Sealing mechanism and turbo refrigerator

A sealing mechanism (40) includes: a ring-shaped sealing body (41) which surrounds a rotating shaft (24) when viewed from an axial direction; a sealing-body support part (42) which supports the sealing body (41) so as to be movable in a radial direction of the rotating shaft (24); and an elastic member (44) which is interposed between the sealing body (41) and the sealing-body support part (42).

TECHNICAL FIELD

The present invention relates to a sealing mechanism and a turbo refrigerator.

Priority is claimed on Japanese Patent Application No. 2013-117738, filed on Jun. 4, 2013, the content of which is incorporated herein by reference.

BACKGROUND ART

For example, in a turbo refrigerator which is provided with a turbo compressor having a motor and an impeller, a refrigerant is compressed by the impeller, and therefore, the impeller side has a high pressure and the motor side relatively has a low pressure. If such a pressure difference is generated, gas leaks out from the high pressure side to the low pressure side, and therefore, it is necessary to perform sealing by a sealing mechanism. However, the impeller and the motor are connected by a rotating shaft for transmitting power, and therefore, it is difficult to completely isolate the high pressure side and the low pressure side from each other.

Therefore, as shown in, for example, Patent Document 1, in general, the leakage of gas along a rotating shaft is prevented by using a non-contact type labyrinth sealing mechanism which is fixed to a housing and disposed on the circumferential surface of the rotating shaft with a slight gap therebetween.

Further, Patent Document 2 discloses a mechanism for preventing the contact between a rotating shaft and a labyrinth seal by moving the labyrinth seal with respect to the rotating shaft in a radial direction of the rotating shaft, thereby narrowing the gap between the rotating shaft and the labyrinth seal at the time of a steady operation of the rotating shaft and widening the gap at the time of the starting and stopping of the rotating shaft.

Further, Patent Document 3 discloses a mechanism for preventing the contact between a rotating shaft and a labyrinth seal by moving the labyrinth seal with respect to the rotating shaft in an axial direction of the rotating shaft, thereby narrowing the gap between the rotating shaft and the labyrinth seal at the time of a steady operation of the rotating shaft and widening the gap at the time of the starting of the rotating shaft.

CITATION LIST

Patent Document

SUMMARY OF INVENTION

Technical Problem

However, if a turbo refrigerator or the like which is provided with the sealing mechanism which seals the periphery of the rotating shaft, as described above, receives an external force due to an earthquake or the like, the rotating shaft comes into contact with the sealing mechanism, and thus there is a possibility that the sealing mechanism may break. For this reason, it is necessary to separate the rotating shaft and the sealing mechanism from each other so as not to come into contact with each other. However, in the related art, since the accuracy of the centering of the sealing mechanism with respect to the rotating shaft is not sufficiently high, it is necessary to take a large safety factor, and thus a large gap has to be secured between the rotating shaft and the sealing mechanism. For this reason, sealing performance by the sealing mechanism is lowered, and thus there is a tendency that the amount of gas leakage is increased.

The present invention has been made in view of the above-described circumstances and has an object to improve sealing performance in a sealing mechanism which is disposed around a rotating shaft which is installed in a turbo refrigerator or the like.

Solution to Problem

According to a first aspect of the present invention, there is provided a sealing mechanism including: a sealing-body support part which is fastened to a housing of a turbo compressor and surrounds a rotating shaft that the housing includes; a sealing body which is provided between the sealing-body support part and the rotating shaft and sandwiched between sliding surfaces of the sealing-body support part, thereby surrounding the rotating shaft; and an elastic member which is sandwiched between the sealing body and the sealing-body support part and surrounds the sealing body.

According to a second aspect of the present invention, in the first aspect, a labyrinth groove is provided in a portion facing the rotating shaft, of the sealing body.

According to a third aspect of the present invention, in the first or second aspect, the elastic member is an O-ring which surrounds the entire circumference of the sealing body when viewed from an axial direction of the rotating shaft.

According to a fourth aspect of the present invention, in the first aspect, the sealing-body support part is composed of a ring-shaped base portion which is brought into contact with the housing, and a ring-shaped cover portion, and the sealing body is sandwiched between the base portion and the cover portion.

According to a fifth aspect of the present invention, there is provided a turbo refrigerator including: a turbo compressor which has a rotating shaft connecting an impeller and a motor and performs compression of a refrigerant; a condenser which condenses the refrigerant compressed in the turbo compressor; and an evaporator which evaporates the condensed refrigerant, wherein the sealing mechanism according to the first aspect is provided as a sealing mechanism which performs sealing of a periphery of the rotating shaft of the turbo compressor.

According to a sixth aspect of the present invention, there is provided a sealing mechanism including: a ring-shaped sealing body which is fastened to a housing of a turbo compressor and surrounds a rotating shaft that the housing includes, when viewed from an axial direction; a sealing-body support part which supports the sealing body so as to be able to move in a radial direction of the rotating shaft; and an elastic member which is interposed between the sealing body and the sealing-body support part.

Advantageous Effects of Invention

According to the present invention, the sealing body surrounding the rotating shaft is supported by the sealing-body support part so as to be able to move in the radial direction of the rotating shaft, and the elastic member is interposed between the sealing body and the sealing-body support part. Such an elastic member can be flexibly deformed, and therefore, it is possible to easily adjust the position of the sealing body with respect to the rotating shaft. Accordingly, it is possible to accurately perform the centering of the sealing body with respect to the rotating shaft by the elastic member, and thus it becomes possible to make the gap between the sealing body and the rotating shaft narrower than that in the related art. Further, according to the present invention, even in a case where the rotating shaft comes into contact with the sealing body, impact due to the contact can be absorbed by the elastic member. Accordingly, it becomes possible to make the gap between the sealing body and the rotating shaft narrower than that in the related art. Therefore, according to the present invention, it becomes possible to improve sealing performance in a sealing mechanism which is disposed around a rotating shaft which is installed in a turbo refrigerator or the like.

DESCRIPTION OF EMBODIMENTS

Hereinafter, an embodiment of a turbo refrigerator according to the present invention will be described with reference to the drawings. In addition, in the following drawings, in order to show each member in a recognizable size, the scale of each member is appropriately changed.

FIG. 1is a system diagram of a turbo refrigerator1in an embodiment of the present invention. The turbo refrigerator1is provided with a condenser2, an economizer3, an evaporator4, a turbo compressor5, an expansion valve6, and an expansion valve7, as shown inFIG. 1.

The condenser2is connected to a gas discharge pipe5aof the turbo compressor5through a flow path R1. A refrigerant (a compressed refrigerant gas X1) compressed by the turbo compressor5is supplied to the condenser2through the flow path R1. The condenser2liquefies the compressed refrigerant gas X1. The condenser2is provided with a heat exchanger tube2athrough which cooling water flows, and cools and liquefies the compressed refrigerant gas X1by heat exchange between the compressed refrigerant gas X1and the cooling water. In addition, as such a refrigerant, a chlorofluorocarbon or the like can be used.

The compressed refrigerant gas X1is cooled and liquefied by heat exchange between itself and the cooling water, thereby becoming a refrigerant liquid X2, and the refrigerant liquid X2accumulates in a bottom portion of the condenser2. The bottom portion of the condenser2is connected to the economizer3through a flow path R2. Further, the expansion valve6for decompressing the refrigerant liquid X2is provided in the flow path R2. The refrigerant liquid X2decompressed by the expansion valve6is supplied to the economizer3through the flow path R2.

The economizer3temporarily stores the decompressed refrigerant liquid X2and separates the refrigerant into a liquid phase and a gas phase. A top portion of the economizer3is connected to an economizer connecting pipe5bof the turbo compressor5through a flow path R3. A gas-phase component X3of the refrigerant separated out by the economizer3is supplied to a second compression stage12(described later) through the flow path R3without passing through the evaporator4and a first compression stage11(described later), and thus the efficiency of the turbo compressor5is increased. On the other hand, a bottom portion of the economizer3is connected to the evaporator4through a flow path R4. The expansion valve7for further decompressing the refrigerant liquid X2is provided in the flow path R4. The refrigerant liquid X2further decompressed by the expansion valve7is supplied to the evaporator4through the flow path R4.

The evaporator4evaporates the refrigerant liquid X2and cools cold water by the heat of vaporization.

The evaporator4is provided with a heat exchanger tube4athrough which the cold water flows, and causes the cooling of the cold water and the evaporation of the refrigerant liquid X2by heat exchange between the refrigerant liquid X2and the cold water. The refrigerant liquid X2evaporates by taking in heat by heat exchange between itself and the cold water, thereby becoming a refrigerant gas X4. A top portion of the evaporator4is connected to a gas suction pipe5cof the turbo compressor5through a flow path R5. The refrigerant gas X4having evaporated in the evaporator4is supplied to the turbo compressor5through the flow path R5.

The turbo compressor5compresses the refrigerant gas X4having evaporated and supplies it to the condenser2as the compressed refrigerant gas X1. The turbo compressor5is a two-stage compressor which is provided with the first compression stage11which compresses the refrigerant gas X4, and the second compression stage12which further compresses the refrigerant compressed in one step.

An impeller13is provided in the first compression stage11, an impeller14is provided in the second compression stage12, and these impellers are connected by a rotating shaft15. The turbo compressor5has a motor10and compresses the refrigerant by rotating the impeller13and the impeller14by the motor10. Each of the impeller13and the impeller14is a radial impeller and radially leads out the refrigerant suctioned in an axial direction.

An inlet guide vane16for regulating the intake amount of the first compression stage11is provided in the gas suction pipe5c. The inlet guide vane16is made to be rotatable such that an apparent area from a flow direction of the refrigerant gas X4can be changed. A diffuser flow path is provided around each of the impeller13and the impeller14, and the refrigerant led out in a radial direction is compressed and increased in pressure in the diffuser flow path. Further, it is possible to supply the refrigerant to the next compression stage by a scroll flow path provided around the diffuser flow path. An outlet throttle valve17is provided around the impeller14and can control the discharge amount from the gas discharge pipe5a.

The turbo compressor5is provided with a hermetic type housing20. The inside of the housing20is partitioned into a compression flow path space S1, a first bearing accommodation space S2, a motor accommodation space S3, a gear unit accommodation space S4, and a second bearing accommodation space S5.

The impeller13and the impeller14are provided in the compression flow path space S1. The rotating shaft15connecting the impeller13and the impeller14is provided to pass through the compression flow path space S1, the first bearing accommodation space S2, and the gear unit accommodation space S4. A bearing21supporting the rotating shaft15is provided in the first bearing accommodation space S2.

A stator22, a rotor23, and a rotating shaft24connected to the rotor23are provided in the motor accommodation space S3. The rotating shaft24is provided to pass through the motor accommodation space S3, the gear unit accommodation space S4, and the second bearing accommodation space S5. A bearing31supporting the anti-load side of the rotating shaft24is provided in the second bearing accommodation space S5. A gear unit25, a bearing26, a bearing27, and an oil tank28are provided in the gear unit accommodation space S4.

The gear unit25has a large-diameter gear29which is fixed to the rotating shaft24, and a small-diameter gear30which is fixed to the rotating shaft15and engaged with the large-diameter gear29. The gear unit25transmits a rotating force such that the rotational frequency of the rotating shaft15increases with respect to the rotational frequency of the rotating shaft24(the speed of the rotating shaft15increases). The bearing26supports the rotating shaft24. The bearing27supports the rotating shaft15.

The oil tank28stores lubricating oil which is supplied to the respective sliding sites such as the bearing21, the bearing26, the bearing27, and the bearing31.

A sealing mechanism32and a sealing mechanism33which seal the periphery of the rotating shaft15are provided in the housing20between the compression flow path space S1and the first bearing accommodation space S2. Further, a sealing mechanism34which seals the periphery of the rotating shaft15is provided in the housing20between the compression flow path space S1and the gear unit accommodation space S4. Further, a sealing mechanism35which seals the periphery of the rotating shaft24is provided in the housing20between the gear unit accommodation space S4and the motor accommodation space S3. Further, a sealing mechanism36which seals the periphery of the rotating shaft24is provided in the housing20between the motor accommodation space S3and the second bearing accommodation space S5. Further, in the turbo refrigerator1of this embodiment, a sealing mechanism40which seals the periphery of the rotating shaft24between the bearing26and the gear unit25is provided in the gear unit accommodation space S4. The sealing mechanism40will be described in detail later.

The motor accommodation space S3is connected to the condenser2through a flow path R6. The refrigerant liquid X2is supplied from the condenser2to the motor accommodation space S3through the flow path R6. The refrigerant liquid X2supplied to the motor accommodation space S3flows around the stator22and cools the motor accommodation space S3by heat exchange between the stator22and the surroundings thereof. The motor accommodation space S3is connected to the evaporator4through a flow path R7. The refrigerant liquid X2having taken in heat in the motor accommodation space S3is supplied to the evaporator4through the flow path R7.

The oil tank28has an oil feed pump37. The oil feed pump37is connected to the second bearing accommodation space S5through, for example, a flow path R8. The lubricating oil is supplied from the oil tank28to the second bearing accommodation space S5through the flow path R8. The lubricating oil supplied to the second bearing accommodation space S5is supplied to the bearing31and secures the lubricity of a sliding site of the rotating shaft24and simultaneously reduces (cools) generation of heat at the sliding site. The second bearing accommodation space S5is connected to the oil tank28through a flow path R9. The lubricating oil supplied to the second bearing accommodation space S5returns to the oil tank28through the flow path R9.

In the turbo refrigerator1of this embodiment having such a configuration, the compressed refrigerant gas X1is cooled and condensed by the cooling water in the condenser2, and the cooling water is heated, whereby heat is exhausted. The refrigerant liquid X2produced by the condensation in the condenser2is decompressed by the expansion valve6and then supplied to the economizer3, and after the gas-phase component X3is separated out, the refrigerant liquid X2is further decompressed by the expansion valve7and then supplied to the evaporator4. The gas-phase component X3is supplied to the turbo compressor5through the flow path R3.

The refrigerant liquid X2supplied to the evaporator4evaporates in the evaporator4, thereby taking the heat of the cold water and thus cooling the cold water. In this way, the heat of the cold water before cooling is substantially transported to the cooling water which is supplied to the condenser2. The refrigerant gas X4produced due to the evaporation of the refrigerant liquid X2is supplied to the turbo compressor5, thereby being compressed, and is then supplied to the condenser2again.

A portion of the refrigerant liquid X2accumulated in the condenser2is supplied to the motor accommodation space S3through the flow path R6. The refrigerant liquid X2supplied to the motor accommodation space S3through the flow path R6cools the motor10accommodated in the motor accommodation space S3and is then returned to the evaporator4through the flow path R7.

The lubricating oil flowing through the flow path R8is supplied to the first bearing accommodation space S2, the second bearing accommodation space S5, and the gear unit accommodation space S4, thereby reducing the sliding resistance of the bearing21, the gear unit25, or the like.

Next, the sealing mechanism40will be described in detail with reference toFIG. 2.FIG. 2is an enlarged detailed view which includes the sealing mechanism40. As shown inFIG. 2, the sealing mechanism40is provided with a sealing body41, a sealing-body support part42, a bolt43, and an O-ring44(an elastic member).

The sealing body41is a ring-shaped member which surrounds the rotating shaft24when viewed from the axial direction, and is disposed on the side of the bearing26fixed to the housing20, as shown inFIG. 2. The sealing body41has a labyrinth groove41aat a portion facing the rotating shaft24and is disposed such that the labyrinth groove41afaces the circumferential surface of the rotating shaft24with a slight gap therebetween.

The sealing-body support part42is composed of a ring-shaped base portion42awhich is brought into contact with the housing20, and a ring-shaped cover portion42b. The base portion42aand the cover portion42bare disposed concentrically to be centered on the axis of the rotating shaft24and sandwich the sealing body41therebetween from the axial direction of the rotating shaft24. The contact surface between the base portion42aand the sealing body41and the contact surface between the cover portion42band the sealing body41are sliding surfaces, and thus when a large external force acts on the sealing body41in a radial direction of the rotating shaft24, the sealing body41becomes movable in the radial direction of the rotating shaft24. The bolt43is inserted into the base portion42aand the cover portion42band fastens these portions (that is, the sealing-body support part42) to the housing20.

The O-ring44is sandwiched between the sealing body41and the sealing-body support part42from the radial direction of the rotating shaft24. That is, the O-ring44is interposed between the sealing body41and the sealing-body support part42. The O-ring44surrounds the entire circumference of the sealing body41when viewed from the axial direction of the rotating shaft24and secures airtightness in the entire area of the gap between the sealing body41and the sealing-body support part42. The O-ring44is an elastic member made of resin or the like which is deformable at the time of the assembling of the turbo refrigerator1or when an external force acts on the sealing body41in the radial direction of the rotating shaft24.

In the turbo refrigerator1of this embodiment, the sealing body41surrounding the rotating shaft24is supported by the sealing-body support part42so as to be able to move in the radial direction of the rotating shaft24and the O-ring44which is an elastic member is interposed between the sealing body41and the sealing-body support part42. The O-ring44can be flexibly deformed, and therefore, it is possible to easily adjust the position of the sealing body41with respect to the rotating shaft24. Accordingly, it is possible to accurately perform the centering of the sealing body41with respect to the rotating shaft24by the O-ring44, and it becomes possible to make the gap between the sealing body41and the rotating shaft24narrower than that in the related art. Further, according to the turbo refrigerator1of this embodiment, even in a case where the rotating shaft24comes into contact with the sealing body41, impact due to the contact can be absorbed by the O-ring44. Accordingly, it becomes possible to make the gap between the sealing body41and the rotating shaft24narrower than that in the related art. Therefore, according to the turbo refrigerator1of this embodiment, it becomes possible to improve sealing performance in the sealing mechanism40.

Further, in the turbo refrigerator1of this embodiment, the labyrinth groove41ais provided in the portion facing the rotating shaft24, of the sealing body41. For this reason, compared to a case where the labyrinth groove41ais not provided in the portion facing the rotating shaft24, of the sealing body41, the shape of the gap between the sealing body41and the rotating shaft24becomes complicated, and thus it becomes possible to further improve the sealing performance.

Further, in the turbo refrigerator1of this embodiment, the O-ring44surrounds the entire circumference of the sealing body41when viewed from the axial direction of the rotating shaft24. For this reason, it is possible to prevent gas from leaking out from the gap between the sealing body41and the sealing-body support part42.

The preferred embodiment of the present invention has been described above with reference to the accompanying drawings. However, the present invention is not limited to the embodiment described above. The shapes, the combination, or the like of the respective constituent members shown in the embodiment described above is one example, and various changes can be made based on design requirements or the like within a scope of the present invention.

For example, in the embodiment described above, an example in which the sealing mechanism according to the present invention is applied to a turbo refrigerator has been described. However, the present invention is not limited thereto, and it is possible to apply the sealing mechanism according to the present invention to all devices in which it is necessary to seal the periphery of a rotating shaft.

Further, in the embodiment described above, a configuration in which the labyrinth groove41ais provided in the portion facing the rotating shaft24, of the sealing body41has been adopted. However, the present invention is not limited thereto, and it is also possible to adopt a configuration in which the labyrinth groove41ais not provided in the portion facing the rotating shaft24, of the sealing body41.

INDUSTRIAL APPLICABILITY

According to the present invention, it is possible to improve sealing performance in a sealing mechanism which is disposed around a rotating shaft which is installed in a turbo refrigerator or the like.

REFERENCE SIGNS LIST