Combustible gas alarm

Abstract

The invention discloses a combustible gas alarm, and belongs to the field of alarms, the combustible gas alarm comprises an alarm main body and a detection head fixedly mounted with the alarm main body, an exhaust cavity is formed in the alarm main body, a standing cavity is also formed in the alarm main body, and external air can enter the standing cavity through the detection head. A semiconductor sensor is fixedly installed on the inner wall of the groove. Through the arrangement of the standing cavity, the electric telescopic rod, the first one-way valve, the semiconductor sensor and the piston disc, the electric telescopic rod works to drive the piston disc to move up and down, and gas stands in the standing cavity, so that the influence of air flow entering from the outside of the alarm main body is reduced; therefore, the semiconductor sensor has enough time to detect the content of the methane gas in the standing cavity, and the situation that the gas which is being detected by the semiconductor sensor is not completely detected and the part which is not completely detected is blown away by new gas is reduced, so that the detection accuracy of the semiconductor sensor is improved.

Description

Technical Field

[0001] The present invention relates to the field of alarms, and more specifically, to a combustible gas alarm. Background Art

[0002] An alarm is a device used to emit alarm signals and is usually used in security and monitoring systems. It can be used to detect various types of hazards, such as intrusion, fire, gas leakage, etc.

[0003] In order to save energy and reduce emissions, kitchens in cities now start to use natural gas instead of coal gas. Similar to coal gas leakage, when the natural gas leakage reaches a certain amount, it may be directly ignited when the gas stove is lit, resulting in kitchen accidents and affecting the safety of residents' lives. In order to be able to promptly know the natural gas leakage and reduce the occurrence of such phenomena, natural gas alarms have been introduced on the market.

[0004] Although existing combustible gas alarms play an important role in detecting and preventing combustible gas leakage, there are still some drawbacks and limitations, especially in terms of sensitivity. When natural gas leaks inside the kitchen, in the initial stage of leakage, the amount of natural gas leakage is small, and methane gas molecules are mixed in the air and diluted by the air. At this time, if an alarm with low sensitivity is used for detection, it will take a long time to detect this part of the gas. If there is a continuous flow of gas entering the alarm at this time, and the alarm has not completely detected the internal gas, this part of the gas that has not been completely detected is blown out by the new air, resulting in incomplete detection of the gas by the alarm and low sensitivity of the alarm. It cannot timely and accurately detect whether natural gas leaks, and the use effect is not good. Summary of the Invention

[0005] Aiming at the problems existing in the prior art, the purpose of the present invention is to provide a combustible gas alarm.

[0006] To solve the above problems, the present invention adopts the following technical solutions.

[0007] A combustible gas alarm, comprising an alarm main body and a detection head fixedly installed on the alarm main body. An exhaust cavity is formed inside the alarm main body, and a static cavity is also formed inside the alarm main body. The static cavity is communicated with the exhaust cavity and is located above the exhaust cavity. An electric telescopic rod is fixedly installed on the inner wall of the top of the exhaust cavity. The telescopic end of the electric telescopic rod passes through the exhaust cavity and is fixedly connected to a piston disc in the static cavity. An intake vertical cavity is formed in the detection head, and a piston disc is slidably and sealingly arranged in the intake vertical cavity. External air can enter the static cavity through the detection head. A groove is formed in the inner wall of the static cavity, and a semiconductor sensor is fixedly installed on the inner wall of the groove. An exhaust pipe is fixedly installed on the inner wall of the exhaust cavity, and the exhaust pipe can discharge the gas in the exhaust cavity to the outside of the alarm main body.

[0008] Further, a plurality of groups of first one-way valves are circumferentially and equidistantly arranged on the piston disc. A plurality of groups of intake horizontal cavities are circumferentially and equidistantly arranged inside the detection head. The first one-way valves are used in cooperation with the intake vertical cavity.

[0009] Further, a ring plate is fixedly installed in the static cavity. An inner air cavity and an outer air cavity are arranged in the static cavity. The ring plate divides the static cavity into two parts, namely the inner air cavity and the outer air cavity from the inside to the outside. The volume of the outer air cavity is smaller than that of the inner air cavity, and the semiconductor sensor is located in the outer air cavity.

[0010] Further, a sliding groove is formed in the ring plate, and a second one-way valve is slidably and sealingly arranged in the sliding groove. The inner air cavity and the outer air cavity are communicated through the second one-way valve. A third one-way valve is fixedly arranged on the inner wall of the exhaust cavity. The exhaust cavity and the outer air cavity are communicated through the third one-way valve.

[0011] Further, a second spring is fixedly installed in the outer air cavity. The top end of the second spring is fixedly connected to a push ring. The push ring is slidably and sealingly arranged in the outer air cavity. A first spring is fixedly arranged on the inner wall of the sliding groove. The first spring is fixedly connected to the second one-way valve.

[0012] Further, an inclined platform is fixedly connected to the top of the detection head. A filter screen is fixedly installed on the outer surface of the inclined platform. The filter screen is arranged in the lowest horizontal circle of the inclined platform, and the filter screen is annular.

[0013] Further, a knocking component is arranged on the outer surface of the telescopic end of the electric telescopic rod. The knocking component is used in cooperation with the filter screen. The knocking component includes multiple groups of triangular plates fixedly installed on the inner surface of the filter screen. Multiple long rods are circumferentially and equidistantly arranged on the outer surface of the output end of the electric telescopic rod. A contraction groove is formed inside each long rod, and a vibration spring is arranged in the contraction groove. One end of the vibration spring is fixedly connected to the inner wall of the contraction groove, and the other end of the vibration spring is fixedly connected to a sliding rod. The sliding rod is slidably arranged in the contraction groove, and one end of the sliding rod located outside the contraction groove is fixedly connected to a contact head. The contact head is used in cooperation with the triangular plate.

[0014] Further, the gas in the intake horizontal cavity can enter the intake vertical cavity through the first one-way valve. The gas in the inner air cavity can enter the outer air cavity through the second one-way valve. The gas in the outer air cavity can enter the exhaust cavity through the third one-way valve.

[0015] Further, the second one-way valve is L-shaped, and the pipe diameter of the second one-way valve is larger than that of the third one-way valve.

[0016] Further, the detection head is fixedly connected to the alarm main body through a thread, and the contact head contacts the inner surface of the filter screen.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0018] (1) By arranging the static chamber, the electric telescopic rod, the first one-way valve, the semiconductor sensor and the piston disc, the present invention drives the piston disc to move up and down through the operation of the electric telescopic rod. The gas is static in the static chamber, reducing the influence of the air flow entering from outside the alarm main body, so that the semiconductor sensor will have enough time to detect the content of methane gas inside the static chamber, reducing the situation that the gas being detected by the semiconductor sensor has not been fully detected and new gas blows away the undetected part, so as to improve the detection accuracy of the semiconductor sensor.

[0019] (2) By arranging the inner air cavity, the outer air cavity, the second one-way valve, the third one-way valve and the first spring, the semiconductor sensor can detect the gas flowing through the semiconductor sensor more comprehensively, making the detected value of the methane content more accurate, reducing the situation that due to the relatively long reaction time of the semiconductor sensor itself, some methane-containing gas does not flow through the semiconductor sensor and cannot be detected, and further improving the detection accuracy of the semiconductor sensor.

[0020] (3) Through the push ring and the second spring provided in the present invention, the push ring can push all the gas that has been fully detected in the external air chamber into the exhaust chamber, thereby preventing the detected gas from interfering with the gas that has just entered the external air chamber and causing misjudgment by the semiconductor sensor. This further improves the measurement accuracy of the alarm main body. The second spring enables the gas in the external air chamber to be detected twice to ensure the detection accuracy of the alarm main body and further reduce the occurrence of misjudgment of the alarm.

[0021] (4) Through the filter screen provided in the present invention, due to cooking in the kitchen, there will be oil stains in the air, which will affect the detection accuracy of the semiconductor sensor if they contaminate the semiconductor sensor. Therefore, when the air enters the internal air chamber, the oil stains inside will be filtered and left by the filter screen, thereby minimizing the impact of oil stains on the detection accuracy of the semiconductor sensor and further improving the detection accuracy of the natural gas content by the alarm main body. Description of the Drawings

[0022] Figure 1 is a schematic structural diagram of the present invention;

[0023] Figure 2 is a front cross-sectional view of the internal structure of the alarm main body of the present invention;

[0024] Figure 3 is a side cross-sectional view of the internal structure of the alarm main body of the present invention;

[0025] Figure 4 is a disassembled schematic diagram of the detection head and the alarm main body of the present invention;

[0026] Figure 5 is the Figure 3 enlarged view of the structure at A in the present invention;

[0027] Figure 6 is a combined schematic diagram of the detection head and the filter screen of the present invention;

[0028] Figure 7 is a combined schematic diagram of the filter screen and the knocking assembly of the present invention;

[0029] Figure 8 is the Figure 7 enlarged view of the structure at B in the present invention.

[0030] Explanation of the reference numerals in the drawings:

[0031] 1. Alarm main body; 2. Detection head; 3. Exhaust cavity; 4. Static chamber; 5. Electric telescopic rod; 6. Piston disc; 7. First one-way valve; 8. Intake vertical cavity; 9. Groove; 10. Semiconductor sensor; 11. Exhaust pipe; 12. Intake horizontal cavity; 13. Ring plate; 14. Inner air cavity; 15. Outer air cavity; 16. Second one-way valve; 17. Slide groove; 18. Third one-way valve; 19. First spring; 20. Second spring; 21. Push ring; 22. Filter screen; 23. Long rod; 24. Slide rod; 25. Contact; 26. Vibration spring; 27. Triangular plate; 28. Inclined platform; 29. Shrinkage groove; 30. Knocking component. Detailed implementation manner

[0032] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention; obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0033] Please refer to Figures 1 to 8 , a combustible gas alarm, including an alarm main body 1 and a detection head 2 fixedly installed on the alarm main body 1. An exhaust cavity 3 is opened inside the alarm main body 1. A static chamber 4 is also opened inside the alarm main body 1. The static chamber 4 is communicated with the exhaust cavity 3, and the static chamber 4 is located above the exhaust cavity 3. An electric telescopic rod 5 is fixedly installed on the inner wall of the top of the exhaust cavity 3. The telescopic end of the electric telescopic rod 5 passes through the exhaust cavity 3 and is fixedly connected to a piston disc 6 in the static chamber 4. An intake vertical cavity 8 is opened in the detection head 2. A piston disc 6 is slidably and sealingly arranged in the intake vertical cavity 8. External air can enter the static chamber 4 through the detection head 2. A groove 9 is opened on the inner wall of the static chamber 4. A semiconductor sensor 10 is fixedly installed on the inner wall of the groove 9. An exhaust pipe 11 is fixedly installed on the inner wall of the exhaust cavity 3. The exhaust pipe 11 can discharge the gas in the exhaust cavity 3 to the outside of the alarm main body 1.

[0034] When using the alarm main body 1, first install the alarm main body 1 beside the kitchen gas pipeline to detect the gas there, so as to detect the leaked natural gas more quickly. After installing the alarm main body 1, the gas beside the kitchen gas pipeline will enter the alarm main body 1. As the electric telescopic rod 5 contracts and drives the piston disc 6 to move upward, the detection head 2 will open at this time, and the gas will enter the interior of the alarm main body 1 through the detection head 2. At this time, the electric telescopic rod 5 drives the piston disc 6 to move downward, and the detection head 2 closes at this time, and the external gas will not enter the alarm main body 1 through the detection head 2. At this time, the gas inside the alarm main body 1 will be in the static chamber 4. At this time, the detection head 2 will detect the methane content in the static chamber 4. Since the electric telescopic rod 5 needs to wait for a period of time to move downward to allow new gas to enter the interior of the alarm main body 1 after moving upward, the semiconductor sensor 10 will have enough time to detect the methane gas content in the static chamber 4, reducing the situation where the gas being detected by the semiconductor sensor 10 has not been fully detected and new gas blows away the undetected part, so as to improve the detection accuracy of the semiconductor sensor 10;

[0035] The first one-way valve 7 is L-shaped, one end is used to communicate with the outside of the detection head 2, and the other end is used to communicate with the static chamber 4. When the electric telescopic rod 5 drives the piston disc 6 to move upward, the end used to communicate with the outside of the detection head 2 is blocked, and the gas will stay in the static chamber 4;

[0036] It should be particularly noted here that: the semiconductor sensor 10 usually uses materials such as tin oxide SnO2. When methane gas contacts the surface of the sensor, methane molecules will react with the semiconductor material, resulting in a change in the conductivity of the material. The semiconductor sensor 10 detects the concentration of methane by monitoring the change in conductivity. There is a built-in alarm mechanism on the alarm main body 1, and the alarm mechanism is electrically connected to the semiconductor sensor 10 inside the alarm main body 1. The alarm mechanism is a horn that can make a sound and a light strip that works simultaneously with the horn. After the semiconductor sensor 10 detects a certain concentration of methane inside the alarm main body 1, the horn and the light strip work simultaneously to play an alarm role. Here, the horn and the light strip are connected in series with each other and used in cooperation with the semiconductor sensor 10, which is a mature existing technology and the circuit structure is simple, so it will not be elaborated here.

[0037] As Figures 2 to 6 shown, multiple groups of first one-way valves 7 are arranged equidistantly on the circumference of the piston disc 6, and multiple groups of intake transverse cavities 12 are arranged equidistantly on the inner and outer circumferences of the detection head 2. The first one-way valve 7 is used in cooperation with the intake vertical cavity 8.

[0038] A fixing mounting ring plate 13 is fixedly installed in the static chamber 4. An inner air chamber 14 and an outer air chamber 15 are arranged in the static chamber 4. The ring plate 13 divides the static chamber 4 into two parts, namely the inner air chamber 14 and the outer air chamber 15 from the inside to the outside. The volume of the outer air chamber 15 is smaller than that of the inner air chamber 14. The semiconductor sensor 10 is located in the outer air chamber 15.

[0039] A chute 17 is formed in the ring plate 13. A second one-way valve 16 is slidably and sealingly arranged in the chute 17. The inner air chamber 14 and the outer air chamber 15 are communicated through the second one-way valve 16. A third one-way valve 18 is fixedly arranged on the inner wall of the exhaust chamber 3. The exhaust chamber 3 and the outer air chamber 15 are communicated through the third one-way valve 18. A first spring 19 is fixedly arranged on the inner wall of the chute 17. The first spring 19 is fixedly connected with the second one-way valve 16.

[0040] The second one-way valve 16 is L-shaped, and the pipe diameter of the second one-way valve 16 is larger than that of the third one-way valve 18.

[0041] When the electric telescopic rod 5 pushes the piston disc 6 to move upward, the piston disc 6 will push the gas in the inner air chamber 14 into the outer air chamber 15. When the gas in the inner air chamber 14 enters the outer air chamber 15 through the second one-way valve 16, the gas in the inner air chamber 14 will push the second one-way valve 16 to move leftward as shown in Figure 5 . At this time, the first spring 19 contracts, and the second one-way valve 16 will block the third one-way valve 18. At this time, the gas entering the outer air chamber 15 from the inner air chamber 14 cannot enter the exhaust chamber 3 through the third one-way valve 18 and be discharged. When the gas entering the outer air chamber 15 from the inner air chamber 14 passes through the position of the semiconductor sensor 10 and fills the outer air chamber 15, the semiconductor sensor 10 will detect the methane content in this gas. After the semiconductor sensor 10 finishes detecting, at this time, the electric telescopic rod 5 drives the piston disc 6 to move downward. Since the air pressure in the inner air chamber 14 is less than the air pressure in the outer air chamber 15, at this time, the first spring 19 will rebound and push the second one-way valve 16 to move rightward as shown in Figure 5 . Thus, the third one-way valve 18 is opened. At this time, the gas that has been detected by the semiconductor sensor 10 in the outer air chamber 15 will enter the exhaust chamber 3 through the third one-way valve 18 and be discharged to the outside of the alarm main body 1 through the exhaust pipe 11;

[0042] Since the volume of the outer air chamber 15 is smaller than that of the inner air chamber 14, the semiconductor sensor 10 can more comprehensively detect the gas flowing through the semiconductor sensor 10, making the detected value of the methane content more accurate, reducing the situation that due to the relatively long reaction time of the semiconductor sensor 10 itself, some methane-containing gas does not flow through the semiconductor sensor 10 and cannot be detected, and further improving the detection accuracy of the semiconductor sensor 10;

[0043] Gases with relatively large relative molecular masses in the air will be located at the bottom inside the alarm main body 1. Since nitrogen, oxygen, argon, and carbon dioxide in the air together account for more than 99.99%, and other gases including methane account for less than 0.01%. At the same time, the relative molecular masses of nitrogen, oxygen, argon, and carbon dioxide are all much larger than that of methane. In the same container, methane will be at the top layer after standing still. And when the proportion of methane in the air reaches 5%-15%, there will be a risk of explosion. Therefore, the semiconductor sensor 10 in the alarm main body 1 only needs to detect whether the methane content exceeds 5%. Since most of the gases detected by the semiconductor sensor 10 are located in the upper layer of the air, the detected proportion of methane in the gas exceeds 0.01%, which is higher than detecting the content of methane in the air outside the alarm main body 1, and the safety is higher.

[0044] As Figures 2 to 6 shown, a second spring 20 is fixedly installed in the outer air cavity 15. The top end of the second spring 20 is fixedly connected to a push ring 21, and the push ring 21 is slidably and sealingly arranged in the outer air cavity 15.

[0045] The gas in the intake horizontal cavity 12 can enter the intake vertical cavity 8 through the first one-way valve 7. The gas in the inner air cavity 14 can enter the outer air cavity 15 through the second one-way valve 16. The gas in the outer air cavity 15 can enter the exhaust cavity 3 through the third one-way valve 18.

[0046] The current alarm main body 1 also adopts the method of allowing air to flow into the inside of the alarm main body 1 and detecting the methane gas content through the semiconductor sensor 10 inside it. In this detection method, it may occur that the gas just detected cannot be completely discharged and is mixed with the continuously incoming gas. At this time, if the continuously incoming air has a small content of methane gas inside, the proportion of methane gas will become smaller after mixing. If the gas just detected is affected by airflows from different directions outside, resulting in incomplete discharge of the methane gas in the upper layer inside it, and at this time, the air just entering the inside of the alarm main body 1 is mixed in, then the proportion of methane gas inside the alarm main body 1 will increase, leading to the situation where the semiconductor sensor 10 detects an increase in methane content, and there will be a situation of false alarm of the alarm. Therefore, when the electric telescopic rod 5 drives the piston disk 6 to move downward, since at this time the second one-way valve 16 moves to the right as shown in Figure 5 and at this time the third one-way valve 18 has been opened, the compressed second spring 20 rebounds, pushing the push ring 21 upward, and pushing all the completely detected gas in the outer air cavity 15 out into the exhaust cavity 3, so as to avoid the mutual influence between the detected gas and the gas just entering the outer air cavity 15, resulting in misjudgment by the semiconductor sensor 10, and further improving the measurement accuracy of the alarm main body 1;

[0047] When the electric telescopic rod 5 contracts and drives the piston disc 6 to move upward, when the gas entering the outer air chamber 15 from the inner air chamber 14 fills the inner part of the outer air chamber 15, since the third one-way valve 18 is closed at this time, under the action of the second one-way valve 16, the second spring 20 contracts at this time, driving the push ring 21 to move downward to the bottom end of the outer air chamber 15. During this process, the gas entering the outer air chamber 15 will pass through the semiconductor sensor 10 and move downward to the bottom of the outer air chamber 15, and gradually fill the outer air chamber 15. Each part of the gas entering the outer air chamber 15 can pass through the semiconductor sensor 10 and be detected by the semiconductor sensor 10. When the electric telescopic rod 5 moves downward and drives the piston disc 6 to move downward, the third one-way valve 18 opens. At this time, the gas in the outer air chamber 15 will, under the action of the second spring 20 and the push ring 21, pass through the third one-way valve 18 from bottom to top and leave the outer air chamber 15. During this process, the gas in the outer air chamber 15 passes through the position of the semiconductor sensor 10 again and is detected by the semiconductor sensor 10 again. Through two detections, the accuracy of the detection by the alarm main body 1 is ensured, and the situation of false judgment of the alarm is further reduced;

[0048] It should be particularly noted here that: since the volume of the outer air chamber 15 is fixed, the volume of the gas entering the outer air chamber 15 from the inner air chamber 14 each time is also fixed, and the volume of the methane gas and other gases in the air entering it is also fixed. The situation of excessive methane gas entering or the volume of the gas in the air other than methane being unfixed will also be greatly reduced, so as to reduce the situation of false judgment of the alarm caused by different contents of different gases in the air entering the outer air chamber 15 due to unstable air flow.

[0049] As Figure 2 and Figure 4 shown, the detection head 2 and the alarm main body 1 are fixedly connected by threads, and the contact head 25 contacts the inner surface of the filter screen 22.

[0050] The top of the detection head 2 is fixedly connected with an inclined platform 28, and the filter screen 22 is fixedly installed on the outer surface of the inclined platform 28. The filter screen 22 is arranged in the lowest circle of the horizontal position of the inclined platform 28, and the filter screen 22 is annular.

[0051] Since the alarm is used in the kitchen, due to the influence of cooking in the kitchen, there will be oil stains in the air. At this time, if the oil stains adhere to the semiconductor sensor 10, it will affect the detection accuracy of the semiconductor sensor 10. Therefore, when the air enters the inner air chamber 14, the oil stains inside it will be filtered by the filter screen 22 and left behind, so as to minimize the influence of the oil stains on the detection accuracy of the semiconductor sensor 10 and further improve the detection accuracy of the alarm main body 1 for the natural gas content;

[0052] When the detector head 2 and the alarm main body 1 are separated by the threads thereon, the oil stains filtered by the filter screen 22 will remain on the filter screen 22 or fall on the inclined platform 28 of the detector head 2 due to gravity. Due to the design of the inclined platform 28, most of the oil stains are at the lowest point of the inclined platform 28. After the detector head 2 is disassembled, the filter screen 22 can be directly cleaned, and at the same time, a small amount of oil stains in the vertical intake cavity 8 can be cleaned, so as to ensure the normal use of the semiconductor sensor 10 and extend the service life of the alarm main body 1;

[0053] It should be specifically noted here that: according to actual use needs, sponge plates or desiccants can be adhered to the inner and outer surfaces of the filter screen 22 to reduce the influence of air humidity and oil stains. The first one-way valve 7 here can also be a simple L-shaped pipe. The first one-way valve 7 is used here to reduce the situation that a large amount of air enters the inner air cavity 14 through the first one-way valve 7 from the gap generated by the friction of the arc surface of the piston disc 6 due to the repeated up and down movement of the piston disc 6.

[0054] Such as Figure 2 、 Figure 3 、 Figure 4 、 Figure 7 and Figure 8 As shown in

[0055] When the detector head 2 and the alarm main body 1 are disassembled and separated by the threads thereon, since the detector head 2 rotates relative to the alarm main body 1, at this time, the knocking component 30 fixed on the electric telescopic rod 5 also rotates relative to the filter screen 22. Since the contact head 25 contacts the filter screen 22, when the knocking component 30 rotates, the contact head 25 will slide along the inclined surface of the triangular plate 27. At this time, the vibration spring 26 contracts, and the sliding rod 24 moves into the contraction groove 29. When the contact head 25 moves to the edge of the inclined surface of the triangular plate 27 to the surface of the filter screen 22, the vibration spring 26 rebounds, causing the contact head 25 to knock on the surface of the filter screen 22, vibrating the filter screen 22, knocking off the oil stains on the surface of the filter screen 22, and making the oil stains fall on the inclined platform 28, thus facilitating the cleaning of the oil stains on the surface of the filter screen 22.

[0056] Usage method: When using the alarm main body 1, first install the alarm main body 1 beside the kitchen gas pipeline to detect the gas at this location so as to detect the leaked natural gas more quickly. After installing the alarm main body 1, the gas beside the kitchen gas pipeline will enter the alarm main body 1. As the electric telescopic rod 5 contracts and drives the piston disc 6 to move upward, at this time the detection head 2 will open, and the gas will enter the interior of the alarm main body 1 through the detection head 2. At this time, the electric telescopic rod 5 drives the piston disc 6 to move downward, and at this time the detection head 2 closes, and the external gas will not enter the alarm main body 1 through the detection head 2. At this time, the gas inside the alarm main body 1 will be inside the static chamber 4. At this time, the detection head 2 will detect the methane content inside the static chamber 4. Since the electric telescopic rod 5 needs to wait for a period of time after moving upward before moving downward to allow new gas to enter the interior of the alarm main body 1, at this time the semiconductor sensor 10 will have enough time to detect the methane gas content inside the static chamber 4, reducing the situation where the gas being detected by the semiconductor sensor 10 has not been fully detected and new gas blows away the undetected part, so as to improve the detection accuracy of the semiconductor sensor 10.

[0057] The above is only a preferred specific implementation manner of the present invention; however, the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution of the present invention and its improved concept, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.

Claims

1. A combustible gas alarm, comprising an alarm main body (1) and a detection head (2) fixedly installed on the alarm main body (1), characterized in that: An exhaust cavity (3) is formed inside the alarm main body (1). A static cavity (4) is also formed inside the alarm main body (1). The static cavity (4) communicates with the exhaust cavity (3), and the static cavity (4) is located above the exhaust cavity (3). An electric telescopic rod (5) is fixedly installed on the inner wall of the top of the exhaust cavity (3). The telescopic end of the electric telescopic rod (5) passes through the exhaust cavity (3) and is fixedly connected to a piston disc (6) in the static cavity (4). An intake vertical cavity (8) is formed inside the detection head (2). A piston disc (6) is slidably and sealingly arranged in the intake vertical cavity (8). External air can enter the static cavity (4) through the detection head (2). A groove (9) is formed on the inner wall of the static cavity (4). A semiconductor sensor (10) is fixedly installed on the inner wall of the groove (9). An exhaust pipe (11) is fixedly installed on the inner wall of the exhaust cavity (3). The exhaust pipe (11) can discharge the gas in the exhaust cavity (3) to the outside of the alarm main body (1).

2. The combustible gas alarm according to claim 1, wherein: A plurality of groups of first one-way valves (7) are arranged on the piston disc (6) at equal circumferential intervals. A plurality of groups of intake transverse cavities (12) are arranged on the inner circumference of the detection head (2) at equal intervals. The first one-way valve (7) is used in cooperation with the intake vertical cavity (8).

3. The combustible gas alarm according to claim 2, characterized in that: A ring plate (13) is fixedly installed in the static cavity (4). An inner air cavity (14) and an outer air cavity (15) are arranged in the static cavity (4). The ring plate (13) divides the static cavity (4) into two parts, namely the inner air cavity (14) and the outer air cavity (15) from the inside to the outside. The volume of the outer air cavity (15) is smaller than that of the inner air cavity (14). The semiconductor sensor (10) is located in the outer air cavity (15).

4. The combustible gas alarm according to claim 3, characterized in that: A chute (17) is formed in the ring plate (13). A second one-way valve (16) is slidably and sealingly arranged in the chute (17). The inner air cavity (14) and the outer air cavity (15) are communicated through the second one-way valve (16). A third one-way valve (18) is fixedly arranged on the inner wall of the exhaust cavity (3). The exhaust cavity (3) and the outer air cavity (15) are communicated through the third one-way valve (18).

5. The combustible gas alarm according to claim 4, wherein: A second spring (20) is fixedly installed in the outer air cavity (15). The top end of the second spring (20) is fixedly connected to a push ring (21). The push ring (21) is slidably and sealingly arranged in the outer air cavity (15). A first spring (19) is fixedly arranged on the inner wall of the chute (17). The first spring (19) is fixedly connected to the second one-way valve (16).

6. The combustible gas alarm according to claim 5, characterized in that: The top of the detection head (2) is fixedly connected to an inclined platform (28). A filter screen (22) is fixedly installed on the outer surface of the inclined platform (28). The filter screen (22) is arranged in the lowest horizontal circle of the inclined platform (28). The filter screen (22) is annular.

7. The combustible gas alarm according to claim 6, wherein: A knocking component (30) is arranged on the outer surface of the telescopic end of the electric telescopic rod (5). The knocking component (30) is used in cooperation with the filter screen (22). The knocking component (30) includes multiple groups of triangular plates (27) fixedly installed on the inner surface of the filter screen (22). Multiple groups of long rods (23) are arranged at equal circumferential intervals on the outer surface of the output end of the electric telescopic rod (5). A contraction groove (29) is formed inside each group of long rods (23). A vibration spring (26) is arranged in the contraction groove (29). One end of the vibration spring (26) is fixedly connected to the inner wall of the contraction groove (29), and the other end of the vibration spring (26) is fixedly connected to a sliding rod (24). The sliding rod (24) is slidably arranged in the contraction groove (29). One end of the sliding rod (24) located outside the contraction groove (29) is fixedly connected to a contact head (25). The contact head (25) is used in cooperation with the triangular plate (27).

8. The combustible gas alarm according to claim 7, characterized in that: The gas in the intake horizontal cavity (12) can enter the intake vertical cavity (8) through the first one-way valve (7). The gas in the inner air cavity (14) can enter the outer air cavity (15) through the second one-way valve (16). The gas in the outer air cavity (15) can enter the exhaust cavity (3) through the third one-way valve (18).

9. The combustible gas alarm according to claim 8, wherein: The second one-way valve (16) is L-shaped. The pipe diameter of the second one-way valve (16) is larger than that of the third one-way valve (18).

10. The combustible gas alarm according to claim 9, characterized in that: The detection head (2) is fixedly connected to the alarm main body (1) by threads. The contact head (25) contacts the inner surface of the filter screen (22).

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