BEARING STRUCTURE, COMPRESSOR, AND REFRIGERATION CYCLE APPARATUS

A rotary machine includes a rotor having a cylindrical shape and having a main oil feed hole through which lubricating oil passes and that is provided in an axial direction and a slide bearing provided outward in a radial direction with a gap between the rotor and the slide bearing and configured to hold the rotor so that the rotor rotates around an axis. The rotor is provided with a branch oil feed hole through which the gap and the main oil feed hole communicate with each other and through which the lubricating oil passes. A foreign matter separating portion configured to separate foreign matter from the lubricating oil is provided further backward in a direction of rotation of the rotor than the branch oil feed hole.

TECHNICAL FIELD

The present disclosure relates to a bearing structure including a shaft provided with an oil feed hole and a slide bearing configured to support the shaft, a compressor, and a refrigeration cycle apparatus.

BACKGROUND ART

In general, a rotary machine such as a compressor includes a bearing structure including a shaft configured to rotate and a slide bearing configured to hold the shaft so that the shaft can rotate. The shaft is provided with an oil feed hole through which lubricating oil is supplied to sliding parts of the shaft and the slide bearing. There is a conventional compressor including a main oil feed hole provided inside a shaft and extending in an axial direction and a branch oil feed hole branching off from the main oil feed hole in a radial direction of the shaft (see, for example, Patent Literature 1). While the shaft is rotating, lubricating oil in the main feed oil hole is subjected to centrifugal force acting outward in the radial direction, whereby the lubricating oil flows from the main oil feed hole to the branch oil feed hole and is supplied to sliding parts of the shaft and a slide bearing. One possible factor that causes abrasion on the sliding parts is that foreign matter such as abrasion powder generated on the sliding parts is supplied together with the lubricating oil to the sliding parts via an oil feed structure of the shaft. The foreign matter supplied together with the lubricating oil to the sliding parts is carried in a direction of rotation of the shaft along with sliding movements of the shaft and the slide bearing while being sandwiched between an outer circumferential surface of the shaft and an inner circumferential surface of the slide bearing. At this point in time, the outer circumferential surface of the shaft and the inner circumferential surface of the slide bearing are scraped against by the foreign matter, whereby abrasion occurs on the sliding parts to generate abrasion powder to further increase the amount of foreign matter (including abrasion powder) inside the compressor. Accordingly, abrasion of the slide bearing and the shaft by the foreign matter is effectively reduced by separating the foreign matter from the lubricating oil.

In the compressor of Patent Literature 1, an oil feed groove communicating with the branch oil feed hole and extending in the axial direction is provided in a location on the outer circumferential surface of the crank shaft (shaft) where the branch oil feed hole is provided in a circumferential direction and that is furthest forward in the direction of rotation of the crank shaft. Further, in the compressor of Patent Literature 1, a drain groove not communicating with the branch oil feed hole but extending in the axial direction is provided in a location on the outer circumferential surface of the crank shaft that is further backward in the direction of rotation than the location where the oil feed groove is provided in the circumferential direction, and a sliding area is formed between the oil feed groove and the drain groove. The compressor of Patent Literature 1 is configured such that of the foreign matter supplied to the gap between the crank shaft and the slide bearing via the branch oil feed hole, foreign matter of a certain size (e.g. foreign matter that is larger than this gap) is either drained out of the bearing structure by being trapped in the oil feed groove immediately after leaving an oil feed port or drained out of the bearing structure by being trapped in the drain groove after leaving the oil feed port and passing through the sliding area.

CITATION LIST

Patent Literature

Patent Literature 1: Japanese Unexamined Patent Application Publication No. 2015-161209

SUMMARY OF INVENTION

Technical Problem

However, in the compressor of Patent Literature 1, since foreign matter separating spaces such as the oil feed groove and the drain groove are provided further backward than, that is, downstream of, the oil feed port in the direction in which the lubricating oil flows, the amount of foreign matter that is supplied to the gap between the slide bearing and the crank shaft cannot be reduced. Further, in the compressor of Patent Literature 1, a portion of the foreign matter supplied to the gap between the slide bearing and the crank shaft that has a size about equal to or smaller than the gap (clearance) between the slide bearing and the crank shaft remains without being trapped in the oil feed groove or the drain groove and abrades the sliding parts.

Accordingly, Patent Literature 1 cannot sufficiently bring about an effect of reducing abrasion on sliding parts of a rotor such as a shaft and a slide bearing.

The present disclosure was made to solve problems such as those noted above and has as an object to provide a bearing structure, a compressor, and a refrigeration cycle apparatus with an ever-further reduction in abrasion on sliding parts of a rotor and a slide bearing.

Solution to Problem

A bearing structure according to an embodiment of the present disclosure is a rotary machine including a rotor having a cylindrical shape and having a main oil feed hole through which lubricating oil passes and that is provided in an axial direction and a slide bearing provided outward in a radial direction with a gap between the rotor and the slide bearing and configured to hold the rotor so that the rotor rotates around an axis. The rotor is provided with a branch oil feed hole through which the gap and the main oil feed hole communicate with each other and through which the lubricating oil passes. A foreign matter separating portion configured to separate foreign matter from the lubricating oil is provided further backward in a direction of rotation of the rotor than the branch oil feed hole.

Further, a compressor according to an embodiment of the present disclosure includes the bearing structure and a closed vessel housing the bearing structure.

Further, a refrigeration cycle apparatus according to an embodiment of the present disclosure includes a refrigerant circuit in which the compressor, an evaporator, a pressure reducing device, and a condenser are connected via refrigerant pipes.

Advantageous Effects of Invention

According to an embodiment of the present disclosure, a foreign matter separating portion configured to separate foreign matter from lubricating oil is provided further backward in the direction of rotation than the branch oil feed hole. Therefore, even in a case in which foreign matter is contained in lubricating oil flowing through the rotor, the action of inertial force on lubricating oil and foreign matter flowing through the branch oil feed hole is utilized so that foreign matter that is higher in density than the lubricating oil can be separated from the lubricating oil in the foreign matter separating portion. This inhibits foreign matter from being supplied from the branch oil feed hole of the rotor to the gap between the rotor and the slide bearing, thus making it possible to further reduce abrasion on sliding parts of the slide bearing and the shaft than has conventionally been the case.

DESCRIPTION OF EMBODIMENTS

FIG.1is a cross-sectional view of a bearing structure1according to Embodiment 1.FIG.2is a longitudinal sectional view of a shaft3as taken along line A-A inFIG.1. The bearing structure1is provided in a rotary machine such as a compressor12(seeFIG.28, which will be described below). The following describes a configuration of the bearing structure1with reference toFIGS.1and2.

As shown inFIG.1, the bearing structure1includes a rotor having a cylindrical shape and a slide bearing2provided outward in a radial direction of the rotor. The slide bearing2has a cylindrical shape and is fixed to a closed vessel103(seeFIG.28, which will be described below) of the rotary machine. The rotor is inserted in the slide bearing2, and is held by the slide bearing2so that the rotor can rotate around an axis Ax.

In Embodiment 1, the rotor is constituted by the shaft3, and an outer circumferential portion32of the shaft3slides over an inner circumferential surface21of the slide bearing2. A gap G (i.e. a clearance) is formed between the outer circumferential portion32of the shaft3and the inner circumferential surface21of the slide bearing2.

Inside the shaft3, a main oil feed hole5through which lubricating oil flows is provided in an axial direction. The term “axial direction” here means a direction in which the axis Ax of the shaft3extends. The main oil feed hole5has a substantially cylindrical shape whose central axis is the axis Ax of the shaft3and has an opening at a lower end of the shaft3in the axial direction. As the shaft3rotates, the lubricating oil flows into the main oil feed hole5via the opening. The lubricating oil in the main oil feed hole5may flow in the axial direction and be pressure-fed by an oil feed pump or other devices.

Further, the shaft3is provided with a columnar branch oil feed hole6branching off from the main oil feed hole5outward in the radial direction. The branch oil feed hole6has an inlet in an inner circumferential surface33of the shaft3and an outlet320in the outer circumferential portion32of the shaft3so that the gap G between the shaft3and the slide bearing2and the main oil feed hole5communicate with each other. As the shaft3rotates, the lubricating oil flowing into the main oil feed hole5passes through the branch oil feed hole6and is drained via the outlet320.

The gap G between the outer circumferential portion32of the shaft3and the inner circumferential surface21of the slide bearing2is filled with lubricating oil drained from the branch oil feed hole6of the shaft3. Friction between the inner circumferential surface21of the slide bearing2and the outer circumferential portion32of the shaft3during rotation of the shaft3is reduced by the lubricating oil.

The lubricating oil in the main oil feed hole5may contain foreign matter8such as abrasion powder. The foreign matter8such as abrasion powder is generated, for example, on sliding parts or other parts of the slide bearing2and the shaft3. The foreign matter8circulates through the closed vessel of the rotary machine together with the lubricating oil. Therefore, if the foreign matter8is supplied directly to the gap between the slide bearing2and the shaft3without being separated from the lubricating oil, the foreign matter8may cause further abrasion to increase in amount.

To address this problem, a structure for separation of foreign matter (hereinafter also referred to as “foreign matter separating portion”) is provided in a flow passage of the lubricating oil up to the supply of the lubricating oil to the gap G between the sliding parts of the slide bearing2and the shaft3. There are three options of where to provide a foreign matter separating portion: a place in the branch oil feed hole6of the shaft3that is at or close to the outlet320, a place in the middle of the branch oil feed hole6, and a place in the branch oil feed hole6that is at or close to the inlet. In one configuration, a foreign matter separating portion may be provided in one of the three places. In an alternative configuration, foreign matter separating portions may be provided in two or more of the three places.

In the bearing structure1of Embodiment 1, a foreign matter separating portion configured to separate the foreign matter8from the lubricating oil is provided in the middle of the branch oil feed hole6. Specifically, a recessed foreign matter separating space7aserving as a foreign matter separating portion is provided in an inner wall portion31aof an inner wall31of the branch oil feed hole6that is backward in a direction of rotation (direction of an arrow R) and upstream from the outlet320. In other words, the foreign matter separating space7ais not connected directly to the main oil feed hole5and communicates with the main oil feed hole5via part of the branch oil feed hole6that is at or close to the inlet, and is not connected directly to the gap G and communicates with the gap G via part of the branch oil feed hole6that is at or close to the outlet320.

A mechanism by which, in a case in which foreign matter8is contained in the lubricating oil in the main oil feed hole5, the foreign matter8is separated from the lubricating oil prior to the supply of the lubricating oil to the gap G is described with reference toFIG.1. The lubricating oil present in the main oil feed hole5of the shaft3in rotation forms a swirl flow in the same direction of rotation (direction of the arrow R) as the shaft3. Foreign matter8present in lubricating oil forming a swirl flow is subjected to centrifugal force and therefore pressed against the inner circumferential surface33of the shaft3, that is, an inner wall surface of the main oil feed hole5. At this point in time, foreign matter8present at a boundary between the branch oil feed hole6and the main oil feed hole5is released together with the lubricating oil by centrifugal force into the branch oil feed hole6, which is further outward in the radial direction than the main oil feed hole5.

Further, in a rotating system of coordinates that rotates at the same angular velocity as the shaft3, the foreign matter8is subjected to not only the centrifugal force but also Coriolis force (indicated by an outline arrow Fc inFIG.1) serving as an apparent force and acting in a direction opposite to the direction of rotation (direction of the arrow R) of the shaft3. This Coriolis force causes the foreign matter8to, as indicated by an arrow F2in the drawing, move in a trajectory that continuously approaches the inner wall portion31ain the inner wall31of the branch oil feed hole6that is backward in the direction of rotation (direction of the arrow R).

Meanwhile, a similar Coriolis force acts on lubricating oil inside the branch oil feed hole6; however, due to a density difference between the lubricating oil and the foreign matter8, the Coriolis force acting on the foreign matter8is greater than the Coriolis force acting on the lubricating oil. Therefore, the trajectory of the foreign matter8indicated by the arrow F2in the drawing is curved further backward in the direction of rotation than a trajectory of the lubricating oil indicated by an arrow F1in the drawing, so that the foreign matter8and the lubrication oil separate from each other inside the branch oil feed hole6. Moreover, the foreign matter8moving to continuously approach the inner wall portion31athat is backward in the direction of rotation (direction of the arrow R) enters the foreign matter separating space7aprovided in the inner wall portion31aand is trapped upstream from the outlet320.

In the example shown inFIG.2, the foreign matter separating space7ais provided such that the width of the foreign matter separating space7ain the axial direction, which is the direction in which the axis Ax extends, (inFIG.2, an up-down direction on the surface of paper) is equal to the width of the branch oil feed hole6in the axial direction (i.e. the diameter of the branch oil feed hole6; hereinafter referred to as “width of the branch oil feed hole6in the axial direction”). Even in a case in which the width of the foreign matter separating space7ain the axial direction is shorter than the width of the branch oil feed hole6in the axial direction, a certain effect of trapping the foreign matter8upstream from the outlet320of the branch oil feed hole6is brought about. Note, however, that it is desirable to make the width of the foreign matter separating space7ain the axial direction greater than or equal to the width of the branch oil feed hole6in the axial direction, as doing so allows more foreign matter8to flow into the foreign matter separating space7ain the branch oil feed hole6.

The rotor of Embodiment 1 is constituted by the shaft3, and in the example shown inFIGS.1and2, at least a portion of the shaft3that faces the slide bearing2is constituted by a single component. Such a rotor, that is, the shaft3, can be manufactured, for example, by using a 3D printer. Using the 3D printer makes it possible to provide a foreign matter separating space7ain the middle of the inner wall31of the branch oil feed hole6and configure the shaft3to be seamless and inseparable. Using the 3D printer makes it possible to easily form a complex foreign matter separating space7ain the branch oil feed hole6.

As noted above, a bearing structure1according to Embodiment 1 includes a rotor having a cylindrical shape and having a main oil feed hole5through which lubricating oil passes and that is provided in an axial direction and a slide bearing2provided outward in a radial direction with a gap G between the rotor and the slide bearing and configured to hold the rotor so that the rotor rotates around an axis. The rotor is provided with a branch oil feed hole6through which the gap G and the main oil feed hole5communicate with each other and through which the lubricating oil passes. A foreign matter separating portion (e.g. a foreign matter separating space7a) configured to separate foreign matter from the lubricating oil is provided further backward in a direction of rotation of the rotor (i.e. further forward in a direction opposite to the direction of rotation) than the branch oil feed hole6.

According to this configuration, a foreign matter separating portion configured to separate the foreign matter8from the lubricating oil is provided further backward in the direction of rotation (direction of the arrow R) than the branch oil feed hole6. Therefore, even in a case in which foreign matter8is contained in lubricating oil flowing through the rotor, the action of inertial force on lubricating oil and foreign matter8flowing through the branch oil feed hole6is utilized so that foreign matter8that is higher in density than the lubricating oil can be separated from the lubricating oil in the foreign matter separating portion. This inhibits foreign matter8from being supplied from the branch oil feed hole6of the rotor to the gap between the rotor and the slide bearing2, thus making it possible to further reduce abrasion on sliding parts of the slide bearing2and the shaft3than has conventionally been the case.

Further, the foreign matter separating portion is a recessed foreign matter separating space7aprovided in an inner wall portion31aof an inner wall31of the branch oil feed hole6that is backward in the direction of rotation. According to this configuration, even if foreign matter8moves from the main oil feed hole5of the rotor to the branch oil feed hole6with the flow of lubricating oil, the action of Coriolis force, which is a type of inertial force, on lubricating oil and foreign matter8flowing through the branch oil feed hole6is utilized so that foreign matter8that is higher in density than the lubricating oil can be separated from the lubricating oil by flowing into the foreign matter separating space7a. This makes it possible to reduce the supply of foreign matter8to the sliding parts of the slide bearing2and the rotor.

Further, the foreign matter separating space7ahas, in the axial direction, a width that is greater than or equal to a width of at least the branch oil feed hole6in the axial direction. This better allows more foreign matter8to flow into the foreign matter separating space7ain the branch oil feed hole6.

FIG.3is a longitudinal sectional view showing a modification of the foreign matter separating space7aof the bearing structure1according to Embodiment 1 with an outer circumferential surface of the shaft3exposed by cutting the slide bearing2of the bearing structure.FIG.4is a longitudinal sectional view of the shaft3as taken along line A-A inFIG.3.FIG.5is a partially enlarged view of a portion of the shaft3ofFIG.4surrounded by a dashed line C including the branch oil feed hole6and an area therearound. In each ofFIGS.4and5, a direction of drainage of foreign matter8is indicated by a chain double-dashed outline arrow Fd. Further, inFIG.5, a direction of action of Coriolis force is indicated by a solid outline arrow Fc.

As shown inFIG.3, a foreign matter drain hole32fcommunicating with the outside of the shaft3is provided in the middle of the branch oil feed hole6. The shaft3rotates clockwise when viewed directly above from the shaft3in a direction parallel with the shaft length inFIGS.3to5(see the arrow R inFIG.1). In this case, as shown inFIGS.4and5, Coriolis force acts on foreign matter particles backward in the direction of rotation (see the outline arrow Fc inFIG.5). For this reason, the foreign matter drain hole32fis provided to extend backward in the direction of rotation from the inner wall31of the branch oil feed hole6. Further, the foreign matter drain hole32fis provided to extend downward in the axial direction from the inner wall31of the branch oil feed hole31, and the foreign matter drain hole32fhas an exit32foprovided outside a sliding part, that is, a portion of the outer circumferential surface of the shaft3exposed from the slide bearing2. It is preferable that the foreign matter drain hole32fextend downward in the axial direction, although the foreign matter drain hole32fmay extend upward or downward in the axial direction. A reason for this is that when the foreign matter drain hole32fextends downward in the axial direction, foreign matter8that is higher in density than the lubricating oil is easily separated from the flow of lubricating oil and drained. The diameter of the foreign matter drain hole32fneeds to be larger than the size of foreign matter particles. Meanwhile, when the diameter of the foreign matter drain hole32fis too large, the amount of oil that is supplied to the gap G (seeFIG.3) formed between the slide bearing2and the shaft3decreases. Therefore, it is preferable that the diameter of the foreign matter drain hole32fbe at most approximately one-fifth of the diameter of the branch oil feed hole6.

As noted above, in the modification shown inFIGS.3to5, the rotor is a shaft3supported to slide directly on the inner circumferential surface21of the slide bearing2and includes a foreign matter drain hole32fprovided to extend backward in the direction of rotation from the branch oil feed hole6of the rotor. Moreover, the foreign matter separating space7ais formed by the branch oil feed hole6and the foreign matter drain hole32fof the shaft3.

According to this configuration, the foreign matter separating space7ais constituted by the foreign matter drain hole32fshown inFIG.4. Therefore, in comparison with a case in which the foreign matter separating space7ais in the shape of a recess as shown inFIG.1, flows of lubricating oil and foreign matter8toward the exit32foare generated in the foreign matter separating space7a. Moreover, since the foreign matter drain hole32fis provided to extend backward in the direction of rotation from the branch oil feed hole6, foreign matter8that is higher in density than the lubricating oil easily flows into the foreign matter drain hole32fwhen the lubricating off and the foreign matter8pass through the branch oil feed hole6. This makes it easy to separate the foreign matter8.

FIG.6is a cross-sectional view of a shaft3of a bearing structure1according to Embodiment 2.FIG.7is a longitudinal sectional view taken along line A-A inFIG.6.FIG.8is a longitudinal sectional view taken along line B-B inFIG.6.

As shown inFIGS.6to8, in the bearing structure1of Embodiment 2 too, as in the case of Embodiment 1, the rotor is constituted by the shaft3, and an outer circumferential portion32of the shaft3slides over an inner circumferential surface21of the slide bearing2. Further, in Embodiment 2 too, as in the case of Embodiment 1, the shaft3is provided with a main oil feed hole5, a branch oil feed hole6, and a foreign matter separating space7a.

Embodiment 2 is different from Embodiment 1 in that the shaft3is constituted by a plurality of elements so that the branch oil feed hole6is divided. In other respects, Embodiment 2 is identical to Embodiment 1. Components of Embodiment 2 that are identical to those of Embodiment 1 are given identical reference signs, and Embodiment 2 is described with a focus on differences from Embodiment 1.

An example configuration of the shaft3is described with reference toFIGS.6to8. As shown inFIG.6, the shaft3is constituted by a second element3bconstituting a large portion of the shaft3and a first element3aconstituting part of an outer circumferential side of the shaft3. The second element3bincludes the main oil feed hole5and portions of the branch oil feed hole6and the foreign matter separating space7athat are close to the main oil feed hole5. Further, the first element3aincludes portions of the branch oil feed hole6and the foreign matter separating space7athat are close to the outlet320. That is, the first element3aand the second element3bare assembled together, whereby the branch oil feed hole6and the foreign matter separating space7aof the shaft3are formed.

The first element3ahas a first planar portion35aintersecting at a right angle with the center line of the branch oil feed hole6and passing through the foreign matter separating space7a, and the second element3btoo has a second planar portion35bintersecting at a right angle with the center line of the branch oil feed hole6and passing through the foreign matter separating space7a. The first planar portion35aand the second planar portion35bare each a plane substantially parallel to the axis Ax. It should be noted thatFIG.6omits to illustrate the center line of the branch oil feed hole6, as the center line of the branch oil feed hole6overlaps line B-B.

First fitting portions36aconstituted, for example, by indented surfaces are formed at both ends of the first planar portion35ain the first element3ain a transverse direction, and second fitting portions36bconstituted, for example, by indented surfaces to fit the first fitting portions36aare formed at both ends of the second planar portion35bin the first element3bin a transverse direction. The second fitting portions36bof the second element3bform a pair of lugs (not illustrated) provided to wrap around an outer circumferential side of the first element3a, and by this pair of lugs, the first element3ais configured not to fall off outward in a radial direction of the second element3b. The fit between the first fitting portions36aand the second fitting portions36bcauses the first planar portion35aof the first element3aand the second planar portion35bof the second element3bto face each other.

Next, a method for manufacturing such a shaft3is described. First, as shown inFIG.6, part of an outer circumferential side of a cylindrically shaped shell element having a main oil feed hole5is detached from the other part, whereby a first element3aand a second element3are formed. At this point in time, on both sides in a transverse direction, the shell element is divided at indented surfaces, whereby first fitting portions36aand second fitting portions36bare formed. Further, in a central part in a transverse direction, the shell element is divided at a plane parallel to the axis Ax, whereby a first planar portion35aand a second planar portion35bare formed. Part of the outer circumferential side serves as the first element3a, and the other part serves as the second element3b.

Further, as shown inFIG.7, a columnar branch oil feed hole6passing from an outer circumferential portion of the shell element to the main oil feed hole5is bored at a predetermined height in the axial direction through the shell element. The branch oil feed hole6is provided in a radial direction to pass through the first element3aand the second element3b. After that, the first element3aand the second element3bare detached from each other by withdrawing the first element3afrom the second element3bin the axial direction.

As shown inFIG.8, after the first element3aand the second element3bhave been detached from each other, a foreign matter separating space7ais formed in the first element3aand the second element3b. In the example shown inFIGS.6to8of Embodiment 2, the shaft3is divided into the first element3aand the second element3bso that the branch oil feed hole6is divided in the radial direction of the shaft3; therefore, the foreign matter separating space7acan be formed by milling. Specifically, the foreign matter separating space7acan be formed by performing milling from the first planar portion35ain the first element3aand performing milling from the second planar portion35bin the second element3b.

After that, the first element3aand the second element3bare assembled together so that the first fitting portions36aof the first element3aand the second fitting portions36bof the second element3bengage with each other, whereby the branch oil feed hole6and the foreign matter separating space7aare formed.

In the manufacturing method, the timing of execution of the step of forming the branch oil feed hole6is not limited to the aforementioned timing. For example, the step of forming the branch oil feed hole6may be executed prior to the step of separating the shell element into the first element3aand the second element3b.

Further, the number of elements that constitute the shaft3and the shape of each element that constitutes the shaft3are not particularly limited to those noted above.

FIG.9is a cross-sectional view showing a modification of the shaft3of the bearing structure1according to Embodiment 2.FIG.10is a longitudinal sectional view taken along line A-A inFIG.9and a diagram showing a method for machining a foreign matter separating space7a. While the shaft3is divided at a plane parallel to the axis Ax in the example configuration ofFIGS.6to8, the shaft3is divided at a plane perpendicular to the axis Ax in the modification shown inFIGS.9and10.

As shown inFIG.9, the shaft3includes a first element3a(not illustrated) constituting one part, that is, an upper portion, of the shaft3in the axial direction and including upper portions of the branch oil feed hole6and the foreign matter separating space7aand a second element3bconstituting the other part, that is, a lower portion, of the shaft3in the axial direction and including lower portions of the branch oil feed hole6and the foreign matter separating space7a. The first element3aand the second element3bare assembled together, whereby the branch oil feed hole6and the foreign matter separating space7aof the shaft3are formed. That is, in the modification of Embodiment 2, as shown inFIG.9, the first element3a(not illustrated) and the second element3beach have a substantially columnar shape. Further, in the modification of Embodiment 2, as shown inFIG.10, the branch oil feed hole6and the foreign matter separating space7aare each quadrangular in cross-section.

Although not illustrated, the modification of Embodiment 2 is configured such that a lower end portion of the first element3aand an upper end portion of the second element3bfit each other, and a lower surface portion of the first element3aand an upper surface portion35cof the second element3bface each other.

In the modification shown inFIGS.9and10of Embodiment 2, the shaft3is cut into the first element3aand the second element3bso that the branch oil feed hole6is divided into upper and lower parts at a plane perpendicular to the axis Ax; therefore, the foreign matter separating space7acan be formed by milling. Specifically, the foreign matter separating space7acan be formed by performing milling from the upper surface portion35cin the second element3band performing milling from the lower surface portion in the first element3a. Specifically, cutting is done with a rotary cutting tool200lowered to a predetermined position in the branch oil feed hole6in the upper surface portion35cof the second element3b. Further, the foreign matter separating space7ais formed by performing milling perpendicularly in a transverse direction to the center line of the branch oil feed hole6.

In a case in which the branch oil feed hole6and the foreign matter separating space7aare each quadrangular in cross-section as shown inFIG.10, milling may be performed only on the second element3bso that upper walls of the branch oil feed hole6and the foreign matter separating space7aare constituted by the lower surface portion of the first element3a.

In the example shown inFIGS.6to8of Embodiment 2 and the modification shown inFIGS.9and10, foreign matter8is separated from the lubricating oil in the branch oil feed hole6and trapped in the foreign matter separating space7a; therefore, as in the case of Embodiment 1, an effect of making it possible to further reduce abrasion of sliding parts than has conventionally been the case is brought about.

Further, in the bearing structure1according to Embodiment 2, the rotor is constituted by a shaft3, and the shaft3is constituted by a first element3aincluding part of the branch oil feed hole6and a second element3bincluding a remaining part of the branch oil feed hole6.

This makes it possible to form the foreign matter separating space7aby performing milling from a division surface (such as the first planar portion35a) between the first element3aand the second element3b, thus eliminating the need for a special device such as a 3D printer and making it possible to avoid an increase in manufacturing cost.

FIG.11is a longitudinal sectional view showing a configuration of a rotor of a bearing structure1according to Embodiment 3.FIG.12is a partially cross-sectional view taken along line A-A inFIG.11. Embodiment 3 is different from Embodiment 1 in that the rotor is constituted by a shaft3and a cylindrically shaped sleeve9fitted onto an outer circumferential portion32of the shaft3. In other respects, Embodiment 3 is identical to Embodiment 1. Components of Embodiment 3 that are identical to those of Embodiment 1 are given identical reference signs, and Embodiment 3 is described with a focus on differences from Embodiment 1. In the following, the bearing structure1of Embodiment 3 is described with reference toFIGS.11and12.

The sleeve9is fixed to the shaft3and rotates at the same rotation speed as the shaft3. That is, in Embodiment 3, the sleeve9is a mating element that slides over the slide bearing2, and lubricating oil is supplied to a gap G (seeFIG.1) between the inner circumferential surface21of the slide bearing2and an outer circumferential portion92of the sleeve9.

As shown inFIG.12, the sleeve9is provided with a sleeve oil feed hole62bored therethrough in a radial direction, and the shaft3is provided with a shaft oil feed hole61bored therethrough in a radial direction. A branch oil feed hole6of the rotor is constituted by the sleeve oil feed hole62and the shaft oil feed hole61. In a circumferential direction of the rotor, the sleeve oil feed hole62is provided in a location that is identical to that of the shaft oil feed hole61, and the sleeve oil feed hole62and the shaft oil feed hole61are arranged in a straight line and communicate directly with each other. The sleeve oil feed hole62has an opening provided in the outer circumferential portion92of the sleeve9, and the opening serves as an outlet920of the branch oil feed hole6.

Note here that the statement that the sleeve oil feed hole62and the shaft oil feed hole61are arranged in a straight line means that as shown inFIG.12, the center line of the shaft oil feed hole61(indicated by a dot-and-dash line inFIG.12) and the center line of the sleeve oil feed hole62are arranged in a straight line. In the example shown inFIG.12, the sleeve oil feed hole62and the shaft oil feed hole61are provided in a straight line, and the sleeve oil feed hole62has the same diameter as the diameter of the shaft oil feed hole61, so that the inner wall31of the branch oil feed hole6at a boundary between the sleeve oil feed hole62and the shaft oil feed hole61is flat. It should be noted that the sleeve oil feed hole62and the shaft oil feed hole61may be different in diameter from each other.

Although, inFIGS.11and12, the shaft3is constituted by one element, the shaft3may be constituted by a plurality of elements, such as those shown in Embodiment 2, that are assembled together to form a foreign matter separating space7a.

A first outer circumferential recessed portion32aformed by a recess in the outer circumferential portion32of the shaft3may be provided backward in the direction of rotation (direction of the arrow R) at an edge of the outlet320of the shaft oil feed hole61. The foreign matter separating space7ais formed by the first outer circumferential recessed portion32aof the shaft3and an inner circumferential surface91of the sleeve9. That is, in Embodiment 3 too, the foreign matter separating space7ais provided in the inner wall portion31aof the inner wall31of the branch oil feed hole6that is backward in the direction of rotation (direction of an arrow R) and upstream from the outlet920.

The following describes an example of a method for manufacturing a bearing structure1of Embodiment 3. After the sleeve oil feed hole62has been formed in the sleeve9and the shaft oil feed hole61and the first outer circumferential recessed portion32ahave been formed in the shaft3, the sleeve9is fitted and fixed onto the outer circumferential portion32of the shaft3so that the sleeve oil feed hole62and the shaft oil feed hole61face each other.

It should be noted that the timing of formation of the branch oil feed hole6is not limited to the aforementioned case. For example, after the sleeve oil feed hole62and the shaft oil feed hole61have been bored from the outer circumferential portion92of the sleeve9with the sleeve9fitted onto the outer circumferential portion32of the shaft3, the sleeve9and the shaft3may be detached, and the first outer circumferential recessed portion32amay be formed in the shaft3.

As noted above, in the bearing structure1according to Embodiment 3 too, foreign matter8is separated from the lubricating oil in the branch oil feed hole6and trapped in the foreign matter separating space7a; therefore, as in the case of Embodiment 1, an effect of making it possible to further reduce abrasion of sliding parts than has conventionally been the case is brought about.

Further, in Embodiment 3, the rotor is constituted by a cylindrically shaped shaft3and a cylindrically shaped sleeve9fitted onto an outer circumferential portion32of the shaft3and configured to rotate with the shaft3. The branch oil feed hole6of the rotor incudes a shaft oil feed hole61provided in the shaft3and a sleeve oil feed hole62provided in the sleeve9. A first outer circumferential recessed portion32aformed by a recess in the outer circumferential portion32of the shaft3is provided backward in the direction of rotation (direction of the arrow R) at an opening edge (edge of the outlet320) of the shaft oil feed hole61. The foreign matter separating space7ais formed by the first outer circumferential recessed portion32aof the shaft3and an inner circumferential surface91of the sleeve9.

According to this configuration, a bearing structure1having a foreign matter separating space7ain the middle of a branch oil feed hole6can be manufactured by providing the first outer circumferential recessed portion32ain the outer circumferential portion32of the shaft3with the shaft3and the sleeve9detached from each other and then assembling the shaft3and the sleeve9together. This makes it possible to easily manufacture the bearing structure1without using a special device such as a 3D printer.

Further, in a circumferential direction of the rotor, the sleeve oil feed hole62is provided in a location that is identical to that of the shaft oil feed hole61, and the branch oil feed hole6of the rotor is constituted by the shaft oil feed hole61and the sleeve oil feed hole62. This prevents the main flow of lubricating oil from being blocked in the branch oil feed hole6, thus making it possible to smoothly supply the lubricating oil to the sliding parts while separating the foreign matter8into the foreign matter separating space7a.

FIG.13is a longitudinal sectional view showing a configuration of a rotor of a bearing structure1according to Embodiment 4.FIG.14is a partially cross-sectional view taken along line A-A inFIG.13.

In the bearing structure1of Embodiment 4 too, as in the case of Embodiment 3, the rotor is constituted by a shaft3and a sleeve9Note, however, that Embodiment 4 is different from Embodiment 3 in the shape of the branch oil feed hole6of the rotor. In the following, a configuration of the bearing structure1according to Embodiment 4 is described with reference toFIGS.13and14.

In Embodiment 4, as shown inFIG.14, in a circumferential direction of the rotor, the sleeve oil feed hole62is provided further forward in the direction of rotation (direction of the arrow R) than the shaft oil feed hole61, and the sleeve oil feed hole62has an entrance provided further forward in the direction of rotation than the outlet320of the shaft oil feed hole61. The rotor includes an oil feed space63through which the sleeve oil feed hole62and the shaft oil feed hole61communicate with each other, and the branch oil feed hole6is constituted by the shaft oil feed hole61, the sleeve oil feed hole62, and the oil feed space63.

A second outer circumferential recessed portion32bformed by a recess in the outer circumferential portion32of the shaft3is provided forward in the direction of rotation (direction of the arrow R) at the edge of the outlet320of the shaft oil feed hole61. The oil feed space63is formed by the second outer circumferential recessed portion32bof the shaft3and the inner circumferential surface91of the sleeve9. That is, Embodiment 4 is configured such that the outer circumferential portion32of the shaft3has recesses both backward and forward in the direction of rotation (direction of the arrow R) at the edge of the outlet320of the shaft oil feed hole61.

In the example shown inFIGS.13and14, as shown inFIG.13, the first outer circumferential recessed portion32aand the second outer circumferential recessed portion32bhave widths that are equal to the width of the outlet320of the shaft oil feed hole61in the axial direction, and the first outer circumferential recessed portion32aand the second outer circumferential recessed portion32bform a horizontally long rectangular shape. Moreover, in the example shown inFIGS.13and14, as shown inFIG.14, the first outer circumferential recessed portion32aand the second outer circumferential recessed portion32bare shaped by cutting out the outer circumferential portion32of the shaft3in the same plane.

The following describes an example of a method for manufacturing a bearing structure1of Embodiment 4. The sleeve oil feed hole62is formed in the sleeve9, and the shaft oil feed hole61is formed in the shaft3. Further, the first outer circumferential recessed portion32aand the second outer circumferential recessed portion32bare formed by passing the cutting tool200in a transverse direction along a plane perpendicular to the center line of the shaft oil feed hole61while keeping the cutting tool200in contact with the outer circumferential portion32of the shaft3. After that, the sleeve9is fitted and fixed onto the outer circumferential portion32of the shaft3so that the second outer circumferential recessed portion32bof the shaft3and the sleeve oil feed hole62face each other.

As noted above, in the bearing structure1according to Embodiment 4 too, foreign matter8is separated from the lubricating oil in the branch oil feed hole6and trapped in the foreign matter separating space7a; therefore, as in the case of Embodiment 1, an effect of making it possible to further reduce abrasion of sliding parts than has conventionally been the case is brought about.

Further, in Embodiment 4, in a circumferential direction of the rotor, the sleeve oil feed hole62is provided further forward in the direction of rotation (direction of the arrow R) than the shaft oil feed hole61. A second outer circumferential recessed portion32bformed by a recess in the outer circumferential portion32of the shaft3is provided forward in the direction of rotation at the opening edge (edge of the outlet320) of the shaft oil feed hole61, and an oil feed space63is formed by the second outer circumferential recessed portion32bof the shaft3and the inner circumferential surface91of the sleeve9. Moreover, the branch oil feed hole6of the rotor is constituted by the shaft oil feed hole61, the sleeve oil feed hole62, and the oil feed space63.

This makes it possible to increase the capacity of a space in which to retain foreign matter8upstream from the outlet920in the branch oil feed hole6and makes it possible to accumulate more foreign matter8within the rotor, thus inhibiting foreign matter8from flowing outward from the outlet920. Further, providing the sleeve oil feed hole62in a location that is further forward in the direction of rotation (direction of the arrow R) than the shaft oil feed hole61sets up a configuration in which the branch oil feed hole6is curved frontward in the direction of rotation upstream from the sleeve oil feed hole62. This inhibits foreign matter8from reaching the sleeve oil feed hole62by being subjected to greater Coriolis force than the lubricating oil. A reason for this is that in the shaft3in rotation, a force in the direction of rotation that is greater than Coriolis force acting in a direction opposite to the direction of rotation does not act on foreign matter8. Accordingly, in Embodiment 4, the amount of foreign matter8that is supplied to the gap G between the slide bearing2and the sleeve9can be further reduced than in the case of Embodiment 3, in which the branch oil feed hole6is provided in a straight line.

FIG.15is a longitudinal sectional view showing a configuration of a rotor of a bearing structure1according to Embodiment 5.FIG.16is a partially cross-sectional view taken along line A-A inFIG.15.

In the bearing structure1of Embodiment 5 too, as in the case of Embodiment 3, the rotor is constituted by a shaft3and a sleeve9Note, however, that Embodiment 5 is different from Embodiment 3 in the shape of the shaft3. In the following, a configuration of the bearing structure1according to Embodiment 5 is described with reference toFIGS.15and16.

In Embodiment 5, the shaft3includes a crowning portion3cin which the outer circumferential portion32is barreled. The crowning portion3cis provided in part of the shaft3in the axial direction. The sleeve9is fitted and fixed onto the outer circumferential portion32of the shaft3to cover an outer circumferential portion of the crowning portion3c, and the crowning portion3cand the sleeve9rotate at the same rotation speed. The crowning portion3cis provided so that the slide bearing2and the sleeve9maintain a parallel positional relationship with each other even in a case in which the shaft3becomes inclined.

The shaft oil feed hole61and the first outer circumferential recessed portion32aare provided in the crowning portion3cof the shaft3, and the foreign matter separating space7ais formed by the first outer circumferential recessed portion32aprovided in the crowning portion3cand the inner circumferential surface91of the sleeve9. AlthoughFIG.15illustrates a case in which the crowning portion3cis applied to the configuration of Embodiment 3, the crowning portion3cmay be applied to the configuration of Embodiment 4. In a case in which the crowning portion3cis applied to the configuration of Embodiment 4, the crowning portion3cis provided with the shaft oil feed hole61, the first outer circumferential recessed portion32a, and the second outer circumferential recessed portion32b.

As noted above, in the bearing structure1according to Embodiment 5 too, foreign matter8is separated from the lubricating oil in the branch oil feed hole6and trapped in the foreign matter separating space7a; therefore, as in the case of Embodiment 1, an effect of making it possible to further reduce abrasion of sliding parts than has conventionally been the case is brought about.

Further, in Embodiment 5, a crowning portion3cin which the outer circumferential portion32of the shaft3is barreled is provided in part of the shaft3in the axial direction, and the shaft oil feed hole61and the first outer circumferential recessed portion32aare provided in the crowning portion3cof the shaft3. Moreover, the sleeve9is fitted on the outer circumferential portion32of the shaft3to cover an outer circumference of the crowning portion3c. This makes it possible to, even in a case in which the shaft3is provided with the crowning portion3c, apply a configuration in which foreign matter8is separated, increasing versatility.

FIG.17is a longitudinal sectional view showing a configuration of a rotor of a bearing structure1according to Embodiment 6.FIG.18is a partially cross-sectional view taken along line A-A inFIG.17.

As in the case of Embodiment 5, the bearing structure1according to Embodiment 6 too is configured such that the shaft3is provided with a crowning portion3c, that the sleeve9is provided to cover an outer circumferential portion of the crowning portion3c, and that the first outer circumferential recessed portion32ais provided in the outer circumferential portion of the crowning portion3c. Note, however, that Embodiment 6 is different from Embodiment 5 in that foreign matter storage grooves32cand foreign matter drain grooves32dare provided in the outer circumferential portion32of the shaft3. In the following, a configuration of the bearing structure1according to Embodiment 6 is described with reference toFIGS.17and18.

The first outer circumferential recessed portion32a, the foreign matter storage grooves32c, and the foreign matter drain grooves32dare formed in a portion of the outer circumferential portion32of the shaft3covered with the sleeve9. The foreign matter storage grooves32care circumferentially provided in locations away from the first outer circumferential recessed portion32ain the axial direction. The foreign matter drain grooves32dcause the first outer circumferential recessed portion32aand the foreign matter storage grooves32cto communicate with each other. Foreign matter8trapped in the foreign matter separating space7aflows into the foreign matter storage grooves32cvia the foreign matter storage grooves32cand is collected by the foreign matter storage grooves32c.

In the example shown inFIG.17, the foreign matter storage grooves32care provided at ends of the crowning portion3cin the axial direction. Specifically, one of the foreign matter storage grooves32cis provided at a boundary between a portion of the outer circumferential portion32of the shaft3that is higher than the crowning portion3cand the crowning portion3c, and the other of the foreign matter storage grooves32cis provided at a boundary between a portion of the outer circumferential portion32of the shaft3that is lower than the crowning portion3cand the crowning portion3c. In the example shown inFIG.17, the two foreign matter storage grooves32care each provided at a distance from the foreign matter separating space7a, with one of the foreign matter drain grooves32dprovided to extend from an upper end of the first outer circumferential recessed portion32atoward the upper foreign matter storage groove32cand the other of the foreign matter drain grooves32dprovided to extend from a lower end of the first outer circumferential recessed portion32atoward the lower foreign matter storage groove32c.

The shapes of the foreign matter drain grooves32dare determined with reference to the orientation of Coriolis force acting on the foreign matter8. In the example shown inFIG.17, the foreign matter drain grooves32d, which extend from the first outer circumferential recessed portion32a, are inclined in a direction opposite to the direction of rotation (direction of the arrow R) of the shaft3. That is, each of the foreign matter drain grooves32dis provided at an angle backward in a direction opposite to the direction of rotation, that is, backward in the direction of rotation, as it extends from the first outer circumferential recessed portion32atoward the corresponding one of the foreign matter storage grooves32c. The foreign matter drain grooves32dthus provided inhibit the foreign matter8from flowing backward from the foreign matter storage grooves32cinto the foreign matter separating space7a.

In Embodiment 6 too, as in the case of Embodiment 5, the shaft oil feed hole61is provided in the crowning portion3cof the shaft3. In the example shown inFIG.18, as in the case of Embodiment 3, the sleeve oil feed hole62and the shaft oil feed hole61are provided in a straight line and communicate directly with each other. It should be noted that as shown in Embodiment 4, in a circumferential direction, the sleeve oil feed hole62may be provided further forward in the direction of rotation of the shaft3than the shaft oil feed hole61, and the sleeve oil feed hole62and the shaft oil feed hole61may communicate with each other via the oil feed space63.

The foreign matter8trapped in the foreign matter separating space7aby separating from the lubricating oil due to the action of Coriolis force is further collected by flowing from the foreign matter separating space7ainto foreign matter storage grooves32cthrough the foreign matter drain grooves32ddue to the action of Coriolis force. In the case of Embodiment 6, the foreign matter8does not flow backward from the foreign matter storage grooves32cinto the foreign matter separating space7aas long as the shaft3does not rotate in the opposite direction, as the foreign matter drain grooves32dare provided.

As noted above, in the bearing structure1according to Embodiment 6 too, foreign matter8is separated from the lubricating oil in the branch oil feed hole6and trapped in the foreign matter separating space7a; therefore, as in the case of Embodiment 1, an effect of making it possible to further reduce abrasion of sliding parts than has conventionally been the case is brought about.

Further, in Embodiment 6, foreign matter storage grooves32cprovided away from the first outer circumferential recessed portion32ain the axial direction and foreign matter drain grooves32dthrough which the first outer circumferential recessed portion32aand the foreign matter storage grooves32ccommunicate with each other are formed in a portion of the outer circumferential portion32of the shaft3covered with the sleeve9.

According to this configuration, foreign matter8trapped in the foreign matter separating space7ais collected in the foreign matter storage grooves32c, whereby more foreign matter8can be retained within the rotor. This makes it possible to reduce the amount of foreign matter8that is supplied to the gap G between the slide bearing2and the sleeve9. Furthermore, the foreign matter8thus collected can be retained in flow passages that are deeper than the outlet920, that is, the foreign matter storage grooves32c. This inhibits foreign matter8once trapped in the foreign matter separating space7afrom flowing again into the branch oil feed hole6, making it possible to more surely reduce the amount of foreign matter8that is supplied to the gap G.

Further, a crowning portion3cin which the outer circumferential portion32of the shaft3is barreled is provided in part of the shaft3in the axial direction, and the shaft oil feed hole61and the first outer circumferential recessed portion32aare provided in the crowning portion3cof the shaft3. The sleeve9is fitted on the outer circumferential portion32of the shaft3to cover an outer circumference of the crowning portion3c, and the foreign matter storage grooves32care provided at ends of the crowning portion3cin the axial direction.

According to this configuration, the shape of the crowning portion3ccan be utilized to provide recesses such as the first outer circumferential recessed portion32and the foreign matter drain grooves32din the barreled outer circumferential portion of the barreled crowning portion3cand provide the foreign matter storage grooves32cat constricted ends of the crowning portion3c. This makes it possible to easily form a structure in which foreign matter8is retained between the crowning portion3cand the sleeve9.

FIG.19is a longitudinal sectional view showing a first modification of the rotor of the bearing structure1according to Embodiment 6.FIG.20is a partially cross-sectional view taken along line A-A inFIG.19. The first modification of Embodiment 6 is described with reference toFIGS.19and20.

As shown inFIG.20, in the first modification of Embodiment 6, as in the case of Embodiment 4, in a circumferential direction of the rotor, the sleeve oil feed hole62is provided further forward in the direction of rotation of the shaft3than the shaft oil feed hole61. The first outer circumferential recessed portion32aand the second outer circumferential recessed portion32bare provided in continuity in the outer circumferential portion of the crowning portion3c, and the sleeve oil feed hole62and the shaft oil feed hole61communicate with each other through an oil feed space63formed by the first outer circumferential recessed portion32aand the inner circumferential surface91of the sleeve9. Further, in the modification of Embodiment 6, the shaft oil feed hole61is provided at an angle with respect to side surfaces32sof the first outer circumferential recessed portion32aand the second outer circumferential recessed portion32bformed in a plane parallel to the axis Ax. Specifically, the shaft oil feed hole61is inclined backward in the direction of rotation (direction of the arrow R) so that the outlet320of the shaft oil feed hole61is away from the entrance of the sleeve oil feed hole62.

As shown inFIG.19, foreign matter storage grooves32care provided at a distance from the edge of the outlet320of the shaft oil feed hole61and at both ends of the edge in the axial direction. In the modification of Embodiment 6, the first outer circumferential recessed portion32aand the second outer circumferential recessed portion32bare provided astride the upper and lower foreign matter storage grooves32cto include the entire edge of the outlet320of the shaft oil feed hole61. That is, the foreign matter separating space7ais connected directly to the foreign matter storage grooves32c, and no foreign matter drain grooves32dare provided.

As a method for forming the foreign matter separating space7aand the oil feed space63in continuity in the shaft3of the first modification of Embodiment 6, there is for example a method for removing part of the outer circumferential portion of the crowning portion3cin a circumferential direction by milling as in the case of Embodiment 4.

As noted above, in the first modification of Embodiment 6, in a portion of the outer circumferential portion32of the shaft3covered with the sleeve9, foreign matter storage grooves32care provided at a distance from the opening edge (edge of the outlet320) of the shaft oil feed hole61and at both ends of the opening edge in the axial direction. The first outer circumferential recessed portion32ais provided astride two of these foreign matter storage grooves32cin the axial direction. This makes it unnecessary to provide foreign matter drain grooves32d, thus simplifying the manufacturing process.

Further, in the first modification of Embodiment 6, in a portion of the outer circumferential portion32of the shaft3covered with the sleeve9, foreign matter storage grooves32care provided at a distance from the opening edge (edge of the outlet320) of the shaft oil feed hole61and at both ends of the opening edge in the axial direction. The first outer circumferential recessed portion32aand the second outer circumferential recessed portion32bare provided in continuity and provided astride two of these foreign matter storage grooves32cin the axial direction. Moreover, the shaft oil feed hole61intersects at an angle with side surfaces32sof the first outer circumferential recessed portion32aand the second outer circumferential recessed portion32band is inclined backward in the direction of rotation.

This causes lubricating oil containing foreign matter8to be released into a space away from the sleeve oil feed hole62, thus inhibiting the foreign matter8from reaching the sleeve oil feed hole62by being subjected to greater Coriolis force than the lubricating oil. This results in making it possible to further reduce the amount of foreign matter8that is supplied to the gap G.

FIG.21is a cross-sectional view showing a second modification of the rotor of the bearing structure1according to Embodiment 6. As shown inFIG.21, in the second embodiment, the contours of the outer circumferential portion32of the shaft3are in the shape of a combination of an arc and a plurality of straight lines. Alternatively, the contours of the outer circumferential portion32of the shaft3may be in a polygonal shape composed of a plurality of straight lines or a multi-arc shape composed of a plurality of arcs. In the second embodiment, the foreign matter separating space7ais formed by the outer circumferential portion32of the shaft3and the inner circumferential portion of the sleeve9. This makes it possible to trap foreign matter8contained in lubricating oil flowing out from the shaft oil feed hole61. This results in making it possible to reduce the amount of foreign matter8that is supplied to the gap G.

FIG.22is a longitudinal sectional view showing a third modification of the rotor of the bearing structure1according to Embodiment 6.FIG.23is a partially cross-sectional view taken along line A-A inFIG.22. InFIG.23, the dashed lines P indicate the positions of projection of the shaft oil feed hole61and the side surfaces32sof the first outer circumferential recessed portion32aand the second outer circumferential recessed portion32b, which are shown inFIG.20.

As shown inFIG.22, in the third modification, the shaft3has cylindrical portions3dprovided above and below the barreled crowning portion3cvia the foreign matter storage grooves32c. Further, the shaft3has an eccentric portion30provided further above the upper cylindrical portion3dand placed eccentrically with respect to the cylindrical portion3d. The crowning portion3cof the shaft3in the axial direction and the foreign matter storage grooves32cand the cylindrical portions3dprovided at the top and bottom of the crowning portion3care covered with the sleeve9, and the eccentric portion30is exposed from the sleeve9.

In the third modification, as shown inFIGS.22and23, a foreign matter drain space32eis provided between the outer circumferential portion32of the cylindrical portion3dof the shaft3and the inner circumferential surface91of the sleeve9by providing a notch in the outer circumferential portion32. As shown inFIG.22, the foreign matter drain space32eis provided in the outer circumferential portion32of the upper cylindrical portion3dto extend from an upper end of the cylindrical portion3dto a lower end in the axial direction and causes the foreign matter storage grooves32cto communicate with a space above the cylindrical portion3d. Foreign matter8leaving the shaft oil feed hole61is drained out of the shaft3through the first outer circumferential recessed portion32a, the foreign matter storage grooves32c, and the foreign matter drain space32ewhile moving backward in the direction of rotation with respect to the shaft3, which rotates in the direction of rotation (direction of the arrow R), in a trajectory indicated by an arrow F20inFIG.22.

Although not illustrated, a foreign matter drain space32emay be provided in the lower cylindrical portion3das well as the cylindrical portion3dabove the shaft oil feed hole61. Although, inFIG.22, the foreign matter drain space32eis provided only in a portion of the outer circumferential portion32of the shaft3covered with the sleeve9, the foreign matter drain space32emay be extended to a portion of the outer circumferential portion32of the shaft3exposed from the sleeve9.

Further, the shapes of the foreign matter drain grooves32dofFIG.17, the foreign matter drain space32emay have a shape inclined in a direction in which foreign matter is actively drained from the foreign matter separating space7awhen the shaft3rotates. That is, the foreign matter drain space32emay be provided at an angle in a direction opposite to the direction of rotation (direction of the arrow R), that is, backward in the direction of rotation, as it extends from an entrance beside the foreign matter storage groove32ctoward an exit in the axial direction.

Furthermore, as shown inFIGS.22and23, the foreign matter drain space32emay be provided at an angle further backward in the direction of rotation than the position of projection of the shaft oil feed hole61. That is, as shown inFIG.23, the foreign matter drain space32emay be provided so that the center axis line L2of the foreign matter drain space32eis further backward in the direction of rotation (direction of the arrow R) than the center axis line L1of the shaft oil feed hole61projected (see the dashed lines P). Note here that the center axis line L2of the foreign matter drain space32eis a straight line passing through the center of the foreign matter drain space32ein a circumferential direction of the shaft3and the axis Ax of the shaft3. InFIG.23, the position of projection of the shaft oil feed hole61is illustrated using the dashed lines P; however, as shown inFIG.22, the position in which the foreign matter drain space32eis provided in the axial direction is different from the position in which the shaft oil feed hole61is provided.

As noted above, in the third modification shown inFIGS.22and23, in the portion of the outer circumferential portion32of the shaft3covered with the sleeve9, the foreign matter storage grooves32cand a foreign matter drain space32ethrough which the foreign matter storage grooves32cand an outside of the portion of the outer circumferential portion32of the shaft3covered with the sleeve9communicate with each other are formed. This causes foreign matter trapped in the foreign matter separating space7aand the oil feed space63to be drained out of the bearing structure through the foreign matter drain space32e. This results in making it possible to further reduce the amount of foreign matter8that is supplied to the gap G.

FIG.24is a cross-sectional view showing a fourth modification of the rotor of the bearing structure according to Embodiment 6. As shown inFIG.24, a foreign matter drain space32emay be provided as a key groove in the inner circumferential surface91of the sleeve9. The foreign matter drain space32emakes it possible to actively drain lubricating oil containing a high proportion of foreign matter8retained in the foreign matter separating space7a.

FIG.25is a cross-sectional view showing a fifth modification of the rotor of the bearing structure according to Embodiment 6. As shown inFIG.25, in the fifth modification of Embodiment 6, the foreign matter separating space7ais provided in the inner circumferential surface91of the sleeve9. In the fifth modification, the foreign matter separating space7ais formed, for example, by wire electric discharge machining. In a case in which a groove is formed over the entire length of the inner circumferential surface91of the sleeve9in the axial direction by wire electric discharge machining, a foreign matter drain space32eshown in the fourth modification (seeFIG.24) of Embodiment 6 too is formed at the same time. A method for forming the foreign matter separating space7ais not limited to the aforementioned method, and the foreign matter separating space7amay also be formed by machining a recess in the inner circumferential surface91of the sleeve9with an internal cylindrical grinding machine.

As noted above, in a case in which the foreign matter separating space7aand the foreign matter drain space32eare provided in the sleeve9too, foreign matter8trapped in the foreign matter separating space7ais drained out of the bearing structure through the foreign matter drain space32eas in the case in which the foreign matter separating space7aand the foreign matter drain space32eare provided in the shaft3. This results in making it possible to further reduce the amount of foreign matter8that is supplied to the gap G.

FIG.26is a longitudinal sectional view showing a modification of a shaft3of a bearing structure according to Embodiment 7.FIG.27is a partially cross-sectional view taken along line A-A inFIG.26. In Embodiment 7, the foreign matter separation portion is constituted by a foreign matter separating wall7bprovided at an entrance of the branch oil feed hole6and extended from the entrance of the branch oil feed hole6into the main oil feed hole5. As shown inFIGS.26and27, the foreign matter separating wall7bis provided close to the center of the main oil feed hole5. That is, the entrance of the branch oil feed hole6is provided closer to the center of the main oil feed hole5than an inner wall surface of the main oil feed hole5(inner circumferential surface33of the shaft3). As a method for forming the foreign matter separating wall7bat the entrance of the branch oil feed hole6, there is for example a method for inserting a cylindrical foreign matter separating wall forming element7cinto the branch oil feed hole6. In the foreign matter separating wall forming element7cinserted into the branch oil feed hole6, an end beside the axis Ax that protrudes into the main oil feed hole5is the foreign matter separating wall7b.

As shown inFIG.27, a space7a1is formed between a wall portion7b1of the foreign matter separating wall7bthat is backward in the direction of rotation (direction of the arrow R) and the inner wall surface of the main oil feed hole5. That is, the space7a1is formed further backward in the direction of rotation (direction of the arrow R) than the entrance of the branch oil feed hole6by the foreign matter separating wall7bbeing extended from the entrance of the branch oil feed hole6into the main oil feed hole5.

While the shaft3is rotating, the lubricating oil is suctioned upward in an oil feed direction (direction of an arrow Fo) from a lower end of the shaft3into the main oil feed hole5. The lubricating oil in the main oil feed hole5moves upward while generating a swirl flow in the same direction as the direction of rotation (direction of the arrow R) of the shaft3. Foreign matter8present in lubricating oil forming a swirl flow swirls with the lubricating oil. Due to the action of centrifugal force on the foreign matter8, the foreign matter8flows in the same direction as the direction of rotation (direction of the arrow R) of the shaft3along the inner circumferential surface33of the shaft3in part of the main oil feed hole5that is far away from the axis Ax. Foreign matter8swirling along the inner wall surface (inner circumferential surface33) of the main oil feed hole5is blocked by the wall portion7b1of the foreign matter separating wall7bfrom moving forward in the direction of rotation and trapped in the space7a1that is further backward in the direction of rotation than the entrance of the branch oil feed hole6.

As noted above, in the bearing structure1according to Embodiment 7 too, a foreign matter separating portion in which foreign matter8is separated from the lubricating oil is provided further backward in the direction of rotation than the branch oil feed hole6; therefore, as in the case of Embodiment 1, an effect of reducing abrasion of sliding parts by the foreign matter8is brought about.

Further, the bearing structure1according to Embodiment 7 includes a foreign matter separating wall7bextending from an entrance of the branch oil feed hole6into the main oil feed hole5, and a space7a1formed further backward in the direction of rotation that the entrance of the branch oil feed hole6by the foreign matter separating wall7bfunctions as a foreign matter separating portion. This makes it possible to separate foreign matter8from lubricating oil and trap the foreign matter8upstream of the entrance of the branch oil feed hole6in the direction in which the lubricating oil and the foreign matter8flow, making it possible to inhibit the foreign matter8from being suctioned through the entrance of the branch oil feed hole6.

FIG.28is a longitudinal sectional view showing a configuration of a compressor12according to Embodiment 8. Embodiment 8 illustrates a case in which Embodiment 6, which is shown inFIGS.17and18, is applied to the compressor12. The compressor12is a closed compressor that is used in air-conditioning cooling equipment such as an air conditioner and a refrigerating machine. The following describes a configuration of the compressor12with reference toFIG.28on the assumption that the compressor12is a scroll compressor. It should be noted that the present disclosure can also be applied to another compressor such as a rotary compressor. Components of Embodiment 8 that are identical to those of Embodiment 1 are given identical reference signs, and Embodiment 3 is described with a focus on differences from Embodiment 1.

The compressor12includes a closed vessel103constituting an outer shell, a fixed scroll101, an orbiting scroll102, and a crank shaft107having an eccentric portion30. The closed vessel103is provided with a suction port109through which refrigerant is suctioned and a discharge port110through which compressed refrigerant is discharged. The crank shaft107is equivalent to the aforementioned shaft3. The crank shaft107is configured to transmit, to the orbiting scroll102, motive power that compresses refrigerant. The fixed scroll101and the orbiting scroll102each have a spiral tooth shape.

Further, the compressor12includes a cylindrically shaped slider106and a cylindrically shaped sleeve9. The slider106is fitted on the eccentric portion30of the crank shaft107. The sleeve9is fitted in such a place on the crank shaft107as to support reaction force that is generated when refrigerant is compressed by rotating the orbiting scroll102. Further, the compressor12includes an orbiting bearing105fitted onto the slider106, a main bearing104fitted onto the sleeve9, a main oil feed hole5provided inside the crank shaft107, and a branch oil feed hole6provided astride the crank shaft107and the sleeve9. Further, an oil feed pump111is attached to a lower portion of the crank shaft107. The oil feed pump111is caused by rotation of the crank shaft107to suck up lubricating oil from an oil sump108and send the lubricating oil to the main oil feed hole5.

FIG.28illustrates a case in which the foreign matter separating space7aof Embodiment 6 is provided in a place on the crank shaft107in which the sleeve9is fitted, and the rotor is constituted by the shaft3and the sleeve9. It should be noted that the bearing structure1of any of Embodiments 1 to 7 may be applied to the compressor12of the present disclosure. In a case in which the bearing structure1of Embodiment 1, 2, or 7 is applied to the compressor12of the present disclosure, the compressor12is configured to include the shaft3of Embodiment 1 or 2 instead of the rotor of the present disclosure, that is, the shaft3and the sleeve9.

As noted above, a compressor12according to Embodiment 8 includes the bearing structure1and a closed vessel103housing the bearing structure1. This makes it possible to, even if foreign matter8present in the oil sump108is sent to the main oil feed hole5via the oil feed pump111, inhibit the foreign matter8from being supplied to sliding parts of the main bearing104and the sleeve9. This makes it possible to reduce abrasion of the sliding parts, lengthening the life of the compressor12.

It should be noted that the present disclosure is not limited to being applied to the compressor12but may be applied to another rotary machine having a configuration in which lubricating oil is supplied to sliding parts of the rotor and the sliding bearing2via the rotor. Further, a refrigeration cycle apparatus10to which the compressor12of the present disclosure is applied is not limited to the aforementioned air-conditioning cooling equipment.

FIG.29is a circuit diagram showing a refrigerant circuit11of a refrigeration cycle apparatus10including the compressor12according to Embodiment 8. The refrigeration cycle apparatus10includes a refrigerant circuit11through which refrigerant circulates. The following description assumes that the refrigeration cycle apparatus10is an air conditioner.

The refrigerant circuit11is formed by the compressor12, an outdoor heat exchanger14, a pressure reducing device15, an indoor heat exchanger16, or other devices being connected by refrigerant pipes. The compressor12is configured to compress refrigerant and cause the refrigerant to circulate through the refrigerant circuit11. The outdoor heat exchanger14and the indoor heat exchanger16are configured to cause the refrigerant and air to exchange heat with each other. The pressure reducing device15is constituted, for example, by an expansion valve and configured to expand and decompress the refrigerant. Further, in the example shown inFIG.29, the refrigerant circuit11includes a flow switching device13. The flow switching device13is constituted, for example, by a four-way valve and configured to switch among flow passages of refrigerant discharged from the compressor12.

The flow switching device13enables switching between cooling and heating. The refrigeration cycle apparatus10includes a controller (not illustrated) configured to control various actuators. The controller controls, for example, the frequency of the compressor12, the opening degree of the pressure reducing device15, and the switching of the flow switching device13. During cooling operation, as indicated by solid arrows inFIG.29, the refrigerant discharged from the compressor12returns to the compressor12after flowing the outdoor heat exchanger14, the pressure reducing device15, and the indoor heat exchanger16in sequence. Meanwhile, during heating operation, as indicated by dashed arrows inFIG.29, the refrigerant discharged from the compressor12returns to the compressor12after flowing the indoor heat exchanger16, the pressure reducing device15, and the outdoor heat exchanger14in sequence. That is, during indoor cooling, the outdoor heat exchanger14functions as a condenser, and the indoor heat exchanger16functions and an evaporator. During indoor heating, the indoor heat exchanger16functions as a condenser, and the outdoor heat exchanger14functions and an evaporator. Therefore, during heating, the indoor heat exchanger16heats indoor air by causing the refrigerant compressed by the compressor12to reject heat, and during cooling, the indoor heat exchanger16cools indoor air by causing the refrigerant expanded by the pressure reducing device15to remove heat.

It should be noted that the configuration of the refrigerant circuit11is not limited to the aforementioned configuration. For example, the flow switching device13may be omitted.

A refrigeration cycle apparatus10according to Embodiment 8 includes a refrigerant circuit11in which the compressor12, an evaporator (e.g. an indoor heat exchanger16), a pressure reducing device15, and a condenser (e.g. an outdoor heat exchanger14) are connected via refrigerant pipes. According to this configuration, including the compressor12with a reduction in abrasion on sliding parts by foreign matter8brings about improvement in reliability of the refrigeration cycle apparatus10.

REFERENCE SIGNS LIST