Scroll Compressor

Abstract

To properly keep an axial clearance between a spiral lap and a tooth bottom while considering deformation of an end plate of a turning scroll by a key groove, even when the end plate is deformed by pressure of a compression gas.SOLUTION: A scroll compressor includes: a fixed scroll in which a spiral lap is vertically disposed on a base plate; a turning scroll in which a spiral lap forming a plurality of compression chambers with respect to the spiral lap of the fixed scroll, is vertically disposed on the end plate; and an Oldham's ring for preventing rotation of the turning scroll. The turning scroll includes: a spiral sliding face opposed to a tooth tip of the spiral lap of the fixed scroll and formed with respect to the spiral lap of the turning scroll; and a key groove formed on a back face of the end plate and engaged with the Oldham's ring. On the spiral sliding face facing a central side from an outer peripheral side of the turning scroll, a part of the spiral sliding face corresponding to the part provided with the key groove, has a convex portion.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to a scroll compressor used in refrigeration cycle devices such as heat pump water heaters, air conditioners, and refrigerators. [Background technology]

[0002] An example of a scroll compressor used in refrigeration cycle devices such as heat pump water heaters, air conditioners, and refrigerators is described in Japanese Patent Laid-Open Publication No. 7-197891 (Patent Document 1). 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 disposed opposite the fixed scroll and also has a spiral wrap portion erected thereon, forming multiple compression chambers between the wrap portion of the fixed scroll and the orbiting 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 wrap portion and the tooth bottom of the other scroll changes in multiple stages. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 7-197891 Summary of the Invention [Problem to be solved by the invention]

[0004] In the design of 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 design of Patent Document 1, the axial gap is formed to linearly increase toward the center of the wrap, where thermal expansion is greater, and is designed to take thermal expansion of the wrap into consideration. However, no consideration is given to the possibility that the pressure of the compressed gas will deform the end plate of the orbiting scroll, resulting in a change in the axial gap.

[0005] An object of the present invention is to provide a scroll compressor that can maintain an appropriate axial gap between a spiral wrap and its mating tooth bottom, taking into account deformation of the end plate due to the key groove, even if the end plate of the orbiting scroll is deformed by the pressure of compressed gas. [Means for solving the problem]

[0006] 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; an orbiting scroll which is rotatably disposed opposite the fixed scroll and has a spiral wrap standing on an end plate which forms a plurality of compression chambers between itself and 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 spiral sliding surface which 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 which is formed on the back surface of the end plate and engages with a key of the Oldham ring, and the spiral sliding surface extending from the outer periphery to the center of the orbiting scroll has a convex portion formed in a portion of the spiral sliding surface which corresponds to the portion where the keyway is provided.

[0007] 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 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 itself and 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 for engaging with a key of the Oldham ring, the fixed scroll has a spiral sliding surface which faces the 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 extending from the outer periphery toward the center of the fixed scroll at a portion of the spiral sliding surface of the fixed scroll which corresponds to the portion where the keyway is provided.

[0008] Yet 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 which is rotatably disposed opposite the fixed scroll and has a spiral wrap standing on an end plate, the orbiting scroll having a spiral wrap standing on an end plate and forming a plurality of 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 for engaging with a key of the Oldham ring, the fixed scroll has a spiral sliding surface which 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 convex portion at the tooth tips of the spiral wrap of the orbiting scroll which corresponds to the portion where the keyway is formed.

[0009] Yet 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 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 itself and 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 for engaging with a key of the Oldham ring, the orbiting scroll has a spiral sliding surface which 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 convex portion at the tooth tips of the spiral wrap of the fixed scroll which corresponds to the portion where the keyway is formed. [Effects of the Invention]

[0010] According to the present invention, it is possible to obtain a scroll compressor that can appropriately maintain the axial gap between the spiral wrap and its mating tooth bottom, taking into account the deformation of the end plate due to the key groove, even if the end plate of the orbiting scroll is deformed by the pressure of the compressed gas. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a longitudinal sectional view showing a first embodiment of a scroll compressor according to the present invention. [Figure 2] 2 is a cross-sectional view taken along the line II-II in FIG. 1, illustrating a state in which the fixed scroll and the orbiting scroll shown in FIG. 1 are engaged with each other. [Figure 3] 2 is an enlarged partial cross-sectional view showing the periphery of a back pressure valve in the scroll compressor shown in FIG. 1. [Figure 4] 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. [Figure 5] FIG. 4 is a schematic diagram illustrating the pressure distribution acting on the orbiting scroll. [Figure 6] FIG. 4 is a perspective view illustrating a deformation state of the end plate of the orbiting scroll. [Figure 7] FIG. 4 is a rear perspective view illustrating the shape of the rear surface of the orbiting scroll. [Figure 8] 1 is a development view schematically showing the tooth tip shape of a fixed scroll and the tooth bottom shape of an orbiting scroll in a scroll compressor according to a first embodiment of the present invention. FIG. [Figure 9] FIG. 4 is a plan view illustrating a range in which a convex portion is formed on the orbiting scroll. [Figure 10] FIG. 10 is a development view for explaining Modification 1 of the present invention, which is a schematic illustration of the tooth bottom shape of the fixed scroll and the tooth tip shape of the orbiting scroll. [Figure 11] FIG. 11 is a diagram for explaining a second modified example of the present invention, and corresponds to FIG. 10. [Figure 12] FIG. 10 is a diagram illustrating a third modified example of the present invention, and corresponds to FIG. 8. DETAILED DESCRIPTION OF THE INVENTION

[0012] Specific embodiments of the scroll compressor of the present invention will be described below with reference to the drawings. In each drawing, the same reference numerals denote the same or corresponding parts. [Example]

[0013] A first embodiment of the scroll compressor of the present invention will be described with reference to Figures 1 to 8. First, the overall configuration of the scroll compressor of 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.

[0014] In the compression mechanism section 3, a rotating scroll 8 is engaged with a fixed scroll 7 fixed to a frame 5 to form a compression chamber 13, and by rotating the motor section 4, the rotating scroll 8 is caused to orbit via a crankshaft (rotating shaft) 10, thereby reducing the volume of the compression chamber 13 and performing a compression operation.

[0015] As a result of this compression operation, the working fluid is sucked from the suction port 14 into the suction chamber 20 (see also FIG. 2), 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 communicates with the first discharge space 16a, and is then discharged from the discharge pipe 6 to the outside of the sealed container 2.

[0016] The fixed scroll 7 includes a disk-shaped base plate 7a, spiral wraps (hereinafter referred to as fixed wraps or simply wraps) 7b extending from the base plate 7a, tooth roots (spiral sliding surfaces) 7c that are the surfaces 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. An end plate surface 7e is formed on the support portion 7d, and the height of the end plate surface 7e is configured to be approximately the same as the height of the tooth tips 7f that are the leading ends of the wraps 7b. The end plate surface 7e is the sliding surface where the support portion 7d of the fixed scroll 7 comes into contact with the end plate 8a of the orbiting scroll 8.

[0017] The support portion 7d of the fixed scroll 7 is fixed to the frame 5 by bolts or the like, and the frame 5 integrally joined to the fixed scroll 7 is fixed to the sealed container 2 by a fixing means such as welding.

[0018] The orbiting scroll 8 is disposed opposite the fixed scroll 7, and is rotatably mounted within the frame 5 with a spiral wrap 7b of the fixed scroll 7 and a spiral wrap 8b of the orbiting scroll 8 (hereinafter referred to as an orbiting wrap or simply a wrap) meshed together. The orbiting scroll 8 has the spiral wrap 8b standing upright from a tooth bottom (spiral sliding surface) 8c, which is the surface of a disk-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 is an end plate surface 8e of the orbiting scroll 8.

[0019] 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 therebetween. 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 therebetween.

[0020] 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 accommodating 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.

[0021] An eccentric crank portion 10a is provided at the tip of the crankshaft 10, and this crank portion 10a is inserted into a rotary bearing 8g provided on the rotary boss portion 8d of the rotary scroll 8, so that the rotary scroll 8 is configured to be able to rotate as the crankshaft 10 rotates.

[0022] 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. The wrap 8b of the orbiting scroll 8 is overlapped with the wrap 7b of the fixed scroll 7 at a circumferential offset of a predetermined angle (generally 180 degrees).

[0023] An Oldham ring 12 is used to orbit 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 (protrusions) arranged diagonally on the upper surface of the annular ring, and two keys arranged on the lower surface, offset by 90 degrees from the keys on the upper surface. The keys on the upper surface slidably engage with a key groove 8h provided in the orbiting scroll 8, and the keys on the lower surface slidably engage with a key groove 5b provided in the frame 5.

[0024] Figure 2 is a diagram showing a state in which the fixed scroll 7 and the orbiting scroll 8 shown in Figure 1 are engaged with each other, and is a cross-sectional view taken along the line II-II in Figure 1. 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).

[0025] 2, multiple crescent-shaped compression chambers 13 (inner orbiting line compression chambers 13a, outer orbiting line compression chambers 13b) are formed between the fixed wrap 7b and the orbiting wrap 8b, and when the orbiting scroll 8 is orbited, the volume of each compression chamber 13 is continuously reduced as it moves toward the center, thereby performing a compression operation. The inner orbiting line compression chamber 13a is a compression chamber formed inside the orbiting wrap 8b, and the outer orbiting line compression chamber 13b is a compression chamber formed outside the orbiting wrap 8b.

[0026] Reference numeral 20 denotes a suction chamber, which is a space in the middle of sucking in a fluid. This suction chamber 20 becomes a compression chamber 13 when the phase of the orbiting motion of the orbiting scroll 8 advances and the confinement of the fluid is completed.

[0027] 1 and 2, the suction port 14 is provided in the fixed scroll 7. The suction port 14 is drilled 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 bored near the center of the scroll of the base plate 7a of the fixed scroll 7 so as to communicate with the compression chamber 13 on the innermost periphery side.

[0028] 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 through the suction port 14, such as a refrigerant gas circulating in a 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 external device, such as a refrigeration cycle.

[0029] 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 sump 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 oil under high pressure in the oil sump 25 by utilizing the pressure difference with 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 sump 25 is sucked through the lubricating oil suction port 10c provided at the bottom of the crankshaft 10 and sent to the top of the crankshaft 10 through a through-hole (oil supply hole) 10b formed in the axial direction in the crankshaft 10.

[0030] As the lubricating oil flows through the through hole 10b, a portion of it is supplied to the sub-bearing 23, which supports the lower part of the crankshaft 10, via a horizontal hole 10d formed in the crankshaft 10. The oil that has lubricated the sub-bearing 23 is then returned to an 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 formed in the crankshaft 10, and also flows into the orbiting bearing 8g through an upper space 24 of the crankshaft 10, lubricating these sliding parts. Thereafter, the flow of the oil is throttled as it passes through the minute gaps between the main bearing 5a and the orbiting bearing 8g, and the oil is decompressed and expanded before flowing into the back pressure chamber 18.

[0031] The lubricating oil that flows into the back pressure chamber 18 flows into the suction chamber 20 and the compression chamber 13. It lubricates 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 the refrigerant gas collide with the discharge cover 26 that defines the first discharge space 16a, where they separate and change direction before flowing 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. The lubricating oil then flows through 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 back to the oil sump 25 at the bottom of the compressor.

[0032] Next, the function of the back pressure chamber 18 will be described. In the scroll compressor 1, the compression action generates an axial force (separating 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 so-called separation phenomenon of the orbiting scroll 8 occurs, which deteriorates the sealing of the compression chamber 13 and reduces the efficiency of the scroll compressor 1.

[0033] 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, and 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 at this time 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, and the efficiency of the scroll compressor 1 decreases.

[0034] That is, there is an optimum value for the back pressure, and if it is too low, the sealing of the compression chamber deteriorates and thermal fluid loss increases, while if it is too high, sliding loss increases. Therefore, maintaining the back pressure at an optimum value is important for improving the performance and reliability of the compressor.

[0035] In order to obtain this optimum back pressure value, in the scroll compressor of this embodiment, as shown in FIG. 1, a back pressure valve 31 for adjusting the back pressure in the back pressure chamber 18 is provided in the support portion 7d of the fixed scroll 7.

[0036] 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 and 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.

[0037] The valve 31a moves upward to connect the back pressure valve inlet channel 32a to the back pressure valve outlet channel 32c when the load due to the pressure in the back pressure valve inlet channel 32a (i.e., the back pressure that is the pressure in the back pressure chamber 18) becomes higher than the load due to the sum of the pressure in the space 32b introduced via the back pressure valve outlet channel 32c (i.e., the pressure in the compression chamber) and the spring 31b. 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, thereby adjusting the pressure in the back pressure chamber 18 (back pressure) to an appropriate value.

[0038] The basic configuration of the scroll compressor 1 has been described above. Next, we will describe 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.

[0039] If this axial clearance is too small, sliding loss at the wrap tips (tooth tips 7f, 8f) increases, or the wrap tips come into contact with the tooth bottoms (spiral sliding surfaces) 7c, 8c, causing wear and galling, resulting in reduced reliability. Furthermore, if the axial clearance is too large, the sealing performance of the compression chamber 13 decreases, increasing leakage, increasing thermal fluid loss, and reducing the efficiency of the scroll compressor 1. Therefore, just as it is important to adjust 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.

[0040] The scroll compressor 1 draws refrigerant gas through the suction port 14 shown in FIG. 2, compresses it sequentially in the crescent-shaped compression chambers 13, and discharges the compressed refrigerant gas through 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 central portion near the discharge port 15 than in the peripheral portion near the suction port 14. Therefore, 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 wrap and the tooth root 8c of the opposing orbiting scroll 8 is eliminated, resulting in increased sliding loss and reduced reliability due to wear and galling caused by contact. The same applies to the wrap tip of the orbiting wrap 8b and the tooth root 7c of the opposing fixed scroll 7.

[0041] To solve this problem, it has been considered to form the tooth bottom (spiral sliding surface) 8c of the orbiting scroll 8 into a sloped shape that monotonically deepens from the wrap outer periphery toward the wrap center, as shown in Fig. 4, 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 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 side of the orbiting wrap 8b, and the right side indicates the center side of the orbiting wrap 8b.

[0042] Reference numeral 40 in the figure represents the axial clearance 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 clearance 40 becomes almost zero when the orbiting wrap 8b thermally expands during operation of the scroll compressor 1.

[0043] Although the tooth bottom shape of the orbiting scroll 8 has been described above, the axial gap 40 can also be formed by forming the tooth bottom (spiral sliding surface) 7c of the fixed scroll 7 as a sloped shape that is dug so that the depth monotonically deepens from the wrap outer periphery toward the wrap center. Also, the axial gap 40 can 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.

[0044] As explained in Figure 4, if only the 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 slope shape in which the depth monotonically increases 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.

[0045] However, in reality, the end 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.

[0046] Here, the pressure acting on the orbiting scroll 8 will be described with reference to Figures 5 and 6. Figure 5 is a schematic diagram illustrating the pressure distribution acting on the orbiting scroll 8, and Figure 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 orbiting bearing 8g on the back side of orbiting scroll 8, while back pressure Pb (pressure between discharge pressure and suction pressure) acts on the area outside orbiting bearing 8g, which is the back pressure chamber 18. The resultant force of these pressures serves as a force pushing up on orbiting scroll 8. The outermost periphery of end plate 8a on the top side of orbiting scroll 8 faces back pressure chamber 18, so back pressure Pb acts thereon. As the pressure moves from there toward suction chamber 20 or 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 compression chamber 13 in the middle of compression. Further inward, as compression chamber 13 becomes more advanced, the pressure rises, reaching discharge pressure Pd at the center where discharge port 15 is located. The resultant force of these pressures serves as a force pushing down on 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.

[0047] 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, causing the wrap 8b to deform into a concave shape with the outer periphery of the wrap 8b bending upward and the center of the wrap 8b bending downward, as shown in Fig. 6. If only this type of deformation were to occur, it would suffice to make the tooth bottom 8c etc. have a sloped shape that is monotonously dug deeper toward the center of the wrap 8b, like the tooth bottom shape that accommodates thermal expansion, as explained using Fig. 4.

[0048] However, generally, a key groove (counterbore elongated hole) 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 deformation of the orbiting scroll 8 due to this key groove 8h.

[0049] Next, the configuration of a scroll compressor according to a 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 schematically illustrates 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 portions provided on the orbiting scroll are formed.

[0050] As described above, deformation due to thermal expansion of the orbiting scroll 8 or the application of pressure as described in Figures 5 and 6 can be prevented by, for example, forming a sloped shape in which the tooth bottom 8c is dug steadily deeper toward the center of the wrap 8b, as described with reference to Figure 4. However, in reality, the orbiting scroll 8 is deformed by the key groove 8h provided on the back surface of the orbiting scroll 8.

[0051] That is, the end plate 8a has a thinner thickness at the location where the key grooves 8h are provided, resulting in a lower rigidity. 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 generally concave shape as explained with reference to Figure 6. In addition to this deformation, the low-rigidity location where the key grooves 8h are provided also deforms so as to bend at the imaginary line 41 connecting the key grooves 8h, which is shown by a dashed line in Figure 7.

[0052] When the end 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 also moves away from the tooth bottom 8c of the orbiting scroll 8. Therefore, the axial clearance 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.

[0053] In order 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 shape similar to that of a padded area.

[0054] Specifically, as shown in Fig. 8, a protrusion (plasterwork) 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 Fig. 7) where the key groove 8h is present. Since the head plate 8a bends the most at the bending position 42 shown in Fig. 8, the protrusion 50 is formed so that it is highest (the padding is thickest) at this bending position 42, and the height of the protrusion 50 decreases (the amount of padding decreases) as it moves away from the bending position 42.

[0055] 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 bending position 42 (a position corresponding to imaginary line 41 in Fig. 7, hereinafter also referred to simply as position) by the key groove 8h. Since the head 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, 50d.

[0056] That is, the protrusion 50 is composed of a plurality of inclined surfaces 50a, 50b, 50c, and 50d with the center as its apex. In this embodiment, the inclination of the inclined surfaces 50b and 50d extending from the center toward the central portion is greater than the inclination of the inclined surfaces 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 center line of the key groove 8h in the groove width direction, i.e., on the imaginary line 41.

[0057] Two keyways 8h are provided on opposite sides of the end plate 8a of the orbiting scroll 8, and the protrusions 50 are provided on the tooth bottoms (spiral sliding surface) 8c (or the tooth tips of the spiral wraps) corresponding to the positions of the two keyways 8h. That is, when the intersection of an imaginary line 41 connecting the two keyways 8h and the tooth bottoms (spiral sliding surface) 8c is taken as a reference, the protrusions 50 are provided on the tooth bottoms (spiral sliding surface) 8c (or the tooth tips 8f of the spiral wraps 8b corresponding to the reference), and the gradient of the protrusions 50 from the reference toward the center is greater than the gradient of the gradient from the reference toward the outer periphery. The reference corresponds to the bending position 42.

[0058] FIG. 9 shows the ranges of formation of the convex portions 50 provided on the tooth bottom 8c of the orbiting scroll 8. As shown in FIG. 9, the convex portions 50 are formed in 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 aforementioned inclined surfaces 50a, 50b, 50c, and 50d, respectively. That is, when the orbiting scroll 8 is viewed from above, in this embodiment, the convex portions 50 are formed in the ranges of the regions 51a, 51b, 51c, and 51d shown in FIG. 9. Of the two convex portions 50 provided corresponding to the two key grooves 8h, the convex portion on the outer periphery is provided in the ranges shown in regions 51a and 51b, and the convex portion on the central portion is provided in the ranges shown in regions 51c and 51d. The vertices of the two convex portions 50 are formed to be located at the bending positions 42.

[0059] 9 is an example, and in this embodiment, all of the regions 51a to 51d are formed within a 90-degree range from the bending position 42. Therefore, the length of the slope 50a in the region 51a located closest to the outer periphery is the longest, and the length of the slope in the region 51d located closest to the center is the shortest.

[0060] The range of each of the regions 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 when the range of each of the regions 51a-51d is 45 degrees, it is possible to configure the axial gap 40 to be small at the position 42 where the end plate 8a bends most greatly. That is, when the intersection of the imaginary line 41 connecting the two keyways 8h and the tooth bottom (spiral sliding surface) 8c is taken as a reference (corresponding to the bending position 42), the apex of the convex portion 50 is provided 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 are each preferably in the range of 45 to 90 degrees in terms of wrap angle.

[0061] Furthermore, the tooth bottom 8c (or the tooth tip 7f of the spiral wrap 7b) is formed along a reference slope that takes thermal expansion into account from the outer periphery to the center 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 to the center, excluding the portion where the protrusion 50 is provided. In this way, the axial gap can be determined in consideration of thermal expansion.

[0062] It is preferable that the end portion of the protrusion 50 facing the outer periphery and the end portion facing the center are configured to be on the reference slope. Also, it is 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.

[0063] 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, thereby further reducing thermal fluid loss and improving the efficiency of the compressor.

[0064] 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, but 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, using FIGS. 10 to 12, we will specifically explain modified examples of the present invention in which the position at which the protrusion 50 is provided is changed.

[0065] (Variation 1) Fig. 10 is a diagram for explaining a first embodiment of the present invention, and is a development view that schematically shows 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, taking thermal expansion into consideration, and a protrusion 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 the first embodiment.

[0066] 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. That is, 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.

[0067] As in 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.

[0068] (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 tip 8f of the orbiting scroll 8 is 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 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.

[0069] 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 becomes 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.

[0070] Note that, similar to the shape of the tooth tip 8f of the orbiting scroll 8, the convex portion 50 may also be provided on the tooth tip 7f of the fixed scroll 7, 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 in a sloped shape. Also, as in Example 1 and Modification 1 shown in Figs. 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.

[0071] (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 tip 7f of the fixed scroll 7 is configured to gradually become lower in a sloped shape from the outer periphery toward the center in consideration of thermal expansion, and a protrusion 50 is provided near 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.

[0072] 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 becomes 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.

[0073] 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 formed in a sloped shape. Furthermore, as in Example 1 and Modification 1 shown in Figs. 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.

[0074] As described above, by configuring the first embodiment and each of the modified examples of the present invention, a convex portion is provided on at least one of the tooth bottom or tooth tip of the orbiting scroll corresponding to the keyway of the orbiting scroll and the tooth bottom or tooth tip of the fixed scroll, so that even if the end plate of the orbiting scroll is deformed by the pressure of the compressed gas, a scroll compressor can be obtained in which the axial gap between the spiral wrap and its mating tooth bottom can be appropriately maintained, taking into account the deformation of the end 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 bottom can be suppressed, and leakage loss at the tip ends of the wraps can be reduced, further improving the efficiency of the scroll compressor, thereby providing a highly efficient scroll compressor.

[0075] It should be noted that the present invention is not limited to the above-described embodiments or modifications, but includes various modifications. Furthermore, the above-described embodiments and modifications have been described in detail to make the present invention easier to understand, and the present invention is not necessarily limited to those having all of the described configurations. [Explanation of symbols]

[0076] 1: Scroll compressor, 2: Sealed container (case), 3: Compression mechanism, 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: head 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: Discharge space, 16a: First discharge space, 16b: Second discharge 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: Convex portion (thickened portion), 50a, 50b, 50c, 50d: Slope, 51a, 51b, 51c, 51d: Areas (where protrusions are formed).

Claims

1. 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.

2. 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.

3. 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.

4. 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.

5. 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.

6. 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.

7. 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, respectively.

8. 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.

9. 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.

10. 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.

11. 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.

12. 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.

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