Liquid adding device for COD (Chemical Oxygen Demand) analytical instrument

Abstract

The invention discloses a liquid adding device for a COD (Chemical Oxygen Demand) analytical instrument, and relates to the technical field of analytical instruments. In the structure, a plurality of digestion groups are sequentially arranged along the X-axis of a rack, and an operation port of an instrument is formed in the Y-axis direction of the rack; each digestion group comprises a plurality of digestion positions which are arranged in two rows and N columns, and each digestion group comprises a lower digestion cup and an upper condensation pipe which are arranged on each digestion position; a plurality of condensation pipes of each digestion group form a condensation module; a plurality of digestion cups of each digestion group form a digestion module; each condensation module is correspondingly connected with a moving end of a first vertical displacement mechanism moving in the Z-axis direction of the rack; the first vertical displacement mechanism corresponding to each condensation module is independently controlled by a controller; through the structure, each digestion group does not interfere with each other in the experiment process, and the use efficiency of the instrument is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of analytical instruments, and particularly relates to a liquid adding device for a COD analyzer. Background Art

[0002] The determination process of chemical oxygen demand based on the dichromate method is as follows: A blank control group and a digestion group are established. The digestion group is filled with the water sample to be tested, and the blank control group is filled with pure water or a blank reagent. Then, a mercury sulfate solution and a potassium dichromate standard solution need to be added to the digestion group and the blank control group in sequence. A condenser is connected to the above-mentioned digestion group, and then a silver sulfate - sulfuric acid solution is added to the condenser. After the reaction, the COD of the water sample to be tested is calculated after titrating the blank control group and the digestion group with a ferrous ammonium sulfate standard solution.

[0003] Existing COD analyzers include digestion cups and condensers. Among them, except for the digestion cup at the blank control position, a condenser is correspondingly provided above each of the other digestion cups at the digestion positions (filled with the water sample to be tested). During the experiment, the condenser needs to be controlled to descend and connect with the digestion cup.

[0004] In existing COD analyzers, generally, the number of digestion positions is set to 32 or 40, and the layout of the digestion positions has a rotary disk type (reference can be made to Chinese Patent Document 202020328325.3) or a linear array layout type (reference can be made to Chinese Patent Document 202220293727.3). Among them, each digestion position is provided with a digestion cup below and a condenser above the digestion cup.

[0005] In the rotary disk type structure, one digestion group is on the rotary disk, and one digestion group includes multiple digestion positions. There are many sample positions in each group. Since the whole group is controlled together during the experiment, when the condenser descends and connects with the digestion cup, the digestion cups in this whole group that are not filled with water samples cannot continue the experiment, which is not flexible enough and reduces the overall experimental efficiency. The linear array layout is relatively more flexible than the rotary disk. However, in existing equipment, the layout of the linear array layout is as Figure 5 shown. There are four digestion groups, with 8 digestion positions in each digestion group, in a 2X2 layout, divided into two rows. Each row of digestion groups is controlled separately, thus forming four independent controlled digestion groups A, B, C, and D. The design of this structure will cause the following interferences: When the condenser of digestion group A descends, it intercepts the path for manual placement, resulting in a situation where the digestion cup cannot be placed, that is, the front row will block the back row, which also causes that when digestion group A works first, digestion group B cannot perform the sample injection work. Summary of the Invention

[0006] The object of the present invention is to provide a liquid adding device for a COD analyzer, and the layout structure of its digestion group enables efficient experiments to be carried out and avoids interference between each module.

[0007] To achieve the above object, the technical solution adopted by the present invention is as follows: A liquid adding device for a COD analyzer includes a frame and a plurality of digestion groups arranged on the frame. The plurality of digestion groups are arranged in sequence along the X-axis of the frame, and the operation port of the instrument is opened in the Y-axis direction of the frame; each digestion group includes a plurality of digestion positions arranged in 2 rows and N columns. Each digestion group includes a digestion cup located below and a condenser tube located above at each digestion position; the plurality of condenser tubes of each digestion group constitute a condensation module; the plurality of digestion cups of each digestion group constitute a digestion module; Each condensation module is correspondingly connected to a mobile end of a first vertical displacement mechanism moving in the Z-axis direction of the frame; the first vertical displacement mechanism corresponding to each condensation module is independently controlled by a controller; A liquid adding module is further provided on the frame. The liquid adding module includes a lateral displacement mechanism and a liquid adding arm. The moving part of the lateral displacement mechanism is rotatably connected to the liquid adding arm, and the liquid adding arm is connected to the driving end of a rotating motor; the moving part on the lateral displacement mechanism moves along the X-axis direction; a drip nozzle for dripping liquid downward is provided on the liquid adding arm; the liquid adding module is arranged between two rows of digestion positions to add liquid to the condenser tubes and digestion cups in the front and rear rows.

[0008] As an implementation scheme, a positioning module is further included. The positioning module includes a linear positioning sensor and an interface positioning sensor; the linear positioning sensor is arranged to collect the lateral displacement position of the liquid adding arm, and the interface positioning sensor collects the rotation position of the liquid adding arm; when both the interface positioning sensor and the linear positioning sensor collect signals, the controller controls the liquid adding arm to perform a dripping operation.

[0009] As an implementation scheme, the first vertical displacement mechanism is a lead screw and nut structure, which includes a motor, a lead screw, and a nut; the output end of the motor is connected to the lead screw, the nut is threadedly connected to the lead screw, and the nut is provided with a limiting member to limit the rotation of the nut; the nut is connected to the condensation module.

[0010] As an implementation scheme, the liquid adding module further includes a second vertical displacement mechanism whose mobile end moves in the Z-axis direction. The moving part of the lateral displacement mechanism is rotatably connected to the liquid adding arm through the second vertical displacement mechanism. The second vertical displacement mechanism is arranged on the moving part of the lateral displacement mechanism, and the mobile end of the second vertical displacement moves is rotatably connected to the liquid adding arm, so that the height of the liquid adding arm can be raised and lowered; a liquid adding module is arranged between two rows of digestion positions; under the lifting control of the second vertical displacement mechanism, the liquid adding arm descends to add liquid to the digestion module at a lower height, and the liquid adding arm rises to add liquid to the condensation module at a higher height.

[0011] As an implementation solution, several condensation tubes of the condensation module are jointly arranged on a condensation support. The condensation support includes a first frame body and a second frame body that respectively correspond to placing two rows of condensation tubes. The first frame body and the second frame body are separated and arranged, and an avoidance channel for avoiding the liquid addition module is formed therebetween; a connecting member is provided between the first frame body and the second frame body; when the condensation support moves up and down under the action of the controller driving the first vertical displacement mechanism, the connecting member connects the first frame body and the second frame body, so that the condensation support moves up and down as a whole; when the liquid addition arm performs Z-axis displacement and X-axis displacement actions, the liquid addition arm passes through the avoidance channel, and the connecting member does not block the avoidance channel.

[0012] As an implementation solution, the connecting member is a portal frame, and the bottom of the portal frame is connected to the first frame body and the second frame body; when the condensation tubes are placed on the first frame body and the second frame body, a space for the liquid addition arm to add liquid is left between the top of the portal frame and the tube orifices of the condensation tubes; the liquid addition module moves between adjacent digestion groups through the avoidance channel.

[0013] As an implementation solution, the condensation support is located below the tube orifices of the condensation tubes, the connecting member is a connecting rod, and the two side edges of the first frame body and the second frame body in the X-axis direction are connected by the connecting rod, and an avoidance channel is formed among the first frame body, the second frame body, and the connecting rod; the second vertical displacement mechanism can pass through the square avoidance channel and move in the X-axis direction within the range of the square avoidance channel; under the action of the second vertical displacement mechanism, the liquid addition arm has three working heights, namely the initial height from low to high, the digestion liquid addition height, and the condensation liquid addition height; When the liquid addition module moves from one digestion group to another digestion group, the liquid addition arm is at the initial height.

[0014] As an implementation solution, the linear positioning sensor is an optoelectronic sensor arranged on the moving part of the lateral displacement mechanism. The optoelectronic sensor is matched with a linear code tooth, and notches are provided on the linear code tooth. The number of notches corresponds to the digestion positions one by one. When the optoelectronic sensor follows the moving part to move to the notch, the optical signal passing through the notch is collected.

[0015] As an implementation solution, the interface positioning sensor includes a reflection sensor and a groove-shaped optoelectronic switch; a reflection sensor located below the drip nozzle is provided on the liquid addition arm for adding liquid to the digestion cup, which is used to detect whether there is a digestion cup or whether it is aligned with the digestion cup; a groove-shaped optoelectronic switch is provided on one side of the liquid addition arm for adding liquid to the condensation tube. The liquid addition arm rotates relative to the groove-shaped optoelectronic switch, and a first rotating code tooth and a second rotating code tooth are respectively provided on the corresponding two sides of the liquid addition arm; when the first rotating code tooth and the second rotating code tooth are respectively located at the positions blocking the groove-shaped optoelectronic switch, the groove-shaped optoelectronic switch collects signals, and it is detected that the drip nozzle of the liquid addition arm is aligned with the front row of condensation tubes or the rear row of condensation tubes.

[0016] As an implementation, there are a number of initial working positions that are the same as the number of digestion groups. The position data corresponding to the initial working positions is written into the controller. The initial working position means that the liquid adding arm is at the initial height, initial angle, and the initial X-axis position corresponding to the digestion group. The initial angle means that the liquid adding arm is at the working position where it does not add liquid to the digestion cup or the condenser tube. The control method for adding liquid to two digestion groups is as follows: When the liquid adding arm needs to move from one digestion group to the next digestion group, the liquid adding arm is at the initial working position of the previous digestion group. At this time, the lateral displacement mechanism receives the controller's instruction, and the liquid adding arm moves in the X-axis to the initial working position of the next digestion group, and then performs the liquid adding work for the next digestion group.

[0017] As an implementation, a water receiving tray is also provided at the mobile end of the lateral displacement sensor. At the initial rotation position of the liquid adding arm, the water receiving tray is located below the nozzle of the liquid adding arm.

[0018] As an implementation, the liquid adding arm includes a liquid adding arm housing and a nozzle provided on the liquid adding arm housing. One end of the liquid adding tube is communicated with the liquid outlet of the peristaltic pump, and the other end passes through the liquid adding arm housing and is communicated with the nozzle. The liquid inlet of the peristaltic pump is communicated with the reagent bottle through a pipeline.

[0019] Compared with the prior art, the present invention has the following beneficial effects: The present invention adopts a 2X4 array digestion position layout. This layout enables each digestion group to be used independently for real-time analysis experiments on samples sent at any time, and there will be no problem that the already experimented digestion groups interfere with the un-experimented digestion groups, resulting in the inability of the un-experimented digestion groups to perform real-time analysis tests.

[0020] In a COD analyzer based on the dichromate method, the blank control group and the digestion group use the sample cup as a carrier, and highly toxic and strongly corrosive solutions such as mercuric sulfate, silver sulfate, and concentrated sulfuric acid are added to the sample cup or the condenser tube through the nozzle provided on the liquid adding arm. At present, the movement of the liquid adding arm of such instruments mostly uses the motor to directly rotate a certain number of steps to complete the nozzle alignment function. When the motor torque is insufficient or the movement is interfered, the motor loses steps, resulting in the nozzle not being able to be aligned, so that the highly toxic and strongly corrosive solution released from the nozzle leaks to other equipment on the instrument rack, posing a safety hazard to the analysts and also making the instrument easily damaged. In the present invention, by setting a linear positioning sensor and an interface positioning sensor to collect positions, the working state of the liquid adding arm is controlled to ensure alignment with the bottle mouth.

[0021] In the present invention, the traditional upper liquid adding module and the lower liquid adding module are combined into one. This design simplifies the overall structural dimensions and does not affect the working efficiency of liquid adding. At the same time, in the present invention, the structure for controlling the lifting of the condensation module is a lead screw nut pair structure. Such a structure arranged on the back plate will not increase the overall size of the instrument and makes the space for manually placing the condensation tube and digestion cup clean, without affecting the operation of the experimenter. However, such a structure will cause interference between the liquid adding arm in the liquid adding module and the condensation support when the digestion cup is docked with the condensation tube. Therefore, the present invention designs the condensation support and its corresponding control logic to avoid the interference problem. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 FIG. is a schematic structural diagram of a COD analyzer in Embodiment 1; Figure 2 FIG. is a schematic structural diagram of the upper liquid adding module / lower liquid adding module; Figure 3 FIG. is a schematic structural diagram of the first vertical displacement mechanism in Embodiment 2; Figure 4 FIG. is a schematic structural diagram of the liquid adding module in Embodiment 3; Figure 5 FIG. is a control layout diagram of the digestion group in the prior art; Figure 6 FIG. is a control layout diagram of the digestion group in Embodiment 1; Figure 7 FIG. is a schematic structural diagram of the condensation support in Embodiment 5.

[0023] The reference numerals are as follows: 1 - frame, 2 - condensation module, 3 - digestion module, 4 - upper liquid adding module, 5 - lower liquid adding module, 6 - liquid adding arm, 7 - nozzle, 8 - linear guide rail, 9 - moving part, 10 - rotary motor, 11 - rotary positioning code teeth, 12 - groove type photoelectric switch, 13 - water receiving tray, 14 - linear positioning code teeth, 15 - second vertical displacement mechanism, 16 - reflection sensor, 17 - back plate, 18 - first vertical displacement mechanism, 19 - lead screw nut pair, 20 - condensation support. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0025] On the contrary, this application covers any substitutions, modifications, equivalent methods, and solutions that are defined by the claims and fall within the essence and scope of this application. Further, in order to enable the public to have a better understanding of this application, in the following detailed description of this application, some specific details are described in detail. Those skilled in the art can fully understand this application without the description of these details.

[0026] Embodiment 1 Please refer to Figure 1 and Figure 6 , on the one hand, this embodiment provides a liquid adding device for a COD analyzer, including several digestion groups. The digestion positions of each digestion group adopt a linear structure layout of 2 (rows) × N (columns). Each digestion group includes a digestion cup and a condenser tube located at the digestion position, and the digestion cup is located at the bottom of the condenser tube.

[0027] Several condenser tubes located above in each digestion group form a condenser module 2, and several digestion cups located below in each digestion position form a digestion module 3; that is, each digestion group includes a condenser module 2 and a digestion module 3.

[0028] Based on the above structure, it can be seen that each condenser module 2 has a structure of 2 rows front and back, with several condenser tubes in each row. Among them, each condenser module 2 is independently lifted and lowered by a first vertical displacement mechanism 18.

[0029] The digestion module 3 has a structure of 2 rows front and back, with several digestion cups in each row. Each digestion module 3 corresponds to a temperature control device, so that the controller can independently control the heating and cooling of each digestion module 3; all digestion modules 3 also correspond to a stirring group.

[0030] The structure of the stirring group is an existing mechanism, including a magnetic motor that is movably arranged on the frame 1 and drives the non-contact rotation of the magnetic stirrer, and a magnetic stirrer placed in each digestion tube. The magnetic motor is located below the heating plate, and the magnetic motor moves along the X-axis to output a moving magnetic force to the magnetic stirrer in the digestion tube respectively.

[0031] Specifically, the temperature control device is a heating plate for heating the digestion plate and a fan for air cooling. The heating plate is arranged on the frame 1 and contacts the bottom of the digestion tube during heating. The blowing direction of the fan is towards the digestion tube.

[0032] An upper liquid adding module 4 and a lower liquid adding module 5 are provided between the two rows of digestion positions, that is, one upper liquid adding module 4 and one lower liquid adding module 5 are responsible for the liquid adding work of the digestion modules 3 and condenser modules 2 in their front and back two rows.

[0033] Specifically, the condenser tubes in one condenser module 2 are placed on the condenser bracket 20, and the digestion cups in one digestion module 3 are placed on the digestion brackets. Since the height of the digestion module 3 is fixed, the digestion brackets are designed in two rows. The two rows of frames respectively correspond to the front and back rows of digestion cups, and a displacement channel is formed between the frames of the two digestion brackets to avoid the lower reagent adding module 5.

[0034] Specifically, the height of the condenser module 2 is not fixed and it moves up and down under the control of the first vertical displacement mechanism 18. The condenser bracket 20 is also designed with two rows of frames. The two frames are connected into one body by a connecting frame. Since the height of the connecting frame is lower than the height of the condenser tube orifice and the upper reagent adding module 4 to minimize the height of the frame 1 as much as possible, a displacement channel is formed between the two rows of condenser tubes to avoid the upper reagent adding module 4.

[0035] Such a layout structure ensures that there is no interference between each independently controlled digestion group of the COD analyzer.

[0036] In this embodiment, the overall structural framework of the COD analyzer is described first. The COD analyzer includes a frame 1 and an upper reagent adding module 4, a lower reagent adding module 5, a condenser module 2, and a digestion module 3 arranged on the frame 1.

[0037] The condenser module 2 is arranged above the digestion module 3. The condenser module 2 is connected with a first vertical displacement mechanism 18, and the first vertical displacement mechanism 18 drives the condenser module 2 to move vertically up and down relative to the frame 1 to complete the docking with the digestion module 3. The condenser module 2 is arranged on the condenser bracket 20, and the moving end of the first vertical displacement mechanism 18 is connected to the condenser bracket 20. The upper reagent adding module 4 is used to drip reagents when the digestion module 3 is docked with the condenser module 2.

[0038] The digestion module 3 is arranged on the frame 1 through the digestion bracket. The digestion cup is filled with the sample to be measured. The lower reagent adding module 5 is used to drip reagents when the digestion module 3 is separated from the condenser module 2.

[0039] The working position described in this embodiment refers to the position area on the frame 1 where the digestion cup can be placed for digestion work.

[0040] Specifically, the entire working process of the COD analyzer is as follows: (1) Take 10.0 ml of water sample and blank reagent into the digestion cup, put a magnetic stirrer in the digestion cup, and then place it on the instrument digestion bracket.

[0041] (2) The lower reagent adding module 5 sequentially adds mercuric sulfate solution and 5.00 ml of potassium dichromate standard solution into the digestion cup. While adding the liquid, the magnetic stirring motor directly below the digestion cup will work to drive the magnetic stirrer in the digestion cup to rotate to achieve the purpose of mixing.

[0042] (3) The condensation module 2 moves downward to connect the digestion cup to the lower end of the condenser tube. Then, the upper liquid adding module 4 slowly adds 15 ml of silver sulfate-sulfuric acid solution from the inner tube nozzle at the upper end of the condenser tube. While adding the liquid, the magnetic stirrer motor directly below the digestion cup will operate to drive the magnetic stirrer in the digestion cup to rotate, achieving the purpose of mixing.

[0043] (4) The temperature control device directly below the digestion cup starts to work, maintaining gentle boiling reflux for 2 h since the solution starts to boil (generally digesting at 180 °C for 2 h).

[0044] (5) The digestion cup cools down. After cooling, the upper liquid adding module 4 adds 45 ml of water from the inner tube nozzle at the upper end of the condenser tube to wash the condenser tube.

[0045] (6) After the solution cools to room temperature, the condenser tube moves upward. The lower liquid adding module 5 adds 3 drops of ferroin indicator solution to the digestion cup and titrates with ammonium ferrous sulfate standard solution. The end point is reached when the color of the solution changes from yellow through blue-green to reddish-brown. (While adding the liquid for titration, the magnetic stirrer motor directly below the digestion cup will operate to drive the magnetic stirrer in the digestion cup to rotate, achieving the purpose of mixing).

[0046] In this embodiment, one of the important design points of the liquid adding device of the COD analyzer is that each digestion position is arranged in a structure of 2 (rows) × N (columns), and each digestion group is independently controlled, that is, each condensation module 2 is independently controlled by a first vertical displacement mechanism 18 to move up and down. Please refer to Figure 1 , as a relatively preferred implementation, the digestion positions are arranged in a 2×4 layout, and each group of digestion positions includes 8 digestion positions. In this way, it is divided into four independently controlled digestion groups A, B, C, and D arranged in sequence along the X-axis, as Figure 6 shown. The advantage of such a design is that the operations of the four digestion groups A, B, C, and D do not interfere with each other.

[0047] In this embodiment, the manual operation port of the analyzer is located in the Y-axis direction.

[0048] In this embodiment, one condensation module 2 is separately connected to the first vertical displacement mechanism 18 to control the lifting and lowering. The first vertical displacement mechanism 18 enables the condensation module 2 to displace in the Z-axis.

[0049] It should be noted that the action performed by the first vertical displacement mechanism 18 is linear displacement up and down, which is a very conventional mechanical structure. Structures such as a lead screw nut pair 19, a hydraulic cylinder, and an electric push rod can all achieve this. In this embodiment, the specific structure of the first vertical displacement mechanism 18 is not restricted.

[0050] The second important design point of the present invention lies in the design of the liquid addition alignment technology, which ensures the precise alignment when the upper liquid addition module 4 and the lower liquid addition module 5 add liquid into the condenser tube and the digestion cup, avoiding the leakage of corrosive liquid.

[0051] Both the upper liquid addition module 4 and the lower liquid addition module 5 include: a lateral displacement mechanism, a rotary motor 10, and a liquid addition arm 6; on the moving part 9 of the lateral displacement mechanism, there is a mounting seat, on which a motor for controlling the rotation of the liquid addition arm 6 (hereinafter referred to as the rotary motor 10) is installed, the liquid addition arm 6 is rotatably connected to the mounting seat, and the output end of the rotary motor 10 is connected to the liquid addition arm 6, driving the liquid addition arm 6 to rotate in the horizontal direction. At the end of the liquid addition arm 6, there is a dropper 7 for dripping liquid downward. The lateral displacement mechanism drives the liquid addition arm 6 to move linearly in the X-axis direction, and the liquid addition to each row of condenser modules 2 can be completed.

[0052] The liquid addition arm 6 includes a liquid addition arm 6 housing and a dropper 7; one end of the liquid addition pipe is connected to the liquid outlet of the peristaltic pump, and the other end of the liquid addition pipe penetrates into the liquid addition arm 6 housing and is connected to the dropper 7. The liquid inlet of the peristaltic pump is connected to the reagent bottle through a pipeline.

[0053] In this embodiment, the lateral displacement mechanism is a mechanism that performs linear reciprocating motion, which is a conventional mechanical structure, such as an electric guide rail or a lead screw nut pair 19 can be used, and no specific structural limitation is made in this embodiment.

[0054] In this embodiment, a positioning module is further included, and the positioning module includes a linear positioning sensor, a rotary positioning sensor, and an interface positioning sensor. Among them, the linear positioning sensor is used to collect the linear displacement position of the liquid addition arm 6, the rotary positioning sensor is used to collect the rotational movement position of the liquid addition arm 6, and the interface positioning sensor is used to collect the position of the condenser tube mouth / digestion cup mouth. After the data collected by the three sensors are sent to the controller for determination, the liquid addition arm 6 will start to drip liquid only when the data collected by the three sensors ensure that the position of the dropper 7 of the liquid addition arm 6 is accurate.

[0055] In this embodiment, a positioning module is further included, and the positioning module includes a linear positioning sensor and an interface positioning sensor; the linear positioning sensor is arranged on the moving part of the lateral displacement mechanism, and the linear positioning sensor is used to sense the linear displacement position to ensure that the robotic arm moves horizontally in place. The interface positioning sensor is used to sense whether the dropper 7 is aligned with the digestion cup / condenser tube.

[0056] In this embodiment, the lateral displacement mechanism corresponds to a linear positioning code tooth 14, and there are several notches on the linear positioning code tooth 14. In the positioning module matched with the upper liquid addition module 4, the number of notches on the linear positioning code tooth 14 is the same as the total number of condenser tubes in each row of condenser modules 2. Refer to Figure 2 , there are 16 notches corresponding to the positions of the condenser tubes on the linear positioning code tooth 14.

[0057] In the positioning module that matches the lower liquid addition module 5, the number of notches on the linear positioning code teeth 14 is the same as the total number of digestion cups in each row of each cold digestion group. In the traditional technology, generally, a calibration position and a waste liquid pool for blank reagents are also provided at the position that matches the lower liquid addition module 5. Therefore, notches corresponding to the calibration position and the waste liquid pool are also provided on the linear positioning code teeth 14 to ensure that the lower liquid addition module 5 can accurately move to the calibration position or the waste liquid pool.

[0058] The linear positioning code teeth 14 are made of an opaque material. When the liquid addition arm 6 on the lateral displacement mechanism moves to the notch, at this time, the linear displacement sensor detects the optical signal through the notch, thereby obtaining a detection signal to ensure that the linear displacement is in place.

[0059] In this embodiment, the interface positioning sensors used by the upper liquid addition module 4 and the lower liquid addition module 5 are different. Specifically, please refer to Figure 2 , the interface positioning sensor used by the upper liquid addition module 4 is a groove-type photoelectric switch 12. A first rotating code tooth and a second rotating code tooth are respectively provided on both sides corresponding to the liquid addition arm 6; the groove-type reflection switch is arranged on the moving part of the lateral displacement mechanism and follows the movement. The groove-type photoelectric switch 12 is a sensor that uses the principle of light occlusion or reflection to detect information such as the position and movement of an object. When the groove-type photoelectric switch 12 cannot detect a signal, it means that the rotating code tooth is located in the groove of the groove-type photoelectric switch 12 at this time, so data cannot be detected. At this time, the dropper 7 is aligned with the condensing tube nozzle: both the first rotating code tooth and the second rotating code tooth can follow the liquid addition arm 6 and rotate into the interface positioning sensor. That is, when aligning with the front row of condensing tubes for liquid addition, the first rotating code tooth blocks the interface positioning sensor; when aligning with the front row of condensing tubes for liquid addition, the second rotating code tooth blocks the interface positioning sensor, and when aligning with the rear row of condensing tubes for liquid addition. Further, a rotation reset sensor (also a groove-type photoelectric switch 12) is also provided below the interface positioning sensor, and a corresponding reset code tooth is provided on the liquid addition arm 6. When the reset code tooth blocks the rotation reset sensor, it means that the liquid addition arm 6 is reset. The reset code tooth, the first code tooth, and the second code tooth are respectively located on three sides of the liquid addition arm 6.

[0060] In this embodiment, the interface positioning sensor used by the lower liquid addition module 5 is a reflection sensor 16, which is located below the dropper 7. When its dropper 7 is aligned with the digestion cup, the waste liquid pool, and the calibration position, the reflection sensor 16 collects data to complete the interface positioning.

[0061] In this embodiment, the liquid addition arm 6 only performs the liquid dropping operation when both the linear positioning sensor and the interface positioning sensor collect data.

[0062] Further, the positioning module further includes a linear limit sensor and a linear reset sensor respectively arranged at both ends of the lateral displacement mechanism, which are used to limit the extreme position of the liquid addition arm 6 and ensure that the liquid addition arm 6 returns to its position.

[0063] Further, the interface positioning sensor in the lower liquid adding module 5 uses a reflection sensor 16 for interface positioning. Due to its reflection effect, it can also detect whether a digestion cup is placed at this position.

[0064] In some embodiment solutions, a water receiving tray 13 is further installed on the moving part of the lateral displacement mechanism. When the liquid adding arm 6 rotates back to the initial state, the nozzle 7 is located above the water receiving tray 13, and the water receiving tray 13 catches the leaked liquid from the nozzle 7.

[0065] In some embodiment solutions, the water receiving plate, the liquid adding pipe, and the nozzle 7 are made of materials with acid and alkali resistance. There is no specific limitation in this embodiment. For reference, it can be made of PTFE (polytetrafluoroethylene) material, and the liquid adding pipe is protected by a drag chain.

[0066] In some embodiment solutions, the lateral displacement mechanism includes a linear guide rail 8, a moving part 9, and a stepping motor. A moving groove is provided on the linear guide rail 8, a rack is provided in the moving groove, a motor is installed on the moving part 9, the output end of the motor is connected to a gear, and the gear meshes with the rack, so that when the motor works, it drives the moving part 9 to move along the linear guide rail 8. In addition, the lateral displacement mechanism can also be: including a linear guide rail 8, a moving part 9, and a stepping motor. A moving groove is provided on the linear guide rail 8, a lead screw is rotatably provided in the moving groove, a nut is provided on the lead screw, the moving part 9 is installed on the nut, and one end of the lead screw is connected to the output end of the motor. When the motor works, it drives the moving part 9 to move along the linear guide rail 8.

[0067] Another aspect of this embodiment is to provide a liquid adding control method for a COD analyzer, which is applied to the liquid adding device described in the present invention, and its implementation includes the following processes: Process 1: The controller receives a liquid adding instruction, controls the lateral displacement mechanism and the rotary motor 10 to work, so that the liquid adding arm 6 moves to a specified position; Process 2: The controller receives the position data collected by the linear positioning sensor and the interface position positioning sensor, and the microcontroller determines whether it is aligned. If it is aligned, it controls the peristaltic pump to work and the liquid adding arm 6 to drip liquid. If it is not aligned, it performs the dripping operation.

[0068] Embodiment 2 Since laboratory equipment needs to be as small as possible in size, in the structural design of the analyzer, how to make the size as small as possible is a key consideration direction. If a cylinder, an electric push rod or other forms are used to control each independent condensation module, setting it towards the top direction will increase the height of the equipment, and setting it towards the side direction will increase the width of the equipment. And the front side of the COD analyzer is an experimental space and needs to be open, and at the same time, the front and rear rows of condensation modules 2 are aligned. Based on this, referring to Figure 4 , in this embodiment, the first vertical displacement mechanism 18 is a lead screw nut pair 19 structure.

[0069] Specifically, the frame 1 is provided with an operation opening in the front side direction of the Y-axis, and a back plate 17 is provided on the rear side direction of the Y-axis of the frame 1.

[0070] The structure of the lead screw nut pair 19 includes a lead screw, a nut, a motor, and a mounting plate; a mounting plate is provided on the back plate 17, the lead screw is vertically rotatably arranged on the mounting plate, a nut is provided on the lead screw, and the motor drives the rotation of the lead screw. The nut is connected to the condensation bracket 20 for placing the condensation module 2, thereby controlling the downward movement of the condensation pipe. The lead screw is a ball screw, a nut is provided on the lead screw, and the balls between the lead screw and the nut serve as limit members to limit the rotation of the nut. In addition, the rotation of the nut can also be restricted by a limit groove and a limit block. For example, a vertical limit groove is arranged parallel to the lead screw, and a vertically movable limit block is arranged in the limit groove, and the limit block is connected to the nut. The limit member is a common mechanical structure, and no specific limitation is made in this embodiment.

[0071] Since it is necessary to design to minimize the height of the frame 1 as much as possible, therefore, the condensation bracket 20 is located below the pipe orifice of the condensation pipe, please refer to Figure 3 and is located at the lower part of the condensation pipe.

[0072] Embodiment 3 The difference between this embodiment and Embodiment 1 is that the upper liquid adding module 4 and the lower liquid adding module 5 are combined into one liquid adding module. The advantage of such a design is that currently, the liquid adding actions of the upper liquid adding module 4 and the lower liquid adding module 5 of the COD analyzer for the condensation pipe and the digestion pipe are not carried out simultaneously, but there is a time difference. After combining the upper and lower liquid adding modules 5 into one, only one positioning module is required. Therefore, combining the two upper and lower liquid adding modules 5 into one liquid adding module not only does not affect the working efficiency, but also can streamline the overall structure of the device and reduce the weight.

[0073] Specifically, please refer to Figure 4 In this embodiment, the COD analyzer only includes one liquid adding module. This liquid adding module includes a horizontal displacement mechanism. A mounting seat is provided on the moving end of the horizontal displacement mechanism. A second vertical displacement mechanism 15 is provided on the mounting seat. A liquid adding arm 6 is rotatably mounted on the moving end of the second vertical displacement mechanism 15, and a rotating motor 10 for driving the liquid adding arm 6 to rotate is also mounted on the moving end. The second vertical displacement mechanism 15 drives the liquid adding arm 6 to displace in the Z-axis.

[0074] Specifically, the rotating motor 10 is arranged on the mounting seat. The second vertical displacement mechanism 15 is an electric lifting sleeve. The mounting seat passes through the electric lifting sleeve and is connected to the rotating arm. The bottom of the electric lifting sleeve is fixed to the moving end, and the top is rotatably connected to the liquid adding arm 6.

[0075] In this embodiment, the installation position of the liquid adding module is at the height of the installation position of the above-mentioned lower liquid adding module 5. Under the control of the second vertical displacement mechanism 15, the liquid adding arm 6 can be lifted or lowered to match the height of the condensation tube and the digestion cup.

[0076] The liquid adding tube passing through the liquid adding arm 6 is a flexible tube. Therefore, its length reserves a margin for the lifting height, and a drag chain is provided on its lateral displacement mechanism to protect the cables of the electrical equipment and the liquid adding tube.

[0077] In this embodiment, one liquid adding module is arranged between two rows of digestion modules 3. Under the action of the second vertical displacement mechanism 15, the liquid adding arm 6 adds liquid to the digestion module 3 at a lower height and samples the condensation module 2 at a higher height.

[0078] As a reference method, in this embodiment, the second vertical displacement mechanism 15 performs a vertical linear displacement action, which is a conventional mechanical structure. It can be realized by using an electric push rod, a hydraulic cylinder, a linear electric guide rail, a lead screw nut pair 19, etc. This embodiment does not make specific limitations.

[0079] In this embodiment, the drip nozzle 7 is provided with an electric control valve.

[0080] It should be noted that in this embodiment, the interface positioning sensor included in the positioning module is a reflection sensor 16.

[0081] Embodiment 4 Based on the structures of Embodiment 2 and Embodiment 3, since one condensation bracket 20 is responsible for placing one condensation module 2, and the condensation tubes in the condensation module 2 are in a two-row structure, when combining the upper and lower liquid adding modules into one, at this time, the condensation bracket 20 will interfere with the lifting and lowering of the liquid adding module.

[0082] Therefore, in this embodiment, on the premise that the first driving mechanism is a lead screw nut pair 19 and one liquid adding module adds liquid to the digestion module 3 and the condensation module 2, the structure of the condensation bracket 20 is designed.

[0083] In this embodiment, the condensation bracket 20 includes a first frame body and a second frame body. The first frame body and the second frame body respectively carry the installation and placement of two rows of condensation tubes. The first frame body and the second frame body are separated, and there is an avoidance channel between them, and this avoidance channel avoids the lifted liquid taking arm.

[0084] The first frame body and the second frame body are connected by a connecting piece. When it is necessary to control the condensation tube to descend and ascend, the connecting piece connects the first frame body and the second frame body into a whole to control the descent and ascent. When the liquid taking arm needs to be lifted to sample the condensation tube, at this time, the connecting piece does not block the avoidance channel.

[0085] In this embodiment, under the control of the corresponding second vertical displacement mechanism 15, the initial height position of the top of the liquid adding arm 6 should be lower than the height of the mouth of the digestion cup, that is, the liquid adding arm 6 has three working heights from low to high in the vertical direction: the initial height, the digestion liquid adding height, and the condensation liquid adding height. The second vertical displacement mechanism 15 controls the transfer of the liquid adding arm 6 between the previous working heights. The initial height should also ensure that when the digestion cup is docked with the condensation tube, the height of the liquid adding arm 6 is lower than the bottom of the condensation bracket 20.

[0086] In this embodiment, the connecting member is a connecting rod; the two side edges of the first frame body and the second frame body in the X-axis direction are connected by the connecting rod, that is, a square avoidance channel is formed among the first frame body, the second frame body, and the connecting rod. In this structure, the second vertical displacement mechanism 15 can pass through the square avoidance channel and move in the X-axis direction within the range of the square avoidance channel. Since the first frame body and the second frame body are used to place the condensation module 2 and are wider than the width of the condensation module 2, during the movement in the X-axis direction within the square avoidance channel, the liquid can be added to the condensation tubes corresponding to each digestion position.

[0087] For the convenience of describing the following control method, in this embodiment, the rotation directions of the liquid adding arm 6 are defined as: the initial angle and the liquid adding angle. At the liquid adding angle, the dropper 7 is located at the top of the mouth of the digestion cup / condensation tube, and the initial angle and the liquid adding angle form a 90° angle. The initial position of the liquid adding arm 6 on the X-axis is defined as the initial distance on the X-axis. When the liquid adding arm 6 is at the initial height, the initial angle, and the initial distance on the X-axis, the liquid adding arm 6 is at the initial working position at this time (the above-mentioned connecting rod is located outside the initial working position and will not cause interference in the lifting direction).

[0088] In this embodiment, the control method for adding liquid to only one set of digestion groups is as follows: Step S1: The liquid adding arm is at the initial working position, and at this time, the top of the liquid adding arm is lower than the mouth of the digestion cup of the previous group; Step S2: The second vertical displacement mechanism receives the instruction from the controller, and the liquid adding arm rises to the digestion liquid adding height; Step S3: The rotation motor receives the instruction from the controller, works to drive the liquid adding arm to rotate to the liquid adding angle, the dropper 7 is located above the mouth of the digestion cup, and after the liquid adding is completed, the liquid adding arm rotates back to the initial angle; Step S4: The lateral displacement mechanism receives the instruction from the controller, the liquid adding arm moves in place on the X-axis, and steps S3 - S4 are repeatedly executed until the liquid adding to one digestion module is completed, and the liquid adding arm returns to the initial working position; Step S5: The first vertical displacement mechanism receives the instruction from the controller, works to lower the condensation tube to dock with the digestion cup; Step S6: The second vertical displacement mechanism receives the instruction from the controller, and the liquid adding arm rises from the initial height to the condensation liquid adding height; Step S7: The rotation motor receives the controller instruction, operates to drive the liquid filling arm to rotate to the liquid filling angle, with the nozzle positioned above the condensation pipe orifice. After liquid filling is completed, the liquid filling arm rotates back to the initial angle. Step S8: The lateral displacement mechanism receives the controller instruction, the liquid filling arm moves into position on the X-axis, and steps S6 - S7 are repeatedly executed until liquid filling of one condensation module is completed, and the liquid filling arm returns to the initial working position. Step S9: The first vertical displacement mechanism receives the controller instruction to raise the condensation pipe to separate it from the digestion cup. Step S10: The second vertical displacement mechanism receives the controller instruction to raise the liquid filling arm to the digestion liquid filling height. Step S11: The rotation motor receives the controller instruction, operates to drive the liquid filling arm to rotate to the liquid filling angle, with the nozzle 7 positioned above the digestion cup orifice. After liquid filling is completed, the liquid filling arm rotates back to the initial angle. Step S12: The lateral displacement mechanism receives the controller instruction, the liquid filling arm moves into position on the X-axis, and steps S11 - S12 are repeatedly executed until liquid filling of one digestion module is completed, and the liquid filling arm returns to the initial working position.

[0089] Further, in this embodiment, a number of initial working positions consistent with the number of digestion groups are written into the controller. If there are four digestion groups, they are the first initial working position, the second initial working position, the third initial working position, and the fourth initial working position respectively. The position data of each initial working position is written into the controller.

[0090] In this embodiment, the control method for liquid filling of two digestion groups is as follows: When the liquid filling arm needs to move from one digestion group to the next digestion group, the liquid filling arm is at the initial working position of the previous digestion group. At this time, the lateral displacement mechanism receives the controller instruction, and the liquid filling arm moves into position on the X-axis to the initial working position of the next digestion group. Then, the liquid filling work of the next digestion group is executed.

[0091] It should be noted that the transfer of the liquid filling arm 6 between any two digestion groups depends on its corresponding initial working position for position positioning.

[0092] Through this control working process of the liquid filling arm 6, on the premise that the front and rear condensation brackets are lifted and lowered together under the action of the screw nut, it is ensured that the movement of the liquid filling arm 6 does not interfere with the condensation bracket 20.

[0093] In some specific embodiments, an edge sensor is further included. The edge sensor is disposed on the second vertical displacement mechanism 15. When the second vertical displacement mechanism 15 operates to lift the liquid adding arm 6 to a relatively high height for sampling the condensation module 2. The height of the edge sensor corresponds to the position of the connecting rod, so as to sense the distance from the connecting rod to detect the edge position in the avoidance channel and perform limit feedback on the moving member of the X-axis movement of the lateral displacement mechanism.

[0094] Embodiment 5 In this embodiment, for the structure of the condensation bracket 20, please refer to Figure 7 . The condensation bracket 20 includes a first frame body and a second frame body. The first frame body and the second frame body respectively carry the installation and placement of two rows of condensation tubes. The first frame body and the second frame body are separately arranged, and there is an avoidance channel therebetween, and the avoidance channel avoids the lifted liquid taking arm.

[0095] The first frame body and the second frame body are connected by a connecting member. When it is necessary to control the descent and ascent of the condensation tube, the connecting member connects the first frame body and the second frame body into a whole to control the descent and ascent. In this embodiment, the connecting member is a portal frame, and the bottom of the portal frame is connected to the first frame body and the second frame body.

[0096] When the condensation tube is placed on the first frame body and the second frame body, there is a space for the liquid adding arm 6 to add liquid between the top of the portal frame and the tube orifice of the condensation tube.

[0097] When the digestion cup and the condensation tube have been docked and it is necessary to move from one digestion group to another digestion group, the liquid adding module can directly move between adjacent two digestion groups through the avoidance channel.

[0098] In this embodiment, the liquid adding arm 6 only needs two working heights, namely the digestion liquid adding height and the condensation liquid adding height. The control logic of the liquid adding arm 6 in this embodiment will be relatively simple. However, relatively speaking, it will increase the height of the COD analyzer.

[0099] It should be noted that the embodiments in this specification are all described in a progressive manner. Each embodiment focuses on the differences from other embodiments. For the same and similar parts between the embodiments, reference can be made to each other.

[0100] As shown in this application and the claims, unless the context clearly indicates an exception, words such as "a", "an", "one" and / or "the" are not specifically singular and may also include plural. Generally speaking, the terms "comprise" and "include" only indicate the inclusion of the clearly identified steps and elements, and these steps and elements do not constitute an exclusive list. The method or device may also include other steps or elements. An element defined by the statement "comprising one..." does not exclude the existence of another identical element in the process, method, commodity or device including the element.

[0101] Among them, in the description of the embodiments of the present application, unless otherwise specified, " / " means "or". For example, A / B may mean A or B. The "and / or" herein is merely a description of the association relationship of the associated objects, indicating that there can be three relationships. For example, A and / or B may mean: A exists alone, A and B exist simultaneously, and B exists alone. In addition, in the description of the embodiments of the present application, "a plurality of" means two or more than two.

[0102] The terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features.

[0103] In this article, embodiments are used to elaborate on the principles and implementation manners of the present invention. The description of the above embodiments is only for helping to understand the core idea of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A liquid adding device for a COD analyzer, characterized in that, It includes a frame and several digestion groups arranged on the frame. The several digestion groups are arranged in sequence along the X-axis of the frame, and the operation port of the instrument is opened in the Y-axis direction of the frame; each digestion group includes several digestion positions arranged in 2 rows and N columns, and each digestion group includes a digestion cup located below and a condensing tube located above at each digestion position; the several condensing tubes of each digestion group form a condensing module; the several digestion cups of each digestion group form a digestion module. Each condensing module is correspondingly connected to a mobile end of a first vertical displacement mechanism that moves in the Z-axis direction of the frame; the first vertical displacement mechanism corresponding to each condensing module is independently controlled by a controller. A liquid adding module is also provided on the frame. The liquid adding module includes a horizontal displacement mechanism and a liquid adding arm. The moving part of the horizontal displacement mechanism is rotatably connected to the liquid adding arm, and the liquid adding arm is connected to the driving end of a rotating motor; the moving part on the horizontal displacement mechanism moves along the X-axis direction; a drip nozzle for dripping liquid downward is provided on the liquid adding arm; the liquid adding module is arranged between two rows of digestion positions to add liquid to the condensing tubes and digestion cups in the front and rear rows.

2. The liquid adding device for a COD analyzer according to claim 1, wherein, It also includes a positioning module. The positioning module includes a linear positioning sensor and an interface positioning sensor; the linear positioning sensor is set to collect the horizontal displacement position of the liquid adding arm, and the interface positioning sensor collects the rotation position of the liquid adding arm. When both the interface positioning sensor and the linear positioning sensor collect signals, the controller controls the liquid adding arm to perform a dripping operation.

3. A liquid adding device for a COD analyzer according to any one of claims 1-2, characterized in that, The first vertical displacement mechanism is a lead screw and nut structure, which includes a motor, a lead screw, and a nut; the output end of the motor is connected to the lead screw, the nut is threadedly connected to the lead screw, and the nut is provided with a limiting part to limit the rotation of the nut; the nut is connected to the condensing module.

4. A liquid adding device for a COD analyzer according to any one of claims 1-2, characterized in that, The liquid adding module also includes a second vertical displacement mechanism whose mobile end moves in the Z-axis direction. The moving part of the horizontal displacement mechanism is rotatably connected to the liquid adding arm through the second vertical displacement mechanism. The second vertical displacement mechanism is arranged on the moving part of the horizontal displacement mechanism. The mobile end of the second vertical displacement moves and is rotatably connected to the liquid adding arm, so that the height of the liquid adding arm can be lifted and lowered; a liquid adding module is arranged between two rows of digestion positions; under the lifting control of the second vertical displacement mechanism, the liquid adding arm descends to add liquid to the digestion module at a lower height, and the liquid adding arm rises to add liquid to the condensing module at a higher height.

5. A liquid adding device for a COD analyzer according to claim 4, characterized in that, The several condensing tubes of the condensing module are jointly arranged on a condensing bracket. The condensing bracket includes a first frame body and a second frame body that respectively correspond to placing two rows of condensing tubes. The first frame body and the second frame body are separated and arranged, and an avoidance channel for avoiding the liquid adding module is formed between them; a connecting piece is provided between the first frame body and the second frame body; when the condensing bracket moves up and down under the action of the controller driving the first vertical displacement mechanism, the connecting piece connects the first frame body and the second frame body, so that the whole condensing bracket moves up and down; when the liquid adding arm performs a Z-axis movement and an X-axis movement, the liquid adding arm passes through the avoidance channel, and the connecting piece does not block the avoidance channel.

6. The liquid adding device for a COD analyzer according to claim 5, characterized in that, The connecting piece is a portal frame, and the bottom of the portal frame is connected to the first frame body and the second frame body; when the condensing tubes are placed on the first frame body and the second frame body, there is a space for the liquid adding arm to add liquid between the top of the portal frame and the tube orifice of the condensing tube. The liquid adding module moves between adjacent two digestion groups through the avoidance channel.

7. A liquid adding device for a COD analyzer according to claim 5, characterized in that, The condensation support is located below the nozzle of the condensation pipe. The connecting part is a connecting rod. The two side edges of the first frame body and the second frame body in the X-axis direction are connected by the connecting rod, and an avoidance channel is formed among the first frame body, the second frame body and the connecting rod. The second vertical displacement mechanism can pass through the square avoidance channel and move in the X-axis direction within the range of the square avoidance channel. Under the action of the second vertical displacement mechanism, the liquid adding arm has three working heights, namely the initial height from low to high, the digestion liquid adding height, and the condensation liquid adding height. When the liquid adding module moves from one digestion group to another digestion group, the liquid adding arm is at the initial height.

8. The liquid adding device for a COD analyzer according to claim 2, characterized in that, The linear positioning sensor is an optoelectronic sensor arranged on the moving part of the horizontal displacement mechanism. The optoelectronic sensor is matched with a linear code tooth, and the linear code tooth is provided with notches. The number of notches corresponds to the digestion positions one by one. When the optoelectronic sensor follows the moving part to move to the notch, the optical signal passing through the notch is collected.

9. The liquid adding device for a COD analyzer according to claim 2, characterized in that, The interface positioning sensor includes a reflection sensor and a groove-shaped optoelectronic switch. A reflection sensor located below the nozzle is arranged on the liquid adding arm for adding liquid to the digestion cup, which is used to detect whether there is a digestion cup or whether it is aligned with the digestion cup. A groove-shaped optoelectronic switch is arranged on one side of the liquid adding arm for adding liquid to the condensation pipe. The liquid adding arm rotates relative to the groove-shaped optoelectronic switch, and a first rotating code tooth and a second rotating code tooth are respectively arranged on the corresponding two sides of the liquid adding arm. When the first rotating code tooth and the second rotating code tooth are respectively located at the position blocking the groove-shaped optoelectronic switch, the groove-shaped optoelectronic switch collects the signal, and it is detected that the nozzle of the liquid adding arm is aligned with the front row of condensation pipes or the rear row of condensation pipes.

10. A liquid adding device for a COD analyzer according to claim 7, characterized in that, There are several initial working positions consistent with the number of digestion groups, and the position data corresponding to the initial working positions are written into the controller. The initial working position refers to the position where the liquid adding arm is at the initial height, the initial angle, and the initial X-axis position corresponding to this digestion group. The initial angle refers to the working position where the liquid adding arm is not adding liquid to the digestion cup or the condensation pipe. The control method for adding liquid to two digestion groups is as follows: When the liquid adding arm needs to move from one digestion group to the next digestion group, the liquid adding arm is at the initial working position of the previous digestion group. At this time, the horizontal displacement mechanism receives the controller instruction, and the liquid adding arm moves in the X-axis to the initial working position of the next digestion group, and then performs the liquid adding work for the next digestion group.

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