Automobile pressure power generation driving vehicle-mounted refrigerator system based on piezoelectric effect

Abstract

The invention relates to the technical field of automobile energy utilization and vehicle-mounted equipment, and discloses an automobile pressure power generation driving vehicle-mounted refrigerator system based on a piezoelectric effect. Comprising a differential pressure power generation system, a thermoelectric refrigeration system and an electric energy collection and management system, wherein the differential pressure power generation system is used for converting mechanical energy into electric energy based on a piezoelectric effect by utilizing pulse pressure generated by self gravity in the running process of automobile tires; the differential pressure power generation system comprises a piezoelectric fiber plate made of a composite piezoelectric material, and the piezoelectric fiber plate is of a five-layer structure. According to the vehicle pressure power generation driving vehicle-mounted refrigerator system based on the piezoelectric effect, a power generation system is built through the vehicle pressure and the piezoelectric effect, mechanical energy in the tire running process is converted into electric energy, power is supplied to a vehicle-mounted refrigerator, effective combination of vehicle tire power generation and vehicle-mounted refrigerator energy supply is achieved, the energy conversion link is reduced, and the energy utilization rate is increased. And the energy utilization rate is improved, and the sustainable development concept is met.

Description

Technical Field

[0001] The present invention relates to the technical field of automotive energy utilization and in-vehicle equipment, and particularly to a vehicle-mounted refrigerator system driven by automotive pressure power generation based on the piezoelectric effect. Background Art

[0002] With the rapid development of society, the energy problem has become increasingly prominent. As an important means of transportation, the energy consumption of automobiles accounts for a considerable proportion in the total energy consumption. At the same time, people's requirements for the comfort and functionality of automobiles are constantly increasing, and the demand for vehicle-mounted refrigerators is gradually increasing. However, traditional vehicle-mounted refrigerators often rely on the vehicle's own power system, increasing the vehicle's energy consumption.

[0003] When an automobile is running, the tires will deform and vibrate due to the road surface pressure, and this part of the energy is usually wasted. Although there have been attempts to collect energy using piezoelectric materials before, such as using a cantilever beam structure to collect tire vibration energy, there are many defects. For example, it is necessary to precisely adjust the resonance frequency between the excitation and the cantilever beam, and the vibration energy can only be recovered in a single direction, unable to fully utilize the deflection energy of the tires in multiple directions, and the collection efficiency is low. Therefore, developing a vehicle-mounted refrigerator power supply system that is efficient, stable and can fully utilize tire energy has become the research focus of the industry. Summary of the Invention

[0004] (I) Technical Problems to be Solved Aiming at the deficiencies of the prior art, the present invention provides a vehicle-mounted refrigerator system driven by automotive pressure power generation based on the piezoelectric effect, which solves the problems raised in the above background art.

[0005] (II) Technical Solutions To achieve the above object, the present invention provides the following technical solutions: A vehicle-mounted refrigerator system driven by automotive pressure power generation based on the piezoelectric effect, including a differential pressure power generation system, a thermoelectric refrigeration system, and an electric energy collection and management system: Differential pressure power generation system: Utilizing the pulse pressure generated by the self-weight of the automobile tires during driving, converting mechanical energy into electrical energy based on the piezoelectric effect; the differential pressure power generation system includes a piezoelectric fiber sheet made of a composite piezoelectric material, the piezoelectric fiber sheet has a five-layer structure, from the outside to the inside are upper and lower plastic protection layers, an electrode layer, and a middle piezoelectric thin film layer for generating electrical energy; it also includes a full-wave rectifier circuit for converting the alternating current generated by the piezoelectric fiber sheet into direct current; Thermoelectric refrigeration system: Using semiconductor thermocouples as the basic refrigeration unit, the semiconductor thermocouples are composed of P-type semiconductors (bismuth telluride - antimony telluride solid solution alloy) and N-type semiconductors (bismuth telluride - bismuth selenide solid solution alloy); multiple semiconductor thermocouples are connected into a thermopile, the thermopile adopts a series structure and is separated by a thermally conductive electrical insulation layer; the system is equipped with a cold plate for exporting cold, a radiator for heat dissipation at the hot end, and a fan for cooling the radiator; Electric energy collection and distribution system: According to the electrical load demand, 6 groups of piezoelectric fiber sheets with a single-chip power of 3w are evenly distributed on each of the 4 tires of the car; part of the electric energy after rectification and filtering is used to provide power consumption for the thermoelectric refrigeration semiconductor, so that the cold plate generates cold to supply the in-vehicle refrigerator, and the other part is used to drive the fan to operate to cool the hot end of the thermopile; there is an energy storage device, when the car stops or the power generation of the piezoelectric fiber sheets is insufficient, it supplies power to the in-vehicle refrigerator.

[0006] Preferably, the distribution method of the piezoelectric fiber sheets on the tire is to be evenly distributed based on the principle of ensuring the maximum contact with the tire deformation area, and their installation positions and angles are optimized so that the piezoelectric fiber sheets can generate the maximum mechanical stress when the tire deforms, thereby improving the power generation efficiency.

[0007] Preferably, the full-wave rectifier circuit is composed of a bridge circuit structure with at least four diodes, which converts the negative half-cycle waveform in the alternating current generated by the piezoelectric fiber sheets into a positive half-cycle waveform, realizes the conversion from alternating current to direct current, and filters the converted direct current through a filter capacitor to output a stable DC voltage.

[0008] Preferably, the thermopile is composed of 71 pairs of thermocouples, arranged in 10 rows with 7 pairs in each row, and the connection methods between the thermocouples in each row and between the thermocouples in each column are designed to ensure uniform current distribution when the thermopile works and the same refrigeration effect for each thermocouple.

[0009] Preferably, the thermally conductive electrical insulation layer uses materials such as beryllium oxide and alumina by anodization. On the premise of meeting the electrical insulation performance, its thickness is as thin as possible, and the specific thickness range is from [X1] millimeters to [X2] millimeters to reduce the additional thermal resistance and additional temperature difference between the thermopile nodes and the heat exchanger.

[0010] Preferably, the radiator is an aluminum flat fin structure, with precise dimensions of 50mm in length, 30mm in width, and 2mm in thickness, a total of 45 fins, evenly arranged in 3 rows with 15 fins in each row, and the shape and spacing of the fins are optimized to improve the heat dissipation efficiency and enhance the heat exchange ability between the air and the radiator.

[0011] Preferably, the model of the blower is DC4V / 1.5A, the outer diameter D is 100 mm, and the shape, number and rotation speed of the blower blades are optimized to ensure that sufficient air volume and wind speed can be generated under rated voltage and current to effectively cool the radiator and take away the heat from the hot end of the thermopile.

[0012] Preferably, the energy storage device is a storage battery, and its charging methods include charging by generating electricity through piezoelectric fiber sheets during the driving process of the vehicle and charging by using household alternating current; and a voltage stabilizing device is provided in the power supply connection circuit between the storage battery and the vehicle-mounted refrigerator to ensure stable power supply to the vehicle-mounted refrigerator when the vehicle stops or travels slowly and maintain the stable temperature inside the refrigerator.

[0013] Preferably, the inner liner size of the vehicle-mounted refrigerator is designed according to the refrigerating capacity and usage requirements. The inner liner is 0.32 m wide, 0.38 m deep and 0.40 m high, and the inner liner material is made of a material with a low thermal conductivity coefficient to reduce cold loss and improve the refrigeration efficiency.

[0014] Preferably, the entire system further includes a temperature collector and a microprocessor. The temperature collector is used to collect the internal temperature of the refrigerator and the temperature of the hot end of the thermopile in real time and transmit the temperature data to the microprocessor; the microprocessor calculates the balanced temperature according to the temperature data and automatically adjusts the working current of the thermopile to achieve precise control of the temperature of the vehicle-mounted refrigerator.

[0015] (III) Beneficial effects Compared with the prior art, the present invention provides a vehicle pressure power generation-driven vehicle-mounted refrigerator system based on the piezoelectric effect, which has the following beneficial effects: 1. The vehicle pressure power generation-driven vehicle-mounted refrigerator system based on the piezoelectric effect constructs a power generation system by utilizing the vehicle's own pressure and the piezoelectric effect, converts the mechanical energy during the driving process of the tire into electrical energy to supply power to the vehicle-mounted refrigerator, realizes the effective combination of vehicle tire power generation and vehicle-mounted refrigerator energy supply, reduces the energy conversion link, improves the energy utilization rate, and conforms to the concept of sustainable development.

[0016] 2. The vehicle pressure power generation-driven vehicle-mounted refrigerator system based on the piezoelectric effect can continue to provide energy for the vehicle-mounted refrigerator when the vehicle stops driving through the designed energy storage device, ensuring the continuity and stability of the refrigerator cooling and meeting the user's usage requirements for the vehicle-mounted refrigerator.

[0017] 3. The vehicle pressure power generation-driven vehicle-mounted refrigerator system based on the piezoelectric effect is not only applicable to traditional fuel vehicles but also can be applied to new energy vehicle models through this design. At present, when new energy vehicles are popularized, no additional energy supply is required, which helps to reduce the vehicle energy consumption. Moreover, the vehicle-mounted refrigerator can meet people's needs for food refrigeration or beverage freezing during travel, and the hot end can be transformed into a heating unit in winter, improving the economy and practicality of the vehicle. Brief Description of the Drawings

[0018] Figure 1 This is a schematic diagram of the principle of the present invention; Figure 2 This is a schematic diagram of the structure of the piezoelectric fiber sheet of the present invention; Figure 3 This is a schematic diagram showing the parameters of the piezoelectric fiber sheet M-568-P2 of the present invention; Figure 4 This is a schematic diagram of the generated voltage when the tire of the present invention is working; Figure 5 This is a schematic diagram of the components for thermoelectric refrigeration semiconductor of the present invention; Figure 6 This is a schematic diagram of the structure of the thermoelectric refrigeration device of the present invention; Figure 7 This is a schematic diagram of the overall structure of the radiator of the present invention; Figure 8 This is a schematic diagram of a partial structure of the radiator of the present invention; Figure 9 This is a schematic diagram of the structure of the fan of the present invention; Figure 10 This is a schematic diagram of the structure of the box body of the present invention; Figure 11 This is a schematic diagram of the process of electric energy rectification of the present invention; Figure 12 This is a schematic diagram of the standard AC-DC energy harvesting circuit of the present invention; Figure 13 This is a schematic diagram of the bonding situation of the piezoelectric fiber sheet in the tire of the present invention. Detailed Description of the Preferred Embodiment

[0019] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0020] Please refer to Figures 1-13 , the present invention provides a technical solution: an automotive pressure power generation-driven in-vehicle refrigerator system based on the piezoelectric effect, including a differential pressure power generation system, a thermoelectric refrigeration system, and an electric energy collection and management system: Pressure difference power generation system: using the pulse pressure generated by the gravity of the automobile tire during driving, the mechanical energy is converted into electrical energy based on the piezoelectric effect; the pressure difference power generation system comprises a piezoelectric fiber sheet made of composite piezoelectric material, the piezoelectric fiber sheet has a five-layer structure, from the outside to the inside, the upper and lower plastic protective layers, the electrode layer and the middle piezoelectric film layer, which are used to generate electrical energy; it also comprises a full-wave rectifier circuit, which is used to convert the alternating current generated by the piezoelectric fiber sheet into direct current; Thermoelectric refrigeration system: uses semiconductor thermocouples as the basic refrigeration unit, the semiconductor thermocouples are composed of P-type semiconductors (bismuth telluride-antimony telluride solid solution alloy) and N-type semiconductors (bismuth telluride-bismuth selenide solid solution alloy); multiple semiconductor thermocouples are connected to form a thermopile, the thermopile adopts a series structure and is separated by a heat-conducting electrical insulation layer; the system is equipped with a cold plate for exporting cold, a radiator for hot end heat dissipation, and a fan for cooling the radiator; Electric energy collection and distribution system: according to the power load demand, 6 groups of piezoelectric fiber sheets with a single power of 3W are evenly distributed on each of the four tires of the car; part of the rectified and filtered electric energy is used to provide power consumption for the thermoelectric refrigeration semiconductor, so that the cold plate generates cold energy to supply cooling to the car refrigerator, and the other part is used to drive the fan to cool the hot end of the thermopile; an energy storage device is provided to supply power to the car refrigerator when the car stops or the piezoelectric fiber sheet generates insufficient power.

[0021] In the present invention, in order to improve the performance of the entire automobile pressure power generation driven car refrigerator system based on the piezoelectric effect, the distribution of the piezoelectric fiber sheets on the tire is arranged to be evenly distributed on the principle of ensuring maximum contact with the tire deformation area, and the installation position and angle are optimized so that the piezoelectric fiber sheets can generate maximum mechanical stress when the tire is deformed, thereby improving the power generation efficiency.

[0022] In the present invention, in order to avoid the unstable refrigeration capacity caused by voltage fluctuation and ensure the constant temperature in the vehicle refrigerator, a full-wave rectifier circuit is set to convert the half-cycle waveform with negative polarity in the alternating current generated by the piezoelectric fiber sheet into a positive half-cycle waveform through a bridge circuit structure composed of at least four diodes, so as to realize the conversion of alternating current to direct current, and filter the converted direct current through a filter capacitor to output a stable direct current voltage. The full-wave rectification is performed by using a bridge circuit structure composed of at least four diodes, which can convert the half-cycle waveform with negative polarity in the alternating current generated by the piezoelectric fiber sheet into a positive half-cycle waveform, so as to realize efficient conversion of alternating current to direct current. Compared with half-wave rectification, full-wave rectification utilizes all cycles of alternating current, and the average value of the output direct current voltage is higher. In the vehicle refrigerator system, a stable direct current voltage is crucial to the stable operation of the thermoelectric refrigeration system. The stable voltage can ensure the stability of the working current of the thermopile, stabilize the refrigeration effect, avoid the instability of the refrigeration capacity caused by voltage fluctuation, and ensure the constant temperature in the vehicle refrigerator.

[0023] In the present invention, in order to ensure the refrigerating capacity and meet the usage requirements, a thermopile is provided and composed of 71 pairs of thermocouples. With 7 pairs in a row, there are a total of 10 rows arranged. Moreover, the connection modes between the thermocouples in each row and between the thermocouples in each column are designed to ensure uniform current distribution during the operation of the thermopile, so that the refrigeration effects of each thermocouple are consistent. The thermopile is composed of 71 pairs of thermocouples, with 7 pairs in a row and a total of 10 rows arranged. Such a quantity and arrangement design are precisely calculated based on the refrigerating capacity requirements of the system. In a vehicle-mounted refrigerator system, to achieve rapid refrigeration and maintain a low-temperature environment, sufficient refrigerating capacity is required. The 71 pairs of thermocouples work together to generate a powerful refrigeration effect. Compared with the situation where the number of thermocouples is small, it can reduce the temperature inside the refrigerator more rapidly, meeting the requirements of users for the refrigeration speed and refrigeration effect of the vehicle-mounted refrigerator. Whether it is refrigerating food or freezing beverages, it can be efficiently completed.

[0024] In the present invention, in order to ensure the heat transfer efficiency, electrical insulation performance, as well as the system stability and reliability, a thermally conductive electrical insulation layer is provided and made of materials such as beryllium oxide by anodic oxidation and aluminum oxide. On the premise of meeting the electrical insulation performance, its thickness is as thin as possible, and the specific thickness range is from [X1] millimeters to [X2] millimeters, so as to reduce the additional thermal resistance and additional temperature difference between the thermopile node and the heat exchanger. The electrical insulation layer is made of materials such as beryllium oxide by anodic oxidation and aluminum oxide, and these materials have the characteristic of high thermal conductivity. In a thermoelectric refrigeration system, the heat transfer efficiency is crucial for the system performance. The heat generated at the hot end of the thermopile needs to be rapidly transferred to the radiator for dissipation, and the cold quantity at the cold end also needs to be efficiently exported to refrigerate the refrigerator. Materials such as beryllium oxide by anodic oxidation and aluminum oxide can enable rapid heat conduction, reduce the thermal resistance, accelerate the heat transfer speed, and improve the refrigeration efficiency. Compared with materials with poor thermal conductivity, it can make the vehicle-mounted refrigerator reach the set temperature faster and maintain a stable refrigeration effect during operation, avoiding refrigeration delay or temperature fluctuation caused by poor heat transfer.

[0025] In the present invention, in order to improve the heat dissipation performance and overall operating efficiency of the system, the radiator is set to an aluminum flat fin structure, whose dimensions are precisely 50mm long, 30mm wide, and 2mm thick. The total number of fins is 45, which are evenly arranged in 3 rows, with 15 fins in each row, and the shape and spacing of the fins are optimized to improve the heat dissipation efficiency and enhance the heat exchange capacity between the air and the radiator. The aluminum flat fin structure is adopted, and the thermal conductivity of aluminum is good, which can quickly conduct the heat from the hot end of the thermopile. The 50mm×30mm×2mm size design, combined with the 45 fins in 3 rows, 15 fins in each row, greatly increases the contact area between the radiator and the air. According to the principle of heat exchange, the larger the contact area, the better the heat dissipation effect. A large number of fins provide more paths for heat transfer, so that the air can more fully exchange heat with the radiator, quickly take away the heat, effectively reduce the temperature of the hot end of the thermopile, ensure the stable operation of the thermoelectric refrigeration system, and then maintain the refrigeration effect of the car refrigerator.

[0026] In the present invention, in order to ensure the stability of the temperature of the hot end of the thermopile and maintain the refrigeration performance of the vehicle refrigerator, the fan model is set to DC4V / 1.5A, the outer diameter D is 100mm, and the blade shape, number and speed of the fan are optimized to ensure that under the rated voltage and current, sufficient air volume and wind speed can be generated to effectively cool the radiator and take away the heat of the hot end of the thermopile. The electrical parameters of DC4V / 1.5A are precisely matched with the power consumption and voltage requirements of the thermoelectric refrigeration system. The heat generated by the hot end of the thermopile needs to be dissipated in time. This model of fan operates under the rated voltage and current and can provide stable and appropriate power to drive the fan to operate. The 100mm outer diameter design, combined with the optimized blade shape, number and speed, makes the air volume and wind speed generated by the fan just meet the heat dissipation requirements of the radiator. While ensuring the heat dissipation effect, it can avoid insufficient heat dissipation or energy waste caused by excessive or too small air volume, ensure the stability of the temperature of the hot end of the thermopile, and maintain the refrigeration performance of the vehicle refrigerator.

[0027] In the present invention, in order to ensure the continuous operation of the refrigerator and avoid problems such as food spoilage caused by power supply interruption, an energy storage device is set as a storage battery. Its charging methods include charging by generating electricity through piezoelectric fiber sheets during the driving process of the vehicle and charging using household alternating current. And a voltage stabilizing device is provided in the power supply connection circuit between the storage battery and the in-vehicle refrigerator to ensure stable power supply to the in-vehicle refrigerator when the vehicle stops or travels at a low speed, maintaining the stable temperature inside the refrigerator. The driving state of the vehicle is not constant. During the driving process, the power generation of the piezoelectric fiber sheets is affected by factors such as the degree of tire deformation and driving speed. When the vehicle stops, the piezoelectric fiber sheets no longer generate electrical energy; when driving at a low speed, the power generation may be insufficient. The existence of the energy storage device (storage battery) is like an "energy buffer pool". When the vehicle is driving normally and the power generation of the piezoelectric fiber sheets is sufficient, the storage battery stores the excess electrical energy; when the power generation is insufficient or stops, the storage battery supplies power to the in-vehicle refrigerator to ensure the continuous operation of the refrigerator and avoid problems such as food spoilage caused by power supply interruption.

[0028] In the present invention, in order to keep the in-vehicle refrigerator at a stable low temperature with limited energy and improve the energy utilization efficiency, the inner liner size of the in-vehicle refrigerator is designed according to the refrigerating capacity and usage requirements. The width of the inner liner is 0.32 m, the depth is 0.38 m, and the height is 0.40 m. The material of the inner liner is a material with a low thermal conductivity coefficient to reduce the loss of cold quantity and improve the refrigeration efficiency. The inner liner size of 0.32 m in width, 0.38 m in depth, and 0.40 m in height is precisely designed based on the refrigerating capacity and usage requirements. Such a size can ensure full contact between the inner liner and the cold plate of the thermoelectric refrigeration system, realizing efficient cold quantity transfer. The reasonable space size is also conducive to the uniform circulation of cold air inside, reducing the temperature stratification phenomenon, making the temperature in each area inside the refrigerator more uniform, thereby improving the overall refrigeration effect and better meeting the needs of refrigerating or freezing items. Using a material with a low thermal conductivity coefficient for the inner liner can effectively reduce the loss of cold quantity. When the inside of the refrigerator is refrigerated, the low-thermal-conductivity material can prevent heat from entering from the outside, reducing the energy consumption of the refrigeration system, keeping the in-vehicle refrigerator at a stable low temperature with limited energy, and improving the energy utilization efficiency.

[0029] In the present invention, in order to better preserve food, extend the freshness period, and enhance the user experience, the entire system is further provided with a temperature collector and a microprocessor. The temperature collector is used to collect the temperature inside the refrigerator and the temperature of the hot end of the thermoelectric pile in real time, and transmit the temperature data to the microprocessor; the microprocessor calculates the balanced temperature based on the temperature data and automatically adjusts the working current of the thermoelectric pile to achieve precise control of the temperature of the in-vehicle refrigerator. The temperature collector collects the temperature inside the refrigerator and the temperature of the hot end of the thermoelectric pile in real time, providing accurate data support for the microprocessor. The microprocessor then calculates the balanced temperature and automatically adjusts the working current of the thermoelectric pile. For example, when the temperature inside the refrigerator rises, the microprocessor increases the current of the thermoelectric pile to enhance refrigeration; when the temperature drops, the current is reduced to avoid over-refrigeration. This intelligent adjustment keeps the temperature inside the refrigerator near the set value with minimal fluctuations. Precise temperature control can better preserve food, extend the freshness period, and enhance the user experience.

[0030] General design principle: During the driving process of the vehicle, the engine power is transmitted to the tires, causing the tires to deform when they come into contact with the ground. The present invention utilizes piezoelectric elements to collect the energy generated by this part of the tire deformation. The piezoelectric elements work based on the piezoelectric effect. When subjected to an external force and deformed, polarization occurs inside them, with equal amounts of opposite charges generated on the surface, thus generating electrical energy. The generated electric power is first rectified by a rectifier circuit to charge a super capacitor. When the capacitor voltage reaches a certain value, it powers the in-vehicle refrigerator through a voltage stabilization rectifier circuit and charges the refrigerator battery. When the vehicle stops running, the battery powers the in-vehicle refrigerator, and the battery can also be charged using household alternating current, solving the problem that the refrigerator cannot refrigerate when the vehicle engine stalls.

[0031] (I) Differential pressure power generation system: 1. Design principle: The piezoelectric effect was discovered by Jaques and Pierre Curie in 1880. Certain crystal materials (such as quartz, tourmaline, and sodium potassium tartrate) have piezoelectric properties, and these crystals need to be asymmetric. When the crystal is subjected to tensile stress or compressive stress, the spacing between the positive and negative charge sites inside the crystal changes, resulting in polarization on the crystal surface and generating electrical energy. Piezoelectric materials have the direct piezoelectric effect and the inverse piezoelectric effect. Under the direct piezoelectric effect, an external force deforms the piezoelectric material to generate charges, and the amount of charge is related to the external force and the material area. The formula is

[0032]

[0033] , The inverse piezoelectric effect refers to the phenomenon that when a voltage is applied to the electrodes of a piezoelectric material, the length or thickness of the material changes. After the voltage is removed, the material returns to its original state. When an alternating current is applied, the change speed is related to the frequency, and the change amplitude is related to the voltage magnitude. In the present invention, the direct piezoelectric effect is utilized to generate electrical energy from a piezoelectric material under the pressure of an automobile tire.

[0034] 2. Materials for design: Piezoelectric materials are divided into organic piezoelectric materials, inorganic piezoelectric materials, composite piezoelectric materials, and dielectric elastomers. Piezoelectric crystals in inorganic piezoelectric materials generally refer to piezoelectric single crystals, and piezoelectric ceramics refer to piezoelectric polycrystals. Piezoelectric ceramics have strong piezoelectric properties but are easily damaged in the environment of large tire deformations and are not suitable for the present invention. Organic piezoelectric materials such as polyvinylidene fluoride (PVDF) have characteristics such as low density, low impedance, high piezoelectric constant, and high flexibility. Composite piezoelectric materials are made by installing rod-shaped, powder-shaped, or sheet-shaped piezoelectric materials in an organic polymer substrate and have excellent performance. Dielectric elastomers are new functional materials. Among them, the electric-field-type DE materials have high energy density, large strain, low price, small mass, and have been commercialized. Considering the deformation characteristics of tire operation, the present invention selects composite piezoelectric materials; The piezoelectric fiber sheet adopted in the present invention is a composite piezoelectric material, and its structure includes five layers. The upper and lower layers are plastic protective layers, whose function is to protect the internal electrode layer and piezoelectric thin film layer; in the middle is the piezoelectric thin film layer, which is responsible for generating electrical energy under pressure; the two electrode layers are located between the plastic protective layer and the piezoelectric thin film layer, and their main function is to conduct the charges generated by the piezoelectric thin film layer to the outside. The MFC piezoelectric thin film is composed of rectangular piezoelectric ceramic rods sandwiched between the upper and lower electrodes and the upper and lower protective layers by adhesives. The piezoelectric ceramic fiber rods are specially processed from PZT piezoelectric ceramics. This piezoelectric fiber sheet has high sensitivity and stability, a long service life, and a wide range of applicable environments; it has good toughness, a soft texture, a wide response frequency, and a small measurement error; it can be made into any shape, has a simple structure, a small mass, and a low cost.

[0035] 3. Selection and parameter determination of the piezoelectric fiber sheet: The M-5628-P2 model piezoelectric fiber sheet is selected for the experiment. Its overall dimensions are 66mm×31mm×0.6mm, and the specific parameters are as Figure 3 . The voltage generated by this piezoelectric fiber sheet is tested experimentally at different vehicle speeds and air pressures. At a tire speed of 10 kilometers per hour and normal air pressure, the maximum voltage is 3.2V, and at half air pressure, it is 6.2V; at a tire speed of 20 kilometers per hour and normal air pressure, the maximum voltage is 5V, and at half air pressure, it is 8.2V. Considering the driving safety of the vehicle, 5V is selected as the maximum voltage. To meet the power requirements of the in-vehicle refrigerator and related equipment, 6 groups of this model piezoelectric fiber sheets are evenly distributed on each of the 4 tires.

[0036] (2) Thermoelectric refrigeration system: 1. Design principle: When an electric current flows through the interface of two different conductors, such asFigure 5 As shown in the figure, energy is absorbed from the outside world or released to the outside world. Experiments show that the heat transfer at the contact point is proportional to the current, that is (1) In the formula, Q—the heat transfer at the contact point, unit: W πab—the proportionality constant, called the Peltier coefficient, unit: W / A I—the current in the circuit, unit: A According to the refrigeration principle, when current passes through the thermocouple pair, Joule heat will also be released inside the thermoelectric element. The Joule heat is proportional to the square of the current, that is: (2) Calculation shows that half of the Joule heat is transferred to the cold end of the thermoelectric element, resulting in a reduction in the thermoelectric refrigeration effect.

[0037] Due to the heat conduction of the semiconductor, a certain amount of heat will also be transferred from the hot end of the stack to the cold end: (3) According to formulas (1), (2), and (3), the refrigerating capacity of the thermoelectric refrigeration unit: (4) When the thermocouple pair is working, the power supply has to do work on the resistance and overcome the thermoelectric potential, so the power consumed is: (5) From formulas (4) and (5), the coefficient of performance can be obtained: (6) The heat generation of the thermoelectric heating unit: (7) In the above formulas, α—the relative Seebeck coefficient of two semiconductor materials, unit: V / K I—the working current in the circuit, unit: A Th, Tc—the high-temperature state temperature, low-temperature state temperature, unit: K R—the total resistance of the thermocouple unit, unit: Ω K—the thermal conductivity of the thermocouple, unit: W / K The Peltier effect and the Seebeck effect are both thermoelectric effects and are closely related. In fact, they are reciprocal effects. One is that an electromotive force will be generated when there is a temperature difference in the thermocouple, and the other is that a temperature difference will be generated when there is current passing through the thermocouple. There is the following direct relationship between the thermoelectric potential α and the Peltier coefficient π: (8) In the formula, T—the temperature at the node, unit: K.

[0038] 2. Design materials: Since the Peltier effect of conductors is much stronger than that of ordinary metal thermocouples and can exhibit an obvious refrigeration effect at the cold junction, the basic unit of the thermoelectric cooler in this design is a semiconductor thermocouple. One of the materials forming the thermocouple is a P-type semiconductor (hole type), and the other is an N-type semiconductor (electron type). The thermopile is designed according to the principle of optimizing the refrigeration performance number, with high energy conversion efficiency, low power consumption, and less heat dissipation at the hot end. The domestic ternary bismuth telluride-antimony telluride solid solution alloy, which is relatively mature in application, is adopted in this design. The P-type material is bismuth telluride-antimony telluride (Bi2Te3 - Sb2Te3) solid solution alloy; the N-type material is bismuth telluride-bismuth selenide (Bi2Te3 - Bi2Sc3), and the figure of merit is maintained at 4×10-3 near 200K. The specific parameters can be seen in Table 1.

[0039] Table 1 Ternary bismuth telluride-antimony telluride solid solution alloy

[0040] 3. Structural design: In thermoelectric refrigeration, since the refrigeration capacity of a pair of basic thermocouples is very small, in actual use, in order to meet the specified cooling capacity, many thermocouples need to be connected into a thermopile. 71 pairs of thermocouples are used for refrigeration in this design, with 7 pairs in a row and a total of 10 rows distributed. The refrigeration equipment mainly consists of a thermopile, a thermally conductive electrical insulation layer, a cold plate, and a radiator, as Figure 6 shown, Figure 6 where: 1 - cold plate, 2 - thermally conductive electrical insulation layer, 3 - metal plate, 4 - radiator.

[0041] According to the design working conditions, the cold end is designed to be 5°C and the hot end is designed to be 60°C. According to △T = 55°C, the thermopile uses first-stage refrigeration and is of a series type. The working current is equal everywhere, and at the same time, it is separated by an electrical insulation layer. The materials generally used are beryllium oxide by anodization, alumina, etc. It is required that the thermal conductivity of this insulation layer is large.

[0042] The cold plate plays the role of conducting the cooling capacity. The cold plate should maintain good thermoelectric contact with the object to be cooled, and the contact surface has good thermal conductivity and electrical insulation.

[0043] The radiator plays the role of heat dissipation at the hot end and uses automotive air exhaust cooling. The radiator can be made into a surface with fins, and the fin type is sheet-like. As Figure 8 shown, this design is an aluminum flat fin, with dimensions of 50mm × 30mm × 2mm. There are a total of 45 fins, divided into 3 rows, with 15 fins in each row.

[0044] In order to enable the heat of the nodes on the same side to be concentrated on the metal plate (cold plate or radiator), while ensuring the electrical isolation between each thermocouple element, a layer of heat-conducting but non-conductive material is used to separate the cold end of the thermopile from the cold plate and the hot end of the thermopile from the radiator. This layer is the heat-conducting electrical insulation layer. Mica sheets, painted layers, or non-conductive metal oxide films can all be used as materials for the heat-conducting electrical insulation layer. The smaller the thickness of this layer, the better, because it is sandwiched between the thermopile nodes and the heat exchanger, which will generate additional thermal resistance and additional temperature difference. Usually, the additional temperature difference caused by each layer is above 2K.

[0045] The fan cools the radiator, takes away the heat, and cools the hot end of the thermopile. According to experience, a DC4V / 1.5A fan with an outer diameter D of 100mm is selected. The structure is as Figure 9 shown.

[0046] According to the refrigerating capacity and the calculation formula of the refrigerator's cold load, determine the relationship between the refrigerating capacity and the width, depth, and height of the refrigerator inner liner; select the thickness of the insulating layer for each surface, set the width and depth of the refrigerator according to the installation position, and finally calculate the height of the refrigerator according to the listed relationship. Considering the convenience of storing items, the width of the inner liner is taken as 0.32m, and the depth of the inner liner is 0.38m. It is calculated that H = 0.47m, and H = 0.40 is taken. The structure is as Figure 10 shown.

[0047] (III) Electric energy collection system: The refrigerating thermopile we selected needs to use direct current during operation, but the piezoelectric fiber sheet presents a periodic change under normal working conditions of the tire. We need to rectify the extracted electric energy before it can be used by the thermopile. The process of rectifying the electric energy of the piezoelectric fiber sheet is as Figure 11 shown.

[0048] We use a full-wave rectifier circuit to rectify and filter the electric energy generated by the piezoelectric fiber sheet. The full-wave rectifier circuit changes all the half-cycles with negative polarity in the input waveform through diodes, and uses a standard AC-DC collection circuit for rectification and filtering.

[0049] The piezoelectric fiber sheet generates electric energy due to the deformation of the grounded footprint area. Through the AC-DC rectifier circuit and the filter capacitor, the DC voltage can be flattened. The diagram of the standard AC-DC energy collection circuit is as Figure 12 shown.

[0050] The power of the thermocouple we selected is 58w and the total resistance is 0.31Ω, and the power of the fan is 6w. The total power is 78w. The single-piece power of the piezoelectric fiber sheet is 3w.

[0051] In order to meet the power requirements, we need to evenly distribute 6 groups of fiber sheets on each of the 4 tires. As Figure 13 shown.

[0052] During use: (1) Installation and commissioning of the pressure difference power generation system: Before installing the piezoelectric fiber sheets on the tires, it is necessary to clean the installation area on the inner wall of the tires to ensure that the surface is flat, dry, and free of impurities, so as to ensure firm adhesion of the piezoelectric fiber sheets; Use special adhesives to paste the piezoelectric fiber sheets of model M-5628-P2 on 4 tires, with 6 groups evenly distributed on each tire according to the design requirements. During the pasting process, pay attention to avoiding the generation of air bubbles to ensure full contact between the piezoelectric fiber sheets and the inner wall of the tires; Connect the electrodes of the piezoelectric fiber sheets to the full-wave rectifier circuit, ensure firm connection and good contact, and avoid energy loss and instability caused by loose connection; After the installation is completed, conduct a preliminary test, simulate the driving state of the vehicle, and detect the power generation of the piezoelectric fiber sheets, such as whether the voltage output is normal. Adjust the installation position or connection slightly according to the test results.

[0053] (2) Assembly and commissioning of the thermoelectric refrigeration system: Connect 71 pairs of thermocouples into a thermopile according to the design requirements. Pay attention to the connection sequence and direction to ensure correct series connection and equal working current everywhere; Install a cold plate and a radiator at the cold end and the hot end of the thermopile respectively. The cold plate is closely attached to the cold end of the thermopile to ensure effective conduction of cold; the radiator is installed firmly to ensure smooth air circulation; Install a thermally conductive electrical insulation layer, such as beryllium oxide or alumina film, between the cold end of the thermopile and the cold plate, and between the hot end of the pile and the radiator. Pay attention to the uniform and as thin as possible thickness of the insulation layer to reduce thermal resistance and temperature difference; Install a fan, connect the fan to the radiator, ensure the correct position of the fan, and be able to effectively cool the radiator. Connect the power supply of the fan and test the operation of the fan to check whether the wind speed meets the heat dissipation requirements; Install the entire thermoelectric refrigeration system at a suitable position inside the vehicle-mounted refrigerator to ensure good contact between the cold plate and the inner liner of the refrigerator to ensure the refrigeration effect; (3) Connection and testing of the electric energy collection and distribution system: Connect the direct current output by the full-wave rectifier circuit to the power supply interface of the thermoelectric refrigeration system to ensure correct connection of the positive and negative poles; Connect the storage battery so that it can supply power to the vehicle-mounted refrigerator when the vehicle stops running. At the same time, set up a charging circuit so that the storage battery can be charged using household alternating current; Conduct an overall system test, start the vehicle, simulate different driving conditions, and monitor the power generation of the piezoelectric fiber sheets, the refrigeration effect of the thermoelectric refrigeration system, and the charge and discharge status of the storage battery. According to the test results, adjust the system parameters, such as checking whether the connections of all components are normal to ensure the stable operation of the entire system.

[0054] Through the above detailed design, installation, and debugging processes, the in-vehicle refrigerator system based on the piezoelectric effect of automobile tires of the present invention can achieve efficient energy harvesting and stable refrigeration functions, providing a more convenient and energy-saving usage experience for automobile users.

[0055] Electricity is generated based on the piezoelectric principle, and electrical energy is obtained by utilizing the energy of tire deformation when the vehicle is in motion. This energy directly powers the semiconductor refrigerator, reducing the energy conversion link and combining the piezoelectric effect with the energy supply of the in-vehicle refrigerator. To achieve continuous and stable refrigeration of the refrigerator, an energy storage device is provided. The energy storage device can stably supply electrical energy to the refrigerator when the vehicle stops or travels at a low speed.

[0056] Automobiles are becoming increasingly popular in cities. With the development of society, more and more people in China are buying private cars. Automobiles serve as the means of transportation for office workers. At the same time, with the continuous improvement of life, in-vehicle refrigerators are bound to become more and more popular, and thermoelectric refrigeration is more likely to replace traditional refrigeration methods. If this design is configured on automobiles, it will bring great benefits. On the one hand, this design can also be applied to new energy vehicle models, which is particularly important in the current era of the popularization of new energy vehicles. Ordinary in-vehicle air conditioners require additional power supply from the vehicle, while this design does not require additional energy supply. On the other hand, in-vehicle refrigerators can carry food stored at low temperatures, or people can drink frozen beverages in the hot summer, which is convenient and serves the people. In winter, the hot end can also be transformed into a heating unit, reducing the economic burden brought by heating and increasing the economy of the vehicle.

[0057] The dimensions and shapes of all components in this structure are not specifically limited here and need to be produced according to the actual situation.

[0058] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An automotive pressure power generation-driven in-vehicle refrigerator system based on the piezoelectric effect, characterized in that: Including pressure difference power generation system, thermoelectric cooling system and power collection and management system: Pressure difference power generation system: using the pulse pressure generated by the gravity of the automobile tire during driving, the mechanical energy is converted into electrical energy based on the piezoelectric effect; the pressure difference power generation system comprises a piezoelectric fiber sheet made of composite piezoelectric material, the piezoelectric fiber sheet has a five-layer structure, from the outside to the inside, the upper and lower plastic protective layers, the electrode layer and the middle piezoelectric film layer, which are used to generate electrical energy; it also comprises a full-wave rectifier circuit, which is used to convert the alternating current generated by the piezoelectric fiber sheet into direct current; Thermoelectric refrigeration system: uses semiconductor thermocouples as the basic refrigeration unit, the semiconductor thermocouples are composed of P-type semiconductors and N-type semiconductors; multiple semiconductor thermocouples are connected to form a thermopile, the thermopile adopts a series structure and is separated by a heat-conducting electrical insulation layer; the system is equipped with a cold plate for exporting cold, a radiator for hot end heat dissipation, and a fan for cooling the radiator; Power collection and distribution system: Based on the power load demand, 6 sets of piezoelectric fiber sheets with a single power of 3W are evenly distributed on each of the four tires of the car; Part of the rectified and filtered electric energy is used to provide power consumption for the thermoelectric refrigeration semiconductor, so that the cold plate generates cold energy to provide cooling for the car refrigerator, and the other part is used to drive the fan to cool the hot end of the thermopile. An energy storage device is provided to supply power to the car refrigerator when the car stops or the piezoelectric fiber sheet does not generate enough electricity.

2. The vehicle pressure power generation-driven vehicle-mounted refrigerator system based on the piezoelectric effect according to claim 1, wherein: The piezoelectric fiber sheets are distributed on the tire in a uniform manner to ensure maximum contact with the tire deformation area, and their installation position and angle are optimized so that the piezoelectric fiber sheets can generate maximum mechanical stress when the tire is deformed, thereby improving power generation efficiency.

3. The vehicle pressure power generation-driven vehicle-mounted refrigerator system based on the piezoelectric effect according to claim 1, characterized in that: The full-wave rectifier circuit converts the negative polarity half-cycle waveform in the alternating current generated by the piezoelectric fiber sheet into a positive half-cycle waveform through a bridge circuit structure composed of at least four diodes, thereby realizing the conversion of alternating current to direct current, and filters the converted direct current through a filter capacitor to output a stable direct current voltage.

4. The vehicle pressure power generation-driven vehicle-mounted refrigerator system based on the piezoelectric effect according to claim 1, characterized in that: The thermopile is composed of 71 pairs of thermocouples, which are arranged in 10 rows with 7 pairs in a row. The connection method between the thermocouples in each row and between the thermocouples in each column is designed to ensure that the current is evenly distributed when the thermopile is working and the cooling effect of each thermocouple is consistent.

5. The vehicle pressure power generation-driven vehicle-mounted refrigerator system based on the piezoelectric effect according to claim 1, wherein: The heat-conductive electrical insulating layer is made of materials such as anodized beryllium oxide and aluminum oxide, and its thickness is as thin as possible while meeting the electrical insulation performance. The specific thickness range is [X1] mm to [X2] mm to reduce the additional thermal resistance and additional temperature difference between the battery stack node and the heat exchanger.

6. The vehicle pressure power generation-driven vehicle-mounted refrigerator system based on the piezoelectric effect according to claim 1, characterized in that: The radiator is an aluminum flat fin structure with precise dimensions of 50 mm in length, 30 mm in width and 2 mm in thickness. There are 45 fins in total, which are evenly arranged in 3 rows, with 15 fins in each row. The shape and spacing of the fins are optimized to improve the heat dissipation efficiency and enhance the heat exchange capacity between the air and the radiator.

7. The vehicle pressure power generation-driven vehicle-mounted refrigerator system based on the piezoelectric effect according to claim 1, characterized in that: The model of the fan is DC4V / 1.5A, and its outer diameter D is 100mm. The shape, number and rotation speed of the fan blades are optimized to ensure that sufficient air volume and wind speed can be generated under the rated voltage and current, effectively cooling the radiator and taking away the heat from the hot end of the thermopile.

8. The vehicle pressure power generation-driven vehicle-mounted refrigerator system based on the piezoelectric effect according to claim 1, characterized in that: The energy storage device is a storage battery, and its charging methods include charging through piezoelectric fiber sheets during vehicle driving and charging using household alternating current; and a voltage stabilizing device is provided in the power supply connection circuit between the storage battery and the in-vehicle refrigerator to ensure stable power supply for the in-vehicle refrigerator and maintain the temperature stability inside the refrigerator when the vehicle stops or drives slowly.

9. The vehicle pressure power generation driven vehicle-mounted refrigerator system based on the piezoelectric effect according to claim 1, characterized in that: The inner liner size of the in-vehicle refrigerator is designed according to the cooling capacity and usage requirements. The inner liner is 0.32m wide, 0.38m deep and 0.40m high. The inner liner material is made of a material with a low thermal conductivity coefficient to reduce cold loss and improve the refrigeration efficiency.

10. The vehicle pressure power generation-driven vehicle-mounted refrigerator system based on the piezoelectric effect according to claim 1, characterized in that: The entire system also includes a temperature collector and a microprocessor. The temperature collector is used to collect the internal temperature of the refrigerator and the temperature of the hot end of the thermopile in real time and transmit the temperature data to the microprocessor; the microprocessor calculates the balanced temperature based on the temperature data and automatically adjusts the working current of the thermopile to achieve precise control of the temperature of the in-vehicle refrigerator.

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