JP2591545Y2 - Giant magnetostrictive actuator - Google Patents

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 suitably used for driving a driving object such as a valve body, and more particularly, to preventing the characteristics from being changed by thermal expansion. The present invention relates to a giant magnetostrictive actuator.

[0002]

2. Description of the Related Art In general, a magnetic field is applied to a cylindrical casing and a casing extending in an axial direction of the casing and provided in the casing and driven at one end of the casing. A giant magnetostrictive rod that expands and contracts in the axial direction, a coil bobbin provided in the casing positioned around the giant magnetostrictive rod, and a coil wound around the coil bobbin, and energized from the outside to generate the giant magnetostrictive rod. A fuel injection valve using a giant magnetostrictive actuator including an electromagnetic coil that applies a magnetic field to the casing and a positioning member provided on the other end side of the casing and positioning the giant magnetostrictive rod in the casing in the axial direction is, for example, JP-A-3-
243174, and the like.

[0003] In this kind of prior art fuel injection valve,
A valve seat having a fuel injection port is provided at one end of the casing, and the valve body is urged in a normally closed direction by a valve spring so that an inwardly-opening valve body to be driven is seated on the valve seat. At the same time, one end of the giant magnetostrictive rod is fixed to the valve body, and when the giant magnetostrictive rod is reduced by the magnetic field from the electromagnetic coil, the giant magnetostrictive rod lifts the valve body against the valve spring, The fuel in the casing is injected outward from the injection port.

On the other end of the casing, there is provided a lid as a positioning member that is in contact with the other end of the giant magnetostrictive rod, and the lid moves the giant magnetostrictive rod together with the valve to the valve seat side. And the spring load of the valve spring is adjusted. When the giant magnetostrictive rod is reduced and deformed by the magnetic field from the electromagnetic coil, the rod is prevented from separating from the lid, and the valve is reliably lifted against the valve spring.

[0005]

In the above-mentioned prior art, a valve body to be driven is provided at one end of the casing, and a lid is provided at the other end of the casing. The giant magnetostrictive rod is positioned in the casing in the axial direction, so if the electromagnetic coil provided around the giant magnetostrictive rod generates heat when energized from the outside, the giant magnetostrictive The rod may thermally expand in the axial direction between the lid and the valve. The giant magnetostrictive rod has a larger coefficient of thermal expansion than the casing, and the lid is integrally fixed to the casing. Therefore, the giant magnetostrictive rod extends toward the valve body during thermal expansion.

Therefore, according to the prior art, not only the spring load of the valve spring changes due to the thermal expansion of the giant magnetostrictive rod, but also when the giant magnetostrictive rod is deformed by the magnetic field from the electromagnetic coil, the lift amount of the valve body is reduced. Therefore, there is a problem that the characteristics and the like of the injection flow rate fluctuate due to thermal influence.

There is also known a structure in which a valve element to be driven is of an open-open type, and the valve element is opened when the giant magnetostrictive rod expands and deforms. When the rod thermally expands, the valve body may be displaced in the valve opening direction and may be separated from the valve seat, causing a problem such as poor sealing.

The present invention has been made in view of the above-mentioned problems of the prior art. In the present invention, even when the giant magnetostrictive rod thermally expands, the thermal expansion can be absorbed by the thermal expansion of the coil bobbin, resulting in poor characteristics. It is an object of the present invention to provide a giant magnetostrictive actuator that can effectively prevent the driving object such as a valve element from being driven stably.

[0009]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a cylindrical casing, which is provided in the casing so as to extend in the axial direction of the casing, and is provided at one end of the casing. A giant magnetostrictive rod that expands and contracts in the axial direction when a magnetic field is applied, a coil bobbin provided around the giant magnetostrictive rod and provided in the casing, and a coil bobbin wound around the coil bobbin. The magnet bobbin is made of a non-magnetic material having a required coefficient of thermal expansion. The coil bobbin is formed in a cylindrical shape with a predetermined length based on the length and the coefficient of thermal expansion, and one end of the coil bobbin is fixed to the casing to form a free end. It is adopted comprising a characteristic structure in that at the other side so as to position the ultrasonic magnetostrictive rod in the axial direction.

In this case, a terminal pin for energizing the electromagnetic coil from outside the casing is provided at the other end of the casing, and one side is provided between the terminal pin and the other end of the coil bobbin. It is preferable that a conductive spring member that is connected to the electromagnetic coil and has the other side elastically contacting the terminal pin is provided.

[0011]

According to the above construction, when the giant magnetostrictive rod expands in the axial direction due to heat generation of the electromagnetic coil or the like, the coil bobbin can be thermally expanded in the axial direction corresponding to the thermal expansion. The expansion can be absorbed by the thermal expansion of the coil bobbin.

If a terminal pin is provided on the other end of the casing and a conductive spring member is provided between the terminal pin and the other end of the coil bobbin, the spring member bends when the coil bobbin is thermally expanded. Therefore, the coil bobbin can be allowed to extend in the axial direction in the casing, and even when the coil bobbin is thermally expanded, the electric current can be reliably supplied from the terminal pin to the electromagnetic coil via the spring member.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

In FIG. 1, reference numeral 1 denotes a cylindrical casing formed of a magnetic material such as an electromagnetic stainless steel into a stepped cylindrical shape.
A, 1B, and an annular projection 1C is provided on the inner peripheral side above the caulking portion 1B by a predetermined dimension.

Reference numeral 2 denotes a rod guide provided on a lower end side inner periphery of the casing 1 via a guide cylinder 3, and the rod guide 2 is formed in a disk shape from a material having high wear resistance.
A rod sliding hole 2A is formed in the center side. Then, the rod guide 2 is a caulked portion 1B of the casing 1.
The annular projection 1C is fixed by caulking via a guide cylinder 3 to close the lower end of the casing 1.

Reference numeral 4 denotes a push rod as an object to be driven provided at the lower end side of the casing 1. The push rod 4 slides in the guide cylinder 3 between the annular projection 1C of the casing 1 and the rod guide 2. A disc-shaped spring receiving portion 4A movably inserted and projecting downward from the center of the lower surface of the spring receiving portion 4A and projecting out of the casing 1 through a rod sliding hole 2A of the rod guide 2. A shaft portion 4B having a small diameter, a disk portion 4C located on the upper surface side of the spring receiving portion 4A and having a smaller diameter than the spring receiving portion 4A, and inserted into the annular projection 1C of the casing 1; The rod storage hole 6A of the coil bobbin 6, which is provided to project upward from the center of the upper surface of the portion 4C and is described later.
And a small-diameter boss portion 4D inserted therein. The boss portion 4D is always in contact with the lower end side end face of the giant magnetostrictive rod 10 described later in the rod storage hole 6A.

Reference numeral 5 denotes a setting spring as biasing means disposed around the shaft portion 4B of the push rod 4 and between the spring receiving portion 4A and the rod guide 2. The setting spring 5 is a push rod. 4, the giant magnetostrictive rod 10 is constantly urged upward through the spring receiving portion 4A, the boss portion 4D, etc., and an initial load is applied to the giant magnetostrictive rod 10 with the coil bobbin 6. Here, for example, a valve body (not shown) such as an intake valve or an exhaust valve of an automobile engine is attached to the push rod 4 on the protruding end side of the shaft portion 4B. Opens and closes.

Reference numeral 6 denotes a stepped cylindrical coil bobbin provided in the casing 1 around the giant magnetostrictive rod 10, and the coil bobbin 6 is, for example, 1.2 to 2.4 × 1.
A rod housing in which an elongated cylindrical shape is formed of a nonmagnetic material such as aluminum or brass having a thermal expansion coefficient α1 (linear expansion coefficient) of about 0 ⁻⁵ / ° C., and a giant magnetostrictive rod 10 is housed on the inner peripheral side. It has a hole 6A. The coil bobbin 6
A thick flange portion 6B projecting radially outward is integrally formed at the lower end of the push rod 4, and a shallow bottom formed at the lower surface of the flange portion 6B with a diameter larger than the disk portion 4C of the push rod 4. 6C is provided. The outer peripheral side of the flange portion 6B of the coil bobbin 6 abuts on the annular projection 1C of the casing 1, and is fixed to the casing 1 via screws 7, 7,.

At the upper end of the coil bobbin 6, there is provided a lid 6D formed on a disk having an outer diameter corresponding to the flange 6B, and a small-diameter projection 6E is formed at the center of the upper surface of the lid 6D. Are integrally formed. The cover 6D of the coil bobbin 6 is a free end and is slidably inserted into the casing 1 and the lower center of the cover 6D is the upper end of the giant magnetostrictive rod 10 housed in the rod housing hole 6A. The side end surface serves as a stopper portion 6F that abuts. Here, the coil bobbin 6 is formed such that the length dimension L1 from the lower surface of the flange portion 6B to the stopper portion 6F satisfies the following equation (3). When the ambient temperature rises by t ° C. The length dimension L1 is based on the coefficient of thermal expansion α1,

[0020]

## EQU1 ## Thermal expansion occurs with a thermal expansion amount ΔL1 of ΔL1 = L1 × α1 × t.

Reference numeral 8 denotes an electromagnetic coil which is located between the flange 6B and the lid 6D of the coil bobbin 6 and is wound around the outer periphery of the coil bobbin 6 via an insulating tape 9. The electromagnetic coil 8 will be described later. And is excited by an externally supplied electric current to generate a magnetic field. And
The giant magnetostrictive rod 10 is extended and deformed in the axial direction by the magnetic field from the electromagnetic coil 8, and at this time, the push rod 4 is driven in the valve opening direction of the valve body against the setting spring 5. Also,
The insulating tape 9 is formed in a strip shape from a fluorine-based resin material, and electrically insulates between the coil bobbin 6 and the electromagnetic coil 8.

10 is a rod storage hole 6A of the coil bobbin 6.
1 shows a giant magnetostrictive rod inserted in
0 is formed from a giant magnetostrictive material such as neodymium (Nd) -iron mother alloy or dysprosium (Dy) -iron or terbium (Tb) -iron mother alloy as an elongated cylindrical rod having a positive magnetostrictive property. The giant magnetostrictive rod 10 is applied with a magnetic field of, for example, 1 kOe (kilo Oersted) from the electromagnetic coil 8 to have a length L2 of 1000P.
It expands and deforms in the axial direction at a ratio of PM (1000 × 10 ⁻⁶ ).

Here, the giant magnetostrictive rod 10 has an upper end side abutting against the stopper 6F of the coil bobbin 6, a lower end side abutting against the boss 4D of the push rod 4, and the inside of the rod housing hole 6A of the coil bobbin 6. It is positioned in the axial direction. The giant magnetostrictive rod 10 is constantly urged upward by the setting spring 5 via the push rod 4, and a predetermined initial load is applied between the push rod 4 and the stopper 6F of the coil bobbin 6.

The giant magnetostrictive rod 10 is, for example, 1 ×
^Has a thermal expansion coefficient α2 (linear expansion coefficient) of about 10 ^-5 / ° C,
When the ambient temperature rises by t ° C., the thermal expansion amount ΔL2 in the axial direction with respect to the length dimension L2,

[0025]

## EQU2 ## Thermal expansion is performed with ΔL2 = L2 × α2 × t.

Here, the coefficient of thermal expansion α 1 of the coil bobbin 6,
The length L1 is expressed by the following equations (1) and (2) with respect to the coefficient of thermal expansion α2 of the giant magnetostrictive rod 10 and the length L2.

[0027]

３L1 = L1 × α1 × t = △ L2 = L2 × α2 × t L1 × α1 = L2 × α2

As a result, when the ambient temperature of the coil bobbin 6 rises by t ° C., and the giant magnetostrictive rod 10 housed inside expands in the axial direction by the dimension (L 2 × α 2 × t), it responds to this. Thermal expansion is performed with the dimension (L1 × α1 × t), and the thermal expansion of the giant magnetostrictive rod 10 is reduced by the stopper 6F.
At this time, the giant magnetostrictive rod 10 is prevented from displacing the push rod 4 in the axial direction. Further, the stopper portion 6F of the coil bobbin 6 comes into surface contact with the upper end side end surface of the giant magnetostrictive rod 10 with a relatively large contact area, so that the initial load from the setting spring 5 acts on the giant magnetostrictive rod 10 effectively. ing.

Reference numeral 11 denotes a caulking portion 1 at the upper end of the casing 1.
A cover, which is fixed via A and constitutes a part of the casing 1, shows a lid made of a magnetic material such as electromagnetic stainless steel in a disk shape. Forming a circuit.

Reference numerals 12 and 12 denote terminal pins fixed to the lid 11 via the respective insulating cylinders 13. The terminal pins 12 are spaced apart from each other at predetermined intervals in the radial direction of the lid 11, and
3 electrically insulates the lid 11. Each terminal pin 12 has a lower head 12A disposed inside the casing 1 and an upper end protruding from the lid 11 to the outside of the casing 1 with a predetermined length.

Numeral 14 denotes a holder fitted on the outer periphery of the projection 6E of the coil bobbin 6 and fixed on the lid 6D of the coil bobbin 6. The holder 14 is made of an insulating resin material such as nylon as shown in FIG. , Cylindrical portion 14A and annular collar portion 14
B is formed in a stepped cylindrical shape, and a tapered chamfered portion 14C is formed on the upper end side of the cylindrical portion 14A. The holder 14 positions each spring 15, which will be described later, on the upper end side of the coil bobbin 6.
And each spring 15 is electrically insulated.

Reference numerals 15 and 15 denote springs as a pair of spring members which are integrally provided on the outer peripheral side of the cylindrical portion 14A of the holder 14 and connect the electromagnetic coil 8 to the respective terminal pins 12. As shown in FIG. 2, a conductive metal plate having a spring property is formed by press forming, and the lower end side is formed on the flange portion 14 </ b> B of the holder 14.
A is a pair of arms 15A, 15A that are curved in an arc shape with a curvature corresponding to A and extend on both sides in the circumferential direction.
A locking claw 15B that is hooked on the outer peripheral side of the cylindrical portion 14A is integrally formed on the tip side of 5A. At the upper end side of each spring 15, an inclined plate portion 15C which is obliquely bent along the chamfered portion 14C of the holder 14 and extends above the cylindrical portion 14A, and a cylindrical portion 14C extending from the tip of the inclined plate portion 15C.
A contact plate 15D bent parallel to the upper surface of A is provided, and the contact plate 15D is provided with spring properties by an inclined plate 15C.

Here, the springs 15 are provided on the outer peripheral side of the cylindrical portion 14A of the holder 14 so as to be separated from each other, and are retained in the cylindrical portion 14A by the locking claws 15B so as not to be pulled out. The contact plate 15D of each spring 15
Are elastically abutted against the head 12A of each terminal pin 12 with a spring property, and when the coil bobbin 6 is thermally expanded, the inclined plate portion 15
By bending via C, the coil bobbin 6 is allowed to extend in the axial direction. Each spring 15
Are connected to both ends (not shown) of the electromagnetic coil 8 pulled out from the lid 6D of the coil bobbin 6, and both ends are electrically insulated from the coil bobbin 6 by a holder 14 or the like. .

The giant magnetostrictive actuator according to the present embodiment has the above-described configuration, and its operation will be described below.

First, a drive pulse is supplied from the outside of the casing 1 to the electromagnetic coil 8 via each terminal pin 12 as shown by a characteristic line 16 in FIG. 3, and a magnetic field is applied to the giant magnetostrictive rod 10 by the electromagnetic coil 8. The giant magnetostrictive rod 10 expands and deforms according to the strength of the magnetic field at this time, and lifts the push rod 4 downward with a lift amount as shown by a characteristic line 17 shown in FIG. The valve of the intake valve or the exhaust valve provided at the tip of the shaft portion 4B of the push rod 4 is driven in the valve opening direction. In this case, the upper end side end surface of the giant magnetostrictive rod 10 abuts against the stopper 6F of the coil bobbin 6 and the upward displacement is restricted. Therefore, the giant magnetostrictive rod 10 expands and deforms downward, and the push rod 4 To the valve opening direction of the valve body.

By the way, the giant magnetostrictive rod 10 thermally expands due to heat generation of the electromagnetic coil 8 or the like, and the length dimension L2 of the giant magnetostrictive rod 10 increases when the ambient temperature rises by t ° C. Is the thermal expansion amount according to the above equation (2)
Only axial displacement. In this case, the upper end surface of the giant magnetostrictive rod 10 is replaced with the stopper 6F of the coil bobbin 6, and the casing 1 is inserted via the lid or the like as described in the related art.
, The coefficient of thermal expansion α2 of the giant magnetostrictive rod 10 is larger than the coefficient of thermal expansion of the casing 1.
In the case of 0, upward expansion due to thermal expansion is restricted, and downward expansion occurs.

When the giant magnetostrictive rod 10 thermally expands downward, the push rod 4 is pushed downward, and in the worst case, the push rod 4 connects the valve body of the intake valve or the exhaust valve to the valve seat ( (Not shown) to cause a seal failure. When a drive pulse is supplied to the electromagnetic coil 8 to expand and deform the giant magnetostrictive rod 10, the thermal expansion of the giant magnetostrictive rod 10 is added to the amount of elongation.
The characteristic of the lift amount of the push rod 4 changes as indicated by a characteristic line 18 shown by a virtual line in FIG.

Therefore, in this embodiment, the coil bobbin 6 is formed in a cylindrical shape from a nonmagnetic material such as aluminum or brass having a relatively large coefficient of thermal expansion α1, and the length L1 of the coil bobbin 6 is set to The thermal expansion coefficient α2 of the rod 10 and the length dimension L2 are set so as to satisfy the relationship of the above equation (3), and the cover 6D side of the coil bobbin 6 is slidably inserted into the casing 1 and the flange portion. 6B is fixed to the casing 1 via the respective screws 7, so that the upper end side surface of the giant magnetostrictive rod 10 housed in the rod housing hole 6A is pressed against the stopper 6F, and the giant magnetostrictive rod 10 is Position in the direction.

Thus, when the giant magnetostrictive rod 10 thermally expands with the thermal expansion amount ΔL 2 due to heat generation of the electromagnetic coil 8, the coil bobbin 6 also has a corresponding thermal expansion amount ΔL 2.
1, the thermal expansion is performed so as to extend in the axial direction, so that the thermal expansion of the giant magnetostrictive rod 10 can be absorbed and offset on the stopper portion 6F side of the coil bobbin 6, allowing upward expansion due to the thermal expansion of the giant magnetostrictive rod 10, It can prevent downward elongation.

Each spring 15 is provided between each terminal pin 12 fixed to the lid 11 of the casing 1 and the lid 6D of the coil bobbin 6 via an insulating holder 14. Since the lower end is connected to both ends of the electromagnetic coil 8 wound around the coil bobbin 6, and the contact plate 15D on the upper end is resiliently contacted with the head 12A of each terminal pin 12 with a spring property. When the coil bobbin 6 thermally expands upward with the thermal expansion amount ΔL1, the contact plate portion 15D bends via the inclined plate portion 15C to allow the coil bobbin 6 to expand in the axial direction. And the terminal pins 12 can be maintained in a conductive state, and the coil bobbin 6 made of a metal material such as aluminum, brass or the like can be held by the insulating tape 9 and the insulating holder 14 or the like. It can be electrically insulated from the electromagnetic coil 8 and the springs 15.

Therefore, according to the present embodiment, it is possible to effectively prevent the lift amount of the push rod 4 from changing due to the thermal expansion of the giant magnetostrictive rod 10, and the push rod 4
By driving with a regular lift amount as shown by the characteristic line 17 in the middle, it is possible to eliminate the occurrence of problems such as sealing failure when the valve body is closed. Further, the spring load of the setting spring 5 can be prevented from changing due to the thermal expansion of the giant magnetostrictive rod 10, and the giant magnetostrictive rod 1 can be prevented from changing.
A constant initial load can be continuously applied to zero.

In the above embodiment, the giant magnetostrictive rod 10
Was described as being formed of a giant magnetostrictive material having a positive magnetostrictive property, but the present invention is not limited to this.For example, a giant magnetostrictive rod is formed of a giant magnetostrictive material having a negative magnetostrictive property, and this giant magnetostrictive When a magnetic field is applied to the rod, the push rod 4 or the like as a driving target may be driven with a desired lift amount.

Further, in the above embodiment, the case where the giant magnetostrictive actuator is applied to an intake valve or an exhaust valve of an engine has been described as an example, but the present invention is not limited to this.
For example, the present invention may be applied to an inward-opening type or an outward-opening type giant magnetostrictive injection valve.In this case, one end of the giant magnetostrictive rod is attached to a spool valve element or a poppet valve element to be driven. do it. Further, the present invention may be applied to a disc brake or the like. In this case, a configuration may be adopted in which the expansion and contraction deformation of the giant magnetostrictive rod is transmitted to a friction pad to apply a braking force to the disc.

[0044]

According to the present invention, as described in detail above, a coil bobbin made of a non-magnetic material having a required coefficient of thermal expansion is provided with a predetermined length based on the length of the giant magnetostrictive rod and the coefficient of thermal expansion. The one end side of the coil bobbin is fixed to the casing, and the other end side is a free end, so that the giant magnetostrictive rod is positioned in the casing in the axial direction. Even when thermal expansion occurs, the thermal expansion of the giant magnetostrictive rod can be offset by the thermal expansion of the coil bobbin, and the occurrence of poor characteristics can be effectively prevented.In addition, the lift amount of the push rod or the like to be driven is thermally expanded. Change can be prevented, and the occurrence of poor sealing or the like can be prevented.

Further, by providing a terminal pin on the other end of the casing and providing a conductive spring member between the terminal pin and the other end of the coil bobbin, the spring member is provided when the coil bobbin is thermally expanded. By bending the coil bobbin, the coil bobbin can be allowed to extend in the axial direction in the casing, and even when the coil bobbin is thermally expanded, the electric current can be reliably supplied from the terminal pin to the electromagnetic coil via the spring member. And the thermal expansion of the giant magnetostrictive rod can be reliably absorbed by the thermal expansion of the coil bobbin, and the characteristics can be stabilized and the reliability can be improved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a giant magnetostrictive actuator according to an embodiment of the present invention.

FIG. 2 is an exploded perspective view showing each terminal pin, holder and each spring in FIG. 1 in an enlarged manner.

FIG. 3 is a characteristic diagram showing a driving pulse and a lift amount of a push rod.

[Explanation of symbols]

 Reference Signs List 1 casing 2 rod guide 4 push rod (object to be driven) 5 setting spring 6 coil bobbin 6A rod storage hole 6B flange (one end) 6D lid (other end) 8 electromagnetic coil 9 insulating tape 10 giant magnetostrictive rod 12 terminal pin 14 Holder 15 Spring (spring member)

Claims (2)

(57) [Scope of request for utility model registration] 1. A magnetic device according to claim 1, wherein a magnetic field is applied to drive an object to be driven, which is provided in the casing and extends in the axial direction of the casing, and is provided at one end of the casing. A giant magnetostrictive rod that expands and contracts in the axial direction,
A coil bobbin provided around the giant magnetostrictive rod and provided in the casing, wound around the coil bobbin,
In a giant magnetostrictive actuator comprising an electromagnetic coil that applies a magnetic field to the giant magnetostrictive rod when energized from the outside, the coil bobbin is made of a nonmagnetic material having a required coefficient of thermal expansion, and the length of the giant magnetostrictive rod is A configuration in which the coil bobbin is fixed to the casing at one end and the giant magnetostrictive rod is axially positioned at the other end serving as a free end. And a giant magnetostrictive actuator. 2. A terminal pin for energizing the electromagnetic coil from the outside of the casing is provided at the other end of the casing, and one side is provided between the terminal pin and the other end of the coil bobbin. 2. The giant magnetostrictive actuator according to claim 1, further comprising a conductive spring member connected to the electromagnetic coil and having the other side elastically contacting the terminal pin.