A small, fast, accurate and controllable positive and negative pressure generating device

Abstract

The utility model discloses a small, fast, accurate and controllable positive and negative pressure generating device, which relates to the technical field of inkjet printers, specifically a small, fast, accurate and controllable positive and negative pressure generating device, comprising a shell, wherein a display button assembly, a data storage assembly, a main control panel, a pressure sensor, a negative pressure pump, an air intake valve, a positive pressure pump, an air pipe, a solenoid valve and a connector are installed inside the shell, and a buffer gas cylinder is connected to the outside of the shell through a connector. Through the coordinated setting of the air intake valve and the solenoid valve, the small, fast, accurate and controllable positive and negative pressure generating device has the effect of improving the stability of the negative pressure output, through the coordinated setting of the air intake valve and the buffer gas cylinder, the small, fast, accurate and controllable positive and negative pressure generating device has the effect of improving the reaction speed and accuracy of the buffer gas cylinder, and through the setting of the air intake valve, the small, fast, accurate and controllable positive and negative pressure generating device has the effect of improving the service life.

Description

Technical Field

[0001] The utility model relates to the technical field of inkjet printers, in particular to a small-sized, fast, accurate and controllable positive and negative pressure generating device. Background Art

[0002] Inkjet printer is a common digital printing device that can print digital graphics or text on the surface of different materials. In this process, the nozzle will continuously spray ink onto the surface of the object. In order to ensure the stable flow of ink, the inkjet printer is usually equipped with a negative pressure system. The negative pressure system can form a low-pressure area around the nozzle. The ink is sucked by this low pressure, which can make the ink in the nozzle flow steadily and avoid problems such as blockage and ink leakage. At the same time, the negative pressure system can also adjust the pressure of the nozzle to mix the ink with the air, so as to achieve a better printing effect and greatly improve the printing efficiency and quality.

[0003] At present, most of the negative pressure generating devices on the market use constant pressure technology to control the negative pressure pump. When the pressure in the buffer gas tank reaches the set value, the solenoid valve and the negative pressure pump are quickly closed. In order to improve the stability of the negative pressure output, the volume of the buffer gas cylinder is often made larger. Therefore, the volume of the negative pressure generating device is generally larger. The large-volume buffer gas cylinder will reduce the reaction speed of the device. The negative pressure pump controlled by constant pressure makes the pressure control less precise. When the pressure in the gas cylinder deviates from the set value, the vacuum pump and the solenoid valve are frequently started, causing the pressure fluctuation amplitude in the buffer bottle to be larger, thereby affecting the inkjet printing effect. Utility Model Content

[0004] 1. Technical issues to be resolved

[0005] In view of the deficiencies in the prior art, the utility model provides a small, fast, accurate and controllable positive and negative pressure generating device, which solves the problems raised in the above-mentioned background technology.

[0006] (II) Technical solution

[0007] To achieve the above objectives, the utility model is implemented through the following technical solutions: a small, fast, accurate and controllable positive and negative pressure generating device, including a shell, wherein a display button assembly, a data storage assembly, a main control board, a pressure sensor, a negative pressure pump, an air intake valve, a positive pressure pump, an air pipe, a solenoid valve and a connector are installed inside the shell, and a buffer gas cylinder is connected to the outside of the shell through a connector, and the display button assembly, the data storage assembly, the pressure sensor and the solenoid valve are all wired to the main control board through cables, and the air pipe connects the pressure sensor, the negative pressure pump, the air intake valve, the positive pressure pump and the buffer gas cylinder, wherein a solenoid valve is arranged between the air pipe and the negative pressure pump, the air intake valve and the positive pressure pump, and a power input protection circuit, a DC-DC power conversion circuit, a fault signal detection circuit, a control signal detection circuit, a solenoid valve control drive circuit, a positive pressure pump drive circuit, a pressure sensor sampling circuit, an ADC analog-to-digital conversion circuit, a data storage circuit, a pulse width modulation circuit, an alarm circuit, an RS485 communication circuit, input and output connectors and a central processing unit are respectively arranged on the main control board.

[0008] Preferably, a separate circuit board is provided in the display button assembly, and the circuit board is provided with a digital tube display circuit, a digital tube segment code driving circuit, a key circuit, an input and output connector and a central processing unit, etc. The assembly is fixedly mounted on the main control board by studs, and the display button assembly J1 socket is connected to the main control circuit board J1 socket through a connector with a wire, and the 1st and 6th pins of the J1 connector of the main control board provide working power for the key display assembly, and the voltage of the power supply is set to 5V. The 3rd and 4th terminals of the J1 connector are communication signal lines, and the communication adopts a TTL serial communication method with simple wiring and high real-time performance. The input end of the digital tube display circuit on the control board of the display button assembly is connected to the output end of the digital tube segment code driving circuit, and the output end of the key circuit is connected to the input end of the central processing unit of the display button assembly. The display button assembly is used to receive the pressure value set by the user, and display the collected air pressure on the display screen in real time. At the same time, when an abnormality occurs in the device, the abnormal information is displayed on the display screen.

[0009] Preferably, the input end of the solenoid valve is connected to the output end of the solenoid valve control drive circuit of the main control board through a connector, the input end of the negative pressure pump is connected to the output end of the pulse width modulation circuit of the main control board through a connector, the input end of the positive pressure pump is connected to the positive pressure pump drive circuit of the main control board through a connector, the pressure sensor is connected to the output end of the solenoid valve assembly of the main control board through an air pipe and a bridge assembly, the output end of the pressure sensor sampling circuit is connected to the input end of the ADC analog-to-digital conversion circuit of the main control board, the data storage assembly is connected to the central processing unit of the main control board through a signal line, the input end of the alarm circuit is connected to the output end of the central processing unit of the main control board, and the output end of the RS485 communication circuit is connected to the input end of the input and output connector of the main control board through a wire.

[0010] Preferably, after obtaining the pressure value set by the user through the display button component or the communication interface terminal, the PID control method is used to output a pulse width modulation signal to drive the corresponding solenoid valve, negative pressure pump and positive pressure pump to work. When the air pressure is set to positive pressure, the solenoid valve and the air intake valve controlling the negative pressure pump are closed, and the solenoid valve and the positive pressure pump controlling the positive pressure pump are opened. When the air pressure reaches the set value, the positive pressure pump and the solenoid valve controlling the positive pressure pump are closed, and the air pressure micro-adjustment mode is entered. When the air pressure is set to negative pressure, the solenoid valve controlling the positive pressure pump is closed and the solenoid valve, the negative pressure pump and the air intake valve controlling the negative pressure pump are opened. When the air pressure reaches the set value, due to the action of the air intake valve, the negative pressure pump continuously works in a constant duty cycle control mode. In this mode, the central processing unit dynamically adjusts the control voltage of the negative pressure pump in real time according to the pressure value sampled by the pressure sensor, so that the air pressure is stabilized at a constant set value.

[0011] Preferably, a negative pressure pump is used to generate negative pressure, a control line of the negative pressure pump is connected to the main control board, the negative pressure pump is driven by a pulse width modulation circuit on the main control board, and an air inlet of the negative pressure pump is connected to a buffer gas cylinder through a solenoid valve, which is used to extract the air in the buffer gas cylinder to obtain a set negative pressure value.

[0012] Preferably, a positive pressure pump is used to generate positive pressure. The control coil of the positive pressure pump is connected to the main control board and driven by the MOSFET circuit on the main control board. The air outlet of the positive pressure pump is connected to the buffer gas cylinder through a solenoid valve, which is used to input air into the buffer gas cylinder to obtain a set positive pressure value.

[0013] Preferably, the pressure sensor is connected to the buffer gas cylinder through a gas connecting valve, collects the gas pressure in the buffer gas cylinder in real time, and converts the pressure value into a corresponding analog voltage and transmits it to the ADC sampling circuit of the main control board. The sampling circuit converts the analog signal into a corresponding digital quantity and provides it to the central processing unit.

[0014] Preferably, the ADC analog-to-digital conversion circuit on the main control board includes a 16-bit high-precision ADC conversion chip, which transmits the collected pressure signal to the central processing unit on the main control board through the I2C bus. The central processing unit converts the collected digital quantity into a pressure value and outputs a corresponding control signal to the drive circuit, thereby controlling the operation of the corresponding air pump. The data storage component is connected to the central processing unit through a data line and is used to store pressure data and event information. The input and output interface includes a power input terminal, a signal input terminal, and a communication terminal. The power input terminal is used to provide the voltage required for the operation of the device, the signal input terminal is used to receive an external control signal, and the communication terminal is used for the device to communicate with an external controller. The power module converts the external input voltage into the working voltage required by the circuit and provides it to the central processing unit, ADC sampling circuit, drive circuit, display button component data storage component and pressure sensor on the main control board.

[0015] The utility model provides a small, fast, accurate and controllable positive and negative pressure generating device, which has the following beneficial effects:

[0016] 1. The small-sized, fast, accurate and controllable positive and negative pressure generating device, through the coordinated setting of the intake valve and the solenoid valve, has the effect of improving the stability of the negative pressure output. The opening and closing of the intake valve can be controlled by the solenoid valve to control the flow of air from the intake valve into the trachea. Controlling the intake volume of the intake valve can change the air pressure in the trachea, making it the third factor for changing the air pressure, making the air pressure adjustment faster to improve the stability of the air pressure. The role of the intake valve is equivalent to negative feedback, and the negative feedback makes the system pressure more stable.

[0017] 2. The small-scale, fast, accurate and controllable positive and negative pressure generating device, through the coordinated setting of the air intake valve and the buffer gas cylinder, has the effect of improving the reaction speed and accuracy of the buffer gas cylinder. By controlling the air intake amount of the air intake valve, the air pump can work in a linear state compared to the adjustable circuit. The linear control of the air intake speed can make the air pressure reach the set value faster and more accurately. Increasing the control of the air pressure by the air intake valve can make the air pressure stable, so there is no need to increase the volume of the buffer gas cylinder to stabilize the airflow. Since the volume of the buffer gas cylinder is small, it can quickly respond to changes in air pressure, thereby improving the reaction speed and accuracy of the buffer gas cylinder.

[0018] 3. This small, fast, accurate and controllable positive and negative pressure generating device, through the setting of the intake valve, has the effect of increasing the service life. Since the intake valve can adjust the air pressure of the air pipe, the frequency of starting and stopping the positive and negative pressure pumps can be reduced, thereby increasing the service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A schematic diagram of a schematic block diagram of the utility model;

[0020] Figure 2 A schematic diagram of the external connection of the utility model;

[0021] Figure 3 It is a schematic diagram of the principle diagram of the main control board of the utility model;

[0022] Figure 4 The utility model is a schematic diagram showing the principle diagram of the key assembly.

[0023] In the figure: 1. Shell; 2. Display button assembly; 3. Data storage assembly; 4. Main control board; 5. Pressure sensor; 6. Negative pressure pump; 7. Inlet valve; 8. Positive pressure pump; 9. Air pipe; 10. Solenoid valve; 11. Connector; 12. Buffer gas cylinder. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments.

[0025] See also Figures 1 to 4The utility model provides a technical solution: a small-sized, fast, accurate and controllable positive and negative pressure generating device, comprising a shell 1, a display button assembly 2, a data storage assembly 3, a main control board 4, a pressure sensor 5, a negative pressure pump 6, an air intake valve 7, a positive pressure pump 8, an air pipe 9, an electromagnetic valve 10 and a connector 11 are installed inside the shell 1, a buffer gas cylinder 12 is connected to the outside of the shell 1 through the connector 11, the display button assembly 2, the data storage assembly 3, the pressure sensor 5 and the electromagnetic valve 10 are all connected to the main control board 4 by cables, the air pipe 9 connects the pressure sensor 5, the negative pressure pump 6, the air intake valve 7, the positive pressure pump 8 and the buffer gas cylinder 12, wherein the air pipe 9 is provided between the negative pressure pump 6, the air intake valve 7 and the positive pressure pump 8 There is a solenoid valve 10, and the main control board 4 is respectively provided with a power input protection circuit, a DC-DC power conversion circuit, a fault signal detection circuit, a control signal detection circuit, a solenoid valve 10 control drive circuit, a positive pressure pump 8 drive circuit, a pressure sensor 5 sampling circuit, an ADC analog-to-digital conversion circuit, a data storage circuit, a pulse width modulation circuit, an alarm circuit, an RS485 communication circuit, an input and output connector and a central processing unit, etc. A separate circuit board is provided in the display button component 2, and a digital tube display circuit, a digital tube segment code drive circuit, a key circuit, an input and output connector and a central processing unit, etc. are provided in the circuit board. The component is fixedly mounted on the main control board 4 by a stud, and the display button component 2J1 socket is connected The connector with a wire is connected to the J1 socket of the main control circuit board. The 1st and 6th pins of the J1 connector of the main control board 4 provide working power for the key display component. The voltage of the power supply is set to 5V. The 3rd and 4th terminals of the J1 connector are communication signal lines. The communication adopts the TTL serial communication method with simple wiring and high real-time performance. The input end of the digital tube display circuit on the control board of the display key component 2 is connected to the output end of the digital tube segment code drive circuit. The output end of the key circuit is connected to the input end of the central processing unit of the display key component 2. The display key component 2 is used to receive the pressure value set by the user and display the collected air pressure on the display screen in real time. At the same time, when an abnormality occurs in the device, the abnormal information is displayed on the display screen. The input end of the solenoid valve 10 is connected to the input end of the digital tube display circuit on the control board of the display key component 2. The connector is connected to the output end of the solenoid valve 10 control driving circuit of the main control board 4, the input end of the negative pressure pump 6 is connected to the output end of the pulse width modulation circuit of the main control board 4 through the connector, the input end of the positive pressure pump 8 is connected to the positive pressure pump 8 driving circuit of the main control board 4 through the connector, the pressure sensor 5 is connected to the output end of the solenoid valve 10 component of the main control board 4 through the air pipe 9 and the bridge component, the output end of the sampling circuit of the pressure sensor 5 is connected to the input end of the ADC analog-to-digital conversion circuit of the main control board 4, the data storage component 3 is connected to the central processing unit of the main control board 4 through the signal line, the input end of the alarm circuit is connected to the output end of the central processing unit of the main control board 4, and the output end of the RS485 communication circuit is connected to the input end of the input and output connector of the main control board 4 through the wire.After obtaining the pressure value set by the user through the display button component 2 or the communication interface terminal, the PID control method is used to output a pulse width modulation signal to drive the corresponding solenoid valve 10, the negative pressure pump 6 and the positive pressure pump 8 to work. When the air pressure is set to positive pressure, the solenoid valve 10 and the air intake valve 7 that control the negative pressure pump 6 are closed, and the solenoid valve 10 and the positive pressure pump 8 that control the positive pressure pump 8 are opened. When the air pressure reaches the set value, the positive pressure pump 8 and the solenoid valve 10 that controls the positive pressure pump 8 are closed, and the air pressure micro-adjustment mode is entered. When the air pressure is set to negative pressure, the solenoid valve 10 that controls the positive pressure pump 8 is closed and the solenoid valve 10, the negative pressure pump 6 and the air intake valve 7 that control the negative pressure pump 6 are opened. When the air pressure reaches the set value, due to the air intake valve 7 The negative pressure pump 6 continuously works in a constant duty cycle control mode. In this mode, the central processing unit dynamically adjusts the control voltage of the negative pressure pump 6 in real time according to the pressure value sampled by the pressure sensor 5, so that the air pressure is stabilized at a constant set value. The negative pressure pump 6 is used to generate negative pressure. The control line of the negative pressure pump 6 is connected to the main control board 4. The negative pressure pump 6 is driven by the pulse width modulation circuit on the main control board 4. The air inlet of the negative pressure pump 6 is connected to the buffer gas cylinder 12 through the solenoid valve 10, which is used to extract the air in the buffer gas cylinder 12 to obtain the set negative pressure value. The positive pressure pump 8 is used to generate positive pressure. The control coil of the positive pressure pump 8 is connected to the main control board 4 and is driven by the MOSFET circuit on the main control board 4. The air outlet of the positive pressure pump 8 The solenoid valve 10 is connected to the buffer gas cylinder 12 to input air into the buffer gas cylinder 12 to obtain a set positive pressure value. The pressure sensor 5 is connected to the buffer gas cylinder 12 through the gas connection valve to collect the gas pressure in the buffer gas cylinder 12 in real time, and convert the pressure value into a corresponding analog voltage and transmit it to the ADC sampling circuit of the main control board 4. The sampling circuit converts the analog signal into a corresponding digital quantity and provides it to the central processing unit. The ADC analog-to-digital conversion circuit on the main control board 4 includes a 16-bit high-precision ADC conversion chip. The conversion chip transmits the collected pressure signal to the central processing unit on the main control board 4 through the I2C bus, and the central processing unit converts the collected digital quantity into a digital quantity. After converting to pressure value, the corresponding control signal is output to the driving circuit, thereby controlling the corresponding air pump to work. The data storage component 3 is connected to the central processor through a data line to store pressure data and event information. The input and output interface includes a power input terminal, a signal input terminal, and a communication terminal. The power input terminal is used to provide the voltage required for the device to work, the signal input terminal is used to receive external control signals, and the communication terminal is used for the device to communicate with an external controller. The power module converts the external input voltage into the working voltage required by the circuit and provides it to the central processor, ADC sampling circuit, driving circuit, display button component 2, data storage component 3, and pressure sensor 5 on the main control board 4.

[0026] When in use, the small, fast, accurate and controllable positive and negative pressure generating device box is fixed on the operation panel of the main box of the UV inkjet printing equipment for user convenience. The output gas nozzle on the device box is connected to the input end of the external buffer gas bottle 12 through the air pipe 9, and the output end of the buffer gas bottle 12 is connected to the input end of the secondary ink cartridge of the UV inkjet printer through the air pipe 9. The output end of the secondary ink cartridge is connected to the printing nozzle. As the UV inkjet printing is running, the nozzle will continuously spray ink onto the surface of the object, and then solidify on the printed object after being irradiated by the ultraviolet lamp. As the ink in the secondary ink cartridge decreases, the space in the cavity of the buffer gas bottle 12 connected to the secondary ink cartridge gradually increases, and the air pressure gradually decreases. The positive and negative pressure generating device adjusts the driving voltage of the negative pressure pump 6 after collecting the pressure change through the pressure sensor 5 connected to the buffer gas bottle 12, and then adjusts the air intake speed of the buffer gas bottle 12 to maintain the pressure value in the buffer gas bottle 12 constant at the set value. During the use of the UV inkjet printer, the UV inkjet printer often stops and waits for a period of time due to workload or other known reasons. At this time, the residual ink attached to the nozzle will thicken. For example, thickened ink will cause the nozzle to be clogged. At this time, the positive pressure generator of the fast, accurate and controllable positive and negative pressure generating device will play its role. After the operator presses the ink pressing button on the operation panel of the UV inkjet printer, the ink pressing button transmits the ink pressing signal to the signal input terminal of the main control board through the wire. After the central processor of the main control board samples the ink pressing signal, it starts the positive pressure generating process, closes the negative pressure solenoid valve 10 and the air inlet valve 7, opens the positive pressure solenoid valve 10 and the positive pressure pump 8, and when the air pressure reaches the set value, closes the positive pressure pump 8 and the positive pressure solenoid valve 10, and enters the air pressure micro-motion Adjustment mode, under the action of positive pressure, the ink blocked in the nozzle is squeezed out by positive pressure, and the nozzle is unblocked. The positive pole of diode D4 is connected to the J6 input terminal, and the negative pole is connected to the F1 self-recovery insurance. When the power supply is reversed, D4 is cut off and the circuit does not work to prevent damage to the subsequent circuit due to reverse power supply. The F1 self-recovery insurance prevents excessive current. D11 is a bidirectional TVS fast diode. When the power supply fluctuates, it prevents overvoltage from causing damage to the subsequent circuit. The combination of D4, F1, and D11 can improve the EMC performance of the system and increase system stability. R10 The D6 and D7 light emitting diodes indicate whether the input power is normal. U4 and U5 are DC-DC power conversion circuits. 24V is connected to the first foot of U4 and U5. The second foot of U4 and U5 is a PWM high-frequency pulse width modulation signal. The second foot output of U4 and U5 is connected to the filter inductors L1 and L2 respectively. The other foot of the filter inductors L1 and L2 is connected to the positive electrode of the electrolytic capacitors C6 and C12 respectively. After the pulse width modulation signal is filtered by the inductor and capacitor, two 5V DC power supplies are output, which are 5V1 and 5V2 respectively. The 5V output is connected to the third foot of U4 and U5 respectively. This foot is the FeedBACK feedback pin. After feedback from the third foot, the 5V power supply will be more accurate.5V1 mainly provides power for the central processor, pressure sensor 5, ADC analog-to-digital conversion circuit, data storage circuit, and RS485 communication circuit on the main control board. 5V2 mainly provides power for the positive pressure pump 8, alarm buzzer, and button display component. U2 is the central processor, which is a wide-voltage processor that can work in the 3V-5V voltage range and has high EMC anti-interference performance. U2 outputs CTL1, CTL2, and CTL3 signals at pins 38, 37, and 32 to control the conduction and cutoff of U3A, U3B, and U3C MOSFET field effect tubes respectively. U3A, U3B, and U3C respectively drive the conduction and closure of the positive pressure pump 8 solenoid valve 10, the negative pressure pump 6 solenoid valve 10, and the intake valve 7 solenoid valve 10; U2 pin 33 outputs CTL4 control signal to control U7 The MOSFET field effect tube is turned on and off, and U7 drives the positive pressure pump 8 to run or stop; the output section of the 30th foot of U2 is connected to the resistor R25, and the other end of R25 is connected to the CTL5 control signal. CTL5 controls the operation or stop of the negative pressure pump 6. R25 is used for current limiting to prevent overcurrent from damaging the central processing unit. Usually CTL5 is a pulse width modulation signal, which can make the negative pressure pump 6 work in a linear state, improve the accuracy of negative pressure output and control sensitivity;. Figure 3 J8 is the pressure sensor interface. The pressure sensor 5 is a gauge pressure sensor with a measurement range of ±50kPa and an output range of 0-4.5V. The sensor is connected to the buffer gas cylinder 12 through a gas connection valve to measure the gas pressure in the buffer gas cylinder 12 in real time. The output terminal of the 5th foot of the pressure sensor 5 is connected to a low-pass RC filter network composed of C19, R30, and C20; Figure 3U10 is the ADC analog-to-digital conversion circuit. The 4th pin of U10 is connected to the output of R30, the 5th pin is connected to the DC differential signal, the 9th and 10th pins are connected to the 5th and 6th pins of the central processor for the I2C bus to complete the data exchange with the central processor. U6 is the RS485 communication component, which mainly includes the RS485 transceiver and its peripheral circuits. The model is SN65HVD3082E, which is used to network and exchange data for multiple positive and negative pressure devices, so as to find the faulty device in time when the positive and negative pressure devices fail, without having to check them one by one. At the same time, it is convenient for UV inkjet printing equipment to quickly configure and collect pressure data. D8 and D12 in the communication component form an EMC absorption circuit to protect subsequent circuits from EMC infringement. The input end of R3 resistor is connected to the alarm drive signal, and the output end is connected to the input end of Q1 transistor. The output end of Q1 transistor is connected to LS1 buzzer. When the device fails, the buzzer is driven to sound an alarm to prompt the operator. U8 is a data storage circuit. This circuit is a NorFlash storage unit used to store real-time sampling data and fault information. U8 The output terminals of pins 1, 2, 5 and 6 are connected to the input terminals of pins 18, 25, 16 and 14 of the central processor. The central processor reads and writes the data storage circuit through these pins. The key display component circuit board is respectively provided with a digital tube display circuit, a digital tube segment code drive circuit, a key circuit, an input and output connector and a central processing unit, etc. U1 is the central processor. The J1 socket is connected to the J1 socket of the main control circuit board through a connector with a wire. Pins 1 and 6 of the J1 connector provide working power for the key display component. The voltage of the power supply is set to 5V. Terminals 3 and 4 of the J1 connector are for communication. Signal line, through which the key display component receives the display information sent by the main control board, and transmits the key information to the central processing unit on the main control board. The output ends of the four keys are connected to the 11th, 12th, 1st and 2nd pins of the central processing unit for the operator to input information. U2 is a 4-digit display digital tube. The 1st, 2nd, 3rd, 4th, 5th, 7th, 10th and 11th pins of the digital tube are segment code drive input ends, which are respectively connected to the output ends of the 20th, 9th, 7th, 6th, 5th, 17th, 18th and 19th pins of the central processing unit to form a segment code drive circuit. Q3, Q2, Q1 and Q4 are NPN transistors, whose input ends are connected to the 3rd, 15th, 16th and 4th pin output ends of the central processing unit to drive the conduction of the 4-digit digital tubes respectively. J2 is a programming and debugging download line interface, whose input ends are connected to the 11th and 12th pins of the central processing unit for program downloading, simulation and debugging.

[0027] In summary, the small, fast, accurate and controllable positive and negative pressure generating device can control the flow of air from the intake valve 7 into the trachea 9 by controlling the opening and closing of the intake valve 7 through the solenoid valve 10. Controlling the intake amount of the intake valve 7 can change the air pressure in the trachea 9, making it the third factor for changing the air pressure, making the air pressure adjustment faster to improve the stability of the air pressure. The role of the intake valve 7 is equivalent to negative feedback, and negative feedback makes the system pressure more stable. By controlling the intake amount of the intake valve 7, the air pump works in a linear state than the adjustable circuit, and linear control of the intake speed can make the air pressure faster. The set value can be reached more accurately. Increasing the control of the air pressure by the air intake valve 7 can make the air pressure stable, and there is no need to increase the volume of the buffer gas cylinder 12 to stabilize the airflow. Since the buffer gas cylinder 12 is small in size, it can quickly respond to changes in air pressure, thereby improving the reaction speed and accuracy of the buffer gas cylinder 12. Through the setting of the air intake valve 7, the small, fast, accurate and controllable positive and negative pressure generating device has the effect of increasing the service life. Since the air intake valve 7 can adjust the air pressure of the air pipe 9, the frequency of starting and stopping the positive and negative pressure pumps 6 can be reduced, thereby increasing the service life.

[0028] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes within the technical scope disclosed by the present invention according to the technical scheme and the utility model concept of the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A small, fast, accurate and controllable positive and negative pressure generating device, comprising a housing (1), characterized in that: The housing (1) is internally installed with a display button assembly (2), a data storage assembly (3), a main control board (4), a pressure sensor (5), a negative pressure pump (6), an air intake valve (7), a positive pressure pump (8), an air pipe (9), an electromagnetic valve (10) and a connector (11). The outside of the housing (1) is connected to a buffer gas cylinder (12) via the connector (11). The display button assembly (2), the data storage assembly (3), the pressure sensor (5) and the electromagnetic valve (10) are all wired to the main control board (4) via cables. The air pipe (9) connects the pressure sensor (5), the negative pressure pump (6), the air intake valve (7), The positive pressure pump (8) and the buffer gas cylinder (12) are connected, wherein a solenoid valve (10) is arranged between the air pipe (9) and the negative pressure pump (6), the air inlet valve (7) and the positive pressure pump (8), and the main control board (4) is respectively provided with a power input protection circuit, a DC-DC power conversion circuit, a fault signal detection circuit, a control signal detection circuit, a solenoid valve (10) control drive circuit, a positive pressure pump (8) drive circuit, a pressure sensor (5) sampling circuit, an ADC analog-to-digital conversion circuit, a data storage circuit, a pulse width modulation circuit, an alarm circuit, an RS485 communication circuit, an input and output connector and a central processing unit, etc.

2. The small-sized, fast, accurate and controllable positive and negative pressure generating device according to claim 1 is characterized in that: A separate circuit board is provided in the display key assembly (2). The circuit board is provided with a digital tube display circuit, a digital tube segment code driving circuit, a key circuit, an input / output connector, and a central processing unit. The assembly is fixedly mounted on the main control board (4) by means of studs. The J1 socket of the display key assembly (2) is connected to the J1 socket of the main control circuit board via a connector with a wire. Pins 1 and 6 of the J1 connector of the main control board (4) provide a working power supply for the key display assembly. The voltage of the power supply is set to 5V. Terminals 3 and 4 of the J1 connector are communication signal lines. The communication adopts a TTL serial communication method with simple wiring and high real-time performance. The input end of the digital tube display circuit on the control board of the display key assembly (2) is connected to the output end of the digital tube segment code driving circuit. The output end of the key circuit is connected to the input end of the central processing unit of the display key assembly (2). The display key assembly (2) is used to receive a pressure value set by a user and display the collected air pressure on the display screen in real time. When an abnormality occurs in the device, the abnormality information is displayed on the display screen.

3. The small-sized, fast, accurate and controllable positive and negative pressure generating device according to claim 1 is characterized in that: The input end of the solenoid valve (10) is connected to the output end of the solenoid valve (10) control driving circuit of the main control board (4) through a connector, the input end of the negative pressure pump (6) is connected to the output end of the pulse width modulation circuit of the main control board (4) through a connector, the input end of the positive pressure pump (8) is connected to the positive pressure pump (8) driving circuit of the main control board (4) through a connector, the pressure sensor (5) is connected to the output end of the solenoid valve (10) component of the main control board (4) through an air pipe (9) and a bridge component, the output end of the sampling circuit of the pressure sensor (5) is connected to the input end of the ADC analog-to-digital conversion circuit of the main control board (4), the data storage component (3) is connected to the central processing unit of the main control board (4) through a signal line, the input end of the alarm circuit is connected to the output end of the central processing unit of the main control board (4), and the output end of the RS485 communication circuit is connected to the input end of the input-output connector of the main control board (4) through a wire.

4. The small-sized, fast, accurate and controllable positive and negative pressure generating device according to claim 1 is characterized in that: After obtaining the pressure value set by the user through the display button assembly (2) or the communication interface terminal, a pulse width modulation signal is outputted in a PID control mode to drive the corresponding solenoid valve (10), the negative pressure pump (6) and the positive pressure pump (8) to work. When the set air pressure is positive pressure, the solenoid valve (10) and the air inlet valve (7) controlling the negative pressure pump (6) are closed, and the solenoid valve (10) and the positive pressure pump (8) controlling the positive pressure pump (8) are opened. When the air pressure reaches the set value, the positive pressure pump (8) and the solenoid valve (10) controlling the positive pressure pump (8) are closed. , enter the air pressure micro-adjustment mode. When the air pressure is set to negative pressure, the solenoid valve (10) controlling the positive pressure pump (8) is closed and the solenoid valve (10) controlling the negative pressure pump (6), the negative pressure pump (6) and the air intake valve (7) are opened. When the air pressure reaches the set value, due to the action of the air intake valve (7), the negative pressure pump (6) continuously works in the constant duty cycle control mode. In this mode, the central processing unit dynamically adjusts the control voltage of the negative pressure pump (6) in real time according to the pressure value sampled by the pressure sensor (5), so that the air pressure is stabilized at the constant set value.

5. The small-sized, fast, accurate and controllable positive and negative pressure generating device according to claim 1 is characterized in that: The negative pressure pump (6) is used to generate negative pressure. The control line of the negative pressure pump (6) is connected to the main control board (4). The negative pressure pump (6) is driven by a pulse width modulation circuit on the main control board (4). The air inlet of the negative pressure pump (6) is connected to the buffer gas cylinder (12) through the solenoid valve (10) and is used to extract the air in the buffer gas cylinder (12) to obtain a set negative pressure value.

6. The small-sized, fast, accurate and controllable positive and negative pressure generating device according to claim 1 is characterized in that: The positive pressure pump (8) is used to generate positive pressure. The control coil of the positive pressure pump (8) is connected to the main control board (4) and driven by the MOSFET circuit on the main control board (4). The air outlet of the positive pressure pump (8) is connected to the buffer gas cylinder (12) through the solenoid valve (10) and is used to input air into the buffer gas cylinder (12) to obtain a set positive pressure value.

7. The small-sized, fast, accurate and controllable positive and negative pressure generating device according to claim 1 is characterized in that: The pressure sensor (5) is connected to the buffer gas cylinder (12) via a gas connection valve, collects the gas pressure in the buffer gas cylinder (12) in real time, and converts the pressure value into a corresponding analog voltage value and transmits it to the ADC sampling circuit of the main control board (4). The sampling circuit converts the analog signal into a corresponding digital value and provides it to the central processing unit.

8. The small-sized, fast, accurate and controllable positive and negative pressure generating device according to claim 1 is characterized in that: The ADC analog-to-digital conversion circuit on the main control board (4) includes a 16-bit high-precision ADC conversion chip. The conversion chip transmits the collected pressure signal to the central processing unit on the main control board (4) through the I2C bus. The central processing unit converts the collected digital quantity into a pressure value and then outputs a corresponding control signal to the drive circuit, thereby controlling the corresponding air pump to work. The data storage component (3) is connected to the central processing unit through a data line and is used to store pressure data and event information. The input and output interface includes a power input terminal, a signal input terminal, and a communication terminal. The power input terminal is used to provide the device with a voltage required for operation. The signal input terminal is used to receive an external control signal. The communication terminal is used for the device to communicate with an external controller. The power module converts the external input voltage into the working voltage required by the circuit and provides it to the central processing unit, the ADC sampling circuit, the drive circuit, the display button component (2), the data storage component (3), and the pressure sensor (5) on the main control board (4).

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