Pressure-sensor-based device start-stop control system

Abstract

The utility model provides a kind of equipment start-stop control system based on pressure sensing belongs to electronic circuit control technical field.It includes: pressure sensor, for measuring pressure and converting pressure signal into voltage signal;Operational amplifier, for obtaining the voltage signal, output amplified voltage signal;Voltage comparator, the opposite input end of the voltage comparator is connected adjustable reference voltage, same direction input end is connected operational amplifier, for obtaining the amplified voltage signal and comparing with adjustable reference voltage, according to the output high level or low level of comparison result;Relay, for controlling the on-off of load circuit according to the output result of voltage comparator, according to the on-off conversion of load circuit to execute the state of equipment.The advantage is that: operational amplifier, cooperate feedback resistance and input resistance adjustable gain mechanism, ensure that weak pressure signal is amplified stably, eliminate the contact sticking problem of relay caused by insufficient electromagnetic force under the condition of under-voltage working condition from source.

Description

Technical Field

[0001] This utility model belongs to the field of electronic circuit control technology, specifically relating to a device start-stop control system based on pressure sensing. Background Technology

[0002] Pressure sensors are among the most commonly used sensors in industrial practice, widely applied in various industrial automation environments, including water conservancy and hydropower, railway transportation, power, machine tools, and pipelines. Currently, commonly used load-limiting equipment employs pressure sensors and relays as pressure control switches. The principle is that when the pressure sensor detects that the pressure has reached a specific value, it energizes the relay, closing the switch.

[0003] However, pressure sensors transmit data linearly, and when undervoltage occurs, the current continuously powers the relay. When the voltage is lower than the relay's rated value, the contacts may fail to release properly due to insufficient electromagnetic force, resulting in a persistently engaged state. This situation can easily lead to short circuits or abnormal equipment operation. Utility Model Content

[0004] The technical problem to be solved by this utility model is that the data transmitted by the pressure sensor is linear, and the current continuously powers the relay when the pressure is low. In view of the shortcomings of the prior art, this utility model provides a device start-stop control system based on pressure sensing.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by this utility model is as follows:

[0006] The system includes: a pressure sensor for measuring pressure and converting the pressure signal into a voltage signal; an operational amplifier, with the output of the pressure sensor connected to the input of the operational amplifier, for acquiring the voltage signal and outputting an amplified voltage signal; a voltage comparator, with its inverting input connected to an adjustable reference voltage and its non-inverting input connected to the operational amplifier, for acquiring the amplified voltage signal and comparing it with the adjustable reference voltage, and outputting a high or low level based on the comparison result; an actuator for switching on / off states based on the output of the voltage comparator; a relay, with a control circuit connected to the output of the voltage comparator and a load circuit connected to the actuator, for controlling the on / off state of the load circuit based on the output of the voltage comparator, and switching the state of the actuator based on the on / off state of the load circuit; and a DC power supply for supplying power to the system.

[0007] Furthermore, the pressure sensor is a resistance strain gauge pressure sensor, forming a Wheatstone bridge circuit, with its differential output terminal connected to the input pin of an operational amplifier.

[0008] Furthermore, it also includes an input resistor and a feedback resistor connected to the operational amplifier, which includes an LM324 chip and is configured as a non-inverting amplifier circuit, with the amplification factor determined by the ratio of the input resistor and the feedback resistor.

[0009] Furthermore, the voltage comparator includes an adjustable resistor and an LM339 chip. The adjustable resistor is connected to the inverting input of the LM339 chip, and the output of the LM339 chip is connected to a DC power supply through a pull-up resistor. The reference voltage at the inverting input is generated by voltage division by the adjustable resistor.

[0010] Furthermore, the adjustable reference voltage generation circuit includes an adjustable resistor connected in series between the DC power supply and ground, whose sliding end outputs a reference voltage to the inverting input of a voltage comparator.

[0011] Furthermore, a driving transistor is connected in series between the control coil of the relay and the output terminal of the voltage comparator. The base of the transistor is connected to the output terminal of the comparator through a current-limiting resistor, the collector drives the relay coil, and the emitter is grounded.

[0012] Furthermore, it also includes a status indication circuit: a running indicator light is connected in parallel across the control coil of the relay, and a standby indicator light is connected in series at the output of the voltage comparator.

[0013] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0014] 1. The operational amplifier adopts a non-inverting proportional amplifier circuit, combined with an adjustable gain mechanism of feedback resistor and input resistor, to ensure that weak pressure signals are stably amplified, eliminating the problem of contact sticking caused by insufficient electromagnetic force of relay under under-voltage conditions; the voltage comparator introduces an adjustable resistor to divide the voltage and generate a reference voltage, changing the output result of the pressure sensor from linear to two results: on and off. The output result is used to power the relay, realizing electrical isolation of the signal transmission link, effectively suppressing the interference of power fluctuations on the control logic, and significantly reducing the failure rate of abnormal start-up and shutdown of equipment.

[0015] 2. Through the collaborative design of the resistance strain gauge pressure sensor and the Wheatstone bridge, the accuracy of pressure signal acquisition and linear response characteristics are effectively enhanced, avoiding threshold misjudgment caused by signal drift. The adjustable reference voltage module supports flexible adjustment of the pressure trigger threshold, enabling the system to adapt to the needs of different load scenarios and greatly improving deployment convenience.

[0016] 3. The status indicator circuit uses a dual-lamp design to intuitively reflect the equipment's operating status: the running indicator LED1 is directly connected in parallel across the relay coil to display the power-on status of the executing equipment in real time; the standby indicator LED2 is connected in series at the comparator output to clearly indicate the standby condition when the pressure has not reached the threshold. Attached Figure Description

[0017] The present invention will now be described in further detail with reference to the accompanying drawings.

[0018] Figure 1 : A flowchart of this utility model;

[0019] Figure 2 : A schematic diagram of the circuit structure in this utility model.

[0020] Among them, 1. Pressure sensor; 2. Operational amplifier; 3. Voltage comparator; 4. Relay; 5. DC power supply; 6. Actuating device; R1, Input resistor; R2, Feedback resistor; R3, Pull-up resistor; R4, Current limiting resistor; RP1, Adjustable resistor; Q1, Transistor; LED1, Run indicator; LED2, Standby indicator. Detailed Implementation

[0021] To better understand this utility model, the following embodiments further illustrate its content, but the scope of protection of this utility model is not limited to the embodiments described below. Numerous specific details are set forth in the following description to provide a more thorough understanding of this utility model. However, it will be apparent to those skilled in the art that this utility model can be practiced without one or more of these details.

[0022] Example 1: See Figure 1-2 This embodiment of a pressure-sensing-based equipment start-stop control system includes:

[0023] Pressure sensor 1 is used to measure pressure and convert the pressure signal into a voltage signal;

[0024] The output terminal of the operational amplifier 2 and the pressure sensor 1 are connected to the positive input terminal of the operational amplifier 2 through a shielded wire. The shielded wire ensures that the weak voltage signal is transmitted without interference, which is used to acquire the voltage signal and output the amplified voltage signal.

[0025] Voltage comparator 3 has its inverting input connected to an adjustable reference voltage generation module and its non-inverting input connected to operational amplifier 2. The output pin of operational amplifier 2 is directly connected to the non-inverting input of voltage comparator 3 via a circuit board trace. This is used to obtain the amplified voltage signal and compare it with the adjustable reference voltage. Based on the comparison result, a high or low level is output.

[0026] The actuator 6 switches between start and stop states based on the output of the voltage comparator 3. The actuator can be one or more of an electric motor, a hydraulic pump, or a solenoid valve, either individually or in combination.

[0027] Relay 4, the control circuit is connected to the output of the voltage comparator, the load circuit is connected to the execution device, the normally open contact of relay 4 is connected in series on the metal terminal block, the power supply live wire of execution device 6 passes through the terminal block, and is used to control the on and off of the load circuit according to the output result of voltage comparator 3, and switch the state of execution device 6 according to the on and off of the load circuit.

[0028] DC power supply 5 is used to power the system and provides isolation voltage to each module through the power distribution unit. The sensors and operational amplifiers share a low-noise power supply branch, while the relays and actuators share a high-power branch.

[0029] See Figure 2 Pressure sensor 1 is a resistance strain gauge pressure sensor, which forms a Wheatstone bridge circuit. Its differential output terminal is connected to the input pin of operational amplifier 2. The resistance strain gauge pressure sensor detects mechanical pressure and converts it into a differential voltage signal through the Wheatstone bridge circuit. The working process is as follows: pressure input → sensor physical deformation → bridge circuit imbalance → generation of original voltage signal → input to the input terminal of operational amplifier.

[0030] See Figure 2 It also includes an input resistor R1 and a feedback resistor R2 connected in series with the operational amplifier. The operational amplifier 2 includes an LM324 chip and is configured as a non-inverting proportional amplifier circuit. The amplification factor is determined by the ratio of the input resistor R1 and the feedback resistor R2.

[0031] The input resistor R1 is a low-temperature drift metal film resistor, soldered to the inverting input pin 2 of the chip. The feedback resistor R2 is a resistor of the same specification, connected between the inverting input pin 2 and the output pin 1. The amplification factor is set by the physical resistance ratio of R1 / R2, and the gain is adjusted by changing different resistor values. A ceramic decoupling capacitor is connected in parallel at the chip's power supply pin to suppress power supply ripple. The working process is as follows: receive differential voltage signal → linearly amplify the signal → output stable amplified signal → input voltage comparator non-inverting input.

[0032] See Figure 2 Voltage comparator 3 includes an LM339 chip, whose output is connected to DC power supply 5 via pull-up resistor R3;

[0033] The adjustable reference voltage generation module includes: an adjustable resistor RP1 connected in series between the DC power supply 5 and ground. This adjustable resistor is a multi-turn precision potentiometer. Its sliding terminal outputs a reference voltage to the inverting input terminal (pin 4) of the voltage comparator 3. The reference voltage at the inverting input terminal is generated by voltage division by the adjustable resistor RP1.

[0034] The non-inverting input (pin 5) of the LM339 chip is connected to the output of operational amplifier 2 via gold-plated contacts. The output (pin 2) is connected to the positive power supply via pull-up resistor R3. The resistance value of R3 ensures that the comparator output logic level is compatible with subsequent driver circuits. The standby indicator LED2 is connected in series between the output and ground, and is equipped with a current-limiting resistor to prevent overcurrent.

[0035] Judgment logic:

[0036] Amplified signal voltage > reference voltage → output high level;

[0037] Amplified signal voltage < reference voltage → output low level.

[0038] See Figure 2 It also includes a status indication circuit: a running indicator LED1 is connected in parallel across the control coil of relay 4. The running indicator LED1 is a high-brightness red LED. A standby indicator LED2 is connected in series across the output of voltage comparator 3. The standby indicator LED2 is a green LED.

[0039] Technical effects of this embodiment:

[0040] 1. The operational amplifier adopts a non-inverting proportional amplifier circuit, combined with an adjustable gain mechanism of feedback resistor and input resistor, to ensure that weak pressure signals are stably amplified, eliminating the problem of contact sticking caused by insufficient electromagnetic force of relay under under-voltage conditions; the voltage comparator introduces an adjustable resistor to divide the voltage and generate a reference voltage, changing the output result of the pressure sensor from linear to two results: on and off. The output result is used to power the relay, realizing electrical isolation of the signal transmission link, effectively suppressing the interference of power fluctuations on the control logic, and significantly reducing the failure rate of abnormal start-up and shutdown of equipment.

[0041] 2. Through the collaborative design of the resistance strain gauge pressure sensor and the Wheatstone bridge, the accuracy of pressure signal acquisition and linear response characteristics are effectively enhanced, avoiding threshold misjudgment caused by signal drift. The adjustable reference voltage module supports flexible adjustment of the pressure trigger threshold, enabling the system to adapt to the needs of different load scenarios and greatly improving deployment convenience.

[0042] 3. The status indicator circuit uses a dual-lamp design to intuitively reflect the equipment's operating status: the running indicator LED1 is directly connected in parallel across the relay coil to display the power-on status of the executing equipment in real time; the standby indicator LED2 is connected in series at the comparator output to clearly indicate the standby condition when the pressure has not reached the threshold.

[0043] Example 2: See Figure 1-2According to Embodiment 1, a pressure-sensing-based device start-stop control system is provided. A driving transistor Q1 is connected in series between the control coil of relay 4 and the output terminal of voltage comparator 3. The driving transistor Q1 is an NPN power transistor. The base of transistor Q1 is connected to the comparator output terminal through a current-limiting resistor R4. The collector is connected to the positive terminal of relay 4 coil to drive the relay coil. The emitter is connected to the power supply ground.

[0044] Workflow:

[0045] High-level drive: When the voltage comparator detects that the pressure exceeds the threshold, it outputs a high-level signal. Current is injected into the base of the transistor through the current-limiting resistor (R4). At this time, the transistor Q1 is saturated and turned on (collector-emitter path is established), the relay coil is energized, the contacts close, and the device is powered on and put into operation.

[0046] Low-level shutdown: When the pressure is below the threshold, the comparator outputs a low level, the base current of transistor Q1 returns to zero; transistor Q1 is cut off (collector-emitter circuit is open); the relay coil is de-energized, the contacts release and disconnect the power supply to the actuator.

[0047] Technical effects of this embodiment

[0048] The transistor's hard-switching characteristics ensure that the relay coil is completely de-energized when the voltage is low. Combined with a voltage comparator, dual circuit isolation is provided to eliminate the risk that insufficient electromagnetic force will prevent the contacts from releasing when the relay is undervoltage.

[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of this utility model and are not intended to limit it. Any other modifications or equivalent substitutions made by those skilled in the art to the technical solution of this utility model, as long as they do not depart from the spirit and scope of the technical solution of this utility model, should be covered within the scope of the claims of this utility model.

[0050] The above are merely preferred embodiments of this utility model and are not intended to limit the scope of this utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A pressure-sensing-based equipment start-stop control system, characterized in that, include: Pressure sensor (1) is used to measure pressure and convert the pressure signal into a voltage signal; Operational amplifier (2), the output terminal of the pressure sensor (1) is connected to the input terminal of the operational amplifier (2) to acquire the voltage signal and output the amplified voltage signal; Voltage comparator (3), the inverting input terminal of the voltage comparator (3) is connected to an adjustable reference voltage, and the non-inverting input terminal is connected to an operational amplifier (2), used to obtain the amplified voltage signal and compare it with the adjustable reference voltage, and output a high level or a low level according to the comparison result; The execution device (6) switches between start and stop states based on the output of the voltage comparator (3); The relay (4) is connected to the output of the voltage comparator (3) via a control circuit and to the execution device (6) via a load circuit. It is used to control the on / off state of the load circuit based on the output of the voltage comparator (3) and to switch the state of the execution device (6) based on the on / off state of the load circuit. DC power supply (5) is used to power the system.

2. The pressure-sensing-based equipment start-stop control system as described in claim 1, characterized in that, The pressure sensor (1) is a resistance strain gauge pressure sensor, which forms a Wheatstone bridge circuit, and its differential output terminal is connected to the input pin of the operational amplifier (2).

3. The pressure-sensing-based equipment start-stop control system as described in claim 1, characterized in that, It also includes an input resistor (R1) and a feedback resistor (R2) connected to the operational amplifier (2), which includes an LM324 chip and is configured as a non-inverting amplifier circuit, the amplification factor being determined by the ratio of the input resistor (R1) and the feedback resistor (R2).

4. The pressure-sensing-based equipment start-stop control system as described in claim 1, characterized in that, The voltage comparator (3) includes an adjustable resistor (RP1) and an LM339 chip. The adjustable resistor (RP1) is connected to the inverting input terminal of the LM339 chip. The output terminal of the LM339 chip is connected to the DC power supply (5) through a pull-up resistor (R3). The reference voltage of the inverting input terminal is generated by voltage division of the adjustable resistor (RP1).

5. The pressure-sensing-based equipment start-stop control system as described in claim 4, characterized in that, The adjustable reference voltage generation circuit includes an adjustable resistor (RP1) connected in series between the DC power supply (5) and ground, whose sliding end outputs the reference voltage to the inverting input of the voltage comparator (3).

6. The pressure-sensing-based equipment start-stop control system as described in claim 1, characterized in that, A driving transistor (Q1) is connected in series between the control coil of the relay (4) and the output terminal of the voltage comparator (3). The base of the transistor (Q1) is connected to the output terminal of the comparator through a current-limiting resistor (R4). The collector drives the relay coil, and the emitter is grounded.

7. The pressure-sensing-based equipment start-stop control system as described in claim 1, characterized in that, It also includes a status indication circuit: a running indicator (LED1) is connected in parallel across the control coil of the relay (4), and a standby indicator (LED2) is connected in series at the output of the voltage comparator (3).

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