JP4106610B2 - Fuel injection valve - Google Patents

Description

[0001]
BACKGROUND 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 unit and injects the fuel into an intake pipe.
[0002]
[Prior art]
It is extremely short to cause the valve body to open by the electromagnetic force when the electric signal output from the electronic control unit is energized according to the operating state of the engine, and to cause the valve body to perform the closing operation by the return spring when not energized. In a fuel injection valve that continuously injects fuel by repeating over time, it is necessary for the valve body to respond sensitively to electrical signals and to perform a predetermined opening and closing operation accurately and stably over a long period of time. It is.
[0003]
With respect to the responsiveness, for example, the return spring is compared with 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, for example, It is more advantageous to use a disc-shaped leaf spring in which a peripheral edge portion is fixed and a movable iron core and a valve body are fixed to the center portion as described in Japanese Patent No. 79107. This is because the movable iron core and the valve body reciprocate in a floating state without having a sliding portion.
[0004]
FIG. 2 is a longitudinal sectional view showing an example of a fuel injection valve using a disk-shaped leaf spring as a return spring. A fixed iron core 54 is provided in a through state at the center of a coil case 53 housed in an outer case 51. In addition, a movable iron core 55 facing the front end surface of the fixed iron core 54 and a 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 comprising the outer case 51 → the spacer plate 59 → the movable iron core 55 → the fixed iron core 54 → the outer case 51 is formed, and the movable iron core 55 is attracted to the fixed iron core 54 and the valve element 57 is moved to the valve seat 58. The fuel is injected from the injection port 60 by moving away from.
[0005]
In the fuel injection valve, as shown in FIG. 2, is the fixed iron core 54 held by screwing the base end portion into the screw hole 61 provided in the base end outer portion of the outer case 51? Alternatively, 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 disposed on the same center line as the movable iron core 55. However, if the screw or the fitting portion is slightly inclined, the fixed iron core 54 is inclined with respect to the center line and penetrates the coil case 53, and the suction surface 54A that is the front end surface of the fixed iron core 54 and the adsorption surface of the movable iron core 55 that faces it. When the coil 52 is energized, the suction surface 55A comes into contact with the suction surface 54A. When the suction surface 54A and the suction surface 55A are unevenly worn due to this single contact, the valve opening stroke of the valve body 57 changes to change the fuel injection amount. Further, if the suction surface 55A is about to be attracted to the suction surface 54A, the movable iron core 55 tilts and contacts the spacer plate 59, resulting in a malfunction, or an eccentric load acts on the return spring 58 to cause early deterioration or breakage. This causes a problem of causing a problem, and it becomes impossible to meet a demand for performing a predetermined opening / closing operation accurately and stably over a long period of time.
[0006]
As a countermeasure, it is conceivable to lengthen the screw part and the fitting holding member so that the inclination is offset as a whole. However, the outer case 51 and the fixed iron core 54 are lengthened to enlarge the whole fuel injection valve. Not only does this increase the weight, it is likely to be affected by vibrations of the engine and the like, and there is a concern that the attachment to the intake pipe will loosen.
[0007]
[Problems to be solved by the invention]
The fuel injection valve having a leaf spring as a return spring is excellent in responsiveness, which is the first requirement, but meets the second requirement that a predetermined opening / closing operation be performed accurately and stably over a long period of time. A fuel injection valve that has been made to solve the above-mentioned problem that there are cases where it cannot be performed, and that can satisfy the first and second requirements without increasing the overall size and weight. The purpose is to provide.
[0008]
[Means for Solving the Problems]
In the present invention, a fixed iron core having a base end held in the outer case is disposed through the center of the coil case installed in the outer case, and is disposed on the same center line as the fixed iron core so as to face the tip surface thereof. The movable iron core and the valve body facing the valve seat are fixed to the center of the return spring consisting of a leaf spring, and the movable iron core and valve body reciprocate in a floating state in response to energization / non-energization of the coil. About the fuel injection valve which injects fuel intermittently, the said subject was solved by doing as follows.
[0009]
That is, a holding member made of a non-magnetic material having a fitting hole centered on the center line of the fixed core is installed in front of the tip of the coil case, and the tip of the fixed core protruding from the tip of the coil case is used as the fitting hole. It was assumed that it was tightly fitted and held concentrically by the holding member.
[0010]
According to the present invention as described above, since the fixed iron core whose base end portion is held in the outer case by screwing or fitting is tightly fitted into the fitting hole of the holding member and held concentrically, The inclination caused by the attachment of the end is corrected, and the suction surface of the fixed iron core and the suction surface of the movable iron core become parallel. Therefore, the objective of achieving both excellent responsiveness and accurate and stable opening / closing operation over a long period of time can be achieved without increasing the size and weight of the entire injection valve.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described with reference to FIG. 1. The outer case 1 has an end cover 3 integrally formed at the base end of a cylindrical case body 2 and a holding nut 4 is provided at the center of the end cover 3. ing. A cylindrical wall 7A projecting from the base end of a coil case 7 holding the coil 6 is fitted into the holding nut 4 and an O-ring 8 attached to the flange 7B at the distal end is inscribed in the case main body 2 so as to be in outer case. 1 is concentrically furnished.
[0012]
Further, the fixed iron core 10 is held by 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 iron core 10 is held by the cylindrical wall 7 </ b> A of the coil case 7. The center hole 9 that is continuous with the O-ring 12 passes through the center hole 9 and the tip end portion projects forward of the tip end of the coil case 7.
[0013]
On the other hand, at the front end of the outer case 1, a spacer plate 15 stacked on the flange 7 </ b> B and a valve seat holder 18 stacked on the spacer plate 15 sandwiching the outer peripheral edge of a return spring 17 made of a disc-shaped plate spring are arranged. These are fixed to the outer case 1 by a folding part 2A formed by bending the case 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 fuel in a valve chamber 22 that is a space sandwiched between the return spring 17 and the valve seat holder 18. The fuel passage 21 for introducing the fuel is provided on the outer side of the valve seat 19.
[0014]
At the center of the return spring 17, the movable iron core 23 and the valve body 24 are fixed in opposite directions and with the return spring 17 interposed therebetween. The movable iron core 23 is loosely fitted in the center hole 16 of the spacer plate 15, and the surface facing the suction surface 10 </ b> A that is the tip surface of the fixed iron core 10 forms an adsorption surface 23 </ b> A. And the holding nut 4, the coil case 7, the fixed iron core 10, the movable iron core 23, the valve body 24, and the valve seat 19 are arrange | positioned on the same centerline NN.
[0015]
In the present embodiment, a thin buffer layer 25 made of an elastic material for reducing impact noise and securing an open voltage is laminated on the suction surface 10A of the fixed iron core 10, and the buffer layer 25 is surrounded by a hard material. A contact member 26 made of a metal cylinder is mounted on the outer peripheral surface of the distal end portion of the fixed iron core 10. The front end 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 the buffer layer 25 is compressed within the elastic deformation range. The buffer layer 25 is prevented from premature deterioration due to repeated excessive compression.
[0016]
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 annular unevenness. The holding member 27 is made of a high-hardness nonmagnetic material, such as SUS304 selected from hard synthetic resin or stainless steel, and is subjected to a nitriding treatment, and the insertion hole 28 that is a hollow hole has a center line NN. And the tip of the fixed iron core 10 protruding from the tip of the coil case 7 is closely fitted.
[0017]
In the present embodiment configured as above, 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 when the coil 6 is not energized. The movable iron core 23 is separated from the fixed iron core 10 while being disconnected from 19A. When the coil 6 is energized, since the holding member 27 is made of a nonmagnetic material, a magnetic circuit of the outer case 1 → the spacer plate 15 → the movable iron core 23 → the fixed iron core 10 → the outer case 1 is formed, and the movable iron core 23 becomes the fixed iron core. 10, the valve body 24 moves away from the valve seat 19, whereby the fuel in the valve chamber 22 is injected from the injection port 20 through the valve passage 19 </ b> A.
[0018]
Here, in the present embodiment in which the base end portion of the fixed iron 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 iron core is fixed. 10 is inclined with respect to the center line NN, and this inclination cannot be corrected by the O-ring 12. However, the tip end portion is closely fitted in the fitting hole 28 concentric with the center line NN of the holding member 27. By inserting, the inclination is forcibly corrected, and the fixed iron core 10 is held concentrically with the center line NN.
[0019]
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 adsorbs the entire surface without hitting the suction surface 10A. These surfaces 10A and 23A are unevenly worn to cause a change in the valve opening stroke of the valve body 24 and deviate the fuel injection amount, and the movable iron core 23 comes into contact with the hole wall of the center hole 16 in an attempt to attract the entire surface. Thus, the inconvenience of causing a malfunction, and the inconvenience that an offset load acts on the return spring 17 to cause early deterioration or breakage are all eliminated.
[0020]
In addition, since the movable iron core 23 and the valve body 24 are fixed to the plate-like return spring 17 and do not have a sliding portion, and are reciprocated by a magnetic force and a spring force in a floating state, the responsiveness is not only excellent. Since the holding member 27 is fixedly installed on the spacer plate 15 using the space between the coil case 7 and the spacer plate 15, the fixed iron core 10 can be formed without increasing the size and weight of the entire injection valve. It can be installed concentrically with the center line NN.
[0021]
【The invention's effect】
As described above, according to the present invention, the responsiveness of the valve body to an electrical signal is improved without increasing the overall size and weight, and the predetermined opening / closing operation can be accurately and stably performed over a long period of time. Can be made compatible with what can be done.
[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]
DESCRIPTION OF SYMBOLS 1 Outer case, 6 coil, 7 coil case, 10 fixed iron core, 10A suction surface, 15 spacer plate, 17 return spring, 19 valve seat, 23 movable iron core, 23A adsorption surface, 24 valve body, 27 holding member, 28 fitting Hole

Claims (1)

A fixed iron core with a base end held in the outer case is penetrated through the center of the coil case installed in the outer case, and the movable iron core is disposed on the same center line as the fixed iron core and faces the tip surface thereof. A valve body facing the iron core and the valve seat is fixed to the center of a return spring consisting of a leaf spring, and the movable iron core and valve body reciprocate in a floating state in response to energization / non-energization of the coil. In a fuel injection valve that injects fuel intermittently,
A spacer in which a holding member made of a non-magnetic material having a fitting hole centered on the center line of the fixed iron core is overlapped on the tip of the coil case, and the outer peripheral edge of the return spring is sandwiched and fixed in cooperation with the valve seat holder It is fixed to a plate and installed in front of the tip of the coil case, and the fixed iron core is tightly fitted into the fitting hole at the tip protruding from the tip of the coil case and held concentrically by the holding member. ing,
The fuel injection valve characterized by the above-mentioned.

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