阅读说明：本技术 一种用于定量分析痕量尿素的方法及装置 (Method and device for quantitatively analyzing trace urea ) 是由 陈炜彧 罗嘉豪 周伟 熊江磊 李军冠 张学良 罗峥 翟新桥 于 2020-12-02 设计创作，主要内容包括：本发明属于水质分析技术领域,具体的说是一种定量分析痕量尿素的方法及装置,其中定量分析痕量尿素的方法包括以下步骤：S1进水先经过注射泵P1和流量传感器F1；S2进水进入预处理单元后,依次进入紫外分解器A和有机吸附器B；S3经过预处理的进水通过蠕动泵W打入微量进样器C；S4进样时,试样溶液将与载水混合,然后进入检测单元；S5载水进入检测单元分析尿素浓度；根据本发明的痕量尿素定量分析方法和装置,可以准确测量半导体/液晶面板厂超纯水制备原水或产水的尿素浓度,且该方法具有准确度高、精密度高和装置集成化程度高的优点。(The invention belongs to the technical field of water quality analysis, and particularly relates to a method and a device for quantitatively analyzing trace urea, wherein the method for quantitatively analyzing the trace urea comprises the following steps: s1, the inlet water passes through a syringe pump P1 and a flow sensor F1; s2, after entering a pretreatment unit, the inlet water sequentially enters an ultraviolet decomposer A and an organic adsorber B; s3 pumping the pretreated inlet water into a microsyringe C through a peristaltic pump W; s4, when the sample is injected, the sample solution is mixed with water, and then enters a detection unit; s5, feeding water into a detection unit to analyze the concentration of urea; according to the method and the device for quantitatively analyzing the trace urea, the concentration of the urea in raw water or produced water prepared by ultrapure water in a semiconductor/liquid crystal panel factory can be accurately measured, and the method has the advantages of high accuracy, high precision and high device integration degree.)

1. A method for the quantitative analysis of urea traces, characterized in that it comprises the following steps:

s1, the inlet water passes through a syringe pump P1 and a flow sensor F1;

s2, after entering a pretreatment unit, the inlet water sequentially enters an ultraviolet decomposer A and an organic adsorber B;

s3 pumping the pretreated inlet water into a microsyringe C through a peristaltic pump W;

s4, when the sample is injected, the sample solution is mixed with water, and then enters a detection unit;

the water loaded in S5 enters a detection unit to analyze the concentration of urea.

2. The method for the quantitative analysis of urea traces according to claim 1, characterized in that: the ultraviolet decomposer A is an ultraviolet lamp tube with a quartz sleeve arranged outside, vacuum ultraviolet rays are adopted, the wavelength range is 100-200 nm, and the organic adsorber B is made of ion exchange resin.

3. The method for the quantitative analysis of urea traces according to claim 1, characterized in that: the micro-sample injector C main body is a six-way valve, the six-way valve comprises six ports and an annular pipeline, and the six ports are numbered as 1 ', 2', 3 ', 4', 5 'and 6' respectively; the ring line is connected with two ports 2 'and 5', and the liquid flow direction in the ring line is 2 '→ 5'.

4. The method for the quantitative analysis of urea traces according to claim 1, characterized in that: the water carrier is provided with a circulating unit, the water carrier in the flow cell G is pressurized by a syringe pump P2 and then enters a water carrier pipeline III, and then enters an annular pipeline of the micro-sampler C after passing through a flow sensor F2, an ion absorber D and a heating coil HC, and is mixed with the sample solution, and the water carrier sequentially passes through ports 3 '→ 2' → 5 '→ 4'.

5. The method for the quantitative analysis of urea traces according to claim 1, characterized in that: the detection unit is characterized in that a conductivity cell C1, a conductivity cell C2, a reagent injection device and a mixing coil MC are arranged on a detection pipeline IV, and the urea concentration is obtained through conversion by measuring the conductivity difference before and after advanced oxidation of the carrier water.

6. An apparatus for quantitatively analyzing a trace amount of urea, characterized in that: a peristaltic pump W as used in S3 of claim 1; the peristaltic pump comprises a motor, a shell, a pump head, a rotor, a roller and a pump pipe; an anti-abrasion mechanism is arranged in the peristaltic pump; the anti-abrasion mechanism comprises a push plate, a connecting plate and a limiting rod; the push plate is positioned between the pump pipe and the pump head, the push plate is arc-shaped, the convex surface of the push plate is attached to the pump pipe, the concave surface of the push plate is attached to the roller, the opposite surface of the push plate to the bottom of the shell is fixedly connected with a connecting plate, the connecting plate penetrates through a gap between the pump pipe and the inner bottom surface of the shell, a sliding hole is formed in the connecting plate, and a limiting rod is in clearance fit in the sliding hole; the limiting rod is located above the pump pipe, and one end of the limiting rod is fixedly connected to the inner bottom surface of the shell.

7. The device for quantitatively analyzing the trace urea according to claim 6, wherein a return spring is arranged in the slide hole; one end of the reset spring is fixedly connected to the side wall of the sliding hole, and the other end of the reset spring is fixedly connected to the limiting rod.

8. The device for quantitatively analyzing the trace urea according to claim 6, wherein a limiting plate is arranged at the other end of the limiting rod; the number of the limiting plates is two, and the limiting plates are symmetrically and fixedly connected to the other end of the limiting rod.

9. The device for quantitatively analyzing the trace urea according to claim 6, wherein sliding grooves are respectively formed on two sides of the sliding hole; the end part of the limiting plate is connected in the sliding groove in a sliding mode.

10. The apparatus according to claim 9, wherein the chute is arc-shaped, and the concave surfaces of the chute are designed to face each other.

Technical Field

The invention belongs to the technical field of water quality analysis, and particularly relates to a method and a device for quantitatively analyzing trace urea.

Background

The ultrapure water is an essential auxiliary material for the production of products in semiconductor/liquid crystal panel factories, and the water quality requirement is quite high. Raw water for preparing ultrapure water is basically from municipal tap water, and the ultrapure water is obtained through multi-stage treatment of a pretreatment system, a preparation system and a polishing system and is used for product production in a semiconductor/liquid crystal panel factory.

Trace urea is doped into municipal tap water sometimes, the concentration is generally 50-200 ppb, and the conversion is only 10-40 ppb of TOC; the ultrapure water preparation system has limited urea removal capacity, and finally, the TOC of produced water exceeds the standard, the production yield is influenced, and huge economic loss is caused to a semiconductor/liquid crystal panel factory. When the existing ultrapure water system is designed, a urea removal unit is arranged at a raw water end, but the owner can reduce the operation cost and the actual operation time; and when the TOC of produced water exceeds the standard, the urea removal unit is started, and the method still brings certain economic loss. Even if a TOC instrument is arranged at the raw water end, trace urea cannot be doped to cause huge fluctuation of TOC; if the on-line monitoring of the trace urea is available, the urea removal unit is operated in time, so that economic loss can be avoided.

The prior technical literature about urea detection is as follows:

patent document 1: 201711338043.0, respectively; a spectrophotometric measuring method is adopted, the principle that diacetyl monoxime and antipyrine reagents react with urea is utilized, and components such as a sample cup, a sampling multi-way valve, a cleaning multi-way valve, a first mechanical arm unit, a second mechanical arm unit and the like are arranged, so that the urea content in a water sample is analyzed. However, the method has the disadvantages of large volume of used parts, low equipment integration degree, complicated sample introduction, long detection period of more than 52min, poor practicability and no accordance with the continuous detection requirement of a pure water system.

Patent document 2: 201810341217.7, respectively; the method has the advantages that the neutral red indicator, the sample to be detected and the polyethylene glycol mixed solution are used as the inner water phase, the urease and glucan mixed solution is used as the outer water phase, the urea content is analyzed through the micro-fluidic device, the operation cost is low, the detection of a single sample only needs 10-20 seconds, but the method cannot be used for detecting raw water prepared from pure water, the enzyme effect is limited when the concentration of reactants is low due to enzymatic reaction, and the actual use effect is poor.

Patent document 3: 201880021497.1, respectively; a method for quantifying urea in sample water by a colorimetric assay using diacetyl monoxime, in particular, cold storage of reagents for the reaction. However, diacetyl monoxime is not only reacted with urea to develop color, but also reacted with citrulline which is a metabolite of diacetyl monoxime, and the influence of citrulline cannot be eliminated by the measuring method; the method has the advantages of limited detection principle precision, lower detection limit of 0.1ppm, incapability of detecting lower trace urea, multiple application in places such as swimming pools and the like, and unsuitability for urea detection of raw water prepared from pure water.

According to the content, the problems that the detection principle in the prior art is limited in precision, trace urea cannot be measured, and the automation and integration degree of equipment sample introduction are low are solved; the present invention has been made in view of the above problems, and an object of the present invention is to provide a method and an apparatus for quantitatively analyzing a trace amount of urea.

Disclosure of Invention

In order to solve the above problems, the present invention provides a method and an apparatus for quantitatively analyzing trace urea, which quantitatively analyzes the urea concentration of raw water or produced water by using a flow injection analysis technique and an advanced oxidation technique, and according to the object of the present invention, provides a method for quantitatively analyzing trace urea, the method comprising the steps of:

s1, the inlet water passes through a syringe pump P1 and a flow sensor F1;

s2, after entering a pretreatment unit, the inlet water sequentially enters an ultraviolet decomposer A and an organic adsorber B;

s3 pumping the pretreated inlet water into a microsyringe C through a peristaltic pump W;

s4, when the sample is injected, the sample solution is mixed with water, and then enters a detection unit;

the water loaded in S5 enters a detection unit to analyze the concentration of urea.

Preferably, the ultraviolet decomposer A main body is an ultraviolet lamp tube with a quartz sleeve arranged outside, vacuum ultraviolet rays are adopted, the wavelength range is 100-200 nm, the organic adsorber B main body is ion exchange resin, and the high-quality domestic macroporous strong base resin and macroporous weak base resin are adopted, the ratio of 1-2 BV/h is 2: 1-3: 1.

Preferably, the main body of the microsyringe C is a six-way valve, the six-way valve comprises six ports and an annular pipeline, and the six ports are numbered as 1 ', 2', 3 ', 4', 5 'and 6', respectively; the ring line is connected with two ports 2 'and 5', and the liquid flow direction in the ring line is 2 '→ 5'.

Preferably, the water carrier is provided with a circulation unit, the water carrier in the flow cell G is pressurized by the syringe pump P2 and then enters the water carrier pipeline (C), passes through the flow sensor F2, the ion absorber D and the heating coil HC and then enters the loop pipeline of the micro-injector C to be mixed with the sample solution, and the water carrier sequentially passes through the 3 '→ 2' → 5 '→ 4' ports.

Preferably, the detection unit is provided with a conductivity cell C1, a conductivity cell C2, a reagent injection device and a mixing coil MC on a detection pipeline r, and the urea concentration is obtained by measuring the conductivity difference of the carrier water before and after advanced oxidation and converting the difference.

An apparatus for quantitatively analyzing a trace amount of urea, which is a peristaltic pump W used in the above step S3; the peristaltic pump comprises a motor, a shell, a pump head, a rotor, a roller and a pump pipe; an anti-abrasion mechanism is arranged in the peristaltic pump; the anti-abrasion mechanism comprises a push plate, a connecting plate and a limiting rod; the push plate is positioned between the pump pipe and the pump head, the push plate is arc-shaped, the convex surface of the push plate is attached to the pump pipe, the concave surface of the push plate is attached to the roller, the opposite surface of the push plate to the bottom of the shell is fixedly connected with a connecting plate, the connecting plate penetrates through a gap between the pump pipe and the inner bottom surface of the shell, a sliding hole is formed in the connecting plate, and a limiting rod is in clearance fit in the sliding hole; the limiting rod is located above the pump pipe, and one end of the limiting rod is fixedly connected to the inner bottom surface of the shell.

Preferably, a return spring is arranged in the sliding hole; one end of the reset spring is fixedly connected to the side wall of the sliding hole, and the other end of the reset spring is fixedly connected to the limiting rod.

Preferably, a limiting plate is arranged at the other end of the limiting rod; the number of the limiting plates is two, and the limiting plates are symmetrically and fixedly connected to the other end of the limiting rod.

Preferably, sliding chutes are respectively formed on two sides of the sliding hole; the end part of the limiting plate is connected in the sliding groove in a sliding mode.

Preferably, the sliding groove is arc-shaped, and the concave surfaces of the sliding groove are designed oppositely.

The invention has the following beneficial effects:

according to the method and the device for quantitatively analyzing the trace urea, the concentration of the urea in raw water or produced water prepared by ultrapure water in a semiconductor/liquid crystal panel factory can be accurately measured, and the method has the following advantages:

firstly, the accuracy is high, the invention adopts an advanced oxidation technology, the generated hydroxyl free radical (. OH) can effectively react with the trace urea, and the test can accurately measure the trace urea of 20-1000 ppb.

Secondly, the precision is high, the invention adopts the flow injection analysis technology, the measured sample volume is certain, the retention time, the reaction temperature, the turbulence intensity and other conditions in the pipeline are the same, the reproducibility of the measurement result is good, and the precision is high.

The device is high in integration degree, highly integrates a pretreatment unit, a microsyringe, a detection unit, a water carrying circulation unit, a double water inlet channel and a double water outlet channel, and is high in integration degree due to the fact that parts such as an injection pump, a flow sensor, a heating coil, a mixing coil and an ion absorber are arranged.

The used peristaltic pump is provided with the anti-abrasion mechanism between the pump pipe and the rollers, so that the rollers are prevented from generating destructive abrasion on the pump pipe, and the service life of the pump pipe is prolonged; the limiting plate slides in the spout of arc form for the removal orbit of connecting plate is restricted, makes the effective action point of push pedal extrusion pump line restricted, makes the pump line extrusion deformation volume at every turn keep the same, thereby the liquid volume of outflow all keeps the same in the pump line.

Drawings

The invention will be further explained with reference to the drawings.

FIG. 1 is a schematic view of a loading gear of a trace urea analysis device according to the present invention;

FIG. 2 is a schematic diagram of a sample injection block of the trace urea analysis device according to the present invention;

FIG. 3 is a graph of urea concentration of raw water versus conductivity (C1, C2, C2-C1);

FIG. 4 is a perspective view of a peristaltic pump W used in the present invention;

FIG. 5 is a cross-sectional view of a peristaltic pump W used in the present invention;

FIG. 6 is an enlarged view of a portion of FIG. 5 at A;

in the figure: the device comprises a motor 1, a shell 2, a pump head 11, a rotor 12, a roller 121, a pump pipe 21, an anti-friction mechanism 3, a push plate 31, a connecting plate 32, a sliding hole 321, a return spring 322, a sliding groove 323, a limiting rod 33 and a limiting plate 331.

Detailed Description

In order to make the technical means, the creation features, the achievement purposes and the effects of the invention easy to understand, the invention is further described with the following embodiments.

As shown in figures 1 to 3 of the drawings,

a method for quantitatively analyzing a trace amount of urea, comprising the steps of:

s1, the inlet water passes through a syringe pump P1 and a flow sensor F1; the injection pump P1 pressurizes the inlet water to ensure that the inlet water can smoothly pass through the subsequent parts; the flow sensor F1 detects the fluid flow, provides the fluid signal in the pipeline, and is convenient for maintenance and repair. The pressurized inlet water can enter the pretreatment unit through a pipeline I, and the front end of the pipeline I is provided with an overhaul valve. When the device is overhauled, the overhaul valve is closed, and water can directly enter the drainage pipeline II;

s2, after entering a pretreatment unit, the inlet water sequentially enters an ultraviolet decomposer A and an organic adsorber B;

s3 pumping the pretreated inlet water into a microsyringe C through a peristaltic pump W; the peristaltic pump is adopted, the inlet water sequentially passes through the ultraviolet decomposer A and the organic adsorber B, the water pressure is weakened, the water pressure is difficult to ensure that the water pressure smoothly passes through the microsyringe C at the later stage, and therefore the pressurization treatment is carried out by using the peristaltic pump W, compared with an injection pump, the peristaltic pump is simple in structure, convenient to maintain and low in cost, and a wearing part is a pump pipe and is easy to wear and break;

s4, when the sample is injected, the sample solution is mixed with water, and then enters a detection unit;

the water loaded in S5 enters a detection unit to analyze the concentration of urea.

The main body of the ultraviolet decomposer A is an ultraviolet lamp tube with a quartz sleeve arranged outside, vacuum ultraviolet rays are adopted, the wavelength range is 100-200 nm, more specifically 180-190 nm, preferably 185nm and 185nm ultraviolet sterilizing lamps can change oxygen in air into ozone, the ozone has strong oxidation effect, bacteria can be effectively killed, and the influence of other organisms on an experiment is discharged; the main body of the organic adsorber B is ion exchange resin, and the organic adsorber B adopts macroporous strong base resin and macroporous weak base resin of certain high-quality brands in China, and the proportion of 1-2 BV/h is 2: 1-3: 1; the ultraviolet decomposer A can remove macromolecular organic matters in the inlet water, but cannot remove micromolecular organic matters, namely urea; the organic adsorber B can effectively adsorb macromolecular organic matters but cannot adsorb micromolecular organic matter urea; in order to improve the detection precision of the instrument, the TOC of the inlet water is required to be less than 2ppm so as to ensure that the pretreatment unit can effectively eliminate the influence of macromolecular organic matters.

The microsyringe C main body is a six-way valve, and the six-way valve comprises six ports and an annular pipeline. The six ports are numbered 1 ', 2', 3 ', 4', 5 'and 6' respectively; the ring line is connected with two ports 2 'and 5', and the liquid flow direction in the ring line is 2 '→ 5'.

The water carrying device is provided with a circulating unit, the water carrying in the flow cell G is pressurized by a syringe pump P2 and then enters a water carrying pipeline III, and then enters an annular pipeline of a micro-sampler C after passing through a flow sensor F2, an ion absorber D and a heating coil HC to be mixed with a sample solution, and the water carrying sequentially passes through ports 3 '→ 2' → 5 '→ 4'; the main body of the ion absorber D is ion exchange resin, and the ion absorber D adopts gel type strong acid resin and gel type strong base resin of certain high-quality brands in China, and the mixture ratio is 3:1 at 40-60 BV/h; experiments show that the advanced urea oxidation technology has certain requirements on temperature, and the detection precision of urea can be improved by setting proper temperature; the water carrying flow is constant, the volume of the sample solution in the annular pipeline is constant, and the heating coil HC with a certain power is selected to keep the water carrying at a proper temperature by calculation, wherein the temperature is selected to be 20-30 ℃, and is preferably 23-25 ℃.

The detection unit is characterized in that a conductivity cell C1, a conductivity cell C2, a reagent injection device and a mixing coil MC are arranged on a detection pipeline IV, and the urea concentration is obtained through conversion by measuring the conductivity difference before and after advanced oxidation of carrier water; after mixing with reagents E and F with certain volumes in the reagent pipelines, the water passes through a conductivity cell C1, a mixing coil MC to promote reaction, and finally enters a flow cell G through a drainage pipeline after passing through a conductivity cell C2 and a flow sensor F5; the reagents E, F are respectively provided with injection pumps P3 and P4 and flow sensors F3 and F4 for controlling reagent volume and transmitting fluid signals, and the signals of the flow sensor F5 are used as the basis of maintenance and overhaul of the detection unit. The reagent E is an alkaline reagent which can be sodium hydroxide or potassium hydroxide solution, and the concentration is 0.5-2%, preferably 1%; the reagent F is an oxidant combination and is a mixed solution of hypochlorite and bromide salt, preferably sodium salt, the concentration of the hypochlorite is 7-10 mM, the concentration of the bromide salt is 10-15 mM, and the molar ratio of the hypochlorite to the bromide salt is 0.6-0.7; and (3) drawing a working curve of the standard solution according to a comparison method when the volume and the concentration of each solution are constant, and analyzing the concentration of urea in the sample solution.

Example 1: the early advanced oxidation experiments were as follows: taking 2000mL of ultrapure water (TOC <1ppb) at a pure water station of a certain semiconductor factory for experiment, adjusting the adding amount of NaClO and NaBr at 23 ℃, and reasonably adjusting the pH value in the process; wherein, the best condition of the advanced oxidation effect is as follows: preparing a 200ppb urea solution, heating in a water bath to control the temperature to be 23 ℃, adding a 10ppm NaClO solution and a 22ppm NaBr solution, adjusting the pH value to be 8.5-9.0, and finding that the concentration of the urea solution is 40ppb after 30 min.

Under the above experimental conditions, the experiment was carried out while changing the temperature to obtain table 1, and it was found that the influence of the temperature on the reaction was large.

Serial number	Temperature/. degree.C	Concentration/ppb of Urea in the effluent
			1	15	132
2	18	99
			3	20	67
4	23	40
			5	25	42
6	27	40
			7	30	38

Example 2: the invention is formed from example 1, the corresponding device being assembled according to the method described in the invention: standard solutions of 20ppb, 50ppb, 100ppb, 250ppb, 500ppb, 750ppb and 1000ppb urea are respectively supplied to a water inlet end, then the urea concentration of the standard solutions is continuously monitored, the measuring times of each standard solution are 10 times, the results are averaged, the single data measuring time is 2min (the microsyringe is shifted for 1 time every 1 min), and a relation graph of the raw water urea concentration and the conductivity (C1, C2, C2-C1) is obtained (figure 3); in the example of FIG. 3, syringe pump P1 has a flow rate of 5 mL/min; the ultraviolet decomposer A adopts an ultraviolet lamp tube with the wavelength of 185nm and the power of 4W; the organic adsorber B is filled with 30mL of resin at 1BV/h, and the ratio of the macroporous strong base resin to the macroporous weak base resin is 3: 1; the volume of the microsyringe C sample loop was 500 μ L; the flow rate of the injection pump P2 is 10 mL/min; 150mL of resin is filled in the ion absorber D, the resin is 40BV/h, and the ratio of the gel type strong base resin to the gel type strong acid resin is 3: 1; heating coil HC resistance is 10 omega, and water carrying temperature is 23 ℃; reagent E is 1% sodium hydroxide solution, and the flow rate of injection pump P3 is 50 μ L/min; the reagent F is a mixed solution of sodium hypochlorite and sodium bromide, the concentration of the sodium hypochlorite is 9mM, the concentration of the sodium bromide is 14mM, the molar ratio of the sodium hypochlorite to the sodium bromide is 0.6, and the flow rate of a syringe pump P4 is 0.5 mL/min.

As shown in figures 4-6 of the drawings,

an apparatus for quantitatively analyzing a trace amount of urea, which is a peristaltic pump W used in S3; the peristaltic pump W comprises a motor 1, a shell 2, a pump head 11, a rotor 12, rollers 121 and a pump tube 21; an anti-abrasion mechanism 3 is arranged in the peristaltic pump W; the anti-abrasion mechanism 3 comprises a push plate 31, a connecting plate 32 and a limiting rod 33; the push plate 31 is positioned between the pump pipe 21 and the pump head 11, the push plate 31 is arc-shaped, the convex surface of the push plate 31 is attached to the pump pipe 21, the concave surface of the push plate 31 is attached to the roller 121, the push plate 31 is fixedly connected with the connecting plate 32 opposite to the bottom of the shell 2, the connecting plate 32 penetrates through a gap between the pump pipe 21 and the inner bottom surface of the shell 2, the connecting plate 32 is provided with a sliding hole 321, and the inner gap of the sliding hole 321 is in clearance fit with the limiting rod 33; the limiting rod 33 is positioned above the pump pipe 21, and one end of the limiting rod 33 is fixedly connected to the inner bottom surface of the shell 2; when the peristaltic pump W works, the rollers 121 rotate around the center position of the rotor 12, meanwhile, the rollers 121 extrude the pump pipe 21 to generate friction blocks, liquid in the pump pipe 21 is pushed out of the pump pipe 21, meanwhile, rolling friction occurs between the rollers 121 and the pump pipe 21, the rollers 121 rub the surface of the pump pipe 21, after the pump pipe 21 runs for a long time, the wall of the pump pipe 21 is gradually abraded and thinned, when the pump pipe 21 is seriously abraded and broken, and liquid leaks to cause that the peristaltic pump W cannot be used, therefore, the rollers 121 are arranged between the pump pipe 21 and the rollers 121 to avoid destructive abrasion of the pump pipe 21; when the roller 121 rotates around the center of the rotor 12, the roller 121 presses the push plate 31, the push plate 31 presses the pump tube 21, then the liquid in the pump tube 21 is extruded, meanwhile, the push plate 31 pushes the connection, the through hole of the connection plate 32 is limited by the limiting rod 33, the connection plate 32 moves upwards, and when the roller 121 does not press the push plate 31, the push plate 31 is pushed back to the initial position by the elasticity of the pump tube 21, so that the pump tube 21 sucks new liquid again.

As an embodiment of the present invention, a return spring 322 is disposed in the sliding hole 321; one end of the return spring 322 is fixedly connected to the side wall of the sliding hole 321, and the other end of the return spring 322 is fixedly connected to the limiting rod 33; when the connecting plate 32 moves, the connecting plate 32 extrudes the return spring 322, the return spring 322 pulls the limiting rod 33, and pulls the push plate 31 downwards, at this time, the push plate 31 moves downwards, the roller 121 can effectively extrude the push plate 31 again, the push plate 31 extrudes the pump tube 21, and the pump tube 21 is extruded, the depressed part is not extruded on the push plate 31 any more, and then the initial state is recovered, so that the pump tube 21 is timely recovered to the liquid absorption state, and the pump tube 21 can effectively absorb liquid.

As an embodiment of the present invention, the other end of the limiting rod 33 is provided with a limiting plate 331; the number of the limit plates 331 is two, and the limit plates 331 are symmetrically and fixedly connected to the other end of the limit rod 33; the limiting plate 331 is used for enabling the connecting plate 32 to be attached to the inner bottom surface of the shell 2 to move, and the end portion of the connecting plate 32 is prevented from tilting, so that the push plate 31 is difficult to effectively extrude the pump pipe 21.

Sliding chutes 323 are respectively formed on two sides of the sliding hole 321; the end of the limit plate 331 is slidably connected in the slide groove 323.

As an embodiment of the present invention, the sliding groove 323 is arc-shaped, and the concave surfaces of the sliding groove 323 are designed oppositely; the limiting plate 331 slides in the arc-shaped sliding groove 323, so that the moving track of the connecting plate 32 is limited, the effective action point of the push plate 31 to press the pump tube 21 is limited, the amount of pressing deformation of the pump tube 21 is kept the same each time, and the liquid amount flowing out of the pump tube 21 is kept the same.

The working principle is as follows: when the roller 121 rotates around the center of the rotor 12, the roller 121 presses the push plate 31, the push plate 31 presses the pump tube 21, then the liquid in the pump tube 21 is extruded, meanwhile, the push plate 31 is pushed to be connected, the through hole of the connecting plate 32 is limited by the limiting rod 33, the connecting plate 32 moves upwards, when the roller 121 does not press the push plate 31, the push plate 31 is pushed back to the initial position by the elasticity of the pump tube 21, so that the pump tube 21 pumps new liquid again; the anti-abrasion mechanism 3 is arranged between the pump pipe 21 and the rollers 121, so that the rollers 121 are prevented from generating destructive abrasion on the pump pipe 21, and the service life of the pump pipe 21 is prolonged; when the connecting plate 32 moves, the connecting plate 32 extrudes the return spring 322, meanwhile, the return spring 322 pulls the limiting rod 33, and pulls the push plate 31 downwards, at this time, the push plate 31 moves downwards, meanwhile, the roller 121 can effectively extrude the push plate 31 again, the push plate 31 can recover the initial state after extruding the pump tube 21 and the extruded depressed part of the pump tube 21 does not extrude the push plate 31 any more, so that the pump tube 21 can recover to the liquid absorption state in time, and the pump tube 21 can effectively absorb liquid; meanwhile, the limiting plate 331 slides in the arc-shaped sliding groove 323, so that the moving track of the connecting plate 32 is limited, the effective action point of the push plate 31 to extrude the pump tube 21 is limited, the extrusion deformation amount of the pump tube 21 is kept the same each time, and the liquid amount flowing out of the pump tube 21 is kept the same.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.