An electrochemical alcohol sensor with an intermittent sampling gas chamber for suppressing baseline drift

Abstract

The application provides an intermittent sampling gas chamber of an electrochemical alcohol sensor for inhibiting baseline drift, belonging to the technical field of alcohol detection, comprising a sampling chamber, a gas chamber is arranged at the central position in the interior of the sampling chamber, a gas inlet is arranged at the central position of the outer wall of one side of the sampling chamber and is communicated with the gas chamber, a gas outlet is arranged at the central position of the outer wall of one side of the sampling chamber adjacent to the gas inlet and is communicated with the gas chamber, a micro stepping motor is fixedly connected to the central position of the bottom of the sampling chamber through bolts, the micro stepping motor is fixedly connected with a valve disc matched with the dynamic seal of the inner wall of the gas chamber through the output end of one side of the micro stepping motor, and a sampling hole and a cleaning hole are arranged in the interior of the valve disc; the application fundamentally inhibits baseline drift: through physical shielding, the sensor is not contacted with the gas in most time, signal drift caused by continuous reaction is avoided from the source, and the accuracy and stability of measurement are significantly improved.

Description

Technical Field

[0001] This invention belongs to the field of alcohol detection technology, specifically relating to an intermittent sampling gas chamber for an electrochemical alcohol sensor that suppresses baseline drift. Background Technology

[0002] Electrochemical alcohol sensors are widely used in portable breathalyzers due to their low cost, small size, and high sensitivity. However, their working principle dictates that when in continuous contact with the gas being tested, the internal electrolyte continuously participates in the redox reaction. This causes the output signal to slowly and continuously rise over time, even if the gas concentration is constant. This phenomenon is known as "baseline drift," which leads to serious measurement errors in applications requiring long-term, continuous gas monitoring or high-precision quantitative analysis (such as law enforcement testing).

[0003] Existing solutions mostly use software algorithm compensation or timed on / off solenoid valves for the air circuit. Software compensation models are complex and easily affected by environmental interference, resulting in limited effectiveness. Traditional solenoid valve control solutions suffer from problems such as large size, high power consumption, slow action, limited lifespan, and high price, making them unsuitable for miniaturized, low-cost portable devices.

[0004] Therefore, an intermittent sampling gas chamber for an electrochemical alcohol sensor that suppresses baseline drift is proposed. Summary of the Invention

[0005] This invention provides an intermittent sampling gas chamber for an electrochemical alcohol sensor to suppress baseline drift. Its purpose is to solve the problems mentioned above and provide a mechanical intermittent sampling gas chamber with ingenious structure, low power consumption, and high reliability, which physically blocks the continuous contact between the sensor and the gas, thereby fundamentally suppressing baseline drift.

[0006] This invention provides an intermittent sampling gas chamber for an electrochemical alcohol sensor to suppress baseline drift. The chamber includes a sampling chamber with a gas chamber located at its center. An air inlet communicating with the gas chamber is located at the center of one side of the outer wall of the sampling chamber. An air outlet communicating with the gas chamber is located at the center of the other side of the outer wall adjacent to the air inlet. A micro stepper motor is bolted to the center of the bottom of the sampling chamber. The micro stepper motor has a valve disc that dynamically seals against the inner wall of the gas chamber via its output end. The valve disc has a sampling hole and a cleaning hole inside. The sampling port is located on one side of the cleaning port and is not connected. A circular hole is provided at the center of the top of the valve disc. A detection port is provided on the inner wall of the circular hole. The detection port is connected to the sampling port. A cylinder is embedded in the circular hole and dynamically seals with its inner wall. The cylinder passes through the top of the sampling chamber. A threaded hole is provided on the outer circumference of the cylinder near the axial position of the detection port. An electrochemical alcohol sensor is connected to the inside of the threaded hole by threaded engagement. One end of the electrochemical alcohol sensor is provided with a sensor sensing surface. A mounting plate is provided on the top of the cylinder. The mounting plate is fixedly connected to the top of the sampling chamber.

[0007] Furthermore, an exhaust port is provided at the center of the outer wall on the other side of the sampling chamber, and a gas inlet channel one is provided at the center of the outer wall on the other side of the sampling chamber adjacent to the air inlet. Both the exhaust port and the gas inlet channel one are connected to the air chamber. A gas inlet channel two is provided on one side of the outer wall of the sampling chamber near the gas inlet channel one. The gas inlet channel two is connected to the air inlet, and a support ring and a limiting ring are provided on the inner side wall of the gas inlet channel two. The limiting ring is located between the air inlet and the support ring. A spring is provided on the outer wall of the support ring facing the limiting ring. A pneumatic plunger is provided at one end of the spring. The limiting ring is located between the pneumatic plunger and the support ring.

[0008] Furthermore, the pneumatic plunger has a guide hole one at one end facing the spring, and a guide hole two communicating with the guide hole one is opened on the outer circumferential surface of the pneumatic plunger. The other end of the pneumatic plunger has a hole mating surface that matches and fits the inner wall of the air inlet.

[0009] Furthermore, on the outer wall of the sampling chamber, near one end of the air inlet, air outlet, exhaust outlet, gas inlet channel one, and gas inlet channel two, an air inlet pipe, an air outlet pipe, an exhaust pipe, a connecting pipe one, and a connecting pipe two are respectively connected and installed. The other end of the connecting pipe one and the connecting pipe two is provided with an air box. An exhaust fan is installed inside the air box, and a filter hole is opened on the outer wall of the air box near the air inlet of the exhaust fan.

[0010] Furthermore, a controller is also installed in the sampling chamber. The controller is electrically connected to a micro stepper motor and an electrochemical alcohol sensor. The controller performs the following operations cyclically according to a fixed period: controlling the micro stepper motor to move the valve disc into the sampling position and maintain it for a first predetermined time, and then controlling the micro stepper motor to move the valve disc into the cleaning position and maintain it for a second predetermined time, wherein the second predetermined time is longer than the first predetermined time. The controller is configured to acquire the peak signal output by the electrochemical alcohol sensor as a valid measurement value when the valve disc is in the sampling position.

[0011] Furthermore, the sampling position is the state when both the air inlet and the air outlet are connected to the sampling hole, at which time a "sampling airflow path" is formed; the cleaning position is the state when both the air inlet and the air outlet are connected to the cleaning hole, at which time a "cleaning airflow path" is formed. By adopting the above technical solution, the "sampling airflow path" and "cleaning airflow path" can be set up so that sampling and cleaning are relatively independent and do not interfere with each other. During cleaning, fresh air or clean purge air can be used to flow directly through the air chamber to wash away the residual alcohol molecules in the chamber. However, the sensor sensing surface is protected by the valve disc and isolated from the airflow, so that the "sampling" and "cleaning" stages do not interfere with each other and can cycle together.

[0012] Furthermore, the bottom of the sampling chamber is symmetrically provided with four support legs. The cross-section of the support legs is L-shaped, and the protruding part of the support legs is provided with mounting holes. After the support legs are installed, the micro stepper motor is in a suspended state. By adopting the above technical solution, the sampling chamber can be installed in the portable breathalyzer using the support legs, and the protruding design of the micro stepper motor can be avoided from affecting the installation of the sampling chamber.

[0013] Furthermore, when no gas is introduced into the gas inlet channel two, the pneumatic plunger is pulled by the spring so that one end of it abuts against the limiting ring, and the hole mating surface coincides with the inner wall of the air inlet; By adopting the above technical solution, when the gas chamber is not being cleaned, the pneumatic plunger does not extend into the air inlet, and the air inlet is in a clear state, allowing gas sampling to be performed so that gas can enter. When the gas chamber is being cleaned, pressurized gas enters the second channel, and the gas pressure pushes the pneumatic plunger toward the air inlet. The spring is stretched, and part of the pneumatic plunger extends into the air inlet. At this time, the second guide hole on the pneumatic plunger is located inside the air inlet. With the connection between the first guide hole and the second guide hole, the air inlet and the second gas inlet are connected, allowing gas to enter the air inlet and clean the air inlet, cleaning hole, and air outlet with gas.

[0014] Furthermore, the air inlet, air outlet, exhaust outlet, and gas entry channel are arranged in a "+" shape with the center of the valve disc as the center point; By adopting the above technical solution, the air inlet, air outlet, exhaust outlet and gas inlet channel 1 are made to be perpendicular to each other, so that the sampling and cleaning can be alternated by controlling the valve disc to rotate 180 degrees.

[0015] The beneficial effects of this invention are as follows: 1. Fundamentally suppress baseline drift: By physically shielding the sensor from contact with the gas most of the time, signal drift caused by continuous reaction is avoided at the source, significantly improving the accuracy and stability of the measurement.

[0016] 2. Automatic cleaning: The unique "cleaning path" design can automatically flush the air chamber while the sensor is in sleep mode, eliminating cross-contamination of sample residues for the next measurement, making it particularly suitable for continuous testing scenarios.

[0017] 3. Low power consumption and long lifespan: The micro stepper motor only consumes power during the switching moment and remains static for a long time. Its overall power consumption is much lower than that of the solenoid valve solution, which requires continuous power supply. The lifespan of the mechanical structure is also usually longer than that of the solenoid valve with frequent operation.

[0018] 4. Compact structure and low cost: The sampling, masking and cleaning functions are integrated into a single rotary valve disc, resulting in a very compact structure that is easy to integrate into portable devices. Compared to a complete solenoid valve system, it is more cost-effective.

[0019] 5. High data quality: Each sampling is a "fresh" measurement performed after the sensor baseline is restored, resulting in good repeatability of the obtained peak signal, which greatly reduces the interpretation error and false alarm risk caused by baseline drift.

[0020] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the description and the drawings. Attached Figure Description

[0021] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of the structure of an embodiment of the present invention; Figure 2 This is a cross-sectional three-dimensional schematic diagram of an embodiment of the present invention; Figure 3 This is a three-dimensional cross-sectional schematic diagram of the sampling chamber according to an embodiment of the present invention; Figure 4 This is a three-dimensional cross-sectional schematic diagram of the valve disc according to an embodiment of the present invention; Figure 5 This is a schematic diagram of the valve disc and cylinder mating according to an embodiment of the present invention; Figure 6 This is a schematic diagram illustrating the combination of a cylindrical structure and an electrochemical alcohol sensor according to an embodiment of the present invention. Figure 7 This is a schematic diagram of the pneumatic plunger structure according to an embodiment of the present invention; Figure 8 This is a schematic diagram of the sampling chamber structure according to an embodiment of the present invention; Reference numerals: 1. Sampling chamber; 11. Gas chamber; 12. Air inlet; 121. Air inlet pipe; 13. Air outlet; 131. Air outlet pipe; 14. Exhaust port; 141. Exhaust pipe; 15. Gas inlet channel one; 151. Connecting pipe one; 16. Gas inlet channel two; 161. Connecting pipe two; 162. Support ring; 163. Limiting ring; 164. Spring; 165. Pneumatic plunger; 1651. Guide hole one; 1652. Guide hole two; 1653. Hole mating surface; 2. Miniature stepper motor; 3. Valve disc; 31. Sampling hole; 32. Cleaning hole; 33. Round hole; 34. Detection port; 4. Cylindrical; 41. Threaded hole; 42. Electrochemical alcohol sensor; 421. Sensor sensing surface; 43. Mounting plate; 5. Gas box; 51. Filter hole; 6. Support leg. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. The same reference numerals in the drawings represent the same components. It should be noted that the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0023] Example 1 Reference Figure 1-6This invention proposes an intermittent sampling chamber for an electrochemical alcohol sensor to suppress baseline drift. The chamber includes a sampling chamber 1, with a gas chamber 11 located at its center. An air inlet 12, connected to the gas chamber 11, is located at the center of one outer wall of the sampling chamber 1. An air outlet 13, also connected to the gas chamber 11, is located at the center of the outer wall of the sampling chamber 1 adjacent to the air inlet 12. A micro stepper motor 2 is bolted to the center of the bottom of the sampling chamber 1. Four support legs 6 are symmetrically arranged at the bottom of the sampling chamber 1. The support legs 6 have an L-shaped cross-section, and their protruding parts have mounting holes. After installation, the micro stepper motor 2 is suspended in the air. The support legs 6 allow the sampling chamber 1 to be installed in a portable breathalyzer, preventing the protruding micro stepper motor 2 from interfering with the installation of the sampling chamber 1. A miniature stepper motor 2 is fixedly connected to a valve disc 3 that dynamically seals with the inner wall of the gas chamber 11 via its output end on one side. The valve disc 3 has a sampling hole 31 and a cleaning hole 32 inside. The sampling hole 31 is located on one side of the cleaning hole 32 and is not connected. A circular hole 33 is opened at the center of the top of the valve disc 3. A detection port 34 is opened on the inner wall of the circular hole 33. The detection port 34 is connected to the sampling hole 31. A cylinder 4 that dynamically seals with its inner wall is embedded inside the circular hole 33. The cylinder 4 passes through the top of the sampling chamber 1. A threaded hole 41 is opened on the outer circumference of the cylinder 4 near the axial position of the detection port 34. An electrochemical alcohol sensor 42 is connected inside the threaded hole 41 by threaded engagement. A sensor sensing surface 421 is provided at one end of the electrochemical alcohol sensor 42. A mounting plate 43 is provided on the top of the cylinder 4. The mounting plate 43 is fixedly connected to the top of the sampling chamber 1. A controller is also installed in sampling chamber 1. The controller is electrically connected to the micro stepper motor 2, the electrochemical alcohol sensor 42, and the exhaust fan. The controller performs the following operations cyclically according to a fixed period: controlling the micro stepper motor 2 to move the valve disc 3 into the sampling position and maintain it for a first predetermined time; then controlling the micro stepper motor 2 to move the valve disc 3 into the cleaning position and maintain it for a second predetermined time, wherein the second predetermined time is longer than the first predetermined time. The controller is configured to collect the peak signal output by the electrochemical alcohol sensor 42 as a valid measurement value when the valve disc 3 is in the sampling position. The sampling positions are: both the air inlet 12 and the air outlet 13 are adjacent to the sampling hole. When 31 is connected, a "sampling airflow path" is formed. The cleaning position is when both the air inlet 12 and the air outlet 13 are connected to the cleaning hole 32, forming a "cleaning airflow path". By using the "sampling airflow path" and the "cleaning airflow path", sampling and cleaning can be in a relatively independent state, without interfering with each other. During cleaning, fresh air or clean purge air can be used to flow directly through the air chamber 11 to wash away the residual alcohol molecules in the chamber. However, the sensor sensing surface 421 is protected by the valve disc 3 and isolated from the airflow, so that the "sampling" and "cleaning" stages do not interfere with each other and can cycle back and forth. In this embodiment, when using sampling chamber 1 to detect alcohol in the gas, it is necessary to go through a sampling stage, a cleaning / dormancy stage, and a cyclic repetition stage, specifically: Sampling stage: The micro stepper motor 2 controls the valve disc 3 to rotate, so that the two ends of the sampling hole 31 on the valve disc 3 are aligned with the air inlet 12 and the air outlet 13 respectively. At this time, with the detection port 34 connected, the sampling hole 31, the air inlet 12, the sensor sensing surface 421 and the air outlet 13 form a "sampling airflow path". The gas to be detected passes through the air inlet pipe 121 and then passes through the air inlet 12, the sampling hole 31 and the air outlet 12 in sequence. The gas to be detected flows through the sensor sensing surface 421, and the electrochemical alcohol sensor 42 generates a response signal. This stage lasts for a short fixed time (such as 3-5 seconds) to obtain a stable peak reading. Cleaning / Sleep Phase: The micro stepper motor 2 controls the valve disc 3 to rotate 180 degrees, so that the two ends of the cleaning hole 32 on the valve disc 3 are aligned with the air inlet 12 and the air outlet 13 respectively. At the same time, as the valve disc 3 rotates, the detection port 34 on the inner wall of the valve disc 3 moves circumferentially in sync. The detection port 34 is misaligned with the sensor sensing surface 421, and the solid part of the valve disc 3 completely covers the sensor sensing surface 421. At this time, clean purge gas (or ambient air) passes through the air inlet pipe 121 and then through the air inlet 12, the cleaning hole 32 and the air inlet 12 in sequence, thoroughly removing the alcohol vapor remaining from the previous cycle. At the same time, the electrochemical alcohol sensor 42 stops reacting because it is isolated from the gas, the signal drops rapidly, and the baseline is restored. This phase lasts much longer than the sampling phase (e.g., 25-30 seconds). 3. Cyclic Repetition: The controller executes the "sampling" and "cleaning / sleep" phases cyclically according to the preset duty cycle.

[0024] Example 2 Reference Figure 1-8 Based on the above embodiments, this embodiment of the invention further proposes that an exhaust port 14 is provided at the center of the outer wall on the other side of the sampling chamber 1, and a gas inlet channel 15 is provided at the center of the outer wall on the other side of the sampling chamber 1 adjacent to the air inlet 12. Both the exhaust port 14 and the gas inlet channel 15 are connected to the gas chamber 11. The air inlet 12, air outlet 13, exhaust port 14, and gas inlet channel 15 are arranged in a "+" shape with the axis of the valve disc 3 as the center, so that the air inlet 12, air outlet 13, exhaust port 14, and gas inlet channel 15 are perpendicular to each other, thereby controlling the valve disc 3 to rotate 1. Sampling and cleaning can be alternated at 80 degrees. A second gas inlet channel 16 is provided on one side of the outer wall of the sampling chamber 1, near the gas inlet channel 15. The second gas inlet channel 16 is connected to the air inlet 12. A support ring 162 and a limiting ring 163 are provided on the inner wall of the second gas inlet channel 16. The limiting ring 163 is located between the air inlet 12 and the support ring 162. A spring 164 is provided on the outer wall of the support ring 162 facing the limiting ring 163. A pneumatic plunger 165 is provided at one end of the spring 164. The limiting ring 163 is located between the pneumatic plunger 165 and the support ring 162. The pneumatic plunger 165 has a guide hole 1651 at one end facing the spring 164, and a guide hole 1652 communicating with the guide hole 1651 is opened on the outer circumferential surface of the pneumatic plunger 165. The other end of the pneumatic plunger 165 has a hole mating surface 1653 that matches and fits the inner wall of the air inlet 12. When no gas is introduced into the gas inlet channel 16, the pneumatic plunger 165 is pulled by the spring 164 so that one end of it abuts against the limiting ring 163. The upper hole mating surface 1653 coincides with the inner wall of the air inlet 12. When the air chamber 11 is not being cleaned, the pneumatic plunger 165 does not extend into the air inlet 12, and the air inlet 12 is in a clear state, allowing gas sampling to be performed so that gas can enter. When the air chamber 11 is being cleaned, pressurized gas from outside enters the gas inlet channel 2 16, and the gas pressure pushes the pneumatic plunger 165 toward the air inlet 12, causing the spring 164 to be... When stretched, a portion of the pneumatic plunger 165 extends into the air inlet 12. At this time, the second guide hole 1652 on the pneumatic plunger 165 is located inside the air inlet 12. With the connection between the first guide hole 1651 and the second guide hole 1652, the air inlet 12 and the second gas inlet channel 16 are connected, allowing gas to enter the air inlet 12 and clean the air inlet 12, cleaning hole 32, and air outlet 13. The outer wall of the sampling chamber 1 near the air inlet... At one end of the inlet 12, outlet 13, exhaust outlet 14, gas inlet channel 15 and gas inlet channel 2 16, an inlet pipe 121, an outlet pipe 131, an exhaust pipe 141, a connecting pipe 151 and a connecting pipe 2 161 are respectively connected and installed. At the other end of the connecting pipe 151 and the connecting pipe 2 161, an air box 5 is provided. An exhaust fan is installed inside the air box 5, and a filter hole 51 is opened on the outer wall of the air box 5 near the air inlet of the exhaust fan. To clean the sampling hole 31 when it is not being sampled and to prevent alcohol residue from remaining in it, this embodiment uses external pressurized gas to clean the sampling hole 31 separately. This thoroughly removes residual alcohol vapor from the previous cycle, ensuring the accuracy of alcohol content detection in the gas during the next cycle. Specifically, when the cleaning operation is performed, the cleaning hole 32 on the valve disc 3 is connected to the inlet 12 and the outlet 13, and the sampling hole 31 on the valve disc 3 is connected to the exhaust port 14 and the first gas inlet channel 15, forming two independent gas flow channels. The exhaust fan is controlled to draw external gas through the filter hole 51 and into the first connecting pipe 151 and the second connecting pipe 161. A portion of the gas passes through the first gas inlet channel 15, the sampling hole 31, and the exhaust port 14 in sequence, and is discharged through the exhaust pipe 141. The other portion of the gas passes through the second gas inlet channel 16, the inlet 12, the cleaning hole 32, and the outlet in sequence. The gas enters through the outlet 13 and is discharged through the outlet pipe 131. The gas can completely remove the residual alcohol vapor from the previous cycle, ensuring the accuracy of alcohol content detection in the gas in the next cycle. When pressurized gas enters the second channel 16, the gas pressure pushes the pneumatic plunger 165 toward the inlet 12, and the spring 164 is stretched. A part of the pneumatic plunger 165 extends into the inlet 12. At this time, the second guide hole 1652 on the pneumatic plunger 165 is located inside the inlet 12. With the connection of the first guide hole 1651 and the second guide hole 1652, the inlet 12 and the gas entry channel 16 are connected, allowing the gas to enter the inlet 12 and clean the inlet 12, the cleaning hole 32 and the outlet 13. During the cleaning process, the sensor sensing surface 421 is completely shielded, the electrochemical alcohol sensor 42 is isolated from the gas, stops reacting, the signal drops rapidly, and the baseline is restored.

[0025] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. An intermittent sampling gas chamber for an electrochemical alcohol sensor that suppresses baseline drift, characterized in that: The sample includes a sampling chamber (1), an air chamber (11) is provided at the center of the sampling chamber (1), and an air inlet (12) connected to the air chamber (11) is provided at the center of one side of the outer wall of the sampling chamber (1). An air outlet (13) connected to the air chamber (11) is provided at the center of the outer wall of the sampling chamber (1) adjacent to the air inlet (12). A micro stepper motor (2) is fixedly connected to the bottom center of the sampling chamber (1) by bolts. The micro stepper motor (2) is fixedly connected to a valve disc (3) that dynamically seals with the inner wall of the air chamber (11) through its output end. The valve disc (3) has a sampling hole (31) and a cleaning hole (32) inside. The sampling hole (31) is located on one side of the cleaning hole (32) and is not connected. The valve disc (31) has a sampling hole (31) and a cleaning hole (32) inside the sampling chamber (1). 3) A circular hole (33) is provided at the center of the top. A detection port (34) is provided on the inner wall of the circular hole (33). The detection port (34) is connected to the sampling hole (31). A cylinder (4) is embedded in the circular hole (33) and dynamically seals with its inner wall. The cylinder (4) passes through the top of the sampling chamber (1). A threaded hole (41) is provided on the outer circumference of the cylinder (4) near the axial position of the detection port (34). An electrochemical alcohol sensor (42) is connected to the inside of the threaded hole (41) by threaded engagement. A sensor sensing surface (421) is provided at one end of the electrochemical alcohol sensor (42). A mounting plate (43) is provided on the top of the cylinder (4). The mounting plate (43) is fixedly connected to the top of the sampling chamber (1).

2. The intermittent sampling gas chamber of an electrochemical alcohol sensor for suppressing baseline drift according to claim 1, characterized in that: An exhaust port (14) is provided at the center of the outer wall on the other side of the sampling chamber (1), and a gas inlet channel one (15) is provided at the center of the outer wall on the other side of the sampling chamber (1) adjacent to the air inlet (12). Both the exhaust port (14) and the gas inlet channel one (15) are connected to the gas chamber (11). A gas inlet channel two (16) is provided on one side of the outer wall of the sampling chamber (1) near the gas inlet channel one (15). The gas inlet channel two (16) is connected to the air inlet. (12) Connected, and a support ring (162) and a limiting ring (163) are provided on the inner wall of the gas inlet channel (16). The limiting ring (163) is located between the air inlet (12) and the support ring (162). A spring (164) is provided on the outer wall of the support ring (162) facing the limiting ring (163). A pneumatic plunger (165) is provided at one end of the spring (164). The limiting ring (163) is located between the pneumatic plunger (165) and the support ring (162).

3. The intermittent sampling gas chamber of an electrochemical alcohol sensor for suppressing baseline drift according to claim 2, characterized in that: The pneumatic plunger (165) has a flow guide hole 1 (1651) at one end facing the spring (164), and a flow guide hole 2 (1652) connected to the flow guide hole 1 (1651) is opened on the outer peripheral surface of the pneumatic plunger (165). The other end of the pneumatic plunger (165) has a hole mating surface (1653) that matches and fits the inner wall of the air inlet (12).

4. The intermittent sampling gas chamber of an electrochemical alcohol sensor for suppressing baseline drift according to claim 2, characterized in that: On the outer wall of the sampling chamber (1), near one end of the air inlet (12), air outlet (13), exhaust outlet (14), gas inlet channel one (15), and gas inlet channel two (16), an air inlet pipe (121), an air outlet pipe (131), an exhaust pipe (141), a connecting pipe one (151), and a connecting pipe two (161) are respectively connected. At the other end of the connecting pipe one (151) and the connecting pipe two (161), an air box (5) is provided. An exhaust fan is installed inside the air box (5), and a filter hole (51) is opened on the outer wall of the air box (5) near the air inlet of the exhaust fan.

5. The intermittent sampling gas chamber of an electrochemical alcohol sensor for suppressing baseline drift according to claim 1, characterized in that: The sampling chamber (1) is also equipped with a controller, which is electrically connected to a micro stepper motor (2) and an electrochemical alcohol sensor (42). The controller performs the following operations in a fixed cycle: controlling the micro stepper motor (2) to move the valve disc (3) into the sampling position and maintain it for a first predetermined time, and then controlling the micro stepper motor (2) to move the valve disc (3) into the cleaning position and maintain it for a second predetermined time, wherein the second predetermined time is longer than the first predetermined time. The controller is configured to collect the peak signal output by the electrochemical alcohol sensor (42) as a valid measurement value when the valve disc (3) is in the sampling position.

6. The intermittent sampling gas chamber of an electrochemical alcohol sensor for suppressing baseline drift according to claim 5, characterized in that: The sampling position is when both the air inlet (12) and the air outlet (13) are connected to the sampling hole (31), forming a "sampling airflow path". The cleaning position is when both the air inlet (12) and the air outlet (13) are connected to the cleaning hole (32), forming a "cleaning airflow path".

7. The intermittent sampling gas chamber of an electrochemical alcohol sensor for suppressing baseline drift according to claim 1, characterized in that: The bottom of the sampling chamber (1) is symmetrically provided with four support legs (6). The cross-section of the support leg (6) is L-shaped, and the protrusion of the support leg (6) is provided with mounting holes. After the support leg (6) is installed, the micro stepper motor (2) is in a suspended state.

8. The intermittent sampling gas chamber of an electrochemical alcohol sensor for suppressing baseline drift according to claim 3, characterized in that: When no gas is introduced into the gas inlet channel 2 (16), the pneumatic plunger (165) is pulled by the spring (164) so ​​that one end of it abuts against the limiting ring (163), and the hole mating surface (1653) coincides with the inner wall of the air inlet (12).

9. The intermittent sampling gas chamber of an electrochemical alcohol sensor for suppressing baseline drift according to claim 2, characterized in that: The air inlet (12), air outlet (13), exhaust outlet (14) and gas inlet channel (15) are arranged in a "+" shape with the center of the valve disc (3) as the center point.

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