A containerized relative constant temperature liquid storage and automatic vending system and its control method

Abstract

This invention discloses a containerized relative constant temperature liquid storage and automatic vending system and its control method. The relative constant temperature refers to the system dynamically selecting a seasonal target temperature range based on the outdoor temperature, rather than maintaining an absolutely constant low temperature. It includes a containerized shell, a 316L stainless steel tank (1), an insulation layer (2), a temperature control unit (3), and an automatic vending unit. The temperature control unit includes a semiconductor cooling / heating module, an internal temperature sensor (4), an outdoor temperature sensor (10), and a controller (9). The controller automatically switches the seasonal relative constant temperature target temperature range based on the outdoor temperature: 19℃±2℃ in summer (triggered at ≥21℃), 7℃±2℃ in winter (triggered at ≤9℃), 15℃±2℃ in spring, and 17℃±2℃ in autumn. Precise temperature control is achieved through a dual-channel control structure of PID feedback control and outdoor temperature feedforward compensation, and hysteresis control and target temperature smooth transition functions are configured. The automated vending unit includes a barcode scanning module (5), a flow meter (6), a solenoid valve (7), and a water outlet (8). It manages the entire process of barcode scanning, payment, and metering dispensing through a transaction state machine, and is equipped with functions for resuming data transmission after network outages and timeout protection. This invention achieves integrated functionality for safe storage of large-capacity drinking water, intelligent relative temperature control, and unmanned automated vending, making it suitable for mass water sales scenarios such as communities, construction sites, and scenic areas.

Description

Technical Field

[0001] This invention relates to the field of liquid storage and vending equipment technology, specifically to a containerized relatively constant-temperature liquid storage and automatic vending system and its control method, which is particularly suitable for the batch, unmanned, and relatively constant-temperature preservation and vending of liquids such as spring water, drinking water, and edible oil. The "relative constant temperature" refers to the system dynamically selecting a seasonal target temperature range based on the outdoor temperature, rather than maintaining an absolutely constant low temperature. Background Technology

[0002] In the bulk storage and unmanned vending of liquids (such as spring water, drinking water, and cooking oil), the following technical problems exist: First, there are issues regarding the safety and hygiene of storage containers. Traditional storage tanks are made of inconsistent materials; some materials may pose a risk of leaching harmful substances during long-term storage, or lack sufficient corrosion resistance, affecting liquid quality and safety. Although food-grade stainless steel is used in some water storage equipment, it has not yet been effectively integrated with intelligent temperature control and unmanned vending systems, lacking a systematic solution. Secondly, the level of intelligence in storage temperature control is insufficient. The storage environment temperature varies drastically with the seasons. High temperatures in summer accelerate the reproduction of microorganisms in the liquid, leading to a deterioration in water quality; low temperatures in winter may affect the drinking taste. Traditional storage methods either do not perform any temperature control or use constant low temperatures (such as 4°C) for refrigeration, which is not only energy-intensive but also fails to consider the balance between the energy-saving needs of seasonal differences and the relatively constant temperature preservation of water quality. It is particularly important to point out that there has long been a technical bias in the field that "the lower the temperature, the better the preservation effect." To maximize the shelf life of liquids, existing technologies generally teach maintaining drinking water and similar products in a consistently low-temperature environment of 4-10°C. This bias leads those skilled in the art, when faced with the high energy consumption problem of large-capacity liquid storage, to often focus only on improving the energy efficiency of the refrigeration system itself, while neglecting to start from the fundamental strategy of "reducing the temperature difference between the inside and outside of the tank" to seek a dynamic temperature control solution that can balance antibacterial preservation and significant energy savings. This obsession with constant low temperatures constitutes the technical obstacle that this invention aims to overcome. A search revealed existing patents related to temperature control of tank containers. For example, Tianxing Advanced Materials Technology (Jiangsu) Co., Ltd.'s patent "A Temperature Control Method and System for Tank Containers Based on the Internet of Things" (authorization announcement number CN118689264B) relates to IoT-based temperature control of tank containers. CIMC Anrui Environmental Technology Co., Ltd.'s patent "Temperature Control System for Tank Containers and Tank Containers with Dual Functions of Cooling and Heating" (publication number CN117508921A) relates to dual-function temperature control for tank containers. However, these existing technologies only focus on the temperature control function of the tank container itself, without integrating the tank container with an automated vending system, proposing a seasonally differentiated temperature control strategy based on outdoor temperature sensing, or providing any insights to overcome the aforementioned technological biases. Third, there is a technological disconnect between large-capacity storage and unmanned vending. Existing vending machines are mostly designed for small volumes (usually bottled or canned drinks), lacking the ability to maintain a relatively constant temperature for large-volume liquids; while large storage tanks (such as bottled water tanks) lack the capability for unmanned, pay-as-you-go vending. The market lacks an integrated device that organically combines large-capacity liquid storage, intelligent relative temperature control, and unmanned vending. A search revealed existing patents related to intelligent vending of bulk liquids. For example, patent application CN117877159A, entitled "Intelligent Vending System, Control Method, and Vending Machine for Bulk Liquids," relates to a liquid vending system consisting of a storage tank, a heating tank, and metering pipelines. However, this solution uses a heating tank to heat the liquid, and its temperature control purpose is heating rather than relatively constant temperature preservation. Furthermore, it does not incorporate features such as a containerized structure or adaptive temperature control based on outdoor temperature sensing. Furthermore, existing technology discloses an automated refrigerated container for selling fresh produce (authorization announcement number CN210924743U), which includes a refrigerated container body, a human-machine interface panel, storage boxes, shelves, a condensing unit, and a robotic arm assembly. However, this solution sells fresh produce (non-bulk liquids), lacks liquid storage tanks, flow meters, and QR code payment; temperature control is constant refrigeration; it lacks outdoor temperature sensing and seasonal temperature differentiation strategies. Existing technology also discloses a temperature-controlled goods sales device (publication number CN112021877A), including a frame and an air conditioning unit, adjusting the storage space temperature via an air duct regulating plate. However, this solution sells goods (non-bulk liquids), lacks liquid storage tanks, and has no flow meters. Fourth, the reliability of transactions in unmanned vending scenarios. Existing vending machines cannot complete transactions or record transaction data when the network is unstable, resulting in transaction failures or data loss, which affects user experience and the operator's financial management; Therefore, existing technologies lack a systematic solution that can simultaneously address the safe storage of large-capacity liquids, adaptive intelligent relative temperature control throughout the four seasons, unmanned automated vending, and guaranteed transaction reliability. In particular, existing technologies adhere to the conventional thinking of "constant low-temperature preservation" and fail to provide an innovative temperature control strategy that can dynamically balance preservation and energy-saving requirements. Summary of the Invention

[0003] [Technical Problem to be Solved] This invention provides a containerized relative constant temperature liquid storage and automatic vending system and its control method, aiming to solve the technical problem that existing technologies cannot simultaneously meet the requirements of safe storage of large-capacity liquids, intelligent relative constant temperature, and unmanned vending. In particular, it aims to overcome the technical bias that "the lower the temperature, the better the preservation effect" and provide a seasonally differentiated temperature control strategy that can adaptively adjust with the outdoor temperature while ensuring the antibacterial and preservation effect of the liquid, thereby significantly reducing energy consumption. Furthermore, it aims to organically integrate this strategy with the automatic vending unit on the container carrier, solving the transaction reliability problem in unmanned vending scenarios. Technical solution

[0004] To achieve the above objectives, the present invention provides the following technical solution: It should be noted that the "relative constant temperature" described in this invention refers to the system not maintaining an absolutely fixed temperature throughout the year, but rather dynamically selecting a corresponding seasonal target temperature range based on changes in the outdoor ambient temperature, so that the liquid temperature inside the tank remains in a relatively constant state adapted to the current environment. This is fundamentally different from the traditional concept of "constant temperature" that pursues an absolutely constant low temperature. A containerized relatively constant temperature liquid storage and automatic vending system includes: a containerized shell, which is of standard container size, facilitating transportation, hoisting, and on-site deployment; A 316L stainless steel tank (1) is installed inside the container-type shell and is used to store liquids for sale. 316L stainless steel has excellent corrosion resistance and chemical inertness, with no harmful substances leaching out. The inner wall is precision polished, with a surface roughness Ra≤0.8μm, which meets food-grade hygiene standards. The insulation layer (2) is wrapped around the outside of the 316L stainless steel tank (1). It is made of polyurethane integral foam material with a thickness of 50mm-500mm. It is used to reduce the heat exchange between the tank and the outside world and reduce the workload of the temperature control unit. The temperature control unit (3) includes a semiconductor cooling / heating module, a first temperature sensor (4), and a controller (9). The first temperature sensor (4) is disposed inside or on the outer wall of the 316L stainless steel tank (1) and is used to detect the liquid temperature inside the tank in real time. The controller (9) is electrically connected to the semiconductor cooling / heating module and the first temperature sensor (4). The automatic vending unit includes a human-machine interaction module (5), a flow metering module (6), a liquid outlet control valve (7), and a liquid outlet. It should be particularly emphasized that the core of this invention lies in the fact that the three elements of "mobile container deployment scenario—seasonal dynamic target temperature control strategy based on outdoor temperature sensing—unmanned automated vending" are not simply a combination of functions, but rather an organic integration with synergistic effects. The outdoor mobility of containers inevitably exposes them to significant seasonal temperature variations, creating a strong demand for adaptive outdoor temperature control. The seasonal differentiated temperature control strategy proposed in this invention minimizes the temperature difference between the inside and outside of the container, reducing system energy consumption to a commercially acceptable range, thus enabling the large-scale deployment of large-capacity liquid vending machines in dispersed scenarios such as communities and construction sites. Removing any one of these elements would negate the overall technical effect of the system. The overall technical effect generated by this synergy far exceeds the simple sum of the individual parts. The controller (9) is also configured to be electrically connected to a second temperature sensor (10) located outside the container housing, automatically select the corresponding target temperature range based on the outdoor ambient temperature detected by the second temperature sensor (10), and control the semiconductor cooling / heating module to operate so that the liquid temperature inside the 316L stainless steel tank (1) is maintained within the target temperature range. The target temperature range includes: - Summer mode (triggered when the average daily outdoor temperature is ≥ 21℃): Target temperature 19℃ ± 2℃; - Winter mode (triggered when average daily outdoor temperature ≤ 9℃): Target temperature 7℃ ± 2℃; - Spring Mode (Switching from Winter to Spring Mode): Target temperature 15℃ ± 2℃; - Autumn Mode (Switching from Summer to Autumn Mode): Target temperature 17℃ ± 2℃; The aforementioned temperature setting logic breaks through conventional technical understanding: while meeting the shelf-life requirements of spring water / drinking water, it creatively minimizes the temperature difference between the water inside the tank and the outdoor ambient temperature, thereby reducing the energy consumption of the temperature control unit. Specifically, the summer temperature is set at 19℃ instead of the traditional 4-10℃ for refrigeration, based on in-depth research and breakthroughs in understanding the laws of microbial reproduction. This invention has found that 19℃ is significantly lower than the 20-40℃ range where microorganisms are most active, effectively inhibiting microbial reproduction while significantly reducing the temperature difference between the inside and outside of the tank, thus reducing the refrigeration load and achieving the technical effect of "antibacterial preservation" and "significant energy saving"—which was considered mutually exclusive under traditional biases. In winter, setting the temperature to 7℃ inhibits microbial activity without requiring additional significant heating; only a small amount of heat compensation is needed to maintain this. Furthermore, the controller (9) controls the current direction of the semiconductor cooling / heating module through an H-bridge drive circuit: when the current flows in the forward direction, the semiconductor cooling chip operates in cooling mode; when the current flows in the reverse direction, the semiconductor cooling chip operates in heating mode. This achieves dual-mode control of cooling and heating with the same actuator, simplifying the system structure. Furthermore, the controller (9) runs a PID control algorithm and outputs a PWM control signal to adjust the power of the semiconductor cooling / heating module based on the difference between the detection value of the first temperature sensor (4) and the target temperature range. The PID control algorithm includes an integral limiting anti-saturation circuit. When the integral accumulation term exceeds the preset limit value, the integral accumulation is stopped to prevent system overshoot. Furthermore, the controller (9) is also equipped with an outdoor temperature feedforward compensation module. The feedforward compensation module calculates the feedforward compensation amount based on the difference between the outdoor ambient temperature detected by the second temperature sensor (10) and the target temperature, and adds it to the output of the PID control algorithm. The formula for calculating the feedforward compensation amount is: FF = Kf × (T_outdoor − T_target), where Kf is the feedforward coefficient (preferably 0.3), T_outdoor is the outdoor ambient temperature, and T_target is the target temperature. The function of feedforward compensation is to respond in advance to the impact of outdoor temperature changes on the tank temperature, rather than waiting until the tank temperature has deviated from the target value before feedback adjustment. Furthermore, the controller (9) is equipped with a hysteresis control module. When the outdoor daily average temperature fluctuates near the mode switching threshold, the hysteresis control module introduces a hysteresis interval to prevent the system from frequently switching working modes. The width of the hysteresis interval is ±3℃. This ±3℃ hysteresis interval is not arbitrarily selected, but rather forms a complete anti-interference and anti-shake scheme in conjunction with the "3 consecutive days" judgment rule. If "3 consecutive days" is used alone without hysteresis, or if the hysteresis interval is too small or too large, it is impossible to achieve stable mode switching while ensuring timely response. All three are indispensable. Furthermore, the controller (9) is equipped with a target temperature smooth transition module. When the operating mode is switched, the smooth transition module gradually adjusts the target temperature from the current value to the new target value at a preset step rate of 0.5℃ / minute. This transition strategy avoids the semiconductor cooling / heating module from working at full load instantaneously due to sudden changes in the target temperature, protecting the equipment and reducing inrush current. Furthermore, the human-machine interaction module (5) of the automatic vending unit is a QR code scanning module, whereby users can identify themselves and make payments by scanning a QR code. The flow metering module (6) is a turbine flow meter, used to detect the liquid output in real time. Its output is a pulse signal, with each pulse corresponding to a fixed volume of liquid. The liquid discharge control valve (7) is a solenoid valve. The controller (9) accumulates the liquid output volume based on the pulse signal from the flow metering module (6). When the accumulated liquid output volume reaches the target value set by the user, it controls the liquid discharge control valve (7) to close. Furthermore, the controller (9) is equipped with a transaction state machine, which includes an idle state, a barcode scanning state, a payment confirmation state, a liquid dispensing and metering state, a transaction completion state, and an abnormal state. The transaction process is as follows: Step T1: The system is in an idle state, and the human-computer interaction module (5) displays a standby interface, waiting for the user to scan the code; Step T2: The user scans the QR code through the scanning module of the human-computer interaction module (5), and the system parses the user's identity information and pre-order information in the QR code, generates an order, and enters the scanning state; Step T3: The system uploads the order information to the cloud server through the communication module, the user completes the online payment, the system polls the payment status, and enters the payment confirmation state after confirming the payment is successful; Step T4: The system opens the liquid discharge control valve (7) and starts discharging liquid, while the flow metering module (6) measures the liquid discharge volume in real time, and the system enters the liquid discharge metering state; Step T5: The controller (9) monitors the cumulative liquid discharge volume in real time. When the cumulative liquid discharge volume reaches the target value set by the user, the liquid discharge control valve (7) is closed, and the transaction is completed; Step T6: The system records the transaction log, uploads the order information, liquid discharge volume, transaction amount, timestamp, and other data to the cloud server, and the system returns to the idle state; Furthermore, the controller (9) is also equipped with a liquid dispensing timeout protection module: when the liquid dispensing time exceeds a preset threshold (such as 30 seconds) and the cumulative liquid dispensing volume still does not reach the target value, the controller forcibly closes the liquid dispensing control valve (7), the system enters an abnormal state, and triggers a refund process through the communication module to return the paid amount to the user account; Furthermore, the controller (9) is also equipped with a network interruption resumption module: the system is equipped with a local storage device (such as a Flash chip). When the network is interrupted, the system stores the transaction logs in the local storage device and marks them as "pending reporting". When the network is restored, the system automatically reads all the "pending reporting" transaction logs in the local storage device and uploads them one by one to the cloud server. After successful upload, the system updates the marking to "reported". This ensures the integrity of transaction data in unstable network scenarios.

[0005] Beneficial effects Compared with the prior art, the present invention has the following outstanding substantive features and significant progress: First, this invention overcomes the technical bias in the field that "the lower the temperature, the better the preservation effect," achieving unexpected technical results. Contrary to the conventional approach of pursuing constant low temperatures, this invention creatively employs a dynamic relative constant temperature strategy that follows the outdoor temperature, especially in summer, controlling the temperature at only 19℃, far higher than the traditional 4-10℃ refrigeration temperature. However, this "unconventional" strategy simultaneously achieves two previously considered contradictory goals: ① 19℃ avoids the most active range of microorganisms, fully ensuring the preservation quality of the liquid; ② The temperature difference between the inside and outside of the container is significantly reduced, resulting in a reduction of refrigeration energy consumption of over 46% (see Example 6). This dual effect of achieving such significant energy savings while ensuring safety is something that those skilled in the art could not have foreseen under the existing teachings of constant low temperatures. Secondly, this invention achieves the organic integration and system-level synergy of four major functional modules. It structurally integrates the "container-type shell," the "316L food-grade storage tank," the "all-season adaptive temperature control unit," and the "unmanned automated vending unit." The outdoor deployment of containers creates a demand for adaptive outdoor temperature control; the differentiated temperature control strategy of this invention makes large-capacity liquid storage and vending economically feasible in terms of energy consumption; and the automated vending unit makes unmanned operation a reality. These modules are interdependent and work synergistically, resulting in an overall system efficiency far greater than the simple sum of the functions of each independent module. This highly integrated system solution is not publicly available in existing technologies. Third, the selection of control parameters is non-obvious, forming a complete and synergistic control system. The "three consecutive days" determination rule, specific seasonal target temperature values ​​(19℃, 7℃, 15℃, 17℃), and ±3℃ hysteresis range in this invention are not easily obtained through a limited number of experiments. They are "optimal equilibrium point groups" determined through complex engineering calculations and field verification, taking into account microbial inhibition models, tank heat conduction models, and system energy consumption models. These parameters must work together to form a stable, energy-efficient, and safe dynamic relative constant temperature system. Imitating any one of these parameters in isolation will not achieve the overall technical effect described in this invention. Fourth, high temperature control accuracy. Adopting a dual-channel control structure of "PID feedback control + outdoor temperature feedforward compensation," combined with PWM power regulation and integral limiting anti-saturation measures, the liquid temperature inside the tank can be stabilized within ±0.8℃ of the target temperature, meeting the temperature requirements for drinking water storage; Fifth, high transaction reliability. Through local storage and a mechanism for resuming data transmission even after network outages, transaction data can be completely recorded even in environments with unstable networks, protecting the rights and interests of both the operator and the consumer; the liquid dispensing timeout protection and automatic refund mechanism further enhance system security and user experience. Sixth, it boasts high structural integration and flexible deployment. Adopting a containerized modular design, it integrates four major functions—storage tank, insulation, temperature control, and sales—within a standard container shell, facilitating factory prefabrication, transportation, hoisting, and rapid deployment. This significantly reduces on-site construction costs and allows for wide application in communities, construction sites, scenic areas, schools, highway service areas, and other locations. Attached Figure Description

[0006] Figure 1 This is a schematic diagram of the overall structure of an embodiment of the present invention; Figure 2 This is a control flowchart of the temperature control system of the present invention; Figure 3 This is a schematic diagram of the transaction state machine of the automated vending system of the present invention; The component numbers in the diagram are as follows: 1-316L stainless steel tank; 2-Insulation layer; 3-Temperature control unit (semiconductor cooling / heating module); 4-First temperature sensor (inside the tank); 5-Human-machine interaction / scanning module; 6-Flow metering module; 7-Discharge control valve; 8-Discharge port; 9-Controller; 10-Second temperature sensor (outdoor). Detailed Implementation

[0007] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention. [Example 1] System Overall Structure and Basic Working Process A containerized relative constant temperature liquid storage and automatic vending system for the bulk sale of spring water in a community. The container shell size is a standard 20-foot container (6058mm long × 2438mm wide × 2591mm high). The interior is equipped with a 316L stainless steel tank (1) with a volume of 20-25 cubic meters and a wall thickness of 3mm-10mm. The inner wall of the tank (1) is precision polished, with a surface roughness Ra≤0.6μm, which meets the food-grade hygiene standards; The insulation layer (2) is made of polyurethane integral foam material with a thickness of 50mm-500mm and a thermal conductivity of ≤0.022W / m·K. It is wrapped around the outside of the tank body (1) to effectively reduce heat exchange between the inside and outside of the tank. The temperature control unit (3) uses two sets of 120W semiconductor cooling chips (TEC1-12706), which, together with the L298N H-bridge drive circuit, realize dual-mode control of cooling / heating. The internal temperature sensor (4) uses a DS18B20 digital temperature sensor with an accuracy of ±0.5℃, and is installed in the lower middle part of the inner wall of the tank (1). The external temperature sensor (10) uses a waterproof encapsulated DS18B20 and is installed on the backlight side of the container shell (avoiding direct sunlight). The controller (9) uses an STM32F407ZGT6 microcontroller (Cortex-M4 core, with FPU), runs a PID control algorithm, and has a PWM output frequency of 1kHz. The controller (9) connects to the cloud server through a 4G communication module to realize payment status query, transaction data reporting and remote monitoring functions; The human-machine interaction module (5) of the automatic vending unit is a 4G network-connected barcode scanner that supports WeChat / Alipay barcode payment. The flow metering module (6) is a turbine flow meter with a calibration coefficient of 450 pulses / liter, which outputs pulse signals to the external interrupt pin of the controller (9). The liquid discharge control valve (7) is a 12V normally closed solenoid valve with a rated flow rate of 20L / min. The overall system operation process is as follows: Users scan the QR code on the screen of the human-computer interaction module (5) with their mobile phones to select the liquid output volume (the preset options are 5L, 10L, and 20L, and users can also customize the input). The controller (9) uploads the order information to the cloud. After the user completes the payment, the controller (9) confirms the payment is successful and opens the liquid output control valve (7). Spring water flows out from the bottom of the tank (1) through the liquid output pipeline. The flow metering module (6) generates pulse signals in real time. The controller (9) accumulates the number of pulses in the interrupt service routine and converts them into liquid output volume. When the accumulated liquid output volume reaches the target value set by the user, the controller (9) closes the liquid output control valve (7) and the liquid output stops. After the transaction is completed, the controller (9) uploads the transaction log to the cloud server. In this embodiment, it is clear that the four functional modules of the system work closely together: the standardization and mobility of the container allow for direct deployment in outdoor communities, facing extreme temperature differences from -5°C to 40°C; if a traditional constant 4°C solution were used, the energy consumption in summer would be extremely high, rendering it commercially unviable. It is precisely the energy-saving characteristics of the temperature control strategy of this invention that make this deployment possible. The addition of automated vending units enables truly 24-hour unattended service. This system-level collaboration, "from the scenario and back to the scenario," is the core of the invention's inventiveness as a complete technical solution. [Example 2] Specific implementation of seasonal temperature control strategy This embodiment details the implementation process of the core innovation of the present invention—the seasonal temperature control strategy. The controller (9) reads the data from the outdoor temperature sensor (10) every 30 minutes and calculates the average temperature of the day. When the average outdoor temperature is detected to be ≥21℃ for 3 consecutive days, the controller (9) automatically switches to summer mode and sets the target temperature to 19℃. When the average outdoor temperature is detected to be ≤9℃ for 3 consecutive days, the controller (9) automatically switches to winter mode and sets the target temperature to 7℃. The spring mode automatically switches from winter (March-May) with a target temperature of 15℃, and the autumn mode automatically switches from summer (September-November) with a target temperature of 17℃. To prevent frequent mode switching caused by outdoor temperature fluctuations at threshold boundaries, the controller (9) introduces hysteresis control logic. Taking summer mode as an example, when the system is in summer mode, it needs to have a daily average temperature <18℃ for 3 consecutive days (i.e., a hysteresis range of 21℃-3℃) before switching back to autumn mode. The same applies to switching winter mode; it needs to have a daily average temperature >12℃ for 3 consecutive days (i.e., a hysteresis range of 9℃+3℃) before switching to spring mode. When the system detects a need to switch operating modes (e.g., from spring to summer), the target temperature will be gradually adjusted from 15℃ to 19℃ at a step rate of 0.5℃ / minute, meaning it takes 8 minutes to rise from 15℃ to 19℃. This smooth transition strategy avoids sudden changes in the target temperature causing the semiconductor cooling / heating module to operate at full load instantly, protecting the equipment and reducing inrush current. The Spring and Autumn modes serve as transitions between the Summer and Winter modes. Their switching is automatically triggered by the exit conditions of the Summer and Winter modes, and the hysteresis rules also apply. For example, the system will only switch from Autumn mode to Winter mode when the average daily temperature in autumn continues to drop and meets the Winter trigger condition (≤9℃); conversely, it will switch when the average daily temperature in autumn does not drop. The Spring mode (roughly corresponding to March-May) and Autumn mode (roughly corresponding to September-November) maintain relatively stable temperature control within the seasons, eliminating the need for frequent switching between them. Their fixed ±2℃ fluctuation range is sufficient to handle daily temperature changes during the transitional seasons. [Example 3] Specific Implementation of PID Control Algorithm and Feedforward Compensation This embodiment describes in detail the core control algorithm of the temperature control system. The controller (9) performs a PID calculation cycle every 30 minutes. Let the target temperature be T_set and the current measured temperature be T_current, then the error = T_set - T_current; The proportional term, P_out = Kp × error, is used for quick response to the current deviation. The integral term, I_out = Ki × ∫error·dt, is used to eliminate steady-state error. The integral accumulation term ∑error is added during each calculation, but is limited by the integral limit ±ILimit to prevent system overshoot caused by integral saturation. In this embodiment, the integral limit is set to ±150. Differential term: D_out = Kd × d(error) / dt, used to predict the trend of error change and suppress overshoot. In this embodiment, a differential-first strategy is adopted, differentiating the measured temperature rather than the error to avoid shock to the differential term when the target temperature changes abruptly; Feedforward compensation term: FF = Kf × (T_outdoor − T_target), where Kf is the feedforward coefficient, which is taken as 0.3 in this embodiment. The function of feedforward compensation is to respond in advance to the impact of changes in outdoor temperature on the tank temperature. For example, when the outdoor temperature rises sharply from 30°C to 35°C, the feedforward term increases accordingly, starting the cooling system earlier to offset the incoming heat; Total control output: OUT = P_out + I_out + D_out + FF; Map OUT to PWM duty cycle: PWM_duty = min(|OUT| × 10, 1000), in per mille (0-1000). When OUT > 0, the controller (9) drives the thermoelectric cooler to work in cooling mode through the H-bridge drive circuit; when OUT < 0, the controller (9) drives the thermoelectric cooler to work in heating mode (current reversed); when OUT = 0, the output stops. In this embodiment, the PID parameters for each seasonal mode are as follows: | Mode | Kp | Ki | Kd | Integral Limiting | Output Limiting | | :--- | :--- | :--- | :--- | :--- | :--- | | Summer Mode | 3.5 | 0.06 | 1.2 | ±150 | ±1000 | | Winter Mode | 2.8 | 0.04 | 1.5 | ±100 | ±800 | Spring Mode | 2.5 | 0.03 | 1.0 | ±80 | ±500 | | Autumn Mode | 2.5 | 0.03 | 1.0 | ±80 | ±500 |; Tests showed that under outdoor high temperatures of 35℃, the water temperature inside the tank could be maintained at a stable 19±0.8℃, with a daily power consumption of approximately 2.8kWh. In comparison, using a traditional constant 4℃ refrigeration mode under the same conditions would consume approximately 5.2kWh per day, making this invention energy-efficient by about 46%. [Example 4] Transaction State Machine and Reliability Assurance of Automated Vending Systems This embodiment describes in detail the implementation of the transaction state machine and the reliability assurance mechanism of the automated vending system; The controller (9) runs a finite state machine to manage the entire transaction process of the automated vending unit. The states are defined as follows: - STATE_IDLE (Idle): The system is in standby mode. The human-computer interaction module (5) displays the welcome screen and QR code. It waits for the user to scan the code to trigger the interaction. - STATE_SCANNING (Scanning code): The user has scanned the code. The controller (9) parses the QR code data, generates an order, and sends a payment request to the cloud. - STATE_PAYING (Payment Confirmation in Progress): The user has completed the payment. The controller (9) polls the cloud payment result every 2 seconds. If the payment is successful, it enters STATE_DISPENSING; if the payment fails, it enters STATE_ERROR and prompts for a retry; if there is no response after 5 minutes, the order is automatically cancelled. - STATE_DISPENSING (Dispensing Metering in Progress): Dispensing control valve (7) is open, and flow metering module (6) measures in real time. Controller (9) continuously monitors whether the cumulative dispensing volume has reached the target value, and simultaneously monitors the timeout timer; - STATE_COMPLETE (Transaction Completed): Liquid discharge ends normally, transaction log is recorded, data is uploaded, and after a 2-second delay, it automatically jumps to STATE_IDLE; - STATE_ERROR (Abnormal): Entered when liquid dispensing timeout, payment failure, or equipment malfunction. The controller (9) performs the corresponding abnormality handling (refund, alarm), and returns to STATE_IDLE after automatic reset; The liquid discharge timeout protection mechanism is as follows: The controller (9) starts a 30-second timeout timer at the same time as opening the liquid discharge control valve (7). If the timer expires and the liquid discharge volume does not reach the target value (which may be caused by flow meter failure, pipeline blockage or insufficient liquid level, etc.), the controller (9) forcibly closes the liquid discharge control valve (7), the system enters the STATE_ERROR state, initiates a refund request through the 4G module, and displays the message "Liquid discharge abnormal, refund has been issued, please contact customer service" on the human-machine interaction module (5); The mechanism for resuming data transmission after network outage is as follows: The system is equipped with a W25Q128 Flash memory (16MB) for local storage of transaction logs. When the network is normal, after each transaction is completed, the controller (9) immediately reports the transaction log to the cloud server via the 4G module. When the network is interrupted (TCP connection failure or HTTP request timeout), the controller (9) writes the transaction log to the Flash memory and marks it as "to be reported". After the network is restored, the controller (9) detects that the communication module has successfully reconnected to the network and automatically traverses all the "to be reported" logs in the Flash memory and re-reports them one by one. After successful upload, the corresponding log is marked as "reported". [Example 5] Temperature Anomaly Protection and Sensor Redundancy This embodiment describes the system's security protection mechanism in detail; The system is equipped with dual temperature sensor redundancy: the main sensor is a DS18B20 digital temperature sensor (installed in the lower middle part of the inner wall of the tank), and the backup sensor is a PT1000 platinum resistance temperature sensor (installed in the outlet pipeline of the tank). The controller (9) monitors the reading of the main sensor in real time. When the reading of the main sensor is detected to be outside the reasonable range (1℃ to 80℃) or to change abruptly (more than 20℃ per second), the main sensor is determined to be faulty, and the system automatically switches to the backup sensor to continue working. The system also sends a fault alarm to the cloud via the 4G module. The over-temperature and over-cooling protection mechanisms are as follows: | Protection Type | Triggering Condition | Protection Action | | :--- | :--- | :--- | | High Temperature Protection Level 1 | Internal Tank Temperature ≥ 23℃ | Forced Start of Refrigeration Module for Full Load Operation, Audible and Visual Alarm | | High Temperature Protection Level 2 | Internal tank temperature ≥ 25℃ | Forcefully shut down all heating outputs, cut off power to the heating module, and send an alarm to the cloud | | Low-temperature protection level 1 | Internal tank temperature ≤ 5℃ | Forced start of heating module to prevent freezing | | Low temperature protection level 2 | Internal tank temperature ≤ 3℃ | Forcefully shut down cooling output, switch to full power heating, and send an alarm to the cloud |; The actuator failure detection mechanism is as follows: The controller (9) calculates the temperature change rate once per second. If the cooling mode is on for more than 5 minutes and the temperature change rate is greater than +0.1℃ / second (the temperature rises instead of falling), the cooling module is judged to be faulty; if the heating mode is on for more than 5 minutes and the temperature change rate is less than -0.1℃ / second (the temperature falls instead of rising), the heating module is judged to be faulty. After the failure, the system enters the safety protection mode and alarms to the cloud. The power outage recovery logic is as follows: When the system is powered on again after a power outage, the controller (9) first reads the most recent working mode and target temperature stored in the EEPROM, then immediately reads the current temperature inside the tank. If it exceeds the safe range, it performs a forced protection action. Then, within 30 seconds, it re-establishes the connection with the cloud server, reports the power outage event and the current status, and finally restores the working mode before the power outage to continue temperature control. [Example 6] Overcoming Technical Bias and Verifying Unexpected Technical Effects To demonstrate that the present invention overcomes technical biases in the field and achieves unexpected technical effects, the following comparative experiments were conducted; Using the system described in this embodiment, placed in an outdoor environment, with the tank filled with drinking water; and operating in two modes during several days of sustained summer high temperatures (average daily outdoor temperature 32-35℃): - Comparison mode: Traditional constant low temperature preservation mode, with the target temperature set at a constant 4℃; - This invention uses a summer adaptive relative constant temperature mode, with the target temperature set at 19℃. During the experiment, the water temperature inside the tank and the system power consumption were continuously monitored, and samples were taken periodically for total bacterial count (CFU / mL) testing. The experimental results show that: - Energy consumption: The average daily power consumption of the comparison mode is 5.2 kWh; the average daily power consumption of the present invention mode is 2.8 kWh, achieving energy savings of up to 46.2%; - Regarding preservation and antibacterial properties: Under both modes, the total bacterial count within 7 days was far below the limit (<100 CFU / mL) of the National Standard for Drinking Water (GB 5749), and there was no significant difference between the two test results. This confirms that a temperature of 19℃ effectively inhibits microbial growth and fully meets the preservation requirements; This experiment demonstrates that the present invention breaks the technical prejudice that "only a constant low temperature of 4°C can preserve food." By achieving temperature control at the critical equilibrium point of 19°C, it achieves energy-saving benefits far exceeding expectations while maintaining almost the same antibacterial effect. This unexpected technical effect is strong evidence of the outstanding inventive progress of this invention.

[0008] Industrial applicability This invention can be widely applied to the large-scale, unmanned self-service vending of drinking water or other liquid beverages in communities, construction sites, scenic spots, schools, highway service areas, and other locations. It adopts a standard container size design, facilitating mass prefabrication in factories and rapid on-site deployment; the 316L food-grade stainless steel material ensures drinking water safety; the intelligent all-season relative constant temperature strategy significantly reduces operating energy consumption while ensuring water quality; and the transaction state machine and network interruption resume mechanism ensure transaction reliability in unmanned scenarios. This invention has good industrial applicability and market economic benefits.

Claims

1. A containerized relative constant temperature liquid storage and automatic vending system, characterized in that, include: A container-type shell; a 316L stainless steel tank (1), located inside the container-type shell, for storing liquids to be sold; an insulation layer (2), wrapped around the outside of the 316L stainless steel tank (1); a temperature control unit (3), including a semiconductor cooling / heating module, a first temperature sensor (4), and a controller (9), wherein the first temperature sensor (4) is located inside or on the outer wall of the 316L stainless steel tank (1) for detecting the temperature of the liquid inside the tank, and the controller (9) is electrically connected to the semiconductor cooling / heating module and the first temperature sensor (4); automatic The vending unit includes a human-machine interaction module (5), a flow metering module (6), a liquid discharge control valve (7), and a water outlet (8); the controller (9) is also configured to be electrically connected to a second temperature sensor (10) located outside the container-type shell, automatically select the corresponding target temperature range according to the outdoor ambient temperature detected by the second temperature sensor (10), and control the semiconductor cooling / heating module to work so that the liquid temperature in the 316L stainless steel tank (1) is maintained within the target temperature range; the target temperature range includes: summer mode: 19℃ ± 2℃; winter mode: 7℃ ± 2℃; spring mode: 15℃ ± 2℃; autumn mode: 17℃ ± 2℃; the summer mode is triggered when the outdoor daily average temperature is ≥ 21℃; the winter mode is triggered when the outdoor daily average temperature is ≤ 9℃.

2. The containerized relative constant temperature liquid storage and automatic vending system according to claim 1, characterized in that, The controller (9) controls the current direction of the semiconductor cooling / heating module through the H-bridge drive circuit to achieve the switching between cooling mode and heating mode; the controller (9) runs a PID control algorithm and outputs a PWM control signal to adjust the power of the semiconductor cooling / heating module according to the difference between the detection value of the first temperature sensor (4) and the target temperature range; the PID control algorithm includes an integral limiting anti-saturation circuit.

3. The containerized relative constant temperature liquid storage and automatic vending system according to claim 2, characterized in that, The controller (9) is also equipped with an outdoor temperature feedforward compensation module. The feedforward compensation module calculates the feedforward compensation amount based on the difference between the outdoor ambient temperature detected by the second temperature sensor (10) and the target temperature, and adds it to the output of the PID control algorithm. The formula for calculating the feedforward compensation amount is: FF = Kf × (T_outdoor − T_target), where Kf is the feedforward coefficient, T_outdoor is the outdoor ambient temperature, and T_target is the target temperature.

4. The containerized relative constant temperature liquid storage and automatic vending system according to claim 1, characterized in that, The controller (9) is equipped with a hysteresis control module. When the outdoor daily average temperature fluctuates near the mode switching threshold, the hysteresis control module introduces a hysteresis interval to prevent the system from frequently switching working modes. The width of the hysteresis interval is ±3℃.

5. The containerized relative constant temperature liquid storage and automatic vending system according to claim 1, characterized in that, The controller (9) is equipped with a target temperature smooth transition module. When the working mode is switched, the smooth transition module gradually adjusts the target temperature from the current value to the new target value at a preset step rate of 0.5℃ / minute.

6. The containerized relative constant temperature liquid storage and automatic vending system according to claim 1, characterized in that, The automatic vending unit further includes: the human-computer interaction module (5) is a QR code scanning module, which allows users to identify themselves and make payments by scanning a QR code; the flow metering module (6) is a turbine flow meter, which is used to detect the liquid output in real time and outputs a pulse signal; the liquid output control valve (7) is a solenoid valve; the controller (9) accumulates the liquid output volume according to the pulse signal of the flow metering module (6), and controls the liquid output control valve (7) to close when the accumulated liquid output volume reaches the target value set by the user.

7. The containerized relative constant temperature liquid storage and automatic vending system according to claim 6, characterized in that, The controller (9) is equipped with a transaction state machine, which includes an idle state, a scanning state, a payment confirmation state, a liquid dispensing metering state, a transaction completion state, and an abnormal state. The controller (9) is also equipped with a liquid dispensing timeout protection module, which forcibly closes the liquid dispensing control valve (7) and triggers a refund process when the liquid dispensing time exceeds a preset threshold. The controller (9) is also equipped with a network interruption resume module, which stores the transaction log in the local storage when the network is interrupted and automatically reports it to the cloud server after the network is restored.

8. The containerized relative constant temperature liquid storage and automatic vending system according to claim 1, characterized in that, The inner wall of the 316L stainless steel tank (1) is a food-grade surface that has been precision polished, with a surface roughness Ra≤0.8μm; the insulation layer (2) is a polyurethane integral foam material with a thickness of 50mm-500mm.

9. A control method for a containerized relative constant temperature liquid storage and automatic vending system, characterized in that, Includes the following steps: S1. Detect the outdoor ambient temperature using the second temperature sensor (10); S2. Automatically select the target temperature range based on the outdoor ambient temperature: When the average daily outdoor temperature is ≥ 21℃ for 3 consecutive days, switch to summer mode, with the target temperature set at 19℃ ± 2℃; and when already in summer mode, the average daily outdoor temperature must be < 18℃ for 3 consecutive days before exiting summer mode and switching to autumn mode (17℃ ± 2℃); when the average daily outdoor temperature is ≤ 9℃ for 3 consecutive days, switch to winter mode, with the target temperature set at 7℃ ± 2℃; when already in winter mode, the average daily outdoor temperature must be > 12℃ for 3 consecutive days before exiting winter mode and switching to spring mode (15℃ ± 2℃). S2℃), thereby forming a hysteresis range of ±3℃ to prevent frequent switching; S3, detect the real-time temperature of the liquid in the tank through the first temperature sensor (4); S4, calculate the error value between the real-time temperature and the target temperature, and calculate the feedback control quantity through the PID control algorithm; S5, calculate the feedforward compensation quantity according to the difference between the outdoor ambient temperature and the target temperature, add it to the feedback control quantity, and generate the total control output; S6, drive the semiconductor cooling / heating module to work according to the total control output until the liquid temperature in the tank is maintained within the target temperature range; wherein, when the working mode is switched, the target temperature is gradually adjusted from the current value to the new target value at a step rate of 0.5℃ / minute.

10. A control method for a containerized relative constant temperature liquid storage and automatic vending system, characterized in that, Includes the following steps: T1. The system is in an idle state, waiting for the user to scan the code; T2. The user scans the code through the human-computer interaction module (5), the system identifies the user's identity and generates an order; T3. The user completes the online payment, and the system confirms the payment is successful; T4. The system opens the liquid dispensing control valve (7) and starts dispensing liquid, while the flow metering module (6) measures the liquid dispensing volume in real time; T5. When the cumulative liquid dispensing volume reaches the target value set by the user, the liquid dispensing control valve (7) is closed; T6. The transaction log is recorded, uploaded to the cloud server, and the system returns to an idle state; If the liquid dispensing time exceeds the preset threshold and the cumulative liquid dispensing volume does not reach the target value, the system forcibly closes the liquid dispensing control valve (7) and triggers the refund process; If the network is interrupted, the transaction logs are stored in local storage and will be automatically retransmitted once the network is restored.

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