JP7813215B2 - Scroll Compressor - Google Patents

Description

The present invention relates to scroll compressors used in refrigeration cycle devices such as heat pump water heaters, air conditioners, and refrigerators.

Scroll compressors used in refrigeration cycle devices such as heat pump water heaters, air conditioners, and freezers include those described in Japanese Patent Laid-Open Publication No. 7-197891 (Patent Document 1). Patent Document 1 describes a scroll-type fluid machine equipped with a fixed scroll having a spiral wrap portion erected on an end plate, and an orbiting scroll that is rotatably disposed opposite the fixed scroll and also has a spiral wrap portion erected thereon, forming multiple compression chambers between itself and the wrap portion of the fixed scroll. It describes that the wrap portion of at least one of the orbiting scroll or the fixed scroll is formed so that the axial clearance between it and the tooth base of the other scroll changes in multiple stages.

Japanese Unexamined Patent Publication No. 7-197891

In the device disclosed in Patent Document 1, an axial gap is provided between the spiral wrap portion and its mating tooth bottom, preventing friction and galling caused by thermal expansion of the wrap portion. In the device disclosed in Patent Document 1, the axial gap is formed to increase linearly toward the center of the wrap, where thermal expansion is greater, and is designed to take into account the thermal expansion of the wrap. However, no consideration is given to the fact that the pressure of the compressed gas can cause deformation of the end plate of the orbiting scroll, resulting in a change in the axial gap.

The object of the present invention is to provide a scroll compressor that can maintain an appropriate axial gap between the spiral wrap and its mating tooth base, taking into account deformation of the end plate due to the keyway, even when the end plate of the orbiting scroll is deformed by the pressure of the compressed gas.

To achieve the above object, the present invention provides a scroll compressor comprising: a fixed scroll having a spiral wrap standing on a base plate; an orbiting scroll having a spiral wrap standing on an end plate that is rotatable opposite the fixed scroll and forms multiple compression chambers between itself and the spiral wrap of the fixed scroll; and an Oldham ring for preventing the orbiting scroll from rotating. The orbiting scroll has a spiral sliding surface that faces the tips of the spiral wrap of the fixed scroll and is formed between the spiral wraps of the orbiting scroll; and a keyway formed on the back surface of the end plate that engages with the key of the Oldham ring. The spiral sliding surface extending from the outer periphery to the center of the orbiting scroll has a convex portion on the spiral sliding surface that corresponds to the portion where the keyway is provided.

Another feature of the present invention is a scroll compressor comprising: a fixed scroll having a spiral wrap standing on a base plate; an orbiting scroll having a spiral wrap standing on an end plate that is rotatably disposed opposite the fixed scroll and forms multiple compression chambers between the spiral wrap of the fixed scroll; and an Oldham ring for preventing the orbiting scroll from rotating on its axis; wherein the orbiting scroll has a keyway formed on the back surface of the end plate that engages with a key of the Oldham ring; the fixed scroll has a spiral sliding surface that faces the tooth tips of the spiral wrap of the orbiting scroll and is formed between the spiral wraps of the fixed scroll; and a convex portion is provided on the spiral sliding surface of the fixed scroll extending from the outer periphery toward the center of the fixed scroll at a portion where the keyway is provided.

Another feature of the present invention is a scroll compressor comprising: a fixed scroll having a spiral wrap standing on a base plate; an orbiting scroll having a spiral wrap standing on an end plate that is rotatably disposed opposite the fixed scroll and forms multiple compression chambers between the spiral wrap of the fixed scroll; and an Oldham ring for preventing the orbiting scroll from rotating on its axis; wherein the orbiting scroll has a keyway formed on the back surface of the end plate that engages with a key of the Oldham ring; the fixed scroll has a spiral sliding surface that faces the tooth tips of the spiral wrap of the orbiting scroll and is formed between the spiral wraps of the fixed scroll; and the spiral wrap extending from the outer periphery to the center of the orbiting scroll has a protrusion at the tooth tips of the spiral wrap of the orbiting scroll that corresponds to the portion where the keyway is provided.

Another feature of the present invention is a scroll compressor comprising: a fixed scroll having a spiral wrap standing on a base plate; an orbiting scroll rotatably disposed opposite the fixed scroll and having a spiral wrap standing on an end plate that forms multiple compression chambers between the spiral wrap of the fixed scroll; and an Oldham ring for preventing the orbiting scroll from rotating about its axis; wherein the orbiting scroll has a keyway formed on the back surface of the end plate that engages with a key of the Oldham ring; the orbiting scroll has a spiral sliding surface that faces the tooth tips of the spiral wrap of the fixed scroll and is formed between the spiral wraps of the orbiting scroll; and the spiral wrap extending from the outer periphery to the center of the fixed scroll has a protrusion at the tooth tips of the spiral wrap of the fixed scroll that corresponds to the portion where the keyway is provided.

The present invention has the advantage of providing a scroll compressor that can maintain an appropriate axial gap between the spiral wrap and its mating tooth bottom, taking into account deformation of the end plate due to the keyway, even if the end plate of the orbiting scroll is deformed by the pressure of the compressed gas.

1 is a longitudinal cross-sectional view showing a first embodiment of a scroll compressor according to the present invention; 2 is a cross-sectional view taken along the line II-II in FIG. 1, showing a state in which the fixed scroll and the orbiting scroll shown in FIG. 1 are engaged with each other; FIG. FIG. 2 is an enlarged partial cross-sectional view showing the periphery of a back pressure valve in the scroll compressor shown in FIG. 1 . FIG. 2 is a development view schematically showing the tooth tip shape of a fixed scroll and the tooth bottom shape of a rotating scroll. FIG. 4 is a schematic diagram illustrating the pressure distribution acting on the orbiting scroll. FIG. 4 is a perspective view illustrating a deformation state of the end plate of the orbiting scroll. FIG. 4 is a rear perspective view illustrating the shape of the rear surface of the orbiting scroll. FIG. 2 is a development view schematically showing the tooth tip shape of the fixed scroll and the tooth bottom shape of the orbiting scroll in the scroll compressor according to the first embodiment of the present invention. FIG. 4 is a plan view illustrating a range in which a convex portion is formed on the orbiting scroll. FIG. 10 is a development view for explaining a first modified example of the present invention, which diagrammatically shows the tooth bottom shape of the fixed scroll and the tooth tip shape of the orbiting scroll. FIG. 11 is a diagram illustrating a second modified example of the present invention, and corresponds to FIG. 10 . FIG. 10 is a diagram illustrating a third modified example of the present invention, and corresponds to FIG. 8 .

Specific embodiments of the scroll compressor of the present invention will be described below with reference to the drawings. Note that in each drawing, parts with the same reference numerals indicate the same or corresponding parts.

A scroll compressor according to a first embodiment of the present invention will be described with reference to Figures 1 to 8. First, the overall configuration of the scroll compressor according to this embodiment will be described with reference to Figures 1 and 2.
1 is a longitudinal sectional view showing a scroll compressor according to a first embodiment of the present invention. As shown in FIG. 1, the scroll compressor 1 is configured by accommodating a compression mechanism 3, a motor 4, and the like in a sealed container (case) 2.

In the compression mechanism 3, a fixed scroll 7 fixed to a frame 5 is meshed with an orbiting scroll 8 to form a compression chamber 13. Rotation of the motor 4 causes the orbiting scroll 8 to orbit via a crankshaft (rotating shaft) 10, thereby reducing the volume of the compression chamber 13 and performing a compression operation.

As this compression occurs, working fluid is drawn into the suction chamber 20 (see also Figure 2) from the suction port 14, undergoes a compression stroke in the compression chamber 13, and is then discharged from the discharge port 15 into the first discharge space 16a that constitutes the discharge space 16. The fluid then passes through the second discharge space 16b, which is the upper discharge space 16 inside the sealed container 2 and is connected to the first discharge space 16a, and is then discharged out of the sealed container 2 from the discharge pipe 6.

The fixed scroll 7 comprises a disk-shaped base plate 7a, spiral wraps (hereinafter referred to as fixed wraps or simply wraps) 7b erected on the base plate 7a, tooth roots (spiral sliding surfaces) 7c which are the surface of the base plate 7a between the wraps 7b, and a cylindrical support portion 7d located on the outer periphery of the base plate 7a and surrounding the wraps 7b. A mirror plate surface 7e is formed on the support portion 7d, and the height of this mirror plate surface 7e is configured to be approximately the same as the height of the tooth tips 7f which are the tip surfaces of the wraps 7b. The mirror plate surface 7e also serves as the sliding surface where the support portion 7d of the fixed scroll 7 comes into contact with the mirror plate 8a of the orbiting scroll 8.

The support portion 7d of the fixed scroll 7 is fixed to the frame 5 with bolts or the like, and the frame 5, which is integrally joined to the fixed scroll 7, is fixed to the sealed container 2 by a fixing means such as welding.

The orbiting scroll 8 is disposed opposite the fixed scroll 7, and is rotatably mounted within the frame 5 with the spiral wrap 7b of the fixed scroll 7 and the spiral wrap 8b of the orbiting scroll 8 (hereinafter referred to as the orbiting wrap or simply the wrap) meshing together. The orbiting scroll 8 has the spiral wrap 8b erected from the tooth base (spiral sliding surface) 8c, which is the surface of a disc-shaped end plate 8a, and an orbiting boss portion 8d provided in the center of the back surface of the end plate 8a. The surface of the outer periphery of the end plate 8a that comes into contact with the fixed scroll 7 forms the end plate surface 8e of the orbiting scroll 8.

The tooth tip 8f at the tip of the wrap 8b of the orbiting scroll 8 is configured to face the tooth bottom 7c of the fixed scroll 7 with a small gap. Similarly, the tooth tip 7f at the tip of the wrap 7b of the fixed scroll 7 is also configured to face the tooth bottom 8c of the orbiting scroll 8 with a small gap.

An oil reservoir 25 for storing lubricating oil (hereinafter also referred to as refrigeration oil or oil) is provided at the bottom of the sealed container 2, which houses the compression mechanism 3, motor 4, etc. The motor 4 is composed of a rotor 4a and a stator 4b, and the crankshaft 10 is fixed integrally to the rotor 4a. The crankshaft 10 is rotatably supported by a main bearing 5a provided in the frame 5, and is coaxial with the central axis of the fixed scroll 7.

An eccentric crank portion 10a is provided at the tip of the crankshaft 10, and this crank portion 10a is inserted into an orbiting bearing 8g provided on the orbiting boss portion 8d of the orbiting scroll 8, allowing the orbiting scroll 8 to orbit as the crankshaft 10 rotates.

The central axis of the orbiting scroll 8 is offset by a predetermined distance (orbital radius) from the central axis of the fixed scroll 7. Furthermore, the wrap 8b of the orbiting scroll 8 is overlapped with the wrap 7b of the fixed scroll 7, shifted circumferentially by a predetermined angle (typically 180 degrees).

Reference numeral 12 denotes an Oldham ring for orbiting the orbiting scroll 8 relative to the fixed scroll 7 while restraining it from rotating on its axis. This Oldham ring 12 has two keys (protrusions) arranged diagonally on the top surface of the annular ring, and two keys arranged on the bottom surface, offset by 90 degrees from the keys on the top surface. The keys on the top surface slidably engage with key groove 8h provided in the orbiting scroll 8, and the keys on the bottom surface slidably engage with key groove 5b provided in the frame 5.

Figure 2 is a cross-sectional view taken along the line II-II in Figure 1, showing the fixed scroll 7 and orbiting scroll 8 meshing together. In Figure 2, the orbiting wrap 8b of the orbiting scroll 8 is shown in cross section, and the portion corresponding to the outer periphery of the end plate 8a of the orbiting scroll 8 is shown by a two-dot chain line (imaginary line).

As shown in Figure 2, multiple crescent-shaped compression chambers 13 (inner orbiting compression chambers 13a, outer orbiting compression chambers 13b) are formed between the fixed wrap 7b and the orbiting wrap 8b. When the orbiting scroll 8 is orbited, the volume of each compression chamber 13 continuously decreases as it moves toward the center, performing a compression operation. The inner orbiting compression chamber 13a is a compression chamber formed inside the orbiting wrap 8b, and the outer orbiting compression chamber 13b is a compression chamber formed outside the orbiting wrap 8b.

20 is the suction chamber, which is the space in the process of sucking in fluid. This suction chamber 20 becomes the compression chamber 13 when the phase of the orbiting motion of the orbiting scroll 8 advances and the fluid is completely trapped inside.

1 and 2, the suction port 14 is provided in the fixed scroll 7. The suction port 14 is bored on the outer periphery of the base plate 7a of the fixed scroll 7 so as to communicate with the suction chamber 20.
The discharge port 15 is bored near the center of the scroll of the base plate 7 a of the fixed scroll 7 so as to communicate with the compression chamber 13 on the innermost periphery side.

When the crankshaft 10 is rotated by the motor unit 4 shown in Figure 1, the orbiting scroll 8 orbits with a predetermined orbital radius around the central axis of the fixed scroll 7. As a result, the working fluid drawn in through the suction port 14, such as refrigerant gas circulating through the refrigeration cycle, is compressed sequentially within each compression chamber 13, and the compressed working fluid is discharged from the discharge port 15 into the first discharge space 16a, then flows into the second discharge space 16b and is supplied from the discharge pipe 6 to an external device, such as a refrigeration cycle.

Oil is supplied to each sliding part, such as the main bearing 5a and the slewing bearing 8g, using a differential pressure oil supply structure. This means that the interior of the sealed container 2 is at discharge pressure, and the oil reservoir 25 at the bottom of the sealed container 2 is also at discharge pressure. The differential pressure oil supply structure uses the pressure difference between the high-pressure oil in the oil reservoir 25 and the pressure in the back pressure chamber (the pressure between the discharge pressure and the suction pressure). Therefore, due to the pressure difference, the lubricating oil in the oil reservoir 25 is sucked through the lubricating oil suction port 10c located at the bottom of the crankshaft 10, and is sent to the top of the crankshaft 10 through a through-hole (oil supply hole) 10b formed axially in the crankshaft 10.

As the lubricating oil flows through the through-hole 10b, a portion of it is supplied to the auxiliary bearing 23 supporting the lower part of the crankshaft 10 via a horizontal hole 10d formed in the crankshaft 10. After lubricating the auxiliary bearing 23, the oil is then returned to the oil reservoir 25 at the bottom of the sealed container 2. The remaining majority of the lubricating oil flowing through the through-hole 10b flows into the main bearing 5a via a horizontal hole 10e formed in the crankshaft 10 and into the slewing bearing 8g through the upper space 24 of the crankshaft 10, lubricating these sliding parts. The oil then is throttled as it passes through the tiny gaps between the main bearing 5a and the slewing bearing 8g, decompressing and expanding, before flowing into the backpressure chamber 18.

The lubricating oil that flows into the back pressure chamber 18 flows into the suction chamber 20 and the compression chamber 13, lubricating the sliding surfaces and gaps between the spiral wraps 7b and 8b, as well as between the compression chambers 13. The lubricating oil is then discharged together with the refrigerant gas from the discharge port 15 into the first discharge space 16a. The lubricating oil and refrigerant gas collide with the discharge cover 26 that defines the first discharge space 16a, separating the oil and refrigerant gas, before changing direction and flowing laterally into the second discharge space 16b. The refrigerant gas that flows into the second discharge space 16b is then discharged from the discharge pipe 6 to the refrigeration cycle, etc., while the lubricating oil returns to the oil sump 25 at the bottom of the compressor via a passage (not shown) formed on the outer periphery of the fixed scroll 7 and the outer periphery of the frame 5, via the motor chamber 27, and so on.

Next, the function of the back pressure chamber 18 will be explained. In the scroll compressor 1, the compression action generates an axial force (separation force) that tries to separate the fixed scroll 7 and the orbiting scroll 8 from each other. When this axial force causes the two scrolls to separate, a phenomenon known as orbiting scroll 8 separation, the sealing of the compression chamber 13 deteriorates, reducing the efficiency of the scroll compressor 1.

Therefore, the back pressure chamber 18, which has a pressure (intermediate pressure) between the discharge pressure and the suction pressure, is provided on the back side of the end plate 8a of the orbiting scroll 8. The pressure (back pressure) in this back pressure chamber 18 cancels out the separating force and presses the orbiting scroll 8 against the fixed scroll 7. If the pressing force is too large, the sliding loss between the end plate surface 8e of the orbiting scroll 8 and the end plate surface 7e of the fixed scroll 7 increases, reducing the efficiency of the scroll compressor 1.

In other words, there is an optimal value for the back pressure; if it is too low, the compression chamber will not seal well and thermal fluid loss will increase, while if it is too high, sliding loss will increase. Therefore, maintaining the back pressure at an optimal value is important for improving the performance and reliability of the compressor.

To obtain this optimal back pressure value, the scroll compressor of this embodiment is provided with a back pressure valve 31 in the support portion 7d of the fixed scroll 7 to adjust the back pressure in the back pressure chamber 18, as shown in Figure 1.

Next, the configuration of the periphery of the back pressure valve 31 will be described with reference to Fig. 3. Fig. 3 is a partial cross-sectional view showing an enlarged view of the periphery of the back pressure valve 31 in the scroll compressor shown in Fig. 1.
The periphery of the back pressure valve 31 is made up of a back pressure valve inlet passage (space communicating with the back pressure chamber 18) 32a that connects the back pressure chamber 18 and the back pressure valve 31, a back pressure valve outlet passage (space communicating with the compression chamber 13) 32c that connects the back pressure valve 31 and the compression chamber 13, and a space 32b that houses the back pressure valve 31. The back pressure valve 31 is provided with a valve 31a that separates the back pressure valve inlet passage 32a from the back pressure valve outlet passage 32c. The valve 31a is arranged so as to be pressed against the opening of the back pressure valve inlet passage 32a by a spring 31b fixed to a stopper 31c.

When the load due to the pressure in the back pressure valve inlet passage 32a (i.e., the back pressure, which is the pressure in the back pressure chamber 18) exceeds the combined load of the pressure in the space 32b (i.e., the pressure in the compression chamber) introduced via the back pressure valve outlet passage 32c and the spring 31b, the valve 31a moves upward to connect the back pressure valve inlet passage 32a and the back pressure valve outlet passage 32c. In other words, when the pressure in the back pressure chamber 18 exceeds a certain value, the back pressure valve 31 releases the fluid in the back pressure chamber 18 toward the compression chamber 13, thereby adjusting the pressure (back pressure) in the back pressure chamber 18 to an appropriate value.

The basic configuration of the scroll compressor 1 has been explained above. Next, we will explain the axial clearance between the tooth bottom 7c or tooth tip 7f of the fixed scroll 7 and the tooth bottom 8c or tooth tip 8f of the orbiting scroll 8, which is an important component of this embodiment. The axial clearance refers to the minute clearance between the tooth tip 7f of the wrap 7b of the fixed scroll 7 and the tooth bottom (spiral sliding surface) 8c of the orbiting scroll 8, or the minute clearance between the tooth bottom (spiral sliding surface) 7c of the fixed scroll 7 and the tooth tip 8f of the wrap 8b of the orbiting scroll 8.

If this axial clearance is too small, sliding loss at the wrap tips (tooth tips 7f, 8f) increases, and the wrap tips come into contact with the tooth bases (spiral sliding surfaces) 7c, 8c, causing wear and galling, reducing reliability. Furthermore, if the axial clearance is too large, the sealing of the compression chamber 13 decreases, increasing leakage, increasing thermal fluid loss, and reducing the efficiency of the scroll compressor 1. Therefore, just as adjusting the pressure (back pressure) in the back pressure chamber 18 to an appropriate value, maintaining the axial clearance at an optimal value is important for improving the performance and reliability of the scroll compressor 1.

The scroll compressor 1 draws refrigerant gas through the suction port 14 shown in Figure 2, compresses it sequentially in the crescent-shaped compression chambers 13, and discharges the compressed refrigerant gas from the discharge port 15. As the refrigerant gas is compressed, its temperature increases. Therefore, the temperature of the fixed wrap 7b and orbiting wrap 8b is higher in the central portion near the discharge port 15 than in the peripheral portion near the suction port 14. As a result, the higher-temperature central portion of the wrap experiences greater thermal expansion than the peripheral portion, increasing the wrap height due to thermal expansion. For example, if the wrap height of the central portion of the fixed wrap 7b increases, the axial clearance between the tooth root 8c of the opposing orbiting scroll 8 disappears, resulting in increased sliding loss and reduced reliability due to wear and galling caused by contact. The same is true for the wrap tooth tips of the orbiting wrap 8b and the tooth root 7c of the opposing fixed scroll 7.

To solve this problem, as shown in Figure 4, it has been considered to design the tooth bottom (spiral sliding surface) 8c of the orbiting scroll 8 as a sloped shape that steadily deepens from the wrap outer periphery toward the wrap center, thereby avoiding contact between the tooth tip 7f of the fixed wrap 7b and the tooth bottom 8c of the orbiting scroll 8. Note that Figure 4 is a development that schematically shows the tooth bottom shape (tooth bottom recessed shape) of the orbiting scroll, and is a comparative example to Example 1, showing the depth of the tooth bottom along the spiral shape of the orbiting wrap 8b. The left side of the horizontal axis indicates the outer periphery of the orbiting wrap 8b, and the right side indicates the center of the orbiting wrap 8b.

In the figure, 40 represents the axial gap between the tooth tip 7f of the wrap 7b of the fixed scroll 7 and the tooth bottom 8c formed on the end plate 8a of the orbiting scroll 8 when the scroll compressor 1 is not operating, i.e., when there is no thermal expansion. The slope shape of the tooth bottom (spiral sliding surface) 8c formed between the spiral wraps of the orbiting scroll 8 is determined so that this axial gap 40 becomes almost zero when the orbiting wrap 8b thermally expands during operation of the scroll compressor 1.

While the tooth bottom shape of the orbiting scroll 8 has been described above, the axial gap 40 can also be formed by sloping the tooth bottom (spiral sliding surface) 7c of the fixed scroll 7 so that the depth monotonically increases from the wrap outer periphery toward the wrap center. Furthermore, the axial gap 40 can also be formed by providing the sloped shape on the tooth tip 7f or 8f side of the spiral wrap 7b or 8b, rather than on the wrap tooth bottom 7c or 8c.

As explained in Figure 4, if only thermal expansion of the wrap is considered, for example, if the tooth bottom (spiral sliding surface) 8c of the orbiting scroll 8 is formed in a sloped shape that monotonically deepens from the outer periphery of the wrap toward the center of the wrap, contact between the tooth tip 7f of the fixed wrap 7b and the tooth bottom 8c of the orbiting scroll 8 can be avoided.

However, in reality, the end plate 8a is also deformed by the pressure acting on the orbiting scroll 8. Therefore, simply carving the tooth bottom into a monotonous slope shape will either locally reduce the axial clearance due to the acting pressure, increasing sliding loss, or expand the axial clearance, increasing thermal fluid loss.

5 and 6, the pressure acting on the orbiting scroll 8 will be described. Fig. 5 is a schematic diagram illustrating the pressure distribution acting on the orbiting scroll 8, and Fig. 6 is a perspective view illustrating the deformation state of the end plate 8a of the orbiting scroll 8.
As shown in FIG. 5 , discharge pressure Pd acts on the area inside the orbiting bearing 8g on the back side of the orbiting scroll 8, while back pressure Pb (a pressure between the discharge pressure and the suction pressure) acts on the area outside the orbiting bearing 8g, which is the back pressure chamber 18. The resultant force of these pressures serves as a force pushing up the orbiting scroll 8. The outermost periphery of the end plate 8a on the top side of the orbiting scroll 8 faces the back pressure chamber 18, so back pressure Pb acts thereon. As the pressure moves from there toward the suction chamber 20 or the compression chamber 13 (see FIGS. 1 and 2 ), which are located slightly inward, the pressure temporarily drops to suction pressure Ps or the pressure inside the compression chamber 13 in the middle of compression. Further inward, the compression chamber 13 becomes a compression chamber 13 where compression has progressed, so the pressure rises, eventually reaching discharge pressure Pd at the center where the discharge port 15 is located. The resultant force of these pressures serves as a force pushing down the orbiting scroll 8. The force obtained by subtracting the downward force from the upward force becomes the pressing force that presses the orbiting scroll 8 against the fixed scroll 7 .

When these pressures act on the orbiting scroll 8, in the region of the end plate 8a where suction pressure Ps acts on the upper surface and back pressure Pb acts on the back surface, the load acts from bottom to top, causing the outer periphery of the wrap 8b to bend upward and the center of the wrap 8b to bend downward, forming a concave shape, as shown in Figure 6. If this type of deformation is the only problem, then it is sufficient to make the tooth bottom 8c etc. a sloped shape that is monotonically dug deeper toward the center of the wrap 8b, similar to the tooth bottom shape that accommodates thermal expansion, as explained using Figure 4.

However, while a key groove (slotted counterbore) 8h is typically provided on the back surface of the orbiting scroll 8 for attaching the key portion (protrusion) of the Oldham ring 12, as shown in Figure 7, no consideration is given to deformation of the orbiting scroll 8 due to this key groove 8h.

Next, the configuration of a scroll compressor according to a first embodiment of the present invention will be described using Figures 7 to 9. Figure 7 is a rear perspective view illustrating the shape of the rear surface of the orbiting scroll, Figure 8 is a development diagram that schematically illustrates the tooth tip shape of the fixed scroll and the tooth bottom shape (tooth bottom recessed shape) of the orbiting scroll in a scroll compressor according to a first embodiment of the present invention, and Figure 9 is a plan view illustrating the range in which the convex portions provided on the orbiting scroll are formed.

As mentioned above, to counter deformation caused by thermal expansion of the orbiting scroll 8 or the pressure described in Figures 5 and 6, the tooth bottom 8c can be made to have a sloped shape that steadily deepens toward the center of the wrap 8b, as described using Figure 4, for example. However, in reality, the orbiting scroll 8 is deformed by the key groove 8h provided on the back surface of the orbiting scroll 8.

In other words, the area where the key grooves 8h are provided has a thinner plate thickness of the end plate 8a, resulting in lower rigidity. As explained using Figures 5 and 6, the pressure acting on the end plate of the orbiting scroll 8 causes the end plate 8a to deform into a roughly concave shape as explained in Figure 6. In addition to this deformation, the area where the key grooves 8h are provided and where rigidity is low also deforms so as to bend at the imaginary line 41 connecting the key grooves 8h, shown by the dashed line in Figure 7.

When the end plate 8a of the orbiting scroll 8 is bent, the tooth tips of the orbiting wrap 8b move away from the tooth root 7c of the fixed scroll 7 at the bent portion (near the imaginary line 41), and the tooth tips of the fixed wrap 7b also move away from the tooth root 8c of the orbiting scroll 8. Therefore, the axial gap 40 becomes wider at the tooth tips 8f and tooth root 8c of the orbiting wrap 8b located on the opposite side of the portion where the key groove 8h is provided.

To prevent this axial gap 40 from widening during operation, in this embodiment 1, the depth of the tooth bottom 8c between the orbiting wraps 8b located on the opposite side of the portion where the keyway 8h is provided is locally made shallower, resulting in a tooth bottom shape resembling padding.

Specifically, as shown in Figure 8, a protrusion (padded portion) 50 is formed on the tooth bottom 8c at bending position 42 (the position corresponding to the position of imaginary line 41 in Figure 7) where the key groove 8h is located, so that the padding is thick (so that the axial gap 40 is reduced) at the tooth bottom 8c. Because the head plate 8a bends most significantly at bending position 42 shown in Figure 8, the protrusion 50 is formed to be highest (thickest padded portion) at this bending position 42, and is formed so that the height of the protrusion 50 decreases (the amount of padded portion decreases) as it moves away from bending position 42.

Next, a preferred shape of the protrusion 50 will be described with reference to FIGS.
As shown in Figure 8, in this embodiment, the convex portion 50 is provided near a portion of the tooth bottom 8c corresponding to bending position 42 (a position corresponding to imaginary line 41 in Figure 7, hereinafter simply referred to as "position") caused by the key groove 8h. Since the end plate 8a bends most greatly at bending position 42, the convex portion 50 is formed so that its height at this position 42 is the highest peak, and the height of the convex portion 50 is gradually reduced as it moves away from this peak position along the tooth bottom (spiral sliding surface) 8c, forming slopes 50a, 50b, 50c, and 50d.

That is, the protrusion 50 is composed of multiple slopes 50a, 50b, 50c, and 50d with its center as its apex. In this embodiment, the slopes of the slopes 50b and 50d extending from the center toward the central portion are greater than the slopes of the slopes 50a and 50c extending from the center toward the outer periphery. Furthermore, the center of the protrusion 50 is configured to be located on the centerline of the key groove 8h in the groove width direction, i.e., on the imaginary line 41.

Two keyways 8h are provided, positioned on opposite sides of the approximate center of the end plate 8a of the orbiting scroll 8. Therefore, the convex portions 50 are provided on the tooth bottoms (spiral sliding surfaces) 8c (or the tooth tips of the spiral wraps) corresponding to the positions of the two keyways 8h. In other words, when the intersection of the imaginary line 41 connecting the two keyways 8h and the tooth bottoms (spiral sliding surfaces) 8c is used as a reference point, the convex portions 50 are provided on the tooth bottoms (spiral sliding surfaces) 8c (or the tooth tips 8f of the spiral wraps 8b corresponding to the reference point) at the reference point. The convex portions 50 are configured so that the gradient of the inclination from the reference point toward the center is greater than the gradient of the inclination from the reference point toward the outer periphery. The reference point corresponds to the bending position 42 described above.

Figure 9 shows the range of the protrusions 50 formed on the tooth bottom 8c of the orbiting scroll 8. As shown in Figure 9, the protrusions 50 are formed in regions 51a, 51b, 51c, and 51d on the tooth bottom (spiral sliding surface) 8c. Here, regions 51a, 51b, 51c, and 51d correspond to the aforementioned inclined surfaces 50a, 50b, 50c, and 50d, respectively. That is, when the orbiting scroll 8 is viewed from above, in this embodiment, the protrusions 50 are formed in the ranges of regions 51a, 51b, 51c, and 51d shown in Figure 9. Of the two protrusions 50 provided corresponding to the two keyways 8h, the outer peripheral protrusion is provided in the ranges shown in regions 51a and 51b, while the central protrusion is provided in the ranges shown in regions 51c and 51d. The vertices of the two protrusions 50 are formed to coincide with the bending position 42.

Note that the formation range of the convex portion 50 shown in Figure 9 is an example; in this embodiment, all of the regions 51a to 51d are formed within a 90-degree range from the bending position 42. As a result, the length of the slope 50a in region 51a, which is located closest to the periphery, is the longest, and the length of the slope in region 51d, which is located closest to the center, is the shortest.

The range of each region 51a-51d forming the convex portion 50 is not limited to 90 degrees; for example, it may be within a range of 45 degrees from the bending position 42. Even if the range of each region 51a-51d is 45 degrees, it is possible to configure it so that the axial gap 40 at the position 42 where the end plate 8a bends most greatly is small. In other words, if the intersection of the imaginary line 41 connecting the two keyways 8h and the tooth bottom (spiral sliding surface) 8c is used as a reference (corresponding to the bending position 42), the apex of the convex portion 50 is located at the tooth bottom 8c at the reference portion (or the tooth tip of the spiral wrap corresponding to the reference), and the lengths of the slopes 50a, 50c extending from the reference toward the outer periphery and the lengths of the slopes 50b, 50d extending toward the center should each be within a range of 45-90 degrees in terms of wrap angle.

In addition, excluding the portion where the protrusion 50 is provided, the axial gap 40 between the tooth bottom (spiral sliding surface) 8c and the tooth tip 7f of the spiral wrap 7b is gradually increased from the outer periphery toward the center, taking thermal expansion into consideration. The tooth bottom 8c (or the tooth tip 7f of the spiral wrap 7b) is formed along a standard slope that takes thermal expansion into account from the outer periphery toward the center. In this way, the axial gap can be determined with thermal expansion taken into consideration.

It is preferable that the ends of the convex portions 50 facing the outer periphery and the ends facing the center are each configured to be on the reference slope. It is also preferable that the portion of the tooth bottom 8c (or the tooth tip of the spiral wrap) between the two convex portions 50 provided corresponding to the positions of the two keyways 8h and perpendicular to the imaginary line 41 connecting the two keyways 8h is also configured to be on the reference slope.

By configuring as described above, it is possible to optimize the axial clearance, taking into account not only the thermal expansion of the wrap but also the deformation of the end plate 8a due to the key groove 8h, further reducing thermal fluid loss and improving the efficiency of the compressor.

Note that Figure 8 illustrates the case where the protrusion 50 is provided on the tooth bottom 8c of the orbiting scroll 8 to optimize the axial gap 40 between the tooth bottom 8c of the orbiting scroll 8 and the tooth tip 7f of the fixed scroll 7. However, the same effect can be achieved by providing the protrusion 50 on the tooth bottom 7c of the fixed scroll 7 to optimize the axial gap 40. Furthermore, the same effect can be achieved by providing the protrusion 50 on the tooth tip 8f of the orbiting scroll 8 or the tooth tip 7f of the fixed scroll 7, rather than on the tooth bottom 8c or 7c, to optimize the axial gap 40. Below, Figures 10 to 12 will be used to specifically explain modified examples of the present invention in which the position of the protrusion 50 is changed.

(Variation 1)
10 is a diagram for explaining Example 1 of the present invention, and is a development view showing a schematic diagram of the tooth bottom shape of the fixed scroll and the tooth tip shape of the orbiting scroll. In the example shown in Fig. 10, the tooth bottom 7c of the fixed scroll 7 is configured to gradually become deeper in a slope shape from the outer periphery toward the center in consideration of thermal expansion, and a convex portion 50 is provided near position 42 of the tooth bottom 7c of the fixed scroll 7. The other configurations are the same as those of Example 1.

Even with this configuration, the axial gap 40 between the tooth bottom 7c of the fixed scroll 7 and the tooth tip 8f of the orbiting scroll 8 can be optimized, just as in Example 1. In other words, it is possible to optimize the axial gap taking into account not only the thermal expansion of the wrap but also the deformation of the end plate 8a due to the key groove 8h, thereby reducing thermal fluid loss and improving the efficiency of the compressor.

As with Example 1 shown in Figure 8, the convex portion 50 may also be provided on the tooth bottom 8c of the orbiting scroll 8, or the convex portion may not be provided on the tooth bottom 8c of the orbiting scroll 8, and the tooth bottom 8c may not be sloped.

(Variation 2)
Fig. 11 is a diagram illustrating a second modified example of the present invention, and corresponds to Fig. 10. In the example shown in Fig. 11, the tooth tips 8f of the orbiting scroll 8 are configured to gradually become lower in a sloped shape from the outer periphery toward the center, taking thermal expansion into consideration, and a protrusion 50 is provided near a position 42 of the tooth tips 8f of the orbiting scroll 8. The other configurations are the same as those of the first embodiment and the first modified example.

Even with this configuration, the axial gap 40 between the tooth bottom 7c of the fixed scroll 7 and the tooth tip 8f of the orbiting scroll 8 can be optimized in the same way as in Example 1, and it is possible to optimize the axial gap taking into account not only the thermal expansion of the wrap but also the deformation of the end plate 8a due to the key groove 8h, thereby achieving the same effects as in Example 1.

Note that, similar to the shape of the tooth tips 8f of the orbiting scroll 8, the convex portions 50 may also be provided on the tooth tips 7f of the fixed scroll 7, or the tooth tips 7f of the fixed scroll 7 may not be provided with convex portions and the tooth tips 7f may not be sloped. Furthermore, as in Example 1 and Variation 1 shown in Figures 8 and 10, the convex portions 50 may also be provided on the tooth bottom 8c of the orbiting scroll 8 or the tooth bottom 7c of the fixed scroll 7.

(Variation 3)
Fig. 12 is a diagram illustrating a third modified example of the present invention, and corresponds to Fig. 8. In the example shown in Fig. 12, the tooth tips 7f of the fixed scroll 7 are configured to gradually become lower in a sloped shape from the outer periphery toward the center, taking thermal expansion into consideration, and a protrusion 50 is provided near a position 42 of the tooth tips 7f of the fixed scroll 7. The other configurations are the same as those of the first embodiment and the first modified example.

Even with this configuration, the axial gap 40 between the tooth tip 7f of the fixed scroll 7 and the tooth bottom 8c of the orbiting scroll 8 can be optimized in the same way as in Example 1, and it is possible to optimize the axial gap taking into account not only the thermal expansion of the wrap but also the deformation of the end plate 8a due to the key groove 8h, thereby achieving the same effects as in Example 1.

Note that, similar to the shape of the tooth tip 7f of the fixed scroll 7, the convex portion 50 may also be provided on the tooth tip 8f of the orbiting scroll 8, or the tooth tip 8f of the orbiting scroll 8 may not be provided with a convex portion, and the tooth tip 8f may not be sloped. Furthermore, as in Example 1 and Variation 1 shown in Figures 8 and 10, the convex portion 50 may also be provided on the tooth bottom 8c of the orbiting scroll 8 or the tooth bottom 7c of the fixed scroll 7.

As explained above, by configuring the present invention as in Example 1 and each of the modified examples, a convex portion is provided on at least one of the tooth bottoms or tooth tips of the orbiting scroll corresponding to the keyway of the orbiting scroll, and the tooth bottoms or tooth tips of the fixed scroll. Therefore, even if the head plate of the orbiting scroll is deformed by the pressure of the compressed gas, a scroll compressor can be obtained that can appropriately maintain the axial gap between the spiral wrap and its mating tooth bottom, taking into account the deformation of the head plate due to the keyway. Therefore, friction and galling between the tip ends (tooth tips) of the wraps of the fixed scroll and orbiting scroll and the tooth bottoms can be suppressed, and leakage loss at the tip ends of the wraps can be reduced, further improving the efficiency of the scroll compressor, resulting in a highly efficient scroll compressor.

The present invention is not limited to the above-described embodiments or modifications, but includes various other modifications. Furthermore, the above-described embodiments and modifications have been described in detail to clearly explain the present invention, and are not necessarily limited to those having all of the configurations described.

1: scroll compressor, 2: sealed container (case), 3: compression mechanism part,
4: motor section, 4a: rotor, 4b: stator,
5: frame, 5a: main bearing, 5b: keyway,
6: discharge pipe,
7: fixed scroll, 7a: base plate, 7b: spiral wrap (fixed wrap, wrap),
7c: Tooth bottom (spiral sliding surface), 7d: Support part, 7e: Mirror plate surface, 7f: Tooth tip,
8: orbiting scroll, 8a: end plate, 8b: spiral wrap (orbiting wrap, wrap),
8c: tooth bottom (spiral sliding surface), 8d: turning boss portion, 8e: end plate surface,
8f: tooth tip, 8g: slewing bearing, 8h: keyway,
10: crankshaft (rotating shaft), 10a: crank portion, 10b: through hole (oil supply hole),
10c: lubricating oil suction port, 10d, 10e: horizontal holes,
12: Oldham Ring,
13: compression chamber, 13a: turning inner line side compression chamber, 13b: turning outer line side compression chamber,
14: suction port, 15: discharge port,
16: ejection space, 16a: first ejection space, 16b: second ejection space,
18: back pressure chamber, 20: suction chamber,
23: auxiliary bearing, 24: upper space,
25: oil reservoir, 26: discharge cover, 27: motor chamber,
31: back pressure valve, 31a: valve, 31b: spring, 31c: stopper,
32a: back pressure valve inflow path, 32b: space, 32c: back pressure valve outflow path,
33: Stopcock,
40: Axial clearance, 41: Virtual line (dotted line) (connecting keyways),
42: bending position,
50: protrusion (thickened portion), 50a, 50b, 50c, 50d: inclined surface,
51a, 51b, 51c, 51d: Areas (where protrusions are formed).

Claims (12)

A scroll compressor comprising: a fixed scroll having a spiral wrap standing on a base plate; an orbiting scroll which is rotatably disposed opposite the fixed scroll and has a spiral wrap standing on an end plate, the orbiting scroll forming a plurality of compression chambers between the orbiting scroll and the spiral wrap of the fixed scroll; and an Oldham ring for preventing the orbiting scroll from rotating on its axis,
the orbiting scroll has a spiral sliding surface that faces the tooth tips of the spiral wraps of the fixed scroll and is formed between the spiral wraps of the orbiting scroll, and a key groove that is formed on the back surface of the end plate and engages with a key of the Oldham ring,
a convex portion is provided on the spiral sliding surface extending from the outer periphery side toward the center side of the orbiting scroll at a portion of the spiral sliding surface corresponding to a portion where the key groove is provided. A scroll compressor comprising: a fixed scroll having a spiral wrap standing on a base plate; an orbiting scroll which is rotatably disposed opposite the fixed scroll and has a spiral wrap standing on an end plate, the orbiting scroll forming a plurality of compression chambers between the orbiting scroll and the spiral wrap of the fixed scroll; and an Oldham ring for preventing the orbiting scroll from rotating on its axis,
the orbiting scroll has a key groove formed on the back surface of the end plate and adapted to engage with a key of the Oldham ring;
the fixed scroll has a spiral sliding surface that faces the tooth tips of the spiral wraps of the orbiting scroll and is formed between the spiral wraps of the fixed scroll,
a convex portion is provided on the spiral sliding surface of the fixed scroll, the convex portion being located at a portion of the spiral sliding surface extending from the outer periphery side toward the center side of the fixed scroll, the convex portion being located at a portion of the spiral sliding surface of the fixed scroll that corresponds to a portion where the key groove is provided. A scroll compressor comprising: a fixed scroll having a spiral wrap standing on a base plate; an orbiting scroll which is rotatably disposed opposite the fixed scroll and has a spiral wrap standing on an end plate, the orbiting scroll forming a plurality of compression chambers between the orbiting scroll and the spiral wrap of the fixed scroll; and an Oldham ring for preventing the orbiting scroll from rotating on its axis,
the orbiting scroll has a key groove formed on the back surface of the end plate and adapted to engage with a key of the Oldham ring;
the fixed scroll has a spiral sliding surface that faces the tooth tips of the spiral wraps of the orbiting scroll and is formed between the spiral wraps of the fixed scroll,
a spiral wrap extending from the outer periphery to the center of the orbiting scroll has a protrusion at a tooth tip portion of the spiral wrap of the orbiting scroll that corresponds to a portion where the key groove is provided. A scroll compressor comprising: a fixed scroll having a spiral wrap standing on a base plate; an orbiting scroll which is rotatably disposed opposite the fixed scroll and has a spiral wrap standing on an end plate, the orbiting scroll forming a plurality of compression chambers between the orbiting scroll and the spiral wrap of the fixed scroll; and an Oldham ring for preventing the orbiting scroll from rotating on its axis,
the orbiting scroll has a key groove formed on the back surface of the end plate and adapted to engage with a key of the Oldham ring;
the orbiting scroll has a spiral sliding surface that faces the tooth tips of the spiral wraps of the fixed scroll and is formed between the wraps of the orbiting scroll,
a spiral wrap extending from the outer periphery to the center of the fixed scroll has a protrusion at a tooth tip portion of the spiral wrap of the fixed scroll that corresponds to a portion where the key groove is provided. The scroll compressor according to any one of claims 1 to 4,
The convex portion is composed of a plurality of inclined surfaces with the center as a vertex, and the inclination of the inclined surface from the center toward the central portion is greater than the inclination of the inclined surface from the center toward the outer periphery. The scroll compressor according to claim 5,
A scroll compressor, characterized in that the center of the convex portion is located approximately on the center line of the key groove in the groove width direction. The scroll compressor according to claim 6,
a scroll compressor characterized in that two of the key grooves are provided at positions opposite to each other with respect to approximately the center of the end plate of the orbiting scroll, and the convex portions are provided on the spiral sliding surface or on the tooth tips of the spiral wrap corresponding to the positions of the two key grooves. The scroll compressor according to claim 7,
a projection is provided on the spiral sliding surface of a portion that serves as the reference point or on a tooth tip of the spiral wrap that corresponds to the reference point when an intersection of an imaginary line connecting the two keyways and the spiral sliding surface is used as a reference point, and the projection is configured such that the gradient of the slope from the reference point toward the central portion is greater than the gradient of the slope from the reference point toward the outer periphery. The scroll compressor according to claim 7,
a projection is provided on the spiral sliding surface of a portion serving as the reference point or on a tooth tip of the spiral wrap corresponding to the reference point when an intersection of an imaginary line connecting the two keyways and the spiral sliding surface is used as a reference point, and the projection is configured such that the length of a slope extending from the reference point toward the outer periphery is longer than the length of a slope extending from the reference point toward the central portion. The scroll compressor according to claim 7,
a scroll compressor, characterized in that, when an intersection of an imaginary line connecting the two keyways and the spiral sliding surface is used as a reference, the convex portion is provided on the spiral sliding surface of the reference portion or on a tooth tip of the spiral wrap corresponding to the reference, and the length of a slope of the convex portion from the reference toward the outer periphery and the length of a slope of the convex portion from the reference toward the central portion each have a wrap angle of 45 to 90 degrees. The scroll compressor according to claim 7,
a spiral sliding surface or a tooth tip of the spiral wrap formed along a reference slope from the outer periphery side to the central portion so that a gap between the spiral sliding surface and a tooth tip of the spiral wrap gradually increases from the outer periphery side to the central portion, except for a portion where the convex portion is provided, and an end portion of the convex portion facing the outer periphery side and an end portion facing the central portion are each on the reference slope. The scroll compressor according to claim 7,
a portion of the spiral sliding surface or the tooth tip of the spiral wrap located between two protrusions provided corresponding to the positions of the two keyways and perpendicular to an imaginary line connecting the two keyways, the portion of the spiral sliding surface or the tooth tip of the spiral wrap located between two protrusions provided corresponding to the positions of the two keyways, being on the reference slope so that a gap between the spiral sliding surface and the tooth tip of the spiral wrap gradually increases from the outer periphery toward the center, except for a portion where the protrusions are provided.