Compressor protection device

Abstract

The compressor protection device relates to the compressor manufacturing technical field, and particularly relates to a refrigeration compressor protection device with functions of detecting input signals, comparing and judging, and executing output. The detection module comprises a PTC resistance value detection module, a power supply voltage detection module, an oil level sensor capacitance value detection module, and a vibration frequency amplitude detection module; the processing and executing unit comprises a processor, a communication module, an alarm lamp, a relay, and a memory connected with the output end of the processor; the PTC resistance value detection module, the power supply voltage detection module, the oil level sensor capacitance value detection module, and the vibration frequency amplitude detection module transmit detection information to the processor; the processor compares the input information with preset threshold values or curves; when the comparison result of the processor exceeds the preset threshold values, the processor outputs an instruction; the alarm lamp displays a fault category; the relay executes an action; the memory stores fault information and normal operation information; and the communication module transmits the fault information and the normal operation information to an external control system.

Description

Technical Field

[0001] This invention relates to a compressor protection device, specifically to a refrigeration compressor protection device that detects input signals, performs comparisons and judgments, and executes outputs. Background Technology

[0002] Under abnormal conditions such as low-quality power supply (unstable voltage or voltage exceeding ±10% of the rated voltage, phase loss, etc.), overload exceeding the operating range, refrigerant leakage in the refrigeration system leading to poor motor cooling, and lack of lubrication causing mechanical component damage and motor stalling, the motor windings may overheat and burn out. Therefore, protective devices must be installed.

[0003] Small compressors (below 15HP, rotary compressors and small scroll compressors, etc.) typically have Y-type windings in their motors. A temperature and current type protector (bimetallic contact type) is installed at the neutral point to protect the compressor motor windings from overheating. Large compressors (above 20HP, large scroll compressors and screw compressors, etc.) have higher currents, making built-in temperature and current type protectors unsuitable. The industry commonly uses an embedded PTC in the windings combined with an external protection device to protect the compressor windings from overheating.

[0004] Currently, compressor protection measures are all designed to prevent overheating of the motor windings, and only consider copper wire winding motors. There is no special rapid protection for windings with faster temperature rise, such as aluminum wire and copper-clad aluminum wire. Moreover, most compressor failures are due to damage to mechanical components, and the main reason for this is poor lubrication caused by insufficient refrigerant oil, which existing compressor protectors cannot protect against.

[0005] When the compressor power supply phase sequence is incorrect, the motor runs normally (in reverse), but the compressor cannot compress the refrigerant. The abnormal operation of mechanical parts leads to wear and damage. At this time, the motor runs under light load, the winding temperature is low, and the traditional protector will not provide protection.

[0006] When the compressor phase sequence is unbalanced or a phase is missing, if the compressor load is light, the motor can still run. Traditional compressor protectors can only protect the compressor after the motor windings gradually heat up. Especially when the built-in temperature and current type protector or PTC is installed on the power supply phase loss winding, it cannot make a timely judgment and provide protection.

[0007] If the compressor is not properly matched to the refrigeration system or is improperly installed, it may experience abnormal vibrations during certain operating conditions or when the compressor's mechanical components are damaged, leading to refrigerant pipeline breakage. In recent years, low-GWP environmentally friendly refrigerants such as R32, R454B, R454C (slightly flammable refrigerants) and R290 (flammable refrigerant) have been widely adopted. Under such circumstances, fire or explosion may occur, and traditional protectors cannot provide protection.

[0008] In view of the problems existing in the above-mentioned prior art, it is necessary to research and design a new type of compressor protection device to overcome the problems existing in the prior art. Summary of the Invention

[0009] To address the technical problems identified in the prior art, this invention provides a compressor protection device. The invention primarily utilizes a detection unit on the compressor that includes a PTC resistance detection module, a power supply voltage detection module, an oil level sensor capacitance detection module, and a vibration frequency and amplitude detection module. This, combined with a processing and execution unit comprising a processor, a communication module, an alarm light, a relay, and a memory, protects the compressor from overheating of the motor windings, abnormal power supply, insufficient lubrication, and abnormal vibration, thus preventing compressor damage or potential hazards.

[0010] The technical means employed in this invention are as follows:

[0011] A compressor protection device includes: a detection unit, a processing and execution unit;

[0012] Furthermore, the detection module includes: a PTC resistance value detection module, a power supply voltage detection module, an oil level sensor capacitance value detection module, and a vibration frequency and amplitude detection module;

[0013] Furthermore, the processing and execution unit includes: a processor and a communication module, an alarm light, a relay, and a memory connected to the processor output;

[0014] Furthermore, the output terminals of the PTC resistance detection module, power supply voltage detection module, oil level sensor capacitance detection module, and vibration frequency and amplitude detection module are connected to the input terminal of the processor, transmitting the detection information to the processor. The processor processes the input information and compares it with a preset threshold or curve. When the processor's comparison exceeds the preset threshold, it outputs a command, the alarm light displays the fault category, the relay performs an action, the memory stores fault information and normal operation information, and the communication module transmits the fault information and normal operation information to the external control system.

[0015] Furthermore, the PTC resistance value detection module includes: one or more PTCs placed on the windings of the motor stator inside the compressor, and a PTC II fixed to the high and low pressure partition inside the high pressure chamber;

[0016] Furthermore, both PTC1 and PTC2 are connected in series, with a total number not exceeding 9;

[0017] Furthermore, the sum of the resistance values ​​R of PTC1 and PTC2 Σ Greater than the threshold R t When, or the sum of PTC resistance values ​​increases at a rate dR Σ / d tGreater than the threshold value k t When this occurs, it is determined to be a fault.

[0018] Furthermore, the power supply voltage detection module monitors the compressor power supply voltage and detects the three-phase voltage phase. If any abnormality is detected, it is identified as a fault. It continuously detects N three-phase voltage waveforms over M cycles. If, as mentioned above, a certain phase voltage waveform is missing H times out of the N×M waveforms, or the amplitude U of the three-phase voltage waveform is missing... R U S U T One of the phases is related to the average value (U) R +U S +U T The deviation of 10% or more from 1 / 3 occurs cumulatively H times, or the zero-crossing time t of each phase voltage waveform occurs. R t S t T The order of events is compared, and if the cumulative number of abnormal events exceeds the threshold H, it is judged as a fault.

[0019] Furthermore, the oil level sensor capacitance detection module detects the capacitance value of the metal grid sensor placed at the minimum oil level required by the compressor. It checks the capacitance value every time interval t1. If the detected capacitance value is less than the set value C within time T1, the module will detect the value. t If the number of occurrences exceeds G, it is considered a fault.

[0020] Furthermore, the vibration frequency and amplitude detection module is fixedly mounted on the protection device, and the protection device is rigidly connected to the compressor housing, or rigidly connected to the compressor housing through junction box A;

[0021] Furthermore, the vibration frequency and amplitude detection module uses a built-in sensing circuit to detect the compressor's vibration frequency and amplitude every t2 time interval. If the vibration amplitude obtained within T2 time interval is greater than the set value A at the corresponding frequency, the module will detect the vibration frequency and amplitude. t If the number of occurrences exceeds J, it is considered a fault.

[0022] Furthermore, after comparing the fault information detected by any one of the PTC resistance detection module, power supply voltage detection module, oil level sensor capacitance detection module, and vibration frequency and amplitude detection module, the processor outputs the information to the alarm light. The alarm light displays the fault category, the relay activates, and the control contactor cuts off the power supply to the compressor.

[0023] Furthermore, the processor compares the fault or normal operation information detected by any one of the following modules: PTC resistance detection module, power supply voltage detection module, oil level sensor capacitance detection module, and vibration frequency and amplitude detection module. The processor then outputs the information to the communication module, which uploads it to the designated cloud server via a wireless transmission module. The communication module also has a dedicated interface for interacting with other devices.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] 1. The compressor protection device provided by this invention addresses the problem of excessively rapid temperature rise in aluminum wire and copper-clad aluminum wire windings by setting a temperature change rate threshold, which provides rapid protection for copper, aluminum, copper-clad aluminum, and mixed windings of the above three materials, further preventing motor burnout.

[0026] 2. The compressor protection device provided by the present invention integrates the functions of a traditional phase sequence protector and optimizes the fault judgment threshold according to the special operating conditions of the compressor. While realizing the protection function, it avoids the problem of frequent malfunctions of traditional phase sequence protectors.

[0027] 3. The compressor protection device provided by the present invention, by setting a capacitance value detection module and a metal grid sensor set in the compressor, plays a role in protecting the compressor oil level and avoiding compressor failure due to lack of oil.

[0028] 4. The compressor protection device provided by the present invention can identify the abnormal operating state of the compressor by setting up a vibration frequency and amplitude detection module, avoid compressor damage caused by improper installation or use, and detect the fault in the early stage, avoiding the risk of flammable refrigerant leakage due to pipeline breakage.

[0029] 5. The compressor protection device provided by the present invention transmits the compressor's operating status and fault information to a cloud server wirelessly, allowing users and equipment manufacturers to remotely obtain compressor operating status information and predict the possibility of compressor failure.

[0030] In summary, the technical solution of this invention solves the problem that existing compressor protectors or devices only provide overheat protection for the motor and cannot protect against the main failure problem of oil shortage, especially the huge risk of abnormal vibration causing pipeline leakage of flammable refrigerant. Moreover, it can remotely obtain compressor operating status data and predict compressor failures. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a structural block diagram of the present invention;

[0033] Figure 2This is a typical application example of the protection device of the present invention and a circuit diagram of the sensor setup;

[0034] Figure 3 This is a schematic diagram of a typical application structure of the protection device of the present invention;

[0035] Figure 4 The RT characteristic curve of the total resistance of the PTC series circuit inside the compressor of this invention is shown.

[0036] Figure 5 This is a schematic circuit diagram showing the PTC connection inside the compressor of the present invention;

[0037] Figure 6 The three-phase voltage waveform diagram for power supply to the compressor of this invention;

[0038] Figure 7 This is a schematic diagram of the oil level sensor structure installed inside the compressor of the present invention;

[0039] Figure 8 This is a characteristic curve of the oil level sensor CL of the present invention;

[0040] Figure 9 This is a characteristic curve of compressor vibration Af in this invention.

[0041] In the diagram: 1. Scroll compressor 2. Sealed housing 3. Electric motor 4. Electric motor stator 5. Electric motor rotor 6. Crankshaft assembly 7. Scroll compressor assembly 8. Main support assembly 9. Secondary support assembly 10. Junction box A 11. Suction pipe 12. Moving scroll 13. Fixed scroll 14. Sealed compression space 15. Valve plate 16. High pressure chamber 17. High and low pressure partition 18. Exhaust pipe 19. Oil sump 20. Oil suction pipe 21. Oil stirring plate 23. Oil return pipe 24. Winding 25. PTC-1 26. PTC-2 27. Wire-1 28. Wire-2 29. Wire-3 30. PTC terminal 31. Compressor power supply sealing terminal 32. Oil level sensor 33. Protection device 34. Junction box B. Detailed Implementation

[0042] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0043] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0045] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0046] In the description of this invention, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this invention. The directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0047] For ease of description, spatial relative terms such as "above," "over," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation besides the orientation of the device as described in the figures. For example, if the device in the figures is inverted, a device described as "above" or "above" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0048] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0049] like Figure 1 As shown, the present invention provides a compressor protection device.

[0050] It contains four detection modules, which respectively detect the total resistance of the PTC series inside the compressor, the compressor power supply voltage, the capacitance value of the compressor oil level sensor, and the vibration frequency and amplitude of the compressor. The detection data is input into the processing and execution module and compared with the preset threshold or curve. If it exceeds the range, it is judged as a fault.

[0051] like Figure 2 As shown in the typical application circuit, the protected compressor has corresponding sensors pre-installed inside. The PTC and oil level sensors are led out on the compressor housing through sealed terminals and connected to the corresponding output terminals of the protection device. The three-phase power supply for the compressor is directly connected in parallel to the power input terminal of the protection device. The vibration frequency and amplitude detection module is fixedly mounted on the protection device 33. The protection device 33 is rigidly connected to the compressor housing directly or through junction box A10. Vibration can be directly transmitted to the vibration frequency and amplitude detection module through the protection device 33.

[0052] When the processor determines a fault, the alarm light displays the corresponding fault code, the internal relay disconnects, and the two ends of the relay are connected to the contactor's electromagnetic coil through terminals M1 and M2, controlling the contactor to cut off the power supply to the compressor.

[0053] The protection device stores fault information and communicates with other equipment in the unit or computers via RS-485 or USB interface. The wireless transmission module uploads the information to the cloud server.

[0054] like Figure 3 The diagram shows a cross-sectional view of a compressor in an example of the application of the protection device. This example uses a scroll compressor as an example for illustration, but the application of the protection device is not limited to scroll compressors.

[0055] The scroll compressor 1 mainly includes: a sealed housing 2 formed of steel plate; an electric motor 3 installed in the sealed housing 2; a crankshaft assembly 6 for transmitting power; a driven scroll compressor assembly 7; a main support assembly 8 and a secondary support assembly 9 for supporting rotating parts; and a junction box A10 for external wiring and installation of protective devices.

[0056] like Figure 3 As shown, the scroll compressor has a vertical structure, with... Figure 3 Above is the top. Figure 3 The text below is for illustrative purposes only and does not limit the invention to vertical compressors.

[0057] When the scroll compressor is working, the low-temperature, low-pressure refrigerant in the refrigeration system enters the compressor from the compressor suction pipe 11. It passes around the motor stator 4 and motor rotor 5 and is cooled. The motor 3 runs, and the torque generated by the rotation of the rotor 5 is transmitted to the moving scroll 12 through the crankshaft assembly 6. It cooperates with the fixed scroll 13 to form a closed compression space 14. The refrigerant pressure in the closed compression space 14 rises to the threshold value, the valve plate 15 opens, and the compressed high-temperature, high-pressure refrigerant enters the high-pressure chamber 16 isolated by the high and low pressure partition 17. Then it is discharged from the compressor through the exhaust pipe 18 and re-enters the refrigeration system.

[0058] The scroll compressor supplier pre-fills a sufficient amount of lubricating oil and stores it in the oil sump 19 at the bottom of the compressor. When the scroll compressor is working, the motor runs and the rotor 5 drives the crankshaft assembly 6 to rotate. The oil suction pipe 20 on it has an oil stirring plate 21 that drives the lubricating oil to flow upward through the inner hole of the crankshaft assembly 6, enter the gap between the main bearing and the main support assembly 8 and the moving scroll 12 for lubrication, and lubricate and seal the refrigerant in the compression assembly. Then the lubricating oil flows downward through the return oil pipe 23 back to the oil sump 19.

[0059] The junction box A10 houses the protection device 33, the compressor power supply sealing terminal 31, and the PTC terminal 30, which are connected to the corresponding input terminals of the protection device 33 via wires.

[0060] The sealed terminal of the oil level sensor 32 inside junction box B34 is connected to the corresponding input terminal of the protection device 33 in junction box A10 via a wire.

[0061] The motor 3 can be an induction motor or a permanent magnet synchronous motor. The heat generated by the loss is mainly generated by the winding 24 of the stator 4, which is made of copper, aluminum, copper-clad aluminum round or flat wire, and enameled wire coated with an insulating varnish film to form a coil of a specific shape, or a combination of two or more of the above enameled wires to form a coil of a specific shape.

[0062] During the manufacturing process of the motor stator 4, one or more PTC-25s are pre-installed in the winding 24. The principle of placement is that there is at least one PTC-25 for each phase coil, or at least one on the upper part and one on the lower part of the winding, and they are not in the same phase winding. All the pre-installed PTC-25s are connected in series, and two wires-27 are led out.

[0063] A PTC 26 is pre-installed in the exhaust chamber 16, passing through the high and low pressure partition 17, and two wires 28 are sealed and led out.

[0064] Wire 1 27 is connected in series with wire 2 28, and finally two wires 3 29 are led out and connected to the sealing terminal 30, leading out of the compressor housing.

[0065] like Figure 4 The diagram shows a pre-set PTC circuit with a total of 9 or fewer PTCs, conforming to IEC 60738-1, and a total series resistance value R. Σ :

[0066] R Σ =R1+R2+R3+……+R N +R0

[0067] like Figure 5 As shown, the characteristic curve of a single PTC resistance value R versus temperature T shows that as the resistance value changes at temperature T... t At that time, the PTC resistance value rapidly increases to R0, which is tens of times that at room temperature.

[0068] PTC-25 is set according to the insulation class of motor 3, and the T of PTC in different positions t They are not necessarily the same; the typical range is 90–155℃.

[0069] PTC 2.26T t The typical range is 105℃~150℃.

[0070] Any one or more PTCs of PTC-25 and PTC-26 reach T t At that time, R Σ The value rapidly increases significantly beyond the preset threshold R of the protection device. t At that time, it was judged as a malfunction.

[0071] The protection device has a preset threshold R. t The range of PTCs in series within the compressor is 1kΩ to 5kΩ.

[0072] When the compressor stalls due to mechanical component damage or other reasons, especially when motor 3 is an induction motor, its stall current LRA is 7-11 times the rated current RLA, and the temperature rise rate of the stator winding 24 far exceeds that of normal operation. Its temperature change rate dT / dt is:

[0073]

[0074] Among them, S C —The cross-sectional area of ​​a single turn of the conductor constituting stator winding 24;

[0075] ρ 电阻率 —The resistivity of the metallic conductors constituting the stator winding 24;

[0076] C—Specific heat capacity of the metals constituting the conductors of stator winding 24;

[0077] ρ 密度 —Metal density of the conductors constituting stator winding 24;

[0078] The parameters of copper and aluminum, which are commonly used metals for stator windings, differ greatly. The dT / dt range of copper wire is 20-30℃ / s, while that of aluminum wire is 45-60℃ / s. The dT / dt of copper-clad aluminum wire is between the two.

[0079] If the compressor is stalled in a cold state, it may take several seconds, or even tens of seconds, to reach the PTC resistance change temperature T. t If a fault protection is initiated, the heat accumulated in the stator winding 24 may reach an even higher temperature, potentially causing it to burn out.

[0080] Based on the above dT / dt and the RT characteristic curve of PTC, a threshold value k for the rate of change of PTC resistance is set. t It provides rapid protection for stator windings 24 that use copper wire, aluminum wire, copper-clad aluminum wire, or a mixture of the above.

[0081] like Figure 6 As shown, the three-phase voltage waveform of the compressor power supply comes from the power grid or is transferred through the refrigeration unit.

[0082] If motor 3 is an induction motor, the above power supply voltage is connected to the compressor power supply sealed terminal and simultaneously connected in parallel to the R, S, T input terminals of the protection device.

[0083] The power supply voltage detection module of the protection device continuously detects N three-phase voltage waveforms as one cycle. After detecting M cycles, a threshold H is set. If the cumulative number of missing voltage waveforms of a certain phase in N×M waveforms exceeds the threshold H, it is judged as a phase loss fault.

[0084] The amplitude U of the same N×M waveforms R U S U T One of them, U X :

[0085]

[0086] The 10% in the above formula is a common setting, not a limitation, and can be set according to the power supply quality and the design capability of the compressor motor.

[0087] If the cumulative number of occurrences exceeds the threshold H, it is determined to be a three-phase voltage imbalance fault.

[0088] The zero-crossing time t of each phase voltage waveform R t S t T The sequence of phases is compared, and if the cumulative number of abnormalities exceeds the threshold H, it is determined to be a phase sequence abnormality fault.

[0089] The same threshold H can be set for phase loss, voltage imbalance, and abnormal phase sequence in the power supply voltage detection, or different thresholds can be set.

[0090] If motor 3 is a permanent magnet synchronous motor, the power supply voltage is modulated by a dedicated driver or a general-purpose frequency converter and then input to the compressor power supply sealed terminal. The modulated voltage waveform input to the compressor is different from the sinusoidal waveform of the power supply directly from the grid. The above detection method is not applicable. In addition, the driver or frequency converter has similar protection functions. In this case, the protection device can monitor the input voltage of the driver or frequency converter, or this part of the function can be left unused.

[0091] like Figure 7 As shown, the oil level sensor 32 installed in the compressor 1 is a grid-type capacitor formed by two long rectangular metal alloy plates 35 that are parallel to each other with a certain gap. The two metal alloy plates are welded to the sealing terminal 36 and led out through the housing 2 of the compressor 1.

[0092] like Figure 8 As shown in the figure, the characteristic curve of the relationship between the capacitance value of the capacitive sensor and the oil level shows that the capacitance value is C when the lubricating oil completely submerges the metal grid. 100 When the lubricating oil level is lower than the oil level sensor, the capacitance value is C0 when the metal grid is filled with gaseous refrigerant. When the lubricating oil submerges part of the metal grid, the static position of the liquid level is linearly related to the capacitance value.

[0093] The capacitance detection module of the aforementioned capacitance value input protection device is set with a capacitance threshold C. t When the compressor is running, the lubricating oil level is unstable due to agitation and oil circulation, and a small amount of oil remains between the compressor's mechanical parts. Short-term oil supply interruption is permissible, generally at least a few seconds to tens of seconds.

[0094] The oil level detection module of the protection device checks the capacitance value once at interval t1. If the capacitance value is lower than the threshold more than G times within the T1 cycle, it is judged as an oil shortage fault.

[0095] like Figure 1 The figure shows the vibration amplitude and frequency threshold curve of a variable frequency scroll compressor (which uses a permanent magnet synchronous motor) as an example. The vibration amplitude is related to the compressor's operating speed. The vibration is generated by the motor driving the mechanical parts. The vibration frequency is the operating frequency of the compressor motor.

[0096] If the compressor uses an induction motor, the power supply frequency is usually a fixed 50Hz or 60Hz. Due to the rotor slip s of the motor, its operating frequency fm is...

[0097]

[0098] In the above announcement, f represents the power supply frequency.

[0099] p — Number of pole pairs of the electric motor

[0100] Therefore, when the compressor uses an induction motor, it is only Figure 9 A portion of the curve.

[0101] Because the compressor is rigidly connected to the protection device, the vibration is directly transmitted to the vibration detection circuit inside the protection device. The compressor's vibration amplitude and frequency are detected at intervals t2 and compared with a characteristic curve. If the vibration amplitude obtained within time T2 is greater than the set value A at the corresponding frequency... t If the number of occurrences exceeds J, it is considered a fault.

[0102] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A compressor protection device, characterized in that: The compressor protection device includes: a detection unit, a processing and execution unit; The detection unit includes: a PTC resistance value detection module, a power supply voltage detection module, an oil level sensor capacitance value detection module, and a vibration frequency and amplitude detection module; The processing and execution unit includes: a processor and a communication module, an alarm light, a relay, and a memory connected to the processor output. The output terminals of the PTC resistance detection module, power supply voltage detection module, oil level sensor capacitance detection module, and vibration frequency and amplitude detection module are connected to the input terminal of the processor, transmitting the detection information to the processor. The processor processes the input information and compares it with a preset threshold or curve. When the processor's comparison exceeds the preset threshold, it outputs a command, the alarm light displays the fault category, the relay performs an action, the memory stores the fault information and normal operation information, and the communication module transmits the fault information and normal operation information to the external control system. The PTC resistance detection module includes: one or more PTC-1 (25) placed on the winding (24) of the motor stator (4) inside the compressor (1), and PTC-2 (26) fixed on the high and low pressure partition (17) inside the high pressure chamber (16). Both PTC-1 (25) and PTC-2 (26) are connected in series, and the total number does not exceed 9. The sum of the resistance values ​​R of PTC-1 (25) and PTC-2 (26) Σ Greater than the threshold R t When, or the sum of PTC resistance values ​​increases at a rate dR Σ / d t Greater than the threshold value k t When this occurs, it is determined to be a fault; The power supply voltage detection module monitors the compressor's (1) power supply voltage, detects the three-phase voltage phase, and judges any abnormality as a fault; continuous detection N Three-phase voltage waveforms M One cycle, as described N × M The waveforms are missing a certain phase voltage waveform. H The amplitude of a single or three-phase voltage waveform U R , U S , U T One of the phases is the average value ( U R + U S + U T A cumulative deviation of more than 10% of 1 / 3 occurs. H Next, or the zero-crossing moment of the voltage waveform of each phase. t R , t S , t T The order of events was compared, and the cumulative number of anomalies exceeded the threshold. H This was determined to be a malfunction.

2. The compressor protection device according to claim 1, characterized in that: The oil level sensor capacitance detection module detects the capacitance value of the metal grid sensor placed at the minimum oil level required by the compressor (1) at intervals. t The capacitance value is checked once every 1 hour. T Within 1 hour, the capacitance value was detected to be less than the set value C. t If the number of occurrences exceeds G, it is considered a fault.

3. The compressor protection device according to claim 1, characterized in that: The vibration frequency and amplitude detection module is fixedly mounted on the protection device (33). The protection device (33) is rigidly connected to the outer shell of the compressor (1), or rigidly connected to the outer shell of the compressor (1) through the junction box A (10). The vibration frequency and amplitude detection module uses a built-in sensing circuit to detect vibrations at intervals. t 2. Detect the compressor vibration frequency and amplitude once within time T2. If the vibration amplitude obtained within time T2 is greater than the set value A at the corresponding frequency... t If the number of occurrences exceeds J, it is considered a fault.

4. The compressor protection device according to claim 1, characterized in that: After comparing the fault information detected by any one of the PTC resistance detection module, power supply voltage detection module, oil level sensor capacitance detection module, and vibration frequency and amplitude detection module, the processor outputs the information to the alarm light. The alarm light displays the fault category, the relay activates, and the control contactor cuts off the power supply to the compressor.

5. The compressor protection device according to claim 4, characterized in that: The processor compares the fault or normal operation information detected by any one of the PTC resistance detection module, power supply voltage detection module, oil level sensor capacitance detection module, and vibration frequency and amplitude detection module, and outputs the information to the communication module. The communication module uploads the information to the designated cloud server through the wireless transmission module, and the communication module has a dedicated interface to interact with other devices.

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