Flow control circuit and pneumoperitoneum machine based on flow control circuit

Abstract

The utility model provides a flow control circuit and a pneumoperitoneum machine based on the flow control circuit. The flow control circuit comprises a flow proportional valve; the flow acquisition circuit is used for acquiring the flow flowing through the flow proportional valve and outputting a voltage value; the control module is electrically connected with the flow acquisition circuit and is used for receiving the voltage value and outputting a PWM signal; the switch module is provided with a stray capacitor, and the switch module is electrically connected with the flow proportional valve and used for controlling opening and closing of the flow proportional valve; and the driving circuit is electrically connected with the control module and the switch module and is used for receiving the PWM signal and driving the switch module to be switched on based on the PWM signal so as to control the flow proportional valve to be switched on or driving the switch module to be switched off so as to control the flow proportional valve to be switched off and synchronously discharge the stored energy on the parasitic capacitor. According to the utility model, the accuracy of gas flow can be effectively improved, and meanwhile, the stability and reliability of the pneumoperitoneum machine are ensured.

Description

Technical Field

[0001] The utility model relates to the field of flow control, in particular to a flow control circuit and a pneumoperitoneum machine based on the flow control circuit. Background Technique

[0002] A pneumoperitoneum machine is a special device for establishing and maintaining pneumoperitoneum in laparoscopic surgery. Through the mechanical pressurized inflation of the pneumoperitoneum machine, the abdominal wall is separated from the viscera, providing sufficient operating space for the surgery and avoiding damage to the viscera when the puncture trocar pierces into the abdominal cavity.

[0003] The flow control of the pneumoperitoneum machine is mainly achieved through components such as proportional valves, switching valves, flow sensors, and control circuits. A medical CO2 pneumoperitoneum machine generally controls the proportional valve by controlling the opening and closing of MOS transistors through an MCU. When the MOS transistor is turned on, the proportional valve opens and the flow increases; when the MOS transistor is turned off, the proportional valve closes and the flow decreases. The opening and closing time of the proportional valve is controlled by adjusting the on and off time of the MOS transistor through PWM. Different combinations of the opening and closing states of the proportional valve achieve the control of multiple flow modes. Due to the existence of the parasitic capacitance of the MOS transistor, there will be a delay in the on and off time of the MOS transistor, which will affect the opening and closing time of the proportional valve at this time, resulting in inaccurate gas flow. At the same time, due to the large electrical signal interference generated when the proportional valve works, it will affect the signals of other module circuits in the system, causing the system to be unstable. Content of the Utility Model

[0004] In order to overcome the defects existing in the above-mentioned prior art, the purpose of the utility model is to provide a flow control circuit and a pneumoperitoneum machine based on the flow control circuit.

[0005] In order to achieve the above object of the utility model, the utility model provides a flow control circuit, including:

[0006] A flow proportional valve;

[0007] A flow acquisition circuit for acquiring the flow rate flowing through the flow proportional valve and outputting a voltage value;

[0008] A control module electrically connected to the flow acquisition circuit for receiving the voltage value and outputting a PWM signal;

[0009] A switching module, the switching module having a parasitic capacitance, the switching module being electrically connected to the flow proportional valve for controlling the opening and closing of the flow proportional valve;

[0010] A drive circuit, electrically connected to the control module and the switch module respectively, is configured to receive the PWM signal and drive the switch module to conduct based on the PWM signal to control the flow proportional valve to open, or drive the switch module to turn off to control the flow proportional valve to close and simultaneously discharge the stored energy on the parasitic capacitance.

[0011] The energy stored in the parasitic capacitance of the switch module in this flow control circuit is discharged to the ground, eliminating the working delay factor of the switch module, thereby enabling the switch module to turn off faster, and thus making the control of the flow more accurate.

[0012] In an alternative solution, the drive circuit includes an opto-isolation circuit;

[0013] The signal input terminal of the opto-isolation circuit is electrically connected to the control module for receiving the PWM signal, and the signal output terminal of the opto-isolation circuit is electrically connected to the switch module for controlling the conduction and turn-off of the switch module.

[0014] In this alternative solution, the opto-isolation circuit isolates the electrical signals of the control part from the electrical signals of the working part of the proportional valve, so that the interference during the operation of the flow proportional valve does not affect the control part.

[0015] In an alternative solution, the switch module includes a MOS transistor, and the parasitic capacitance is located at the gate of the MOS transistor;

[0016] The gate of the MOS transistor is connected to the drive signal output terminal of the drive circuit; the drain of the MOS transistor is electrically connected to the flow proportional valve; the source of the MOS transistor is grounded.

[0017] In an alternative solution, the opto-isolation circuit includes a first opto-coupler and a second opto-coupler;

[0018] The negative terminal of the light-emitting source of the first opto-coupler and the positive terminal of the light-emitting source of the second opto-coupler are both electrically connected to the control module for receiving the PWM signal;

[0019] The positive terminal of the light-emitting source of the first opto-coupler is externally connected to the first voltage output terminal of the power supply circuit, the first terminal of the light-receiving device of the first opto-coupler is externally connected to the second voltage output terminal of the power supply circuit, and the second terminal of the light-receiving device of the first opto-coupler is connected to the gate of the MOS transistor;

[0020] The negative terminal of the light-emitting source of the second opto-coupler is grounded, the first terminal of the light-receiving device of the second opto-coupler is connected to the gate of the MOS transistor, and the second terminal of the light-receiving device of the second opto-coupler is grounded;

[0021] The output voltage value of the second voltage output terminal is greater than the output voltage value of the first voltage output terminal.

[0022] In this alternative solution, the control module outputs a PWM signal. When the PWM signal is at a low level, the first optocoupler conducts, the second optocoupler disconnects, the gate of the MOS transistor is at a high level, and the MOS transistor conducts. At this time, there will be a voltage difference across the flow rate proportional valve, and the flow rate proportional valve opens, allowing gas or liquid to pass through. When the PWM signal is at a high level, the first optocoupler disconnects, the second optocoupler conducts, and at this time the MOS transistor will turn off, there is no voltage difference across the flow rate proportional valve, and the flow rate proportional valve closes. Due to the parasitic capacitance existing at the gate of the MOS transistor, when the PWM waveform changes from a low level to a high level, the second optocoupler will conduct, causing the energy stored in the parasitic capacitance of the MOS transistor to be quickly discharged to the ground through both ends of the light receiver of the second optocoupler, and the turn-off speed of the MOS transistor will be faster, thus making the flow rate control more accurate.

[0023] In an alternative solution, it further includes a number of protection resistors, which are respectively arranged at:

[0024] Between the negative terminal of the light-emitting source of the first optocoupler and the PWM signal output terminal of the control module;

[0025] Between the first terminal of the light receiver of the first optocoupler and the second voltage output terminal of the power supply circuit;

[0026] Between the first terminal of the light receiver of the first optocoupler and the gate of the MOS transistor;

[0027] Between the positive terminal of the light-emitting source of the second optocoupler and the PWM signal output terminal of the control module;

[0028] Between the first terminal of the light receiver of the second optocoupler and the gate of the MOS transistor.

[0029] The setting of the protection resistors in this alternative solution avoids the problem that the light-emitting sources and light receivers of the first optocoupler and the second optocoupler are burned out due to excessive input current.

[0030] In an alternative solution, it further includes a power supply circuit, and the power supply circuit includes:

[0031] A power conversion module, externally connected to the mains power, for converting the mains power into a first supply voltage and supplying power to the flow rate proportional valve;

[0032] An isolated power module, electrically connected to the power conversion module, for converting the first supply voltage into a second supply voltage and supplying power to the flow rate acquisition circuit;

[0033] A buck circuit, electrically connected to the power conversion module, for adjusting the first supply voltage to the second supply voltage and supplying power to the drive circuit.

[0034] Since the inside of the flow proportional valve is a coil, the signal interference generated at the moment of startup and shutdown is very large. This optional solution isolates the power supply part of the flow proportional valve and supplies power separately, which can effectively reduce the signal interference to the control circuit and improve the stability and reliability of the system.

[0035] In an optional solution, the power supply circuit further includes:

[0036] A DCDC circuit, electrically connected to the isolated power supply module, for adjusting the second supply voltage to a third supply voltage and supplying power to the follower circuit of the flow acquisition circuit;

[0037] An LDO circuit, electrically connected to the DCDC circuit, for receiving the third supply voltage and adjusting the third supply voltage to a fourth supply voltage, and supplying power to the control module and / or the optocoupler isolation circuit.

[0038] In an optional solution, the flow acquisition circuit includes:

[0039] A flow sensor for collecting the flow rate and outputting the voltage value;

[0040] A follower circuit, connected to the flow sensor, for receiving the voltage value, amplifying the voltage value and outputting it to the signal input end of the control module.

[0041] In an optional solution, the follower circuit includes an operational amplifier; the signal output end of the flow sensor is connected to the signal input end of the operational amplifier, and the output end of the operational amplifier is connected to the flow signal input end of the control module.

[0042] In this optional solution, the voltage value output by the flow sensor can be accurately input to the operational amplifier and output. Since the output impedance of the follower circuit is very low, when the output voltage of the operational amplifier is given to the flow signal input end of the control module for AD acquisition, this voltage value can be accurately input to the AD part, making the voltage value obtained during the AD acquisition of the control module more accurate and the calculated flow rate value more precise.

[0043] This application also provides a pneumoperitoneum machine, including a pneumoperitoneum machine body and the above-mentioned flow control circuit, and controlling the pneumoperitoneum machine body to supply gas to the surgical process based on this flow control circuit.

[0044] The beneficial effects of the present utility model are:

[0045] 1. By optocoupler isolation, the electrical signals of the control part are isolated from the electrical signals of the working part of the proportional valve, so that the interference during the operation of the flow proportional valve does not affect the control part.

[0046] 2. Since the energy stored in the parasitic capacitance of the MOS transistor can be quickly discharged to the ground synchronously through both ends of the light receiver of the second optocoupler while the MOS transistor is turned off to control the closing of the flow proportional valve, the turn-off speed of the MOS transistor is increased, which can not only reduce the turn-off delay of the MOS transistor but also improve the accuracy of flow control.

[0047] 3. The setting of the isolated power supply module isolates and supplies power to the power part of the flow proportional valve alone, effectively reducing the interference to the control circuit and improving the stability and reliability of the system.

[0048] 4. The design of the follower circuit enables the voltage value output by the flow sensor to be accurately input to the operational amplifier, and the output impedance of the follower circuit is very low, so the voltage value obtained during the AD acquisition of the control module is more accurate, and the calculated flow value is also more accurate.

[0049] 5. This application can effectively improve the accuracy of gas flow, and at the same time ensure the stability and reliability of the pneumoperitoneum machine.

[0050] The additional aspects and advantages of the present utility model will be partly given in the following description, partly will become obvious from the following description, or will be understood through the practice of the present utility model. Brief Description of the Drawings

[0051] The above and / or additional aspects and advantages of the present utility model will become obvious and easy to understand from the description of the embodiments in conjunction with the following drawings, wherein:

[0052] Figure 1 is the principle block diagram of Embodiment 1;

[0053] Figure 2 is the circuit schematic diagram of the isolated power supply module;

[0054] Figure 3 is the schematic diagram of the DCDC circuit;

[0055] Figure 4 is the schematic diagram of the LDO circuit;

[0056] Figure 5 is the schematic diagram of the buck circuit;

[0057] Figure 6 is the schematic diagram of the flow sensor signal acquisition;

[0058] Figure 7 is the schematic diagram of the follower circuit;

[0059] Figure 8 is the schematic diagram of the drive circuit;

[0060] Figure 9 is the schematic diagram of the control module circuit. Detailed implementation manners

[0061] The embodiments of the present utility model will be described in detail below. The examples of the embodiments are shown in the accompanying drawings, in which the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions from beginning to end. The embodiments described below by referring to the accompanying drawings are exemplary and are only used to explain the present utility model, and cannot be understood as a limitation to the present utility model.

[0062] In the description of the present utility model, unless otherwise specified and limited, it should be noted that the terms "installation", "connection", and "connection" should be understood in a broad sense. For example, it can be a mechanical connection or an electrical connection, or it can be the communication inside two elements. It can be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific situations.

[0063] Embodiment 1

[0064] As Figure 1 shown, this embodiment provides a flow control circuit, which can be used to control the flow of gas or liquid. The flow control circuit in this embodiment specifically includes: a flow proportional valve, a flow acquisition circuit, a control module, a switch module, a drive circuit, and a power supply circuit.

[0065] Among them,

[0066] Flow proportional valve: Electrically connected to the switch module, the PWM signal output by the control module drives the opening and closing of the switch module through the drive circuit to control the opening and closing of the flow proportional valve. By controlling the opening and closing of the flow proportional valve, the on and off of the gas or liquid flowing through the flow proportional valve is controlled.

[0067] Flow acquisition circuit: Used to acquire the flow of gas or liquid flowing through the flow proportional valve and output a voltage value. The flow acquisition circuit includes a flow sensor and a follower circuit electrically connected to the flow sensor. The signal output end of the follower circuit is connected to the flow signal input end of the control module. The flow sensor is used to acquire the flow of fluids such as gas or liquid flowing out through the flow proportional valve and output a voltage value to the follower circuit. The follower circuit receives the voltage value output by the flow sensor, amplifies it, and outputs it to the control module. In this embodiment, the flow sensor is preferably but not limited to a digital flow sensor, which is arranged on the pipeline downstream of the flow proportional valve.

[0068] Control module: Electrically connected to the flow acquisition circuit, used to receive the voltage value output by the flow acquisition circuit and output a PWM signal.

[0069] Switch module, the switch module has parasitic capacitance, and the switch module is electrically connected to the flow rate proportional valve, and is used to control the opening and closing of the flow rate proportional valve, so as to control the flow rate of gas or liquid passing through the flow rate proportional valve.

[0070] Drive circuit: electrically connected to the control module and the switch module respectively, and is used to receive the PWM signal output by the control module and drive the switch module to conduct based on the PWM signal to control the flow rate proportional valve to open, or drive the switch module to turn off to control the flow rate proportional valve to close and synchronously discharge the stored energy on the parasitic capacitance in the switch module. The discharge of the stored energy on the parasitic capacitance in the switch module eliminates the working delay factor of the switch module, so as to control the switch module to turn off faster, thereby making the control of the flow rate more accurate. In this embodiment, the drive circuit includes an opto-isolation circuit; the signal input end of the opto-isolation circuit is electrically connected to the control module for receiving the PWM signal, and the signal output end of the opto-isolation circuit is electrically connected to the switch module for controlling the conduction and turn-off of the switch module. Since the inside of the flow rate proportional valve is a coil, the signal interference generated at the moment of startup and shutdown is very large. In this embodiment, the opto-isolation circuit separates the circuit for supplying power to the proportional valve from the circuits of other modules, which can effectively reduce the interference of the signals generated by the flow rate proportional valve on the control circuits of other modules and improve the stability and reliability of the pneumoperitoneum machine circuit system.

[0071] Power supply circuit: separately supplies power to the flow rate proportional valve, flow sensor, drive circuit, etc. Specifically, in this embodiment, the power supply circuit includes: an external mains supply, a power conversion module for converting the mains supply into a first supply voltage and supplying power to the flow rate proportional valve; an isolation power supply module electrically connected to the power conversion module for converting the first supply voltage into a second supply voltage and supplying power to the flow sensor of the flow acquisition circuit; a buck circuit electrically connected to the power conversion module for adjusting the first supply voltage to the second supply voltage and supplying power to the drive circuit; a DCDC circuit electrically connected to the isolation power supply module for adjusting the second supply voltage to a third supply voltage and supplying power to the follower circuit of the flow acquisition circuit; an LDO circuit electrically connected to the DCDC circuit for receiving the third supply voltage and adjusting the third supply voltage to a fourth supply voltage and supplying power to the control module and / or the opto-isolation circuit.

[0072] Preferably but not limited to, in this embodiment, the power conversion module converts the mains supply into a direct current with a voltage of 24V, that is, the first supply voltage, the isolation power supply module converts the direct current of 24V into a direct current with a voltage of 12V, that is, the second supply voltage, the buck circuit converts the direct current of 24V into a direct current with a voltage of 12V, the DCDC circuit converts the direct current of 12V into a direct current with a voltage of 5V, that is, the third supply voltage, and the LDO circuit converts the direct current of 5V into a direct current with a voltage of 3.3V, that is, the fourth supply voltage.

[0073] The specific circuit designs of the power supply circuit, the flow rate acquisition circuit, and the drive circuit are as follows.

[0074] As Figure 2 shown, the isolated power supply module includes an isolated power supply chip U14. Its input terminal is connected to a 24V voltage, and its output terminal outputs a 12V voltage to supply power to the flow sensor. The model of U14 is preferably but not limited to URB2412YMD-20WR3.

[0075] As Figure 3 shown, the 12V voltage output by the isolated power supply module is also converted to a 5V voltage through a DCDC circuit and supplied to the power-consuming modules that require a 5V voltage, such as the follower circuit and the LDO circuit of the flow rate acquisition circuit. In this DCDC circuit, a switching regulator chip with the model ADP2303ARDZ-5.0 is preferably but not limited to be used.

[0076] As Figure 4 shown, the 5V voltage output by the DCDC circuit conversion is also converted to a 3.3V voltage through an LDO circuit and supplied to the power-consuming modules that require a 3.3V power supply, such as the control module and the optocoupler isolation circuit. In this LDO circuit, a linear voltage regulator chip with the model LM1117MPX-3.3 is preferably but not limited to be used.

[0077] As Figure 5 shown, the buck circuit includes a buck module U12. Its input terminal is connected to a 24V voltage, and its output terminal outputs a 12V voltage to supply power to the drive circuit.

[0078] As Figure 6 and Figure 7 shown, the signal output terminal of the flow sensor is connected to the series-connected first resistor R1 and second resistor R2 through a terminal block J1, and the second resistor R2 is grounded; the voltage signal between the first resistor R1 and the second resistor R2 is taken and input to the signal input terminal of the operational amplifier U1 in the follower circuit, and the signal output terminal of the operational amplifier U1 is connected to the flow rate signal input terminal of the control module, as Figure 7 and Figure 9 shown. The model of this operational amplifier U1 is preferably but not limited to MCP6002T.

[0079] When gas or liquid flows through the flow sensor, the flow sensor can convert the above-mentioned flow rate into a corresponding voltage value for output. This voltage value passes through a follower circuit to increase its input impedance, making the input impedance very high. According to the voltage division principle, the larger the impedance, the larger the voltage divided. At this time, the voltage value output by the flow sensor can be accurately input to the operational amplifier U1 and output. Since the output impedance of the follower circuit is very low, when the output voltage of the operational amplifier U1 is given to the flow signal input terminal of the control module for AD acquisition, this voltage value can be accurately input to the AD part, making the voltage value obtained during the AD acquisition of the control module more accurate, and the calculated flow rate value more precise.

[0080] As Figure 8 shown, the switch module includes MOS transistor U5, and the opto-isolation circuit in the drive circuit includes first opto-coupler U3 and second opto-coupler U7.

[0081] The PWM signal output terminal of the control module is connected to the third resistor R3 and then connected to the negative terminal of the light-emitting source of the first opto-coupler U3. The first opto-coupler U3 receives the PWM signal sent by the control module. The positive terminal of the light-emitting source of the first opto-coupler U3 is externally connected to the first voltage output terminal of the power supply circuit, that is, the voltage output terminal of the LDO circuit. In this embodiment, the first voltage output terminal outputs 3.3V DC, that is, the fourth power supply voltage; the first terminal of the light-receiving device of the first opto-coupler U3 is externally connected to the second voltage output terminal of the power supply circuit, that is, the voltage output terminal of the buck circuit. A fourth resistor R4 is connected in series between them. In this embodiment, the second voltage output terminal outputs 12V DC, that is, the second power supply voltage; the second terminal of the light-receiving device of the first opto-coupler U3 is connected to the fifth resistor R5 and then connected to the gate of the MOS transistor U5. The PWM signal output terminal of the control module is also connected to the sixth resistor R6 and then connected to the positive terminal of the light-emitting source of the second opto-coupler U7. The negative terminal of the light-emitting source of the second opto-coupler U7 is grounded. The first terminal of the light-receiving device of the second opto-coupler U7 is connected to the seventh resistor R7 and then connected to the gate of the MOS transistor U5. The second terminal of the light-receiving device of the second opto-coupler U7 is grounded. Among them, the third resistor R3, the fourth resistor R4, the fifth resistor R5, the sixth resistor R6, and the seventh resistor R7 are all protection resistors. The source of the MOS transistor U5 is grounded, and its drain is connected to one end of the flow proportional valve J4. The other end of the flow proportional valve J4 is connected to its operating voltage, which is 24V DC in this embodiment.

[0082] The control module outputs a PWM signal. When the PWM signal is at a low level, the first optocoupler U3 conducts, and the second optocoupler U7 is turned off. At this time, the optocoupler isolation circuit of DC12V conducts with the MOS tube U5, and the current supplies power to the MOS tube U5 through both ends of the photoreceiver of the first optocoupler U3 (that is, flowing through pin 4 and then through pin 3), resulting in the gate of the MOS tube U5 being at a high level of DC12V, causing the drain and source of the MOS tube U5 to be connected, and the MOS tube U5 conducts. At this time, there will be a voltage difference across the flow proportional valve J4 (the 2nd pin of the flow proportional valve J4 is DC24V, and the 1st pin is 0V), and the flow proportional valve J4 conducts and opens, allowing gas or liquid to pass through. When the PWM signal is at a high level, the first optocoupler U3 is turned off, and the second optocoupler U7 conducts. At this time, the energy stored in the gate parasitic capacitance of the MOS tube U5, that is, the voltage, quickly discharges to the ground through both ends of the photoreceiver of the second optocoupler U7, that is, from pin 4 to pin 3, causing the MOS tube U5 to turn off quickly. At this time, the drain and source of the MOS tube U5 are disconnected, there is no voltage difference across the flow proportional valve J4, and the flow proportional valve J4 closes, and the gas or liquid is blocked. Due to the existence of the parasitic capacitance C at the gate of the MOS tube U5, after the PWM waveform changes from a low level to a high level, the second optocoupler U7 will conduct, causing the energy stored in the parasitic capacitance of the MOS tube U5 to quickly discharge to the ground through the seventh resistor R7 and both ends of the photoreceiver of the second optocoupler U7, eliminating the factor of the MOS tube's working delay, and the MOS tube will turn off faster, thus making the control of the flow proportional valve more precise.

[0083] As Figure 9 shown, the control module preferably but not limited to uses the STM32F103 chip of ST company as the main control. After setting the flow threshold in advance, the control module outputs a PWM signal to control the on and off time of the MOS tube, thereby controlling the opening and closing time of the flow proportional valve. At the same time, it receives the voltage value real-time collected by the flow acquisition circuit. The control module converts this voltage value into the corresponding actual flow value and adjusts the width of the PWM signal according to the comparison result between the actual flow value and the pre-set flow threshold, so as to accurately control the start and stop time of the flow proportional valve.

[0084] Embodiment 2

[0085] This embodiment provides a pneumoperitoneum machine. The pneumoperitoneum machine includes a pneumoperitoneum machine body and the flow control circuit described in Embodiment 1. Based on this flow control circuit, the pneumoperitoneum machine body supplies carbon dioxide gas to the surgical process to facilitate the establishment and maintenance of pneumoperitoneum in laparoscopic surgery.

[0086] In the description of this specification, the descriptions referring to terms such as "one embodiment", "some embodiments", "examples", "specific examples", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present utility model. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in a suitable manner in any one or more embodiments or examples.

[0087] Although the embodiments of the present utility model have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present utility model, and the scope of the present utility model is defined by the claims and their equivalents.

Claims

1. A flow control circuit, characterized in that, Comprising: A flow rate proportional valve; A flow rate acquisition circuit for acquiring the flow rate flowing through the flow rate proportional valve and outputting a voltage value; A control module electrically connected to the flow rate acquisition circuit for receiving the voltage value and outputting a PWM signal; A switch module having a parasitic capacitance, the switch module being electrically connected to the flow rate proportional valve for controlling the opening and closing of the flow rate proportional valve; A drive circuit electrically connected to the control module and the switch module respectively for receiving the PWM signal and driving the switch module to conduct based on the PWM signal to control the opening of the flow rate proportional valve, or driving the switch module to turn off to control the closing of the flow rate proportional valve and synchronously discharging the stored energy on the parasitic capacitance.

2. The flow control circuit according to claim 1, wherein The drive circuit includes an opto-isolation circuit; The signal input end of the opto-isolation circuit is electrically connected to the control module for receiving the PWM signal, and the signal output end of the opto-isolation circuit is electrically connected to the switch module for controlling the conduction and turn-off of the switch module.

3. The flow control circuit according to claim 2, wherein The switch module includes a MOS transistor, and the parasitic capacitance is located at the gate of the MOS transistor; The gate of the MOS transistor is connected to the drive signal output end of the drive circuit; the drain of the MOS transistor is electrically connected to the flow rate proportional valve; the source of the MOS transistor is grounded.

4. The flow control circuit according to claim 3, wherein The opto-isolation circuit includes a first opto-coupler and a second opto-coupler; The negative terminal of the light-emitting source of the first opto-coupler and the positive terminal of the light-emitting source of the second opto-coupler are both electrically connected to the control module for receiving the PWM signal; The positive terminal of the light-emitting source of the first opto-coupler is externally connected to the first voltage output terminal of the power supply circuit, the first end of the light-receiving device of the first opto-coupler is externally connected to the second voltage output terminal of the power supply circuit, and the second end of the light-receiving device of the first opto-coupler is connected to the gate of the MOS transistor; The negative terminal of the light-emitting source of the second opto-coupler is grounded, the first end of the light-receiving device of the second opto-coupler is connected to the gate of the MOS transistor, and the second end of the light-receiving device of the second opto-coupler is grounded; The output voltage value of the second voltage output terminal is greater than the output voltage value of the first voltage output terminal.

5. The flow control circuit according to claim 4, wherein It further includes a plurality of protection resistors respectively provided at: Between the negative terminal of the light-emitting source of the first opto-coupler and the PWM signal output terminal of the control module; Between the first end of the light-receiving device of the first opto-coupler and the second voltage output terminal of the power supply circuit; Between the first end of the light-receiving device of the first opto-coupler and the gate of the MOS transistor; Between the positive terminal of the light-emitting source of the second opto-coupler and the PWM signal output terminal of the control module; Between the first end of the light-receiving device of the second opto-coupler and the gate of the MOS transistor.

6. The flow control circuit according to claim 2, wherein It further includes a power supply circuit, and the power supply circuit includes: A power conversion module externally connected to the mains for converting the mains into a first supply voltage and supplying power to the flow rate proportional valve; An isolated power supply module electrically connected to the power conversion module for converting the first supply voltage into a second supply voltage and supplying power to the flow rate acquisition circuit; A buck circuit electrically connected to the power conversion module for adjusting the first supply voltage to the second supply voltage and supplying power to the drive circuit.

7. The flow control circuit according to claim 6, wherein The power supply circuit further includes: A DCDC circuit, electrically connected to the isolation power supply module, for adjusting the second power supply voltage to a third power supply voltage and supplying power to the follower circuit of the flow rate acquisition circuit; An LDO circuit, electrically connected to the DCDC circuit, for receiving the third power supply voltage and adjusting the third power supply voltage to a fourth power supply voltage, and supplying power to the control module and / or the optocoupler isolation circuit.

8. The flow control circuit according to claim 1, wherein The flow rate acquisition circuit includes: A flow rate sensor, for acquiring the flow rate and outputting the voltage value; A follower circuit, connected to the flow rate sensor, for receiving the voltage value, amplifying the voltage value and then outputting it to the signal input end of the control module.

9. The flow control circuit according to claim 8, wherein, The follower circuit includes an operational amplifier; The signal output end of the flow rate sensor is connected to the signal input end of the operational amplifier, and the output end of the operational amplifier is connected to the flow rate signal input end of the control module.

10. A pneumoperitoneum machine, characterized in that, It includes a pneumoperitoneum machine body and the flow rate control circuit according to any one of claims 1-9, and controls the pneumoperitoneum machine body to supply gas to the surgical process based on this flow rate control circuit.

Images