Gas sensor

A gas sensor and external gas technology, applied in instruments, scientific instruments, measuring devices, etc., can solve the problems of inability to miniaturize and large structure of the gas sensor, and achieve the effect of fewer structural parts, fewer process steps, and simpler assembly.

Active Publication Date: 2012-08-15

RAE SYST SHANGHAI

4 Cites 17 Cited by

AI-Extracted Technical Summary

Problems solved by technology

[0004] However, the structure of the above-mentioned ...

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Method used

Adopt stopper 125 to fix the first breathable waterproof membrane 142a on the shell cover 124, the assembly is simple, use the mode of tight fit to realize fixing to the first breathable waterproof membrane 142a, with traditional seal ring, waterproof breathable membrane Compared with the sealing method of thermal fusion on the plastic part, the fixing method of this embodiment is beneficial to simplify the assembly process.

Fig. 5 shows the partial enlarged view of housing 122 of the present embodiment, with reference to Fig. 5, there is via hole 130 on the side wall of housing 122, and wire 132 passes through each electrode in this via hole and gas sensor (measuring electrode, reference electrode and counter electrode) are connected. The way of forming the via hole 130 on the side wall can improve the reliability of preventing and controlling the leakage, and the size of the via hole 130 is controlled to facilitate sealing; moreover, it is different from the conventional wire 132 in the prior art to bypass the casing wall and enter the gas sensor. Compared with the internal method, the routing distance of the wire 132 is smaller. Since the wire 132 is usually made of precious metal such as platinum wire, reducing the routing distance can reduce the cost.

[0035] The external air passes through the dustproof membrane 126, the second breathable and waterproof membrane 142b, the capillary 128, the third breathable and waterproof membrane 142c and the catalyst 118 to the measuring electrode 112 in turn. Wherein, the third air-permeable and waterproof membrane 142c plays a role of sealing on the one hand, preventing the electrolyte inside the gas sensor from leaking into the capillary 128 , and on the other hand, allows the gas to diffuse to the measuring electrode 112 . The second waterproof and gas-permeable membrane 142b prevents water or other substances from entering the capillary 128 from the external environment to block the capillary 128, and on the other hand, allows external air t...

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Abstract

The invention provides a gas sensor, which comprises a shell, a measuring electrode, a support, a counter electrode, a plug and a shell cover. The top of the shell is opened, the bottom of the shell is provided with a flange, and perforative pores are arranged on the bottom wall of the shell in a region surrounded by the flange; the measuring electrode is disposed in the region surrounded by the flange, and external gas reaches the measuring electrode via the pores; the top and the bottom of the support are opened, the support hermetically matches with the flange, and the measuring electrode is fixedly clamped between the shell and the support; the counter electrode is disposed in the support, and a first liquid absorbing material layer is arranged between the counter electrode and the measuring electrode; the plug is provided with an air outlet hole, and the first liquid absorbing material layer and the counter electrode are fixedly clamped between the support and plug; and the shell cover is provided with an opening, the shell cover is detachably connected with the top of the shell, and the opening hermetically matches with the plug and is communicated with the air outlet hole. Miniaturization of the gas sensor is realized, and the gas sensor is compact in structure and fine in liquid leakage prevention property.

Application Domain

Material analysis by electric/magnetic means

Technology Topic

EngineeringFlange +2

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Examples

Experimental program(1)

Example Embodiment

[0030] The present invention will be further described below with reference to specific embodiments and accompanying drawings, but the protection scope of the present invention should not be limited by this.

[0031] figure 1 The cross-sectional structure diagram of the gas sensor of this embodiment is shown. The gas sensor mainly includes: a casing 122, a casing cover 124, a bracket 127, a plug 125, a measuring electrode 112, a first liquid absorbing material layer 144a, and a counter electrode 114, In addition, it also includes a second liquid absorbing material layer 144b, a reference electrode 116, a first breathable waterproof membrane 142a, a second breathable waterproof membrane 142b, a dustproof membrane 126, and a third breathable waterproof membrane 142c.

[0032] The materials of the casing 122, the casing cover 124, the bracket 127 and the plug 125 may be plastic. The outer shape of the casing 122 is cylindrical or approximately cylindrical. After the gas sensor of this embodiment is assembled, the outer diameter is about 10 mm, and the height is about 6 mm.

[0033] The top of the casing 122 is open, the bottom has a flange, and the bottom wall of the casing also has a through capillary hole 128 in the area surrounded by the flange; the measuring electrode 112 is arranged in the area surrounded by the flange, and external gas can pass through The capillary 128 reaches the measurement electrode 112 .

[0034] In this embodiment, a second air-permeable and waterproof membrane 142b is arranged on the outer wall of the bottom of the casing 122, and a dust-proof membrane 126 is arranged on the outer side of the second air-permeable and waterproof membrane 142b; figure 2 The bottom inner wall of the casing 122 is also provided with a third gas permeable waterproof membrane 142c, the third gas permeable waterproof membrane 142c has a catalyst 118, and the measuring electrode 112 is supported on the third gas permeable waterproof membrane 142c.

[0035] The outside air reaches the measuring electrode 112 through the dustproof membrane 126 , the second gas-permeable and waterproof membrane 142 b , the capillary 128 , the third gas-permeable and waterproof membrane 142 c and the catalyst 118 in sequence. The third gas permeable and waterproof membrane 142c plays a role of sealing on the one hand, preventing the electrolyte inside the gas sensor from leaking into the capillary 128, and on the other hand enabling the gas to diffuse to the measuring electrode 112. The second waterproof and breathable membrane 142b on the one hand prevents water or other substances from entering the capillary 128 from the external environment and blocks the capillary 128, and on the other hand enables external air to enter the capillary 128 through the second waterproof and breathable membrane 142b. The dust-proof membrane 126 is located on the outer side wall of the second gas-permeable and waterproof membrane 142b, and is used to prevent dust and other particulate contaminants from entering the gas sensor and protect the working electrode 112 from pollution.

[0036] The dustproof membrane 126 may be made of polypropylene or polyester, and the second breathable waterproof membrane 142b and the third breathable waterproof membrane 142c may be made of Teflon or other suitable materials.

[0037] The top and bottom of the bracket 127 are open, and are sealingly matched with the flange at the bottom of the casing 122 to clamp and fix the measuring electrode 112 between the casing 122 and the bracket 127 . combined at the same time image 3 , the bracket 127 is in sealing fit with the flange at the bottom of the housing 122 to clamp and fix the measuring electrode 112 in the area surrounded by the flange. The bracket 127 fixes the measuring electrode 112 on the one hand, and on the other hand uses a tight fit to play a sealing effect, so that the electrolyte will not penetrate into the capillary 128 and block the capillary 128. In addition, the measuring electrode 112 and the liquid storage tank can be connected. 150 to prevent the gas generated by the counter electrode 114 from reaching the measurement electrode and distorting the signal.

[0038] still refer to image 3 , in this embodiment, the side wall of the bracket 127 has a plurality of grooves, and there are protrusions between adjacent grooves. Among them, the grooves can facilitate the wiring of the wires, and the wires connected to different electrodes of the gas sensor can be routed in different grooves to reduce the risk of short circuit between the wires. In addition, it is convenient for the liquid absorbing material layer to penetrate into the surrounding liquid storage tank 150. , balance the amount of electrolyte in the storage tank 150 and the middle part. The protruding part can play the role of positioning, which facilitates the installation of components such as the liquid absorbing material layer, the reference electrode 116 , and the counter electrode 114 .

[0039] The first liquid-absorbing material layer 144a, the reference electrode 116, the second liquid-absorbing material layer 144b and the counter electrode 114 are arranged in the bracket 127 in sequence, and then the plug 125 is inserted into the opening at the top of the bracket 127, and the first liquid-absorbing material is inserted into the bracket 127. The material layer 144 a , the reference electrode 116 , the second liquid-absorbing material layer 144 b and the counter electrode 114 are sandwiched and fixed between the bracket 127 and the plug 125 . The first liquid-absorbing material layer 144a and the second liquid-absorbing material layer 144b may be glass microfiber paper, and the plug 125 has an air outlet 154 .

[0040] combine figure 1 and Figure 4 , the casing cover 124 is detachably connected with the top of the casing 122 , the casing cover 124 has an opening, and the opening is sealed with the plug 125 . After being assembled and fixed, the opening of the case cover 124 communicates with the air outlet 154 of the plug 125 . The bracket 127, the casing 122 and the casing cover 124 together form a reservoir 150, which can be filled with electrolyte.

[0041]In addition, a first air-permeable and waterproof membrane 142a is disposed between the opening of the case cover 124 and the air outlet 154 , and the first air-permeable and waterproof film 142a is clamped and fixed by the case cover 124 , the plug 125 and the bracket 127 together. The first breathable and waterproof membrane 142a can prevent moisture from entering the air outlet hole 154 . The material of the first air-permeable and waterproof membrane 142a can also be made of Teflon or the like. On the one hand, the first breathable waterproof membrane 142a can prevent the electrolyte from leaking into the air outlet 154 to play a sealing role; The pressure is balanced with the environment so that it does not affect the response performance of the gas sensor.

[0042] The plug 125 is used to fix the first breathable waterproof membrane 142a on the shell cover 124, which is easy to assemble, and the first breathable waterproof membrane 142a is fixed by means of tight fitting. Compared with the sealing method on the plastic parts, the fixing method in this embodiment is beneficial to simplify the assembly process.

[0043] Figure 5 A partial enlarged view of the housing 122 of this embodiment is shown, refer to Figure 5 , there is a via hole 130 on the side wall of the housing 122, and the wire 132 is connected to each electrode (measurement electrode, reference electrode and counter electrode) in the gas sensor through the via hole. The method of forming the via hole 130 on the side wall can improve the reliability of preventing and controlling liquid leakage, and by controlling the size of the via hole 130, the sealing is facilitated; and the conventional wire 132 in the prior art detours from the housing wall and enters the gas sensor Compared with the internal method, the wiring distance of the wires 132 is smaller. Since the wires 132 are usually made of precious metals such as platinum wire, reducing the wiring distance can reduce the cost.

[0044] As a non-limiting example, the gas sensor in this embodiment is an oxygen sensor. still refer to figure 1 , the oxygen diffuses to the measuring electrode 112 through the capillary 128. At the measuring electrode 112, the oxygen captures the electrons from the counter electrode 114 and combines with the hydrogen ions, and a reduction reaction occurs to generate water molecules. The reduction reaction is as follows:

[0045] O 2 +4H + +4e - →2H 2 O (1)

[0046] On the other hand, at the counter electrode 114, water molecules are decomposed to generate hydrogen ions and electrons, and the electrolysis process is as follows:

[0047] 2H 2 O→4H + +O 2 +4e - (2)

[0048] The measuring electrode 112 may be set as a cathode, and the counter electrode 114 may be set as an anode, and the hydrogen ions generated at the counter electrode 114 may diffuse to the measuring electrode 112 through the liquid-absorbing material layer. The electrons generated at the counter electrode 114 can reach the measurement electrode 112 through an external circuit. In a specific example, a negative bias voltage of -0.6V is applied between the measurement electrode 112 and the reference electrode 116 through a potentiostatic circuit to provide a negative potential for the measurement electrode 112, that is, a negative potential is applied to the measurement electrode 112 through the reference electrode 116. The polarization potential is located in the diffusion limit region, and this potential is lower than the hydrogen evolution potential. At this potential, the measurement electrode 112 undergoes a reduction reaction as shown in formula (1), and a reduction current is formed at the same time. Since the reduction current depends on the consumption rate of oxygen, the oxygen at the measurement electrode 112 can be determined by measuring the reduction current. concentration.

[0049] In addition, the oxygen gas generated at the counter electrode 114 diffuses to the outside of the gas sensor through the gas outlet hole 154 . Since equations (1) and (2) are balanced, the reaction in the oxygen sensor is to convert the water at the counter electrode 114 to the water at the measurement electrode 112, and the oxygen at the measurement electrode 112 to the counter electrode 114. Therefore, this oxygen sensor can also be called "oxygen pump". In addition, the electrons are released at the counter electrode 114 and captured at the measurement electrode 112, and hydrogen ions migrate from the counter electrode 114 to the measurement electrode 112 through the layer of imbibition material, which in turn prevents the oxygen at the counter electrode 114 from diffusing to the measurement electrode 112. electrode 112 .

[0050] It should be noted that although an oxygen sensor is used as an example for description, those skilled in the art should understand that the structure of the gas sensor in this embodiment can also be applied to other gas sensors.

[0051] To sum up, the structure of the gas sensor in this embodiment is beneficial to miniaturization, has a long life, compact structure, good liquid leakage resistance, can adapt to wide humidity changes in the environment, can quickly establish an effective pressure balance with the environment, and prevent pressure changes from affecting the gas. Destruction of the sensor so as to affect the signal output of the gas sensor.

[0052] Although the present invention is disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications without departing from the spirit and scope of the present invention. Therefore, the present invention The scope of protection shall be subject to the scope defined by the claims of the present invention.

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Classification and recommendation of technical efficacy words

Easy assembly
Few structural parts

Gas sensor

A gas sensor and external gas technology, applied in instruments, scientific instruments, measuring devices, etc., can solve the problems of inability to miniaturize and large structure of the gas sensor, and achieve the effect of fewer structural parts, fewer process steps, and simpler assembly.

AI-Extracted Technical Summary

Problems solved by technology

Method used

Abstract

Image

Examples

Example Embodiment

PUM

Description & Claims & Application Information

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