Two-stage compression high vacuum small dry vacuum pump

Abstract

The application discloses a two-stage compression high-vacuum small dry vacuum pump, comprising a vacuum pump body, two-stage compression cylinders connected in series, engaging male and female rotors rotatably installed in the compression cylinders, and motors for driving the male and female rotors. A multi-transmission frequency converter is simultaneously connected to the motors of the two-stage compression cylinders. An acquisition assembly comprises a first sensor for acquiring actual exhaust pressure in real time and a second sensor for acquiring actual inter-stage pressure in real time. A controller is connected to the transmission frequency converter and the acquisition assembly, and comprises a first sub-control module and a second sub-control module. The application solves the problem that the existing high-vacuum small dry vacuum pump does not perform synchronous control on two-stage compression, and there is a risk of imbalance of inter-stage rotating speed.

Description

Technical Field

[0001] This invention relates to the field of vacuum pump technology, and specifically to a two-stage compression high-vacuum small dry vacuum pump. Background Technology

[0002] Small dry vacuum pumps typically employ multi-stage compression to achieve high efficiency, high vacuum levels, and stable operation, aiming to improve the ultimate vacuum. Because single-stage compression pumps have limited compression ratios, multi-stage cascade compression pumps can increase the final vacuum level. Simultaneously, multi-stage compression pumps match gas flow rates through volumetric variations between stages, avoiding the efficiency losses caused by gas backflow at low pressures in single-stage compression. High compression ratios in single-stage pumps lead to a rapid increase in gas temperature, potentially damaging sealing materials. Multi-stage compression, on the other hand, progressively reduces gas temperature, minimizing thermal stress on the pump body. Compared to single-stage adiabatic compression, this can reduce energy consumption by 20-30%, and also avoids excessive instantaneous power consumption in single-stage motors, extending the lifespan of bearings and transmission components.

[0003] In summary, the core objective of using multi-stage compression in high-vacuum small dry vacuum pumps is to balance vacuum level, efficiency, and reliability. Essentially, it breaks through the physical limits of a single stage through multi-stage compression, while reducing heat load and energy consumption. Under the premise of meeting requirements, the fewer the number of stages, the better, and two-stage compression is usually the most common.

[0004] The electrical system of a high-vacuum miniature dry vacuum pump generally includes a control system, a drive system, and an execution system. The standard controller of the control system integrates control logic and pre-alarm protection measures, monitoring the vacuum pump's operating status in real time to control the drive system and the execution system motors. Currently, the control system for two-stage compression high-vacuum miniature dry vacuum pumps uses a standard controller, the drive system consists of two frequency converters, and the execution system consists of two permanent magnet synchronous motors. While seemingly simple and practical, it has some shortcomings:

[0005] The permanent magnet synchronous motor of the execution system is too large, which makes the vacuum pump, which should be compact, slightly bulky. In addition, the use of the metal material of the motor housing for heat conduction results in low heat dissipation efficiency, which makes it easy to overheat when operating under high load.

[0006] The drive system directly uses two sets of frequency converters, which is simple and convenient, but lacks integration considerations;

[0007] Based on the standard controller for single-stage compression, the control system adds a frequency converter to control the motors of two-stage compression. The two frequency converters also adopt a sequential start-stop control method, which basically meets the working requirements of the whole machine. However, the two-stage compression is not synchronized, which makes the control scheme imperfect and poses a risk of speed imbalance between stages. Summary of the Invention

[0008] To overcome the shortcomings of existing technologies, a two-stage compression high-vacuum small dry vacuum pump is provided to solve the problem that existing high-vacuum small dry vacuum pumps do not have synchronous control of the two compression stages, resulting in the risk of speed imbalance between stages.

[0009] To achieve the above objectives, a two-stage compression high-vacuum miniature dry vacuum pump is provided, comprising:

[0010] The vacuum pump body includes two-stage compression cylinders connected in series, wherein meshing male and female rotors are rotatably mounted inside the compression cylinders, and a motor for driving the male and female rotors is mounted in the compression cylinders;

[0011] A multi-drive frequency converter that is simultaneously connected to a motor in a two-stage compression cylinder;

[0012] The acquisition components include a first sensor for real-time acquisition of actual exhaust pressure and a second sensor for real-time acquisition of actual interstage pressure.

[0013] A controller, connected to the drive inverter and the acquisition component, includes a first sub-control module and a second sub-control module. Based on a first pressure difference between the target exhaust pressure and the actual exhaust pressure, and when the first pressure difference is non-zero, the first sub-control module increases the first shaft frequency of the multi-drive inverter to increase the motor speed of the first-stage compression cylinder driven by the first shaft of the multi-drive inverter, causing the actual exhaust pressure to rise. After the first pressure difference decreases, the first sub-control module decreases the given increase in the first shaft frequency to reduce the increase in the motor speed of the first-stage compression cylinder, thus slowing down the rise in actual exhaust pressure. This process is repeated until the first pressure difference returns to zero. Simultaneously, based on a second pressure difference between the target interstage pressure and the actual interstage pressure, and when the second pressure difference is non-zero, the second sub-control module increases the second shaft frequency of the multi-drive inverter to increase the motor speed of the second-stage compression cylinder driven by the second shaft of the multi-drive inverter, thereby adjusting the actual interstage pressure to assist in returning the first pressure difference to zero.

[0014] Furthermore, the motor is a parallel-shaft dual-rotor motor, wherein the two rotors of the parallel-shaft dual-rotor motor are respectively coaxially arranged with the male and female rotors.

[0015] Furthermore, the motor is attached to a heat sink using thermally conductive adhesive.

[0016] Furthermore, the radiator is an extruded radiator.

[0017] The beneficial effect of the present invention is that the controller of the two-stage compression high vacuum small dry vacuum pump of the present invention adds a sub-module for synchronous control of two-stage compression (first sub-control module and second sub-control module) to synchronously regulate the speed of the two-stage compression cylinders. The speed balance between the two-stage compression is achieved through PID control, so that the two-stage compression high vacuum small dry vacuum pump of the present invention can operate efficiently and stably under high load, and is suitable for high-precision vacuum application scenarios such as laboratories. Attached Figure Description

[0018] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0019] Figure 1 This is a schematic diagram of the structure of a two-stage compression high-vacuum small dry vacuum pump according to an embodiment of the present invention.

[0020] Figure 2 This is a schematic diagram of the structure of the vacuum pump body according to an embodiment of the present invention.

[0021] Figure 3 This is a schematic diagram of the internal structure of the vacuum pump body according to an embodiment of the present invention.

[0022] Figure 4 This is a schematic diagram of the internal structure of the compression cylinder according to an embodiment of the present invention.

[0023] Figure label:

[0024] Vacuum pump body 1, compression cylinder 11, primary compression cylinder 11a, secondary compression cylinder 11b, male and female rotors 12, motor 13, radiator 14;

[0025] Multi-drive frequency converter 2;

[0026] Data acquisition component 3, first sensor 31, second sensor 32;

[0027] Controller 4, first sub-control module 41, second sub-control module 42. Detailed Implementation

[0028] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings.

[0029] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0030] Reference Figures 1 to 4As shown, the present invention provides a two-stage compression high vacuum small dry vacuum pump, comprising: a vacuum pump body 1, a multi-drive frequency converter 2, a data acquisition component 3, and a controller 4.

[0031] See Figure 3 As shown, the vacuum pump body 1 includes two-stage compression cylinders 11. The two-stage compression cylinders 11 are connected in series. Specifically, the two-stage compression cylinders 11 include a primary compression cylinder 11a and a secondary compression cylinder 11b. Air from outside the vacuum pump body is drawn in through the air inlet of the primary compression cylinder, undergoes primary compression in the primary compression cylinder, and then undergoes secondary compression in the secondary compression cylinder to generate compressed air.

[0032] A male and female rotor 12 are rotatably mounted inside a compression cylinder 11. A motor 13 is mounted on the compression cylinder 11. The motor 13 is used to drive the male and female rotors 12.

[0033] The multi-drive frequency converter 2 is simultaneously connected to the motor 13 of the two-stage compression cylinder 11.

[0034] The data acquisition component 3 includes a first sensor 31 and a second sensor 32. The first sensor 31 is used to acquire the actual exhaust pressure in real time. The second sensor 32 is used to acquire the actual interstage pressure in real time.

[0035] Controller 4 is connected to the drive inverter and the acquisition component 3.

[0036] The controller 4 includes a first sub-control module 41 and a second sub-control module 42.

[0037] After acquiring the actual exhaust pressure and the actual interstage pressure, the first sub-control module 41 and the second sub-control module 42 of the controller, based on the first pressure difference between the target exhaust pressure and the actual exhaust pressure and when the first pressure difference is non-zero, increase the first shaft frequency of the multi-drive inverter 2 to increase the speed of the motor 13 of the first-stage compression cylinder 11a driven by the first shaft of the multi-drive inverter 2, thereby increasing the actual exhaust pressure. After the first pressure difference decreases, the first sub-control module decreases the first shaft frequency by a larger margin to reduce the increase in the speed of the motor 13 of the first-stage compression cylinder 11a, thereby slowing down the increase in the actual exhaust pressure. This cycle repeats until the first pressure difference returns to zero. At the same time, based on the second pressure difference between the target interstage pressure and the actual interstage pressure and when the second pressure difference is non-zero, the second sub-control module 42 increases the second shaft frequency of the multi-drive inverter 2 to increase the speed of the motor 13 of the second-stage compression cylinder 11b driven by the second shaft of the multi-drive inverter 2, thereby adjusting the actual interstage pressure to assist in returning the first pressure difference to zero.

[0038] In this embodiment, the motor 13 is a parallel-shaft dual-rotor motor 13. The two rotors of the parallel-shaft dual-rotor motor 13 are respectively coaxially arranged with the male and female rotors 12.

[0039] In this embodiment, the motor 13 is bonded to the heat sink 14 with thermally conductive adhesive.

[0040] The parallel-shaft dual-rotor motor body and radiator both adopt a modular and detachable design. The dual rotors of the motor are coaxial with the male and female rotors of the vacuum pump body, which reflects the compact structure and improves transmission efficiency. At the same time, the extruded radiator is bonded to the motor stator through thermally conductive potting compound, ensuring that the compact size meets the compact structure of the vacuum pump while effectively reducing the temperature rise of the motor.

[0041] The two-stage compression high-vacuum miniature dry vacuum pump multi-drive frequency converter of the present invention is composed of a set of rectifier modules and a set of dual-shaft inverter modules, and the combination method is more in line with integration.

[0042] The controller of the two-stage compression high-vacuum miniature dry vacuum pump of this invention adds a sub-module for synchronous control of two-stage compression (a first sub-control module and a second sub-control module). The drive system of the two-stage compression high-vacuum miniature dry vacuum pump of this invention uses a multi-drive frequency converter. For frequency converters, they all consist of a rectifier and an inverter. The difference is that the rectifier module and inverter module of a standard frequency converter are fixed and inseparable; while the multi-drive frequency converter is composed of a rectifier module and an inverter module. Furthermore, depending on the number of motors controlled, the inverter module can be divided into a single-axis inverter module and a dual-axis inverter module. The multi-drive frequency converter used in the two-stage compression high-vacuum miniature dry vacuum pump of this invention consists of a rectifier module and a dual-axis inverter module, which receives commands from the controller to operate the execution system. Specifically, the execution system of the two-stage compression high-vacuum miniature dry vacuum pump of this invention is a parallel-shaft dual-rotor motor. Both the parallel-shaft dual-rotor motor and the heat sink adopt a modular and detachable design. The dual rotors of the parallel-shaft dual-rotor motor are coaxial with the male and female rotors of the vacuum pump body. The extruded heat sink is bonded to the motor using thermally conductive potting compound, ensuring a compact size that meets the requirements of a compact vacuum pump structure while effectively reducing motor temperature rise. This invention's two-stage compression high-vacuum miniature dry vacuum pump operates efficiently and stably under high loads, making it suitable for high-precision vacuum applications such as those in laboratories.

[0043] The controller of the two-stage compression high-vacuum miniature dry vacuum pump of this invention adopts PID (Proportional-Integral-Derivative) control. PID control is a classic automatic control algorithm that uses a combination of proportional (P), integral (I), and derivative (D) operations to adjust the control quantity in real time according to the system error, so as to enable the controlled object to quickly, accurately, and smoothly track the target value.

[0044] The real-time monitored exhaust pressure is the actual exhaust pressure, and the exhaust pressure set by the user is the target exhaust pressure. The pressure difference between the two (the first pressure difference) is used as the input of the first sub-control module. The adjustment control quantity of the first sub-control module is used as the first shaft frequency of the dual-axis inverter module to adjust the speed of the motor driven by the first shaft in real time, thereby adjusting the exhaust pressure.

[0045] When the first differential pressure is non-zero, the first shaft frequency setting will be increased, which will increase the speed of the motor driven by the first shaft and thus increase the exhaust pressure. After the first differential pressure decreases, the increase in the first shaft frequency setting will be reduced, which will decrease the increase in the speed of the motor driven by the first shaft and thus slow down the increase in exhaust pressure. The first differential pressure will then decrease further. This cycle repeats until the first differential pressure input is zero.

[0046] The interstage pressure monitored in real time is the actual interstage pressure, and the theoretical interstage pressure is the target interstage pressure. The pressure difference between the two (the second pressure difference) is used as the input of the second sub-control module. The adjustment control quantity of the second sub-control module is used as the second axis frequency of the dual-axis inverter module to adjust the speed of the motor driven by the second axis in real time, thereby adjusting the interstage pressure. Finally, the first pressure difference input is reduced to zero, thus achieving speed balance between the two compression stages.

[0047] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the inventive concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. A two-stage compression high-vacuum small dry vacuum pump, characterized in that, include: The vacuum pump body includes two-stage compression cylinders connected in series, wherein meshing male and female rotors are rotatably mounted inside the compression cylinders, and a motor for driving the male and female rotors is mounted in the compression cylinders; A multi-drive frequency converter that is simultaneously connected to a motor in a two-stage compression cylinder; The acquisition components include a first sensor for real-time acquisition of actual exhaust pressure and a second sensor for real-time acquisition of actual interstage pressure. A controller, connected to the drive inverter and the acquisition component, includes a first sub-control module and a second sub-control module. Based on a first pressure difference between the target exhaust pressure and the actual exhaust pressure, and when the first pressure difference is non-zero, the first sub-control module increases the first shaft frequency of the multi-drive inverter to increase the motor speed of the first-stage compression cylinder driven by the first shaft of the multi-drive inverter, causing the actual exhaust pressure to rise. After the first pressure difference decreases, the first sub-control module decreases the given increase in the first shaft frequency to reduce the increase in the motor speed of the first-stage compression cylinder, thus slowing down the rise in actual exhaust pressure. This process is repeated until the first pressure difference returns to zero. Simultaneously, based on a second pressure difference between the target interstage pressure and the actual interstage pressure, and when the second pressure difference is non-zero, the second sub-control module increases the second shaft frequency of the multi-drive inverter to increase the motor speed of the second-stage compression cylinder driven by the second shaft of the multi-drive inverter, thereby adjusting the actual interstage pressure to assist in returning the first pressure difference to zero. The motor is a parallel-shaft dual-rotor motor, and the two rotors of the parallel-shaft dual-rotor motor are respectively coaxially arranged with the male and female rotors; The motor is attached to a heat sink by thermally conductive adhesive. The radiator is an extruded radiator.

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