JPH11280940A - Splenoid valve and injector having it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevented from the increase of size and to ensure sealability between the forward end face of a valve member and the seal surface of a valve seat member regardless of dispersion in a machining tolerance therebetween. SOLUTION: A solenoid valve 10 is provided to open and close a duct by making contact with each other and parting from each other between the forward end face 34b of the valve member 34 to axially reciprocate through a force relation between the excitation force of a solenoid 36 and the energizing force of a coil spring 37 and the surface 33a of a valve seat member 33. A valve seat member 33 is floatable arranged that the valve seat member 33 is moved as its own attitude is changed matching with that of the forward end face 34b of the valve member. Through floating of the valve member 33 occasioned by press of the valve member 34 against the seat surface 33a, dispersion in a machining tolerance between the forward end face 34b and the seat surface 33a is absorbed and the surfaces are formed into close contact without any gap and a closing state to reliably close is ensured, and the less excitation force of the solenoid 36 suffice for operation of the solenoid valve.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic valve used for opening and closing a flow path of a fluid such as fuel injected into a combustion chamber by electronic control, and an internal combustion engine incorporating the electromagnetic valve. More particularly, the present invention relates to an injector provided in a fuel injection device for a diesel engine.

[0002]

2. Description of the Related Art For example, an injector of a common rail type fuel injection device having a common rail as a pressure accumulating chamber and supplying fuel is operated by electronically controlling an electromagnetic valve built in the injector, so that high pressure fuel is burned by an internal combustion engine. It is designed to inject into the chamber intermittently. A solenoid valve for such an application is known from European Patent Application EP 0 740 068 A2.

In this solenoid valve, the distal end surface of a valve member which is reciprocated in the axial direction due to the force relationship between the exciting force of a solenoid and the urging force of a spring comes into contact with and separates from the seat surface of a valve seat member, thereby supplying high-pressure fuel. It opens and closes the flow path.

[0006] That is, as shown in FIG. 6 schematically showing a main part of the solenoid valve, a valve member 101 is formed of a cylindrical body having a fluid passage 103 opened at a front end surface 102 thereof. An armature 104 sucked by a solenoid (not shown) is connected to the upper end of the armature. The valve member 101 is constantly urged by the force of the coil spring 107 so that the flat distal end surface 102 is pressed against the seat surface 106 of the flat valve seat member 105, and the flow path is closed by this pressing. (Close).
In FIG. 6, reference numeral 108 denotes a valve member guide through which the valve member 101 slidably passes in the axial direction, 109 denotes a high-pressure fuel inflow chamber, and 110 denotes a high-pressure fuel outflow chamber. The solenoid generates an exciting force by energizing the solenoid, pulls up the valve member 101 together with the armature 104 against the force of the coil spring 107, opens the flow path (opens the valve), and opens the flow passage.
9 allows the high-pressure fuel to flow to the outflow chamber 110.

In the solenoid valve having such a configuration, since the oil pressure of the high-pressure fuel does not act in the valve opening direction, the spring force of the coil spring 107 for urging the valve member 101 can be reduced, and the solenoid can be reduced in size. Excellent in point.

Further, the invention in which the solenoid valve is improved is disclosed in
It is known from Japanese Patent Application Publication No. -178041, which describes an invention capable of ensuring good sealing performance in a planar seal structure between the front end surface of a valve member and a seat surface. In other words, a part of the outer periphery of the valve member driven by the solenoid is cut off, and the part is made thinner than the other parts to form a relatively flexible region. The entire flat front end surface of the member is securely brought into close contact with the seat surface of the valve seat member to prevent a gap from being generated between them, thereby ensuring sealing performance.

[0007]

In the invention described in the above-mentioned European Patent Application EP 0 740 068 A2, the valve member 1 is provided.
01 and the seat surface 10 of the valve seat member 105
6, the coaxiality between the valve member 101 and the guide 108, the front end surface 102 and the seat surface 10
6, there may be an angle α in FIG. When such an angle α is provided, there is a problem that the sealing performance is impaired and the high-pressure fuel in the inflow chamber 109 always leaks through the fluid passage 103 of the valve member 101. Therefore, in the injector, as described above, the pressure of the inflow chamber 109 is not stabilized due to the leakage of the high-pressure fuel. With this, this room 10
Since the pressure in the back pressure chamber that applies back pressure to a nozzle needle (not shown) that opens and closes the injection hole in communication with the nozzle 9 is not stable, problems such as variations in the amount of fuel injected from the injection hole are caused. In addition, since the pressure of the high-pressure fuel leaked to the outflow chamber 110 is applied to the lower surface of the armature 104, in the worst case, the valve member 101 is kept in the raised position, and accordingly, the high-pressure fuel is discharged. There is a risk that the jet will remain.

On the other hand, Japanese Patent Application Laid-Open No. 9-17804 describes
In the solenoid valve described in Japanese Patent Application Laid-Open No. 1 (1993) -1999, even if the processing accuracy of the distal end surface of the valve member or the like is poor and the angle α is provided as described above, the bending of the valve member in the flexible region causes It is excellent in that the surface is brought into close contact with the sealing surface of the valve seat member without any gap to ensure the sealing performance.

However, in order to flexibly deform the valve member as described above, it is necessary to press the valve member against the valve seat member with a coil spring, but the valve member is pressed with such a strong spring force. That is, a large exciting force is required for a solenoid that pulls the valve member to open the valve.
As a result, the amount of winding of the solenoid has to be increased, and this solenoid is increased in size.
There is a problem that is damaged. For this reason, the injector incorporating such a solenoid valve must be increased in size.

The first problem to be solved by the present invention is as follows.
An object of the present invention is to provide an electromagnetic valve that does not cause an increase in size and that can secure sealing performance between the front end surface of the valve member and the sealing surface of the valve seat member irrespective of a variation in processing tolerance.

A second problem to be solved by the present invention is that
In order to solve the first problem, an object of the present invention is to provide a solenoid valve suitable for further downsizing. A third problem to be solved by the present invention is to obtain an injector that can realize appropriate fuel injection without increasing the size.

[0012]

Means for Solving the Problems The inventions of claims 1 to 6 are:
It is assumed that an electromagnetic valve opens and closes a flow path by bringing a distal end surface of a valve member reciprocated in the axial direction into and out of contact with a seat surface of a valve seat member by a force relationship between an exciting force of a solenoid and an urging force of a spring.

[0013] In order to solve the first problem, the invention according to claim 1 is characterized in that the valve seat member changes its own posture and moves in accordance with the distal end surface of the valve member. The member is provided so as to be freely movable.

In the first aspect of the present invention, when the solenoid is not energized, the valve member is pressed by the biasing force of the spring so that the distal end surface thereof is in close contact with the seat surface of the valve seat member. Irrespective of the variation in processing tolerance between the seat surface and the front end surface, the valve seat member changes its posture so that the seat surface is in close contact with the front end surface without any gap. Thus, the spring force for urging the valve member and the exciting force of the solenoid that moves the valve member in the valve opening direction against the spring force can be reduced.

In carrying out the invention of claim 1,
As means for allowing fluid to flow out when the valve is opened, the valve member may be formed of a cylindrical body having a fluid passage opening to the front end surface of the valve member. When the valve is opened, the fluid can flow out through the fluid passage inside the valve member without the trouble of making the valve.

Similarly, in practicing the first or second aspect of the present invention, the seat surface has a planar shape as in the third aspect of the invention as means for providing the valve seat member in a freely movable manner. It is preferable that the valve seat member is formed of a sphere having a part thereof, and the valve seat member is movably supported by a valve seat member holder formed of a spherical bearing. According to the third aspect of the present invention, the position of the valve seat member with respect to the valve member is determined, and at this fixed position, when the valve is closed, the distal end surface of the valve member is pressed against the seat surface of the valve seat member. Can easily slide by sliding its spherical outer surface against the bearing surface of a valve seat holder made of a spherical bearing.

According to a fourth aspect of the present invention, there is provided a valve seat member holder having an upper surface opened and filled with a fluid, the chamber being provided with a fluid. It is characterized in that the valve seat member is accommodated therein so as to be freely movable by the pressure of the fluid.

The invention of claim 4 has the following operation in addition to the operation of the invention of claim 2. In the present invention, the valve seat member in the chamber receives a force in the direction of the valve member by the pressure of the fluid filled in the chamber of the valve seat member holder, so that when the valve is closed, the valve seat member is aligned with the distal end surface of the valve member. By changing the posture, the fluid passage of the valve member can be closed in close contact with the front end surface without any gap. In this closed state, the closed state can be maintained by the pressure of the fluid acting on the valve seat member and the force of the spring biasing the valve member, so that the spring force and, consequently, the excitation force of the solenoid can be further reduced. It is.

In carrying out the invention of claim 4,
A spherical body may be used for the movable valve seat member as in the invention of claim 5, or a flat seat surface is provided on the upper surface of the movable valve seat member as in the invention of claim 6. May be used.

In the injector according to the present invention, a nozzle body having an injection hole for injecting fuel contains a nozzle needle for opening and closing the injection hole in a reciprocating manner, and a back pressure applied to the nozzle needle. Is controlled by an electromagnetic valve incorporated in the nozzle body to open and close the injection hole.

In order to solve the third problem, an injector according to a seventh aspect of the present invention uses the solenoid valve according to any one of the first to sixth aspects. It is characterized by the following.

In the seventh aspect of the present invention, since the solenoid valve incorporated in the nozzle body is the solenoid valve according to any one of the first to sixth aspects, the solenoid valve is small. Accordingly, the entire injector can be downsized.
Then, the fuel is injected from the injection hole by moving the nozzle needle by changing the solenoid valve from the closed state to the open state, but in the closed state, the distal end face of the valve member and the valve seat member are closed as described above. The high pressure fuel can leak from the solenoid valve due to the variation in the processing tolerance, because the seat surface can be tightly closed without any gap regardless of the variation in the processing tolerance and the like, and the high pressure fuel flow path can be reliably closed. Absent.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS. As shown in a system diagram of FIG. 1 schematically showing a configuration of an electronic fuel injection system for a diesel engine provided with an injector according to a first embodiment, a fuel pump 2 is provided by a feed pump 1.
The fuel sucked out of the fuel tank is pressurized by a fuel injection pump 3 to become high-pressure fuel and sent to a common rail 4 which is a storage pressure chamber. The amount of high-pressure fuel sent to the common rail 4 is adjusted by controlling an adjusting solenoid valve 5 attached to the fuel injection pump 3 by a control signal from an electronic control unit (hereinafter abbreviated as ECU) 6. You. A fuel injection nozzle 8 is attached to the multi-cylinder diesel engine 7 corresponding to each cylinder individually, and each of these nozzles 8 is connected to the common rail 4 via a high-pressure pipe 9. The injection amount and the injection timing of the high-pressure fuel from each injector 8 are determined by the solenoid valve 1 built in each injector 8.
It is determined by controlling the energization to 0 by the ECU 6.

In FIG. 1, reference numeral 11 denotes a pressure sensor for detecting the pressure of the high-pressure fuel in the common rail 4, and the detection information is supplied to the ECU 6. Similarly, reference numeral 12 denotes a temperature sensor for detecting the temperature of the engine 7, and the detection information is EC.
It is supplied to U6. Similarly, reference numeral 13 denotes an accelerator pedal, and information on the depression amount is supplied to the ECU 6. The ECU 6 controls the energization and the like to the solenoid valves 5, 10 and the like based on the information and the like supplied thereto, and accordingly the fuel injection amount and the injection timing from each injector 8 to the corresponding in-cylinder combustion chamber. Control.

The electronic fuel injection device for a diesel engine as described above is excellent in that it can cope with the recent tightening of exhaust gas regulations, is excellent in protection of the global environment, and can also realize improved drivability. I have.

The structure of each injector 8 will be described with reference to FIG. As shown in FIG. 2, a tapered seat portion (valve seat portion) 22 of a nozzle body 21 provided in the injector 8 has one or more small-diameter injection holes 23 through which the high-pressure fuel is injected. Is provided. Seat part 2
The inclined inner bottom surface 2 is a body seat surface (valve seat surface) 22a.
It has become. The nozzle body 21 of the Hall-type injector 8 has a stepped cylindrical shape in which a large-diameter portion and a small-diameter portion are connected vertically, and the solenoid valve 10 is built in the large-diameter portion. A nozzle needle 24 for opening and closing the injection hole 23 in accordance with the opening and closing operation of the solenoid valve 10 is incorporated so as to be reciprocally movable in the axial direction.

The solenoid valve 10 includes a valve seat member holder 31, a valve member holder 32, a valve seat member 33, a valve member 34, an armature 35, a solenoid 36, a coil spring 37, and the like.

More specifically, the circular valve seat member holder 31
The nozzle body 21 is positioned and attached to a tapered step portion in the nozzle body 21 which borders the large diameter portion and the small diameter portion, and partitions the inside of the nozzle body 21 up and down. As shown in FIG. 3 and the like, a spherical bearing having a concave spherical bearing concave portion 31a opened on the upper surface is used for the valve seat member holder 31. The circular valve seat member 33 is formed of a sphere having a seat surface (valve seat surface) 33a in a part thereof, and the seat surface 33a side is projected from the bearing recess 31a to form the concave portion 3a.
1a. The spherical outer surface of the valve seat member 33 is slidable along the spherical inner surface of the bearing recess 31a, and therefore, the valve seat member 3 supported by the valve seat member 33
Numeral 3 is provided so as to be freely movable so that its own posture can be changed at the disposition position. The seat surface 33a is flat. This flat concept includes not only a flat surface but also a slightly curved surface.

The valve member guide 32 is mounted inside the nozzle body 21 so as to overlap the upper surface of the peripheral portion of the valve seat member holder 31.
An inflow chamber 38 for accommodating the seat surface 33a is formed between the guide 32 and the valve seat member holder 31. At the center of the guide 32, a guide hole 32a opening in the center of the inflow chamber 38 is provided so as to penetrate in the axial direction, and the valve member 3 is slidably penetrated through the guide hole 32a.
4 are attached. The valve member 34 is formed of a cylindrical cylinder having a fluid passage 34a at the center thereof. One end (lower end) of the passage 34a is opened at a distal end surface 34b of the valve member 34 protruding into the inflow chamber 38. ing. Fluid passage 34
The other end (upper end) of “a” is opened in the hollow portion inside the nozzle body above the valve member guide 32, that is, the upper side surface of the valve member 34 facing the outflow chamber 39, and communicates with the outflow chamber 39.

A disk-shaped armature 35 is connected to the upper end of the valve member 34 located in the outflow chamber 39. The outflow chamber 39 is connected to the fuel tank 2 through a drain port 40 provided at an upper portion of the nozzle body 21 and a return pipe (not shown) connected to the port 40. The outflow chamber 39 accommodates a solenoid 36 which is opposed to the upper surface of the armature 35 and whose power is cut off by the ECU 6. The solenoid 36 is formed by winding a winding around a yoke having a spring receiving hole in the center, and attracts the armature 35 to the yoke by an exciting force generated when the winding is energized. This solenoid 3
A coil spring 37 is accommodated in the spring accommodation hole 6 in a compressed state, and the lower end of the spring 37 is engaged with the center of the rear surface of the armature 35. Due to the spring force of the coil spring 37, the valve member 34 is constantly urged toward the valve seat member 33 via the armature 35, and the distal end surface 34b of the valve member 34 is pressed against the seat surface 33a. .

The nozzle needle 24 disposed below the solenoid valve 10 having the above-described structure has a large needle diameter portion 24a and a small needle diameter portion 24b integral therewith. Is slidably fitted to the inner surface of the small diameter portion of the nozzle body 21. The distal end portion (lower end portion) of the needle small diameter portion 24b forms a needle valve body portion 24c having a tapered distal end. The valve body portion 24c contacts and separates from the seat surface 22a to open and close the injection hole 23. Has become.

When the nozzle needle 24 is accommodated in the nozzle body 21, the back pressure chamber 51 is provided between the needle large diameter portion 24a and the lower surface of the valve member holder 31 facing the upper surface.
Are formed, and the lower surface of the needle large diameter portion 24a and the outer surface of the needle small diameter portion 24b are
An oil reservoir 52 is formed between the inner surface of the small diameter portion.
A high-pressure feed port 53 communicating with the oil sump 52 is provided at a lower portion of the nozzle body 21, and the tip of the high-pressure pipe 9 connected to the common rail 4 is connected to the port 53.

The back pressure chamber 51 is connected to a high pressure feed port 53 via a first throttle passage 54. In the back pressure chamber 51, a needle urging spring 55 is housed in a compressed state sandwiched between the nozzle needle 24 and the valve seat member holder 31.
The spring 55 always applies a biasing force to the nozzle needle 24 to press the nozzle needle 24 in the valve closing direction. FIG.
The middle 56 is from the needle large diameter portion 24a to the valve seat member holder 31.
A needle urging spring 55 is provided by winding the stopper. This stopper 5
6 is the nozzle needle 24 which contacts the valve seat member holder 31;
The maximum lift amount is regulated. The stopper 56 may be provided so as to project from the lower surface of the valve seat member holder 31 toward the nozzle needle 24. The back pressure chamber 51 communicates with the inflow chamber 38 through a second throttle passage 57 opened in the valve seat member holder 31.

The injector 8 having the above configuration performs the following fuel injection. High-pressure fuel is guided to the nozzle 8 from the common rail 4 through the high-pressure pipe 9 as described above. This fuel is supplied from the high pressure feed port 53 to the oil sump 5.
2 and acts on the lower surface of the large-diameter portion 24a of the needle to apply an upward force to the nozzle needle 24,
It is guided to the back pressure chamber 51 through the first throttle passage 54 and applies a downward back pressure to the nozzle needle 24. In addition, the high-pressure fuel in the back pressure chamber 51 passes through the second throttle passage 57 and flows into the inflow chamber 3.
8

For this reason, as shown in FIG.
4 is pressed against and held by the seat surface 33a of the valve seat member 33 and the solenoid valve 10 is closed.
By the back pressure and the urging force of the needle urging spring 55, the needle valve body 24c is pressed against the body seat surface 22a, and the injection hole 23 is kept closed.

At the time of fuel injection, as described above, EC
The solenoid 36 of the solenoid valve 10 is energized by U6, and the solenoid valve 10 is opened. That is, since the solenoid 10 generates an exciting force and attracts the armature 35 to the lower end surface of the yoke against the spring force of the coil spring 37, the valve member 34 is pulled up together with the armature 35. Thereby, the distal end surface 34b of the valve member 34 is separated from the seat surface 33a, and the inflow chamber 38 and the outflow chamber 39 are communicated via the fluid passage 34a of the valve member 34.

Therefore, the high-pressure fuel in the inflow chamber 38 flows through the fluid passage 34a to the outflow chamber 39, and flows through the nozzle body 2
As the fuel is discharged from the drain port 40, the fuel in the back pressure chamber 51 is supplied to the inflow chamber 38, and the back pressure chamber 5
1 (in other words, the back pressure acting downward on the nozzle needle 24) decreases, and eventually acts on the lower surface of the needle large-diameter portion 24a rather than the resultant force for pushing down the nozzle needle 24. The fuel pressure of the high-pressure fuel for pushing up the nozzle needle 24 becomes larger.

Then, as the nozzle needle 24 starts rising against the urging force of the needle urging spring 55, the needle valve body part 24c separates from the body seat surface 22a and the oil sump 52 and the injection hole 23 Is communicated. Therefore, the high-pressure fuel is guided to the injection hole 23 through the oil reservoir 52 around the needle small-diameter portion 24b with respect to the injection hole 23, and is injected vigorously from the injection hole 23 toward the combustion chamber.

At the end of the fuel injection, the power supply to the solenoid 36 of the solenoid valve 10 is cut off by the ECU 6 and the solenoid valve 10 is closed. That is, as the exciting force of the solenoid 36 is lost, the valve member 34 and the armature 35 are moved together with the armature 35 by the spring force of the coil spring 37 already stored.
Is pushed down toward the valve seat member 33, so that the distal end surface 34 b of the member 34 is pressed against the seat surface 33 a of the valve seat member 33. The sheet surface 33a of such a front end surface 34b
The flow path from the inflow chamber 38 to the outflow chamber 39 is closed by close contact with the flow path.

Therefore, the pressure of the fuel in the inflow chamber 38 and the pressure of the fuel in the back pressure chamber 51, which are communicated with each other via the second throttle passage 57, are respectively increased, so that the pressure in the back pressure chamber 51 rises to a predetermined value. In the above, the nozzle needle 24 starts descending due to the downward resultant force of the back pressure and the spring force of the needle urging spring 55 to bring the needle valve body portion 24c into contact with the body seat surface 22a to close the injection hole 23. Thereby, the fuel injection stops. Thereafter, the fuel injection and the stop are repeated by the control of the solenoid valve 10.

The opening and closing of the flow path by the solenoid valve 10 provided in the injector 8 operating as described above is performed by using the distal end surface 34b of the valve member 34 which is moved in the axial direction as described above.
3 by bringing the sheet into contact with and separating from the third sheet surface 33a. By the way, the closeness of the electromagnetic valve 10 in the closed state where the seat surface 33a and the front end surface 34b are in close contact with each other depends on the degree of coaxiality between the holder 32 and the valve member 34 and on the both surfaces 33a and 34b.
The variation of the processing tolerance a in FIG.

Nevertheless, since the valve seat member 33 having the seat surface 33a is mounted on the valve seat member holder 31 so that its own posture can be freely changed, for example, the distal end surface 34b of the valve member 34 is Even if the valve member 34 is formed at an angle indicated by α in FIG. 3 with respect to the central axis of the valve member 34, the distal end surface 34b can be brought into close contact with the seat surface 33a without any gap.

That is, as described above, as the valve member 34 is pressed against the seat surface 34 a of the valve seat member 33 by the spring force of the coil spring 37, the pressing force is used to make use of the valve seat member 3.
3 changes its own posture while floating in accordance with the angle α so that the seat surface 33a has the angle α as shown in FIG. Therefore, the front end surface 34b and the sheet surface 33a are brought into close contact with no gap and the flow path can be reliably closed.

In this case, the valve seat member 33 is a sphere partly having a seat surface 33a, and is fitted and supported movably in the bearing recess 31a of the valve seat member holder 31 formed of a spherical bearing. The position of the valve seat member 33 with respect to the valve member 34 is fixed. Then, in this fixed position, the distal end surface 34b of the valve member 34 is pressed against the seat surface 33a as described above, so that the spherical outer surface of the valve seat member 33 is
By sliding on the spherical inner surface (bearing surface) of the first bearing recess 31a, it can be easily rotated, whereby the solenoid valve 10 can be brought into the closed state.

As described above, it is possible to realize a planar sealing structure in which the flow path is securely closed by the free movement of the valve seat member 33 without bending the valve member 34 with a strong force. It is not necessary to particularly increase the spring force of the coil spring 37 for urging the spring. Therefore, the exciting force of the solenoid 36 that moves the armature 35 and the valve member 34 in the valve opening direction against the force of the coil spring 37 can be reduced, and accordingly, the winding amount of the solenoid 36 is reduced, and Power consumption can be suppressed low, and the solenoid 36 and the solenoid valve 10 having the same can be made compact. Accordingly, the size of the injector 8 in which the solenoid valve 10 is built can be reduced.

In addition, despite the fact that the seat surface 33a moves so as to absorb the variation in the processing tolerance and the like to realize a planar sealing structure, the fluid passage 34 of the valve member 34 in the valve open state.
Since the high-pressure fuel is circulated through “a”, there is no need to create a passage that bypasses the valve member 34. In order to allow the high-pressure fuel to flow to the drain port 40 side without passing through the valve member 34, a passage in the valve seat member, which is opened to the seat surface 33 a and the leading end of the valve member 34 comes and goes, is provided to the valve seat member 33. A valve passage in the holder is provided in the valve seat member holder 31 for communicating with the valve seat member passage through a structure for maintaining the communication state irrespective of the idle movement of the valve seat member 33. As a result, a passage in the guide that penetrates the valve member guide 32 must be formed, so that there is a problem that the processing is complicated. Therefore, the structure in which the fluid flows out when the valve is opened through the fluid passage 34a inside the valve member 34 formed of a cylindrical body is as follows.
It is excellent in that the processing of the solenoid valve 10 can be easily performed without the above-mentioned problems.

As described above, since the electromagnetic valve 10 can be reliably sealed at the time of closing with the flat seal structure without being affected by the variation of the processing tolerance, etc., the injector 8 incorporating the electromagnetic valve 10 is used. In the solenoid valve 10
The high-pressure fuel in the inflow chamber 38 does not leak to the drain port 40 side through the fluid passage 34a in the valve closed state. Therefore, since the pressure in the back pressure chamber 51 is stabilized, it is possible to prevent the fuel injection amount from fluctuating, to achieve proper fuel injection, and to push the armature 35 upward in the valve closed state with the leaked fuel. Therefore, there is no possibility that the injection hole 32 is kept open and the fuel is kept injected, and proper fuel injection can be performed.

FIG. 4 shows a main part of the second embodiment of the present invention. This embodiment has basically the same configuration as that of the first embodiment. Therefore, the same components are denoted by the same reference numerals as those of the first embodiment, and the configuration and operation will be described. Are omitted, and different portions will be described below. The difference between the second embodiment and the first embodiment is the configuration of the portion forming the planar sealing structure of the solenoid valve.

That is, the valve seat member holder 31 is provided with a chamber 60 which is open to the upper surface and communicates with the inflow chamber 38 through the open surface, and a stopper plate 61 which narrows the open area of the chamber 60. Is attached to the upper surface of the valve seat member holder 31. Chamber 6
A valve seat member 62 formed of a spherical body is freely movably accommodated in the inner space 0, and the outer peripheral surface of the valve seat member 62 is used as a sealing surface 62a. The diameter of the valve seat member 62 is larger than the opening 61 a of the stopper plate 61, thereby preventing the valve seat member 62 from going out of the chamber 60.
Further, the distal end surface 34b of the valve member 34 is formed as a tapered surface that gradually widens toward the outside in the radial direction from the fluid passage 34a. The configuration other than the points described above is the same as that of the first embodiment, including parts not shown in FIG.

In the second embodiment, the valve member 3 pushed down by the force of the coil spring 37 in the valve closed state.
4 is in contact with the sealing surface 62a of the valve seat member 62, and the valve seat member 62 is
The valve seat member 62 receives the pressure of the high-pressure fuel filled in the chamber 60 upward from below, and is pressed against the tapered distal end surface 34b of the valve member 34. At this time, the valve seat member 62 is
According to the variation of the processing tolerance of the valve member 34, it moves freely while shifting its position in the chamber 60, changes its own posture, and is pressed against the distal end surface 34 b of the valve member 34.

Further, since the distal end face 34b has the above-described tapered structure, the substantially outermost periphery of the distal end face 34b and the sealing surface 62a of the spherical valve seat member 62 are brought into close contact with no gap and the flow path is securely closed. Can be. Therefore, it is possible to prevent the pressure of the high-pressure fuel from being applied to the front end face 34b and pushing up the valve member 34 and the like.

When the solenoid 36 is excited by the ECU 6, the valve member 34 is pulled up.
2a, the fluid passage 34a of the valve member 34 and the inflow chamber 38 communicate with each other to open the valve. Accordingly, the high-pressure fuel is discharged to the drain port 40 through the outflow chamber 39, so that fuel injection is performed. In this case, the spherical valve seat member 62 is hooked on the edge of the opening 61a of the stopper plate 61, and does not follow the valve member 34 any more, so that the valve opening state can be obtained.

Therefore, also in the configuration of the second embodiment, the first problem of the present invention can be solved as in the case of the first embodiment. FIG. 5 shows a main part of the third embodiment of the present invention. This embodiment has basically the same configuration as that of the first embodiment. Therefore, the same components are denoted by the same reference numerals as those of the first embodiment, and the configuration and operation will be described. Are omitted, and different portions will be described below. The difference between the third embodiment and the first embodiment is the configuration of the portion forming the planar sealing structure of the solenoid valve.

That is, the valve seat member holder 31 is provided with a chamber 60 which is open to the upper surface and communicates with the inflow chamber 38 through the open surface, and a stopper plate 61 which narrows the open area of the chamber 60. Is attached to the upper surface of the valve seat member holder 31. Chamber 6
The valve seat member 65 is freely movably accommodated in the cylinder 0. The valve seat member 65 has a small-diameter portion 66 having an upper surface forming a flat sealing surface 66a, and a large-diameter portion 67 integrally connected to the lower surface.
And a convex portion 68 protruding downward from the center of the lower surface of the large diameter portion 67. The diameter of the large diameter portion 67 is larger than the opening 61a of the stopper plate 61,
The valve seat member 65 is prevented from coming out of the chamber 60. The configuration other than the points described above is the same as that of the first embodiment, including parts not shown in FIG.

In the third embodiment, the valve member 3 pushed down by the force of the coil spring 37 in the valve closed state.
4 is in contact with the sealing surface 66a of the valve seat member 65, and the valve seat member 65 receives the pressure of the high-pressure fuel filled in the chamber 60 upward from below the large-diameter portion 67. It is pressed against the tapered tip surface 34b of the valve member 34. At this time, the valve seat member 65 moves while shifting its position in the chamber 60 according to the variation of the processing tolerance of the tip end surface 34b indicated by the angle α in FIG. It is pressed against the distal end surface 34b of the member 34. Thereby, the front end surface 34b and the sealing surface 66a are closely contacted without any gap, and the flow path can be reliably closed. Since the valve seat member 65 has a convex portion 68 on its lower surface, the pressure of the fuel can be applied to the lower surface of the large-diameter portion 67 even at the time of starting the engine 7 or the like, whereby Irrespective of the fuel pressure acting on the surface 66a, the valve seat member 65 can be pressed against the distal end surface 34b of the valve member 34 by applying a lifting force to the valve seat member 65 while allowing the member 65 to float.

When the solenoid 36 is energized by a signal from the ECU 6, the valve member 34 is pulled up, so that the distal end surface 34b is separated from the sealing surface 66a of the valve seat member 65, and The fluid passage 34a and the inflow chamber 38 communicate with each other to open the valve. Therefore, high-pressure fuel flows through the drain chamber 40 through the outflow chamber 39.
, Fuel injection is performed. In this case, the large diameter portion 67 of the valve seat member 65
Of the valve member 34.
And the valve opening state can be obtained without rising.

Therefore, also in the configuration of the third embodiment, the first problem of the present invention can be solved similarly to the first embodiment. The present invention is not limited to the above embodiments. INDUSTRIAL APPLICABILITY The present invention can be applied not only to the injector of the common rail type fuel injection device and the solenoid valve built therein, but also to the injector of the conventional electronic control type fuel injection device not using the common rail and the solenoid valve built therein, In addition to the device, the present invention can be applied to a mechanical device having an electronically controlled solenoid valve.

[0058]

The present invention is embodied in the form described above and has the following effects. According to the solenoid valve according to the first to third aspects of the present invention, the movable valve seat member changes its own posture so that its seat surface is in close contact with the front end surface of the valve member without any gap. It absorbs the variation in the processing tolerance of the tip surface and the sealing surface of the valve seat member, etc., and secures the sealing property between them, and in the valve opening direction against the spring force that urges the valve member accordingly. Since the exciting force of the solenoid that moves the valve member can be weakened, the size of the entire valve does not increase.

The effect of the invention of claim 2 can be obtained also by the invention of claim 4 dependent on the invention of claim 2 and the inventions of claims 5 and 6 dependent on this invention. According to the injector according to the seventh aspect of the present invention, the size of the solenoid valve incorporated in the nozzle body can be reduced, so that the entire injector does not increase in size. The surface of the valve and the seat surface of the valve seat member are tightly closed without gaps regardless of the variation in processing tolerances, etc., and the fuel flow path is securely closed so that high-pressure fuel does not leak from the solenoid valve. There is no danger that the fuel oil will fluctuate or the fuel will not be continuously injected, and the fuel can be properly injected.

[Brief description of the drawings]

FIG. 1 is a system diagram schematically showing a configuration of an electronic fuel injection system for a diesel engine having an injector according to a first embodiment of the present invention.

FIG. 2 is a sectional view schematically showing a configuration of an injector according to the first embodiment.

FIG. 3 is an enlarged cross-sectional view showing a planar seal structure of an electromagnetic valve provided in the injector shown in FIG. 2;

FIG. 4 is a sectional view showing a planar seal structure of an electromagnetic valve provided in an injector according to a second embodiment of the present invention.

FIG. 5 is a sectional view showing a planar seal structure of an electromagnetic valve provided in an injector according to a third embodiment of the present invention.

FIG. 6 is a sectional view showing a planar seal structure of an electromagnetic valve provided in an injector according to a conventional example.

[Explanation of symbols]

 Reference Signs List 8 injector, 10 solenoid valve, 21 nozzle body, 22 seat part, 22a body seat surface, 23 injection hole, 24 nozzle needle, 31 valve seat member holder, 31a bearing recess, 32 valve Member guide, 33: valve seat member, 33a: seat surface of valve seat member, 34: valve member, 34a: fluid passage of valve member, 34b: distal end surface of valve member, 35: armature, 36: solenoid, 37: coil Spring 55: Needle biasing spring 56: Back pressure chamber 57: Restriction passage 60: Chamber 62: Valve seat member 62a: Seat surface 65: Valve seat member 66a: Seat surface

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI F02M 47/00 F02M 47/00 A

Claims (7)

[Claims] An electromagnetic valve for opening and closing a flow path by bringing a distal end surface of a valve member reciprocated in an axial direction into and out of contact with a seat surface of a valve seat member by a force relationship between an exciting force of a solenoid and an urging force of a spring. 2. The electromagnetic valve according to claim 1, wherein the valve seat member is provided so as to be freely movable so that the valve seat member changes its own posture and moves in accordance with the distal end surface of the valve member. 2. The solenoid valve according to claim 1, wherein said valve member is formed of a cylindrical body having a fluid passage opening to a front end surface thereof. 3. The valve seat member is formed by a sphere having a flat surface and a part of the seat surface, and the valve seat member is freely movable to a valve seat member holder comprising a spherical bearing. The solenoid valve according to claim 1, wherein the solenoid valve is supported by a solenoid valve. 4. A valve seat member holder having an upper surface opened and filled with a fluid, wherein the valve seat member is movably accommodated in the chamber by the pressure of the fluid. 3. The solenoid valve according to 2. 5. The solenoid valve according to claim 4, wherein said freely movable valve seat member is a sphere. 6. The solenoid valve according to claim 4, wherein said freely movable valve seat member has a flat seat surface on an upper surface thereof. 7. A nozzle body having an injection hole for injecting fuel, a nozzle needle for opening and closing the injection hole is housed in a reciprocating manner, and a back pressure applied to the nozzle needle is incorporated in the nozzle body. 7. An injector which opens and closes the injection hole by controlling with an electromagnetic valve, wherein the electromagnetic valve uses the one according to any one of the claims 1 to 6.