Automatic drainage device for filter negative pressure system

Abstract

The present invention discloses an automatic drainage device for a filter negative pressure system, comprising an upper valve body, a cylindrical shell and a lower valve body, wherein the upper valve body, the cylindrical shell and the lower valve body form a valve cavity; a coil, a central tube and a double-control valve core are arranged in the valve cavity, an air inlet hole communicating with the environment and an air outlet hole communicating with the filter water collecting cup upward are arranged in the upper valve body; a water discharge inlet hole communicating with the filter water collecting cup upward is arranged in the upper valve body, and a water discharge outlet hole communicating with the environment downward is arranged in the lower valve body; when the coil is energized, the air path and the water path are simultaneously connected at the double-control valve core; when the coil is de-energized, the air path and the water path are simultaneously blocked at the double-control valve core. The present invention has a dual channel of air path and water path, solves the problem of being unable to drain water under negative pressure conditions, and is small in size and easy to install, has universal properties, can be widely promoted and used in fuel filters used in negative pressure systems, solves the problem of difficult and untimely disassembly and assembly of manual drainage, and the problem of oil pollution of personnel's clothes caused by manual drainage.

Description

Technical Field

[0001] The invention relates to the technical field of diesel engine fuel filter systems. Background Art

[0002] During the National VI emission regulations stage, diesel engines have increasingly higher requirements for the efficiency of water separation in fuel. After the fuel is filtered and separated by the diesel filter, the separated water is deposited in the water collecting cup at the lower end of the filter. As time goes on, when the accumulated amount of water in the water collecting cup reaches the set limit, if the water in the water collecting cup is not discharged in time, the water will enter the filter element and occupy the volume space of the fuel, which will affect the filter's filtration of the fuel and affect the separation of oil and water. In severe cases, it will affect the filter's oil flow rate, resulting in insufficient fuel supply to the engine or even engine stalling.

[0003] To solve the above problem, the water in the water collection cup needs to be drained in time. The most common method is to install a screw plug at the bottom of the filter water collection cup, and manually open the screw plug regularly to drain the water; when the water level in the water collection cup reaches or exceeds the drain level set by the on-board ECU, the driver needs to drain the water at any time after receiving the on-board ECU alarm, but because the fuel filter is in a negative pressure state when working, even if the water is drained, the water cannot be discharged smoothly at this time (similar to blocking the air intake pipe on the infusion bottle, unless the infusion bottle is flattened by atmospheric pressure, normal infusion cannot be performed).

[0004] Manual drainage requires a high level of subjective enthusiasm from the operator and requires a large margin of space for the filter installation position, which is difficult to achieve in vehicles with compact engine layouts. In addition, manual drainage will cause the operator to be covered in oil. Therefore, the manual drainage solution has great disadvantages. Summary of the invention

[0005] The object of the present invention is to provide an automatic drainage device for a filter negative pressure system, which solves the problem that the fuel filter cannot drain water under negative pressure state, and has a small size and is easy to install.

[0006] To achieve the above object, the automatic drainage device for the filter negative pressure system of the present invention comprises an upper valve body, a cylindrical shell and a lower valve body connected in sequence from top to bottom, the lower valve body and the cylindrical shell are screwed or welded, and the upper valve body, the cylindrical shell and the lower valve body form a valve cavity;

[0007] A vertically arranged center tube is provided in the valve cavity, a horizontal upper end cover is radially extended from the upper end of the center tube, a horizontal lower end cover is radially extended from the lower end of the center tube, the upper end cover is sealed with the top of the inner wall of the cylindrical shell, and the lower end cover is sealed with the bottom of the inner wall of the cylindrical shell;

[0008] The upper valve body is provided with an air inlet hole communicating with the environment and an air outlet hole communicating upward with the filter water collecting cup;

[0009] The upper valve body is provided with a drain inlet hole communicating upward with the filter water collecting cup, and the lower valve body is provided with a drain outlet hole communicating downward with the environment;

[0010] The center tube, the upper end cover, the lower end cover and the inner wall of the cylindrical shell form an annular cavity, and a coil is arranged in the annular cavity. The coil is used to connect with the vehicle-mounted ECU through the vehicle-mounted circuit;

[0011] A double-control valve core is arranged in the central tube, the air inlet hole and the air outlet hole form an air path passing through the double-control valve core, and the water discharge inlet hole and the water discharge outlet hole form a water path passing through the double-control valve core;

[0012] When the coil is energized, the gas circuit and the water circuit are connected at the dual-control valve core at the same time; when the coil is de-energized, the gas circuit and the water circuit are blocked at the dual-control valve core at the same time.

[0013] An upper sealing groove is provided on the circumferential surface of the upper end cover, an annular upper sealing ring is provided in the upper sealing groove, and the upper sealing ring is pressed against the inner wall of the cylindrical shell;

[0014] The lower surface of the lower end cover is convex downwardly and is provided with a bottom groove, in which a lower sealing ring is arranged, and the lower sealing ring is pressed against a convex ring on the top surface of the lower valve body which convexly protrudes upward into the bottom groove.

[0015] The double-control valve core includes a fixed iron core embedded in the middle of the central tube in the vertical direction, an upper moving iron core is arranged in the central tube above the fixed iron core, and a lower moving iron core is arranged in the central tube below the fixed iron core;

[0016] The winding direction of the portion of the coil located above the fixed iron core is opposite to the winding direction of the portion of the coil located below the fixed iron core;

[0017] The top surface of the upper end cover is provided with a groove opening upward, and the groove and the upper valve body above it form a water-passing and air-passing cavity; the water-passing and air-passing cavity is respectively connected with the air inlet hole and the air outlet hole;

[0018] The interface through which the air inlet hole is downwardly connected to the water ventilation cavity is located directly above the upper moving iron core, and this interface is called the upper interface;

[0019] The top of the upper moving iron core is connected to an upper sphere, and the upper moving iron core protrudes upward from the middle and upper part of the upper sphere; an upper step hole is provided in the center of the lower part of the upper moving iron core, and an upper reset spring is pressed between the upper step hole and the fixed iron core; when the coil loses power, the upper reset spring presses the upper sphere against the upper interface through the upper moving iron core and closes the upper interface, and in this state, the air inlet hole is isolated from the air outlet hole;

[0020] When the coil is energized, the upper moving iron core compresses the upper return spring downward so that the upper sphere moves downward away from the upper interface. In this state, the air inlet hole is connected to the air outlet hole through the water ventilation cavity;

[0021] A water hole which is transparent from top to bottom is provided at the center of the fixed iron core. A circular boss is provided at the middle of the upper and lower parts of the water hole, which protrudes radially inward. The top surface of the circular boss is upwardly pressed and matched with the upper return spring.

[0022] The upper moving iron core above the upper step hole is respectively recessed with upper water-passing steps on two opposite sides, and the upper water-passing steps and the central tube form an upper water-passing cavity; an upper water-passing hole connecting the upper water-passing cavity and the upper step hole is opened in the upper moving iron core at the bottom of the upper water-passing step;

[0023] The part of the bottom groove located in the convex ring and the lower valve body below it form a water passage cavity; the interface of the water discharge hole connected with the water passage cavity upward is located directly below the lower moving iron core, and this interface is called the lower interface;

[0024] The bottom end of the lower moving iron core is connected to a lower sphere, and the lower moving iron core protrudes downward from the middle and lower part of the lower sphere; a lower step hole is provided in the center of the upper part of the lower moving iron core, and a lower return spring is pressed between the lower step hole and the fixed iron core;

[0025] The bottom surface of the annular boss is pressed downward to fit with the lower return spring;

[0026] The upper moving iron core below the lower step hole is provided with lower water-passing steps on two opposite sides thereof, and the lower water-passing steps and the central tube form a lower water-passing cavity; the lower moving iron core at the top of the lower water-passing step is provided with a lower water-passing hole connecting the lower water-passing cavity and the lower step hole;

[0027] When the coil loses power, the lower return spring presses the lower ball onto the lower interface through the lower moving iron core and closes the lower interface. In this state, the water inlet hole is isolated from the water outlet hole.

[0028] When the coil is energized, the lower moving iron core compresses the lower return spring upward to make the lower sphere move upward away from the lower interface. In this state, the water inlet hole and the water outlet hole are connected through the upper water cavity, the upper water through hole, the upper step hole, the water through hole, the lower step hole, the lower water through hole and the lower water cavity.

[0029] There are more than two air inlet holes and more than two water inlet holes.

[0030] A horizontal connecting seat is integrally provided on the upper valve body, and the connecting seat is used to connect with the filter, and a connecting hole is provided on the connecting seat;

[0031] The upper valve body above the connecting seat is an inserting part for inserting into a corresponding mounting hole on the filter, and an annular mounting sealing groove is provided on the circumferential surface of the inserting part, and a mounting sealing ring is provided in the mounting sealing groove.

[0032] The present invention has the following advantages:

[0033] The present invention provides an automatic drainage device for a filter negative pressure system, which has dual channels of air and water, and solves the problem that water cannot be drained under negative pressure conditions (the fuel filter is in a negative pressure state when working normally) (in the past, water was drained when the engine was turned off and the negative pressure state was released); the device adopts a dual-control valve core, which is small in size and easy to install, and the device is a universal part and can be widely promoted and used in fuel filters used in negative pressure systems; it is particularly suitable for vehicles with compact engine arrangements to achieve automatic drainage, and solves the problems of difficult and untimely disassembly and assembly of manual drainage, as well as the problem of oil pollution on people's clothes caused by manual drainage.

[0034] When the filter is working normally, the water collecting cup is in a negative pressure state, and even if the drain valve is opened, the water cannot be drained normally. With the present invention, the air path and the water path can be conducted simultaneously by controlling the coil to be energized, thereby solving the problem that the water collecting cup cannot drain normally when the filter is working, and there is no need for personnel to manually unscrew the plug under the vehicle, which is very convenient to use.

[0035] The upper sealing ring and the lower sealing ring ensure that the coil is isolated from the water circuit and the gas circuit under any circumstances.

[0036] The specific structure of the double-control valve core is reliable, and it is convenient to connect the air and water circuits or shut off the air and water circuits at the same time by controlling the power-on and power-off states of the control coil. When the air and water circuits are connected at the same time, water can be discharged under negative pressure; when the air and water circuits are shut off at the same time, water discharge is stopped. The present invention can realize the simultaneous acceptance or blocking of the air circuit and the water circuit, and its specific structure also ensures the reliability and sealing of long-term use in a vibration environment (there will be vibration when the vehicle is driving).

[0037] The winding direction of the part of the coil 11 located above the fixed iron core is opposite to the winding direction of the part of the coil located below the fixed iron core, so that one coil can synchronously drive the upper moving iron core 16 and the lower moving iron core 17, ensuring that when the coil is energized, the air path and the water path are connected at the double-control valve core at the same time; when the coil is de-energized, the air path and the water path are blocked at the double-control valve core at the same time. There is no need to set up two coils to control the upper moving iron core 16 and the lower moving iron core 17 respectively, which not only improves the synchronization of the actions of the upper moving iron core 16 and the lower moving iron core 17, but also reduces the structural complexity, saves manufacturing costs, and helps to reduce the product volume. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a vertical cross-sectional structural schematic diagram of the present invention;

[0039] Figure 2 yes Figure 1 Although the enlarged view of point A;

[0040] Figure 3 It is a schematic diagram of a vertical cross-section structure of the present invention at another angle, used to express the gas path;

[0041] Figure 4 It is a schematic diagram of a vertical cross-section structure at a third angle of the present invention, used to express a waterway;

[0042] Figure 5 yes Figure 4 The enlarged view of point B in the middle;

[0043] Figure 6 It is a three-dimensional structural schematic diagram of the present invention;

[0044] Figure 7 It is a structural diagram of the double control valve core;

[0045] Figure 8 yes Figure 7 A top view of

[0046] Fig. 9 It is a three-dimensional structural diagram of the double-control valve core. DETAILED DESCRIPTION

[0047] like Figures 1 to 9 As shown, the automatic drainage device for the filter negative pressure system of the present invention comprises an upper valve body 1, a cylindrical shell 2 and a lower valve body 3 which are sequentially connected from top to bottom. The upper valve body 1 and the cylindrical shell 2 can be separately arranged and screwed or welded together, or can be arranged in one piece; the lower valve body 3 is screwed or welded to the cylindrical shell 2, and the upper valve body 1, the cylindrical shell 2 and the lower valve body 3 enclose a valve cavity;

[0048] A vertically arranged center tube 4 is provided in the valve cavity, a horizontal upper end cover 5 is radially extended from the upper end of the center tube 4, a horizontal lower end cover 6 is radially extended from the lower end of the center tube 4, the upper end cover 5 is sealed with the top of the inner wall of the cylindrical shell 2, and the lower end cover 6 is sealed with the bottom of the inner wall of the cylindrical shell 2;

[0049] The upper valve body 1 is provided with an air inlet 7 communicating with the environment and an air outlet 8 communicating upward with the filter water collecting cup;

[0050] The upper valve body 1 is provided with a drain inlet 9 communicating upward with the filter water collecting cup, and the lower valve body 3 is provided with a drain outlet 10 communicating downward with the environment; the air outlet 8 and the drain inlet 9 are both vertical through holes arranged in the upper valve body 1, and the total number of the two is greater than two. Figure 6 As shown, there are four holes in total for smooth ventilation and drainage. The air outlet hole 8 and the water inlet hole 9 do not need to be strictly distinguished from each other, and the vertical through hole in the same upper valve body 1 can be used for ventilation and drainage at the same time.

[0051] The center tube 4, the upper end cover 5, the lower end cover 6 and the inner wall of the cylindrical shell 2 form an annular cavity, and a coil 11 is arranged in the annular cavity. The coil 11 is used to connect with the vehicle-mounted ECU through the vehicle-mounted circuit;

[0052] A double-control valve core is arranged in the central tube 4, the air inlet hole 7 and the air outlet hole 8 form an air path passing through the double-control valve core, and the water discharge inlet hole 9 and the water discharge outlet hole 10 form a water path passing through the double-control valve core;

[0053] The air inlet hole 7 and the air outlet hole 8 are connected or isolated by a double-control valve core, and the water discharge inlet hole 9 and the water discharge outlet hole 10 are connected or isolated by a double-control valve core;

[0054] When the coil 11 is energized, the gas circuit and the water circuit are connected at the dual-control valve core at the same time; when the coil 11 is de-energized, the gas circuit and the water circuit are blocked at the dual-control valve core at the same time.

[0055] When the filter is working normally, the water collecting cup is in a negative pressure state, and even if the drain valve is opened, the water cannot be drained normally. With the present invention, the control coil 11 can be energized to conduct the air path and the water path at the same time, solving the problem that the water collecting cup cannot drain normally when the filter is working, and there is no need for personnel to manually unscrew the screw plug under the vehicle, which is very convenient to use.

[0056] An upper sealing groove is provided on the circumferential surface of the upper end cover 5, and an annular upper sealing ring 12 is provided in the upper sealing groove. The upper sealing ring 12 is pressed against the inner wall of the cylindrical shell 2;

[0057] The lower surface of the lower end cover 6 is convex downwardly provided with a bottom groove 29, in which a lower sealing ring 13 is provided, and the lower sealing ring 13 is pressed against a convex ring 14 protruding upwardly into the bottom groove 29 on the top surface of the lower valve body 3. The upper sealing ring 12 and the lower sealing ring 13 ensure that the coil 11 is isolated from the water circuit and the gas circuit under any circumstances.

[0058] The double-control valve core includes a fixed iron core 15 embedded in the middle of the central tube 4 in the up and down directions, an upper moving iron core 16 is provided in the central tube 4 above the fixed iron core 15, and a lower moving iron core 17 is provided in the central tube 4 below the fixed iron core 15; the (electromagnetic) coil 11 is characterized in that: when powered on, the electromagnetic forces generated at both ends of the coil 11 are in the same direction, the winding directions at both ends of the coil 11 are opposite, the number of turns is the same or the number of turns at both ends of the coil 11 is allocated as required. Specifically, the winding direction of the part of the coil 11 located above the fixed iron core 15 is opposite to the winding direction of the part of the coil located below the fixed iron core 15, so that one coil can synchronously drive the upper moving iron core 16 and the lower moving iron core 17, ensuring that when the coil is energized, the air path and the water path are connected at the double-control valve core at the same time; when the coil is de-energized, the air path and the water path are blocked at the double-control valve core at the same time. There is no need to set up two coils to control the upper moving iron core 16 and the lower moving iron core 17 respectively, which not only improves the synchronization of the actions of the upper moving iron core 16 and the lower moving iron core 17, but also reduces the structural complexity and saves manufacturing costs.

[0059] The top surface of the upper end cover 5 is provided with a groove opening upward, and the groove and the upper valve body 1 above it form a water-passing and air-passing cavity 18; the water-passing and air-passing cavity 18 is communicated with the air inlet hole 7 and the air outlet hole 8 respectively;

[0060] The interface of the air inlet hole 7 downwardly connected to the water ventilation cavity 18 is located just above the upper moving iron core 16, and this interface is called the upper interface 22;

[0061] The upper sphere 19 is connected to the top of the upper moving iron core 16, and the upper moving iron core 16 protrudes upward from the middle and upper part of the upper sphere 19; the upper interface 22 is in a trumpet shape matching the upper sphere 19. An upper step hole 25 is provided in the center of the lower part of the upper moving iron core 16, and an upper return spring 21 is pressed between the upper step hole 25 and the fixed iron core 15; when the coil 11 loses power, the upper return spring 21 presses the upper sphere 19 against the upper interface 22 through the upper moving iron core 16 and closes the upper interface 22, in this state, the air inlet 7 is isolated from the air outlet 8;

[0062] When the coil 11 is energized, the upper moving iron core 16 compresses the upper return spring 21 downward so that the upper ball 19 moves downward away from the upper interface 22. In this state, the air inlet 7 is connected to the air outlet 8 through the water ventilation cavity 18;

[0063] A water hole 23 which is transparent from top to bottom is provided at the center of the fixed iron core 15. An annular boss 24 is provided at the middle of the upper and lower parts of the water hole 23, and the top surface of the annular boss 24 is upwardly pressed and matched with the upper return spring 21.

[0064] The upper moving iron core 16 above the upper step hole 25 is recessed on two opposite side surfaces to form upper water steps 35, and the upper water steps 35 and the inner wall of the center tube 4 form an upper water cavity 26; an upper water hole 27 connecting the upper water cavity 26 and the upper step hole 25 is opened in the upper moving iron core 16 at the bottom of the upper water step 35; the upper water hole 27 includes a horizontal part and a vertical part that are connected to each other, the horizontal part is connected to the upper water cavity 26, and the vertical part is connected to the upper step hole 25.

[0065] The part of the bottom groove 29 located inside the convex ring 14 and the lower valve body 3 thereunder form a water passage cavity 28;

[0066] The interface of the water discharge hole 10 communicating with the water passage cavity 28 upward is located directly below the lower moving iron core 17, and this interface is referred to as the lower interface 30;

[0067] The bottom end of the lower moving iron core 17 is connected to the lower sphere 20, and the lower moving iron core 17 protrudes downward from the lower middle part of the lower sphere 20; a lower step hole 31 is provided in the center of the upper part of the lower moving iron core 17, and a lower return spring 32 is pressed between the lower step hole 31 and the fixed iron core 15; the lower interface 30 is in a trumpet shape matching the lower sphere 20.

[0068] The bottom surface of the annular boss 24 is pressed downwardly to fit with the lower return spring 32;

[0069] The upper moving iron core 16 below the lower step hole 31 is provided with lower water-passing steps 33 on both sides thereof, and the lower water-passing steps 33 and the central tube 4 form a lower water-passing cavity 34; the lower moving iron core 17 at the top of the lower water-passing step 33 is provided with a lower water-passing hole 36 connecting the lower water-passing cavity 34 and the lower step hole 31;

[0070] When the coil 11 loses power, the lower return spring 32 presses the lower ball 20 against the lower interface 30 through the lower moving iron core 17 and closes the lower interface 30. In this state, the water inlet hole 9 is isolated from the water outlet hole 10.

[0071] When the coil 11 is energized, the lower moving iron core 17 compresses the lower return spring 32 upward so that the lower sphere 20 moves upward away from the lower interface 30. In this state, the water inlet hole 9 is connected to the water outlet hole 10 through the upper water cavity 26, the upper water through hole 27, the upper step hole 25, the water through hole 23, the lower step hole 31, the lower water through hole 36 and the lower water cavity 34.

[0072] The specific structure of the double-control valve core is reliable, and it is convenient to connect the air and water circuits or shut off the air and water circuits at the same time by controlling the energized and de-energized states of the control coil 11. When the air and water circuits are connected at the same time, water can be discharged under negative pressure; when the air and water circuits are shut off at the same time, water discharge is stopped.

[0073] There are more than two air inlet holes 7 and more than two water inlet holes 9. In this embodiment, there are two air inlet holes 7, and the air outlet holes 8 and water inlet holes 9 are through holes that penetrate the upper valve body 1 from top to bottom, and there are four in total.

[0074] The upper valve body 1 is integrally provided with a horizontal connection seat 37, which is used to connect with the filter, and a connection hole 38 is provided on the connection seat 37;

[0075] The upper valve body 1 above the connecting seat 37 is an insertion part for inserting into a corresponding mounting hole on the filter (the mounting hole is communicated with the water collecting cup of the filter), and an annular mounting sealing groove is provided on the circumferential surface of the insertion part, and a mounting sealing ring 39 is provided in the mounting sealing groove.

[0076] When the present invention is used, there are several conditions that can be selected or simultaneously triggered to drain water. After the drainage is triggered, the coil 11 is energized, the air path and the water path are connected at the same time, and the ambient air enters the water collection cup through the air path under the action of atmospheric pressure, and the water in the water collection cup flows downward. The principle is similar to that when a hospital drips an infusion, the infusion bottle is connected to the atmosphere through the air path and to the human body through the water path, and water will not flow out through the air path.

[0077] The first drainage triggering condition is: the driver directly controls the coil 11 to be energized through the vehicle ECU to drain water; the advantage of the first drainage triggering condition is that the water can be drained at any time, and the drainage occasion can be manually selected before draining, so as to avoid polluting the environment that is not suitable for drainage; and there is no need for personnel to open the screw plug under the vehicle, which is very convenient. The disadvantage is that the driver needs to remember the drainage matters.

[0078] The second drainage triggering condition is: the coil 11 is set to be energized periodically (for example, once a week) through the vehicle ECU to drain water periodically. The advantage of the second drainage triggering condition is that it is simple and easy (just like setting an alarm clock), and the driver does not need to be too concerned about drainage. The disadvantage is that there is no manual selection of drainage occasions, and the setting of the drainage cycle is based on the average use of the vehicle, without considering the specific use of the vehicle in a specific time period (for example, if the vehicle is not driven for a period of time, there is no need to drain water).

[0079] The third triggering condition for drainage is: after the water level sensor in the filter water collection cup detects that the water level reaches or exceeds the predetermined water level, the vehicle-mounted ECU controls the coil 11 to be energized according to the detection signal of the water level sensor to drain the water. The advantage is that the drainage is timely and no human operation is required. The disadvantage is that there is no manual selection of drainage occasions.

[0080] The above three drainage triggering conditions can be selected one by one or can be parallel conditions that are carried out at the same time, that is, drainage is triggered after any one of them is triggered. Preferably, as parallel conditions, if the driver has not forgotten, the coil 11 can be energized after the appropriate drainage occasion and time are manually selected to drain the water. When strengthening the negligence of personnel, there are also trigger drainage conditions 2 and 3 as supplements.

[0081] The above embodiments are only used to illustrate rather than limit the technical solutions of the present invention. Although the present invention is described in detail with reference to the above embodiments, those skilled in the art should understand that the present invention can still be modified or replaced by equivalents. Any modification or partial replacement that does not depart from the spirit and scope of the present invention should be included in the scope of the claims of the present invention.

Claims

1. An automatic drainage device for a filter negative pressure system, comprising an upper valve body, a cylindrical shell and a lower valve body connected in sequence from top to bottom, the lower valve body and the cylindrical shell are screwed or welded, and the upper valve body, the cylindrical shell and the lower valve body form a valve cavity; Features: A vertically arranged center tube is provided in the valve cavity, a horizontal upper end cover is radially extended from the upper end of the center tube, a horizontal lower end cover is radially extended from the lower end of the center tube, the upper end cover is sealed with the top of the inner wall of the cylindrical shell, and the lower end cover is sealed with the bottom of the inner wall of the cylindrical shell; The upper valve body is provided with an air inlet hole communicating with the environment and an air outlet hole communicating upward with the filter water collecting cup; The upper valve body is provided with a drain inlet hole communicating upward with the filter water collecting cup, and the lower valve body is provided with a drain outlet hole communicating downward with the environment; The center tube, the upper end cover, the lower end cover and the inner wall of the cylindrical shell form an annular cavity, and a coil is arranged in the annular cavity. The coil is used to connect with the vehicle-mounted ECU through the vehicle-mounted circuit; A double-control valve core is arranged in the central tube, the air inlet hole and the air outlet hole form an air path passing through the double-control valve core, and the water discharge inlet hole and the water discharge outlet hole form a water path passing through the double-control valve core; When the coil is energized, the gas circuit and the water circuit are connected at the dual-control valve core at the same time; when the coil is de-energized, the gas circuit and the water circuit are blocked at the dual-control valve core at the same time; An upper sealing groove is provided on the circumferential surface of the upper end cover, an annular upper sealing ring is provided in the upper sealing groove, and the upper sealing ring is pressed against the inner wall of the cylindrical shell; The lower surface of the lower end cover is convex downwardly and is provided with a bottom groove, in which a lower sealing ring is provided, and the lower sealing ring is pressed against a convex ring on the top surface of the lower valve body and convexly protrudes upward into the bottom groove; The double-control valve core includes a fixed iron core embedded in the middle of the central tube in the vertical direction, an upper moving iron core is arranged in the central tube above the fixed iron core, and a lower moving iron core is arranged in the central tube below the fixed iron core; The winding direction of the portion of the coil located above the fixed iron core is opposite to the winding direction of the portion of the coil located below the fixed iron core; The top surface of the upper end cover is provided with a groove opening upward, and the groove and the upper valve body above it form a water-passing and air-passing cavity; the water-passing and air-passing cavity is respectively connected with the air inlet hole and the air outlet hole; The interface through which the air inlet hole is downwardly connected to the water ventilation cavity is located directly above the upper moving iron core, and this interface is called the upper interface; The top of the upper moving iron core is connected to an upper sphere, and the upper moving iron core protrudes upward from the middle and upper part of the upper sphere; an upper step hole is provided in the center of the lower part of the upper moving iron core, and an upper reset spring is pressed between the upper step hole and the fixed iron core; when the coil loses power, the upper reset spring presses the upper sphere against the upper interface through the upper moving iron core and closes the upper interface, and in this state, the air inlet hole is isolated from the air outlet hole; When the coil is energized, the upper moving iron core compresses the upper return spring downward so that the upper sphere moves downward away from the upper interface. In this state, the air inlet hole is connected to the air outlet hole through the water ventilation cavity; A water hole which is transparent from top to bottom is provided at the center of the fixed iron core. A circular boss is provided at the middle of the upper and lower parts of the water hole, which protrudes radially inward. The top surface of the circular boss is upwardly pressed and matched with the upper return spring. The upper moving iron core above the upper step hole is respectively recessed with upper water-passing steps on two opposite sides, and the upper water-passing steps and the central tube form an upper water-passing cavity; an upper water-passing hole connecting the upper water-passing cavity and the upper step hole is opened in the upper moving iron core at the bottom of the upper water-passing step; The part of the bottom groove located in the convex ring and the lower valve body below it form a water passage cavity; the interface of the water discharge hole connected with the water passage cavity upward is located directly below the lower moving iron core, and this interface is called the lower interface; The bottom end of the lower moving iron core is connected to a lower sphere, and the lower moving iron core protrudes downward from the middle and lower part of the lower sphere; a lower step hole is provided in the center of the upper part of the lower moving iron core, and a lower return spring is pressed between the lower step hole and the fixed iron core; The bottom surface of the annular boss is pressed downward to fit with the lower return spring; The upper moving iron core below the lower step hole is provided with lower water-passing steps on two opposite sides thereof, and the lower water-passing steps and the central tube form a lower water-passing cavity; the lower moving iron core at the top of the lower water-passing step is provided with a lower water-passing hole connecting the lower water-passing cavity and the lower step hole; When the coil loses power, the lower return spring presses the lower ball onto the lower interface through the lower moving iron core and closes the lower interface. In this state, the water inlet hole is isolated from the water outlet hole. When the coil is energized, the lower moving iron core compresses the lower return spring upward so that the lower ball moves upward away from the lower interface. In this state, the water discharge inlet hole and the water discharge outlet hole are connected through the upper water cavity, the upper water through hole, the upper step hole, the water through hole, the lower step hole, the lower water through hole and the lower water cavity; A horizontal connecting seat is integrally provided on the upper valve body, and the connecting seat is used to connect with the filter, and a connecting hole is provided on the connecting seat; The upper valve body above the connecting seat is an inserting part for inserting into a corresponding mounting hole on the filter, and an annular mounting sealing groove is provided on the circumferential surface of the inserting part, and a mounting sealing ring is provided in the mounting sealing groove.

2. The automatic drainage device for the filter negative pressure system according to claim 1, characterized in that: There are more than two air inlet holes and more than two water inlet holes.

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