An ultrasonic-based passive wireless temperature measurement gun

Abstract

The application provides an ultrasonic-based passive wireless temperature measuring gun, and belongs to the technical field of passive wireless temperature measurement. The temperature measuring gun innovatively adopts an integrated ultrasonic lens. The geometric structure of the ultrasonic lens hemisphere can focus the ultrasonic wave energy generated by the piezoelectric ceramic array on the spherical surface thereof to the position of the spherical center. The focused high-power ultrasonic wave penetrates the metal shielding layer, thereby providing stable wireless power supply for the passive temperature collection circuit placed in the closed metal shell. After the circuit is activated, the temperature data is collected in real time, and the temperature information is modulated onto the ultrasonic wave signal through the piezoelectric effect and is returned to the temperature measuring gun, so that the internal temperature wireless monitoring without built-in power supply and without damaging the metal shell is realized.

Description

Technical Field

[0001] This invention belongs to the field of passive wireless temperature measurement technology, specifically relating to an ultrasonic-based passive wireless temperature measuring gun. Background Technology

[0002] Passive wireless temperature measurement technology refers to a type of temperature measurement method that uses an external excitation device to provide working energy to a temperature sensing terminal and transmits temperature information wirelessly. Existing passive wireless temperature measurement technologies mainly include surface acoustic wave (SAW), RFID, and infrared solutions. SAW utilizes the difference in sound wave propagation speed in piezoelectric materials caused by temperature changes to measure temperature. An external transmitter excites a sensor to generate sound waves via radio frequency signals, and the temperature is calculated by measuring the sound wave delay time. RFID technology uses the principle of backscattering radio signals. An external reader emits a radio frequency signal to excite a sensor, which modulates the temperature data into the backscattered signal and transmits it back. Infrared temperature measurement utilizes the characteristic that objects emit infrared radiation energy according to their own temperature. An infrared detector receives the radiation and converts it into an electrical signal, which is then used by an algorithm to calculate the temperature value—a non-contact temperature measurement method. These passive wireless temperature measurement solutions completely eliminate the maintenance needs caused by battery replacement and line aging compared to traditional active or wired temperature measurement solutions. They do not require complex wiring during installation, greatly shortening the construction cycle and reducing deployment costs. At the same time, they have stronger environmental adaptability and can be safely and reliably applied to harsh environments that are difficult for wired solutions to cover, such as high temperature, high pressure, strong electromagnetic fields, explosion hazard areas, and rotating parts. They also have lower overall life cycle costs and are particularly suitable for high-reliability monitoring scenarios that require long-term unattended operation.

[0003] While passive wireless temperature measurement technology has its advantages, it faces a key bottleneck in temperature measurement within completely enclosed metal-cased devices: due to electromagnetic shielding, wireless signals struggle to penetrate the metal shielding. In the aforementioned technologies, surface acoustic waves and radio frequency communication rely on electromagnetic waves for transmission, but the metal casing strongly shields and reflects these waves, leading to severe signal attenuation or interruption. This prevents sensors installed inside the metal casing from reliably communicating with external reading devices. Existing solutions typically require drilling holes in the cabinet or extending external antennas, but this compromises the original sealing and insulation levels of the equipment, introducing safety hazards and causing complex and costly retrofitting of existing equipment. Furthermore, alternative infrared temperature measurement technology, because infrared light also cannot penetrate metal casings, can only measure surface temperature and cannot directly and accurately monitor the temperature of critical internal contacts.

[0004] Therefore, developing a technology that can penetrate metal shielding layers without damage and achieve accurate temperature monitoring of equipment inside a closed metal cavity has become an urgent need in the field of industrial temperature measurement. Summary of the Invention

[0005] To address the problems existing in the background technology, the purpose of this invention is to provide a passive wireless temperature measuring gun based on ultrasound. This temperature measuring gun innovatively adopts an integrated ultrasonic lens. The geometric structure of the ultrasonic lens hemisphere can focus the ultrasonic energy generated by the piezoelectric ceramic array on its spherical surface to its center. The focused high-power ultrasonic wave then penetrates the metal shielding layer, providing a stable wireless power supply to the passive temperature acquisition circuit placed inside the sealed metal shell. After the circuit is activated, it acquires temperature data in real time and modulates the temperature information onto the ultrasonic signal through the piezoelectric effect and transmits it back to the temperature measuring gun, thereby realizing wireless internal temperature monitoring without the need for a built-in power supply or damage to the metal shell.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] An ultrasonic-based passive wireless temperature gun includes a temperature gun housing, an ultrasonic power supply system, an ultrasonic lens, and a temperature acquisition system.

[0008] The temperature gun housing is handheld and has an OLED display screen for displaying the measured temperature value; an ultrasonic lens is fixedly mounted on the front end of the temperature gun housing, and an ultrasonic power supply system is fixedly mounted on the temperature gun housing; the temperature acquisition system is fixedly mounted inside a closed metal cavity.

[0009] The ultrasonic power supply system includes a DC power supply, a first microcontroller, a self-excited oscillation circuit, a first piezoelectric ceramic, a power management module, and a first amplifier.

[0010] The temperature acquisition system includes a second microcontroller, a temperature sensor, a second amplifier, a rectifier bridge, a linear regulator, a constant current source, a second piezoelectric ceramic, and a third piezoelectric ceramic.

[0011] The ultrasonic lens is hemispherical in shape, consisting of a rigid hemispherical shell, a piezoelectric ceramic array, a silicone rubber protective layer, and a rigid hemispherical shell from the outside to the inside; the piezoelectric ceramic array includes a central piezoelectric ceramic and eight peripheral piezoelectric ceramics evenly distributed around the central piezoelectric ceramic;

[0012] The center of the ultrasonic lens and the second piezoelectric ceramic of the temperature acquisition system are respectively disposed on both sides of the metal layer of the closed metal cavity and aligned. The first piezoelectric ceramic and the third piezoelectric ceramic are respectively disposed on both sides of the metal layer of the closed metal cavity and aligned. The temperature sensor is disposed in the temperature region to be measured within the closed metal cavity.

[0013] The DC power supply provides power to the power management module and the self-excited oscillation circuit; the power management module is used to step down and filter the voltage before outputting it to the first microcontroller.

[0014] The self-excited oscillation circuit generates sinusoidal alternating current and transmits it to the ultrasonic lens, driving the ultrasonic lens to generate ultrasonic waves. After the ultrasonic waves penetrate the metal layer of the sealed metal cavity, they act on the second piezoelectric ceramic. The second piezoelectric ceramic converts the ultrasonic waves into alternating current based on the piezoelectric effect. The alternating current is rectified into direct current by a rectifier bridge, filtered, and then transmitted to a linear regulator. The linear regulator then outputs a stable voltage to continuously power the second microcontroller and the constant current source. The constant current source continuously generates a constant current. The temperature sensor detects the temperature of the area to be measured and converts the resistance signal into a voltage signal under the action of the constant current. The voltage signal is then amplified by the second amplifier. The signal is amplified and transmitted to a second microcontroller, which converts the voltage signal into a digital signal and modulates it to generate a PWM wave carrying temperature information. The PWM wave acts on a third piezoelectric ceramic, which converts it into an ultrasonic signal carrying temperature information based on the inverse piezoelectric effect. This ultrasonic signal penetrates the metal shell and acts on a first piezoelectric ceramic. After receiving the ultrasonic signal, the first piezoelectric ceramic converts it into an AC signal based on the piezoelectric effect. This AC signal is amplified by a first amplifier and then transmitted to the first microcontroller. The first microcontroller decodes the AC signal to obtain a digital temperature signal and transmits it to an OLED display screen on the temperature gun housing for display.

[0015] Furthermore, the power of the sinusoidal alternating current is 1.5W~2W, and the frequency can be determined according to the resonant frequency of the piezoelectric ceramic array of the ultrasonic lens.

[0016] Furthermore, the resonant frequency of the piezoelectric ceramic array is determined by the size and material of the piezoelectric ceramics in the array.

[0017] Furthermore, the piezoelectric ceramic material is a lead zirconate titanate-based piezoelectric ceramic.

[0018] Furthermore, the spacing between adjacent piezoelectric ceramics in the piezoelectric ceramic array is 8mm to 12mm, the size of a single piezoelectric ceramic is 8mm to 12mm, and the thickness is 1.5mm to 2.5mm.

[0019] Furthermore, the outer shell of the temperature measuring gun is made of polylactic acid (PLA) material through 3D printing process. Its front end is provided with a hemispherical groove for accommodating the ultrasonic lens and a circuit groove for fixing the ultrasonic power supply system. The size is determined by the ultrasonic lens and the ultrasonic power supply system.

[0020] Furthermore, during temperature measurement, acoustic impedance matching is achieved by attaching PI double-sided tape or other acoustic impedance matching adhesives to all media interfaces, where the media interfaces exist between the ultrasonic lens and the second piezoelectric ceramic, and between the first piezoelectric ceramic and the third piezoelectric ceramic.

[0021] Furthermore, the material of the silicone rubber protective layer is preferably Ecoflex.

[0022] Furthermore, both the rigid hemispherical shell and the rigid hemisphere are made of PMMA, the diameter of the rigid hemisphere is 20mm to 30mm, and the thickness of the rigid hemispherical shell is 0.8mm to 1.2mm.

[0023] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0024] 1. This invention innovatively employs ultrasound as a dual carrier for energy transmission and signal communication. The ultrasonic power supply system of the temperature gun emits ultrasound waves to provide working energy for the temperature acquisition system placed within a closed cavity, eliminating the need for an internal battery or external wires and achieving complete passivity. After acquiring energy, the temperature acquisition system transmits the collected temperature data back to the temperature gun via an ultrasonic carrier wave. Because ultrasound is a mechanical wave, unlike electromagnetic waves, it can effectively penetrate metal shielding shells, avoiding the shielding effect of metal on electromagnetic signals. This enables direct and non-destructive monitoring of the temperature at key points inside closed metal cavities (such as high-voltage switchgear, metal-sealed equipment, etc.), solving the long-standing problem of temperature measurement in such scenarios.

[0025] 2. This invention integrates a specially designed ultrasonic lens into the temperature measuring gun. The core of this lens is an optimized piezoelectric ceramic array. The geometry of the hemispherical lens allows the ultrasonic energy generated by multiple piezoelectric ceramics on its surface to be focused collaboratively at its center. This design significantly improves the ultrasonic power density over the operating distance, enabling a sufficient and stable supply of energy to a distant or hard-to-reach temperature acquisition system from one side of the temperature measuring gun. This overcomes the weaknesses of traditional single ultrasonic sources, such as limited power supply and susceptibility to distance and angle effects, and solves the core problem of unstable ultrasonic power supply, ensuring reliable startup and stable operation of the temperature acquisition circuit. Attached Figure Description

[0026] Figure 1 This is a schematic diagram showing the appearance and structure of the passive wireless temperature measuring gun based on ultrasonic power transmission communication according to the present invention.

[0027] Figure 2 This is a schematic diagram of the ultrasonic lens structure used for focusing ultrasound according to the present invention.

[0028] Figure 3 This is a physical image of the piezoelectric ceramic array inside the ultrasonic lens in this invention.

[0029] Figure 4 This is a circuit logic diagram of the ultrasonic power supply system and temperature acquisition system in actual use of the present invention.

[0030] Figure labels: 1 is the outer shell of the temperature measuring gun, 2 is the ultrasonic lens, and 3 is the ultrasonic power supply system.

[0031] 101 is an OLED display screen, 201 is a rigid hemispherical shell, 202 is a silicone protective layer, 203 is a rigid hemispherical body, 204 is a piezoelectric ceramic array, and 301 is the first piezoelectric ceramic. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings.

[0033] This invention designs a passive wireless temperature gun based on ultrasound. A specially designed hemispherical ultrasonic lens focuses ultrasonic waves to increase ultrasonic power, which then powers the accompanying temperature acquisition system. The temperature acquisition system uses piezoelectric ceramics to convert the received ultrasonic waves into electrical signals via the piezoelectric effect. After rectification and filtering, the signal activates the circuit and acquires data from the built-in temperature sensor. An encoding chip loads the temperature information onto the ultrasonic waves and transmits it back to the temperature gun. The temperature gun receives and analyzes the signal, thus achieving passive wireless measurement of the temperature of the monitored object. Because ultrasonic waves, as mechanical waves, can penetrate metal shielding, this temperature gun is suitable for temperature monitoring scenarios inside enclosed metal cavities.

[0034] A passive wireless temperature gun based on ultrasound, its external structure is shown in the schematic diagram below. Figure 1 As shown, it includes a temperature gun housing 1, an ultrasonic lens 2, and an ultrasonic power supply system 3; it also includes a temperature acquisition system, which is not shown in the figure.

[0035] The temperature gun housing is handheld and features an OLED display screen for showing the measured temperature value. The housing is made of polylactic acid (PLA) material using a 3D printing process. Its front end has a hemispherical groove for accommodating an ultrasonic lens and a circuit groove for fixing the ultrasonic power supply system. The ultrasonic lens 2 is fixedly mounted on the front end of the temperature gun housing 1, and the ultrasonic power supply system 3 is fixedly mounted in a slot within the housing. The temperature acquisition system is fixedly mounted within a sealed metal cavity.

[0036] The OLED display 101, the ultrasonic lens 2 and the ultrasonic power supply system 3 are electrically connected by flexible copper wires. The ultrasonic power supply system 3 is encapsulated and protected with silicone sealant to ensure that the working surface of the piezoelectric ceramic 301 is exposed and not covered by the sealant.

[0037] A schematic diagram of the ultrasonic lens structure is shown below. Figure 2As shown, the structure is hemispherical, consisting of a rigid hemispherical shell 201, a piezoelectric ceramic array 204, a silicone rubber protective layer 202, and a rigid hemispherical 203, arranged from the outside in. The piezoelectric ceramic array includes a central piezoelectric ceramic and eight peripheral piezoelectric ceramics evenly distributed around it. The rigid hemispherical shell 201 serves as the external protective structure. The silicone rubber protective layer 202 covers the periphery of the piezoelectric ceramic array 204, serving as an adhesive and acoustic matching layer. The rigid hemispherical 203 acts as a supporting substrate, and its higher sound velocity helps reduce energy loss during ultrasonic wave propagation. A physical image of the piezoelectric ceramic array 204 is shown below. Figure 3 As shown; the array consists of 9 piezoelectric ceramics arranged in a centrally symmetrical geometric structure, with a distance of 8mm to 12mm between each piezoelectric ceramic; the ceramics are connected by serpentine wires to avoid mechanical stress causing the wires to break; in terms of electrical connection, the 9 piezoelectric ceramics are connected in parallel.

[0038] The ultrasonic power supply system includes a DC power supply, a first microcontroller, a self-excited oscillation circuit, a first piezoelectric ceramic, a power management chip, and a first amplifier.

[0039] The temperature acquisition system includes a second microcontroller, a temperature sensor, a second amplifier, a rectifier bridge, a linear regulator, a constant current source, a second piezoelectric ceramic, and a third piezoelectric ceramic.

[0040] Figure 4 This is a circuit logic diagram of the ultrasonic power supply system and temperature acquisition system during use of the present invention. The second piezoelectric ceramic of the temperature acquisition system corresponds spatially to the center of the hemispherical ultrasonic lens, and the third piezoelectric ceramic of the temperature acquisition system corresponds to the first piezoelectric ceramic. When the ultrasonic temperature gun measures temperature, the 15V DC power supply, after being filtered by the power management module, powers the first microcontroller of the ultrasonic power supply system, and also powers the self-excited oscillation circuit in the ultrasonic power supply system. The self-excited oscillation circuit generates a sinusoidal alternating current, which is loaded onto the ultrasonic lens through a flexible copper wire, driving the ultrasonic lens to generate and focus ultrasonic waves. After the ultrasonic waves penetrate the metal layer of the sealed metal cavity, they act on the second piezoelectric ceramic of the temperature acquisition system. The second piezoelectric ceramic converts the ultrasonic waves into alternating current based on the piezoelectric effect and transmits it to the rectifier bridge. The rectifier bridge rectifies the alternating current into direct current, filters it, and then transmits it to the linear voltage regulator. The linear voltage regulator stabilizes the output voltage, continuously powering the second microcontroller and the constant current source.

[0041] In the temperature acquisition system located within the metal cavity, a constant current source continuously generates a constant current. A temperature sensor detects the temperature of the area to be measured; its resistance changes with temperature, and under the constant current excitation of the constant current source, it converts the resistance signal into an analog voltage signal. This analog voltage signal is amplified 20 times by a second amplifier and then transmitted to a second microcontroller. The second microcontroller's ADC acquires the amplified analog voltage signal, converts it into a digital signal, and inputs it into the second microcontroller's timer. The timer encodes the digital signal according to the OOK data modulation method and generates a PWM wave carrying temperature information. This PWM wave acts on a third piezoelectric ceramic, which converts it into an ultrasonic signal carrying temperature information based on the inverse piezoelectric effect. This ultrasonic signal penetrates the metal shell and acts on a first piezoelectric ceramic. After receiving the returned ultrasonic signal, the first piezoelectric ceramic amplifies it and transmits it to a first microcontroller. The first microcontroller decodes and converts it back into a digital temperature signal, ultimately displaying the temperature data on an OLED display screen on the temperature gun's outer shell.

[0042] The above description is merely a specific embodiment of the present invention. Any feature disclosed in this specification may be replaced by other equivalent or similar features unless otherwise specified. All disclosed features, or steps in all methods or processes, may be combined in any way except for mutually exclusive features and / or steps.

Claims

1. A passive wireless temperature measuring gun based on ultrasound, characterized in that, It includes the temperature gun housing, ultrasonic power supply system, ultrasonic lens, and temperature acquisition system; The temperature gun housing is handheld and has an OLED display screen for displaying the measured temperature value; an ultrasonic lens is fixedly mounted on the front end of the temperature gun housing, and an ultrasonic power supply system is fixedly mounted on the temperature gun housing; the temperature acquisition system is fixedly mounted inside a closed metal cavity. The ultrasonic power supply system includes a DC power supply, a first microcontroller, a self-excited oscillation circuit, a first piezoelectric ceramic, a power management module, and a first amplifier. The temperature acquisition system includes a second microcontroller, a temperature sensor, a second amplifier, a rectifier bridge, a linear regulator, a constant current source, a second piezoelectric ceramic, and a third piezoelectric ceramic. The ultrasonic lens is hemispherical in shape, consisting of a rigid hemispherical shell, a piezoelectric ceramic array, a silicone rubber protective layer, and a rigid hemispherical shell from the outside to the inside; the piezoelectric ceramic array includes a central piezoelectric ceramic and eight peripheral piezoelectric ceramics evenly distributed around the central piezoelectric ceramic; The center of the ultrasonic lens and the second piezoelectric ceramic of the temperature acquisition system are respectively disposed on both sides of the metal layer of the closed metal cavity and aligned. The first piezoelectric ceramic and the third piezoelectric ceramic are respectively disposed on both sides of the metal layer of the closed metal cavity and aligned. The temperature sensor is disposed in the temperature region to be measured within the closed metal cavity. The DC power supply provides power to the power management module and the self-excited oscillation circuit; the power management module is used to step down and filter the voltage before outputting it to the first microcontroller. The self-excited oscillation circuit generates sinusoidal alternating current and transmits it to the ultrasonic lens, driving the ultrasonic lens to generate ultrasonic waves. After the ultrasonic waves penetrate the metal layer of the sealed metal cavity, they act on the second piezoelectric ceramic. The second piezoelectric ceramic converts the ultrasonic waves into alternating current based on the piezoelectric effect. The alternating current is rectified into direct current by a rectifier bridge and filtered before being transmitted to a linear voltage regulator. The linear voltage regulator then outputs a stable voltage to continuously power the second microcontroller and the constant current source. A constant current source is used to continuously generate a constant current; a temperature sensor is used to detect the temperature of the area to be measured and converts the resistance signal into a voltage signal under the action of the constant current. The voltage signal is amplified by a second amplifier and transmitted to a second microcontroller. The second microcontroller converts the voltage signal into a digital signal and modulates it to generate a PWM wave carrying temperature information. The PWM wave acts on a third piezoelectric ceramic, which converts it into an ultrasonic signal carrying temperature information based on the inverse piezoelectric effect. The ultrasonic signal penetrates the metal shell and acts on a first piezoelectric ceramic. After receiving the ultrasonic signal, the first piezoelectric ceramic converts it into an alternating current signal based on the piezoelectric effect. After being amplified by a first amplifier, it is transmitted to a first microcontroller. The first microcontroller decodes the alternating current signal to obtain a digital temperature signal and transmits the digital temperature signal to an OLED display screen on the temperature gun housing for display.

2. The passive wireless temperature measuring gun as described in claim 1, characterized in that, The power of the sinusoidal alternating current is 1.5W~2W, and the frequency can be determined according to the resonant frequency of the piezoelectric ceramic array of the ultrasonic lens.

3. The passive wireless temperature measuring gun as described in claim 2, characterized in that, The resonant frequency of a piezoelectric ceramic array is determined by the size and material of the piezoelectric ceramics in the array.

4. The passive wireless temperature measuring gun as described in claim 1, characterized in that, The piezoelectric ceramic material is a lead zirconate titanate-based piezoelectric ceramic.

5. The passive wireless temperature measuring gun as described in claim 1, characterized in that, The spacing between adjacent piezoelectric ceramics in the piezoelectric ceramic array is 8mm to 12mm, the size of a single piezoelectric ceramic is 8mm to 12mm, and the thickness is 1.5mm to 2.5mm.

6. The passive wireless temperature measuring gun as described in claim 1, characterized in that, The outer shell of the temperature gun is made of polylactic acid material using a 3D printing process. Its front end has a hemispherical groove for accommodating the ultrasonic lens and a circuit groove for fixing the ultrasonic power supply system. The size is determined by the ultrasonic lens and the ultrasonic power supply system.

7. The passive wireless temperature measuring gun as described in claim 1, characterized in that, During temperature measurement, acoustic impedance matching is achieved by attaching PI double-sided tape or other acoustic impedance matching adhesive to all media interfaces. The media interfaces exist between the ultrasonic lens and the second piezoelectric ceramic, and between the first piezoelectric ceramic and the third piezoelectric ceramic.

8. The passive wireless temperature measuring gun as described in claim 1, characterized in that, The material of the silicone rubber protective layer is Ecoflex.

9. The passive wireless temperature measuring gun as described in claim 1, characterized in that, Both the rigid hemispherical shell and the rigid hemisphere are made of PMMA. The diameter of the rigid hemisphere is 20mm to 30mm, and the thickness of the rigid hemispherical shell is 0.8mm to 1.2mm.

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