An abnormality detection circuit for an internal cooling fan of an instrument

Abstract

The utility model provides a kind of abnormal detection circuit of internal heat dissipation fan of instrument and apparatus, including fan interface P1, the anode of fan interface P1 is connected with 12V power supply, the cathode of fan interface P1 is connected with the second pin of resistance two R2 and the second pin of resistance three R3 respectively, the first pin of resistance two R2 is connected with the drain of MOS tube Q1, the source of MOS tube Q1 is grounded, the gate of MOS tube Q1 is connected with signal input end and the first pin of resistance one R1 respectively, the second pin of resistance one R1 is grounded, the first pin of resistance three R3 is connected with the second pin of fourth resistance R4 and differential circuit respectively, differential circuit first pin is grounded, differential circuit and differential amplifier circuit.The utility model has the following beneficial effects, the utility model's circuit is simple, the space of layout on circuit board is very small, almost does not affect the realization of normal function of product and layout can detect abnormal signal when fan occurs abnormality, to alarm in time.

Description

Technical Field

[0001] This utility model relates to an abnormal detection circuit for the internal cooling fan of an instrument, belonging to the technical field. Background Technology

[0002] Inside instruments, we often need to install cooling fans to dissipate heat from the various components inside. However, sometimes the fans may malfunction for various reasons. This requires us to issue an alarm signal when the fan malfunctions, so that the instrument operator can stop the instrument and troubleshoot the problem.

[0003] Currently, the main method for detecting fan malfunctions is to determine whether the fan is malfunctioning by detecting the temperature and the fan speed.

[0004] The above solution requires both various signals to detect the fan speed and temperature sensors to detect the device temperature. The circuitry is complex and occupies a large space. For instruments that already have high requirements for miniaturization and simplicity, this will undoubtedly increase the size and cost of the instruments, which is not conducive to the promotion of the product. Utility Model Content

[0005] In view of the shortcomings of the existing technology, the purpose of this utility model is to provide an abnormal detection circuit for the internal cooling fan of an instrument.

[0006] To achieve the above objectives, this utility model is implemented through the following technical solution:

[0007] An instrument internal cooling fan malfunction detection circuit includes a fan interface P1. The positive terminal of the fan interface P1 is connected to a 12V power supply. The negative terminal of the fan interface P1 is connected to the second pins of resistor R2 and resistor R3. The first pin of resistor R2 is connected to the drain of MOSFET Q1. The source of MOSFET Q1 is grounded. The gate of MOSFET Q1 is connected to the signal input terminal and the first pin of resistor R1. The second pin of resistor R1 is grounded. The first pin of resistor R3 is connected to the second pin of resistor R4 and a differentiating circuit. The first pin of the differentiating circuit is grounded. The differentiating circuit is connected to a differential amplifier circuit. A filter circuit is provided between the differentiating circuit and the differential amplifier circuit.

[0008] Furthermore, the differentiating circuit includes an operational amplifier IC1A. The non-inverting input of the operational amplifier IC1A is connected to the first pin of resistor R6 and the first pin of resistor R7, respectively. The second pin of resistor R6 is connected to a 5V power supply, and the second pin of resistor R7 is grounded. The inverting input of the operational amplifier IC1A is connected to the second pin of resistor R5, the second pin of resistor R8, and the anode of diode D1, respectively. The first pin of resistor R5 is connected to the first pin of capacitor C1, and the second pin of capacitor C1 is connected to the first pin of resistor R3. The output of the operational amplifier IC1A is connected to a differential amplifier circuit. The cathode of diode D1 and the first pin of resistor R8 are connected between the output of the operational amplifier IC1A and the differential amplifier circuit.

[0009] Furthermore, the differential amplifier circuit includes operational amplifier IC1B, whose non-inverting input is connected to the second pin of resistor R10 and the first pin of resistor R11, respectively. The second pin of resistor R11 is grounded, and the first pin of resistor R10 is connected to a 5V power supply. The inverting input of operational amplifier IC1A is connected to the second pin of resistor R12 and the first pin of resistor R13, respectively. The first pin of resistor R12 is connected to the output of operational amplifier IC1A. A filter circuit is set between the output of operational amplifier IC1A and the first pin of resistor R12. The second pin of resistor R13 is connected to the data output of operational amplifier IC1B.

[0010] Furthermore, the filter circuit includes capacitor C2 and resistor R9. The first pin of resistor R9 is grounded and connected to the first pin of capacitor C2. The second pins of resistor R9 and capacitor C2 are connected between the output of operational amplifier IC1A and the first pin of resistor R12.

[0011] The beneficial effects of this utility model are:

[0012] The cooling fan malfunction detection circuit of this invention can detect malfunctions in the cooling fan. Furthermore, the circuit is simple, occupies little space, and is suitable for use inside instruments and meters. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1This is a circuit diagram of an instrument's internal cooling fan malfunction detection circuit according to the present invention. Detailed Implementation

[0015] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0016] Please see Figure 1 This utility model provides a technical solution for an abnormal detection circuit of an internal cooling fan in an instrument, including a fan interface P1. The positive terminal of the fan interface P1 is connected to a 12V power supply. The negative terminal of the fan interface P1 is connected to the second pin of resistor R2 and the second pin of resistor R3. The first pin of resistor R2 is connected to the drain of MOSFET Q1. The source of MOSFET Q1 is grounded. The gate of MOSFET Q1 is connected to the signal input terminal and the first pin of resistor R1. The second pin of resistor R1 is grounded. The first pin of resistor R3 is connected to the second pin of resistor R4 and a differentiating circuit. The first pin of the differentiating circuit is grounded. The differentiating circuit is connected to a differential amplifier circuit. A filter circuit is provided between the differentiating circuit and the differential amplifier circuit.

[0017] See Figure 1 The differentiating circuit includes operational amplifier IC1A. The non-inverting input of operational amplifier IC1A is connected to the first pin of resistor R6 and the first pin of resistor R7. The second pin of resistor R6 is connected to a 5V power supply, and the second pin of resistor R7 is grounded. The inverting input of operational amplifier IC1A is connected to the second pin of resistor R5, the second pin of resistor R8, and the anode of diode D1. The first pin of resistor R5 is connected to the first pin of capacitor C1, and the second pin of capacitor C1 is connected to the first pin of resistor R3. The output of operational amplifier IC1A is connected to a differential amplifier circuit. The cathode of diode D1 and the first pin of resistor R8 are connected between the output of operational amplifier IC1A and the differential amplifier circuit.

[0018] See Figure 1The differential amplifier circuit includes operational amplifier IC1B. The non-inverting input of operational amplifier IC1B is connected to the second pin of resistor R10 and the first pin of resistor R11. The second pin of resistor R11 is grounded, and the first pin of resistor R10 is connected to a 5V power supply. The inverting input of operational amplifier IC1A is connected to the second pin of resistor R12 and the first pin of resistor R13. The first pin of resistor R12 is connected to the output of operational amplifier IC1A. A filter circuit is set between the output of operational amplifier IC1A and the first pin of resistor R12. The second pin of resistor R13 is connected to the output of operational amplifier IC1B and the uniform data output terminal.

[0019] See Figure 1 The filter circuit includes capacitor C2 and resistor R9. The first pin of resistor R9 is grounded and connected to the first pin of capacitor C2. The second pins of resistor R9 and capacitor C2 are connected between the output of operational amplifier IC1A and the first pin of resistor R12.

[0020] In use, this invention can determine whether the fan has malfunctioned by detecting whether the periodic changes of the control signal of the target fan, after being processed by the fan malfunction detection circuit, are maintained.

[0021] P1 is the fan interface, pin 1 is the positive terminal of the fan, and pin 2 is the negative terminal of the fan. The operating voltage of the fan is 12V. The Input is connected to the control signal from the MCU. This control signal is a PWM signal, which controls the fan speed by adjusting the duty cycle.

[0022] When Input is high, MOSFET Q1 is turned on, and the negative terminal of the fan is grounded through resistor R2. At this time, pin 2 of P1 is 0V. When Input is low, MOSFET Q1 is turned off, and the negative terminal of the fan is grounded through resistors R3 and R4. At this time, pin 2 of the fan interface P1 is 12V. After voltage division by resistors R3 and R4, when Input is high, the left end of capacitor C1 is 0V; when Input is low, the left end of capacitor C1 is 4V.

[0023] IC1 is a dual operational amplifier, consisting of operational amplifier IC1A and operational amplifier IC1B, each operating as a separate operational amplifier. Operational amplifier IC1A, capacitor C1, resistors R5 and R6, and diode D1 form a differentiating circuit. Because the voltage signal at the left end of capacitor C1 is a square wave of 0-4V, when the signal at the left end of capacitor C1 is on its falling edge, the output of operational amplifier IC1A has a 4V spike pulse; when it is on its rising edge, the output has a -4V spike pulse; otherwise, it is 0V. After passing through an RC filter circuit composed of capacitor C2 and resistor R9, the signal enters a differential amplifier circuit composed of operational amplifier IC1B, resistors R10, R11, R12, and R13. The final output signal is transmitted to the MCU for signal analysis.

[0024] When the fan is working normally, the spike pulses appear periodically. However, when the fan malfunctions, the periodic spike pulse phenomenon will be disrupted. At this time, no matter what the output signal looks like, it indicates that the fan is malfunctioning. In this case, it is necessary to stop operating the instrument and troubleshoot the problem.

[0025] Although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A circuit for detecting abnormal cooling fans inside instruments and meters, characterized in that, The system includes a fan interface P1, with its positive terminal connected to a 12V power supply. The negative terminal of the fan interface P1 is connected to the second pins of resistors R2 and R3. The first pin of resistor R2 is connected to the drain of MOSFET Q1, and the source of MOSFET Q1 is grounded. The gate of MOSFET Q1 is connected to the signal input terminal and the first pin of resistor R1, and the second pin of resistor R1 is grounded. The first pin of resistor R3 is connected to the second pin of resistor R4 and a differentiating circuit, and the first pin of the differentiating circuit is grounded. A filter circuit is provided between the differentiating circuit and the differential amplifier circuit.

2. The instrument internal cooling fan malfunction detection circuit according to claim 1, characterized in that, The differentiating circuit includes operational amplifier IC1A. The non-inverting input of operational amplifier IC1A is connected to the first pins of resistor R6 and resistor R7, respectively. The second pin of resistor R6 is connected to a 5V power supply, and the second pin of resistor R7 is grounded. The inverting input of operational amplifier IC1A is connected to the second pins of resistor R5 and resistor R8, respectively, and to the anode of diode D1. The first pin of resistor R5 is connected to the first pin of capacitor C1, and the second pin of capacitor C1 is connected to the first pin of resistor R3. The output of operational amplifier IC1A is connected to a differential amplifier circuit. The cathode of diode D1 and the first pin of resistor R8 are connected between the output of operational amplifier IC1A and the differential amplifier circuit.

3. The instrument internal cooling fan malfunction detection circuit according to claim 2, characterized in that, The differential amplifier circuit includes operational amplifier IC1B. The non-inverting input of operational amplifier IC1B is connected to the second pin of resistor R10 and the first pin of resistor R11. The second pin of resistor R11 is grounded, and the first pin of resistor R10 is connected to a 5V power supply. The inverting input of operational amplifier IC1A is connected to the second pin of resistor R12 and the first pin of resistor R13. The first pin of resistor R12 is connected to the output of operational amplifier IC1A. A filter circuit is set between the output of operational amplifier IC1A and the first pin of resistor R12. The second pin of resistor R13 is connected to the data output of operational amplifier IC1B.

4. The instrument internal cooling fan malfunction detection circuit according to claim 3, characterized in that, The filter circuit includes capacitor C2 and resistor R9. The first pin of resistor R9 is grounded and connected to the first pin of capacitor C2. The second pins of resistor R9 and capacitor C2 are connected between the output of operational amplifier IC1A and the first pin of resistor R12.

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