Test tube temperature measuring device

Abstract

The present invention relates to the field of temperature measurement, and in particular to the field of temperature measurement inside a test tube for chemical experiments. A test tube temperature measuring device places a magnetostrictive sensor inside an induction coil and an excitation coil, inputs a sinusoidal wave signal within a certain frequency range into the excitation coil, the excitation coil generates an alternating magnetic field, the magnetostrictive sensor vibrates under the action of the alternating magnetic field, and the induction coil outputs an induced voltage. By detecting the maximum value of the induced voltage of the induction coil, the resonant frequency of the magnetostrictive sensor can be obtained, and the corresponding curve between the test tube temperature and the resonant frequency of the magnetostrictive sensor can be obtained through experiments. The magnetostrictive sensor used in this temperature measuring device is passive and wireless, which is convenient for experimenters to operate the test tube and does not affect the conduct of the experiment.

Description

Technical Field

[0001] The invention relates to the field of temperature measurement, in particular to the field of temperature measurement inside a test tube used in chemical experiments. Background Art

[0002] In chemical experiments, it is usually necessary to measure the temperature of a test tube. The traditional test tube temperature detection method is to place a thermometer in the test tube or stick a temperature sensor on the surface of the test tube, and the experimenter reads the temperature value, which takes up the experimenter's time. The measurement process may interrupt the experiment at any time, and there may be errors in the reading of the temperature value. Chinese patents CN104549595A (a test tube capable of measuring temperature) and CN205684059U (a test tube capable of measuring temperature) place the thermometer between the test tube and the shell, and the experimenter needs to read the temperature value.

[0003] The temperature sensor is pasted on the surface of the test tube. The temperature sensor senses the temperature value of the test tube and transmits it to the processor through a data cable. The processor receives the data and converts it for display. This method has reduced vehicle accuracy due to the influence of the test tube wall, and uses an active, wired connection method, which limits the movement range of the test tube and is not conducive to the development of the experiment. Summary of the invention

[0004] The technical problem to be solved by the present invention is: how to provide a device that has high measurement accuracy for the contents of a test tube, is easy to move, and is convenient for measuring the temperature inside a test tube for chemical experiments. The technical solution adopted by the present invention is: a test tube temperature measuring device, comprising a strip-shaped magnetostrictive sensor (3), an induction coil (4), an excitation coil (5), an excitation signal driving module, an induction coil voltage detection module, and a host computer. The magnetostrictive sensor (3) is installed inside the test tube (1) in a length direction parallel to the test tube (1). The induction coil (4) and the excitation coil (5) are sleeved on the side of the test tube (1). The magnetostrictive sensor (3) is inside the induction coil (4) and the excitation coil (5). The excitation signal driving module is connected to the excitation coil (5), and the induction coil voltage detection module is connected to the induction coil (4). During use, the excitation signal driving module continuously sends an increasing frequency or An electrical signal of the same voltage with decreasing frequency is given to the excitation coil (5). Each frequency signal is a cycle. After completion, the next frequency is generated. The excitation coil (5) generates an excitation magnetic field. The magnetostrictive sensor (3) vibrates in the excitation magnetic field. The induction coil voltage detection module detects the voltage of the induction coil (4) and sends it to the host computer. The host computer detects the frequency corresponding to the electrical signal sent by the excitation signal driving module when the induction coil (4) has a maximum voltage, i.e., the resonant frequency of the magnetostrictive sensor. In the temperature measurement range, the resonant frequency of the magnetostrictive sensor is in a one-to-one correspondence with its temperature. The host computer obtains the temperature of the magnetostrictive sensor through the resonant frequency of the magnetostrictive sensor.

[0005] The test tube temperature measuring device also includes a programmable logic device FPGA and a wireless communication module. The host computer sends an excitation sinusoidal wave signal frequency range to the programmable logic device FPGA via the wireless communication module. The programmable logic device FPGA sends a sinusoidal wave signal to the excitation signal driving module according to the excitation sinusoidal wave signal frequency range. The excitation signal driving module sends a sinusoidal wave signal of the same voltage with increasing or decreasing frequency to the excitation coil (5).

[0006] The excitation signal driving module comprises a DA conversion circuit and a signal amplification circuit. The excitation signal driving module sends the sine wave signal to the excitation coil (5) after DA conversion and amplification.

[0007] The programmable logic device FPGA is connected to the induction coil voltage detection module. The programmable logic device FPGA obtains the voltage value of the induction coil (4) in real time through the induction coil voltage detection module while sending the sinusoidal wave signal to the excitation signal driving module and stores the voltage value in the RAM memory of the programmable logic device FPGA. The programmable logic device FPGA increases or decreases the frequency of the sinusoidal wave signal sent to the excitation signal driving module at a stepping frequency. The programmable logic device FPGA obtains the maximum value of the voltage value stored in the RAM memory within a cycle when the programmable logic device FPGA outputs the sinusoidal wave signal from the starting and ending frequencies to the ending frequency. The sinusoidal wave signal frequency corresponding to the maximum value is the resonance frequency of the magnetostrictive sensor.

[0008] The magnetostrictive sensor (3) is fixed on the bottom of the test tube (1).

[0009] The test tube temperature measuring device also includes a display module, which displays the temperature of the magnetostrictive sensor obtained by the resonance frequency in real time and transmits it to the host computer.

[0010] The magnetostrictive sensor is used to sense the temperature of the test tube. The magnetostrictive sensor is pasted to the bottom of the test tube. The magnetostrictive sensor is placed in the induction coil and the excitation coil. A sinusoidal signal is input at both ends of the excitation coil to generate an alternating magnetic field. The magnetostrictive sensor vibrates under the action of the alternating magnetic field, and the induction coil outputs an induced voltage. The resonant frequency of the magnetostrictive sensor changes with the temperature of the test tube. The corresponding curve between the test tube temperature and the resonant frequency of the magnetostrictive sensor can be obtained through experiments. When the input sinusoidal wave frequency is equal to the resonant frequency of the magnetostrictive sensor, the induced voltage value of the induction coil is the largest. The resonant frequency of the magnetostrictive sensor can be obtained by detecting the maximum value of the induced voltage of the induction coil. The test tube temperature value can be calculated from the corresponding curve between the test tube temperature and the resonant frequency of the magnetostrictive sensor.

[0011] The present invention uses a programmable logic device FPGA (FPGA for short) as a system control unit, receives the frequency range of the excitation signal sent by the host computer through a wireless communication module, uses the internal logic resources of the FPGA to design a sine wave signal generator, uses the internal RAM of the FPGA as a memory, writes the sine wave signal sampling value into the memory, and the memory read address clock frequency is equal to the output sine wave signal frequency multiplied by the number of sampling points in a single cycle. The FPGA outputs a sine wave signal to the excitation signal driving circuit, the excitation signal driving circuit completes the DA conversion and signal amplification of the sine wave signal, and outputs it to the excitation coil, and the excitation coil generates an alternating magnetic field. The magnetostrictive sensor vibrates under the action of the alternating magnetic field, and the induction coil outputs an induced voltage, which is output to the induction coil voltage detection module. The induction coil voltage detection module is composed of an amplifier circuit, an effective value conversion circuit, and an AD conversion circuit. The effective value conversion circuit is implemented by using an LTC1968 chip or an AD536A chip to convert the AC voltage output by the induction coil into an effective value DC voltage. The AD conversion circuit is implemented by using an analog-to-digital conversion chip to convert the effective value DC voltage output by the effective value conversion circuit into a digital signal, and outputs it to the FPGA controller. Utilizing the internal logic resources of FPGA, design the AD converter data reading timing, read the induction coil induced voltage value output by the AD conversion circuit, store the current FPGA output sine wave frequency and the induction coil induced voltage value into the FPGA internal RAM memory, increase the output sine wave frequency at a step frequency according to the excitation sine wave frequency range sent by the receiving host computer, and store the induction coil induced voltage value at the same time.

[0012] The FPGA outputs a sinusoidal excitation signal from the start frequency to the end frequency within a cycle, and the maximum value of the induction voltage of the induction coil is determined. The sinusoidal wave frequency corresponding to the maximum value is the resonant frequency of the magnetostrictive sensor. The resonant frequency of the magnetostrictive sensor changes with the temperature of the test tube. Through experiments, the corresponding curve between the test tube temperature and the resonant frequency of the magnetostrictive sensor is obtained. According to the resonant frequency of the magnetostrictive sensor, the current test tube temperature value can be calculated. The current test tube temperature value is transmitted to the display module, which can be displayed in real time on the digital tube and LCD screen, and can be transmitted to the host computer through Bluetooth and Wifi wireless communication modules. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a structural diagram of the present invention;

[0014] Figure 2 for Figure 1 A top view of

[0015] Among them: 1. test tube; 2. bracket; 3. magnetostrictive sensor; 4. induction coil; 5. excitation coil. DETAILED DESCRIPTION

[0016] The implementation process of the present invention will be further described below in conjunction with the embodiments of the present invention. A 32mm*6mm rectangular strip magnetostrictive sensor is vertically pasted to the bottom of the test tube. Figure 1 As shown, the magnetostrictive sensor is placed inside the induction coil (wire diameter 0.16mm, 237 turns, length 38mm) and the excitation coil (wire diameter 0.16mm, 200 turns, length 48mm). The induction coil is placed inside the excitation coil. The diameter of the excitation coil is larger than the diameter of the induction coil. A programmable logic device FPGA is used as the system control unit.

[0017] When the device is working, the host computer sends data to the programmable logic device FPGA through the wireless communication module (Bluetooth or Wifi). The data sent is the frequency range of the excitation signal (the range can be obtained through experience or experiments). The sent data consists of 9 bytes. The first byte indicates the frame type, which is defined as 0xA1 (the data transmitted between the host computer and the system control unit (programmable logic device FPGA) is divided into data frame, response frame, and retransmission frame). The second byte indicates the node ID (0x00-0xFF) (the host computer can communicate with multiple temperature measuring devices, that is, it can control multiple test tubes for temperature testing at the same time. The embodiment is a test tube, each temperature measuring device is used as a node, and different IDs are defined). The 3rd and 4th bytes represent the starting frequency of the excitation signal, the 5th and 6th bytes represent the ending frequency of the excitation signal, and the 7th and 8th bytes represent the step frequency of the excitation signal (which can be positive or negative, positive in this embodiment, and the step frequency is a constant value. In theory, the smaller the step frequency value, the better (the smaller the step frequency, the more accurate the measurement result), but in actual process, the smaller the step frequency, the longer the measurement time is required. It can be selected according to actual needs, such as 10 Hz), and the 9th byte is a check, using a cyclic redundancy check CRC-8 check. The wireless communication module sends data to the FPGA through the UART serial port. After receiving the data, the FPGA performs verification according to the CRC-8 algorithm. If the verification result is correct (using the existing verification technology), the FPGA sends a response message to the host computer through the wireless communication module. The response message consists of 2 bytes, 1 byte indicates the frame type, defined as 0xA2, and 2 bytes are defined as the node ID (0x00-0xFF); if the verification is wrong, the FPGA sends a retransmission message through the wireless communication module. The retransmission message consists of 2 bytes, 1 byte indicates the frame type, defined as 0xA3, and 2 bytes are defined as the node ID (0x00-0xFF). The retransmission message is sent to the FPGA through the wireless communication module.

[0018] After the programmable logic device FPGA receives the data and verifies that it is correct, the 3rd and 4th bytes are extracted as the starting frequency of the excitation signal, the 5th and 6th bytes are extracted as the ending frequency of the excitation signal, and the 7th and 8th bytes are extracted as the stepping frequency of the excitation signal. The internal RAM of the FPGA is used as a memory, and the sine wave signal (sinusoidal AC signal of equal voltage) data is stored in memory 1 (such as using Matlab software to generate a sine wave signal, and sampling it to obtain a sine wave signal). The memory read address clock frequency is equal to the output sine wave signal frequency multiplied by the number of sampling points in a single cycle. The number of sampling points in a single cycle is set to 128. The programmable logic device FPGA outputs an excitation sine wave signal. The sine wave signal frequency is the starting frequency of the excitation signal. The excitation sine wave signal output by the FPGA is transmitted to the excitation signal driving circuit. The excitation signal driving circuit consists of a DA conversion and a signal amplification circuit. The DA conversion circuit converts the digital sine wave signal output by the FPGA into an analog signal. The signal amplification circuit amplifies the converted analog sine wave signal and transmits it to the excitation coil to drive the excitation coil to generate an alternating magnetic field.

[0019] The magnetostrictive sensor vibrates under the action of the alternating magnetic field, and the induction coil outputs an induced voltage, which is transmitted to the induction coil voltage detection module. The voltage amplifier circuit amplifies the induced voltage output by the induction coil, and the effective value conversion circuit converts the amplified AC voltage into an effective value. The effective value conversion circuit is implemented using the LTC1968 chip or the AD536A chip. The AD conversion circuit converts the converted effective value into a digital DC voltage, and the digital DC voltage is output to the FPGA controller. The AD converter data reading timing is designed using the logic resources in the FPGA (designed according to the data reading timing of the AD converter chip, which belongs to the prior art), and the induction coil to induced voltage value output by the AD conversion circuit is obtained.

[0020] The frequency of the sine wave signal output by the FPGA and the obtained induction coil induced voltage value are stored in the FPGA internal RAM memory 2. According to the sine wave frequency range information sent by the host computer, the output sine wave frequency is increased in sequence according to the step frequency, and the induction coil induced voltage value corresponding to the output frequency is obtained until the FPGA output sine wave frequency is equal to the termination frequency of the excitation signal sent by the host computer. According to the stored induction coil induced voltage value, the maximum value is determined, and the sine wave frequency corresponding to the maximum value is the resonant frequency of the magnetostrictive sensor. The corresponding curve of the test tube temperature and the resonant frequency of the magnetostrictive sensor is obtained through experiments (increasing the test tube temperature in sequence, measuring the corresponding resonant frequency of the magnetostrictive sensor at different temperatures, and obtaining the corresponding curve of the test tube temperature and the resonant frequency of the magnetostrictive sensor). According to the resonant frequency of the magnetostrictive sensor, the current test tube temperature value can be calculated.

[0021] The digital tube and LCD display drivers are designed using the internal logic resources of the FPGA, and the calculated temperature value can be displayed in the display module. The UART serial communication interface is designed using the internal logic resources of the FPGA to realize the connection between the FPGA and the Bluetooth module and the Wifi wireless communication module, and the temperature value can be transmitted to the host computer through the Bluetooth and Wifi wireless communication modules. The functional modules inside the FPGA are described using the hardware description language VHDL or Verilog HDL and designed and implemented using the internal logic resources of the FPGA.

[0022] The above content is a further detailed description of the present invention in combination with specific implementation methods. It cannot be determined that the specific implementation methods of the present invention are limited to these. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the present invention, which should be regarded as belonging to the present invention and the scope of patent protection determined by the submitted claims.

Claims

1. A test tube temperature measuring device, characterized in that: The invention comprises a strip-shaped magnetostrictive sensor (3), an induction coil (4), an excitation coil (5), an excitation signal driving module, an induction coil voltage detection module, and a host computer. The magnetostrictive sensor (3) is installed inside the test tube (1) in a length direction parallel to the test tube (1). The induction coil (4) and the excitation coil (5) are sleeved around the test tube (1). The magnetostrictive sensor (3) is inside the induction coil (4) and the excitation coil (5). The excitation signal driving module is connected to the excitation coil (5). The induction coil voltage detection module is connected to the induction coil (4). During use, the excitation signal driving module continuously sends a signal. An electric signal of the same voltage with increasing or decreasing frequency is sent to the excitation coil (5), the excitation coil (5) generates an excitation magnetic field, the magnetostrictive sensor (3) vibrates in the excitation magnetic field, the induction coil voltage detection module detects the voltage of the induction coil (4) and sends it to the host computer, the host computer detects the frequency corresponding to the electric signal sent by the excitation signal driving module when the induction coil (4) has the maximum voltage, that is, the resonant frequency of the magnetostrictive sensor. In the temperature measurement range, the resonant frequency of the magnetostrictive sensor is in a one-to-one correspondence with its temperature, and the host computer obtains the magnetostrictive sensor through the resonant frequency of the magnetostrictive sensor. The test tube temperature measuring device also includes a programmable logic device FPGA and a wireless communication module. The upper computer sends an excitation sinusoidal wave signal frequency range to the programmable logic device FPGA through the wireless communication module. The programmable logic device FPGA sends a sinusoidal wave signal to the excitation signal driving module according to the excitation sinusoidal wave signal frequency range. The excitation signal driving module sends a sinusoidal wave signal of the same voltage with increasing or decreasing frequency to the excitation coil (5). The programmable logic device FPGA is connected to the induction coil voltage detection module. When the programmable logic device FPGA sends the sinusoidal wave signal to the excitation signal driving module, it obtains the voltage value of the induction coil (4) in real time through the induction coil voltage detection module and stores the voltage value in the RAM memory of the programmable logic device FPGA. The programmable logic device FPGA increases or decreases the frequency of the sinusoidal wave signal sent to the excitation signal driving module at a stepping frequency. When the programmable logic device FPGA outputs a sinusoidal wave signal from the starting and ending frequencies to the ending frequencies in a cycle, the programmable logic device FPGA obtains the maximum value of the voltage value stored in the RAM memory in the cycle. The sinusoidal wave signal frequency corresponding to the maximum value is the resonance frequency of the magnetostrictive sensor.

2. A test tube temperature measuring device according to claim 1, characterized in that: The excitation signal driving module comprises a DA conversion circuit and a signal amplification circuit. The excitation signal driving module sends the sine wave signal to the excitation coil (5) after DA conversion and amplification.

3. A test tube temperature measuring device according to claim 1, characterized in that: The magnetostrictive sensor (3) is fixed on the bottom of the test tube (1).

4. A test tube temperature measuring device according to claim 1, characterized in that: The test tube temperature measuring device also includes a display module, which displays the temperature of the magnetostrictive sensor obtained by the resonance frequency in real time and transmits it to the host computer.

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