A method for judging motor forward and reverse rotation faults of a single-machine two-stage screw compressor

Abstract

The present application relates to the related field of compressor, especially to a kind of single machine two-stage screw compressor motor forward and reverse fault determination method.The determination method is judged using compressor unit system, and the system includes compressor, controller and frequency converter;S1, first pressure sensor, second pressure sensor and third pressure sensor are respectively installed on the three pressure measuring points of compressor, and each pressure data is transmitted to controller;The pressure value of first pressure sensor is A, the pressure value of second pressure sensor is B and the pressure value of third pressure sensor is C;S2, controller judges and processes the pressure data input A / B / C;S3, when the result detects that high-pressure stage motor and / or low-pressure stage motor reverses, controller sends signal alarm, and makes frequency converter stop to protect compressor.By collecting the pressure of each part of compressor, whether the compressor is running in forward direction is judged;When the compressor runs in reverse direction, timely alarm is sent out.

Description

Technical Field

[0001] This invention relates to the field of compressors, and more particularly to a method for determining forward and reverse rotation faults in a single-unit two-stage screw compressor motor. Background Technology

[0002] A single-unit two-stage screw compressor contains two motors: a low-pressure stage and a high-pressure stage. Through its unique two-stage design and intercooling mechanism, it achieves highly efficient gas compression and energy utilization, making it particularly suitable for industrial applications with stringent requirements for compressed gas quality and efficiency. Currently, commonly used compressors lack feedback devices such as encoders and rotary transformers in their motors. Therefore, the compressor's rotation direction and actual speed cannot be immediately determined during operation. Furthermore, reversing the compressor's rotation can cause severe damage. Summary of the Invention

[0003] To address the aforementioned technical problems, the present invention aims to provide a method for determining the forward and reverse rotation faults of a single-unit two-stage screw compressor motor. This method involves collecting pressure data from various parts of the compressor to determine whether it is running in the forward direction; and issuing an alarm promptly when the compressor is running in the reverse direction.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A method for diagnosing forward and reverse rotation faults in a single-unit two-stage screw compressor motor. This method uses a compressor unit system for diagnosis, which includes a compressor, a controller, and a frequency converter. The compressor comprises a high-pressure stage compression mechanism, an intermediate-pressure control mechanism, and a low-pressure stage compression mechanism, arranged sequentially and integrally. The high-pressure stage compression mechanism is equipped with a high-pressure stage motor and an exhaust pressure measuring point. The intermediate-pressure control mechanism is equipped with an interstage pressure measuring point. The low-pressure stage compression mechanism is equipped with a low-pressure stage motor and an intake pressure measuring point. The method includes the following steps:

[0006] S1. Install a first pressure sensor, a second pressure sensor, and a third pressure sensor on the exhaust pressure measuring point, the interstage pressure measuring point, and the intake pressure measuring point, respectively, and transmit each pressure data to the controller; wherein, the pressure value of the first pressure sensor is A, the pressure value of the second pressure sensor is B, and the pressure value of the third pressure sensor is C.

[0007] S2. The controller judges the pressure data input A / B / C and processes it itself or sends the result to the frequency converter for processing.

[0008] S3. When the results detect that the high-voltage motor and / or low-voltage motor are reversing, the controller sends an alarm signal and stops the inverter to protect the compressor.

[0009] Preferably, the controller determines two modes:

[0010] A. Jogging mode, suitable for the compressor not yet running. By separately jogging the low-pressure stage compression mechanism and the high-pressure stage compression mechanism, the forward and reverse rotation conditions of the high-pressure stage motor and the low-pressure stage motor are judged.

[0011] B. Running mode, when the compressor is running, judge the forward and reverse rotation conditions of the high-pressure stage motor and the low-pressure stage motor.

[0012] Preferably, the jogging mode:

[0013] a) The controller records the current data and controls the frequency converter to drive the low-pressure stage motor at a low speed. Record the values of the three pressure measurement points A / B / C every 1 second. After 5 seconds, stop the operation of the low-pressure stage motor. Analyze the pressure measurement point data. If the pressure at point C continuously decreases and the pressure at point B continuously increases, the low-pressure stage motor rotates forward; if the pressure at point C continuously increases and the pressure at point B continuously decreases, the low-pressure stage motor rotates in reverse.

[0014] b) After waiting for the pressure value to recover, control the frequency converter to drive the high-pressure stage motor at a low speed. Record the values of the three pressure measurement points A / B / C every 1 second. After 5 seconds, stop the motor operation. Analyze the pressure measurement point data. If the pressure at point A continuously increases and the pressure at point B continuously decreases, the high-pressure stage motor rotates forward; if the pressure at point A continuously decreases and the pressure at point B continuously increases, the high-pressure stage motor rotates in reverse.

[0015] Preferably, the running mode:

[0016] a) During the operation of the compressor, monitor the pressure value. Similarly, record the values of the three pressure measurement points A / B / C every 1 second. During normal operation, A1 (current exhaust pressure) > A (exhaust pressure before operation); C1 (current suction pressure) < C (suction pressure before operation); B1 (current inter-stage pressure) is between A1 and C1, that is: C1 < B1 < A1;

[0017] b) After the unit starts running, if the pressure value is not within the normal range (C1 < B1 < A1), further judgment is made:

[0018] If the value of B1 drops rapidly, and at this time B1 < A1, B1 < C1, and the duration is greater than the set threshold, it is judged that the low-pressure stage motor rotates in reverse;

[0019] If the value of B1 has no rapid fluctuation, and at this time A1 < B1 < C1, and the duration is greater than the set threshold, it is judged that both the low-pressure stage motor and the high-pressure stage motor rotate in reverse;

[0020] If the value of B1 rises rapidly, and at this time A1 < B1 and C1 < B1, and the duration is greater than the set threshold, it is determined that the high-pressure stage motor rotates in reverse.

[0021] In summary, the advantages of the present invention are as follows:

[0022] The present invention can determine the forward and reverse rotation conditions of the two motors of the compressor through this method without a speed sensor. When the motors rotate forward, the overall structure operates normally; while when one or both motors rotate in reverse, an alarm will be issued, thus effectively avoiding the problem of compressor damage caused by the reverse rotation of the compressor. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a side view of the compressor;

[0024] Figure 2 is a schematic structural diagram of the pressure sensor arranged on the side view of the compressor;

[0025] Figure 3 is a schematic cross-sectional structural diagram inside the compressor;

[0026] Figure 4 is a schematic structural diagram of the connection relationship of the needle valve;

[0027] Reference numerals: 1, compressor; 2, needle valve; 4, high-pressure stage motor; 5, low-pressure stage motor; 11, exhaust pressure measurement point; 12, inter-stage pressure measurement point; 13, suction pressure measurement point; 31, first pressure sensor; 32, second pressure sensor; 33, third pressure sensor. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0029] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present application.

[0030] It should also be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0031] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0032] like Figures 1 to 4 As shown, a single-unit two-stage screw compressor 1 includes a high-pressure stage compression mechanism, a medium-pressure control mechanism, and a low-pressure stage compression mechanism arranged sequentially and integrally. The high-pressure stage compression mechanism is provided with a high-pressure stage motor 4 and an exhaust pressure measuring point 11. The medium-pressure control mechanism is provided with an interstage pressure measuring point 12. The low-pressure stage compression mechanism is provided with a low-pressure stage motor 5 and an intake pressure measuring point 13.

[0033] When compressor 1 is working, refrigerant enters from the low-pressure stage compression mechanism and is compressed by the low-pressure stage compression mechanism. Then, the compressed refrigerant flows to the left and passes through the low-pressure stage motor 5 and the high-pressure stage motor 4 in sequence, cooling the low-pressure stage motor 5 and the high-pressure stage motor 4. After that, the compressed refrigerant serves as the air source for the suction side of the high-pressure stage compression mechanism, enters the high-pressure stage compression mechanism, is compressed by the high-pressure stage compression mechanism, and is discharged from the left end of compressor 1.

[0034] The other settings and internal structure of the compressor 1 are all existing technologies, so this patent will not describe them in detail. For details, please refer to Chinese Utility Model Patent No. CN202222824817.3.

[0035] Because the motor inside the commonly used compressor 1 does not have feedback devices such as encoders and rotary transformers, it cannot know the rotation direction and actual speed immediately when the compressor 1 is running. When the compressor 1 runs in reverse, it will cause serious damage to the compressor 1.

[0036] Therefore, based on the above problems, it is necessary to first determine the forward and reverse rotation of the compressor 1 motor. Thus, this patent proposes a method for determining the forward and reverse rotation fault of a single-unit two-stage screw compressor motor. This method uses the compressor unit system for judgment, which includes compressor 1, controller and frequency converter.

[0037] Pressure sensors are installed at the discharge pressure measuring point 11, interstage pressure measuring point 12, and suction pressure measuring point 13 of compressor 1. The pressure sensors can be connected to the above three pressure measuring points by welding or by other connection methods such as needle valve 2.

[0038] The method includes the following steps:

[0039] S1. Install a first pressure sensor 31, a second pressure sensor 32, and a third pressure sensor 33 on the exhaust pressure measuring point 11, the interstage pressure measuring point 12, and the intake pressure measuring point 13, respectively, and transmit each pressure data to the controller; wherein, the pressure value of the first pressure sensor 31 is A, the pressure value of the second pressure sensor 32 is B, and the pressure value of the third pressure sensor 33 is C.

[0040] S2. The controller judges the pressure data input A / B / C and processes it itself or sends the result to the frequency converter for processing.

[0041] S3. When the result detects that the high-pressure stage motor 4 and / or the low-pressure stage motor 5 are reversing, the controller sends an alarm signal and stops the frequency converter to protect the compressor 1.

[0042] The controller described above has two decision modes:

[0043] A. Jogging mode, suitable for compressor 1 not yet running, by jogging the low-pressure stage compression mechanism and the high-pressure stage compression mechanism separately to determine the forward and reverse rotation of the high-pressure stage motor 4 and the low-pressure stage motor 5;

[0044] B. Operating mode: When compressor 1 is running, the forward and reverse rotation of high-pressure stage motor 4 and low-pressure stage motor 5 is determined.

[0045] The jog mode is specifically divided into two cases, a and b, as follows:

[0046] a) The controller records the current data and controls the frequency converter to drive the low-pressure stage motor 5 at a low speed. Every second, it records the values ​​of the three pressure measurement points A / B / C. After 5 seconds, it stops the low-pressure stage motor 5 and analyzes the pressure measurement point data. If the pressure at point C continues to decrease and the pressure at point B continues to increase, the low-pressure stage motor 5 rotates in the forward direction; if the pressure at point C continues to increase and the pressure at point B continues to decrease, the low-pressure stage motor 5 rotates in the reverse direction.

[0047] b) After the pressure value recovers, control the frequency converter to drive the high-pressure stage motor 4 at a low speed. Record the values ​​of the three pressure measurement points A / B / C every second. After 5 seconds, stop the motor and analyze the pressure measurement point data. If the pressure at point A continues to increase and the pressure at point B continues to decrease, then the high-pressure stage motor 4 rotates in the forward direction; if the pressure at point A continues to decrease and the pressure at point B continues to increase, then the high-pressure stage motor 4 rotates in the reverse direction.

[0048] The operating mode is specifically divided into two cases, a and b:

[0049] a) During the operation of the compressor 1, the pressure value is monitored. Similarly, the values of the three pressure measurement points A / B / C are recorded every 1 second. During normal operation, A1 (current exhaust pressure) > A (exhaust pressure before operation); C1 (current suction pressure) < C (suction pressure before operation); B1 (current intermediate pressure) is between A1 and C1, that is: C1 < B1 < A1;

[0050] b) After the unit starts running, if the pressure value is not within the normal range (C1 < B1 < A1), then further judgment is made:

[0051] If the value of B1 drops rapidly, and at this time B1 < A1, B1 < C1, and the duration is greater than the set threshold, it is judged that the low-pressure stage motor 5 rotates in reverse;

[0052] If the value of B1 has no rapid fluctuation, and at this time A1 < B1 < C1, and the duration is greater than the set threshold, it is judged that the low-pressure stage motor 5 and the high-pressure stage motor 4 rotate in reverse simultaneously;

[0053] If the value of B1 rises rapidly, and at this time A1 < B1, C1 < B1, and the duration is greater than the set threshold, it is judged that the high-pressure stage motor 4 rotates in reverse.

[0054] By using this method, the forward and reverse rotation conditions of the two motors of the compressor can be judged. When the motors are rotating forward, the overall structure operates normally; while when one or two motors rotate in reverse, an alarm will be issued, thus effectively avoiding the problem of damage to the compressor 1 caused by the reverse rotation of the compressor 1.

[0055] The above is the description of the embodiments of the present invention. Through the above description of the disclosed embodiments, those skilled in the art can implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but will conform to the widest scope consistent with the principles and novel points disclosed herein.

Claims

1. A method for judging the motor reverse rotation fault of a single machine two-stage screw compressor, which adopts a compressor unit system for judgment, the unit system comprising a compressor (1), a controller and a frequency converter; the compressor (1) comprises a high-pressure stage compression mechanism, a medium-pressure control mechanism and a low-pressure stage compression mechanism which are integrally arranged in sequence, a high-pressure stage motor (4) and an exhaust pressure measuring point (11) are arranged on the high-pressure stage compression mechanism, an inter-stage pressure measuring point (12) is arranged on the medium-pressure control mechanism, and a low-pressure stage motor (5) and a suction pressure measuring point (13) are arranged on the low-pressure stage compression mechanism; characterized in that, The method comprises the following steps: S1, first, second and third pressure sensors (31, 32 and 33) are respectively installed at the exhaust pressure measuring point (11), the inter-stage pressure measuring point (12) and the suction pressure measuring point (13), and the pressure data of each pressure sensor is transmitted to a controller; wherein the pressure value of the first pressure sensor (31) is A, the pressure value of the second pressure sensor (32) is B and the pressure value of the third pressure sensor (33) is C; S2, the controller judges the input pressure data A / B / C and processes the data by itself or sends the result to a frequency converter for processing; S3, when the result detects that the high-pressure stage motor (4) and / or the low-pressure stage motor (5) is reversed, the controller sends a signal for alarm and stops the frequency converter to protect the compressor (1); The controller judges in two modes: A. Jog mode, which is suitable for the compressor (1) not running yet, and the high-pressure stage motor (4) and the low-pressure stage motor (5) are jogged separately to judge the forward and reverse rotation of the high-pressure stage motor (4) and the low-pressure stage motor (5); a) the controller records the current data and controls the frequency converter to drive the low-pressure stage motor (5) at a small speed, and records the pressure values of the three pressure measuring points A / B / C every 1 second, and stops the low-pressure stage motor (5) after 5 seconds, and analyzes the pressure measuring point data, if the C-point pressure continuously becomes smaller and the B-point pressure continuously becomes larger, the low-pressure stage motor (5) is forward rotating; if the C-point pressure continuously becomes larger and the B-point pressure continuously becomes smaller, the low-pressure stage motor (5) is reversed; b) after the pressure value is restored, the frequency converter is controlled to drive the high-pressure stage motor (4) at a small speed, and the pressure values of the three pressure measuring points A / B / C are recorded every 1 second, and the motor is stopped after 5 seconds, and the pressure measuring point data is analyzed, if the A-point pressure continuously becomes larger and the B-point pressure continuously becomes smaller, the high-pressure stage motor (4) is forward rotating; if the A-point pressure continuously becomes smaller and the B-point pressure continuously becomes larger, the high-pressure stage motor (4) is reversed; B. Running mode, which is suitable for judging the forward and reverse rotation of the high-pressure stage motor (4) and the low-pressure stage motor (5) when the compressor (1) is running; a) when the compressor (1) is running, the pressure values are monitored, and the pressure values of the three pressure measuring points A / B / C are recorded every 1 second, and when the compressor (1) is running normally, A1 (the current exhaust pressure) > A (the exhaust pressure before running); C1 (the current suction pressure) < C (the suction pressure before running); B1 (the current inter-stage pressure) is between A1 and C1, i.e. C1 < B1 < A1; b) when the unit is running, if the pressure values are not in the normal range (C1 < B1 < A1), the low-pressure stage motor (5) is further judged: if the B1 value rapidly decreases, and at this time B1 < A1, B1 < C1, and the duration is greater than a set threshold, it is judged that the low-pressure stage motor (5) is reversed; if the B1 value does not fluctuate rapidly, and at this time A1 < B1 < C1, and the duration is greater than a set threshold, it is judged that the low-pressure stage motor (5) and the high-pressure stage motor (4) are reversed simultaneously; If the value of B1 rises rapidly and at the same time A1 < B1, C1 < B1, and the duration is greater than a set threshold, it is determined that the high-voltage stage motor (4) is reversed.

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