WO2015025416A1

WO2015025416A1 - Rotary machine and refrigeration cycle device

Info

Publication number: WO2015025416A1
Application number: PCT/JP2013/072493
Authority: WO
Inventors: 小山田　具永
Original assignee: 株式会社日立製作所
Priority date: 2013-08-23
Filing date: 2013-08-23
Publication date: 2015-02-26
Also published as: JPWO2015025416A1

Abstract

The objective of the present invention is to provide a rotary machine and a refrigeration cycle device with which the shear resistance of an oil film of a lubricating oil between a sliding bearing and the outer peripheral surface of a rotating shaft can be reduced, thereby reducing bearing loss during fluid lubrication, and enabling the reliability of the bearing to be maintained even during a high-load operation. This rotary machine is equipped with: a rotating shaft; a housing part having a hole in which the shaft is inserted; a first bearing part arranged nearest one end in the axial direction within the hole of the housing part; a second bearing part arranged nearest the other end; and an intermediate bearing part arranged between the first bearing part and the second bearing part, with the linear expansion coefficient of the primary material forming the intermediate bearing part being less than that of the housing part, the first bearing part, the second bearing part, and the shaft, and with the gap between the intermediate bearing part and the outer peripheral surface of the shaft before the shaft begins to rotate being larger than the gap between the intermediate bearing part and the first bearing part and the gap between the intermediate bearing part and the second bearing part.

Description

Rotating machinery and refrigeration cycle equipment

The present invention relates to a rotary machine and a refrigeration cycle device, and more particularly to a rotary machine and a refrigeration cycle device provided with a slide bearing that slides on the outer peripheral surface of a rotating shaft via lubricating oil.

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

The orbiting scroll is provided with an orbiting slide bearing that slides in engagement 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 movement of the eccentric portion of the crankshaft is transmitted to the orbiting scroll to cause the orbiting scroll to orbit. The crankshaft, which is connected to the rotor of the motor for rotational movement, is supported by sliding via lubricating oil against a journal sliding bearing called a main bearing and a sub-bearing fixed in the scroll compressor.

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

As a prior art aiming at reduction of bearing loss, there is a thing of Unexamined-Japanese-Patent No. 2003-239876 (patent document 1). According to this patent document 1, the floating ring member 110 is rotatably and idleably held in the insertion groove 8a of the hub 8 formed in the lower part of the orbiting scroll 5, and the rotating shaft 4 is The slide bush 10 fixed to the eccentric portion 4a is inserted to constitute a friction loss reduction device of the scroll compressor.

Generally, in a sliding part such as a bearing in which two surfaces slide and slide via lubricating oil, it is known that the bearing loss due to oil film shear increases as the sliding speed increases. In the technology described in Patent Document 1, a floating ring member capable of rotating is disposed in a space between a slide bush fixed to an eccentric portion of a rotary shaft filled with lubricating oil and a hub. Thereby, the sliding which occurs between the slide bush fixed to the eccentric part of the rotating shaft and the hub is the sliding between the slide bush outer periphery and the floating ring member inner periphery, the floating ring member outer periphery and the inside of the hub It can be dispersed in sliding with the circumference. For this reason, the relative sliding velocity at each sliding portion is reduced, and the bearing loss due to oil film shearing is reduced.

Another prior art is described in JP-A-2008-101538 (Patent Document 2). In this patent document 2, "the bearing has a main bearing 6c for supporting the main shaft portion 7a and a crank bearing 4c for supporting the crank portion 7b. The main bearing 6c is a crank side main bearing 6c1 and this crank side A motor-side main bearing 6c2 adjacent to the main bearing The crank bearing 4c and the crank-side main bearing 6c1 are carbon bearings in which pores of a carbonaceous base material containing graphite are impregnated with metal. The bearing 6c2 is composed of a winding bush formed by winding a plate material. "

In the technology described in Patent Document 2, by configuring the crank bearing and the crank side main bearing to be a high load portion with high surface pressure with carbon bearings, reliability such as wear resistance and seizure resistance in boundary lubrication state can be improved. I have secured.

Japanese Patent Application Publication No. 2003-239876 JP 2008-101538 A

However, in the technology described in Patent Document 1, as the rotation speed of the rotating shaft decreases, the oil film is less likely to be formed than a general slide bearing, and direct contact with the floating ring member is likely to occur. There is.

Further, in the technique described in Patent Document 2, by using a carbon bearing having lubricity, a bearing by contact friction when the crankshaft and the bearing slide with direct contact in a state where oil film formation is difficult. The 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 reduction of bearing loss is extremely limited.

The object of the present invention is to reduce the bearing loss at the time of fluid lubrication by reducing the shear resistance of the oil film by the lubricating oil existing between the outer peripheral surface of the rotating shaft and the slide bearing, and also at the time of high load operation In the above, it is desirable to provide a rotating machine and a refrigeration cycle apparatus capable of maintaining the reliability as a bearing.

The rotary machine according to the present invention comprises: a rotating shaft; a housing portion having a hole into which the shaft is inserted; a first bearing portion disposed closest to one axial end in the hole of the housing portion; The linear expansion coefficient of the main material which is disposed between the second bearing disposed closest to the end and the first bearing and the second bearing is the housing, the first bearing, and the second bearing. And an intermediate bearing portion which is smaller than the shaft and whose clearance between the shaft and the outer peripheral surface of the shaft before the start of rotation of the shaft is larger than the first bearing portion and the second bearing portion.

According to the present invention, it is possible to reduce the bearing loss at the time of 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 slide bearing, and It is possible to provide a rotating machine and a refrigeration cycle device capable of maintaining the reliability as a bearing even during load operation.

Longitudinal sectional view of scroll compressor Enlarged sectional view around main bearing (comparative example) Enlarged sectional view around the main bearing Enlarged sectional view around the main bearing when the scroll compressor performs high load operation Graph showing the relationship between the expansion ratio of the gap between the intermediate bush and the crankshaft and the relative bearing loss Graph showing the relationship between the expansion ratio of the gap between the intermediate bush and the crankshaft and the relative minimum oil film thickness An enlarged sectional view around the main bearing according to a first modification of the first embodiment An enlarged sectional view around the main bearing according to a second modification of the first embodiment An enlarged sectional view around the main bearing according to a third modification of the first embodiment Longitudinal sectional view showing a rotary compressor

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 a first embodiment of the present invention. That is, in the first embodiment, the rotary machine of the present invention will be described using an example of the scroll compressor 100 that performs compression of refrigerant gas.

As shown in FIG. 1, the scroll compressor 100 is a closed type compressor used for air conditioning such as an air conditioner or refrigeration air conditioning such as a refrigeration system. The scroll compressor 100 has a closed vessel 102 forming a housing, and a fixed scroll 103 and an orbiting scroll 104 engaged with the fixed scroll 103 and pivoted are provided at an upper portion in the closed vessel 102. The fixed scroll 103 and the orbiting scroll 104 each have a spiral tooth shape.

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

An eccentric portion 106 a having an axial center eccentric to the axial center of a portion supported by the main bearing 108 and the secondary bearing 110 of the crankshaft 106 is provided on the upper portion of the crankshaft 106. The eccentric portion 106a engages with and slides in the orbiting bearing 112 provided on the lower surface (rear surface) side of the end plate 104a of the orbiting scroll 104, and the swinging rotational movement (eccentric motion) of the eccentric portion 106a is the orbiting scroll It is transmitted to 104.

The rotation scroll 104 has its rotation restricted by the Oldham ring 113 and makes a turning motion with respect to the fixed scroll 103. The Oldham ring 113 is attached to a groove formed on the lower surface (rear 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 rotationally driven by the electric motor 105, low-pressure refrigerant gas is sucked from the suction port 114 and guided to the 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 toward the center of the

scrolls

103 and 104, and is then discharged to the outside through the discharge port 115.

Inside the crankshaft 106, there is provided an oil supply hole 116 penetrating from the lower end to the end surface (upper end surface) side of the eccentric portion 106a along the axial direction. The lubricating oil 117 stored in the lower part of the sealed container 102 is supplied by the 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 pushed up through 116 and supplied to the gap between the inner circumferential surface of each bearing (main bearing 108, secondary bearing 110, and orbiting bearing 112) and the outer circumferential surface of crankshaft 106.

Here, the inside of the sealed container 102 has a discharge pressure, and an intermediate chamber (back pressure chamber) 118 formed on the lower surface side of the end plate 104 a of the orbiting scroll 104 has an intermediate pressure between the discharge pressure and the suction pressure. For this reason, the lubricating oil 117 stored in the lower part of the sealed container 102 is supplied to the

bearings

108, 110, 112, etc. via the oil supply hole 116 due to the pressure difference between the discharge pressure and the intermediate pressure.

FIG. 2 is an enlarged sectional view around the main bearing 108 in a 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 views). As shown in FIG. 2, the main bearing 108 of the comparative example has two cylindrical slide bearing bushes inside a through hole 107b formed inside a bearing housing 107a provided in a part of the frame 107. An upper bushing 120 and a lower bushing 122 are arranged axially side by side.

Specifically, the upper bush 120 is disposed closer to the eccentric portion 106a, and the lower bush 122 is disposed farther from the eccentric portion 106a. Lubricant oil is supplied to the gap between the outer peripheral surface of the crankshaft 106 and the inner peripheral surface of the main bearing 108 (the upper bush 120 and the lower bush 122) through the oil supply hole 116 and the oil supply port 119. The outer circumferential surface of and the inner circumferential 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.

FIG. 3 is an enlarged cross-sectional view around 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 is, for example, a through hole (hole) 107b formed inside a bearing housing (housing portion) 107a provided on a part of a cast iron frame 107. The upper bush (first bearing) 120 which is three cylindrical slide bearing bushes, the middle bush (intermediate bearing) 121, and the lower bush (second bearing) 122 are disposed from the upper side in the inside of the They are arranged in line in the axial direction in order.

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

The upper bush 120, the intermediate bush 121, and the lower bush 122 are inserted into the through hole 107b by press-fitting, and the outer diameter of each bush before the press-in is larger than the inner diameter of the through hole 107b. Therefore, each bush is elastically deformed by itself and the bearing housing 107a and is inserted in a state in which the inner diameter of the through hole 107b is enlarged, and is held by the respective elastic force.

The upper bush 120 and the lower bush 122 are made of, for example, a carbon bearing material in which a carbonaceous substrate containing graphite is impregnated with a metal. On the other hand, the intermediate bush 121 is composed of the back metal 121a and the thin sliding layer 121b inside thereof, and the back metal 121a constitutes the bearing housing 107a, a carbon bearing material that constitutes the upper bush 120 and the lower bush 122 It is made of a material that exhibits a smaller linear expansion coefficient, such as Invar alloy (36 Ni—Fe), as compared to a cast iron material and a carbon steel material that constitutes the crankshaft 106. The sliding layer 121 b is made of, for example, a material containing a resin for the purpose of preventing surface damage of the crankshaft 106 when contact sliding occurs with the outer periphery of the crankshaft 106. The sliding layer 121b is adhered or coated in a thin layer on the inner periphery of the back metal 121a, and the strength and deformation of the intermediate bush 121 are mainly determined by the back metal 121a.

In addition, the clearance between the intermediate bush 121 and the outer peripheral surface of the crankshaft 106 at least before the start of rotation of the crankshaft 106 is the clearance between the upper bush 120 and the outer peripheral surface of the crankshaft 106 and the lower bush 122 And the clearance between the cylinder and the outer peripheral surface of the crankshaft 106. That is, the difference between the inner diameter of intermediate bush 121 and the outer diameter of crankshaft 106 is larger than the difference between the inner diameter of upper bush 120 and the outer diameter of crankshaft 106, and the inner diameter of lower bush 122 and crankshaft 106. Greater than the difference between the outer diameter of

An oil supply hole 116 is formed in a 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). 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 will be described.

The oil film shear force generated at the interface between the rotating shaft (for example, the crankshaft 106) sliding through the oil film and the cylindrical bearing (for example, the main bearing 108) has a relationship of the equation (1) generally called Petrov's equation It is known to have
F = τA = η (V / h) A (1)
Here, F is an oil film shear force, τ is an oil film shear stress, 粘度 is an absolute viscosity, V is a circumferential velocity of the rotating shaft, h is a radial gap (oil film thickness), and A is an area of the bearing inner periphery related to 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 sum of the areas of the inner peripheral surfaces of all the slide bearing bushs is equal, and the inner diameters of the upper bush 120 and the lower bush 122 In the first embodiment of the present invention, since the radial gap h is set larger in the portion of the intermediate bush 121 than in the comparative example, the oil film shear force and hence the bearing loss are reduced more than in the comparative example.

If it is attempted 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 a concern that the resulting scroll compressor loss may increase. However, in the structure of the first embodiment of the present invention shown in FIG. 3, the clearance at the upper bush 120 and the lower bush 122 which are the outflow paths of the lubricating oil is smaller than the clearance at the middle bush 121. Therefore, even if the gap in the portion of the intermediate bush 121 is enlarged, the increase in the flow rate of the lubricating oil through the gap between the crankshaft 106 and the main bearing 108 hardly occurs, and the loss increase due to it is also prevented.

Also, according to the operating conditions and operating temperature of the scroll compressor 100, the materials, thickness, and inner diameter of the upper bearing 120, the intermediate bearing 121, and the lower bearing 122, which are slide bearing bushes, and the bearing housing 107a are determined. By doing this, it is possible to secure the load (load capacity) which can be supported by the main bearing 108 at the time of high load operation to be equal to that in the related art and maintain the reliability as the bearing.

FIG. 4 is an enlarged cross-sectional view around the main bearing 108 when the scroll compressor 100 shown in FIG. 1 performs a high load operation. FIG. 4 shows the crankshaft 106 slightly inclined with respect to the main bearing 108 during high load operation. The reason why the crankshaft 106 tilts will be described later.

As shown in FIG. 4, during high load operation where the rotational speed of the crankshaft 106 is large and the gas load 123 acting on the crankshaft 106 by the refrigerant gas is large, the circumferential velocity V of the crankshaft 106 increases and eccentricity The oil film shear force F increases due to the partial reduction of the radial gap h due to. Due to the increase in oil film shear heat generation and the increase in gas temperature in the scroll compressor 100, the temperature of the main bearing 108 (hereinafter also referred to as "bearing temperature") rises. 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 slide bearing bushes, respectively undergo thermal expansion.
In the first embodiment of the present invention, since the linear expansion coefficient of the back metal 121a that determines the deformation of the intermediate bush 121 is particularly small, the gap between the intermediate bush 121 and the crankshaft 106 is under high load operation (see FIG. 4) is smaller than in low load operation (see FIG. 3). Therefore, in the high load operation state, the region where the high oil film pressure can be held by the dynamic pressure is expanded as compared with the low load operation state, whereby the load capacity of the bearing is increased.

As shown in FIG. 4, since the gas load 123 acts as an overhang load on the crankshaft 106 at a portion above the main bearing 108, 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 of For this reason, at the bearing end portions shown 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 carbon bearing material having lubricity, oil film formation is difficult and the crankshaft 106 and the main bearing 108 make direct contact. Even in the state of sliding accompanied by the above, good wear resistance can be obtained.

Next, the evaluation regarding the bearing loss by oil film shear is described.

A main bearing 108 having an upper bush 120, an intermediate bush 121, and a lower bush 122 which are three slide bearing bushes as shown in FIG. 3 is disposed in the through hole 107b of the bearing housing 107a. On the other hand, the bearing loss due to the oil film shear when the crankshaft 106 slides through the lubricating oil was evaluated. Then, the influence of the clearance between the intermediate bush 121 and the crankshaft 106 in the bearing structure according to the first embodiment of the present invention on bearing loss and minimum oil film thickness was verified. The verification result is shown in FIG. 5 and FIG.

In this verification, in the scroll compressor 100 for an air conditioner, it is assumed that the crankshaft 106 has a diameter of 14 to 18 mm. Further, the axial length of the upper bush 120, the middle bush 121, and the lower bush 122 is the same and equal to the diameter of the crankshaft 106. The gaps between the upper and

lower bushes

120 and 122 and the crank shaft 106 are equal to 0.15% of the diameter of the crank shaft 106. Further, the inclination angle of the crankshaft 106 with respect to the main bearing 108 is 0.01 ° in the acting load direction.

FIG. 5 is a graph showing the results of evaluation of the bearing loss by variously changing the expansion ratio of the gap between the intermediate bush 121 and the crankshaft 106. That is, FIG. 5 shows the relationship between the enlargement 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 a reference (0%). Indicates the rate. The vertical axis represents a relative value to a bearing loss of 100% when the clearances between the upper bush 120, the intermediate bush 121, and the lower bush 122 and the crank shaft 106 are all equal. As shown in the verification result of FIG. 5, the bearing loss tends to decrease by enlarging the gap between the intermediate bush 121 and the crankshaft 106.

FIG. 6 is a graph showing the results of evaluation of the minimum oil film thickness by variously changing the enlargement ratio of the gap between the intermediate bush 121 and the crank shaft 106. That is, FIG. 6 shows the relationship between the enlargement ratio of the gap between the intermediate bush 121 and the crankshaft 106 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 taken as a reference (0%). Indicates the rate. The vertical axis represents a relative value to the minimum oil film thickness when the clearances between the upper bush 120, the intermediate bush 121, and the lower bush 122 and the crank shaft are all equal to 100%. Show. In addition, the minimum oil film thickness here is the minimum oil film thickness in the case of supporting the same load. As shown in the verification result of FIG. 6, the minimum oil film thickness tends to increase by reducing the gap between the intermediate bush 121 and the crankshaft 106.

The scroll compressor 100 according to the first embodiment of the present invention is disposed in the through hole 107b of the bearing housing 107a having the crankshaft 106 which is rotationally moved, the through hole 107b into which the crankshaft 106 is inserted, And a main bearing 108 sliding on the outer peripheral surface of the crankshaft 106 via lubricating oil. Further, the main bearing 108 is an upper bush 120 disposed closest to one end in an axial direction in the through hole 107 b of the bearing housing 107 a, a lower bush 122 disposed closest to the other end, and an upper bush 120 And an intermediate bush 121 disposed between the lower bush 122 and the lower bush 122. The intermediate bush 121 is composed of the back metal 121a and the sliding layer 121b, and the linear expansion coefficient of the back metal 121a is smaller than that of the bearing housing 107a, the upper bush 120, the lower bush 122, and the crankshaft 106. At least before the start of rotation of the crankshaft 106, the gap with the outer peripheral surface of the crankshaft 106 becomes larger than the upper bush 120 and the lower bush 122.

That is, in the first embodiment of the present invention, of the components of the main bearing 108 that supports the rotation of the crankshaft 106 while causing oil film shear of lubricating oil, the back metal 121a of the intermediate bush 121 disposed at the center portion , Made of a material having a smaller linear expansion coefficient than the upper and

lower bushes

120 and 122 arranged at both ends, and at least before the start of rotation of the crank shaft 106, the crank shaft than the upper and

lower bushes

120 and 122; The gap between the two is increased. The magnitude relationship of the clearance with the crankshaft 106 is at the time of normal temperature stop and at the time of low load operation with a small rotational speed of the crankshaft 106 and a low applied load (low bearing temperature) except during high load operation (high bearing temperature). The same holds true. Then, the inner diameter dimension change rate (reduction rate) of the intermediate bush 121 due to the temperature change is smaller than the inner diameter dimension change rate (reduction rate) of the upper bush 120 and the lower bush 122.

Therefore, during low load operation where the rotational speed of the crankshaft 106 and the load acting on the crankshaft 106 are small, the clearance with the crankshaft 106 is large at the portion of the intermediate bush 121, so the friction loss is reduced and the bearing loss is reduced. Do. In addition, since the gaps at the portions of the upper bush 120 and the lower bush 122 which are the outflow paths of the lubricating oil are small, the lubricating oil flow rate hardly increases, and the loss increase due to the lubricating oil flow rate is also prevented. On the other hand, during high load operation where 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 part due to dynamic pressure Increases the minimum oil film thickness and the load carrying capacity of the bearing (load carrying capacity).

That is, according to the first embodiment of the present invention, the bearing at the time of fluid lubrication is reduced by reducing the shear resistance of the oil film due to the lubricating oil existing between the outer peripheral surface of the rotating crankshaft 106 and the main bearing 108. The loss can be reduced, and the reliability as a bearing can be maintained even at high load operation.
(Material of upper bush and lower bush)
The material of the upper bush 120 and the lower bush 122 may be made of a carbon-based, metal-based or ceramic-based material having a linear expansion coefficient larger than that of the back metal 121a of the intermediate bush 121 and excellent in wear resistance. it can. In the example shown in FIG. 3, a carbon bearing material in which a carbonaceous base material containing graphite is impregnated with metal is used, with emphasis on securing wear resistance at the time of partial contact and direct contact friction due to oil film breakage. However, according to the abrasion resistance, environmental resistance, etc. required of the rotary machine to be applied as the material of the upper bush 120 and the lower bush 122, for example, a carbon bearing material in which a carbonaceous substrate containing graphite is impregnated with a resin Cast iron, carbon steel, copper alloy, brass, tin alloy, aluminum alloy, zirconia, alumina, silicon carbide, silicon nitride and the like may be used.
(Material of the intermediate bush)
As a material of the back metal 121a of the intermediate bush 121, a metal material having a linear expansion coefficient smaller than the material of the upper bush 120 and the lower bush 122 may be used. However, as the material of the back metal 121a, Ni-Fe-based, Ni-Co-Fe-based or so-called Invar alloy or Kovar alloy depending on the temperature condition of the rotary machine to be applied and the amount of change in the bearing gap to be expected. A low thermal expansion metal or the like composed of similar components may be used.

In addition, as the material of the sliding layer 121b of the intermediate bush 121, resin, sintered metal, or carbon-based material can be used, which causes less wear and damage of the crankshaft 106 when in direct contact with the outer periphery of the crankshaft 106. . However, as the material of the sliding layer 121b, polytetrafluoroethylene, polyetheretherketone, polyphenylene sulfide, nylon, polyimide, polyamide imide, polyethylene, ultra high molecular weight according to the material of the crankshaft 106 and the material of the back metal 121a. Polyethylene and the like, and composites of these resins and sintered metals, particles, fiber materials and the like may be used. The sliding layer 121 b is formed thin and low in rigidity on the inner periphery of the back metal 121 a, and the influence on the thermal deformation of the intermediate bush 121 is extremely small.
(First modification)
FIG. 7 is an enlarged sectional view around the main bearing 108 according to a first modification of the first embodiment. The same configuration and operation as those of the first embodiment shown in FIGS. 1 to 6 will not be described in detail, and only different points will be described (the same applies to the other modified embodiments described later).

As shown in FIG. 7, the first modified example of the first embodiment is different from the first embodiment in that the lower bush 122 of the main bearing 108 is integrally formed of the same member as the bearing housing 107. Note that the upper bush, instead of the lower bush 122, may be formed integrally with the bearing housing 107a. 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 122 (or the upper bush) is integrated with the same bearing housing 107a. Ru. According to the first modification of the first embodiment, in addition to the effects similar to those of the first embodiment can be obtained, it is possible to reduce the assembly cost by reducing the number of parts.
(2nd modification)
FIG. 8 is an enlarged sectional view around the main bearing 108 according to a 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 at the portion of the main bearing 108 facing the intermediate bush 121 than at other portions. That is, in the method of enlarging the bearing gap in the central portion of the main bearing 108, instead of enlarging the inner diameter of the intermediate bush 121 as in the first embodiment, the outer diameter of the crankshaft 106 of the portion facing the intermediate bush 121 It is also possible by making 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 slide bearing bushes can be obtained with high accuracy. In order to process the inner diameter efficiently by the axial feed in one cycle, the temperature in the high load operation of the scroll compressor 100 is heated in a state in which three slide bearing bushes are inserted in the bearing housing 107a, and 3 in that state It is necessary to devise a machining process such as machining the inner diameter of each slide bearing bush to the same diameter. On the other hand, in the structure according to the second modification of the first embodiment shown in FIG. 8, the inner diameters of the upper bush 120, the intermediate bush 121, and the lower bush 122 which are three slide bearing bushes are one at room temperature. It can be machined to the same diameter by axial feeding in one cycle. According to the second modification of the first embodiment, in addition to the effects similar to those of the first embodiment, the manufacturing cost can be reduced.
(Third modification)
FIG. 9 is an enlarged sectional view around the main bearing 108 according to a third modification of the first embodiment.

As shown in FIG. 9, in the third modification of the first embodiment, a groove 124 that divides the inner peripheral surface in the axial direction is formed in the inner peripheral surface of the intermediate bush 121, and the groove 124 The intermediate bush 121 has a V shape extending obliquely in the rotational direction of the crankshaft 106 from both ends in the axial direction to the central portion. That is, the inner peripheral surface of the intermediate bush 121 has a groove 124 extending in the axial direction, and the central portion of the groove 124 is formed to protrude in the rotational direction of the crankshaft 106 more than the both ends of the groove 124. According to the third modification of the first embodiment, the lubricating oil is moved from the both ends in the axial direction of the intermediate bush 121 toward the central portion through the groove 124 to increase the pressure in the vicinity of the central portion. For this reason, it is possible to improve the dynamic pressure and increase the minimum oil film thickness particularly when the load is high.
Second Embodiment
Next, a second embodiment of the present invention will be described with reference to FIG.

FIG. 10 is a longitudinal sectional view showing a rotary compressor 130 according to a second embodiment of the present invention. That is, in the second embodiment, the rotary machine of the present invention will be described using an example of the rotary compressor 130 that performs compression of the refrigerant gas.

As shown in FIG. 10, the rotary compressor 130 includes a vertical cylindrical closed vessel 138, a compression mechanism 139 for compressing the refrigerant gas in the closed vessel 138, a motor 131 for driving the compression mechanism 139, and a compression mechanism. And an oil reservoir 144 for storing lubricating oil supplied to the sliding surfaces of the parts and members constituting the part 139. In the closed container 138, the electric motor 131, the compression mechanism 139, and the oil reservoir 144 are disposed in order from the top.

A rotating shaft (shaft) 132 extending downward is connected to the rotor of the motor 131. The compression mechanism 139 includes an eccentric shaft 132a formed near the lower end of the rotary shaft 132, and a cylindrical roller 133 in which the eccentric shaft 132a is engaged inside and eccentric rotation is given by the eccentric shaft 132a. The cylinder 134 for accommodating the eccentric shaft portion 132a and the roller 133, the upper bearing member 135 which serves as the upper lid of the cylinder 134 and supports the rotary shaft 132, and serves as the lower lid of the cylinder 134 and supports the lower end portion of the rotary shaft 132 Lower bearing member 136, and a vane (not shown) sliding on the outer peripheral surface of the roller 133 to separate 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 on 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 is an upper bush (first bearing portion) 140, which is three cylindrical slide bearing bushes, and an intermediate bush (intermediate bearing portion) 141 in a through hole 135b formed inside the bearing housing 135a. And lower bushes (second bearing portions) 142 are arranged in order in the axial direction from the upper side.

Specifically, the upper bush 140 is disposed closest to one end (opposite to the eccentric shaft 132a) in the axial direction in the through hole 135b, that is, the side farthest from the eccentric shaft 132a. The lower bush 142 is disposed closest to the other end (the eccentric shaft portion 132a side) in the axial direction in the through hole 135b, that is, the side closest to the eccentric shaft portion 132a. Also, 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 bush 142 (including the sliding surface which is the inner circumferential surface thereof) is integrally formed with the bearing housing 135 a of the upper bearing member 135. On the other hand, the intermediate bush 141 is composed of the back metal 141a and the sliding layer 141b formed on the inner periphery thereof, and the linear expansion coefficient of the back metal 141a is determined by the linear expansion coefficient of the upper bush 140 and the lower bush 142 Also, it is made of a material smaller than the linear expansion coefficient of the bearing housing 135a and the rotary shaft 132, such as Invar alloy (36 Ni-Fe). The sliding layer 141 b is made of, for example, a material containing a resin.

In addition, the clearance between the intermediate bush 141 and the outer peripheral surface of the rotation shaft 132 is at least the clearance between the upper bush 140 and the outer peripheral surface of the rotation shaft 132 and the lower bush 142 before the rotational start of the rotation shaft 132. And the gap between the outer surface of the rotating shaft 132 and the Here, the outer diameter of the rotating shaft 132 is smaller at the portion of the upper bearing 143 facing the intermediate bush 141 than at other portions. That is, the difference between the inner diameter of the intermediate bush 141 and the outer diameter of the rotary 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 rotary shaft 132 and is lower. The difference 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 which is an inner peripheral surface thereof) which is a slide bearing for supporting the lower end portion of the rotating shaft 132 is integrally formed with the lower bearing member 136 made of cast iron. The lubricating oil 117 in the oil reservoir 144 provided at the lower part of the rotary compressor 130 passes through the branch holes radially branched from the oil supply hole 146 formed along the axial center of the rotary shaft 132, and the upper bearing 143 and the lower bearing The oil is supplied to the sliding portion of each bearing 143, 145 by lubricating oil, and smooth lubrication is ensured.

In the second embodiment of the present invention, at the time of low load operation where the rotational speed of the rotating shaft 132 and the load acting on the rotating shaft 132 are small, the clearance with the rotating shaft 132 is large at the portion of the intermediate bush 141, so the friction loss is reduced. And the bearing loss is reduced. In addition, since the gap between the upper bush 140 and the lower bush 142, which are the outflow paths of the lubricating oil, is small, the flow rate of the lubricating oil hardly increases, thereby preventing an increase in loss. On the other hand, during high load operation where the rotational speed of the rotating shaft 132 and the load acting on the rotating shaft 132 are large, the gap with the rotating shaft 132 in the intermediate bush 141 is reduced due to temperature change, and the oil film pressure at this portion due to dynamic pressure Increases the minimum oil film thickness and the load carrying capacity of the bearing (load carrying capacity).

That is, according to the second embodiment of the present invention, the bearing at the time of fluid lubrication is reduced by reducing the shear resistance of the oil film due to the lubricating oil existing between the outer bearing surface of the rotating shaft 132 which moves in rotation and the upper bearing 143. The loss can be reduced, and the reliability as a bearing can be maintained even at 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. Moreover, 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 a slide bearing bush, and the sliding surfaces which are the inner peripheral surfaces thereof are the bearing

members

135, 136 And each one. As a result, the movement of the fluid in the portion other than the bearing gap such as the inside of the material of the slide bearing bush as in the case where the slide bearing bush is configured separately from the bearing

members

135 and 136 is eliminated. Therefore, the inflow / outflow relationship of gas and lubricating oil between the bearings 143 and 145 and the compression chamber 137 can be easily controlled, and the design can be facilitated.

As mentioned above, although this invention was demonstrated based on embodiment, this invention is not limited to above-described embodiment, A various modified example is included. For example, the above-described embodiments are described in detail to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the described configurations. Further, part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Moreover, it is possible to add, delete, and replace other configurations for part of the configurations of the respective embodiments.

For example, in the above-described embodiment, three slide bearing bushes, ie, an upper bush, an intermediate bush, and a lower bush, are axially arranged in order from the upper side in the through hole formed inside the bearing housing. Ru. However, the present invention is not limited to this, and may be applied to a structure in which four or more slide bearing bushes are arranged in line in the axial direction. In this case, the slide bearing bushes at both axial ends correspond to the upper bush and the lower bush in the above embodiment, and at least one of the plurality of slide bearing bushes disposed between the slide bearing bushes at the axial both ends One corresponds to the intermediate bush in the above embodiment.

Also, for example, in the second modification of the first embodiment, as a method of enlarging the bearing gap in the central portion of the main bearing 108b, a method of reducing the outer diameter of the crankshaft 106 in the portion facing the intermediate bush 121a is adopted. 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 crank shaft 106 of the portion facing the intermediate bush 121 may be reduced.

In the above embodiment, the present invention is applied to a scroll compressor and a rotary compressor. However, the present invention is not limited to these and can be applied to other types of compressors. is there. In the above embodiment, the vertical compressor in which the rotational axis is arranged along the vertical direction has been described. However, the present invention is not limited to this, and the rotational axis is in the horizontal direction. The present invention is also applicable to a horizontal type compressor arranged along. Furthermore, the present invention is also applicable to various rotating machines provided with a slide bearing that slides on the outer peripheral surface of a rotating shaft via lubricating oil.

Furthermore, the present invention may be configured as a refrigeration cycle apparatus including the rotary machine according to the present invention as a refrigerant compressor for refrigeration or air conditioning. The refrigeration cycle apparatus includes a refrigerant compressor as a rotary machine according to the present invention, a condenser for radiating heat from refrigerant gas compressed by the refrigerant compressor to a high temperature and a high pressure, and decompressing the high pressure refrigerant from the condenser. And an evaporator for evaporating the liquid refrigerant from the pressure reducing device. Such refrigeration cycle equipment may be used for a refrigeration system, an air conditioning system, a heat pump water heater, and the like.

100 ... Scroll compressor (rotary machine)
102: sealed container 103: fixed scroll 104: orbiting scroll 105: electric motor 106: crank shaft (shaft)
106a ... eccentric part 107 ... frame 107a ... bearing housing (housing part)
107b ... through hole (hole)
108 ... Main bearing (slide bearing)
109: Lower frame 110: Secondary bearing 112: Swing bearing 113: Oldham ring 114: Suction port 115: Discharge port 116: Fuel port 117: Lubricating oil 118: Intermediate chamber 119: Fuel port 120: Upper bush (first bearing portion)
121 ... Intermediate bush (intermediate bearing part)
121a ... back metal 121b ... sliding layer 122 ... lower bush (second bearing)
124 ... groove 130 ... rotary compressor (rotary machine)
131 ... motor 132 ... rotating shaft (shaft)
133: Roller 134: Cylinder 135: Upper bearing member 135a: Bearing housing (housing part)
135b ... through hole (hole)
136 ... lower bearing member 137 ... compression chamber 138 ... sealed container 139 ... compression mechanism 140 ... upper bush (first bearing portion)
141 ... Intermediate bush (intermediate bearing part)
142 ... lower bush (second bearing)
143 ... Upper bearing (slide bearing)
144: Oil reservoir 145: Lower bearing (slide bearing)

Claims

An axis that rotates and
A housing portion having a hole into which the shaft is inserted;
A first bearing portion disposed closest to one end in an axial direction in the hole of the housing portion;
A second bearing portion disposed closest to the other end in the axial direction in the hole of the housing portion;
Disposed between the first bearing portion and the second bearing portion, and the linear expansion coefficient of the main material to be configured is smaller than the housing portion, the first bearing portion, the second bearing portion, and the shaft, And an intermediate bearing portion whose gap with the outer peripheral surface of the shaft is larger than the first bearing portion and the second bearing portion before the start of rotation of the shaft.
A rotary machine equipped with
An axis that rotates and
A housing portion having a hole into which the shaft is inserted;
A first bearing portion disposed closest to one end in an axial direction in the hole of the housing portion;
A second bearing portion disposed closest to the other end in the axial direction in the hole of the housing portion;
Disposed between the first bearing portion and the second bearing portion, and the linear expansion coefficient of the main material to be configured is smaller than the housing portion, the first bearing portion, the second bearing portion, and the shaft, And an intermediate bearing portion whose clearance between the outer circumferential surface of the shaft and the first bearing portion is the same as the first bearing portion and the second bearing portion before the start of rotation of the shaft.
A rotating machine, wherein an outer diameter of the shaft in a portion opposed to the intermediate bearing portion is small in other portions.
In claim 1 or 2,
The intermediate bearing portion is
A back metal whose linear expansion coefficient is smaller than the housing portion, the first bearing portion, the second bearing portion, and the shaft;
A sliding layer located on the inner periphery of the back metal and made of a material containing a resin;
With rotating machinery.
The rotary machine according to claim 3, wherein the back metal is an invar alloy.
The rotary machine according to any one of claims 1 to 4, wherein the first bearing portion and the second bearing portion are carbon bearings in which a carbonaceous substrate containing graphite is impregnated with a metal.
The rotary machine according to any one of claims 1 to 5, wherein the first bearing portion or the second bearing portion is integrally formed of the same member as the housing portion.
In any one of claims 1 to 6, a groove extending in the axial direction is provided on an inner peripheral surface of the intermediate bearing portion, and a central portion of the groove protrudes to the rotational direction side of the shaft than both end portions of the groove. Molded rotary machine.
The rotary machine according to any one of claims 1 to 7, 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.