Patent Application
20240410601
The present disclosure relates to a compressor and an air conditioner.
Some typical compressors include a muffler provided between a fluid outlet (discharge port) of a compression mechanism in a casing and a high-pressure space in the casing (see, e.g., Japanese Utility Model Publication No. S55-17914).
The compressor of Japanese Utility Model Publication No. S55-17914 employs a configuration allowing the resonance frequency in the muffler to match the resonance frequency in the space between the muffler and the casing in order to reduce noise.
A first aspect of the present disclosure is directed to a compressor including a casing having a cylindrical shape and end plates at both ends, a compression mechanism housed in the casing, and a muffler disposed between a fluid outlet of the compression mechanism and a space in the casing. A size of the casing or the muffler is set so that in an entire range of a first resonance mode in which a resonance frequency changes as an oil level of lubricant oil stored in the casing changes, the resonance frequency of the first resonance mode is different from a resonance frequency of a second resonance mode in which the resonance frequency does not change as the oil level of the lubricant oil changes.
Embodiments will be described in detail with reference to the drawings.
A compressor (10) of this embodiment is a compressor (10) of oscillating piston type and is connected to a refrigerant circuit (1) as shown in
The compressor (10) includes a casing (20). The casing (20) is a closed container having a vertically long cylindrical shape and including a first end plate (22) at one end (upper end) and a second end plate (23) at the other end (lower end) of a cylindrical barrel (21) in the axial direction. The casing (20) houses a compression mechanism (30) that compresses a refrigerant in the refrigerant circuit (1) and an electric motor (40) of variable-speed type that drives the compression mechanism (30), where the compression mechanism (30) and the electric motor (40) are fixed to the inner peripheral surface of the barrel (21). the electric motor (40) is disposed in the casing (20) in which a first space (S1) is sandwiched between the electric motor (40) and the first end plate (22), and the compression mechanism (30) is disposed in the casing (20) in which a second space (S2) is sandwiched between the compression mechanism (30) and the electric motor (40).
The electric motor (40) includes a stator (41) and a rotor (42), both formed in a cylindrical shape. The stator (41) is fixed to the barrel (21) of the casing (20). The stator (41) includes a hollow portion where the rotor (42) is disposed. A drive shaft (45) is fixed to a hollow portion of the rotor (42) so as to penetrate the rotor (42), and the rotor (42) and the drive shaft (45) rotates integrally.
The drive shaft (45) includes a main shaft portion (46) extending vertically. The drive shaft (45) is formed integrally with an eccentric portion (47) near a lower end of the main shaft portion (46). The eccentric portion (47) has a larger diameter than the main shaft portion (46). The eccentric portion (47) has an axis decentered by a predetermined distance with respect to the axis of the main shaft portion (46).
A lower end portion of the main shaft portion (46) is provided with an oil supply pump (48). The oil supply pump (48) is immersed in lubricant oil in an oil reservoir formed at the bottom of the casing (20). The oil supply pump (48) pumps up lubricant oil into an oil supply path (not shown) in the drive shaft (45) along with rotation of the drive shaft (45), and then supplies the lubricant oil to each sliding portion of the compression mechanism (30).
The compression mechanism (30) includes a cylinder (31) formed in an annular shape. The cylinder (31) has one axial end (upper end) to which a front head (32) is fixed and the other axial end (lower end) to which a rear head (33) is fixed. The cylinder (31), the front head (32), and the rear head (33) are stacked from top to bottom in order of the front head (32), the cylinder (31), and the rear head (33), and are fastened and fixed together with a plurality of bolts, for example. The compression mechanism (30) is what is called a single-cylinder compression mechanism including one cylinder and one piston.
The drive shaft (45) vertically penetrates the compression mechanism (30). The front head (32) and the rear head (33) are provided with bearing portions (32a, 33a) that support the drive shaft (45) at both above and below the eccentric portion (47).
The cylinder (31) has an upper end closed by the front head (32) and a lower end closed by the rear head (33). The internal space of the cylinder (31) forms a cylinder chamber (35). The cylinder (31) (cylinder chamber (35)) houses a tubular piston (34) slidably fitted to the eccentric portion (47) of the drive shaft (45). As the drive shaft (45) rotates, the piston (34) rotates eccentrically in the cylinder chamber (35). Although not shown in the figure, the piston (34) has an outer peripheral surface integrated with a blade extending radially outward from the outer peripheral surface of the piston (34). The blade is held by a bush (not shown) provided in the piston (34) and swings along with rotation of the drive shaft (45). Thus, the piston (34) being rotated by itself is restricted.
The cylinder (31) has a suction port (31a) communicating with the cylinder chamber (35). The suction port (31a) is connected with a suction pipe (36) fixed to the barrel (21). The suction pipe (36) is connected with an accumulator (37) fixed to the casing (20).
The front head (32) has a discharge port (32b) extending parallel to the axis of the drive shaft (45). The discharge port (32b) is opened and closed by a discharge valve (not shown). A muffler (38) is attached to an upper surface of the front head (32) so as to cover the discharge port (32b) and the discharge valve. A muffler space (38a) defined in the muffler (38) communicates with the internal space of the casing (20) through a discharge opening (38b) formed on an upper portion of the muffler (38).
As described above, the suction pipe (36) connected to the suction port (31a) is attached to the casing (20) so that a refrigerant is sucked into the compression mechanism (30) through the accumulator (37) and the suction pipe (36).
A discharge pipe (39) is attached to the casing (20) and penetrates the first end plate (22). A lower end portion of the discharge pipe (39) is open to the inside of the casing (20). The discharge port (32b) as a fluid outlet of the compression mechanism (30) communicates with the internal space of the casing (20) through the discharge opening (38b) of the muffler (38). A refrigerant discharged from the compression mechanism (30) flows out of the casing (20) through the internal space of the casing (20) and the discharge pipe (39).
The first end plate (22) of the casing (20) is provided with a terminal (50) to which an electric wire for supplying electric power to the electric motor (40) is connected.
As described above, the compressor of this embodiment includes: the casing (20) having a cylindrical shape and including the end plates (22, 23) at both ends; the compression mechanism (30) housed in the casing (20); and the muffler (38) disposed between the discharge port (32b) of the compression mechanism (30) and the space (second space (S2)) in the casing (20).
The compressor (10) has a first resonance mode where the resonance frequency changes as the oil level of lubricant oil stored in the casing (20) changes and a second resonance mode where the resonance frequency does not change as the oil level of lubricant oil stored in the casing (20) changes. The compressor (10) includes the casing (20) and the muffler (38), each of which has a size and shape defined so that in an entire range of the first resonance mode, a resonance frequency f1 of the first resonance mode is different from a resonance frequency f2 of the second resonance mode.
The resonance frequency f1 of the first resonance mode is a resonance frequency of which main parameters are a volume of the muffler and a volume of the primary space (60), and is determined by the formula shown in
The resonance frequency f2 of the second resonance mode is a resonance frequency generated in the cross section of the casing (20), and is determined by the formula shown in
In
In this embodiment, the resonance frequency f1 of the first resonance mode is about 1027 Hz, where the sound speed c is 243 (m/s), assuming an example where the area Ap of the discharge opening (38b) of the muffler (38) is 5.84×10−5 (m2), the length Lp of the discharge opening (38b) of which the opening end is corrected is 2.83×10−3 (m), the volume Vm of the muffler is 2.32×10−5 (m3), the volume V1 of the primary space (60) is 1.90×10−4 (m3), and the correction coefficient β is 0.84.
In
On the other hand, in a typical compressor (as a comparative example), the resonance frequency f1 of the first resonance mode is about 1160 Hz, where, for example, the area Ap of the discharge opening of the muffler is 4.75×10−5 (m2), the length Lp of the discharge opening of which the opening end is corrected is 2.65×10−3 (m), the volume Vm of the muffler is 1.55×10−5 (m3), the volume V1 of the primary space (60) is 1.56×10−4 (m3), the correction coefficient β is 0.84, and the sound speed c is 243 (m/s). In the comparative example, the resonance frequency f2 of the second resonance mode is about 1154 Hz similarly to the above example, where the correction coefficient α is 0.73, the mode coefficient λ is 1.84, the radius R1 is 4.5×10−2 (m) similarly to the above example, and the sound speed c is 243 (m/s).
As described above, this embodiment exhibits a large difference between the resonance frequency f1 of the first resonance mode and the resonance frequency f2 of the second resonance mode, while the typical compressor exhibits a small difference between the resonance frequency f1 of the first resonance mode and the resonance frequency f2 of the second resonance mode. Thus, in the typical compressor, if the resonance frequency f1 of the first resonance mode fluctuates, the resonance frequencies of the two resonance modes are likely to match each other.
If as shown in
In this embodiment, as described above, the size of the casing (20) or the muffler (38) is set so that the resonance frequency f1 of the first resonance mode is different from the resonance frequency f2 of the second resonance mode in the entire range of the first resonance mode, and thus the two resonance modes do not overlap each other.
Specifically, in the compressor (10) of the first embodiment, the size of the casing (20) or the muffler (38) is determined so that as shown in
When operating at a high speed (e.g., where the rotational speed N (rps) during a steady operation is 120≤N), a compressor undergoes an oil loss such that there is significant change in the oil level reached by the amount of oil initially supplied. Thus the compressor (10) that do not allow the two resonance modes to overlap each other is more useful in one preferred embodiment. In other words, a typical compressor operating at a high speed causes the oil level to lower, thereby allowing the two resonance modes to overlap each other, but the compressor of this embodiment do not allow them to overlap each other even when the oil level lowers, thereby easily operating at a high speed.
The compressor (10) operating at a high speed tends to allow the casing (20) to discharge a larger amount of oil so that the oil level lowers. In addition, if the casing (20) is downsized and has a smaller diameter, the oil level significantly fluctuates as the amount of oil changes. Thus, typically, the resonance frequency of the first resonance mode and the resonance frequency of the second resonance mode are likely to match each other.
In this embodiment, the size and shape of the casing (20) or the muffler (38) are set so that the resonance frequency of the first resonance mode is different from the resonance frequency of the second resonance mode. Accordingly, even if the oil level fluctuates, the resonance frequencies of the two resonance modes do not match each other. Thus, noise increase caused by the two resonance modes overlapping each other can be reduced. In addition, even if the oil level easily fluctuates by the compressor (10) being downsized and operated at a high speed, the two resonance modes do not overlap each other, and thus noise increase can be reduced. This embodiment has a great advantage in reducing the noise even if the compressor is not downsized and operated at a high speed.
According to a compressor of a first variation, the sizes and shapes of parts such as a diameter of a discharge opening of a muffler, the number of discharge openings of the muffler, an area of the discharge opening of the muffler, a plate thickness of the muffler, a volume of a muffler space (38a), an inner diameter of a barrel (21), a volume of a primary space (60), and the like are determined so that with no lubricant oil being stored in a casing (20), a resonance frequency of the first resonance mode is higher than a resonance frequency of the second resonance mode, as shown in
A second embodiment will be described below.
The second embodiment relates to an air conditioner including a refrigerant circuit (1). Similarly to the above descriptions, a compressor (10) of the air conditioner includes: a casing (20) having a cylindrical shape and including end plates (22, 23) at both ends; a compression mechanism (30) housed in a casing (20); and a muffler (38) disposed between a fluid outlet (32b) of the compression mechanism (30) and a space in the casing (20). The compressor (10) has a first resonance mode where the resonance frequency changes as the oil level of lubricant oil stored in the casing (20) changes and a second resonance mode where the resonance frequency does not change as the oil level of lubricant oil stored in the casing (20) changes.
In the air conditioner, the amount of oil and the length of pipe in the refrigerant circuit (1) are determined so that the resonance frequency of the first resonance mode is lower than the resonance frequency of the second resonance mode at the oil level at which lubricant oil in the refrigerant circuit (1) is collected in the compressor (10). In the second embodiment, the sizes of the casing (20) and the muffler (38) of the compressor (10) are not necessarily set so that the resonance frequency of the first resonance mode is different from the resonance frequency of the second resonance mode, but the use of the compressor of the first embodiment is not excluded.
Also in the second embodiment, the resonance frequency f1 of the first resonance mode is lower than the resonance frequency f2 of the second resonance mode when the oil level of lubricant oil is at the highest one, and thus similarly to the example shown in
Similarly to the second embodiment, an air conditioner of a first variation includes a refrigerant circuit (1) including a compressor having a first resonance mode and a second resonance mode.
The air conditioner operates to control the oil level of a compressor (10) so that the resonance frequency of the first resonance mode is lower than the resonance frequency of the second resonance mode at all times during a steady operation in the entire operation range.
Specifically, as shown in
The compressor (10) is provided with an oil level gauge (not shown) for detecting the oil level. The oil return circuit (6) includes an oil separator (7) connected to the discharge side of the compressor (10) and includes an oil return pipe (7a) connected to a suction pipe (37a) provided between an accumulator (37) and the compressor (10). The oil return pipe (7a) is provided with an oil return valve (7b). The oil return valve (7b) may be an on-off valve adjustable between two positions, i.e., a fully closed position and a fully open position, or may be an opening degree control valve adjustable to any opening degree.
In the oil return operation, the rotational speed of the compressor (10) is increased to increase the amount of refrigerant circulated, and the oil return valve (7b) is opened to collect the oil in the refrigerant circuit (1). As the rotational speed of the compressor (10) increases, the amount of oil loss (the amount of oil flowing out of the compressor (10)) increases, and thus, in general, the rotational speed is set to a medium speed in order to reduce the oil loss. In addition, as the differential pressure in the refrigerant circuit increases, the amount of oil loss increases, and thus, in general, the oil return operation is performed with a low load (low differential pressure).
If the oil level gauge detects that the oil level of the compressor (10) lowers, the oil return operation is performed at a medium speed with a low load in order to secure the oil level. Accordingly, the oil level rises. In contrast, an operation at a high speed with a high differential pressure causes increase in the amount of oil loss, and thus an operation at a high speed with a high differential pressure is performed in order to decrease the oil level.
In the first variation, an operation is performed as described above to control the oil level of the compressor (10) so that the resonance frequency f1 of the first resonance mode is lower than the resonance frequency f2 of the second resonance mode at all times. Thus, the resonance frequencies f1 and f2 of the two resonance modes do not match each other at any point, and thus noise increase caused by the resonance frequencies of the two resonance modes overlapping each other can be reduced.
Similarly to the second embodiment and the first variation thereof, an air conditioner of a second variation includes a refrigerant circuit (1) including a compressor having a first resonance mode and a second resonance mode.
Unlike the first variation, the air conditioner operates to control the oil level of a compressor (10) so that the resonance frequency of the first resonance mode is higher than the resonance frequency of the second resonance mode at all times during a steady operation in the entire operation range.
Also in the second variation, the resonance frequencies f1 and f2 of the two resonance modes do not match each other at any point, and thus similarly to the first variation, noise increase caused by the resonance frequencies of the two resonance modes overlapping each other can be reduced.
Similarly to the second embodiment and the first and second variations thereof, an air conditioner of a third variation includes a refrigerant circuit (1) including a compressor having a first resonance mode and a second resonance mode.
The air conditioner operates to control the rotational speed of the compressor (10) to avoid a point at which the resonance frequencies f1 and f2 of the first resonance mode and the second resonance mode match each other, thereby controlling the resonance frequency of the first resonance mode. In other words, the air conditioner operates to adjust the rotational speed of the compressor (10) in order to adjust the oil level so that the resonance frequency f1 of the first resonance mode do not match the resonance frequency f2 of the second resonance mode. The operation of adjusting the oil level in the second embodiment can be performed by avoiding an operation of the compressor (10) and not performing a steady operation at a point at which the resonance frequencies of the first resonance mode and the second resonance mode match each other.
Also in the third variation, the resonance frequencies f1 and f2 of the two resonance modes do not match each other at any point, and thus similarly to the first and second variations, noise increase caused by the resonance frequencies of the two resonance modes overlapping each other can be reduced.
The above embodiments may be modified as follows.
For example, the above embodiments assume that the compressor (10) is downsized and rotated at a high speed, but the configuration of the present disclosure is useful in reducing the noise not only when a compressor is downsized and rotated at a high speed but also when a compressor in a typical size is rotated at a normal speed, when a compressor in a normal size is rotated at a high speed, and when a compressor in a still smaller size is rotated at a normal speed. The numerical values in the embodiments are not limited to themselves.
While the embodiments and variations thereof have been described above, it will be understood that various changes in form and details may be made without departing from the spirit and scope of the claims. The elements according to the embodiments, the variations thereof, and the other embodiments may be combined and replaced with each other.
As described above, the present disclosure is useful for a compressor and an air conditioner.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2022-059440 | Mar 2022 | JP | national |
This is a continuation of International Application No. PCT/JP2023/011559 filed on Mar. 23, 2023, which claims priority to Japanese Patent Application No. 2022-059440, filed on Mar. 31, 2022. The entire disclosures of these applications are incorporated by reference herein.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2023/011559 | Mar 2023 | WO |
| Child | 18812744 | US |
