Push type potentiometer

Abstract

The utility model relates to the technical field of potentiometers, in particular to a push type potentiometer, which is convenient to press and adjust the potentiometer in various modes, improves the practicability, and is convenient to protect the potentiometer from being damaged by excessive pressing. Comprising a shell and a resistor body, the device further comprises a main body mechanism, a pressing mechanism, a first fixing mechanism, a second fixing mechanism and an alarm mechanism, the pressing mechanism is installed at the top end of the main body mechanism, the first fixing mechanism is installed on the pressing mechanism, the second fixing mechanism is installed at the top end of the main body mechanism, and the alarm mechanism is installed in the main body mechanism; the potentiometer is adjusted by pressing the main body mechanism through the pressing mechanism, the potentiometer of the main body mechanism is adjusted and fixed through the first fixing mechanism, the potentiometer is conveniently adjusted and fixed through the second fixing mechanism in another mode, and the potentiometer is conveniently prevented from being damaged by too large pressing force through the alarm mechanism.

Description

Technical Field

[0001] The utility model relates to the technical field of potentiometers, in particular to a push-type potentiometer. Background Art

[0002] A potentiometer is an adjustable electronic component with three terminals, and its resistance value can be adjusted according to a certain change rule. It usually consists of a resistor and a movable brush. When the brush moves along the resistor, the output end can obtain a resistance value or voltage that is related to the displacement. The potentiometer can be used as a three-terminal component or a two-terminal component. When used as a two-terminal component, it is equivalent to a variable resistor, and an output voltage that is related to the input voltage can be obtained in the circuit.

[0003] Existing potentiometers, such as the prior art with application number CN201611051553.5, include a potentiometer, an adapter, a push switch and a lower support plate. The adapter is a columnar body with grooves at both ends of the columnar body. The potentiometer is fixed in the groove at one end, and the movable column of the push switch is fixed in the groove at the other end. The push switch housing is fixed on the lower support plate. The potentiometer integrated with the push switch is easy to install as a whole and has high assembly efficiency, which greatly improves the space utilization of the light guide plate. The overall structure is simple, the product is easy to maintain, and can improve the production efficiency of the light guide plate.

[0004] However, the prior art is not convenient for adjusting the pressing method and controlling the pressing force, which reduces the convenience. Furthermore, the prior art is not convenient for preventing the damage of the potentiometer caused by excessive pressing force, which reduces the practicality. Utility Model Content

[0005] In order to solve the above technical problems, the utility model provides a push-type potentiometer which is convenient for adjusting the potentiometer by pressing in multiple ways, thereby improving the practicality, and is convenient for protecting the potentiometer from damage caused by excessive pressing.

[0006] The utility model discloses a push-type potentiometer, comprising a shell and a resistor; a main body mechanism, a push mechanism, a first fixing mechanism, a second fixing mechanism and an alarm mechanism, wherein the push mechanism is mounted on the top of the main body mechanism, the first fixing mechanism is mounted on the push mechanism, the second fixing mechanism is mounted on the top of the main body mechanism, and the alarm mechanism is mounted in the main body mechanism; the main body mechanism is pressed by the push mechanism to adjust the potentiometer; the adjustment of the potentiometer of the main body mechanism is fixed by the first fixing mechanism; the second fixing mechanism is convenient for adjusting and fixing the potentiometer in another way; the alarm mechanism is convenient for preventing the potentiometer from being damaged by excessive pressing force; the potentiometer is adjusted by pressing the main body mechanism by the push mechanism, thereby improving practicality; the adjustment of the potentiometer of the main body mechanism is fixed by the first fixing mechanism; the second fixing mechanism is convenient for adjusting and fixing the potentiometer in another way; the alarm mechanism is convenient for preventing the potentiometer from being damaged by excessive pressing force, thereby improving practicality.

[0007] Preferably, the main body mechanism includes a shell, a resistor, a sliding sleeve, a sliding plate and a sliding connecting plate, the resistor is installed in the shell, the sliding sleeve is installed inside the shell, the sliding sleeve is provided with a first slide groove, a second slide groove and a third slide groove, the second slide groove is connected to the third slide groove, the sliding plate is slidably installed in the sliding sleeve, the sliding connecting plate is installed on the sliding plate, the sliding connecting plate is slidably installed in the first slide groove, and the sliding connecting plate contacts the resistor; when the potentiometer is to be adjusted, the sliding plate is pushed to slide in the sliding sleeve by pressing the pressing mechanism, thereby driving the sliding connecting plate to slide in the first slide groove, thereby completing the adjustment of the potentiometer.

[0008] Preferably, the pressing mechanism includes a pressing rod, a limit seat, a limit plate and a first spring, one end of the pressing rod is rotatably mounted on the top of the sliding plate, the pressing rod is slidably mounted on the top of the shell, the limit seat is mounted on the top of the shell, the pressing rod is slidably mounted on the limit seat, the limit plate is mounted on the top of the pressing rod, one end of the first spring is mounted on the top of the limit seat, and the other end of the first spring is mounted on the bottom end of the limit plate; when the potentiometer is to be adjusted, the limit plate is pressed to drive the pressing rod to slide on the top of the shell and the limit seat, thereby pushing the sliding plate to slide in the sliding sleeve, thereby driving the sliding connecting plate to slide in the first sliding groove, thereby completing the adjustment of the potentiometer, and the elasticity of the first spring facilitates the rebound of the pressing rod.

[0009] Preferably, the first fixing mechanism comprises a fixing box, a sliding mounting plate, a baffle, a second spring and a fixing tooth, the fixing box is mounted on the pressing rod, a chamber is arranged in the fixing box, the sliding mounting plate is slidably mounted in the fixing box, the baffle is mounted on the sliding mounting plate, the baffle is slidably mounted on the outer wall of the fixing box, one end of the second spring is mounted on the inner wall of the fixing box, the other end of the second spring is mounted on the sliding mounting plate, the fixing tooth is mounted on the inner wall of the shell, and the baffle is slidably mounted in the third sliding groove of the sliding sleeve; when the sliding plate slides in the sliding sleeve, the baffle contacts with the fixing tooth, the fixing tooth squeezes the baffle to cause the second spring to contract, and then the sliding mounting plate is caused to slide in the fixing box, the baffle is pushed between the fixing teeth by the elasticity of the second spring, the baffle is resisted and fixed by the fixing teeth, and then the sliding plate is fixed; when the sliding plate is to be reset, the limit plate is rotated to cause the limit seat to rotate, and then the fixed box is driven to rotate, so that the baffle is rotated into the second sliding groove, and since the baffle releases the fixation of the fixing tooth, the sliding plate is reset by the elasticity of the first spring.

[0010] Preferably, the second fixing mechanism includes a sliding box, a fixed block and a cam shaft, the sliding box is installed at the top of the shell, the pressing rod passes through the sliding box, the fixed block is slidably installed in the sliding box, and the cam shaft is rotatably installed in the sliding box; when the potentiometer is adjusted by sliding the baffle in the second slide groove, the cam shaft is rotated, and the convex point of the cam shaft pushes the fixed block to slide in the sliding box, and then the cam shaft squeezes the fixed block to fix the pressing rod.

[0011] Preferably, the alarm mechanism includes a sliding cylinder, a top block, a pressure sensor and a third spring, the sliding cylinder is installed at the bottom end of the sliding sleeve, the top block is slidably installed in the sliding cylinder, the pressure sensor is installed in the sliding cylinder, one end of the third spring is installed at the top end of the pressure sensor, the other end of the third spring is installed at the bottom end of the top block, and a buzzer is arranged on the outer wall of the shell; when the sliding plate slides in the sliding sleeve, when the position of the sliding plate reaches the limit position, the sliding plate contacts the top block and squeezes the top block to slide in the sliding cylinder, thereby squeezing the pressure sensor through the elasticity of the third spring, detecting the pressure through the pressure sensor, and sending an electrical signal through the pressure sensor to control the buzzer alarm.

[0012] Compared with the prior art, the utility model has the following beneficial effects: the potentiometer is adjusted by pressing the main body mechanism through the pressing mechanism, thereby improving practicality; the adjustment of the potentiometer of the main body mechanism is fixed by the first fixing mechanism; the second fixing mechanism facilitates the adjustment and fixing of the potentiometer in another way; and the alarm mechanism facilitates preventing damage to the potentiometer caused by excessive pressing force, thereby improving practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a first axonometric structural schematic diagram of the utility model;

[0014] Figure 2 It is a second axonometric structural schematic diagram of the utility model;

[0015] Figure 3 It is a front-view cross-sectional axonometric structural schematic diagram of the utility model;

[0016] Figure 4 It is a front cross-sectional structural schematic diagram of the utility model;

[0017] Figure 5 It is a schematic diagram of the top-view cross-section axonometric structure of the utility model;

[0018] Figure 6 It is a schematic diagram of the cross-sectional structure of the utility model in a top view;

[0019] Markings in the accompanying drawings: 01, main body mechanism; 11, shell; 12, resistor; 13, sliding sleeve; 14, first slide groove; 15, second slide groove; 16, third slide groove; 17, sliding plate; 18, sliding connecting plate; 02, pressing mechanism; 21, pressing rod; 22, limit seat; 23, limit plate; 24, first spring; 03, first fixing mechanism; 31, fixing box; 32, sliding mounting plate; 33, baffle; 34, second spring; 35, fixing tooth; 04, second fixing mechanism; 41, sliding box; 42, fixing block; 43, cam; 05, alarm mechanism; 51, sliding cylinder; 52, top block; 53, pressure sensor; 54, third spring. DETAILED DESCRIPTION

[0020] In order to facilitate the understanding of the utility model, the utility model will be described more comprehensively below with reference to the relevant drawings. The utility model can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the utility model more thorough and comprehensive.

[0021] Example 1

[0022] like Figure 2 , Figure 3 and Figure 5 As shown, it includes a housing 11 and a resistor 12, and also includes a main body mechanism 01, a pressing mechanism 02, a first fixing mechanism 03, a second fixing mechanism 04 and an alarm mechanism 05. The pressing mechanism 02 is installed at the top of the main body mechanism 01, the first fixing mechanism 03 is installed on the pressing mechanism 02, the second fixing mechanism 04 is installed at the top of the main body mechanism 01, and the alarm mechanism 05 is installed in the main body mechanism 01;

[0023] The potentiometer is adjusted by pressing the main body 01 through the pressing mechanism 02, and the adjustment of the potentiometer of the main body 01 is fixed through the first fixing mechanism 03. The second fixing mechanism 04 is convenient for adjusting and fixing the potentiometer in another way, and the alarm mechanism 05 is convenient for preventing the potentiometer from being damaged by excessive pressing force.

[0024] The main body mechanism 01 includes a housing 11, a resistor 12, a sliding sleeve 13, a sliding plate 17 and a sliding connecting plate 18. The resistor 12 is installed in the housing 11, the sliding sleeve 13 is installed inside the housing 11, the sliding sleeve 13 is provided with a first sliding groove 14, a second sliding groove 15 and a third sliding groove 16, the second sliding groove 15 is connected to the third sliding groove 16, the sliding plate 17 is slidably installed in the sliding sleeve 13, the sliding connecting plate 18 is installed on the sliding plate 17, the sliding connecting plate 18 is slidably installed in the first sliding groove 14, and the sliding connecting plate 18 is in contact with the resistor 12;

[0025] The pressing mechanism 02 includes a pressing rod 21, a limiting seat 22, a limiting plate 23 and a first spring 24. One end of the pressing rod 21 is rotatably mounted on the top of the sliding plate 17, the pressing rod 21 is slidably mounted on the top of the housing 11, the limiting seat 22 is mounted on the top of the housing 11, the pressing rod 21 is slidably mounted on the limiting seat 22, the limiting plate 23 is mounted on the top of the pressing rod 21, one end of the first spring 24 is mounted on the top of the limiting seat 22, and the other end of the first spring 24 is mounted on the bottom end of the limiting plate 23;

[0026] The first fixing mechanism 03 includes a fixing box 31, a sliding mounting plate 32, a baffle 33, a second spring 34 and a fixing tooth 35. The fixing box 31 is mounted on the pressing rod 21. A chamber is provided in the fixing box 31. The sliding mounting plate 32 is slidably mounted in the fixing box 31. The baffle 33 is mounted on the sliding mounting plate 32. The baffle 33 is slidably mounted on the outer wall of the fixing box 31. One end of the second spring 34 is mounted on the inner wall of the fixing box 31. The other end of the second spring 34 is mounted on the sliding mounting plate 32. The fixing tooth 35 is mounted on the inner wall of the housing 11. The baffle 33 is slidably mounted in the third slide groove 16 of the sliding sleeve 13.

[0027] When the potentiometer is to be adjusted, the pressing rod 21 is driven to slide on the top of the housing 11 and the limiting seat 22 by pressing the limiting plate 23, thereby pushing the sliding plate 17 to slide in the sliding sleeve 13, thereby driving the sliding connecting plate 18 to slide in the first sliding groove 14, thereby completing the adjustment of the potentiometer. The elasticity of the first spring 24 facilitates the rebound of the pressing rod 21. When the sliding plate 17 slides in the sliding sleeve 13, the baffle 33 contacts the fixed tooth 35, and the baffle 33 is squeezed by the fixed tooth 35 to make the second spring 34 contract, and then the sliding mounting plate 32 slides in the fixed box 31, and the elasticity of the second spring 34 is used to The baffle plate 33 is pushed between the fixed teeth 35, and the fixed teeth 35 are used to resist and fix the baffle plate 33, thereby fixing the sliding plate 17. When the sliding plate 17 needs to be reset, the limit plate 23 is rotated to rotate the limit seat 22, thereby driving the fixed box 31 to rotate, so that the baffle plate 33 is rotated into the second slide groove 15. Since the baffle plate 33 releases the fixation of the fixed teeth 35, the sliding plate 17 is reset through the elasticity of the first spring 24. The second fixing mechanism 04 facilitates the adjustment and fixation of the potentiometer in another way. The alarm mechanism 05 facilitates preventing damage to the potentiometer caused by excessive pressing force, thereby improving practicality.

[0028] Example 2

[0029] like Figures 1 to 6 As shown, it includes a housing 11 and a resistor 12, and also includes a main body mechanism 01, a pressing mechanism 02, a first fixing mechanism 03, a second fixing mechanism 04 and an alarm mechanism 05. The pressing mechanism 02 is installed at the top of the main body mechanism 01, the first fixing mechanism 03 is installed on the pressing mechanism 02, the second fixing mechanism 04 is installed at the top of the main body mechanism 01, and the alarm mechanism 05 is installed in the main body mechanism 01;

[0030] The potentiometer is adjusted by pressing the main body 01 through the pressing mechanism 02, and the adjustment of the potentiometer of the main body 01 is fixed through the first fixing mechanism 03. The second fixing mechanism 04 is convenient for adjusting and fixing the potentiometer in another way, and the alarm mechanism 05 is convenient for preventing the potentiometer from being damaged by excessive pressing force.

[0031] The main body mechanism 01 includes a housing 11, a resistor 12, a sliding sleeve 13, a sliding plate 17 and a sliding connecting plate 18. The resistor 12 is installed in the housing 11, the sliding sleeve 13 is installed inside the housing 11, the sliding sleeve 13 is provided with a first sliding groove 14, a second sliding groove 15 and a third sliding groove 16, the second sliding groove 15 is connected to the third sliding groove 16, the sliding plate 17 is slidably installed in the sliding sleeve 13, the sliding connecting plate 18 is installed on the sliding plate 17, the sliding connecting plate 18 is slidably installed in the first sliding groove 14, and the sliding connecting plate 18 is in contact with the resistor 12;

[0032] The pressing mechanism 02 includes a pressing rod 21, a limiting seat 22, a limiting plate 23 and a first spring 24. One end of the pressing rod 21 is rotatably mounted on the top of the sliding plate 17, the pressing rod 21 is slidably mounted on the top of the housing 11, the limiting seat 22 is mounted on the top of the housing 11, the pressing rod 21 is slidably mounted on the limiting seat 22, the limiting plate 23 is mounted on the top of the pressing rod 21, one end of the first spring 24 is mounted on the top of the limiting seat 22, and the other end of the first spring 24 is mounted on the bottom end of the limiting plate 23;

[0033] The second fixing mechanism 04 includes a sliding box 41, a fixing block 42 and a convex shaft 43. The sliding box 41 is installed at the top of the housing 11. The pressing rod 21 passes through the sliding box 41. The fixing block 42 is slidably installed in the sliding box 41. The convex shaft 43 is rotatably installed in the sliding box 41.

[0034] The alarm mechanism 05 includes a sliding cylinder 51, a top block 52, a pressure sensor 53 and a third spring 54. The sliding cylinder 51 is installed at the bottom end of the sliding sleeve 13, the top block 52 is slidably installed in the sliding cylinder 51, the pressure sensor 53 is installed in the sliding cylinder 51, one end of the third spring 54 is installed at the top end of the pressure sensor 53, and the other end of the third spring 54 is installed at the bottom end of the top block 52. A buzzer is arranged on the outer wall of the housing 11;

[0035] When the potentiometer is to be adjusted, the pressing rod 21 is driven to slide on the top of the shell 11 and the limiting seat 22 by pressing the limiting plate 23, and then the sliding plate 17 is pushed to slide in the sliding sleeve 13, and then the sliding connecting plate 18 is driven to slide in the first slide groove 14, so as to complete the adjustment of the potentiometer. The elasticity of the first spring 24 facilitates the rebound of the pressing rod 21, and the adjustment of the potentiometer of the main mechanism 01 is fixed by the first fixing mechanism 03. When the potentiometer is adjusted by sliding the baffle 33 in the second slide groove 15, the convex shaft 43 is rotated. Since the convex point of the convex shaft 43 pushes the fixed block 42 to slide in the sliding box 41, the convex shaft 43 squeezes the fixed block 42 to fix the pressing rod 21. When the sliding plate 17 slides in the sliding sleeve 13, when the position of the sliding plate 17 reaches the limit position, the sliding plate 17 contacts the top block 52 and squeezes the top block 52 to slide in the sliding cylinder 51, so that the pressure sensor 53 is squeezed by the elasticity of the third spring 54, the pressure is detected by the pressure sensor 53, and the pressure sensor 53 sends an electrical signal to control the buzzer alarm.

[0036] like Figures 1 to 6As shown, a push-type potentiometer of the utility model is used. When the potentiometer is in operation, the pressing limit plate 23 is pressed to drive the pressing rod 21 to slide on the top of the shell 11 and the limit seat 22, thereby pushing the sliding plate 17 to slide in the sliding sleeve 13, thereby driving the sliding connecting plate 18 to slide in the first sliding groove 14, thereby completing the adjustment of the potentiometer. The elasticity of the first spring 24 facilitates the rebound of the pressing rod 21. When the sliding plate 17 slides in the sliding sleeve 13, the baffle 33 contacts the fixed teeth 35, and the baffle 33 is squeezed by the fixed teeth 35 to make the second spring 34 contract, and then the sliding mounting plate 32 slides in the fixed box 31. The baffle 33 is pushed between the fixed teeth 35 by the elasticity of the second spring 34, and the baffle 33 is resisted and fixed by the fixed teeth 35, thereby fixing the sliding plate 17. When the sliding plate 17 is to be reset, the limiting plate 23 is rotated to make The limit seat 22 rotates, thereby driving the fixed box 31 to rotate, so that the baffle plate 33 rotates into the second slide groove 15. Since the baffle plate 33 releases the fixation of the fixed tooth 35, the sliding plate 17 is reset by the elasticity of the first spring 24. When the baffle plate 33 slides in the second slide groove 15 to adjust the potentiometer, the convex shaft 43 is rotated, and the convex point of the convex shaft 43 pushes the fixed block 42 to slide in the sliding box 41, and then the convex shaft 43 squeezes the fixed block 42 to fix the pressing rod 21. When the sliding plate 17 slides in the sliding sleeve 13, when the position of the sliding plate 17 reaches the limit position, the sliding plate 17 contacts the top block 52 and squeezes the top block 52 to slide in the sliding cylinder 51, thereby squeezing the pressure sensor 53 by the elasticity of the third spring 54, and the pressure is detected by the pressure sensor 53, and the pressure sensor 53 sends an electrical signal to control the buzzer alarm.

[0037] The pressure sensor 53 of the utility model is purchased on the market, and technicians in the industry only need to install and operate it according to the accompanying instruction manual, without the need for technicians in the field to make creative efforts.

[0038] The main functions realized by the utility model are: during the working process of the potentiometer, the potentiometer can be adjusted by pressing in a variety of ways, thereby improving the practicality, and the potentiometer can be protected from damage caused by excessive pressing.

[0039] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principle of the present invention. These improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A push-type potentiometer, comprising a housing (11) and a resistor (12); characterized in that: It also includes a main body mechanism (01), a pressing mechanism (02), a first fixing mechanism (03), a second fixing mechanism (04) and an alarm mechanism (05), wherein the pressing mechanism (02) is mounted on the top of the main body mechanism (01), the first fixing mechanism (03) is mounted on the pressing mechanism (02), the second fixing mechanism (04) is mounted on the top of the main body mechanism (01), and the alarm mechanism (05) is mounted in the main body mechanism (01), and the potentiometer is adjusted by pressing the main body mechanism (01) with the pressing mechanism (02); The first fixing mechanism (03) fixes the adjustment of the potentiometer of the main mechanism (01), the second fixing mechanism (04) facilitates the adjustment and fixing of the potentiometer in another way, and the alarm mechanism (05) facilitates preventing damage to the potentiometer caused by excessive pressing force.

2. A push-type potentiometer as claimed in claim 1, characterized in that: The main body mechanism (01) comprises a housing (11), a resistor (12), a sliding sleeve (13), a sliding plate (17) and a sliding connecting plate (18); the resistor (12) is installed in the housing (11); the sliding sleeve (13) is installed inside the housing (11); a first sliding groove (14), a second sliding groove (15) and a third sliding groove (16) are arranged on the sliding sleeve (13); the second sliding groove (15) is connected to the third sliding groove (16); the sliding plate (17) is slidably installed in the sliding sleeve (13); the sliding connecting plate (18) is installed on the sliding plate (17); the sliding connecting plate (18) is slidably installed in the first sliding groove (14); and the sliding connecting plate (18) contacts the resistor (12).

3. A push-type potentiometer as claimed in claim 2, characterized in that: The pressing mechanism (02) comprises a pressing rod (21), a limiting seat (22), a limiting plate (23) and a first spring (24); one end of the pressing rod (21) is rotatably mounted on the top end of the sliding plate (17); the pressing rod (21) is slidably mounted on the top end of the shell (11); the limiting seat (22) is mounted on the top end of the shell (11); the pressing rod (21) is slidably mounted on the limiting seat (22); the limiting plate (23) is mounted on the top end of the pressing rod (21); one end of the first spring (24) is mounted on the top end of the limiting seat (22); and the other end of the first spring (24) is mounted on the bottom end of the limiting plate (23).

4. A push-type potentiometer as claimed in claim 3, characterized in that: The first fixing mechanism (03) comprises a fixing box (31), a sliding mounting plate (32), a baffle (33), a second spring (34) and a fixing tooth (35); the fixing box (31) is mounted on the pressing rod (21); a chamber is arranged in the fixing box (31); the sliding mounting plate (32) is slidably mounted in the fixing box (31); the baffle (33) is mounted on the sliding mounting plate (32); the baffle (33) is slidably mounted on the outer wall of the fixing box (31); one end of the second spring (34) is mounted on the inner wall of the fixing box (31); the other end of the second spring (34) is mounted on the sliding mounting plate (32); the fixing tooth (35) is mounted on the inner wall of the housing (11); and the baffle (33) is slidably mounted in the third sliding groove (16) of the sliding sleeve (13).

5. A push-type potentiometer as claimed in claim 2, characterized in that: The second fixing mechanism (04) comprises a sliding box (41), a fixing block (42) and a convex shaft (43); the sliding box (41) is installed at the top end of the housing (11); the pressing rod (21) passes through the sliding box (41); the fixing block (42) is slidably installed in the sliding box (41); and the convex shaft (43) is rotatably installed in the sliding box (41).

6. A push-type potentiometer as claimed in claim 2, characterized in that: The alarm mechanism (05) comprises a sliding cylinder (51), a top block (52), a pressure sensor (53) and a third spring (54); the sliding cylinder (51) is mounted at the bottom end inside the sliding sleeve (13); the top block (52) is slidably mounted inside the sliding cylinder (51); the pressure sensor (53) is mounted inside the sliding cylinder (51); one end of the third spring (54) is mounted at the top end of the pressure sensor (53); the other end of the third spring (54) is mounted at the bottom end of the top block (52); and a buzzer is arranged on the outer wall of the housing (11).

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