A general intelligent magnetic stirrer for chemical laboratory

Abstract

This invention discloses a general-purpose intelligent magnetic stirrer for chemical laboratories, belonging to the field of chemical laboratory technology. It includes: a constant current source circuit for providing a stable current to the speed control knobs; a microcontroller with a built-in ADC module that sequentially collects the resistance values ​​of each speed control knob via DMA and generates corresponding PWM waves based on the resistance values; a brushless DC motor whose speed is controlled by the PWM waves generated by the microcontroller, and whose speed feedback line is connected to the microcontroller through an isolation circuit to achieve PID closed-loop control; an aluminum alloy stirring platform equipped with eight independently operating motors and the speed control system; and a communication interface enabling a host computer to intelligently control the stirrer. This invention ensures more accurate collection of resistance values, thereby improving the accuracy of motor speed control. This accuracy is particularly important for experiments requiring long-term, continuous, and uniform stirring.

Description

Technical Field

[0001] This utility model belongs to the field of chemical laboratory technology, and in particular to a general-purpose intelligent magnetic stirrer for chemical laboratories. Background Technology

[0002] Some liquid samples in chemical experiments require continuous, uniform stirring for extended periods, often several hours or more, and must be stirred in a sealed environment. Many magnetic stirrers on the market can meet this need. However, these magnetic stirrers have several problems:

[0003] Many domestically produced mixers primarily use pure hardware circuitry to control the mixing speed (e.g., using a single chip to generate a PWM wave to adjust the motor speed), lacking a microprocessor. This results in imprecise speed control and a lack of intelligent control methods. Because many domestic mixers do not use microprocessors (microcontrollers) for speed control, they cannot achieve closed-loop speed control. Many foreign mixers offer precise speed control, and some use microprocessors for speed adjustment, but they are generally single-unit mixers, meaning one mixer can only mix one sample at a time. At most, they can typically mix four samples simultaneously. Utility Model Content

[0004] The purpose of this invention is to provide a universal intelligent magnetic stirrer for chemical laboratories to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, this utility model provides the following technical solution: a general-purpose intelligent magnetic stirrer for chemical laboratories, comprising:

[0006] A constant current source circuit is used to provide a stable current to the speed control knob;

[0007] The microcontroller has a built-in ADC module that collects the resistance values ​​of each speed control knob in turn via DMA and generates corresponding PWM waves based on the resistance values.

[0008] The speed of the brushless DC motor is controlled by the PWM wave generated by the microcontroller, and the speed feedback line is connected to the microcontroller through an isolation circuit to realize PID closed-loop control.

[0009] The aluminum alloy mixing table is equipped with eight independently operating motors and a speed control system.

[0010] The communication interface enables the host computer to intelligently control the mixer.

[0011] In this preferred embodiment, the constant current source circuit ensures the stability of the current, so that the voltage difference generated when passing through the external adjustable resistor is accurate. This voltage difference is amplified and filtered before being input to the internal ADC of the microcontroller.

[0012] In this preferred embodiment, the microcontroller uses the PWM mode of a timer to write the duty cycle value into the corresponding timer register, thereby changing the duty cycle of the PWM wave and achieving precise speed control of the motor.

[0013] In this preferred embodiment, the intelligent magnetic stirrer includes one or more communication interfaces, supporting direct connection to a host computer, allowing users to control the stirrer for constant speed, variable speed, and timing via software installed on the host computer.

[0014] In this preferred embodiment, the aluminum alloy stirring table is suitable for sample containers of different diameters, thus improving the versatility and applicability of the equipment.

[0015] In this preferred embodiment, the analog, digital, and motor control sections of the circuit design employ complete isolation technology, enhancing the overall reliability and stability of the machine.

[0016] In this preferred embodiment, each speed control knob is equipped with an independent filtering circuit between itself and the microcontroller to reduce the impact of external electromagnetic interference on resistance value acquisition and ensure the accuracy of signal transmission.

[0017] In this preferred embodiment, the intelligent magnetic stirrer also includes an emergency stop button. When the emergency stop button is pressed, the power supply to all motors is immediately cut off through the control circuit to ensure the safety of the operator and the safe operation of the equipment.

[0018] In this preferred embodiment, a temperature regulator is provided below the aluminum alloy stirring table. The temperature regulator includes a heating element and a temperature sensor, which can automatically adjust the temperature of the stirred sample according to the set temperature parameters, and is suitable for experimental conditions that require reaction at a specific temperature.

[0019] In this preferred embodiment, the intelligent magnetic stirrer is also equipped with a wireless communication module. In addition to connecting to a host computer via a communication interface, it can also connect to a mobile device or remote server via a wireless network, which facilitates users to remotely monitor and control the working status of the stirrer and supports data upload and download functions.

[0020] Compared with the prior art, the technical effects and advantages of this utility model are as follows:

[0021] This general-purpose intelligent magnetic stirrer for chemistry labs uses a constant current source circuit to provide a stable current to the speed control knob, ensuring accurate voltage difference when passing through an external adjustable resistor. This voltage difference is amplified and filtered before being input to the microcontroller's built-in ADC module. Compared to traditional pure hardware circuit control methods, this approach ensures more precise resistance values, thereby improving the accuracy of motor speed control. This precision is particularly important for experiments requiring long-term, continuous, and uniform stirring.

[0022] The microcontroller uses DMA (Distributed Dynamic Range) to sequentially collect the resistance values ​​of each speed control knob and generates corresponding PWM waves to control the motor speed based on these values. DMA eliminates the need for the CPU to monitor the ADC register status in real time, significantly reducing the processor load and improving the overall system efficiency. Furthermore, the use of a microprocessor for control enables closed-loop speed control, further enhancing the accuracy and stability of speed control.

[0023] The speed feedback line of the brushless DC motor is connected to the microcontroller through an isolation circuit. The PID algorithm is used to adjust the PWM waveform to achieve precise speed control. Compared with the traditional open-loop control system, the PID closed-loop control can dynamically adjust the PWM waveform according to the difference between the actual speed and the set value, ensuring that the motor always runs at the preset speed, which greatly enhances the stability and response speed of the system.

[0024] The aluminum alloy stirring table is equipped with an independently operating motor and speed control system, supporting intelligent control via a communication interface or wireless communication module connected to a host computer or mobile device. This not only allows for the simultaneous processing of multiple samples but also enhances the flexibility and convenience of the experimental process through remote control. Furthermore, the design supports complex control modes such as constant speed, variable speed, and timed operation, making it suitable for a wider range of experimental needs. Attached Figure Description

[0025] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the structure of this utility model;

[0027] Figure 2 This is a schematic diagram of the installation structure of the stirring motor of this utility model;

[0028] Figure 3 This is a schematic diagram of the communication interface of this utility model;

[0029] Figure 4 This is a block diagram of the internal circuit principle of a single motor stirring control circuit of this utility model;

[0030] Figure 5 This is a schematic diagram of the disassembly structure of the electrical board protection mechanism of this utility model;

[0031] Figure 6 This is a schematic diagram of the disassembled structure of the electrical board protection mechanism of this utility model.

[0032] Explanation of reference numerals in the attached figures:

[0033] In the diagram: 1. Aluminum alloy mixing table; 2. Mixing magnet; 3. Speed ​​control knob; 4. Power switch; 5. Electrical board; 6. Mixing motor; 7. Communication interface; 8. Electrical board protection mechanism; 9. First protective plate; 10. Second protective plate; 11. Miniature air buffer spring; 12. Buffer airbag. Detailed Implementation

[0034] In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention can be practiced without one or more of these details. In other instances, certain technical features well-known in the art have not been described in order to avoid confusion with the present invention.

[0035] Unless otherwise defined, the directions mentioned herein, such as up, down, left, right, front, back, inside, and outside, are based on the directions shown in the figures of this utility model, and are explained here together.

[0036] This embodiment provides, for example Figures 1 to 6 The illustrated general-purpose intelligent magnetic stirrer for chemical laboratories includes:

[0037] A constant current source circuit is used to provide a stable current to the speed control knob 3;

[0038] The microcontroller has a built-in ADC module that collects the resistance values ​​of each speed control knob 3 in turn via DMA and generates corresponding PWM waves based on the resistance values.

[0039] Electrical panel (5) is located in the lower part of the internal compartment of the machine;

[0040] The speed of the brushless DC motor 6 is controlled by the PWM wave generated by the microcontroller, and the speed feedback line is connected to the microcontroller through an isolation circuit to realize PID closed-loop control.

[0041] The aluminum alloy mixing table 1 is equipped with 8 independently operating motors and a speed control system.

[0042] Communication interface 7 enables the host computer to intelligently control the mixer.

[0043] An electrical board protection mechanism 8 is disposed between the electrical board 5 and the brushless DC motor 6, and is capable of absorbing the mechanical vibration generated by the operation of the brushless DC motor 6. The electrical board protection mechanism 8 is elastically abutted against the electrical board 5. The electrical board protection mechanism 8 includes a second protection plate 10 installed at the tail end of multiple brushless DC motors 6, a first protection plate 9 installed on the bottom surface of the electrical board 5 by screws, and an elastic buffer absorption component disposed between the second protection plate 10 and the first protection plate 9. The elastic buffer absorption component includes miniature air buffer springs 11 installed in a rectangular arrangement at the four corners of the top surface of the second protection plate 10. The top ends of the four miniature air buffer springs are fixedly connected to the bottom surface of the first protection plate 9. The elastic buffer absorption component also includes a buffer airbag 12 disposed between the four miniature air buffer springs 11 and bonded to the top surface of the second protection plate 10. The top surface of the buffer airbag 12 is bonded to the bottom surface of the first protection plate 9. When the brushless direct motor 6 vibrates during operation, the vibration force can be transmitted to the miniature air buffer spring 11 and the buffer air bag 12 through the second protective plate 10, thereby absorbing the vibration force and achieving the effect of buffering and shock absorption, thus realizing the shock absorption and protection of the electrical board 5.

[0044] In this embodiment, the constant current source circuit ensures the stability of the current, so that the voltage difference generated when passing through the external adjustable resistor is accurate. The voltage difference is amplified and filtered before being input to the internal ADC of the microcontroller.

[0045] In this embodiment, the microcontroller uses the PWM mode of the timer to write the duty cycle value into the corresponding timer register in order to change the duty cycle of the PWM wave and achieve precise speed regulation of the motor 6.

[0046] In this embodiment, the intelligent magnetic stirrer includes one or more communication interfaces 7, which support direct connection to a host computer, allowing users to control the stirrer to constant speed, variable speed, and time using software installed on the host computer.

[0047] In this embodiment, the aluminum alloy stirring table 1 is suitable for sample containers of different diameters, which improves the versatility and applicability of the equipment.

[0048] In this embodiment, the analog, digital and motor control parts of the circuit design adopt complete isolation technology, which enhances the reliability and stability of the whole machine.

[0049] In this embodiment, each speed control knob 3 is equipped with an independent filtering circuit between itself and the microcontroller to reduce the influence of external electromagnetic interference on the resistance value acquisition and ensure the accuracy of signal transmission.

[0050] In this embodiment, the intelligent magnetic stirrer also includes an emergency stop button. When the emergency stop button is pressed, the power supply to all motors 6 is immediately cut off by the control circuit to ensure the safety of the operator and the safe operation of the equipment.

[0051] See Figure 4 As can be seen, firstly, a high-precision constant current source is designed in the circuit. Then, the constant current source (I) flows through an external adjustable resistor (used for rotational speed control). The current generates a voltage difference (V) across the resistor; the larger the resistance, the larger the voltage difference. After passing through an amplification circuit and a filtering circuit, the generated voltage difference is input to the internal ADC of the microprocessor (microcontroller). The microprocessor converts the ADC signal to obtain the corresponding resistance value, and then generates a corresponding PWM wave based on the resistance value using an internal timer to control the motor speed control line and adjust the motor speed. Simultaneously, the microprocessor and a switching circuit (high-side drive) control the motor's power supply line, thereby controlling the motor's power supply. The motor also has a speed feedback line, which, after passing through an isolation circuit, is input to the microprocessor for speed determination.

[0052] In this embodiment, since there are a total of 8 motors, the above circuit scheme has 8 identical modules. Furthermore, for the conversion of the ADC inside the microprocessor, a DMA conversion method can be used in software (using DMA only requires the microcontroller program to periodically read the conversion data from memory without needing to monitor the ADC registers in real time). This method can easily achieve high-speed conversion of the 8-channel ADC without occupying the microprocessor core, and its efficiency is much higher than the traditional polling conversion method.

[0053] In this embodiment, for the PWM wave required for speed control, the microprocessor uses the PWM mode of the internal timer (the timer is a peripheral of the microcontroller; once the peripheral register is set, the peripheral will automatically execute the operation of generating the PWM wave, without the microcontroller program needing to continuously execute the PWM wave program, which is equivalent to not occupying the microprocessor's core). The duty cycle value can be easily changed by simply writing it into the corresponding timer register. Compared to using the switching mode of the microprocessor's I / O port to control the duty cycle, this solution can achieve very high precision and higher duty cycle resolution, making the microcontroller program more concise and efficient.

[0054] In this embodiment, because the speed feedback line of the brushless DC motor is connected to the microprocessor, the microcontroller software can know the current motor speed in real time. For precise speed control, a PID control algorithm can be used to control the motor speed, resulting in very high speed control accuracy. An external communication interface is also provided, as shown in the figure below. This interface can be directly connected to a host computer to achieve intelligent speed control. For example, it can perform timed, constant-speed, and variable-speed control of the motor speed, making the instrument highly intelligent.

[0055] In this embodiment, a temperature regulator is provided below the aluminum alloy stirring table 1. The temperature regulator includes a heating element and a temperature sensor, which can automatically adjust the temperature of the stirred sample according to the set temperature parameters. It is suitable for experimental conditions that require reaction at a specific temperature.

[0056] In this embodiment, the intelligent magnetic stirrer is also equipped with a wireless communication module. In addition to connecting to the host computer through the communication interface 7, it can also connect to mobile devices or remote servers through a wireless network, which makes it convenient for users to remotely monitor and control the working status of the stirrer and supports data upload and download functions.

[0057] Working principle

[0058] This general-purpose intelligent magnetic stirrer for chemical laboratories, when the device is powered on, changes the resistance value by rotating the speed control knob 3. Each speed control knob is connected to an independent filter circuit to reduce the influence of external electromagnetic interference on the resistance value. The constant current source circuit provides a stable current to flow through the speed control knob 3, generating a voltage difference. This voltage difference is amplified and filtered before being input to the ADC built into the microcontroller. The microcontroller uses DMA to collect the resistance value of each speed control knob in turn and converts it into a digital signal.

[0059] Based on the collected resistance value, the microcontroller calculates the corresponding duty cycle and writes this value into the corresponding timer register to generate a PWM waveform to control the speed of the brushless DC motor 6. The motor speed feedback line is connected to the microcontroller through an isolation circuit using magnetic isolation technology to monitor the motor speed in real time. Precise speed control is achieved by adjusting the PWM waveform based on a PID algorithm. Eight independently operating motors and the speed control system are directly controlled via the speed control knob 3 on the aluminum alloy stirring table 1, suitable for sample containers of different diameters. Through the communication interface 7 or a wireless communication module, it can be connected to a host computer or mobile device, allowing users to perform intelligent control such as constant speed, variable speed, and timing using software installed on these devices. Data upload and download functions are also supported for convenient experimental data management.

[0060] In case of emergency, press the emergency stop button to immediately cut off the power supply to all motors 6, ensuring personnel safety and safe operation of the equipment. A temperature control device, including a heating element and a temperature sensor, is located beneath the aluminum alloy stirring table 1. Temperature parameters are set according to experimental requirements, and the temperature of the stirred sample is automatically adjusted, suitable for reaction experiments requiring specific temperature conditions.

[0061] After completing the experiment, turn off the device power. The microcontroller will execute a shutdown procedure, save necessary data, and disconnect all circuit connections to ensure optimal performance upon the next startup.

[0062] It should be noted that, in this document, relational terms such as "one" and "two" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, the phrase "comprising an element defined as..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0063] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A universal intelligent magnetic stirrer for chemical laboratories, characterized in that, include: A constant current source circuit is used to provide a stable current to the speed control knob (3); The microcontroller has a built-in ADC module that collects the resistance values ​​of each speed control knob (3) in turn via DMA and generates corresponding PWM waves based on the resistance values. Electrical panel (5) is located in the lower part of the internal compartment of the machine; The speed of the brushless DC motor (6) is controlled by the PWM wave generated by the microcontroller, and the speed feedback line is connected to the microcontroller through the isolation circuit to realize PID closed-loop control. An aluminum alloy mixing table (1) is equipped with eight independently operating motors and a speed control system. The communication interface (7) enables the host computer to intelligently control the mixer; An electrical board protection mechanism (8) is provided between the electrical board (5) and the brushless DC motor (6) and can absorb the mechanical vibration generated by the operation of the brushless DC motor (6). The electrical board protection mechanism (8) is elastically abutted against the electrical board (5).

2. A universal intelligent magnetic stirrer for chemical laboratory as claimed in claim 1, wherein: The electrical board protection mechanism (8) includes a second protective plate (10) installed at the tail end of a plurality of brushless DC motors (6), a first protective plate (9) installed on the bottom surface of the electrical board (5) by screws, and an elastic buffer absorption component disposed between the second protective plate (10) and the first protective plate (9); The voltage difference generated by the constant current source circuit when connected to an external adjustable resistor is accurate. This voltage difference is amplified and filtered before being input to the internal ADC of the microcontroller.

3. A universal smart magnetic stirrer for chemical laboratory as claimed in claim 2, wherein: The elastic buffer absorption component includes miniature air buffer springs (11) arranged in a rectangular pattern and installed at the four corners of the top surface of the second protective plate (10). The top ends of the four miniature air buffer springs are fixedly connected to the bottom surface of the first protective plate (9). The microcontroller uses the PWM mode of the timer to write the duty cycle value into the corresponding timer register in order to change the duty cycle of the PWM wave and realize the precise speed regulation of the motor (6).

4. The universal intelligent magnetic stirrer for chemical laboratory according to claim 3, characterized in that: The elastic buffer absorption component also includes a buffer airbag (12) disposed between four miniature air buffer springs (11) and bonded to the top surface of the second protective plate (10), wherein the top surface of the buffer airbag (12) is bonded to the bottom surface of the first protective plate (9). The intelligent magnetic stirrer includes one or more communication interfaces (7), which support direct connection to a host computer, allowing users to control the stirrer to constant speed, variable speed and time through software installed on the host computer.

5. A universal smart magnetic stirrer for chemical laboratory as claimed in claim 4, wherein: The aluminum alloy stirring table (1) is suitable for sample containers of different diameters.

6. A universal smart magnetic stirrer for chemical laboratory as claimed in claim 5, wherein: Each speed control knob (3) is equipped with an independent filter circuit between itself and the microcontroller to reduce the influence of external electromagnetic interference on the resistance value acquisition and ensure the accuracy of signal transmission.

7. A universal smart magnetic stirrer for chemical laboratory as claimed in claim 6, wherein: The intelligent magnetic stirrer also includes an emergency stop button. When the emergency stop button is pressed, the power supply to all motors (6) is immediately cut off through the control circuit to ensure the safety of the operator and the safe operation of the equipment.

8. A universal smart magnetic stirrer for chemical laboratories as claimed in claim 7, wherein: The aluminum alloy stirring table (1) is equipped with a temperature regulator, which includes a heating element and a temperature sensor. It can automatically adjust the temperature of the stirred sample according to the set temperature parameters and is suitable for experimental conditions that require reaction at a specific temperature.

9. A universal smart magnetic stirrer for chemical laboratory as claimed in claim 8, wherein: The intelligent magnetic stirring instrument is also provided with a wireless communication module, and is connected with a mobile device or a remote server through a wireless network in addition to being connected with a host computer through the communication interface (7).

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