CN1208547C - Electromagnetic valve and fuel jet device - Google Patents

Abstract

In a solenoid valve (40) used in a fuel injection device (1), the distance D between the facing surfaces of an armature (60) and a fixing member (60) is set when the valve is closed In 5μm to 60μm. Since the upper limit of the distance D is 60 μm, after a coil (43) is de-energized and just before the moving part finishes moving, the moving part will receive a sudden increase in direction from the fluid superimposed between the moving part and the fixed part. The reaction force of the magnetic core is fixed, so that the collision impact generated when a valve part (50) is supported on the second plate (82) is relieved, and the jumping of the valve part is limited. Furthermore, since the lower limit of the distance D is 5 μm, after the coil is charged and the moving part is ready to start moving, the movement initiation time of the moving part is not significantly delayed by the adhesive force of the fluid superimposed between the moving part and the fixed part.

Description

Solenoid valve and fuel injection device

technical field

The present invention relates to a solenoid valve and a fuel injection device equipped with the solenoid valve.

Background technique

In a conventional solenoid valve, a valve member actuated by electromagnetic force operates to open and close an opening for fluid to flow through. For example, in a solenoid valve that opens an opening by energizing a coil, when the coil is not energized, the valve member is pushed by a urging means such as a spring in the opening closing direction and rests on the valve seat to close the opening. When the coil is energized, a movable member is attracted to a fixed magnetic core by an electromagnetic force generated in a fixed magnetic core surrounding the coil, so that the valve member moves with the movable member to open the opening. The valve element moves under the guidance of a fixed element opposite to the movable element.

When the valve member leans against the valve seat to close the opening, the valve member will forcibly collide against the valve seat forming the opening under the thrust of the pushing device. As the valve part moves at extremely high speeds and hits the seat, a shock occurs between the valve part and the seat, causing the valve part to bounce on the seat. The opening will be forced open over multiple beats. Therefore, in a solenoid valve used in, for example, a fuel injection device, the jumping of the valve member will cause a drop in fuel pressure in a pressure control chamber for pushing the valve needle in the direction of closing the injection hole to open and close the injection hole, thereby causing the fuel pressure to drop. Squirting over a given time.

In order to solve the valve bouncing problem, an electromagnetic metering valve used in a fuel injection device is known, as disclosed in JP-A-9-166063. According to this electromagnetic metering valve, the jumping of the valve member when it hits the valve seat is limited by a moving member, which is made of two elements for the purpose of reducing the weight of the moving member.

However, the moving part made of two elements leads to a complicated structure of the solenoid valve, and thus a large size of the solenoid valve.

Contents of the invention

An object of the present invention is to provide a solenoid valve in which the jumping of the valve member is limited when it hits the valve seat without making the solenoid valve too large. Jetting device.

Another object of the present invention is to provide a solenoid valve in which electromagnetic attraction force for attracting a moving member toward a fixed magnetic core is stronger, and to provide a fuel injection device equipped with the solenoid valve.

In order to achieve the above object, the present invention proposes a solenoid valve, which is installed on a valve seat member, the valve seat member has an opening for flowing fluid and a valve seat surrounding the opening, the solenoid valve has: A valve part, which is used to rest on or leave the valve seat to open or close the opening; a moving part, which moves axially with the valve part; a fixed magnetic core, which surrounds a coil, when When the coil is charged, the moving part is attracted to the fixed magnetic core by the generated magnetic force; and a fixed part, one end face of which is opposite to the end face on the opposite side of the fixed magnetic core on the moving part, and the other end face faces the valve seat part, It is characterized in that: when the valve member closes the opening, the distance D between the opposite end surfaces of the movable member and the fixed member is located within a predetermined range with a lower limit and an upper limit, so that the lower limit is set as such a distance, that is, on the line After the ring is charged and the moving part is ready to start moving in the opening opening direction, the movement start time of the moving part will not be delayed due to the adhesive force of the fluid superimposed between the moving part and the fixed part, and the upper limit is set to such a The distance, that is, after the coil is de-energized and just before the moving part ends its movement in the direction of opening closure, the moving part will receive a sudden increase in the reaction directed towards the fixed core from the fluid superimposed between the moving part and the fixed part force, the lower limit of the distance D is 5 μm, and the upper limit of the distance D is 60 μm.

Preferably the moving member is integrally formed with at least one portion of the valve member. Since the moving part and the valve part do not need to be joined together by welding or other joining elements, the weight of the valve part is lighter and less electromagnetic attraction force needs to be generated between the fixed magnetic core and the moving part. Therefore, the body size of the fixed core and coil is more compact, and the current consumption of the coil is smaller.

The axial lengths of the valve part and the fixing part are each subject to manufacturing dimensional tolerances. Therefore, preferably, after measuring the axial lengths of a plurality of valve parts and fixing parts, any one of the valve parts and any one of the fixing parts is selectively assembled so that the distance D is within a predetermined range from the lower limit to the upper limit.

The valve element is composed of a contact element and a shaft element, the contact element is used to support on the valve seat, one end of the shaft element holds the contact element, and the other end is combined with the moving part. In this case, the axial length of the valve member is the sum of the axial lengths of the contact element and the shaft element.

Furthermore, it is also preferred that the fixing element is composed of first and second fixing elements having different axial lengths. After measuring the axial lengths of a plurality of first and second fixing parts, any one of the first fixing parts and any one of the second fixing parts are selectively assembled so that the distance D is located at a predetermined value with a lower limit and an upper limit. within range.

Furthermore, it is also preferable that the fixing member is made of a material having a yield point value to such an extent that the fixing member is not plastically deformed when the fixing member is strongly pressed against the valve seat member. In this way, a fluid-tight seal between the stationary part and the valve seat part can be ensured.

In addition, it is preferred for the fixing part to have a non-magnetic element made of a non-magnetic material. The nonmagnetic element may be arranged on the fixing piece at one end on the side of the fixed magnetic core, or the fixing piece itself may be made of a nonmagnetic material. With this structure, the magnetic flux leaked to the fixed member from the magnetic circuit constituted by the fixed magnetic core and the movable member is suppressed, thereby effectively increasing the electromagnetic attractive force between the fixed magnetic core and the movable member.

In addition, the moving member is provided with cutouts on its outer circumference, each cutout having a given depth and extending in the axial direction. These cutouts can not only be used to limit the eddy current generated in the moving part due to electromagnetic attraction, but also can smoothly discharge the fluid superimposed between the moving part and the fixed part.

The moving part can also be provided with a through hole at a position facing the fixed magnetic core between the inner magnetic pole surface and the outer magnetic pole surface, and each through hole passes through in the axial direction. The through-openings are used to discharge fluid superimposed between the moving part and the fixed part without negatively affecting the electromagnetic attraction force, since the through-openings are arranged at positions where no magnetic circuit is formed.

It is also preferable to make the area of the inner magnetic pole surface larger than the area of the outer magnetic pole surface. This structure is used to increase the electromagnetic attraction, because the magnetic flux flowing from the inner pole surface is blocked by the outer pole surface.

Description of drawings

Other features and advantages of the invention, as well as the method of operation and the function of the associated parts, will be understood from the following detailed description, appended claims and accompanying drawings, which form a part hereof. In the attached picture:

1 is a sectional view of a fuel injection system equipped with a solenoid valve according to a first embodiment of the present invention;

Fig. 2 is a partially enlarged view of the solenoid valve in Fig. 1;

Fig. 3 is another partial enlarged view of the solenoid valve in Fig. 1;

Fig. 4 is a sectional view taken along line IV-IV among Fig. 3;

Figure 5 is a graph of the relationship between valve member position and elapsed time after a valve closing command versus distance D;

Figure 6 is a graph of the relationship between valve member position and elapsed time after a valve opening command versus distance D;

Fig. 7 is a graph of the relationship between the distance D and the valve opening time delay, which is used to determine the setting range of the distance D;

8 is a partially enlarged cross-sectional view of a solenoid valve according to a second embodiment of the present invention;

Fig. 9 is a top view of the fixing part in the solenoid valve in Fig. 8 viewed from the side of the armature.

Detailed ways

(first embodiment)

A solenoid valve used in a fuel injection device according to a first embodiment will be described below with reference to FIGS. 1 and 2 . High-pressure fuel is supplied into the fuel injection device 1 by a fuel pump (not shown) from a common rail (not shown) where fuel is accumulated at a predetermined pressure.

The fuel injection device 1 mainly includes a nozzle body 10 , a valve needle 20 , a valve body 30 and a solenoid valve 40 .

The valve needle 20 is slidably accommodated within the inner circumference of the nozzle body 10 formed into a substantially cylindrical shape. The nozzle body 10 is provided with an injection hole 11 at its front end and a fuel pool 12 for storing high-pressure fuel inside it.

The valve needle 20 moves axially repeatedly in the inner circumferences of the nozzle body 10 and the valve body 30 . The valve needle 20 has a sliding portion 21 slidable within the inner circumference of the nozzle body 10 . The valve needle 20 is provided with a frustoconical portion 22 and a conical portion 23 on the injection hole 11 side with respect to the sliding portion 21 . The surface boundary between the frustoconical portion 22 and the conical portion 23 forms a contact portion 24 which bears against a valve seat 13 formed in the nozzle body 10 on the inlet side of the spray hole 11 .

The valve body 30 is fixed on the nozzle body through a stop nut 31 . A control piston 32 is accommodated in the valve body 30 for axial movement. One end of the control piston 32 on the injection hole 11 side is in contact with the valve needle 20 . A pressure chamber 33 is formed in the first plate 81 and at the end of the control piston 32 on the opposite side to the injection hole 11 .

The valve body 30 is provided with a high-pressure fuel conduit 34 through which high-pressure fuel is supplied into the valve body. The high-pressure fuel conduit 34 communicates with a first high-pressure fuel conduit 341 and a second high-pressure fuel conduit 342 . The first high-pressure fuel conduit 341 axially extends in the valve body 30 and the nozzle body 20 and communicates with the fuel pool 12 . The second high-pressure fuel conduit 342 communicates with the pressure control chamber 33 and the low-pressure conduit 401 in the solenoid valve 40 . A part of the fuel supplied into the second high-pressure fuel conduit 342 is supplied into the pressure control chamber 33 through a fuel conduit 811 passing through the first plate 81 . Another part of the fuel supplied into the second high-pressure fuel conduit 342 is injected into the low-pressure conduit 401 through the fuel conduit 821 and the shut-off gate 822 formed in the second plate 82, which constitutes a valve seat.

A spring chamber 35 in which a spring 351 is arranged is provided in the valve body 30 . The spring 351 pushes the needle 20 in a direction to close the injection hole 11 .

As shown in FIG. 3 , the first and second plates 81 and 82 are disposed on the injection hole 11 at one end on the opposite side of the injection hole 11 . As shown in Figures 1 and 3, the pressure control chamber 33 consists of the end surface 81a on the side facing the injection hole 11 on the first plate 81, the inner peripheral surface of the valve body 30 and the position on the control piston 32 opposite to the injection hole 11. side end face 32a. As shown in FIG. 3 , a fuel conduit 811 is provided in the first plate 81 , and the conduit communicates with the high-pressure fuel conduit 342 and a cut-off valve 812 at one end of the fuel conduit 811 . A fuel groove 813 is also provided in the first plate 81 , one end of which communicates with the fuel conduit 811 through the cut-off gate 812 , and the other end communicates with the through hole 814 passing through the first plate 81 . One end of the through hole 814 communicates with the fuel conduit 821 , and the other end communicates with the pressure control chamber 33 .

The second plate 82 is disposed on the opposite side of the injection hole 11 with respect to the first plate 81 , and is provided with a shut-off gate 822 at an end of the fuel conduit 821 on the opposite side of the injection hole 11 . The fuel conduit 821 is provided with an opening at one end thereof on the solenoid valve 40 side. A valve seat 82a is provided around the opening, on which the solenoid valve 40 rests, as shown in FIG. 2 .

The solenoid valve 40 is a two-way valve, which can operate to interrupt the connection between the pressure control chamber 33 and the low pressure conduit 401 . The solenoid valve 40 is disposed on the valve body 30 at one end on the opposite side of the injection hole 11 . The solenoid valve 40 is fixed on the valve body 330 through a limit nut 41 .

As shown in FIGS. 1 to 3 , the solenoid valve 40 is mainly composed of a fixed magnetic core 42 , a valve element 50 , an armature 60 constituting a movable element, and a fixed element 70 .

The fixed core 42 surrounds a coil 43 in a wound state. Current is supplied into the coil 44 through a connector 44 . The fixed core 42 is made of ferromagnetic material. The fixed core 42 is provided on its end face on the armature 60 side with an inner magnetic pole surface 42a and an outer magnetic pole surface 42b. The area of the inner magnetic pole surface 42a is larger than the area of the outer magnetic pole surface 42b. The area ratio between the inner magnetic pole surface 42a and the outer magnetic pole surface 42b is in the range of 1.0 to 2.0.

The fixed core 42 is shaped into a substantially cylindrical shape. A spring 45 is arranged within the inner circumference of the fixed core 42 . The spring 45 pushes the valve member 50 towards the second plate 82 . An adjustment tube 46 is used to adjust the thrust of the spring 45 .

The armature 60 made of ferromagnetic material is shaped like a disc. The armature 60 can be attracted to the fixed magnetic core 42 by the electromagnetic attraction generated on the fixed magnetic core 42 .

The valve member 50 includes a shaft 51 constituting a shaft member and a ball 52 constituting a contact member. The shaft 51 is integral with the armature 60 and moves axially together with the movement of the armature 60 . The ball 52 is rotatably held by the end of the shaft 51 on the opposite side to the armature 60 .

When the armature 60 is attracted to the fixed magnetic core 42 by the electromagnetic attraction generated between the fixed magnetic core 42 and the armature 60, since the shaft 51 and the armature 60 are both made of ferromagnetic materials, they are integrally formed, so The shaft 51 will move towards the fixed magnetic core 42 together with the armature 60 .

As shown in FIG. 4 , the armature 60 is provided with notches 61 on its outer circumference, each of which has a predetermined depth and extends in the axial direction. According to a first embodiment, three cutouts 61 are arranged at constant angular intervals. The armature 60 is also provided with through holes 62, which are at a position opposite to the surface of the fixed magnetic core 42 between the inner magnetic pole table 42a and the outer magnetic pole surface 42b, that is, surrounded by the fixed magnetic core 42 on one side. The position of the attached coil 62 axially passes through the armature 60. Three through holes 62 are arranged at constant angular intervals in the circumferential direction.

The cutout 61 and the through hole 62 are formed to discharge excess fuel stacked between the armature 60 and the fixing member 70 . In addition, the notch 61 can effectively limit the eddy current generated in the armature 60 due to electromagnetic attraction.

In order to efficiently discharge the fuel between the armature 60 and the fixing member 70, it is desirable to form many cutouts 61. However, as the number of cutouts 61 increases, the magnetic pole area of the armature decreases, thereby weakening the electromagnetic attractive force between the fixed magnetic core 42 and the armature 60 . According to the first embodiment, the through hole 62 is used to easily discharge the fuel between the armature 60 and the fixing piece 70 . The through hole 62 is provided at a position facing the coil 43 where no magnetic circuit will be formed, so the magnetic pole area of the armature 60 will not be reduced.

The ball 52 is partially cut away to have a flat portion 521 . Since the ball 52 is rotatably held by one end of the shaft 51, the flat portion 521 is always kept in surface contact with the valve seat 82a of the second plate 82. As the armature 60 and shaft 51 move towards the stationary core 42, the ball 52 moves towards the stationary core 42 due to the fuel pressure acting on the flat surface 521 of the ball 52 to open the opening.

The fixing base 70 is formed into a substantially cylindrical shape and has a through hole 71 in the center thereof. A bushing 72 is press-fitted in the through hole 71, and the shaft 51 is rotatably movable in the bushing. The fixing member 70 is made of non-magnetic material. Therefore, there will be no magnetic flux leaking from the magnetic circuit formed by the fixed core 42 and the armature 60 to the fixed member 70, so that the electromagnetic flux generated between the fixed core 42 and the armature 60 can be caused when the coil 43 is charged. Gravity increases.

Next, the distance D between the armature 60 and the fixing part 70 will be described.

As shown in Figure 2, when the ball 52 rests on the valve seat 82a, that is, when the valve is closed, the surface 60a on the armature 60 on the side of the fixed part 70 and the surface on the side of the armature 60 on the fixed part 70 The distance D between 70a is set within a given range. According to a first embodiment, the lower limit of the given distance is 5 μm and the upper limit is 60 μm. The area of the armature 60 facing the fixed core 42 , that is, the area of the armature 60 on the side of the fixed core 42 is 150 mm ² .

The reasons for setting the above lower limit and upper limit are explained below.

Figure 5 shows the relationship between the position of the valve member 50 and the elapsed time after the valve closing command, ie, after the supply of current to the coil 43 has ceased, with respect to various changes in the distance D.

If the distance D is longer than 60 μm, for example, the distance D is 100 μm or 1000 μm, as shown in FIG. 5 , the valve member 50 will bounce when the valve is closed. The beating of the valve element 50 is the axial reciprocating movement of the valve element 50 caused by the pushing force of the spring 45 to push the valve element 50 , thus colliding with the second plate 82 at a high speed. Since the valve member 50 moves at a high speed in a short time and impacts against the second plate 82 , the valve member 50 bounces repeatedly on the second plate 82 . Therefore, even if the current supplied to the coil 43 is terminated and the electromagnetic attractive force between the fixed core 42 and the armature 60 disappears, the opening of the second plate 82 cannot be completely closed. In the case of the fuel injection device 1 employing the solenoid valve 40, when the opening is not completely closed, the pressure in the pressure control chamber 33 changes to move the needle 20. Therefore, the injection hole 11 cannot be completely closed by the needle 20, resulting in fuel injection exceeding a given time after the supply of electric current to the coil 43 is terminated. As a result, incomplete combustion of the fuel in the internal combustion engine has a negative effect on exhaust emissions.

According to a first exemplary embodiment, a gap is provided between the armature 60 and the fastening part 70 so that fuel can penetrate into the gap. When the ball 52 of the valve element 50 abuts against the valve seat 82a, the fuel interposed between the armature 60 and the fixing element 70 is squeezed. The pressurized fuel imparts a reaction force to the armature 60 acting upwardly in FIG. 2 , ie, toward the stationary core 42 . The reaction force experienced by the armature 60 serves to reduce the speed at which the valve member 50 moves together with the armature 60 just before the valve member 50 bears against the valve seat 82a. As a result, when the valve member 50 is abutted against the valve seat 82a, the shock to the valve member 50 is relieved, and the bounce of the valve member 50 is restricted.

When the jumping of the valve member 50 is lower than the allowable limit shown in FIG. Move so that fuel injection can be prevented beyond a given time. According to a first embodiment, the upper limit of the distance D is 60 μm.

Figure 6 shows the relationship between the position of the valve member 50 and the elapsed time after the start of supplying current to the coil 43 after the valve opening command for various changes in the distance D.

In the case where the distance D is shorter than 60 μm, the bounce of the valve member 50 is restricted. However, if the distance D is too short, for example, when the distance D is 3 μm, as shown in FIG. 6 , the valve opening time is greatly delayed. This delay is caused by the adhesive force of the fuel superimposed between the surface 60 a of the armature 60 and the surface 70 a of the holder 70 .

The surface 60a of the armature 60 and the surface 70a of the fixing member 70 are smooth ground. Since the distance D is very small, even though the valve member 50 is driven to lift when the valve is opened, thus extending the space between the facing surfaces 60a and 70a on the armature 60 and the fixed member 70, due to the existence of the surface Since a negative pressure is generated between 60a and 70a, the fuel flowing into this space cannot follow. Thus, even if current supply to the coil 43 is started and electromagnetic attraction is generated between the fixed core 42 and the armature 60, the armature 60 does not move until the electromagnetic attraction becomes greater than the generated negative pressure, so the valve opening time is delayed.

In the fuel injection device 1 equipped with the solenoid valve 40, since the valve opening time is delayed, the injection time of fuel is delayed from the predetermined time. This will cause incomplete combustion of the fuel, resulting in undesirable exhaust gases from the internal combustion engine.

When the distance D is, for example, 5 μm, as shown in FIG. 6 , the delay of the valve opening time becomes shorter than when the distance D is 3 μm, but it does not change much compared to when the distance D is 1000 μm. Therefore, in order to ensure that the valve opening time is within the allowable delay time, it is desirable that the distance D is not less than 5 μm.

As a result of the above investigation, the relationship between the distance D and the runout when the valve is closed and the relationship between the distance D and the valve opening time delay when the valve is opened are shown in FIG. 7 . As shown in FIG. 7 , the distance D is set within a range between upper and lower limits, ie, 5 μm≦D≦60 μm.

Next, a method of adjusting the distance D is described.

In order to ensure the allowable valve opening time and allowable run-out of the valve member 50, the distance D must be precisely adjusted. The valve member 50 is composed of a shaft 51 and a ball 52 . The height of the ball 52 in the axial direction of the valve member 50 lies within a manufacturing dimensional tolerance of ±15 μm. Likewise, the axial length of the armature 60 and the shaft 51 formed integrally by machining or cold forging is also within the manufacturing dimensional tolerance of ±15 μm. Among the plurality of integral elements and the plurality of spheres 52 constituting the armature 60 and the shaft 51, any one integral element 60 and 51 and any one sphere 52 are selectively assembled together so that their axial lengths lie within a given range. within a certain range.

Furthermore, the fixing part 70 has similar manufacturing dimensional tolerances as the valve part 50 . The fixing member 70 whose axial length is selected is assembled with the valve member 50 to set the distance D to a value within a predetermined range.

Furthermore, the fixing member 70 may be made from two elements, each of which is formed in a plate shape respectively. The thicknesses of the plate-shaped elements are selectively combined so that the axial length of the fixing member is adjustable.

Next, the operation of the fuel injection device equipped with the solenoid valve 40 will be described.

When the coil 43 is not energized, the armature 60 and the shaft 51 are pushed in the downward direction in FIG. 1 by the urging force of the spring 45 . Accordingly, the ball 52 abuts on the valve seat 82a of the second plate 82, so that the opening of the shut-off gate 822 formed in the fuel conduit 821 on the side of the ball 52 is closed.

A part of the fuel supplied from the common rail is delivered and stored in the fuel pool 12 through the high-pressure fuel conduit 341, and another part of the fuel is delivered and stored in the pressure control chamber 33 through the high-pressure fuel conduit 342, the fuel conduit 811, the fuel groove 813 and the through hole 814. . Since the end of the fuel conduit 821 is closed by the ball 52, the fuel pressure in the pressure control chamber 33 is equal to the pressure of the fuel accumulated in the common rail.

In this way, the sum of the thrust acting on the valve needle 20 along the closing direction of the injection hole 11 due to the fuel pressure in the pressure control chamber 33 and the thrust of the spring 351 is greater than that caused by the pressure of the fuel in the fuel pool 12 and near the valve seat 13. Resulting in the force acting on the valve needle 20 along the opening direction of the injection hole 11. Accordingly, the contact portion 24 of the needle 20 abuts on the valve seat 13 to close the injection hole 11, so that fuel is not injected from the injection hole 11.

After the coil 43 is energized, the armature 60 and the shaft 51 are attracted to the fixed core 42 by the electromagnetic attractive force generated between the fixed core 42 and the armature 60 . When the electromagnetic attractive force becomes greater than the pushing force of the spring 45 , the armature 60 and the shaft 51 will move towards the fixed magnetic core 42 . Thus, the ball 52 moves in the upward direction in FIG. 2 due to the fuel pressure in the pressure control chamber 33 acting on the flat surface 521, so that the ball 52 is separated from the valve seat 82a. Therefore, the pressure control chamber 33 communicates with the low-pressure conduit 401 , so that the high-pressure fuel in the pressure control chamber 33 flows out into the low-pressure conduit 401 .

As the high-pressure fuel flows out into the low-pressure conduit 401 , the fuel pressure in the pressure control chamber 33 decreases, so that the force acting on the valve needle 20 in the direction of closing the injection hole 11 decreases. When the force acting on the valve needle 20 in the closing direction of the injection hole 11 becomes smaller than the force acting on the valve needle 20 in the opening direction of the injection hole 11 due to the pressure of the fuel in the fuel pool 12 and in the vicinity of the valve seat 13, The valve needle 20 will be lifted in an upward direction in FIG. 1 to open the injection hole 11 so that fuel is sprayed from the injection hole 11 .

When the current supplied to the coil 43 stops, the armature 60 , the shaft 51 and the ball 52 will move in the downward direction in FIG. 1 under the urging force of the spring 45 . With the flat surface 521 of the ball 52 abutting on the valve seat 82a, the flow of fuel from the pressure control chamber 33 into the low pressure conduit 401 is interrupted. The stop of fuel flowing to the low-pressure conduit 401 will cause the fuel pressure in the pressure control chamber to increase, thereby increasing the force acting on the valve needle 20 in the direction of closing the injection hole 11 . When the force acting on the valve needle 20 in the closing direction of the injection hole 11 becomes greater than the force in the opening direction of the injection hole 11, the contact portion 24 of the valve needle 20 will abut on the valve seat 13 to close the injection hole 11, The fuel injection from the injection hole 11 is thereby stopped.

In the solenoid valve 40 according to the first embodiment, the distance D at which the valve is closed is set to a value in the range of 5 μm to 60 μm. Since the upper limit of the distance D is 60 μm, the fuel superimposed between the opposing surfaces of the armature 60 and the fixing part 70 can be used to relieve the impact caused when the valve part 50 rests on the second plate 82, So that the beating of the valve member 50 is limited. It is not necessary to construct the valve member 50 as two components like conventional solenoid valves, so that the valve member 50 has a compact structure.

Since the lower limit of the distance D is 5 μm, the adhesive force due to the presence of fuel or negative pressure between the armature 60 and the fixing member 70 is relatively small. In this way, the start of movement of the valve member 50 is not delayed too much after the valve opening command, ie after the start of supplying current to the coil 43 .

According to the first embodiment, the armature 60 is provided with a cutout 61 and a through hole 62 . The cut-out 61 and the through-hole 62 are used for draining fuel accumulated between the armature 60 and the fixing part 70 . In this way, the fuel stacked between the armature 60 and the fixing member 70 is not squeezed to a high pressure, so the valve member 50 can move smoothly. Furthermore, the cutout 61 prevents eddy currents from being generated in the armature 60 . In addition, since the through hole 62 is disposed between the inner and outer magnetic pole surfaces 42a and 42b of the fixed magnetic core 42, that is, on the position where the armature 60 faces the coil 43, the magnetic pole area on which the electromagnetic attraction acts will not be reduced, so the electromagnetic attraction will not decrease, while the fuel oil can be easily discharged through the through hole 62.

According to a first embodiment, the fixing member 70 is made of non-magnetic material. Even if the axial length or thickness of the armature 60 is short or thin, leakage of magnetic flux to the fixing member 70 can be suppressed so that the electromagnetic attractive force between the fixed core 42 and the armature 60 is not adversely affected. In addition, since the area ratio between the inner magnetic pole surface 42a and the outer magnetic pole surface 42b of the fixed core 42 is set to an arbitrary value in the range of 1 to 2, the magnetic flux flowing out from the inner magnetic pole surface 42a will be at the outer magnetic pole surface 42b. is blocked, so the electromagnetic attraction between the fixed core 42 and the armature 60 will increase.

According to a first embodiment, the armature 60 and the shaft 51 forming part of the valve member 50 are integrally formed. In this way, since the armature 60 and the shaft 51 do not need to be connected by welding or using other components, the weight of the armature 60 and the shaft 51 is relatively small. Since a small electromagnetic attractive force is enough to attract the armature 60 to the fixed magnetic core 42, the fixed magnetic core 42 or the coil 43 becomes lighter and more compact, and the current consumption of the coil 43 is smaller.

In addition, after measuring the corresponding axial lengths of the combined body composed of the armature 60 and the shaft 51, the ball 52 and the fixing piece 70, which have corresponding manufacturing dimensional tolerances, any combined body and any ball 52 are selectively assembled to form a combined unit of the armature 60 and the valve member 50, so that the overall axial length of the combined unit is within a given range. Afterwards, any one of the fixing members and any one of the combination units are selectively assembled together so that the distance D is within the range of 5 μm to 60 μm. This manufacturing method can be used to increase throughput and thus reduce manufacturing costs.

As previously mentioned, the bounce of the valve member 50 is limited so that the opening can be closed in time. Therefore, there is no undesired pressure change in the pressure control chamber 33 and no undesired change in the thrust force acting on the valve needle 20 . Thus, the fuel is not injected from the injection hole 11 at a time other than the predetermined time, and since the valve opening timing of the valve member 50 is not delayed, the fuel can be injected in time.

(second embodiment)

A solenoid valve used in a fuel injection device according to a second embodiment will be described below with reference to FIGS. 8 and 9 . Parts and elements that are substantially similar to those in the first embodiment are denoted by the same reference numerals and will not be explained again.

The structure of the fixing member 90 in the solenoid valve 40 according to the second embodiment is different from that of the first embodiment. The fixing member 90 is composed of a fixing member body 91 and a non-magnetic member 92, as shown in FIGS. 8 and 9 . The fixing part body 91 is made of iron-based magnetic material, and the non-magnetic part 92 is made of non-magnetic material such as austenitic stainless steel or aluminum. Furthermore, the bushing 72 press-fitted in the through hole 71 in the first embodiment is not used in the through hole 93 provided at the center of the fixing member 90 at this time. Therefore, the shaft 51 of the valve member 50 is directly in sliding contact with the inner surface of the through hole 93 .

The fixture body 91 is made of a material with a relatively high yield point. The fixing part body 91 is not easy to be plastically deformed, even if the fixing part 90 is assembled on the valve body 30 with relatively greater force. The first and second plates 81 and 82 are pushed and squeezed with greater force by the fixing member 90, so that the first plate 81 is rigidly press-fitted on the valve body 30 and tightly superimposed on the second plate 82 to ensure A fluid-tight seal is achieved between the two plates.

The non-magnetic body 92 is arranged on one end of the fixing body 91 on the side of the armature 60 . The non-magnetic member 92 is an annular plate in which an inner hole forms a part of the through hole 93 . The non-magnetic part 92 is embedded in the fixing part body 91 so that the ends of the fixing part body 91 and the non-magnetic part 92 on the side of the armature 60 form the same flat surface. Therefore, the distance between the armature 60 and the fixing member body 91 and the distance between the armature 60 and the non-magnetic member 92 are equal, so that the distance between the armature 60 and the fixing member 90 is easy to adjust. In addition, the outer periphery of one end of the fixing body 91 faces the armature 60, as shown in FIG. In this way, even if the fixture body 91 is strongly fastened to the valve body 30, the stress generated in the fixture body 91 never reaches the yield point. The non-magnetic member 92 is connected to the fixing member body 91 by, for example, laser welding, brazing, stacking or press-fitting. The non-magnetic member 92 for preventing leakage of magnetic flux is formed to be about 1 to 3 mm thick. Therefore, the magnetic flux generated by the magnetic circuit between the fixed core 42 and the armature 60 never leaks to the fixed member 90 . Although the fixture body 91 is made of a magnetic material with a high yield point, the electromagnetic attraction between the stationary core 42 and the armature 60 does not decrease, so the responsiveness of the armature 60 to the current supplied into the coil 43 very high.

As mentioned above, the fixing member body 91 is connected to the valve body 30 by a strong fastening force without plastic deformation, so that the first and second plates 81 and 82 are firmly press-fitted against the fixing member 90 . In this way, the fluid-tight seal between the valve body 30 and the first and second plates 81 and 82 can be highly ensured, so even if the fuel pressure is very high, for example, greater than 180 MPa, between the first plate 81 and the valve body 30 and the first Fuel leakage between the plate 81 and the second plate 82 can also be suppressed.

In the case where the fixing member 90 is not constituted by the fixing member body 91 and the non-magnetic member 92, the fixing member 90 made of a non-magnetic material and having a relatively high yield point may be used. This fixing 90 has the same advantages as described in the second embodiment.

In addition, the application of the solenoid valve 40 is not limited to the above-described common rail fuel injection device, but can also be applied to other fuel injection devices such as gasoline fuel injection devices, and can also be applied to devices and systems for any purpose.

Although the surface area of the armature 60 on the side of the fixed magnetic core 42 is 150 mm ² in the previously described embodiment, the size of the area is not limited to this value.

Claims (12)

1. solenoid valve, it is installed on the valve base piece (82), and valve base piece has the opening (821 and 822) and the valve seat around opening (82a) that are used to flow through fluid, and this solenoid valve has:

A valve member (50), it is used to rest on the valve seat or lifts off a seat, thereby opening is opened or closed;

A moving part (60), it moves axially with valve member;

A fixed magnetic core (42), it surrounds a coil (43), and when coil was recharged, the magnetic force that moving part is produced was inhaled to fixed magnetic core; And

A fixed block (70,90), its end face is mutually opposed with the end face that is positioned at the fixed magnetic core opposition side on the moving part, and another end face is characterized in that towards valve base piece:

When valve member is closed opening, distance D between the end face opposite each other on moving part and the fixed block is positioned at a prespecified range with lower limit and upper limit, thereby lower limit is set to such distance, promptly be recharged and moving part is prepared after beginning opens direction along opening and move at coil, the motion actuated time of moving part can be owing to the adhesive force that is superimposed upon the fluid between moving part and the fixed block is delayed, and the upper limit is set to such distance, promptly after coil blackout and just finish before the moving of opening closing direction at moving part, moving part can receive a reaction force of the sensing fixed magnetic core of increase suddenly from the fluid that is superimposed upon between moving part and the fixed block

The following 5 μ m that are limited to of described distance D are limited to 60 μ m on the distance D.

2. solenoid valve according to claim 1 is characterized in that, at least one position integral body of moving part and valve member forms as one.

3. solenoid valve according to claim 1 and 2 is characterized in that, valve member is made up of a contact member (52) and a shaft element (51), and contact member is used to rest on valve seat, and an end of shaft element is keeping contact member, and the other end combines with moving part.

4. solenoid valve according to claim 1 and 2 is characterized in that, fixed block is made up of the first and second different fixed blocks of axial length.

5. solenoid valve according to claim 1 and 2 is characterized in that, fixed block is made by a kind of material with given yield point value, and this yield point reaches such degree, and promptly when the fixed block brute force was pushed valve base piece, fixed block can plastic deformation.

6. solenoid valve according to claim 5 is characterized in that, fixed block has a non magnetic element of being made by nonmagnetic substance.

7. solenoid valve according to claim 6 is characterized in that, the end place that be positioned at fixed magnetic core one side of non magnetic planning on fixed block.

8. solenoid valve according to claim 5 is characterized in that self is made fixed block by nonmagnetic substance.

9. solenoid valve according to claim 1 and 2 is characterized in that, moving part is provided with otch (61) on its excircle, and each otch has certain depth respectively and extends vertically.

10. solenoid valve according to claim 1 and 2, it is characterized in that, moving part is being provided with through hole (62) its one between inboard pole surface (42a) and the outside pole surface (42b) on the position of fixed magnetic core, the break-through vertically respectively of each through hole.

11. solenoid valve according to claim 10 is characterized in that, the area ratio of inboard pole surface and outside pole surface is positioned at 1 to 2 scope.

12. a fuel injection system, it has solenoid valve according to claim 1 and 2.

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