JP2004360470A - Fuel injection valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection valve having excellent responsiveness and capable of accurately and stably performing opening/closing operations for a long period. <P>SOLUTION: In this fuel injection valve, a movable iron core 23 and a valve element 24 are fixed to a plate spring-made return spring 17, and reciprocatingly moved in a floated state. A nonmagnetic cylindrical contact member 26 to bring the compression of a cushioning layer 25 installed at the tip face of a fixed iron core 10 into an elastic deformation range is installed on the tip outer peripheral surface thereof. The contact member 26 is closely fitted to a fitting hole 28 using, as a center, the centerline N-N of the fixed iron core 10 fitted to a nonmagnetic holding member 27 to position the fixed iron core 10 and the movable iron core 23 on the centerline N-N. Since the cushioning layer 25 and the contact member 26 make constant the suction stroke of the movable iron core 23 and stabilizes the valve opening amount of the valve element 24. Thus, the responsiveness can be improved by securing a release voltage. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a fuel injection valve that controls fuel supplied to an engine by an electric signal sent from an electronic control device and injects the fuel into an intake pipe.
[0002]
[Prior art]
It is extremely short to make the valve body perform the opening operation by the electromagnetic force when the electric signal output by the electronic control device is energized in accordance with the operation state of the engine, and perform the closing operation by the return spring when the energization is not performed. 2. Description of the Related Art In a fuel injection valve that continuously injects fuel by repeating over time, it is necessary that a valve body responds sharply to an electric signal and that a predetermined opening / closing operation is performed accurately and stably for a long time. It is.
[0003]
Regarding the responsiveness, the return spring is, for example, disclosed in Japanese Unexamined Patent Application Publication No. 9-1990, compared to a coil spring inserted between a fixed iron core and a movable iron core as described in Japanese Utility Model Laid-Open No. 55-180066. It is more advantageous to use a disc-shaped leaf spring in which a peripheral portion is fixed and a movable core and a valve body are fixed to a center portion as described in JP-A-79107. This is because the movable core and the valve element reciprocate in a floating state without any sliding portion.
[0004]
FIG. 2 is a longitudinal sectional view showing an example of a fuel injection valve using a disc-shaped leaf spring as a return spring. A fixed iron core 54 is provided in the center of a coil case 53 provided in an outer case 51 in a penetrating state. The movable iron core 55 facing the distal end surface of the fixed iron core 54 and the valve body 57 facing the valve seat 56 are fixed to the center of the return spring 58. When the coil 52 is energized, a magnetic circuit composed of the outer case 51 → the spacer plate 59 → the movable core 55 → the fixed core 54 → the outer case 51 is formed. The movable core 55 is attracted to the fixed core 54 and the valve body 57 is moved to the valve seat 58. As a result, the fuel is injected from the injection port 60.
[0005]
In the above-described fuel injection valve, the fixed iron core 54 is held by screwing the base end into a screw hole 61 provided on the outer side of the base end of the outer case 51 as shown in FIG. Alternatively, as shown in the drawing of Japanese Patent Application Laid-Open No. 9-79107, the base end portion is fitted into the outer case 51 and the coil case 53 and is held by an O-ring or the like, and is on the same center line as the movable iron core 55. Be deployed. However, when the screw or the fitting portion has a slight inclination, the fixed iron core 54 is inclined with respect to the center line, penetrates through the coil case 53, and has a suction surface 54A which is a front end surface thereof and a suction surface of the movable iron core 55 facing the suction surface 54A. 55A becomes non-parallel, and when the coil 52 is energized, the suction surface 55A hits the suction surface 54A. When the suction surface 54A and the suction surface 55A are unevenly worn due to the one-sided contact, the valve opening stroke of the valve body 57 changes to change the fuel injection amount. Further, when the suction surface 55A attempts to suction the entire surface of the suction surface 54A, the movable iron core 55 tilts and comes into contact with the spacer plate 59 to cause malfunction, or an uneven load acts on the return spring 58 to cause early deterioration or breakage. This makes it impossible to meet the demand for accurate and stable predetermined opening and closing operations over a long period of time.
[0006]
As a countermeasure, it is conceivable to lengthen the screw portion or the fitting holding member so that the inclination is offset as a whole. However, the outer case 51 and the fixed iron core 54 become longer, and the entire fuel injection valve becomes larger. Not only is the weight increased, but it is also susceptible to vibrations of the engine and the like, and there is a concern that the mounting portion to the intake pipe may be loosened.
[0007]
[Problems to be solved by the invention]
The present invention meets the second requirement that the fuel injection valve using the return spring as a leaf spring has the first requirement of excellent responsiveness, but performs the predetermined opening and closing operation accurately and stably for a long period of time. A fuel which has been made in order to solve the above-mentioned problem that it may not be possible, and which can completely satisfy the first and second requirements without increasing the size and weight of the whole. It is intended to provide an injection valve.
[0008]
[Means for Solving the Problems]
According to the present invention, a fixed core having a base end held by the outer case is penetrated and arranged at the center of a coil case housed in the outer case, and is disposed on the same center line as the fixed core and faces the distal end surface. The valve element facing the movable core and the valve seat is fixed to the center of the return spring composed of a leaf spring, and the movable core and the valve element reciprocate in a floating state in response to energization / de-energization of the coil. The above problem has been solved by a fuel injection valve that injects fuel intermittently as follows.
[0009]
That is, the fixed iron core has a thin plate-shaped buffer layer on the distal end surface, and has a contact member made of a hard cylinder on the outer peripheral surface of the distal end portion with the distal end surface being slightly retracted from the surface of the buffer layer. At the same time, a holding member made of a non-magnetic material having a fitting hole centered on the center line is installed in front of the distal end of the coil case, and a fixed iron core closely fits the member into the fitting hole so that the center line is formed. And concentrically.
[0010]
According to the present invention as described above, since the fixed core whose base end is held in the outer case by screwing or fitting is tightly fitted into the fitting hole of the holding member with its leading end held concentrically, The inclination caused by the attachment of the ends is corrected, and the suction surface of the fixed iron core and the suction surface of the movable iron core become parallel, thereby achieving both excellent responsiveness and accurate and stable opening and closing operation for a long period of time. It becomes possible easily.
[0011]
Further, when both the buffer layer and the contact member are made of a non-magnetic material, the responsiveness of the valve opening operation when the current is not supplied to the coil is improved, and in addition, the contact member and the holding member are separated from each other. Both are made of a non-magnetic material, and together with the improvement of the magnetic characteristics, the response can be further improved. Furthermore, if the compression of the buffer layer is limited to the range of elastic deformation, the fixed member and the movable core are arranged on the same center line. Therefore, it is possible to more reliably achieve the object of performing accurate and stable opening / closing operation for a long period of time by eliminating uneven wear.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Referring to FIG. 1, an embodiment of the present invention will be described. An outer case 1 has an end cover 3 integrally provided at a base end of a cylindrical case main body 2 and a holding nut 4 provided at the center of the end cover 3. ing. Further, a cylindrical wall 7A protruding from a base end of a coil case 7 holding a coil 6 is fitted to a holding nut 4, and an O-ring 8 mounted on a flange 7B at a distal end is inscribed in the case main body 2 so as to form an outer case. 1 is concentrically furnished.
[0013]
Further, the fixed core 10 is held in the outer case 1 by screwing a male screw 11 provided on the outer peripheral surface of the base end portion into the screw hole 5 of the holding nut 4, and the fixed core 10 is attached to the cylindrical wall 7 </ b> A of the coil case 7. The center hole 9 is held by the O-ring 12 and penetrates through the center hole 9.
[0014]
On the other hand, a spacer plate 15 superposed on the flange 7B and a valve seat holder 18 superposed on the spacer plate 15 with the outer peripheral edge of a return spring 17 formed of a disc-shaped leaf spring interposed therebetween are arranged at the tip of the outer case 1. These are fixed to the outer case 1 by a bent portion 2A formed by bending the case main body 2. The valve seat holder 18 has a valve seat 19 fitted and fixed at the center, has an injection port 20, and has a fuel chamber 22 which is a space sandwiched between the return spring 17 and the valve seat holder 18. Is provided on the outer side of the valve seat 19.
[0015]
The movable iron core 23 and the valve element 24 are fixed to the center of the return spring 17 in opposite directions to each other and sandwich the return spring 17 therebetween. The movable iron core 23 is loosely fitted in the center hole 16 of the spacer plate 15, and a surface of the fixed iron core 10 facing the suction surface 10 </ b> A, which is a distal end surface, forms a suction surface 23 </ b> A. The holding nut 4, the coil case 7, the fixed iron core 10, the movable iron core 23, the valve element 24, and the valve seat 19 are arranged on the same center line N-N.
[0016]
In the present embodiment, a thin buffer layer 25 made of a non-magnetic and elastic material, for example, rubber, is stacked on the suction surface 10A of the fixed iron core 10 to reduce the collision sound and secure the open voltage. A contact member 26 formed of a cylindrical body is mounted on the outer peripheral surface of the distal end portion of the fixed iron core 10 surrounding the buffer layer 25. The tip surface of the contact member 26 is slightly retracted from the surface of the buffer layer 25, and the contact member 26 stops when the movable core 23 is attracted to the fixed core 10 and compresses the buffer layer 25 within the elastic deformation range. Thus, the buffer layer 25 is prevented from being deteriorated early due to repeated compression.
[0017]
On the surface of the spacer plate 15 facing the coil case 7, an annular holding member 27 surrounding the opening end of the center hole 16 is fixedly installed by fitting of annular unevenness. A fitting hole 28, which is a hollow hole of the holding member 27, is concentric with the center line N-N, and a tip end portion of the fixed iron core 10 protruding from a tip end of the coil case 7 connects the hitting member 26 to the fitting hole 28. And is concentric with the fitting hole 28 by being fitted closely.
[0018]
The contact member 26 can be made of a magnetic material, but in the present embodiment, both the contact member 26 and the holding member 27 are made of a hard non-magnetic material, for example, SUS304 selected from a high-hard synthetic resin or stainless steel. It was made of a material subjected to a nitrification treatment.
[0019]
In the present embodiment having such a configuration, when the coil 6 is de-energized, the contact surface 24A of the valve body 24 is brought into close contact with the seat surface 19A of the valve seat 19 by the spring force of the return spring 17, and the valve seat 22 and the valve passage are connected. 19A and the movable iron core 23 is separated from the fixed iron core 10. When the coil 6 is energized, the hitting member 26 and the holding member 27 are made of a non-magnetic material, so that a magnetic circuit of the outer case 1 → spacer plate 15 → movable core 23 → fixed iron core 10 → outer case 1 is formed. When 23 is sucked into the fixed iron core 10 and the valve body 24 moves away from the valve seat 19, the fuel in the valve chamber 22 is injected from the injection port 20 through the valve passage 19A.
[0020]
Here, in the present embodiment in which the base end of the fixed core 10 is held in the outer case 1 by screw fitting with the holding nut 4, if the male screw 11 or the screw of the screw hole 5 has a slight inclination, the fixed core is fixed. 10 is inclined with respect to the center line N-N, and this inclination cannot be corrected by the O-ring 12, but the tip end portion is densely inserted into the fitting hole 28 concentric with the center line N-N of the holding member 27. By being fitted, the inclination is forcibly corrected, and the fixed iron core 10 is held concentrically with the center line N-N.
[0021]
For this reason, the suction surface 10A of the fixed iron core 10 and the suction surface 23A of the movable iron core 23 are parallel to each other, and when the coil 6 is energized, the suction surface 23A compresses the buffer layer 25 evenly and the leading end of the contact member 26 Stops in close contact with the entire surface. In this valve opening operation, the contact member 26 and the holding member 27 are non-magnetic, so that the magnetic leakage is small, the magnetic circuit is formed with a high magnetic flux density, the valve opening operation is started responsively, and the valve body 24 is opened. The valve opening stroke can always be constant. Since the contact member 26 is provided on the outer peripheral surface of the fixed iron core 10, the movable iron core 23 can be stably and closely adhered on a large diameter so that the opening degree of the valve body 24 can be always kept constant, and even if it is made thinner. The contact area of the movable iron core 23 is large, so that the collision load can be reduced and damage at the contact point can be prevented.
[0022]
When the coil 6 is de-energized, the non-magnetic buffer layer 25 and the contact member 26 are sandwiched between the suction surface 10A and the adsorption surface 23A, and the open voltage is secured. Is started in a responsive manner, and in combination with the fact that the valve opening stroke is constant, a predetermined amount of fuel can always be injected accurately.
[0023]
In the present embodiment, the holding member 27 is fixedly set to the spacer plate 15 using the space between the coil case 7 and the spacer plate 15, and in addition, the contact member 26 is located outside the distal end of the fixed iron core 10. Since it is mounted on the peripheral surface, the fixed iron core 10 is installed concentrically with the center line N-N without increasing the size and weight of the injection valve as a whole. Can be performed.
[0024]
【The invention's effect】
As described above, according to the present invention, the response of the valve body to electric signals is improved without increasing the size and weight of the whole, and the predetermined opening / closing operation can be performed accurately and stably for a long time. Thus, it is possible to always inject an accurate predetermined amount of fuel.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention.
FIG. 2 is a longitudinal sectional view showing a conventional example.
[Explanation of symbols]
Reference Signs List 1 outer case, 6 coil, 7 coil case, 10 fixed iron core, 15 spacer plate, 17 return spring, 19 valve seat, 23 movable iron core, 24 valve body, 25 buffer layer, 26 contact member, 27 holding member

Claims (3)

A fixed core whose base end is held by the outer case is penetrated and arranged at the center of the coil case housed in the outer case, and is movable on the same center line as the fixed core and opposed to the tip surface. A valve body facing the iron core and the valve seat is fixed to the center of a return spring composed of a leaf spring, and the movable iron core and the valve body reciprocate in a floating state corresponding to energization / de-energization of the coil. In a fuel injection valve that injects fuel intermittently,
The fixed iron core has a thin plate-shaped buffer layer on the distal end surface, and has a contact member made of a hard cylinder on the outer peripheral surface of the distal end portion with the distal end surface being slightly retracted from the surface of the buffer layer. A holding member made of a hard non-magnetic material having a fitting hole centered on a center line is provided at the front end of the coil case, and the fixed iron core closely fits the contact member into the fitting hole. Held concentrically with said center line,
A fuel injection valve characterized in that: 2. The fuel injection valve according to claim 1, wherein both the buffer layer and the contact member are made of a non-magnetic material. 2. The fuel injection valve according to claim 1, wherein the contact member limits the buffer layer to a compression within an elastic deformation range when the movable core is attracted to the fixed core.

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