Patent Publication Number: US-RE46091-E

Title: Oil level detecting device for a compressor and an air conditioning system having the same

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application is a Reissue Application of prior U.S. Pat. No. 8,733,116 issued May 27, 2014 (U.S. patent application Ser. No. 12/958,874 filed Dec. 2, 2010), which claims priority under 35 U.S.C. §119 to Korean Application No. 10-2010-0030122 filed in Korea on Apr. 1, 2010, whose entire disclosure(s) is/are disclosures are hereby incorporated by reference. 
     BACKGROUND 
     1. Field 
     An oil level detecting device for a compressor and an air conditioning system having the same are disclosed herein. 
     2. Background 
     Oil level detecting devices for compressors and air conditioning systems having the same are known. However, they suffer from various disadvantages. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments will be described in detail with reference to the following drawings in which like reference numerals refer to like elements, and wherein: 
         FIG. 1  is a cross-sectional view of a compressor having an oil level detecting device according to an embodiment; 
         FIG. 2  is a perspective view of the oil level detecting device of  FIG. 1  according to an embodiment; 
         FIG. 3  is a perspective view of an oil level detecting device according to another embodiment; 
         FIG. 4  is a perspective view of a controller including a signal processor according to an embodiment; 
         FIG. 5  is a circuit diagram of the signal processor of  FIG. 4 ; and 
         FIG. 6  is a block diagram of an air conditioning system according to an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     A compressor, as broadly described and embodied herein, may include a drive motor that provides a driving force to a compression device to compress refrigerant while operating in conjunction with the drive motor. The compressor may be categorized as, for example, a reciprocating type, a scroll type, a rotary type, or a vibration type, depending on the method by which the refrigerant is compressed. Reciprocating type, scroll type, and rotary type compressors use a rotary motion of the drive motor, while vibration type compressors use a reciprocating motion of the drive motor. 
     The drive motor of a rotary type compressor may be provided with a crankshaft that transfers the rotary motion of the drive motor to the compression device. For example, the drive motor of the rotary compressor may include a stator fixed to a container or case, a rotor positioned in the stator with a predetermined gap therebetween to rotate in interaction with the stator, and a crankshaft connected to the rotor to transfer rotary power to the compression device. In addition, the compression device may be combined with the crankshaft to suction, compress, and discharge refrigerant while rotating inside a cylinder. A plurality of bearing members may be provided to form a compression space between the crank shaft and the compression device, and may also support the compression device. 
     In the compressor having the foregoing structure, the refrigerant may be compressed by rotating the compression device with rotary motion generated by the drive device. The compressor may be provided with an oil supply device to supply oil to the compression device that may facilitate the rotation of the compression device as well as easily dissipate heat generated during operation of the drive device. The oil supply device may be provided at a lower end portion of the crankshaft. The oil may be stored in a lower portion of the container, or case, and may be pumped through an oil flow path formed inside the crankshaft by the rotation of the crankshaft. The pumped oil may then be supplied to each component inside the compressor. 
     In compressors of various air conditioning systems, the oil flow path, or pipe, in which the working fluid flows may be lengthened, requiring an increased amount of oil to operate the compressor. Thus, it may be difficult to estimate when, where, and how much oil will remain, and accordingly, it may be difficult to maintain the oil level inside each compressor in an appropriate condition or level. As a result, the oil level in the oil storage space may become irregular and may vary outside of acceptable levels during operation of the respective compressor, even when the oil levels were within a suitable range at an initial stage of the operation. 
     Therefore, it may be necessary to continuously check the oil level inside each compressor during operation of the air conditioner. If it is determined that the oil level is not in an appropriate condition, then an oil collecting operation to add oil to the compressor may be performed. Conventionally, it is not easy to check the oil level in each compressor, and therefore, the oil collecting operation may be performed at a predetermined period of time regardless of the actual oil level. Performing the oil collecting operation irrespective of the actual oil levels may be inefficient as energy is wasted during unnecessary oil collecting operations. 
     To overcome this problem, an oil level sensor may be provided in the compressor to measure the oil level to determine whether an oil collecting operation is necessary. In such a system, the number of unnecessary oil collecting operations may be reduced, resulting in decreased energy consumption as well as decreased compressor downtime. 
       FIG. 1  is a cross-sectional view of a compressor having an oil level detecting device according to an embodiment, and  FIG. 2  is a perspective view of the oil level detecting device of  FIG. 1  according to an embodiment. Simply for ease of explanation, this embodiment is described with reference to a scroll compressor, but the embodiments are not limited thereto. It will be apparent to those skilled in the art that the embodiments disclosed herein may be applied to any type of compressor, in particular, any type of compressor in which oil is provided at a lower end portion of a rotating shaft. 
     Referring to  FIGS. 1 and 2 , a main frame  120  and a sub-frame  130  may be provided inside a container or case  110 , and a drive device  140 , for example, a drive motor, may be provided between the main frame  120  and the sub-frame  130 . A compression device may be provided at an upper side of the main frame  120  and combined with the drive motor  140  that compresses a working fluid, for example, a refrigerant. The compression device may include a fixed scroll  150  and an orbiting scroll  160 . 
     The drive motor  140  may include a stator  141 , which may be wound with a coil, a rotor  142  rotatably inserted in the stator  141 , and a rotating shaft  143  attached to a center of the rotor  142  that that transfers rotary force to a compression mechanism. A driving pin portion  144  may be formed to protrude at an upper end of the rotating shaft  143 . The driving pin portion  144  may be formed adjacent to a rotational axis of the rotating shaft  143 . That is, the driving pin portion  144  may be positioned away from a rotational center of the rotating shaft  143 . 
     The compression mechanism may include a fixed scroll  150  fixed to an upper surface of the main frame  120 , an orbiting scroll  160  placed on the upper surface of the main frame  120  and engaged with the fixed scroll  150 , and an Oldham ring  170  disposed between the orbiting scroll  160  and the main frame  120  that prevents the rotation of the orbiting scroll  160 . A fixed wrap  151  may be spirally wound and formed on the fixed scroll  150 . Further, an orbiting wrap  161  may be spirally wound and formed on the orbiting scroll  160 . The fixed wrap  151  together with the orbiting wrap  161  may form a compression chamber (P). A boss portion  162  may be formed to protrude at a bottom surface of the orbiting scroll  160 , for example, a lateral surface opposite the orbiting wrap  161 . The boss portion  162  may engage the rotating shaft  143  to receive a rotary force therefrom. 
     A sliding bush  163  may be combined with the driving pin portion  144  of the rotating shaft  143  to slide in a radial direction. The sliding bush  163  may be combined with the boss portion  162  of the orbiting scroll  160  to slide in a rotating direction. An external diameter of the sliding bush  163  may be formed to be same as an internal diameter of the boss portion  162  of the orbiting scroll  160 , to thereby reduce friction between the rotating shaft  143  and the orbiting scroll  160 . Further, a main frame bush  122  may be provided on an inside surface of the main frame  120  to reduce friction between the rotating shaft  143  and main frame  120 . Oil may be supplied by an oil feeder  180  provided at a lower end portion of the rotating shaft  143  to lubricate each of the bushes  122 ,  163 . 
     For example, the oil may be stored in a oil storage space formed by an inner surface of a base  112  of the container  110 . The oil may be pumped from the oil storage space and supplied to the compression device through an oil flow path  143 a formed inside the rotating shaft  143 . The oil feeder  180 , provided at a lower end portion of the oil flow path  143 a, may rotate with the rotating shaft  143  to pump the oil from the oil storage space into the oil flow path  143 a. The pumped oil may then be supplied to the compression device positioned at an upper portion of the oil flow path  143 a. 
     To ensure that the oil is supplied to the oil feeder  180 , oil should be maintained at an appropriate level. As discussed previously, the oil level may vary during operation of the compressor. The variation of oil level may be an absolute variation, which may be caused by a loss of oil, for example, by leakage of oil, or a temporary variation, which may be caused during operation of the compressor. For example, the oil level may temporarily increase or decrease during operation according to a change in an operational speed of the compressor. Accordingly, the oil level should be maintained at an appropriate level to account for both absolute and temporary variations to ensure normal operation of the compressor. 
     An oil level detecting device that detects the oil level in real time may include a detector  200 , provided in the container  110 , and a controller  250 . The controller  250  may monitor the oil level using measurements obtained from the detector  200 . The controller  250  may be provided on an outer wall of the container  110 . Alternatively, the controller  250  may be provided at a remote location, for example, in a management facility or control room. 
     The detector  200  may include a pair of electrodes  210  that may protrude into the container  110 . A supporting plate  220  may be provided to support the electrodes  210  and allow it to pass through the case  110  into the compressor. The supporting plate  220  may be inserted into a mounting hole  114  formed through the container  110  and may be attached thereto by, for example, welding or another appropriate method. The supporting plate  220  may be attached to the case  110  such that the supporting plate  220  is flush with an outer surface of the case  110 . Further, the supporting plate  220  may include a flange  222  that protrudes from an outer circumference of the supporting plate  220 . A flange seating portion  116  having a diameter greater than the mounting hole  114  may be formed at an outer circumference of the mounting hole  114 . The flange  222  may then be seated on the flange seating portion  116  and may be, for example, welded to the case. 
     Referring to  FIG. 2 , the detector  200  may include a pair of electrode plates  210  disposed inside the container  110 . The electrode plates  210  may extend into the oil storage space such that variation in oil levels may be detected by the electrode plates  210 . The electrode plates  210  may be mounted to an interior side wall of the container by being connected to the supporting plate  220 . 
     Each of the electrode plates  210  may include a conductive plate  212 , which may be formed of a conductive material, and a pin  214 , which may be formed to be integral with the conductive plate  212 . As shown in  FIG. 2 , the pins  214  may have a width that is smaller than a width of the conductive plates  212 . The pair of conductive plates  212  may be disposed to be adjacent to each other having a predescribed spacing therebetween. Thus, the pair of conductive plates  212  may serve as a capacitor having a capacitance that may vary according to variations in the oil level. For example, the capacitance between the electrode plates  210  may be a predetermined value when the oil level is below the electrode plates  210 . As the oil level rises to contact the electrode plates  210 , the presence of the oil may vary the capacitance of the electrode plates  210 . Accordingly, each of the electrode plates  210  may be disposed at appropriate positions corresponding to an upper and lower limit of the oil level. The incremental changes in the capacitance may then be monitored to detect whether the oil level is outside an acceptable range. 
     Simply for ease of explanation, the conductive plate  212  and pin  214  of the electrode plate  210  have been described as being integrally formed. In another embodiment, as illustrated in  FIG. 3 , a conductive plate  212 ′ and a pin  214 ′ may be individually molded, then bonded to each other using a method, such as, for example welding, or another appropriate method. Moreover, the electrode plates  210  may be formed such that the conductive plate  212  and the pin  214  are the same width. In such a case, the conductive plate  212  and the pin  214  may be formed such that they are integrally formed as a single piece or as separate parts that are bonded together. 
       FIG. 4  is a perspective view of a controller including a signal processor to an embodiment. The controller  250  of  FIG. 4  may be connected to the detector  200 . The controller  250  may be electrically connected to the detector  200  by a connector  240 . The connector  240  may be attached to lead wires  230 , which may be connected to pins  214  of the detector  200 . A printed circuit board including a signal processor may be provided in the controller  250 . The controller  250  may also include two LEDs  252 ,  254  provided on an outer surface thereof. 
     The LEDs  252 ,  254  may serve as a display to visually display the detected oil level. More specifically, the LED  252  may indicate that the oil level is in a normal condition, and the LED  254  may indicate that the oil level is not in a normal condition. Each LED may have a different color, thereby allowing the user to easily recognize the oil level visually. 
       FIG. 5  is a circuit diagram of the signal processor of  FIG. 4  according to an embodiment. The signal processor  500  of  FIG. 5  may be provided in a printed circuit board. The signal processor  500  may include a microcomputer  260  connected to the detector  200  that receives a capacitance value from the detector  200  for comparison to a reference property of an electric element. 
     The microcomputer  260  may be provided with six terminals. DC voltage (VDD) may be applied to a first terminal, and a noise filter may be connected to a second terminal. Further, the detector  200  may be connected to a third terminal, and an electric element, for example, a reference capacitor  264  having a predetermined capacitance, may be connected to a fourth terminal. The capacitance of the reference capacitor  264  may be the same as the capacitance of the detecting portion  210  (electrode plates) of the detector  200  when the oil level is in a normal condition. The microcomputer  260  may check the oil level by using a measured capacitance of the detecting portion  210  as an input value, and using the capacitance of the reference capacitor  264  as a reference value for comparison to the measured value. 
     A fifth terminal of the microcomputer  260  may be grounded, and a sixth terminal may be an output terminal. The output terminal may be connected to a third terminal of a three-pin header  262  corresponding to an output terminal provided on the controller  250 . A second terminal of the three-pin header  262  may be grounded, and the first terminal may be connected to a DC voltage (VDD). In addition, the three-pin header  262  may be connected to the controller  250  to provide information about the oil level. 
     The compressor as illustrated in  FIG. 1  may be implemented in an air conditioning system having a plurality of compressors and indoor units. Examples of an air conditioner having a plurality of compressors and methods of controlling the same are disclosed in co-pending application Ser. No. 12/958,915, now abandoned, which is hereby incorporated by reference. 
     Referring to  FIG. 6 , the air conditioner may include two compressors  101 ,  102 , three indoor heat exchangers  300 ,  310 ,  320 , expansion valves  302 ,  312 ,  322  connected to the indoor heat exchangers, respectively, an outdoor heat exchanger  330 , a 4-way valve  340 , and an accumulator  350  that supplies refrigerant to each of the compressors  101 ,  102 . Each of the compressors  101 ,  102  may be provided with the above discussed detector  200  and controller  250 . An indoor unit in an air conditioning system may include an indoor heat exchanger and an expansion valve to control the flow rate of working fluid to the indoor heat exchanger. The controller  250  may transmit control signals to a system controller  360  that controls the operation of the air conditioner. Further, the system controller  360  may control various valves or fans in addition to the other elements of the air conditioning system as illustrated in  FIG. 6 . 
     Hereinafter an operation of the signal processor  500  will be described. If the oil level is in a normal condition or within an acceptable range, then the capacitance of the detector  200  may be similar to the capacitance of the reference capacitor  264 . In this case, a voltage similar to the DC voltage (VDD) may be output through the sixth terminal, thus a voltage difference between the first and third terminals may become “0”. On the contrary, if the oil level is not in a normal condition or is outside an acceptable range, then the capacitance of the detector  200  may have deviated from the reference capacitor  264 . In this case, the voltage of the sixth terminal may become “0.” Accordingly, a voltage difference between the first and third terminals of the three-pin header  262  may correspond to VDD. The voltage difference output from the three-pin header  262  may be transmitted to the system controller  360  as a control signal. The system controller  360  may control the operation of the compressor or the indoor unit according to the received control signal. If it is determined that oil is not at an appropriate level, the system controller  360  may adjust the oil level to maintain an appropriate condition. For example, if the oil level is determined to be below a normal range, the controller  360  may implement an oil collecting operation to adjust the oil level. 
     Simply for ease of explanation, the values for voltages output at the sixth terminal have been described as being VDD when the oil level is within an acceptable range, and “0” when the oil level is outside the acceptable range. However, the voltage output at the sixth terminal is not limited to the foregoing values and may be configured to have an opposite value. For example, when the oil level is in a normal condition, the output voltage may become “0”, but otherwise it may become “VDD.” 
     Further, a voltage in proportion to a difference between the capacitance of the reference capacitor  264  and the capacitance of the detector  200  may be output at the sixth terminal. For example, it may be possible not only to merely check whether the oil level is in a normal condition, but also to check an amount in which the oil level is outside a normal condition or range, thereby allowing a more precise control of the oil levels. 
     Moreover, the microcomputer  260  may monitor the oil level in real time while simplifying the configuration of the oil level detecting device. For example, complicated processes, such as converting a value measured from the detecting portion to compare the value with a reference value recorded in memory, and the like, may be eliminated. 
     In addition, a property of a detecting portion used to detect the oil level may not be necessarily limited to a capacitance as described above, but any property that varies with respect to the oil level may be used. For example, in another embodiment the detecting portion may be configured such that a resistance value may vary with respect to the oil level. In this embodiment, an electronic element having a reference resistance value may be provided in the signal processor to be compared to a measured resistance value of the detecting portion. 
     In another embodiment, a plurality of electronic elements may be provided in the signal processor. In this embodiment, each of the plurality of electronic elements may be configured to correspond to a different oil level. Thus, a greater predetermined range of oil levels may be monitored. 
     According to an embodiment, there is provided an oil level detecting unit, which may be provided in a compressor including a compression unit that introduces and compresses a working fluid, a driving unit mechanically connected to the compression unit that operates the compression unit, and a case that accommodates the compression unit and driving unit thereinside and having an oil storage space to store oil at a lower portion thereof. The oil level detecting unit may include a detector including a supporting portion welded to the case and a detecting portion disposed to be protruded inside the case in which the property thereof varies according to the oil level, and a signal processor comprising an electronic element having a reference property that compares the property of the detecting portion with the reference property of the electronic element and output a control signal according to the result. 
     According to this embodiment, an oil level is not determined by converting a value measured by the detecting portion and comparing the value with a numerical value recorded in the storage means, such as a memory, but rather, the detecting portion may be configured to have a property that varies according to the oil level, and the signal processor may include an electronic element having the property corresponding to the property of the detecting portion when the oil level inside the case is at a specific level, for example, at a desirable level, and thus, the two properties, the property of the detecting portion and the property of the electronic element, may be directly compared to each other without having an additional conversion process, thereby simplifying the configuration of a signal processor. 
     Further, a plurality of electronic elements may be provided therein, and the property of each electronic element may correspond to a specific oil level inside the compressor. Accordingly, it may be possible to check whether the oil level is positioned within a specific range. 
     Moreover, the property may be an arbitrary value that an electronic element may have, or the property may be any physical property, such as a resistance or capacitance. In one embodiment, the detecting portion may have a capacitance that varies according to the oil level, and the electronic element may be a capacitor having a capacitance corresponding to a reference value. On the other hand, the detecting portion may include a pair of electrode plates that extends to an inside of the oil storage space, and in this case, a capacitance of the detecting portion may be changed according to the amount of oil existing between the electrode plates. In addition, the oil level detecting unit may further include a display operated by a control signal of the signal processor to visually or acoustically indicate the oil level. 
     Further, the supporting portion may include a supporting plate welded inside a mounting hole formed at a wall surface of the case, and the detecting portion may include a pair of electrode plates connected to the supporting plate. A flange may be formed at an outer circumference of the supporting portion, and a flange seating portion, on which the flange may be contacted, may be formed at an outer circumference of the mounting hole. In other words, the flange may be seated on a flange seating portion positioned at an outer circumference of the mounting hole to be maintained at the desired position, thereby facilitating the mounting process. The supporting plate may be made of a metallic material, and the supporting plate and the electrode may be combined with each other by interposing an insulation material therebetween. 
     The electrode plate may include a conductive plate positioned at an inside of the oil storage space and a pin that extends from the conductive plate by penetrating the supporting portion. Further, the display may include a light emitter that emits different colors according to a control signal output from the signal processor. 
     According to another embodiment, there is provided an air conditioner, including one or more compressors that may include a compression unit that introduces and compresses a working fluid, a driving unit mechanically connected to the compression unit that operates the compression unit, a case that accommodates the compression unit and driving unit thereinside and having an oil storage space to store oil at a lower portion thereof, and an oil level detecting unit fixed to the case; an indoor unit that performs cooling or heating using refrigerant discharged from the compressor; and a controller that controls the operation of the compressor and the indoor unit. The detector oil level detecting unit may include a detector including a supporting portion welded to the case and a detecting portion disposed to protrude inside the case in which the property thereof varies according to the oil level; and a signal processor including an electronic element having a reference property, that compares the property of the detecting portion with the reference property of the electronic element and outputs a control signal according to the result. The controller may control the operation of the compressor or the indoor unit according to a control signal transmitted from the signal processor, to control the oil level to be in an appropriate condition. The indoor unit may be defined to have a indoor heat exchanger and an expansion valve. 
     According to this embodiment, the oil level may be checked in real time by comparing the property of the detecting portion with the property of the electronic element as a reference value, and thus, the configuration of the signal processor may be simplified, thereby reducing the unit cost of the product, as well as enhancing reliability. 
     According to another embodiment, an oil level detecting device may be provided in a compressor. The compressor may include a compression device that introduces and compresses a working fluid, a drive device mechanically connected to the compression device that operates the compression device, and a case that accommodates the compression device and the driving device thereinside and having an oil storage space that stores oil at a lower portion thereof. The oil level detecting device may include a detector including a supporting portion configured to be attached to the case of the compressor and a detecting portion that protrudes inside the case, wherein at least one property of the detecting portion may vary according to an oil level inside the case, and a signal processor including an electronic element having at least one reference property, that compares the at least one property of the detecting portion with the at least one reference property of the electronic element and outputs a control signal according to the result. 
     The supporting portion may be welded to the case of the compressor. Further, a surface of the supporting portion may be flush with an outer surface of the case. Furthermore, the at least one property of the detecting portion may be a capacitance of the detecting portion, which may vary according to the oil level, and the electronic element may be a capacitor and the at least one reference property may include a predetermined capacitance of the electronic element. The predetermined capacitance of the capacitor may be the same as the capacitance of the detecting portion when the oil level inside the case is in an appropriate condition. Alternatively, when the oil level inside the case is in an appropriate condition, the capacitance of the detecting portion may be within a predetermined range of the predetermined capacitance of the capacitor. 
     The detecting portion may include a pair of electrode plates that extends into an inside of the oil storage space. Further, the pair of electrode plates may extend perpendicular to an inner wall of the case. 
     The oil level detecting device of this embodiment may further include a display operated by a control signal of the signal processor that visually or acoustically displays the oil level. The display may include a light emitter that emits different colors according to a control signal output from the signal processor. 
     The supporting portion may include a supporting plate welded inside a mounting hole formed at a wall surface of the case, and the detecting portion may include a pair of electrode plates connected to the supporting plate. A flange may be formed at an outer circumference of the supporting portion, and a flange seating portion, on which the flange may be positioned, may be formed at an outer circumference of the mounting hole. Each of the plurality of electrode plates may include a conductive plate positioned at an inside of the oil storage space, and a pin that extends from the conductive plate to the supporting portion. The pins of the plurality of electrode plates may extend perpendicular to a wall surface of the case. Further, the conductive plates of the plurality of electrode plates may extend perpendicular to a wall surface of the case. The pin may be formed integral with the conductive plate, and the conductive plate may be formed wider than the pin. 
     According to another embodiment, an air conditioner may be provided which may include a plurality of compressors including a compression device that introduces and compresses a working fluid, a driving device mechanically connected to the compression device that operates the compression device, a case that accommodates the compression device and the driving device thereinside and having an oil storage space that stores oil at a lower portion thereof, and an oil level detecting device fixed to the case; an indoor device that performs cooling or heating using refrigerant discharged from the plurality of compressors, the indoor device comprising an indoor heat exchanger and an expansion valve; and a controller that controls an operation of the plurality of compressors or the indoor device. The oil level detecting device may include a detector including a supporting portion configured to be attached to the case and a detecting portion that protrudes inside the case, wherein at least one property of the detecting portion may vary according to an oil level within the case; and a signal processor including an electronic element having at least one reference property, the signal processor comparing the at least one property of the detecting portion with the at least one reference property of the electronic element and outputting a control signal according to the result. The controller may control the operation of the plurality of compressors or the indoor device according to the control signal transmitted from the signal processor to control the oil level inside the case to be in an appropriate condition. 
     Any reference in this specification to “one embodiment,” “an embodiment,” “example embodiment,” etc., means particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with any embodiment, it is submitted that it is within the purview of one skilled in the art to effect such feature, structure, or characteristic in connection with other ones of the embodiments. 
     Although embodiments have been described with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this disclosure. More particularly, various variations and modifications are possible in the component parts and/or arrangements of the subject combination arrangement within the scope of the disclosure, the drawings and the appended claims. In addition to variations and modifications in the component parts and/or arrangements, alternative uses will also be apparent to those skilled in the art.