JP2002227742A - Fuel injection valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate deterioration of controlling properties and loss of valve closing function due to progress of compression permanent deformation of an elastic member provided on a valve element and a valve seat for improving property of shutting off fuel in a valve close state. SOLUTION: When compression permanent deformation of the elastic member 16 due to repeated compression deformation in closing the valve reaches a certain amount, a stopper 25 getting into contact at opposing parts of the valve element 14 and the valve seat 20 functions at an outer side of a contact surface 17 and a seating surface 23 to restrict motion of the valve element 14 in closing direction greater than that. Consequently, progress of compression permanent deformation is eliminated and fuel flow rate control can be accurately continued.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetically driven fuel injection valve used for supplying gaseous or liquid fuel to an engine.

[0002]

2. Description of the Related Art When an electric signal sent from an electronic control unit is energized in accordance with the operation state of an engine, an opening operation by an electromagnetic force is performed by a valve body, and when not energized, a closing operation by a spring force of a return spring is performed by the valve body. In a fuel injection valve that intermittently injects gaseous or liquid fuel by causing
In order to accurately control the flow rate of fuel supplied to the engine, it is necessary that the valve element responds sharply to turning on and off the electric signal, and that the valve element completely seats on the valve seat when the valve is closed. .

[0003] For this purpose, the return spring is a disc-shaped leaf spring, the outer peripheral portion of which is fixed and the movable core and the valve body are fixed at the center, so that the movable core and the valve body have no sliding portion. Japanese Patent Application Laid-Open No. 9-79107 describes an example in which the responsivity is improved by reciprocating in a floating state. Also, at least one of the contact surface of the valve body and the seat surface of the valve seat is made of rubber or synthetic resin, and when the valve body is seated on the valve seat, the rubber or synthetic resin is compressed and deformed, and the seat portion of the valve seat is formed. It is a well-known means to have a shape protruding toward the valve body and to completely seat and block the flow of fuel by compression deformation of rubber or synthetic resin.

FIG. 3 is a longitudinal sectional view showing a main part of the valve element and the valve seat. A movable iron core 52 and a valve element 53 are integrally fixed to a center of a leaf spring 51. Valve seat 5 of valve body 53
A thin plate-shaped elastic piece 54 made of rubber or synthetic resin is laminated on the end face facing 5 by baking, bonding or the like, and the surface forms a contact surface. on the other hand,
An annular projection 57 surrounding the valve hole 56 is formed at the center of the surface of the valve seat 55 facing the valve body 53, and the end surface forms a seat surface.

[0005]

When the valve is closed, the elastic piece 54 comes into contact with the ring projection 57 of the valve seat 55 and then bites and is compressed and deformed. When the valve is opened, it separates from the ring projection 54 and restores its original shape. Therefore, if the device is used for a long period of time, it gradually deteriorates and the elastic force is reduced, and a permanent compression set is generated so that the original shape cannot be completely restored. Therefore, not only does the stroke of the valve body 53 increase, causing a decrease in responsiveness and an increase in fuel flow rate, but also as the elastic force decreases, a crack occurs, a breakage state such as partial peeling occurs, and when the valve is closed. There is a concern that the fuel flow will not be cut off.

According to the present invention, the elastic member provided for completely shutting off the flow of fuel when the valve is closed to improve controllability has a permanent compression set when used for a long period of time, resulting in reduced responsiveness and reduced fuel flow rate. In addition to causing an increase, there is a concern that the complete valve closing function may be lost, which was made in order to solve the above-mentioned problem.
Accordingly, it is an object of the present invention to minimize a decrease in responsiveness and an increase in fuel flow rate so as not to impair reliability of fuel flow rate control.

[0007]

According to the present invention, a valve element which operates integrally with a movable iron core performs an opening operation of separating from a valve seat by an electromagnetic force when an electric signal is applied, and a valve seat by a spring force of a return spring when the electric signal is not applied. A fuel injection valve that performs a closing operation to be seated on a valve body, wherein a ring projection surrounding a valve through hole is provided on a surface of the valve seat facing the valve body, and a tip end surface of the ring projection is formed on an end face of the valve body. The above-mentioned problem in which the seat surface on which the contact surface is seated and at least one of the contact surface and the seat surface is made of an elastic material is solved as follows.

That is, the opposing portions of the valve element on the outer side of the contact surface and the outer side of the ring projection of the valve seat are made of metal, and the opposing portions have a constant compression set of the elastic member when the valve is closed. When it is within the range, it does not contact each other, but when it reaches a certain value, it comes into contact with each other and acts as a stopper for limiting the stroke of the valve element.

The elastic member is compressed and deformed each time the valve is closed, and when used for a long period of time, the elasticity gradually decreases to cause permanent compression. However, until the elastic member reaches a certain value, the valve through hole is closed by biting. Turn off fuel flow. When the compression set becomes a fixed value, the valve body and the stopper portion of the valve seat come into contact with each other to prevent further closing operation of the valve body, without causing further compression set to the elastic member, Therefore, the valve through-hole closing action is performed without further lowering the elastic force, and the fuel flow is stably and reliably shut off for a long period of time without causing breakage such as cracking or partial peeling. can do.

In addition, by setting the stopper portions to contact each other at a stage where the compression set is small, the delay in response and the increase in fuel flow are minimized within an allowable range, and the reliability of control is impaired. The object of not allowing the object to be achieved is easily achieved.

[0011] By treating the surface of at least one of the valve element and the stopper portion of the valve seat with a surface hardening treatment, when they come into contact with each other, the increase in the stroke of the valve element is completely prevented. It is possible to control the fuel flow rate stably throughout.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIG. 1. A fixed iron core 5 has a base end at the center of a coil holder 2 housed in an outer case 3 while holding a coil 1. 3 is held in a penetrating state protruding outside. A spacer plate 6, a plate-like return spring 7, and a valve seat holder 8 are disposed in front of the end of the coil holder 2 such that their outer peripheral portions are overlapped with each other.
The spacer plate 6 is fixed adjacent to the coil holder 2 by sandwiching the outer peripheral edge portion in a caulking portion 4 formed by bending the tip of the coil holder 2.

At the center of the return spring 7, a movable iron core 12 mounted on a cylindrical piece 11 superposed on the base end surface thereof and a valve element 14 superposed on the distal end surface thereof are arranged. A shaft piece 15 protruding from the center is inserted through the return spring 7, the cylindrical piece 11, and the movable iron core 12, and they are integrally fixed by an expanded portion 15a at the shaft end.

The spacer plate 6 is annular, and the movable core 12 is loosely fitted into the center hole thereof. The base end surface of the movable core 12 facing the distal end surface of the fixed core 5 is made of an elastic material such as rubber. The obtained thin plate-shaped buffer layer 13 is laminated by baking or the like. This buffer layer 13
A magnetic circuit formed when an electric signal is supplied to the coil 1 is useful for reducing the collision sound when the movable iron core 12 is attracted to the fixed iron core 5 and for securing a predetermined open voltage.

The valve seat holder 8 has a fuel through hole 9 and an injection cylinder 10 protruding in the center in a direction opposite to the valve body 14.
The valve seat 20 is fitted and fixed to the injection cylinder 10 and held.

The valve body 14 is made of metal, and its valve seat 20 is made of metal.
A circular plate-like elastic member 16 made of rubber or synthetic resin is overlaid and fixed to the central portion of the surface opposite to the surface by appropriate means such as baking and bonding. The contact surface 1 which is the surface of the member 16
An annular protruding piece 18 located forward of 7 is formed by integral molding.

The valve seat 20 is made of metal.
A ring projection 22 surrounding the entrance of the valve through-hole 21 is formed at the center of the surface facing the projection by integral molding.
The distal end surface forms a seat surface 23 on which the contact surface 17 is seated, and a flat portion outside the annular projection 22 forms a receiving portion 24 that contacts the distal end surface of the projecting piece 18. When the valve is closed, the elastic piece 16 is
When a state in which the compression deformation generated by biting into the valve is completely restored when the valve is opened is repeated, a small gap is provided so as not to contact the receiving portion 24 when the valve is closed.

When the elastic member 16 has been used for a long period of time and the elastic member 16 has deteriorated to reduce the elastic force to cause compression set, and the contact surface 17 has receded, the valve body 14 has a thickness reduced by the compression set when the valve is closed. In addition, a stroke is performed in which the elastic member 16 is further compressed and deformed.
The stroke of No. 4 gradually increases. When the stroke of the valve element 14 increases, the projecting piece 18 and
And the valve body 14 stops at the position where they contact, and further stroke in the valve closing direction is prevented.

That is, the protruding piece 18 and the receiving portion 24 do not come into contact with each other when the compression set of the elastic member 16 is within a predetermined value, but come into contact when the compression set becomes a predetermined value, thereby limiting the stroke of the valve element 14. The stopper 25 is formed. Therefore, by setting the dimensions so that they come into contact with each other at a stage where the compression set is small, it is possible to minimize a decrease in responsiveness and an increase in fuel flow rate due to an increase in the stroke of the valve body 14 within an allowable range. it can. Also, the stopper 25
Restricts the biting of the elastic member 16 into the annular projection 22 within the range of elastic deformation, and can greatly delay the deterioration of the elastic member 16.

In addition, both or one of the surfaces of the projecting piece 18 and the receiving portion 24 facing each other is carburized,
A surface hardening treatment by nitriding treatment or carbonitriding treatment may be performed. This eliminates the fear that the surface of the valve body 14 is deformed by the impact at the time of closing the valve and the function of preventing the valve body 14 from increasing the stroke is reduced, and the fuel flow rate can be controlled for a long period of time. Become.

In the embodiment shown in FIG. 1, the fuel adjusted to a predetermined pressure is fed into the space on the distal end side of the valve seat holder 8, and
Thus, the fuel gas enters the base end side space of the valve seat holder 8 through the fuel through hole 9, and the valve body 14 passes through the injection cylinder 10 through the valve through hole 21 when the valve is opened away from the valve seat 20, and the intake pipe of the engine. Injected into. The return spring 7 is a disc-shaped leaf spring provided with a plurality of through-holes, or a spring wire is formed into a plate shape by winding a spring wire into a spiral shape with a small gap. Since the space on both sides of the return spring 7 communicates with each other to prevent a pressure difference from occurring, the valve element 14 can be properly moved in the closing direction when no electric signal is supplied.

FIGS. 2A and 2B show the valve element 14 and the valve seat 20.
FIG. 7A is a partial view showing another embodiment of the present invention, wherein FIG.
The center of the surface of the metal valve body 14 facing the valve seat 20
Contact surface 17 as it is_AAnd a ring on the outside
Projecting piece 18_AIs formed by integral molding
The valve hole 21 of the metal valve seat 20_AAround the entrance
Ring protrusion 22_AMade of rubber or synthetic resin
Annular elastic member 16 _AAnd the tip surface of the sheet
Face 23_AAnd the ring projection 22_AOutside flat part of
Receiving part 24_A(B) is a metal
The surface facing the valve seat 20 of the valve body 14 made of
Formed at the center and the same elasticity as the form shown in FIG.
Member 16_BAnd the surface is brought into contact with the surface 17_BToss
And the outer side of the pressing portion 18_BAnd a metal valve
Valve through hole 21 of seat 20_BEntrance is the same as that shown in Fig. 1.
Ring projection 22_BEnclose it with the sheet surface 23_BToss
Ring projection 22_BSurround the outside with multiple pillars
Or block-shaped receiving piece 24_BWith a protrusion formed
is there.

[0023] to those shown FIG. 2 (A), results in compression set resilient member 16 _A of the valve seat 20 is pushed by the contact surface 17 _A of the valve body 14 when the valve is closed, which is a certain value protruding piece 18 _a is in contact with the receiving portion 24 _a when the, these stoppers 2
At 5 _A , the valve body 14 is prevented from further moving in the closing direction. To those shown FIG. 2 (B), results in compression set is the elastic member 16 _B of the valve body 14 bite into the ring projection 22 _B when the valve is closed, the contact portion 18 _B when this was the certain value There contacts the receiving portion piece 24 _B, they prevent further closing direction operation of the valve body 14 is a stopper 25 _B.

The present invention is not limited to the above-mentioned embodiment, but is also applicable to the case where both the contact surface of the valve element and the seat surface of the valve seat are made of an elastic member, and the compression set of the elastic member becomes a constant value. The portion that acts as a stopper when it is formed can be arbitrary such as formed by a protruding portion provided opposite to each other on both the valve body and the valve seat,
If the surface portions that come into contact with each other are hardened, the reliability can be further improved.

[0025]

As described above, according to the present invention, the compression set of the elastic member provided on one or both of the valve body and the valve seat exceeds a certain value in order to improve the fuel shutoff performance when the valve is closed. Not only completely eliminates the risk of cracking or partial delamination leading to loss of complete valve closing function, but also allows for reduced responsiveness and increased fuel flow due to increased valve stroke. The fuel flow control can be kept good for a long period of time with the minimum value within the range, and high reliability can be given.

[Brief description of the drawings]

FIG. 1 is a partially enlarged longitudinal sectional view showing an embodiment of the present invention.

FIGS. 2A and 2B are partial longitudinal sectional views showing different embodiments of the present invention.

FIG. 3 is a partial longitudinal sectional view showing a conventional example.

[Explanation of symbols]

5 fixed iron core, 7 return spring, 12 movable iron core,
14 valve, 16, 16 _A, 16 _B elastic member, 1
7, 17 _A, 17 _B per side, 20 valve seat, 21,2
1 _A, 21 _B Bendoriana, 22, 22 _A, 22 _B ring projections, 23, 23 _A, 23 _B seat surface, 25, 25
_A , 25 _B stopper,

Claims (2)

[Claims] 1. A valve element which operates integrally with a movable iron core performs an opening operation to separate from a valve seat by electromagnetic force when an electric signal is applied, and performs a closing operation to be seated on the valve seat by a spring force of a return spring when no electric current is applied. A fuel injection valve, wherein a ring projection surrounding a valve through hole is provided on a surface of the valve seat facing the valve body, and a tip end surface of the ring projection is formed on an end surface of the valve body. A seat surface on which a seat is to be seated, wherein at least one of the contact surface and the seat surface is made of an elastic member, wherein the outside of the contact surface of the valve body and the outside of the ring projection of the valve seat. The opposing portions are made of metal, and the opposing portions do not contact each other when the compression set of the elastic member is within a certain value when the valve is closed, but do contact each other when a certain value is reached. A fuel injection valve, wherein is has it to act as a stop to limit the stroke of the valve body Te. 2. The fuel injection valve according to claim 1, wherein at least one of the valve body and a portion of the valve seat that functions as the stopper is subjected to a surface hardening treatment.