Semi-closed single-stage screw compressor and working method thereof

Abstract

The invention relates to a semi-closed single-stage screw compressor and a working method thereof. The semi-closed single-stage screw compressor is characterized in that the semi-closed single-stage screw compressor comprises a motor shell, a rotor shell, a motor arranged in the motor shell, and female and male rotors arranged in the rotor shell; the motor comprises a motor stator, a motor rotor and a motor spindle, the motor stator is positioned and fixed in the motor shell through a positioning screw and a shell key, the motor rotor is arranged in the motor stator, the motor spindle and the motor rotor are fixed in an interference fit mode, the motor spindle is coaxially connected with a male rotor in the rotor shell through a coupler, and the male rotor is arranged in the rotor shell. A pair of rolling bearings are installed at the two ends of the motor spindle for supporting, and a cover plate is installed on the rolling bearing side to prevent lubricating oil from splashing to the motor side; according to the compressor mechanism, the problem of shaft seal leakage of a traditional open-type screw compressor is solved; and the problems of overlong shafts and overlarge shaft deflection caused by coaxial design due to the limitation of structures and layouts of part of compressors are avoided.

Description

Technical Field

[0001] This invention relates to the field of screw compressor technology, and more particularly to a semi-hermetic single-stage screw compressor. Background Technology

[0002] A screw compressor is a high-efficiency rotary positive displacement compressor, mainly composed of a pair of precision meshing male and female rotors, a housing, an inlet, an outlet, bearings, and a lubrication and cooling system. Its working principle is that the rotation of the rotor causes the volume of the meshing tooth grooves to gradually decrease from the intake end to the exhaust end, thereby continuously drawing in, compressing, and discharging gas.

[0003] In open-type screw compressors, the motor is separate from the compressor, and a mechanical seal, or shaft seal, is required on the compressor shaft extension. Refrigerant and lubricating oil leakage can easily occur at the shaft seal, leading to a decrease in system efficiency and an increase in maintenance costs.

[0004] Leakage problems become particularly noticeable after long-term operation, requiring regular replacement of the shaft seal; otherwise, it may affect the stable operation of the compressor. Currently, most semi-hermetic single-stage screw compressors have a coaxial design for the drive shaft and motor shaft, i.e., a single shaft design. However, due to structural and layout limitations, some compressors may require an excessively long shaft or excessive shaft deflection if a coaxial design is adopted, which is not conducive to the stable operation of the compressor.

[0005] In addition, existing screw compressors have the following problems: 1. Fixed internal volume ratio (Vi), which easily leads to over-compression or under-compression; the discharge port size of traditional semi-hermetic screw compressors is fixed and cannot be adjusted according to operating conditions, resulting in over-compression (discharge pressure higher than system requirements) or under-compression (discharge pressure insufficient) under certain loads, reducing energy efficiency. 2. Low partial load efficiency; energy efficiency drops significantly when operating at low loads, and adaptability to varying operating conditions is poor. Summary of the Invention

[0006] To address the aforementioned problems in the prior art, this invention provides a semi-hermetic single-stage screw compressor and its operating method. This compressor mechanism avoids the shaft seal leakage problem of traditional open screw compressors; it also avoids the problems of excessively long shafts and excessive shaft deflection caused by the coaxial design of some compressors due to structural and layout limitations.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: This invention relates to a semi-hermetic single-stage screw compressor, characterized in that it comprises a motor housing, a rotor housing, a motor disposed within the motor housing, and male and female rotors disposed within the rotor housing; the motor includes a motor stator, a motor rotor, and a motor main shaft; the motor stator is fixedly positioned within the motor housing by positioning screws and a housing key; the motor rotor is disposed within the motor stator; the motor main shaft is fixed to the motor rotor by an interference fit; the motor main shaft is coaxially connected to the male rotor in the rotor housing by a coupling; a pair of rolling bearings are installed at both ends of the motor main shaft for support; and a cover plate is installed on the rolling bearing side to prevent lubricating oil from splashing onto the motor side.

[0008] Preferably, an internal volume ratio adjustment mechanism is installed inside the rotor housing below the male and female rotors. The internal volume ratio adjustment mechanism includes a Vi threaded rod, a Vi transmission rod, and a Vi slide valve for changing the size of the radial exhaust port. The Vi threaded rod is installed on the internal volume ratio adjustment cavity. The Vi transmission rod is threaded to the outer periphery of the Vi threaded rod to form a screw and nut mechanism. The Vi slide valve is fixedly connected to the Vi transmission rod. When the Vi threaded rod is rotated, it drives the Vi transmission rod to move the Vi slide valve axially along the Vi threaded rod.

[0009] Preferably, a capacity adjustment mechanism is installed inside the rotor housing below the male and female rotors. The capacity adjustment mechanism includes the Vi slide valve, a capacity slide valve, a capacity piston, a capacity adjustment rod, and a compression spring. The capacity piston is fixedly installed on the first end of the capacity adjustment rod, and the second end of the capacity adjustment rod is fixedly connected to the capacity slide valve. A capacity cylinder end cover is fixedly installed on the rotor housing. The capacity adjustment rod is slidably connected to the opening in the middle of the capacity cylinder end cover. The intake end cover, the capacity piston, and the capacity cylinder end cover installed on the rotor housing form a first control chamber and a second control chamber. The Vi slide valve is slidably assembled on the capacity adjustment rod. A spring is sleeved on the capacity adjustment rod between the Vi slide valve and the inner cavity of the capacity slide valve. The first control chamber and the second control chamber are alternately connected to the low-pressure chamber and the high-pressure oil circuit of the compressor, respectively.

[0010] Preferably, an air inlet is provided on the rotor housing and an exhaust outlet is provided on the exhaust housing.

[0011] Preferably, the motor stator is fixed in the motor housing by positioning screws and housing keys.

[0012] Preferably, the Vi protection cap is threaded onto the air intake end cap to protect the internal Vi adjustment structure.

[0013] Preferably, the Vi threaded rod is installed on the internal volume ratio adjustment cavity, and a sealing ring and a bearing are provided on the Vi threaded rod. The bearing is used to support the rotation of the Vi threaded rod, and the sealing ring is used for sealing.

[0014] Preferably, the Vi transmission rod has a threaded sleeve that is threadedly connected to the threaded section of the Vi threaded rod. The Vi slide valve is in the shape of a stepped bushing and is arranged parallel to the Vi threaded rod. The upper part of the Vi transmission rod is sleeved on one side of the Vi slide valve and locked and fixed with a first locking nut.

[0015] Preferably, a capacity displacement sensor is installed on the air intake end cover. The extension rod of the capacity displacement sensor is in contact with the capacity adjustment rod so that the extension rod of the capacity displacement sensor is driven to slide when the capacity adjustment rod moves, thereby changing the value of the capacity displacement sensor.

[0016] A method for operating a semi-hermetic single-stage screw compressor, characterized in that: When it is necessary to manually adjust the internal volume ratio, rotate the Vi threaded rod, and then use the Vi transmission rod to drive the Vi slide valve to move along the axis of the Vi threaded rod, thereby changing the size of the exhaust port radially, and thus adjusting the internal volume ratio. Capacity regulation is achieved by adjusting the compressor's discharge volume. This is done by changing the relative positions of the Vi and capacity valves, thereby altering the rotor's effective working length and thus the compressor's discharge volume and output power. During loading, high-pressure oil is injected into the second control chamber, while the first control chamber connects to the compressor's low-pressure chamber, discharging the lubricating oil within. Due to the pressure difference between the second and first control chambers on the cylinder body, the capacity piston moves away from the Vi valve, causing the capacity valve to move closer to the Vi valve. This gradually increases the rotor's effective working length and the compressor's discharge volume. When the capacity valve... When the piston is in contact with the Vi slide valve end face, the compressor's discharge volume and output power reach their maximum, and the compressor operates at full load. When the load is reduced, high-pressure oil is injected into the first control chamber, and the second control chamber is connected to the compressor's low-pressure chamber to discharge the lubricating oil in the second control chamber. Due to the pressure difference on both sides of the piston, the capacity piston moves towards the Vi slide valve end, causing the capacity slide valve to move away from the Vi slide valve. As a result, the effective working length of the rotor gradually decreases, and the compressor's discharge volume gradually decreases. When the piston is in contact with the capacity cylinder end cover, the compressor's discharge volume reaches its minimum. At this time, the compressor's discharge volume and output power are at their minimum, and the compressor load is at its lowest.

[0017] The beneficial effects of this invention are: the semi-hermetic screw compressor avoids the shaft seal leakage problem of traditional open screw compressors; it avoids the problem of excessive shaft length and excessive shaft deflection caused by the coaxial design of some compressors due to structural and layout limitations; and it can effectively adjust the internal volume ratio and capacity to ensure that the compressor operates at high energy efficiency. Attached image description: Figure 1 This is the front cross-sectional view of the present invention (i.e.) Figure 3 (AA cross-section view); Figure 2This is a cross-sectional view of the product ratio adjustment mechanism of the present invention (i.e., Figure 3 (BB cross-section view); Figure 3 This is a cross-sectional view of the capacity adjustment mechanism of the present invention; Figure 4 This is a schematic diagram showing the connection between the first control chamber, the second control chamber, and the compressor's low-pressure chamber and high-pressure oil circuit. Figure 5 This is a schematic diagram of the effective working length (Vi slide valve and capacity slide valve are not fitted together); Figure 6 This is a schematic diagram of the effective working length (Vi slide valve and capacity slide valve are fitted together).

[0018] Figure 7 This is a partial perspective view of the present invention; Figure 8 yes Figure 7 The main view; Figure 9 yes Figure 7 The left view. Detailed implementation method: The semi-hermetic single-stage screw compressor structure of this invention mainly includes a motor end cover 1, a motor housing 2, an exhaust housing 3, a rotor housing 4, an intake end cover 5, a motor 6, male and female rotors, an internal volume ratio adjustment structure A, and a capacity adjustment mechanism B.

[0019] The motor includes a motor stator 601, a motor rotor 602, and a motor main shaft 603. An air inlet 401 is provided on the rotor housing 4, and an exhaust outlet 301 is provided on the exhaust housing 3.

[0020] The motor 6 is installed inside the motor housing 2, and the motor stator 601 is fixed inside the motor housing 2 by positioning screws 201 and housing key 202. The motor and compressor are integrated into one design, which eliminates the need for shaft seals and avoids the risk of medium leakage from the shaft seals. This fundamentally solves the leakage problem of shaft seals in traditional open screw compressors.

[0021] The traditional single shaft is replaced with two shafts (motor main shaft 603 and motor rotor 602). The motor rotor and motor main shaft are interference-fitted. A pair of rolling bearings 604 are installed on the motor main shaft 603 for support. A cover plate 605 is used to block the lubricating oil on the bearing side to prevent the lubricating oil from splashing to the motor side. In this embodiment, the male rotor is used as the drive shaft. The motor main shaft 603 and the male rotor 7 are connected by a coupling 8 to drive the meshing male rotor 7 and female rotor 9 to rotate. The connection method of using a coupling compensates for the unavoidable angular deviation and radial deviation between the two shafts (motor main shaft and male rotor 7) and absorbs impact loads to reduce vibration.

[0022] The internal volume ratio adjustment mechanism A is located inside the intake end cover 5 and the rotor housing 4, and is positioned below the male and female rotors. The internal volume ratio adjustment mechanism A mainly includes a Vi protective cover A1, a Vi threaded rod A2, a sealing ring A3, a bearing A4, a Vi transmission rod A5, a first locking nut A6, and a Vi slide valve A7 (the Vi slide valve A7 is radially positioned on the exhaust port; the radial movement of the Vi slide valve A7 adjusts the size of the exhaust port). The Vi protective cover A1 is threaded onto the intake end cover 5 to protect the internal Vi adjustment structure (internal volume ratio adjustment mechanism A). The Vi threaded rod A2 is installed at the internal volume ratio adjustment chamber and has a sealing ring A3 and a bearing A4 (specifically...) on it. Bearing A4 is used to support the rotation of Vi threaded rod A2, and sealing ring A3 is used for sealing); Vi transmission rod A5 (lower part) has a threaded sleeve, which is threadedly connected to the threaded section of Vi threaded rod. Vi slide valve A7 is in the shape of a stepped bushing and is set parallel to Vi threaded rod A2. The upper part of Vi transmission rod A5 is sleeved on one side of Vi slide valve A7 and locked and fixed with first locking nut A6; when it is necessary to manually adjust the internal volume ratio, first remove Vi protective cover A1, then rotate Vi threaded rod A2 to drive Vi transmission rod A5 to move axially, that is, simultaneously drive Vi slide valve A7 to move axially along Vi threaded rod, thereby radially changing the size of exhaust port, and thus adjusting the internal volume ratio.

[0023] The capacity adjustment mechanism B is located between the intake end cover 5 and the rotor housing 4, and below the male and female rotors. The capacity adjustment mechanism B includes a capacity displacement sensor (not shown in the figure), the Vi slide valve A7 (the same as the one in the internal volume ratio adjustment mechanism A), a capacity slide valve B2, a capacity piston B1, a capacity cylinder end cover B3, a capacity adjustment rod B4, a spring B5, an internal hexagonal socket head cap screw B6, and a capacity rod washer B7. The capacity displacement sensor is mounted on the intake end cover 5, and its extension rod contacts and engages with the capacity adjustment rod B4. When the capacity adjustment rod B4 moves, it drives the extension rod of the capacity displacement sensor to slide, thus changing the value indicated by the capacity displacement sensor. The capacity piston B1 is locked onto the first end of the capacity adjustment rod B4 by a locking nut. The capacity cylinder end cover B3 is locked to the housing with screws. The cylinder end cover B3 has an opening in the middle for sliding connection of the capacity adjustment rod B4; the intake end cover 5, the capacity piston, and the capacity cylinder end cover B3 together form the first control chamber B8 and the second control chamber B9 (the first control chamber B8 and the second control chamber B9 are located on both sides of the capacity piston B1); the Vi slide valve A7 is slidably fitted on the capacity adjustment rod B4, and the capacity slide valve B2 is installed on the second end of the capacity adjustment rod B4 (i.e., a hexagonal socket head cap screw B6 is screwed into the threaded hole at the second end of the capacity adjustment rod, and a capacity rod washer B7 is provided between the second end of the capacity adjustment rod B4 and the hexagonal socket head cap screw B6). The side of the Vi slide valve A7 opposite to the capacity slide valve B2 has an inner cavity for accommodating a spring B5 (compression spring), which is fitted on the capacity adjustment rod B4 and drives the Vi slide valve A7 and the capacity slide valve B2 to tend to move away from each other.

[0024] The first control chamber B8 and the second control chamber B9 are alternately connected to the low-pressure chamber B10 and the high-pressure oil circuit B11 of the compressor, respectively. Their alternate connection can be achieved by two sets of three-way solenoid valves. That is, the high-pressure oil circuit is connected to the inlet of the first control chamber and the second control chamber through the first set of three-way solenoid valves T1, and the outlet of the first control chamber and the second control chamber is connected to the low-pressure chamber of the compressor through the second set of three-way solenoid valves T2.

[0025] Capacity regulation is achieved by adjusting the compressor's discharge volume. This is done by changing the relative positions of Vi valve A7 and capacity valve B2, thereby altering the effective working length of the rotor and ultimately the compressor's discharge volume and output power. (After Vi valve A7 is fixed, capacity valve B2 moves axially. When Vi valve A7 and capacity valve B2 are not in contact, such as...) Figure 5 As shown, this is a partial load condition. A return orifice in the middle reduces the intake and exhaust of gas, thus reducing the effective working length. The effective working length is the axial distance between the upper surface of the capacity slide valve and the rotor. When the Vi slide valve and the capacity slide valve are in close contact, as... Figure 6As shown, this is the fully loaded state, and the effective working length is the axial distance between the upper surface of the capacity slide valve and the rotor, plus the axial length between the upper surface of the Vi slide valve and the rotor. During loading, high-pressure oil is injected into the second control chamber, and the first control chamber is connected to the low-pressure chamber of the compressor to discharge the lubricating oil. Due to the pressure difference between the second and first control chambers on the cylinder body, the capacity piston B1 moves away from the Vi slide valve, causing the capacity slide valve to move closer to the Vi slide valve. Therefore, the effective working length of the rotor gradually increases, and the compressor's discharge volume gradually increases. When the end faces of the capacity slide valve and the Vi slide valve are in contact, the compressor's discharge volume and output... When the power reaches its maximum, the compressor operates at full load. During load reduction, high-pressure oil is injected into the first control chamber, and the second control chamber is connected to the low-pressure chamber of the compressor to discharge the lubricating oil in the second control chamber. Due to the pressure difference on both sides of the piston, the capacity piston B1 moves towards the Vi slide valve end, causing the capacity slide valve to move away from the Vi slide valve. As a result, the effective working length of the rotor gradually decreases, and the compressor's discharge volume gradually decreases. When the piston is pressed against the end cover of the capacity cylinder, the compressor's discharge volume reaches its minimum. At this time, the compressor's discharge volume and output power are at their minimum, and the compressor load is at its lowest. In addition, the change in the piston's movement position can be observed through a capacity displacement sensor to achieve precise energy-adjustable control.

[0026] The beneficial effects of this invention are: the semi-hermetic screw compressor avoids the shaft seal leakage problem of traditional open screw compressors; it avoids the problem of excessive shaft length and excessive shaft deflection caused by the coaxial design of some compressors due to structural and layout limitations; and it can effectively adjust the internal volume ratio and capacity to ensure that the compressor operates at high energy efficiency.

Claims

1. A semi-hermetic single-stage screw compressor, characterized in that: The device includes a motor housing, a rotor housing, and a motor housed within the motor housing, as well as male and female rotors housed within the rotor housing. The motor includes a motor stator, a motor rotor, and a motor main shaft. The motor stator is fixed within the motor housing, the motor rotor is housed within the motor stator, and the motor main shaft is fixed to the motor rotor with an interference fit. The motor main shaft is coaxially connected to the male rotor in the rotor housing by a coupling. A pair of rolling bearings are installed at both ends of the motor main shaft for support, and cover plates are installed on the rolling bearing side to prevent lubricating oil from splashing onto the motor side.

2. The semi-hermetic single-stage screw compressor according to claim 1, characterized in that: The internal volume ratio adjustment mechanism is installed inside the rotor housing below the male and female rotors. The internal volume ratio adjustment mechanism includes a Vi threaded rod, a Vi transmission rod, and a Vi slide valve for changing the size of the radial exhaust port. The Vi threaded rod is installed on the internal volume ratio adjustment chamber. The Vi transmission rod is threaded to the outer periphery of the Vi threaded rod to form a screw and nut mechanism. The Vi slide valve is fixedly connected to the Vi transmission rod. When the Vi threaded rod is rotated, it drives the Vi transmission rod to move the Vi slide valve axially along the Vi threaded rod.

3. The semi-hermetic single-stage screw compressor according to claim 2, characterized in that: A capacity adjustment mechanism is installed inside the rotor housing below the male and female rotors. The capacity adjustment mechanism includes the Vi slide valve, a capacity slide valve, a capacity piston, a capacity adjustment rod, and a compression spring. The capacity piston is fixedly installed on the first end of the capacity adjustment rod, and the second end of the capacity adjustment rod is fixedly connected to the capacity slide valve. A capacity cylinder end cover is fixedly installed on the rotor housing. The capacity adjustment rod is slidably connected to the opening in the middle of the capacity cylinder end cover. The air inlet end cover, the capacity piston, and the capacity cylinder end cover installed on the rotor housing form a first control chamber and a second control chamber. The Vi slide valve is slidably assembled on the capacity adjustment rod. A spring is sleeved on the capacity adjustment rod between the Vi slide valve and the inner cavity of the capacity slide valve. The first control chamber and the second control chamber are alternately connected to the low-pressure chamber and the high-pressure oil circuit of the compressor, respectively.

4. The semi-hermetic single-stage screw compressor according to claim 3, characterized in that: The alternating connection between the first control chamber, the second control chamber, the compressor low-pressure chamber, and the high-pressure oil circuit is achieved by two sets of three-way solenoid valves. Specifically, the high-pressure oil circuit is connected to the inlet of the first control chamber and the second control chamber respectively through the first set of three-way solenoid valves, and the outlet of the first control chamber and the second control chamber is connected to the compressor low-pressure chamber through the second set of three-way solenoid valves.

5. The semi-hermetic single-stage screw compressor according to claim 1, characterized in that: The motor stator is fixed in the motor housing by positioning screws and housing keys.

6. The semi-hermetic single-stage screw compressor according to claim 2, characterized in that: The Vi protective cap is threaded onto the air intake end cap and is used to protect the internal Vi adjustment structure.

7. The semi-hermetic single-stage screw compressor according to claim 2, characterized in that: The Vi threaded rod is installed on the internal volume ratio adjustment cavity, and a sealing ring and a bearing are provided on the Vi threaded rod. The bearing is used to support the rotation of the Vi threaded rod, and the sealing ring is used for sealing.

8. The semi-hermetic single-stage screw compressor according to claim 7, characterized in that: The Vi transmission rod has a threaded sleeve, which is threadedly connected to the threaded section of the Vi threaded rod. The Vi slide valve is in the shape of a stepped bushing and is arranged parallel to the Vi threaded rod. The upper part of the Vi transmission rod is sleeved on one side of the Vi slide valve and locked and fixed with a first locking nut.

9. The semi-hermetic single-stage screw compressor according to claim 8, characterized in that: A capacity displacement sensor is installed on the air intake end cover. The extension rod of the capacity displacement sensor is in contact with the capacity adjustment rod so that the extension rod of the capacity displacement sensor slides when the capacity adjustment rod moves, thereby changing the value of the capacity displacement sensor.

10. A method for operating a semi-hermetic single-stage screw compressor as described in claim 9, characterized in that: When it is necessary to manually adjust the internal volume ratio, rotate the Vi threaded rod, and then use the Vi transmission rod to drive the Vi slide valve to move along the axis of the Vi threaded rod, thereby changing the size of the exhaust port radially and adjusting the internal volume ratio. Capacity regulation is achieved by adjusting the compressor's discharge volume. This is done by changing the relative positions of the Vi and capacity valves, thereby altering the rotor's effective working length and thus the compressor's discharge volume and output power. During loading, high-pressure oil is injected into the second control chamber, while the first control chamber connects to the compressor's low-pressure chamber, discharging the lubricating oil within. Due to the pressure difference between the second and first control chambers on the cylinder body, the capacity piston moves away from the Vi valve, causing the capacity valve to move closer to the Vi valve. This gradually increases the rotor's effective working length and the compressor's discharge volume. When the capacity valve... When the piston is in contact with the Vi slide valve end face, the compressor's discharge volume and output power reach their maximum, and the compressor operates at full load. When the load is reduced, high-pressure oil is injected into the first control chamber, and the second control chamber is connected to the compressor's low-pressure chamber to discharge the lubricating oil in the second control chamber. Due to the pressure difference on both sides of the piston, the capacity piston moves towards the Vi slide valve end, causing the capacity slide valve to move away from the Vi slide valve. As a result, the effective working length of the rotor gradually decreases, and the compressor's discharge volume gradually decreases. When the piston is in contact with the capacity cylinder end cover, the compressor's discharge volume reaches its minimum. At this time, the compressor's discharge volume and output power are at their minimum, and the compressor load is at its lowest.

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