Alarm device for long-term pressure on a manhole cover

Abstract

The utility model belongs to municipal pipe network maintenance technical field, specifically provides a kind of alarm device for manhole cover long time pressure, including power supply BT, the power supply BT is powered to time delay circuit, NE555 delay module and alarm release circuit by touch pressure switch S1, the output of time delay circuit is connected with NE555 delay module, the output of NE555 delay module is connected alarm release circuit and alarm circuit;Time delay circuit and NE555 delay module are used for time control, when the pressure of manhole cover reaches the set time, trigger alarm circuit and alarm, alarm release circuit is used to when the pressure of manhole cover is released and touch pressure switch is disconnected, change the output voltage of NE555 delay module, alarm circuit is released alarm. By setting the device, can be in manhole cover bears certain pressure to set time, only then alarm, it is favorable to pipe network management operation and maintenance.

Description

Technical Field

[0001] This utility model relates to the field of municipal pipeline maintenance technology, and in particular to an alarm device for manhole covers subjected to long-term pressure. Background Technology

[0002] Prolonged exposure to pressure can cause manhole covers to deform, crack, and break. Sustained pressure can loosen the connection between the cover and the base, or even cause the cover to shift. If vehicles or pedestrians pass by, accidents may occur due to a damaged manhole cover, such as vehicles getting stuck or pedestrians falling and getting injured. Furthermore, a damaged or shifted manhole cover exposes the opening, potentially causing pedestrians or vehicles to fall in, resulting in serious injury or death. In conclusion, damage or shifting of manhole covers caused by prolonged pressure can affect the normal passage of vehicles and pedestrians and may even lead to traffic accidents. In addition, the presence of toxic or harmful gases or water inside the manhole further increases the risk of falling in and poses a safety hazard.

[0003] Existing manhole cover pressure alarm devices still trigger false alarms when pedestrians or vehicles briefly pass over the manhole cover. Therefore, there is an urgent need for a device that can alarm when a manhole cover is under prolonged pressure to prevent deformation, damage, or displacement caused by prolonged pressure. Summary of the Invention

[0004] The technical problem to be solved by this utility model is to provide an alarm device for manhole covers subjected to long-term pressure. The alarm will only be triggered after the manhole cover has been subjected to a certain pressure for a set time, which is beneficial to the management and maintenance of pipeline networks.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by this utility model is: an alarm device for long-term pressure on manhole covers, including a power supply BT. The power supply BT supplies power to a delay circuit, an NE555 delay module, and an alarm deactivation circuit through a pressure-sensitive switch S1. The output terminal of the delay circuit is connected to the NE555 delay module, and the output terminal of the NE555 delay module is connected to the alarm deactivation circuit and the alarm circuit. The delay circuit and the NE555 delay module are used for time control. When the pressure on the manhole cover reaches a set time, the alarm circuit is triggered to sound an alarm. The alarm deactivation circuit is used to change the output voltage of the NE555 delay module to deactivate the alarm circuit when the pressure on the manhole cover is released and the pressure-sensitive switch is opened.

[0006] In a preferred embodiment, the delay circuit includes a range resistor. One end of the range resistor is connected to the positive terminal of the power supply BT via a pressure switch S1. The other end of the range resistor is connected to the first terminal of capacitor C1. The second terminal of capacitor C1 is connected to the negative terminal of the power supply BT. The first terminal of capacitor C1 is connected to the sixth and seventh pins of the NE555 delay module.

[0007] In a preferred embodiment, the range resistors are configured with three ranges: a first range resistor R7, a second range resistor R8, and a third range resistor R9. The resistance of the first range resistor R7 is less than that of the second range resistor R8, and the resistance of the second range resistor R8 is less than that of the third range resistor R9. The first terminal of the capacitor C1 is connected to the first range resistor R7, the second range resistor R8, or the third range resistor R9 via a switching switch S2.

[0008] In a preferred embodiment, the second terminal of capacitor C1 is grounded.

[0009] In the preferred embodiment, the first pin of the NE555 delay module is grounded, the second pin is connected to the alarm cancellation circuit, the third pin is connected to the alarm circuit, the fifth pin is connected to the first end of capacitor C2, the second end of capacitor C2 is grounded, the sixth and seventh pins are connected to the delay circuit, and the eighth pin is connected to the pressure switch S1.

[0010] In a preferred embodiment, the alarm deactivation circuit includes diodes D1 and D2. The anode of diode D2 is connected to the pressure-sensitive switch S1. The cathode of diode D2 is connected in sequence to resistor R2 and the first terminal of capacitor C3. The second terminal of capacitor C3 is grounded. The first terminal of capacitor C3 is simultaneously connected to the emitter of transistor Q1 and the NE555 delay module. The base of transistor Q1 is connected to the cathode of diode D1. The collector of transistor Q1 is connected to the collector of transistor Q2. The anode of diode D1 is connected to the pressure-sensitive switch S1. The emitter of transistor Q2 is grounded.

[0011] In a preferred embodiment, a resistor R1 is provided between the emitter of the transistor Q2 and ground.

[0012] In a preferred embodiment, the alarm circuit includes transistors Q3 and Q4, capacitors C4 and C5, resistors R3, R4, and R5, and an LED L1. The positive terminal of LED L1 is connected to the same end of resistors R3, R4, R5, and R6. The other end of resistor R6 is grounded. The other ends of resistors R3 and R4 are connected to the first and second ends of capacitor C4, respectively. The negative terminal of LED L1 and resistor R5 are connected to the first and second ends of capacitor C5, respectively. The first end of capacitor C4 is connected to the collector of transistor Q3. The base of transistor Q3 is connected to the second end of capacitor C5. The second end of capacitor C4 is connected to the base of transistor Q4. The emitters of transistors Q3 and Q4 are connected to the NE555 delay module.

[0013] In a preferred embodiment, the alarm circuit further includes a communication module. One end of the communication module is grounded through diode D3, with the negative terminal of diode D3 connected to the communication module and the positive terminal grounded. The other end of the communication module is connected to the NE555 delay module through diode D5, with the negative terminal of diode D5 connected to the NE555 delay module.

[0014] In a preferred embodiment, a bypass circuit is provided on one side of the communication module, and a diode D4 is provided on the bypass circuit. The negative terminal of diode D4 is connected to the negative terminal of diode D3, and resistor R6 is grounded through Zener diode V1.

[0015] The alarm device for manhole covers subjected to prolonged pressure provided by this utility model has the following beneficial effects: 1. The alarm will only be triggered after the manhole cover has been subjected to a certain pressure for a set time. This effectively filters the instantaneous pressure from pedestrians and vehicles passing over the manhole cover in a short period of time, avoiding frequent invalid alarms that occupy maintenance resources and facilitating pipeline network management and maintenance.

[0016] 2. The delay circuit features three resistance levels with varying values. The delay time can be flexibly selected via switch S2. For manhole covers on main roads with high pedestrian and vehicle traffic, a short 60-minute delay can be selected by switching to R7 for rapid warning of potential risks. For manhole covers in remote areas or industrial zones, a long delay of 120 minutes / 240 minutes (switching to R8 / R9) can be selected to avoid false alarms caused by objects that have been there for extended periods (such as temporary storage). This multi-level adjustable design allows the device to adapt to different locations and usage frequencies of manhole covers in municipal pipe networks, improving the flexibility of maintenance solutions.

[0017] 3. The alarm deactivation circuit is designed so that when the pressure on the manhole cover is released and the pressure-sensitive switch S1 is opened, capacitor C3 discharges through transistors Q1 / Q2 and resistor R1. It takes about 10 seconds for the discharge to reach below 1 / 3 of the power supply voltage. If the pressure release time exceeds 10 seconds, the circuit is completely reset and the timing restarts when the manhole cover is pressurized again. If the pressure is applied again in less than 10 seconds, C3 has not completed discharging, and the alarm circuit will be triggered again. This mechanism avoids the problem of frequent resets after frequent short-term pressure releases and also prevents the alarm from failing to stop in time after the pressure is released, ensuring that the alarm status is accurately matched with the actual pressure risk of the manhole cover.

[0018] 4. The alarm circuit adopts a dual output design of on-site warning and background notification. On the one hand, the charging and discharging circuit composed of transistors Q3 / Q4 and capacitors C4 / C5 drives the LED L1 to flash, realizing on-site visual warning and reminding pedestrians and vehicles of the potential danger of the manhole cover. On the other hand, the communication module communicates with the system background, turning on when the NE555 delay module outputs a low voltage, and stably transmitting the alarm signal to the background. The dual alarm not only realizes on-site risk warning, but also ensures that maintenance personnel can remotely obtain alarm information in a timely manner, avoiding delays in manhole cover maintenance due to no one on-site noticing the danger. Attached Figure Description

[0019] The present invention will be further described below with reference to the accompanying drawings and embodiments: Figure 1 This is the circuit diagram of this utility model; In the diagram: Power supply BT, pressure switch S1, toggle switch S2, capacitors C1, C2, C3, C4, and C5, resistors R1, R2, R3, R4, R5, and R6, first-position resistor R7, second-position resistor R8, and third-position resistor R9, diodes D1, D2, D3, D4, and D5, transistors Q1, Q2, Q3, and Q4, LED L1, Zener diode V1, NE555 delay module 1, and communication module 2. Detailed Implementation

[0020] like Figure 1 As shown, an alarm device for manhole covers subjected to prolonged pressure includes a power supply BT. In this embodiment, the power supply BT outputs a voltage of 4.5V. The power supply BT supplies power to a delay circuit, an NE555 delay module, and an alarm deactivation circuit via a pressure-sensitive switch S1. The output of the delay circuit is connected to the NE555 delay module, and the output of the NE555 delay module is connected to the alarm deactivation circuit and the alarm circuit. The delay circuit and the NE555 delay module are used for time control. When the pressure on the manhole cover reaches a set time, the alarm circuit is triggered to sound an alarm. The alarm deactivation circuit is used to change the output voltage of the NE555 delay module to deactivate the alarm circuit when the pressure on the manhole cover is released and the pressure-sensitive switch is opened.

[0021] The pressure-sensitive switch S1 is installed below the pressure surface of the manhole cover as a sensing element. Specifically, the adjustable pressure type of PMN or PMM series can be selected. The pressure-sensitive switch S1 is used to sense the pressure signal acting on the manhole cover from the top. The delay circuit is mainly for time control. When a certain delay time is reached, the delay circuit alarms to remind the Yangtze River protection pipeline network manager that an alarm has been received about the abnormality of the manhole cover.

[0022] The delay circuit described in this embodiment includes a range resistor. One end of the range resistor is connected to the positive terminal of the power supply BT through a touch switch S1, and the other end of the range resistor is connected to the first terminal of capacitor C1. The second terminal of capacitor C1 is connected to the negative terminal of the power supply BT. In this embodiment, the second terminal of capacitor C1 is also grounded. The first terminal of capacitor C1 is connected to the sixth and seventh pins of the NE555 delay module. The capacitor C1 is 470uF.

[0023] The resistors are configured with three levels: a first level resistor R7, a second level resistor R8, and a third level resistor R9. The resistance of the first level resistor R7 is less than that of the second level resistor R8, and the resistance of the second level resistor R8 is less than that of the third level resistor R9. The first terminal of the capacitor C1 is connected to the first level resistor R7, the second level resistor R8, or the third level resistor R9 through a switching switch S2.

[0024] In this embodiment, the first-position resistor R7, the second-position resistor R8, and the third-position resistor R9 are selected as 7MΩ, 14MΩ, and 28MΩ models, respectively.

[0025] The first pin of the NE555 delay module is grounded, the second pin is connected to the alarm cancellation circuit, the third pin is connected to the alarm circuit, the fourth pin has the same potential as the eighth pin (4.5V), the fifth pin is connected to the first terminal of capacitor C2, the second terminal of capacitor C2 is grounded, the sixth and seventh pins are connected to the delay circuit, and the eighth pin is connected to the pressure switch S1. Capacitor C2 is selected as 0.01uF.

[0026] The alarm deactivation circuit includes diodes D1 and D2. The anode of diode D2 is connected to a pressure-sensitive switch S1. The cathode of diode D2 is connected in sequence to resistor R2 and the first terminal of capacitor C3. The second terminal of capacitor C3 is grounded. The first terminal of capacitor C3 is also connected to the emitter of transistor Q1 and the NE555 delay module. The base of transistor Q1 is connected to the cathode of diode D1. The collector of transistor Q1 is connected to the collector of transistor Q2. The anode of diode D1 is connected to the pressure-sensitive switch S1. The emitter of transistor Q2 is grounded. A resistor R1 is placed between the emitter of transistor Q2 and ground. The larger the resistor R1, the slower C3 discharges. In this embodiment, when R1 is 10K ohms, the time required for C3 to discharge to below 1 / 3 of the power supply voltage is approximately 10 seconds.

[0027] The resistor R2 is selected as 200K ohms, and the capacitor C3 is selected as 100uF.

[0028] The alarm circuit includes transistors Q3 and Q4, capacitors C4 and C5, resistors R3, R4, and R5, and LED L1. The positive terminal of LED L1 is connected to the same end of resistors R3, R4, R5, and R6. The other end of resistor R6 is grounded, and the potential of the non-grounded end of resistor R6 is 4.5V. Resistors R3 and R4 are connected to the first and second ends of capacitor C4, respectively. The negative terminal of LED L1 and resistor R5 are connected to the first and second ends of capacitor C5, respectively. The first end of capacitor C4 is connected to the collector of transistor Q3, the base of transistor Q3 is connected to the second end of capacitor C5, the second end of capacitor C4 is connected to the base of transistor Q4, and the emitters of transistors Q3 and Q4 are connected to the NE555 delay module.

[0029] In this embodiment, capacitors C4 and C5 are both 47 uF, and resistors R3, R4, and R5 are 20K ohms, 100K ohms, and 100K ohms, respectively.

[0030] Preferably, the alarm circuit further includes a communication module, which communicates with the system backend or the central control computer. One end of the communication module is grounded through diode D3, with the cathode of diode D3 connected to the communication module and the anode grounded. The other end of the communication module is connected to the NE555 delay module through diode D5, with the cathode of diode D5 connected to the NE555 delay module. A bypass circuit is provided on one side of the communication module, with diode D4 installed on the bypass circuit. The cathode of diode D4 is connected to the cathode of diode D3, and resistor R6 is grounded through Zener diode V1.

[0031] By configuring the communication module, when the third pin of the NE555 delay module outputs a low voltage, current flows through the communication module line, transmitting an alarm signal to the system backend to trigger an alarm.

[0032] The main circuits used in this application include delay circuits and alarm circuits, the specific circuits of which are as follows: Figure 1 As shown, the parameters of each electrical component are as follows: the power supply BT output voltage is 4.5V; resistors R1, R2, R3, R4, R5, R6, R7, R8, and R9 are 10K ohms, 200K ohms, 20K ohms, 100K ohms, 100K ohms, 100 ohms, 7M ohms, 14M ohms, and 28M ohms, respectively; capacitors C1, C2, C3, C4, and C5 are 470uF, 0.01uF, 100uF, 47uF, and 47uF, respectively.

[0033] The working principle of this application is as follows: When the manhole cover is subjected to a certain pressure, the pressure-sensitive switch S1 connects the power supply BT, and the circuit begins to work. The power supply BT charges capacitor C3 through diode D2 and resistor R2, and charges capacitor C1 through the range resistors R7, R8, or R9 (different charging times can be set by selecting different range resistors R7, R8, or R9). Since the voltage across capacitor C3 cannot change abruptly, the second pin of the NE555 delay module initially shows a low voltage, and the third pin of the NE555 outputs a high voltage. At this time, the base potential of transistor Q1 is higher than the emitter potential, so Q1 cannot conduct. Therefore, transistor Q2 also cannot conduct, and capacitor C3 cannot discharge.

[0034] After capacitor C1 has been charged for a long time, the voltage of the sixth pin of the NE555 delay module is higher than 2 / 3 of the power supply voltage. At this time, the potential of the second pin is already higher than 2 / 3 of the power supply voltage. The potential of the third pin of the NE555 delay module flips, and the output is a low voltage, so the alarm circuit can work. The delay time can be selected by switch S as 60 minutes, 120 minutes or 240 minutes. Switching to the R7 side results in a 60-minute delay, switching to the R8 side results in a 120-minute delay, and switching to the R9 side results in a 240-minute delay.

[0035] The NE555 delay module starts working because the third pin outputs a low voltage. If the manhole cover is continuously pressed, causing the switch to remain closed, the alarm will continue indefinitely. Although the voltage of capacitor C1 becomes low due to the discharge of the seventh pin of the NE555 delay module, the second pin of the NE555 delay module does not discharge, so the state of the third pin of the NE555 delay module remains unchanged. When the foreign object on the top of the manhole cover is removed, the pressure is no longer applied, causing the contact switch S1 to close. The emitter potential of transistor Q1 will be higher than the base potential. At this time, transistor Q2 conducts because Q1 is conducting. Transistors Q1, Q2, and resistor R1 discharge capacitor C3. The larger the resistor R1, the slower C3 discharges. When R1 is 10K ohms, it takes about 10 seconds for C3 to discharge to below 1 / 3 of the power supply voltage. Therefore, if more than 10 seconds have passed since the foreign object was removed from the manhole cover, applying pressure again will not trigger the alarm, and the delay circuit will restart the timing. If less than 10 seconds have passed and C3 has not discharged to below 1 / 3 of the power supply voltage, the alarm circuit will be retried.

[0036] Alarm circuit working principle: When the emitter potentials of transistors Q3 and Q4 are low, one of them will conduct first. If transistor Q3 conducts first, its collector becomes low. The voltage across capacitor C4 cannot change abruptly, resulting in a low base voltage for transistor Q4, preventing it from conducting. Consequently, the LED alarm light does not illuminate. Power supply BT charges capacitor C4 through resistor R4. Once C4 is fully charged, it turns on transistor Q4, causing its collector to become low. The voltage across capacitor C5 cannot change abruptly, causing a low base voltage for transistor Q3, cutting it off. Power supply BT then charges capacitor C5 through resistor R5. When capacitor C5 is fully charged, transistor Q3 will conduct again, while transistor Q4 will be cut off. The above charging and discharging process will be repeated continuously to achieve the effect of flashing the LED alarm light; after the third pin of the NE555 delay module outputs a low voltage, current flows through the communication module line, transmitting the alarm signal to the system backend to prompt the alarm.

[0037] The above embodiments are merely preferred technical solutions of this utility model and should not be considered as limitations on this utility model. The embodiments and features described in this application can be arbitrarily combined without conflict. The protection scope of this utility model should be defined as the technical solution described in the claims, including equivalent substitutions of the technical features described in the claims. That is, equivalent substitutions and improvements within this scope are also within the protection scope of this utility model.

Claims

1. An alarm device for manhole covers subjected to prolonged pressure, comprising a power supply BT, characterized in that, The power supply BT supplies power to the delay circuit, the NE555 delay module, and the alarm deactivation circuit via a pressure-sensitive switch S1. The output of the delay circuit is connected to the NE555 delay module, and the output of the NE555 delay module is connected to the alarm deactivation circuit and the alarm circuit. The delay circuit and the NE555 delay module are used for time control. When the pressure on the manhole cover reaches the set time, the alarm circuit is triggered to sound an alarm. The alarm deactivation circuit is used to change the output voltage of the NE555 delay module to deactivate the alarm circuit when the pressure on the manhole cover is released and the pressure-sensitive switch is opened. The delay circuit includes a stop resistor. One end of the stop resistor is connected to the positive terminal of the power supply BT via the pressure-sensitive switch S1, and the other end of the stop resistor is connected to the first terminal of capacitor C1. The second terminal of capacitor C1 is connected to the negative terminal of the power supply BT, and the first terminal of capacitor C1 is connected to the sixth and seventh pins of the NE555 delay module.

2. The alarm device for long-term pressure on manhole covers according to claim 1, characterized in that, The resistors are configured with three levels: a first level resistor R7, a second level resistor R8, and a third level resistor R9. The resistance of the first level resistor R7 is less than that of the second level resistor R8, and the resistance of the second level resistor R8 is less than that of the third level resistor R9. The first terminal of the capacitor C1 is connected to the first level resistor R7, the second level resistor R8, or the third level resistor R9 through a switching switch S2.

3. The alarm device for long-term pressure on manhole covers according to claim 1, characterized in that, The second terminal of capacitor C1 is grounded.

4. An alarm device for long-term pressure on manhole covers according to claim 1, characterized in that, The first pin of the NE555 delay module is grounded, the second pin is connected to the alarm cancellation circuit, the third pin is connected to the alarm circuit, the fifth pin is connected to the first end of capacitor C2, the second end of capacitor C2 is grounded, the sixth and seventh pins are connected to the delay circuit, and the eighth pin is connected to the pressure switch S1.

5. An alarm device for long-term pressure on manhole covers according to claim 1, characterized in that, The alarm deactivation circuit includes diodes D1 and D2. The anode of diode D2 is connected to the pressure-sensitive switch S1. The cathode of diode D2 is connected in sequence to resistor R2 and the first terminal of capacitor C3. The second terminal of capacitor C3 is grounded. The first terminal of capacitor C3 is also connected to the emitter of transistor Q1 and the NE555 delay module. The base of transistor Q1 is connected to the cathode of diode D1. The collector of transistor Q1 is connected to the collector of transistor Q2. The anode of diode D1 is connected to the pressure-sensitive switch S1. The emitter of transistor Q2 is grounded.

6. An alarm device for long-term pressure on manhole covers according to claim 5, characterized in that, A resistor R1 is provided between the emitter of transistor Q2 and ground.

7. An alarm device for long-term pressure on manhole covers according to claim 1, characterized in that, The alarm circuit includes transistors Q3 and Q4, capacitors C4 and C5, resistors R3, R4, and R5, and LED L1. The positive terminal of LED L1 is connected to the same end of resistors R3, R4, R5, and R6. The other end of resistor R6 is grounded. The other ends of resistors R3 and R4 are connected to the first and second ends of capacitor C4, respectively. The negative terminal of LED L1 and resistor R5 are connected to the first and second ends of capacitor C5, respectively. The first end of capacitor C4 is connected to the collector of transistor Q3. The base of transistor Q3 is connected to the second end of capacitor C5. The second end of capacitor C4 is connected to the base of transistor Q4. The emitters of transistors Q3 and Q4 are connected to the NE555 delay module.

8. An alarm device for long-term pressure on manhole covers according to claim 7, characterized in that, The alarm circuit also includes a communication module. One end of the communication module is grounded through diode D3, with the negative terminal of diode D3 connected to the communication module and the positive terminal grounded. The other end of the communication module is connected to the NE555 delay module through diode D5, with the negative terminal of diode D5 connected to the NE555 delay module.

9. An alarm device for long-term pressure on manhole covers according to claim 8, characterized in that, A bypass circuit is provided on one side of the communication module. A diode D4 is installed on the bypass circuit. The negative terminal of diode D4 is connected to the negative terminal of diode D3. Resistor R6 is grounded through Zener diode V1.

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