JP2000257527A - Fuel injection valve - Google Patents

Abstract

(57) [Problem] To provide a fuel injection valve without changing the size of a gap between an output member of a giant magnetostrictive actuator and a valve body.
The dynamic characteristics of the giant magnetostrictive actuator can be adjusted by changing the magnitude of the elastic force applied to the giant magnetostrictive material. SOLUTION: A fuel injection valve I includes a giant magnetostrictive actuator A for displacing a piston 20 by giant magnetostrictive materials 15 and 16 which expand and contract by the action of a magnetic field, and a preload on the giant magnetostrictive materials 15 and 16 by urging the piston 20. And a nozzle hole 1 driven by a piston 20 to inject fuel.
It includes a valve body 27 for opening and closing the 2 ₁ and a valve spring 29 for urging the valve body 27 in the closing direction. By adjusting the elastic force of the valve spring 29 with the shim 30, the dynamic characteristics of the giant magnetostrictive actuator A can be changed without changing the gap α between the piston 20 and the valve body 27 already set by the preload spring 21. Can be adjusted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection valve which opens and closes a valve by a giant magnetostrictive actuator using a giant magnetostrictive material which expands and contracts under the action of a magnetic field.

[0002]

2. Description of the Related Art Among magnetostrictive materials that generate distortion in a magnetic field,
A rare earth metal single crystal such as Tb (terbium) or Dy (dysprosium) known as a giant magnetostrictive material generates a giant magnetostriction several hundred times that of a general magnetostrictive material such as Ni or Co. TbFe ₂ or DyFe ₂ which is a binary alloy of Tb and Fe or Dy and Fe can generate giant magnetostriction at room temperature, and is therefore used as a drive source for an actuator. A fuel injection valve using such a giant magnetostrictive actuator is known from JP-A-4-81565.

[0003]

In order to extend the giant magnetostrictive material of the giant magnetostrictive actuator by a magnetic field, it is necessary to apply a preload with a preload spring, and this preload compresses the giant magnetostrictive material to reduce its length. to shrink. The valve body is urged in the valve closing direction by a valve spring, so that the valve body can be securely seated on the valve seat when the giant magnetostrictive actuator is not operated. , A minute gap is formed. Therefore, when the giant magnetostrictive actuator is operated and the giant magnetostrictive material is extended, first, after the gap disappears and the output member comes into contact with the valve body, the giant magnetostrictive material is subjected to the elastic force of the preload spring and the valve. It extends against both spring forces of the spring.

In order to adjust the dynamic characteristics of the giant magnetostrictive actuator, it is necessary to adjust the resilient force of the preload spring. The amount of change changes the size of the gap between the output member of the giant magnetostrictive actuator and the valve body, and new dimensions such as changing the dimensions of the valve body to readjust the size of this gap Adjustment is necessary.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has been made in consideration of the elasticity applied to the giant magnetostrictive material without changing the size of the gap between the output member of the giant magnetostrictive actuator of the fuel injection valve and the valve element. It is an object of the present invention to adjust the dynamic characteristics of a giant magnetostrictive actuator by changing the magnitude of the generated force.

[0006]

According to the first aspect of the present invention, there is provided a giant magnetostrictive actuator for displacing an output member by a giant magnetostrictive material which expands and contracts under the action of a magnetic field. A preload spring for urging the member to preload the giant magnetostrictive material, a valve body driven by an output member to open and close a nozzle hole for injecting fuel, and a valve spring for urging the valve body in a valve closing direction And a small gap is formed between the valve element and the output member when the giant magnetostrictive actuator is not operating, and the output member resiliently acts on the preload spring and the valve spring when the giant magnetostrictive actuator operates. There has been proposed a fuel injection valve which is displaced against a force and is provided with adjusting means for adjusting the elastic force of a valve spring.

According to the above construction, when a magnetic field is applied to the giant magnetostrictive actuator, the giant magnetostrictive material expands against the resilience of the preload spring, and the piston is displaced to move the piston between the piston and the valve element. Small gaps disappear. Thereafter, the giant magnetostrictive material further expands against both the elastic force of the preload spring and the elastic force of the valve spring, thereby pressing the valve body with the piston to open the nozzle hole. The dynamic characteristics of the giant magnetostrictive actuator are determined by the sum of the spring force of the preload spring and the spring force of the valve spring. The gap between the piston and the valve body can be adjusted by setting the spring force of the preload spring in advance, and the dynamic characteristics of the giant magnetostrictive actuator can be adjusted by adjusting the spring force of the valve spring by adjusting means. It is possible. As described above, since the adjustment of the dynamic characteristics of the giant magnetostrictive actuator is performed only by the valve spring, the gap between the piston and the valve element already set by the preload spring does not change, and the dynamic characteristics and the The work of adjusting the gap becomes easy.

According to the invention described in claim 2,
A fuel injection valve is proposed, wherein the adjusting means is a shim mounted on an end of a valve spring.

According to the above configuration, the elasticity of the valve spring can be adjusted only by attaching the shim to the end of the valve spring, and the adjustment operation is extremely easy.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described based on embodiments of the present invention shown in the accompanying drawings.

1 to 4 show a first embodiment of the present invention. FIG. 1 is a longitudinal sectional view of a fuel injection valve, FIG. 2 is an enlarged view of a main part of FIG. 1, and FIG. FIG. 4 is an exploded perspective view of a main part of the giant magnetostrictive actuator.

As shown in FIG. 1, a fuel injection valve I used in a direct injection engine for natural gas has a substantially cylindrical housing 11, and a nozzle 1 is provided at a front end and a rear end thereof.
2 and cap 13 are respectively fixed. The giant magnetostrictive actuator A housed at the rear of the housing 11 for driving the fuel injection valve I includes a coil 14 as a magnetic field generating means, a first giant magnetostrictive material 15, a second giant magnetostrictive material 16, and a connecting member 17 And The front end of the coil 14 formed into a cylindrical shape and fitted on the inner peripheral surface of the housing 11 is
The housing 1 through the front guide member 18 having a 8 ₁
Is engaged with the first stepped portion 11 ₁ and the rear end of the coil 14 is engaged with the front surface of the cap 13 through the rear guide member 19 having guide holes 19 ₁ and the stopper surface 19 _2.

Referring to FIG. 4 together, it is clear that
First super magnetostrictive material 15, a super magnetostrictive material body 15 ₁ formed in a cylindrical shape, the front end member 15 ₂ and the rear end member 15 which is fixed to the front end and the rear end of the super magnetostrictive material body 15 _{1 3} and the rear end member 15 ₃
Stepped portion 15 ₄ are formed on the outer peripheral surface of the. Second giant magnetostrictive material 16
Includes a super magnetostrictive material body 16 ₁ formed in a cylindrical shape, each consist of a fixed front end member 16 ₂ and the rear end member 16 ₃ which the front and rear ends of the super magnetostrictive material body 16 _1, stepped portions 1 on the inner peripheral surface of the front end member 16 ₂
6 ₄ is formed. Connecting member 17 formed in substantially cylindrical in the non-magnetic material, which has a stepped portion 17 ₁ to the outer peripheral surface of the front side has a step portion 17 ₂ on the inner peripheral surface of the rear end.

Thus, the second giant magnetostrictive member 16 is arranged inside the coil 14 fitted and supported by the housing 11, the connecting member 17 is arranged inside the second giant magnetostrictive member 16, and the first giant magnetostrictive member 15 is arranged inside the coil. In this state, the housing 11, the coil 14, the second giant magnetostrictive material 16, the connecting member 17 and the first
The giant magnetostrictive material 15 is arranged concentrically with respect to the axis L of the fuel injection valve I.

The rear end member 16 _{3 of} the second giant magnetostrictive material 16
Is positioned in contact with the stopper surface 19 ₂ of the rear guide member 19, the front end member 16 ₂ is the front guide member 1
Slidably fitted to the inner circumference of the 8 of the guide hole 18 _1. Further, the step 16 of the front end member 16 ₂ of the second giant magnetostrictive material 16
₄ engages the front step 17 ₁ of the connecting member 17, and the rear step 17 ₂ of the connecting member 17 engages the step 15 ₄ of the rear end member 15 ₃ of the first giant magnetostrictive material 15. I do. At this time, the rear end member 15 ₃ of the first super magnetostrictive member 15 is slidably fitted into the guide hole 19 ₁ of the rear guide member 19.

The super magnetostrictive material body 16 ₁ of the first super magnetostrictive material body 15 ₁ and the second super magnetostrictive member 16 of the super magnetostrictive material 15, for example Terfenol D; composed of (Terfenol-D tradename). Terphenol D is composed of TbFe ₂ and D
An alloy combining yFe ₂ with a composition of 27% Tb
-30%, Dy 70% -73%, Fe 19% -20%, and has a property that the magnetic anisotropy constant is close to 0 due to positive magnetostriction (extending in the direction of the magnetic field).

[0017] As is clear with reference also to FIG. 2 and FIG. 3, the piston 20 is slidably fitted in the output member to the cylinder 11 ₂ formed in the peripheral front portion of the housing 11, this piston rod 20 ₁ from the piston 20 extending rearwardly abuts against the front end member 15 ₂ of the first super magnetostrictive member 15. Front of it if preload is housed in the cylinder 11 ₂ 21 is engaged with the rear end of the nozzle 12 via a collar 22 and a washer 23, its rear end is locked to the front surface of the piston 20. Accordingly, the piston 20 is urged rearward by the elastic force of the preload spring 21.

Nozzle hole 12 at the tip₁Nozzle 12 having
The valve seat 24 and the valve body support member 25 are housed inside the
A nut 26 having a thread formed on the outer peripheral surface is connected to the inner periphery of the nozzle 12.
It is fixed by screwing on the surface. Valve support member 25
Is a guide hole 25 passing through the center thereof in the axial direction.₁And 9
Four strips that are formed at 0 ° intervals and extend radially in the radial direction
Step 25_Two… And the rib 25_TwoNose around the outer edge of
Is positioned in the radial direction by contacting the inner peripheral surface of the
You. The valve body 27 has a head 27₁And shaft 27_TwoWith
Head 27₁Can be seated in front of the valve seat 24,
Shaft 27_TwoIs a guide hole 25 of the valve body support member 25.₁Nisuri
It is movably supported. Shaft 27 of valve body 27 _TwoAt the back end
A seat 28 is provided, and a front surface of the spring seat 28 and a valve are provided.
The valve spring 29 is supported between the body support member 25 in a compressed state.
It is. The head 27 of the valve body 27 is₁But
It is urged rearward and sits on the valve seat 24.

A shim 30 is mounted between the rear end of the valve spring 29 and the spring seat 28, and the preload of the valve spring 29 can be adjusted by changing the thickness of the shim 30.

A fuel supply hole 11 _{3 is} provided at the front of the housing 11.
There are formed, high-pressure fuel supplied from here to the cylinder 11 in the ₂ four ribs 25 of the valve support member 25 ₂ ...
Between the valve seat 24 and the head 27 _{1 of the} valve body 27.
It is injected from the nozzle hole 12 ₁ into the engine cylinder through the gap between.

Next, the operation of the fuel injection valve I having the above configuration will be described.

[0022] When the piston 20 by the elastic force of the cylinder 11 ₂ of the preload springs 21 housed within the compressed state is urged rearward, the front end member 15 to the piston rod 20 ₁
A compressive preload in the axial direction acts on the first giant magnetostrictive material 15 on which the _{second member 2} is pressed. Compressive preload acting on the first super magnetostrictive member 15 is transmitted from the stepped portion 15 ₄ of the rear end member 15 ₃ to the stepped portion 17 ₂ of the rear side of the connecting member 17, biasing the connecting member 17 rearward. Biasing force for biasing the connecting member 17 rearward is transmitted from the front side of the stepped portion 17 ₁ of the connecting member 17 to the front end member 16 _{and second} step portion 16 ₄ of the second super magnetostrictive member 16, as a result, the rear compressive preload in the axial direction acts the rear end member 16 ₃ to the second super magnetostrictive member 16 which is engaged with the guide member 19. The first giant magnetostrictive material 15 and the second giant magnetostrictive material 16 that have received the axial precompression load contract in the axial direction according to the magnitude of the compression preload.

[0023] When not performed by energization of the coil 14, the valve body 27 is urged rearward by the valve spring 29, the head 27 ₁ is seated on the valve seat 24. At this time, as the head 27 ₁ of the valve element 27 is not prevented from seating on the valve seat 24,
Gap alpha (see FIG. 2) of the preset size between the front of the shaft portion 27 ₂ of the rear end the piston 20 of the valve body 27 is formed.

When the coil 14 of the giant magnetostrictive actuator A is energized by a command from the fuel injection amount control device in order to supply fuel to the engine, the first giant magnetostrictive material is generated according to the magnitude of the magnetic field generated by the coil 14. 15 and the second giant magnetostrictive material 16 elongate against the compression preload. Second super magnetostrictive member 16 which is engaged with the rear end member 16 ₃ to the rear guide member 19, the front end member 16 ₂ is moved forward by the extension of the super magnetostrictive material body 16 _1, the front end member 1
6 ₂ of the step portion 16 ₄ on the front side of the stepped portion 17 ₁ locked the connecting member 17 to move forward. The displacement force for moving the connecting member 17 forward is changed from the step 17 ₂ on the rear side of the connecting member 17 to the step 15 of the rear end member 15 ₃ of the first giant magnetostrictive material 15.
₄ is transmitted to, as a result, the rear end member 15 ₃ of the first super magnetostrictive member 15 moves forward by the expansion amount of the second super magnetostrictive member 16. And by super magnetostrictive material body 15 ₁ of the first super magnetostrictive member 15 in accordance with the magnitude of the magnetic field coil 14 is generated is expanded against the compressive preload, front-end member of the first super magnetostrictive member 15 15 ₂ is moved forward relative to the rear end member 15 _3.

Thus, the extension amount of the first giant magnetostrictive material 15 and the second
The piston 20 is displaced forward by a distance corresponding to the sum of the amount of extension of the giant magnetostrictive material 16. Piston 20 is a gap α is clogged between the shaft portion 27 ₂ of the valve body 27 when displaced forward, the valve body 27 is pressed by the piston 20 moves forward against the elastic force of the valve spring 29, the valve body The head 27 ₁ of 27 is separated from the valve seat 24. As a result, the cylinder 1 from the fuel supply hole 11 ₃
1 high-pressure fuel supplied into the _2, the head of the valve element 27 27
It is injected from the nozzle holes 12 ₁ through the gap ₁ and the valve seat 24. Therefore, by changing the opening and closing times of the gap of the head 27 ₁ and the valve seat 24 of the valve element 27 by the pulse width control energization to the coil 14 or coil, 1
4 to change the size of the gap of the head 27 ₁ and the valve seat 24 of the valve body 27 by controlling the magnitude of current applied to the can be arbitrarily controlled fuel injection amount.

As described above, the first giant magnetostrictive material 15, the connecting member 17, the second giant magnetostrictive material 16, and the coil 14 are coaxially arranged around the axis L so as to be sequentially superposed from the radially inner side to the outer side. The giant magnetostrictive actuator A can be made compact. Moreover, the first giant magnetostrictive material 15,
Since all loads of the connecting member 17 and the second giant magnetostrictive material 16 act on the axis L, the first giant magnetostrictive material 15 and the connecting member 17
In addition, it is possible to prevent the asymmetric deformation of the second giant magnetostrictive material 16 around the axis L, effectively transmit the load, and ensure the smooth operation of the giant magnetostrictive actuator A. In addition, since the connecting member 17 has no fulcrum or sliding portion, it has a very simple structure, and it is possible to reduce the number of parts and the number of assembling steps, as well as to improve the durability and reduce the failure rate. can do. In addition, by employing the coil 14 as the magnetic field generating means, the giant magnetostrictive actuator A can be operated only by changing the pulse width of the current or the magnitude of the applied current.
Can be easily and precisely controlled.

When the coil 14 is energized to operate the giant magnetostrictive actuator A, the first
The preload spring 2 is applied to the giant magnetostrictive material 15 and the second giant magnetostrictive material 16.
Since the resilient force of the valve spring 29 simultaneously acts in addition to the resilient force of (1), the sum of the resilient forces of both the preload spring 21 and the valve spring 29 affects the dynamic characteristics of the giant magnetostrictive actuator A. become. In order to adjust the sum of the resilient forces, a first method for adjusting both the resilient force of the preload spring 21 and the resilient force of the valve spring 29, and only the resilient force of the preload spring 21 is adjusted. A second method for adjusting the spring force of the valve spring 29 and a third method for adjusting only the elastic force of the valve spring 29 can be considered.

However, if the resilience of the preload spring 21 is changed, the amount of contraction of the first and second giant magnetostrictive members 15 and 16 due to the preload changes, so that the front surface of the piston 20 and the shaft of the valve body 27 are changed. the size of the gap α between the parts 27 ₂ trailing ends up changing, becomes necessary a new adjustment of the replacement of the valve body 27. Therefore, the first method and the second method including the change of the resilient force of the preload spring 21 are not preferable. On the other hand, in the third method for adjusting only the resilient force of the valve spring 29, the resilient force of the valve spring 29 is controlled when the giant magnetostrictive actuator A is not operated by the first giant magnetostrictive material 15 and the second giant magnetostrictive material. 16 is not transmitted, the problem that the size of the gap α changes does not occur.

That is, the resilience of the preload spring 21 is set in advance to a value at which a desired gap α can be obtained, and in this state, the resilience of the valve spring 29 is adjusted by the thickness of the shim 30. , The sum of the resilient forces of both the preload spring 21 and the valve spring 29 can be adjusted to a size at which the desired dynamic characteristic can be obtained, and the gap α can be adjusted by adjusting the resilient force of the valve spring 29. The size does not change. As described above, the dynamic characteristics of the giant magnetostrictive actuator A can be easily adjusted without changing the size of the gap α by a simple operation of only changing the thickness of the shim 30 supporting one end of the valve spring 29. Can be.

In the first embodiment, the shim 30 is arranged between the rear end of the valve spring 29 and the front surface of the piston 20.
Similar effects can be obtained by arranging the shim 30 between the front end of the valve spring 29 and the rear surface of the valve body support member 25 as in the second embodiment shown in FIG.

Although the embodiments of the present invention have been described in detail, various design changes can be made in the present invention without departing from the gist thereof.

For example, in the embodiment, the fuel injection valve I for natural gas is illustrated, but the present invention can be applied to a fuel injection valve of any other fuel. The adjustment of the resilience of the valve spring 29 can also be performed by means other than the shim 30 (for example, the thickness of the valve seat 24).

[0033]

As described above, according to the first aspect of the present invention, when a magnetic field is applied to the giant magnetostrictive actuator, the giant magnetostrictive material expands against the elastic force of the preload spring, and the piston moves. The displacement causes the minute gap between the piston and the valve body to disappear. Thereafter, the giant magnetostrictive material further extends against both the elastic force of the preload spring and the elastic force of the valve spring, thereby pressing the valve body with the piston to open the nozzle hole.
The dynamic characteristics of the giant magnetostrictive actuator at this time are determined by the sum of the resilient force of the preload spring and the resilient force of the valve spring. The gap between the piston and the valve body can be adjusted by setting the spring force of the preload spring in advance, and the dynamic characteristics of the giant magnetostrictive actuator can be adjusted by adjusting the spring force of the valve spring by adjusting means. It is possible. As described above, since the dynamic characteristics of the giant magnetostrictive actuator are adjusted only by the valve spring,
The gap between the piston and the valve element, which has already been set, does not change due to the preload spring, and the work of adjusting the dynamic characteristics and the gap becomes easy.

According to the second aspect of the present invention,
Since the elasticity of the valve spring can be adjusted only by attaching a shim to the end of the valve spring, the adjustment operation is extremely easy.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a fuel injection valve.

FIG. 2 is an enlarged view of a main part of FIG. 1;

FIG. 3 is a sectional view taken along line 3-3 in FIG.

FIG. 4 is an exploded perspective view of a main part of the giant magnetostrictive actuator.

FIG. 5 corresponds to FIG. 2 according to a second embodiment of the present invention.

[Explanation of symbols]

12 ₁ Nozzle hole 15 1st giant magnetostrictive material (giant magnetostrictive material) 16 2nd giant magnetostrictive material (giant magnetostrictive material) 20 Piston (output member) 21 Preload spring 27 Valve element 29 Valve spring 30 Shim (adjustment means) A Super Magnetostrictive actuator α gap

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Hiroyuki Goto 1-4-1 Chuo, Wako-shi, Saitama F-term in Honda R & D Co., Ltd. (Reference) 3G066 AA02 AB02 AB05 AD12 BA46 BA54 BA56 BA57 BA61 BA67 CC06U CC14 CC40 CC51 CC57 CE27

Claims (2)

[Claims] A giant magnetostrictive material that expands and contracts under the action of a magnetic field.
A giant magnetostrictive actuator (A) for displacing the output member (20) by 16), a preload spring (21) for urging the output member (20) to preload the giant magnetostrictive materials (15, 16), A valve element (27) for opening and closing a nozzle hole (12 ₁ ) driven by the output member (20) for injecting fuel; a valve spring (29) for urging the valve element (27) in a valve closing direction;
When the giant magnetostrictive actuator (A) is not operated, a minute gap (α) is formed between the valve body (27) and the output member (20), and when the giant magnetostrictive actuator (A) is operated, the output member ( Reference numeral 20) denotes a fuel injection valve which is displaced against the resilience of the preload spring (21) and the resilience of the valve spring (29), and is an adjusting means for adjusting the resilience of the valve spring (29). A fuel injection valve comprising (30). 2. The method according to claim 1, wherein said adjusting means (30) is a valve spring (29).
The fuel injection valve according to claim 1, wherein the fuel injection valve is a shim attached to an end of the fuel injection valve.