Patent Publication Number: US-9429158-B2

Title: Air conditioner and compressor having power and saving modes of operation

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS 
     This application is a U.S. National Stage Application under 35 U.S.C. §371 of PCT Application No. PCT/KR09/04059, filed Jul. 22, 2009, which claims priority to Korean Patent Application Nos. 10-2008-0071197 and 10-2008-0071199, both filed Jul. 22, 2008. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a compressor and an air-conditioner having the same and, more particularly, to a compressor capable of enhancing an operation efficiency in an area where an operational environment is abnormal and an air-conditioner having the air-conditioner. 
     2. Description of the Related Art 
     In general, a compressor is applied to an air-conditioner. Recently, as the functions of air-conditioners and the like are diversified, a compressor whose capacity can be changed is on demand. As a technique for varying the capacity of the compressor, a technique for controlling the number of rotations of the compressor by employing an inverter motor and a technique for mechanically controlling a vane to idly rotate it are widely known. 
     First, the technique employing the inverter motor has a problem in that because the inverter motor is costly, the burden of a unit cost is high, and it is difficult to increase a freezing capability in a cooling condition compared with an increase in a freezing capability in a heating condition. 
     Meanwhile, the technique for idly rotating the vane by mechanically controlling it includes two types of methods: The first is constraining and releasing the vane by varying the pressure of a refrigerant supplied to a compression space of a cylinder; and the second is constraining and releasing the vane while changing the pressure applied to a rear surface of the vane. 
     In the case of the compressor, in an area where a voltage situation is not good, a low voltage is frequently generated, and in this occurrence, motive power of the compressor is insufficient to stop the compressor. Namely, during a certain time domain during which power of the compressor is turned off, refrigerant is not compressed, failing to obtain a cooling effect to make it difficult to realize an agreeable cooling operation. If an ambient temperature is high, the compressor is stopped, so the refrigerating is not compressed during a certain time domain while power of the compressor is turned off, failing to obtain a cooling effect to make it difficult to realize an agreeable cooling operation. Because the compressor is repeatedly turned on and off, power consumption increases and the reliability is degraded. 
     In addition, when a discharge temperature of the compressor refrigerator is high, power of the compressor is cut off by an electric overload protection (OLP) device or a temperature sensor to thus protect the compressor. In addition, when an ambient temperature is high, the same operation is performed. In particular, in an area, such as a tropical region, in which an ambient temperature is considerably high, such operation is frequently performed. If such operation is frequently performed, the refrigerant is not compressed during a certain time domain, failing to obtain a cooling effect to make it difficult to realize an agreeable cooling operation. Also, because the compressor is repeatedly turned on and off, power consumption increases and the reliability is degraded. 
     In addition, with the excessively high ambient temperature, the compressor is continuously operated in a power mode, excessive cooling operation is performed even at night, failing to provide an agreeable cooling operation and causing big noise. 
     SUMMARY OF THE INVENTION 
     Therefore, in order to address the above matters, the various features described herein have been conceived. 
     An aspect of the present invention provides a compressor and an air-conditioner, having the compressor, operated in a pre-set operation mode or operated based on a detected compressor application voltage or operated in a pre-set operation mode during a certain time domain to continuously operate the compressor, thus improving the reliability and operation efficiency of the compressor and the air-conditioner and reducing noise. 
     Another aspect of the present invention provides a compressor and an air-conditioner, having the compressor, operated in a pre-set operation mode by detecting a compressor temperature or an ambient temperature, thereby improving the reliability and operation efficiency of the compressor and the air-conditioner and reducing noise. 
     Another aspect of the present invention provides a compressor and an air-conditioner, having the compressor, operated in a pre-set operation mode by detecting a compressor or an ambient temperature or operated in a pre-set operation mode during a certain time domain to continuously operate the compressor, thus improving the reliability and operation efficiency of the compressor and the air-conditioner and reducing noise. 
     According to an aspect of the present invention, there is provided a compressor including: a casing having a hermetically closed internal space; a driving motor installed in the internal space of the casing and generating a driving force; and a compression unit installed along with the driving motor in the internal space of the casing, having at least two or more compression spaces, and controlled to be operated in a power mode or in a saving mode in which the compression unit is idly rotated in at least one compression space, according to a compressor application voltage. Here, if the application voltage is lower than a reference voltage, the compression unit controls the compressor to be operated in the saving mode, and when the application voltage is equal to or higher than the reference voltage, the compression unit controls the compressor to be operated in the power mode. 
     According to another aspect of the present invention, there is provided a compressor including: a casing having a hermetically closed internal space; a driving motor installed in the internal space of the casing and generating a driving force; and a compression unit installed along with the driving motor in the internal space of the casing, having at least two or more compression spaces, and controlled to be operated in a power mode or in a saving mode in which the compression unit is idly rotated in at least one compression space, according to the difference between actually measured temperatures of refrigerants discharged from the compression spaces. Here, when the actually measured temperature is lower than a first reference temperature, the compression unit is changed to the saving mode, when the actually measured temperature is equal to or higher than the first reference temperature but lower than a second reference temperature, the compression unit is changed to the power mode, and when the actually measured temperatures is equal to or higher than the second reference temperature, the compression unit is changed to the saving mode. 
     The compression unit may be changed to one of the operation modes, e.g., to the saving mode, during a particular time domain of a pre-set time domain. Here, the time domain may be set based on, for example, an average temperature. 
     The compression unit may be idly rotated by using a refrigerant sucked to a suction opening of the compression unit and a refrigerant filled in the internal space of the casing. 
     According to another aspect of the present invention, there is provided an air-conditioner including: a compressor having a power mode in which the compressor is operated with a maximum compression capacity and a saving mode in which the compressor is operated with a smaller compression capacity than in the power mode; a detection unit configured to detect a compressor application voltage for determining an operation mode of the compressor; and a control unit configured to change an operation mode of the compressor by comparing an application voltage detected by the detection unit to a pre-set reference voltage. Here, when the application voltage is lower than the reference voltage, the control unit may control the compressor to be operated in the saving mode. 
     The control unit may control the operation mode of the compressor by comparing the application voltage detected by the detection unit and the reference voltage according to an application voltage detection period. If the application voltage is higher than a first reference voltage, the control unit may control the compressor to be operated in the power mode. If the application voltage ranges from a second voltage to the first reference voltage, the control unit may control the compressor to be operated in the saving mode. If the application voltage is lower than the second reference voltage, the control unit may control the compressor to be stopped. 
     According to another aspect of the present invention, there is provided an air-conditioner including: a compressor having a power mode in which the compressor is operated with a maximum compression capacity and a saving mode in which the compressor is operated with a smaller compression capacity than in the power mode; a detection unit configured to detect a compressor application voltage for determining an operation mode of the compressor; a control unit configured to change an operation mode of the compressor by comparing an application voltage detected by the detection unit to a pre-set reference voltage; and a temperature detection unit configured to detect an actually measured temperature for determining an operation mode of the compressor. Here, if the application voltage is higher than a first reference voltage, the control unit may control the operation mode of the compressor by comparing the actually measured temperature which has been detected by the temperature detection unit and a pre-set reference temperature according to an actually measured temperature detection period. 
     According to another aspect of the present invention, there is provided an air-conditioner including: a compressor having a power mode in which the compressor is operated with a maximum compression capacity and a saving mode in which the compressor is operated with a smaller compression capacity than in the power mode; a temperature detection unit configured to detect an actually measured temperature for determining an operation mode of the compressor; and a control unit for changing the operation mode of the compressor by comparing the actually measured temperature which has been detected by the temperature detection unit to a pre-set reference temperature. Here, if the actually measured temperature is higher than an upper limit of a temperature range corresponding to the power mode domain, the control unit may control the compressor to be operated in the saving mode. 
     Here, the control unit may control the operation mode of the compressor by comparing the actually measured temperature which has been detected by the temperature detection unit and the pre-set reference temperature according to the actually measured temperature detection period. If the actually measured temperature is lower than a first reference temperature, the control unit may control the compressor to be operated in the saving mode. If the actually measured temperature is equal to or higher than the first reference temperature but lower than the second reference temperature, the control unit may control the compressor to be operated in the power mode. If the actually measured temperature is equal to or higher than the second reference temperature, the control unit may control the compressor to be operated in the saving mode. 
     According to another aspect of the present invention, there is provided an air-conditioner including: a compressor having a power mode in which the compressor is operated with a maximum compression capacity and a saving mode in which the compressor is operated with a smaller compression capacity than in the power mode; and a control unit configured to change an operation mode of the compressor according to each of pre-set time domains, wherein the control unit controls the compressor to be operated in the saving mode in a particular time domain of the time domains. Here, the time domains may be set based on, for example, an average temperature. 
     The air-conditioner may further include: a temperature detection unit configured to detect an actually measured temperature for determining an operation mode of the compressor. The control unit compares the actually measured temperature which has been detected by the temperature detection unit to a pre-set reference temperature, and if the actually measured temperature is higher than an upper limit of a temperature range corresponding to the power mode domain, the control unit may control the compressor to be operated in the saving mode. If the actually measured temperature is lower than a first reference temperature, the control unit may control the compressor to be operated in the saving mode. When the actually measured temperature ranges from the first reference temperature to a second reference temperature, the control unit may control the compressor to be operated in the power mode. When the actually measured temperature is higher than the second reference temperature, the control unit may control the compressor to be operated in the saving mode. 
     Here, the temperature detection unit may be installed at a discharge side of the compressor to detect the temperature of a refrigerator discharged from the compressor, or may be installed in an air-conditioned room to detect an indoor temperature. 
     The compressor and air-conditioner having the same according to exemplary embodiments of the present invention have many advantages. 
     That is, first, because the compressor is prevented from being interrupted due to a low voltage, power consumption can be reduced and an agreeable cooling operation can be provided. 
     Second, because power of the compressor is not repeatedly turned on or off, power consumption can be reduced and reliability can be improved. 
     Third, because the compressor is operated in a particular operation mode during a certain time slot regardless of an ambient temperature, an excessive cooling is not performed especially at a night time, providing an agreeable cooling operation and reducing noise. 
     The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic block diagram showing a system configuration to explain an air-conditioner according to a first exemplary embodiment of the present invention; 
         FIG. 2  is a schematic block diagram showing a system configuration to explain an air-conditioner according to a second exemplary embodiment of the present invention; 
         FIG. 3  is a graph showing a change in a compressor operation mode in  FIG. 1 or 2 ; 
         FIG. 4  is a schematic block diagram showing a system configuration to explain an air-conditioner according to a third or fourth exemplary embodiment of the present invention; 
         FIG. 5  is a graph showing a change in a compressor operation mode in  FIG. 4 ; 
         FIG. 6  is a perspective view showing the configuration of a compressor according to first to sixth exemplary embodiments of the present invention; and 
         FIG. 7  is a vertical-sectional view showing the configuration of a compressor according to an exemplary embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A compressor and an air-conditioner having the compressor according to exemplary embodiments of the present invention will now be described with reference to the accompanying drawings. 
     With reference to  FIG. 1 , the air-conditioner according to a first exemplary embodiment of the present invention includes a compressor  10  having a power mode in which the compressor  10  operates with a maximum compression capacity and a saving mode in which the compressor  10  operates with a smaller compression capacity than in the power mode; a detection unit  30  configured to detect a compressor application voltage for determining an operation mode of the compressor  10 ; and a control unit  20  configured to change an operation mode of the compressor  10  by comparing an application voltage detected by the detection unit  30  to a pre-set reference voltage. In addition, the air-conditioner further includes an outdoor unit  40  for controlling distribution and circulation of a refrigerant, and an indoor unit  50  shared by the outdoor unit  40  and discharging air to each room. When the application voltage is lower than the reference voltage, the control unit controls the compressor to be operated in the saving mode. Here, the reference voltage is a pre-set voltage value, at which the compressor is not stopped when a low voltage not within a compressor driving available voltage range occurs or when such a low voltage that may cause a trouble to driving of the compressor although it is within the compressor driving available voltage range. For example, if the voltage of a commercial power source is 220V and the compressor driving available voltage range ranges 187V to 253V, the reference voltage may be set as 200V and, in this case, if a voltage lower than 200V is applied as a compressor application voltage, the compressor is operated in the saving mode. For another example, when the compressor is operated in the saving mode, a voltage lower than that used for operating the compressor in the power mode is required. Thus, the reference voltage may be set as 180V by extending the compressor driving available voltage range, and if a lower voltage than the reference voltage occurs, the compressor may be operated in the saving mode. 
     The power mode is a compressor operation mode in which the compressor is operated with a maximum compression capacity, and the saving mode is a compressor operation mode in which the compressor is operated with a compression capacity ranging from 0 to 100% of the compression capacity of the power mode. 20%, 40%, 60% and 80% of the maximum compression capacity may be set for the saving mode, according to which the compressor may be operated, and most commonly, the compression capacity is set to be 50% to operate the compressor. This is called a two-stage mode. 
     The present invention is based on the two-stage mode of the power mode and the saving mode, for which every electrical or mechanical means dividing the two modes may be used. 
     In the air-conditioner according to the first exemplary embodiment of the present invention, the control unit  20  controls the operation mode of the compressor  10  by comparing an application voltage detected by the detection unit  30  and the reference voltage according to an application voltage detection period. Here, an actually measured temperature detection period refers to a period at which an actually measured temperature is compared with a pre-set reference temperature in real time whenever it occurs. 
     In the air-conditioner according to the first exemplary embodiment of the present invention, if the application voltage is higher than a first reference voltage, the control unit  20  controls the compressor  10  to be operated in the power mode. If the application voltage ranges from the first reference voltage to a second reference voltage, the control unit  20  controls the compressor  10  to be operated in the saving mode. If the application voltage is lower than the second reference voltage, the control unit  20  controls the compressor  10  to be stopped. Here, the first and second reference voltages are voltage values set by previously measuring voltages at which the compressor  10  can be driven according to the operation mode of the compressor  10 . 
     In the air-conditioner according to the first exemplary embodiment of the present invention, one or more time domains are set, and the control unit  20  provides control to change the operation mode of the compressor according to each time domain. During a particular time domain of the time domains, the control unit  20  controls the compressor to be operated in the saving mode. 
     With reference to  FIG. 2 , an air-conditioner according to a second exemplary embodiment of the present invention includes: the compressor  10  having a power mode in which the compressor  10  operates with a maximum compression capacity and a saving mode in which the compressor  10  operates with a smaller compression capacity than in the power mode; the detection unit  30  configured to detect a compressor application voltage for determining an operation mode of the compressor; the control unit  20  configured to change an operation mode of the compressor by comparing an application voltage detected by the detection unit  30  to a pre-set reference voltage; and a temperature detection unit  60  configured to detect an actually measured temperature for determining an operation mode of the compressor. The air-conditioner further includes: the outdoor unit  40  for controlling distribution and circulation of a refrigerant, and the indoor unit  50  shared by the outdoor unit  40  and discharging air to each room. Here, if the application voltage is lower than the reference voltage, the control unit  20  controls the compressor to be operated in the saving mode. The same content as description with respect to  FIG. 1  will be replaced by the description with respect to  FIG. 1 . 
     In the air-conditioner according to the second exemplary embodiment of the present invention, if the application voltage is higher than the reference voltage, namely, the application voltage is a normal voltage, an actually measured temperature is detected by the temperature detection unit  60  and determines an operation mode of the compressor  10  based on the actually measured temperature. The control unit  20  controls the operation mode of the compressor  10  by comparing the actually measured temperature detected by the temperature detection unit  60  and the pre-set reference temperature according to the actually measured temperature detection period. Here, the actually measured temperature detection period refers to a period at which the actually measured temperature is compared with the pre-set reference temperature in real time whenever the actually measured temperature detected. In addition, the reference temperature is a value set to be lower than a limit temperature of an overload protection device as installed, which is used to prevent the compressor from being stopped by the overload protection device. The temperature detection unit  60  may have the function of the overload protection device or may be installed separately from the overload protection device. 
     In the air-conditioner according to the second exemplary embodiment of the present invention, if the actually measured temperature is lower than a first reference temperature, the control unit  20  controls the compressor to be operated in the saving mode. If the actually measured temperature ranges from the first reference temperature to a second reference temperature, the control unit  20  controls the compressor to be operated in the power mode. If the actually measured temperature is higher than the second reference temperature, the control unit controls the compressor to be operated in the saving mode. Here, the first reference temperature is a reference temperature value used for discriminating the saving mode and the power mode. The temperature range from the first reference temperature to the second reference temperature corresponds to a power mode domain. The second reference temperature is an upper limit temperature value of the temperature range corresponding to the power mode domain set to be lower than the limit temperature of the overload protection device in order to prevent the compressor from being stopped. 
     Here, the temperature detection unit  60  may be installed at a discharge side of the compressor to detect the temperature of a refrigerant discharged from the compressor, or may be installed in an air-conditioned room to detect an indoor temperature. 
       FIG. 3  is a graph showing a change in the compressor operation mode according to a first or second exemplary embodiment of the present invention. As shown in  FIG. 3 , time is divided into morning time, daytime, nighttime slots, and the operation modes include two modes: the power mode and the saving mode. 
     First, when the user turns on power of the compressor, sets a desired temperature and drives the air-conditioner, the compressor is operated in the power mode so as to be driven to make an indoor temperature reach a user desired temperature. In addition, in a state that a certain temperature is previously set, if the temperature is lower than the pre-set certain temperature, the compressor is operated in the saving mode, whereas if the temperature is higher than the pre-set certain temperature, the compressor is operated in the power mode. Here, with the air-conditioner according to an exemplary embodiment of the present invention, for example, as shown in the morning time slot in  FIG. 3 , if a detected compressor application voltage is lower than the reference voltage, namely, if the compressor application voltage is low, the operation mode of the compressor is changed to the saving mode, in which the compressor can be operated even at the low voltage, so as to be driven the compressor at the low voltage without being stopped. 
     In the related art air-conditioner operation method, the operation of the compressor is stopped at a daytime slot during which an average temperature is high because an ambient temperature exceeds the limit temperature of the overload protection device. When the compressor is driven again by applying power thereto, because the ambient temperature exceeds again the limit temperature of the overload protection device, stopping the operation of the compressor. In a tropical area, in particular, during a daytime slot during which an average temperature is high, power of the compressor is repeatedly turned on or off, failing to provide an agreeable cooling operation and increase power consumption. 
     In comparison, according to the air-conditioner operation method according to an exemplary embodiment of the present invention, because the reference temperature is set to be lower than the limit value of the overload protection device and set for the upper limit of the temperature range of the power mode domain, and when an actually measured temperature is higher than the reference temperature, the compressor is forcibly changed to the saving mode and operated, thereby reducing power consumption and noise according to operation of the compressor such as a compressor operation noise and the like. 
     In an area where an ambient temperature is high, the high temperature is still maintained at an evening time (or nighttime) slot, so the compressor tends to be operated in the power mode. However, in the air-conditioner according to an exemplary embodiment of the present invention, a particular time domain is set, so that the compressor is operated in the particular operation mode. That is, for example, the compressor is operated in the saving mode during the nighttime slot, rather than being continuously operated in the power mode, thus preventing an excessive cooling operation and reducing noise. 
       FIG. 4  is a schematic block diagram showing a system configuration to explain an air-conditioner according to a third or fourth exemplary embodiment of the present invention. 
     With reference to  FIG. 4 , an air-conditioner according to the third exemplary embodiment of the present invention includes the compressor  10  having a power mode in which the compressor  10  is operated with a maximum compression capacity and a saving mode in which the compressor  10  is operated with a smaller compression capacity than in the power mode; the temperature detection unit  60  configured to detect an actually measured temperature for determining an operation mode of the compressor  10 ; and the control unit  20  for changing the operation mode of the compressor by comparing the actually measured temperature which has been detected by the temperature detection unit to a pre-set reference temperature. In addition, the air-conditioner further includes an outdoor unit  40  for controlling distribution and circulation of a refrigerant, and an indoor unit  50  shared by the outdoor unit  40  and discharging air to each room. Here, if the actually measured temperature is higher than an upper limit of a temperature range corresponding to the power mode domain, the control unit may control the compressor to be operated in the saving mode. Here, the temperature range is a pre-set value. A reference temperature used for discriminating the power mode and the saving mode is a lower limit of the temperature range corresponding to the power mode domain, and one of temperature values higher than the lower limit is set to be an upper limit of the temperature range. If the actually measured temperature is higher than the upper limit of the temperature range, the control unit is forcibly changed to the saving mode. 
     The power mode is a compressor operation mode in which the compressor is operated with a maximum compression capacity, and the saving mode is a compressor operation mode in which the compressor is operated with a compression capacity ranging from 0 to 100% of the compression capacity of the power mode. 20%, 40%, 60% and 80% of the maximum compression capacity may be set for the saving mode, according to which the compressor may be operated, and most commonly, the compression capacity is set to be 50% to operate the compressor. This is called a two-stage mode. 
     The present invention is based on the two-stage mode of the power mode and the saving mode, for which every electrical or mechanical means dividing the two modes may be used. 
     In the general air-conditioner operation method, a saving mode operation and a power mode operation are divided based on a pre-set reference temperature. If a current temperature is lower than the pre-set reference temperature, the compressor is operated in the saving mode, whereas if the current temperature is higher than the pre-set reference temperature, the compressor is operated in the power mode. Over this operation method, an overload protection (OLP) device is commonly installed to protect the compressor provided in the air-conditioner, and in this case, if a compressor refrigerant discharge temperature exceeds the limit temperature of the overload protection device, the compressor is stopped to be protected. 
     Thus, the purpose of the present invention can be achieved by not exceeding the limit temperature of the overload protection device. Namely, in the air-conditioner according to the first exemplary embodiment of the present invention having the above-described configuration, the control unit controls the operation mode of the compressor by comparing the actually measured temperature detected by the temperature detection unit and the pre-set reference temperature according to the actually measured temperature detection period. Here, the actually measured temperature detection period refers to a period at which the actually measured temperature is compared with the pre-set reference temperature in real time whenever the actually measured temperature detected. In addition, the reference temperature is a value set to be lower than the limit temperature of the overload protection device as installed, which is used to prevent the compressor from being stopped by the overload protection device. The temperature detection unit may have the function of the overload protection device or may be installed separately from the overload protection device. 
     In the air-conditioner according to the third exemplary embodiment of the present invention, if the actually measured temperature is lower than a first reference temperature, the control unit  20  controls the compressor to be operated in the saving mode. If the actually measured temperature ranges from the first reference temperature to a second reference temperature, the control unit  20  controls the compressor to be operated in the power mode. If the actually measured temperature is higher than the second reference temperature, the control unit controls the compressor to be operated in the saving mode. Here, as described above with respect to the general air-conditioner operation method, the first reference temperature is a reference temperature value used for discriminating the saving mode and the power mode. The temperature range from the first reference temperature to the second reference temperature corresponds to a power mode domain. The second reference temperature is an upper limit temperature value of the temperature range corresponding to the power mode domain set to be lower than the limit temperature of the overload protection device in order to prevent the compressor from being stopped. 
     In the air-conditioner according to the third exemplary embodiment of the present invention, the temperature detection unit  60  may be installed at a discharge side of the compressor to detect the temperature of a refrigerant discharged from the compressor, or may be installed in an air-conditioned room to detect an indoor temperature. 
     The air-conditioner according to a fourth exemplary embodiment of the present invention will now be described with reference to  FIG. 4 . 
     The air-conditioner according to the fourth exemplary embodiment of the present invention includes: the compressor  10  having a power mode in which the compressor  10  is operated with a maximum compression capacity and a saving mode in which the compressor  10  is operated with a smaller compression capacity than in the power mode; and the control unit  20  configured to change an operation mode of the compressor according to each of pre-set time domains. The control unit  20  controls the compressor to be operated in the saving mode in a particular time domain of the time domains. 
     The air-conditioner according to the fourth exemplary embodiment of the present invention further includes: the temperature detection unit  60  configured to detect an actually measured temperature for determining an operation mode of the compressor. The control unit compares the actually measured temperature which has been detected by the temperature detection unit to a pre-set reference temperature, and if the actually measured temperature is higher than an upper limit of a temperature range corresponding to the power mode domain, the control unit may control the compressor to be operated in the saving mode. If the actually measured temperature is lower than a first reference temperature, the control unit may control the compressor to be operated in the saving mode. Here, the temperature range is a pre-set value. A reference temperature used for discriminating the power mode and the saving mode is a lower limit of the temperature range corresponding to the power mode domain, and one of temperature values higher than the lower limit is set to be an upper limit of the temperature range. If the actually measured temperature is higher than the upper limit of the temperature range, the control unit is forcibly changed to the saving mode. 
     Namely, in the air-conditioner according to the fourth exemplary embodiment of the present invention having the above-described configuration, the control unit controls the operation mode of the compressor by comparing the actually measured temperature detected by the temperature detection unit and the pre-set reference temperature according to the actually measured temperature detection period. Here, the actually measured temperature detection period refers to a period at which the actually measured temperature is compared with the pre-set reference temperature in real time whenever the actually measured temperature detected. In addition, the reference temperature is a value set to be lower than the limit temperature of the overload protection device as installed, which is used to prevent the compressor from being stopped by the overload protection device. The temperature detection unit may have the function of the overload protection device or may be installed separately from the overload protection device. 
     Also, in the air-conditioner according to the fourth exemplary embodiment of the present invention, if the actually measured temperature is lower than a first reference temperature, the control unit  20  controls the compressor to be operated in the saving mode. If the actually measured temperature ranges from the first reference temperature to a second reference temperature, the control unit  20  controls the compressor to be operated in the power mode. If the actually measured temperature is higher than the second reference temperature, the control unit controls the compressor to be operated in the saving mode. Here, as described above with respect to the general air-conditioner operation method, the first reference temperature is a reference temperature value used for discriminating the saving mode and the power mode. The temperature range from the first reference temperature to the second reference temperature corresponds to a power mode domain. The second reference temperature is an upper limit temperature value of the temperature range corresponding to the power mode domain set to be lower than the limit temperature of the overload protection device in order to prevent the compressor from being stopped. 
     Here, the time domain may be set based on a different reference such as 24 hours a day, etc., or may be set according to an average temperature. 
     In the air-conditioner according to the fourth exemplary embodiment of the present invention, the temperature detection unit  60  may be installed at a discharge side of the compressor to detect the temperature of a refrigerant discharged from the compressor, or may be installed in an air-conditioned room to detect an indoor temperature. 
       FIG. 5  is a graph showing a change in the compressor operation mode, in which time is divided into the morning, day, night time slots, and operation mode is divided into the power mode and the saving mode. 
     First, when the user turns on power of the compressor, sets a desired temperature and drives the air-conditioner, the compressor is operated in the power mode so as to be driven to make an indoor temperature reach a user desired temperature. In addition, in a state that a certain temperature is previously set, if the temperature is lower than the pre-set certain temperature, the compressor is operated in the saving mode, whereas if the temperature is higher than the pre-set certain temperature, the compressor is operated in the power mode. In this case, in an area, such as a tropical area, where an average temperature is high, it is difficult to set a certain temperature and temperature is maintained at higher than the set temperature, so the control unit is continuously operated in the power mode. In the air-conditioner according to an exemplary embodiment of the present invention, for example, as shown in a morning time domain slot in  FIG. 2 , a new reference temperature is set to be within a temperature range higher than the pre-set certain temperature and lower than the limit temperature of the overload protection device, and when temperatures goes up to be higher than the newly set reference temperature, the compressor is forcibly changed to the saving mode. Thus, because the compressor is not continuously operated in the power mode, power consumption can be reduced and noise can be also reduced. 
     In the related art air-conditioner operation method, the operation of the compressor is stopped at a daytime slot during which an average temperature is high because an ambient temperature exceeds the limit temperature of the overload protection device. When the compressor is driven again by applying power thereto, because the ambient temperature exceeds again the limit temperature of the overload protection device, stopping the operation of the compressor. In a tropical area, in particular, during a daytime slot during which an average temperature is high, power of the compressor is repeatedly turned on or off, failing to provide an agreeable cooling operation and increase power consumption. 
     In comparison, according to the air-conditioner operation method according to an exemplary embodiment of the present invention, because the reference temperature is set to be lower than the limit value of the overload protection device and set for the upper limit of the temperature range of the power mode domain, and when an actually measured temperature is higher than the reference temperature, the compressor is forcibly changed to the saving mode and operated, thereby reducing power consumption and noise according to operation of the compressor such as a compressor operation noise and the like. 
     In an area, such as a tropical area, where an average temperature is high especially at nighttime slot, the high temperature is still maintained at the nighttime slot, so the compressor tends to be operated in the power mode. However, in the air-conditioner according to an exemplary embodiment of the present invention, a particular time domain is set, so that the compressor is operated in the particular operation mode. That is, for example, the compressor is operated in the saving mode during the nighttime slot, rather than being continuously operated in the power mode, thus preventing an excessive cooling operation and reducing noise. 
     A compressor according to exemplary embodiments of the present invention will be described with reference to  FIG. 6 . 
     A compressor according to a first exemplary embodiment of the present invention includes a casing  100  having a hermetically closed internal space; a driving motor (not shown) installed in the internal space of the casing and generating a driving force; and a compression unit (not shown) installed along with the driving motor in the internal space of the casing, having at least two or more compression spaces, and controlled to be operated in a power mode or in a saving mode in which the compression unit is idly rotated in at least one compression space, according to a compressor application voltage. Here, if the application voltage is lower than a reference voltage, the compression unit controls the compressor to be operated in the saving mode, and when the application voltage is equal to or higher than the reference voltage, the compression unit controls the compressor to be operated in the power mode. Here, the reference voltage is a value previously set such that the compressor is prevented from being stopped due to a low voltage. 
     In the compressor according to the first exemplary embodiment of the present invention, when the application voltage is higher than the reference voltage, namely, when the application voltage is normal, and when the actually measured temperature is lower than a first reference temperature, the compression unit is changed to the saving mode. If the actually measured temperature ranges from the first reference temperature to a second reference temperature, the compression unit is changed to the power mode. If the actually measured temperature is higher than the second reference temperature, the compression unit is changed to the saving mode. Here, the first reference temperature is a reference temperature value used for discriminating the saving mode and the power mode. The temperature range from the first reference temperature to the second reference temperature corresponds to a power mode domain. The second reference temperature is an upper limit temperature value of the temperature range corresponding to the power mode domain set to be lower than the limit temperature of the overload protection device in order to prevent the compressor from being stopped. 
     The compressor  10  includes an accumulator  110  and a connection unit allowing a refrigerant to flow therethrough and connected to the outdoor unit  40  and the indoor unit  50 . The connection unit includes a low pressure side connection pipe  120 , a high pressure side connection pipe  130  connected with the internal space of the casing  100 , and a common use side connection pipe  140  alternately connected with the low pressure side connection pipe  120  and the high pressure side connection pipe  130 . 
     In the compressor according to the first exemplary embodiment of the present invention, the compression unit is changed to the saving mode during a particular time domain of a pre-set time domain. Here, the time domain may be set based on a different reference such as 24 hours a day, etc., or may be set according to an average temperature. A detailed description will be replaced by the description made above with reference to  FIG. 2 . 
     In the compressor according to the first exemplary embodiment of the present invention, the compression unit may be idly rotated by using a refrigerant sucked to a suction opening of the compression unit and a refrigerant filled in the internal space of the casing  100 . 
     A compressor according to a second exemplary embodiment of the present invention includes a casing  100  having a hermetically closed internal space, a driving motor (not shown) installed in the internal space of the casing and generating a driving force, a compression unit (not shown) installed along with the driving motor in the internal space of the casing, having at least two or more compression spaces, and controlled to be operated in a power mode or in a saving mode in which the compression unit is idly rotated in at least one compression space, according to a compressor application voltage, a plurality of cylinders each having a separated compression space and installed in the internal space of the casing  100 , a suction pipe for distributedly supplying a refrigerant to the compression spaces of the plurality of cylinders, a plurality of rolling pistons for compressing the refrigerant while making a rotating movement in the compression spaces of the cylinders, a plurality of vanes dividing the compression spaces of the cylinders into suction spaces and discharge spaces together with the rolling pistons, and a vain restraining unit for varying the operation mode of the compressor by restraining or releasing a vane of a cylinder among the vanes. Here, if the application voltage is lower than a reference voltage, the compression unit controls the compressor to be operated in the saving mode, and when the application voltage is equal to or higher than the reference voltage, the compression unit controls the compressor to be operated in the power mode. Here, the reference voltage is a value previously set such that the compressor is prevented from being stopped due to a low voltage. 
     Here, in the compressor, one side of at least one of the vanes has a sealing surface being in contact with the rolling piston, and the other side of the sealing surface has a pressure surface pressing the vane toward the rolling piston. 
     A chamber is formed at the pressure surface of the vane of one of the cylinders, which is separated from the internal space of the casing and filled with a refrigerator of suction pressure or discharge pressure. 
     The compressor further includes a mode conversion unit formed at an outer side of the casing to selectively provide the refrigerant of suction pressure or discharge pressure to the pressure surface of the vane. 
     In the compressor according to the second exemplary embodiment of the present invention, the mode conversion unit includes: a mode conversion valve for selecting the refrigerant of suction pressure or discharge pressure at the vane, a low pressure side connection pipe for connecting a first entrance of the mode conversion valve and a suction pipe, a high pressure side connection pipe for connecting a second entrance of the mode conversion valve and the internal space of the casing, and a common side connection pipe connected with an exit of the move conversion valve and the pressure surface of the vane. 
     In the compressor according to the second exemplary embodiment of the present invention, when the application voltage is higher than the reference voltage, namely, when the application voltage is normal, and when the actually measured temperature is lower than a first reference temperature, the compression unit is changed to the saving mode. If the actually measured temperature ranges from the first reference temperature to a second reference temperature, the compression unit is changed to the power mode. If the actually measured temperature is higher than the second reference temperature, the compression unit is changed to the saving mode. Here, the first reference temperature is a reference temperature value used for discriminating the saving mode and the power mode. The temperature range from the first reference temperature to the second reference temperature corresponds to a power mode domain. The second reference temperature is an upper limit temperature value of the temperature range corresponding to the power mode domain set to be lower than the limit temperature of the overload protection device in order to prevent the compressor from being stopped. 
     A compressor according to a third exemplary embodiment of the present invention includes a casing  100  having a hermetically closed internal space, a driving motor (not shown) installed in the internal space of the casing and generating a driving force, a compression unit (not shown) installed along with the driving motor in the internal space of the casing, having at least two or more compression spaces, and controlled to be operated in a power mode or in a saving mode in which the compression unit is idly rotated in at least one compression space, according to a compressor application voltage, a plurality of cylinders each having a separated compression space and installed in the internal space of the casing  100 , a suction pipe for distributedly supplying a refrigerant to the compression spaces of the plurality of cylinders, a plurality of rolling pistons for compressing the refrigerant while making a rotating movement in the compression spaces of the cylinders, a plurality of vanes dividing the compression spaces of the cylinders into suction spaces and discharge spaces together with the rolling pistons, and a vain restraining unit for varying the operation mode of the compressor by restraining or releasing a vane of a cylinder among the vanes, wherein at least one of the vanes is restrained by pressure in the internal space of the casing. Here, if the application voltage is lower than a reference voltage, the compression unit controls the compressor to be operated in the saving mode, and when the application voltage is equal to or higher than the reference voltage, the compression unit controls the compressor to be operated in the power mode. Here, the reference voltage is a value previously set such that the compressor is prevented from being stopped due to a low voltage. 
     In the compressor according to the third exemplary embodiment of the present invention, at least one of the cylinders communicates with a vane slot allowing the vane to move in a radial direction, and at least one first restraining hole is formed substantially in a right angle direction with respect to a direction in which the vane is moved in the vane slot and communicates with the internal space of the casing. 
     In the compressor, the cylinder includes a second restraining hole formed to communicate with the suction hole at the opposite side of the first restraining hole based on the vane slot. 
     In the compressor according to the third exemplary embodiment of the present invention, when the application voltage is higher than the reference voltage, namely, when the application voltage is normal, and when the actually measured temperature is lower than a first reference temperature, the compression unit is changed to the saving mode. If the actually measured temperature ranges from the first reference temperature to a second reference temperature, the compression unit is changed to the power mode. If the actually measured temperature is higher than the second reference temperature, the compression unit is changed to the saving mode. Here, the first reference temperature is a reference temperature value used for discriminating the saving mode and the power mode. The temperature range from the first reference temperature to the second reference temperature corresponds to a power mode domain. The second reference temperature is an upper limit temperature value of the temperature range corresponding to the power mode domain set to be lower than the limit temperature of the overload protection device in order to prevent the compressor from being stopped. 
     A compressor according to a fourth exemplary embodiment of the present invention includes a casing  100  having a hermetically closed internal space, a driving motor (not shown) installed in the internal space of the casing and generating a driving force, a compression unit (not shown) installed along with the driving motor in the internal space of the casing, having at least two or more compression spaces, and controlled to be operated in a power mode or in a saving mode in which the compression unit is idly rotated in at least one compression space, according to the difference of actually measured temperatures of refrigerants discharged from the compression spaces. When the actually measured temperature is lower than a first reference temperature, the compression unit is changed to the saving mode. If the actually measured temperature ranges from the first reference temperature to a second reference temperature, the compression unit is changed to the power mode. If the actually measured temperature is higher than the second reference temperature, the compression unit is changed to the saving mode. Here, the first reference temperature is a reference temperature value used for discriminating the saving mode and the power mode. The temperature range from the first reference temperature to the second reference temperature corresponds to a power mode domain. The second reference temperature is an upper limit temperature value of the temperature range corresponding to the power mode domain set to be lower than the limit temperature of the overload protection device in order to prevent the compressor from being stopped. 
     The compressor includes the accumulator  110  and the connection unit allowing a refrigerant to flow therethrough and connected to the outdoor unit  40  and the indoor unit  50 . The connection unit includes a low pressure side connection pipe  120 , a high pressure side connection pipe  130  connected with the internal space of the casing  100 , and a common use side connection pipe  140  alternately connected with the low pressure side connection pipe  120  and the high pressure side connection pipe  130 . 
     In the compressor according to the fourth exemplary embodiment of the present invention, the compression unit is changed to the saving mode during a particular time domain of a pre-set time domain. Here, the time domain may be set based on a different reference such as 24 hours a day, etc., or may be set according to an average temperature. A detailed description will be replaced by the description made above with reference to  FIG. 2 . 
     In the compressor according to the fourth exemplary embodiment of the present invention, the compression unit may be idly rotated by using a refrigerant sucked to a suction opening of the compression unit and a refrigerant filled in the internal space of the casing. 
     A compressor according to a fifth exemplary embodiment of the present invention includes a casing having a hermetically closed internal space, a driving motor installed in the internal space of the casing and generating a driving force, a compression unit installed along with the driving motor in the internal space of the casing, having at least two or more compression spaces, and controlled to be operated in a power mode or in a saving mode in which the compression unit is idly rotated in at least one compression space, according to the difference of actually measured temperatures of the refrigerants discharged from the compression spaces, a plurality of cylinders each having a separated compression space and installed in the internal space of the casing  100 , a suction pipe for distributedly supplying a refrigerant to the compression spaces of the plurality of cylinders, a plurality of rolling pistons for compressing the refrigerant while making a rotating movement in the compression spaces of the cylinders, a plurality of vanes dividing the compression spaces of the cylinders into suction spaces and discharge spaces together with the rolling pistons, and a vain restraining unit for varying the operation mode of the compressor by restraining or releasing a vane of a cylinder among the vanes. Here, when the actually measured temperature is lower than a first reference temperature, the compression unit is changed to the saving mode. If the actually measured temperature ranges from the first reference temperature to a second reference temperature, the compression unit is changed to the power mode. If the actually measured temperature is higher than the second reference temperature, the compression unit is changed to the saving mode. 
     Here, in the compressor, one side of at least one of the vanes has a sealing surface being in contact with the rolling piston, and the other side of the sealing surface has a pressure surface pressing the vane toward the rolling piston. 
     A chamber is formed at the pressure surface of the vane of one of the cylinders, which is separated from the internal space of the casing and filled with a refrigerator of suction pressure or discharge pressure. 
     The compressor further includes a mode conversion unit formed at an outer side of the casing to selectively provide the refrigerant of suction pressure or discharge pressure to the pressure surface of the vane. 
     In the compressor according to the fifth exemplary embodiment of the present invention, the mode conversion unit includes: a mode conversion valve for selecting the refrigerant of suction pressure or discharge pressure at the vane, a low pressure side connection pipe for connecting a first entrance of the mode conversion valve and a suction pipe, a high pressure side connection pipe for connecting a second entrance of the mode conversion valve and the internal space of the casing, and a common side connection pipe connected with an exit of the move conversion valve and the pressure surface of the vane. 
     A compressor according to a sixth exemplary embodiment of the present invention includes a casing having a hermetically closed internal space, a driving motor installed in the internal space of the casing and generating a driving force, a compression unit installed along with the driving motor in the internal space of the casing, having at least two or more compression spaces, and controlled to be operated in a power mode or in a saving mode in which the compression unit is idly rotated in at least one compression space, according to the difference of actually measured temperatures of the refrigerants discharged from the compression spaces, a plurality of cylinders each having a separated compression space and installed in the internal space of the casing  100 , a suction pipe for distributedly supplying a refrigerant to the compression spaces of the plurality of cylinders, a plurality of rolling pistons for compressing the refrigerant while making a rotating movement in the compression spaces of the cylinders, a plurality of vanes dividing the compression spaces of the cylinders into suction spaces and discharge spaces together with the rolling pistons, and a vain restraining unit for varying the operation mode of the compressor by restraining or releasing a vane of a cylinder among the vanes, wherein at least one of the vanes is restrained by pressure in the internal space of the casing. Here, when the actually measured temperature is lower than a first reference temperature, the compression unit is changed to the saving mode. If the actually measured temperature ranges from the first reference temperature to a second reference temperature, the compression unit is changed to the power mode. If the actually measured temperature is higher than the second reference temperature, the compression unit is changed to the saving mode. 
     In the compressor according to the sixth exemplary embodiment of the present invention, at least one of the cylinders communicates with a vane slot allowing the vane to move in a radial direction, and at least one first restraining hole is formed substantially in a right angle direction with respect to a direction in which the vane is moved in the vane slot and communicates with the internal space of the casing. 
     In the compressor, the cylinder includes a second restraining hole formed to communicate with the suction hole at the opposite side of the first restraining hole based on the vane slot. 
     The structure of a compressor according to exemplary embodiments of the present invention will now be described with reference to  FIGS. 6 and 7 . 
     A compressor according to an exemplary embodiment of the present invention includes a casing  100  including a plurality of gas suction pipes SP 1  and SP 2  and a single gas discharge pipe DP connected thereto, a driving motor  200  installed at an upper portion of the casing  100  and generating a driving force, first and second compression mechanism units  300  and  400  installed at a lower portion of the casing  100  and compressing a refrigerant with a rotational force generated from the driving motor  200 , a valve unit  500  allowing the second compression mechanism unit  400  to be operated in the power mode or saving mode by changing a rear surface of a second vane  440  of the second compression mechanism unit to a high pressure atmosphere or a low pressure atmosphere, and a connection unit  600  connecting the valve unit  500  to the casing  100  and the second compression mechanism unit  400  to allow the second compression mechanism unit  400  to be controlled by the valve unit  500 . Here, the first and second compression mechanism units  300  and  400  constitute a compression unit. 
     The driving motor  200  is a motor performing a constant speed driving or an inverter driving. The driving motor  200  includes a stator  210  fixed within the casing  100  and receiving power applied from the exterior, a rotor  220  disposed with a certain gap within the stator  210  and rotated while interworking with the stator  210 , and a rotational shaft  230  coupled to the rotor  220  and transferring a rotational force to the first and second compression mechanism units  300  and  400 . 
     The first compression mechanism unit  300  includes a first cylinder  300  formed as a portion of a first cylinder assembly, having an annular shape and installed within the casing  110 , and upper and lower bearing plates (upper and lower bearings  320  and  330  coupled at both upper and lower sides of the first cylinder  310  to constitute a first cylinder assembly. 
     The first compression mechanism unit  300  further includes a first rolling piston  340  rotatably coupled to an upper eccentric portion of the rotational shaft  230  and compressing a refrigerant while making a rotational movement in a first compression space V 1  of the first cylinder, and a first vane  350  coupled to be movable in a radial direction to the first cylinder  310  such that it is pressed to be brought into contact with an outer circumferential surface of the first rolling piston  340  and dividing the first compression space V 1  of the first cylinder  310  into a first suction chamber and a first compression chamber. 
     The first compression mechanism unit  300  further includes a vane support spring  360  formed as a compression spring to elastically support a rear side of the vane  350 , a first discharge valve  370  coupled to a front end of a first discharge opening  321  provided at a central portion of the upper bearing  320  and adjusting a refrigerant gas discharged from the compression chamber of the first compression space V 1 , and a first muffler  380  having an internal volume to accommodate the first discharge valve  370  and coupled to the upper bearing  320 . 
     The second compression mechanism unit  400  includes a second cylinder  410  formed as a portion of a second cylinder assembly, having an annular shape and installed at a lower side of the first cylinder  310  within the casing  110 , and an intermediate bearing  330  and a lower bearing  420  coupled to both upper and lower sides of the second cylinder  410  to constitute the second cylinder assembly having a second compression space V 2  together with the second cylinder  410 . 
     The second compression mechanism  400  further includes a second rolling piston  430  rotatably coupled to a lower eccentric portion of the rotational shaft  230  and compressing the refrigerant while making a rotational movement within the second compression space V 2  of the second cylinder  410 , and a second vane  440  coupled to be movable in a radial direction to the second cylinder  410  such that it is pressed to be brought into contact with or separated from an outer circumferential surface of the second rolling piston  430  and dividing the second compression space V 2  of the second cylinder  410  into a second suction chamber and a second compression chamber, or connecting them. 
     The second compression mechanism unit  400  further includes a second discharge valve  450  coupled to a front end of a second discharge opening  421  provided at a central portion of the lower bearing  420  and adjusting a refrigerant gas discharged from the second compression chamber, and a second muffler  460  having a certain internal volume to accommodate the second discharge valve  450  and coupled to the lower bearing  420 . 
     The second cylinder  410  includes a second vane slot  411  formed at one side of an inner circumferential surface constituting the second compression space V 2  to allow the second vane  440  to make a reciprocal movement in a radial direction, a second suction opening  412  formed at one side of the second vane slot  411  in a radial direction to guide the refrigerant to the second compression space V 2 , and a second discharge guide groove (not shown) formed to be sloped in an axial direction at another side of the second vane slot  411  to allow the refrigerant to be discharged to the interior of the casing  100 . 
     A vane chamber  413  is formed at a radially rear side of the second vane slot  411 , hermetically closed by being connected with a common side connection pipe  630  of the connection unit  600  (to be described) and separated from the interior of the casing  100  to provide a suction pressure (Ps) or a discharge pressure (Pd) to the rear side of the second vane  440 . The vane chamber  413  is formed to have a certain internal volume and connected with the common side connection pipe  630  in order to allow a rear surface of the second vane  440  to form a pressure surface with respect to pressure supplied through the common side connection pipe  630  even if the second vane  440  moves backward completely and received at the inner side of the second vane slot  411 . 
     In the second cylinder  410 , a first flow path  414  is formed to connect the interior of the casing  100  and the second vane slot  411  in a direction perpendicular to a movement direction of the second vane  440  or in a direction having a certain crossing angle to thus allow the second vane  440  to be restraining by the discharge pressure Pd of an internal space  101  of the casing  100 , and a second flow path  415  is formed at the opposite side of the first flow path  414  to quickly restrain the second vane  440  according to a pressure difference between the first and second flow paths  414  and  415  as the second vane slot  411  and the second suction opening  412  are connected. The first and second flow paths  414  and  415  may be formed on the same straight line or may have the same sectional area. 
     The valve unit  500  includes a main valve unit  510  connected to the vane chamber  412  of the second cylinder  410 , and a sub-valve unit  520  connected with the main valve unit  510  and controlling an opening and closing operation of the main valve unit  510 . 
     The connection unit  600  includes a low pressure side connection pipe  120  branched from the second gas suction pipe SP 2  and connected to the main valve unit  510 , a high pressure side connection pipe  130  connected with the internal space  101  of the casing  100  so as to be connected to the main valve unit  510 , and a common side connection pipe  140  connected with the vane chamber  412  of the second cylinder  410  so as to be alternately connected with the low pressure connection pipe  120  and the high pressure side connection pipe  130 . 
     Here, preferably, one side of the high pressure side connection pipe  130  connected with the casing  100  is positioned between a lower end of the electric mechanism unit  200  and an upper end of the first compression mechanism unit  300  so as to be connected to be higher than the surface of oil to prevent oil from being introduced into the vane chamber  41 . 
     Although not shown, an oil blocking net may be formed at the entrance of the high pressure side connection pipe  130  or an oil blocking plate may be installed to be open downwardly to effectively prevent an introduction of oil, and the high pressure side connection pipe  130  may be disposed to become higher as it becomes away from a connection point to allow oil introduced to the high pressure side connection pipe  130  to flow to the casing  100  to thus more effectively prevent introduction of oil. 
     The operation of the compressor according to exemplary embodiments of the present invention will now be described. 
     When power is applied to the stator  210  of the driving motor  200  so the rotor  220  is rotated, the rotational shaft  230  is rotated together with the rotor  220  to transfer a rotational force of the driving motor  200  to the first and second compression mechanism units  300  and  400 . Then, the first and second compression mechanism units  300  and  400  are all perform power operation to generate a large cooling capacity, or only the first compression mechanism unit  300  may perform power operation while the second compression mechanism unit  400  perform saving operation to generate a small cooling capacity. Here, the first and second compression mechanism units  300  and  400  constitute a compression unit. 
     Here, when the compressor performs power operation, a high pressure refrigerant within the casing  100  is introduced to the vane chamber  413  through the high pressure side connection pipe  130  by the main valve unit  510  and the sub-valve unit  520 , and because the high pressure refrigerant introduced into the vane chamber  413  supports the second vane  440 , the second compression mechanism unit  400  as well as the first compression mechanism unit  300  is normally operated to compress the refrigerant. 
     Meanwhile, when the compressor perform saving operation, a low pressure refrigerant sucked to the second cylinder  410  via the gas suction pipe SP 2  is introduced to the vane chamber  413  through the low pressure side connection pipe  120  by the main valve unit  510  and the sub-valve unit  520 , so the low pressure refrigerant introduced into the vane chamber  413  supports the rear surface of the second vane  440  while the pressure force in the second compression space V 2  is applied to the front surface of the second vane  440 , separating the second vane  440  from the second rolling piston  430 . And, because a pressure difference applied to both sides of the second vane  440  is increased by the first and second flow paths  414  and  415  provided at the second cylinder  410 , the second vane  440  is quickly and effectively restrained. For example, because the high pressure oil or refrigerant is introduced to the first flow path  414  and, at the same time, it is quickly leaked to the second suction opening  412  through the gap between the second vane  440  and the vain slot  411  and the second flow path  415 , when the operation mode of the compressor is changed, the second vane  440  is quickly and stably restrained. Accordingly, compression is normally made only in the first compression mechanism unit  300 , while the second compression mechanism unit does not perform compression. 
     As so far described, the compressor and the air-conditioner having the same have the following advantages. 
     That is, voltage applied to the compressor is detected, or voltage applied to the compressor is detected, temperature of a refrigerant discharged from the compressor or an ambient temperature is detected to operate the air-conditioner in a pre-set operation mode or operate the air-conditioner in a pre-set operation mode in a certain time domain, to thus continuously operate the compressor, thereby improving the reliability and operation efficiency of the compressor and air-conditioner and reducing noise. 
     Second, the temperature of the refrigerant discharged from the compressor of the ambient temperature are detected to operate the air-conditioner in a pre-set operation mode or operate the air-conditioner in a pre-set operation mode in a certain time domain, to thus continuously operate the compressor, thereby improving the reliability and operation efficiency of the compressor and air-conditioner and reducing noise. 
     In the above description, the compressor application voltage is detected, and the compressor is operated based on the detected application voltage, but the present invention can be also applicable to a method in which a compressor application current is detected and the compressor is operated based on the detected application current. 
     As the present invention may be embodied in several forms without departing from the characteristics thereof, it should also be understood that the above-described embodiments are not limited by any of the details of the foregoing description, unless otherwise specified, but rather should be construed broadly within its scope as defined in the appended claims, and therefore all changes and modifications that fall within the metes and bounds of the claims, or equivalents of such metes and bounds are therefore intended to be embraced by the appended claims.