Oil immersion type miniature electromagnetic valve and control method thereof

Abstract

The invention relates to the technical field of electromagnetic valves, in particular to an oil immersion type miniature electromagnetic valve and a control method thereof, the working environment of the miniature electromagnetic valve is adjusted to be oil immersion, so that the length of an external oil return channel in the radial direction can be shortened, an additional oil discharge channel does not need to be arranged, the external oil return channel is communicated with external oil, the size of the electromagnetic valve can be reduced, and the cost is reduced. Meanwhile, the production difficulty and the production cost can be reduced, and the production efficiency is improved; the valve needle and the armature are of a split structure, so that during production and installation, the coaxiality of the armature and the coil framework and the coaxiality of the valve needle and the valve body are guaranteed, the movement control of the valve needle can be guaranteed, the valve needle cannot be driven to deviate after the armature is heated and expanded, the sealing effect and the control reliability of the valve needle are guaranteed, and the service life is prolonged; installation and maintenance cost is reduced, and actual use requirements are met.

Description

Technical Field

[0001] The invention relates to the technical field of solenoid valves, and in particular to an oil-immersed micro solenoid valve and a control method thereof. Background Art

[0002] In petroleum logging instruments, due to the limitations of wellhead and casing size, the outer diameter of petroleum logging instruments is relatively small, and the size requirements for the components used are also smaller; with the continuous development of logging technology, the well depth continues to deepen and the well temperature continues to increase, and the temperature and pressure resistance requirements for the components used are also higher.

[0003] Many solenoid valves currently used in hydraulic oil logging instruments, such as the Chinese utility model patent with application number 202021310781.1, provide a miniature solenoid valve that changes the position and direction of the channel on the valve body so that the valve core is not subjected to the pressure of the liquid in the axial direction, thereby improving the pressure-bearing capacity of the solenoid valve; however, it opens each channel in the radial direction of the valve core, which increases the volume of the solenoid valve and reduces its scope of application, and cannot meet the requirements of small-size use.

[0004] At the same time, the valve core of the solenoid valve is connected to the armature, and high coaxiality must be ensured between the coil frame, the valve core and the valve body. This increases the difficulty of installation and reduces production efficiency on the one hand. On the other hand, the armature is deformed by heat in a high-temperature environment, which affects the coaxiality of the valve core. Therefore, the valve core increases loss during frequent movement, while also reducing the sealing performance, increasing the failure rate, reducing service life, and increasing the difficulty and cost of maintenance and replacement, which cannot meet actual usage needs. Summary of the invention

[0005] The purpose of the present invention is to provide an oil-immersed micro solenoid valve and a control method thereof, so as to solve the technical problems that the current micro solenoid valves are large in size and have a short service life.

[0006] The present invention solves the above-mentioned technical problems by: An oil-immersed micro solenoid valve, comprising a coil frame, a high temperature resistant coil, an armature, a valve needle and a valve body, wherein the high temperature resistant coil is sleeved on one side of the coil frame, the armature is arranged inside the coil frame and elastically connected to the coil frame, one end of the valve needle is close to the armature, the other end of the valve needle extends into the valve body, and the valve body is connected to the coil frame; The valve body is provided with an external oil return channel, a control channel and an oil inlet pressure channel in sequence, and the external oil return channel and the control channel are both opened in the radial direction of the valve body; the oil inlet pressure channel is opened in the axial direction of the valve body, and the external oil return channel is connected with the oil inlet pressure channel through the control channel; The valve needle reciprocates along the axial direction of the valve body to adjust the external oil return channel to communicate with the control channel, or the control channel to communicate with the oil inlet pressure channel.

[0007] It is further defined that the coil skeleton includes a coil stop iron, a magnetic isolation tube and a coil connection seat connected in sequence, the coil stop iron and the coil connection seat are tightly connected with the magnetic isolation tube, and the coil stop iron, the magnetic isolation tube and the coil connection seat are coaxially connected, the outer side of the coil connection seat is sleeved with a mounting seat, and the high temperature resistant coil sleeve is arranged between the outer end surface of the coil stop iron and the mounting seat; The coil connection seat is communicated with the magnetic isolation tube, and the coil connection seat and the magnetic isolation tube are both sleeved on the outer side of the armature.

[0008] It is further defined that the coil stop iron and the coil connecting seat are both made of soft magnetic alloy processed by a vacuum furnace; the thickness of the magnetic isolation tube is 1mm to 1.5mm, and the width of the magnetic isolation tube is 3mm to 4.5mm.

[0009] It is further defined that a high temperature resistant wire is welded to the connection terminal of the high temperature resistant coil, the high temperature resistant wire extends to the outside of the coil frame, and a heat shrink protective tube is provided on the outside of the welding position between the connection terminal of the high temperature resistant coil and the high temperature resistant wire.

[0010] It is further defined that the high temperature resistant coil and the coil frame are insulated by high temperature resistant silicone, and the high temperature resistant coil is vacuum dipped to eliminate pores.

[0011] It is further defined that a spring is arranged inside the armature and connected to the corresponding end of the spring, the other end of the spring is connected to the coil stop iron, the spring and the armature are coaxially arranged, and the armature and the coil connecting seat are coaxially arranged.

[0012] It is further defined that one end of the valve needle is located inside the coil connecting seat and close to the corresponding end face of the armature, the other end of the valve needle extends through the external oil return channel to the control channel, and the oil inlet pressure channel is opposite to the corresponding end face of the valve needle.

[0013] It is further defined that the external oil return channel is connected to the interior of the magnetic isolation tube and the interior of the coil connecting seat.

[0014] It is further defined that one end of the valve body is coaxially connected to the coil connecting seat, the other end of the valve body is connected to a filter screen, and the valve needle is coaxially connected to the valve body.

[0015] A control method for an oil-immersed micro solenoid valve is provided, based on the above-mentioned oil-immersed micro solenoid valve, and comprises the following steps: S1. Immerse the oil-immersed micro solenoid valve into the oil tank and install it at the corresponding position inside the oil tank through the mounting seat. The oil inlet pressure channel is connected to the pressure oil pipe, the control channel is connected to the control oil pipe, and the external oil return channel is connected to the oil tank; S2, determine whether the oil inlet pressure channel is connected to the control channel, if so, execute step S3, if not, execute step S4; S3, the high temperature resistant coil is energized, so that the armature is close to the coil stopper, and the pressure oil in the pressure oil pipe pushes the valve needle close to the armature. The valve needle cuts off the control channel and the external oil return channel, and opens the oil inlet pressure channel to connect it with the control channel; S4. The high temperature resistant coil is powered off, so that the armature pushes the valve needle close to the oil inlet pressure channel, separating the control channel from the oil inlet pressure channel, and opening the external oil return channel to connect it with the control channel.

[0016] The beneficial effects of the present invention are: 1. The present invention adjusts the working environment of the micro solenoid valve to oil immersion, thereby shortening the length of the external oil return channel in the radial direction, and there is no need to set an additional oil discharge channel for it to connect it with the external oil, which can not only reduce the size of the solenoid valve, but also reduce the production difficulty and production cost, and improve production efficiency; the valve needle and the armature have a split structure, so during production and installation, it is only necessary to ensure the coaxiality of the armature and the coil frame and the coaxiality of the valve needle and the valve body, which can ensure the movement control of the valve needle and the valve needle will not be displaced after the armature is heated and expanded, thereby ensuring the sealing effect and control reliability of the valve needle, improving the service life, reducing the installation and maintenance costs, and meeting the actual use needs.

[0017] 2. The present invention integrates the coil stop iron on the coil frame. On the one hand, it reduces the expansion coefficient of the all-metal coil frame to avoid damage to the high-temperature resistant coil due to the expansion of the coil frame in a high-temperature working environment, thereby increasing the working environment temperature and meeting the high-temperature working requirements; on the other hand, it reduces the volume of the coil frame and optimizes the structural design, which can further reduce the volume of the miniature solenoid valve and meet the use requirements of small size.

[0018] 3. The present invention utilizes the movement of the valve needle to achieve the sealing and opening of the oil inlet pressure channel. By increasing the elastic coefficient of the spring, when the high-temperature resistant coil is not energized, the spring pushes the valve needle through the armature to seal the oil inlet pressure channel, thereby increasing the sealing pressure of the oil inlet pressure channel and further improving the scope of application. By increasing the wire diameter of the high-temperature resistant coil and increasing the number of turns of the high-temperature resistant coil, it is ensured that the armature can compress the spring after the high-temperature resistant coil is energized, and the operation is reliable, further meeting the use requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the cross-sectional structure of the oil-immersed micro solenoid valve of the present invention; Figure 2 It is a schematic diagram of the cross-sectional structure of the coil skeleton of the present invention; Figure 3 It is a schematic cross-sectional structure diagram of the coil skeleton and the coil after being assembled in the present invention; Figure 4 It is a schematic diagram of the cross-sectional structure of the armature of the present invention; Figure 5This is a schematic diagram of the cross-sectional structure of the valve body of the present invention; In the figure, 10, coil skeleton; 11, coil stop iron; 12, magnetic isolation tube; 13, coil connecting seat; 14, first storage compartment; 20, high temperature resistant coil; 21, high temperature resistant wire; 22, heat shrink protection tube; 30, coil cover; 40, spring; 50, armature; 51, second storage compartment; 52, push rod; 60, valve needle; 61, steel ball; 70, mounting seat; 80, valve body; 81, filter; C, control channel; P, oil inlet pressure channel; R, external oil return channel. DETAILED DESCRIPTION

[0020] 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. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] refer to Figure 1 The present invention provides an oil-immersed micro solenoid valve, including a coil skeleton 10, a high temperature resistant coil 20, an armature 50, a valve needle 60 and a valve body 80, wherein the valve body 80 is provided with an external oil return channel R, a control channel C and an oil inlet pressure channel P in sequence, and the external oil return channel R is close to the coil skeleton 10.

[0022] The high temperature resistant coil 20 is sleeved on the outside of the coil skeleton 10, the valve body 80 is connected to one end of the coil skeleton 10, the armature 50 is arranged inside the coil skeleton 10, the armature 50 is elastically connected to the coil skeleton 10 through the spring 40, one end of the valve needle 60 extends to the inside of the valve body 80, and the other end of the valve needle 60 is close to the armature 50. The high temperature resistant coil 20 compresses the spring 40 when the armature 50 moves by power on / off control, so that the valve needle 60 is pushed by the oil to block the external oil return channel R, or the armature 50 is pushed close to the valve body 80 under the elastic action of the spring 40; when the armature 50 is pushed close to the valve body 80, the armature 50 pushes the valve needle 60 to move and block the oil inlet pressure channel P, completing the electromagnetic control.

[0023] To further illustrate, the external oil return channel R and the control channel C are both opened along the radial direction of the valve body 80, and the oil inlet pressure channel P is opened along the axial direction of the valve body 80. The external oil return channel R is directly connected to the external oil environment of the oil-immersed micro solenoid valve, and there is no need to open an additional oil drain channel separately. Only a simple oil return groove needs to be processed. While meeting the use requirements, it can reduce the processing difficulty and reduce the volume, thereby improving production efficiency and being able to adapt to smaller volume operations.

[0024] In order to further reduce the overall volume, the outer diameter of the armature 50 may be reduced, thereby further reducing the volume of the coil skeleton 10 .

[0025] To further explain, the valve needle 60 and the armature 50 are of segmented structure, that is, they are not directly connected, and when in use, the valve needle 60 is pushed to move by the armature 50, or the oil in the oil inlet pressure channel P pushes the valve needle 60 to move in the opposite direction.

[0026] By optimizing the structural design, on the one hand, the difficulty of assembling the valve needle 60 and the armature 50 can be reduced. On the other hand, the armature 50 can be prevented from being deformed due to heat, which may affect the assembly reliability of the valve needle 60, and the friction between the valve needle 60 and the external structure during movement, which may reduce the service life and affect the control accuracy and reliability, thereby meeting actual use requirements.

[0027] Example 1 refer to Figure 1 and Figure 2 In the oil-immersed micro solenoid valve provided in this embodiment, the coil skeleton 10 includes a coil stop iron 11, a magnetic isolation tube 12 and a coil connecting seat 13 which are connected in sequence.

[0028] The outside of the coil connection seat 13 is preferably sleeved with a mounting seat 70 for connecting with an external structure to ensure stable and reliable operation; the mounting seat 70 is on the outside of the high temperature resistant coil 20 and is close to the valve body 80 .

[0029] A first placement bin 14 is provided inside the coil connecting seat 13, and the first placement bin 14 is connected to the interior of the magnetic isolation tube 12. Preferably, the inner diameter of the magnetic isolation tube 12 is the same as the outer diameter of the first placement bin 14. The inner end face of the coil stop iron 11 extends to the interior of the magnetic isolation tube 12 and is tightly connected to the magnetic isolation tube 12. The inner end face of the coil stop iron 11 is opposite to the first placement bin 14.

[0030] During the processing, the coil stop iron 11, the magnetic isolation tube 12 and the coil connecting seat 13 are matched to ensure the consistency of the outer circle size and the interference size. The coil stop iron 11 and the coil connecting seat 13 are made of soft magnetic alloy and processed in a vacuum furnace to increase their magnetic permeability. During installation, the coil stop iron 11 and the magnetic isolation tube 12 are tightly fitted and pressed, and the magnetic isolation tube 12 and the coil connecting seat 13 are tightly fitted and pressed, which effectively ensures the coaxiality between the inner hole of the magnetic isolation tube 12 and the first placement bin 14.

[0031] Preferably, laser welding technology is used to weld the connection position between the coil stop iron 11 and the magnetic isolation tube 12, as well as the connection position between the magnetic isolation tube 12 and the coil connecting seat 13. The welding depth is controlled to be 0.5mm~0.8mm. Laser welding technology can fuse two different materials and effectively ensure the strength of the weld.

[0032] For example, the wall thickness of the magnetic isolation tube 12 can be selected to be 1 mm to 1.5 mm, and the width can be 3 mm to 4.5 mm, so as to ensure flexible and rapid movement of the armature 50 when the power is repeatedly turned on and off.

[0033] The coil stop iron 11 is integrated with the coil frame 10, so that the coil frame 10 is made of all-metal material. Its thermal expansion coefficient is low and the thermal expansion change is small in a high-temperature environment. Therefore, it can operate stably in a high-temperature environment, avoiding damage to the high-temperature resistant coil 20 caused by squeezing due to thermal expansion, meeting high-temperature operation requirements and ensuring its service life.

[0034] refer to Figure 1 and Figure 3 , further explained, a first retaining ring is arranged on the coil stop iron 11, the first retaining ring is close to the outer end surface of the coil stop iron 11, and a second retaining ring is arranged on the coil connecting seat 13, the second retaining ring is close to the valve body 80. At this time, the high temperature resistant coil 20 is sleeved on the outer side of the coil stop iron 11, the outer side of the magnetic isolation tube 12 and the outer side of the coil connecting seat 13, and the high temperature resistant coil 20 is located between the first retaining ring and the second retaining ring.

[0035] At this time, the mounting seat 70 is sleeved on the outside of the second retaining ring, and at the same time, the coil cover 30 is sleeved on the outside of the high temperature resistant coil 20, one end of the coil cover 30 is sleeved on the outside of the first retaining ring and flush with the end face of the first retaining ring, and the other end of the coil cover 30 is sleeved on the outside of the second retaining ring and contacts the mounting seat 70, forming a complete magnetic field through the coil cover 30.

[0036] A wire hole is opened on the first retaining ring so that the terminal of the high temperature resistant coil 20 can be connected to the high temperature resistant wire 21 passing through the wire hole. The high temperature resistant wire 21 is limited by the wire hole to prevent the high temperature resistant wire 21 from shaking frequently and reducing the reliability of the connection with the terminal of the high temperature resistant coil 20.

[0037] The high temperature resistant wire 21 and the high temperature resistant coil 20 can be connected by welding. In order to improve the reliability of the connection, it is preferred to sleeve a heat shrink protective tube 22 on the outside of the high temperature resistant wire 21, so that the heat shrink protective tube 22 is sleeved on the welding position of the high temperature resistant wire 21 and the high temperature resistant coil 20, thereby improving its service life.

[0038] When installing the high temperature resistant coil 20, it is preferred to spray the contact position between the high temperature resistant coil 20 and the coil frame 10 with high temperature resistant silicone insulating paint, and then use enameled wire to wind it at the corresponding position of the coil frame 10. After the winding is completed, the high temperature resistant coil 20 is vacuum dipped in paint to ensure that the interior of the high temperature resistant coil 20 is fully dipped in paint to avoid the presence of pores. While ensuring insulation, it is also possible to avoid the high temperature resistant coil 20 from being damaged by explosion due to the expansion of the pores due to heat and squeezing the enameled wire or the excessive air pressure in the pores, thereby further increasing the operating temperature of the high temperature resistant coil 20 to meet actual operating requirements.

[0039] Example 2 refer to Figure 1 and Figure 4 In the oil-immersed micro solenoid valve provided in this embodiment, the armature 50 is elastically connected to the coil skeleton 10 through the spring 40.

[0040] Specifically, a second placement bin 51 is opened inside one side of the armature 50, and a push rod 52 is connected to the other side of the armature 50. The push rod 52 is tightly connected to the armature 50. The hole in the armature 50 for placing the push rod 52 is connected to the second placement bin 51, so that the air can be discharged in time when the push rod 52 is connected to the armature 50.

[0041] Preferably, the second placing bin 51 is coaxially arranged with the armature 50, and the axial length of the second placing bin 51 is smaller than the axial length of the armature 50. During installation, the second placing bin 51 is sleeved on the outside of the spring 40 and connected to one end of the spring 40, and the corresponding end of the spring 40 is in direct contact with the corresponding end of the second placing bin 51; the other end of the spring 40 is connected to the inner end face of the coil stop iron 11, and a moving gap is reserved between the armature 50 and the inner end face of the coil stop iron 11.

[0042] When the high temperature resistant coil 20 is not energized, the spring 40 is compressed. At this time, the spring 40 pushes the armature 50 to move to the valve needle 60 and seals and contacts the port of the oil inlet pressure channel P, thereby blocking the oil inlet pressure channel P and disconnecting it from the control channel C. At the same time, after the valve needle 60 moves, the external oil return channel R is connected to the control channel C. At this time, the elastic force of the spring 40 is not less than the oil pressure in the oil inlet pressure channel P, thereby ensuring accurate and reliable control.

[0043] After the high temperature resistant coil 20 is energized, the armature 50 moves to reduce the moving gap between it and the inner end face of the coil stop iron 11, the spring 40 is further compressed, and the push rod 52 moves away from the end of the valve needle 60. The valve needle 60 cannot offset the oil pressure in the oil inlet pressure channel P by relying on the friction between it and the valve body 80. At this time, the valve needle 60 is pushed in the opposite direction to block the passage between the external oil return channel R and the control channel C. At this time, the oil inlet pressure channel P is connected with the control channel C, and the corresponding end of the valve needle 60 is in contact with or close to the push rod 52, that is, the valve needle 60 blocks the passage between the external oil return channel R and the control channel C under the action of the oil pressure in the oil inlet pressure channel P, thereby meeting the actual control requirements.

[0044] It is further explained that the thrust of the valve needle 60 can be adjusted by adjusting the thickness of the push rod 52 and the compression length of the spring 40 when the high-temperature resistant coil 20 is not energized, so as to cope with the use requirements of different oil pressures in the oil inlet pressure channel P. At the same time, the elastic coefficient of the spring 40 can be increased to increase the pressure of the working environment and further improve the applicability requirements.

[0045] It is further explained that the valve needle 60 and the armature 50 adopt a split structure, so that the friction between the armature 50 and the external structure and the friction between the valve needle 60 and the valve body 80 are unrelated, thereby reducing the coaxiality requirements between the valve body 80 and the coil skeleton 10, reducing the coaxiality requirements between the valve needle 60 and the armature 50, reducing the difficulty of assembly, and improving assembly efficiency; at the same time, during operation, the end face area of ​​the push rod 52 is increased to ensure reliable contact between the valve needle 60 and the push rod 52, so that the deformation of the armature 50 in a high temperature environment will not affect the installation reliability between the valve needle 60 and the valve body 80, further ensuring stable and reliable control to meet the working requirements of high temperature, high pressure and small size.

[0046] Example 3 refer to Figure 1 and Figure 5 In the oil-immersed micro solenoid valve provided in this embodiment, a steel ball 61 is provided at one end of the valve needle 60 close to the oil inlet pressure channel P, the valve needle 60 is coaxially arranged with the valve body 80, and the connecting end of the valve body 80 is connected to the coil connecting seat 13. Preferably, the valve body 80 is coaxially arranged with the coil connecting seat 13; the first oil channel, the second oil channel and the third oil channel are sequentially opened in the valve body 80.

[0047] Specifically, the first oil channel is coaxially arranged with the valve body 80, one end of the first oil channel is connected with the first placement chamber 14, the other end of the first oil channel is connected with the second oil channel, and at the same time, the external oil return channel R is connected with the first oil channel, so that the external oil of the oil-immersed micro solenoid valve can flow into the interior of the coil skeleton 10 through the first oil channel; the valve needle 60 is arranged along the first oil channel, the inner diameter of the first oil channel is larger than the outer diameter of the valve needle 60, and the gap between the inner wall of the first oil channel and the outer wall of the valve needle 60 is about 0.05mm~0.06mm, and at this time the steel ball 61 extends to the second oil channel.

[0048] The second oil channel is preferably coaxially arranged with the valve body 80. While the second oil channel is connected to the oil inlet pressure channel P through the third oil channel, the second oil channel is also connected to the control channel C. The inner diameter of the port connecting the second oil channel to the first oil channel is smaller than the outer diameter of the steel ball 61, the inner diameter of the port connecting the second oil channel to the third oil channel is smaller than the outer diameter of the steel ball 61, and the middle position of the second oil channel is larger than the outer diameter of the steel ball 61.

[0049] When the valve needle 60 moves left and right along the axis of the valve body 80, the valve needle 60, under the push of the spring 40, makes the steel ball 61 press against the port connecting the second oil channel and the third oil channel. At this time, the control channel C is connected to the external oil return channel R through the first oil channel; or the valve needle 60, under the action of the hydraulic oil in the oil inlet pressure channel P, the steel ball 61 presses against the port connecting the second oil channel and the first oil channel. At this time, the control channel C is connected to the oil inlet pressure channel P through the third oil channel.

[0050] The external oil return channel R is close to the outer end of the valve body 80, and the external oil return channel R is connected to the pressure oil pipe. Preferably, a filter 81 is set at the outer end of the valve body 80. The filter 81 is detachably connected to the valve body 80. The filter 81 can be optionally a spherical structure. A plurality of filter holes with an inner diameter of 0.1 mm are opened in an array on the filter 81 by laser to ensure effective filtration while avoiding blockage.

[0051] Example 4 Based on the oil-immersed micro solenoid valves provided in Examples 1 to 3, this embodiment provides a method for controlling an oil-immersed micro solenoid valve, comprising the following steps: S1. Immerse the oil-immersed micro solenoid valve into the oil tank and install it at the corresponding position inside the oil tank through the mounting seat 70. The oil inlet pressure channel P is connected to the pressure oil pipe, the control channel C is connected to the control oil pipe, and the external oil return channel R is connected to the oil tank; S2, determine whether the oil inlet pressure channel P is connected to the control channel C, if so, execute step S3, if not, execute step S4; S3, the high temperature resistant coil 20 is energized, so that the armature 50 is close to the coil stopper 11, and the pressure oil in the pressure oil pipe pushes the valve needle 60 to approach the armature 50, and the valve needle 60 cuts off the control channel C and the external oil return channel R, and opens the oil inlet pressure channel P to make it communicate with the control channel C; S4, the high temperature resistant coil 20 is powered off, so that the armature 50 pushes the valve needle 60 to approach the oil inlet pressure channel P, cuts off the control channel C from the oil inlet pressure channel P, and opens the external oil return channel R to connect it with the control channel C.

[0052] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some or all of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the present invention.

Claims

1. An oil-immersed micro solenoid valve, characterized in that: The valve body (80) comprises a coil frame (10), a high temperature resistant coil (20), an armature (50), a valve needle (60) and a valve body (80), wherein the high temperature resistant coil (20) is sleeved on one side of the coil frame (10), the armature (50) is arranged inside the coil frame (10) and is elastically connected to the coil frame (10), one end of the valve needle (60) is close to the armature (50), and the other end of the valve needle (60) extends into the valve body (80), and the valve body (80) is connected to the coil frame (10); The valve body (80) is provided with an external oil return channel (R), a control channel (C) and an oil inlet pressure channel (P) in sequence, and the external oil return channel (R) and the control channel (C) are both opened along the radial direction of the valve body (80); the oil inlet pressure channel (P) is opened along the axial direction of the valve body (80), and the external oil return channel (R) is connected to the oil inlet pressure channel (P) through the control channel (C); The valve needle (60) reciprocates along the axial direction of the valve body (80) to adjust the external oil return channel (R) to communicate with the control channel (C), or the control channel (C) to communicate with the oil inlet pressure channel (P).

2. The oil-immersed micro solenoid valve according to claim 1, characterized in that: The coil frame (10) comprises a coil stop iron (11), a magnetic isolation tube (12) and a coil connection seat (13) which are connected in sequence, the coil stop iron (11) and the coil connection seat (13) are tightly connected to the magnetic isolation tube (12), and the coil stop iron (11), the magnetic isolation tube (12) and the coil connection seat (13) are coaxially connected, the outer side of the coil connection seat (13) is sleeved with a mounting seat (70), and the high temperature resistant coil (20) is sleeved between the outer end surface of the coil stop iron (11) and the mounting seat (70); The coil connection seat (13) is in communication with the magnetic isolation tube (12), and the coil connection seat (13) and the magnetic isolation tube (12) are both sleeved on the outside of the armature (50).

3. The oil-immersed micro solenoid valve according to claim 2, characterized in that: The coil stop iron (11) and the coil connection seat (13) are both made of a soft magnetic alloy processed by a vacuum furnace; the thickness of the magnetic isolation tube (12) is 1 mm to 1.5 mm, and the width of the magnetic isolation tube (12) is 3 mm to 4.5 mm.

4. The oil-immersed micro solenoid valve according to claim 2, characterized in that: A high temperature resistant wire (21) is welded to the connection end of the high temperature resistant coil (20), the high temperature resistant wire (21) extends to the outside of the coil frame (10), and a heat shrink protection tube (22) is provided on the outside of the welding position between the connection end of the high temperature resistant coil (20) and the high temperature resistant wire (21).

5. The oil-immersed micro solenoid valve according to claim 4, characterized in that: The high temperature resistant coil (20) and the coil frame (10) are insulated by high temperature resistant silicone, and the high temperature resistant coil (20) is vacuum dipped to eliminate pores.

6. The oil-immersed micro solenoid valve according to any one of claims 2 to 5, characterized in that: A spring (40) is arranged inside the armature (50) and is connected to a corresponding end of the spring (40); the other end of the spring (40) is connected to a coil stop iron (11); the spring (40) and the armature (50) are coaxially arranged; and the armature (50) and the coil connection seat (13) are coaxially arranged.

7. The oil-immersed micro solenoid valve according to claim 6, characterized in that: One end of the valve needle (60) is located inside the coil connection seat (13) and close to the corresponding end face of the armature (50), and the other end of the valve needle (60) extends through the external oil return channel (R) to the control channel (C), and the oil inlet pressure channel (P) is opposite to the corresponding end face of the valve needle (60).

8. The oil-immersed micro solenoid valve according to claim 7, characterized in that: The external oil return channel (R) is in communication with the interior of the magnetic isolation tube (12) and the interior of the coil connection seat (13).

9. The oil-immersed micro solenoid valve according to claim 8, characterized in that: One end of the valve body (80) is coaxially connected to the coil connection seat (13), the other end of the valve body (80) is connected to a filter screen (81), and the valve needle (60) is coaxially connected to the valve body (80).

10. A control method for an oil-immersed micro solenoid valve, characterized in that: The oil-immersed micro solenoid valve according to claim 8 comprises the following steps: S1. Immerse the oil-immersed micro solenoid valve in the oil tank and install it at a corresponding position inside the oil tank through a mounting seat (70), wherein the oil inlet pressure channel (P) is connected to the pressure oil pipe, the control channel (C) is connected to the control oil pipe, and the external oil return channel (R) is connected to the oil tank; S2, determine whether the oil inlet pressure channel (P) is connected to the control channel (C), if so, execute step S3, if not, execute step S4; S3, the high temperature resistant coil (20) is energized, so that the armature (50) is close to the coil stopper (11), and the pressure oil in the pressure oil pipe pushes the valve needle (60) close to the armature (50), and the valve needle (60) isolates the control channel (C) from the external oil return channel (R), and opens the oil inlet pressure channel (P) to make it communicate with the control channel (C); S4, the high temperature resistant coil (20) is de-energized, so that the armature (50) pushes the valve needle (60) close to the oil inlet pressure channel (P), thereby isolating the control channel (C) from the oil inlet pressure channel (P), and opening the external oil return channel (R) to connect it with the control channel (C).

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