JPWO2013175623A1 - Rotating machinery and refrigeration cycle equipment - Google Patents

Abstract

The rotating machine is disposed in the crankshaft (106), the bearing housing (107a) having a through hole (107b), and the through hole (107b), and the outer peripheral surface of the crankshaft (106) is interposed with lubricating oil. And a main bearing (108) that slides. The main bearing (108) has an upper bush (120), a lower bush (122), and an intermediate bush (121) disposed between the upper bush (120) and the lower bush (122). The intermediate bush (121) has a linear expansion coefficient larger than that of the bearing housing (107a), the upper bush (120), and the lower bush (122), and at least before the crankshaft (106) starts rotating, 106) is larger than the upper bush (120) and the lower bush (122). Thereby, the bearing loss at the time of fluid lubrication can be reduced, and the reliability as a bearing can be maintained even at the time of high load operation.

Description

  The present invention relates to a rotary machine and a refrigeration cycle apparatus, and more particularly to a rotary machine including a sliding bearing portion that slides on an outer peripheral surface of a rotating shaft via a lubricating oil, and a refrigeration cycle apparatus.

  A scroll compressor as a rotating machine is a compressor that compresses a gas such as a refrigerant by relatively rotating two scroll members having a spiral tooth shape. In the scroll compressor, generally, the other movable orbiting scroll is configured to orbit with respect to the fixed scroll restrained by screw fastening or welding.

  The orbiting scroll is provided with an orbiting slide bearing that engages and slides with the eccentric portion of the crankshaft. Then, while the eccentric portion of the crankshaft and the orbiting slide bearing slide through the lubricating oil, the swinging rotational motion of the eccentric portion of the crankshaft is transmitted to the orbiting scroll, and the orbiting scroll is caused to orbit. A crankshaft that is connected to the rotor of the electric motor and rotates is supported by sliding through a lubricant with respect to a journal slide bearing called a main bearing and a sub-bearing fixed in the scroll compressor.

  For example, in scroll compressors for refrigerant compression installed in air conditioners, it is generally known that reducing losses under low rotational speed and low load operating conditions is particularly effective for reducing power consumption throughout the air conditioner year. It has been. In recent years, reduction of bearing loss caused by sliding between a crankshaft and a slide bearing has been an issue under the low rotational speed and low load operating conditions.

  As a conventional technique for reducing the bearing loss, there is one disclosed in Japanese Patent Application Laid-Open No. 2003-239876 (Patent Document 1). According to Patent Document 1, “a floating ring member 110 is held in an insertion groove 8 a of a hub 8 formed in a lower part of the orbiting scroll 5 so as to be capable of rotating and idling. The slide bush 10 fixed to the eccentric part 4a is inserted to constitute a friction loss reducing device of the scroll compressor "(see summary).

  In general, it is known that in a sliding portion such as a bearing in which two surfaces slide through a lubricating oil, bearing loss due to oil film shear increases as the sliding speed increases. The technique described in Patent Document 1 has a structure in which a self-rotating floating ring member is disposed in a space between a slide bush and a hub fixed to an eccentric portion of a rotating shaft filled with lubricating oil. . As a result, the sliding that occurs between the slide bush fixed to the eccentric portion of the rotating shaft and the hub, the sliding between the outer periphery of the slide bush and the inner periphery of the floating ring member, and the outer periphery of the floating ring member and the hub It is possible to disperse and slide between the circumferences. For this reason, the relative sliding speed in each sliding part becomes small, and the bearing loss by oil film shearing is reduced.

  As another prior art, there is one described in Japanese Patent Application Laid-Open No. 2008-101538 (Patent Document 2). This Patent Document 2 states that “the bearing has a main bearing 6c that supports the main shaft portion 7a and a crank bearing 4c that supports the crank portion 7b. The main bearing 6c includes the crank side main bearing 6c1 and the crank side. The crank bearing 4c and the crank side main bearing 6c1 are constituted by carbon bearings in which pores of a carbonaceous base material containing graphite are impregnated with metal, which are adjacent to the main bearing. The bearing 6c2 is composed of a wound bush formed by winding a plate material "(see abstract).

  In the technique described in Patent Document 2, the crank bearing and the crank side main bearing, which are high load portions with high surface pressure, are constituted by carbon bearings, so that reliability such as wear resistance and seizure resistance in a boundary lubrication state is achieved. Is secured.

  Still another conventional technique is described in Japanese Patent Laid-Open No. 9-250465 (Patent Document 3). In Patent Document 3, “at least one of the slewing bearing, the main bearing, and the sub-bearing has an oil-impregnated porous body in a surface in sliding contact with the crankshaft. It is described as “a scroll compressor” characterized in that a surface other than the surface in sliding contact with the shaft is surrounded by a member that does not penetrate oil (see claim 1). Further, “at least one of the slewing bearing, the main bearing, and the sub-bearing is an elastic body in which both ends of the surface slidingly contacting the crankshaft do not permeate oil, and the surfaces other than the both ends are oil-containing porous. The surface of the oil-containing porous body other than the surface in sliding contact with the crankshaft is surrounded by the elastic body or a member that does not penetrate oil ”(see claim 6).

  According to the technology described in Patent Document 3, the performance of the bearing is improved, and in an environment where the lubrication state is severe, such as when oil is out, a piece hit, a non-steady state such as refrigerant foaming, or when using alternative CFCs with poor lubricity. The odor can also ensure compression performance and reliability.

JP 2003-239876 A JP 2008-101538 A JP-A-9-250465

  However, in the technique described in Patent Document 1, as the rotational speed of the rotary shaft decreases, it becomes more difficult to form an oil film than a general slide bearing, and direct contact with the floating ring member is likely to occur. There are challenges.

  Further, in the technique described in Patent Document 2, by using a carbon bearing having lubricity, it is caused by contact friction when the crankshaft and the bearing slide with direct contact in a state where oil film formation is difficult. Bearing losses can be reduced. However, at the time of normal oil film formation, there is almost no effect of reducing the shear resistance of the oil film, and therefore the bearing loss is not reduced or very limited.

  Further, the technique described in Patent Document 3 promotes the inflow of lubricating oil from the oil-containing porous body into the gap between the shaft and the bearing when oil film formation becomes difficult, and prevents direct contact between the shaft and the bearing. This is effective in reducing bearing loss. However, at the time of normal oil film formation, there is almost no effect of reducing the shear resistance of the oil film, and therefore the bearing loss is not reduced or very limited.

  The object of the present invention is to reduce the bearing loss during fluid lubrication and reduce the bearing loss during fluid lubrication by reducing the shear resistance of the oil film due to the lubricating oil existing between the outer peripheral surface of the rotating shaft and the sliding bearing. It is another object of the present invention to provide a rotating machine and a refrigeration cycle apparatus that can maintain reliability as a bearing.

  In order to achieve the above-described object, a rotating machine reflecting one aspect of the present invention includes a rotating shaft, a housing portion having a hole into which the shaft is inserted, and an axial direction of the housing portion in the hole. A first bearing portion disposed closest to one end, a second bearing portion disposed closest to the other end, and a linear expansion coefficient disposed between the first bearing portion and the second bearing portion; Is larger than the housing portion, the first bearing portion, and the second bearing portion, and at least a gap between the shaft and the outer peripheral surface before the shaft starts to rotate is the first bearing portion and the first bearing portion. A sliding bearing having an intermediate bearing portion larger than two bearing portions and sliding with respect to the outer peripheral surface of the shaft via lubricating oil.

  Moreover, the refrigeration cycle apparatus reflecting one aspect of the present invention includes the rotary machine as a refrigerant compressor for refrigeration or air conditioning.

  According to the present invention, by reducing the shear resistance of the oil film due to the lubricating oil existing between the outer peripheral surface of the rotating shaft and the slide bearing, it is possible to reduce bearing loss during fluid lubrication, It is possible to provide a rotating machine and a refrigeration cycle apparatus that can maintain reliability as a bearing even during a load operation.

It is a longitudinal section showing a scroll compressor concerning a 1st embodiment of the present invention. It is an expanded sectional view near the main bearing in the scroll compressor as a comparative example. It is an expanded sectional view near the main bearing in the scroll compressor concerning a 1st embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view of the vicinity of a main bearing when the scroll compressor shown in FIG. 1 is operating at a high load. It is a graph which shows the relationship between the expansion ratio of the clearance gap between an intermediate | middle bush and a crankshaft, and a relative bearing loss. It is a graph which shows the relationship between the expansion rate of the clearance gap between an intermediate bush and a crankshaft, and a relative minimum oil film thickness. It is an expanded sectional view near the main bearing concerning the 1st modification of a 1st embodiment. It is an expanded sectional view near the main bearing which concerns on the 2nd modification of 1st Embodiment. It is an expanded sectional view near the main bearing concerning the 3rd modification of a 1st embodiment. It is an expanded sectional view near the main bearing concerning the 4th modification of a 1st embodiment. It is a longitudinal cross-sectional view which shows the rotary compressor which concerns on 2nd Embodiment of this invention.

Next, embodiments of the present invention will be described in detail with reference to the drawings as appropriate.
<< First Embodiment >>
First, a first embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a longitudinal sectional view showing a scroll compressor 100 according to the first embodiment of the present invention. That is, in this 1st Embodiment, the rotary machine of this invention is demonstrated using the example of the scroll compressor 100 which compresses refrigerant | coolant gas.

  As shown in FIG. 1, the scroll compressor 100 is a hermetic compressor used for refrigerating and air conditioning such as an air conditioner such as an air conditioner or a refrigeration apparatus. The scroll compressor 100 includes a sealed container 102 that forms a casing, and a fixed scroll 103 and a turning scroll 104 that orbits and engages with the fixed scroll 103 are provided in an upper portion of the sealed container 102. ing. The fixed scroll 103 and the orbiting scroll 104 each have a spiral tooth shape portion.

  Further, an electric motor 105 as a rotational power source is provided in the sealed container 102, and a crankshaft (shaft) 106 is connected to the rotor of the electric motor 105. A crankshaft 106 that is connected to the electric motor 105 and rotates is provided by a main bearing (slide bearing) 108 provided on a frame 107 fixed in the sealed container 102 and a sub-bearing 110 provided on a lower frame 109. It is supported rotatably.

  An eccentric portion 106 a having an eccentricity with respect to the axial center of the portion of the crankshaft 106 supported by the main bearing 108 and the auxiliary bearing 110 is provided on the upper portion of the crankshaft 106. The eccentric portion 106a slides by engaging with the orbiting bearing 112 provided on the lower surface (rear surface) side of the end plate 104a of the orbiting scroll 104, so that the swinging rotational motion (eccentric motion) of the eccentric portion 106a is the orbiting scroll. 104.

  The rotation of the orbiting scroll 104 is restricted by the Oldham ring 113, and the orbiting scroll 104 orbits with respect to the fixed scroll 103. The Oldham ring 113 is attached to a groove formed on the lower surface (back surface) side of the end plate 104 a of the orbiting scroll 104 and a groove formed on the frame 107. When the orbiting scroll 104 orbits through the crankshaft 106 driven to rotate by the electric motor 105, a low-pressure refrigerant gas is sucked from the suction port 114 and led to a compression chamber formed by the orbiting scroll 104 and the fixed scroll 103. . Here, the refrigerant gas is reduced in volume and compressed as it moves in the center direction of the scrolls 103 and 104, and then discharged to the outside through the discharge port 115.

  An oil supply hole 116 that penetrates from the lower end to the end face (upper end face) side of the eccentric portion 106a is provided in the crankshaft 106 along the axial direction. Lubricating oil 117 stored in the lower part of the sealed container 102 is supplied to the oil supply hole by a pressure difference described later using the discharge pressure of the refrigerant gas or by a pump (not shown) separately attached to the lower end of the crankshaft 106. It is configured to be pushed up through 116 and supplied to a gap between the inner peripheral surface of each bearing (main bearing 108, sub-bearing 110, slewing bearing 112) and the outer peripheral surface of the crankshaft 106.

  Here, the inside of the sealed container 102 is at a discharge pressure, and an intermediate chamber (back pressure chamber) 118 formed on the lower surface side of the end plate 104a of the orbiting scroll 104 is an intermediate pressure between the discharge pressure and the suction pressure. It has become. For this reason, the lubricating oil 117 stored in the lower portion of the sealed container 102 is supplied to the bearings 108, 110, 112, and the like through the oil supply holes 116 due to a pressure difference between the discharge pressure and the intermediate pressure.

  FIG. 2 is an enlarged cross-sectional view of the vicinity of the main bearing 208 in the scroll compressor as a comparative example. In addition, in FIG. 2, since it is sectional drawing seen from the extension direction of the straight line orthogonal to the axial center of the crankshaft 106 and the axial center of the eccentric part 106a, both axial centers are seen overlapping (other expansion) The same applies to the sectional view). As shown in FIG. 2, the main bearing 208 according to the comparative example includes two cylindrical sliding bearing bushes in a through hole 107 b formed inside a bearing housing 107 a provided in a part of the frame 107. The upper bush 120 and the lower bush 122 are arranged side by side in the axial direction.

  Specifically, the upper bush 120 is disposed on the side close to the eccentric part 106a, and the lower bush 122 is disposed on the side far from the eccentric part 106a. Lubricating oil is supplied to the gap between the outer peripheral surface of the crankshaft 106 and the inner peripheral surface of the main bearing 208 (the upper bush 120 and the lower bush 122) through the oil supply hole 116 and the oil supply port 119. And the inner peripheral surface of the main bearing 208 slide through an oil film. The lubricating oil that has formed the oil film then flows out of the bearing housing 107a through the end of the bearing housing 107a.

  FIG. 3 is an enlarged cross-sectional view of the vicinity of the main bearing 108 in the scroll compressor 100 according to the first embodiment of the present invention. As shown in FIG. 3, the main bearing 108 according to the first embodiment includes a through hole (hole) 107b formed inside a bearing housing (housing portion) 107a provided in a part of a frame 107 made of cast iron, for example. The upper bush (first bearing portion) 120, the intermediate bush (intermediate bearing portion) 121, and the lower bush (second bearing portion) 122, which are three cylindrical plain bearing bushes, are arranged in the order from above. It has a structure arranged side by side.

  Specifically, the upper bush 120 is disposed closest to one end (on the eccentric part 106a side) in the axial direction in the through hole 107b, that is, on the side closest to the eccentric part 106a. Further, the lower bush 122 is disposed closest to the other end (on the opposite side to the eccentric portion 106a) in the axial direction in the through hole 107b, that is, on the side farthest from the eccentric portion 106a. The intermediate bush 121 is disposed between the upper bush 120 and the lower bush 122.

  The upper bush 120 and the lower bush 122 are made of a carbon bearing material in which, for example, a carbonaceous substrate containing graphite is impregnated with a metal. On the other hand, the intermediate bush 121 includes a carbon bearing material that forms the upper bush 120 and the lower bush 122 and a material that exhibits a higher linear expansion coefficient than the cast iron material that forms the bearing housing 107a, such as a resin. Consists of materials.

  Further, at least before the rotation of the crankshaft 106 is started, the gap between the intermediate bush 121 and the outer peripheral surface of the crankshaft 106 is the gap between the upper bush 120 and the outer peripheral surface of the crankshaft 106, and the lower bush 122. And the clearance between the outer peripheral surface of the crankshaft 106 is larger. That is, the difference between the inner diameter of the intermediate bush 121 and the outer diameter of the crankshaft 106 is larger than the difference between the inner diameter of the upper bush 120 and the outer diameter of the crankshaft 106, and the inner diameter of the lower bush 122 and the crankshaft 106. It is larger than the difference with the outer diameter.

  An oil supply hole 116 is formed in a gap (hereinafter also referred to as “bearing gap”) between the outer peripheral surface of the crankshaft 106 and the inner peripheral surface of the main bearing 108 (the upper bush 120, the intermediate bush 121, and the lower bush 122). The lubricating oil is supplied through the oil supply port 119, and the outer peripheral surface of the crankshaft 106 and the inner peripheral surface of the main bearing 108 slide through an oil film. The lubricating oil that has formed the oil film then flows out of the bearing housing 107a through the end of the bearing housing 107a.

Next, the operation of the first embodiment configured as described above will be described.
The oil film shear force generated at the interface between the rotating shaft (for example, the crankshaft 106) that slides through the oil film and the cylindrical bearing (for example, the main bearing 108) is a relation of the equation (1) generally called Petrov's equation. It is known to have
F = τA = η (V / h) A (1)
Here, F is the oil film shear force, τ is the oil film shear stress, η is the absolute viscosity, V is the peripheral speed of the rotating shaft, h is the radial gap (oil film thickness), and A is the area of the inner circumference of the bearing related to the oil film shear. is there.

  In the first embodiment of the present invention shown in FIG. 3 and the comparative example shown in FIG. 2, the total area of the inner peripheral surfaces of all the sliding bearing bushes is equal, and the inner diameters of the upper bush 120 and the lower bush 122 are the same. In the first embodiment of the present invention, since the radial gap h is set to be larger than that of the comparative example in the intermediate bush 121 portion, the oil film shear force and consequently the bearing loss is reduced as compared with the comparative example.

  If an attempt is made to enlarge the gap between the crankshaft 106 and the main bearing 208 in order to reduce the oil film shear force in the structure of the comparative example shown in FIG. 2, the flow rate of the lubricating oil through the gap increases, There is concern about the increase in the loss of the scroll compressor. However, in the structure of the first embodiment of the present invention shown in FIG. 3, the gap in the upper bush 120 and the lower bush 122 that are the outflow path of the lubricating oil is smaller than the gap in the intermediate bush 121 part. Therefore, even if the gap at the intermediate bush 121 is enlarged, the flow rate of the lubricating oil through the gap between the crankshaft 106 and the main bearing 108 hardly increases, and an increase in loss due to this is prevented.

  Further, the material, thickness, and inner diameter of the upper bush 120, the intermediate bush 121, and the lower bush 122, which are sliding bearing bushes, and the bearing housing 107a are determined according to the operating conditions and operating temperature of the scroll compressor 100. By doing so, it is possible to secure a load (load capacity) that can be supported by the main bearing 108 at the time of high-load operation equivalent to the conventional one, and to maintain the reliability as the bearing.

  FIG. 4 is an enlarged cross-sectional view of the vicinity of the main bearing 108 when the scroll compressor 100 shown in FIG. 1 is operating at a high load. FIG. 4 shows a state where the crankshaft 106 is slightly inclined with respect to the main bearing 108 during high load operation (the same applies to FIGS. 9 and 10). The reason why the crankshaft 106 is inclined will be described later.

  As shown in FIG. 4, during high load operation in which the rotational speed of the crankshaft 106 and the gas load 123 acting on the crankshaft 106 by the refrigerant gas are large, the portion due to the increase in the peripheral speed V and eccentricity of the crankshaft 106 The oil film shear force F increases due to a decrease in the radial gap h (see formula (1)). The temperature of the main bearing 108 (hereinafter also referred to as “bearing temperature”) rises due to the increase in oil film shear heat generation and the increase in gas temperature in the scroll compressor 100 accompanying this. In response to this temperature rise, the crankshaft 106, the bearing housing 107a, and the upper bush 120, the intermediate bush 121, and the lower bush 122, which are sliding bearing bushes, each cause thermal expansion.

  In the first embodiment of the present invention, since the linear expansion coefficient of the intermediate bush 121 is particularly large, the clearance between the intermediate bush 121 and the crankshaft 106 is lower during high load operation (see FIG. 4). It becomes smaller than during operation (see FIG. 3). Therefore, in the state at the time of high load operation, the region where a high oil film pressure can be maintained by the dynamic pressure is expanded compared to the state at the time of low load operation, thereby increasing the load capacity of the bearing.

  As shown in FIG. 4, the gas load 123 acts on the crankshaft 106 as an overhanging load at a position above the main bearing 108, so that the inclination of the crankshaft 106 with respect to the main bearing 108 is an operating load. It is easy to expand with the increase. For this reason, direct contact between the crankshaft 106 and the main bearing 108 tends to occur at the bearing end portions indicated by A and B in FIG. In the example shown in FIG. 3, since the upper bush 120 and the lower bush 122 are made of a hard and lubricating carbon bearing material, it is difficult to form an oil film, and the crankshaft 106 and the main bearing 108 are directly connected to each other. Even when it is in a state of sliding with contact, good wear resistance can be obtained.

Next, evaluation regarding bearing loss due to oil film shear will be described.
A main bearing 108 having an upper bush 120, an intermediate bush 121, and a lower bush 122, which are three plain bearing bushes as shown in FIG. 3, is disposed in the through hole 107b of the bearing housing 107a. In contrast, the bearing loss due to oil film shearing when the crankshaft 106 was slid through the lubricating oil was evaluated. Then, the influence of the gap between the intermediate bush 121 and the crankshaft 106 on the bearing loss and the minimum oil film thickness in the bearing structure according to the first embodiment of the present invention was verified. The verification results are shown in FIGS.

  In this verification, in the scroll compressor 100 for an air conditioner, it was assumed that the crankshaft 106 had a diameter of 14 to 18 mm. Further, the upper bush 120, the intermediate bush 121, and the lower bush 122 have the same axial length and the same diameter as the crankshaft 106. The clearances between the upper bush 120 and the lower bush 122 and the crankshaft 106 were equally 0.15% of the diameter of the crankshaft 106. The inclination angle of the crankshaft 106 with respect to the main bearing 108 was set to 0.01 ° in the acting load direction.

  FIG. 5 is a graph showing the result of evaluating the bearing loss by variously changing the enlargement ratio of the gap between the intermediate bush 121 and the crankshaft 106. That is, FIG. 5 shows the relationship between the expansion ratio of the gap between the intermediate bush and the crankshaft and the relative bearing loss. In FIG. 5, the horizontal axis indicates an increase in the gap between the intermediate bush 121 and the crankshaft 106 when the gap between the upper bush 120 and the lower bush 122 and the crankshaft 106 is set as a reference (0%). Indicates the rate. The vertical axis shows the relative value when the bearing loss is 100% when the gaps between the upper bush 120, the intermediate bush 121, and the lower bush 122 and the crankshaft 106 are all equal. Yes. As shown in the verification results of FIG. 5, the bearing loss tended to decrease by increasing the gap between the intermediate bush 121 and the crankshaft 106.

  FIG. 6 is a graph showing the results of evaluating the minimum oil film thickness by changing the expansion ratio of the gap between the intermediate bush 121 and the crankshaft 106 in various ways. That is, FIG. 6 shows the relationship between the expansion ratio of the gap between the intermediate bush and the crankshaft and the relative minimum oil film thickness. In FIG. 6, the horizontal axis indicates an increase in the gap between the intermediate bush 121 and the crankshaft 106 when the gap between the upper bush 120 and the lower bush 122 and the crankshaft 106 is set as a reference (0%). Indicates the rate. The vertical axis represents the relative value when the minimum oil film thickness is 100% when the gaps between the upper bush 120, the intermediate bush 121, and the lower bush 122 are all equal to the crankshaft 106. Show. Here, the minimum oil film thickness is the minimum oil film thickness when the same load is supported. As shown in the verification result of FIG. 6, the minimum oil film thickness tended to increase by reducing the gap between the intermediate bush 121 and the crankshaft 106.

  As described above, the scroll compressor 100 according to the first embodiment of the present invention includes the crankshaft 106 that rotates and the bearing housing 107a having the through-hole 107b into which the crankshaft 106 is inserted, and the through-hole of the bearing housing 107a. And a main bearing 108 that is disposed in the hole 107b and slides on the outer peripheral surface of the crankshaft 106 via lubricating oil. The main bearing 108 has an upper bush 120 disposed closest to one end in the axial direction in the through hole 107b of the bearing housing 107a, a lower bush 122 disposed closest to the other end, and the upper bush 120. And an intermediate bush 121 disposed between the lower bush 122 and the lower bush 122. The intermediate bush 121 has a linear expansion coefficient larger than that of the bearing housing 107a, the upper bush 120, and the lower bush 122, and at least a gap between the outer periphery of the crankshaft 106 before the crankshaft 106 starts rotating. Is larger than the upper bush 120 and the lower bush 122.

  That is, in the first embodiment of the present invention, among the components of the main bearing 108 that supports the rotation of the crankshaft 106 while causing oil film shearing of the lubricating oil, the intermediate bush 121 arranged at the center is provided at both ends. It is made of a material having a linear expansion coefficient larger than that of the upper bush 120 and the lower bush 122, and at least between the crankshaft 106 and the upper bush 120 and the lower bush 122 before the crankshaft 106 starts rotating. The gap between is large. This gap relationship is maintained in the same way even during high-temperature operation (where the bearing temperature is high) and during low-temperature operation where the rotational speed and working load of the crankshaft 106 are small (the bearing temperature is low). Be drunk. Then, the inner diameter dimensional change rate (reduction rate) of the intermediate bush 121 due to the temperature change becomes larger than the inner diameter dimensional change rate (reduction rate) of the upper bush 120 and the lower bush 122.

  Accordingly, during low load operation where the rotational speed of the crankshaft 106 and the load acting on the crankshaft 106 are small, the gap between the intermediate bush 121 and the crankshaft 106 is large, so that friction loss is reduced and bearing loss is reduced. To do. Further, since the gaps at the upper bush 120 and the lower bush 122, which are the outflow paths of the lubricating oil, are small, the increase in the flow rate of the lubricating oil hardly occurs, and an increase in loss due to this is prevented. On the other hand, at the time of high load operation in which the rotational speed of the crankshaft 106 and the load acting on the crankshaft 106 are large, the gap between the intermediate bush 121 and the crankshaft 106 is reduced due to temperature change, and the oil film pressure at this portion due to dynamic pressure is reduced. Therefore, the minimum oil film thickness and the load capacity (load support capacity) of the bearing increase.

  That is, according to the first embodiment of the present invention, by reducing the shear resistance of the oil film caused by the lubricating oil existing between the outer peripheral surface of the rotating crankshaft 106 and the main bearing 108, the bearing at the time of fluid lubrication. Loss can be reduced, and reliability as a bearing can be maintained even during high load operation.

(Material of upper bush and lower bush)
As the material of the upper bush 120 and the lower bush 122, a carbon-based, metal-based, or ceramic-based material having a linear expansion coefficient smaller than that of the intermediate bush 121 can be used. In the example shown in FIG. 3, a carbon bearing material in which a metal is impregnated with a carbonaceous base material containing graphite is used with emphasis on ensuring wear resistance at the time of one-piece contact and direct contact friction due to oil film breakage. However, as materials of the upper bush 120 and the lower bush 122, for example, cast iron, carbon steel, copper alloy, brass, tin alloy, aluminum alloy according to the wear resistance and environment resistance required for the rotating machine to be applied. Zirconia, alumina, silicon carbide, silicon nitride, etc. may be used.

(Material of intermediate bush)
As the material of the intermediate bush 121, a resin material having a larger linear expansion rate than the material of the upper bush 120 and the lower bush 122 can be used. However, as the material of the intermediate bush 121, polytetrafluoroethylene, polyether ether ketone, polyphenylene sulfide, nylon, polyimide, polyamideimide, polyethylene, depending on the temperature conditions of the rotating machine to be applied and the expected change in bearing clearance Ultra high molecular weight polyethylene and the like, and composite materials of these resins and sintered metals, particles, fiber materials, and the like may be used.

(First modification)
FIG. 7 is an enlarged cross-sectional view of the vicinity of the main bearing 108a according to the first modification of the first embodiment. The detailed description of the same configuration and operation as those of the first embodiment shown in FIGS. 1 to 6 will be omitted as they are incorporated in the first modification, and different points will be described (further described below). The same applies to the modified example).

  As shown in FIG. 7, the first modification of the first embodiment is different from the first embodiment in that the lower bush 122a of the main bearing 108a is formed integrally with the bearing housing 107a. Note that the upper bushing may be formed integrally with the bearing housing 107a instead of the lower bushing 122a. That is, instead of installing the upper bush 120 and the lower bush 122 as separate members in the bearing housing 107a as in the first embodiment, the lower bush 122a (or the upper bush) is integrated with the bearing housing 107a. According to such a first modification of the first embodiment, in addition to being able to achieve the same operational effects as those of the first embodiment described above, it is possible to reduce the assembly cost by reducing the number of parts. Become.

(Second modification)
FIG. 8 is an enlarged cross-sectional view of the vicinity of the main bearing 108b according to the second modification of the first embodiment.
As shown in FIG. 8, in the second modification of the first embodiment, the outer diameter of the crankshaft 106 is smaller than the other portions in the portion of the main bearing 108b that faces the intermediate bush 121a. That is, the method of enlarging the bearing gap at the center of the main bearing 108b is to increase the outer diameter of the crankshaft 106 at the portion facing the intermediate bush 121a instead of increasing the inner diameter of the intermediate bush 121 as in the first embodiment. It is also possible to make it smaller.

  In the structure according to the first embodiment shown in FIG. 3, the coaxiality of the inner peripheral surfaces of the upper bush 120, the intermediate bush 121, and the lower bush 122, which are three plain bearing bushes, is obtained with high accuracy. In order to efficiently machine the inner diameter by one axial feed, the three slide bearing bushes are inserted into the bearing housing 107a and heated to the temperature during the high load operation of the scroll compressor 100. It is necessary to devise a processing process such as processing the inner diameter of each plain bearing bush to the same diameter. On the other hand, in the structure according to the second modification example of the first embodiment shown in FIG. 8, the inner diameters of the upper bush 120, the intermediate bush 121a, and the lower bush 122, which are three plain bearing bushes, are set to be equal at room temperature. The same diameter can be processed by one axial feed. According to such a second modification of the first embodiment, it is possible to reduce the manufacturing cost in addition to the same effects as the first embodiment described above.

(Third Modification)
FIG. 9 is an enlarged cross-sectional view of the vicinity of the main bearing 108c according to a third modification of the first embodiment.
As shown in FIG. 9, in the third modification of the first embodiment, at least one groove 124 that divides the inner peripheral surface in the circumferential direction is formed on the inner peripheral surface of the intermediate bush 121b. According to the third modification of the first embodiment, in addition to being able to achieve the same operational effects as those of the first embodiment described above, by providing the groove 124, the intermediate bush 121b can be In addition to relieving the internal stress in the circumferential direction and reducing variations in the inner diameter change due to temperature rise, the sliding area is reduced by the amount of the groove 124, so that the bearing loss can be further reduced.

(Fourth modification)
FIG. 10 is an enlarged cross-sectional view of the vicinity of the main bearing 108d according to a fourth modification of the first embodiment.
As shown in FIG. 10, in the fourth modification of the first embodiment, a groove 124a that divides the inner peripheral surface in the circumferential direction is formed on the inner peripheral surface of the intermediate bush 121c. The intermediate bush 121c has a V-shape extending from both end portions in the axial direction toward the central portion so as to incline in the rotation direction of the crank shaft 106. According to such a fourth modification of the first embodiment, in addition to the same operational effects as the third modification of the first embodiment described above, the following operational effects are further exhibited. . That is, the lubricating oil passes through the groove 124a and is moved from the both end portions in the axial direction of the intermediate bush 121c to the central portion, and the pressure near the central portion increases. For this reason, it is possible to increase the minimum oil film thickness by improving the dynamic pressure especially at high load.

<< Second Embodiment >>
Next, a second embodiment of the present invention will be described with reference to FIG.
FIG. 11 is a longitudinal sectional view showing a rotary compressor 130 according to the second embodiment of the present invention. That is, in this 2nd Embodiment, the rotary machine of this invention is demonstrated using the example of the rotary compressor 130 which compresses refrigerant gas.

  As shown in FIG. 11, the rotary compressor 130 functionally includes a vertical cylindrical sealed container 138, a compression mechanism 139 that compresses refrigerant gas in the sealed container 138, and an electric motor that drives the compression mechanism 139. 131 and an oil sump 144 for storing lubricating oil to be supplied to the sliding surfaces of the components and members constituting the compression mechanism 139. In the sealed container 138, an electric motor 131, a compression mechanism 139, and an oil sump 144 are arranged in order from the top.

  A rotating shaft (shaft) 132 extending downward is connected to the rotor of the electric motor 131. The compression mechanism 139 includes an eccentric shaft portion 132a formed near the lower tip portion of the rotary shaft 132, and a cylindrical roller 133 that is eccentrically rotated by the eccentric shaft portion 132a when the eccentric shaft portion 132a is engaged inside. , A cylinder 134 that houses the eccentric shaft portion 132a and the roller 133, an upper bearing member 135 that serves as an upper lid of the cylinder 134 and supports the rotating shaft 132, and a lower lid of the cylinder 134 and supports the lower end portion of the rotating shaft 132. And a vane (not shown) that slides on the outer peripheral surface of the roller 133 and separates the low pressure side and the high pressure side of the compression chamber 137 from each other.

  The upper bearing member 135 has a bearing housing (housing portion) 135 a provided in a part of the upper bearing member 135. A through hole (hole) 135b into which the rotary shaft 132 is inserted is formed in the bearing housing 135a, and an upper bearing (slide bearing) 143 is disposed in the through hole 135b. The upper bearing 143 includes an upper bush (first bearing portion) 140 and an intermediate bush (intermediate bearing portion) 141 that are three cylindrical slide bearing bushes in a through hole 135b formed inside the bearing housing 135a. The lower bush (second bearing portion) 142 is arranged in the axial direction in order from above.

  Specifically, the upper bush 140 is disposed closest to one end (on the side opposite to the eccentric shaft portion 132a) in the axial direction in the through hole 135b, that is, on the side farthest from the eccentric shaft portion 132a. The lower bush 142 is disposed closest to the other end (on the eccentric shaft portion 132a side) in the axial direction in the through hole 135b, that is, on the side closest to the eccentric shaft portion 132a. The intermediate bush 141 is disposed between the upper bush 140 and the lower bush 142.

  The material of the upper bush 140 and the lower bush 142 is, for example, cast iron. The lower bushing 142 (including the sliding surface that is the inner peripheral surface thereof) is formed integrally with the bearing housing 135a of the upper bearing member 135. On the other hand, the intermediate bush 141 is made of a material whose linear expansion coefficient is larger than the linear expansion coefficients of the upper bush 140 and the lower bush 142 and larger than the linear expansion coefficient of the bearing housing 135a, for example, a material containing resin. Has been.

  In addition, at least before the rotation of the rotary shaft 132 is started, the gap between the intermediate bush 141 and the outer peripheral surface of the rotary shaft 132 is the gap between the upper bush 140 and the outer peripheral surface of the rotary shaft 132 and the lower bush 142. And the clearance between the outer peripheral surface of the rotary shaft 132 and the outer peripheral surface of the rotary shaft 132 is larger. Here, the outer diameter of the rotating shaft 132 is smaller in the portion facing the intermediate bush 141 of the upper bearing 143 than in the other portions. That is, the difference between the inner diameter of the intermediate bush 141 and the outer diameter of the rotating shaft 132 at the portion facing the intermediate bush 141 is larger than the difference between the inner diameter of the upper bush 140 and the outer diameter of the rotating shaft 132, and It is larger than the difference between the inner diameter of the bush 142 and the outer diameter of the rotating shaft 132.

  A lower bearing 145 (including a sliding surface that is an inner peripheral surface) that is a slide bearing that supports the lower end portion of the rotating shaft 132 is formed integrally with a lower bearing member 136 made of cast iron. Lubricating oil 117 in an oil sump 144 provided at the lower portion of the rotary compressor 130 passes through an oil supply hole 146 formed along the axial center of the rotary shaft 132 through a branch hole in the radial direction, and the upper bearing 143 and the lower bearing. 145, and a sliding portion of each of the bearings 143 and 145 is formed with an oil film by lubricating oil to ensure smooth lubrication.

  In the above-described second embodiment of the present invention, during low load operation where the rotational speed of the rotary shaft 132 and the load acting on the rotary shaft 132 are small, the gap between the intermediate bush 141 and the rotary shaft 132 is large. Is reduced and bearing loss is reduced. Further, since the gap in the upper bush 140 and the lower bush 142, which is the lubricating oil outflow path, is small, the flow rate of the lubricating oil hardly increases and an increase in loss due to this is prevented. On the other hand, during a high load operation in which the rotational speed of the rotating shaft 132 and the load acting on the rotating shaft 132 are large, the gap between the intermediate bush 141 and the rotating shaft 132 is reduced due to temperature change, and the oil film pressure at this portion due to dynamic pressure is reduced. Therefore, the minimum oil film thickness and the load capacity (load support capacity) of the bearing increase.

  That is, according to the second embodiment of the present invention, by reducing the shear resistance of the oil film due to the lubricating oil existing between the outer peripheral surface of the rotating shaft 132 that rotates and the upper bearing 143, the bearing at the time of fluid lubrication Loss can be reduced, and reliability as a bearing can be maintained even during high load operation.

  Further, in the rotary compressor 130 according to the second embodiment of the present invention, the bearings 143 and 145 are provided at positions close to the compression chamber 137. In addition, the lower bush 142 and the lower bearing 145 located at the end of the upper bearing member 135 on the roller 133 side function as sliding bearing bushes, and the sliding surfaces that are the inner peripheral surfaces thereof are bearing members 135 and 136. And are integrally formed. This eliminates fluid movement in portions other than the bearing gap, such as the inside of the material of the sliding bearing bush, as in the case where the sliding bearing bush is configured separately from the bearing members 135 and 136. Therefore, it is easy to control the inflow / outflow relationship of gas and lubricating oil between the bearings 143 and 145 and the compression chamber 137, and the design becomes easy.

  As mentioned above, although this invention was demonstrated based on embodiment, this invention is not limited to above-described embodiment, Various modifications are included. For example, the above-described embodiment has been described in detail for easy understanding of the present invention, and is not necessarily limited to one having all the configurations described. Further, a part of the configuration of an embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of an embodiment. In addition, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

  For example, in the above-described embodiment, the upper bush, the intermediate bush, and the lower bush, which are three plain bearing bushes, are arranged in the axial direction in order from above in a through hole formed inside the bearing housing. It has a structure. However, the present invention is not limited to this, and can be applied to a structure in which four or more plain bearing bushes are arranged side by side in the axial direction. In this case, the sliding bearing bushes at both ends in the axial direction correspond to the upper bushing and the lower bushing in the embodiment, and at least of the plurality of sliding bearing bushes disposed between the sliding bearing bushes at both axial ends. One corresponds to the intermediate bush in the embodiment.

  Further, for example, in the second modification of the first embodiment, a method of reducing the outer diameter of the crankshaft 106 at a portion facing the intermediate bush 121a is adopted as a method of expanding the bearing gap at the center portion of the main bearing 108b. However, the present invention is not limited to this. For example, the inner diameter of the intermediate bush 121 may be enlarged, and the outer diameter of the crankshaft 106 at the portion facing the intermediate bush 121a may be reduced.

  For example, in the 3rd modification of 1st Embodiment, although the groove | channel 124 which divides | segments the said internal peripheral surface into the circumferential direction was formed in the internal peripheral surface of the intermediate bush 121b, this invention is based on this. It is not limited. The present invention is also applicable to the case where the depth of the groove 124 reaches the outer peripheral surface of the intermediate bush 121b, for example. In other words, the intermediate bush 121b may be configured to be divided into a plurality of portions in the circumferential direction by a dividing surface along the axial direction, and to include a plurality of portions forming a part of a cylindrical shape.

  Moreover, although the case where the present invention is applied to a scroll compressor and a rotary compressor has been described in the above embodiment, the present invention is not limited to these and can be applied to other types of compressors. is there. Moreover, although the said embodiment demonstrated the vertical compressor with which the axis | shaft which rotationally moves is arrange | positioned along a perpendicular direction, this invention is not limited to this, The axis | shaft which rotationally moves is horizontal. The present invention can also be applied to a horizontal compressor arranged along. Furthermore, the present invention can also be applied to various types of rotating machines that include a sliding bearing portion that slides on the outer peripheral surface of a rotating shaft via a lubricating oil.

  Moreover, this invention can be comprised as a refrigerating-cycle apparatus provided with the rotary machine which concerns on this invention as a refrigerant compressor for refrigeration or an air conditioning. This refrigeration cycle equipment includes a refrigerant compressor as a rotating machine according to the present invention, a condenser that dissipates heat from refrigerant gas that has been compressed by the refrigerant compressor into a high temperature and high pressure, and decompresses the high-pressure refrigerant from the condenser. And a evaporator for evaporating the liquid refrigerant from the pressure reducing device. Such a refrigeration cycle apparatus can be used for a refrigeration apparatus, an air conditioner, a heat pump type hot water heater, and the like.

100 scroll compressor (rotary machine)
106 Crankshaft (shaft)
107a Bearing housing (housing part)
107b Through hole (hole)
108, 108a to 108d Main bearing (slide bearing)
117 Lubricating oil 120 Upper bush (first bearing part)
121, 121a-121c Intermediate bush (intermediate bearing part)
122, 122a Lower bush (second bearing part)
124, 124a Groove 130 Rotary compressor (rotary machine)
132 Rotating shaft (axis)
135a Bearing housing (housing part)
135b Through hole (hole)
140 Upper bush (first bearing)
141 Intermediate bush (intermediate bearing)
142 Lower bushing (second bearing part)
143 Upper bearing (slide bearing)

Claims (10)

A rotating shaft,
A housing part having a hole into which the shaft is inserted;
A first bearing portion disposed closest to one end in the axial direction in the hole of the housing portion, a second bearing portion disposed closest to the other end, and the first bearing portion and the second bearing portion The linear expansion coefficient is larger than that of the housing part, the first bearing part, and the second bearing part, and at least between the outer peripheral surface of the shaft before the rotation of the shaft is started. A slide bearing having an intermediate bearing portion with a gap larger than that of the first bearing portion and the second bearing portion, and sliding with respect to the outer peripheral surface of the shaft via lubricating oil;
A rotating machine comprising:   2. The rotating machine according to claim 1, wherein an outer diameter of the shaft is smaller in a portion facing the intermediate bearing portion than in other portions.   The rotary machine according to claim 1, wherein a groove that divides the inner peripheral surface in the circumferential direction is formed on the inner peripheral surface of the intermediate bearing portion.   The rotary machine according to claim 2, wherein a groove that divides the inner peripheral surface in the circumferential direction is formed in the inner peripheral surface of the intermediate bearing portion.   The material of the first bearing part and the second bearing part is a carbon bearing material obtained by impregnating a carbonaceous base material containing graphite with a metal, and the material of the intermediate bearing part contains a resin. The rotating machine according to item 1.   The material of the first bearing part and the second bearing part is a carbon bearing material obtained by impregnating a carbonaceous base material containing graphite with a metal, and the material of the intermediate bearing part contains a resin. The rotating machine according to item 2.   The material of the first bearing part and the second bearing part is a carbon bearing material obtained by impregnating a carbonaceous base material containing graphite with a metal, and the material of the intermediate bearing part contains a resin. The rotating machine according to item 3.   The material of the first bearing part and the second bearing part is a carbon bearing material obtained by impregnating a carbonaceous base material containing graphite with a metal, and the material of the intermediate bearing part contains a resin. The rotating machine according to item 4.   The rotary machine according to any one of claims 1 to 8, wherein the rotary machine is a scroll compressor or a rotary compressor.   A refrigeration cycle apparatus comprising the rotary machine according to any one of claims 1 to 8 as a refrigerant compressor for refrigeration or air conditioning.

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