Normally open electromagnetic valve

Abstract

In order to reduce noise, a movable iron core and a valve needle are movably connected in a matched mode through a first spring, and the impact force generated when the valve needle makes contact with a main valve element is reduced; the valve needle is designed to be of a wide-end-up structure, the valve needle can be conveniently inserted into the upper portion of the driven iron core for assembly, assembly is convenient, and coaxiality is high. A ventilation cutting groove is formed in the outer side wall of the valve needle, extends from a thin cylinder on the lower portion of the valve needle to a thick cylinder on the upper portion of the valve needle, and penetrates through an inner cavity of the thick cylinder and an inner cavity of the movable iron core, so that it is guaranteed that airflow in the upper space of the movable iron core and airflow in the upper space of the main valve element are smoothly communicated; a good guiding effect is improved for axial movement of the static iron core, and the valve needle of the structure is high in strength and easier to machine; the integrated main valve element made of the elastic material is arranged on the lower portion of the valve needle, the pilot opening is formed in the main valve element, and the main valve element is wrapped by the metal guide sleeve, so that the sealing effect of the main valve element is good, and the guide effect of axial movement is good.

Description

Technical Field

[0001] The invention relates to the technical field of solenoid valves, and mainly refers to a normally open solenoid valve used in automobile air-conditioning systems. Background Art

[0002] Normally open solenoid valves are often used in automobile air conditioning systems to control the on and off of fluid pipelines. Normally open solenoid valves use the moving iron core to drive the valve needle to move axially, and use the valve needle to push the main valve core set at the bottom of the valve needle to seal the main valve port and cut off the fluid. When the valve core inside the solenoid valve moves axially, the sealing and the smoothness of the axial movement must be considered. In order to prevent the "air holding" phenomenon caused by the axial air path blockage when the moving iron core moves axially, a reasonable air path design is required.

[0003] The invention patent with publication number CN117739152A discloses "a normally open solenoid valve for automobile air spring". The patent is to open a ventilation slot along the axial direction on the outer side wall of the moving iron core, the top rod under the moving iron core is narrow at the top and wide at the bottom, and a through hole is opened on the wider pipe sleeve base at the bottom of the top rod. Figure 1 It can be seen that the ventilation channel between the upper space of the automatic iron core and the upper space of the main valve core in the patent is actually formed by the combination of two channels, namely: a channel is formed from the ventilation groove along the side wall of the moving iron core on the upper part of the automatic iron core to the space between the moving iron core and the top of the base, and then another channel is formed from the top space of the base along the gap between the inner wall of the base and the top rod of the top rod, through the through hole on the pipe sleeve base of the top rod. It is obvious that the air path formed after the above two channels are connected has a turn. This design cannot form a smooth air path well. It is necessary to leave a larger matching gap during assembly to ensure smooth ventilation, which has some impact on improving the sealing of the valve core. In addition, a magnetic isolation tube is set on the outside of the moving iron core in the patent, and the axial movement of the moving iron core is guided by the magnetic isolation tube. However, in order to ensure smooth ventilation, the matching gap between the moving iron core and the magnetic isolation tube is larger, which will reduce the guiding effect of the magnetic isolation tube on the moving iron core.

[0004] Another utility model patent with announcement number CN220523321U discloses "a normally open solenoid valve with high sealing performance". The ventilation channel of this patent is straight up and down, and the moving iron core and the ejector pin at the bottom of the moving iron core are designed to be hollow structures. The ejector pin is narrow at the top and wide at the bottom, and the narrow end of the ejector pin is riveted to the bottom of the moving iron core. Although this structural design is obviously better than the solution in the previous patent in terms of ventilation smoothness, it has the following shortcomings: (1) The moving iron core and the ejector pin are riveted together. The moving iron core drives the ejector pin to hit the sealing block of the main valve core, which has a large impact force and is prone to generate a lot of noise; (2) The ejector pin is narrow at the top and wide at the bottom. When assembling the ejector pin, it needs to be passed upward from the bottom of the valve seat and then riveted to the moving iron core. This structure is difficult to assemble and has poor coaxiality. (3) The ejector pin has a hollow structure, which is difficult to process and has a certain impact on strength; (4) An ejector pad is provided at the lower part of the ejector, a valve core pad is provided at the lower part of the sealing block, a pilot port is provided at the top of the sealing block, the sealing block moves axially with the inner wall of the valve seat as a guide, and a valve core gasket is provided between the sealing block and the inner wall of the valve seat. In this structural design, in order to ensure a good guiding effect between the sealing block and the inner wall of the valve seat, there must be a gap between the sealing block and the inner wall of the valve seat, and the material of the sealing block must be a material with a low friction coefficient. Therefore, in order to improve the sealing performance, the patent adds an ejector pad for blocking the pilot port at the upper part of the sealing block, and adds a valve core pad for blocking the main valve port at the lower part of the sealing block. In this split sealing design, if one of the parts is worn, the overall sealing effect will be affected; (5) The air inlet and outlet channels on the valve body are not on the same straight line, and the height of the valve body is relatively high. Summary of the invention

[0005] The invention discloses a normally open electromagnetic valve, which has the advantages of convenient assembly, low noise, smooth gas path and good sealing performance.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is: A normally open solenoid valve comprises a valve body and a valve core assembly, the valve core assembly comprises a valve core sleeve located on the upper part of the valve body and a static iron core embedded with the valve body, the valve core sleeve is closed at the top but open at the bottom, a moving iron core and a valve needle are arranged inside the valve core sleeve, the moving iron core is located on the upper part of the static iron core, both the moving iron core and the static iron core are hollow inside and open at the upper and lower ends, a cover is fixedly installed on the upper part of the inner cavity of the moving iron core, a through hole is provided on the cover which is respectively connected with the inner cavity of the moving iron core and the inner cavity of the valve core sleeve, the inner cavity of the moving iron core is connected with the inner cavity of the static iron core, the width of the inner cavity of the moving iron core near the cover end is greater than the width near the end of the static iron core; the valve needle comprises a first cylinder and a second cylinder connected from top to bottom, the first cylinder is a hollow structure and is open at the top, the diameter of the first cylinder is greater than the diameter of the second cylinder, the first cylinder is located in the wider inner cavity of the upper part of the moving iron core, the first cylinder The body and the sealing cover are connected by a first spring, and the moving iron core moves axially with the outer wall of the first cylinder as a guide reference. The second spring is sleeved on the second cylinder, and the second cylinder passes through the inner cavity of the lower part of the moving iron core and the inner cavity of the static iron core. The second cylinder of the valve needle moves axially with the inner cavity wall of the static iron core as a guide reference; a ventilation groove is axially arranged on the outer wall of the valve needle from the bottom to the first cylinder, and the ventilation groove passes through the inner cavity of the first cylinder. An elastic main valve core is arranged at the lower part of the valve needle, a pilot port is arranged at the top of the main valve core, and a through hole with an aperture larger than the pilot port is arranged at the lower part of the pilot port, and the pilot port is connected with the through hole, and the outer circumference of the main valve core is covered and fixed by the guide sleeve, and the guide sleeve is embedded in the inner cavity of the static iron core, and the guide sleeve drives the main valve core to move axially with the inner cavity wall of the static iron core as a guide reference. A third spring is arranged at the bottom of the guide sleeve, and the third spring is fixed on the valve body.

[0007] Furthermore, an air inlet channel and a connecting chamber are provided at one end of the valve body, and the air inlet channel is connected to the connecting chamber in a straight line. An air outlet channel and a sealing chamber are provided at the other end of the valve body, and the air outlet channel is connected to the sealing chamber in a straight line. The connecting chamber and the sealing chamber are respectively connected to the inner chamber of the static iron core, and the connecting chamber and the sealing chamber are not connected in a straight line. When the main valve core does not block the sealing chamber, the connecting chamber and the sealing chamber are connected, and the air inlet channel and the air outlet channel are located on the same straight line.

[0008] Furthermore, the inner cavity of the first cylinder of the valve needle serves as a first spring accommodating cavity, the upper end of the first spring is fixed to the bottom of the cover, the lower part of the first spring is placed in the first spring accommodating cavity, and the lower end of the first spring is fixed to the first cylinder.

[0009] Furthermore, a convex cone protruding from the bottom surface of the second cylinder of the valve needle is provided on the bottom surface of the second cylinder, and the shape of the convex cone matches the shape of the pilot port on the main valve core, and the convex cone is used to block the pilot port of the main valve core.

[0010] Furthermore, the main valve core is an integrated structure formed by stacking multiple cylinders of different diameters up and down. The diameter of the cylinder on the main valve core gradually increases from the end close to the valve needle to the bottom. The guide sleeve is made of metal. The middle part of the guide sleeve is provided with an inner chamber matching the shape of the main valve core. The main valve core is embedded in the inner chamber from the bottom of the guide sleeve and fixed.

[0011] Furthermore, an outer annular wall is provided on the outer circumference of the inner chamber of the guide sleeve, an inner cylinder is formed at the top of the inner chamber, an annular cavity is formed between the inner cylinder and the outer annular wall, the lower part of the outer annular wall is located on the outer circumference of the inner chamber to form a third spring slot, the third spring is arranged in the third spring slot, the upper end of the third spring is fixed on the guide sleeve, and the lower end of the third spring is fixed on the valve body.

[0012] Furthermore, the cover includes an upper cylinder and a lower cylinder connected to each other, the diameter of the upper cylinder is larger than the diameter of the lower cylinder, the upper inner cavity wall of the moving iron core forms a first step, and the first step is used to limit the upper cylinder of the cover; a second step is formed on the inner cavity wall of the moving iron core at the lower part of the cover, and the second step is used to limit the first cylindrical body of the valve needle; a frustum is formed at the lower part of the moving iron core, which is wide at the top and narrow at the bottom, and a third step is formed at the transition between the frustum and the outer wall of the moving iron core, and the third step is used to limit the moving iron core when the moving iron core contacts the static iron core.

[0013] Furthermore, the inner chamber of the static iron core is divided into an upper chamber, a middle chamber and a lower chamber from top to bottom, the inner diameter of the upper chamber is larger than the inner diameter of the middle chamber, the inner diameter of the lower chamber is larger than the inner diameter of the upper chamber, and the upper inner wall of the upper chamber forms a conical surface matching the outer circumferential surface of the truncated cone of the moving iron core; a first limiting step is formed on the outer circumferential wall of the upper chamber, the upper part of the static iron core is inserted into the valve core sleeve, the lower part of the static iron core is embedded in the inner cavity of the valve body, and the bottom of the valve core sleeve is fixed at the first limiting step; a second limiting step is formed at the transition between the upper chamber and the middle chamber, the second limiting step is used to limit the lower end of the second spring, and a sealing ring limiting groove is formed on the outer circumferential wall of the lower chamber, a sealing ring is arranged in the sealing ring limiting groove, and the sealing ring is used to seal between the outer wall of the static iron core and the inner cavity wall of the valve body.

[0014] The solenoid valve designed in the present invention has a movable fitting connection between the moving iron core and the valve needle, and a first spring is used to combine the two together, which can effectively reduce the impact force of the valve needle in the process of contacting the main valve core, thereby reducing the working noise; secondly, the valve needle designed in the present invention is wide at the top and narrow at the bottom, and can be directly inserted from the top of the static iron core to the bottom for assembly. Compared with the valve needle structure with a narrow top and a wide bottom in the prior art, the assembly is more convenient and quick; thirdly, the present invention provides a ventilation groove on the side wall of the valve needle, and the ventilation groove extends from the bottom of the second cylinder at the bottom of the valve needle to the first cylinder at the top, and passes through the inner cavity of the first cylinder, so that the airflow between the upper space of the moving iron core and the upper space of the main valve core is smooth; in the design of the guiding effect for the axial movement of the moving iron core and the valve needle, the inner cavity wall of the first cylinder and the moving iron core adopts a small gap to make the moving iron core With the outer wall of the first cylinder as the guide reference, the second cylinder and the inner wall of the static iron core are also matched with a small gap, so that the second cylinder of the valve needle uses the inner wall of the static iron core as the guide reference, thereby improving the guiding effect of the moving iron core and the valve needle; a ventilation groove is arranged on the side wall of the valve needle, which is easier to process than a hollow structure, and the strength of the valve needle is also higher; the present invention directly uses elastic material to make an integrated main valve core, and a pilot port is arranged on the main valve core. The outside of the main valve core is covered with a metal guide sleeve, which can ensure that the integrated main valve core has a good sealing effect and can also ensure that the guiding effect is good during its axial movement. The main valve core is pushed downward by the valve needle, and the convex cone at the bottom of the valve needle first blocks the pilot port on the main valve core to play a valve closing role. The main valve core is pushed to the upper part of the sealing cavity of the valve body to complete the closing of the main valve port. The above structural design achieves a better valve closing and sealing effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of assembling the valve core component and the valve body of the normally open solenoid valve in the embodiment; Figure 2 for Figure 1 Exploded view of the valve core assembly and valve body; Figure 3 The exploded view of the valve core assembly; Figure 4 Schematic diagram of the structure of the valve needle; Figure 5 It is a structural schematic diagram of the top of the valve needle; Figure 6 This is a schematic diagram of the structure of the main valve core; Figure 7 Schematic diagram of the structure of the guide sleeve; Figure 8 is a cross-sectional view of the static iron core; Fig. 9 for Figure 1 sectional view of Fig.10 A cross-sectional view of the valve core assembly.

[0016] Reference numerals: 1. Valve body; 2. Valve core sleeve; 3. Cover; 301. Upper cylinder; 302. Lower cylinder; 303. Through hole; 4. Moving iron core; 401. First step; 402. Second step; 403. Round table; 404. Third step; 405. Cylinder; 5. Valve needle; 501. First cylinder; 502. Second cylinder; 503. Ventilation groove; 504. Convex cone; 505. First spring accommodating chamber; 506. Ventilation hole; 6. Stationary iron core; 601. Conical surface; 602. First limit table Step; 603, second limit step; 604, sealing ring limit ring groove; 605, lower chamber; 606, upper chamber; 607, middle chamber; 7, main valve core; 701, pilot port; 702, through hole; 8, guide sleeve; 801, inner cylinder; 802, outer ring wall; 803, annular cavity; 804, third spring limit step; 9, first spring; 10, second spring; 11, sealing ring; 12, third spring; 13, air inlet channel; 14, connecting chamber; 15, sealing chamber; 16, air outlet channel. DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0018] This embodiment discloses a normally open solenoid valve. Figure 1 and Figure 2 As shown, it mainly includes a valve body 1 and a valve core assembly installed on the valve body 1. In order to make the accompanying drawings more focused on showing the structure related to the technical improvement of the present invention, Figure 1 The product shown is a simplified diagram, omitting the schematic diagram of conventional structures such as the external coil of the main valve core.

[0019] The structure of the valve body 1 is as follows Figure 2 and Fig. 9 As shown, Fig. 9 The direction shown is for reference. The left end of the valve body 1 is the air inlet channel 13, and the right end is the air outlet channel 16, wherein the air inlet channel 13 is in linear communication with the connecting chamber 14, and the air outlet channel 16 is in linear communication with the sealing chamber 15. There is a gap between the connecting chamber 14 and the sealing chamber 15 and they cannot be in linear communication with each other. In this embodiment, the air inlet channel 13 and the air outlet channel 16 are designed to be on the same straight line, which is conducive to reducing the overall height of the valve body 1. The space above the connecting chamber 14 and the sealing chamber 15 is the valve core chamber for installing the valve core. The connecting chamber 14 and the sealing chamber 15 are respectively connected to the valve core chamber. When the sealing chamber 15 is not blocked by the main valve core 7, the fluid can enter the connecting chamber 14 along the air inlet channel 13, and then flow into the sealing chamber 15 through the valve core chamber, and finally flow out from the air outlet channel 16.

[0020] Valve core components such as Figure 2 and Figure 3 As shown, it mainly includes a valve core sleeve 2, a moving iron core 4, a stationary iron core 6, a valve needle 5, and a main valve core 7. The valve core sleeve 2 is a hollow sleeve with an open bottom, and a coil is arranged outside it. Fig. 9 As shown, the movable iron core 4 and the valve needle 5 are both located inside the valve core sleeve 2, the upper part of the static iron core 6 is embedded in the valve core sleeve 2, and the remaining part is exposed outside the valve core sleeve 2, and the exposed part of the static iron core 6 is fixedly installed in the valve core cavity of the valve body 1. The following first describes the structure of each component constituting the valve core assembly one by one, and then describes the connection relationship between the components in detail in conjunction with the drawings.

[0021] The structure of the valve needle 5 is as follows Figure 4 and Figure 5 As shown, the body of the valve needle 5 is divided into a first cylinder 501 located at the upper part and a second cylinder 502 located at the lower part. The diameter of the first cylinder 501 is larger than that of the second cylinder 502. The first cylinder 501 is a hollow structure with an open top surface. The inner cavity of the first cylinder 501 can be used as a first spring accommodating cavity 505. The middle part of the bottom surface of the second cylinder 502 protrudes outward to form an inverted cone convex cone 504. A ventilation groove 503 is provided along the length direction of the outer wall of the second cylinder 502. The ventilation groove 503 extends upward from the bottom surface of the second cylinder 502 to the outer wall of the first cylinder 501. The ventilation groove 503 directly penetrates the side wall of the first cylinder 501 and communicates with the inner cavity of the first cylinder 501. The ventilation groove 503 can be provided on only one side of the valve needle 5, or can be symmetrically provided on both sides. The latter structure is adopted in this embodiment.

[0022] The main valve core 7 is made of elastic material, such as polytetrafluoroethylene. In this embodiment, the main valve core 7 is an integrally formed structure. Figure 6 As shown, the main valve core 7 is an integrated structure formed by stacking multiple cylinders with different diameters. In this embodiment, a three-layer cylindrical stacking structure is used as an example. Figure 6 The direction shown is for reference, and the diameter of the cylinder gradually increases from top to bottom. A through hole is provided in the middle of the main valve core 7 along the axial direction, such as Fig.10 As shown, the through hole on the main valve core 7 can be divided into a pilot port 701 located at the upper part and a through hole 702 located at the lower part. The inner diameter of the pilot port 701 is smaller than the inner diameter of the through hole 702. The pilot port 701 and the through hole 702 are connected up and down. The shape of the pilot port 701 matches the shape of the convex cone 504 at the bottom of the valve needle 5.

[0023] The main valve core 7 mainly seals the main valve port of the valve body 1. In order to ensure that the main valve core 7 has a good guiding effect when moving along the axial direction, a metal guide sleeve 8 is used in this embodiment to be sleeved on the outside of the main valve core 7. The structure of the guide sleeve 8 is as follows: Figure 7As shown, the guide sleeve 8 is cylindrical in shape as a whole, and comprises an outer ring wall 802 located on the outer circumference, and an inner cylinder 801 located inside the outer ring wall 802. The outer ring wall 802 and the inner cylinder 801 are connected by a horizontal ring plate. The top surface of the inner cylinder 801 is lower than the top surface of the outer ring wall 802. An annular cavity 803 is formed between the outer ring wall 802 and the inner cylinder 801. A through hole is provided in the middle of the inner cylinder 801 along the axial direction, as shown in FIG. Fig.10 As shown, the lower part of the inner cylinder 801 forms an inner chamber matching the outer shape of the main valve core 7, and the bottom of the inner chamber is open, so that the main valve core 7 can be easily embedded into the inner chamber from the bottom of the guide sleeve 8 for fixation. A third spring limiting step 804 is formed at the lower part of the outer ring wall 802 and on the outer circumference of the inner chamber. The guide sleeve 8 and the main valve core 7 are assembled to form an integral part.

[0024] The structure of the moving iron core 4 is as follows Figure 3 and Fig.10 As shown, the main body of the moving iron core 4 is a cylinder 405, and the lower part of the main body is a conical cone 403, which gradually narrows from top to bottom, and the connection transition between the main body and the conical cone 403 forms a third step 404. The moving iron core 4 is a hollow structure with upper and lower open openings. The chamber inside the moving iron core 4 is connected from top to bottom. The inner cavity of the moving iron core 4 can be divided into an upper chamber, a middle chamber and a lower chamber with gradually decreasing inner diameters from top to bottom. The connection between the upper chamber and the middle chamber forms a first step 401, and the connection between the middle chamber and the lower chamber forms a second step 402.

[0025] The structure of the static iron core 6 is as follows Figure 8 As shown, the static iron core 6 is also a hollow cylindrical structure, with open upper and lower ends. The inner chamber of the static iron core 6 is divided into an upper chamber 606, a middle chamber 607 and a lower chamber 605 from top to bottom. The inner diameter of the upper chamber 606 is larger than the inner diameter of the middle chamber 607, and the inner diameter of the lower chamber 605 is larger than the inner diameter of the upper chamber 606. The upper inner wall of the upper chamber 606 forms a conical surface 601 matching the outer circumferential surface of the truncated cone 403 of the moving iron core 4, the transition between the outer circumferential wall of the upper chamber 606 and the outer circumferential wall of the middle chamber 607 forms a first limiting step 602, the transition between the inner wall of the upper chamber 606 and the inner wall of the middle chamber 607 forms a second limiting step 603, and the outer circumferential wall of the lower chamber 605 forms a sealing ring limiting annular groove 604.

[0026] The assembly relationship of the components constituting the valve core assembly given above is as follows: Fig. 9 and Fig.10As shown, the thickest cylinder at the bottom of the static iron core 6 is embedded in the valve core cavity of the valve body 1 and fixed. In order to improve the sealing between the outer wall of the static iron core 6 and the inner wall of the valve core cavity, an O-ring 11 is installed in the sealing ring limiting ring groove 604 of the static iron core 6. The uppermost cylinder of the static iron core 6 is embedded in the interior of the valve core sleeve 2, and the bottom of the valve core sleeve 2 is stuck at the first limiting step 602. Above the static iron core 6 is the moving iron core 4, which is completely placed in the valve core sleeve 2, and one side of the truncated cone 403 of the moving iron core 4 faces the static iron core 6. When the solenoid valve is energized, the moving iron core 4 moves downward, and when the third step 404 on the moving iron core 4 contacts the top of the static iron core 6, the moving iron core 4 is limited. At this time, a certain height of space is left between the upper part of the moving iron core 4 and the top of the valve core sleeve 2. The valve needle 5 is inserted downward from the upper part of the moving iron core 4 into the interior of the moving iron core 4, the first cylinder 501 of the valve needle 5 is located in the middle chamber of the moving iron core 4, and the second step 402 serves to limit the first cylinder 501 of the valve needle 5. In order to reduce the working noise of the solenoid valve in this embodiment, the riveting method of the valve needle 5 and the moving iron core 4 in the prior art is abandoned, and a cover 3 is installed in the upper chamber of the moving iron core 4. The cover 3 includes an upper cylinder 301 and a lower cylinder 302 connected to each other, the diameter of the upper cylinder 301 is larger than the diameter of the lower cylinder 302, and a through hole 303 is axially opened in the middle of the cover 3, the upper cylinder 301 is located in the upper chamber of the moving iron core 4, and the lower cylinder 302 is located in the middle chamber of the moving iron core 4, and the cover 3 is fixedly connected to the moving iron core 4. A first spring 9 is arranged between the cover 3 and the first cylinder 501 of the valve needle 5. The upper end of the first spring 9 is fixed to the bottom of the cover 3. The lower part of the first spring 9 is embedded in the first spring accommodating cavity 505 of the first cylinder 501 and fixed. The first spring 9 is used to realize the movable matching connection between the valve needle 5 and the movable iron core 4. A second spring 10 is sleeved on the second cylinder 502 of the valve needle 5. The second cylinder 502 penetrates the middle chamber, the lower chamber of the iron core 4, the upper chamber, the middle chamber and the lower chamber of the static iron core. The second step 402 limits the upper end of the second spring 10, and the second limiting step 603 limits the lower end of the second spring 10. After the guide sleeve 8 and the main valve core 7 are assembled into an integral part, they are installed from the bottom of the static iron core 6 to the lower chamber 605 of the static iron core 6. The outer wall of the guide sleeve 8 and the inner wall of the lower chamber 605 are matched with a small gap, so that the guide sleeve 8 moves axially with the inner wall of the lower chamber 605 as the guide reference. A third spring 12 is arranged between the bottom of the guide sleeve 8 and the sealing cavity 15 of the valve body 1 , the upper end of the third spring 12 is fixed to the third spring limiting step 804 of the guide sleeve 8 , and the lower end of the third spring 12 is fixed to the valve body 1 .

[0027] The working principle of the solenoid valve assembled in the above manner is as follows: when the coil of the solenoid valve is energized, the moving iron core 4 begins to move downward, the first spring 9 is compressed, and the valve needle 5 is also pushed downward, and the convex cone 504 at the bottom of the valve needle 5 first blocks the pilot port 701 at the top of the main valve core 7, and the valve needle 5 pushes the main valve core 7 downward during the downward movement until the main valve core 7 completely blocks the sealing cavity 15 of the valve body 1, thereby completing the valve closing action and blocking the flow of fluid inside the valve body 1. When the coil of the solenoid valve is de-energized, the compressed third spring 12 will push the main valve core 7 and the guide sleeve 8 to move upward together under the action of elastic force, and the valve needle 5 is also pushed upward by the main valve core 7, and the compressed second spring 10 will continue to push the valve needle 5 upward under the action of elastic force, and the compressed first spring 9 will also push the cover 3 under the action of elastic force and drive the moving iron core 4 to move upward together to reset.

[0028] The movable iron core 4 in the present invention uses the outer wall of the first cylindrical body 501 of the valve needle 5 as a guide reference, and the two form a small gap fit; the second cylindrical body 502 of the valve needle 5 uses the inner wall of the middle chamber 607 of the stationary iron core as a guide reference, and the two also form a small gap fit; the guide sleeve 8 uses the inner wall of the lower chamber 605 of the stationary iron core 6 as a guide reference, and the two form a small gap fit. The above settings all ensure good guiding effects and are very convenient to assemble. Fig. 9 It can be seen that the ventilation channel design from the upper space of the automatic iron core 4 to the lower chamber 605 of the static iron core 6 of the present invention is generally straight up and down, ensuring smooth ventilation and preventing the "air holding" problem from occurring during the up and down movement of the moving iron core 4. The main valve core 7 of the present invention adopts an integrated structure, which can play a better sealing role.

[0029] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A normally open solenoid valve, comprising a valve body and a valve core assembly, wherein the valve core assembly comprises a valve core sleeve located on the upper part of the valve body and a static iron core engaged with the valve body, wherein the valve core sleeve is closed at the top but open at the bottom, wherein a moving iron core and a valve needle are arranged inside the valve core sleeve, wherein the moving iron core is located on the upper part of the static iron core, wherein both the moving iron core and the static iron core are hollow inside and open at the upper and lower ends, wherein the valve core sleeve is closed at the top but open at the bottom, wherein ... closed at the top and lower ends, and wherein the valve core sleeve is closed at the top and lower ends, and wherein the moving iron core and the static iron core are closed at the top and lower ends, and wherein the moving iron core and the static iron core are hollow inside and open at the upper and lower ends, A sealing cover is fixedly installed on the upper part of the inner cavity of the moving iron core, and a through hole is provided on the sealing cover, which is respectively connected with the inner cavity of the moving iron core and the inner cavity of the valve core sleeve, and the inner cavity of the moving iron core is connected with the inner cavity of the static iron core, and the width of the inner cavity of the moving iron core near the sealing cover is greater than the width near the end of the static iron core; the valve needle includes a first cylinder and a second cylinder connected from top to bottom, the first cylinder is a hollow structure with an open top, the diameter of the first cylinder is greater than the diameter of the second cylinder, the first cylinder is located in the wider inner cavity at the upper part of the moving iron core, the first cylinder and the sealing cover are connected by a first spring, the moving iron core moves axially with the outer wall of the first cylinder as a guide reference, a second spring is sleeved on the second cylinder, and the second cylinder The cylinder passes through the lower inner cavity of the moving iron core and the inner cavity of the static iron core, and the second cylinder of the valve needle moves axially with the inner cavity wall of the static iron core as a guide reference; a ventilation groove is axially arranged on the outer wall of the valve needle from the bottom to the first cylinder, and the ventilation groove passes through the inner cavity of the first cylinder, and an elastic main valve core is arranged at the lower part of the valve needle, a pilot port is arranged at the top of the main valve core, and a through hole with an aperture larger than the pilot port is arranged at the lower part of the pilot port, and the pilot port is communicated with the through hole, and the outer circumference of the main valve core is covered and fixed by a guide sleeve, and the guide sleeve is embedded in the inner cavity of the static iron core, and the guide sleeve drives the main valve core to move axially with the inner cavity wall of the static iron core as a guide reference, and a third spring is arranged at the bottom of the guide sleeve, and the third spring is fixed on the valve body.

2. A normally open solenoid valve according to claim 1, characterized in that: One end of the valve body is provided with an air inlet channel and a connecting cavity, and the air inlet channel is connected to the connecting cavity in a straight line. The other end of the valve body is provided with an air outlet channel and a sealing cavity, and the air outlet channel is connected to the sealing cavity in a straight line. The connecting cavity and the sealing cavity are respectively connected to the inner cavity of the static iron core, and the connecting cavity and the sealing cavity are not connected in a straight line. When the main valve core does not block the sealing cavity, the connecting cavity and the sealing cavity are connected, and the air inlet channel and the air outlet channel are located on the same straight line.

3. A normally open solenoid valve according to claim 1, characterized in that: The first cylindrical inner cavity of the valve needle serves as a first spring accommodating cavity, the upper end of the first spring is fixed to the bottom of the cover, the lower part of the first spring is placed in the first spring accommodating cavity, and the lower end of the first spring is fixed to the first cylinder.

4. A normally open solenoid valve according to claim 1, characterized in that: A convex cone protruding from the bottom surface of the second cylinder of the valve needle is provided on the bottom surface of the second cylinder. The shape of the convex cone matches the shape of the pilot port on the main valve core. The convex cone is used to block the pilot port of the main valve core.

5. A normally open solenoid valve according to claim 1, characterized in that: The main valve core is an integrated structure formed by stacking multiple cylinders of different diameters. The diameter of the cylinder on the main valve core gradually increases from the end close to the valve needle to the bottom. The guide sleeve is made of metal. The middle part of the guide sleeve is provided with an inner chamber matching the shape of the main valve core. The main valve core is embedded in the inner chamber from the bottom of the guide sleeve and fixed.

6. A normally open solenoid valve according to claim 5, characterized in that: An outer annular wall is provided on the outer circumference of the inner chamber of the guide sleeve, an inner cylinder is formed on the top of the inner chamber, an annular cavity is formed between the inner cylinder and the outer annular wall, the lower part of the outer annular wall is located on the outer circumference of the inner chamber to form a third spring slot, the third spring is arranged in the third spring slot, the upper end of the third spring is fixed on the guide sleeve, and the lower end of the third spring is fixed on the valve body.

7. A normally open solenoid valve according to claim 1, characterized in that: The cover includes an upper cylinder and a lower cylinder connected to each other, the diameter of the upper cylinder is larger than the diameter of the lower cylinder, the upper inner cavity wall of the moving iron core forms a first step, and the first step is used to limit the upper cylinder of the cover; a second step is formed on the inner cavity wall of the moving iron core at the lower part of the cover, and the second step is used to limit the first cylindrical body of the valve needle; a frustum is formed at the lower part of the moving iron core, which is wide at the top and narrow at the bottom, and a third step is formed at the transition between the frustum and the outer wall of the moving iron core, and the third step is used to limit the moving iron core when the moving iron core contacts the static iron core.

8. A normally open solenoid valve according to claim 7, characterized in that: The inner chamber of the static iron core is divided into an upper chamber, a middle chamber and a lower chamber from top to bottom. The inner diameter of the upper chamber is larger than that of the middle chamber, and the inner diameter of the lower chamber is larger than that of the upper chamber. The upper inner wall of the upper chamber forms a conical surface matching the outer circumferential surface of the truncated cone of the moving iron core; a first limiting step is formed on the outer circumferential wall of the upper chamber, the upper part of the static iron core is inserted into the valve core sleeve, the lower part of the static iron core is embedded in the inner cavity of the valve body, and the bottom of the valve core sleeve is fixed at the first limiting step; a second limiting step is formed at the transition between the upper chamber and the middle chamber, and the second limiting step is used to limit the lower end of the second spring, and a sealing ring limiting groove is formed on the outer circumferential wall of the lower chamber, and a sealing ring is arranged in the sealing ring limiting groove, and the sealing ring is used to seal between the outer wall of the static iron core and the inner cavity wall of the valve body.

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