Scroll compressor
By incorporating an injection port and low-expansion materials in the scroll compressor, the thermal expansion differences are mitigated, reducing tooth tip biting and enhancing mechanical stability.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- MITSUBISHI HEAVY IND THERMAL SYST
- Filing Date
- 2025-10-16
- Publication Date
- 2026-05-15
AI Technical Summary
The occurrence of tooth tip biting in scroll compressors due to thermal expansion differences caused by injecting a low-temperature refrigerant during the compression process, leading to potential mechanical failure.
The scroll compressor employs a fixed end plate with an injection port to guide a low-temperature fluid into the compression chamber, using materials with a linear expansion coefficient of 10 × 10^-6 /K or less for the fixed and orbiting scroll members, and optimizing the wrap gap and injection port positioning to minimize thermal expansion differences.
Reduces the possibility of tooth tip biting by minimizing thermal expansion differences between the scroll wraps, thereby enhancing mechanical stability and reducing mechanical failure.
Smart Images
Figure JP2025036532_15052026_PF_FP_ABST
Abstract
Description
Scroll compressor
[0001] The present disclosure relates to a scroll compressor.
[0002] For example, in the scroll compressor described in Patent Document 1, an injection structure for injecting a low-temperature refrigerant during the compression stroke is adopted in order to reduce the discharge gas temperature.
[0003] Japanese Patent Application Laid-Open No. 2019-210867
[0004] When a refrigerant having a lower temperature than the refrigerant in the compression process is injected into the compression chamber, the housing, or the suction pipe, a temperature difference occurs in the compression chamber due to the decrease in the temperature of the scroll wrap caused by the injected refrigerant. Then, a thermal expansion difference (tooth height expansion difference) occurs in the scroll wrap, so that an event in which the tooth tip of the wrap contacts the end plate facing the tooth tip (this is referred to as "tooth tip biting") may occur.
[0005] The present disclosure has been made in view of such circumstances, and an object thereof is to provide a scroll compressor capable of reducing the possibility of tooth tip biting.
[0006] In order to solve the above problems, the scroll compressor of the present disclosure employs the following means. The scroll compressor according to one aspect of the present disclosure includes a fixed scroll member having a spiral fixed wrap provided on a fixed end plate, and a spiral orbiting wrap provided on an orbiting end plate disposed to face the fixed end plate, the orbiting wrap meshing with the fixed wrap to form a compression chamber for compressing a fluid. The fixed end plate is formed with an injection port for guiding a fluid having a lower temperature than the fluid in the compression process in the compression chamber into the compression chamber, and the fixed scroll member and / or the orbiting scroll member is made of a material having a linear expansion coefficient of 10×10 －６ / K or less.
[0007] According to the present disclosure, the possibility of tooth tip biting can be reduced.
[0008] This figure shows an example of a refrigerant circuit including a scroll compressor according to one embodiment of the present disclosure. This is a longitudinal cross-sectional view of a scroll compressor according to one embodiment of the present disclosure. This is a planar cross-sectional view of the compression mechanism of a scroll compressor according to one embodiment of the present disclosure.
[0009] A scroll compressor according to one embodiment of this disclosure will be described below with reference to the drawings.
[0010] [Scroll Compressor Configuration] As shown in Figure 1, the scroll compressor 11, together with the condenser 12, expansion valve 13, evaporator 14, refrigerant piping 15, etc., constitutes a refrigeration cycle 10 in which fluid is sealed. The fluid is a refrigerant that undergoes a greater temperature change during the compression process than R1234yf (for example, R32).
[0011] This refrigeration cycle 10 is equipped with an injection circuit 20. The injection circuit 20 includes an injection pipe 21, a strainer 22 provided on the injection pipe 21, a valve 23, and a capillary tube 24.
[0012] The injection piping 21 connects the refrigerant piping 15, which is connected to the refrigerant outlet of the condenser 12, to the scroll compressor 11, and is configured to guide the refrigerant condensed in the condenser 12 to the scroll compressor 11 (more specifically, to the injection pipe 34 described later). The strainer 22 is a device for removing foreign matter contained in the liquid refrigerant flowing through the injection piping 21. The valve 23 is a valve for adjusting the flow rate of the liquid refrigerant flowing through the injection piping 21. Examples of valves 23 include on / off valves and flow control valves. The capillary tube 24 is a device for adjusting the pressure and condition of the liquid refrigerant flowing through the injection piping 21 to a state suitable for injection.
[0013] The injection circuit 20 further includes a temperature measuring means (not shown). The temperature measuring means is a device for measuring the temperature of the refrigerant immediately before it flows into the scroll compressor 11. Based on the measurement value from the temperature measuring means, the degree of superheating of the refrigerant immediately before it flows into the scroll compressor 11 is determined. A thermocouple is an example of a temperature measuring means. However, the degree of superheating of the refrigerant may be determined by a method other than using a thermocouple. The temperature measuring means may also be provided in the injection tube 34, which will be described later.
[0014] As shown in Figure 2, the scroll compressor 11 is a sealed scroll compressor and comprises a housing 33 having a sealed space inside, a discharge cover 40 that divides the sealed space, a compression mechanism 60 that compresses the refrigerant, a drive shaft 95 that causes the orbiting scroll member 80 of the compression mechanism 60 to revolve and rotate, and an electric motor 96 that drives the drive shaft 95.
[0015] The housing 33 has an upper housing 33A, an intermediate housing 33B, and a lower housing (not shown), forming a sealed space inside.
[0016] The upper housing 33A and the intermediate housing 33B are connected via the outer peripheral end of the discharge cover 40. Therefore, the discharge cover 40 divides the sealed space inside the housing 33 in the direction of the central axis X (up and down direction in Figure 2). Of the divided sealed space, the space formed above the discharge cover 40 is designated as the discharge chamber 53, and the space formed below the discharge cover 40 is designated as the intake chamber 55.
[0017] A discharge pipe 31 is provided on the upper wall of the upper housing 33A for discharging refrigerant from the discharge chamber 53 to the outside of the housing 33. The discharge pipe 31 is connected to the refrigerant piping 15, and is configured so that the refrigerant discharged from the discharge pipe 31 is guided to the condenser 12 (see Figure 1).
[0018] An intake pipe 32 is provided on the side wall of the intermediate housing 33B for drawing refrigerant into the intake chamber 55 from outside the housing 33. The intake pipe 32 is connected to the refrigerant piping 15 and is configured to guide the refrigerant evaporated in the evaporator 14 into the intake chamber 55 (see Figure 1).
[0019] The intake chamber 55 is provided with a compression mechanism 60 for compressing the refrigerant, a drive shaft 95, an electric motor 96, and a support member 97 that pivotally supports the drive shaft 95.
[0020] The compression mechanism 60 includes a fixed scroll member 70 on which a spiral fixed wrap 75 is provided on a fixed end plate 71, and a spiral scroll member 80 on which a spiral spiral wrap 85 is provided on a spiral end plate 81. In the fixed scroll member 70 and the spiral scroll member 80, the fixed wrap 75 and the spiral wrap 85 mesh with each other to form a compression chamber 61. The tooth height of the fixed wrap 75 and the spiral wrap 85 is, for example, 15 mm or more. A wrap gap is set between the tooth tip of the fixed wrap 75 and the tooth root of the spiral end plate 81, and between the tooth tip of the spiral wrap 85 and the tooth root of the fixed end plate 71, taking into account the thermal expansion of each wrap. However, the wrap gap in the area facing the injection port 73 (openings 73a, 73b), which will be described later, may be set larger than the wrap gap in other areas.
[0021] The fixed scroll member 70 and / or the orbiting scroll member 80 have a coefficient of linear expansion of 10 × 10 －６ Materials with a temperature of / K or less, preferably 5 x 10 －６ It is made of a material with a coefficient of thermal expansion of 10°C or less. The lower limit of the coefficient of thermal expansion is not particularly limited, but as an example, it is 0.7 × 10°C. －６ The material is defined as / K. An example of the material is a low thermal expansion cast iron in which C (carbon), Si (silicon), Ni (nickel), and Sb (antimony) are blended in an optimal ratio. The portion formed from this material is the base material (substrate) of the fixed scroll member 70 and / or the orbiting scroll member 80, and the coating applied to the fixed scroll member 70 and / or the orbiting scroll member 80 may be made of a different material.
[0022] The fixed scroll member 70 is fixed to the support member 97 by a fixing portion 74 formed on the outer peripheral end of the fixed end plate 71. Since the support member 97 is fixed to the intermediate housing 33B, the fixed scroll member 70 is fixed to the intermediate housing 33B via the support member 97.
[0023] The orbiting scroll member 80 is configured to revolve and orbit around the central axis X of the fixed scroll member 70 by means of a drive shaft 95 and an anti-rotation mechanism (for example, an Oldham link).
[0024] A discharge cover 40 is positioned above the fixed scroll member 70 (on the back side of the fixed end plate 71), and together with the back surface of the fixed end plate 71, it forms a back pressure chamber 54 and an injection refrigerant flow path 56. The back pressure chamber 54 is a space formed in approximately the central part in the radial direction. On the other hand, the injection refrigerant flow path 56 is a space (flow path) formed radially outside the back pressure chamber 54 and does not communicate with the back pressure chamber 54.
[0025] The fixed end plate 71 has a discharge port 72 that connects the compression chamber 61 and the back pressure chamber 54. The discharge cover 40 also has a discharge port 41 (different from the discharge port 72 on the fixed end plate 71) that connects the back pressure chamber 54 and the discharge chamber 53. In other words, the compression chamber 61 and the discharge chamber 53 are connected via the discharge port 72, the back pressure chamber 54, and the discharge port 41.
[0026] In the back pressure chamber 54, a reed valve 92 and a retainer 93 that restricts the range of motion of the reed valve 92 are provided at the outlet of the discharge port 72.
[0027] The fixed end plate 71 is further provided with at least one injection port 73 that connects the compression chamber 61 and the injection refrigerant flow path 56. An injection pipe 34 for guiding refrigerant from the injection piping 21 is provided on the upper wall of the upper housing 33A. The injection pipe 34 is connected to the injection refrigerant flow path 56 via a connecting pipe 35 attached to the discharge cover 40. In other words, the flow path in the injection pipe 34 and the compression chamber 61 are in communication via the flow path in the connecting pipe 35, the injection refrigerant flow path 56, and the injection port 73.
[0028] As shown in Figure 3, the position of the injection port 73 (more precisely, the positions of the openings 73a and 73b of the injection port 73 facing the compression chamber 61) is set to a predetermined location. This predetermined location is within 180 degrees from the position where the compression chamber 61 begins to close when the end of the fixed wrap 75 of the fixed scroll member 70 and the end of the orbiting wrap 85 of the orbiting scroll member 80 engage. In the case of Figure 3, the opening 73a of the injection port 73 is provided at the position where communication to the compression chamber 61 begins when the chamber is closed at the closing start position P1 (this may be within a further 180-degree range in the orbital angle), and the opening 73b of the other injection port 73 is provided at the position where communication to the compression chamber 61 begins when the chamber is closed at the closing start position P2 (this may be within a further 180-degree range in the orbital angle). Note that the closing start position P1 is also the position where the inner surface of the fixed wrap 75 and the outer surface of the orbiting wrap 85 begin to come into contact. Therefore, the opening 73a faces the compression chamber 61 formed between the inner surface of the fixed wrap 75 and the outer surface of the swivel wrap 85. On the other hand, the closing start position P2 is also the position where the inner surface of the swivel wrap 85 and the outer surface of the fixed wrap 75 begin to come into contact. Therefore, the opening 73b faces the compression chamber 61 formed between the inner surface of the swivel wrap 85 and the outer surface of the fixed wrap 75.
[0029] [Refrigerant Flow] In the scroll compressor 11 configured as described above, the refrigerant flows as follows. That is, the refrigerant evaporated in the evaporator 14 (see Figure 1) is guided through the refrigerant piping 15 from the suction pipe 32 to the suction chamber 55 of the scroll compressor 11. Here, it is preferable that the superheating degree of the refrigerant at the outlet of the suction pipe 32 is 30 degrees or less.
[0030] As shown in Figure 2, the refrigerant introduced into the intake chamber 55 is taken into the compression chamber 61 from around the compression mechanism 60 (compression chamber 61). The refrigerant taken into the compression chamber 61 is compressed in the compression chamber 61, whose volume changes due to the orbital motion of the orbiting scroll member 80, and is introduced into the back pressure chamber 54 through the discharge port 72 formed in the central part of the fixed end plate 71. Here, it is preferable that the degree of superheating of the refrigerant at the inlet of the compression chamber 61 is 50 degrees or less.
[0031] The refrigerant guided into the back pressure chamber 54 is then guided into the discharge chamber 53 via the discharge port 41 formed in the discharge cover 40.
[0032] The refrigerant guided into the discharge chamber 53 is then guided from the discharge pipe 31 to the condenser 12 (see Figure 1) via the refrigerant piping 15 connected to the discharge pipe 31.
[0033] As shown in Figure 1, the refrigerant introduced into the condenser 12 is condensed by heat exchange, and some of the liquid refrigerant is introduced into the injection piping 21, while the remaining refrigerant is introduced into the expansion valve 13 via the refrigerant piping 15.
[0034] The refrigerant guided to the expansion valve 13 is expanded (pressurized) and guided to the evaporator 14. The same cycle is then repeated.
[0035] Meanwhile, the liquid refrigerant guided into the injection piping 21 is led to the injection tube 34 provided in the scroll compressor 11 via the strainer 22, valve 23, and capillary tube 24.
[0036] As shown in Figure 2, the refrigerant introduced into the injection tube 34 is guided to the compression chamber 61 via the injection refrigerant flow path 56 and the injection port 73, where it merges with the refrigerant undergoing compression. Here, the temperature of the refrigerant introduced into the compression chamber 61 is lower than the temperature of the refrigerant undergoing compression in the compression chamber 61. Although the refrigerant is in the state of wet vapor immediately after flowing out of the capillary tube 24, it may be heated during the process of being introduced into the compression chamber 61, and the state of the refrigerant just before flowing into the compression chamber 61 may be superheated vapor. When the refrigerant is superheated vapor, it is preferable that its degree of superheating is 10 degrees or less.
[0037] [Effects] The scroll compressor according to this embodiment provides the following effects.
[0038] The fixed end plate 71 has an injection port 73 formed therein for guiding a refrigerant at a lower temperature than the refrigerant undergoing compression in the compression chamber 61 into the compression chamber 61, and the fixed scroll member 70 and / or the orbiting scroll member 80 have a coefficient of linear expansion of 10 × 10 －６ Since it is made of a material with a temperature of 0.5°C or lower, the difference in thermal expansion (difference in tooth height expansion) between each wrap 75 and 85 caused by the temperature difference in the compression chamber resulting from introducing a low-temperature refrigerant is smaller than the difference in thermal expansion when using general materials, thus reducing the possibility of tooth tip galling caused by the difference in thermal expansion.
[0039] Since the degree of superheating of the fluid introduced into the compression chamber 61 via the injection port 73 is set to 10 degrees or less, in this embodiment, where a low-temperature refrigerant is introduced into the compression chamber 61 and the temperature difference within the compression chamber 61 tends to be large, it is expected that the possibility of tooth tip galling caused by thermal expansion differences will be reduced.
[0040] Since the injection port 73 is formed within a range of 180 degrees from the positions P1 and P2 where the compression chamber 61 is closed, in this embodiment, where the outer periphery of the compression chamber 61 tends to become colder and the temperature difference between the outer periphery and the center of the compression chamber 61 tends to be large, it is expected that the possibility of tooth tip galling caused by thermal expansion differences will be reduced.
[0041] The superheat degree of the refrigerant at the outlet of the suction pipe 32 is set to 30 degrees or less, or the superheat degree of the refrigerant at the inlet of the compression chamber 61 is set to 50 degrees or less. Therefore, in this embodiment where it is easy to have a temperature difference with the refrigerant introduced into the compression chamber 61 via the injection port 73, an effect of particularly reducing the possibility of tip biting due to the thermal elongation difference can be expected.
[0042] Since the temperature change of the refrigerant in the compression process in the compression chamber 61 is greater than that of R1234yf, in this embodiment where the temperature difference between the outer peripheral portion and the central portion of the compression chamber 61 is likely to increase, an effect of particularly reducing the possibility of tip biting due to the thermal elongation difference can be expected.
[0043] In this embodiment where it is easy to have a temperature difference with the refrigerant introduced into the compression chamber 61 via the injection port 73, since the thermal elongation difference in the range facing the injection port 73 (openings 73a, 73b) is large, by increasing the wrap gap in this range, an effect of reducing the possibility of tip biting due to the thermal elongation difference in this range can be expected.
[0044] [Modification] In the embodiment described above, the low-temperature refrigerant was injected into the compression chamber 61 via the injection port 73 formed in the fixed end plate 71. However, the location for guiding the low-temperature refrigerant is not limited to the injection port 73 formed in the fixed end plate 71, and it may be any position where the low-temperature refrigerant is finally guided to the compression chamber 61. For example, an injection port may be formed in the suction pipe 32 or the housing 33, and the low-temperature refrigerant may be injected into the inside of the suction pipe 32 or the inside of the housing 33 (for example, the suction chamber 55).
[0045] [Supplementary Note] The scroll compressor according to an embodiment of the present disclosure described above can be understood, for example, as follows.
[0046] A scroll compressor (11) according to a first aspect of the present disclosure comprises a fixed scroll member (70) having a spiral fixed wrap (75) on a fixed end plate (71), and a spiral scroll member (80) having a spiral spiral wrap (85) on a spiral end plate (81) arranged opposite to the fixed end plate, the spiral wrap engaging with the fixed wrap to form a compression chamber (61) for compressing a fluid, and an injection port (73) for introducing a fluid at a lower temperature than the fluid being compressed into the compression chamber, and the fixed scroll member and / or the spiral scroll member having a coefficient of linear expansion of 10 × 10 －６ It consists of materials with a K rating of / or lower.
[0047] An injection port is provided in the compression chamber to introduce a fluid at a lower temperature than the fluid undergoing compression into the compression chamber, and the fixed scroll member and / or orbiting scroll member have a coefficient of linear expansion of 10 × 10 －６ Since it is made of a material with a temperature of 0.5°C or lower, the difference in thermal expansion (difference in tooth height expansion) of each wrap caused by the temperature difference in the compression chamber resulting from introducing a low-temperature fluid is smaller than the difference in thermal expansion when using general materials, thus reducing the possibility of tooth tip galling caused by the difference in thermal expansion.
[0048] In the scroll compressor according to a second aspect of this disclosure, in the first aspect, the degree of superheating of the fluid introduced into the compression chamber via the injection port is 10 degrees or less.
[0049] Since the superheating of the fluid introduced into the compression chamber via the injection port is set to 10 degrees or less, in this embodiment, where a low-temperature fluid is introduced into the compression chamber and the temperature difference within the compression chamber tends to be large, it is expected that the possibility of tooth tip galling caused by thermal expansion differences will be reduced.
[0050] In a scroll compressor according to a third aspect of this disclosure, in the first or second aspect, the injection port is formed in the fixed end plate and is located within a range of 180 degrees from the position (P1, P2) where the closure of the compression chamber is initiated.
[0051] Since the injection port is formed in the fixed end plate and positioned within 180 degrees from the position where the compression chamber is closed, in this embodiment, where the outer periphery of the compression chamber tends to become colder and the temperature difference between the outer periphery and the center of the compression chamber tends to be large, it is expected to have the effect of reducing the possibility of tooth tip galling caused by thermal expansion differences.
[0052] A scroll compressor according to a fourth aspect of the present disclosure, in any of the first to third aspects, comprises a housing (33) for housing the fixed scroll member and the orbiting scroll member, and a suction pipe (32) for introducing fluid into the housing, wherein the degree of superheating of the fluid at the outlet of the suction pipe is 30 degrees or less, or the degree of superheating of the fluid at the inlet of the compression chamber is 50 degrees or less.
[0053] Since the superheating of the fluid at the outlet of the suction pipe is set to 30 degrees or less, or the superheating of the fluid at the inlet of the compression chamber is set to 50 degrees or less, in this embodiment, where a temperature difference is likely to occur between the fluid introduced into the compression chamber via the injection port, it is expected that the possibility of tooth tip galling caused by thermal expansion differences will be reduced.
[0054] In the scroll compressor according to the fifth aspect of this disclosure, in any of the first to fourth aspects, the fluid is a refrigerant.
[0055] Since the fluid is a refrigerant, a scroll compressor can be used to compress the refrigerant.
[0056] In the scroll compressor according to the sixth aspect of this disclosure, in the fifth aspect, the refrigerant is such that the temperature change during the compression process in the compression chamber is greater than that of R1234yf.
[0057] Since the refrigerant is said to have a greater temperature change during the compression process in the compression chamber than R1234yf, in this embodiment, where the temperature difference between the outer periphery and the center of the compression chamber tends to be large, it is expected to have the effect of reducing the possibility of tooth tip galling caused by thermal expansion differences.
[0058] In the scroll compressor according to the seventh aspect of this disclosure, in any of the first to sixth aspects, the lap gap in the area facing the injection port is larger than the lap gap in the other areas.
[0059] In this embodiment, where a temperature difference is likely to occur between the fluid introduced into the compression chamber via the injection port, the difference in thermal expansion is large in the area facing the injection port. Therefore, by increasing the overlap gap in that area, it is expected that the possibility of tooth tip galling caused by the difference in thermal expansion in that area can be reduced.
[0060] 10 Refrigeration cycle 11 Scroll compressor 12 Condenser 13 Expansion valve 14 Evaporator 15 Refrigerant piping 20 Injection circuit 21 Injection piping 22 Strainer 23 Valve 24 Capillary tube 31 Discharge pipe 32 Suction pipe 33 Housing 33A Upper housing (housing) 33B Intermediate housing (housing) 34 Injection pipe 35 Connecting pipe 40 Discharge cover 41 Discharge port 53 Discharge chamber 54 Back pressure chamber 55 Suction chamber 56 Injection refrigerant flow path 60 Compression mechanism 61 Compression chamber 70 Fixed scroll member 71 Fixed end plate 72 Discharge port 73 Injection port 74 Fixed part 75 Fixed wrap 80 Swivel scroll member 81 Swivel end plate 85 Swivel wrap 92 Reed valve 93 Retainer 95 Drive shaft 96 Electric motor 97 Support member
Claims
1. A fixed scroll member having a spiral-shaped fixed wrap on a fixed end plate, and a spiral scroll member having a spiral-shaped spiral wrap on a spiral end plate positioned opposite the fixed end plate, the spiral wrap meshing with the fixed wrap to form a compression chamber for compressing fluid, wherein an injection port is provided for introducing a fluid at a lower temperature than the fluid undergoing compression into the compression chamber, and the fixed scroll member and / or the spiral scroll member have a coefficient of linear expansion of 10 × 10 －６ A scroll compressor made of materials with a K rating of / K or lower.
2. The scroll compressor according to claim 1, wherein the degree of superheating of the fluid introduced into the compression chamber via the injection port is 10 degrees or less.
3. The scroll compressor according to claim 1, wherein the injection port is formed in the fixed end plate and is located within a range of 180 degrees from the position in which the closure of the compression chamber is initiated.
4. The scroll compressor according to claim 2, comprising: a housing for housing the fixed scroll member and the orbiting scroll member; and a suction pipe for guiding fluid into the interior of the housing, wherein the superheating degree of the fluid at the outlet of the suction pipe is 30 degrees or less, or the superheating degree of the fluid at the inlet of the compression chamber is 50 degrees or less.
5. The scroll compressor according to any one of claims 1 to 4, wherein the fluid is a refrigerant.
6. The scroll compressor according to claim 5, wherein the refrigerant is such that the temperature change during the compression process in the compression chamber is greater than that of R1234yf.
7. The scroll compressor according to claim 3, wherein the lap gap in the area facing the injection port is larger than the lap gap in the other areas.