An inductive sensor for underwater detection

Abstract

The invention relates to the technical field of inductive sensors, in particular to an inductive sensor for underwater detection. The sensor sensing surface and the front shell and the rear shell are combined into a whole, which can effectively prevent other substances such as oil and water from penetrating from the sensing surface. The tail adopts a waterproof joint design, and the front shell and the rear shell are integrally processed with 316 stainless steel, which has excellent IP protection and acid and alkali corrosion resistance. The LC oscillation circuit sends an oscillation signal to an integration circuit, and the integration circuit integrates the continuous sine wave generated by the oscillation circuit, and then outputs it to the reverse end of an operational amplifier IC1A of an amplification processing circuit, and compares it with the threshold setting value of the same direction end of the operational amplifier IC1A of the amplification processing circuit, so as to control the output of the corresponding current conduction circuit, so that the output end line is turned on to obtain the corresponding current value, and the corresponding distance value is obtained by the external PLC control. The detection distance attenuation of the aluminum alloy material is smaller than that of the traditional inductive sensor, and the detection distance is far.

Description

Technical Field

[0001] The present invention relates to the technical field of inductive sensors, and in particular to an inductive sensor for underwater detection. Background Art

[0002] Inductive sensor is a position sensor with switch output. It consists of LC high-frequency oscillator and amplification processing circuit. When a metal object approaches the oscillating sensing head that can generate an alternating electromagnetic field, eddy current is generated inside the object. This eddy current reacts to the inductive sensor, causing the oscillation ability of the inductive sensor to decay and the parameters of the internal circuit to change, thereby identifying whether a metal object is approaching, and then controlling the on or off of the switch. It can detect whether an object is approaching within a certain distance (several millimeters to tens of millimeters). When the object approaches it to the set distance, an "action" signal can be sent. It is widely used in machine tools, metallurgy, chemical industry, textile and printing industries, and can be used as travel limit, product counting of production lines and other applications in automatic control systems. Inductive sensors do not contact the object being measured, do not produce mechanical wear and fatigue damage, have a long working life, fast response, no contacts, no sparks, no noise, moisture-proof, dust-proof, explosion-proof performance, strong output signal load capacity, safe and reliable.

[0003] Currently in the inductive sensor industry, the sensors as a whole cannot meet the requirements of long-term stable operation at 500 meters underwater, and the detection distance attenuation of aluminum alloy materials is large and the detection distance is short. Summary of the invention

[0004] The purpose of the present invention is to provide an inductive sensor for underwater detection, which can realize real-time monitoring of the state of the opening and closing coils without powering off the circuit breaker, so as to solve the problems raised in the above-mentioned background technology.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] An inductive sensor for underwater detection, comprising:

[0007] A front shell, one side of the front shell is connected to a rear shell by bolts, a circuit board assembly is installed inside the front shell and the rear shell, the circuit board assembly includes a circuit board and an electromagnetic coil welded on the circuit board, a sensor circuit is arranged on the circuit board, the sensor circuit includes an LC oscillation circuit, an integration circuit, an amplification processing circuit and an output control circuit, and the front shell and the rear shell are respectively made of 316 stainless steel and integrally processed;

[0008] A waterproof plug is connected to the bottom of the rear shell, and the waterproof plug is connected to the circuit board assembly through a wire.

[0009] Preferably, the LC oscillation circuit is composed of an oscillation inductor L1, a first oscillation capacitor C1, a second oscillation capacitor C2, a first resistor R1, a first PNP transistor T1A, a second resistor R2, a third adjustable resistor R3, a seventh resistor R7, a first PNP transistor T1B, a sixth resistor R6, a second switch diode T2A and a second switch diode T2B; the input end of the oscillation inductor L1, the input end of the first oscillation capacitor C1, and the input end of the seventh resistor R7 are electrically connected to a power supply VCC, the output end of the first oscillation capacitor C1 is electrically connected to the input end of the second oscillation capacitor C2, the output end of the oscillation inductor L1 is electrically connected to the output end of the second oscillation capacitor C2 and the input end of the first resistor R1, and the output end of the first resistor R1 is electrically connected to the emitter of the first PNP transistor T1A. The base of the first PNP transistor T1A is electrically connected to the collector of the first PNP transistor T1A, the base of the first PNP transistor T1B, and the input end of the second resistor R2, the output end of the second resistor R2 is grounded, the output end of the first oscillation capacitor C1 is electrically connected to the output end of the second oscillation capacitor C2 and the input end of the third adjustable resistor R3, the output end of the third adjustable resistor R3 is electrically connected to the output end of the seventh resistor R7 and the emitter of the first PNP transistor T1B, the collector of the first PNP transistor T1B is electrically connected to the input end of the sixth resistor R6 and the input end of the integration circuit, the output end of the sixth resistor R6 is electrically connected to the cathode of the second switch diode T2A and the anode of the second switch diode T2B, and the anode of the second switch diode T2A and the cathode of the second switch diode T2B are grounded.

[0010] Preferably, a temperature compensation circuit is provided in the LC oscillation circuit, and the temperature compensation circuit is composed of a fifth resistor R5 and a fourth thermistor R4; the output end of the first oscillation capacitor C1 and the input end of the second oscillation capacitor C2 are electrically connected to the fifth resistor R5 and the input end of the fourth thermistor R4, and the output end of the fifth resistor R5 is electrically connected to the output end of the fourth thermistor R4 and the input end of the third adjustable resistor R3.

[0011] Preferably, the integration circuit is composed of a third capacitor C3 and an eighth resistor R8; the input end of the third capacitor C3 is electrically connected to the input end of the eighth resistor R8, the collector of the first PNP transistor T1B of the LC oscillation circuit, and the input end of the sixth resistor R6, the output end of the third capacitor C3 is grounded, and the output end of the eighth resistor R8 is electrically connected to the input end of the amplification processing circuit.

[0012] Preferably, the amplification processing circuit is composed of a ninth resistor R9, a tenth resistor R10, a fourth capacitor C4, an operational amplifier IC1, a twelfth resistor R12, a thirteenth resistor R13A, a thirteenth resistor R13B, a light emitting diode D1 and an eighteenth resistor R18; the input end of the ninth resistor R9 is electrically connected to the power supply VCC, the output end of the ninth resistor R9 is electrically connected to the input end of the tenth resistor R10, the input end of the fourth capacitor C4, the same-direction input end of the operational amplifier IC1A, the same-direction input end of the operational amplifier IC1B, the input end of the twelfth resistor R12, the reverse input end of the operational amplifier IC1A is electrically connected to the output end of the eighth resistor R8 of the integration circuit, and the reverse input end of the operational amplifier IC1A is electrically connected to the output end of the eighth resistor R8 of the integration circuit. The output end is electrically connected to the output end of the tenth resistor R10, the output end of the fourth capacitor C4, the reverse input end of the operational amplifier IC1B, and the input end of the thirteenth resistor R13A; the 8th pin of the operational amplifier IC1 is electrically connected to the power supply VCC, the 4th pin of the operational amplifier IC1 is grounded, the output end of the operational amplifier IC1B is electrically connected to the input end of the thirteenth resistor R13B, the output end of the thirteenth resistor R13B is electrically connected to the output end of the thirteenth resistor R13A and the positive electrode of the light-emitting diode D1; the negative electrode of the light-emitting diode D1 is electrically connected to the input end of the eighteenth resistor R18 and the input end of the output control circuit, and the output end of the eighteenth resistor R18 is grounded.

[0013] Preferably, the output control circuit includes a seventh NPN transistor T7, an eighth PNP transistor T8, a twenty-first resistor R21, a twenty-second resistor R22, a twenty-third resistor R23 and a fourth light-emitting diode D4; the base of the seventh transistor T7 is electrically connected to the cathode of the light-emitting diode D1 of the amplification processing circuit and the input end of the eighteenth resistor R18, the collector of the seventh NPN transistor T7 is electrically connected to the base of the eighth PNP transistor T8 and the input end of the twenty-first resistor R21, the emitter of the eighth PNP transistor T8 is electrically connected to the output end of the twenty-first resistor R21, the cathode of the fourth diode D4, and the signal output end C, and the anode of the fourth diode D4 is grounded; the collector of the eighth PNP transistor T8 is electrically connected to the emitter of the seventh NPN transistor T7 and the input end of the twenty-second resistor R22, the output end of the twenty-second resistor R22 is electrically connected to the input end of the twenty-third resistor R23, and the output end of the twenty-third resistor R23 is grounded.

[0014] Preferably, the sensor circuit further includes a power supply overvoltage protection circuit and a power supply voltage stabilization circuit;

[0015] The power supply overvoltage protection circuit is composed of a twenty-fourth resistor R24 ​​and a second voltage stabilizing diode D2; the input end of the twenty-fourth resistor R24 ​​is electrically connected to the power supply input end A, the output end of the twenty-fourth resistor R24 ​​is electrically connected to the cathode of the second voltage stabilizing diode D2 and the input end of the power supply voltage stabilizing circuit, and the anode of the second voltage stabilizing diode D2 is grounded;

[0016] The power supply voltage stabilization circuit is composed of an eighth capacitor C8, a nineteenth resistor R19, a fourth NPN transistor T4, a controllable precision voltage stabilization source T5, a sixteenth resistor R16, a seventeenth resistor R17 and a sixth capacitor C6; the input end of the eighth capacitor C8 is electrically connected to the input end of the nineteenth resistor R19, the collector of the fourth NPN transistor T4 and the output end of the twenty-fourth resistor R24 ​​of the power supply overvoltage protection circuit, and the negative electrode of the second voltage stabilizing diode D2; the output end of the nineteenth resistor R19 is electrically connected to the input end of the nineteenth resistor R19, the collector of the fourth NPN transistor T4 and the output end of the twenty-fourth resistor R24 ​​of the power supply overvoltage protection circuit, and the negative electrode of the second voltage stabilizing diode D2; the output end of the nineteenth resistor R19 is electrically connected to the To the base of the fourth NPN transistor T4 and the cathode of the controllable precision voltage-stabilizing source T5, the reference electrode of the controllable precision voltage-stabilizing source T5 is electrically connected to the output end of the sixteenth resistor R16 and the input end of the seventeenth resistor R17, the anode of the controllable precision voltage-stabilizing source T5 and the output end of the seventeenth resistor R17 are grounded, the input end of the sixteenth resistor R16, the emitter of the fourth NPN transistor and the input end of the sixth capacitor C6 are electrically connected to the power supply VCC, and the output end of the sixth capacitor C6 is grounded.

[0017] Preferably, the sensor circuit also includes a power-on protection circuit, which is composed of a third NPN transistor T3, a fourteenth resistor R14, a fifth capacitor C5 and a fifteenth resistor R15; the collector of the third NPN transistor T3 is electrically connected to the output end of the thirteenth resistor R13B of the amplification processing circuit, the output end of the thirteenth resistor R13A and the positive electrode of the light-emitting diode D1, the base of the third transistor T3 is electrically connected to the output end of the fourteenth resistor R14 and the input end of the fifteenth resistor R15, the emitter of the third transistor and the output end of the fifteenth resistor R15 are grounded, the input end of the fourteenth resistor is electrically connected to the output end of the fifth capacitor C5, and the input end of the fifth capacitor C5 is electrically connected to the power supply VCC.

[0018] Preferably, the sensor circuit also includes an output short-circuit overload protection circuit, which is composed of a sixth NPN transistor T6A, a sixth NPN transistor T6B, a twentieth resistor R20 and a seventh capacitor C7; the collector of the sixth NPN transistor T6A is electrically connected to the base of the sixth NPN transistor T6B, the cathode of the light-emitting diode D1 of the power-on protection circuit, the input end of the eighteenth resistor R18 and the base of the seventh transistor T7 of the output control circuit, and the The emitter of the sixth NPN transistor T6A is electrically connected to the output end of the twenty-second resistor R22 and the input end of the twenty-third resistor R23 of the output control circuit, the base of the sixth NPN transistor T6A is electrically connected to the input end of the twentieth resistor R20, the output end of the twentieth resistor R20 is electrically connected to the emitter of the sixth NPN transistor T6B and the input end of the seventh capacitor C7, the collector of the sixth NPN transistor T6B is suspended, and the output end of the seventh capacitor C7 is grounded.

[0019] Preferably, the sensor circuit also includes the power reverse protection circuit, which is composed of a third switching diode D3; the positive pole of the third switching diode D3 is connected to the positive pole of the fourth diode D4 of the output control circuit, and the negative pole of the third switching diode D3 is electrically connected to the power input terminal B.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The sensor sensing surface and the front shell and the rear shell of the inductive sensor for underwater detection provided by the embodiment of the present invention are combined into a whole, which can effectively prevent other substances such as oil and water from penetrating from the sensing surface. The tail adopts a waterproof joint design, and the front shell and the rear shell are made of 316 stainless steel in one piece, which has excellent IP protection and acid and alkali corrosion resistance. The sensor is not easily damaged in harsh environments. The all-metal shell is more resistant to mechanical forces, thus overcoming the weakness of traditional inductive sensors that are easily damaged by collisions, having higher impact resistance and wear resistance, and can work stably for a long time at 500 meters underwater. The overall water pressure resistance of the sensor is above 5MPa;

[0022] The power supply provided by the power supply voltage stabilizing circuit of the inductive sensor for underwater detection provided by the embodiment of the present invention provides a stable voltage for the LC oscillation circuit and the amplification processing circuit. The LC oscillation circuit sends the oscillation signal to the integration circuit, and the integration circuit integrates the continuous sine wave generated by the oscillation circuit, and then outputs it to the reverse end of the operational amplifier IC1A of the amplification processing circuit, and compares it with the threshold setting value of the same direction end of the operational amplifier IC1A of the amplification processing circuit, so as to control the output of the corresponding current conduction circuit, so that the output end line is turned on to obtain the corresponding current value, and the corresponding distance value is obtained by the external PLC control. The detection distance attenuation of the aluminum alloy material is smaller than that of the traditional inductive sensor, and the detection distance is far; the output is short-circuited or overloaded by the short-circuit overload protection circuit, and the stability of the output current and the stability of the LC oscillation are further guaranteed by the power supply voltage stabilizing circuit, thereby reducing the false detection or failure of the previous sensor due to long-distance detection, thereby improving the accuracy of sensor detection;

[0023] The inductive sensor for underwater detection provided in the embodiment of the present invention performs temperature compensation on the sensor through a temperature compensation circuit, thereby improving the temperature performance of the sensor, enabling it to be used normally in high and low temperature environments, and ensuring the accuracy of sensor detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A structural block diagram of an inductive sensor for underwater detection provided by an embodiment of the present invention;

[0025] Figure 2 A circuit diagram of a power supply unit, a closing and opening coil, and a voltage dividing unit of an inductive sensor for underwater detection provided by an embodiment of the present invention;

[0026] Figure 3 A structural block diagram of an inductive sensor for underwater detection provided by an embodiment of the present invention;

[0027] Figure 4 A circuit schematic diagram of an inductive sensor for underwater detection provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] Figure 1A structural block diagram of an inductive sensor for underwater detection provided by an embodiment of the present invention, Figure 2 The circuit diagram of the power supply unit, the opening and closing coil and the voltage dividing unit of the inductive sensor for underwater detection provided by the embodiment of the present invention. The embodiment of the present invention provides an inductive sensor for underwater detection, such as Figure 1 and Figure 2 As shown, the inductive sensor for underwater detection may include:

[0030] A front shell 1, one side of which is connected to a rear shell 2 by bolts, a circuit board assembly is installed inside the front shell 1 and the rear shell 2, the circuit board assembly includes a circuit board 3 and an electromagnetic coil 4 welded on the circuit board 3, a sensor circuit is arranged on the circuit board 4, the sensor circuit includes an LC oscillation circuit, an integration circuit, an amplification processing circuit and an output control circuit, and the front shell 1 and the rear shell 2 are respectively made of 316 stainless steel in one piece;

[0031] A waterproof plug 5 is connected to the bottom of the rear housing 2 , and the waterproof plug 5 is connected to the circuit board assembly through a wire.

[0032] The sensor sensing surface of the inductive sensor for underwater detection provided by the embodiment of the present invention is combined with the front shell 1 and the rear shell 2 as a whole, which can effectively prevent other substances such as oil and water from penetrating from the sensing surface. The tail adopts a waterproof joint 5 design, and the front shell and the rear shell are made of 316 stainless steel in one piece. It has excellent IP protection and acid and alkali corrosion resistance, and the sensor is not easily damaged in harsh environments. The all-metal shell is more resistant to mechanical forces, thereby overcoming the weakness of traditional inductive sensors that are easily damaged by collisions. It has higher impact resistance and wear resistance and can work stably for a long time at 500 meters underwater. The overall water pressure resistance of the sensor is above 5MPa.

[0033] like Figure 4As shown, in one embodiment of the present invention, the LC oscillation circuit is composed of an oscillation inductor L1, a first oscillation capacitor C1, a second oscillation capacitor C2, a first resistor R1, a first PNP transistor T1A, a second resistor R2, a third adjustable resistor R3, a seventh resistor R7, a first PNP transistor T1B, a sixth resistor R6, a second switch diode T2A and a second switch diode T2B; the input end of the oscillation inductor L1, the input end of the first oscillation capacitor C1, and the input end of the seventh resistor R7 are electrically connected to the power supply VCC, the output end of the first oscillation capacitor C1 is electrically connected to the input end of the second oscillation capacitor C2, the output end of the oscillation inductor L1 is electrically connected to the output end of the second oscillation capacitor C2 and the input end of the first resistor R1, the output end of the first resistor R1 is electrically connected to the emitter of the first PNP transistor T1A, the base of the first PNP transistor T1A is electrically connected to the collector of the first PNP transistor T1A, the base of the first PNP transistor T1B, and the input end of the second resistor R2, The output end of the second resistor R2 is grounded, the output end of the first oscillation capacitor C1 is electrically connected to the output end of the second oscillation capacitor C2 and the input end of the third adjustable resistor R3, the output end of the third adjustable resistor R3 is electrically connected to the output end of the seventh resistor R7 and the emitter of the first PNP transistor T1B, the collector of the first PNP transistor T1B is electrically connected to the input end of the sixth resistor R6 and the input end of the integration circuit, the output end of the sixth resistor R6 is electrically connected to the cathode of the second switch diode T2A and the anode of the second switch diode T2B, and the anode of the second switch diode T2A and the cathode of the second switch diode T2B are grounded.

[0034] Furthermore, a temperature compensation circuit is provided in the LC oscillation circuit, and the temperature compensation circuit is composed of a fifth resistor R5 and a fourth thermistor R4; the output end of the first oscillation capacitor C1 and the input end of the second oscillation capacitor C2 are electrically connected to the fifth resistor R5 and the input end of the fourth thermistor R4, and the output end of the fifth resistor R5 is electrically connected to the output end of the fourth thermistor R4 and the input end of the third adjustable resistor R3.

[0035] The inductive sensor for underwater detection provided in the embodiment of the present invention performs temperature compensation on the sensor through a temperature compensation circuit, thereby improving the temperature performance of the sensor, enabling it to be used normally in high and low temperature environments, and ensuring the accuracy of sensor detection.

[0036] like Figure 4 As shown, in one embodiment of the present invention, the integration circuit is composed of a third capacitor C3 and an eighth resistor R8; the input end of the third capacitor C3 is electrically connected to the input end of the eighth resistor R8, the collector of the first PNP transistor T1B of the LC oscillation circuit, and the input end of the sixth resistor R6, the output end of the third capacitor C3 is grounded, and the output end of the eighth resistor R8 is electrically connected to the input end of the amplification processing circuit.

[0037] like Figure 4 As shown, in one embodiment of the present invention, the amplification processing circuit is composed of a ninth resistor R9, a tenth resistor R10, a fourth capacitor C4, an operational amplifier IC1, a twelfth resistor R12, a thirteenth resistor R13A, a thirteenth resistor R13B, a light-emitting diode D1 and an eighteenth resistor R18; the input end of the ninth resistor R9 is electrically connected to the power supply VCC, the output end of the ninth resistor R9 is electrically connected to the input end of the tenth resistor R10, the input end of the fourth capacitor C4, the same-direction input end of the operational amplifier IC1A, the same-direction input end of the operational amplifier IC1B, the input end of the twelfth resistor R12, and the reverse input end of the operational amplifier IC1A is electrically connected to the eighth resistor R8 of the integration circuit. The output end of the operational amplifier IC1A is electrically connected to the output end of the tenth resistor R10, the output end of the fourth capacitor C4, the inverting input end of the operational amplifier IC1B, and the input end of the thirteenth resistor R13A; the 8th pin of the operational amplifier IC1 is electrically connected to the power supply VCC, the 4th pin of the operational amplifier IC1 is grounded, the output end of the operational amplifier IC1B is electrically connected to the input end of the thirteenth resistor R13B, the output end of the thirteenth resistor R13B is electrically connected to the output end of the thirteenth resistor R13A and the positive electrode of the light emitting diode D1; the negative electrode of the light emitting diode D1 is electrically connected to the input end of the eighteenth resistor R18 and the input end of the output control circuit, and the output end of the eighteenth resistor R18 is grounded.

[0038] like Figure 4 As shown, in one embodiment of the present invention, the output control circuit includes a seventh NPN transistor T7, an eighth PNP transistor T8, a twenty-first resistor R21, a twenty-second resistor R22, a twenty-third resistor R23 and a fourth light-emitting diode D4; the base of the seventh transistor T7 is electrically connected to the cathode of the light-emitting diode D1 of the amplification processing circuit and the input end of the eighteenth resistor R18, the collector of the seventh NPN transistor T7 is electrically connected to the base of the eighth PNP transistor T8 and the input end of the twenty-first resistor R21, the emitter of the eighth PNP transistor T8 is electrically connected to the output end of the twenty-first resistor R21, the cathode of the fourth diode D4, and the signal output end C, and the anode of the fourth diode D4 is grounded; the collector of the eighth PNP transistor T8 is electrically connected to the emitter of the seventh NPN transistor T7 and the input end of the twenty-second resistor R22, the output end of the twenty-second resistor R22 is electrically connected to the input end of the twenty-third resistor R23, and the output end of the twenty-third resistor R23 is grounded.

[0039] like Figure 4 As shown, in one embodiment of the present invention, the sensor circuit further includes a power supply overvoltage protection circuit and a power supply voltage stabilization circuit;

[0040] The power supply overvoltage protection circuit is composed of a twenty-fourth resistor R24 ​​and a second voltage stabilizing diode D2; the input end of the twenty-fourth resistor R24 ​​is electrically connected to the power supply input end A, the output end of the twenty-fourth resistor R24 ​​is electrically connected to the cathode of the second voltage stabilizing diode D2 and the input end of the power supply voltage stabilizing circuit, and the anode of the second voltage stabilizing diode D2 is grounded;

[0041] The power supply voltage stabilizing circuit is composed of an eighth capacitor C8, a nineteenth resistor R19, a fourth NPN transistor T4, a controllable precision voltage stabilizing source T5, a sixteenth resistor R16, a seventeenth resistor R17 and a sixth capacitor C6; the input end of the eighth capacitor C8 is electrically connected to the input end of the nineteenth resistor R19, the collector of the fourth NPN transistor T4 and the output end of the twenty-fourth resistor R24 ​​of the power supply overvoltage protection circuit, and the negative electrode of the second voltage stabilizing diode D2; the output end of the nineteenth resistor R19 is electrically connected to the base of the fourth NPN transistor T4 and the cathode of the controllable precision voltage stabilizing source T5, the reference electrode of the controllable precision voltage stabilizing source T5 is electrically connected to the output end of the sixteenth resistor R16 and the input end of the seventeenth resistor R17, the anode of the controllable precision voltage stabilizing source T5 and the output end of the seventeenth resistor R17 are grounded, the input end of the sixteenth resistor R16, the emitter of the fourth NPN transistor and the input end of the sixth capacitor C6 are electrically connected to the power supply VCC, and the output end of the sixth capacitor C6 is grounded.

[0042] like Figure 4 As shown, in one embodiment of the present invention, the sensor circuit also includes a power-on protection circuit, which is composed of a third NPN transistor T3, a fourteenth resistor R14, a fifth capacitor C5 and a fifteenth resistor R15; the collector of the third NPN transistor T3 is electrically connected to the output end of the thirteenth resistor R13B of the amplification processing circuit, the output end of the thirteenth resistor R13A and the positive electrode of the light-emitting diode D1, the base of the third transistor T3 is electrically connected to the output end of the fourteenth resistor R14 and the input end of the fifteenth resistor R15, the emitter of the third transistor and the output end of the fifteenth resistor R15 are grounded, the input end of the fourteenth resistor is electrically connected to the output end of the fifth capacitor C5, and the input end of the fifth capacitor C5 is electrically connected to the power supply VCC.

[0043] like Figure 4As shown, in one embodiment of the present invention, the sensor circuit also includes an output short-circuit overload protection circuit, which is composed of a sixth NPN transistor T6A, a sixth NPN transistor T6B, a twentieth resistor R20 and a seventh capacitor C7; the collector of the sixth NPN transistor T6A is electrically connected to the base of the sixth NPN transistor T6B, the negative electrode of the light-emitting diode D1 of the power-on protection circuit, the input end of the eighteenth resistor R18 and the base of the seventh transistor T7 of the output control circuit, the emitter of the sixth NPN transistor T6A is electrically connected to the output end of the twenty-second resistor R22 and the input end of the twenty-third resistor R23 of the output control circuit, the base of the sixth NPN transistor T6A is electrically connected to the input end of the twentieth resistor R20, the output end of the twentieth resistor R20 is electrically connected to the emitter of the sixth NPN transistor T6B and the input end of the seventh capacitor C7, the collector of the sixth NPN transistor T6B is suspended, and the output end of the seventh capacitor C7 is grounded.

[0044] The output is protected from short circuit or overload by the short-circuit overload protection circuit, and the stability of the output current and the stability of the LC oscillation are further guaranteed by the power supply voltage stabilization circuit, reducing the false detection or failure caused by long-distance detection of previous sensors, thereby improving the accuracy of sensor detection.

[0045] like Figure 4 As shown, in one embodiment of the present invention, the sensor circuit also includes a power reverse protection circuit, which is composed of a third switching diode D3; the positive pole of the third switching diode D3 is connected to the positive pole of the fourth diode D4 of the output control circuit, and the negative pole of the third switching diode D3 is electrically connected to the power input terminal B.

[0046] Working principle:

[0047] The inductive sensor for underwater detection provided by the embodiment of the present invention provides a stable voltage for the LC oscillation circuit and the amplification processing circuit through the power provided by the power supply voltage stabilization circuit. The LC oscillation circuit sends the oscillation signal to the integration circuit, and the integration circuit integrates the continuous sine wave generated by the oscillation circuit, and then outputs it to the reverse end of the operational amplifier IC1A of the amplification processing circuit, and compares it with the threshold setting value of the same direction end of the operational amplifier IC1A of the amplification processing circuit, thereby controlling the output of the corresponding current conduction circuit, so that the output end line is turned on to obtain the corresponding current value, and the corresponding distance value is obtained by the external PLC control. The detection distance attenuation of the aluminum alloy material is smaller than that of the traditional inductive sensor, and the detection distance is far; the output is short-circuited or overloaded by the short-circuit overload protection circuit, and the stability of the output current and the stability of the LC oscillation are further guaranteed by the power supply voltage stabilization circuit, thereby reducing the false detection or failure of the previous sensor due to long-distance detection, thereby improving the accuracy of the sensor detection; the sensor is temperature compensated by the temperature compensation circuit, thereby improving the temperature performance of the sensor, so that it can be used normally in high and low temperature environments, and the accuracy of the sensor detection is guaranteed.

[0048] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An inductive sensor for underwater detection, characterized in that: include: A front shell (1), one side of the front shell (1) being connected to a rear shell (2) by means of bolts, a circuit board assembly being installed inside the front shell (1) and the rear shell (2), the circuit board assembly comprising a circuit board (3) and an electromagnetic coil (4) welded to the circuit board (3), a sensor circuit being arranged on the circuit board (3), the sensor circuit comprising an LC oscillation circuit, an integration circuit, an amplification processing circuit and an output control circuit, the front shell (1) and the rear shell (2) being respectively integrally processed from 316 stainless steel; A waterproof plug (5), the waterproof plug (5) being connected to the bottom of the rear housing (2), the waterproof plug (5) being connected to the circuit board assembly via a wire; The LC oscillation circuit is composed of an oscillation inductor L1, a first oscillation capacitor C1, a second oscillation capacitor C2, a first resistor R1, a first PNP transistor T1A, a second resistor R2, a third adjustable resistor R3, a seventh resistor R7, a first PNP transistor T1B, a sixth resistor R6, a second switch diode T2A and a second switch diode T2B; the input end of the oscillation inductor L1, the input end of the first oscillation capacitor C1 and the input end of the seventh resistor R7 are electrically connected to a power supply VCC, the output end of the first oscillation capacitor C1 is electrically connected to the input end of the second oscillation capacitor C2, the output end of the oscillation inductor L1 is electrically connected to the output end of the second oscillation capacitor C2 and the input end of the first resistor R1, the output end of the first resistor R1 is electrically connected to the emitter of the first PNP transistor T1A, the base of the first PNP transistor T1A is electrically connected to the collector of the first PNP transistor T1A, the base of the first PNP transistor T1B and the input end of the second resistor R2, The output end of the second resistor R2 is grounded, the output end of the first oscillation capacitor C1 is electrically connected to the output end of the second oscillation capacitor C2 and the input end of the third adjustable resistor R3, the output end of the third adjustable resistor R3 is electrically connected to the output end of the seventh resistor R7 and the emitter of the first PNP transistor T1B, the collector of the first PNP transistor T1B is electrically connected to the input end of the sixth resistor R6 and the input end of the integration circuit, the output end of the sixth resistor R6 is electrically connected to the cathode of the second switch diode T2A and the anode of the second switch diode T2B, and the anode of the second switch diode T2A and the cathode of the second switch diode T2B are grounded; The LC oscillator circuit is provided with a temperature compensation circuit, which is composed of a fifth resistor R5 and a fourth thermistor R4; the output end of the first oscillation capacitor C1 and the input end of the second oscillation capacitor C2 are electrically connected to the fifth resistor R5 and the input end of the fourth thermistor R4, and the output end of the fifth resistor R5 is electrically connected to the output end of the fourth thermistor R4 and the input end of the third adjustable resistor R3; The integration circuit is composed of a third capacitor C3 and an eighth resistor R8; the input end of the third capacitor C3 is electrically connected to the input end of the eighth resistor R8, the collector of the first PNP transistor T1B of the LC oscillation circuit, and the input end of the sixth resistor R6; the output end of the third capacitor C3 is grounded, and the output end of the eighth resistor R8 is electrically connected to the input end of the amplification processing circuit; The amplification processing circuit is composed of a ninth resistor R9, a tenth resistor R10, a fourth capacitor C4, an operational amplifier IC1, a twelfth resistor R12, a thirteenth resistor R13A, a thirteenth resistor R13B, a light-emitting diode D1 and an eighteenth resistor R18; the input end of the ninth resistor R9 is electrically connected to the power supply VCC, the output end of the ninth resistor R9 is electrically connected to the input end of the tenth resistor R10, the input end of the fourth capacitor C4, the same-direction input end of the operational amplifier IC1A, the same-direction input end of the operational amplifier IC1B, the input end of the twelfth resistor R12, the reverse input end of the operational amplifier IC1A is electrically connected to the output end of the eighth resistor R8 of the integration circuit, and the output end of the operational amplifier IC1A is electrically connected to the output end of the eighth resistor R8 of the integration circuit. The pin 8 of the operational amplifier IC1 is electrically connected to the power supply VCC, the pin 4 of the operational amplifier IC1 is grounded, the output end of the operational amplifier IC1B is electrically connected to the input end of the thirteenth resistor R13B, the output end of the thirteenth resistor R13B is electrically connected to the output end of the thirteenth resistor R13A and the positive electrode of the light emitting diode D1; the negative electrode of the light emitting diode D1 is electrically connected to the input end of the eighteenth resistor R18 and the input end of the output control circuit, and the output end of the eighteenth resistor R18 is grounded.

2. The inductive sensor for underwater detection according to claim 1, characterized in that: The output control circuit includes a seventh NPN transistor T7, an eighth PNP transistor T8, a twenty-first resistor R21, a twenty-second resistor R22, a twenty-third resistor R23 and a fourth light-emitting diode D4; the base of the seventh NPN transistor T7 is electrically connected to the cathode of the light-emitting diode D1 of the amplification processing circuit and the input end of the eighteenth resistor R18, the collector of the seventh NPN transistor T7 is electrically connected to the base of the eighth PNP transistor T8 and the input end of the twenty-first resistor R21, the emitter of the eighth PNP transistor T8 is electrically connected to the output end of the twenty-first resistor R21, the cathode of the fourth light-emitting diode D4, and the signal output end C, and the anode of the fourth light-emitting diode D4 is grounded; the collector of the eighth PNP transistor T8 is electrically connected to the emitter of the seventh NPN transistor T7 and the input end of the twenty-second resistor R22, the output end of the twenty-second resistor R22 is electrically connected to the input end of the twenty-third resistor R23, and the output end of the twenty-third resistor R23 is grounded.

3. The inductive sensor for underwater detection according to claim 2, characterized in that: The sensor circuit also includes a power supply overvoltage protection circuit and a power supply voltage stabilization circuit; The power supply overvoltage protection circuit is composed of a twenty-fourth resistor R24 ​​and a second voltage stabilizing diode D2; the input end of the twenty-fourth resistor R24 ​​is electrically connected to the power supply input end A, the output end of the twenty-fourth resistor R24 ​​is electrically connected to the cathode of the second voltage stabilizing diode D2 and the input end of the power supply voltage stabilizing circuit, and the anode of the second voltage stabilizing diode D2 is grounded; The power supply voltage stabilization circuit is composed of an eighth capacitor C8, a nineteenth resistor R19, a fourth NPN transistor T4, a controllable precision voltage stabilization source T5, a sixteenth resistor R16, a seventeenth resistor R17 and a sixth capacitor C6; the input end of the eighth capacitor C8 is electrically connected to the input end of the nineteenth resistor R19, the collector of the fourth NPN transistor T4 and the output end of the twenty-fourth resistor R24 ​​of the power supply overvoltage protection circuit, and the negative electrode of the second voltage stabilizing diode D2; the output end of the nineteenth resistor R19 is electrically connected to the input end of the nineteenth resistor R19, the collector of the fourth NPN transistor T4 and the output end of the twenty-fourth resistor R24 ​​of the power supply overvoltage protection circuit, and the negative electrode of the second voltage stabilizing diode D2; the output end of the nineteenth resistor R19 is electrically connected to the To the base of the fourth NPN transistor T4 and the cathode of the controllable precision voltage-stabilizing source T5, the reference electrode of the controllable precision voltage-stabilizing source T5 is electrically connected to the output end of the sixteenth resistor R16 and the input end of the seventeenth resistor R17, the anode of the controllable precision voltage-stabilizing source T5 and the output end of the seventeenth resistor R17 are grounded, the input end of the sixteenth resistor R16, the emitter of the fourth NPN transistor and the input end of the sixth capacitor C6 are electrically connected to the power supply VCC, and the output end of the sixth capacitor C6 is grounded.

4. The inductive sensor for underwater detection according to claim 3, characterized in that: The sensor circuit also includes a power-on protection circuit, which is composed of a third NPN transistor T3, a fourteenth resistor R14, a fifth capacitor C5 and a fifteenth resistor R15; the collector of the third NPN transistor T3 is electrically connected to the output end of the thirteenth resistor R13B of the amplification processing circuit, the output end of the thirteenth resistor R13A and the positive electrode of the light-emitting diode D1, the base of the third NPN transistor T3 is electrically connected to the output end of the fourteenth resistor R14 and the input end of the fifteenth resistor R15, the emitter of the third NPN transistor T3 and the output end of the fifteenth resistor R15 are grounded, the input end of the fourteenth resistor is electrically connected to the output end of the fifth capacitor C5, and the input end of the fifth capacitor C5 is electrically connected to the power supply VCC.

5. The inductive sensor for underwater detection according to claim 4, characterized in that: The sensor circuit also includes an output short-circuit overload protection circuit, which is composed of a sixth NPN transistor T6A, a sixth NPN transistor T6B, a twentieth resistor R20 and a seventh capacitor C7; the collector of the sixth NPN transistor T6A is electrically connected to the base of the sixth NPN transistor T6B, the cathode of the light-emitting diode D1 of the power-on protection circuit, the input end of the eighteenth resistor R18 and the base of the seventh NPN transistor T7 of the output control circuit, and the cathode of the light-emitting diode D1 of the power-on protection circuit is electrically connected to the input end of the eighteenth resistor R18 and the base of the seventh NPN transistor T7 of the output control circuit. The emitter of the sixth NPN transistor T6A is electrically connected to the output end of the twenty-second resistor R22 and the input end of the twenty-third resistor R23 of the output control circuit, the base of the sixth NPN transistor T6A is electrically connected to the input end of the twentieth resistor R20, the output end of the twentieth resistor R20 is electrically connected to the emitter of the sixth NPN transistor T6B and the input end of the seventh capacitor C7, the collector of the sixth NPN transistor T6B is suspended, and the output end of the seventh capacitor C7 is grounded.

6. The inductive sensor for underwater detection according to claim 5, characterized in that: The sensor circuit also includes a power reverse protection circuit, which is composed of a third switching diode D3; the positive pole of the third switching diode D3 is connected to the positive pole of the fourth light-emitting diode D4 of the output control circuit, and the negative pole of the third switching diode D3 is electrically connected to the power input terminal B.

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