Automatic sample injector for gas isotope spectrometer

Abstract

A gas isotope spectrometer automatic sampler includes: a control system, a gas circuit system, a positioning system and a bottom plate; wherein the control system includes a control panel and a single-chip microcomputer, and the control panel is connected to the single-chip microcomputer through a cable; the positioning system includes a sample plate, a gear plate, a motor, a cylinder, a cylinder arm, a central axis rod, and a side axis rod; the gas circuit system includes a three-way needle inlet valve, a three-way needle retracting valve, an air pressure stabilizing valve, a two-way vacuum valve, a three-way air inlet valve, a three-way selection valve, a vacuum pump, a gas sampling pump, a sample gas bag, a two-way inflation valve, an electronic air pressure control table, a dilution buffer bag, and a nitrogen pressure regulating valve. The present invention can be used in conjunction with an isotope spectrometer to realize the preparation of gas isotope samples and fully automatic sampling and analysis.

Description

Technical Field

[0001] The invention relates to the technical field of gas detection, and more particularly to an automatic sample injector for a gas isotope spectrometer. Background Art

[0002] Isotope tracing technology is to use the isotope of an element itself or to replace an element of the substance with an isotope to mark a compound. According to different purposes, isotopes can use radioactive isotopes or stable isotopes, all of which target the difference in radiation energy or mass of isotopes. Generally, since stable isotopes have no nuclear radiation, the properties of isotope atoms or molecules will not affect the physical and chemical properties of the substance, and will not affect the physiological and biochemical processes of animals and plants. They are widely used in the study of the mechanism of action in scientific research, and can study the source and destination of substances.

[0003] Traditionally, the detection of stable isotopes is achieved by isotope mass spectrometers, whose main principle is to distinguish different isotope molecules by their different mass numbers and different deflections in the magnetic field. Isotope mass spectrometers are expensive, bulky, have long stabilization time, and long analysis time. In recent years, the spectrum analyzer of stable isotopes has made great progress. The most typical one is the gas isotope spectrometer of Piccaro Company in the United States. Its main analysis principle is to use the cavity ring-down technology, that is, by increasing the detection optical path by using mirror reflection in the optical cavity, turning off the laser after irradiating the gas to be tested, and recording the different ring-down times of the source laser in the optical cavity caused by different isotopes for detection. Compared with the traditional mass spectrometry, it has great advantages. Its accuracy is higher than that of mass spectrometry, the detection speed is hundreds or thousands of times faster, the instrument is small in size, and easy to maintain. It is a new generation of isotope detection instrument. However, the optical cavity of the gas isotope spectrometer is large in size, and the required injection volume is much larger than that of the mass spectrometer, reaching tens to hundreds of milliliters, and the isotope spectrometer needs to be injected at normal pressure or micro pressure.

[0004] Gas isotope spectrometers require a large sample volume, and samples are generally stored in sample bags. However, sample bags are not fixed in shape and occupy a large volume, making them unsuitable for large-scale automatic analysis. In addition, the injection pressure range of gas isotope spectrometers is relatively narrow. Direct use of headspace bottles for injection will cause the internal pressure to be too low as the injection progresses, making it impossible to meet the injection requirements.

[0005] Therefore, how to provide a method for realizing automatic preparation of isotope gas samples and automatic sampling and analysis in conjunction with a gas isotope spectrometer under normal pressure is an urgent problem to be solved by those skilled in the art. Summary of the invention

[0006] In view of this, the present invention provides a gas isotope spectrometer automatic sample injector, which adopts a control system, a gas path system and a positioning system to realize the preparation of gas isotope samples and the automatic injection function.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] A gas isotope spectrometer automatic sample injector comprises a control system, a gas path system, a positioning system and a bottom plate; the positioning system is electrically connected to the control system; the positioning system is fixed on the bottom plate;

[0009] The gas circuit system includes a gas cylinder, an injection device, a gas cylinder driving device, a two-way vacuum valve, a three-way air inlet valve, a three-way selection valve, a vacuum pump, a gas sampling pump, a sample gas bag, a two-way inflation valve, an electronic air pressure control meter, a dilution buffer bag, and a nitrogen pressure regulating valve;

[0010] The three-way air inlet valve is connected to the vacuum pump through the two-way vacuum valve, the three-way air inlet valve is connected to the sample gas bag through the gas sampling pump, the three-way air inlet valve is connected to the isotope spectrometer, and the three-way air inlet valve is connected to the injection device through the three-way selection valve; the injection device, the electronic air pressure control table, the dilution buffer bag, and the two-way inflation valve are connected through a four-way connector; the two-way inflation valve is connected to the nitrogen pressure regulating valve, and the two-way inflation valve is electrically connected to the electronic air pressure control table;

[0011] The cylinder is fixed on the positioning system and connected to the cylinder driving device;

[0012] The injection system is connected to the cylinder;

[0013] The two-way vacuum valve, three-way air inlet valve, three-way selection valve, vacuum pump, air sampling pump, two-way charging valve, electronic air pressure control meter, nitrogen pressure regulating valve, and cylinder driving device are electrically connected to the control system respectively.

[0014] Preferably, the cylinder driving device comprises: a three-way needle inlet valve, a three-way needle return valve and an air pressure-stabilizing valve; the three-way needle inlet valve outlet and the three-way needle return valve outlet are respectively connected to the cylinder; the three-way needle inlet valve inlet and the three-way needle return valve inlet are respectively connected to the air pressure-stabilizing valve outlet through a three-way joint; the air pressure-stabilizing valve inlet is connected to compressed air; the three-way needle inlet valve, the three-way needle return valve and the air pressure-stabilizing valve are respectively electrically connected to the control system;

[0015] The cylinder comprises: a cylinder barrel, a piston, and a cylinder shaft; the piston divides the cylinder into an upper air chamber and a lower air chamber;

[0016] The upper air chamber is communicated with the air outlet of the three-way needle valve, and the lower air chamber is communicated with the air outlet of the three-way needle valve;

[0017] One end of the cylinder shaft is connected to the piston, and the other end is connected to the injection system.

[0018] A stroke adjustment knob is installed on the top of the cylinder;

[0019] The injection system comprises: a needle seat and a double-hole injection needle, one end of the needle seat is connected to the cylinder shaft, and the other end is connected to the double-hole injection needle, and the interior of the needle seat is connected to the three-way selection valve; the double-hole injection needle is connected to the four-way connector.

[0020] The needle seat has external threads at both ends, a hexagonal prism in the middle, the upper external threads are connected to the cylinder shaft, the cylinder shaft and the piston are an integrated structure, and the lower external threads are connected to the double-hole injection needle with internal threads. There is a 90-degree gas channel hole inside the needle seat that connects the inner center of the needle head external thread and the center of one of the faces of the hexagonal prism. One end of this gas channel inside the needle seat is connected to the air inlet pipe in the center of the double-side hole injection needle with a sealing ring, and the air inlet channel at the other end is on the prism surface. The double-side hole air inlet needle square head is processed with threads inside, and a rubber gasket is placed below the needle seat and on the end face of the double-side hole air inlet needle. The needle seat and the needle are sealed by this thread while being connected to the needle seat. There is a stainless steel capillary inside the double-side hole air inlet needle. The upper end of the capillary is sealed with the needle seat through a sealing ring, and the lower end is also sealed with the inner wall of the needle tube. The two side holes of the double-side hole needle are separated, so that the side hole at the bottom of the sealing ring is connected to the middle capillary. There is an air outlet on the side of the double-side hole needle square head, and the side hole at the top of the sealing ring is connected to the air outlet on the side of the needle. The side hole is a rectangular small hole processed on the side wall of the needle tube to prevent the needle tube from being blocked by foam when the needle pierces the rubber sealing gasket.

[0021] Specifically, the three-way air inlet valve, three-way selection valve, three-way needle inlet valve and three-way needle outlet valve are all normally closed two-position three-way solenoid valves. This valve has three interfaces, namely the air inlet, air outlet and exhaust port. The exhaust port is located at the top of the valve. When the valve is in the closed state with no power on, the air inlet is sealed by a sealing gasket, and gas cannot pass through, while the air outlet and the exhaust port are connected; when the valve is energized, the air inlet and the air outlet are connected, while the exhaust port is not connected; the two-way vacuum valve and the two-way air inlet valve are normally closed two-position two-way solenoid valves, which only have an air inlet and an air outlet. When the valve is closed without power on, the air inlet and the exhaust port are not ventilated, and when the valve is energized and opened, the air inlet and the air outlet are connected.

[0022] Furthermore, the air outlet of the two-way vacuum valve is connected to the vacuum pump, the air inlet is connected to the exhaust port of the three-way air inlet valve, the air outlet of the three-way selection valve is connected to the needle seat, the air inlet of the three-way selection valve is connected to the air outlet of the three-way air inlet valve, the exhaust port of the three-way selection valve is connected to the spectrometer, and the air inlet of the three-way air inlet valve is connected to the gas sampling pump; the air outlet of the three-way needle inlet valve is connected to the upper air chamber of the square cylinder, its air inlet is connected to the three-way joint, and the exhaust port is connected to the atmosphere; the air outlet of the three-way needle retreat valve is connected to the lower air chamber of the square cylinder, its air inlet is connected to the other interface of the three-way joint, and the exhaust port is connected to the atmosphere; the air outlet of the two-way inflation valve is connected to the four-way joint, and the air inlet of the two-way inflation valve is connected to the nitrogen pressure regulating valve.

[0023] Preferably, the positioning system comprises: a sample plate, a gear plate, a cylinder arm, a central axis device, a side axis device, a sliding arm, a gear and a power device;

[0024] The sample tray and the gear tray are both fixedly mounted on the central axis device, and the sample tray is located on the top of the gear tray; the sample tray is provided with bottle holes arranged in an involute manner; and the gear tray surface is provided with slide grooves corresponding to the bottle holes;

[0025] The central axis device and the side axis device are both vertically mounted on the bottom plate;

[0026] The slide arm and one end of the cylinder arm are both mounted on the side-shaft device, and the slide arm is parallel to the cylinder arm; a guide head is fixedly arranged on the slide arm, and the guide head slides in the slide groove; the cylinder is fixed on the cylinder arm;

[0027] The gear is connected to the power device, and the gear is matched with the gear plate.

[0028] Preferably, the slide arm comprises: an upper slide and a lower slide, the upper slide and the lower slide are fixedly mounted on the side axis device, the upper slide and the lower slide are PCB circuit boards with components welded thereon, and the guide head is arranged on the upper slide;

[0029] The upper slide and the lower slide are electrically connected to the control system via conductive wires respectively;

[0030] The starting position and the ending position of the slide slot are respectively provided with a starting magnet and a final magnet; the upper slide is provided with a starting probe and a final probe; the starting probe and the final probe are both electrically connected to the control device.

[0031] Preferably, a capacitive gate displacement sensor is welded on the upper slide, the head of the capacitive gate displacement sensor is located in the guide head, and a capacitive gate circuit is pasted inside the slide groove; the capacitive gate displacement sensor is powered by the upper slide.

[0032] Preferably, the central axis device comprises: a central axis bearing portion and a central axis rod; the lower portion of the central axis rod is fitted in the central axis bearing portion; and the sample plate and the gear plate are both fixedly mounted on the central axis rod;

[0033] The paraxial device comprises: a paraxial bearing part and a paraxial rod; the paraxial rod is fitted in the paraxial bearing part; and the upper slide plate and the lower slide plate are both fixedly sleeved on the paraxial rod;

[0034] Furthermore, the central axis bearing portion and the side axis bearing portion are both vertically mounted on the bottom plate.

[0035] Among them, a through-shaft hole is provided at the center of one end of the cylinder arm, so that the cylinder shaft and the connected needle seat can pass smoothly. There is a stroke adjustment nut on the upper part of the square cylinder, which is a cylindrical stroke adjustment rod and a lock nut that can be adjusted by threading, and the cylinder shaft stroke can be adjusted. A locking hole is provided at the center of the other end of the cylinder arm, and a locking threaded hole is provided on the side of the locking hole away from the through-shaft hole. The cylinder arm can be just sleeved on the side shaft rod through the locking hole, and the cylinder arm can slide up and down on the side shaft rod. When sliding to a suitable height position, a long screw can be screwed into the locking threaded hole to clamp and lock the cylinder arm on the side shaft rod. There is also a locking hole notch on the other side of the corresponding locking hole, which can make the locking clamping deformation force evenly distributed and easier to clamp and tighten.

[0036] Furthermore, the injection system also includes an adjusting rod and a bottle blocking plate, the bottle blocking plate is a metal plate with a center and two side holes; the cylinder is fixed to the cylinder arm through an adjusting rod; there are at least two adjusting rods, which are symmetrically arranged, and the adjusting rod includes: a screw rod, a nut and a screw, one end of the screw rod is an external thread, the other end is a hexagonal prism on the outside and an internal thread on the inside; one end of the external thread of the screw rod passes through the cylinder arm and is connected to the cylinder and is locked with a nut; the screw passes through the side hole of the bottle blocking plate and is screwed into the internal thread of the screw rod.

[0037] Specifically, the adjusting rod is in the shape of a long rod, one end of which is an external thread, and the other end is a hexagonal prism with an internal thread on the outside; the bottle blocking piece is in the shape of a rectangular metal sheet, and there is a small round hole in the center of the sheet that allows the side hole needle to pass smoothly, and this small hole also has the function of straightening the needle; there is a screw hole in the middle of the left and right ends of the bottle blocking piece, and the screw passes through the bottle blocking piece and is screwed into the internal thread of the adjusting rod. A hexagonal nut is first screwed into the external thread of the adjusting rod as a lock, and then the external thread of the adjusting rod is passed through the fixing hole on the cylinder arm and screwed into the threaded fixing hole on the square cylinder.

[0038] When it is necessary to adjust the height of the bottle blocking piece, first loosen the fixing screws and locknuts, then rotate the hexagonal prism on the adjusting rod. When rotating clockwise, the outer thread of the adjusting rod screws into the threaded hole of the cylinder, and the position of the adjusting piece increases. When rotating counterclockwise, the outer thread of the adjusting rod screws out of the threaded hole of the cylinder, and the position of the adjusting piece decreases. Adjust it to the position where the needle tip is just hidden in the small hole of the bottle blocking piece when the needle is in the uppermost position, and the positions of the adjusting rods on both sides are the same height, and then tighten the locknuts and screws in sequence.

[0039] Preferably, the central axis bearing component and the side axis bearing component are the same, both comprising: a bearing seat, a bearing and a shaft cylinder; the bearing seat is open at the top, cylindrical, hollow, and has an external threaded interface at the bottom, which is screwed to the base plate through the external threaded interface; the bottom of the bearing sleeve is connected to the base plate and there is an annular depression inside; there are two bearings, which are respectively located at the upper and lower ends of the bearing seat, and the shaft cylinder is a hollow cylindrical position with an inner diameter larger than the inner diameter of the bearing. It is located between the two bearings, and the two end faces of the shaft cylinder are in close contact with the inner ring end faces of the upper and lower bearings; the central axis rod and the side axis rod pass through the inner holes of the bearing and the shaft cylinder.

[0040] Preferably, the sample plate and the gear plate are mounted on the central axis through a plate base, and the plate base includes: a locking hole at the center, screw holes at the four corners and a locking nail hole at one side, a locking hole notch is provided on one side of the locking hole, and a penetrating locking hole through groove is provided on the other side corresponding to the locking hole notch, and the locking nail hole is perpendicular to the locking hole through groove; screw holes consistent with the screw holes are provided on the gear plate and the sample plate.

[0041] Specifically, the bearing seats of the two shafts have the same structure, with an opening at the top, cylindrical, hollow, and an external thread interface at the bottom, which can be screwed to the bottom plate. There is an annular depression inside the bottom of the bearing sleeve connected to the bottom plate, which is convenient for the outer ring of the bearing seat to reduce the contact surface between the shaft and the bottom plate, keep the bearing seat in close contact with the bottom plate and perpendicular to the bottom plate; there are two small round holes on the side wall of the middle part of the bearing seat, which is convenient for using a rod-shaped tool (such as a screwdriver) to reach into the hole to help tighten or loosen the bearing seat thread and remove it.

[0042] The bottom of the central axis rod is matched with a bearing, a shaft tube and another bearing in sequence. The inner ring of the bearing is in close contact with the central axis rod, and the shaft tube is a hollow cylindrical shape. The two end faces of the shaft tube are in contact with the inner ring end faces of the bearing, but not with the central axis rod, supporting the upper and lower bearings, keeping the central axis rod vertical, and allowing the central axis rod, the inner ring of the bearing and the shaft tube to rotate smoothly at the same time. Then press the central axis rod with the bearing and the shaft tube into the bearing seat, so that the outer rings of the upper and lower bearings are in close contact with the inner wall of the bearing seat, so that the central axis rod can rotate smoothly in the bearing seat. The assembly method of the side axis is the same as that of the central axis.

[0043] Furthermore, there is a long rounded groove on the central axis, in which a standard rounded flat key can be placed. After the rounded flat key is placed inside, half of its height protrudes from the surface of the axis. When the disk shaft sleeve of the sample disk is put on the central axis, the protruding rounded flat key can be stuck in the notch on the disk shaft sleeve, and the hand-tightened locking pin can be screwed into the top of the disk shaft sleeve to accurately position the sample disk on the central axis.

[0044] Preferably, the sample plate comprises an upper plate, a middle plate, a lower plate, a single-pass copper column, a double-pass copper column and fixing screws; the middle plate is arranged between the upper plate and the lower plate, and is connected by the single-pass copper column, the double-pass copper column and fixing screws; the upper plate and the middle plate have the same structure, a central axis hole is arranged at the center position, and bottle position holes arranged in an involute manner are arranged on the plate surface; except that the bottle position holes are not arranged on the lower plate, the other structures are the same as those of the upper plate.

[0045] Preferably, the control system includes a control panel and a single-chip microcomputer, and the control panel is connected to the single-chip microcomputer with a wiring harness; the positioning system, two-way vacuum valve, three-way air intake valve, three-way selection valve, vacuum pump, air sampling pump, two-way charging valve, electronic air pressure control meter, nitrogen pressure regulating valve, and cylinder drive device are respectively connected to the single-chip microcomputer with conductive wires and are controlled by the program in the single-chip microcomputer.

[0046] It can be seen from the above technical solution that compared with the prior art, the present invention has the following beneficial effects:

[0047] The invention can realize the preparation of gas isotope samples and automatic sampling analysis in conjunction with an isotope spectrometer. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0049] Figure 1 The accompanying drawing is a schematic diagram of the overall structure of the present invention;

[0050] Figure 2 The accompanying drawing is a schematic diagram of the gas path system structure of the present invention;

[0051] Figure 3 The accompanying drawing is a schematic diagram of the cylinder arm structure of the present invention;

[0052] Figure 4 The accompanying drawing is a schematic diagram of the gear plate structure of the present invention;

[0053] Figure 5The accompanying drawing is a schematic diagram of the structure of the disc on the sample tray of the present invention;

[0054] Figure 6 The accompanying drawing is a schematic diagram of the disc seat structure of the present invention.

[0055] Among them, in the figure,

[0056] 1-control panel; 2-single chip microcomputer; 3-three-way needle inlet valve; 4-three-way needle outlet valve; 5-air pressure regulating valve; 6-two-way vacuum valve; 7-three-way air inlet valve; 8-three-way selection valve; 9-vacuum pump; 10-gas sampling pump; 11-sample gas bag; 12-air inlet pipe; 13-two-way inflation valve; 14-electronic air pressure control table; 15-nitrogen pressure regulating valve; 16-dilution buffer bag; 17-spectrometer; 18-sample plate; 181-upper plate; 182-middle plate; 183-lower plate; 184-shaft sleeve hole; 185-bottle position hole; 19-gear plate; 191 - slide; 192- starting magnet; 193- final magnet; 194- capacitive gate circuit; 20- cylinder; 201- piston; 202- upper air chamber; 203- lower air chamber; 21- cylinder arm; 22- middle axis rod; 23- side axis rod; 24- needle seat; 25- double-hole injection needle; 26- adjustment rod; 27- bottle stopper; 28- plate seat; 29- bearing seat; 30- bearing; 31- shaft cylinder; 32- bottom plate; 33- guide head; 34- slide arm; 341- upper slide; 342- lower slide; 35- motor; 36- gear; 37- stroke adjustment. DETAILED DESCRIPTION

[0057] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. 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.

[0058] Example

[0059] like Figure 1-6 As shown, the main components of the device of the present invention are:

[0060] 1) Control system: mainly includes control panel 1 and single chip computer 2 (Hongjing STC12C5A series chip); and control panel 1, motor 35 (planetary reduction motor), gas pump 10, vacuum pump 9, three-way air inlet valve 7, three-way selection valve 8, two-way vacuum valve 6, three-way needle inlet valve 3, three-way needle retracting valve 4, two-way inflation valve 13, electronic air pressure control meter 15, upper slide 341 and lower slide 342 are respectively connected to single chip computer 2 by conductive wires and controlled by the program in single chip computer 2. Control panel 1 is connected to single chip computer 2 by flat cable, with LCD screen to display information and buttons to input parameters or commands. The end position probe and the start position probe are both Hall sensors that can obtain position information through magnetic induction; upper slide 341 and lower slide 342 are long rectangular PCB circuit boards with components welded on them, and the end position probe, the start position probe and the capacitive gate displacement sensor are welded on the upper slide 341, and are all powered by the upper slide 341, and the head of the capacitive gate displacement sensor is located in the guide head 23. The capacitor gate circuit 144 is adhered to the slide groove 191 of the gear plate 19 by adhesive.

[0061] 2) Gas system (such as Figure 2 shown):

[0062] The three-way air inlet valve 7, three-way selection valve 8, three-way inlet needle valve 3, and three-way outlet needle valve 4 are all normally closed two-position three-way solenoid valves. This valve has three interfaces, namely the air inlet, the air outlet, and the exhaust port. The exhaust port is located at the top of the valve. When the valve is closed and not powered on, the air inlet is sealed by a sealing gasket, and the gas cannot pass through, while the air outlet and the exhaust port are connected in air path; when the valve is powered on, the air inlet and the air outlet are connected, while the exhaust port is not connected; the two-way vacuum valve 6 and the two-way air inlet valve 13 are normally closed two-position two-way solenoid valves, which only have an air inlet and an air outlet. When the valve is closed and not powered on, the air inlet and the exhaust port are not connected in air flow, and when the valve is powered on and opened, the air inlet and the air outlet are connected. The air path connection is as follows Figure 2 As shown, the air outlet of the two-way vacuum valve 6 is connected to the vacuum pump 9, and the air inlet is connected to the exhaust port of the three-way selection valve 8, the air outlet of the three-way selection valve 8 is connected to the needle seat 24, the air inlet of the three-way selection valve 8 is connected to the air outlet of the three-way air inlet valve 7, the exhaust port of the three-way air inlet valve 7 is connected to the outlet of the spectrometer 17, and the inlet of the three-way air inlet valve 7 is connected to the air sampling pump 10; the air outlet of the three-way needle inlet valve 3 is connected to the upper air chamber 202 of the square cylinder 20, the air inlet thereof is connected to the three-way joint, and the exhaust port is connected to the atmosphere; the air outlet of the three-way needle retreat valve 4 is connected to the lower air chamber 203 of the square cylinder 20, the air inlet thereof is connected to the other interface of the three-way joint, and the exhaust port is connected to the atmosphere;

[0063] Figure 2The structure of the needle injection system is also shown. Both ends of the needle seat 24 are externally threaded, and the middle is a hexagonal prism. The upper external thread is connected to the cylinder shaft, and the lower external thread is connected to the double-hole injection needle 25 (side hole needle) with internal threads. There is a 90-degree gas passage hole connecting the center of the needle external thread inside the needle seat 24 and the center of one of the faces of the hexagonal prism. There is also a gas pipe joint (intake pipe 12) on the prism surface. The adjusting rod 26 is in the shape of a long rod, one end of which is an external thread, and the other end is a hexagonal prism with an internal thread; the bottle blocking piece 27 is in the shape of a rectangular metal sheet, and there is a small round hole in the center of the sheet that allows the side hole needle to pass smoothly, and this small hole also has the function of straightening the needle; there is a screw hole in the middle of the left and right ends of the bottle blocking piece 27, and the screw passes through the bottle blocking piece 27 and is screwed into the internal thread of the adjusting rod 26. A hexagonal nut is first screwed into the external thread of the adjusting rod 26 as a lock, and then the external thread of the adjusting rod 26 is passed through the fixing hole on the cylinder arm 21 and screwed into the threaded fixing hole on the square cylinder 20. Figure 3 The structure of the cylinder arm 21 is shown. When the height of the bottle blocking piece 27 needs to be adjusted, the fixing screws and locks are loosened first, and then the hexagonal prism on the adjusting rod 26 is rotated. When the adjusting rod 26 is rotated clockwise, the external thread of the adjusting rod 26 is screwed into the threaded hole of the cylinder, and the position of the adjusting piece is raised. When the adjusting rod 26 is rotated counterclockwise, the external thread of the adjusting rod 26 is screwed out of the threaded hole of the cylinder, and the position of the adjusting piece is lowered. When the needle is in the uppermost position, the needle tip is just hidden in the small hole of the bottle blocking piece 27, and the positions of the adjusting rods 26 on both sides are at the same height, and then the locks and screws are tightened in sequence.

[0064] After the compressed air passes through the air pressure regulating valve 5 and the three-way joint, it supplies air to the three-way needle valve 3 and the three-way needle valve 4. Figure 2 As shown, when needle insertion is required, the three-way needle inlet valve 3 is opened, and the compressed gas enters the upper air chamber 202 through the upper air inlet of the square cylinder 20, while the lower air chamber 203 is at normal pressure. The compressed gas pushes the piston 201 and the cylinder shaft inside the cylinder to move downward, and drives the needle seat 24 and the side hole needle to move downward together. The needle pierces the rubber sealing ring of the head space bottle below and extends into the head space bottle. At this time, the three-way needle inlet valve 3 is closed, so that the compressed gas in the upper air chamber 202 is discharged through the exhaust port of the three-way needle inlet valve 3, keeping the upper air chamber 202 at normal pressure, and completing the needle insertion action. When the needle needs to be withdrawn, the three-way needle withdrawal valve 4 is opened, and the compressed gas enters the lower air chamber 203 of the square cylinder 20, pushing the piston 201 and the cylinder shaft to move upward, and driving the needle seat 24 and the side hole needle to move upward. At this time, the side hole needle is in the head space bottle. Due to the friction between the rubber sealing pad in the head space bottle cover and the needle, the head space bottle is also driven to move upward. When the head space bottle cover contacts the bottle blocking piece 27, the bottle blocking piece 27 prevents the head space bottle from moving further upward, so that the side hole needle overcomes the friction resistance and is pulled out of the rubber sealing pad and the needle tip is hidden in the bottle blocking piece 27.

[0065] Figure 3The cross-sectional view of the cylinder arm 21 is shown. The square cylinder fixing hole is used to fix the square cylinder, and the large circular hole in the middle allows the cylinder shaft and the connected needle seat 24 to pass smoothly. There is a cylinder arm 21 locking hole at the left end of the cylinder arm 21, through which the cylinder arm 21 can be exactly sleeved on the side shaft rod 23, and the cylinder arm 21 can slide up and down on the side shaft rod 23. When sliding to a suitable height position, a long screw can be screwed into the locking threaded hole to clamp and lock the cylinder arm 21 on the side shaft rod 23. There is also a locking hole notch on the other side of the corresponding locking hole, which can make the locking clamping deformation force evenly distributed and easier to clamp and tighten.

[0066] 3) Positioning system

[0067] Figure 4 The structural diagram of the gear plate 19 is listed, Figure 5 The structure diagram of the disc 181 on the sample disc 18 is listed. Figure 4 As shown, the gear plate 19 is in the shape of a disc, with a large circular hole in the center and four chassis fixing holes. The gear plate 19 can be locked on the disc seat 28 by screws, and the disc seat 28 is then locked on the central axis by long screws. A circle of teeth is evenly distributed on the outer ring of the gear plate 19. A slide groove 191 is processed in the shape of an involute on the front of the gear plate 19. A cylindrical starting magnet 192 and a final magnet 193 are buried at the starting position of the outer ring of the slide groove 191 and the end position of the inner ring of the slide groove 191, respectively, to indicate the starting position and the end position of the slide groove 191. A capacitive gate circuit 194 with adhesive backing is pasted in the middle of the inner part of the slide groove 191, which can be used to indicate the displacement of the slider in the slide groove 191.

[0068] Figure 5 The structure of the upper disc 181 of the sample disc 18 is shown in FIG. There is a large circle (sleeve hole 184) and four screw fixing holes in the middle of the upper disc 181. The disc can be fixed to the disc seat 28 with screws, and then the disc seat 28 is fixed to the sleeve with long screws. The structure of the middle disc 182 is the same as that of the upper disc 181, and the bottom disc is the same as that of the upper disc 181 except that there is no bottle position hole 185.

[0069] Figure 6 It is a schematic diagram of the cross-sectional structure of the pan seat 28. The upper pan 181 or the bottom pan can be fixed to the pan seat 28 by screws, the sleeve passes through the locking hole, and the sleeve of the sample pan 18 can be clamped and locked on the pan seat 28 by screwing the locking pin into the locking pin hole.

[0070] The structure of the sample tray 18 is as follows Figure 1 As shown, the sample plate 18 is mainly composed of an upper plate 181, a middle plate 182, a lower plate 183, a plate sleeve, a plate seat 28, a single-pass copper column, a double-pass copper column and fixing screws. Figure 5As shown, there are four screw holes on the outer ring of the upper disk 181, and the upper part of the upper disk 181 is connected to the single-pass copper column by screws, and the upper disk 181 is clamped between the screws and the single-pass copper column, the middle disk 182 is clamped by the threaded single and double-pass copper columns of the single-pass copper column, and the bottom disk is clamped by screws and double-pass copper columns. The four single-pass copper columns and double-pass copper columns and locking screws connect the outer rings of the three disks, and in the center of the disk, the upper disk 181 and the bottom disk are fixed to the disk seat 28 with screws, and then the disk shaft sleeve is passed through the upper disk seat 28, the middle disk 182 and the lower disk seat 28, and is locked to the disk shaft seat by the screws of the upper disk seat 28 and the lower disk seat 28.

[0071] The structures of the central axis rod 22 and the side axis rod 23 are as follows: Figure 1 As shown in . The components of the middle shaft include a bearing seat 29, a bearing 30, a shaft cylinder 31, a shaft seat hole, a middle shaft rod 22, a keyway and a hand-tightened locking pin. The components of the side bearing include a bearing seat 29, a bearing 30, a shaft cylinder 31, a shaft seat hole, and a side shaft rod 23; the bearing seats 29 of the two shafts have the same structure, with an opening at the top, a cylindrical shape, and a hollow center. There is an external threaded interface at the bottom, which can be screwed onto the bottom plate 32 through the external threaded interface. There is an annular depression at the bottom of the bearing sleeve connected to the inside of the bottom plate 32, which is convenient for the outer ring of the bearing seat 29 to reduce the contact area between the shaft and the bottom plate 32, keep the bearing seat 29 in close contact with the bottom plate 32 and perpendicular to the bottom plate 32; there are two small round holes on the middle side wall of the bearing seat 29, which is convenient for using a rod-shaped tool (such as a screwdriver) to reach into the hole to help tighten or loosen the bearing seat 29 thread and remove it. The assembly structure of the middle shaft and the side shaft is also shown in Figure 1 As shown, the bottom end of the central axis rod 22 is sequentially matched with a bearing, a shaft cylinder 31 and another bearing, the inner ring of the bearing is in close contact with the central axis rod 22, and the shaft cylinder 31 is a hollow cylindrical shape, the two end faces of the shaft cylinder 31 are in contact with the inner ring end face of the bearing, but not in contact with the central axis rod 22, supporting the upper and lower bearings, keeping the central axis rod 22 vertical, and allowing the central axis rod 22 and the inner ring of the bearing and the shaft cylinder 31 to rotate smoothly at the same time. Then, the central axis rod 22 with the bearing and the shaft cylinder 31 is pressed into the bearing seat 29, so that the outer rings of the upper and lower bearings are in close contact with the inner wall of the bearing seat 29, so that the central axis rod 22 can rotate smoothly in the bearing seat 29. The assembly method of the side shaft is the same as that of the central shaft. There is also a long rounded groove on the central axis 22, in which a standard rounded flat key can be placed. After the rounded flat key is placed inside, half of its height protrudes from the surface of the axis. When the disk sleeve of the sample disk 18 is placed on the central axis, the protruding rounded flat key can be stuck in the notch on the disk sleeve, and the hand-tightened locking pin can be screwed into the top of the disk sleeve to accurately position the sample disk 18 on the central axis 22.

[0072] Positioning principle: During assembly, the cylinder arm 21 and the sliding arm 34 are coaxially fixed on the side axis rod 23, the vertical position of the needle is consistent with the vertical position of the guide head 33, and the sample plate 18 and the gear plate 19 are also coaxially fixed on the central axis rod 22. When positioning is required, the single chip microcomputer 2 detects the position of the guide head 33 in the slide arm 34 based on the starting position probe on the slide arm 34. When the position does not meet the specific position, the single chip microcomputer 2 drives the planetary reduction motor 35 to rotate, and the teeth 36 on the motor 35 drive the gear disk 19 to rotate, and the sample disk 18 fixed on the central axis rotates coaxially. Moreover, since the guide head 33 on the slide arm 34 is in the slide groove 191 of the gear disk 19, the slide groove 191 distributed in an involute line will push the guide head 33, and the guide head 33 pushes the slide arm 34, and the slide arm 34 pushes the side shaft rod 23 to rotate. The side shaft rod 23 drives the coaxially fixed cylinder arm 21 to rotate, and the cylinder arm 21 drives the needle head to move to the top of the corresponding slide groove 191. When the guide head 33 slides in the slide groove 191, the capacitive displacement sensor in the guide head 33 records its displacement distance. When the moving distance is reached, the movement stops, so that the needle position stops at the corresponding hole position on the sample disk 18, and the positioning of the needle position is completed.

[0073] Moreover, since the grooves of the gear plate 19 are involute distribution, the speed of the guide head 33 in the outer and inner circles of the slide groove 191 will be very different during gear transmission. The single-chip computer 2 system will record the position of the plate according to the involute function, adjust the speed of the motor 35, and control the moving speed of the guide head 33 in the slide groove 191. When it is far away from the target bottle position, it will run at a high speed, and when it is close to the target bottle hole position, it will reduce the speed to prevent the rotation inertia from being too large and affecting the positioning accuracy. After using the capacitive grid positioning, the maximum moving speed can reach 1.8 meters per second, and the displacement resolution can reach 0.02 mm, which can change the speed to quickly and accurately locate the position of the sample bottle.

[0074] 4) Main process of function realization

[0075] When the planetary gear motor 35 rotates to the corresponding sample bottle position,

[0076] (1) Batch isotope gas sample preparation function is realized: manually rotate the stroke adjustment nut 37 and the upper lock nut clockwise downward, so that when the square cylinder piston 201 moves to the lowest position, when the double-hole injection needle 25 is inserted into the sample bottle, only the lower side hole is located in the head space bottle, and the upper side hole of the needle tube does not enter the head space bottle, rotate the stroke adjustment nut 37 counterclockwise and the lock nut clockwise at the same time, the two nutes are locked on the square cylinder shaft rod by force, and the stroke of the square cylinder 20 and the double-side hole injection needle 25 is set. Open the vacuum pump 9 for preheating, open the three-way needle valve 3, and the air pressure regulating valve 5 compresses the gas into the upper air chamber 202 of the square cylinder, and drives the needle to penetrate into the vacuum bottle. Due to the set stroke, the side hole on the upper part of the double-hole injection needle 25 does not enter the head space bottle, close the three-way needle valve 3 to allow the compressed gas in the upper air chamber 202 to be discharged from the exhaust port of the three-way needle valve 3, open the two-way vacuum valve 6 and the three-way selection valve 8, and the gas in the sample bottle is pumped away under the suction of the vacuum pump 9. After a certain period of time, when the required vacuum degree is reached, close the two-way vacuum valve 6, open the gas sampling pump 10 and the three-way air inlet valve 7, and the gas sampling pump 10 pumps the isotope gas sample in the sample bag 11 into the head space bottle, and then close the gas sampling pump 10 and the three-way selection valve 8. The air inlet valve 7 can cycle the two actions of vacuuming and collecting gas several times so as to use the sample gas to flush the pipeline and the headspace bottle. When the cycle cleaning is completed, the headspace bottle is filled with isotope sample gas. At this time, the three-way air inlet valve 8 and the two-way vacuum valve 6 are closed, and the three-way needle valve 4 is opened. The compressed air is fed into the lower air chamber 203, driving the cylinder shaft to move upward. The friction between the needle tube and the rubber sealing pad drives the sample bottle to move upward. The bottle cap is blocked by the bottle blocking piece 27, so that the needle is pulled out of the sample bottle. The sample bottle falls back to its position under the action of gravity. When the cylinder shaft returns to the top, the three-way needle valve 4 is closed, and the compressed gas in the lower air chamber 203 is discharged from the exhaust port of the three-way needle valve 4, completing the preparation of the sample bottle gas. Then, under the action of the planetary reduction motor 35, it rotates to the next bottle position to start transferring the gas in the sample gas bag 11 to the headspace bottle. After the preparation of all samples in a batch is completed, all valves and pumps are in the closed state, and the two-hole sampling needle 25 has been pulled out of the head space bottle. At this time, it is necessary to open the two-way vacuum valve 6 and the three-way selection valve 8. At this time, the air in the atmosphere enters the vacuum pump 9 along the gas channel from the two-hole sampling needle 25 to balance the pressure, preventing the pump tube from returning oil due to the vacuum in the vacuum pump 9. Maintain this state for about half a minute and then close the two-way vacuum valve 6 and the three-way selection valve 8 to complete the sample preparation.

[0077] (2) Automatic injection of isotope gas samples: Set the parameters of the electronic gas pressure control table 14, set its lower value to a pressure slightly higher than the atmospheric pressure of about 0.1 KPa, set its upper value to about 4 KPa, and set the value of the nitrogen pressure regulating valve 15 to about 0.1 MPa. After setting, it can be stored for long-term use. The electronic air pressure control meter 14 automatically controls the opening and closing of the two-way filling valve 13. When the pressure in the dilution buffer bag 16 is lower than the set low value of 0.1 KPa, the two-way filling valve 13 is opened, and the high-purity nitrogen enters the dilution buffer bag 16 through the nitrogen pressure regulating valve 14, the two-way filling valve 13 and the four-way connector to increase the internal pressure. When it increases to the set high value of 4 KPa, the electronic air pressure control meter 14 closes the two-way filling valve 13, so that the pressure in the dilution buffer bag 16 is always maintained between the set low pressure value and the high pressure value, and then adjusts the stroke adjustment 37 and the lock 37 to the uppermost part and locks them, so that the two side holes of the double-hole injection needle 25 can be located inside the head space bottle when the needle is inserted. Since the isotope spectrometer 17 has a self-priming pump inside to provide air intake power, when the needle is not inserted into the head space bottle, the spectrometer 17 takes in air from the lower side hole of the double-hole injection needle 25. When the automatic injection is officially started, the system is positioned and the needle is inserted as described above, and the isotope spectrometer 17 sucks air and injects samples through the lower side hole of the double-hole injection needle 25. As the injection continues, the pressure in the head space bottle will drop, and the side of the double-hole injection needle 25 is connected to the dilution buffer bag 16 through a four-way connector. The dilution buffer bag 16 contains high-purity low-pressure nitrogen, which is injected through the air intake. The upper side hole of the pipeline and the double-hole injection needle 25 enters the headspace bottle, and gradually supplements and dilutes the gas sample in the headspace bottle. Since the supplemented high-purity nitrogen does not contain the gas isotope component to be detected, and the isotope spectrometer 17 measures the ratio of different isotope components of specific gas in the gas sample, the dilution will not affect the determination of its ratio. When the determination reaches the set time length, the single-chip microcomputer 2 pulls the needle out of the headspace bottle as mentioned above and moves it to another sample bottle. During this process, the low-pressure nitrogen in the gas buffer bag 16 flushes the air intake pipeline. When the next injection time is reached, the single-chip microcomputer 2 controls the needle and injection again until all the set sample injections are completed. The injector distinguishes different gas samples by the length of the time interval, and matches the analysis result of the isotope spectrometer 17 by the injection time, so that automatic injection can be achieved without special software control, and can be used in conjunction with any isotope spectrometer with an accurate clock for injection, and has a wide range of adaptability.

[0078] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A gas isotope spectrometer automatic sample injector, characterized in that: It includes a control system, an air circuit system, a positioning system and a base plate; the positioning system is electrically connected to the control system; the positioning system is fixed on the base plate; The gas circuit system includes a gas cylinder, an injection device, a gas cylinder driving device, a two-way vacuum valve, a three-way air inlet valve, a three-way selection valve, a vacuum pump, a gas sampling pump, a sample gas bag, a two-way inflation valve, an electronic air pressure control meter, a dilution buffer bag, and a nitrogen pressure regulating valve; The three-way air inlet valve is connected to the vacuum pump through the two-way vacuum valve, the three-way air inlet valve is connected to the sample gas bag through the gas sampling pump, the three-way air inlet valve is connected to the isotope spectrometer, and the three-way air inlet valve is connected to the injection device through the three-way selection valve; the injection device, the electronic air pressure control table, the dilution buffer bag, and the two-way inflation valve are connected through a four-way connector; the two-way inflation valve is connected to the nitrogen pressure regulating valve, and the two-way inflation valve is electrically connected to the electronic air pressure control table; The cylinder is fixed on the positioning system and connected to the cylinder driving device; The injection device is connected to the cylinder; The two-way vacuum valve, three-way air inlet valve, three-way selection valve, vacuum pump, air sampling pump, two-way charging valve, electronic air pressure control meter, nitrogen pressure regulating valve, and cylinder driving device are electrically connected to the control system respectively; The cylinder driving device comprises: a three-way needle inlet valve, a three-way needle return valve and an air pressure-stabilizing valve; the three-way needle inlet valve air outlet and the three-way needle return valve air outlet are respectively connected to the cylinder; the three-way needle inlet valve air inlet and the three-way needle return valve air inlet are respectively connected to the air pressure-stabilizing valve air outlet through a three-way joint; the air pressure-stabilizing valve air inlet is connected to compressed air; the three-way needle inlet valve, the three-way needle return valve and the air pressure-stabilizing valve are respectively electrically connected to the control system; The cylinder comprises: a cylinder barrel, a piston, and a cylinder shaft; the piston divides the cylinder into an upper air chamber and a lower air chamber; The upper air chamber is communicated with the air outlet of the three-way needle valve, and the lower air chamber is communicated with the air outlet of the three-way needle valve; One end of the cylinder shaft is connected to the piston, and the other end is connected to the injection device; A stroke adjustment knob is installed on the top of the cylinder; The injection device comprises: a needle seat and a double-hole injection needle, one end of the needle seat is connected to the cylinder shaft, and the other end is connected to the double-hole injection needle, and the interior of the needle seat is connected to the three-way selection valve; the double-hole injection needle is connected to the four-way connector; The positioning system comprises: a sample plate, a gear plate, a cylinder arm, a central axis device, a side axis device, a sliding arm, a gear and a power device; The sample tray and the gear tray are both fixedly mounted on the central axis device, and the sample tray is located on the top of the gear tray; the sample tray is provided with bottle holes arranged in an involute line; and the gear tray surface is provided with slide grooves corresponding to the bottle holes; The central axis device and the side axis device are both vertically mounted on the bottom plate; The slide arm and one end of the cylinder arm are both mounted on the side axis device, and the slide arm is parallel to the cylinder arm; a guide head is fixedly arranged on the slide arm, and the guide head slides in the slide groove; the cylinder is fixed on the cylinder arm; The gear is connected to the power device, and the gear is matched with the gear plate.

2. The automatic sample injector for gas isotope spectrometer according to claim 1, characterized in that: The slide arm comprises: an upper slide and a lower slide, the upper slide and the lower slide are fixedly mounted on the side axis device, the upper slide and the lower slide are PCB circuit boards with components welded thereon, and the guide head is arranged on the upper slide; The upper slide and the lower slide are electrically connected to the control system via conductive wires respectively; The starting position and the ending position of the slide slot are respectively provided with a starting magnet and a final magnet; the upper slide is provided with a starting probe and a final probe; the starting probe and the final probe are both electrically connected to the control device.

3. The automatic sample injector for gas isotope spectrometer according to claim 2, characterized in that: The upper slide is welded with a capacitive grid displacement sensor, the head of the capacitive grid displacement sensor is located in the guide head, and a capacitive grid circuit is pasted inside the slide groove; the capacitive grid displacement sensor is powered by the upper slide.

4. The automatic sample injector for gas isotope spectrometer according to claim 2, characterized in that: The central axis device comprises: a central axis bearing portion and a central axis rod; the central axis rod is fitted in the central axis bearing portion; and the sample plate and the gear plate are both fixedly sleeved on the central axis rod; The paraxial device comprises: a paraxial bearing part and a paraxial rod; the lower part of the paraxial rod is fitted in the paraxial bearing part; and the upper slide plate and the lower slide plate are both fixedly sleeved on the paraxial rod; Furthermore, the central axis bearing portion and the side axis bearing portion are both vertically mounted on the bottom plate.

5. The automatic sample injector for gas isotope spectrometer according to claim 4, characterized in that: The central axis bearing component and the side axis bearing component are the same, both comprising: a bearing seat, a bearing and a shaft cylinder; the bearing seat is open at the top, cylindrical, hollow, and has an external threaded interface at the bottom, which is screwed to the base plate through the external threaded interface; the bottom of the bearing sleeve is connected to the base plate and there is an annular depression inside; there are two bearings, which are located at the upper and lower ends of the bearing seat respectively; the shaft cylinder is a hollow cylinder with an inner diameter larger than the inner diameter of the bearing, and is located between the two bearings, and the two end faces of the shaft cylinder are in close contact with the inner ring end faces of the upper and lower bearings; the central axis rod and the side axis rod pass through the inner holes of the bearing and the shaft cylinder.

6. The automatic sample injector for gas isotope spectrometer according to claim 4, characterized in that: The sample plate and the gear plate are mounted on the central axis through a plate seat, and the plate seat includes: a locking hole located in the center, screw holes located in the four corners, and a locking nail hole located on one side, a locking hole notch is provided on one side of the locking hole, and a penetrating locking hole through groove is provided on the other side corresponding to the locking hole notch, and the locking nail hole is perpendicular to the locking hole through groove; screw holes consistent with the screw holes are provided on the gear plate and the sample plate.

7. The automatic sample injector for gas isotope spectrometer according to claim 1, characterized in that: The sample plate comprises an upper plate, a middle plate, a lower plate, a single-pass copper column, a double-pass copper column and fixing screws; the middle plate is arranged between the upper plate and the lower plate, and is connected by the single-pass copper column, the double-pass copper column and the fixing screws; the upper plate and the middle plate have the same structure, a central axis hole is arranged at the center position, and bottle position holes arranged in an involute manner are arranged on the plate surface; except that the bottle position holes are not arranged on the lower plate, the other structures are the same as those of the upper plate.

8. The automatic sample injector for gas isotope spectrometer according to claim 1, characterized in that: The control system includes a control panel and a single-chip microcomputer. The control panel is connected to the single-chip microcomputer by wiring. The positioning system, two-way vacuum valve, three-way air intake valve, three-way selection valve, vacuum pump, air sampling pump, two-way charging valve, electronic air pressure control meter, nitrogen pressure regulating valve, and cylinder drive device are respectively connected to the single-chip microcomputer by conductive wires and are controlled by the program in the single-chip microcomputer.

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