Patent Grant
10739327
This application is a National Stage application of International Patent Application No. PCT/CN2016/081066, filed on May 5, 2016, which claims priority to Chinese Patent Application No. 201510233934.4, filed on May 8, 2015, each of which is hereby incorporated by reference in its entirety.
The present invention relates to the technical field of detection, in particular to a monitoring apparatus and a monitoring method for monitoring lubricating oil in a compressor.
In some compressors, in order to reduce compressor wear and extend the service life of the compressor, a sufficient amount of lubricating oil is poured into the compressor, to provide adequate lubrication for the various components of the compressor. However, in actual applications, if the quality of the lubricating oil in a compressor deteriorates, this might result in failure of the lubricating function of the lubricating oil in the compressor.
Indices associated with the quality of lubricating oil in a compressor include the degree of dilution of the lubricating oil, foreign substance mixed into the lubricating oil, oxidation or carbonization of the lubricating oil, etc.
If the degree of dilution of lubricating oil in a compressor is too high, i.e. an excessive amount of coolant has mixed into the lubricating oil in the compressor, the concentration of the lubricating oil in the compressor will be too low as a result. This will cause a reduction in the viscosity of the lubricating oil; once the viscosity of the lubricating oil is reduced, serious wear to the bearings of the compressor will result. Thus, once the degree of dilution of lubricating oil is higher than a warning level, it is necessary to immediately stop the compressor or reduce the degree of dilution of the lubricating oil. In the prior art, some of the coolant that has mixed into the lubricating oil can generally be evaporated out by heating the lubricating oil, so as to reduce the degree of dilution of the lubricating oil.
If foreign substance, for instance iron fragments that have fallen off compressor bearings, becomes mixed into lubricating oil, this will aggravate wear of compressor components. Once iron fragments are mixed into lubricating oil, it is necessary to immediately stop the compressor, and remove the iron fragments from the lubricating oil.
If lubricating oil is oxidized or carbonized, the lubricating oil will lose its lubricating function, and this will lead to rapid wear of the compressor, shortening the service life of the compressor. Once lubricating oil is oxidized or carbonized, it is necessary to immediately stop the compressor, and replace the lubricating oil with new lubricating oil.
In summary, in order to ensure that a compressor can operate safely, the quality of lubricating oil in the compressor must be monitored on-line in real time.
Regarding the on-line real-time monitoring of the quality of lubricating oil in a compressor, in the prior art, the quality of lubricating oil is generally monitored by measuring the viscosity, density or contaminants of the lubricating oil. However, an existing monitoring apparatus for monitoring the quality of lubricating oil by measuring the viscosity, density or contaminants of the lubricating oil has a very high cost; the price of the monitoring apparatus is 400,000 to 1.6 million RMB. Furthermore, the installation of such an existing monitoring apparatus is very complex, and large amounts of data need to be processed, so the detection speed is slow. At present, such a monitoring apparatus is only suitable for laboratory tests; it cannot yet be used industrially.
The objective of the present invention is to solve at least one aspect of the abovementioned problems and shortcomings in the prior art.
An objective of the present invention is to provide a monitoring apparatus and a monitoring method for on-line real-time monitoring of lubricating oil in a compressor, which can conveniently and accurately monitor quality, or quality and level, of the lubricating oil in the compressor.
According to one aspect of the present invention, a monitoring apparatus is provided, for monitoring lubricating oil in a compressor. The monitoring apparatus includes: a first capacitance detector, disposed in the compressor, and completely immersed in the lubricating oil in the compressor; a calculation unit, for calculating a relative dielectric constant εr of the lubricating oil in the compressor according to a first capacitance value C11 detected by the first capacitance detector; and a determining unit, for monitoring whether quality of the lubricating oil in the compressor is abnormal according to the relative dielectric constant εr calculated.
According to an embodiment of the present invention, the monitoring apparatus further includes: a second capacitance detector, disposed vertically in the compressor. The calculation unit calculates, based on the calculated relative dielectric constant εr of lubricating oil in the compressor and a second capacitance value C21 detected by the second capacitance detector disposed vertically in the compressor, a depth H to which the second capacitance detector is immersed in the lubricating oil in the compressor; and the determining unit monitors, based on the depth H calculated, whether the level of lubricating oil in the compressor is lower than a safe level value.
According to another embodiment of the present invention, the relative dielectric constant εr of the lubricating oil in the compressor is calculated according to formula (1):
wherein
C10 is a capacitance value detected by the first capacitance detector in vacuum.
According to another embodiment of the present invention, the depth H to which the second capacitance detector is immersed in the lubricating oil is calculated according to formula (2):
wherein
C20 is a capacitance value detected by the second capacitance detector in air, and
L is the length of the second capacitance detector in a vertical direction.
According to another embodiment of the present invention, the determining unit monitors whether the calculated relative dielectric constant εr is greater than a predetermined dielectric constant value, and if the calculated relative dielectric constant εr is greater than the predetermined dielectric constant value, the determining unit determines that the quality of the lubricating oil in the compressor is abnormal; and/or the determining unit monitors whether the calculated depth H is less than a predetermined depth value, and if the calculated depth H is less than the predetermined depth value, the determining unit determines that the level of lubricating oil in the compressor is lower than a safe level value.
According to another embodiment of the present invention, the first capacitance detector is a parallel-plate capacitance detector or a cylindrical capacitance detector; the second capacitance detector is a parallel-plate capacitance detector or a cylindrical capacitance detector.
According to another embodiment of the present invention, the first capacitance detector is substantially horizontally installed on a bottom wall of an oil tank in the compressor.
According to another embodiment of the present invention, the second capacitance detector is installed vertically on a sidewall of the oil tank in the compressor.
According to another practical embodiment of the present invention, a lower end of the second capacitance detector is in contact with a bottom wall of the oil tank in the compressor.
According to another embodiment of the present invention, the first capacitance detector and the second capacitance detector are two physically separated components or are integrated to form a one-piece component.
According to another aspect of the present invention, a monitoring method is provided, for monitoring lubricating oil in a compressor. The monitoring method includes steps of: calculating a relative dielectric constant εr of lubricating oil in a compressor according to a first capacitance value C11 detected by a first capacitance detector completely immersed in the compressor, and monitoring whether quality of the lubricating oil in the compressor is abnormal according to the relative dielectric constant εr calculated.
According to an embodiment of the present invention, the abovementioned method further includes: calculating, based on a second capacitance value C21 detected by a second capacitance detector disposed vertically in the compressor and the calculated relative dielectric constant εr of lubricating oil in the compressor, a depth H to which the second capacitance detector is immersed in the lubricating oil in the compressor.
According to another embodiment of the present invention, in the abovementioned method, the relative dielectric constant εr of the lubricating oil in the compressor is calculated according to formula (1):
wherein
C10 is a capacitance value detected by the first capacitance detector in vacuum.
According to another embodiment of the present invention, in the abovementioned method, the depth H to which the second capacitance detector is immersed in the lubricating oil is calculated according to formula (2):
wherein
C20 is a capacitance value detected by the second capacitance detector in air, and
L is the length of the second capacitance detector in a vertical direction.
According to another embodiment of the present invention, in the abovementioned method, when the calculated relative dielectric constant εr is greater than a predetermined dielectric constant value, the quality of lubricating oil in the compressor is determined as abnormal; and/or when the calculated depth H is less than a predetermined depth value, the level of the lubricating oil in the compressor is determined as lower than a safe level.
According to another embodiment of the present invention, the abovementioned method further includes: switching off the compressor when the calculated relative dielectric constant εr is greater than a predetermined dielectric constant value or when the calculated depth H is less than a predetermined depth value.
According to another embodiment of the present invention, in the abovementioned method, the first capacitance detector is a parallel-plate capacitance detector or a cylindrical capacitance detector; the second capacitance detector is a parallel-plate capacitance detector or a cylindrical capacitance detector.
According to another embodiment of the present invention, in the abovementioned method, the first capacitance detector is substantially horizontally installed on a bottom wall of an oil tank in the compressor.
According to another embodiment of the present invention, in the abovementioned method, the second capacitance detector is installed vertically on a sidewall of the oil tank in the compressor.
According to another embodiment of the present invention, in the abovementioned method, a lower end of the second capacitance detector is in contact with a bottom wall of the oil tank in the compressor.
According to another embodiment of the present invention, in the abovementioned method, the first capacitance detector and the second capacitance detector are two physically separated components or are integrated to form a one-piece component.
In the monitoring apparatus and monitoring method in the various practical embodiments of the present invention above, the capacitance detectors enable convenient and accurate monitoring of the quality of lubricating oil in a compressor. Moreover, continuous real-time detection of the level of lubricating oil can be carried out to realize simultaneous detection of the quality and level of lubricating oil. The monitoring apparatus reduces monitoring costs, and increases monitoring accuracy.
The following description of the present invention with reference to the accompanying drawings will make other objectives and advantages of the present invention obvious, and can provide a comprehensive understanding of the present invention.
The technical solution of the present invention is further explained in detail below according to embodiments, with reference to the accompanying drawings. In the description, identical or similar reference signs indicate identical or similar components. The following explanation of embodiments of the present invention with reference to the accompanying drawings is intended to explain the overall inventive concept of the present invention, and should not be interpreted as a limitation of the present invention.
Furthermore, in the following detailed description, to facilitate explanation, several specific details are expounded to provide a comprehensive understanding of embodiments of the present disclosure. However, it is obvious that one or more embodiments could also be implemented in the absence of these specific details. In other cases, well-known structures and apparatuses are embodied as illustrations in order to simplify the accompanying drawings.
As stated above, to ensure that a compressor can operate safely, the quality of lubricating oil in the compressor must be monitored on-line in real time. According to an overall technical concept of the present invention, a monitoring apparatus is provided, for monitoring lubricating oil in a compressor. The monitoring apparatus includes: a first capacitance detector, disposed in the compressor and completely immersed in lubricating oil in the compressor; a calculation unit, for calculating a relative dielectric constant εr of the lubricating oil in the compressor according to a first capacitance value C11 detected by the first capacitance detector; and a determining unit, for monitoring whether the quality of the lubricating oil in the compressor is abnormal according to the relative dielectric constant εr calculated.
In actual applications, operation safety of the compressor will be affected if the level of the lubricating oil in the compressor is too low. If the level of the lubricating oil in the compressor is too low, it will be impossible to provide a sufficient amount of lubricating oil to various components of the compressor, and as a result, the various components of the compressor will not be lubricated adequately. Consequently, it accelerates wear of the various components of the compressor, thereby shortening the service life of the compressor. Thus, once the level of the lubricating oil in the compressor is lower than a warning level, it is necessary to immediately switch off the compressor, and provide a sufficient amount of lubricating oil into the compressor.
Regarding on-line real-time monitoring of the level of lubricating oil in the compressor, in the conventional art, the level of lubricating oil in a compressor is generally monitored by a pressure-differential detector or a magnetic floating ball. However, since the pressure in the compressor is up to 45 bar, this will damage the pressure-differential detector or magnetic floating ball. Furthermore, since operating circumstance inside the compressor is very complex, for example, there will be foam, temperature instability, higher pressure fluctuation, and bigger density variation, it will make the pressure-differential detector or magnetic floating ball unable to precisely detect the level of the lubricating oil in the compressor.
In view of the above, the abovementioned monitoring apparatus further includes: a second capacitance detector, disposed vertically in the compressor. The calculation unit calculates, based on the calculated relative dielectric constant εr of the lubricating oil in the compressor and a second capacitance value C21 detected by the second capacitance detector disposed vertically in the compressor, a depth H to which the second capacitance detector is immersed in the lubricating oil in the compressor; the determining unit, monitors, based on the depth H calculated, whether the level of the lubricating oil in the compressor is lower than a safe level value.
According to a technical concept of the present invention, a monitoring method is provided, for monitoring lubricating oil in a compressor. The monitoring method includes steps of: calculating a relative dielectric constant εr of the lubricating oil in the compressor according to a first capacitance value C11 detected by a first capacitance detector completely immersed in the compressor, and monitoring whether quality of the lubricating oil in the compressor is abnormal according to the relative dielectric constant εr calculated.
According to another technical concept of the present invention, the abovementioned monitoring method further includes the step of: calculating, based on a second capacitance value C21 detected by a second capacitance detector disposed vertically in the compressor and the calculated relative dielectric constant εr of the lubricating oil in the compressor, a depth H to which the second capacitance detector is immersed in the lubricating oil in the compressor, and monitoring, based on the depth H calculated, whether the level of lubricating oil in the compressor is lower than a safe level value.
In an embodiment of the present invention, a monitoring apparatus for monitoring lubricating oil 20 in a compressor 10 is disclosed. As
As
wherein
C10 is a capacitance value detected by the first capacitance detector 100 in vacuum.
In the embodiments of the present invention, the determining unit of the monitoring apparatus monitors whether the quality of the lubricating oil 20 in the compressor 10 is abnormal according to the relative dielectric constant εr calculated.
A brief description is given below of the principles of monitoring whether the quality of the lubricating oil 20 in the compressor 10 is abnormal according to the relative dielectric constant εr calculated.
Generally, indices associated with the quality of lubricating oil in a compressor include dilution of the lubricating oil, foreign substance mixed into the lubricating oil, oxidation or carbonization of the lubricating oil, etc.
If the dilution of the lubricating oil in a compressor is too high, i.e. an excessive amount of coolant mixes into the lubricating oil in the compressor, the concentration of the lubricating oil in the compressor will be too low as a result. This will cause a reduction in the viscosity of the lubricating oil; once the viscosity of the lubricating oil is reduced, it will result in serious wear to the bearings of the compressor.
The relative dielectric constant of coolant is far greater than the relative dielectric constant of pure lubricating oil. Thus, once an excessive amount of coolant has mixed into lubricating oil, the relative dielectric constant of the lubricating oil (or a mixture of lubricating oil and coolant) will be greatly increased, and as a result, the relative dielectric constant εr of the lubricating oil mentioned above and detected on-line will be greater than a predetermined dielectric constant value (or a dielectric constant warning value). Once the relative dielectric constant εr of the lubricating oil mentioned above and detected on-line is greater than the predetermined dielectric constant value, the monitoring apparatus gives an alarm, and immediately switches off the compressor or reduces the dilution of the lubricating oil. For example, some of the coolant mixed into the lubricating oil can be evaporated out by heating the lubricating oil, so as to reduce the dilution of the lubricating oil, thereby reducing the relative dielectric constant εr of the lubricating oil to a value below the warning value.
If foreign substance mixes into the lubricating oil, for instance iron fragments that have fallen off compressor bearings become mixed into the lubricating oil, this will aggravate wear of compressor components. Since the relative dielectric constant of iron fragments is far greater than the relative dielectric constant of pure lubricating oil, the relative dielectric constant of the lubricating oil will be greatly increased once iron fragments have mixed into lubricating oil, and as a result, the relative dielectric constant εr of the lubricating oil mentioned above and detected on-line will be greater than a predetermined dielectric constant value (or a dielectric constant warning value). Once the relative dielectric constant εr of the lubricating oil mentioned above and detected on-line is greater than the warning value, the monitoring apparatus gives an alarm, and immediately switches off the compressor. Once the compressor is switched off, the iron fragments must be removed from the lubricating oil.
If lubricating oil is oxidized or carbonized, the lubricating oil will lose its lubricating function, and this will lead to rapid wear of the compressor. Once lubricating oil has been oxidized or carbonized, the relative dielectric constant εr thereof will increase sharply, and as a result, the relative dielectric constant εr of the lubricating oil mentioned above and detected on-line will be greater than a predetermined dielectric constant value (or a dielectric constant warning value). Once the relative dielectric constant εr of the lubricating oil mentioned above and detected on-line is greater than the warning value, the monitoring apparatus gives an alarm and immediately switches off the compressor. Once the compressor is switched off, the lubricating oil must be replaced with new lubricating oil.
As
Table 1 below shows a capacitance value detected when the first capacitance detector 100 shown in
According to Table 1 above, it can be clearly seen that the mean value of the relative dielectric constant of the pure fatty oil, detected by the parallel-plate first capacitance detector 100 provided in the present invention, is 3.1708. The true relative dielectric constant of the pure fatty oil is 3.20. As can be seen, the detection result of the first capacitance detector 100 mentioned above is substantially accurate, and the first capacitance detector 100 can be used to detect the relative dielectric constant of lubricating oil in the compressor.
As shown in
As shown in
As shown in
Thus, the calculation unit of the monitoring apparatus can calculate, based on the calculated relative dielectric constant εr of the lubricating oil 20 in the compressor 10 and a second capacitance value C21 detected by the second capacitance detector 200, the depth H to which the second capacitance detector 200 is immersed in the lubricating oil 20 in the compressor 10.
The depth H to which the second capacitance detector 200 is immersed in the lubricating oil 20 is calculated according to Formula (2):
wherein
C20 is a capacitance value detected by the second capacitance detector 200 in air, and
L is the length of the second capacitance detector 200 in a vertical direction.
In the embodiments of the present invention, the determining unit of the monitoring apparatus monitors, based on the depth H calculated, whether the level of the lubricating oil 20 in the compressor 10 is lower than a safe level value.
As shown in
As shown in
As can be seen from
In an embodiment of the present invention, as shown in
In an embodiment of the present invention, as shown in
In an embodiment of the present invention, as shown in
In the embodiment shown in
In another embodiment of the present invention, a monitoring method is disclosed, for monitoring lubricating oil in a compressor. The monitoring method includes the following steps:
calculating a relative dielectric constant εr of lubricating oil 20 in a compressor 10 according to a first capacitance value C11 detected by a first capacitance detector 100, and monitoring whether quality of the lubricating oil 20 in the compressor 10 is abnormal according to the relative dielectric constant εr calculated.
In an embodiment of the present invention, the monitoring method further includes:
calculating, based on the calculated relative dielectric constant εr of the lubricating oil 20 in the compressor 10 and a second capacitance value C21 detected by the second capacitance detector 200 disposed vertically in the compressor 10, a depth H to which the second capacitance detector 200 is immersed in the lubricating oil 20 in the compressor 10.
In another embodiment of the present invention, the abovementioned monitoring method may further include the step of: switching off the compressor 10 immediately when the calculated relative dielectric constant εr is greater than a predetermined dielectric constant value or when the calculated depth H is less than a predetermined depth value.
As stated above, an important index associated with the quality of the lubricating oil in the compressor is dilution of the lubricating oil. If the dilution of the lubricating oil in the compressor is too high, i.e. an excessive amount of coolant is mixed into the lubricating oil in the compressor, the concentration of the lubricating oil in the compressor will be too low as a result. This will cause a reduction in the viscosity of the lubricating oil. Once the viscosity of the lubricating oil is reduced, it will result in serious wear to the bearings of the compressor. Thus, once the dilution of the lubricating oil is higher than a warning level, it is necessary to immediately switch off the compressor or reduce the dilution of the lubricating oil.
Thus, it is needed to monitor the dilution of the lubricating oil on-line in real time. The inventors of the present application, on the basis of a large amount of testing, have found that a certain functional relationship exists between the dilution of the lubricating oil and the relative dielectric constant of the lubricating oil. Thus, the dilution of the lubricating oil can be monitored by monitoring the relative dielectric constant of the lubricating oil.
As shown in
y=0.0003x2+0.0416x+2.8374 (3)
wherein x ranges from 0% to 100%.
As can be seen from the relationship graph shown in
However, the dilution of the lubricating oil is only one of parameters for judging the quality of the lubricating oil. During actual application, the quality of the lubricating oil in a compressor may also be monitored with reference to other parameters (such as viscosity, density or contaminants) of the lubricating oil, thereby determining a warning value for the relative dielectric constant. Thus, the relative dielectric constant of the lubricating oil may be measured, and the quality of the lubricating oil may be determined according to the relative dielectric constant and the warning value.
Those skilled in the art will understand that the embodiments described above are all demonstrative. Moreover, those skilled in the art could make improvements thereto. The structures described in the various embodiments may be freely combined, in the absence of any conflict in structures or principles.
Although the present invention has been explained with reference to the accompanying drawings, the embodiments disclosed in the accompanying drawings are intended to explain preferred embodiments of the present invention demonstratively, and must not be interpreted as a limitation of the present invention.
Although some embodiments of the present overall inventive concept have been displayed and explained, those skilled in the art will understand that changes may be made to these embodiments without departing from the principles and spirit of the present overall inventive concept. The scope of the present invention is defined by the claims and their equivalents.
It should be noted that the word “includes” does not exclude other elements or steps, and the word “a” does not exclude a plurality. Furthermore, no reference signs in the claims should be interpreted as limiting the scope of the present invention.
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| WO2016/180263 | 11/17/2016 | WO | A |
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