JP4265229B2 - Rotary compressor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a rotary compressor, and particularly relates to a rotary compressor having a double casing structure including an outer casing and an inner casing, and a compression mechanism and an electric motor housed inside the inner casing.
[0002]
[Prior art]
Conventionally, rotary compressors have been used to compress refrigerant in a refrigerant circuit that performs, for example, a vapor compression refrigeration cycle. In this rotary compressor, there is a type in which a casing has a double structure including an outer casing and an inner casing, and a compression mechanism and an electric motor are housed inside the inner casing (see, for example, Patent Document 1).
[0003]
As shown in FIG. 8, in the compressor (1), the inner casing (16) is elastically held inside the outer casing (11), and the compression mechanism (30) is placed inside the inner casing (16). And an electric motor (40) for driving the compression mechanism (30). Further, there is a gap between the outer casing (11) and the inner casing (16), and a space (S1) is formed.
[0004]
The suction pipe (27) for introducing the refrigerant into the compression mechanism (30) includes a first suction pipe (27a) that penetrates the outer casing (11), and a second suction pipe (27b) that penetrates the inner casing (16). The refrigerant is introduced into the space (S1) between the outer casing (11) and the inner casing (16) through the first suction pipe (27a) and then compressed through the second suction pipe (27b). Inhaled into mechanism (30). The discharge pipe (28) passes through the inner casing (16) and the outer casing (11), and the refrigerant discharged from the compression mechanism (30) fills the space (S2) in the inner casing (16). After that, it is discharged out of the machine through the discharge pipe (28).
[0005]
[Patent Document 1]
Japanese Patent Laid-Open No. 3-96693 [0006]
[Problems to be solved by the invention]
By the way, in the rotary compressor (1) having a double casing structure, when the inner casing (16) vibrates with the operation of the electric motor (40), the inner casing (16) contacts the outer casing (11), There is a risk that vibration and contact noise of the inner casing (16) may leak out of the compressor (1). In particular, when the compressor (1) is started or stopped, there is a problem that vibrations having a low frequency and a large amplitude are generated, and vibration sounds and contact sounds are likely to be generated.
[0007]
As a countermeasure, if the gap between the inner casing (16) and the outer casing (11) is increased, it is possible to avoid contact between both casings (11, 16), but the compressor (1) itself becomes larger. It will be. Moreover, even if the gap is slightly increased, it is difficult to sufficiently reduce the sound.
[0008]
The present invention was devised in view of such problems, and its purpose is to suppress the generation of sound during operation and to increase the size of the compressor in a rotary compressor having a double casing structure. It is to be able to prevent.
[0009]
[Means for Solving the Problems]
The present invention relates to a rotary compressor having a double casing (10) structure, wherein the electric motor (40) is driven to a variable speed by driving an inverter (50), and the wall thickness of the inner casing (16) is changed to that of the outer casing (11). It is thicker than the wall thickness.
[0010]
Specifically, the invention described in claim 1 includes an outer casing (11) and an inner casing (16) elastically held in the outer casing (11), and the inner casing (16) includes the inner casing (16). It is premised on a rotary compressor that houses a compression mechanism (30) and an electric motor (40) that drives the compression mechanism (30).
[0011]
The rotary compressor according to claim 1 includes an inverter (50) for driving the electric motor (40) at a variable speed, and the natural frequency of the inner casing (16) is greater than the natural frequency of the outer casing (11). It is also characterized by being large.
[0012]
In the invention of claim 1, and more to increase the thickness of the inner casing (16), it is possible to increase the natural frequency of the inner casing (16). Further, if the natural frequency of the inner casing (16) is made larger than that of the outer casing (11), low frequency sound can be absorbed in the inner casing (16). As a result, the sound (vibration) radiated from the inner casing (16) is closer to the high frequency range, but the vibration absorption rate in the high frequency range is almost the same regardless of the wall thickness. Even if the wall thickness is thin, the high frequency sound can be absorbed.
[0013]
In addition, when using an electric motor (40) driven by an inverter (50), the frequency range of the sound that should be cut off with the variable speed drive is widened, whereas the sound in the low frequency range is absorbed by the inner casing (16). In addition, by absorbing the sound in the high frequency range with the outer casing (11), it is possible to efficiently insulate the sound.
[0014]
The invention according to claim 2 is the rotary compressor according to claim 1 , wherein the rotor (42) of the electric motor (40) is an embedded magnet type rotor (42). It is said.
[0015]
In the invention of claim 2 , since the embedded magnet type rotor (42) is used, the distance between the inner peripheral surface of the stator (41) and the magnet (42b) is longer than that of the surface magnet type. The vibration of the stator (41) due to the attractive force and repulsive force acting on the stator (41) and the rotor (42) is reduced. Therefore, sound can be suppressed efficiently.
[0016]
According to a third aspect of the present invention, in the rotary compressor according to the first or second aspect , the maximum value of the rotational speed of the electric motor (40) is set to 180 rotations or more per second. It is a feature. The upper limit value may be determined as appropriate within the possible range of operation.
[0017]
In the invention of claim 3 , by specifying the rotational speed of the electric motor (40) in the compressor of the double casing (10) to the above value, the compressor casing (10) is rotated by the single casing (10). It can be accommodated in a size equal to or smaller than the case where the speed is about 60 (S ⁻¹ ) (see FIG. 5). Further, when the rotational speed is increased in this way, a high-frequency sound is likely to be generated, but the high-frequency sound can be reduced relatively easily even if the outer casing (11) is thin.
[0018]
According to a fourth aspect of the present invention, in the rotary compressor according to the first, second, or third aspect of the invention, the electric motor (40) is accelerated at a rate of 5 revolutions per second or less at startup. It is characterized by being composed. In particular, it is preferable to accelerate the motor (40) at a rate of 2 revolutions per second or less at the time of startup.
[0019]
In the invention of claim 4 , since the electric motor (40) is gradually accelerated at the time of starting, there is little impact during starting and vibration of the inner casing (16) is reduced. Therefore, even if the gap between the inner casing (16) and the outer casing (11) is reduced, the inner casing (16) does not contact the outer casing (11), so that sound can be suppressed even if the casing (10) is small.
[0020]
The invention according to claim 5 is the rotary compressor according to any one of claims 1 to 4 , wherein the suction pipe (27) for introducing the refrigerant into the compression mechanism (30) includes an outer casing (11). ) Through the first suction pipe (27a) and the second suction pipe (27b) through the inner casing (16), and the discharge pipe (28) for discharging the refrigerant from the compression mechanism (30) The inner casing (16) and the outer casing (11) are penetrated, and a suction space (S1) is formed between the inner casing (16) and the outer casing (11), and the inner casing (16) A discharge space (S2) is formed in the interior of the apparatus.
[0021]
In the invention of claim 5 , the refrigerant is introduced into the suction space (S1) between the outer casing (11) and the inner casing (16) via the first suction pipe (27a), and then the second suction pipe ( 27b) through the compression mechanism (30). The high-pressure refrigerant discharged from the compression mechanism (30) flows out from the discharge space (S2) in the inner casing (16) through the discharge pipe (28) to the outside.
[0022]
In this configuration, the discharge space (S2) inside the inner casing (16) is high because it is filled with the discharged refrigerant, but the suction space (S1) between the outer casing (11) and the inner casing (16). ) Is filled with the suction refrigerant that has returned from the refrigerant circuit to the compressor (1), and therefore has a lower pressure (but higher than atmospheric pressure). Therefore, the pressure difference between the inside and outside of the inner casing (16) (pressure difference between the suction pressure and the discharge pressure) and the pressure difference between the inside and outside of the outer casing (11) (the pressure difference between the atmospheric pressure and the suction pressure) are the single casing. Thus, the pressure difference between the inside and outside of the casing (pressure difference between the atmospheric pressure and the discharge pressure) when the internal space becomes high pressure becomes smaller.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0024]
The present embodiment relates to a rotary compressor that performs a compression stroke in a refrigerant circuit of a vapor compression refrigeration cycle. As shown in FIG. 1 which is a cross-sectional structure diagram, the rotary compressor (1) includes a double-structure casing (10) including an outer casing (11) and an inner casing (16). Housed in the inner casing (16) are a compression mechanism (30) and an electric motor (40) that drives the compression mechanism (30).
[0025]
The outer casing (11) has a vertically long cylindrical outer body (12), an outer upper end plate (13) fixed to the upper end of the outer body (12), and a lower end of the outer body (12). And an outer lower end plate (14). The outer upper end plate (13) and the outer lower end plate (14) are each airtightly joined to the outer body portion (12) by welding. The outer lower end plate (14) is integrally formed with a leg (15) for installing the rotary compressor (1).
[0026]
The inner casing (16) has a vertically long cylindrical shape and is fixed to the inner trunk (17) having a smaller diameter and a shorter length than the outer trunk (12) and the upper end of the inner trunk (17). An inner upper end plate (18) and an inner lower end plate (19) fixed to the lower end of the inner trunk portion (17) are provided. The inner upper end plate (18) and the inner lower end plate (19) are each airtightly joined to the inner body portion (17) by welding.
[0027]
The inner casing (16) is formed of a plate material having a thickness dimension larger than that of the outer casing (11). In this regard, for example, when comparing the average thicknesses of the body parts (12, 17), the inner casing (16) is thicker than the outer casing (11). The thinnest part of the inner casing (16) need not be thicker than the thickest part of the outer casing (11). By doing so, the natural frequency of the inner casing (16) becomes larger than the natural frequency of the outer casing (11).
[0028]
Between the outer casing (11) and the inner casing (16), as will be described later, a space that is filled with the suction refrigerant during operation (hereinafter referred to as suction space (S1)) is defined. The inner casing (16) is elastically held in the outer casing (11). For this reason, the outer casing (11) is slightly on the outer lower end plate (14) slightly inward in the radial direction from the inner peripheral surface of the outer body (12) than the lower end of the outer body (12). An annular holding portion (25) located above is provided. The holding portion (25) is provided with an elastic holding mechanism (20) that holds the inner casing (16). The elastic holding mechanism (20) includes a base plate (21) fixed to the holding portion (25), a coil spring (22) having a lower end fixed on the base plate (21), and an upper end of the coil spring (22). Holding plate (23). The holding plate (23) is formed by pressing a circular plate, and the flat peripheral edge is fixed to the coil spring (22), while the central part is a curved surface along the inner lower end plate (19). And fixed to the inner lower end plate (19). The elastic holding mechanism (20) may be configured to use rubber or a leaf spring instead of the coil spring (22).
[0029]
The suction pipe (27) for introducing the refrigerant into the compression mechanism (30) includes a first suction pipe (27a) fixed to the outer upper end plate (13) and a second suction pipe fixed to the inner trunk portion (17). (27b). Then, the refrigerant flows into the suction space (S1) from the first suction pipe (27a), and further sucked into the compression mechanism (30) in the inner casing (16) through the second suction pipe (27b). On the other hand, the refrigerant discharge pipe (28) passes through the inner casing (16) and the outer casing (11). The discharge pipe (28) constitutes a passage for guiding the discharged refrigerant discharged from the compression mechanism (30) and filling the space in the inner casing (16) (hereinafter referred to as discharge space (S2)) to the outside of the machine. ing. The discharge pipe (28) has an intermediate portion formed in a spiral shape, and the spiral portion allows the vibration of the inner casing (16).
[0030]
A brushless DC motor is used for the electric motor (40). As shown in FIG. 1 and FIG. 2 which is a cross-sectional view taken along the line II-II of FIG. 1, the electric motor (40) is a cylindrical stator fixed at a position near the upper end of the inner trunk (17). 41), a rotor (42) rotatably mounted in the stator (41), and a rotating shaft (43) connected to the rotor (42) at the center of rotation. The stator (41) is composed of a stator core (41a) in which electromagnetic steel sheets punched by press working are laminated, and a coil (41b) mounted on the stator core (41a). On the other hand, the rotor (42) is composed of a rotor core (42a) in which electromagnetic steel plates punched by pressing are laminated, and a permanent magnet (42b) embedded in the rotor core (42a). ing.
[0031]
The stator (41) of the electric motor (40) employs a concentrated winding (direct winding) method as a winding method of the coil (41b). In the example shown in the figure, six teeth (T) are provided at equal intervals on the stator core (41a), and coils (41b) are individually wound around each of them. The stator (41) has a three-phase winding structure, and is arranged so that the coils (41b) having the same phase face each other. In addition, four permanent magnets (42b) are embedded in the rotor (42) at equal intervals. The rotor (42) is formed with a magnetic barrier space (B) extending radially outward from both ends of each magnet (42b).
[0032]
The compression mechanism (30) is a rolling piston type compression mechanism. The compression mechanism (30) includes a cylinder (31), a front head (32), a rear head (33), and a rotary piston (34), and the cylinder (31) is located on the lower side in the inner casing (16). Fixed in position. The cylinder (31) is formed in a thick cylindrical shape, and is disposed on the same center line as the electric motor (40). The cylinder (31), the front head (32), and the rear head (33) are integrally assembled by fastening with bolts (not shown), etc., and the front head (32) is mounted on the lower end surface of the cylinder (31). A rear head (33) is provided. An annular compression chamber (C) is defined between the inner peripheral surface of the cylinder (31), the lower end surface of the front head (32), and the upper end surface of the rear head (33).
[0033]
The rotating shaft (43) of the electric motor (40) passes through the compression chamber (C) in the vertical direction on the center line of the inner casing (16). In order to support the rotating shaft (43), the front head (32) and the rear head (33) are respectively provided with bearing portions (32a, 32b) on which sliding bearings are mounted.
[0034]
The rotation shaft (43) has a portion located in the compression chamber (C) that is decentered by a predetermined amount from the rotation center of the rotation shaft (43), and has an eccentric portion (43a) having a larger diameter than the upper and lower portions thereof. It is configured. The rotating piston (34) of the compression mechanism (30) is fixed to the eccentric portion (43a). The rotating piston (34) has an annular shape, and its outer peripheral surface is substantially in contact with the inner peripheral surface of the cylinder (31) at one point during operation (actually a slight clearance is provided). Has been.
[0035]
On the other hand, as shown in FIG. 3 which is a sectional view taken along line III-III in FIG. 1, the cylinder (31) is formed with a blade groove (35) penetrating in the axial direction of the cylinder (31). A blade (36) formed in a rectangular plate shape is mounted in the groove (35) so as to be slidable in the radial direction in the blade groove (35). The blade (36) is urged radially inward by a spring (37), and the rotation of the rotary shaft (43) is maintained while maintaining the state where the tip is always in pressure contact with the outer peripheral surface of the rotary piston (34). Accordingly, the blade groove (35) is configured to advance and retreat.
[0036]
The blade (36) partitions the compression chamber (C) between the inner peripheral surface of the cylinder (31) and the outer peripheral surface of the rotary piston (34) into a low pressure chamber (C1) and a high pressure chamber (C2). ing. The second suction pipe (27b) penetrates the inner body part (17) and the cylinder (31) in the radial direction, and communicates with the suction space (S1) and the low pressure chamber (C1). On the other hand, as indicated by a virtual line in FIG. 3, the front head (32) has a discharge port (29) that penetrates in the vertical direction of FIG. A discharge valve (29a) that is formed and opens and closes the discharge port (29) is provided. The discharge valve (29a) opens the discharge port (29) when the pressure difference between the pressure in the compression chamber (C) (high pressure chamber (C2)) and the pressure in the discharge space (S2) becomes larger than a predetermined value. It is configured as follows. Therefore, when the pressure difference becomes larger than a predetermined value, the high-pressure refrigerant in the compression chamber (C) is discharged into the discharge space (S2) in the inner casing (16) and filled therein, and then the discharge pipe Flow out of the machine via (28).
[0037]
As described above, the discharge space (S2) inside the inner casing (16) becomes high pressure because it is filled with the discharged refrigerant, but the suction space (S1) between the outer casing (11) and the inner casing (16). ) Is filled with the suction refrigerant that has returned from the refrigerant circuit to the compressor (1), and therefore has a lower pressure (but higher than atmospheric pressure). Therefore, the pressure difference between the inside and outside of the inner casing (16) (pressure difference between the suction pressure and the discharge pressure) and the pressure difference between the inside and outside of the outer casing (11) (the pressure difference between the atmospheric pressure and the suction pressure) are the single casing. Thus, the pressure difference between the inside and outside of the casing (pressure difference between the atmospheric pressure and the discharge pressure) when the internal space becomes high pressure becomes smaller. Therefore, in the present embodiment, the thicknesses of the outer casing (11) and the inner casing (16) can be made smaller than in the case of a single casing.
[0038]
On the other hand, the inner terminal (46) is fixed to the inner casing (16), and the outer terminal (47) is fixed to the outer casing (11). The electric motor (40) is connected to the inner end of a terminal pin provided on the inner terminal (46) via a lead wire (48a). An inverter module (50) is mounted on the outer end of the terminal pin. The inverter module (50) is obtained by covering a circuit unit body composed of a circuit board and circuit components such as switching elements by resin molding.
[0039]
Since the resin material used as the outer shell of the inverter module (50) is required not to react with refrigerant or refrigerating machine oil, LCP (liquid crystal polymer), PPS (polyphenylene sulfide), PBT (polybutylene terephthalate) or the like is used. Is preferred. The inverter module (50) is preferably not only inserted into the terminal pin of the inner terminal (46) but also provided with an auxiliary fixing means to prevent it from coming off. For example, a configuration in which claws that engage with each other are provided on both the inner terminal (46) and the inverter module (50) can be considered.
[0040]
This inverter module (50) is electrically connected to the terminal (46) by being inserted into the terminal pin of the inner terminal (46), and the lead wire (48b) drawn from the resin molded portion is connected to the outer terminal (47). Is electrically connected to the outer terminal (47). An external power supply wiring is connected to the outer terminal (47), and a power supply voltage is applied to the electric motor (40) via the inverter module (50).
[0041]
In the inverter module (50), as shown in FIG. 4, which is a sectional view taken along the line IV-IV in FIG. 1, a slit (51) is formed in a portion through which the discharge pipe (28) passes. The slit (51) is formed wider than the diameter of the discharge pipe (28) so that the discharge pipe (28) and the inverter module (50) do not contact each other. Thus, a gap is provided between the inner surface of the slit (51) and the outer surface of the discharge pipe (28).
[0042]
In this embodiment, since the operation control using the inverter is performed as described above, the operation frequency of the electric motor (40) can be changed by changing the pulse width of the switching pulse in the PWM control (pulse width control). Is possible. For this reason, the rotational speed of the electric motor (40) can be freely selected and operated within a predetermined range. Therefore, the operation capacity of the compressor (1) can be controlled.
[0043]
Further, since the variable speed drive is performed by the inverter, the electric motor (40) is compared with the induction motor (40) whose rotational speed is fixed around 50 (S ^-1 ) or 60 (S ^-1 ). Thus, it is possible to operate at a higher rotational speed. When the rotation speed is increased, it is possible to increase the instantaneous cooling / heating capacity in an air conditioner, for example.
[0044]
Furthermore, if the inverter is configured to perform variable speed driving, it is possible to reduce the size of the compressor (1) by increasing the rotational speed while reducing the refrigerant compression amount per rotation. That is, the compressor (1) can be downsized by rotating the electric motor (40) at high speed.
[0045]
In particular, as shown in the graph of FIG. 5, the general relationship between the rotational speed and the outer diameter of the compressor (1) is based on a compressor having a single casing (10) and a rotational speed of 60 (S ⁻¹ ). Then, at the same rotational speed, the rotational speed is increased to about 180 (S ⁻¹ ) or more with the compressor (1) of the double casing (10) whose outer diameter is about 1.2 times that of the single casing (10). Thus, it can be seen that even the double casing compressor (1) can be made smaller than the standard compressor. In this regard, if the compressor (1) has a capacity in the range from about 700 W to about 5 KW, it can be considered that this tendency is almost the same.
[0046]
Further, the use of the embedded magnet type rotor (42) also contributes to an increase in the rotational speed of the electric motor (40). In other words, in this type of motor (40), not only the magnet torque but also the reluctance torque can be used effectively by operating the current phase appropriately beyond the induced voltage. In addition, it is possible to operate in a high-speed rotation region by performing flux-weakening control with a more advanced current phase. Therefore, the use of the embedded magnet type rotor (42) also contributes to the downsizing of the compressor (1) for the same reason as described above.
[0047]
On the other hand, simply rotating the motor (40) at a high speed and downsizing the compressor (1) causes a problem with the sound generated by the operation, but in this embodiment, the generation of sound is suppressed as follows. .
[0048]
First, in the compressor (1), since the inner casing (16) is elastically held inside the outer casing (11), for example, in a configuration without inverter control, large vibrations are generated during startup and acceleration. Then, the inner casing (16) may come into contact with the outer casing (11) to generate sound. In contrast, since the compressor (1) is driven by an inverter, the acceleration speed can be adjusted. In particular, if the control to reduce the acceleration speed is performed, the vibration of the inner casing (16) can be suppressed, so that the inner casing (16) is less likely to contact the outer casing (11), and the casing (10) does not have to be enlarged. The problem of vibration sound and contact sound can be avoided. In this case, it is preferable to set a moderate acceleration so that the motor (40) accelerates at a rate of 5 revolutions per second or less, preferably 2 revolutions or less.
[0049]
Here, the sound generated by the inverter-driven electric motor (40) includes the sound of the carrier frequency component of PWM control (usually about 2 KHz to 10 KHz, often about 3 KHz to 5 KHz), the rotation speed in addition to the mechanical sound as described above. There is a sound with a frequency proportional to an integer multiple of. In particular, in the case of a three-phase motor, a sound that is six times the excitation frequency is remarkable. For example, in the case of a quadrupole type used in a normal compressor, the sound has a frequency about 12 times the rotational speed.
[0050]
Then, when the rotational speed is 180 (S ⁻¹ ), the above frequency is 180 × 12 = 2160 Hz. Such high frequency sound exceeding 2 kHz can be cut off relatively easily by the outer casing (11). In addition, the sound of low frequency makes the inner casing (16) thicker than the outer casing (11), and the natural frequency of the inner casing (16) is higher than the natural frequency of the outer casing (11). It can be reduced by increasing the size.
[0051]
This is because, as shown in the graph of FIG. 6, the transmission loss of high-frequency sound hardly changes even when the thickness (natural frequency) of the casing changes, whereas the transmission loss of low-frequency sound. Is different depending on the thickness, and the thicker (the higher the natural frequency), the larger the transmission loss, in other words, the higher the absorption rate. In this case, in order to sufficiently increase the low-frequency sound absorption rate in the inner casing (16) than in the outer casing (11), the natural frequency of the inner casing (16) is set to the natural frequency of the outer casing (11). √2 times or more is better. By doing so, the vibration attenuation rate becomes 1 or less, and the adverse effect that the casings (11, 16) resonate can be avoided, so that a sufficient sound insulation effect can be exhibited.
[0052]
-Driving action-
Next, the operation of the rotary compressor (1) will be described.
[0053]
First, in the electric motor (40), the rotor (42) rotates by passing a three-phase alternating current through the coil (41b) of the stator (41). Specifically, a rotating magnetic field is generated by passing an alternating current rectified by the inverter through the coil (41b), and the rotor (42) is rotated by the action of the rotating magnetic field and the permanent magnet (42b).
[0054]
When the rotor (42) rotates, the rotating shaft (43) integrated with the rotor (42) also rotates. Therefore, in the compression mechanism (30), the rotary piston (34) turns on a predetermined orbit while maintaining a state in which it is substantially inscribed in the inner peripheral surface of the cylinder (31). As a result, the volume of the compression chamber (C) repeatedly increases and decreases, and the refrigerant suction, compression, and discharge processes are repeatedly performed in the compression mechanism (30).
[0055]
When the compression mechanism (30) operates, the refrigerant is temporarily introduced from the first suction pipe (27a) into the suction space (S1) and then sucked into the compression mechanism (30) via the second suction pipe (27b). . The refrigerant becomes high pressure as the volume of the compression chamber (C) decreases. When the pressure in the compression chamber (C) becomes larger than the pressure in the inner casing (16) by a predetermined value or more, the discharge valve of the compression mechanism (30) opens, and the refrigerant flows from the compression chamber (C) to the inner casing ( 16) It flows out. The refrigerant fills the inner casing (16) and then is discharged out of the compressor (1) through the discharge pipe (28).
[0056]
-Effect of the embodiment-
According to this embodiment, the natural frequency of the inner casing (16) is increased by making the inner casing (16) thicker than the outer casing (11). Therefore, low frequency sound can be absorbed and reduced in the inner casing (16).
[0057]
On the other hand, if high-speed rotation is performed in the inverter-driven electric motor (40), the generated sound includes many high frequencies, and the inner casing (16) absorbs low-frequency sound. The radiated sound becomes closer to high frequencies. However, since the transmission loss of sound in the high frequency range is almost the same even if the wall thickness is different, the low frequency sound can be absorbed even if the outer casing (11) is thin. Therefore, since the outer casing (11) can be thinned, the compressor (1) can be reduced in weight and can be reduced in size. It should be noted that the outer casing (11) can be thinned because the differential pressure between the suction space (S1) and the space outside the machine is small.
[0058]
In the above embodiment, the rotor (42) of the electric motor (40) is an embedded magnet type rotor (42). When an embedded magnet type rotor (42) is used, when the rotational speed is increased, the vibration force transmitted to the inner casing (16) increases due to the deformation vibration of the stator (41), and more noise reduction is required. On the other hand, the vibration of the stator (41) can be reduced by suppressing the attractive force and the repulsive force between the stator (41) and the rotor (42). Therefore, the silent effect can be enhanced. In addition, since the inverter (50) is used, the frequency of the sound to be cut off is increased by extending the operating range, but the noise reduction effect can be enhanced.
[0059]
In addition, the use of a magnet-embedded rotor (42) enables high-speed and high-efficiency operation by flux-weakening control, and because the motor (40) is highly efficient, the motor (40) generates less heat and the compressor efficiency Contributes to improvement. Further, since the motor (40) generates little heat, it contributes to cooling of the inverter (50).
[0060]
Moreover, since the maximum value of the rotational speed of the electric motor (40) is 180 (S- ¹ ) or more, the compressor (1) can be downsized as described above. Further, since the electric motor (40) is configured to accelerate at a rate of 5 revolutions per second or less at the time of startup, vibration at the time of startup is reduced, and the inner casing (16) and the outer casing (11). The generation of sound can be prevented even if the compressor (1) is made smaller by reducing the gap.
[0061]
Also, the space between the outer casing (11) and the inner casing (16) is the suction space (S1), and the space in the inner casing (16) is the discharge space (S2), so the inner casing (16) The pressure difference between the inside and outside and the pressure difference between the inside and outside of the outer casing (11) can be made smaller than the pressure difference between the inside and outside of the casing in the single casing. For this reason, the thickness of the inner casing (16) and the outer casing (11) can be reduced, and the compressor (1) can be reduced in size and weight.
[0062]
Other Embodiments of the Invention
The present invention may be configured as follows with respect to the above embodiment.
[0063]
For example, in the above embodiment, the first suction pipe (27a) is fixed to the outer upper end plate (13) and is arranged in the vicinity of the inverter module (50). As shown in FIG. 7, you may fix to an outer trunk | drum (12). In the example of this figure, the first suction pipe (27a) is not placed close to the inverter module (50) but is arranged near the inner lower end plate (19).
[0064]
If comprised in this way, the distance of a 1st suction pipe (27a) and a 2nd suction pipe (27b) will become near rather than embodiment. Accordingly, since the refrigerant is efficiently sucked into the compression mechanism (30), an efficient operation can be performed.
[0065]
In the above embodiment, the example in which the present invention is applied to the rolling piston type rotary compressor (1) has been described. However, the present invention is not limited to other types such as a swing piston type (swing type) or a scroll type. You may apply to this rotary compressor.
[0066]
Further, in the above embodiment, the inverter module (50) in which the circuit board and circuit components of the inverter are covered with resin molding is inserted into the inner terminal (46), so that the position is fixed. It is also possible to use an inverter that does not cover the circuit parts with resin molding. In that case, for example, the circuit board of the inverter can be configured to be fixed to the inner casing (16) or the outer casing (11) with screws or the like in the suction space (S1).
[0067]
Further, in the above embodiment, the suction space (S1) filled with the suction refrigerant is formed between the outer casing (11) and the inner casing (16), and the inner casing (16) is filled with the discharge refrigerant. Although the space (S2) is formed, this is not necessarily a requirement and can be changed depending on circumstances.
[0068]
【The invention's effect】
According to the invention described in claim 1, since the natural frequency of the inner casing (16) is made larger than the natural frequency of the outer casing (11 ), low frequency sound is absorbed in the inner casing (16). In addition, sound leakage to the outside of the machine can be reduced. Also, since the low frequency sound is absorbed in the inner casing (16), the sound radiated from the inner casing (16) shifts closer to the high frequency range, but the vibration absorption rate in the high frequency range is the inner casing (16). And the outer casing (11) are almost the same, so the high frequency sound can be absorbed. And since an outer casing (11) can be made thin, size reduction and weight reduction are also possible .
[0069]
According to the second aspect of the present invention, since the rotor (42) of the electric motor (40) is an embedded magnet type rotor (42), the stator (41 ) Is easy to vibrate, and more noise reduction is required, while efficient noise reduction can be realized. In addition, if this embedded magnet type rotor (42) is used, not only magnet torque but also reluctance torque can be used, enabling high-speed and high-efficiency operation and miniaturization of the compressor (1). Become.
[0070]
According to the invention of claim 3 , the casing (10) of the compressor (1) has a double structure by setting the maximum value of the rotational speed of the electric motor (40) to 180 (S- ¹ ) or more. In spite of this, the size can be reduced to the same size as when the rotational speed is about 60 (S ⁻¹ ) with a single casing. In addition, when the rotational speed is increased, high frequency sound is generated, but high frequency sound can be absorbed sufficiently even if the outer casing (11) is thin, and low frequency sound is less likely to be generated. The generation of sound can be suppressed.
[0071]
According to the fourth aspect of the invention, since the rate of acceleration of the electric motor (40) at the time of starting is specified, the shock during the starting is reduced, and the vibration of the inner casing (16) is reduced. Therefore, even if the clearance between the inner casing (16) and the outer casing (11) is reduced to reduce the size of the compressor (1), the generation of sound can be suppressed.
[0072]
According to the invention described in claim 5 , since the inside casing (16) is a high pressure space and the space between the inside casing (16) and the outside casing (11) is a low pressure space, Both the pressure difference between the space inside and outside (16) and the pressure difference between the space inside and outside the outer casing (11) can be reduced. Therefore, the thickness of the compressor (1) can be reduced by reducing the thickness of the inner casing (16) and the outer casing (11).
[Brief description of the drawings]
FIG. 1 is a sectional structural view of a rotary compressor according to an embodiment of the present invention.
2 is a cross-sectional view taken along the line II-II in FIG. 1. FIG. 3 is a cross-sectional view taken along the line III-III in FIG.
4 is a cross-sectional view taken along line IV-IV in FIG.
FIG. 5 is a graph showing a general relationship between the rotational speed and the outer diameter of the compressor.
FIG. 6 is a graph showing the relationship between sound transmission loss and frequency in a casing.
FIG. 7 is a cross-sectional structure diagram of a rotary compressor according to a modification of the embodiment.
FIG. 8 is a sectional structural view of a conventional rotary compressor.
[Explanation of symbols]
(1) Rotary compressor
(10) Casing
(11) Outer casing
(16) Inner casing
(20) Elastic holding mechanism
(27) Suction pipe
(27a) First suction pipe
(27b) Second suction pipe
(28) Discharge pipe
(30) Compression mechanism
(40) Electric motor
(41) Stator
(42) Rotor
(43) Rotating shaft
(46) Inner terminal
(47) Outside terminal
(50) Inverter module
(51) Slit
(S1) Suction space
(S2) Discharge space

Claims (5)

An outer casing (11) and an inner casing (16) elastically held in the outer casing (11) are provided, and the compression mechanism (30) and the compression mechanism (30) are provided in the inner casing (16). A rotary compressor in which a driving electric motor (40) is housed,
It has an inverter (50) that drives the electric motor (40) at a variable speed,
The rotary compressor characterized in that the natural frequency of the inner casing (16) is larger than the natural frequency of the outer casing (11) . The rotary compressor according to claim 1, wherein
The rotor of the electric motor (40) (42), a rotary compressor which is a embedded magnet type rotor (42). The rotary compressor according to claim 1 or 2,
The rotary compressor characterized in that the maximum value of the rotation speed of the electric motor (40) is set to 180 rotations or more per second . The rotary compressor according to claim 1, 2, or 3,
A rotary compressor characterized in that the electric motor (40) is configured to accelerate at a rate of not more than 5 revolutions per second at startup . The rotary compressor according to any one of claims 1 to 4,
Suction pipe for introducing the refrigerant into the compression mechanism (30) (27), first suction pipe passing through the outer casing (11) and (27a), a second suction pipe passing through the inner casing (16) and (27b) Consists of
A discharge pipe (28) for discharging refrigerant from the compression mechanism (30) passes through the inner casing (16) and the outer casing (11) ,
A rotary type characterized in that a suction space (S1) is formed between the inner casing (16) and the outer casing (11) , and a discharge space (S2) is formed inside the inner casing (16). Compressor.

Images