Ion mobility tube

Abstract

An ion migration tube is composed of an outer cylinder, an outer cylinder gland, an electrode ring and an insulating ring. The outer cylinder has an annular groove and an internal thread. The outer cylinder gland has an external thread and is connected to the outer cylinder by screwing. The electrode ring has an annular groove on both sides, which can be matched with the two protrusions of the insulating ring to form two-sided contact. Two electrode rings and an insulating ring with a smaller outer diameter are combined into an annular groove. An O-shaped sealing ring is placed in the annular groove and is compressed by the inner wall of the outer cylinder to form a seal. This structure mainly uses an electrode ring with double-sided annular grooves and an insulating ring with double-sided protrusions to form an internal seal. The external annular groove is combined, and the O-shaped ring is placed to form an external seal. The double-sealing structure has an internal seal determined by the material properties of the insulating ring, which uses a Teflon material with sealing properties. This material does not release impurity gas at high temperatures, which can contaminate the internal sealing cavity. The external seal uses a low-temperature-resistant O-shaped ring material that can maintain good sealing performance in a low-temperature environment.

Description

Technical Field

[0001] This invention relates to the sealing of the ion migration tube, a core component of ion migration spectroscopy, specifically a novel method for achieving internal sealing of the ion migration tube using a slot and an O-ring. Background Technology

[0002] As the core component of ion mobility spectrometry, the quality of the ion mobility spectrometry tube's sealing directly affects the sensitivity, recovery time of the initial state, and cleanliness of the tube's interior, thus directly impacting the continuity and stability of the ion mobility spectrometry's performance indicators. Therefore, this invention designs a new method to achieve high sealing performance of the ion mobility spectrometry tube.

[0003] Currently, ion migration tube sealing employs an inner cavity with an insulating sleeve and rubber O-rings. However, this method suffers from several drawbacks. First, the plastic insulating sleeve can cause severe charge accumulation. Second, the rubber O-rings release organic matter at high temperatures, contaminating the inside of the migration tube. Using ceramic as the insulating material and bonding a ceramic ring to a stainless steel electrode with ceramic sealant is another method for sealing ion migration tubes, but this method is unsuitable for high-temperature applications. Low-temperature co-firing ceramic integral molding technology has also been used in the design of high-sealing ion migration tubes, but this technology is time-consuming and costly. Chen et al. used planar fit and stress spring compression to achieve gas-phase sealing inside the ion migration tube, but this method suffers from high axial clamping force during assembly, and the effects of cold shrinkage and deformation of the insulating material at low temperatures, potentially leading to poor contact between the end faces and affecting performance in low-temperature environments. Therefore, this invention discloses a new method for achieving high sealing performance in ion migration tubes, employing a double-sealing method combining a groove and an O-ring to achieve gas-phase sealing inside the migration tube. Because it uses a double-sided protrusion and slot assembly, the insulation material deforms under heat, automatically filling the slot to achieve an internal seal without requiring a large axial clamping force. The annular groove formed by the electrode ring and the outer diameter of the insulation places an O-ring. The O-ring is squeezed by the inner wall of the outer cylinder to produce a sealing effect, forming an outer seal inside the migration tube. This achieves a double-layer seal inside and outside the migration tube, enabling a high sealing effect in both high and low temperature environments. Summary of the Invention

[0004] The technical problem to be solved by this invention is: the O-ring of the migration tube releases organic matter in a high-temperature environment, the sealing is poor in a low-temperature environment, and a large pre-tightening force is required for assembly.

[0005] The specific content includes:

[0006] A novel method for achieving high sealing performance of ion migration tubes comprises an outer cylinder, an outer cylinder cap, an electrode ring, and an insulating ring. The outer cylinder has an annular groove and internal threads. The outer cylinder cap has external threads and is connected to the outer cylinder by screwing. The electrode rings have annular grooves on both sides, which can engage with the protrusions on both sides of the insulating ring to form a two-sided contact. The two electrode rings and an insulating ring with a smaller outer diameter are combined to form an annular groove. An O-ring is placed in the annular groove, and a seal is formed by compression from the inner wall of the outer cylinder.

[0007] The outer cylinder has an annular groove that mates with the insulating ring; the depth of the groove is 0.01-0.05 mm greater than the height of the protrusion on the insulating ring.

[0008] The electrode ring has annular grooves on the front and back, the depth of which must be 0.01-0.05mm greater than the height of the protrusion on the insulating ring. Furthermore, the outer edge of the annular groove on the electrode ring must be machined with a certain precision, and its roughness must not exceed 1.6μm.

[0009] The insulating ring has raised rings at the front and back, and its height is 0.05mm less than the annular grooves on the outer cylinder and electrode ring. The insulating ring is made of Teflon material with sealing properties and is a type that can expand in high-temperature environments.

[0010] The outer cylinder cover is made of insulating material, specifically PPS material with a certain strength. It has external threads that mate with the internal threads on the outer cylinder to fix the electrode ring and insulating ring inside the migration tube.

[0011] This structure primarily employs an electrode ring with double-sided annular grooves and an insulating ring with double-sided protrusions to form an inner seal, and an outer annular groove to hold an O-ring, creating an outer seal. The inner seal is mainly determined by the material properties of the insulating ring, which uses Teflon, a material with inherent sealing properties. This material does not release impurities at high temperatures, thus preventing contamination of the internal sealed cavity. The outer seal uses a low-temperature resistant O-ring material, maintaining good sealing performance even in low-temperature environments. Attached Figure Description

[0012] Figure 1 A schematic diagram of the ion migration tube structure. Wherein: 1--outer cylinder, 2--O-ring seal, 3--electrode ring, 4--insulating ring, 5--outlet, 6--inlet, 7--outer cylinder cap. Detailed Implementation

[0013] Example 1

[0014] like Figure 1 As shown, an ion migration tube includes an outer cylinder 1, an outer cylinder cap 7, an electrode ring 3, and an insulating ring 4;

[0015] Electrode ring 3 is a circular plate electrode with a circular through hole in the middle. Symmetrical annular grooves are formed on both sides of the plate, and the through hole is located in the area surrounded by the annular grooves. Insulating ring 4 is a circular plate electrode with a circular through hole in the middle. Symmetrical annular bosses are formed on both sides of the plate, and the through hole is located in the area surrounded by the annular bosses. The radial cross-section of the annular bosses is the same as or equivalent to the radial cross-section of the annular grooves.

[0016] Along the axial direction, n+1 insulating rings 4 and n electrode rings 3 are alternately stacked to form a cylindrical ion migration tube inner tube with open ends on both sides, where n is 14. The circular through holes in the middle of the electrode rings 3 and insulating rings 4 are coaxial. The annular boss is placed in the annular groove adjacent to it. The outer diameter of the insulating ring 4 is smaller than the outer diameter of the electrode ring 3. An annular groove is formed between adjacent electrode rings 3 on the outer side wall of each insulating ring 4. An O-ring seal 2 is provided in the annular groove.

[0017] The outer cylinder (1) is a cylindrical body with a closed left end and an open right end. The inner cylinder of the cylindrical ion migration tube is placed inside the cylindrical outer cylinder 1. The inner cylinder and the outer cylinder 1 are coaxial. A circular groove corresponding to the circular annular boss on the insulating ring 4 is provided on the left end face inside the outer cylinder 1. The radial cross section of the circular annular boss is the same as or equivalent to the radial cross section of the circular annular groove. The circular annular boss of the insulating ring 4 on the leftmost side of the inner cylinder is placed in the circular annular groove on the left end face inside the outer cylinder 1. An O-ring is provided between the outer wall of the insulating ring 4 on the leftmost side and the inner wall of the outer cylinder 1.

[0018] An internal thread is provided on the inner wall surface of the right opening end of the outer cylinder 1. The outer cylinder cover 7 is a round cover with an external thread. The outer cylinder cover 7 is screwed into the right opening end of the outer cylinder 1 through its external thread.

[0019] An annular groove corresponding to the annular boss on the insulating ring 4 is provided on the left end face of the outer cylinder cover 7. The radial cross-section of the annular boss and the radial cross-section of the annular groove are the same or equivalent in shape and size. The annular boss of the insulating ring 4 on the far right of the inner cylinder is placed in the annular groove on the left end face of the outer cylinder cover 7. An O-ring is provided between the outer wall of the insulating ring 4 on the far right and the inner wall of the outer cylinder 1.

[0020] A through hole serving as an air outlet 5 is provided on the side wall of the left part of the outer cylinder cover 7, and a through hole serving as an air inlet 6 is provided on the outer cylinder cover 7.

[0021] The inner diameter of the outer cylinder is 40mm, and the inner diameter of the annular groove on the outer cylinder is 27mm, the outer diameter is 30mm, and the depth is 1.5mm.

[0022] The electrode ring has an outer diameter of 39mm, which is smaller than the inner diameter of the outer cylinder. The O-ring has an outer diameter of 40.5mm, which is larger than the inner diameter of the outer cylinder. The insulating ring has an outer diameter of 37mm and an inner diameter of the protrusion that is greater than 27mm. The tolerance is between 0 and 0.05. The outer diameter is less than 30mm, with a tolerance between 0 and 0.05.

[0023] Insert the insulating ring into the outer cylinder, then install the electrode ring and the insulating ring in sequence, and finally screw on the outer shell cap. Do not insert the O-ring. Only the inner seal is used to form the migration tube. Test the sealing performance at a gas pressure of 200 kPa. Place the sealed migration tube in room temperature water. After 1 minute, bubbles will emerge and the pressure gauge reading will drop, indicating that in a low-temperature environment, the sealing performance is not good if only the groove is used for sealing.

[0024] Example 2

[0025] like Figure 1 As shown, an ion migration tube includes an outer cylinder 1, an outer cylinder cap 7, an electrode ring 3, and an insulating ring 4;

[0026] Electrode ring 3 is a circular plate electrode with a circular through hole in the middle. Symmetrical annular grooves are formed on both sides of the plate, and the through hole is located in the area surrounded by the annular grooves. Insulating ring 4 is a circular plate electrode with a circular through hole in the middle. Symmetrical annular bosses are formed on both sides of the plate, and the through hole is located in the area surrounded by the annular bosses. The radial cross-section of the annular bosses is the same as or equivalent to the radial cross-section of the annular grooves.

[0027] Along the axial direction, n+1 insulating rings 4 and n electrode rings 3 are alternately stacked to form a cylindrical ion migration tube inner tube with open ends on both sides, where n is 13. The circular through holes in the middle of the electrode rings 3 and insulating rings 4 are coaxial. The annular boss is placed in the annular groove adjacent to it. The outer diameter of the insulating ring 4 is smaller than the outer diameter of the electrode ring 3. An annular groove is formed between adjacent electrode rings 3 on the outer side wall of each insulating ring 4. An O-ring seal 2 is provided in the annular groove.

[0028] The outer cylinder 1 is a cylindrical body that is sealed at the left end and open at the right end. The inner cylinder of the cylindrical ion migration tube is placed inside the cylindrical outer cylinder 1, and the inner cylinder and the outer cylinder 1 are coaxial. On the left end face inside the outer cylinder 1, there is an annular groove corresponding to the annular boss on the insulating ring 4. The radial cross section of the annular boss is the same as or equivalent to the radial cross section of the annular groove. The annular boss of the leftmost insulating ring 4 of the inner cylinder is placed in the annular groove on the left end face inside the outer cylinder 1. An O-ring is provided between the outer wall of the leftmost insulating ring 4 and the inner wall of the outer cylinder 1.

[0029] An internal thread is provided on the inner wall surface of the right opening end of the outer cylinder 1. The outer cylinder cover 7 is a round cover with an external thread. The outer cylinder cover 7 is screwed into the right opening end of the outer cylinder 1 through its external thread.

[0030] An annular groove corresponding to the annular boss on the insulating ring 4 is provided on the left end face of the outer cylinder cover 7. The radial cross-section of the annular boss and the radial cross-section of the annular groove are the same or equivalent in shape and size. The annular boss of the insulating ring 4 on the far right of the inner cylinder is placed in the annular groove on the left end face of the outer cylinder cover 7. An O-ring is provided between the outer wall of the insulating ring 4 on the far right and the inner wall of the outer cylinder 1.

[0031] A through hole serving as an air outlet 5 is provided on the side wall of the left part of the outer cylinder cover 7, and a through hole serving as an air inlet 6 is provided on the outer cylinder cover 7.

[0032] The inner diameter of the outer cylinder is 40mm, and the inner diameter of the annular groove on the outer cylinder is 27mm, the outer diameter is 30mm, and the depth is 1.5mm.

[0033] The electrode ring has an outer diameter of 39mm, which is smaller than the inner diameter of the outer cylinder. The O-ring has an outer diameter of 40.5mm, which is larger than the inner diameter of the outer cylinder. The insulating ring has an outer diameter of 37mm and an inner diameter of the protrusion that is greater than 27mm. The tolerance is between 0 and 0.05. The outer diameter is less than 30mm, with a tolerance between 0 and 0.05.

[0034] Insert the insulating ring into the outer cylinder, then install the electrode ring and the insulating ring in sequence, and finally screw on the outer shell cap and insert the O-ring. The migration tube, which is formed by both inner and outer seals, is tested for sealing performance at a gas pressure of 200 kPa. After the sealed migration tube is placed in room temperature water and left to stand for 30 minutes, there are no bubbles in the water and the pressure gauge reading does not change. This indicates that in a low-temperature environment, when the insulating ring material does not expand to provide a sealing effect, the outer O-ring provides a sealing effect.

[0035] Example 3

[0036] like Figure 1 As shown, an ion migration tube includes an outer cylinder 1, an outer cylinder cap 7, an electrode ring 3, and an insulating ring 4;

[0037] Electrode ring 3 is a circular plate electrode with a circular through hole in the middle. Symmetrical annular grooves are formed on both sides of the plate, and the through hole is located in the area surrounded by the annular grooves. Insulating ring 4 is a circular plate electrode with a circular through hole in the middle. Symmetrical annular bosses are formed on both sides of the plate, and the through hole is located in the area surrounded by the annular bosses. The radial cross-section of the annular bosses is the same as or equivalent to the radial cross-section of the annular grooves.

[0038] Along the axial direction, n+1 insulating rings 4 and n electrode rings 3 are alternately stacked to form a cylindrical ion migration tube inner tube with open ends on both sides, where n is 10. The circular through holes in the middle of the electrode rings 3 and insulating rings 4 are coaxial. The annular boss is placed in the annular groove adjacent to it. The outer diameter of the insulating ring 4 is smaller than the outer diameter of the electrode ring 3. An annular groove is formed between adjacent electrode rings 3 on the outer side wall of each insulating ring 4. An O-ring seal 2 is provided in the annular groove.

[0039] The outer cylinder 1 is a cylindrical body that is sealed at the left end and open at the right end. The inner cylinder of the cylindrical ion migration tube is placed inside the cylindrical outer cylinder 1, and the inner cylinder and the outer cylinder 1 are coaxial. On the left end face inside the outer cylinder 1, there is an annular groove corresponding to the annular boss on the insulating ring 4. The radial cross section of the annular boss is the same as or equivalent to the radial cross section of the annular groove. The annular boss of the leftmost insulating ring 4 of the inner cylinder is placed in the annular groove on the left end face inside the outer cylinder 1. An O-ring is provided between the outer wall of the leftmost insulating ring 4 and the inner wall of the outer cylinder 1.

[0040] An internal thread is provided on the inner wall surface of the right opening end of the outer cylinder 1. The outer cylinder cover 7 is a round cover with an external thread. The outer cylinder cover 7 is screwed into the right opening end of the outer cylinder 1 through its external thread.

[0041] An annular groove corresponding to the annular boss on the insulating ring 4 is provided on the left end face of the outer cylinder cover 7. The radial cross-section of the annular boss and the radial cross-section of the annular groove are the same or equivalent in shape and size. The annular boss of the insulating ring 4 on the far right of the inner cylinder is placed in the annular groove on the left end face of the outer cylinder cover 7. An O-ring is provided between the outer wall of the insulating ring 4 on the far right and the inner wall of the outer cylinder 1.

[0042] A through hole serving as an air outlet 5 is provided on the side wall of the left part of the outer cylinder cover 7, and a through hole serving as an air inlet 6 is provided on the outer cylinder cover 7.

[0043] The inner diameter of the outer cylinder is 40mm, and the inner diameter of the annular groove on the outer cylinder is 27mm, the outer diameter is 30mm, and the depth is 1.5mm.

[0044] The electrode ring has an outer diameter of 39mm, which is smaller than the inner diameter of the outer cylinder. The O-ring has an outer diameter of 40.5mm, which is larger than the inner diameter of the outer cylinder. The insulating ring has an outer diameter of 37mm and an inner diameter of the protrusion that is greater than 27mm. The tolerance is between 0 and 0.05. The outer diameter is less than 30mm, with a tolerance between 0 and 0.05.

[0045] Insert the insulating ring into the outer cylinder, then install the electrode ring and the insulating ring in sequence, and finally screw on the outer shell cap and insert the O-ring. The migration tube, which is formed by both internal and external sealing, is tested for sealing performance at a gas pressure of 200 kPa. The sealed migration tube is then heated for sample injection testing. The background peak of the emission signal does not change, indicating that under high temperature conditions, the insulating ring expands and plays a sealing role. The organic matter released by the O-ring under high temperature conditions does not enter the interior of the migration tube. This double-sealed structure can achieve good sealing performance under both high and low temperature environments.

Claims

1. An ion migration tube, characterized in that: It includes an outer cylinder (1), an outer cylinder cap (7), an electrode ring (3), and an insulating ring (4); The electrode ring (3) is a circular plate electrode with a circular through hole in the middle. Symmetrical annular grooves are provided on both sides of the plate, and the through hole is located in the area surrounded by the annular groove. The insulating ring (4) is a circular plate electrode with a circular through hole in the middle. Symmetrical annular bosses are provided on both sides of the plate, and the through hole is located in the area surrounded by the annular bosses. The radial cross section of the annular bosses is the same as or equivalent to the radial cross section of the annular grooves. Along the axial direction, n+1 insulating rings (4) and n electrode rings (3) are alternately stacked to form a cylindrical ion migration tube inner tube with open ends on both sides, where n is an integer greater than or equal to 4 (preferably an integer greater than or equal to 10). The circular through holes in the middle of the electrode rings (3) and the insulating rings (4) are coaxial. The annular boss is placed in the annular groove adjacent to it. The outer diameter of the insulating ring (4) is smaller than the outer diameter of the electrode ring (3). An annular groove is formed between adjacent electrode rings (3) on the outer side wall of each insulating ring (4). An O-ring (2) is provided in the annular groove. The outer cylinder (1) is a cylindrical body with a closed left end and an open right end. The inner cylinder of the cylindrical ion migration tube is placed inside the cylindrical outer cylinder (1), and the inner cylinder and the outer cylinder (1) are coaxial. A circular groove corresponding to the circular annular boss on the insulating ring (4) is provided on the left end face inside the outer cylinder (1). The radial cross section of the circular annular boss is the same as or equivalent to the radial cross section of the circular annular groove. The circular annular boss of the insulating ring (4) on the leftmost side of the inner cylinder is placed in the circular annular groove on the left end face inside the outer cylinder (1). An O-ring is provided between the outer wall of the insulating ring (4) on the leftmost side and the inner wall of the outer cylinder (1). An internal thread is provided on the inner wall surface of the right opening end of the outer cylinder (1), and the outer cylinder cover (7) is a round cover with an external thread. The outer cylinder cover (7) is screwed into the right opening end of the outer cylinder (1) through its external thread. An annular groove corresponding to the annular boss on the insulating ring (4) is provided on the left end face of the outer cylinder cap (7). The radial cross-section of the annular boss and the radial cross-section of the annular groove are the same or equivalent in shape and size. The annular boss of the insulating ring (4) on the far right of the inner cylinder is placed in the annular groove on the left end face of the outer cylinder cap (7). An O-ring is provided between the outer wall of the insulating ring (4) on the far right and the inner wall of the outer cylinder (1). A through hole serving as an air outlet (5) is provided on the side wall of the left part of the outer cylinder cover (7), and a through hole serving as an air inlet (6) is provided on the outer cylinder cover (7).

2. The ion migration tube according to claim 1, characterized in that: A circular pressure plate is provided between the outer cylinder cap (7) and the inner cylinder of the ion migration tube. A circular groove corresponding to the circular annular boss on the insulating ring (4) is provided on the left end face of the circular pressure plate. The radial cross section of the circular annular boss and the radial cross section of the circular annular groove are the same or equivalent in shape and size. The circular annular boss of the insulating ring (4) on the far right of the inner cylinder is placed in the circular annular groove on the left end face of the circular pressure plate. An O-ring is provided between the outer wall of the insulating ring (4) on the far right and the inner wall of the outer cylinder (1). A through hole as an air outlet (5) is provided on the side wall of the left part of the outer cylinder cover (7), and corresponding through holes as air inlets (6) are provided on both the outer cylinder cover (7) and the circular pressure plate.

3. The ion migration tube according to claim 1 or 2, characterized in that: An air outlet pipe is inserted inside the air outlet (5); An air inlet pipe is inserted inside the air inlet (6).

4. The ion migration tube according to claim 1, characterized in that: The O-ring (2) is squeezed by the inner wall of the outer cylinder to achieve sealing between the inner cylinder and the outer cylinder.

5. The ion migration tube according to claim 1 or 2, characterized in that: The insulating ring is made of a plastic material with a certain degree of elasticity.

6. The ion migration tube according to claim 1 or 2, characterized in that: The depth of the annular groove should be 0.01-0.05 mm greater than the height of the boss on the insulating ring.

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