JP2024073734A - Scroll Compressor - Google Patents

Abstract

[Problem] Even if the head plate of the orbiting scroll is deformed by the pressure of compressed gas, the axial gap between the spiral wrap and the tooth bottom is appropriately maintained taking into consideration the deformation of the head plate due to the key groove. [Solution] A scroll compressor includes a fixed scroll having a spiral wrap standing on a base plate, an orbiting scroll having a spiral wrap standing on the head plate that forms a plurality of compression chambers between 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 wrap 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 head plate and engages with the key of the Oldham ring, and a convex portion is provided on the spiral sliding surface extending from the outer periphery side to the center side of the orbiting scroll, at a portion of the spiral sliding surface that corresponds to the portion where the key groove is provided. [Selected drawing] Fig. 8

Description

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

Scroll compressors used in refrigeration cycle devices such as heat pump water heaters, air conditioners, and freezers include those described in JP 7-197891 A (Patent Document 1). This Patent Document 1 describes a scroll-type fluid machine that includes a fixed scroll having a spiral wrap portion erected on an end plate, and an orbiting scroll that is rotatably arranged opposite the fixed scroll and has a spiral wrap portion erected thereon that forms multiple compression chambers between the wrap portion of the fixed scroll, and that the wrap portion of at least one of the orbiting scroll or the fixed scroll is formed so that the axial clearance between the bottom of the mating scroll changes in multiple stages.

Japanese Patent Application Laid-Open No. 7-197891

In the above-mentioned Patent Document 1, an axial gap is provided between the spiral wrap portion and its mating tooth bottom, which makes it possible to prevent friction and galling caused by thermal expansion of the wrap portion. In the above-mentioned Patent Document 1, the axial gap is formed so that it increases linearly toward the center of the wrap where thermal expansion is greater, and is configured with consideration given to the thermal expansion of the wrap. However, no consideration is given to the fact that the head plate of the orbiting scroll is deformed by the pressure of the compressed gas, which causes the axial gap to change.

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 caused by the key groove, even if the end plate of the orbiting scroll is deformed by the pressure of the compressed gas.

In order 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, a rotating scroll having a spiral wrap standing on a mirror plate that is rotatably arranged opposite the fixed scroll and forms a plurality of compression chambers between the spiral wrap of the fixed scroll, and an Oldham ring for preventing the rotating scroll from rotating on its axis, the rotating scroll having 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 rotating scroll, and a key groove formed on the back surface of the mirror plate that engages with the key of the Oldham ring, and a convex portion is provided on the spiral sliding surface that faces from the outer periphery side to the center side of the orbiting scroll, in the portion of the spiral sliding surface that corresponds to the portion where the key groove is provided.

Another feature of the present invention is a scroll compressor that includes a fixed scroll having a spiral wrap standing on a base plate, an orbiting scroll that is rotatably arranged opposite the fixed scroll and has a spiral wrap standing on a mirror 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 on its axis, the orbiting scroll has a key groove formed on the back surface of the mirror plate and engaging with a key of the Oldham ring, the fixed scroll has a spiral sliding surface that faces the tooth tip 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 that corresponds to the portion where the key groove is provided on the spiral sliding surface that faces from the outer periphery side to the center side of the fixed scroll.

Another feature of the present invention is a scroll compressor that includes a fixed scroll having a spiral wrap standing on a base plate, an orbiting scroll that is rotatably arranged opposite the fixed scroll and has a spiral wrap standing on a mirror 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 on its axis, the orbiting scroll has a key groove formed on the back surface of the mirror plate and engages with the 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 tooth tips of the spiral wrap of the orbiting scroll that corresponds to the portion where the key groove is provided in the spiral wrap extending from the outer periphery side to the center side of the orbiting scroll.

Another feature of the present invention is a scroll compressor that includes a fixed scroll having a spiral wrap standing on a base plate, an orbiting scroll that is rotatably arranged opposite the fixed scroll and has a spiral wrap standing on a mirror 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 on its axis, the orbiting scroll has a key groove formed on the back surface of the mirror plate and engages with the 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 a convex portion is provided on the tooth tips of the spiral wrap of the fixed scroll that corresponds to the portion where the key groove is provided in the spiral wrap extending from the outer periphery side to the center side of the fixed scroll.

The present invention has the effect 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 head plate caused by the key groove, even if the head plate of the orbiting scroll is deformed by the pressure of the compressed gas.

1 is a vertical 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; 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. 4 is a development view showing a schematic diagram of a tooth tip shape of a fixed scroll and a tooth bottom shape of a rotating scroll. FIG. 4 is a schematic diagram illustrating a pressure distribution acting on the orbiting scroll. FIG. 4 is a perspective view illustrating a deformation state of an 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 showing a tooth tip shape of a fixed scroll and a tooth bottom shape of a rotating 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. 11 is a development view for explaining a first modified example of the present invention, which diagrammatically illustrates the tooth bottom shape of the fixed scroll and the tooth tip shape of the orbiting scroll. FIG. 11 is a diagram for explaining a second modified example of the present invention, and corresponds to FIG. 10 . FIG. 10 is a diagram for explaining a third modified example of the present invention, and corresponds to FIG. 8 .

Specific examples 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 the first embodiment will be described with reference to Figures 1 and 2.
Fig. 1 is a vertical cross-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, etc. in a sealed container (case) 2.

In the compression mechanism 3, a fixed scroll 7 fixed to a frame 5 is meshed with a rotating scroll 8 to form a compression chamber 13, and the rotation of the motor 4 causes the rotating 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 a result of this compression operation, the working fluid is sucked into the suction chamber 20 (see also Figure 2) from the suction port 14, and the sucked working fluid undergoes a compression stroke in the compression chamber 13 before being discharged from the discharge port 15 into the first discharge space 16a that constitutes the discharge space 16. The working fluid then passes through the second discharge space 16b, which is the discharge space 16 at the top of the sealed container 2 and is connected to the first discharge space 16a, and is discharged from the discharge pipe 6 to the outside of the sealed container 2.

The fixed scroll 7 comprises a disk-shaped base plate 7a, a spiral wrap (hereinafter referred to as a fixed wrap or simply a wrap) 7b erected on the base plate 7a, a tooth bottom (spiral sliding surface) 7c which is the surface of the base plate 7a between the wraps 7b, and a support part 7d located on the outer periphery of the base plate 7a and provided in a cylindrical shape to surround the wrap 7b. A mirror plate surface 7e is formed on the support part 7d, and the height of the mirror plate surface 7e is configured to be approximately the same as the height of the tooth tip 7f which is the tip surface of the wrap 7b. The mirror plate surface 7e is also the sliding surface where the support part 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 by 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 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 wrap) are engaged with each other, and are provided so as to be capable of orbiting within the frame 5. The orbiting scroll 8 has the spiral wrap 8b erected from the tooth bottom (spiral sliding surface) 8c, which is the surface of a disk-shaped mirror plate 8a, and a rotating boss portion 8d provided in the center of the back surface of the mirror plate 8a. In addition, the surface of the outer periphery of the mirror plate 8a that comes into contact with the fixed scroll 7 is the mirror 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.

The bottom of the sealed container 2, which houses the compression mechanism 3 and the motor 4, etc., is provided with an oil reservoir 25 for storing lubricating oil (hereinafter also referred to as refrigeration oil or oil). 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.

The tip of the crankshaft 10 is provided with an eccentric crank portion 10a, which is inserted into a rotating bearing 8g provided in the rotating boss portion 8d of the rotating scroll 8, so that the rotating scroll 8 can rotate as the crankshaft 10 rotates.

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

12 is an Oldham ring for orbiting the orbiting scroll 8 relative to the fixed scroll 7 while restraining it from rotating on its axis. The Oldham ring 12 has two keys (protruding parts) arranged diagonally on the upper surface of the annular ring, and two keys arranged on the lower surface, shifted by 90 degrees from the keys on the upper surface. The keys on the upper surface are slidably engaged with key grooves 8h provided on the orbiting scroll 8, and the keys on the lower surface are slidably engaged with key grooves 5b provided on the frame 5.

Figure 2 is a cross-sectional view taken along the line II-II in Figure 1, showing the state in which the fixed scroll 7 and the orbiting scroll 8 shown in Figure 1 are engaged. 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 FIG. 2, multiple crescent-shaped compression chambers 13 (inner line compression chamber 13a, outer line compression chamber 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 is continuously reduced as it moves toward the center, and compression is performed. The inner line compression chamber 13a is a compression chamber formed inside the orbiting wrap 8b, and the outer line 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 the 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 trapping of the fluid is completed.

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

When the crankshaft 10 is rotated by the motor unit 4 shown in FIG. 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 sucked in from the suction port 14, for example, the refrigerant gas circulating in the refrigeration cycle, is compressed sequentially in each compression chamber 13, and the compressed working fluid is discharged from the discharge port 15 to the first discharge space 16a, then flows into the second discharge space 16b and is supplied from the discharge pipe 6 to an outside of the compressor, for example, to the refrigeration cycle.

Oil is supplied to each sliding part such as the main bearing 5a and the slewing bearing 8g by a differential pressure oil supply structure. That is, the inside 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 is a structure that pumps up the oil under high pressure in the oil reservoir 25 by utilizing the pressure difference with the pressure in the back pressure chamber (pressure between the discharge pressure and the suction pressure). Therefore, the lubricating oil in the oil reservoir 25 is sucked in through the lubricating oil suction port 10c provided at the bottom of the crankshaft 10 by the pressure difference, and is sent to the top of the crankshaft 10 through the through hole (oil supply hole) 10b formed in the axial direction 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. The oil that lubricates the auxiliary bearing 23 is then returned to the oil reservoir 25 at the bottom of the sealed container 2. The remaining majority of the lubricating oil that flows through the through hole 10b flows into the main bearing 5a via a horizontal hole 10e provided 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 flow is then throttled as it passes through the tiny gaps between the main bearing 5a and the slewing bearing 8g, reducing its pressure and expanding, before flowing into the back pressure chamber 18.

The lubricating oil that flows into the back pressure chamber 18 is configured to flow into the suction chamber 20 and the compression chamber 13, lubricating the wrap sliding surface and wrap tip gap of the spiral wraps 7b and 8b, and is also used for sealing between the compression chambers 13. The lubricating oil is then discharged from the discharge port 15 together with the refrigerant gas into the first discharge space 16a. At that time, the lubricating oil and the refrigerant gas collide with the discharge cover 26 that forms the first discharge space 16a, and while the oil and the refrigerant gas are separated, they change the flow direction sideways and flow 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., and the lubricating oil passes through a passage (not shown) formed on the outer periphery of the fixed scroll 7 and the outer periphery of the frame 5, and returns to the oil sump 25 at the bottom of the compressor via the motor chamber 27.

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

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 mirror plate 8a of the orbiting scroll 8, and the pressure (back pressure) of this back pressure chamber 18 cancels the separating force and presses the orbiting scroll 8 against the fixed scroll 7. If the pressing force at this time is too large, the sliding loss between the mirror plate surface 8e of the orbiting scroll 8 and the mirror plate surface 7e of the fixed scroll 7 increases, and the efficiency of the scroll compressor 1 decreases.

That is, there is an optimal value for the back pressure; if it is too low, the sealing of the compression chamber deteriorates and thermal fluid loss increases, while if it is too high, friction loss increases. 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 for adjusting the back pressure in the back pressure chamber 18 in the support portion 7d of the fixed scroll 7, as shown in FIG. 1.

Next, the configuration of the back pressure valve 31 and its surroundings will be described with reference to Fig. 3. Fig. 3 is an enlarged partial cross-sectional view showing the back pressure valve 31 and its surroundings 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 communicates the back pressure chamber 18 with the back pressure valve 31, a back pressure valve outlet passage (space communicating with the compression chamber 13) 32c that communicates the back pressure valve 31 with the compression chamber 13, and a space 32b that accommodates 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 provided 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 of the back pressure chamber 18) becomes higher than the load due to the sum of the pressure in the space 32b (i.e., the pressure of the compression chamber) introduced through 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 to the back pressure valve outlet passage 32c. In other words, when the pressure in the back pressure chamber 18 becomes higher than a certain value, the back pressure valve 31 releases the fluid in the back pressure chamber 18 to the compression chamber 13 side, and adjusts the pressure (back pressure) of the back pressure chamber 18 to an appropriate value.

The basic configuration of the scroll compressor 1 has been described 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 is 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 the axial gap is too small, the sliding loss at the wrap tip (tooth tips 7f, 8f) increases, or the wrap tip comes into contact with the tooth bottom (spiral sliding surface) 7c, 8c, causing wear and galling, and reducing reliability. Also, if the axial gap is too large, the sealing of the compression chamber 13 decreases, increasing leakage, and increasing thermal fluid loss, reducing the efficiency of the scroll compressor 1. Therefore, just as it is important to adjust the pressure (back pressure) of the back pressure chamber 18 to an appropriate value, maintaining the axial gap at an optimal value is important for improving the performance and reliability of the scroll compressor 1.

The scroll compressor 1 draws in refrigerant gas from the suction port 14 shown in FIG. 2, compresses it sequentially in the crescent-shaped compression chamber 13, and discharges the compressed refrigerant gas from the discharge port 15. The temperature of the refrigerant gas increases as it is compressed. Therefore, the temperature of the fixed wrap 7b and the orbiting wrap 8b is higher in the center near the discharge port 15 than in the outer periphery near the suction port 14. For this reason, the thermal expansion is larger on the wrap center side where the temperature is higher than on the outer periphery side, and the wrap height increases due to the thermal expansion. For example, if the wrap height on the wrap center side of the fixed wrap 7b becomes higher, the axial gap between the tooth bottom 8c of the opposing orbiting scroll 8 disappears, and reliability decreases due to increased sliding loss and wear and galling caused by contact. The same is true for the wrap tooth tip of the orbiting wrap 8b and the tooth bottom 7c of the opposing fixed scroll 7.

To solve this problem, as shown in FIG. 4, it has been considered to make the tooth bottom (spiral sliding surface) 8c of the orbiting scroll 8 into a slope shape that monotonically deepens from the wrap outer periphery side toward the wrap center side, 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 FIG. 4 is a development diagram that shows a schematic bottom shape (tooth bottom excavation shape) in the orbiting scroll, and is a comparative example to this embodiment 1, and shows 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 side of the orbiting wrap 8b, and the right side indicates the center side 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.

Although the tooth bottom shape of the orbiting scroll 8 has been described here, the axial gap 40 can also be formed by digging the tooth bottom (spiral sliding surface) 7c of the fixed scroll 7 into a slope shape that monotonically deepens from the wrap outer periphery toward the wrap center. Also, the axial gap 40 can be formed by providing the slope shape on the tooth tip 7f or 8f side of the spiral wrap 7b or 8b, rather than the wrap tooth bottom 7c or 8c.

As explained in FIG. 4, if only the thermal expansion of the wrap is considered, for example, by forming the tooth bottom (spiral sliding surface) 8c of the orbiting scroll 8 in a slope shape in which the depth increases monotonically from the wrap outer periphery toward the wrap center, 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 head plate 8a is also deformed by the pressure acting on the orbiting scroll 8. Therefore, if the tooth bottom is simply carved into a monotonous slope shape, the acting pressure will locally reduce the axial clearance, increasing sliding loss, or expand the axial clearance, increasing thermal fluid loss.

Here, the pressure acting on the orbiting scroll 8 will be described with reference to Fig. 5 and Fig. 6. Fig. 5 is a schematic diagram for explaining the pressure distribution acting on the orbiting scroll 8, and Fig. 6 is a perspective view for explaining the deformation state of the end plate 8a of the orbiting scroll 8.
As shown in FIG. 5, the orbiting scroll 8 is subjected to a discharge pressure Pd in the region inside the orbiting bearing 8g on the back side, and a back pressure (pressure between the discharge pressure and the suction pressure) Pb is applied to the region outside the orbiting bearing 8g because it is the back pressure chamber 18. The resultant force of these pressures becomes the pushing force of the orbiting scroll 8. The outermost periphery of the end plate 8a on the upper surface side of the orbiting scroll 8 faces the back pressure chamber 18, so the back pressure Pb is applied, and as it moves from there to the suction chamber 20 or the compression chamber 13 (see FIG. 1 and FIG. 2) located slightly on the inner periphery side, the pressure once drops to the suction pressure Ps or the pressure inside the compression chamber 13 in the middle of compression. The compression chamber 13 further becomes compressed on the inner periphery side, so the pressure rises, and at the center where the discharge port 15 is located, it becomes the discharge pressure Pd. The resultant force of these pressures becomes the pushing force of the orbiting scroll 8. The force obtained by subtracting the pushing force from the pushing force becomes the pushing force that pushes 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 the suction pressure Ps acts on the upper surface and the back pressure Pb acts on the back surface, the load acts from bottom to top, so as shown in Figure 6, the outer periphery of the wrap 8b is bent upward and the center of the wrap 8b is bent downward into a concave shape. If this is the only deformation, as explained using Figure 4, it is sufficient to make the tooth bottom 8c etc. monotonously deeper as it approaches the center of the wrap 8b, like the tooth bottom shape that corresponds to thermal expansion.

However, generally, a key groove (countersunk slot) 8h for attaching the key portion (protrusion) of the Oldham ring 12 is provided on the back surface of the orbiting scroll 8 as shown in FIG. 7, but no consideration is given to the deformation of the orbiting scroll 8 caused by this key groove 8h.

Next, the configuration of the scroll compressor according to the first embodiment of the present invention will be described with reference to 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 shows a schematic of the tooth tip shape of the fixed scroll and the tooth bottom shape (tooth bottom recessed shape) of the orbiting scroll in the scroll compressor according to the first embodiment of the present invention, and Figure 9 is a plan view that illustrates the range in which the convex portion on the orbiting scroll is formed.

As described above, to prevent deformation due to thermal expansion of the orbiting scroll 8 or the application of pressure as described in Figures 5 and 6, the tooth bottom 8c may be monotonously dug deeper toward the center of the wrap 8b, forming a slope shape, as described in 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.

That is, the area where the key groove 8h is provided has a low rigidity because the plate thickness of the end plate 8a is thin. As explained with reference to 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, in the area of low rigidity where the key groove 8h is provided, the end plate 8a 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 mirror plate 8a of the orbiting scroll 8 is bent, the tooth tip of the orbiting wrap 8b moves away from the tooth bottom 7c of the fixed scroll 7 at the bent portion (near the imaginary line 41), and the tooth tip of the fixed wrap 7b moves away from the tooth bottom 8c of the orbiting scroll 8. Therefore, the axial gap 40 becomes wider at the tooth tip 8f and tooth bottom 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 key groove 8h is provided is locally made shallow, giving the tooth bottom a padded shape.

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

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

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

The key grooves 8h are provided in two positions on opposite sides of the mirror plate 8a of the orbiting scroll 8, so that the protrusions 50 are provided in the tooth bottom (spiral sliding surface) 8c (or the tooth tip of the spiral wrap) corresponding to the positions of the two key grooves 8h. That is, when the intersection of the virtual line 41 connecting the two key grooves 8h and the tooth bottom (spiral sliding surface) 8c is taken as a reference, the protrusions 50 are provided in the tooth bottom (spiral sliding surface) 8c (or the tooth tip 8f of the spiral wrap 8b corresponding to the reference), and the protrusions 50 are configured so that the gradient of the inclination from the reference toward the center is greater than the gradient of the inclination from the reference toward the outer periphery. The reference corresponds to the bending position 42 described above.

Figure 9 shows the formation range of the convex portion 50 provided on the tooth bottom 8c of the orbiting scroll 8. As shown in this figure, the convex portion 50 is formed at the positions of the regions 51a, 51b, 51c, and 51d on the tooth bottom (spiral sliding surface) 8c. Here, the regions 51a, 51b, 51c, and 51d correspond to the inclined surfaces 50a, 50b, 50c, and 50d, respectively. That is, when the orbiting scroll 8 is viewed from above, in this embodiment, the convex portion 50 is formed in the range of the regions 51a, 51b, 51c, and 51d shown in Figure 9. In addition, of the two convex portions 50 provided corresponding to the two key grooves 8h, the convex portion on the outer periphery side is provided in the range shown in the regions 51a and 51b, and the convex portion on the central side is provided in the range shown in the regions 51c and 51d, and the vertices of the two convex portions 50 are formed to be the bending positions 42.

Note that the formation range of the convex portion 50 shown in FIG. 9 is one example, and in this embodiment, all of the regions 51a to 51d are formed within a range of 90 degrees from the bending position 42. Therefore, the length of the slope 50a of the region 51a located closest to the outer periphery is the longest, and the length of the slope of the region 51d 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, and may be, for example, 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 so that the axial gap 40 at the position 42 where the end plate 8a bends the most is small. In other words, if the intersection point between the virtual line 41 connecting the two key grooves 8h and the tooth bottom (spiral sliding surface) 8c is taken as the reference (corresponding to the bending position 42), the apex of the convex portion 50 is provided at the tooth bottom 8c (or the tooth tip of the spiral wrap corresponding to the reference), and the length of the slopes 50a, 50c from the reference toward the outer periphery and the length of the slopes 50b, 50d toward the center should each be in the range of 45 to 90 degrees in terms of wrap angle.

In addition, except for the portion where the protrusion 50 is provided, 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 side to the central portion so that the axial gap 40 between the tooth bottom (spiral sliding surface) 8c and the tooth tip 7f of the spiral wrap 7b gradually increases from the outer periphery side toward the central portion, taking thermal expansion into account. In this way, the axial gap can be determined with thermal expansion taken into account.

It is preferable that the end of the protrusion 50 toward the outer periphery and the end toward 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 protrusions 50 provided corresponding to the positions of the two key grooves 8h and perpendicular to the imaginary line 41 connecting the two key grooves 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 head plate 8a due to the key groove 8h, further reducing thermal fluid loss and improving the efficiency of the compressor.

Note that FIG. 8 describes the case where the convex portion 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 obtained by providing the convex portion 50 on the tooth bottom 7c of the fixed scroll 7 to optimize the axial gap 40. Also, the same effect can be obtained by providing the convex portion 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, using FIG. 10 to FIG. 12, a specific description will be given of a modified example of the present invention in which the position at which the convex portion 50 is provided is changed.

(Variation 1)
Fig. 10 is a view for explaining the first embodiment of the present invention, and is a development view showing a typical example 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 become gradually deeper in a slope shape from the outer periphery side toward the center side in consideration of thermal expansion, and a protrusion 50 is provided near a position 42 of the tooth bottom 7c of the fixed scroll 7. The other configurations are the same as those of the first embodiment.

Even with this configuration, the axial clearance 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. In other words, 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, thereby reducing thermal fluid loss and improving the efficiency of the compressor.

As in the first embodiment shown in FIG. 8, the convex portion 50 may also be provided on the tooth bottom 8c of the orbiting scroll 8, or the tooth bottom 8c of the orbiting scroll 8 may not be provided with a convex portion, and the tooth bottom 8c may not be formed in a slope shape.

(Variation 2)
Fig. 11 is a diagram for explaining a second modified example of the present invention, and corresponds to Fig. 10. In the example shown in Fig. 11, the tooth tip 8f of the orbiting scroll 8 is configured to be gradually lowered in a slope shape from the outer periphery side toward the center side in consideration of thermal expansion, and a convex portion 50 is provided near a position 42 of the tooth tip 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 obtaining the same effect as in Example 1.

In addition, the convex portion 50 may be provided on the tooth tip 7f of the fixed scroll 7, similar to the shape of the tooth tip 8f of the orbiting scroll 8, or the tooth tip 7f of the fixed scroll 7 may not be provided with a convex portion and the tooth tip 7f may not be formed into a slope shape. Also, as in Example 1 and Modification 1 shown in Figures 8 and 10, the convex portion 50 may 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 for explaining a third modified example of the present invention, and corresponds to Fig. 8. In the example shown in Fig. 12, the tooth tip 7f of the fixed scroll 7 is configured to gradually become lower in a slope shape from the outer periphery side toward the center side in consideration of thermal expansion, and a protrusion 50 is provided near a position 42 of the tooth tip 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 obtaining the same effect as in Example 1.

In addition, the convex portion 50 may be provided on the tooth tip 8f of the orbiting scroll 8 in the same manner as the shape of the tooth tip 7f of the fixed scroll 7, 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 formed into a slope shape. Also, as in Example 1 and Modification Example 1 shown in Figures 8 and 10, the convex portion 50 may be provided on the tooth bottom 8c of the orbiting scroll 8 or the tooth bottom 7c of the fixed scroll 7.

As described 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 bottom or tooth tip of the orbiting scroll corresponding to the key groove of the orbiting scroll and the tooth bottom or tooth tip of the fixed scroll, so that 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 properly 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 key groove. Therefore, friction and galling between the tip (tooth tip) of the wrap of the fixed scroll or orbiting scroll and the tooth bottom can be suppressed, and leakage loss at the tip of the wrap can be reduced, further improving the efficiency of the scroll compressor, so that a highly efficient scroll compressor can be obtained.

The present invention is not limited to the above-mentioned embodiment or modification, but includes various modifications. Furthermore, the above-mentioned embodiment or modification has been described in detail to explain the present invention in an easy-to-understand manner, and is not necessarily limited to those having all of the configurations described.

1: scroll compressor, 2: sealed container (case), 3: compression mechanism,
4: motor section, 4a: rotor, 4b: stator,
5: frame, 5a: main bearing, 5b: key groove,
6: discharge pipe,
7: fixed scroll, 7a: base plate, 7b: spiral wrap (fixed wrap, wrap),
7c: tooth bottom (spiral sliding surface), 7d: support portion, 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: mirror plate surface,
8f: tooth tip, 8g: swivel bearing, 8h: key groove,
10: crankshaft (rotating shaft), 10a: crank portion, 10b: through hole (oil supply hole),
10c: lubricating oil suction port, 10d, 10e: side 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 inlet passage, 32b: space, 32c: back pressure valve outlet passage,
33: Stopcock,
40: Axial clearance, 41: Virtual line (dotted line) (connecting keyways),
42: bending position,
50: protruding portion (pillar 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; a rotating scroll which is rotatably disposed opposite to the fixed scroll and has a spiral wrap standing on an end plate, the spiral wrap forming a plurality of compression chambers between the fixed scroll and the spiral wrap; and an Oldham ring for preventing the rotating scroll from rotating on its axis,
the orbiting scroll has a spiral sliding surface that faces a tooth tip of a spiral wrap of the fixed scroll and is formed between the spiral wraps of the orbiting scroll, and a key groove that is formed on a back surface of the end plate and engages with a key of the Oldham ring,
a convex portion is provided on a portion of the spiral sliding surface extending from an outer periphery side toward a center side of the orbiting scroll, the portion 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; a rotating scroll which is rotatably disposed opposite to the fixed scroll and has a spiral wrap standing on a head plate, the spiral wrap forming a plurality of compression chambers between the fixed scroll and the spiral wrap; and an Oldham ring for preventing the rotating 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 a tooth tip of the spiral wrap of the orbiting scroll and is formed between the spiral wraps of the fixed scroll,
a convex portion is provided on a portion of the spiral sliding surface of the fixed scroll that corresponds to a portion where the key groove is provided, in the spiral sliding surface extending from the outer periphery side toward the center side of the fixed scroll. A scroll compressor comprising: a fixed scroll having a spiral wrap standing on a base plate; a rotating scroll which is rotatably disposed opposite to the fixed scroll and has a spiral wrap standing on a head plate, the spiral wrap forming a plurality of compression chambers between the fixed scroll and the spiral wrap; and an Oldham ring for preventing the rotating 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 a tooth tip of the spiral wrap of the orbiting scroll and is formed between the spiral wraps of the fixed scroll,
a spiral wrap extending from the outer periphery side to the center side of the orbiting scroll has a protrusion at a portion of the tooth tip 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; a rotating scroll which is rotatably disposed opposite to the fixed scroll and has a spiral wrap standing on a head plate, the spiral wrap forming a plurality of compression chambers between the fixed scroll and the spiral wrap; and an Oldham ring for preventing the rotating 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 a tooth tip of a spiral wrap of the fixed scroll and is formed between wraps of the orbiting scroll,
a spiral wrap extending from an outer periphery side to a central portion of the fixed scroll, the spiral wrap having a protrusion at a portion of a tooth tip of the spiral wrap of the fixed scroll corresponding 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 having a vertex at its center, and the gradient of the inclined surface extending from the center toward the central portion is greater than the gradient of the inclined surface extending from the center toward the outer periphery. The scroll compressor according to claim 5,
A scroll compressor, characterized in that a center of the convex portion is located approximately on a center line of the key groove in a groove width direction. The scroll compressor according to claim 6,
a scroll compressor comprising: a rotating scroll having a rotating scroll end plate and a spiral wrap having a spiral lapped end plate, the spiral wrap being provided with a spiral lapped end plate and a spiral wrap having a spiral lapped end plate and a spiral wrap having a spiral lapped end plate and a spiral wrap having a spiral wrap plate, the spiral lapped end plate and a spiral wrap plate having a spiral wrap plate and ... The scroll compressor according to claim 7,
a protrusion 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, and the protrusion is configured so 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 portion. The scroll compressor according to claim 7,
a protrusion 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, the protrusion being configured such that a length of a slope extending from the reference point toward an outer periphery side is longer than a length of a slope extending from the reference point toward a central portion side. The scroll compressor according to claim 7,
a protrusion is provided on the spiral sliding surface of a portion serving as a reference point, or on a tooth tip of the spiral wrap corresponding to the reference point, and the protrusion has a length of a slope from the reference point toward an outer periphery side and a length of a slope from the reference point toward a central portion side, each of which has a winding 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 is formed along a reference slope from the outer periphery side to the central portion such 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 toward the outer periphery side and an end portion of the convex portion toward the central portion are each on the reference slope. The scroll compressor according to claim 7,
a spiral sliding surface or a tooth tip of the spiral wrap is 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 a portion of the spiral sliding surface or the tooth tip of the spiral wrap that is between two convex portions provided corresponding to the positions of the two key grooves, respectively, and that is perpendicular to a virtual line connecting the two key grooves, is on the reference slope.

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