Oxygen sensor for detecting trace oxygen in gas

Abstract

The utility model discloses an oxygen sensor for detecting trace oxygen in gas, the oxygen sensor comprises a base, a pressing ring, a sealing washer and a cathode, the pressing ring, the sealing washer and the cathode are sequentially arranged on the base from top to bottom, the pressing ring has conductivity, is used for pressing the sealing washer and the cathode below and is used as an anode at the same time, and the cathode is used as an anode. The sealing gasket is made of an insulating material, isolates the pressing ring from the cathode to enable the cathode and the anode not to be conducted, is arranged between the pressing ring and the base, and is tightly attached to the contact surface of the base and the pressing ring; the pressing ring is used for pressing the sealing gasket and the cathode which are located on the lower portion and serves as the anode at the same time, assembling is simplified, the trouble of spraying an anode diaphragm is omitted, and the size of an existing coulomb sensor is reduced by reasonably arranging the positions of the cathode and the anode.

Description

Technical Field

[0001] The present application relates to the technical field of oxygen sensors, and in particular to an oxygen sensor for detecting trace oxygen in gas. Background Art

[0002] Most oxygen sensors on the market are fuel cell oxygen sensors. The reaction is spontaneous, and the overall reaction is a combustion reaction between the battery anode and oxygen. The anode is constantly consumed and therefore needs to be replaced regularly. Unlike fuel cell sensors, coulometric oxygen sensors require an external power supply to drive the reaction, but their battery components are non-consumable and generally do not need to be replaced. They have high sensitivity, with a detection range from constant oxygen to ppt level, which is beyond the reach of other sensors. However, existing coulometric oxygen sensors, such as Panametrics' Delta-F oxygen sensor, have the problem of being large in size and difficult to integrate. In addition, since the anode and cathode of traditional coulometric oxygen sensors are both composed of current collectors and diaphragms, the sealing structure of the anode current collector needs to be the same as the cathode current collector, which also increases the difficulty of sealing.

[0003] Therefore, there is an urgent need for an oxygen sensor for detecting trace oxygen in gas. Based on the original Coulomb sensor, the anode and the clamping ring are simplified in assembly, and the sprayed anode diaphragm is omitted, so that the original high precision is maintained while the volume of the structure is reduced. Utility Model Content

[0004] To solve the above problems, the present application provides an oxygen sensor for detecting trace oxygen in gas, which improves the structure of the traditional Coulomb oxygen sensor. The clamping ring has both a clamping function and can also serve as an anode, thereby reducing its volume while maintaining extremely high accuracy.

[0005] The technical solution adopted in this application is:

[0006] The present application provides an oxygen sensor for detecting trace oxygen in gas, comprising a base, a clamping ring, a sealing gasket and a cathode. The clamping ring, the sealing gasket and the cathode are arranged on the base in sequence from top to bottom. The clamping ring is conductive and is used to clamp the sealing gasket and the cathode located below and serve as an anode at the same time. The sealing gasket is made of an insulating material, isolating the clamping ring and the cathode so that the positive and negative electrodes are not conductive. The sealing gasket is arranged between the clamping ring and the base, and the sealing gasket fits tightly with the contact surface of the base and the clamping ring.

[0007] Furthermore, the cathode is composed of a current collecting sheet and a catalytic membrane, the catalytic membrane and the current collecting sheet are fixedly connected, the current collecting sheet is used to support the catalytic membrane and provide reaction electrons for the cathode, and the catalytic membrane is used to attach the catalyst.

[0008] Furthermore, two through holes are arranged on the side wall of the sensor base, and a wire passes through each of the two through holes, wherein one wire is connected to the cathode, and the other wire is connected to the clamping ring.

[0009] Furthermore, it also includes a plurality of locking screws, which are tightened after passing through the clamping ring, the sealing gasket and the base in sequence.

[0010] Furthermore, the clamping ring is made of stainless steel, in which the nickel element is used as an anode catalyst material.

[0011] Furthermore, a hollow structure is provided on the current collecting sheet, and the hollow structure is a plurality of fan-shaped holes, and the area occupied by the fan-shaped holes is larger than 1 / 2 of the area of ​​the current collecting sheet.

[0012] Furthermore, the current collecting sheet and the catalyst membrane are connected by means of a conductive adhesive.

[0013] Furthermore, an O-ring is arranged below the current collecting sheet, a groove is opened inside the base, and the O-ring is arranged in the groove inside the base, and is used to seal between the cathode and the base when being pressed by the pressing ring.

[0014] Beneficial effects of this application:

[0015] 1. The clamping ring of the present application is used to clamp the sealing gasket and cathode located below, and also serves as an anode, which simplifies assembly and saves the trouble of spraying the anode diaphragm. By rationally arranging the positions of the anode and cathode, the volume of the existing Coulomb sensor can be reduced.

[0016] 2. The present application simplifies the anode and eliminates the traditional anode structure consisting of a current collector and an anode diaphragm. Since the current collector is not easy to seal, the sealing ring also serves as the anode to further ensure the sealing.

[0017] 3. In the design of the current collecting sheet, the present application reduces the supporting portion of the current collecting sheet, expands its hollow portion to increase the diffusion area, and improves the sensitivity of the sensor.

[0018] 4. The present application uses a plurality of locking screws to fasten the clamping ring, the base and the sealing gasket, so that the sealing gasket receives an extrusion force between the clamping ring and the base, and the sealing gasket is deformed to form an end face liquid seal with the contact surface of the clamping ring and the base. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The present invention is a front view of an oxygen sensor for detecting trace oxygen in gas.

[0020] Figure 2 This is a cross-sectional schematic diagram of an oxygen sensor for detecting trace oxygen in gas according to the present application.

[0021] Figure 3This is a top view of a flip cover of an oxygen sensor for detecting trace oxygen in gas according to the present application.

[0022] Figure 4 A top view of a base of an oxygen sensor for detecting trace oxygen in gas according to the present application.

[0023] Figure 5 A top view of a clamping ring of an oxygen sensor for detecting trace oxygen in gas according to the present application.

[0024] Figure 6 A top view of a sealing gasket of an oxygen sensor for detecting trace oxygen in gas according to the present application.

[0025] Figure 7 This is a cathode structure diagram of an oxygen sensor for detecting trace oxygen in gas according to the present application.

[0026] Figure 8 This is a top view of a current collecting piece of an oxygen sensor for detecting trace oxygen in gas according to the present application.

[0027] Fig. 9 This is a response curve diagram of an oxygen sensor for detecting trace oxygen in gas under different oxygen concentrations (0-1000ppm) of the present application.

[0028] In the figure, 1 is a flip cover, 2 is a base, 21 is a first through hole, 22 is a second through hole, 3 is a clamping ring, 4 is a sealing gasket, 5 is a locking screw, 6 is a cathode, 7 is an O-ring, 8 is a current collector, 9 is a catalytic membrane, 10 is a gas inlet, 11 is a gas outlet, and 12 is an electrolyte chamber. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solution and advantages of the present application clearer, the technical solution of the present application will be clearly and completely described below in conjunction with the accompanying drawings and a preferred implementation method.

[0030] This embodiment provides an oxygen sensor for detecting trace oxygen in gas, which is further improved based on the structure of Panametrics' Delta-F oxygen sensor. Figure 1-Figure 4 The oxygen sensor includes a base 2 and a flip cover 1. The base 2 is a hollow cylindrical structure with a bottom but no cover. The flip cover 1 covers the base 2. A first through hole 21 is provided at a position of the side wall of the base 2 near the clamping ring 3 (anode) for passing a wire connected to the clamping ring 3 (anode). A second through hole 22 is provided at a position of the side wall of the base 2 near the cathode 6 for passing a wire connected to the cathode 6. The other ends of the two wires are connected to the circuit. Voltage is applied to the anode and cathode through the two wires, and the current of the anode and cathode is also detected.

[0031] refer to Figure 2The oxygen sensor also includes a clamping ring 3, a sealing gasket 4, a locking screw 5, a cathode 6 and an O-ring 7. The clamping ring 3, the sealing gasket 4 and the cathode 6 are arranged on the base 2 from top to bottom. The clamping ring 3 is conductive. The clamping ring 3 is used to clamp the sealing gasket 4 and the cathode 6 located below and also acts as an anode. The sealing gasket 4 is made of insulating material to isolate the clamping ring 3 and the cathode 6 so that the anode and cathode are not conductive. Specifically, the clamping ring 3 in this embodiment is made of stainless steel, and the nickel element therein is used as an anode catalyst material to form a side reaction with the cathode 6. Reference Figure 5 There is also a through hole in the middle of the clamping ring 3 for passing the electrolyte. Figure 6 A through hole with a relatively large diameter is provided in the middle of the sealing gasket 4 , and the space between the through hole and the cathode 6 forms an electrolyte chamber 12 , in which potassium hydroxide electrolyte is stored.

[0032] Continue to refer Figure 2 The sealing gasket 4 is arranged between the clamping ring 3 and the base 2. The sealing gasket 4 is in close contact with the contact surface of the base 2 and the clamping ring 3 to prevent the electrolyte in the electrolyte chamber 12 from leaking out. An O-ring 7 is arranged under the cathode 6 for sealing. The number of locking screws 5 is 6 (only 3 are shown in the figure). Figure 4-Figure 6 As shown, six screw holes are preset on the outer periphery of the clamping ring 3, the sealing gasket 4 and the base 2 respectively. The locking screw 5 passes through the preset screw holes on the clamping ring 3, the sealing gasket 4 and the base 2 in turn, and is tightened by threads, so that the sealing gasket 4 receives an extrusion force between the clamping ring 3 and the base 2, and the sealing gasket 4 is deformed, forming an end face liquid seal with the contact surface of the clamping ring 3 and the base 2.

[0033] Continue to refer Figure 2 The left and right sides of the oxygen sensor base 2 are respectively penetrated with a gas outlet 11 and a gas inlet 10. In actual use, a 1 / 16'NPT threaded ferrule will be added to the gas inlet 10 and the gas outlet 11 according to the thread. After the gas to be tested enters the oxygen sensor from the gas inlet 10, the oxygen sensor completes the detection, and the detected gas sample flows out from the gas outlet 11. The through hole in the middle of the top of the flip cover 1 is located at F of the oxygen sensor, as shown in FIG. Figure 3 As shown, the through hole on the top of the flip cover 1 is used to discharge oxygen generated by the side reaction.

[0034] refer to Figure 7 and Figure 8 The cathode 6 is composed of a current collecting sheet 8 and a catalytic membrane 9. The catalytic membrane 9 and the current collecting sheet 8 are fixedly connected. The current collecting sheet 8 is used to support the catalytic membrane 9 and provide reaction electrons for the cathode 6. The catalytic membrane 9 is used to attach the catalyst.

[0035] The hollowed-out part on the collector of the original Panametrics Delta-F oxygen sensor is a uniformly distributed small hole, and the hot pressing bonding is not strong, and it is easy to fall off and make the sensor ineffective. In order to increase the sensitivity of the sensor, this embodiment increases the diffusion area of ​​the holes on the collector 8 of the cathode 6, so that oxygen is more easily diffused. For this purpose, the following design is carried out: Figure 8 , the current collector 8 is provided with a hollow structure, the function of the hollow part is to allow oxygen to diffuse to the cathode 6, the non-hollow metal part is conductive and serves as a fixed support for the cathode 6, the support part of the current collector 8 is reduced, the hollow structure is a plurality of fan-shaped holes, the area occupied by the fan-shaped holes is greater than 1 / 2 of the area of ​​the current collector 8, specifically, the hollow structure is four quarter-circle holes, the four holes are evenly distributed, the hollow part is enlarged to increase the diffusion area, oxygen is easier to diffuse, and the sensor sensitivity will also increase. And the four holes form a cross structure, which can play a role in bonding and fixing, and there will be no hollowing. The original reference prototype Panametrics' Delta-F oxygen sensor has a mesh structure in the middle of the current collector, which has good air permeability, but cannot be fixed with glue. Therefore, when a large air pressure is introduced, the middle may be hollowed out by the air pressure, resulting in the inability of the current collector and the catalytic membrane of the Delta-F oxygen sensor to fit together, and the conductivity fails.

[0036] In this embodiment, the current collecting sheet 8 and the catalytic membrane 9 are combined in a bonding manner, which has a stronger bonding ability. The current collecting sheet 8 and the catalytic membrane 9 are connected by a conductive adhesive, and the conductive adhesive is directly applied, so that the current collecting sheet 8 and the catalytic membrane 9 have a stronger bonding force when they are conductive. Figure 2 An O-ring 7 is arranged below the current collecting sheet 8, and a groove is also provided in the middle of the base 2. The O-ring 7 is arranged in the groove and is used to seal between the cathode 6 and the base 2 when being pressed by the pressing ring 3.

[0037] Specifically, the catalyst of this embodiment adopts a platinum-based catalyst, and other platinum and its alloy catalysts may also be adopted. The catalyst ink is prepared and sprayed to be uniformly loaded on the catalyst membrane 9.

[0038] The oxygen sensor body of this embodiment is made of transparent plastic material, which is lightweight, and the inlet and outlet are made of stainless steel, which is high in strength and impact-resistant, and is suitable for the requirements of miniaturized oxygen sensors. The gas outlet is in the form of a 1 / 16'NPT ferrule interface, which is easy to install and completely sealed to ensure that the gas will not leak during the test.

[0039] Preferably, when manufacturing and installing the oxygen sensor provided in this embodiment, glue, silicone gasket and silicone mechanical compression can be used to avoid structural failure caused by high temperature and the temperature resistance can be increased to above 80°C.

[0040] The workflow of this embodiment is as follows:

[0041] The driving voltage is applied to the cathode and cathode through two wires passing through the first through hole 21 and the second through hole 22. The gas to be measured enters the oxygen sensor from the gas inlet 10, and the oxygen in the gas to be measured diffuses through the current collector 8 to the catalytic membrane 9 of the cathode 6. The oxygen is reduced to hydroxide ions by the platinum-based catalyst and the driving voltage, and the hydroxide ions enter the electrolyte chamber 12. The hydroxide ions are transferred to the clamping ring 3 (anode) through the electrolyte in the electrolyte chamber 12, and the hydroxide ions are reoxidized to oxygen through the clamping ring 3 (anode). In this process, the cathode 6 and the clamping ring 3 (anode) react with each other as side reactions, and the electrode assembly components are not consumed. Finally, the oxygen is discharged from the through hole of the flip cover 1 located at F, where the cathode reaction is The anode reaction is At the cathode, oxygen and water react with electric charge to generate hydroxide ions, and at the anode, hydroxide ions react to generate oxygen and water with electric charge.

[0042] In some other embodiments, Figure 1 The first through hole 21 and the second through hole 22 are used to connect to the signal amplifier processing circuit. In the above reaction, the oxygen in the gas to be measured is completely reduced when it enters the catalytic membrane 9 that reaches the cathode 6. When the oxygen reaction rate of the oxygen in the gas to be measured diffuses to the cathode 6 is consistent with the reverse reaction rate of the hydroxyl radicals migrating to the anode, the current value of the electrolysis current is proportional to the oxygen content diffused to the cathode 6. Therefore, the current generated is proportional to the oxygen content in the gas to be measured. After the signal amplifier processing circuit detects this current signal, the current signal is connected to the display instrument to read a more accurate oxygen content.

[0043] This embodiment improves the structure of the traditional coulometric oxygen sensor. The clamping ring 3 has both a clamping function and can also serve as an anode, so that the oxygen sensor can work normally and maintain extremely high accuracy while reducing the volume. This embodiment simplifies the anode structure, combines the anode and the sealing structure into one, and reduces the volume of the original Panametrics Delta-F oxygen sensor from about 646 cm³ to about 17 cm³, greatly reducing the volume.

[0044] refer to Fig. 9 The horizontal axis is the standard concentration (ppm), and the vertical axis is the current (mA). The linear fitting degree of the response curve of this application under different oxygen concentrations (0-1000ppm) reaches above 0.999. It can be considered that the current is highly proportional to the oxygen concentration, and the sensitivity of this application is 0.00122mA / ppm. The volume is reduced while maintaining extremely high accuracy.

[0045] The above is only a preferred embodiment of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications are also within the scope of protection of the present application.

Claims

1. An oxygen sensor for detecting trace oxygen in gas, comprising a base (2), a clamping ring (3), a sealing gasket (4) and a cathode (6), characterized in that: The clamping ring (3), the sealing gasket (4) and the cathode (6) are arranged on the base (2) in sequence from top to bottom. The clamping ring (3) is conductive and is used to clamp the sealing gasket (4) and the cathode located below and simultaneously serves as an anode. The sealing gasket (4) is made of an insulating material and isolates the clamping ring (3) and the cathode (6) so that the positive and negative electrodes are not conductive. The sealing gasket (4) is arranged between the clamping ring (3) and the base (2). The contact surfaces of the sealing gasket (4) and the base (2) and the clamping ring (3) are tightly fitted.

2. The oxygen sensor for detecting trace oxygen in gas according to claim 1, characterized in that: The cathode (6) is composed of a current collecting sheet (8) and a catalytic membrane (9). The catalytic membrane (9) and the current collecting sheet (8) are fixedly connected. The current collecting sheet (8) is used to support the catalytic membrane (9) and provide reaction electrons for the cathode (6). The catalytic membrane (9) is used to attach the catalyst.

3. The oxygen sensor for detecting trace oxygen in gas according to claim 1, characterized in that: Two through holes are provided on the side wall of the sensor base (2), and a wire passes through each of the two through holes, one of the wires is connected to the cathode (6), and the other wire is connected to the clamping ring (3).

4. The oxygen sensor for detecting trace oxygen in gas according to claim 1, characterized in that: It also includes a plurality of locking screws (5), which are tightened after passing through the clamping ring (3), the sealing gasket (4) and the base (2) in sequence.

5. The oxygen sensor for detecting trace oxygen in gas according to claim 1, characterized in that: The clamping ring (3) is made of stainless steel, in which the nickel element is used as an anode catalyst material.

6. The oxygen sensor for detecting trace oxygen in gas according to claim 2, characterized in that: The current collecting sheet (8) is provided with a hollow structure, which is a plurality of fan-shaped holes, and the area occupied by the fan-shaped holes is greater than 1 / 2 of the area of ​​the current collecting sheet (8).

7. The oxygen sensor for detecting trace oxygen in gas according to claim 2, characterized in that: The current collecting sheet (8) and the catalytic membrane (9) are connected via conductive adhesive.

8. The oxygen sensor for detecting trace oxygen in gas according to claim 2, characterized in that: An O-ring (7) is arranged below the current collecting sheet (8), a groove is provided inside the base (2), and the O-ring (7) is arranged in the groove inside the base (2) and is used to seal between the cathode (6) and the base (2) when being pressed by the pressing ring (3).

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