Scroll compressor

A scroll compressor includes a fixed scroll, an orbiting scroll, a suction section, a discharge section, and an electric motor. A sliding surface of a scroll is formed outside a wrap with a depression section depressed with respect to a sliding surface and a flange section elevated with respect to the depression section. The flange section is a remaining region in a protruding region disposed outside a referential perfect circle, the remaining region being other than a region continuing to an end of an involute curve of a scroll formed with the flange section, the referential perfect circle having a radius set to a distance between the center of the scroll formed with the flange section and the end of the involute curve. The scroll compressor enhances reduction of the sliding loss with a simple structure and reduction of the refrigerant leakage loss in the entire compression chambers.

TECHNICAL FIELD

The present invention relates to a scroll compressor.

BACKGROUND ART

Compressors to compress working fluid such as a refrigerant are used in various apparatuses. Refrigeration cycle apparatuses such as refrigerating machines, water heaters, and air conditioners employ scroll compressors as a device to compress refrigerant gas.

A scroll compressor includes: a fixed scroll including a spiral wrap stood on an end plate (a base plate); and an orbiting scroll including a spiral wrap stood on an end plate (a sliding plate). The scroll compressor has a structure in which the fixed scroll and the orbiting scroll are arranged to face each other so that the wraps thereof engage with each other. In the scroll compressor, the orbiting scroll orbits to sequentially reduce the volumes of a plurality of compression chambers formed between the wraps, thereby compressing the refrigerant.

Such compression operation produces axial force (hereinafter, referred to as “separating force”) which attempts to separate the fixed scroll and the orbiting scroll from each other. In addition to the axial force (separating force), tangential force, radial force, and centrifugal force are applied to the orbiting scroll by the compression operation. These forces produce a moment (an upsetting moment) that attempts to tilt the orbiting scroll. The orbiting scroll thereby swings. If the scrolls are separated from each other, a gap is formed between the end (the end surface) of the wrap and the bottom thereof. Accordingly, the sealing performance of the compression chambers cannot be maintained, and the refrigerant leaks in the compression chambers (especially in the vicinity of the suction chamber where the seal length is short). The efficiency of the compressor is thereby reduced.

In view of this, a backpressure chamber is formed, on the back of the sliding plate of the orbiting scroll, to hold backpressure to press the orbiting scroll against the fixed scroll. The backpressure is pressure within the backpressure chamber and takes an intermediate value between the discharge pressure and the suction pressure. In the scroll compressor having this structure, the orbiting scroll is pressed against the fixed scroll with the backpressure within the backpressure chamber to cancel out the separating force and produce a force (hereinafter, referred to as pressing force) to press a sliding surface of the orbiting scroll against a sliding surface of the fixed scroll. In the scroll compressor having this structure, the refrigerant leakage loss can be reduced in the compression chambers (especially in the vicinity of the suction chamber where the seal length is short) by the pressing force. Herein, the sliding surface of the fixed scroll is a surface formed so as to continue to the end surface of the wrap of the fixed scroll. The sliding surface of the orbiting scroll is a surface of the outer peripheral portion of the sliding plate of the orbiting scroll which comes into contact with the fixed scroll.

However, the pressing force produces sliding friction between the sliding surface of the fixed scroll and the sliding surface of the orbiting scroll. When the pressing force excessively increases, the sliding loss increases, and the performance of the compressor decreases.

Accordingly, a scroll compressor is proposed which includes a backpressure introduced space on the sliding surface of the fixed scroll or the orbiting scroll. To the backpressure introduced space, the pressure (backpressure) within the backpressure chamber is introduced. This increases the pressing force in a region where a lot of refrigerant leaks between the sliding surfaces to reduce the refrigerant leakage loss in the compression chambers (Patent Document 1, for example). In the scroll compressor having this structure, the refrigerant leakage loss in the compression chamber (especially in the vicinity of the suction chamber where the seal length is short) and the sliding loss can be reduced.

CITATION LIST

Patent Literature

SUMMARY OF INVENTION

Technical Problem

However, the conventional scroll compressor described in Patent Literature 1 has a problem that the area of contact between the sliding surface of the fixed scroll and the sliding surface of the orbiting scroll is large, and the sliding loss is still large, as described below.

For example, an object of the conventional scroll compressor described in Patent Literature 1 is to reduce the refrigerant leakage loss between the sliding surface of the fixed scroll and the sliding surface of the orbiting scroll. In the conventional scroll compressor, therefore, the seal length to reduce refrigerant leakage is excessively elongated. The area of contact between the sliding surface of the fixed scroll and the sliding surface of the orbiting scroll is therefore increased, and the sliding loss in the conventional scroll compressor therefore remains large. Such a conventional scroll compressor still has room for improvement.

In addition, as described later, the conventional scroll compressor has a problem that when the backpressure introduced space is expanded, the orbiting scroll is more likely to swing. This can increase the amount of refrigerant leakage in the entire compression chambers.

If the backpressure introduced space is simply expanded in the conventional scroll compressor for the purpose of reducing the area of contact between the sliding surfaces, the force pressing down a portion of the sliding surface of the orbiting scroll that corresponds to the backpressure introduced space increases. Specifically, another force pressing the portion of the sliding surface of the orbiting scroll that corresponds to the backpressure introduced space is produced in addition to the upsetting moment. In the conventional scroll compressor, the orbiting scroll is thus more likely to swing. This can increase the amount of refrigerant leakage in the entire compression chambers.

The present invention has been made to solve the aforementioned problem. A major object of the present invention is to provide a highly-efficient scroll compressor which reduction of the sliding loss is enhanced with a simple structure and reduction of the refrigerant leakage loss in the entire compression chambers is enhanced.

Solution to Problem

To solve the above problems, the present invention is a scroll compressor including: a fixed scroll including an end plate and a spiral wrap standing on the end plate: an orbiting scroll which includes an end plate and a spiral wrap standing on the end plate and forms a compression chamber between the fixed scroll and the orbiting scroll, the compression chamber having a refrigerant to be compressed therein; a suction section configured to introduce the refrigerant from an outside to an inside of the compressor; a discharge section configured to discharge the refrigerant from the inside to the outside of the compressor; and an electric motor configured to orbit the orbiting scroll. At least one scroll of the fixed scroll and the orbiting scroll includes a sliding surface which is formed outside a wrap with a depression section depressed with respect to the sliding surface and a flange section elevated with respect to the depression section. The flange section is a remaining region in a protruding region disposed outside a referential perfect circle, the remaining region being other than the region continuing to an end of an involute curve of a scroll formed with the flange section, the referential perfect circle having a radius set to a distance between the center of the scroll formed with the flange section and the end of the involute curve.

Advantageous Effects of Invention

According to the present invention, it is possible to enhance reducing the sliding loss with a simple structure and enhance reducing the refrigerant leakage loss in the entire compression chamber.

The other means are described later.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments of the present invention (hereinafter, referred to as embodiments) will be described with reference to the accompanying drawings. Each drawing is just shown schematically to some extent enough to allow sufficient understanding of the present invention. The present invention is not limited to the examples illustrated in the drawings. In each drawing, the same or similar constituent components are given the same reference numerals, and the redundant description thereof is omitted.

Embodiment 1 provides a scroll compressor1(seeFIG. 5), in which later-described depression sections5gand a later-described flange section5hare provided in a sliding surface5fof a later-described fixed scroll5, or a scroll compressor1(seeFIG. 9), in which later-described depression sections6gand a later-described flange section6hare provided in a sliding surface6fof a later-described orbiting scroll6.

Hereinafter, the construction of the scroll compressor1according to Embodiment 1 will be described with reference toFIGS. 1 and 2.FIG. 1is a longitudinal sectional view of the scroll compressor1.FIG. 2is a cross-sectional view of the scroll compressor1.FIG. 2illustrates the construction of the cross section along a line X1-X1illustrated inFIG. 1, when viewed from below. The line X1-X1is included in the sliding surface5fof the later-described fixed scroll5and the sliding surface6fof the later-described orbiting scroll6.

As illustrated inFIG. 1, the scroll compressor1includes a compression mechanism3, an electric motor4, and a sealed casing2. The compression mechanism3includes the orbiting scroll6with a spiral wrap6astood thereon and the fixed scroll5with a spiral wrap5astood thereon. The electric motor4drives the compression mechanism3. The sealed casing2accommodates the compression mechanism3and the electric motor4. The orbiting scroll6is a moving member that moves to form compression chambers that compress a refrigerant, between the orbiting scroll6and the fixed scroll5. The fixed scroll5is a fixed member which is fixed within the scroll compressor1. The compression mechanism3is disposed in upper part of the sealed casing2. The electric motor4, which orbits (moves) the orbiting scroll6, is disposed in lower part of the sealed casing2. In the bottom of the sealed casing2, lubricant13is reserved.

The sealed casing2includes a cylindrical cylinder chamber2a, a top chamber2b, and a bottom chamber2cand has a sealed structure. The sealed casing2is formed by welding the top chamber2bto the top of the cylinder chamber2aand welding the bottom chamber2cto the underside of the cylinder chamber2a. To the top chamber2b, a suction pipe2dis attached. In Embodiment 1, the suction pipe2dis attached to the upper surface of the top chamber2band is positioned so as to extend in the longitudinal direction (that is, positioned lengthwise). To the side surface of the cylinder chamber2a, a discharge pipe2eis attached. In the vicinity of the suction pipe2dwithin the sealed casing2, a suction chamber5cis provided. The suction chamber5cis a space to which the refrigerant is sucked. The suction chamber5cserves as a compression chamber11after trapping of the refrigerant is completed by the orbital motion of the orbiting scroll6. Within the sealed casing2, a discharge pressure space2fis provided. A discharge port5eis provided on a center O (seeFIG. 6) of a base plate5bof the fixed scroll5, which corresponds to an axis of the fixed scroll5, so as to communicate with the compression chamber11in the innermost side.

The compression mechanism3includes: the fixed scroll5including the spiral wrap5aon the end plate (base plate)5b; the orbiting scroll6including the spiral wrap6aon the end plate (sliding plate)6b; and a frame9, which is fastened to the fixed scroll5with bolts8and supports the orbiting scroll6.

The fixed scroll5includes: the end plate (base plate)5b, which has a circular disk shape; the wrap5a, which is stood on the base plate5bin a spiral manner; and a cylindrical support section5i, which is located on the periphery of the base plate5band surrounds the wrap5a. A bottom surface5d(seeFIG. 5) of the base plate5bis at the bottom of the wrap5a, which serves as a tooth configured to engage with the wrap6aof the orbiting scroll6, and is referred to as a tooth bottom. In the support section5ias the outer periphery of the base plate5b, a surface continuing to the end surface of the wrap5aconstitutes a sliding surface5fof the fixed scroll5. The sliding surface5fof the fixed scroll5is the surface configured to come into contact with the later-described sliding surface6fof the orbiting scroll6.

The fixed scroll5is fixed to the frame9at the support section5iwith the bolts8and the like. The frame9, which is integrated with the fixed scroll5, is fixed to the inside of the cylinder chamber2aof the sealed casing2by fixing means such as welding.

On the other hand, the orbiting scroll6is disposed within the frame9so as to orbit, facing the fixed scroll5. The orbiting scroll6includes: the end plate (the sliding plate)6b, which has a circular disk shape; the spiral wrap6a, which is stood on the base plate6bin the spiral manner; and a boss section6i, which is provided at the center of the back surface of the sliding plate6b. The bottom surface6d(seeFIG. 9) of the sliding plate6bis at the bottom of the wrap6a, which serves as a tooth configured to engage with the wrap5aof the fixed scroll5, and is referred to as a tooth bottom. The surface of the outer periphery of the sliding plate6bthat comes into contact with the end surface of the wrap5aof the fixed scroll5serves as the sliding surface6fof the orbiting scroll6. The axis of the orbiting scroll6is shifted by a predetermined distance δ (not illustrated) from the axis of the fixed scroll5. The wrap6aof the orbiting scroll6is laid on the wrap5aof the fixed scroll5with a predetermined angle in the circumferential direction.

On the back of the sliding plate6bof the orbiting scroll6, a backpressure chamber10is formed. The backpressure chamber10holds backpressure to press the orbiting scroll6against the fixed scroll5. The backpressure chamber10is formed by the fixed scroll5, the orbiting scroll6, a crankshaft7, and the frame9. The backpressure chamber10is connected to the compression chambers11through a communication channel. In the middle of the communication channel, a backpressure regulation valve10ais provided.

The frame9includes a main bearing9a, which rotatably supports the crankshaft7. The lower surface side of the orbiting scroll6is connected to an eccentric section7bof the crankshaft7. The crankshaft7is rotatably disposed within the frame9and is coaxial with the fixed scroll5.

Between the lower surface of the orbiting scroll6and the frame9, an Oldham ring12is provided. The Oldham ring12is a mechanism to restrict the orbiting scroll6so that the orbiting scroll6does not rotate with respect to the fixed scroll5while allowing the orbiting scroll6to orbit relatively. The Oldham ring12is attached to a groove formed in the lower surface of the orbiting scroll6and a groove formed in the upper surface of the frame9. The Oldham ring12allows the orbiting scroll6to orbit, without rotating, upon eccentric rotation of the eccentric section7bof the crankshaft7.

The electric motor4includes a stator4aand a rotator4b. The stator4ais fixed within the sealed casing2by pressure insertion, welding, or the like. The rotator4bis rotatably disposed within the stator4a. The rotator4bis fixed to the crankshaft7.

The crankshaft7includes a main shaft7aand the eccentric section7b. The crankshaft7is supported by the main bearing9a, which is provided for the frame9, and a lower bearing14, which is provided near the bottom of the cylinder chamber2a. The eccentric section7bis eccentrically integrated with the main shaft7a. The eccentric section7bis fit in an orbiting bearing6c, which is provided for the boss section6iin the back of the orbiting scroll6. The crankshaft7is driven by the electric motor4. In this process, the eccentric section7bof the crankshaft7eccentrically rotates with respect to the main shaft7ato allow the orbiting scroll6to orbit. Within the crankshaft7, a lubrication channel7cis provided which introduces the lubricant13to the orbiting bearing6c, main bearing9a, and lower bearing14.

As illustrated inFIG. 2, the suction pipe2dand suction chamber5care provided in slightly outer positions of the base plate5bof the fixed scroll5. The suction pipe2dand suction chamber5cconstitute a suction section20that introduces the refrigerant from the outside of the scroll compressor1. In the substantially center of the base plate5bof the fixed scroll5, the discharge port5eis provided. In the outer periphery of the fixed scroll5, a lubrication hole19to supply the lubricant13is provided.

The orbiting scroll6is disposed so as to orbit, facing the fixed scroll5. The compression mechanism3causes the orbiting scroll6to orbit with the wrap6aof the orbiting scroll6and the wrap5aof the fixed scroll5engaged with each other, thus forming a plurality of crescent compression chambers11between the wrap5aof the fixed scroll5and the wrap6aof the orbiting scroll6. The plurality of compression chambers11communicate with the suction chamber5c. In Embodiment 1, the plurality of compression chambers11include two compression chambers11formed on the outer curve and inner curve of the wrap6aof the orbiting scroll6. Hereinafter, the compression chamber11formed on the outer curve of the wrap6aof the orbiting scroll6is referred to as an outside compression chamber11a. The compression chamber11formed on the inner curve of the wrap6aof the orbiting scroll6is referred to as an inside compression chamber11b. The outside and inside compression chambers11aand11bmove toward the discharge port5ewith the orbital motion of the orbiting scroll6and continuously decrease in volume with the movement.

When the orbiting scroll6orbits with the crankshaft7driven by the electric motor4, the refrigerant is introduced to the compression chambers11from the suction pipe2dthrough the suction chamber5c. The compression chambers11decreases in volume as the orbiting scroll6orbits. The refrigerant is thereby compressed. The compressed refrigerant is discharged from the discharge port5eto the discharge pressure space2fwithin the sealed casing2(seeFIG. 1) and is then discharged out of the scroll compressor1through the discharge pipe2e(seeFIG. 1). The discharge port5e, discharge pressure space2f, and discharge pipe2econstitute a discharge section21. A clearance is formed across the substantially entire circumference between the outer circumferential surface of the fixed scroll5and the inner wall surface of the cylinder chamber2aof the sealed casing2and between the outer circumferential surface of the frame9and the inner wall surface of the cylinder chamber2aof the sealed casing2. The discharge pressure space2fis formed between above the discharge port5eand the vicinity of the bottom of the sealed casing2through the clearance.

Herein, the operation of the scroll compressor1will be described with reference to mainlyFIG. 1.

First, the scroll compressor1drives and rotates the crankshaft7with the electric motor4. The rotational driving force is transmitted from the eccentric section7bof the crankshaft7through the orbiting bearing6cto the orbiting scroll6. The orbiting scroll6performs orbital motion around the axis (the center O (seeFIG. 6)) of the fixed scroll5with an orbiting radius of the predetermined distance δ (not illustrated). In this process, the Oldham ring12restricts the orbiting scroll6so that the orbiting scroll6does not rotate while allowing the orbiting scroll6to orbit relatively.

With the orbital motion of the orbiting scroll6, the compression chambers11aand11b(seeFIG. 2), which are formed between the wrap5aof the fixed scroll5and the wrap6aof the orbiting scroll6, move toward the discharge port5e. With the movement, the compression chambers11aand11bcontinuously decrease in volume. The scroll compressor1thereby sequentially compresses the refrigerant sucked from the suction pipe2dwithin the compression chambers11aand11b(seeFIG. 2) and discharges the compressed refrigerant through the discharge port5eto the discharge pressure space2f. The discharged refrigerant fills the inside of the sealed casing2to be supplied through the discharge pipe2eto a refrigeration cycle, for example, outside the sealed casing2.

In the aforementioned construction, the lubricant13is reserved in the bottom of the sealed casing2. The inside of the sealed casing2serves as the discharge pressure space2f. The pressure (discharge pressure) inside the discharge pressure space2fis higher than the pressure (backpressure) within the backpressure chamber10. The lubricant13reserved in the bottom of the sealed casing2flows into the backpressure chamber10through the lubrication channel7c, which is provided in the crankshaft7, due to the difference between the discharge pressure within the sealed casing2and the backpressure within the backpressure chamber10. Specifically, the lubricant13flows through the lubrication channel7c, which is provided in the crankshaft7, and reaches the eccentric section7bof the crankshaft7. The lubricant13then passes through the orbiting bearing6c, which is provided in the boss section6iof the orbiting scroll6, and the main bearing9a, which is provided in the frame9, into the backpressure chamber10. In this process, the lubricant13lubricates the orbiting bearing6cand main bearing9a.

The lubricant13flows into the backpressure chamber10through the orbiting bearing6cand main bearing9awith a pressure lower than the discharge pressure since the spaces in the orbiting bearing6cand main bearing9aare small. When the backpressure of the backpressure chamber10is higher than a specified value, the lubricant13having flown into the backpressure chamber10opens the backpressure regulation valve10a, which is provided in the middle of the communication channel connecting the backpressure chamber10and compression chambers11and flows into the compression chambers11to be mixed with the refrigerant. The lubricant13having flown into the compression chambers11passes through the compression chambers11with the refrigerant to be discharged through the discharge port5eto the discharge pressure space2f. A part of the lubricant13is discharged through the discharge pipe2eto the refrigeration cycle while the other part is separated from the refrigerant within the sealed casing2to return to the bottom of the sealed casing2.

<Structure to Enhance Reducing Refrigerant Leakage Loss in Compression Chamber and Reducing Sliding Loss>

Herein, the structure to enhance reducing the refrigerant leakage loss in the compression chambers11and enhance reducing the sliding loss in the scroll compressor1will be described.

In the scroll compressor1, the operation of the compression mechanism3to compress the refrigerant produces axial force (separating force) to separate the fixed scroll5from the orbiting scroll6. Separation of the fixed and orbiting scrolls5and6forms gaps between the end surface of the wrap5aand the tooth bottom5d(seeFIG. 5) and between the end surface of the wrap6aand the tooth bottom6d(seeFIG. 9). The sealing performance of the compression chambers11is not maintained. The refrigerant leaks in the compression chambers11(especially in the vicinity of the suction chamber5cwhere the seal length is short), thus reducing the efficiency of the scroll compressor1.

On the back of the sliding plate6bof the orbiting scroll6, the backpressure chamber10is formed to hold the backpressure that presses the orbiting scroll6against the fixed scroll5. The backpressure is the pressure within the backpressure chamber10, and takes an intermediate value between the pressure (discharge pressure) within the discharge pressure space2fand the pressure (suction pressure) within the suction chamber5c. In the thus-configured scroll compressor1, the backpressure of the backpressure chamber10presses the orbiting scroll6against the fixed scroll5to cancel out the separating force and produce a pressing force that presses the sliding surface6fof the orbiting scroll6against the sliding surface5fof the fixed scroll5. By the pressing force, the refrigerant leakage loss in the compression chambers11(especially in the vicinity of the suction chamber5cwhere the seal length is short) is reduced in the scroll compressor1.

The sliding surfaces5fand6fface each other with a minute space interposed therebetween. This space plays a role of separating the backpressure chamber10and suction chamber5cor compression chambers11. In the fixed scroll5, this space is filled with the lubricant13supplied from the lubrication hole19and the lubricant13flown into the compression chambers11, thus securing the sealing performance between the sliding surfaces5fand6fand reducing the sliding friction between the sliding surfaces5fand6f. The sliding loss is thereby reduced. The smaller the space between the sliding surfaces5fand6f, the less the refrigerant leakage at the sliding surfaces5fand6f. The magnitude of the space between the sliding surfaces5fand6fvaries depending on the phase of the orbital motion of the orbiting scroll6and the seal length. The amount of refrigerant leakage in the compression chambers11therefore varies. The reason therefor will be described later.

When the orbiting scroll6orbits, for example, the operation of the compression mechanism3to compress the refrigerant produces the axial force (separating force) to separate the fixed scroll and orbiting scroll from each other. By this compression operation, tangential force, radial force, and centrifugal force are applied to the orbiting scroll6in addition to the axial force (separating force). These forces produce a moment (upsetting moment) to tilt the orbiting scroll6, causing the orbiting scroll6to swing. The sliding surfaces5fand6fof the fixed scroll5and the orbiting scroll6are not always parallel while the orbiting scroll6orbits. Accordingly, the magnitude of the space between the sliding surfaces5fand6fchanges with the phase of the orbital motion of the orbiting scroll6. With such a change in the magnitude of the space, the refrigerant leakage in the compression chambers11changes.

The refrigerant leakage in the compression chambers11is affected by the seal length. Herein, the seal length refers to a length of the sliding surfaces5fand6fof the fixed scroll5and orbiting scroll6in the radial direction and is a length by which the backpressure chamber10is separated from the compression chambers11or suction chamber5c.

FIGS. 3 and 4illustrate an example of the seal length.FIGS. 3 and 4are explanatory views for the seal length.FIGS. 3 and 4are different in the phase of the orbital motion of the orbiting scroll6. In the example illustrated inFIG. 3, the axis of the orbiting scroll6is offset from the center to the lower right-hand side. The seal length in the vicinity of the suction chamber5cis the distance between points5mand5n. In the example illustrated inFIG. 4, the axis of the orbiting scroll6is offset from the center to the upper left-hand side. The seal length in the vicinity of the suction chamber5cis the distance between the point5mand a point6e.

Herein, the point5m(seeFIGS. 3 and 4) is a point on the outermost circumference in the inner curve of the fixed scroll5. The position of the point5mis at an end of an inside involute curve Liv (seeFIG. 6) of the fixed scroll5. The point5n(seeFIG. 3) is a point on the inner circumference of an annular groove5j, which is provided in the sliding surface5fof the fixed scroll5. The point6e(seeFIG. 4) is a point on the outer circumference of the sliding plate6bof the orbiting scroll6. In the example illustrated inFIG. 4, since the axis of the orbiting scroll6is offset from the center to the upper left-hand side, the outer circumference of the sliding plate6bof the orbiting scroll6is located at the position of the point6e.

As illustrated inFIGS. 3 and 4, the seal length changes depending on the phase of the orbital motion of the orbiting scroll6. The seal length at each phase is the shorter one of the distance between the points5mand5n(seeFIG. 3) and the distance between the points5mand point6e(seeFIG. 4). When the later-described annular groove5jis not provided, the seal length is the distance between the points5mand6e. The seal length changes by double the orbiting radius while the orbiting scroll6orbits once. In this description, it is assumed that the seal length is the minimum value while the orbiting scroll6orbits once for convenience.

The shorter the seal length, the more difficult it is to maintain the sealing performance between the sliding surfaces5fand6f, and the more the refrigerant leakage loss. The seal length depends on the location of the seal portion between the sliding surfaces5fand6f.

In the scroll compressor1, as described later, it is difficult to secure sufficient seal length in the vicinity of the suction chamber5c, and the seal length is the shortest in the vicinity of the suction chamber5c. In the scroll compressor1, the amount of refrigerant leakage in the vicinity of the suction chamber5cis greater than that in the other part of the sliding surface5f.

In the scroll compressor1, the difference in pressure between both sides of the seal portion in the vicinity of the suction chamber5cis the differential pressure between the backpressure and suction pressure. On the other hand, the difference in pressure between the both sides of the other part in the sliding surface5fis the differential pressure between the backpressure and the pressure within the compression chambers5e. From the influence of these differential pressures, in the scroll compressor1, the amount of refrigerant leakage in the vicinity of the suction chamber11is greater than that in the other part of the sliding surface5f.

The scroll compressor1therefore includes the depression sections5g, that function as a backpressure introduced space to which the pressure (backpressure) of the backpressure chamber10is introduced, in the sliding surface5fof the fixed scroll5or the sliding surface6fof the orbiting scroll6. For example, in the scroll compressor1, the depression sections5gare provided in the sliding surface5fof the fixed scroll5as illustrated inFIG. 5.FIG. 5is a schematic view of the fixed scroll5of the scroll compressor1, illustrating the shape of the sliding surface5fof the fixed scroll5.

Each depression section5gis a step provided for the sliding surface5fof the fixed scroll5. The depression sections5gare depressed with respect to the sliding surface5f. The depression sections5gfunction as the backpressure introduced space. In Embodiment 1, each depression section5gextends from the annular groove5jto the sliding surface5f. In the scroll compressor1, providing the depression sections5gfor the sliding surface5fof the fixed scroll5increases the pressure (backpressure) applied to the depression sections5g. In the scroll compressor1, the pressing force is increased in the region between the sliding surfaces5fand6fwhere a larger amount of refrigerant leaks, so that the reduction in refrigerant leakage loss is enhanced.

Meanwhile, there can be a scroll compressor in which the backpressure is simply increased without providing the depression sections5gin order to press the orbiting scroll6against the fixed scroll5strongly. However, in the thus-configured scroll compressor, since the backpressure is increased, the amount of the lubricant13flown into the suction chamber5cdecreases. This results in an increase in sliding loss between the sliding surfaces5fand6fof the fixed scroll5and the orbiting scroll6.

In the scroll compressor1according to Embodiment 1, the depression sections5gare provided for the sliding surface5for6fthat can produce a large sliding loss. The area of contact between the sliding surface5fof the fixed scroll5and the sliding surface6fof the orbiting scroll6is thereby reduced, so that the reduction in sliding loss is enhanced.

<Detailed Description of Fixed Scroll Construction>

Hereinafter, the construction of the fixed scroll5will be described in detail with reference toFIGS. 5 and 6.FIG. 6is a schematic view of the fixed scroll5of the scroll compressor1, illustrating the shape of the sliding surface5fof the fixed scroll5similarly toFIG. 5.

As illustrated inFIG. 5, the fixed scroll5includes the support section5i, the annular groove5j, the sliding surface5f, and the wrap5a, which are sequentially arranged from the outside. To the support section5i, fastening devices, such as the bolts8, to fix the fixed scroll5to the frame9are attached. The wrap5ais wound in a spiral manner toward the center, including the inner sidewall of the sliding surface5fas a part.

The annular groove5jis a step provided on the outer periphery of the sliding surface5fof the fixed scroll5so as to face the backpressure space. The annular groove5jis depressed with respect to the sliding surface5f. The annular groove5jincludes a surface different in level from the sliding surface5fby a predetermined amount. When the orbiting scroll6orbits, the end of the sliding surface6fof the orbiting scroll6passes over the annular groove5j. In this process, the sliding surface6fof the orbiting scroll6is opened to the backpressure space since the annular groove5jfaces the backpressure space. The scroll compressor1may be configured so that the annular groove5jis not provided for the fixed scroll5.

In the example illustrated inFIG. 5, the depression sections5ginclude two depression sections5gprovided for the sliding surface5fof the fixed scroll5. The depression sections5gare opened to the annular groove5jand each form a space communicating with the backpressure chamber10without reducing the backpressure. The depression sections5gare disposed on the inside of the annular groove5jin the sliding surface5fof the fixed scroll5. The depression sections5gare also provided so as to protrude inward across the later-described inside involute curve Liv.

Each of the depression sections5ghas a shape obtained by expanding a part of the annular groove5jinto the sliding surface5f. In other words, each depression section5gis an extension of the width of the annular groove5jtoward the center. The depression sections5gare formed in a part of the sliding surface5fother than a later-described region R0(seeFIG. 6). The region R0(seeFIG. 6) is a seal portion provided to prevent refrigerant leakage in the vicinity of the suction chamber5c. The width of the region R0(seeFIG. 6) in the vicinity of the suction chamber5cis set equal to or greater than the wall thickness of the wrap5awhich is needed to prevent the refrigerant leakage. In the thus-configured scroll compressor1, even if the annular groove5jis not provided for the fixed scroll5, the backpressure is introduced to the depression sections5gprovided in the sliding surface5f. Even if the scroll compressor1has such a structure, the pressing force is increased in a region between the sliding surfaces5fand6fwhere a large amount of the refrigerant leaks, that enhances reducing the refrigerant leakage loss.

The fixed scroll5includes a flange section5hbetween the two depression sections5g. The flange section5his a step provided in the outer periphery of the sliding surface5fof the fixed scroll5. The flange section5his elevated with respect to the depression sections5g. The surface level of the flange section5his equal to or slightly lower than the sliding surface5f.

Herein, the flange section refers to a remaining region of a protruding region of the sliding surface that are disposed outside of a referential perfect circle, other than the region continuing to the end of the involute curve of the scroll where the flange section is formed. The referential perfect circle has a radius set to the distance between the center of the scroll of interest and the end of the involute curve. When the flange section is provided for the fixed scroll, the involute curve of the scroll is the inside involute curve of the fixed scroll. When the flange section is provided for the orbiting scroll, the involute curve of the scroll is the outside involute curve of the orbiting scroll.

In the example illustrated inFIG. 6, for example, the flange section5hcorresponds to a remaining region R1, which is in the regions (the regions R0and R1in the illustrated example) disposed outside of the perfect circle Lci in the sliding surface5f, other than the region R0, which continues to the end point5mof the inside involute curve Liv.

Herein, the perfect circle Lci refers to a circle with a radius set to a distance t between the center O of the fixed scroll5and the end point5mof the inside involute curve Liv of the fixed scroll5.

The inside involute curve Liv refers to a curve that defines the profile of an inner wall surface5aaof the wrap5aof the fixed scroll5. The inner wall surface5aaof the wrap5aof the fixed scroll5is formed along the inside involute curve Liv.

The region R0is a part of the sliding surface5fand is disposed outside of the perfect circle Lci in the sliding surface5fof the fixed scroll5in order to secure the seal length in the vicinity of the suction chamber5c.

The region R1is a part of the sliding surface5fand is disposed outside of the perfect circle Lci in the sliding surface5fof the fixed scroll5in order to reduce the upsetting moment of the orbiting scroll6.

In the aforementioned construction, the scroll compressor1includes the protruding region R0, which is disposed outside of the perfect circle Lci, in the sliding surface5fof the fixed scroll5in order to secure the seal length in the vicinity of the suction chamber5c. The scroll compressor1also includes the depression sections5gin the sliding surface5fof the fixed scroll5, which is disposed outside of the wrap5a, in order to reduce the sliding loss during operation. However, the protruding region R0and depression sections5gupsets the balance at supporting the orbiting scroll6, making the orbiting scroll6more likely to swing. The scroll compressor1according to Embodiment 1 therefore includes the elevated flange section5hin the sliding surface5fof the fixed scroll5in order to prevent the orbiting scroll6from swinging.

In the example illustrated inFIG. 6, an end of the flange section5hon the upstream side and an end thereof on the downstream side are located at 120 degrees or less from both two intersections Pa and Pb at which the sliding surface5fintersect with the perfect circle Lci. Herein, the upstream and downstream sides are defined based on the direction that the refrigerant flows in the compression chambers11.

The flange section5h(region R1) is provided so that an area15athereof is always smaller than an area15bof the region R0. The width of the flange section5h(region R1) is preferably not greater than 20 mm in the light of the magnitude of the region R0and the magnitude of the depression sections5g, which function as the backpressure introduced space.

As described above, the lubrication hole19for supplying the lubricant13is provided in the outer periphery of the fixed scroll5. The lubrication hole19is disposed within the flange section5hor in the vicinity thereof. The lubrication hole19is preferably located downstream of a point P1in order to supply the lubricant13around the flange section5hthat produces frictional resistance between the sliding surface5fof the fixed scroll5and the sliding surface6fof the orbiting scroll6. The point P1is the point where the perfect circle Lci and the flange section5h(region R1) intersect first. When the fixed scroll5includes a plurality of flange sections5has illustrated inFIG. 12, for example, the point where the perfect circle Lci and the flange section5h(region R1) intersect first (that is, the point P1) indicates a point where the most upstream flange section5hintersects with the perfect circle Lci.

At the end of the tooth bottom5din the base plate5bof the fixed scroll5, the suction chamber5cis provided. The suction chamber5cis located in the vicinity of the end point5mof the inside involute curve Liv of the fixed scroll5. The end point5mis located on the edge of the inner circumference of the suction port of the suction chamber5c. The fixed scroll5has a structure in which the radial length of the wrap5ais short in the vicinity of the suction chamber5csince the suction chamber5cis located near the end point5m. This means that it is difficult to secure sufficient seal length in the vicinity of the suction chamber5c.

Hereinafter, the operation of the flange section5hwill be described with reference toFIGS. 7 and 8.FIG. 7is a schematic diagram illustrating a distribution of load applied to a sliding surface6fof an orbiting scroll6of a scroll compressor B1according to a comparative example. The scroll compressor B1according to the comparative example corresponds to the conventional scroll compressor described in Patent Literature 1.FIG. 8is a schematic diagram illustrating a distribution of load applied to the sliding surface6fof the orbiting scroll6of the scroll compressor1according to Embodiment 1.

As illustrated inFIG. 7, the scroll compressor B1according to the comparative example differs from the scroll compressor1(seeFIG. 8) according to Embodiment 1 in that the flange section5his not provided for the sliding surface5fof the fixed scroll5.

As illustrated inFIG. 7, in the scroll compressor B1according to the comparative example, the depression sections5gare provided in the sliding surface5fof the fixed scroll5. In the thus-configured scroll compressor B1, the pressure within the depression sections5gis the backpressure. In the scroll compressor B1, force that presses down the sliding surface6fof the orbiting scroll6is increased in the portion corresponding to the depression section5gby a load increase17(expressed by a triangle) compared with the case where the depression sections5gare not provided for the sliding surface5fof the fixed scroll5. In the scroll compressor B1, another force that presses down the portion of the sliding surface6fof the orbiting scroll6that corresponds to the depression sections5gis produced in addition to the upsetting moment. In the scroll compressor B1, therefore, the orbiting scroll6is more likely to swing. The refrigerant leakage can be reduced especially in the vicinity of the suction chamber5cwhere the seal length is short in the scroll compressor B1. On the other hand, in the scroll compressor B1, the orbiting scroll6is more likely to swing. In the scroll compressor B1, therefore, the difference in pressure between both sides of the seal portion in the place other than the vicinity of the suction chamber5c, for example, is differential pressure between the backpressure and suction pressure. This can increase the amount of refrigerant leakage in the place other than the vicinity of the suction chamber5c.

In the scroll compressor1according to Embodiment 1, as illustrated inFIG. 8, the depression sections5gare provided in the sliding surface5fof the fixed scroll5similarly to the scroll compressor B1according to the comparative example. In the scroll compressor1according to Embodiment 1, the flange section5his additionally provided in the sliding surface5fof the fixed scroll5.

In the fixed scroll5of the thus-configured scroll compressor1, the pressing force of the orbiting scroll6composed of the backpressure is born at the plurality of places including the flange section5hand other portions in the sliding surface5f. Accordingly, even if the force that presses down the sliding surface6fof the orbiting scroll6increases in the portion corresponding to the depression sections5g, the pressing force from the orbiting scroll6composed of the backpressure and the upsetting moment are reduced in the scroll compressor1, in contrast to the scroll compressor B1according to the comparative example. Accordingly, in the scroll compressor1, compared with the scroll compressor B1according to the comparative example, the orbiting scroll6is prevented from swinging while the refrigerant leakage is reduced in the vicinity of the suction chamber5cwhere the seal length is short as well as in the entire compression chambers11.

The above-described operation of the flange section5his obtained irrespectively of the phase of the orbital motion of the orbiting scroll6. In the scroll compressor1, therefore, the reduction in sliding loss can be enhanced even when the radial width of the seal portion (the region R0, seeFIG. 6) in the vicinity of the suction chamber5cis equal to or greater than the wall thickness of the wrap5athat is needed to prevent the refrigerant leakage.

As illustrated inFIG. 5, connecting sections16abetween the flange section5hand depression sections5gand a connecting section16bbetween the flange section5hand annular groove5jare preferably formed in a smooth circular shape so as to minimize sharp edges. Since the sliding surface5fdoes not include any sharp edge, the sliding surfaces5fand6fare prevented from being damaged even if the orbiting scroll6tilts due to swinging motion of the orbiting scroll6and the sliding surface6fcomes into contact with the sliding surface5f.

In the construction illustrated inFIGS. 5 and 6, the scroll compressor1includes the depression sections5gand flange section5hin the sliding surface5fof the fixed scroll5. As illustrated inFIG. 9, for example, the scroll compressor1may include depression sections6gand a flange section6hin the sliding surface6fof the orbiting scroll6instead of including the depression sections5gand flange section5hin the sliding surface5fof the fixed scroll5.FIG. 9is a schematic view of the orbiting scroll6according to a modification.FIG. 9illustrates the construction of the orbiting scroll6according to the modification along a line X2-X2ofFIG. 1when viewed from above.

As illustrated inFIG. 9, in the modification, the depression sections6ginclude two depression sections6g, and the flange section6hincludes one flange section6h. The two depression sections6gand one flange section6hare disposed in the sliding surface6fof the orbiting scroll6. The side view of one of the depression sections6gis illustrated inFIG. 10.FIG. 10is a longitudinal sectional view of the orbiting scroll6according to the modification.FIG. 10illustrates the construction of the section taken along a line X3-X3ofFIG. 9when seen from the side.

Each depression section6gis a step provided in the sliding surface6fof the orbiting scroll6. As illustrated inFIG. 10, the depression sections6gare depressed with respect to the sliding surface6f. The depression sections6gfunction as the backpressure introduced space in the same way as the depression sections5g(seeFIGS. 5 and 6). In the scroll compressor1, providing the depression sections6gin the sliding surface6fof the orbiting scroll6increases the pressure (backpressure) applied to the depression sections6g. In the scroll compressor1, therefore, the pressing force is increased in the region between the sliding surfaces5fand6fwhere a large amount of refrigerant leaks, so that the reduction in refrigerant leakage loss is enhanced especially in the vicinity of the suction port5c.

The orbiting scroll6according to the modification includes the flange section6hbetween the two depression sections6g. The flange section6his a step provided in the outer periphery of the sliding surface6fof the orbiting scroll6. The flange section6his elevated with respect to the depression sections6g. The surface level of the flange section6his equal to or slightly lower than that of the sliding surface6f.

The flange section6his disposed in the sliding surface6fbased on a referential perfect circle with the radius set to the distance between the center of the orbiting scroll6in which the flange section6his formed and the end of the outside involute curve of the orbiting scroll6. Specifically, the flange section6his provided as a remaining region of the protruding regions disposed outside of the referential perfect circle, other than the region continuing to the end of the outside involute curve.

In the above-described construction, the depression sections6gfunction as the backpressure introduced space to introduce the pressure (backpressure) of the backpressure chamber10to the sliding surfaces5fand6fin the same way as the depression sections5g(seeFIGS. 5 and 6). The flange section6fbears the pressing force of the orbiting scroll6in the same way as the flange section5h(seeFIGS. 5 and 6).

Even when the depression sections6gand flange section6hare provided in the sliding surface6fof the orbiting scroll6like the modification, the scroll compressor1provides the same operation as that in the case where the depression sections5gand flange section5hare provided in the sliding surface5fof the fixed scroll5(seeFIGS. 5and6). Herein, the same operation includes preventing the orbiting scroll6from swinging while reducing the refrigerant leakage in the vicinity of the suction chamber5cwhere the seal length is short as well as reducing the refrigerant leakage in the entire compression chambers11.

<Major Features of Scroll Compressor>

(1) In the scroll compressor1, the sliding surface5fof the fixed scroll5is formed outside of the wrap5awith the depression sections5g, which are depressed with respect to the sliding surface5f, and the flange section5h, which is elevated with respect to the depression sections5g. Alternatively, the sliding surface6fof the orbiting scroll6is formed outside of the wrap6awith the depression sections6g, which are depressed with respect to the sliding surface6f, and the flange section6h, which is elevated with respect to the depression sections6g. The flange section is a remaining region provided in the protruding regions disposed outside of the referential perfect circle, other than the region continuing to the end of the involute curve of the scroll formed withe the flange section. The referential perfect circle has a radius set to a distance between the center of the scroll formed with the flange section and the end of the involute curve of the scroll.

Thus-configured scroll compressor1prevents the orbiting scroll6from swinging due to the upsetting moment to enhance reducing the sliding loss with the simple structure as well as enhance reducing the refrigerant leakage loss in the entire compression chambers11.

(2) The area15aof the flange section5h, that corresponds to the protruding region R1among the protruding regions R0and R1(seeFIG. 6), is smaller than the area15bof the protruding region R0, which corresponds to the region continuing to the end of the involute curve. In the thus-configured scroll compressor1, the sliding loss is efficiently reduced.

(3) The lubrication hole19(seeFIG. 6) is disposed downstream of the intersection P1, at which the perfect circle Lci (seeFIG. 6) and the flange section5hintersect first. In the thus-configured scroll compressor1, providing the flange section5hin the place where a large amount of lubricant is supplied reduces the sliding loss due to the flange section5h. The same goes with the flange section6h(seeFIG. 9).

(4) The width of the flange section5h(seeFIG. 6) is preferably 20 mm or less. In the thus-configured scroll compressor1, the sliding loss due to the flange section5his reduced. The same goes with the flange section6h(seeFIG. 9).

As described above, with the scroll compressor1according to Embodiment 1, it is possible to prevent the orbiting scroll6from swinging due to the upsetting moment with the simple structure to enhance reducing the sliding loss as well as enhance reducing the refrigerant leakage loss in the entire compression chambers11.

Hereinafter, the construction of a scroll compressor1A according to Embodiment 2 will be described with reference toFIG. 11.FIG. 11is an enlarged cross-sectional view of the fixed scroll5of the scroll compressor1.

As illustrated inFIG. 11, the scroll compressor1A differs from the scroll compressor1according to Embodiment 1 (seeFIG. 5) in that the lubrication hole19is provided within the flange section5h.

In the thus-configured scroll compressor1A, similarly to the scroll compressor1according to Embodiment 1, it is possible to enhance reducing the sliding loss with the simple structure and enhance reducing the refrigerant leakage loss in the entire compression chambers11.

In the scroll compressor1A, the lubrication hole19is provided within the flange section5h. The flange section5his therefore sufficiently supplied with the lubricant13. This can reduce the sliding loss of the scroll compressor1A more than that of the scroll compressor1according to Embodiment 1.

Hereinafter, the construction of a scroll compressor1B according to Embodiment 3 will be described with reference toFIG. 12.FIG. 12is an enlarged cross-sectional view of the fixed scroll5of the scroll compressor1B.

As illustrated inFIG. 12, the scroll compressor1B differs from the scroll compressor1(seeFIG. 5) according to Embodiment 1 in that the sliding surface5fis provided with a plurality of flange sections5h.

In the thus-configured scroll compressor1B, similarly to the scroll compressor1according to Embodiment 1, it is possible to enhance reducing the sliding loss with the simple structure and enhance reducing the refrigerant leakage loss in the entire compression chambers11.

In the scroll compressor1B, additionally, the plurality of flange sections5hare provided in the sliding surface5fand are able to bear the pressing force of the orbiting scroll6composed of larger backpressure than that in the scroll compressor1according to Embodiment 1. The pressing force and upsetting moment can be thereby efficiently reduced in the scroll compressor1B. In other words, the stability of the orbiting scroll6is improved in the scroll compressor1B. With the scroll compressor1B, it is possible to prevent the orbiting scroll6from swinging and reduce the refrigerant leakage in the vicinity of the suction chamber5cwhere the seal length is short as well as reduce the refrigerant leakage in the entire compression chambers11.

Hereinafter, the construction of a scroll compressor1C according to Embodiment 4 will be described with reference toFIG. 13.FIG. 13is an enlarged cross-sectional view of the fixed scroll5of the scroll compressor1C.

As illustrated inFIG. 13, the scroll compressor1C differs from the scroll compressor1(seeFIG. 5) according to Embodiment 1 in that the depression sections5ginclude a non-machining surface which is not machined.

The surface in the depression sections5g, which have the non-machining surface, is rougher than the surface of the sliding surface. In the thus-configured scroll compressor1C, the lubricant efficiently retains in the depression sections5g. This improves the sealing performance between the sliding surface5fof the fixed scroll5and the sliding surface6fof the orbiting scroll6. In addition, the depression sections5gare partially not machined. This reduces the time and man-hours for the machining process of the scroll compressor1C and reduces the manufacturing cost thereof.

In the thus-configured scroll compressor1C, similarly to the scroll compressor1according to Embodiment 1, it is possible to enhance reducing the sliding loss with the simple structure and enhance reducing the refrigerant leakage loss in the compression chambers11.

In the scroll compressor1C, the sealing performance between the sliding surface5fof the fixed scroll5and the sliding surface6fof the orbiting scroll6can be improved more than that in the scroll compressor1according to Embodiment 1. In addition, compared with the scroll compressor1according to Embodiment 1, it is possible to significantly reduce the time and man-hours for the machining process of the scroll compressor1C and reduce the manufacturing cost thereof.

The present invention is not limited to the aforementioned embodiments and includes various modifications. For example, the aforementioned embodiments are described in detail to explain the present invention for easy understanding, and the present invention is not limited to apparatuses including all of the configurations described above. In addition, a part of the configuration of each embodiment can be replaced with the configuration of another embodiment. Alternatively, the configuration of each embodiment can be added to the configuration of another embodiment. Furthermore, a part of the configuration of each embodiment can be subjected to addition, deletion, and replacement of another configuration.

REFERENCE SIGNS LIST