JPH0670418B2 - Filter for electromagnetic spill valve - Google Patents

Description

TECHNICAL FIELD The present invention relates to a filter suitable for an electromagnetic spill (leakage) valve applied to a fuel injection amount control system of a diesel engine.

[Prior Art] An electromagnetic spill valve has a variable volume liquid chamber that is in constant communication with a pressurizing chamber of a high-pressure pump that pressure-feeds fuel to a fuel injection nozzle, and inflow and outflow of fuel into and out of the liquid chamber. An electromagnetic spill valve in which a port and an outflow port communicate with each other is known. (For example, JP-A-58-187537).

[Problems to be Solved by the Invention] However, such an electromagnetic spill valve originally responds to a control signal from an external or electronic control circuit at high speed.
It is designed with the problem of being sufficiently small, and also has the above-mentioned liquid chamber, that is, a liquid chamber in which fuel may flow in and out but does not flow through and easily accumulate. Therefore, foreign matter is likely to enter and accumulate in the liquid chamber, and the free moving body that is always exposed in the liquid chamber and the cylinder member in which the free moving body is slidably inserted is minute. It is highly conceivable that foreign matter may enter the large gap to hinder the smooth operation of the free moving body, and as a result, the opening / closing operation of the fuel injection nozzle may not be performed at a desired timing.

In view of the above points, the present invention reduces the amount of foreign matter entering the liquid chamber by installing a gasket / filter near the inflow port, ensures a smooth operation of the free moving body, and improves the fuel injection nozzle. It is an object of the present invention to enable the open / close operation to be continued at a desired timing.
Further, since the fuel pressure near the inflow port is a high pressure of about 400 kg / cm ^2, it is another object of the present invention to provide a filter that can sufficiently withstand the high pressure.

[Means for Solving the Problems] Therefore, the present invention has a variable volume liquid chamber that is always in communication with a pressurizing chamber of a high-pressure pump that pressure-feeds the fuel to the fuel injection nozzle. It is a filter used for an electromagnetic spill valve in which an inflow port and an outflow port are communicated with each other according to the inflow of a plurality of sheets. It is characterized by having a wire net.

[Operation] The filter removes the foreign matter from the fuel when the fuel containing the foreign matter passes through the inflow port and reaches the filter position. Therefore, since the amount of foreign matter contained in the fuel flowing into and out of the liquid chamber is small, the smooth operation of the free moving body is ensured for a long period of time, and the fuel injection nozzle is opened and closed at a desired timing during that time. . Further, since it has a plurality of wire nets, it can sufficiently withstand high pressure.

[Embodiment] FIG. 1 is a sectional view of a filter according to a first embodiment of the present invention,
2 and 3 show a plan view and a rear view of the filter, respectively.

In FIGS. 1 to 3, 1a is a casing made of metal such as stainless steel, 1b is a porous plate made of the same metal, 1c is a wire mesh laminate, and 1d is a metal holding plate. Wire mesh laminates 1c consists of three layers wire mesh, so that it can withstand the passage of high-pressure fuel of about 400 kg / cm ^2, the finest eye wire mesh for filtration toward the flow of fuel, little to reinforce this It consists of a coarse mesh and the coarsest mesh for reinforcement. The holding plate 1d is press-fitted into the casing 1a, and the perforated plate 1b and the wire mesh laminate 1c are housed in the casing 1a.

FIG. 4 shows a cross-sectional structure of the electromagnetic spill valve and the filter 1 incorporated in the fuel injection amount control system of the diesel engine.

In FIG. 4, 3 is a housing of the high-pressure pump, and 5 is an inflow port formed in the housing 3. The inflow port 5 communicates with a pressure chamber (not shown). Reference numeral 7 denotes an outflow port formed in the housing 3.

Reference numeral 9 represents an electromagnetic spill valve attached to the housing 3.

In the electromagnetic spill valve 9, 11 is a coil which is energized in accordance with a control signal from an electronic control circuit (not shown), and 13 is a coil 11
Is a moving core that receives a magnetic attraction force downward in the drawing when energized, 15 is a spring that constantly applies a pressing force to the moving 13 in the downward direction in the drawing, 17 is a rod-shaped body fixed and extended to the moving core 13, 19 Is a through hole that allows the rod-shaped body 17 to move without abutting the rod-shaped body 17, 21 is a wall body in which the through-hole 19 is formed, 23 is the through-hole 19 of the wall body 21 opposite to the moving core 13. Side, that is, the lid body that opens and closes from the lower side in the drawing, and 25 is always in the upper direction in the drawing
Indicates a spring that applies a pressing force in the direction to close 19.

27 is a cylindrical free moving body, 29 is a first cylindrical fixing member into which the free moving body 27 is slidably inserted, 31 is a throttle hole formed at the front end 33 of the cylindrical fixing member 29, 35 Is a cylindrical valve body having an inner peripheral surface 39 facing the outer peripheral surface 37 of the cylindrical fixing member 29, 41 is an orifice formed at the front end 43 of the cylindrical valve body 35, and 45 is the cylindrical valve body 35. , 47 is a spring for constantly applying a pressing force downward in the drawing, and 47 is a second cylindrical fixing member into which the cylindrical valve element 35 is slidably inserted and has a function as a valve seat of the cylindrical valve element 35. , 49 are passages formed in the cylindrical fixing member 47, and 51 is another passage formed in the cylindrical fixing member 47.

Reference numeral 53 represents a liquid chamber referred to in the present invention which is formed by the front end surface 55 of the free moving body 27 and the inner peripheral surface 57 of the first cylindrical fixing member 29 including the throttle hole 31. As will be described later, the liquid chamber 53 has its volume increased by the movement of the free moving body 27 in the upward direction in the drawing,
Fuel flows into the room through the throttle hole 31.

Reference numeral 59 is an end surface including the rear end surface 61 of the free moving body 27, the inner peripheral surface 57 of the first cylindrical fixing member 29, and the through hole 19 of the wall body 21.
61 is another liquid formed by the liquid and the liquid 59 is a lid.
When 23 is in close contact with the wall 21, it is in a sealed state, and when separated, it is in a state of communication with the low-pressure fuel side.

In the filter 1, as shown in FIG. 4, the holding plate 1d side is opposed to the inflow port 5 side, and the casing 1a is provided on the stepped portion 63 formed in the housing 3 with the second spill of the electromagnetic spill valve 9. It is fixed by being pressed by the front end of the cylindrical fixing member 47.

Next, an outline of the operation example will be described.

When the high-pressure pump starts the pressurizing operation, the coil 11 is kept in the non-energized state, the lid 23 is kept in close contact with the wall 21, and the liquid chamber 59 is kept in a sealed state. As the pressurizing operation progresses, the fuel pressure in the pressurizing chamber rises, and accordingly, the inflow port 5, the filter 1, the passage 49 of the second cylindrical fixing member 47,
Although the fuel pressure applied to the front end surface 55 of the free moving body 27 via the orifice 41 of the cylindrical valve body 35 increases, the free moving body 27
The cylindrical valve body 35 is prevented from separating from the valve seat by keeping the liquid chamber 59 as a back pressure chamber in the above-mentioned sealed state.

During this pressurizing operation, an electric current is applied to the coil 11 to
The lid 23 is separated from the wall 21 by 17. As a result, the liquid chamber 59 communicates with the low-pressure fuel side, the back pressure applied to the free moving body 27 is rapidly reduced, and the free moving body 27 rapidly moves upward in the drawing. The rapid movement of the free moving body 27 generates a large negative pressure in the liquid chamber 53, and sucks the fuel on the positive pressure side at a high flow rate through the throttle hole 31, and the fuel accompanying the suction of the fuel into the liquid chamber 53 The back pressure applied to the inner peripheral surface 39 of the cylindrical valve body 35 by the flow is made a large negative pressure, and the cylindrical valve body 35 is moved upward in the drawing. Due to the movement of the cylindrical valve body 35, that is, the separation from the valve seat, the high-pressure fuel in the pressurizing chamber flows to the outflow port 7 through the inflow port 5, the filter 1, the orifice 41 and the passages 49 and 51, and a fuel injection nozzle (not shown). Ends the fuel injection by. At this time, the fuel pressure applied to the filter 1 has reached a high pressure of about 400 kg / cm ² , whereas the filter 1 is made up of a three-layer wire mesh laminate 1c and a perforated plate 1b for reinforcing it. Therefore, the fuel pressure can be satisfactorily filtered without being deformed by the fuel pressure.

As described above, according to the filter 1 of this embodiment, the stepped portion 63 of the housing 3 that surrounds the inflow port 5 that connects the filter 1 to the pressurizing chamber of the high-pressure pump at the front end of the electromagnetic spill valve 9 is provided.
Since it can be used as a gasket because it is pressed and fixed to the back, multiple fine meshes for filtration are reinforced by the multiple meshes behind it and the perforated plate 1b, so it can withstand the passage of fuel with a pressure of about 400 kg / cm ^2. As a result, foreign substances mixed in the fuel can be removed.

Here, in the first embodiment, the perforated plate 1b and the wire mesh laminated body 1c are fitted into the casing 1a, and then the pressing plate 1d is press-fitted. Therefore, it is desired to improve the dimensional accuracy of the pressing plate 1d. . However, if the perforated plate and the wire mesh of the wire mesh laminate can be housed in the casing so that they overlap with each other, there is no problem even if the filter does not have a holding plate. Therefore, a filter thus constructed will be described as a second embodiment of the present invention.

That is, as shown in FIG. 5, in this embodiment, unlike the first embodiment, two perforated plates are used instead of the holding plate. That is, the wire mesh laminate 2c in the same order as in the first embodiment.
Are sandwiched between the same perforated plates 2b, and the portions indicated by arrows in the figure are spot-welded and fixed. Then, the wire mesh laminate 2c sandwiched between the two perforated plates 2b is superposed and fixed in the casing 2a.

Thus, according to this embodiment, the wire mesh laminate 2c is replaced with the porous plate 2b.
By sandwiching and spot welding, the perforated plate 2b and the wire nets of the wire net laminate 2c are overlapped with each other without using a holding plate, so that the same effect as the first embodiment can be obtained. Further, the perforated plates 2b sandwiching the wire mesh laminated body 2c may be the same ones and mass production is possible, so that the manufacturing cost can be facilitated.

[Effects of the Invention] As described above, the filter of the present invention is a filter that also serves as a gasket in the middle of the fuel passage from the inflow port to the liquid chamber of the electromagnetic spill valve, and has a plurality of wire meshes. It will be. Therefore, it is possible to sufficiently withstand high pressure, and foreign matter in the fuel is removed by the filter and flows into the liquid chamber, which avoids undesired operation of the movable body due to foreign matter invading and accumulating in the liquid chamber. can do.

[Brief description of drawings]

1 to 3 show a filter according to a first embodiment of the present invention, FIG. 1 is a sectional view, FIG. 2 is a plan view, and FIG. 3 is a rear view. FIG. 4 is a sectional view of a main part of a fuel injection amount control system of a diesel engine in which the filter is incorporated with an electromagnetic spill valve, and FIG. 5 is a sectional view showing a filter of a second embodiment of the present invention. 1 ... Filter, 1c ... Wire mesh laminate 3 ... Housing, 5 ... Inflow port 7 ... Outflow port, 9 ... Electromagnetic spill valve 11 ... Coil, 13 ... Moving core 15 ... Spring, 17 ... … Rod-like body 19 …… Through hole, 21 …… Wall body 23 …… Lid body, 25 …… Spring 27 …… Free moving body 29 …… First cylindrical fixing member 31 …… Throttle hole, 35 …… Cylinder Valve body 41 …… Orifice, 45 …… Spring 47 …… Second cylindrical fixing member 49 …… Passage, 51 …… Passage 53 …… Liquid chamber, 59 …… Liquid chamber 63 …… Stepped portion

Claims (1)

[Claims] 1. A liquid chamber having a variable volume, which always communicates with a pressurizing chamber of a high-pressure pump for feeding fuel to a fuel injection nozzle, and an inflow port and an outflow port communicate with each other according to the inflow of fuel into the liquid chamber. A filter used for an electromagnetic spill valve, characterized in that it is installed as a gasket in the middle of the fuel passage from the inflow port to the liquid chamber and has a plurality of wire meshes. Filter for spill valve.