inward opening type valve body, and in this case, a giant magnetostrictive shaft that undergoes contraction deformation in the axial direction when a magnetic field is applied. Can be used.

Furthermore, the giant magnetostrictive actuator of the present invention is not limited to the one applied to the giant magnetostrictive injection valve, but the giant magnetostrictive actuator may be used instead of an electromagnetic solenoid such as an electromagnetic on-off valve. In this case, the one end side of the giant magnetostrictive rod may be attached to the spool valve body, the poppet valve body or the like which is the object to be driven. Further, it may be applied to a disc brake or the like, and in this case, the expansion / contraction deformation of the giant magnetostrictive shaft may be transmitted to the friction pad to apply a braking force to the disc.

[0072]

As described in detail above, according to the first aspect of the invention, the shaft holder is formed by combining a plurality of members having different thermal expansion coefficients, so that the giant magnetostrictive shaft generates heat from the electromagnetic coil. Even when thermal expansion occurs due to, etc., the thermal expansion of the entire shaft holder can be made compatible with the thermal expansion of the giant magnetostrictive shaft by appropriately selecting the material and shape (length dimension) of each member constituting the shaft holder. Therefore, the thermal expansion of the shaft holder can be easily approximated or matched with the thermal expansion of the giant magnetostrictive shaft as compared with the case where the shaft holder is formed of a single material.

When the giant magnetostrictive shaft thermally expands in the axial direction, the shaft holder also thermally expands in substantially the same manner, and this thermal expansion can offset the displacement of the driven object due to the thermal expansion of the giant magnetostrictive shaft. Therefore, it is possible to effectively prevent the occurrence of characteristic defects and the like. Further, when applied to a giant magnetostrictive injection valve or the like, it is possible to prevent the lift amount of the valve body from changing due to thermal expansion, and it is possible to eliminate the occurrence of defective sealing.

According to a second aspect of the present invention, the shaft holder is fixed to the casing with a first holder cylinder and the other end side of the first holder cylinder is joined to the other end side of the supermagnetostriction. By configuring the second holder cylinder that engages with the other end of the shaft, the thermal expansion of the entire shaft holder can be performed by changing the material of each holder cylinder and the dimensional ratio of each holder cylinder to the entire shaft holder. Can be easily adjusted.

On the other hand, according to the invention of claim 3, one end of the shaft holder serves as a fixing portion fixed to the casing, and the other end thereof serves as an engaging portion for engaging with the other end of the giant magnetostrictive shaft. A first holder member and a material having a coefficient of thermal expansion smaller than that of the first holder member, one end side being a fixing portion fixed to the casing, and the other end side being an engaging portion of the first holder member. Since the second holder member serves as a stopper portion that comes into contact with the outside from the outside, the second holder member can regulate the thermal expansion of the first holder member, and the thermal expansion of the entire shaft holder is reduced to the first. It can be adjusted to an intermediate value between the thermal expansion of the holder member and the thermal expansion of the second holder member.

Further, as in the invention described in claim 4,
A flow path for a pressurized fluid is formed between the casing and the giant magnetostrictive shaft, and the driven object is constituted by an outward-opening type valve body protruding outside the casing in order to discharge the fluid to the outside of the casing. As a result, the electromagnetic coil can be cooled by the pressurized fluid flowing in the casing, and the temperature difference between the shaft holder and the giant magnetostrictive shaft can be prevented.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing a giant magnetostrictive injection valve according to a first embodiment of the present invention.

FIG. 2 is an enlarged vertical sectional view showing the shaft holder in FIG.

FIG. 3 is a characteristic diagram showing a relationship between a valve lift amount and an injection pulse.

FIG. 4 is a characteristic diagram showing a relationship between a drive time of a giant magnetostrictive injection valve and a lift amount of a valve body in a state where a material of a shaft holder is changed.

FIG. 5 is a vertical sectional view showing a giant magnetostrictive injection valve according to a second embodiment.

FIG. 6 is an exploded perspective view showing a shaft holder in FIG. 5 in an enlarged manner.

FIG. 7 is an enlarged front view of the shaft holder in FIG.

8 is a bottom view of the shaft holder shown in FIG. 7. FIG.

9 is a plan view of the shaft holder shown in FIG. 7. FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Casing 1E Fuel flow hole 2 Valve guide 3 Spacer cylinder 4 Valve seat member 4E Valve seat 5 Valve body (object to be driven) 6 Valve spring 7 Spring receiving member 8 Spacer 9 Setting spring 10 Giant magnetostrictive shaft 11, 31 Shaft holder 12 1st holder cylinder 12A Flange part 13 2nd holder cylinder 13A Engagement part 14 Electromagnetic coil 15 Coil bobbin 17 Lid body 32 Holder frame (1st holder member) 32A, 33A Arm part 32B Engagement part 32C, 33C fixed. Part 32D, 33D Storage space 33 Holder frame (second holder member) 33B Stopper part

Claims (4)

[Claims] 1. A cylindrical casing, a giant magnetostrictive shaft that is provided in the casing so as to extend in the axial direction and expands and contracts by the action of a magnetic field, and is driven in the axial direction by the giant magnetostrictive shaft. , A driving object displaceably provided on one end side of the casing and extending in the axial direction to position the giant magnetostrictive shaft in the casing, one end side being fixed to the casing, the other end side of the giant magnetostrictive shaft. A shaft holder that engages with the other end side, and an electromagnetic coil that is provided between the shaft holder and the casing and applies a magnetic field to the super magnetostrictive shaft are provided, and the shaft holder has thermal expansion of the super magnetostrictive shaft. A giant magnetostrictive actuator configured by combining a plurality of members having different coefficients of thermal expansion so as to absorb the displacement caused by. 2. The shaft holder has a first holder cylinder fixed to the casing with one end side being an open end, one end side joined to the other end side of the first holder cylinder, and the other end side closed. The giant magnetostrictive actuator according to claim 1, wherein the giant magnetostrictive actuator comprises two members having different coefficients of thermal expansion from a second holder cylinder that becomes an end and engages with the other end side of the giant magnetostrictive shaft. 3. A first holder member, wherein the shaft holder has one end serving as a fixing portion fixed to the casing, and the other end serving as an engaging portion engaging with the other end of the giant magnetostrictive shaft, A stopper portion formed of a material having a smaller thermal expansion coefficient than that of the first holder member, one end side being a fixing portion fixed to the casing, and the other end side being in contact with the engaging portion of the first holder member from the outside. The giant magnetostrictive actuator according to claim 1, wherein the giant magnetostrictive actuator comprises a second holder member. 4. An outward-opening type in which the driven object projects to the outside of the casing to form a flow path of a pressurized fluid between the casing and the giant magnetostrictive shaft, and to discharge the fluid to the outside of the casing. The giant magnetostrictive actuator according to claim 1, wherein the giant magnetostrictive actuator is configured by the valve body.