Photoacoustic gas detection device

Abstract

The embodiment of the utility model discloses a photoacoustic gas detection device, and relates to the field of to-be-detected gas detection devices. In one specific embodiment, the device comprises an air pump, a photoacoustic cavity and at least one airflow buffer device, wherein the airflow buffer device comprises a buffer unit; the first valve is arranged on a gas circulation channel between the gas inlet of the gas flow buffer device and the ventilation port of the buffer unit; the second valve is arranged on a gas circulation channel between the gas outlet and the gas vent of the gas flow buffer device; according to the embodiment, the process of supplying air to the photoacoustic cavity is divided into an air supplying process and an air discharging process which are alternately carried out through the buffer unit and the first valve and the second valve at the two ends of the buffer unit, so that noise generated by an air pump is prevented from being transmitted into the photoacoustic cavity; the gas flow area of the first valve in the open state is controlled to be larger than the gas flow area of the second valve in the open state, so that the gas flow is more stable.

Description

Technical Field

[0001] The utility model relates to the field of gas detection devices to be detected. More specifically, it relates to a photoacoustic gas detection device. Background Art

[0002] At present, a photoacoustic gas detection device based on photoacoustic spectroscopy inputs a laser pulse into the gas to be detected. The corresponding gas to be detected absorbs light energy and then generates sound. The resonance sound field of the gas to be detected in the photoacoustic cavity is received by a microphone device, and the concentration of the gas to be detected that can absorb the laser wavelength in the gas to be detected is deduced inversely. Since the signal sampling device uses a microphone to detect mechanical waves, i.e., sound waves, in the gas to be detected. When detecting, an air pump is required to pump the gas to be detected into the photoacoustic cavity of the photoacoustic gas detection device. Among them, the pressure fluctuation is relatively large when the air pump pumps in the gas to be detected, which will form noise in the sound field and reduce the sensitivity of the system.

[0003] The prior art attenuates the sound wave noise in the entire gas path by adding a muffler in the gas path. However, the noise reduction ability of using a muffler is limited, and part of the noise caused by pressure fluctuation will still be transmitted to the photoacoustic cavity of the photoacoustic gas detection device, reducing the sensitivity of the system. Summary of the Utility Model

[0004] The purpose of the utility model is to provide a photoacoustic gas detection device that divides the test process into a gas storage process and a gas release process to eliminate the influence of noise brought by the air pump on detection, so as to solve at least one of the problems existing in the prior art.

[0005] To achieve the above purpose, the utility model adopts the following technical solutions:

[0006] The utility model provides a photoacoustic gas detection device, including: an air pump, a photoacoustic cavity and at least one air flow buffer device. The air inlet of the air flow buffer device is connected to the air outlet of the air pump, and the air outlet of the air flow buffer device is connected to the air inlet of the photoacoustic cavity. The air flow buffer device includes:

[0007] A buffer unit;

[0008] A first valve arranged on the gas flow channel between the air inlet of the air flow buffer device and the ventilation port of the buffer unit; and

[0009] A second valve arranged on the gas flow channel between the air outlet of the air flow buffer device and the ventilation port;

[0010] Wherein, the gas flow area in the open state of the first valve is larger than the gas flow area in the open state of the second valve.

[0011] Further, the first valve and the second valve are respectively electronically controlled regulating valves with adjustable opening degrees.

[0012] Further, the first valve and the second valve have the same nominal diameter.

[0013] Further, the buffer unit includes an elastic airbag.

[0014] Further, the buffer unit includes a cylinder and a piston. The piston is arranged inside the cylinder, and the edge of the piston is in sealed sliding connection with the cylinder.

[0015] Further, the buffer unit further includes a spring arranged on the side of the piston away from the air vent.

[0016] Further, the photoacoustic gas detection device includes at least two air flow buffer devices.

[0017] Further, the photoacoustic gas detection device further includes a filtering device arranged at the air inlet of the air pump.

[0018] Further, the air pump is a silent air pump.

[0019] The beneficial effects of the present utility model are as follows:

[0020] Through the buffer unit and the first valve and the second valve at both ends of the buffer unit, the process of supplying gas to the photoacoustic cavity of the photoacoustic detection unit by the air pump is divided into a gas supply process and a deflation process, and the two processes are separated in time and carried out alternately, avoiding the noise generated by the air pump from being transmitted into the photoacoustic cavity; by controlling that the gas flow area in the opened state of the first valve is larger than the gas flow area in the opened state of the second valve, the gas filling speed of the air pump is greater than the deflation speed of the buffer unit, so that the buffer unit can slowly discharge the gas to be detected, and the air flow is more stable; therefore, the pressure fluctuation of the gas to be detected supplied by the present disclosure is smaller and the noise is smaller, which is beneficial to improving the signal-to-noise ratio of the detection device. Description of the Drawings

[0021] The following further describes in detail the specific embodiments of the present utility model with reference to the drawings.

[0022] Figure 1 The structural schematic diagram of the existing photoacoustic gas detection device is shown.

[0023] Figure 2 The structural schematic diagram of a photoacoustic gas detection device provided by an embodiment of the present utility model is shown.

[0024] Figure 3 The structural schematic diagram of a buffer unit in a photoacoustic gas detection device provided by an embodiment of the present utility model is shown.

[0025] Figure 4 Another structural schematic diagram of the buffer unit in the photoacoustic gas detection device provided by the embodiment of the present invention is shown.

[0026] Figure 5 Another structural schematic diagram of the photoacoustic gas detection device provided by the embodiment of the present invention is shown. Detailed implementation manners

[0027] To describe the present invention more clearly, the present invention will be further described below in conjunction with embodiments and drawings. Similar components in the drawings are denoted by the same reference numerals. Those skilled in the art should understand that the content specifically described below is illustrative rather than restrictive, and should not be used to limit the protection scope of the present invention.

[0028] As Figure 1 shown, the current traditional method for eliminating the noise generated by the air pump is to add a muffler in the gas path to attenuate the acoustic noise in the entire gas path and improve the sensitivity of the system. However, using a muffler can only reduce the noise to a certain extent, and its noise reduction ability is not thorough, and there is still room for improvement in the sensitivity of the entire device.

[0029] As Figure 2 shown, the present invention provides a photoacoustic gas detection device, including: an air pump, a photoacoustic cavity, and at least one air flow buffer device. The air inlet of the air flow buffer device is connected to the air outlet of the air pump, and the air outlet of the air flow buffer device is connected to the air inlet of the photoacoustic cavity. The air flow buffer device includes:

[0030] A buffer unit;

[0031] A first valve provided on the gas flow passage between the air inlet of the air flow buffer device and the vent of the buffer unit; and

[0032] A second valve provided on the gas flow passage between the air outlet of the air flow buffer device and the vent;

[0033] wherein, the gas flow area in the open state of the first valve is larger than the gas flow area in the open state of the second valve.

[0034] In a possible implementation manner, the first valve and the second valve are respectively electronically controlled regulating valves with adjustable opening degrees.

[0035] In a possible implementation manner, the first valve and the second valve have the same nominal diameter.

[0036] In a possible implementation manner, as Figure 3As shown, the buffer unit includes an elastic airbag 1. Its working principle includes: when the first valve is open and the second valve is closed, the gas to be detected transported by the air pump is filled into the elastic airbag 1 through the first valve and the ventilation port; or, when the second valve is open and the first valve is closed, the gas to be detected in the elastic airbag 1 is discharged to the photoacoustic cavity through the ventilation port and the second valve.

[0037] In a possible implementation, as Figure 4 shown, the buffer unit includes a cylinder 2 and a piston 3. The piston 3 is arranged inside the cylinder 2, and the edge of the piston 3 is in sealed sliding connection with the cylinder 2.

[0038] In a possible implementation, the buffer unit further includes a spring 4 arranged on the side of the piston 3 away from the ventilation port. The specific working principle of this embodiment is that when the first valve is open and the second valve is closed, the gas to be detected transported by the air pump is filled into the cylinder 2 through the first valve and the ventilation port; the piston 3 moves in the direction away from the ventilation port under the action of the filled gas to be detected, and the spring 4 is compressed by the extrusion of the piston 3; or, when the second valve is open and the first valve is closed, the piston 3 moves in the direction close to the second buffer gas port under the action of the spring 4 and the air pressure in the space where the spring 4 is located, so as to discharge the gas to be detected in the cylinder 2 to the photoacoustic cavity through the ventilation port and the second valve.

[0039] In a possible implementation, the photoacoustic gas detection device includes at least two airflow buffer devices.

[0040] In a possible implementation, the photoacoustic gas detection device further includes a filtering device arranged at the air inlet of the air pump.

[0041] In a possible implementation, the air pump is a silent air pump. In this disclosure, a silent air pump is used for the air pump, and its vibration is smaller to avoid vibration being transmitted to the photoacoustic cavity.

[0042] In a specific example, as Figure 2 shown, in this embodiment, there is one airflow buffer device, and its working principle is as follows:

[0043] Inflation process: The first valve is open and the second valve is closed. The air pump is started, and the gas to be detected transported by the air pump is filled into the buffer unit through the first valve.

[0044] Deflation process: The second valve is open and the first valve is closed. The gas to be detected in the buffer unit is discharged to the photoacoustic cavity through the second valve.

[0045] To make the gas flow rate for inflating the buffer unit greater than the gas flow rate for deflating the buffer unit, the gas flow area in the open state of the first valve is greater than the gas flow area in the open state of the second valve, so that the deflation speed of the buffer unit should be as slow as possible.

[0046] Through a buffer unit, a first valve and a second valve at both ends of the buffer unit, the process of supplying gas to the photoacoustic cavity of the photoacoustic detection unit by a gas pump is divided into a gas supply process and a deflation process, and the two processes are separated in time and alternated, avoiding the noise generated by the gas pump from being transmitted into the photoacoustic cavity; by controlling the gas flow area of the open state of the first valve to be larger than the gas flow area of the open state of the second valve, the gas filling speed of the gas pump is greater than the deflation speed of the buffer unit, so that the buffer unit can slowly discharge the gas to be detected, and the air flow is more stable; therefore, the pressure fluctuation of the gas to be detected supplied by the present disclosure is smaller and the noise is smaller, which is beneficial to improving the signal-to-noise ratio of the detection device.

[0047] In another specific example, as Figure 5 shown, in this embodiment, there are two gas flow buffer devices, including a 1# gas flow buffer device and a 2# gas flow buffer device. The 1# gas flow buffer device includes a 1# first valve, a 1# second valve and a 1# buffer unit, and the 2# gas flow buffer device includes a 2# first valve, a 2# second valve and a 2# buffer unit. The working process of this embodiment is as follows:

[0048] Open the 1# first valve, and close the 1# second valve, the 2# first valve and the 2# second valve. The gas pump starts to work, and the gas pump transports the gas to be detected and fills it into the 1# buffer unit through the 1# first valve;

[0049] Close the 1# first valve and the 2# second valve, open the 1# second valve and the 2# first valve, discharge the gas to be detected in the 1# buffer unit to the photoacoustic cavity of the photoacoustic detection unit through the 1# second valve, and discharge it through the air outlet of the photoacoustic cavity, so that the photoacoustic gas detection device detects the gas to be detected. At the same time, the gas pump transports the gas to be detected and fills it into the 2# buffer unit through the 2# first valve;

[0050] Open the 1# first valve and the 2# second valve, close the 1# second valve and the 2# first valve, discharge the gas to be detected in the 2# buffer unit to the photoacoustic cavity of the photoacoustic detection unit through the 2# second valve, and discharge it through the air outlet of the photoacoustic cavity, so that the photoacoustic gas detection device detects the gas to be detected. At the same time, the gas pump transports the gas to be detected and fills it into the 1# buffer unit through the 1# first valve;

[0051] The 1# buffer unit and the 2# buffer unit alternately supply gas to the photoacoustic cavity of the photoacoustic detection unit, thereby realizing continuous gas detection.

[0052] Similarly, when there are more than two gas flow buffer devices, the working principle is the same as above and will not be elaborated here.

[0053] In this embodiment, the No. 1 buffer unit or the No. 2 buffer unit can stop the inflation process when the internal air pressure is greater than the first preset pressure threshold, or can stop the inflation when the inflation time is greater than the first preset time threshold. Similarly, for the deflation process, it can stop the deflation process when the internal air pressure is lower than the second preset pressure threshold, or can stop the deflation when the deflation time is greater than the preset time threshold. There is no limitation here.

[0054] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by terms such as "upper" and "lower" is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention. Unless otherwise clearly specified and defined, the terms "installation", "connection" and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0055] It should also be noted that in the description of the present invention, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variation thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, the element defined by the statement "including a..." does not exclude the existence of additional identical elements in the process, method, article or device including the element.

[0056] Obviously, the above embodiments of the present invention are only examples for clearly illustrating the present invention, rather than limitations on the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is impossible to list all the implementation manners here. Any obvious changes or modifications derived from the technical solutions of the present invention still fall within the protection scope of the present invention.

Claims

1. A photoacoustic gas detection device, characterized in that Comprising: An air pump, a photoacoustic cavity, and at least one air flow buffer device. The air inlet of the air flow buffer device is connected to the air outlet of the air pump, and the air outlet of the air flow buffer device is connected to the air inlet of the photoacoustic cavity. The air flow buffer device includes: A buffer unit; A first valve disposed on the gas flow passage between the air inlet of the air flow buffer device and the ventilation port of the buffer unit; and A second valve disposed on the gas flow passage between the air outlet of the air flow buffer device and the ventilation port; Wherein, the gas flow area in the open state of the first valve is larger than the gas flow area in the open state of the second valve; The buffer unit includes an airbag or the buffer unit includes a cylinder and a piston; The piston is disposed in the cylinder, and the edge of the piston is in sealed sliding connection with the cylinder; The buffer unit further includes a spring disposed on the side of the piston away from the ventilation port.

2. The photoacoustic gas detection device according to claim 1, wherein The first valve and the second valve are respectively electronically controlled regulating valves with adjustable opening degrees.

3. The photoacoustic gas detection device according to claim 2, characterized in that, The first valve and the second valve have the same nominal diameter.

4. The photoacoustic gas detection device according to claim 1, characterized in that The photoacoustic gas detection device includes at least two air flow buffer devices.

5. The photoacoustic gas detection device according to claim 1, wherein The photoacoustic gas detection device further includes a filtering device disposed at the air inlet of the air pump.

6. The photoacoustic gas detection device according to claim 1, characterized in that, The air pump is a silent air pump.

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