Pressure transformation system of semi-automatic coffee machine and pressure transformation method thereof

Abstract

The invention belongs to the technical field of coffee devices, and discloses a variable pressure system of a semi-automatic coffee machine and a variable pressure method of the variable pressure system. A central processing unit; the pressure detection unit is used for collecting pressure parameters in the coffee extraction process; and the pressure regulation execution unit is used for receiving an instruction of the central processing unit and consists of a triode, a resistor and a fly-wheel diode. Through cooperative control of the double pressure sensors, the electromagnetic valve and the motor, dynamic adjustment of the extraction pressure is achieved, and the problems that an existing semi-automatic coffee machine only adopts the design that a single pressure sensor is matched with a fixed electromagnetic valve for on-off, and only single extraction pressure can be provided; the problem that the pressure cannot be adjusted according to the difference of the baking degree, the grinding degree and the like of coffee beans to meet the extraction requirements of different coffee beans is solved, dual-sensor redundancy collection is achieved, dual pressure sensors synchronously collect 4-20 mA current signals and convert the signals into 1.05-4.5 V voltage, the voltage is input into an MCU after filtering and noise reduction, the collection precision is smaller than or equal to + / -0.05 V, and the reliability of pressure data is ensured.

Description

Technical Field

[0001] The present invention belongs to the technical field of coffee devices, and in particular relates to a voltage conversion system and a voltage conversion method of a semi-automatic coffee machine. Background Art

[0002] Semi-automatic coffee machines require the operator to fill and press the powder himself. Everyone has different tastes and naturally different requirements for coffee. Semi-automatic coffee machines can provide coffee with different flavors by allowing the operator to choose the amount of powder and the strength of pressing the powder. Therefore, they are called truly professional coffee machines. At present, in the domestic semi-automatic coffee machine market, although there are many products, there are obvious shortcomings in the key links of coffee extraction.

[0003] On the one hand, faced with a wide variety of coffee beans, including different brands, roasting depths, and grinding coarseness, existing semi-automatic coffee machines find it difficult to accurately match the optimal extraction pressure. For example, lightly roasted coffee beans have dense internal flavor substances and require higher pressure to fully extract the rich fruity aroma and refreshing acidity; while darkly roasted coffee beans have a loose structure, and excessive pressure can easily lead to over-extraction and produce a bitter taste. At this time, low pressure is more suitable. However, most existing domestic semi-automatic coffee machines only provide fixed pressure settings, which cannot meet the diverse extraction needs of coffee beans and seriously affect the presentation of coffee flavor. On the other hand, the water temperature of existing equipment fluctuates by more than ±3°C during continuous extraction, resulting in significant flavor differences between cups. Coffee extraction is extremely sensitive to water temperature. Ideally, the water temperature fluctuation should be controlled within a very small range to ensure a consistent taste in each cup of coffee.

[0004] Therefore, in view of the above-mentioned problems of existing semi-automatic coffee machines, the present invention proposes a voltage conversion system and voltage conversion method for a semi-automatic coffee machine. For coffee beans of different brands, roast depths, and grind finenesses, the present invention controls the motor speed by adjusting the voltage, thereby changing the output pressure of the booster pump. This allows lightly roasted beans to fully extract the fruity aroma under high pressure, while darkly roasted beans are prevented from over-extraction under low pressure. In addition, the pressure curve optimized by professional baristas is stored as a callable program. When ordinary users call it with a button, they can "reproduce professional curves with one click", significantly lowering the threshold for extraction technology. Summary of the Invention

[0005] In order to solve the problems raised in the above background technology, the present invention provides a pressure conversion system and a pressure conversion method for a semi-automatic coffee machine, comprising a pressure detection unit, a central processing unit,

[0006] Pressure detection unit, used to collect pressure parameters during coffee extraction;

[0007] The pressure regulation execution unit is used to receive instructions from the central processing unit, and control the on and off of the extraction solenoid valve with the help of a circuit composed of a transistor, a resistor and a freewheeling diode, and realize segmented control of the extraction pressure in conjunction with pressure regulation;

[0008] The user interaction unit is used for baristas to input pressure curve parameters and for ordinary users to call preset pressure curves. The operation instructions are transmitted to the central processing unit through a level conversion and filtering circuit composed of buttons, resistors, and capacitors;

[0009] The power expansion unit is used to expand and control the coffee machine's peripherals. It drives the solid-state relay through a drive circuit composed of a chip and resistors, and can control peripheral devices such as heating and water pumps.

[0010] The central processing unit is used to store the barista's customized pressure curve data. Based on the real-time pressure feedback from the pressure detection unit and the instructions from the user interaction unit, it outputs a PWM signal or a level signal. The power amplifier element controls the pressure adjustment execution unit and the motor voltage adjustment component to work together to achieve accurate reproduction of the pressure curve.

[0011] Preferably, the pressure detection unit includes at least one set of pressure sensors and a signal conditioning circuit, which can convert the current signal output by the pressure sensor into a voltage signal.

[0012] Preferably, the pressure detection unit adopts a dual-path parallel detection design, including a first pressure sensor and a second pressure sensor. The first pressure sensor and the second pressure sensor independently collect pressure signals during the coffee extraction process. The output signals of the two are processed by a signal conditioning circuit composed of independent resistors, capacitors, and diodes, and then transmitted to the central processing unit to ensure the reliability and anti-interference of pressure signal collection.

[0013] Preferably, the pressure curve stored in the central processing unit includes multiple time-pressure segmentation points, and the pressure regulation rate of each segmentation point is 0.1-2 bar / s. The central processing unit dynamically adjusts the output of the pressure regulation execution unit through the PID control algorithm to achieve precise pressure control.

[0014] Preferably, the PID control algorithm calculates in real time the deviation between the real-time pressure fed back by the pressure detection unit and the target pressure of the pressure curve, and dynamically adjusts the control signal output to the pressure regulation execution unit according to preset proportional, integral and differential parameters.

[0015] Preferably, the power extension unit includes at least one solid-state relay driving circuit to achieve level conversion between the I / O port and the relay.

[0016] Preferably, the user interaction unit includes a touch display screen and a mechanical button interaction form, which is used to input digital pressure parameters, time node parameters, and select preset coffee bean types, roasting degrees and other options, which is convenient for users with different operating habits and reduces the operating threshold.

[0017] Preferably, the central processing unit supports a wireless communication module, which can remotely upload the barista-optimized pressure curve data and download the preset curve library through a mobile terminal, and can also modify the pressure curve parameters in real time to achieve remote debugging and curve updates, thereby improving the intelligence and convenience of the device.

[0018] This solution also provides a voltage conversion method for a semi-automatic coffee machine

[0019] The following steps are included:

[0020] The following steps are included:

[0021] S1: Pressure acquisition: The pressure parameters during coffee extraction are collected through the pressure detection unit, processed by the signal conditioning circuit, and transmitted to the central processing unit, and then S2 is executed;

[0022] S2: Command interaction: Input pressure curve parameters or call preset pressure curve through the user interaction unit, which is received by the pin after processing, and the operation command is transmitted to the central processing unit, and then S3 is executed;

[0023] S3: Curve calculation and control: The central processing unit retrieves the stored pressure curve data, compares the real-time pressure with the target pressure curve, and generates a control signal based on the PID control algorithm to make the pressure fluctuation ≤±0.3bar. The microcontroller in the central processing unit retrieves the node data stored in the Flash memory, and the PID algorithm calculates the deviation and generates a PWM signal to PB0 / PB1, and then executes S4;

[0024] S4: Pressure regulation execution: The pressure regulation execution unit receives the control signal, controls the on / off of the extraction solenoid valve, adjusts the motor voltage, etc., to achieve dynamic adjustment of the extraction pressure. The PWM signal is amplified by IRF3205 to control the motor. At the same time, VALVE7 / 8 is driven on and off by Q13 / Q14, and then S5 is executed.

[0025] S5: Peripheral collaborative control: The power expansion unit coordinates and controls peripherals such as heating and water pumps according to the instructions of the central processing unit to help maintain a stable extraction environment.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The present invention realizes dynamic adjustment of extraction pressure through the coordinated control of dual pressure sensors, solenoid valves and motors, solving the problem that existing semi-automatic coffee machines only use a single pressure sensor with a fixed solenoid valve on-off design, can only provide a single extraction pressure, and cannot adjust the pressure to meet the extraction requirements of different coffee beans according to differences in coffee bean roasting degree, grinding degree, etc. The dual sensors perform redundant data collection, and the dual pressure sensors synchronously collect 4-20mA current signals and convert them into 1.05-4.5V voltages. After filtering and noise reduction, they are input into the MCU, with an acquisition accuracy of ≤±0.05V, ensuring the reliability of pressure data.

[0028] Furthermore, the present invention realizes "one-click reproduction of professional pressure curves" through the key interaction unit and the curve storage function, which solves the problem that existing coffee machines need to set pressure and time segmentation points one by one through knobs or touch screens, which is time-consuming and error-prone. Ordinary users need professional training to complete basic settings. The parameter settings are complicated and difficult for ordinary users to operate. The internal Flash of the central processing unit stores ≥3 groups of preset curves. The light and dark roasting types of coffee beans are selected through SW1-SW4, and SW5 is used to confirm the call with one click. There is no need to manually set parameters. Ordinary users can call the curve optimized by professional baristas in just a few seconds, significantly reducing the operating technical threshold.

[0029] Furthermore, the present invention controls the continuous extraction water temperature fluctuation to ≤±1°C through the coordinated control of the power expansion unit and multiple peripherals, solving the problem that existing coffee machines mostly use mechanical thermostats or simple PID control, and the water temperature fluctuates by more than ±3°C due to pressure regulation and continuous extraction, resulting in obvious flavor differences between the first and last cups of coffee due to unstable water temperature. The water temperature and pressure are coordinated to adjust, and the central processing unit synchronously increases the power of the heating tube. The PID algorithm is used to dynamically compensate for heat loss and maintain the water temperature at 92±1°C. During the continuous extraction of 20 cups of espresso, the water temperature fluctuation is always ≤±1°C, maintaining the flavor between cups. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a circuit diagram of the core circuit and peripheral interface of the central processing unit of the present invention, showing the signal interaction logic between the single-chip microcomputer in the central processing unit and the pressure detection, user interaction, and pressure regulation execution units, realizing pressure curve storage and PID control operation;

[0031] Figure 2 This is the circuit diagram of the power expansion unit of the present invention. Based on the ULN2003APWR chip, a 6-way solid-state relay drive channel is designed to control peripherals such as heating and water pumps to maintain the extraction water temperature fluctuation ≤±1°C.

[0032] Figure 3This is a circuit diagram of the pressure detection unit signal conditioning circuit of the present invention, showing the filter and amplitude limiting circuit composed of the resistors, capacitors and diodes of the dual pressure sensor;

[0033] Figure 4 This is the driving circuit of the extraction solenoid valve of the pressure regulation execution unit of the present invention, showing the extraction solenoid valve control circuit composed of a transistor, a resistor, and a freewheeling diode, and the relay closing time;

[0034] Figure 5 This is a circuit diagram of the user interaction unit key circuit of the present invention. The eight groups of mechanical keys support digital parameter input and preset curve call through level conversion and filtering circuits, lowering the operating threshold.

[0035] Figure 6 This is the circuit diagram of the wireless communication module expansion circuit of the present invention, which reserves the UART serial port and filtering circuit, supports WiFi / Bluetooth module expansion, and realizes remote debugging and updating of pressure curves;

[0036] Figure 7 This is a system diagram of the present invention, showing the working process of the pressure conversion system of a semi-automatic coffee machine. DETAILED DESCRIPTION

[0037] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0038] like Figures 1 to 7 As shown, the present invention provides a pressure changing system for a semi-automatic coffee machine, comprising a pressure detection unit and a central processing unit;

[0039] Pressure detection unit, used to collect pressure parameters during coffee extraction;

[0040] Specifically, the pressure detection unit adopts a dual pressure sensor redundant design, namely the first pressure sensor and the second pressure sensor, which independently collect pressure signals to ensure the reliability of data acquisition. The 4-20mA current signal output by the pressure sensor is first converted from current to voltage through a 10Ω resistor, converting the current signal into a 1.05-4.5V voltage signal. The signal then enters the filter circuit composed of 100nF capacitors C34 and C50. This circuit can effectively filter out high-frequency noise and attenuate the noise by ≥30dB, ensuring signal purity. Then, a BAV99 diode is used for limiting protection to prevent excessive voltage from damaging subsequent circuit components, ensuring that the voltage input to the central processing unit is stable in a safe range. The processed signal is finally transmitted to the central processing unit. The pressure signal acquisition accuracy is ≤±0.05V, providing accurate data support for subsequent pressure regulation.

[0041] The pressure regulation execution unit is used to receive instructions from the central processing unit, and control the on and off of the extraction solenoid valve with the help of a circuit composed of a transistor, a resistor and a freewheeling diode, and realize segmented control of the extraction pressure in conjunction with pressure regulation;

[0042] Pressure regulation execution unit: used to receive instructions from the central processing unit. This unit mainly consists of a circuit consisting of S8050 transistors Q13 and Q14, 4.7kΩ resistors R84 and R86, and 1N4007 freewheeling diodes D13 and D14 to control the on and off of the VALVE7 extraction solenoid valve and the VALVE8 extraction solenoid valve. When the central processing unit outputs a control signal, the signal is input into the base of the SS8050 transistor through the 4.7kΩ resistor, controlling the conduction and cutoff of the transistor, and further controlling the attraction and disconnection of relays K7 and K8 to achieve on-off control of the extraction solenoid valve. In conjunction with pressure regulation, extraction pressure is controlled in stages. Among them, the relay attraction time is ≤10ms, which ensures the rapid response of the solenoid valve on and off, so that pressure regulation can be carried out in a timely and accurate manner to meet the pressure requirements of different extraction stages.

[0043] The user interaction unit is used for baristas to input pressure curve parameters and for ordinary users to call preset pressure curves. The operation instructions are transmitted to the central processing unit through a level conversion and filtering circuit composed of buttons, resistors, and capacitors;

[0044] The user interface unit is used for baristas to input pressure curve parameters and for users to call preset pressure curves. It transmits operational commands to the central processing unit via a level conversion and filtering circuit consisting of a PH2.0 interface, 10kΩ pull-up resistors R11-R18, 10Ω current-limiting resistors R20-R27, and 100nF filter capacitors C21-C28. When a user presses buttons SW1-SW8, the voltage level in the circuit changes. The 10kΩ pull-up resistors pull the voltage level high when the button is not pressed and pull it low when the button is pressed. The 10Ω current-limiting resistors limit current to protect circuit components. The 100nF filter capacitor filters out ≥20mV of key jitter noise, ensuring a level flip time of ≤5ms when a button is pressed, ensuring reliable command input. Users can use buttons to enter digital pressure parameters, time node parameters, and select preset coffee bean types such as light roast, dark roast, and roast degree. Operations can also be performed via the touchscreen display, making it convenient for users with different operating habits and lowering the operational barriers to coffee making.

[0045] The power expansion unit is used to expand and control the coffee machine's peripherals. It drives the solid-state relay through a drive circuit composed of a chip and resistors, and can control peripheral devices such as heating and water pumps.

[0046] Power expansion unit: used to expand and control coffee machine peripherals. This unit drives the solid-state relay through a driver circuit consisting of a ULN2003APWR chip and 1kΩ resistors R74-R79, and can control peripherals such as heating and water pumps.

[0047] The central processing unit (CPU) stores the barista's customized pressure curve data. Based on the real-time pressure feedback from the pressure detection unit and the user interaction unit's instructions, it outputs a PWM signal or a level signal. This signal is then controlled by the power amplifier to coordinate the pressure adjustment execution unit and the motor voltage adjustment component to achieve accurate reproduction of the pressure curve.

[0048] Central Processing Unit: Used to store barista-customized pressure curve data, including at least 3 groups of independent curves, each group with ≥5 pressure-time segment nodes, and node time accuracy ≤1s. Based on the real-time pressure feedback from the pressure detection unit and the user interaction unit command, it outputs a PWM signal frequency of 0-20kHz, a duty cycle of 0-100% or a level signal. The power amplifier component controls the pressure adjustment execution unit and the motor voltage adjustment component to work together to achieve "precise control of the pressure curve with an adjustment accuracy of ≤±0.3bar. The curve data is stored in the internal Flash storage area. The STC8H4K64TLCD.451 microcontroller in the central processing unit is the core. The pressure signal processed by the pressure detection unit is received through the PC0 / PC1 pins, and the operation command transmitted by the user interaction unit is received through the PA series pins. Upon receiving the user's operation command, the microcontroller in the central processing unit calls the pressure curve stored in the internal Flash storage area. The PID control algorithm calculates the deviation and generates a corresponding control signal. If the pressure needs to be adjusted, a PWM signal is output through the PB0 / PB1 pin. After the signal is amplified by power amplifier components such as the IRF3205PBF field-effect transistor, the motor voltage is continuously adjustable in the range of 0-24V, thereby achieving precise adjustment of the boost pump pressure in the range of 2-15bar. At the same time, the on and off of the solenoid valve in the pressure regulation execution unit is controlled to achieve accurate reproduction of the pressure curve. In addition, this unit also supports wireless communication modules such as Bluetooth and Wi-Fi expansion, reserves a UART2 interface and level conversion circuit, supports Bluetooth / Wi-Fi module expansion, and can remotely upload barista-optimized pressure curve data and download preset curve libraries through mobile phones and tablets. It can also modify pressure curve parameters in real time, realize remote debugging and curve updates, and enhance the intelligence and convenience of the device.

[0049] like Figures 1 to 7 As shown, the pressure detection unit includes at least one set of pressure sensors and a signal conditioning circuit, which can convert the current signal output by the pressure sensor into a voltage signal.

[0050] Specifically, the signal conditioning circuit includes 10Ω resistors R43 and R88, 100nF capacitors C34 and C50, and a BAV99 diode. The 4-20mA current signal output by each sensor is processed by an independent signal conditioning circuit: first, the current-to-voltage conversion is completed by the 10Ω resistors R43 and R88, and then the high-frequency noise is attenuated by ≥30dB by the low-pass filter circuit composed of 100nF capacitors C34 and C50. Finally, the BAV99 diode performs limiting protection to ensure that the voltage signal input to the central processing unit is stable in the safe range of 1.05-4.5V. The two processed signals are respectively transmitted to the ADC input port of the central processing unit, and the dual-channel data is compared and fused in real time through the internal algorithm. When any sensor fails or the data is abnormal, the system automatically switches to the normal channel to continue working, and triggers an alarm prompt at the same time to ensure the continuity and reliability of pressure signal acquisition.

[0051] like Figures 1 to 7 As shown, the pressure detection unit adopts a dual-path parallel detection design, including a first pressure sensor and a second pressure sensor. The first pressure sensor and the second pressure sensor independently collect pressure signals during the coffee extraction process. The output signals of the two are processed by a signal conditioning circuit composed of independent resistors, capacitors, and diodes, and then transmitted to the central processing unit to ensure the reliability and anti-interference of pressure signal acquisition.

[0052] Specifically, the pressure detection unit adopts a dual-path parallel design. The output signals of the first pressure sensor and the second pressure sensor are processed by independent R43 / C34 / BAV99 and R88 / C50 / BAV99 circuits, and then input into the MCU through the AD_STRESS1 / AD_STRESS2 interface to achieve redundant detection and ensure signal reliability.

[0053] like Figures 1 to 7 As shown, the pressure curve stored in the central processing unit contains multiple time-pressure segmented points, and the pressure adjustment rate of each segmented point is 0.1-2 bar / s. The central processing unit dynamically adjusts the output of the pressure adjustment execution unit through the PID control algorithm to achieve precise pressure control. The PID control algorithm runs inside the microcontroller in the central processing unit.

[0054] Specifically, the central processing unit outputs PWM signals through the PWM_M1 / PWM_M2 interface. The central processing unit is based on the STC8H4K64TLCD.451 microcontroller. Its internal Flash memory is divided into a special area for storing pressure curve data. Each pressure curve is set by the user through the user interaction unit and contains at least 5 time-pressure segment points. After amplification by the IRF3205 field-effect transistor, the motor voltage is adjusted to 0-24V, the pressure regulation rate is controlled at 0.1-2bar / s, and the regulation accuracy is ≤±0.3bar.

[0055] like Figures 1 to 7 As shown, the PID control algorithm calculates the deviation between the real-time pressure feedback from the pressure detection unit and the target pressure of the pressure curve in real time, and dynamically adjusts the control signal output to the pressure regulation execution unit according to the preset proportional, integral and differential parameters.

[0056] Specifically, the PID control algorithm calculates the pressure deviation in real time based on the MCU, outputs a control signal with a duty cycle of 0-100% through the PWM_M1 / PWM_M2 interface, and cooperates with the solenoid valve drive circuit of the pressure regulation execution unit to achieve dynamic pressure adjustment. The algorithm parameters work in coordination with the hardware interface through software configuration.

[0057] like Figures 1 to 7 As shown, the power expansion unit includes at least one solid-state relay driving circuit to achieve level conversion between the I / O port and the relay.

[0058] Specifically, the power expansion unit uses the ULN2003APWR chip as the core driver device. The unit contains 6 independent solid-state relay drive channels. The specific working process is that the control signal output by the central processing unit is input into the ULN2003APWR chip through a 1kΩ resistor. The chip amplifies and level-converts the signal and drives the solid-state relay to work. The solid-state relay contact capacity is ≥2A / 250VAC, which can stably control the on and off of peripherals, so that the continuous extraction water temperature fluctuation is ≤±1℃, which helps to improve the extraction stability. In addition to controlling heating and water pumps, it can also be adapted to control peripherals such as steam generators to achieve coordinated control of multiple parameters such as pressure, temperature, and steam, further expanding the function of the device to meet the needs of different coffee making processes.

[0059] like Figures 1 to 7 As shown, the user interaction unit includes a touch display screen and mechanical button interaction forms, which are used to input digital pressure parameters, time node parameters, and select preset coffee bean types, roasting degrees and other options, which is convenient for users with different operating habits and reduces the operating threshold.

[0060] Specifically, when the user interaction unit is a touch display, it supports quick operations such as gesture sliding and clicking during use, which can be selected according to user needs. The touch display is an optional expansion module, and its hardware circuit is connected to the PB6-PB13 pins of the central processing unit through a parallel bus. When the user interaction unit is a mechanical button interaction, 8 groups of mechanical button circuits SW1-SW8 have corresponding functions: SW1-SW4: numeric keys for quick input of parameters, SW5: Confirm / Save key, SW6: Return / Cancel key, SW7: Mode switching key manual / automatic, SW8: Menu key, which can input digital pressure parameters, time node parameters or select preset coffee bean types such as light roasting, dark roasting, roasting degree and other options to lower the operation threshold.

[0061] like Figures 1 to 7 As shown, the central processing unit supports wireless communication modules, which can remotely upload barista-optimized pressure curve data and download preset curve libraries through mobile terminals. It can also modify pressure curve parameters in real time, realize remote debugging and curve updates, and enhance the intelligence and convenience of the device.

[0062] Specifically, the central processing unit has a reserved UART2 interface and a communication interface, which can be expanded to connect external devices to realize curve data management. The current hardware architecture supports communication with external modules through the I / O port. The system supports two wireless module expansions, the ESP8266WiFi module is configured by default, and the HC-05 Bluetooth module is configured as an alternative. Through the wireless communication function, the barista can remotely adjust the extraction parameters on the other side of the bar.

[0063] This solution also provides a voltage conversion method for a semi-automatic coffee machine

[0064] The following steps are included:

[0065] S1: Pressure Acquisition: During the coffee extraction process, dual pressure sensors are located at key nodes in the extraction pipeline to synchronously collect pressure data. The 4-20mA current signal is converted into a voltage signal through a 10Ω resistor. After being filtered by a 100nF capacitor and protected by a BAV99 diode, it is transmitted to the central processing unit. The dual-sensor redundant design can automatically compare the two channels of data. When one channel is abnormal, it immediately switches to the normal channel, ensuring continuous and reliable pressure data and laying the foundation for accurate extraction. The pressure parameters during the coffee extraction process are collected by the pressure detection unit, conditioned by R43 / R88, C34 / C50, and BAV99, and then input into the PC0 / PC1 signal conditioning circuit for processing and transmission to the central processing unit, and then execute S2;

[0066] S2: Command Interaction: Through the interactive unit consisting of eight sets of mechanical buttons SW1-SW8, the barista can enter custom pressure parameters or directly call preset curves. The button signals are processed by a 10kΩ pull-up resistor, a 10Ω current-limiting resistor, and a 100nF filter capacitor before being transmitted to the control core. This allows for quick selection of preset curves corresponding to different coffee beans, such as light roast and dark roast, enabling a "one-click call" function. Pressure curve parameters are entered through the user interaction unit or a preset pressure curve is called. After processing by R11-R18, R20-R27, and C21-C28, the PA pin receives the operation command, transmits it to the central processing unit, and then executes S3;

[0067] S3: Curve calculation and control: The central processing unit retrieves the stored pressure curve data, compares the real-time pressure with the target pressure curve, and generates a control signal based on the PID control algorithm for each group of at least 5 time-pressure nodes. The microcontroller in the central processing unit retrieves the node data stored in the Flash memory, and the PID algorithm calculates the deviation and generates a PWM signal to PB0 / PB1, and then executes S4;

[0068] S4: Pressure regulation execution: The pressure regulation execution unit receives the control signal, dynamically adjusts the control signal according to the real-time pressure feedback based on the PID control algorithm, outputs the pulse signal through the PWM_M1 / M2 interface, adjusts the motor voltage after amplification by the IRF3205 field-effect transistor, and controls the on and off of the VALVE7 extraction solenoid valve and the VALVE8 extraction solenoid valve at the same time, achieving dynamic regulation within the pressure range of 2-15 bar. The pressure fluctuation can be controlled within ±0.3 bar, and then executes S5;

[0069] S5: Multiple peripherals collaborate to control power in the extraction environment. The power expansion unit drives 6 solid-state relays through the ULN2003APWR chip to collaboratively control peripherals such as the heating tube and water pump. For example, the water temperature is preheated to 92±1°C before extraction, and the water temperature fluctuation is maintained at ≤±1°C during extraction. The steam volume is synchronously adjusted according to the segmented points of the pressure curve to provide a stable environment support for the extraction of different coffee beans.

[0070] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0071] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A voltage conversion system for a semi-automatic coffee machine, characterized in that: It includes a pressure detection unit and a central processing unit; Pressure detection unit, used to collect pressure parameters during coffee extraction; The pressure regulation execution unit is used to receive instructions from the central processing unit, and control the on and off of the extraction solenoid valve with the help of a circuit composed of a transistor, a resistor and a freewheeling diode, and realize segmented control of the extraction pressure in conjunction with pressure regulation; The user interaction unit is used for baristas to input pressure curve parameters and for ordinary users to call preset pressure curves. The operation instructions are transmitted to the central processing unit through a level conversion and filtering circuit composed of buttons, resistors, and capacitors; The power expansion unit is used to expand and control the coffee machine's peripherals. It drives the solid-state relay through a drive circuit composed of a chip and resistors, and can control peripheral devices such as heating and water pumps. The central processing unit is used to store the barista's customized pressure curve data. Based on the real-time pressure feedback from the pressure detection unit and the instructions of the user interaction unit, it outputs a PWM signal or a level signal. The power amplifier element controls the pressure adjustment execution unit and the motor voltage adjustment component to work together to achieve accurate reproduction of the pressure curve.

2. The voltage conversion system of a semi-automatic coffee machine according to claim 1, characterized in that: The pressure detection unit includes at least one set of pressure sensors and a signal conditioning circuit, which can convert the current signal output by the pressure sensor into a voltage signal.

3. The voltage conversion system of a semi-automatic coffee machine according to claim 2, characterized in that: The pressure detection unit adopts a dual-path parallel detection design, including a first pressure sensor and a second pressure sensor. The first pressure sensor and the second pressure sensor independently collect pressure signals during the coffee extraction process. The output signals of the two are processed by a signal conditioning circuit composed of independent resistors, capacitors, and diodes, and then transmitted to the central processing unit to ensure the reliability and anti-interference of pressure signal collection.

4. The voltage conversion system of a semi-automatic coffee machine according to claim 1, characterized in that: The pressure curve stored in the central processing unit includes multiple time-pressure segmentation points, and the pressure regulation rate of each segmentation point is 0.1-2 bar / s. The central processing unit dynamically adjusts the output of the pressure regulation execution unit through the PID control algorithm to achieve precise pressure control.

5. The voltage conversion system of a semi-automatic coffee machine according to claim 4, characterized in that: The PID control algorithm calculates in real time the deviation between the real-time pressure fed back by the pressure detection unit and the target pressure of the pressure curve, and dynamically adjusts the control signal output to the pressure regulation execution unit according to preset proportional, integral and differential parameters.

6. The voltage conversion system of a semi-automatic coffee machine according to claim 1, characterized in that: The power expansion unit includes at least one solid-state relay driving circuit to achieve level conversion between the I / O port and the relay.

7. The voltage conversion system of a semi-automatic coffee machine according to claim 1, characterized in that: The user interaction unit includes a touch display screen and mechanical button interaction forms, which are used to input digital pressure parameters, time node parameters, and select preset coffee bean types, roasting degrees and other options, making it convenient for users with different operating habits to use and lowering the operating threshold.

8. The voltage conversion system of a semi-automatic coffee machine according to claim 1, characterized in that: The central processing unit supports a wireless communication module, which can remotely upload barista-optimized pressure curve data and download a preset curve library through a mobile terminal. It can also modify pressure curve parameters in real time, realize remote debugging and curve updates, and enhance the intelligence and convenience of the device.

9. A method for changing the pressure of a semi-automatic coffee machine according to any one of claims 1 to 8, characterized in that: The following steps are included: S1: Pressure acquisition: The pressure parameters during coffee extraction are collected through the pressure detection unit, processed by the signal conditioning circuit, and transmitted to the central processing unit, and then S2 is executed; S2: Command interaction: Input pressure curve parameters or call preset pressure curve through the user interaction unit, which is received by the pin after processing, and the operation command is transmitted to the central processing unit, and then S3 is executed; S3: Curve calculation and control: The central processing unit retrieves the stored pressure curve data, compares the real-time pressure with the target pressure curve, and generates a control signal based on the PID control algorithm to make the pressure fluctuation ≤±0.3bar. The microcontroller in the central processing unit retrieves the node data stored in the Flash memory, and the PID algorithm calculates the deviation and generates a PWM signal to PB0 / PB1, and then executes S4; S4: Pressure regulation execution: The pressure regulation execution unit receives the control signal, controls the on / off of the extraction solenoid valve, adjusts the motor voltage, etc., to achieve dynamic adjustment of the extraction pressure. The PWM signal is amplified by IRF3205 to control the motor. At the same time, VALVE7 / 8 is driven on and off by Q13 / Q14, and then S5 is executed. S5: Peripheral collaborative control: The power expansion unit coordinates and controls peripherals such as heating and water pumps according to the instructions of the central processing unit to help maintain a stable extraction environment.

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