JPH0749777B2 - Solenoid valve for fluid control - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a fluid control solenoid valve, and more particularly, in a fuel injection control device for a diesel engine, a passage for high pressure fuel pressurized by a fuel injection pump is arbitrarily set. The present invention relates to a fluid control solenoid valve suitable for controlling the fuel injection amount or the fuel injection timing by opening and closing at the timing.

"Prior Art" A method in which high-pressure fuel is directly overflowed by a solenoid valve and the fuel injection timing or injection amount is controlled is disclosed in US Pat.
As shown in No. 253, it is obvious that it has already been disclosed in the unit injector, and can also be implemented in the fuel injection device having the injection pump and the nozzle.

The above method is to provide a solenoid valve in a passage communicating between the high pressure chamber and the low pressure side of the pump, and to open the solenoid valve at a predetermined timing during the pump operation cycle to overflow the high pressure fuel to control the fuel injection amount. Compared with a conventional mechanical governor that positions a rack or sleeve to control the fuel injection amount, the mechanism is significantly simpler and suitable for electronic control.

The problem with the above high pressure direct overflow system is that it can withstand a pump chamber pressure of a diesel injection pump of up to 150Mpa and keeps the valve closed, and it operates with a response of up to 200Hz depending on the engine speed. Is how to realize a high solenoid valve.

Currently, as this type of solenoid valve, a pressure balance type valve as shown in FIG. 9 is put into practical use. In this valve, a needle valve body 8 having a substantially cylindrical shape slides up and down in the body 4 by an electromagnetic force and a spring force to open and close the high pressure fluid passage 18 and the low pressure side. When closing the valve, the needle valve body 8 moves upward, and the tapered seat portion 16 formed on the needle valve body 8 is replaced by the edge formed on the body 4.
Abut 20. In this case, the area of the seat portion 16 on the inner peripheral side of the edge 20 is made equal to the area of the tapered surface 15 above the needle valve body 8 and acts on the needle valve body 8 when the valve is closed. It is configured such that the axial component of the high pressure fluid pressure is balanced and canceled.

[Problems to be Solved by the Invention] However, the balance valve described above has a problem that the valve opening response deteriorates as the pressure of the high-pressure fluid increases, as shown in FIG. It was found that this was because the dynamic pressure balance was lost. That is, when the high pressure fluid flows out to the low pressure side when the valve is opened, the high pressure fluid is jetted obliquely downward along the seat portion 16 of the needle valve body 8 as shown by the arrow in FIG. Therefore, the reaction of the jetted high-pressure fluid acts on the upper tapered surface 15 of the needle valve body 8 and pushes up the needle valve body 8 in the closing direction. Due to the reaction of this jetted high-pressure fluid, the valve opening under high pressure became slower than in the stationary fluid.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a solenoid valve for fluid control capable of enhancing valve opening response under high pressure.

[Means for Solving the Problems] Therefore, in the present invention, in a pressure balance type fluid control solenoid valve having a tapered seat portion in the valve body, the high pressure fluid flowing out from the seat portion when the valve is opened is used as the valve. Provided is a solenoid valve for fluid control, characterized in that the valve body is provided with a rectifying portion for flowing out in a direction perpendicular to a moving direction of a body or a direction close to the vertical direction.

[Operation] According to the above configuration, the high-pressure fluid ejected along the seat portion when the valve is opened is changed in direction by the rectifying portion and ejected in the direction perpendicular to or nearly perpendicular to the moving direction of the valve body. The reaction of the jetted high-pressure fluid has almost no effect in the moving direction of the valve element and cancels each other. Therefore, the dynamic pressure balance that acts on the valve body is maintained even when the valve is opened, and excellent responsiveness can be maintained even under high pressure.

[Examples] Examples of the present invention will be specifically described with reference to the drawings.

FIG. 2 is a sectional view of the fluid control solenoid valve 1 according to the present invention, and FIG. 1 is a sectional view showing only the valve portion.

A solenoid 3 and a body 4 are fixed in a cylindrical housing 2, and the solenoid 3 includes a coil 6 connected to an electric wire 5.

A needle valve element 8 having a substantially axial shape is provided in the hole 7 at the center of the body.
Is vertically slidably inserted. A disk-shaped armature 9 is fixed to the upper end of the needle valve 8, and when the coil 6 is energized, it is drawn upward by the solenoid 3. Also, a compression spring is provided in the hole 10 in the center of the solenoid 3.
An armature 11 is supported by a screw 12 to urge the armature 9 and the needle valve body 8 downward.

A part of the side peripheral surface of the needle valve body 8 is shaved below, and an upper tapered surface 15 and a lower tapered seat portion 16 are formed. The lower end of the seat portion 16 horizontally extends in the radial direction to form a rectifying portion 17.

Further, a high-pressure fluid passage 18 and a valve chamber 19 are formed in the body 4, and the lower end of the valve chamber 19 has a seat portion 16 of the needle valve body 8.
It forms an edge 20 that abuts against. The inside diameter of the edge 20 is formed to be equal to the outside diameter of the cylindrical portion above the needle valve body 8.

The operation of this embodiment will be described. When the coil 6 is not energized, the compression spring 11 moves the needle valve body 8 downward, the seat portion 16 is separated from the edge 20, and the valve is opened. On the other hand, when the coil 6 is energized, the armature 9 is attracted upward against the biasing force of the compression spring 11, and the seat portion 16 of the needle valve body 8 contacts the edge 20 of the body 4 to close the valve. It will be in the state of being. At this time, since the inner diameter of the edge 20 is equal to the outer diameter of the cylindrical portion above the needle valve body 8, the pressure of the high-pressure fluid acting on the upper tapered surface 15 of the needle valve body 8 and the lower seat portion 16 becomes equal,
The axial component of the high pressure fluid pressure acting on the needle valve body 8 is canceled. Therefore, it is possible to withstand the pressure of the high-pressure fluid and maintain the valve closed.

Next, when the coil 6 is de-energized, the needle valve body 8 is moved downward by the urging force of the compression spring 11, and the valve is opened. The high-pressure fluid flowing out of the valve chamber 19 when the valve is opened flows out along the seat portion 16 of the needle valve body 8 and is redirected by the rectifying portion 17 extending in the radial direction.
It jets horizontally as shown by the arrow in the figure. The high-pressure fluid that radiates horizontally has no downward velocity component,
The reactions cancel each other out and the needle valve body 8
Does not exert any force in the vertical direction. Therefore, the valve can be quickly opened by the urging force of the compression spring 11 without being affected by the dynamic acting force of the high-pressure fluid.

Although the balance valve in which the pressure is completely balanced is used and the flat plate-shaped rectifying unit 17 is used in the above-described embodiment, various modifications can be considered. FIG. 3 shows that a slight difference is provided between the outer diameter of the cylindrical portion above the needle valve body 8 and the diameter of the edge 20 so that the valve chamber is closed when the valve is closed.
It is a pressure assist type valve in which a slight force acts in the axial direction of the needle valve body 8 by the pressure inside 19. Even in such a valve, the rectifying unit 17 can be provided to cancel the reaction of the high-pressure fluid that is ejected and speed up the operation when the valve is closed.

In the embodiment shown in FIG. 4, the rectifying portion 25 is not a horizontal plane but a tapered surface having an angle with respect to the horizontal.
Even with such a rectifying section 25, if the angle is gentler than the angle of the seat section 16, the direction of the high-pressure fluid to be ejected is brought closer to the horizontal direction, and the axial component of the reaction acting on the needle valve body 8 is reduced. You can Further, it is also possible to reduce the fluid resistance by making the surface of the rectifying portion 25 not a taper surface but a curved surface whose slope gradually decreases from the seat portion 16.

Further, the seat portion and the rectifying portion do not necessarily have to be continuous. FIG. 5 shows an example thereof, in which a step portion 26 is provided and the seat portion 16 and the rectifying portion 27 are separated from each other. With such a structure, there is an advantage that the sheet portion 16 can be precisely processed without being obstructed by the rectifying portion 27.

FIG. 6 shows the solenoid valve 1 shown in FIG.
FIG. 11 is a cross-sectional view showing an example applied to 30. Here, the high pressure chamber 31 of the unit injector 30 is connected to the high pressure fluid passage 18 of the solenoid valve 1.
The high pressure chamber 31 and the low pressure spill port 32 are opened and closed. The fuel sucked into the high-pressure chamber 31 from the suction port 33 is pressurized by the plunger 34 driven by a cam (not shown). In the initial stage of the pressure feeding stroke of the plunger 34, the solenoid valve 1 is de-energized and the solenoid valve 1 is opened. Therefore, the fuel in the high pressure chamber 31 escapes from the solenoid valve 1 to the spill port 32, and fuel injection is not performed. The solenoid valve 1 is energized at the timing of an appropriate crank angle (advance position), the solenoid valve 1 is closed, and the pressure in the high pressure chamber 31 rises. The pressure pushes up the nozzle 36 urged by the compression spring 35, and fuel injection into the cylinder starts. In this way, the fuel injection timing is controlled by controlling the timing of closing the solenoid valve 1.

Next, before the plunger 34 reaches the top dead center, the solenoid valve 1 is de-energized at an appropriate time, and the solenoid valve is opened, so that the high pressure fuel in the high pressure chamber 31 overflows into the spill port 32 and the nozzle 36
Closes and fuel injection ends. In this way, the fuel injection amount is controlled by controlling the timing of opening the solenoid valve 1.

FIG. 7 is a sectional view showing an example of application to the distribution type fuel injection pump 40. Here, from the pressure pump chamber 41 to the distribution port 42
The high-pressure passage 43 up to is communicated with the solenoid valve 1, and the high-pressure passage 43 and the low-pressure pump chamber 44 are opened and closed. This injection pump 40
Is an inner cam type distribution type fuel injection pump, and an inner cam 46 is provided in a housing 45. A cam surface 47 is formed on the inner peripheral surface of the inner cam 46. In this embodiment, the cam surface 47 has the same shape at 90 ° intervals corresponding to a four-cylinder engine. A drive shaft 48 is rotatably supported in the housing 45 by a bearing 49 and an inner circumference of the bush 50, and is rotationally driven at a rotation speed of 1/2 of the engine. A plunger passage 51 is provided in the central portion of the drive shaft 48 in the radial direction, and two plungers 52 are slidably fitted therein. The tip of each plunger 52 contacts the roller shoe 53, and the roller 54 supported by the roller shoe 53 contacts the cam surface 47 of the inner cam 46.
The space at the center of the drive shaft sandwiched between the two plungers 52 forms the pressure pump chamber 41. A high-pressure passage 43 is formed inside the drive shaft in the central axis direction, and a suction port 55 and a distribution port 42 provided in the bush 50 according to the rotational position of the drive shaft 48.
And the solenoid valve port 56.

The fuel pre-pressurized by the vane pump 57 that is rotationally driven by the drive shaft 48 is sent to the low pressure pump chamber 44, and is sucked into the pressure pump chamber 41 via the suction port 55. The high-pressure fuel, which has been made high in the pressure-feeding process of the plunger 52, is sent from the distribution port 42 to the delivery valve 58 and is injected from the injection nozzle of each cylinder. The injection start timing is controlled by rotating the inner cam 46 by the timer piston 59 driven by the fuel pressure in the low pressure pump chamber 44 and shifting the timing at which the plunger 52 starts the pressure feeding.

On the other hand, the control of the fuel injection amount is performed by controlling the valve opening timing of the solenoid valve 1. That is, the electronic control unit
At 61, an appropriate injection amount is calculated based on the signal from the load sensor 62, and in order to realize the injection amount, the solenoid valve 1 is turned off at an appropriate timing based on the signal from the reference angle sensor 63 or the like. The plunger 52 causes the high-pressure fuel that is being pumped to overflow into the low-pressure pump chamber 44 to end the fuel injection and control the injection amount.

In this way, in any application example, the overflow adjustment amount is performed by the solenoid valve. Therefore, the valve opening response of the solenoid valve has a great influence on the disconnection of fuel injection.

FIG. 8 is a characteristic diagram showing a result of measuring the valve opening response of the solenoid valve in the inner cam type distribution type injection pump.

In the conventional solenoid valve in which the needle valve body 8 does not have the rectifying section 17, as the engine speed increases and the oil transfer rate becomes red, as indicated by the mark X in the figure, in other words, the fuel when the valve is opened It can be seen that the valve opening response deteriorates as the pressure increases. On the other hand, in the solenoid valve 1 of the present invention in which the needle valve pair 8 is provided with the rectifying portion 17, the flat characteristic is exhibited regardless of the oil feeding rate and the valve opening response is It shows a remarkable effect that it is not affected by the oil transfer rate. For this reason, the valve opening response time has been improved to less than half that of the conventional one, especially at high oil transfer rates.

[Advantages of the Invention] As described above, the present invention has the above-described configuration and includes the rectifying portion in the valve body. Therefore, the ejection direction of the high-pressure fluid flowing out from the tapered seat portion is changed and ejected. There is an excellent effect that the force exerted on the valve body by the high-pressure fluid can be reduced and the responsiveness at the time of valve opening can be improved.

[Brief description of drawings]

1 to 8 show an embodiment of the present invention, FIG. 1 is a sectional view showing a valve portion, FIG. 2 is a sectional view of an electromagnetic valve, and FIGS. 3 to 5 are other embodiments. 6 and 7 are sectional views showing an application example to a fuel injection pump, FIG. 8 is a characteristic view, and FIG. 9 is a sectional view showing a valve portion of a conventional solenoid valve. . 1 ... solenoid valve, 6 ... coil, 8 ... needle valve body, 16
...... Seat section, 17,25,27 …… Rectification section, 20 …… Edge, 31
...... High pressure chamber, 34 ...... Plunger, 41 ...... Pressure pump chamber,
52 ... Plunger.

Claims (1)

[Claims] 1. A pressure balancing type fluid control solenoid valve having a tapered seat portion on a valve body, wherein a high pressure fluid flowing out from the seat portion when the valve is opened is directed in a direction perpendicular to a moving direction of the valve body or perpendicularly thereto. A fluid control solenoid valve, wherein the valve body is provided with a rectifying portion that causes the rectifier to flow out in a near direction.