JP2011027043A - Positive-displacement compressor and refrigeration cycle device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a positive-displacement compressor ingeniously using a supercharging effect by resonance. <P>SOLUTION: This compressor 20 includes: a motor 2 controlling rotational speed; a controller 42 driving the motor 2 at the rotational speed within a range from a predetermined minimum rotational speed to a predetermined maximum rotational speed; a positive displacement compression mechanism 3 operated by the motor 2 in order to compress working fluid; an accumulator 12 keeping the working fluid to be sucked into the compression mechanism 3; and a suction path 14 (typically, a suction pipe) introducing the working fluid from the accumulator 12 to the compression mechanism 3. The suction pipe 14 has an inlet part 14a positioned inside of the accumulator 12 and an outlet part 14b connected to the compression mechanism 3. Length L from the inlet part 14a to the outlet part 14b is adjusted so that the resonance based on the pressure pulsation of the working fluid is produced when the controller 42 drives the motor 2 at the maximum rotational speed. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a positive displacement compressor and a refrigeration cycle apparatus using the positive displacement compressor.

  A positive displacement compressor such as a rotary compressor or a scroll compressor is used in the vapor compression refrigeration cycle apparatus. The positive displacement compressor is often provided with an accumulator (or a suction muffler) in order to prevent liquid refrigerant from being sucked. The refrigerant is supplied from the accumulator to the working chamber (compression chamber) through the suction pipe.

  As a technology for improving the volumetric efficiency of positive displacement compressors, a technology that resonates the pressure pulsation of the refrigerant generated with the change in the volume of the working chamber in the suction pipe, thereby obtaining a supercharging effect (so-called resonance supercharging technology) Has been studied. In this technique, the length of the suction pipe is adjusted so that resonance occurs in the suction pipe when the compressor is operated at a predetermined rotation speed (frequency). Since there is a design limitation on the length of the suction tube, resonance usually occurs only at a single rotational speed. Therefore, in order to obtain a sufficient supercharging effect, it is necessary to examine in detail the relationship between the rotation speed of the compressor and the length of the suction pipe.

  For example, Patent Document 1 describes a supercharged rotary compressor in which the length of a suction pipe is adjusted so that resonance occurs at a rotational speed that is 1500 to 2000 rpm (revolutions per minute) lower than the maximum rotational speed. .

Japanese Patent No. 2501337

  By the way, the efficiency of the refrigeration cycle apparatus strongly depends on the efficiency of the motor as well as the volumetric efficiency of the compressor. FIG. 10 shows a typical efficiency curve of an IPMSM (Interior Permanent Magnet Synchronous Motor) widely used in a compressor. The IPMSM normally exhibits the highest efficiency at a certain rotation speed Np. It would be ideal if the compressor could be operated at this rotational speed Np. However, the most frequently used rotational speed Nh is often lower than the rotational speed Np. In order to improve the APF (Annual Performance Factor) of the refrigeration cycle apparatus, it is desired to use a motor that exhibits high efficiency at the rotational speed Nh. In short, it is preferable that the rotation speed Np matches the rotation speed Nh.

  If cost and dimensional problems are ignored, it may be possible to manufacture a motor having a small difference between the rotational speed Np and the rotational speed Nh and high efficiency. Specifically, an electrical steel sheet having a low iron loss so as to reduce the copper loss by thickening the copper wire so that the rotational speed Np shifts to the low rotational speed side and to secure the torque in the high rotational speed region. The method to use can be considered. However, electrical steel sheets with low iron loss are very expensive, and this method inevitably increases costs. There is a method of increasing torque by increasing the diameter of the motor instead of using an expensive electromagnetic steel sheet, but a motor for a compressor always has dimensional restrictions, and this cannot be ignored. Furthermore, since it is premised that the maximum revolving speed Nmax can be operated because of the demand for the maximum capacity of the refrigeration cycle apparatus, the torque in the high revolving speed region cannot be sacrificed. If only the rotation speed Np is brought close to the rotation speed Nh without reexamination of dimensions and materials, the motor efficiency itself is greatly lowered or the flatness of the efficiency curve is lost. In this case, the APF of the refrigeration cycle apparatus may even decrease rather than improve.

  On the other hand, an attempt to adjust the length of the suction pipe so that resonance occurs at the rotation speed Nh can be considered. However, in the vapor compression refrigeration cycle apparatus, the rotation speed Nh is often relatively low at about 1500 rpm. In order to cause resonance at such a low rotational speed, it is necessary to lengthen the suction pipe considerably, but this newly introduces a problem of the size of the compressor.

  In view of such circumstances, an object of the present invention is to provide a positive displacement compressor that skillfully utilizes a supercharging effect due to resonance, and a refrigeration cycle apparatus using the positive displacement compressor.

That is, the present invention
A motor capable of controlling the rotation speed;
A controller that drives the motor at a rotational speed ranging from a predetermined minimum rotational speed to a predetermined maximum rotational speed;
A positive displacement compression mechanism moved by the motor to compress the working fluid;
An accumulator for holding the working fluid to be sucked into the compression mechanism;
An inlet portion located in the accumulator; and an outlet portion connected to a suction hole of the compression mechanism; and when the controller is driving the motor at the maximum rotational speed, A suction path for guiding the working fluid from the accumulator to the compression mechanism, wherein a length from the inlet to the outlet is adjusted so that resonance based on pressure pulsation occurs;
A positive displacement compressor is provided.

In another aspect, the present invention provides:
The positive displacement compressor of the present invention;
A radiator for cooling the working fluid compressed by the positive displacement compressor;
An inflating portion for inflating the working fluid radiated by the radiator;
An evaporator for evaporating the working fluid expanded in the expansion section;
A refrigeration cycle apparatus is provided.

  According to the compressor of the present invention, the length of the suction path is adjusted so that resonance occurs when operating at the maximum rotational speed. That is, the maximum supercharging effect can be obtained at the maximum rotational speed. Therefore, when the compressor of the present invention is used in a refrigeration cycle apparatus, the maximum capacity equivalent to that when a conventional compressor is used can be secured at a maximum speed lower than the maximum speed of a conventional compressor. Since the required maximum capacity can be secured at a low rotational speed, the variable range of the rotational speed of the motor can be narrowed. That is, the degree of freedom in motor design increases.

  For example, to avoid the increase in size and cost, and limit the maximum number of rotations to achieve the highest efficiency (peak of the efficiency curve) closer to the most frequently used number of rotations. Is allowed. A motor designed under such a concept can exhibit an efficiency higher than that of a conventional motor at the most frequently used rotational speed. According to the present invention, since such a motor can be used for the compressor, the APF of the refrigeration cycle apparatus is also improved. In addition, when it is allowed to limit the maximum number of revolutions as compared with the prior art, it is easy to optimize the shape and dimensions of the motor. As a result, the compressor may be downsized.

The longitudinal cross-sectional view of the rotary compressor which concerns on 1st Embodiment of this invention. 1 is a cross-sectional view taken along line AA of the rotary compressor shown in FIG. Side view of the rotary compressor shown in FIG. Top view of the rotary compressor shown in FIG. Graph showing the relationship between compressor speed and volumetric efficiency Graph showing the relationship between motor speed and efficiency A longitudinal sectional view of a rotary compressor according to a second embodiment of the present invention. A longitudinal sectional view of a rotary compressor according to a third embodiment of the present invention. Configuration diagram of a refrigeration cycle apparatus using the compressor of the present embodiment Typical efficiency curve of IPMSM

(First embodiment)
As shown in FIG. 1, the rotary compressor 20 of this embodiment includes a compressor body 40, an accumulator 12, a suction pipe 14, a discharge pipe 11, and a controller 42.

  The compressor main body 40 includes a sealed container 1, a compression mechanism 3, a motor 2, and a shaft 4. The compression mechanism 3 is disposed below the sealed container 1. The motor 2 is disposed above the compression mechanism 3 in the sealed container 1. The compression mechanism 3 and the motor 2 are connected by the shaft 4. A terminal 21 for supplying electric power to the motor 4 is provided on the top of the sealed container 1. An oil sump 22 for holding lubricating oil is formed at the bottom of the sealed container 1.

  The discharge pipe 11 penetrates the upper part of the sealed container 1 and is open inside the sealed container 1. The discharge pipe 11 serves as a discharge path that guides the compressed working fluid to the outside of the compressor body 40. The suction pipe 14 passes through the trunk of the sealed container 1 and is connected to the compression mechanism 3. The suction pipe 14 serves as a suction path that guides the working fluid from the accumulator 12 to the compression mechanism 3.

  Specifically, the suction pipe 14 has an inlet portion 14 a (first opening portion) opened inside the accumulator 12 and an outlet portion 14 b (second opening portion) connected to the compression mechanism 3. The length L from the inlet portion 14a to the outlet portion 14b is adjusted so that resonance based on the pressure pulsation of the working fluid occurs when the controller 42 is driving the motor 2 at the maximum rotation speed.

  The compression mechanism 3 is a positive displacement fluid mechanism and is moved by the motor 2 so as to compress the working fluid. As shown in FIGS. 1 and 2, the compression mechanism 3 includes a cylinder 5, a piston 8, a vane 10, an upper bearing 6, a lower bearing 7, and a muffler 9. Inside the cylinder 5, a piston 8 fitted to the eccentric part 4 a of the shaft 4 is arranged. A vane groove 24 is formed in the cylinder 5. The vane groove 24 accommodates the vane 10 having a tip in contact with the outer peripheral surface of the piston 8. The upper bearing 6 and the lower bearing 7 are respectively provided on the upper side and the lower side of the cylinder 5 so as to close the cylinder 5. The cylinder 5, the piston 8, the upper bearing 6 and the lower bearing 7 form a space for sucking and compressing the working fluid. The space is partitioned by the vane 10, thereby forming the suction chamber 25 and the compression chamber 26. The muffler 9 is provided on the upper bearing 6. The muffler 9 is formed with a discharge hole 9 a for guiding the compressed working fluid into the sealed container 1. The shaft 4 passes through the center portions of the upper bearing 6, the lower bearing 7 and the muffler 9.

  In the present embodiment, the position of the outlet portion 14 b of the suction pipe 14 matches the position of the suction hole 29 of the compression mechanism 3. However, the outlet portion 14 b may be separated from the suction hole 29. A portion from the outlet portion 14 b to the suction hole 29 can be formed by the cylinder 5. In this case, the sum of the length of the portion formed by the cylinder 5 and the length of the suction pipe 14 corresponds to the entire length of the suction path.

  The motor 2 includes a stator 17 and a rotor 18. The stator 17 is fixed to the inner peripheral surface of the sealed container 1. The rotor 18 is fixed to the shaft 4 and rotates together with the shaft 4. As the motor 2, for example, a motor capable of controlling the rotation speed such as IPMSM or SPMSM (Surface Permanent Magnet Synchronous Mortar) can be used.

  The controller 42 adjusts the rotation speed of the motor 2, that is, the rotation speed of the compressor 20 through the control of the inverter 44. As the controller 42, a DSP (Digital Signal Processor) including an A / D conversion circuit, an input / output circuit, an arithmetic circuit, a storage device, and the like can be used. The controller 42 drives the motor 2 at a rotational speed in a range from a predetermined minimum rotational speed Nm to a predetermined maximum rotational speed Nsc. For example, in the range of 800-5500 rpm, the rotation speed of the motor 2 can be changed in increments of 60 rpm. The maximum rotation speed Nsc is usually determined according to the maximum capacity of the refrigeration cycle apparatus to which the compressor 20 is applied. Similarly, the minimum rotation speed Nm is also determined according to the ability that the refrigeration cycle apparatus should exhibit.

  The accumulator 12 includes a storage container 23, a baffle plate 15, and an introduction pipe 16. The suction pipe 14 is connected to the accumulator 12 so as to penetrate the bottom of the storage container 23. The introduction pipe 16 passes through the upper part of the storage container 23 and is open inside the storage container 23. The baffle plate 15 is provided in the accumulation container 23 and separates the suction pipe 14 and the introduction pipe 16 in the accumulation container 23. The suction pipe 14 and the introduction pipe 16 are opened below and above the baffle plate 15, respectively. In the storage container 23, the lower surface of the baffle plate 15 and the inlet portion 14 a of the suction pipe 14 face each other so that a gap having a predetermined width is formed between the baffle plate 15 and the inlet portion 14 a of the suction pipe 14. ing. Similarly, in the accumulation container 23, the upper surface of the baffle plate 15 and the outlet portion 16 a of the introduction pipe 16 are formed so that a gap having a predetermined width is formed between the baffle plate 15 and the outlet portion 16 a of the introduction pipe 16. Are facing each other. The baffle plate 15 has a through hole 15p formed in the outer peripheral portion thereof so that the working fluid guided to the accumulator 12 through the introduction pipe 16 can move from the space above the baffle plate 15 to the space below. The plate-like member provided at the lower part in the accumulation container 23 is for suppressing the liquid-phase working fluid accumulated in the accumulation container 23 from rising.

  As shown in FIGS. 3 and 4, the suction pipe 14 includes a portion 14 p that is curved along the outer peripheral surface of the sealed container 1 outside the sealed container 1 and the accumulator 12. In this embodiment, since the sealed container 1 has a cylindrical shape, the curved portion 14p is along the circumferential direction of the sealed container 1. According to this configuration, the accumulator 12 can be disposed near the compressor body 40 even if the length of the suction pipe 14 is increased as compared with the conventional case in order to obtain a supercharging effect due to resonance. This is preferable from the viewpoint of reducing the installation area of the compressor 20.

  Next, the operation of the compressor 20 will be described. The working fluid is guided into the accumulator 12 through the introduction pipe 16 and is temporarily held in the storage container 23. Since the baffle plate 15 is provided between the introduction pipe 16 and the suction pipe 14, the working fluid cannot move directly from the introduction pipe 16 to the suction pipe 14. The working fluid moves from the upper space in the accumulator 12 to the lower space through the through hole 15p formed in the baffle plate 15. When the working fluid is in a liquid phase or a gas-liquid two-phase state, the liquid phase working fluid is stored at the bottom of the accumulation container 23. Only the gas phase working fluid is guided to the suction chamber 25 of the compression mechanism 3 through the suction pipe 14.

  As shown in FIG. 2, as the piston 8 rotates, the volumes of the suction chamber 25 and the compression chamber 26 change. Specifically, the volume of the suction chamber 25 gradually increases according to the rotation of the piston 8, and the working fluid is sucked from the suction pipe 14 into the suction chamber 25 through the suction hole 29. On the other hand, the volume of the compression chamber 26 gradually decreases, whereby the working fluid in the compression chamber 26 is compressed. The compressed working fluid is guided from the compression chamber 26 to the inside of the muffler 9 through the discharge hole 27, and further discharged from the discharge hole 9 a of the muffler 9 to the internal space 28 of the sealed container 1 near the lower part of the motor 2. Is done.

  The working fluid flows upward in the internal space 28 of the sealed container 1. At this time, since the working fluid forms a swirling flow according to the rotation of the rotor 18, centrifugal force acts on the lubricating oil mixed with the working fluid, and the lubricating oil can be separated from the working fluid. The separated lubricating oil adheres to the inner peripheral surface of the sealed container 1 or falls downward due to gravity, and returns to the oil reservoir 22. The working fluid is guided to the outside of the sealed container 1 through the discharge pipe 11.

In the present embodiment, the suction pipe 14 has a length L (unit: m) represented by the following formula (1). Note that the speed of sound in the suction pipe 14 filled with the working fluid to be compressed is a _s (unit: m / sec), the rotational speed of the motor 2 is f (unit: rpm), and the equivalent pipe length of the suction chamber 25 is _Is C _t (unit: m), and the opening end correction of the suction pipe 14 is C _k (unit: m). The “equivalent pipe length C _t of the suction chamber 25” is the apparent length of the suction chamber 25, and is a value obtained by dividing the maximum volume of the suction chamber 25 (the volume when the suction is completed) by the cross-sectional area of the suction pipe 14. expressed. Further, as the distance from the inlet portion 14a of the suction pipe 14 to the baffle plate 15 becomes longer, the opening end correction C _k also increases, whereby the suction pipe 14 can be shortened.

_{L = [60 × a s (} 2m-1) / 4f] -C t -C k (m is a positive integer) (1)

  When the working fluid is sucked into the compression mechanism 3, pressure pulsation is generated as the volume of the suction chamber 25 changes. The pressure pulsation propagates through the suction pipe 14 and is reflected by the inlet portion 14 a to return to the suction chamber 25. When the suction pipe 14 has a length L that satisfies the above formula (1), the pressure pulsation of the working fluid and the pressure wave propagating through the suction pipe 14 cause resonance. The positive part of the amplified pressure wave is confined in the suction chamber 25, which increases the volumetric efficiency, ie a supercharging effect.

For example, in a compressor for an air conditioner having a heating or refrigeration capacity of about 2 to 3 kW, in order to obtain a supercharging effect due to resonance, R410a is used as a working fluid, a _s = 170 (m / s), f = 3600 (rpm), C _t = 0.1 (m), and C _k = 0.01 (m), L≈0.60 (m).

  FIG. 5 shows the relationship between the rotational speed and the volumetric efficiency in each of the compressor of the present embodiment and the conventional compressor (those that do not perform supercharging by resonance). The volumetric efficiency of conventional compressors only changes slightly with increasing rotational speed. This change is mainly due to changes in flow loss and leakage loss. On the other hand, according to the compressor 20 of the present embodiment, the volume efficiency equivalent to that of the conventional compressor is shown in the rotational speed range excluding the vicinity of the resonance rotational speed Nsc, but in the vicinity of the resonant rotational speed Nsc. Soars. That is, the compressor 20 of the present embodiment shows a volumetric efficiency curve having the resonance rotation speed Nsc as a peak. Note that the maximum rotation speed of the compressor 20 of the present embodiment is equal to the resonance rotation speed Nsc. Therefore, the compressor 20 is not operated at a rotational speed higher than the resonant rotational speed Nsc.

  Next, the characteristics of the motor 2 used in the compressor 20 will be described. FIG. 6 is a graph showing the relationship between the rotational speed and efficiency of two types of motors. One shows the efficiency curve of the motor used in the conventional compressor, and the other shows the efficiency curve of the motor 2 used in the compressor 20 of this embodiment. The rotation speeds Np and Np ′ at which each motor exhibits the maximum efficiency are determined according to various factors such as the material, dimensions, output, and variable range of the rotation speed. The most frequently used rotation speed Nh throughout the year depends on the specifications of the refrigeration cycle apparatus, which is the main application of the compressor.

  For example, it is assumed that a compressor using a conventional motor is operated in a range from the minimum rotation speed Nm to the maximum rotation speed Nmax. The most frequently used rotational speed Nh exists on the lower rotational speed side than the rotational speed Np that exhibits the highest efficiency. Although the frequency of operation at the maximum rotation speed Nmax is not necessarily high, it is indispensable to ensure the heating capacity (including the defrosting capacity) of the refrigeration cycle apparatus that the operation at the maximum rotation speed Nmax is possible. For example, it is necessary to operate at the maximum number of rotations Nmax when the outside air temperature in winter is very low or when defrosting operation is required. As described above, since there is a restriction on the maximum number of rotations Nmax, in the conventional compressor, the difference between the number of rotations Np at which the motor exhibits the highest efficiency and the number of rotations Nh that is used most frequently tends to be large. .

  On the other hand, according to the compressor 20 of the present embodiment, the length L of the suction pipe 14 is adjusted so that the supercharging effect by resonance is obtained at the maximum rotational speed Nsc. That is, the refrigeration cycle apparatus exhibits the maximum capacity at the maximum rotation speed Nsc. Although the maximum rotation speed Nsc is lower than the maximum rotation speed Nmax, taking into account the supercharging effect, the ability that the refrigeration cycle apparatus exhibits when the compressor 20 of the present embodiment is operating at the maximum rotation speed Nsc is: This is approximately equal to the ability of the refrigeration cycle apparatus when the conventional compressor is operating at the maximum rotational speed Nmax. That is, if resonance occurs at the maximum rotation speed Nsc, the difference (500 rpm) between the rotation speed Nmax (for example, 6000 rpm) and the rotation speed Nsc (for example, 5500 rpm) can be compensated by the supercharging effect. In order to ensure the maximum capacity of the refrigeration cycle device, supercharging by resonance can be used.

  As a result, since operation at a higher rotational speed than the maximum rotational speed Nsc becomes unnecessary, the motor 2 improved so as to exhibit the maximum efficiency at the rotational speed Np ′ can be used for the compressor 20. That is, the rotation speed Np ′ that exhibits the highest efficiency can be brought close to the rotation frequency Nh that is used most frequently, while avoiding an increase in size and cost. There is a difference ΔE between the efficiency of the improved motor 2 at the rotational speed Nh and the efficiency of the conventional motor at the rotational speed Nh. According to the compressor 20 including the motor 2 that exhibits high efficiency at the most frequently used rotational speed Nh, the APF of the refrigeration cycle apparatus can be improved.

(Second Embodiment)
FIG. 7 is a longitudinal sectional view of a rotary compressor according to the second embodiment of the present invention. In addition, the same reference number is attached | subjected to the component which is the same as or respond | corresponds to 1st Embodiment, and description is abbreviate | omitted.

  As shown in FIG. 7, the compressor 50 according to the present embodiment includes a suction pipe 32 including a coiled portion 32 c as a suction path connecting the accumulator 12 and the compressor body 40. The coil-shaped portion 32 c is located in the accumulator 12, specifically in the storage container 23. In this way, since the suction pipe 32 can be stored in the storage container 23 in a compact manner, the compressor 50 can be downsized. Similar to the first embodiment, the inlet portion 32 a of the suction pipe 32 faces the baffle plate 15. The outlet portion 32 b of the suction pipe 32 is connected to the compression mechanism 3 so as to supply the working fluid to the suction chamber 25.

  Generally, the working fluid in the suction pipe of the compressor has a temperature slightly higher than the outside air temperature. On the other hand, the temperature around the compressor during operation is higher than the outside air temperature due to the radiant heat from the compressor. For this reason, the working fluid in the suction pipe may have a temperature lower than the temperature around the compressor. In this case, the working fluid receives heat from the surroundings in the suction pipe. When the working fluid receives heat in the suction pipe, the density of the working fluid sucked into the compression mechanism decreases. As a result, the weight of the working fluid that can be compressed by the compressor is reduced, and as a result, the heating / refrigeration capacity of the refrigeration cycle apparatus is reduced.

  If the suction pipe is lengthened in order to obtain a supercharging effect due to resonance, the amount of heat received by the working fluid in the suction pipe may increase. However, according to the present embodiment, the suction pipe 32 has the coiled portion 32 c, and the coiled portion 32 c is located in the storage container 23. That is, most of the suction pipe 32 (for example, ½ or more of the entire length) is located in the accumulator 12. Since the accumulator 12 is filled with a low-temperature working fluid, the working fluid in the suction pipe 32 can be prevented from receiving heat from the surroundings. That is, the amount of heat received by the working fluid in the suction pipe 32 can be maintained at a level equivalent to that of a conventional compressor. As a result, the benefits described in the first embodiment can be enjoyed while avoiding the disadvantages due to the increase in the length of the suction pipe 32.

  Further, according to the coiled portion 32c, the suction pipe 32 can be made compact, so that an increase in the size of the storage container 23 can be avoided. Furthermore, according to the present embodiment, when the installation surface of the compressor 50 is parallel to the horizontal direction, the coiled portion 32c extends in the vertical direction. By winding the suction pipe 32 in a coil shape along the vertical direction, the lubricating oil of the compressor 50 circulating in the refrigerant circuit can be prevented from being trapped in the suction pipe 32.

(Third embodiment)
FIG. 8 is a longitudinal sectional view of a rotary compressor according to the third embodiment of the present invention. As shown in FIG. 8, the compressor 70 according to the present embodiment includes a suction pipe 33 including a U-shaped portion 33 u as a suction path connecting the accumulator 12 and the compressor body 40. The U-shaped portion 33 u is located in the accumulator 12, specifically in the storage container 23. According to this embodiment, the same effect as that of the second embodiment can be obtained.

  In the present embodiment, the outlet 33b of the suction pipe 33 is connected to the compression mechanism 3 so as to supply the working fluid to the suction chamber 25 as in the first and second embodiments. On the other hand, the inlet 33 a of the suction pipe 33 does not face the baffle plate 15. Specifically, the inlet portion 33a faces downward. That is, the suction pipe 33 is opened vertically downward in the accumulator 12. According to such a configuration, regardless of the presence or absence of the baffle plate 15, the gas-liquid two-phase working fluid guided to the accumulator 12 through the introduction pipe 16 does not flow directly into the suction pipe 33, and the liquid-phase operation is performed. The fluid can be prevented from being sucked into the compression mechanism 3.

  Further, in the present embodiment, the U-shaped portion 33u is formed only at one location of the suction pipe 33, and the inlet portion 33a forming the tip of the U-shaped portion 33u faces downward in the vertical direction. Yes. Therefore, lubricating oil does not accumulate in the U-shaped portion 33u.

  As described above, in each embodiment, the single-stage rotary compressors 20, 50, and 70 have been described. However, the present invention is not limited to a single-stage rotary compressor, but a two-stage rotary compressor, a scroll compressor, a reciprocating compressor, and the like. Can be widely applied to other positive displacement compressors.

(Embodiment of refrigeration cycle apparatus)
As shown in FIG. 9, the refrigeration cycle apparatus 100 of the present embodiment includes the compressor 20 described in the first embodiment, the radiator 102 that cools the working fluid compressed by the compressor 20, and the radiator 102. An expansion unit 104 that expands the dissipated working fluid and an evaporator 106 that evaporates the working fluid expanded by the expansion unit 104 are provided. A bypass circuit 108, a valve 110, and a valve 112 are provided so that high-temperature and high-pressure refrigerant can flow through the evaporator 106 to remove frost attached to the evaporator 106. A refrigerant such as carbon dioxide or hydrofluorocarbon can be used as the working fluid. The expansion unit 104 is typically an expansion valve, but a positive displacement expander can also be used so that expansion energy can be recovered from the refrigerant. In place of the compressor 20, the compressors 50 and 70 described in the second and third embodiments can also be suitably used.

  The controller 42 of the compressor 20 is also used for overall control of the refrigeration cycle apparatus 100, specifically, control of the expansion unit 104. When the controller 42 is driving the motor 2 at the maximum rotation speed Nsc (see FIG. 6), the refrigeration cycle apparatus 100 exhibits the maximum cooling capacity and / or maximum heating capacity in design. Further, the controller 42 drives the motor 2 at the maximum rotation speed Nsc (see FIG. 6) when performing a defrost operation for removing frost adhering to the evaporator 106. In the defrost operation, the valves 110 and 112 are operated so that the refrigerant compressed by the compressor 20 bypasses the radiator 102 and is guided to the expansion unit 104 and the evaporator 106.

  The compressor of the present invention has great utility value in a refrigeration cycle apparatus that constitutes equipment such as an air conditioner, a water heater, and a refrigerator.

DESCRIPTION OF SYMBOLS 1 Airtight container 2 Motor 3 Compression mechanism 12 Accumulator 14, 32, 33 Suction pipe 14a, 32a, 33a Inlet part 14b, 32b, 33b Outlet part 15 Baffle plate 16 Introducing pipe 20, 50, 70 Compressor 23 Accumulation container 32c Coil shape Portion 33u U-shaped portion 40 Compressor body 42 Controller 44 Inverter 100 Refrigeration cycle apparatus 102 Radiator 104 Expansion section 106 Evaporator

Claims (9)

A motor capable of controlling the rotation speed;
A controller that drives the motor at a rotational speed ranging from a predetermined minimum rotational speed to a predetermined maximum rotational speed;
A positive displacement compression mechanism moved by the motor to compress the working fluid;
An accumulator for holding the working fluid to be sucked into the compression mechanism;
An inlet portion located in the accumulator; and an outlet portion connected to a suction hole of the compression mechanism; and when the controller is driving the motor at the maximum rotational speed, A suction path for guiding the working fluid from the accumulator to the compression mechanism, wherein a length from the inlet to the outlet is adjusted so that resonance based on pressure pulsation occurs;
A positive displacement compressor. Further comprising a sealed container containing the motor and the compression mechanism;
The positive displacement compressor according to claim 1, wherein the suction path includes a portion curved along an outer peripheral surface of the hermetic container outside the hermetic container and the accumulator.   The positive displacement compressor according to claim 1 or 2, wherein the suction path includes a coiled portion, and the coiled portion is located in the accumulator.   The positive displacement compressor according to claim 3, wherein when the installation surface of the positive displacement compressor is parallel to the horizontal direction, the coiled portion extends in the vertical direction.   The positive displacement compressor according to claim 1 or 2, wherein the suction path includes a U-shaped portion, and the U-shaped portion is located in the accumulator. The accumulator has a storage container for temporarily holding the working fluid, and a baffle plate provided in the storage container;
In the storage container, the baffle plate and the inlet portion of the suction path face each other so that a gap having a predetermined width is formed between the baffle plate and the inlet portion of the suction path. The positive displacement compressor according to any one of claims 1 to 4. The positive displacement compressor according to any one of claims 1 to 6,
A radiator for cooling the working fluid compressed by the positive displacement compressor;
An inflating portion for inflating the working fluid radiated by the radiator;
An evaporator for evaporating the working fluid expanded in the expansion section;
A refrigeration cycle apparatus comprising:   The refrigeration cycle apparatus according to claim 7, wherein a maximum cooling capacity and / or maximum heating capacity in design is exhibited at the maximum rotation speed of the motor.   The refrigeration cycle apparatus according to claim 7 or 8, wherein the controller drives the motor at the maximum rotational speed when performing a defrost operation for removing frost attached to the evaporator.

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