Ultra-clean differential solenoid valve with low power consumption

Abstract

The present invention discloses a low-power ultra-clean differential solenoid valve. The valve cover and the valve seat are tightly assembled to form an ultra-clean flow chamber, and the ultra-clean flow chamber has inlet and outlet flow paths; an ultra-clean valve core is arranged inside, and the outer walls of the valve cover outside the top and bottom of the ultra-clean flow chamber are respectively installed with an outer upper layer of permanent magnets and an outer lower layer of permanent magnets; an actuating coil is sleeved on the outer wall of the valve cover between the outer upper layer of permanent magnets and the outer lower layer of permanent magnets, and a valve core displacement sensor is sleeved on the outer side of the fixed sleeve, and the valve core displacement sensor is used to detect the axial position of the ultra-clean valve core in the ultra-clean flow chamber in real time. The present invention is energized only when the opening is maintained, which solves the problem that the current in the coil-driven ultra-clean solenoid valve is large, the heat is serious, and the temperature rise of the ultra-clean medium is too high, and the power consumption of the coil-type ultra-clean solenoid valve is reduced.

Description

Technical Field

[0001] The invention relates to a solenoid valve in the field of valve technology, and in particular to a low-power solenoid valve suitable for ultra-clean occasions. Background Art

[0002] Semiconductors, biomedicine, electronic-grade chemicals and other fields are very sensitive to pollutants such as particles and ions, and have very high cleanliness requirements for liquids or gases required for production processes. Materials or processes that meet certain cleanliness standards are called ultra-clean materials or ultra-clean processes. Flow control components that transport ultra-clean fluid media must strictly prevent the internal media from communicating with the outside world, be safe, reliable and corrosion-resistant, and at the same time, no wear and particulate matter should be generated during the opening and closing process of the valve itself.

[0003] In areas where ultra-clean fluids or corrosive fluids need to be transported and controlled, ultra-clean solenoid valves are often used as the basic components of ultra-clean fluid control. Traditional solenoid valves are usually equipped with external control parts such as valve stems, which makes it difficult to eliminate dynamic sealing points in principle and easily cause external leakage during long-term and multiple opening and closing processes. In addition, traditional solenoid valves often use metal elastic elements (such as return springs), which will pollute the entire ultra-clean environment. If non-metallic elastic elements (such as polytetrafluoroethylene PTFE springs) are used, there are problems such as insufficient rigidity, difficulty in manufacturing, and short service life.

[0004] In this regard, the common measure in the industry is to use an electric diaphragm valve (see patents WO2007089689A2, CN101365904A, CN1836124A, US20030722168 for details). The motor drives the elastic flexible element to deform to realize the opening and closing of the valve port and the opening control. The flexible element diaphragm is used as a seal to completely isolate the drive device such as the outer valve stem from the flow channel, ensuring the clean characteristics of the fluid. However, there are problems such as the diaphragm is prone to fatigue rupture and the control response speed is slow. The Chinese invention with application number CN202011163914.1 provides an ultra-clean proportional electric valve, which uses the minimum magnetic resistance principle to open and close the valve port, and can achieve precise control of the valve port position; but compared with the electromagnetic coil drive form, there are problems such as large overall structure volume and slow control response speed of the valve port.

[0005] Compared with electric valves driven by motors, solenoid valves driven by coils have advantages such as compact structure and rapid control response. However, one of the important factors restricting the application of coil-driven solenoid valves in the field of ultra-clean flow control is that due to the limitations of ultra-clean characteristics, the armature air gap of ultra-clean solenoid valves is larger than that of traditional solenoid valves, resulting in a larger coil current required to maintain the valve core position and more severe heat generation, which will change the temperature of the ultra-clean fluid medium, resulting in the solenoid valve solutions driven by coils being rarely used in the field of ultra-clean flow control. Summary of the invention

[0006] In order to overcome the deficiencies of the above-mentioned prior art, the present invention provides a low-power ultra-clean differential solenoid valve, which solves the problem that the current in the coil-driven ultra-clean solenoid valve is large, the heat is serious and the temperature rise of the ultra-clean medium is too high, and the power consumption of the coil-driven ultra-clean solenoid valve is reduced.

[0007] The technical solution adopted by the present invention is:

[0008] The invention comprises a permanent magnet, an actuating coil, a valve core displacement sensor and an ultra-clean valve core; wherein a valve cover and a valve seat made of ultra-clean material are tightly assembled and enclosed internally to form an ultra-clean flow chamber, wherein the ultra-clean flow chamber has an inlet flow path and an outlet flow path connected to an external environment; an ultra-clean valve core is arranged inside the ultra-clean flow chamber, the ultra-clean valve core is located just above the position of the inlet flow path outlet at the top surface of the valve seat, the ultra-clean valve core can move along the axial direction of the ultra-clean flow chamber in the ultra-clean flow chamber, and an annular outer upper layer permanent magnet and an outer lower layer permanent magnet are respectively installed on the outer wall of the valve cover outside the top and bottom of the ultra-clean flow chamber; an actuating coil is sleeved on the outer wall of the valve cover between the outer upper layer permanent magnet and the outer lower layer permanent magnet, a fixing sleeve is sleeved outside the actuating coil for packaging, and a valve core displacement sensor is sleeved outside the fixing sleeve.

[0009] The ultra-clean valve core comprises an annular body, a block body, an embedded permanent magnet, a connecting arm and an outer layer of ultra-clean material coating; the annular body is located above the block body, an annular cavity is provided in the annular body, an embedded permanent magnet is embedded in the annular cavity, a flow hole is opened in the annular body, a gap in the up and down directions is provided between the annular body and the block body, the annular body and the block body are tightly connected by a plurality of connecting arms arranged at intervals along the circumferential direction around them, the interior of the annular body is arranged as a hollow structure with an annular cavity, and the interior of the block body is solid.

[0010] The top surface of the valve seat is provided with a convex surface as a sealing boss at the outlet end of the inlet flow path, and the bottom surface of the ultra-clean valve core is provided with an inner concave surface as an annular sealing surface. The sealing boss and the annular sealing surface are correspondingly embedded in line.

[0011] The valve core displacement sensor includes but is not limited to LVDT sensor and LDC sensor.

[0012] The valve core displacement sensor adopts an LVDT sensor, including an LVDT secondary winding and an LVDT primary winding; two LVDT secondary windings and one LVDT primary winding are arranged outside the fixed sleeve, the LVDT primary winding is arranged in the middle, and the LVDT secondary windings are arranged on the upper and lower sides of the LVDT primary winding respectively; a winding shell is set outside the LVDT secondary winding and an LVDT primary winding.

[0013] The valve core displacement sensor 0 adopts an LDC sensor, including an external fixed shell and an LDC sensor. The LDC sensor is provided on one side surface outside the fixed sleeve. The LDC sensor is a sensor coil, which is arranged in a planar spiral. The coil density on one side of the sensor coil is lower than the coil density on the other symmetrical side. The LDC sensor is encapsulated by an external fixed shell.

[0014] The outer upper layer permanent magnet, the outer lower layer permanent magnet, and the embedded permanent magnet of the ultra-clean valve core have the same magnetization direction, which is along the up-down direction, and the same magnetic arrangement direction.

[0015] The static magnetic adsorption of the ultra-clean valve core is controlled by the outer upper permanent magnet and the outer lower permanent magnet. The ultra-clean valve core moves and positions in the axial direction of the ultra-clean flow chamber in the up and down directions by the power supply of the actuating coil and the current size, and the spacing between the ultra-clean valve core and the inlet flow path is adjusted, thereby adjusting the opening of the ultra-clean differential solenoid valve. The larger the spacing between the ultra-clean valve core and the inlet flow path, the smaller the flow resistance and the larger the opening.

[0016] The valve cover, valve seat, annular body, block body and connecting arm of the ultra-clean valve core are all made of ultra-clean materials.

[0017] The embedded permanent magnet is embedded in an annular permanent magnet of ultra-clean material during the injection molding process, or coated or wrapped with ultra-clean material to form an ultra-clean valve core. To ensure ultra-clean properties, all walls in contact with the fluid are made of ultra-clean materials.

[0018] The ultra-clean material is a fluorine-containing plastic, including perfluoroalkoxy, polytetrafluoroethylene or polyvinylidene fluoride, or any combination thereof.

[0019] The embedded permanent magnet needs to be metal plated during manufacturing, and a metal film with a thickness of at least micrometer level exists on its surface.

[0020] The ultra-clean differential solenoid valve is used for ultra-clean fluid transmission and control in the fields of semiconductors, biomedicine, electronic-grade chemicals, etc.

[0021] The ultra-clean differential solenoid valve of the present invention can be used for ultra-clean fluid transmission and control in the fields of semiconductors, biomedicine, electronic-grade chemical industry, etc.

[0022] LVDT refers to Linear Variable Differential Transformer and LDC refers to Inductive Transducer.

[0023] The beneficial effects of the present invention are:

[0024] Through analysis and experiments on the maintaining force required for the valve core in different positions, the present invention finds that in engineering practice, the static pressure on the valve core sealing fluid when closed is one order of magnitude higher than the fluid impact force on the valve core to maintain a fixed position when open. When closed and sealed, the coil current required is the largest and the heat generation is the most serious.

[0025] The valve uses two permanent magnets to construct a symmetrical magnetic circuit, changes the force on the valve core by controlling the current of the energized coil, relies on the valve core position sensor to detect the valve core position, and adjusts the coil current to compensate for the magnetic differential momentum caused by the valve core position deviation, thereby controlling the position of the valve core and realizing the valve opening and closing and opening functions.

[0026] Since the magnetic force required to adjust the opening is several orders of magnitude smaller than the magnetic force required to complete the sealing closure, and the ultra-clean solenoid valve with a differential magnetic circuit relies only on the magnetic force of the permanent magnet to seal when closed, the coil only needs to be energized to maintain the opening. Therefore, this invention solves the problem of large current and severe heat generation in the coil-driven ultra-clean solenoid valve, resulting in excessive temperature rise of the ultra-clean medium, and reduces the power consumption of the coil-type ultra-clean solenoid valve. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a structural schematic diagram of an open state of an embodiment of the present invention;

[0028] Figure 2 Schematic diagram of an ultra-clean valve core according to an embodiment of the present invention; (a) is a stereoscopic diagram of the ultra-clean valve core, and (b) is a cross-sectional view of the ultra-clean valve core;

[0029] Figure 3 It is a structural schematic diagram of a closed state of an embodiment of the present invention;

[0030] Figure 4 This is a schematic diagram of the valve core position detection principle based on LVDT according to an embodiment of the present invention;

[0031] Figure 5 It is a schematic diagram of the valve core position detection principle based on LDC according to an embodiment of the present invention.

[0032] Figure 6 Schematic diagram of the wiring of the LDC sensor in an embodiment of the present invention.

[0033] In the figure, 1: discharge flow path; 2: valve cover; 3: ultra-clean flow chamber; 4: outer upper permanent magnet; 5: fixing sleeve; 6: actuating coil; 7: outer lower permanent magnet; 8: threaded sealing surface; 9: valve seat; 10: flow hole; 11: embedded permanent magnet; 12: ultra-clean coating; 13: connecting arm; 14: annular sealing surface; 15: ultra-clean valve core; 16: sealing boss; 17: inlet flow path; 18: LVDT secondary winding; 19: LVDT primary winding; 20: valve core displacement sensor; 21: outer shell; 22: outer fixing shell; 23: LDC sensor. DETAILED DESCRIPTION

[0034] The present invention is further described below in conjunction with the accompanying drawings and embodiments:

[0035] like Figure 1 As shown, the valve structure includes a valve seat 9, a valve cover 2, two permanent magnets 4, 7 and an actuating coil 6, a valve core displacement sensor 20, and an ultra-clean valve core 15; the valve cover 2 is cylindrical and is installed on the valve seat 9. The valve cover 2 and the valve seat 9 made of ultra-clean materials are tightly assembled and enclosed internally to form an ultra-clean flow chamber 3. The axial direction of the ultra-clean flow chamber 3 is arranged along the vertical direction. The ultra-clean flow chamber 3 has an inlet flow path 17 and an outlet flow path 1 connected to the external environment; in a specific implementation, a through hole connecting the outside world and the ultra-clean flow chamber 3 is provided at the top of the valve cover 2 as the outlet flow path 1, and a channel connecting the outside world and the ultra-clean flow chamber 3 is provided in the bottom end of the valve seat 9 as the inlet flow path 17. The fluid enters the ultra-clean flow chamber 3 through the inlet flow path 17 and is discharged from the ultra-clean flow chamber 3 through the outlet flow path 1.

[0036] An ultra-clean valve core 15 is arranged inside the ultra-clean flow chamber 3. The ultra-clean valve core 15 is located just above the top surface of the valve seat 9 at the outlet of the inlet flow path 17. The ultra-clean valve core 15 can move in the axial direction of the ultra-clean flow chamber 3 in the ultra-clean flow chamber 3. The outer walls of the valve cover 2 outside the top and bottom of the ultra-clean flow chamber 3 are respectively installed with an annular outer upper permanent magnet 4 and an outer lower permanent magnet 7. The outer upper permanent magnet 4 and the outer lower permanent magnet 7 have the same magnetization direction and strength and are arranged at the upper and lower parts of the outer wall of the valve cover 2; the outer wall of the valve cover 2 between the outer upper permanent magnet 4 and the outer lower permanent magnet 7 is sleeved with an actuating coil 6, and the actuating coil 6 is packaged with a fixed sleeve 5, and the fixed sleeve 5 is sleeved with a valve core displacement sensor 20, which is arranged on the outside of the valve cover, and the valve core displacement sensor 20 is used to detect the axial position of the ultra-clean valve core 15 in the ultra-clean flow chamber 3 in real time.

[0037] like Figure 2As shown, the ultra-clean valve core 15 includes an annular body, a block body, an embedded permanent magnet 11, a connecting arm 13 and an outer ultra-clean material coating layer 12; the annular body is located above the block body, and a closed annular cavity is provided in the annular body, and the embedded permanent magnet 11 is embedded in the annular cavity. The annular body outside the embedded permanent magnet 11 forms an ultra-clean coating layer 12 for the embedded permanent magnet 11. The embedded permanent magnet 11 is embedded in the ultra-clean coating layer 12 by injection molding, that is, it is ensured that the permanent magnet does not contact the conveying medium. The annular body is provided with a flow hole 10, and there is a gap in the up and down directions between the annular body and the block body. The annular body and the block body are tightly connected by a plurality of connecting arms 13 arranged circumferentially at intervals around them. The connecting arm 13 is L-shaped, and the interior of the annular body is arranged as a hollow structure with an annular cavity, and the interior of the block body is solid; the annular body and the block body are both non-magnetic conductive materials. The valve cover 2, the valve seat 9, and the annular body, the block body and the connecting arm 13 of the ultra-clean valve core 15 are all made of ultra-clean materials.

[0038] The flow hole 10 formed in the annular body with the embedded permanent magnet 11 is located in the center of the ultra-clean valve core 15, which plays the role of renewing the fluid and balancing the pressure difference. The inlet and outlet flow paths are opened at the upper and lower ends of the ultra-clean flow chamber, and the fluid flow in the ultra-clean flow chamber is renewed without flow dead zones.

[0039] The fluid entering the ultra-clean flow chamber 3 below the ultra-clean valve core 15 passes through the gap between the annular body and the block body and the flow hole 10 in sequence and then enters the ultra-clean flow chamber 3 above the ultra-clean valve core 15 .

[0040] The number of connecting arms 13 is preferably 3-4, which are evenly distributed around the annular body and the block body along the circumference.

[0041] The top surface of the valve seat 9 is provided with a raised surface as a sealing boss 16 at the outlet end of the inlet flow path 17, and the block bottom surface of the ultra-clean valve core 15 is provided with an inner concave surface as an annular sealing surface 14, and the sealing boss 16 and the annular sealing surface 14 are correspondingly embedded in line; the annular sealing surface 14 can fit tightly with the sealing boss 16 and block the flow path, and when the sealing boss 16 is embedded in the annular sealing surface 14, the ultra-clean valve core 15 is sealed and installed on the valve seat 9 to block the inlet flow path 17.

[0042] The actuating coil 6 is energized, and the actuating coil has a current regulation function, and regulates currents of different intensities according to the feedback amount of the valve core position to generate magnetic fields of different intensities.

[0043] According to the position of the valve core, currents of different strengths are passed through the actuating coil 6 to generate magnetic fields of different strengths, thereby generating driving forces of different sizes on the ultra-clean valve core 15 in the ultra-clean flow chamber 3, realizing non-contact control of the valve core movement, and realizing valve opening and closing, sealing and opening control while ensuring the ultra-clean characteristics of the fluid medium.

[0044] The valve core displacement sensor is arranged on the outside of the valve cover and connected to the actuating coil. The valve core displacement sensor detects the ultra-clean valve core position at all times, compares it with the target value set for the ultra-clean valve core position, and feeds back the output to the actuating coil, which then controls the movement and position of the ultra-clean valve core 15 in a closed-loop manner.

[0045] The outer upper permanent magnet 4 , the outer lower permanent magnet 7 , and the embedded permanent magnet 11 of the ultra-clean valve core 15 have the same magnetization direction, which is along the up-and-down direction parallel to the axial direction of the ultra-clean flow chamber 3 , and the magnetic arrangement direction is the same.

[0046] exist Figure 1 In the figure, the outer upper permanent magnet 4 and the outer lower permanent magnet 7 have the same magnetization direction and strength. The symmetry line of the upper and lower positions of the two is in the working range of the valve core. The embedded permanent magnet and the external permanent magnet have the same magnetization direction and work by suction.

[0047] When the valve core embedded permanent magnet 11 is located in the middle between the outer upper permanent magnet 4 and the outer lower permanent magnet 7, the magnetic forces of the outer upper permanent magnet 4 and the outer lower permanent magnet 7 on the embedded permanent magnet 11 cancel each other out, or the remaining force is very small;

[0048] When the valve is in the closed state, Figure 3 As shown, the ultra-clean valve core 15 is affected by gravity. At this time, the sealing is completed only by the magnetic attraction between the outer lower layer permanent magnet 7 and the embedded permanent magnet 11. The actuating coil 6 does not need to be energized. The magnetic force required for the valve core sealing is one or two orders of magnitude larger than the magnetic force required for adjusting the opening. Not energizing when closed greatly reduces power consumption.

[0049] The magnetic attraction force of the outer upper layer permanent magnet 4 and the outer lower layer permanent magnet 7 on the embedded permanent magnet 11 in the ultra-clean valve core 15 is smaller than the gravity of the ultra-clean valve core 15 .

[0050] When the valve is in the open position, Figure 4 As shown, the actuating coil 6 is energized to generate a magnetic field, driving the embedded permanent magnet 11 in the ultra-clean valve core 15 to rise, so that the ultra-clean valve core 15 is separated from the outlet of the inlet flow path 17 on the top surface of the valve seat 9, thereby opening the valve.

[0051] The current flowing through the actuating coil 6 increases, driving the embedded permanent magnet 11 in the ultra-clean valve core 15 to rise, so that the distance between the ultra-clean valve core 15 and the inlet flow path 17 increases, and the opening degree increases.

[0052] The valve core displacement sensor in the specific implementation includes but is not limited to LVDT sensor and LDC sensor.

[0053] like Figure 3 and Figure 4As shown, a valve core displacement sensor 20 in one embodiment adopts an LVDT sensor, including an LVDT secondary winding 18 and an LVDT primary winding 19; two LVDT secondary windings 18 and one LVDT primary winding 19 are arranged outside the fixed sleeve 5, the LVDT primary winding 19 is arranged in the middle, and the LVDT secondary windings 18 are arranged on the upper and lower sides of the LVDT primary winding 19 respectively; the LVDT secondary winding 18 and one LVDT primary winding 19 are covered with a winding shell 21, and the winding shell 21 is passed through.

[0054] like Figure 5 and Figure 6 As shown, another embodiment of the valve core displacement sensor 20 adopts an LDC sensor, including an outer fixed shell 22 and an LDC sensor 23. The LDC sensor 23 is provided on one side surface outside the fixed sleeve 5. The LDC sensor 23 is a sensor coil, and the sensor coil is arranged in a planar spiral. The coil density on one side of the sensor coil is lower than the coil density on the other side of the symmetry, that is, the spacing between the coils on one side of the sensor coil is lower than the spacing between the coils on the other side of the symmetry. The LDC sensor 23 is encapsulated by the outer fixed shell 22.

[0055] like Figure 4 As shown, the valve is in the working state when the opening is adjusted. An LVDT sensor 20 is arranged on the outside of the actuating coil 6, which is divided into a central LVDT primary winding 19 and symmetrical LVDT secondary windings 18 on both sides. When the embedded permanent magnet 11 is manufactured, the surface needs to be coated with zinc or nickel, and the thickness of the metal coating is generally more than 50 microns. The metal coating is entirely in the annular body of the ultra-clean material. According to the skin effect of the current, when the LVDT primary winding 19 is energized, this metal coating can generate electromagnetic induction to affect the induced current in the LVDT secondary windings 18 on both sides.

[0056] The metal coating is in the annular body of ultra-clean material. The metal coating is a part of the embedded permanent magnet 11, which is similar to a layer of outer skin of the permanent magnet 11. The embedded permanent magnet is generally a neodymium iron boron permanent magnet. Its manufacturing process is generally to sinter neodymium iron boron into rods, machine them into magnetic blocks of fixed size, and then magnetize them. After the magnetization is completed, there will be a coating process, generally zinc plating or nickel plating, with a thickness of tens of microns. The main purpose of the coating in the industry is to prevent corrosion. Here, based on the skin effect of metal electromagnetic induction, an induced current is generated on the surface, and its back electromotive force acts on the secondary coil of the LVDT to change the current size of the secondary coil, and this thickness of the coating is sufficient to generate an induced current for positioning the valve core.

[0057] When working, the central LVDT primary winding 19 is energized, and the symmetrical LVDT secondary windings 18 on both sides generate induced current. The difference between the coil currents on both sides is linearly related to the position of the valve core. When the embedded permanent magnet 11 is in the middle position, the difference between the coil currents on both sides is 0. When the embedded permanent magnet 11 produces an offset distance, the difference between the coil currents on both sides is not 0 and is constantly fed back to the actuating coil 6, changing the magnitude of the current in the actuating coil 6, and thus changing the axial position of the ultra-clean valve core 15. For example, when the target offset of the embedded permanent magnet 11 required to adjust the opening is a, the LVDT sensor 20 will constantly detect the valve core position, and compare it with the a value in the control circuit, and adjust the current of the actuating coil 6 until the axial position of the valve core is equal to the target a value. At this time, the feedback output of the LVDT sensor 20 is 0, the current of the actuating coil 6 no longer changes, and the valve core position is dynamically stabilized at the target offset a.

[0058] Since the magnetic circuits of the permanent magnets on both sides are symmetrical, the difference in magnetic force on the valve core is only caused by the offset a of the valve core position. The driving force of the coil only needs to compensate for the differential momentum of the magnetic forces on both sides. In the opening adjustment, the required offset distance a is often very small, and the magnetic force differential momentum is small. The actuating coil 6 only needs a small current to maintain the opening. In summary, the actuating coil 6 does not need to be energized when the valve core is sealed, and the actuating coil 6 only needs a small current to maintain the opening. Therefore, the present invention can reduce the power consumption of the solenoid valve coil, solve the problem of heating of the coil-driven solenoid valve, and enable the coil-driven solenoid valve to be used in the field of ultra-clean flow control.

[0059] Further, the LVDT sensor 20 may be replaced by an LDC sensor 23, such as Figure 5 As shown, its basic working principle is roughly the same as the above, the difference is that the LDC sensor 23 replaces the LVDT sensor 20, wherein the wiring method of the LDC sensor 23 is as follows Figure 6 As shown, a symmetrical arrangement with different coil spacing densities on both sides is formed. The embedded permanent magnet 11 in the ultra-clean valve core is provided with a metal coating during manufacturing. When the ultra-clean valve core 15 moves in the LDC wiring interval, the metal coating on its surface generates an induced current on the surface of the permanent magnet due to the electromagnetic induction principle and the skin effect. The induced magnetic field generated by the induced current further acts on the LDC coil, changing the current therein, completing the detection of the axial position of the valve core, and thus feeding back to the actuating coil 6, changing the current size of the actuating coil 6, changing the axial position of the valve core, and completing the adjustment of the valve opening.

[0060] In order to meet the needs of high-cleanliness occasions, the wall surface in contact with the fluid in the ultra-clean magnetic levitation valve should be made of ultra-clean material. The embedded permanent magnet array 19 arranged in a spatial layered manner is embedded with ultra-clean material during the injection molding process, or coated or wrapped with ultra-clean material to form an ultra-clean magnetic levitation valve core 22. Optional ultra-clean materials include but are not limited to fluorine-containing plastics such as perfluoroalkoxy (PFA), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF) or any combination thereof.

[0061] In the description of the positional relationship of the present invention, terms such as "inside", "outside", "up", "down", "left", "right", etc. that indicate orientation or positional relationship are based on the orientation or positional relationship shown in the drawings and are only for the convenience of describing the embodiments and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0062] The above content and structure describe the basic principle, main features and advantages of the product of the present invention, which should be understood by those skilled in the art. The above examples and descriptions are only for explaining the principle of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which are within the scope of the present invention. The scope of the present invention is defined by the attached claims and their equivalents.

Claims

1. A low-power ultra-clean differential solenoid valve, comprising a valve seat (9) and a valve cover (2), wherein the valve cover (2) is mounted on the valve seat (9), and is characterized in that: The invention comprises permanent magnets (4, 7), an actuating coil (6), a valve core displacement sensor (20), and an ultra-clean valve core (15); wherein a valve cover (2) and a valve seat (9) made of ultra-clean material are tightly assembled and enclosed internally to form an ultra-clean flow chamber (3); the ultra-clean flow chamber (3) has an inlet flow path (17) and an outlet flow path (1) connected to the external environment; an ultra-clean valve core (15) is arranged inside the ultra-clean flow chamber (3); the ultra-clean valve core (15) is located at the outlet of the inlet flow path (17) directly above the top surface of the valve seat (9), The ultra-clean valve core (15) is movable in the ultra-clean flow chamber (3) along the axial direction of the ultra-clean flow chamber (3); the outer walls of the valve cover (2) outside the top and bottom of the ultra-clean flow chamber (3) are respectively installed with an annular outer upper layer permanent magnet (4) and an outer lower layer permanent magnet (7); the outer wall of the valve cover (2) between the outer upper layer permanent magnet (4) and the outer lower layer permanent magnet (7) is sleeved with an actuating coil (6); the actuating coil (6) is sleeved with a fixing sleeve (5) for packaging; the fixing sleeve (5) is sleeved with a valve core displacement sensor (20); The ultra-clean valve core (15) comprises an annular body, a block body, an embedded permanent magnet (11), a connecting arm (13) and an outer ultra-clean material coating layer (12); the annular body is located above the block body, an annular cavity is provided in the annular body, an embedded permanent magnet (11) is embedded in the annular cavity, a flow hole (10) is provided in the annular body, a gap in the vertical direction is provided between the annular body and the block body, the annular body and the block body are tightly connected by a plurality of connecting arms (13) arranged at intervals along the circumferential direction, the interior of the annular body is arranged as a hollow structure with an annular cavity, and the interior of the block body is solid; The top surface of the valve seat (9) is provided with a raised surface as a sealing boss (16) at the outlet end of the inlet flow path (17), and the bottom surface of the ultra-clean valve core (15) is provided with an inner concave surface as an annular sealing surface (14), and the sealing boss (16) and the annular sealing surface (14) are embedded in corresponding phase lines; The outer upper layer permanent magnet (4), the outer lower layer permanent magnet (7), and the embedded permanent magnet (11) of the ultra-clean valve core (15) have the same magnetization direction, which is along the up-down direction, and the same magnetic arrangement direction.

2. A low-power ultra-clean differential solenoid valve as claimed in claim 1, characterized in that: The valve core displacement sensor includes an LVDT sensor and an LDC sensor.

3. A low-power ultra-clean differential solenoid valve as claimed in claim 1, characterized in that: The valve core displacement sensor (20) adopts an LVDT sensor, including an LVDT secondary winding (18) and an LVDT primary winding (19); two LVDT secondary windings (18) and one LVDT primary winding (19) are arranged outside the fixed sleeve (5); the LVDT primary winding (19) is arranged in the middle, and the LVDT secondary windings (18) are arranged on the upper and lower sides of the LVDT primary winding (19); the LVDT secondary winding (18) and the one LVDT primary winding (19) are covered with a winding housing (21).

4. A low-power ultra-clean differential solenoid valve as claimed in claim 2, characterized in that: The valve core displacement sensor (20) adopts an LDC sensor, comprising an outer fixed shell (22) and an LDC sensor (23). The LDC sensor (23) is provided on one side surface outside the fixed sleeve (5). The LDC sensor (23) is a sensor coil. The sensor coil is arranged in a planar spiral. The coil density on one side of the sensor coil is lower than the coil density on the other side. The LDC sensor (23) is encapsulated by the outer fixed shell (22).

5. The low-power ultra-clean differential solenoid valve according to claim 1, characterized in that: The static magnetic adsorption of the ultra-clean valve core (15) is controlled by the outer upper layer permanent magnet (4) and the outer lower layer permanent magnet (7), and the movement and position of the ultra-clean valve core (15) in the upper and lower directions of the ultra-clean flow chamber (3) are controlled by energizing the actuating coil (6), thereby adjusting the opening of the ultra-clean differential solenoid valve.

6. A low-power ultra-clean differential solenoid valve as claimed in claim 1, characterized in that: The valve cover (2), valve seat (9) and the annular body, block body and connecting arm (13) of the ultra-clean valve core (15) are all made of ultra-clean materials.

7. The application of a low-power ultra-clean differential solenoid valve as claimed in claim 1, characterized in that: The ultra-clean differential solenoid valve is used for ultra-clean fluid transmission and control in the fields of semiconductors, biomedicine, electronic-grade chemicals, etc.

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