Patent Description:
As shown in PTL <NUM> (<CIT>), a refrigerant that has a small global warming potential and that includes a chlorine atom and an olefin bond in a molecule may be used for environmental conservation in a refrigeration cycle apparatus.

US patent application <CIT> discloses a refrigeration apparatus comprising a refrigerant circuit wherein the refrigerant contains chlorine atoms and an olefin bond in the molecule (R-1233zd(E)).

Grease may be used as a lubricant for various sliding portions of devices installed in a refrigerant circuit in which a refrigerant flows.

However, when a refrigerant containing a chlorine atom and an olefin bond in a molecule is used, using grease which is used in a conventional refrigeration cycle apparatus may cause inconvenience such as a decrease in the function of the grease as a lubricant.

The use of grease (G) according to a first aspect is the use of grease in a device installed in a refrigerant circuit in which a refrigerant containing a chlorine atom and an olefin bond in a molecule flows. The grease contains fluorine as a component as an oil containing fluorine is used as a base oil in the grease (G) and/or a fluororesin is used as a thickening agent in the grease (G).

With the use of grease according to the first aspect, by using the grease containing fluorine which has high chemical stability, it is possible to suppress the decrease in the function of the grease as a lubricant even when using a refrigerant that contains a chlorine atom and an olefin bond in the molecule.

The use of grease according to a second aspect is the use of grease according to the first aspect in which the refrigerant contains R1233zd(E).

By using the grease according to the second aspect, it is possible to suppress occurrence of sliding failure of sliding portions of devices in the refrigerant circuit while using, in the refrigerant circuit, R1233zd(E) that has a small global warming potential, a zero ozone depletion potential, a small environmental load and that is non-flammable and safe with low toxicity.

The use of grease according to a third aspect is the grease according to the first aspect or the second aspect in which the grease is used as the lubricant for at least one of a rolling bearing that pivotably supports a shaft coupled to a motor of a compressor installed in the refrigerant circuit, a drive portion of an inlet guide vane provided at a suction port of the compressor installed in the refrigerant circuit, and a drive portion of a valve body of an expansion valve installed in the refrigerant circuit.

By using the grease having high chemical stability, it is possible to suppress damage to the rolling bearing, the inlet guide vane, the expansion valve, and the like even when using a refrigerant that contains a chlorine atom and an olefin bond in a molecule.

A refrigeration cycle apparatus according to a fourth aspect includes a refrigerant circuit in which a refrigerant that contains a chlorine atom and an olefin bond in a molecule flows. At least a turbo compressor and an expansion valve are installed in the refrigerant circuit. The turbo compressor includes an inlet guide vane, a motor, a shaft, an impeller, and a rolling bearing. The inlet guide vane is provided at a suction port of the turbo compressor. The shaft is coupled to the motor. The impeller is provided on the shaft. The rolling bearing pivotably supports the shaft. The expansion valve includes a valve body and a drive portion of the valve body. Grease containing fluorine is used as a lubricant for at least one of the rolling bearing of the turbo compressor, a drive portion of the inlet guide vane of the turbo compressor, and the drive portion of the expansion valve, wherein an oil containing fluorine is used as a base oil in the grease and/or a fluororesin is used as a thickening agent in the grease.

In the refrigeration cycle apparatus according to the fourth aspect, it is possible to suppress damage to the rolling bearing, the inlet guide vane, the expansion valve, and the like for each of which grease is used, even when using a refrigerant that contains a chlorine atom and an olefin bond in a molecule.

A refrigeration cycle apparatus according to a fifth aspect comprises a refrigerant circuit in which a refrigerant containing a chlorine atom and an olefin bond in a molecule flows; a device installed in the refrigerant circuit; and a grease used in the device and including fluorine as a component, wherein an oil containing fluorine is used as a base oil in the grease and/or a fluororesin is used as a thickening agent in the grease.

Hereinafter, an embodiment of grease and a refrigeration cycle apparatus will be described with reference to the drawings.

A chiller apparatus <NUM> in which grease according to the present disclosure is used as a lubricant will be described with reference to <FIG> is a schematic diagram of the chiller apparatus <NUM>.

The chiller apparatus <NUM> is an example of a refrigeration cycle apparatus that uses a vapor compression refrigeration cycle. The chiller apparatus <NUM> is an apparatus that cools liquid (heat medium) by causing the liquid to exchange heat with a refrigerant. The liquid cooled in the chiller apparatus <NUM> is supplied to a use-side device (not illustrated) and used for air conditioning, cooling of facility devices, and the like. The liquid used in the present embodiment is, for example, water or brine. The brine is, for example, a sodium chloride aqueous solution, a calcium chloride aqueous solution, an ethylene glycol aqueous solution, a propylene glycol aqueous solution, or the like. The liquid (heat medium) that exchanges heat with the refrigerant is not limited to the types presented here as examples and may be selected, as appropriate. In the present embodiment, water is used as the liquid (heat medium).

The type of the refrigeration cycle apparatus is not limited to the chiller apparatus <NUM> that cools liquid. For example, the refrigeration cycle apparatus may be an apparatus that causes the liquid (heat medium) to exchange heat with the refrigerant, thereby heating the liquid. The refrigeration cycle apparatus may be an apparatus that causes air, instead of a liquid, to exchange heat with the refrigerant, thereby cooling or heating the air.

The chiller apparatus <NUM> includes a refrigerant circuit <NUM>. Devices disposed in the refrigerant circuit <NUM> include, mainly, a compressor <NUM>, a condenser <NUM>, an expansion valve <NUM>, and an evaporator <NUM>. The refrigerant circuit <NUM> is configured such that the compressor <NUM>, the condenser <NUM>, the expansion valve <NUM>, and the evaporator <NUM> are connected to each other by refrigerant pipes as follows. A discharge pipe <NUM>, which will be described later, of the compressor <NUM> is connected to an inlet of the condenser <NUM> by a refrigerant pipe. An outlet of the condenser <NUM> is connected to an inlet of the evaporator <NUM> by a refrigerant pipe. The expansion valve <NUM> is disposed in the refrigerant pipe that connects the outlet of the condenser <NUM> and the inlet of the evaporator <NUM> to each other. An outlet of the evaporator <NUM> is connected to a later-described suction pipe <NUM> of the compressor <NUM>.

Devices disposed in the refrigerant circuit <NUM> are not limited to the compressor <NUM>, the condenser <NUM>, the expansion valve <NUM>, and the evaporator <NUM> and may include, in addition to these devices, other devices that are generally used in the refrigerant circuit <NUM> of the refrigeration cycle apparatus.

The refrigerant circuit <NUM> is charged with a refrigerant that contains a chlorine atom and an olefin bond in a molecule. The refrigerant that contains a chlorine atom and an olefin bond in a molecule and that is charged in the refrigerant circuit <NUM> includes, for example, R1233zd(E) (trans-<NUM>-chloro-<NUM>,<NUM>,<NUM>-trifluoropropene), R1233xf (<NUM>-chloro-<NUM>,<NUM>,<NUM>-trifluoropropene), and R1224yd(Z) ((Z)-<NUM>-chloro-<NUM>,<NUM>,<NUM>,<NUM>-tetrafluoropropene); however, the type of the refrigerant is not limited. The refrigerant charged in the refrigerant circuit <NUM> may be a refrigerant of a single component or may be a mixed refrigerant in which two or more types of refrigerants are mixed. In the chiller apparatus <NUM> of the present embodiment, a single component of R1233zd(E) is used as a refrigerant.

The chiller apparatus <NUM> also includes a controller <NUM> that controls operation of various components (an inlet guide vane <NUM>, a motor <NUM>, and a magnetic bearing <NUM>, which will be described later) of the compressor <NUM>, the expansion valve <NUM>, and portions of the chiller apparatus <NUM>.

When the chiller apparatus <NUM> is operated, the refrigerant circulates in the refrigerant circuit <NUM>, and a refrigeration cycle is performed. Specifically, when the motor <NUM> of the compressor <NUM> is operated, the compressor <NUM> sucks a low-pressure gas refrigerant of the refrigeration cycle, compresses the sucked gas refrigerant, and discharges the gas refrigerant as a high-pressure gas refrigerant of the refrigeration cycle. The high-pressure gas refrigerant discharged by the compressor <NUM> is sent to the condenser <NUM>. The high-pressure gas refrigerant sent to the condenser <NUM> radiates heat and condenses in the condenser <NUM>, thereby becoming a high-pressure liquid refrigerant. The refrigerant that has condensed in the condenser <NUM> passes through the expansion valve <NUM> and is sent to the evaporator <NUM>. The high-pressure liquid refrigerant that flows from the condenser <NUM> toward the evaporator <NUM> is decompressed when passing through the expansion valve <NUM> and becomes a low-pressure gas-liquid two-phase refrigerant. The low-pressure gas-liquid two-phase refrigerant that has flowed into the evaporator <NUM> evaporates by absorbing heat from the liquid (heat medium) that is supplied to the evaporator <NUM>, thereby becoming a low-pressure gas refrigerant. As a result of the refrigerant absorbing heat from the liquid in the evaporator <NUM>, the liquid is cooled. The liquid cooled in the evaporator <NUM> is supplied to a use-side device (not illustrated) that uses the cooled liquid. The gas refrigerant that has evaporated in the evaporator <NUM> is sucked by the compressor <NUM> and compressed again.

The compressor <NUM> is an apparatus that sucks a low-pressure gas refrigerant of the refrigeration cycle, compresses the sucked gas refrigerant, and discharges the gas refrigerant as a high-pressure gas refrigerant of the refrigeration cycle. In the present embodiment, the compressor <NUM> is a single-stage compression turbo compressor.

The compressor <NUM> is, however, not limited to the single-stage compression turbo compressor and may be a multi-stage compression turbo compressor. The type of the compressor used in the refrigeration cycle apparatus is not limited to the turbo compressor and may be a compressor of another type. For example, the compressor of the refrigeration cycle apparatus may be a positive-displacement compressor, such as a screw compressor, instead of a centrifugal compressor, such as a turbo compressor.

The compressor <NUM> of the present embodiment is an oil-free compressor that does not use a refrigerating-machine oil (lubricating oil) for lubrication of sliding portions.

The structure of the compressor <NUM> will be described with reference to <FIG> is a schematic sectional view of the compressor <NUM>. The compressor <NUM> includes, mainly, a casing <NUM>, a compression mechanism <NUM>, a shaft <NUM>, a motor <NUM>, a magnetic bearing <NUM>, and a touchdown bearing (auxiliary bearing) <NUM>.

Configurations of these components of the compressor <NUM> will be roughly described.

The casing <NUM> accommodates therein various components of the compressor <NUM>, including the compression mechanism <NUM>, the shaft <NUM>, the motor <NUM>, the magnetic bearing <NUM>, and the touchdown bearing <NUM>.

The compression mechanism <NUM> includes, mainly, an impeller <NUM>, the inlet guide vane <NUM>, and a diffuser portion <NUM> provided in the casing <NUM>. After increasing the speed of a refrigerant gas by the rotation of the impeller <NUM>, the compression mechanism <NUM> converts the kinetic energy of the refrigerant gas into a pressure at the diffuser portion <NUM> and thereby compresses the refrigerant gas.

The impeller <NUM> of the compression mechanism <NUM> is attached to the shaft <NUM>. The shaft <NUM> is coupled to a later-described rotor <NUM> of the motor <NUM>. When the rotor <NUM> of the motor <NUM> rotates, the shaft <NUM> rotates, and the impeller <NUM> attached to the shaft <NUM> rotates.

The magnetic bearing <NUM> magnetically floats the shaft <NUM> and rotatably supports the shaft <NUM>. The touchdown bearing <NUM> supports the shaft <NUM> while the magnetic bearing <NUM> is not energization due to a power failure or the like, in other words, while the shaft <NUM> is not magnetically floated.

Details of the casing <NUM>, the compression mechanism <NUM>, the shaft <NUM>, the motor <NUM>, the magnetic bearing <NUM>, and the touchdown bearing <NUM> will be described.

The casing <NUM> has a cylindrical shape closed at both ends. The compressor <NUM> is installed in an orientation in which a center axis O of the cylindrical casing <NUM> extends substantially horizontally. The internal space of the casing <NUM> is demarcated by a wall portion <NUM> into an impeller chamber S1 that accommodates the impeller <NUM> of the compression mechanism <NUM> and a motor chamber S2 that accommodates the motor <NUM>. In <FIG>, the impeller chamber S1 is disposed on the right side of the wall portion <NUM>, and the motor chamber S2 is disposed on the left side of the wall portion <NUM>. The impeller chamber S1 and the motor chamber S2 are demarcated by the wall portion <NUM> to be in communication with each other, not in an airtight manner.

The casing <NUM> is provided with the suction pipe <NUM> and the discharge pipe <NUM>.

One end of the suction pipe <NUM> is connected to a suction port <NUM> formed at one end portion (right end portion in <FIG>) of the casing <NUM> in the axial direction of the center axis O. The suction port <NUM> opens at a center portion of the impeller chamber S1 when viewed along the center axis O. The other end (end portion on a side opposite to the side connected to the suction port <NUM> of the casing <NUM>) of the suction pipe <NUM> is connected to the evaporator <NUM> via a pipe. When the compressor <NUM> is operated, the low-pressure gas refrigerant of the refrigeration cycle is sucked into the impeller chamber S1 via the suction pipe <NUM>. As described above, the impeller chamber S1 and the motor chamber S2 are in communication with each other, and thus, part of the refrigerant that has flowed into the impeller chamber S1 via the suction pipe <NUM> also flows into the motor chamber S2.

An end of the discharge pipe <NUM> is connected to a side portion of the casing <NUM>. The discharge pipe <NUM> opens in a first space <NUM>. The first space <NUM> is a space into which the refrigerant whose speed has been increased by the impeller <NUM> flows by passing through the diffuser portion <NUM>. The other end (end portion on a side opposite to the side connected to the casing <NUM>) of the discharge pipe <NUM> is connected to the condenser <NUM> via a pipe. When the compressor <NUM> is operated, the high-pressure gas refrigerant compressed by the compression mechanism <NUM> passes through the first space <NUM> and the discharge pipe <NUM> and is sent to the condenser <NUM>.

As described above, the compression mechanism <NUM> includes, mainly, the impeller <NUM>, the inlet guide vane <NUM>, and the diffuser portion <NUM>.

The impeller <NUM> includes a plurality of blades and has substantially a conical outer shape. The impeller <NUM> is disposed in the impeller chamber S1. The impeller <NUM> is attached to the shaft <NUM>. When the shaft <NUM> rotates and the impeller <NUM> rotates, the gas refrigerant is taken into the impeller <NUM>, and the speed of the gas refrigerant is increased by the impeller <NUM>.

The inlet guide vane <NUM> is a mechanism that is provided at the suction port <NUM> of the compressor <NUM> to which the suction pipe <NUM> is connected and that adjusts the inflow amount of the refrigerant that flows to the impeller <NUM>. The inlet guide vane <NUM> is disposed on the upstream side of the impeller <NUM> in a refrigerant suctioning direction of the compressor <NUM>. The inlet guide vane <NUM> is attached to the casing <NUM>.

The inlet guide vane <NUM> includes, mainly, a plurality of vane bodies 124a, a support portion 125a, an attachment portion 125b, and a drive portion 124b that drives the vane bodies 124a. The drive portion 124b is a stepping motor but is not limited thereto. The vane bodies 124a are wing-shaped members formed on a thin plate. The support portion 125a supports the vane bodies 124a. The support portion 125a is a member that is coupled to the vane bodies 124a and that serves as a shaft for turning the vane bodies 124a. The attachment portion 125b rotatably supports the support portion 125a. The attachment portion 125b is fixed to the casing <NUM> directly or indirectly. By the drive portion 124b turning the support portion 125a with respect to the attachment portion 125b via a power transmission mechanism (not illustrated), the vane bodies 124a turn, and the flow-path area of a flow path for the refrigerant that flows from the suction port <NUM> toward the impeller <NUM> in a view along the center axis O changes. As a result, the inflow amount of the refrigerant that flows to the impeller <NUM> changes.

The diffuser portion <NUM> is a refrigerant flow path that changes the refrigerant speed and increases the refrigerant pressure. The diffuser portion <NUM> is disposed between the impeller chamber S1 and the first space <NUM>.

The shaft <NUM> is a drive shaft that transmits the driving force of the motor <NUM> to the impeller <NUM>. The shaft <NUM> extends across the impeller chamber S1 and the motor chamber S2. In other words, the shaft <NUM> extends between the impeller chamber S1 and the motor chamber S2 beyond the wall portion <NUM>. The shaft <NUM> is coupled at a center portion thereof in the axial direction (identical to the axial direction of the center axis O of the casing <NUM>) of the shaft <NUM> to the rotor <NUM> of the motor <NUM>. The impeller <NUM> is attached to one end portion of the shaft <NUM>. The other end portion of the shaft <NUM> is provided with a disc portion <NUM>.

The shaft <NUM> and the disc portion <NUM> are each made of a magnetic material since the shaft <NUM> is supported by the magnetic bearing <NUM> in the compressor <NUM>.

The motor <NUM> rotates the shaft <NUM>. The motor <NUM> has, mainly, a stator <NUM> and the rotor <NUM>. The stator <NUM> is formed in a cylindrical shape. The outer surface of the stator <NUM> is fixed to the inner surface of the casing <NUM>. The rotor <NUM> is formed in a columnar shape. The rotor <NUM> is rotatably installed on the inner side of the stator <NUM> with a slight gap therebetween. A shaft hole into which the shaft <NUM> is inserted and fixed is formed at a center portion of the rotor <NUM>.

The magnetic bearing <NUM> supports the shaft <NUM> rotatably in a non-contact manner by magnetically floating the shaft <NUM>.

The magnetic bearing <NUM> preferably includes a first radial magnetic bearing <NUM>, a second radial magnetic bearing <NUM>, and a thrust magnetic bearing <NUM>. The first radial magnetic bearing <NUM> is disposed between the impeller <NUM> and the motor <NUM> in the axial direction of the shaft <NUM>. In the axial direction of the shaft <NUM>, the second radial magnetic bearing <NUM> is disposed between the motor <NUM> and the disc portion <NUM> provided at the end portion of the shaft <NUM>. The thrust magnetic bearing <NUM> is disposed adjacent to the disc portion <NUM> provided at the end portion of the shaft <NUM>.

Each of the first radial magnetic bearing <NUM>, the second radial magnetic bearing <NUM>, and the thrust magnetic bearing <NUM> includes a plurality of electromagnets (not illustrated) and supports the shaft <NUM> in a non-contact manner by a combined electromagnetic force of the plurality of electromagnets.

The plurality of electromagnets of the first radial magnetic bearing <NUM> are disposed adjacent to each other in the circumferential direction around the shaft <NUM>. The plurality of electromagnets of the second radial magnetic bearing <NUM> are disposed adjacent to each other in the circumferential direction around the shaft <NUM>. The plurality of electromagnets of the thrust magnetic bearing <NUM> are disposed in the axial direction of the shaft <NUM> so as to sandwich the disc portion <NUM> provided at the end portion of the shaft <NUM>. The first radial magnetic bearing <NUM> and the second radial magnetic bearing <NUM> adjust the position of the shaft <NUM> in the radial direction. The thrust magnetic bearing <NUM> adjusts the position of the shaft <NUM> in the axial direction.

Positional adjustment of the shaft <NUM> will be described in more detail. The compressor <NUM> is provided with a plurality of sensors (not illustrated) for detecting the radial-direction position and the axial-direction position of the shaft <NUM> with respect to the magnetic bearings <NUM>, <NUM>, and <NUM>. The sensors for detecting the radial-direction position and the axial-direction position of the shaft <NUM> with respect to the magnetic bearings <NUM>, <NUM>, and <NUM> are, for example, eddy-current-type displacement sensors. On the basis of results of detection by these sensors, the controller <NUM>, which will be described later, controls the combined electromagnetic force that acts on the shaft <NUM> such that the shaft <NUM> is disposed at a predetermined position with respect to the magnetic bearings <NUM>, <NUM>, and <NUM>. Specifically, the controller <NUM> controls a current that flows through each of the plurality of electromagnets of the first radial magnetic bearing <NUM>, the second radial magnetic bearing <NUM>, and the thrust magnetic bearing <NUM> to thereby control the combined electromagnetic force that acts on the shaft <NUM> and control the position of the shaft <NUM> with respect to the magnetic bearings <NUM>, <NUM>, and <NUM>.

The touchdown bearing <NUM> is a bearing that supports the shaft <NUM> while the magnetic bearing <NUM> is not energized, in other words, while the shaft <NUM> does not magnetically float.

The touchdown bearing <NUM> includes a first radial touchdown bearing <NUM> and a second radial touchdown bearing <NUM>. The first radial touchdown bearing <NUM> and the second radial touchdown bearing <NUM> are each a rolling bearing. The rolling bearing may be a ball bearing in which a rolling element is a "ball" or may be a roller bearing in which a rolling element is a "roller". The inner ring, the outer ring, and the rolling element of each of the first radial touchdown bearing <NUM> and the second radial touchdown bearing <NUM> are each made of, for example, high-carbon chromium bearing steel but are not limited thereto.

The first radial touchdown bearing <NUM> is disposed adjacent to the first radial magnetic bearing <NUM>. The first radial touchdown bearing <NUM> is disposed between the impeller <NUM> and the first radial magnetic bearing <NUM> in the axial direction of the shaft <NUM>. The position of the first radial touchdown bearing <NUM> is, however, not limited to this position and the first radial touchdown bearing <NUM> may be disposed between the first radial magnetic bearing <NUM> and the motor <NUM> in the axial direction of the shaft <NUM>.

The second radial touchdown bearing <NUM> is disposed adjacent to the second radial magnetic bearing <NUM>. The second radial touchdown bearing <NUM> is disposed between the second radial magnetic bearing <NUM> and the disc portion <NUM> provided at the end portion of the shaft <NUM> in the axial direction of the shaft <NUM>. The position of the second radial touchdown bearing <NUM> is, however, not limited this position and the second radial touchdown bearing <NUM> may be disposed between the motor <NUM> and the second radial magnetic bearing <NUM> in the axial direction of the shaft <NUM>.

The condenser <NUM> is a water-cooled condenser in the present embodiment. However, the condenser <NUM> of the chiller apparatus <NUM> is not limited to the water-cooled condenser and may be an air-cooled condenser.

The condenser <NUM> is, for example, a shell-and-tube condenser; however, the type of heat exchanger is not limited. Cooling water cooled in, for example, a cooling tower (not illustrated) is supplied to the condenser <NUM>, and heat is exchanged between the cooling water and the refrigerant.

In the present embodiment, the expansion valve <NUM> is an electronic expansion valve. The expansion valve <NUM>, however, may be a temperature automatic expansion valve that has a temperature sensitive cylinder. The chiller apparatus <NUM> may have, as an alternative to the expansion valve <NUM>, a capillary tube as an expansion mechanism.

As illustrated in <FIG>, the expansion valve <NUM> includes, mainly, a valve body <NUM> and a drive portion <NUM> that drives the valve body <NUM>. The drive portion <NUM> is a stepping motor but is not limited thereto. On the basis of results of detection by one or a plurality of sensors (not illustrated) that measure the temperature or the pressure of the refrigerant at a predetermined location in the refrigerant circuit <NUM>, the later-described controller <NUM> controls the drive portion <NUM> to drive the valve body <NUM> and controls the opening degree of the expansion valve <NUM>. When the drive portion <NUM> drives the valve body <NUM>, the valve body <NUM> moves, while sliding on a side wall 32a that surrounds the valve body <NUM>, to narrow the flow path for the refrigerant in the expansion valve <NUM> or to expand the flow path for the refrigerant in the expansion valve <NUM>. For example, in <FIG>, the valve body <NUM> moves upward and downward while sliding on the side wall 32a that surrounds the valve body <NUM>. The controller <NUM> controls the drive portion <NUM> to drive the valve body <NUM> and controls the opening degree of the expansion valve <NUM>, for example, to cause the degree of superheating calculated from the evaporation temperature of the refrigerant and the refrigerant temperature at the outlet of the evaporator <NUM>, which are measured by the sensors, to become target values; however, the control method is not limited.

The evaporator <NUM> is an evaporator for cooling liquid in the present embodiment. The evaporator <NUM> of the chiller apparatus <NUM> is not limited to the evaporator for cooling liquid and may be an evaporator for cooling air.

The evaporator <NUM> is, for example, a shell-and-tube evaporator; however, the type of heat exchanger is not limited. Liquid (heat medium) is supplied to the evaporator <NUM>, heat is exchanged between the liquid and the refrigerant, and the liquid is cooled. The liquid cooled in the evaporator <NUM> is supplied to a use-side device (not illustrated) that uses the cooled liquid and used for air conditioning, cooling of facility devices, and the like.

The controller <NUM> is a device that controls operation of portions of the chiller apparatus <NUM>. The controller <NUM> is electrically connected to the compressor <NUM> and the expansion valve <NUM>, for example, to be capable of controlling the operation of the compressor <NUM> and the expansion valve <NUM>. The controller <NUM> is connected to sensors (not illustrated) for detecting the radial-direction position and the axial-direction position of the shaft <NUM> with respect to the magnetic bearings <NUM>, <NUM>, and <NUM> and sensors (not illustrated) for measuring the temperature or the pressure of the refrigerant at a predetermined location in the refrigerant circuit <NUM>, so as to be capable of receiving signals from the sensors.

The controller <NUM> has, for example, a microprocessor or a CPU, an input/output interface, a RAM, a ROM, and a storage device in which a control program for controlling the operation of the chiller apparatus <NUM> is stored. The controller <NUM> may have an input device that receives an input from a user, a display device that displays various types of information for a user, and the like.

As described above, the controller <NUM> controls the combined electromagnetic force that acts on the shaft <NUM> on the basis of results of detection by the sensors for detecting the radial-direction position and the axial-direction position of the shaft <NUM> with respect to the magnetic bearings <NUM>, <NUM>, and <NUM> to dispose the shaft <NUM> at a predetermined position with respect to the magnetic bearings <NUM>, <NUM>, and <NUM>.

The controller <NUM> also controls the capacity of the compressor <NUM> by controlling the rotational speed of the motor <NUM> of the compressor <NUM> on the basis of a result of measurement and the like by sensors (not illustrated) that measure the temperature or the pressure of the refrigerant at a predetermined location in the refrigerant circuit <NUM>. The controller <NUM> also controls the amount of the refrigerant that flows into the impeller <NUM> by controlling the drive portion 124b of the inlet guide vane <NUM> on the basis of a measurement result and the like obtained by sensors (not illustrated) that measure the temperature or the pressure of the refrigerant at predetermined locations in the refrigerant circuit <NUM>. The controller <NUM> also controls the drive portion <NUM> of the expansion valve <NUM> on the basis of a result of measurement and the like by sensors (not illustrated) that measure the temperature or the pressure of the refrigerant at predetermined portions of the refrigerant circuit <NUM>, and adjusts the opening degree of the expansion valve <NUM>. As a method of controlling the motor <NUM>, the inlet guide vane <NUM>, and the expansion valve <NUM> by the controller <NUM>, various methods may be used.

In the chiller apparatus <NUM>, the following grease (referred to as grease G) is used for at least one of the devices installed in the refrigerant circuit <NUM>. More specifically, the grease G is used, in the devices installed in the refrigerant circuit <NUM>, at portions that require lubrication and in which the refrigerant may flow. In other words, the grease G is used, in the devices installed in the refrigerant circuit <NUM>, at portions at each of which one member slides with respect to another member and in each of which the refrigerant may flow.

As a specific example, the grease G is used for at least one of the touchdown bearing <NUM> (the first radial touchdown bearing <NUM> and the second radial touchdown bearing <NUM>), the drive portion 124b of the inlet guide vane <NUM>, and the drive portion <NUM> of the expansion valve <NUM>. In particular, in the chiller apparatus <NUM> of the present embodiment, the grease G is used as the lubricant for all of the touchdown bearing <NUM>, the drive portion 124b of the inlet guide vane <NUM>, and the drive portion <NUM> of the expansion valve <NUM>. Specifically, the grease G is used, for the inlet guide vane <NUM>, at a rolling bearing 124ba in the stepper motor as the drive portion 124b of the inlet guide vane <NUM>. Specifically, the grease G is used, for the expansion valve <NUM>, at a rolling bearing 34a in the stepper motor as the drive portion <NUM> of the expansion valve <NUM>. The rolling bearings 34a and 124ba may be each a ball bearing in which the rolling element is a "ball" or may be a roller bearing in which the rolling element is a "roller". The inner ring, the outer ring, and the rolling element of each of the rolling bearings 34a and 124ba are each made of, for example, high-carbon chromium bearing steel but is not limited thereto.

The grease G may be used only for some of the touchdown bearing <NUM>, the drive portion 124b of the inlet guide vane <NUM>, and the drive portion <NUM> of the expansion valve <NUM>. The grease G may be used at parts, other than those presented as examples, of the compressor <NUM> and/or the expansion valve <NUM> that require lubrication and in which the refrigerant may flow. The grease G may be used at portions of devices other than the compressor <NUM> and the expansion valve <NUM>, that require lubrication and in each of which the refrigerant may flow.

The grease G is grease that contains, as a component, fluorine having high chemical stability. In particular, in order to suppress an influence that is generated on the grease by using the refrigerant that contains a chlorine atom and an olefin bond in a molecule in the refrigerant circuit <NUM>, the grease that contains 10wt% or more of fluorine is preferably used as the grease G.

The grease G contains, mainly, a base oil that serves as a base material, and a thickening agent dispersed in the base oil. Examples of the base oil used in the grease G include a mineral oil, a synthetic hydrocarbon oil, an ether oil, an ester oil, a polyglycol oil, a silicone oil, a fluorosilicone oil, and a fluorine oil. Examples of the thickening agent used in the grease G include calcium soap, lithium soap, sodium soap, calcium complex soap, aluminum complex soap, lithium complex soap, barium complex soap, bentonite, a urea compound, and a fluororesin (PTFE and the like).

When an oil that does not contain fluorine is used as the base oil in the grease G, a component containing fluorine is used as the thickening agent. When a component containing fluorine is not used as the thickening agent in the grease G, an oil containing fluorine is used as the base oil.

In particular, it is preferable for the grease G to use a fluorine-containing oil (the fluorosilicone oil or the fluorine oil among the presented examples of the base oil) as the base oil, and a fluororesin as the thickening agent. As described above, the grease G preferably contains 10wt% or more of fluorine.

(<NUM>-<NUM>)
The use of grease G of the present embodiment is the use of grease in a device installed in the refrigerant circuit <NUM> in which a refrigerant containing a chlorine atom and an olefin bond in a molecule flows. The grease G contains fluorine as a component, wherein an oil containing fluorine is used as a base oil in the grease and/or a fluororesin is used as a thickening agent in the grease.

By using the grease G that contains fluorine and therefore has high chemical stability, it is possible to suppress the decrease in the function of the grease G as the lubricant, even when using a refrigerant that contains a chlorine atom and an olefin bond in a molecule and that has high oil solubility.

(<NUM>-<NUM>)
The refrigerant containing a chlorine atom and an olefin bond in a molecule is, for example, a refrigerant containing R1233zd(E) (trans-<NUM>-chloro-<NUM>,<NUM>,<NUM>-trifluoropropene). The refrigerant may be a refrigerant of a single component or may be a mixed refrigerant in which two or more types of refrigerants are mixed.

R1233zd(E) is a refrigerant that has a small global warming potential, a zero ozone depletion potential, a small environmental load, and that is non-flammable and safe with low toxicity. By using the grease G as the lubricant, it is possible to suppress the occurrence of the sliding failure of sliding portions of the devices in the refrigerant circuit <NUM> while using the above-described refrigerant that has a small environmental load and that is safe.

(<NUM>-<NUM>)
In the use of grease G of the present embodiment, an oil containing fluorine is is used as the base oil.

By using the grease G in which an oil containing fluorine and therefore having high chemical stability is used as the base oil, it is possible to suppress the decrease in the function of the grease G as the lubricant even when using a refrigerant containing a chlorine atom and an olefin bond in a molecule and having high oil solubility.

Alternatively or in addition to the use of an oil containing fluorine, in the use of grease G of the present embodiment, a fluororesin is used as the thickening agent.

By using the grease G in which a fluororesin having high chemical stability is used as the thickening agent, it is possible to suppress the decrease in the function of the grease G as the lubricant even when using a refrigerant that contains a chlorine atom and an olefin bond in a molecule and that has high oil solubility.

In particular, it is preferable for the grease G to use a fluorine-containing oil as the base oil and a fluororesin as the thickening agent.

(<NUM>-<NUM>)
The use of grease G of the present embodiment is preferably as the lubricant for at least one of the following portions.

In the present embodiment, the grease G is used for all of the aforementioned three portions.

Specifically, the grease G is used, for the inlet guide vane <NUM>, at the rolling bearing 124ba in the drive portion 124b of the inlet guide vane <NUM>. Specifically, the grease G is used, for the expansion valve <NUM>, at the rolling bearing 34a in the drive portion <NUM> of the expansion valve <NUM>.

By using the grease G having high chemical stability, it is possible to suppress damage to the radial touchdown bearings <NUM> and <NUM>, the inlet guide vane <NUM>, the expansion valve <NUM>, and the like even when using a refrigerant that contains a chlorine atom and an olefin bond in a molecule.

(<NUM>-<NUM>)
The chiller apparatus <NUM> according to an example of the refrigeration cycle apparatus of the present embodiment includes the refrigerant circuit <NUM> in which a refrigerant that contains a chlorine atom and an olefin bond in a molecule flows. At least the compressor <NUM> and the expansion valve <NUM> are installed in the refrigerant circuit <NUM>. The compressor <NUM> includes the inlet guide vane <NUM>, the motor <NUM>, the shaft <NUM>, the impeller <NUM>, and the first radial touchdown bearing <NUM> and the second radial touchdown bearing <NUM> as examples of the rolling bearing. The inlet guide vane <NUM> is provided at the suction port <NUM> of the compressor <NUM>. The shaft <NUM> is coupled to the motor <NUM>. The impeller <NUM> is provided on the shaft <NUM>. The first radial touchdown bearing <NUM> and the second radial touchdown bearing <NUM> pivotably support the shaft <NUM>. The expansion valve <NUM> includes the valve body <NUM> and the drive portion <NUM> of the valve body <NUM>. The grease G containing fluorine is used as the lubricant for at least one of the first radial touchdown bearing <NUM> and the second radial touchdown bearing <NUM> of the compressor <NUM>, the drive portion 124b of the inlet guide vane <NUM> of the compressor <NUM>, and the drive portion <NUM> of the expansion valve <NUM>.

In the chiller apparatus <NUM> of the present embodiment, it is possible to suppress damage to the radial touchdown bearings <NUM> and <NUM>, the inlet guide vane <NUM>, the expansion valve <NUM>, and the like, for each of which grease is used, even when using a refrigerant containing a chlorine atom and an olefin bond in a molecule.

Modifications of the aforementioned embodiment will be described below. The following modifications may be combined together, as appropriate, within a scope that causes no inconsistency.

In the aforementioned embodiment, the compressor <NUM> of the chiller apparatus <NUM> is a turbo compressor. As described above, the compressor <NUM> of the chiller apparatus <NUM>, however, may be a screw compressor. When the compressor <NUM> is a screw compressor, the grease G may be used, for example, for a rolling bearing that pivotably supports a shaft to which a rotor is attached.

In the aforementioned embodiment, the compressor <NUM> has the magnetic bearing <NUM> and the touchdown bearing <NUM> as bearings that pivotably support the shaft <NUM>; however, the compressor <NUM> is not limited thereto.

For example, the compressor <NUM> may have only a rolling bearing as the bearing of the shaft <NUM> without having the magnetic bearing <NUM>. In other words, in the compressor <NUM>, the shaft <NUM> may be constantly pivotably supported by a rolling bearing. In this case, the grease G is preferably used as the lubricant for the rolling bearing of the compressor <NUM>.

In the aforementioned embodiment, the compressor <NUM> is a compressor of a type that does not use a refrigerating-machine oil; however, the compressor <NUM> is not limited thereto. The compressor <NUM> may be a compressor that uses a refrigerating-machine oil. In this case, the grease G is not necessarily used for the first radial touchdown bearing <NUM> and the second radial touchdown bearing <NUM>.

Although an embodiment and modifications of the present disclosure have been described above, it should be understood that various changes in the forms and the details thereof are possible within the scope of the claims.

The grease of the present disclosure can be widely used and is useful in a device installed in a refrigerant circuit of a refrigeration cycle apparatus in which a refrigerant that contains a chlorine atom and an olefin bond in a molecule flows.

Claim 1:
Use of grease (G) in a device installed in a refrigerant circuit (<NUM>) in which a refrigerant containing a chlorine atom and an olefin bond in a molecule flows, the grease comprising:
fluorine as a component, wherein an oil containing fluorine is used as a base oil in the grease (G) and/or a fluororesin is used as a thickening agent in the grease (G).