JP2006170168A - Solenoid valve for injector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new construction of a solenoid valve for an injector preventing wear of an armature and capable of maintaining operation accuracy of a valve element for a long period of time. <P>SOLUTION: This solenoid valve for the injector has a construction moving the armature 22 in a low pressure fuel chamber 18 between a solenoid core 14 and a valve seat 13, controlling circulation of fuel for injection control by the valve element 21 constructed as one unit with the armature 22 and controlling fuel injection. The armature 22 is provided with a stopper 24 arranged between the armature 2 and the solenoid core 14 and abutting on the solenoid core 14 at a time of attraction of the armature 22. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a common rail fuel injection device provided in a diesel engine, and more particularly to an injector solenoid valve that injects fuel supplied from the common rail.

Conventionally, a common rail type fuel injection device provided in a diesel engine has been well known, and a specific structure of an injector that injects fuel supplied from the common rail is also well known (see, for example, Patent Document 1). ).
An electromagnetic valve for controlling the back pressure of the command piston to control fuel injection from the nozzle is provided at the upper part of the injector.
The conventional configuration of this solenoid valve is as in the examples shown in FIGS. In this electromagnetic valve 60, the solenoid coil 50 is energized, the armature 53 integrally formed with the valve body 52 is sucked upward, the valve seat 54 closed by the valve body 52 is opened, and the low pressure fuel High pressure fuel is allowed to flow out into the chamber 55. Further, when the solenoid coil 50 is not energized, the valve body 52 is urged downward by a spring 56 provided in the solenoid core 51, and the valve seat 54 is closed.

A cylindrical stopper 57 is provided around the spring 56 built in the solenoid core 51, and the valve body 52 is received by the stopper 57, and between the upper surface of the armature 53 and the lower surface of the solenoid core 51. An air gap 58 of several tens of microns is secured, so that the armature 53 is prevented from coming into close contact with the solenoid core 51, and the returning operation of the valve body 52 downward by the biasing force of the spring 56 can be performed smoothly.
The armature 53 is provided with a plurality of through holes 53a and 53a in the vertical direction. When the armature 53 moves up and down, the fuel passes through the through holes 53a and 53a and flows from the fuel. Resistance is reduced.
Japanese Patent Laid-Open No. 10-131827

However, in the above-described conventional configuration, if the stopper 57 is provided in the solenoid core 51, the inner diameter of the solenoid core 51 becomes large, which is disadvantageous in terms of magnetic characteristics. That is, the suction force of the armature 53 generated in the solenoid core 51 is weakened, and the accuracy of the operation of the valve body 52 is deteriorated.
Furthermore, the presence of the above-described through holes 53a and 53a also leads to a decrease in the suction force of the armature 53 and is related to a decrease in operation accuracy.
Such a problem of the attractive force of the armature 53 can be dealt with by increasing the size of the solenoid core 51 or the armature 53, but it creates new problems such as an increase in size and weight of the entire solenoid valve. It will be.

  Further, in order to solve the above problem, if the projection provided on the upper surface of the armature 53 is received by the solenoid core 51, the armature 53 will collide with the lower surface 51a of the solenoid core 51, and the stopper 57 is unnecessary. Thus, the inner diameter of the solenoid core 51 can be reduced. However, the armature 53 may be made of a magnetic material, and the armature 53 is worn by the collision, and the accuracy of the operation of the valve body 52 is deteriorated.

  Therefore, the present invention proposes a novel electromagnetic valve configuration that prevents the armature from being worn, can maintain the operation accuracy of the valve body for a long period of time, and can further reduce the size of the device.

  The problem to be solved by the present invention is as described above. Next, means for solving the problem will be described.

  That is, as described in claim 1, the armature is moved in the low-pressure fuel chamber between the solenoid core and the valve seat, and the flow of fuel for injection control is controlled by the valve body configured integrally with the armature. A solenoid valve of an injector configured to control fuel injection, wherein the armature is provided with a stopper that is disposed between the armature and the solenoid core and that contacts the solenoid core when the armature is sucked And

  Further, as described in claim 2, the stopper is constituted by a coating layer.

  Further, as described in claim 3, the stopper is formed in an annular shape.

  According to a fourth aspect of the present invention, a plurality of groove portions are provided at a plurality of locations of the stopper so as to communicate the inner space and the outer space of the stopper.

  As effects of the present invention, the following effects can be obtained.

  That is, according to the first aspect of the invention, the armature does not directly collide with the solenoid core, and wear of the armature can be prevented. By preventing the wear of the armature, the durability of the valve body can be improved and the operation accuracy can be maintained for a long time.

  Further, in the invention described in claim 2, the stopper can be configured without requiring machining, and the thickness can be adjusted more easily than machining. Moreover, the dimension of an air gap can be set with the thickness of a coating layer.

  In the invention of claim 3, when the annularly configured stopper forms an oil chamber and the valve body moves to the solenoid side, the flow resistance of the fuel flowing out from the oil chamber causes the solenoid core to The impact at the time of collision is reduced, that is, a damper effect can be obtained.

  In the invention according to claim 4, it is possible to facilitate the inflow of fuel between the armature and the solenoid core, and to smoothly move the valve body by the biasing force of the spring. Further, the flow resistance received from the fuel can be reduced, and the suction operation can be performed smoothly.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In the following description, it is assumed that the vertical positional relationship is defined with the upper side in FIG. 1 being the upper side and the lower side being the lower side.

  As shown in FIG. 1, an injector 1 includes an injector body 2, an electromagnetic valve 3 that is attached to the upper portion of the injector body 2, controls the back pressure of the command piston 4, and controls fuel injection, and the injector body 2. The command piston body 5 is attached to the lower portion of the command piston 4 so that the command piston 4 is slidably provided therein, and the nozzle body is attached to the lower portion of the command piston body 5 and the needle valve 6 is provided slidably therein. 7. With this configuration, high-pressure fuel supplied from a common rail (not shown) to the fuel supply path 8 is injected from the nozzles 7 a and 7 a provided at the tip of the nozzle body 7.

As shown in FIGS. 1 and 2, in the electromagnetic valve 3, the orifice plate 12 and the valve seat 13 are integrated with the injector body 2 by the valve pressing member 11, and the solenoid core 14 is built in the valve pressing member 11. The cap 15 is fixed.
The valve seat 13 is provided with a shaft-shaped valve body 21 that can slide up and down. The valve body 21 is always urged downward by the elastic force of the spring 16 built in the spring chamber 14 s of the solenoid core 14, and the valve body seat surface 21 a is abutted against the valve seat seat surface 13 a of the valve seat 13. By doing so, the outflow of fuel from the high pressure oil passage 13 b to the low pressure fuel chamber 18 is restricted, and the back pressure of the command piston 4 is secured through the control oil passage 9. The back pressure causes the command piston 4 to move downward to press the needle valve 6 downward, thereby restricting fuel injection.

An armature 22 is fixed to the upper part of the valve body 21.
The armature 22 is disposed so as to be vertically movable in a low-pressure fuel chamber 18 formed between the solenoid core 14 and the valve seat 13.
When the solenoid coil 17 is energized, the armature 22 is moved upward together with the valve body 21, the valve body seat surface 21a is separated from the valve seat surface 13a, and the fuel in the high pressure oil passage 13b is low pressure fuel. It flows out into the chamber 18. As a result, the high pressure fuel in the control oil passage 9 flows out to the low pressure fuel chamber 18, and the back pressure of the command piston 4 is reduced. The needle valve 6 is lifted by the high-pressure fuel supplied to the nozzle fuel chamber 6a, and fuel is injected.
As described above, the armature 22 is moved in the low-pressure fuel chamber 18 between the solenoid core 14 and the valve seat 13, and the fuel for injection control is distributed by the valve body 21 configured integrally with the armature 22. It is the structure which controls and fuel-injection.

The armature 22 has a disk shape as shown in FIGS.
The armature 22 is provided with a stopper 24 that is disposed between the armature 22 and the solenoid core 14 and is brought into contact with the solenoid core 14 when the armature 22 is sucked.
Due to the presence of the stopper 24, as shown in FIG. 4, when the armature 22 is sucked, the upper surface 24u of the stopper 24 abuts against the bottom surface 14a of the solenoid core 14, so that the upper surface 22u of the armature 22 directly collides with the solenoid core 14. The armature 22 can be prevented from being worn. Further, by preventing the armature 22 from being worn, the operation accuracy of the valve element 21 can be maintained for a long time.
Further, since the upper surface 24 u of the stopper 24 contacts the bottom surface 14 a of the solenoid core 14, an air gap 25 can be secured between the upper surface 22 u of the armature 22 and the bottom surface 14 a of the solenoid core 14. By this air gap 25, the armature 22 is not brought into close contact with the solenoid core 14, and the returning operation of the valve body 21 downward by the urging force of the spring 16 is smoothly performed.
Further, since the stopper 57 on the solenoid core 51 side shown in the conventional configuration of FIG. 6 is not provided, as shown in FIG. 2, the inner diameter of the spring chamber 14s can be reduced, that is, a large volume of the solenoid core 14 is secured. Will be able to. Thereby, good magnetic properties can be obtained.
Further, due to this good magnetic property, the solenoid core 14 and the armature 22 can be downsized, and further, the entire solenoid valve 3 can be downsized. Further, the downsizing of the armature 22 can reduce the inertial force and fuel resistance applied to the armature 22.

As shown in FIG. 3, the stopper 24 is formed in an annular shape.
With this annular structure, as shown in FIG. 4, when the armature 22 is attracted to the solenoid core 17, it is surrounded by the inner side surface 24 b of the stopper 24, the upper surface 22 u of the armature 22, and the bottom surface 14 a of the solenoid core 14. The fuel is temporarily confined in the minute space 28 formed.
The impact of the stopper 24 colliding with the solenoid core 14 is mitigated by the flow resistance of the fuel flowing into and out of the minute space 28, that is, a damper effect can be obtained.

Further, as shown in FIGS. 3 and 4, grooves 24 c and 24 c are provided at a plurality of locations of the stopper 24 to communicate the inner space and the outer space of the stopper 24.
The presence of the grooves 24c and 24c enables the fuel to flow between the minute space 28 closed by the stopper 24 and the low-pressure fuel chamber 18. By adjusting the behavior of the fuel flowing into and out of the minute space 28 by the groove portion 24c, it is possible to adjust the buffer characteristic when sucked by the solenoid core 14. And it becomes easy to flow a fuel between the armature 22 and the solenoid core 14, and the responsiveness of the return operation | movement to the downward direction of the valve body 21 can be improved.

With the above configuration, when the solenoid coil 17 is energized and the armature 22 is attracted, the fuel existing above the armature 22 can overflow from the grooves 24c and 24c, and the flow received from the fuel. The resistance can be reduced and the suction operation can be performed smoothly.
Further, when the energization of the solenoid coil 17 is released and the valve body 21 moves downward by the spring 16, inflow of fuel from the low pressure fuel chamber 18 to the minute space 28 is allowed, The valve body 21 can be smoothly moved downward. If the grooves 24c and 24c are not provided, the armature 22 is brought into close contact with the solenoid core 14 through the fuel confined in the minute space 28, and the responsiveness of the return operation of the valve body 21 may be reduced. . For this reason, the precision of fuel injection control is maintained by providing the grooves 24c and 24c.
The number and width of the grooves 24c and 24c are not particularly limited, and are appropriately set according to the speed required for the valve body 21 and the sizes of the valve body 21 and the armature 22. .

In the second embodiment, as shown in FIG. 5, a wear-resistant coating layer 29 such as chromium nitride (CrN) is formed on the surface (upper surface 22 u) of the armature 22 facing the solenoid core 14. Reference numeral 29 denotes a stopper.
According to the wear-resistant coating layer 29, it is possible to prevent the upper surface 22u of the armature 22 made of a magnetic material from being worn, and the operation accuracy of the valve body 21 can be maintained for a long time.

Moreover, according to the structure of Example 2, a stopper can be comprised without requiring a machining and the dimension of an air gap can be set with the thickness.
In addition, the dimension setting can be realized with high accuracy, and the air gap can be suppressed to the minimum necessary, so that good magnetic characteristics can be obtained.
Further, due to this good magnetic property, the solenoid core 14 and the armature 22 can be downsized, and further, the entire solenoid valve 3 can be downsized.
In the second embodiment, the same effect as in the first embodiment can be obtained by providing the grooves 29c and 29c.

The figure shown about the structure of the injector provided with the solenoid valve concerning this invention. The figure similarly shown about the structure of a solenoid valve. The figure shown about the structure of the armature of Example 1. FIG. The figure similarly shown about the state by which the armature was attracted | sucked. The figure shown about the structure of the armature of Example 2. FIG. The figure shown about the structure of the conventional solenoid valve. The figure shown about the structure of the stopper of the conventional solenoid valve.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Injector 3 Solenoid valve 13 Valve seat 14 Solenoid core 16 Spring 18 Low pressure fuel chamber 21 Valve body 22 Armature 24 Stopper

Claims (4)

  An injector configured to control fuel injection by moving an armature in a low-pressure fuel chamber between a solenoid core and a valve seat, and controlling the flow of fuel for injection control by a valve body configured integrally with the armature. An electromagnetic valve for an injector, wherein the armature is provided with a stopper that is disposed between the armature and the solenoid core and that contacts the solenoid core when the armature is attracted.   The injector solenoid valve according to claim 1, wherein the stopper is formed of a coating layer.   3. The injector solenoid valve according to claim 1, wherein the stopper is formed in an annular shape.   4. The injector solenoid valve according to claim 3, wherein a groove portion is provided at a plurality of locations of the stopper so as to communicate the inner peripheral space and the outer peripheral space of the stopper.

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