Refrigeration cycle device

Abstract

This refrigeration cycle device comprises: a compressor having a shell which has a low-pressure structure and in which a motor is installed in a low-pressure atmosphere; an oil separator; a condenser; a decompressor; and an evaporator. The compressor, the oil separator, the condenser, the decompressor, and the evaporator are connected by piping, and a refrigerant circulates therein. The refrigeration cycle device further comprises: an oil reservoir container having an upper part to which oil return piping for introducing oil separated by the oil separator is connected; and an oil return liquid pipe having one end part connected to the lower part of the oil reservoir container and the other end part in communication with an oil storage part formed at the bottom part of the compressor. The lower part of the oil reservoir container is disposed at a position higher than the other end part of the oil return liquid pipe in the shell of the compressor.

Description

Refrigeration Cycle Device

[0001] The present disclosure relates to a refrigeration cycle device, and particularly to a refrigeration cycle device including a low-pressure shell type compressor.

[0002] A refrigeration cycle device is filled with refrigerating machine oil for maintaining the reliability of a compressor having a sliding portion such as a rotary compressor, a scroll compressor, or a screw compressor. In refrigeration cycle devices, technologies for improving reliability through oil management and technologies for improving energy saving efficiency through oil flow control have been proposed.

[0003] For example, a technology is known in which an oil drain pipe is provided at the bottom of a compressor and connected to a discharge pipe to control so that no more than a predetermined amount of oil accumulates inside the compressor. Another known technology provides an oil phase pipe for returning oil separated by an oil separator at the bottom of the compressor, and returns the oil using the height difference between the oil separator and the compressor.

[0004] The above-described technologies relate to high-pressure shell type compressors, that is, compressors having a shell with a high-pressure structure, and cannot be directly applied to low-pressure shell type compressors. On the other hand, Patent Document 1 discloses a configuration in which a partition plate is provided inside an oil separator, the upper part is a high-pressure space connected to a discharge pipe in the refrigeration cycle device, the lower part is a low-pressure space connected to a low-pressure part of the compressor, and the upper part and the lower part of the oil separator are connected by a capillary tube.

[0005] Japanese Unexamined Patent Publication No. 2005-164056

[0006] According to Patent Document 1, even with a low-pressure shell type compressor, a sufficient amount of oil in the compressor can be secured. However, when the amount of oil in the compressor increases, there is a possibility that the oil level rises to the rotating part. When the oil level rises to the rotating part, the oil is agitated by the rotating part, which may cause problems such as an increase in electrical input. As described above, sufficient countermeasures have not been taken for the case where the amount of oil in the compressor exceeds an appropriate amount.

[0007] An object of the present disclosure is to provide a refrigeration cycle device that can appropriately maintain the oil amount of a low-pressure shell type compressor.

[0008] The refrigeration cycle apparatus according to this disclosure comprises a compressor having a low-pressure structure shell in which a motor is installed in a low-pressure atmosphere, an oil separator, a condenser, a pressure reducing device, and an evaporator, wherein the compressor, the oil separator, the condenser, the pressure reducing device, and the evaporator are connected by piping and a refrigerant circulates, further comprising an oil reservoir container to which an oil return pipe for receiving oil separated by the oil separator is connected at the top, and a return oil liquid pipe having one end connected to the bottom of the oil reservoir container and the other end connected to an oil storage section formed at the bottom of the compressor, wherein the bottom of the oil reservoir container is positioned higher than the other end of the return oil liquid pipe in the shell of the compressor.

[0009] According to the refrigeration cycle device described herein, the lower part of the oil reservoir is positioned higher than the height of the return oil pipe of the oil reservoir in the compressor. Therefore, when the oil level in the oil storage section rises above the appropriate oil level, the oil moves to the oil reservoir, maintaining the appropriate oil level.

[0010] This is a circuit diagram of a refrigeration cycle device according to Embodiment 1. This is a schematic diagram illustrating the position of the oil reservoir container in the refrigeration cycle device according to Embodiment 1. This is a schematic cross-sectional view of the compressor in the refrigeration cycle device according to Embodiment 1. This is a circuit diagram of a refrigeration cycle device according to Modification 1-1 of Embodiment 1. This is a circuit diagram of a refrigeration cycle device according to Modification 1-2 of Embodiment 1. This is a circuit diagram of a refrigeration cycle device according to Modification 1-3 of Embodiment 1. This is a schematic cross-sectional view of the oil reservoir container in the refrigeration cycle device according to Modification 1-4 of Embodiment 1. This is a circuit diagram of a refrigeration cycle device according to Embodiment 2. This is a circuit diagram of a refrigeration cycle device according to Embodiment 3. This is a circuit diagram of a refrigeration cycle device according to Embodiment 4. This is a circuit diagram of a refrigeration cycle device according to Embodiment 5.

[0011] The embodiments for implementing this disclosure will be described with reference to the attached drawings. In each drawing, the same or corresponding parts are denoted by the same reference numerals, and redundant explanations are simplified or omitted as appropriate. In the following description, for convenience, the positional relationships of each structure may be expressed based on the illustrated state. This disclosure is not limited to the following embodiments, and any combination of embodiments, any modification of any component of each embodiment, or any omission of any component of each embodiment is possible without departing from the spirit of this disclosure. In addition, the dimensional relationships or shapes of each component in each drawing may differ from those of the actual components. Furthermore, the positional relationships between each component, such as the top-down relationship, are, in principle, as they are when installed in a usable state. However, in order to facilitate understanding, terms indicating direction, such as "up," "down," "right," "left," "front," and "back," will be used as appropriate, but these notations are merely for the convenience of explanation and do not limit the arrangement and orientation of the device or parts.

[0012] Embodiment 1. Figure 1 is a circuit diagram of a refrigeration cycle device 100 according to Embodiment 1. As shown in Figure 1, the refrigeration cycle device 100 includes a compressor 10, an oil separator 11, a condenser 12, a pressure reducing device 13, and an evaporator 14. The compressor 10, the oil separator 11, the condenser 12, the pressure reducing device 13, and the evaporator 14 are connected in a ring by piping 100a, forming a main circuit R. Refrigerant flows through piping 100a and circulates through the main circuit R.

[0013] An accumulator 15 is connected between the evaporator 14 and the compressor 10. The refrigeration cycle device 100 also includes an oil reservoir container 16.

[0014] The refrigeration cycle device 100 may be, for example, a household air conditioner or a multi-split air conditioner for buildings, in which case the main circuit R may be equipped with a four-way valve that switches the direction of refrigerant flow. A multi-split air conditioner for buildings is an air conditioner configured in which a number of indoor units, each equipped with a user-side heat exchanger that functions as a condenser 12 or evaporator 14, are connected to the main circuit R.

[0015] [Compressor 10] The compressor 10 compresses a low-temperature and low-pressure refrigerant to produce a high-temperature and high-pressure gaseous refrigerant. Since the compressor 10 has sliding parts, it is sealed with refrigerant oil to lubricate the sliding parts. Note that refrigerant oil is sometimes simply referred to as oil.

[0016] The compressor 10 has a low-pressure shell 110 in which the motor 101 is placed in a low-pressure atmosphere L. The shell 110 is, for example, cylindrical in shape with the vertical direction as its axial direction, and houses the motor 101 and the compression mechanism 102 inside. The motor 101 consists of a stator 101a fixed to the inner wall of the shell 110 and a rotor 101b slidably arranged on the inner circumference side of the stator 101a.

[0017] The compression mechanism 102 is located above the motor 101. The compression mechanism 102 draws in refrigerant and compresses it using the rotational force generated by the motor 101, which is transmitted via a crankshaft 103 extending axially from the compressor 10, and then discharges it from the compression mechanism 102. The discharged refrigerant creates a high-pressure atmosphere H above the compression mechanism 102.

[0018] An oil passage is formed in the crankshaft 103 that penetrates axially, and an oil pump 103a is provided at the lower end of the oil passage. The oil pump 103a is provided to draw up oil from the oil reservoir 104 formed at the bottom of the shell 110 and supply oil to each sliding part of the compressor 10. The oil supplied to each sliding part of the compressor 10 is discharged into the main circuit R together with high-temperature and high-pressure gaseous refrigerant.

[0019] The shell 110 has an intake pipe 105 and a discharge pipe 106 inserted into it. The intake pipe 105, for example, is inserted through the side of the shell 110 and draws in low-temperature and low-pressure gaseous refrigerant and guides it into the interior of the shell 110. The discharge pipe 106, for example, is inserted through the upper end of the shell 110 and discharges high-temperature and high-pressure gaseous refrigerant to the main circuit R.

[0020] [Oil Separator 11] The oil separator 11 separates the high-temperature and high-pressure refrigerant containing oil, which flows in via the main circuit R, into gas and liquid. The gas generally contains gaseous refrigerant, and the liquid generally contains oil. The volume of the oil separator 11 is, for example, 100 cc to 1 L. An inlet 111 is formed on the side of the oil separator 11, an outlet 112 is formed at the top, and an oil return port 113 is formed at the bottom. Of the high-temperature and high-pressure refrigerant that flows in from the inlet 111, the gas flows out from the outlet 112 and flows through the main circuit R, and the liquid flows out from the oil return port 113.

[0021] [Condenser 12] The condenser 12 is a heat exchanger into which high-temperature and high-pressure gaseous refrigerant flows and exchanges heat with the surrounding heat transfer medium. The heat transfer medium is, for example, air, in which case the condenser 12 is, for example, a fin-and-tube type heat exchanger. The type of heat transfer medium and the configuration of the heat exchanger are not particularly limited. In the condenser 12, the high-temperature and high-pressure refrigerant exchanges heat with the low-temperature heat transfer medium surrounding the condenser 12, heating the surrounding heat transfer medium, causing it to liquefy, and then flows out as liquid refrigerant.

[0022] [Pressure Reducing Device 13] The pressure reducing device 13 reduces the pressure of the liquid refrigerant to make it a low-pressure liquid refrigerant. The pressure reducing device 13 is, for example, an expansion valve.

[0023] [Evaporator 14] The evaporator 14 is a heat exchanger into which a low-pressure refrigerant flows and exchanges heat with the surrounding heat transfer medium. Similar to the condenser 12, the heat transfer medium in the evaporator 14 is, for example, air, in which case the condenser 12 is, for example, a fin-and-tube type heat exchanger. The type of heat transfer medium and the configuration of the heat exchanger are not particularly limited. In the evaporator 14, the medium-pressure refrigerant exchanges heat with the high-temperature heat transfer medium surrounding the evaporator 14, cools the surrounding heat transfer medium, evaporates, and flows out as a gas or two-phase refrigerant.

[0024] [Accumulator 15] The accumulator 15 stores excess refrigerant and liquid refrigerant that could not be completely evaporated in the evaporator 14, separated from the gaseous refrigerant. The volume of the accumulator 15 is, for example, 10 to 20 liters. The presence of the accumulator 15 prevents damage to valves or valve covers, etc., caused by liquid compression resulting from the inhalation of liquid refrigerant that could not be completely evaporated into the compressor 10.

[0025] [Oil reservoir container 16] The oil reservoir container 16 is a container for storing the oil separated by the oil separator 11. The oil reservoir container 16 is located near the compressor 10. For example, the oil reservoir container 16 is attached in contact with the side of the compressor 10. By having the oil reservoir container 16 located near the compressor 10, oil can be immediately supplied to the oil reservoir 104 of the compressor 10 even if the amount of oil in the oil reservoir 104 of the compressor 10 decreases rapidly.

[0026] The oil reservoir container 16 is, for example, a spherical shape that is convex downwards, with a cross-sectional area perpendicular to the axial direction decreasing towards the bottom. Due to this shape, when the amount of oil in the oil reservoir container 16 increases, the surface area of ​​the oil increases, so the rise in the oil level in response to the increase in oil volume is gradual.

[0027] The oil reservoir container 16 is connected to a return oil pipe 161, a return oil liquid pipe 162, and a gas pipe 163. One end of the return oil pipe 161 is connected to the upper part, and the other end is connected to the lower part of the oil separator 11. Oil separated from the oil separator 11 flows into and circulates through the return oil pipe 161. A throttle 164 is provided in the return oil pipe 161. The throttle 164 reduces the pressure of the refrigerant flowing into the oil reservoir container 16 to the pressure of the low-pressure space.

[0028] The oil return pipe 162 has one end connected to the bottom of the container and the other end communicating with the oil storage section 104. One end of the oil return pipe 162 is connected, for example, to the bottom of the oil reservoir container 16. One end of the oil return pipe 162 penetrates, for example, the bottom of the oil reservoir container 16 vertically upward. The other end of the oil return pipe 162 penetrates the shell 110 of the compressor 10 and extends in a bend vertically upward. This prevents gaseous refrigerant from accumulating in the oil return pipe 162. If one end of the oil return pipe 162 is connected to the compressor 10 from, for example, the very bottom of the oil reservoir container 16, the amount of oil in the container can be limited while ensuring the oil level in the oil reservoir container 16.

[0029] The gas pipe 163 has one end connected to the upper side of the oil reservoir container 16, and the other end penetrates the side of the compressor 10's shell 110 and is connected to a low-pressure space in the compressor 10 that is not filled with oil, for example, above the motor 101. The gas pipe 163 allows the refrigerant gas separated from the liquid in the oil reservoir container 16 to flow out into the low-pressure space of the compressor 10. The gas pipe 163 is provided to return the refrigerant gas separated in the oil reservoir container 16 from the oil reservoir container 16 to the compressor 10. The refrigerant gas flows into the oil reservoir container 16 mixed with the liquid flowing in from the oil separator 11.

[0030] Figure 2 is a schematic diagram illustrating the position of the oil reservoir container 16 of the refrigeration cycle device 100 according to Embodiment 1. As shown in Figure 2, the oil reservoir container 16 is positioned such that its lower height A is higher than the tip height B of the other end of the return oil pipe 162. The lower height A of the oil reservoir container 16 refers to the lower part of the inner surface of the oil reservoir container 16, and is the height of the bottom surface.

[0031] Furthermore, the lower height A of the oil reservoir container 16 is lower than the appropriate oil level height D. The appropriate oil level height D is the height of the oil surface in the compressor 10 when the minimum amount of oil necessary for the sliding of bearings and the like is sealed inside. The appropriate oil level height D is set lower than the lower end height E of the motor 101.

[0032] Furthermore, the tip height B of the other end of the oil return pipe 162 is higher than the suction height C, which is the tip height of the oil pump 103a. In other words, the oil reservoir container 16 is positioned such that the following relationship holds: suction height C of the oil pump 103a < tip height B of the oil return pipe 162 < lower height A of the oil reservoir container 16 < appropriate oil volume height D.

[0033] [Oil level height measuring means 17] Figure 3 is a schematic cross-sectional view of the compressor 10 of the refrigeration cycle device 100 according to Embodiment 1. As shown in Figure 3, an oil level height measuring means 17 is provided at the bottom of the compressor 10.

[0034] The oil level measuring means 17 is composed of, for example, multiple temperature sensors. When multiple temperature sensors are used as the oil level measuring means 17, the multiple temperature sensors are arranged, for example, at equal intervals along the vertical direction of the compressor 10. Since the oil that accumulates in the oil reservoir 104 is oil that has been heated and separated by the compression mechanism 102, the portion of the oil reservoir 104 where the oil has accumulated is at a higher temperature than the surrounding low-temperature and low-pressure gaseous refrigerant.

[0035] As an oil level height measuring means 17, for example, the temperature of the lower part of the compressor 10 is measured by multiple temperature sensors, and the temperature distribution in the vertical direction of the compressor 10 is determined based on the measured temperature, thereby detecting the oil level height X of the oil reservoir 104.

[0036] [Control device 20] The operation of the refrigeration cycle device 100 is controlled by the control device 20. The control device 20, for example, acquires a value detected from the oil level height measuring means 17 and calculates the oil level height X. The control device 20 also controls the rotation speed of the compressor 10 and adjusts the amount of refrigerant discharged. Furthermore, if the refrigeration cycle device 100 has a four-way valve, the control device 20 controls the switching of the four-way valve to switch between cooling operation and heating operation.

[0037] The control device 20 is composed of, for example, a CPU (Central Processing Unit, central processing unit, processing unit, arithmetic unit, microprocessor, microcomputer, processor, also called a DSP (Digital Signal Processor)). The control device 20 has memory composed of, for example, non-volatile or volatile semiconductor memory such as RAM (Random Access Memory), ROM (Read Only Memory), flash memory, EPROM (Erasable Programmable Read Only Memory), EEPROM (Electrically Erasable Programmable Read Only Memory), magnetic disks, flexible disks, optical disks, compact disks, minidiscs, DVDs (Digital Versatile Disks), etc. The control device 20 performs processing using programs stored in memory. However, the control device 20 is not limited to this, and each part may be composed of separate dedicated devices.

[0038] <Refrigerant Operation> The refrigerant is compressed in the compression mechanism 102 of the compressor 10, becoming a high-temperature and high-pressure gaseous refrigerant, which is then discharged from the discharge pipe 106. The refrigerant discharged from the compressor 10 passes through the oil separator 11 and flows into the condenser 12, where it exchanges heat with the surrounding heat transfer medium, releases heat, and flows out at a low temperature. The refrigerant that flows out of the condenser 12 is depressurized in the depressurizing device 13, becoming low-pressure, and flows into the evaporator 14. In the evaporator 14, it absorbs heat from the surrounding heat transfer medium and evaporates, becoming a low-temperature and low-pressure gaseous two-phase refrigerant. The low-temperature and low-pressure gaseous two-phase refrigerant passes through the accumulator 15, becomes a gaseous refrigerant, and is drawn into the compressor 10.

[0039] <Oil Operation> Oil is drawn up from the oil reservoir 104 at the bottom of the compressor 10 by the oil pump 103a, passes through the oil passage that penetrates the crankshaft 103, and is supplied to each sliding part of the compressor 10, for example, to lubricate each sliding part such as bearings. A portion of the oil that has lubricated each sliding part returns to the bottom of the compressor 10 and is stored in the oil reservoir 104. Another portion of the oil that has lubricated each sliding part is discharged from the discharge pipe 106 together with the refrigerant, which has become high pressure and high temperature, and flows out into the main circuit R. The oil that has flowed out into the main circuit R flows into the oil separator 11, where it is separated from the gaseous refrigerant, and flows from the outlet 112 of the oil separator 11 through the return oil pipe 161 into the oil reservoir container 16, where it is stored.

[0040] In the oil reservoir 104 at the bottom of the compressor 10, the oil level X is maintained at a height higher than the suction height C of the oil pump 103a and lower than the appropriate oil volume height D. When the oil level X is higher than the appropriate oil volume height D, the oil moves from the oil reservoir 104 to the oil storage container 16 through the oil return pipe 162 and is stored in the oil storage container 16. This is because the lower height A of the oil storage container 16 is higher than the tip height B of the oil return pipe 162 and lower than the appropriate oil volume height D.

[0041] In this case, if the oil return pipe 162 is connected to the bottom of the oil reservoir container 16, the amount of oil stored in the oil reservoir container 16 can be reduced while maintaining the oil level height X in the oil storage section 104. As a result, the oil level height X in the oil storage section 104 is maintained at a level lower than the appropriate oil volume height D, and excess oil in the compressor 10 is suppressed.

[0042] On the other hand, if the oil level height X falls below the suction height C of the oil pump 103a, it becomes impossible to draw oil from the oil pump 103a, and the oil in the oil reservoir container 16 moves to the oil storage section 104 via the return oil liquid pipe 162. As a result, the oil level height X in the oil storage section 104 becomes higher than the suction height C of the oil pump 103a, making it possible to draw oil from the oil pump 103a, thereby suppressing oil depletion in the compressor 10.

[0043] For example, when compressor 10 constitutes a refrigeration cycle apparatus 100 used for a multi-type air conditioner for buildings, the piping length may increase and reach up to 1000 m depending on the number of indoor units connected to main circuit R. In such a case, part of the oil discharged from compressor 10 flows to the indoor units connected to main circuit R. Therefore, if an insufficient amount of oil is sealed in compressor 10, the oil that has flowed to the indoor units cannot be recovered, and oil depletion may occur.

[0044] When oil depletion causes the oil level height X in oil storage section 104 to become lower than that of oil pump 103a, oil cannot be sucked up, no oil is supplied to the sliding parts of compressor 10, and the performance of compressor 10 degrades. Therefore, in order to prevent the amount of oil sealed in compressor 10 from becoming excessively small, the maximum piping length condition for compressor 10 is taken as the catalog value, and the amount of oil to be sealed is set based on this.

[0045] In this case, if the piping length in the installed state is shorter than the catalog value, an excessively oil-rich condition occurs where the oil level height X in compressor 10 is higher than the appropriate oil level height D. In an excessively oil-rich condition, for example, the motor or the like may be immersed in oil, or oil may be stirred, which leads to an increase in electrical input. In addition, stirring of oil causes the oil to flow out into the refrigerant circuit, which changes the flow rate of the refrigerant itself in the refrigerant circuit, resulting in degraded performance of compressor 10.

[0046] In Embodiment 1, an oil sump container 16 is disposed adjacent to compressor 10, and is arranged such that the lower height A of oil sump container 16 is higher than the tip height B of the other end of oil return pipe 162. Accordingly, when the amount of oil increases, the oil exceeding the appropriate oil level height D moves to and is stored in oil sump container 16. Since oil that cannot be entirely stored in oil storage section 104 of compressor 10 is stored in oil sump container 16 disposed adjacent to compressor 10, performance degradation of compressor 10 caused by excessive oil can be suppressed.

[0047] <Modification 1-1> FIG. 4 is a circuit configuration diagram of a refrigeration cycle apparatus 100 according to Modification 1-1 of Embodiment 1. As shown in FIG. 4, an oil return pipe 162 is provided with a first opening / closing valve 61. The first opening / closing valve 61 adjusts the amount of oil flowing into the oil reservoir 104 in the compressor 10 from the oil sump container 16 via the oil return pipe 162. The first opening / closing valve 61 is, for example, a solenoid valve with an adjustable opening degree. The control device 20 controls, for example, the opening degree of the first opening / closing valve 61 provided in the oil return pipe 162. The first opening / closing valve 61 is controlled based on the oil level height X in the oil reservoir 104. The first opening / closing valve 61 is an example of a flow rate adjusting valve.

[0048] When the oil level height X of the oil reservoir 104 is lower than the suction portion height C of the oil pump 103a, the first opening / closing valve 61 is controlled to allow oil to flow into the oil reservoir 104 from the oil sump container 16. Accordingly, when the oil level height X in the oil reservoir 104 decreases, it is possible to increase the oil level height X and maintain the proper oil amount height D, thereby suppressing an excessive shortage of oil stored in the compressor 10.

[0049] <Modification 1-2> FIG. 5 is a circuit configuration diagram of a refrigeration cycle apparatus 100 according to Modification 1-2 of Embodiment 1. As shown in FIG. 5, the oil sump container 16 has a configuration in which the other end of a gas pipe 163 is connected to the suction pipe 105 of the compressor 10. Since the suction pipe 105 is a component originally provided in the compressor 10, it is possible to optimize the amount of oil in the compressor 10 while minimizing modification to the compressor 10.

[0050] <Modification 1-3> FIG. 6 is a circuit configuration diagram of a refrigeration cycle apparatus 100 according to Modification 1-3 of Embodiment 1. As shown in FIG. 6, the oil sump container 16 is integrated with the accumulator 15. For example, the oil sump container 16 shares a part of its side surface with a part of the side surface of the accumulator 15. The oil sump container 16 may have a configuration in which the interior of the container is divided into a portion of the oil sump container 16 and a portion of the accumulator 15 by a partition plate.

[0051] Because the oil reservoir 16 is integrated with the accumulator 15, the high-temperature oil in the oil reservoir 16 is cooled by the low-temperature refrigerant in the accumulator 15, which suppresses excessive oil temperature and thus improves the reliability of the oil in the compressor 10. Furthermore, the low-temperature refrigerant in the accumulator 15 is heated by the high-temperature oil in the oil reservoir 16, which promotes the evaporation of the liquid refrigerant, suppressing liquid backflow in the compressor 10 or accelerating the movement of the refrigerant.

[0052] <Modification 1-4> Figure 7 is a schematic cross-sectional view of the oil reservoir container 16 of the refrigeration cycle device 100 according to Modification 1-4 of Embodiment 1. As shown in Figure 7, a float-type sensor 22 may be provided in the oil reservoir container 16 as an oil level height measuring means 17 to measure the height of the oil level in the oil reservoir container 16.

[0053] The float-type sensor 22 includes a shaft 221, a shaft 222 attached to the shaft 221, a float 223 attached to one end of the shaft 222, and a valve body 224 attached to the other end of the shaft 222. The shaft 221 rotatably holds the shaft 222. The valve body 224 has a shape that can close the opening 16a leading to the oil return pipe 162.

[0054] When the oil level in the oil reservoir container 16 is low, the float 223 also descends and the valve body 224 rises, so the opening 16a is open. When the oil level rises, the float 223 rises accordingly, and the shaft 222 rotates around its axis, causing the valve body 224 to descend and the opening 16a to be closed by the valve body 224. As a result, when the oil level in the oil reservoir container 16 reaches a predetermined value, the return oil liquid pipe 162 is sealed, and the inflow of oil from the return oil liquid pipe 162 to the oil storage section 104 is stopped.

[0055] The oil level measuring means 17 may be provided in at least one of the oil storage section 104 or the oil reservoir container 16. Alternatively, for example, the oil level measuring means 17, which is composed of multiple temperature sensors, may be provided in the oil reservoir container 16.

[0056] The refrigeration cycle device 100 according to Embodiment 1, as described above, includes an oil reservoir container 16 in which the oil separated by the oil separator 11 is stored. The oil reservoir container 16 is positioned such that its lower height A is higher than the tip height B of the return oil pipe 162 which communicates with the oil storage section 104 of the compressor 10. Therefore, when the oil level X in the oil storage section 104 reaches or exceeds the appropriate oil volume height D, oil moves from the oil storage section 104 to the oil reservoir container 16. This suppresses a decrease in the performance of the compressor 10 due to excess oil. Consequently, the appropriate oil volume height D, which is the minimum necessary for the sliding of the bearings of the compressor 10 in the oil storage section 104, can be secured. For example, if the oil separated by the oil separator 11 is returned to the suction side of the compressor 10, it may heat the refrigerant at the inlet of the compressor 10, causing a loss. However, if the oil volume is above the appropriate oil volume height D, the oil is stored in the oil reservoir container 16, thereby reducing the loss. In particular, if the oil reservoir 16 is located near the compressor 10, oil can be supplied to the oil reservoir 104 immediately even if the oil level in the compressor 10 rapidly decreases. Furthermore, if the shape of the oil reservoir 16 is such that the liquid level decreases towards the bottom, for example, a downward-convex spherical shape, and the return oil pipe 162 is connected to the bottom surface of the oil reservoir 16, it is possible to reduce the amount of oil while maintaining the height of the oil level in the oil reservoir 16. Also, if the shape of the oil reservoir 16 is such that the liquid area increases as the oil level rises, the rise in the oil level in response to an increase in the amount of oil becomes more gradual, and the movement of oil to the compressor 10 as the oil level drops becomes faster.

[0057] Furthermore, since the oil reservoir container 16 is positioned such that its lower height A is higher than the suction height C of the oil pump 103a, the oil level X in the oil reservoir 104 can be maintained at or above the suction height C of the oil pump 103a.

[0058] Furthermore, since the return oil pipe 162 is equipped with a first on-off valve 61 that functions as a flow control valve, the amount of oil stored inside the compressor 10 can be adjusted to an appropriate level.

[0059] Furthermore, the oil reservoir 104 of the compressor 10 is provided with an oil level measuring means 17 for measuring the oil level height X, and the amount of oil returned can be adjusted according to the oil level height X in the oil reservoir 104. The oil level measuring means 17 is composed of, for example, a plurality of temperature sensors. The oil level measuring means 17 may be, for example, a float type sensor 22, or an ultrasonic or capacitive type sensor.

[0060] Furthermore, the oil level measuring means 17 may be provided in the oil reservoir container 16, in which case the oil level measuring means 17 can measure the height of the oil in the oil reservoir container 16. In this case as well, the oil level measuring means 17 can be, for example, a plurality of temperature sensors, a float-type sensor 22, an ultrasonic or capacitive sensor, etc.

[0061] Furthermore, since a gas pipe 163 connected to the low-pressure space of the compressor 10 is connected to the upper part of the oil reservoir container 16, the refrigerant gas that flows into the oil reservoir container 16 can be returned to the compressor 10.

[0062] In particular, by connecting the gas pipe 163 to the suction pipe 105, it is possible to return the refrigerant gas that has flowed into the oil reservoir container 16 to the compressor 10 while minimizing modifications to the compressor 10.

[0063] Furthermore, since the oil reservoir container 16 is housed in a container integrated with the accumulator 15, it is possible to suppress excessive oil temperature and improve the reliability of the oil, as well as suppress liquid backflow or increase the refrigerant's movement speed by evaporating the refrigerant liquid.

[0064] Embodiment 2. Figure 8 is a circuit diagram of the refrigeration cycle device 100 according to Embodiment 2. The refrigeration cycle device 100 according to Embodiment 2 differs from that of Embodiment 1 in the configuration of the oil return pipe 162. In Embodiment 2, parts common to Embodiment 1 are denoted by the same reference numerals and their descriptions are omitted, and the explanation will focus on the differences from Embodiment 1.

[0065] As shown in Figure 8, the oil return pipe 162 is equipped with a first pump 165a and a second pump 165b as oil pumps. The first pump 165a and the second pump 165b are connected in parallel to the oil return pipe 162. The first pump 165a transports oil so that the oil in the oil storage section 104 flows into the oil reservoir container 16. On the other hand, the second pump 165b transports oil so that the oil in the oil reservoir container 16 flows into the oil storage section 104. The operation of the first pump 165a and the second pump 165b is controlled, for example, by a control device 20.

[0066] By connecting the first pump 165a and the second pump 165b to the oil return pipe 162, switching between oil return and oil extraction becomes reliable, and the oil level X in the oil storage section 104 can be actively adjusted.

[0067] Furthermore, the oil return pipe 162 only needs to be equipped with at least a first pump 165a, in which case, instead of the second pump 165b, for example, an on-off valve may be provided. When the first pump 165a and the on-off valve are installed, the switching between oil return and extraction can be performed in a more energy-efficient manner.

[0068] As described above, in the refrigeration cycle device 100 according to Embodiment 2, since the return oil liquid pipe 162 is provided with a first pump 165a and a second pump 165b, the oil level X in the oil storage section 104 can be actively adjusted.

[0069] Embodiment 3. Figure 9 is a circuit diagram of the refrigeration cycle device 100 according to Embodiment 3. The refrigeration cycle device 100 according to Embodiment 3 differs from Embodiments 1 or 2 in that it is equipped with a plurality of compressors 10. In Embodiment 3, parts common to Embodiments 1 or 2 are denoted by the same reference numerals and their descriptions are omitted, and the explanation will focus on the differences from Embodiments 1 or 2.

[0070] As shown in Figure 9, the refrigeration cycle device 100 has a first compressor 10a and a second compressor 10b. The first compressor 10a and the second compressor 10b are connected in parallel to the main circuit R. The main circuit R is configured to branch downstream of the accumulator 15 and merge upstream of the oil separator 11. The oil reservoir container 16 is connected to an oil return pipe 161, a first oil return pipe 162a and a second oil return pipe 162b, and a first gas pipe 163a and a second gas pipe 163b. The first oil return pipe 162a communicates with the first oil storage section 104a of the first compressor 10a, and the second oil return pipe 162b communicates with the second oil storage section 104b of the second compressor 10b. The first oil return pipe 162a and the second oil return pipe 162b are each provided with a first on / off valve 61.

[0071] To increase the capacity of the air conditioner, it is effective to install multiple compressors 10 in parallel. On the other hand, it is difficult to perfectly match the length of the piping 100a or the shape of the suction pipe 105 in each compressor 10, and since the amount of oil returned to each compressor 10 is different, it is also difficult to match the oil level height X in each compressor 10. By connecting one oil reservoir container 16 to each of the oil storage sections 104 of the multiple compressors 10, it is possible to equalize the oil level height X in the multiple compressors 10.

[0072] As described above, in the refrigeration cycle device 100 according to Embodiment 3, since the oil storage units 104 provided in each of the multiple compressors 10 are connected to a single oil storage container 16, the oil level height X in the multiple compressors 10 can be made equal.

[0073] Embodiment 4. Figure 10 is a circuit diagram of the refrigeration cycle device 100 according to Embodiment 4. The configuration of the gas pipe 163 in the refrigeration cycle device 100 according to Embodiment 4 differs from that of Embodiments 1 to 3. In Embodiment 4, parts common to Embodiments 1 to 3 are denoted by the same reference numerals and their descriptions are omitted, and the explanation will focus on the differences from Embodiments 1 to 3.

[0074] As shown in Figure 10, the gas pipe 163 penetrates the side of the shell 110 of the compressor 10 and is connected to an oil tray 107 located in the low-pressure space of the compressor 10. The oil tray 107 is located between the compression mechanism 102 and the motor 101. The oil tray 107 receives oil that has lubricated the sliding parts of the compression mechanism 102 and then falls below the compression mechanism 102 before it reaches the top surface of the motor 101. The oil tray 107 is, for example, a dish-shaped member provided on a plane perpendicular to the axis of the compressor 10.

[0075] The other end of the gas pipe 163 is connected to the oil receiver 107. The gas pipe 163 connects the oil reservoir 16 and the compressor 10 such that the height of the connection position G on the container side is lower than the height of the connection position F on the compressor side. The connection position G on the container side is the position where one end of the gas pipe 163 is connected to the oil reservoir 16, and the connection position F on the compressor side is the position where the other end of the gas pipe 163 penetrates the side of the shell 110. As a result, the oil received in the oil receiver 107 flows through the gas pipe 163 by gravity from the other end of the gas pipe 163 to the one end of the gas pipe 163 and is stored in the oil reservoir 16, so that excess refrigerant in the compressor 10 can be recovered.

[0076] The oil stored in the oil reservoir 104 is drawn in by the oil pump 103a and reaches the compression mechanism 102, lubricating the sliding parts of the compression mechanism 102. The oil that has lubricated the sliding parts of the compression mechanism 102 passes through the flow passage 102a between the shell 110 and the compression mechanism 102, moves to the bottom of the compression mechanism 102, falls, and is collected in the oil receiver 107. The oil collected in the oil receiver 107 passes through the gas pipe 163 and is stored in the oil reservoir container 16. In this way, the compressor 10 itself can be used as a pump to move oil to the oil reservoir container 16.

[0077] Embodiment 5. Figure 11 is a circuit diagram of the refrigeration cycle device 100 according to Embodiment 5. The refrigeration cycle device 100 according to Embodiment 5 differs from Embodiments 1 to 4 in that it has a booster pipe 168 and an oil drain pipe 169. In Embodiment 5, parts common to Embodiments 1 to 4 are denoted by the same reference numerals and their descriptions are omitted, and the explanation will focus on the differences from Embodiments 1 to 4.

[0078] As shown in Figure 11, the oil reservoir container 16 is connected to an oil return pipe 161, an oil return liquid pipe 162, a pressure boosting pipe 168, and an oil draining pipe 169. The pressure boosting pipe 168 connects the oil reservoir container 16 to the oil separator 11. The oil draining pipe 169 connects the oil reservoir container 16 to the accumulator 15. The pressure boosting pipe 168 and the oil draining pipe 169 perform an oil return operation that returns the oil from the oil separator 11 back to the compressor 10, and an oil draining operation that moves the oil from the compressor 10 to the accumulator 15.

[0079] A first on-off valve 61 is provided in the oil return pipe 162. A second on-off valve 62, a third on-off valve 63, and a chamber 65 provided between the second on-off valve 62 and the third on-off valve 63 are provided in the booster pipe 168. The operation of the first on-off valve 61, the second on-off valve 62, and the third on-off valve 63 is controlled, for example, by a control device 20.

[0080] The oil reservoir container 16 is equipped with an oil level measuring means 17, such as a float-type sensor, and one end of the oil drain pipe 169 is inserted near the bottom of the oil reservoir container 16 so as to be below the oil level.

[0081] The oil return operation and oil draining operation are performed, for example, by the control of the control device 20. In the oil return operation, the control device 20 first opens the first on-off valve 61 and closes the second on-off valve 62 and the third on-off valve 63. At this time, the inside of the oil reservoir container 16 is in communication with the accumulator 15 via the oil draining pipe 169 and is at the same pressure as the accumulator 15.

[0082] The oil flows from the oil separator 11 through the return oil pipe 161 into the oil reservoir container 16, and then from the oil reservoir container 16 through the return oil liquid pipe 162 and into the oil storage section 104 of the compressor 10 via the first on-off valve 61. Since the oil storage section 104 of the compressor 10 is in communication with the oil reservoir container 16 via the return oil liquid pipe 162, the oil level in the oil storage section 104 rises to the same height as the oil level in the oil reservoir container 16. When the oil level height X in the oil storage section 104 reaches the appropriate oil volume height D, the control device 20 closes the first on-off valve 61 and ends the oil return operation.

[0083] During the oil draining operation, the control device 20 first closes the first on-off valve 61, opens the second on-off valve 62, and closes the third on-off valve 63. The oil draining operation is started, for example, when the float-type sensor 22 detects that the oil level in the oil reservoir container 16 has risen above a predetermined value. As a result, high-pressure fluid flows from the oil separator 11 into the chamber 65, and the pressure inside the chamber 65 increases.

[0084] Next, the control device 20 keeps the first on-off valve 61 closed, opens the second on-off valve 62, and closes the third on-off valve 63. As a result, the gas from the chamber 65 flows into the oil reservoir container 16. The gas from the chamber 65 temporarily increases the pressure in the oil reservoir container 16, causing the oil reservoir container 16 to reach medium pressure and the accumulator 15 to reach low pressure, creating a pressure difference between the oil reservoir container 16 and the accumulator 15.

[0085] As a result, the oil in the oil reservoir 16 moves to the accumulator 15. The movement of oil from the oil reservoir 16 to the accumulator 15 stops when the pressure in the oil reservoir 16 decreases and balances out with the pressure in the accumulator 15 and the resistance of the oil drain pipe 169.

[0086] Next, when the control device 20 determines, based on the oil level detection means, that the liquid level has decreased, it closes the second on-off valve 62. The operation to close the second on-off valve 62 may be performed at a predetermined timing or after a predetermined time has elapsed.

[0087] Next, the control device 20 opens the first on-off valve 61. This allows the oil in the compressor 10 to move to the oil reservoir container 16, thereby lowering the oil level X in the compressor 10.

[0088] In this way, the booster piping 168, which includes the second on-off valve 62, the third on-off valve 63, and the chamber 65, can move the oil from the compressor 10 to the accumulator 15 on the suction side via the oil reservoir container 16. The oil separator 11 has a volume of 1 liter or 100 cc, while the accumulator 15 has a volume of 10 liters to 20 liters, allowing it to store more oil. By providing the booster piping 168, when the amount of oil in the compressor 10 increases, it is possible to move the oil to the accumulator 15 using the booster piping 168, thereby reducing the amount of oil in the compressor 10 and maintaining an appropriate oil level.

[0089] The chamber 65 may utilize the volume of a spiral pipe or the like, rather than a container. Also, if the high-pressure flow rate can be controlled by the opening and closing time of the second on-off valve 62, the chamber 65 and the third on-off valve 63 can be omitted. Alternatively, the second on-off valve 62, the third on-off valve 63, and the chamber 65 may be provided in the return oil pipe 161, in which case the return oil pipe 161 has the function of supplying high pressure to the oil reservoir container 16. Furthermore, a flow control valve, such as a linear expansion valve, may be installed in the return oil pipe 161, and pressure may be generated in the oil reservoir container 16 by temporarily increasing the opening of the flow control valve.

[0090] The refrigeration cycle device 100 according to Embodiment 5 described above is equipped with a second on-off valve 62, a third on-off valve 63, and a chamber 65 in the booster piping 168. Therefore, the high-pressure fluid flowing in from the booster piping 168 can move the oil in the oil reservoir container 16 to the accumulator 15 via the oil drain piping 169. Consequently, even when the amount of oil inside the compressor 10 increases, the amount of oil can be reduced and the appropriate amount of oil in the compressor 10 can be maintained.

[0091] Furthermore, embodiments 1 to 5 can be combined as appropriate.

[0092] 10 Compressor, 10a First compressor, 10b Second compressor, 11 Oil separator, 12 Condenser, 13 Pressure reducing device, 14 Evaporator, 15 Accumulator, 16 Oil reservoir container, 16a Opening, 17 Oil level height measuring means, 20 Control device, 22 Float type sensor, 61 First on-off valve, 62 Second on-off valve, 63 Third on-off valve, 65 Chamber, 100 Refrigeration cycle device, 100a Piping, 101 Motor, 101a Stator, 101b Rotor, 102 Compression mechanism, 102a Flow passage, 103 Crankshaft, 103a Oil pump, 104 Oil reservoir, 104a First reservoir, 104b Second oil reservoir, 105 Suction pipe, 106 Discharge pipe, 107 Oil receiver, 110 Shell, 111 Inlet, 112 Outlet, 113 Return oil port, 161 Return oil piping, 162 Return oil liquid pipe, 162a First return oil liquid pipe, 162b Second return oil liquid pipe, 163 Gas pipe, 163a First gas pipe, 163b Second gas pipe, 164 Throttle, 165a First pump, 165b Second pump, 168 Pressure boosting piping, 169 Oil draining piping, 221 Shaft, 222 Float, 224 Valve body, A Lower height, B Front height, C Suction height, D Appropriate oil volume height, E Lower end height, F Compressor side connection position, G Container side connection position, H High pressure atmosphere, L Low pressure atmosphere, R Main circuit, X Oil level height.

Claims

1. A refrigeration cycle device comprising: a compressor having a low-pressure structure shell in which a motor is installed in a low-pressure atmosphere; an oil separator; a condenser; a pressure reducing device; and an evaporator, wherein the compressor, the oil separator, the condenser, the pressure reducing device, and the evaporator are connected by piping and a refrigerant circulates, further comprising: an oil reservoir container to which an oil return pipe for receiving oil separated by the oil separator is connected at the top; and a return oil liquid pipe having one end connected to the bottom of the oil reservoir container and the other end connected to an oil reservoir formed at the bottom of the compressor, wherein the bottom of the oil reservoir container is positioned higher than the other end of the return oil liquid pipe in the shell of the compressor.

2. The refrigeration cycle apparatus according to claim 1, further comprising an oil pump for drawing oil from the oil reservoir, wherein the oil reservoir is positioned such that the lower part of the oil reservoir is higher than the tip of the oil pump.

3. The refrigeration cycle apparatus according to claim 1 or 2, wherein the return oil liquid pipe is provided with a flow control valve for adjusting the amount of oil returned from the oil reservoir container to the oil storage section of the compressor.

4. The refrigeration cycle apparatus according to any one of claims 1 to 3, wherein the oil storage section is provided with an oil level height measuring means for measuring the height of the oil level in the oil storage section.

5. The refrigeration cycle apparatus according to any one of claims 1 to 3, wherein the oil reservoir is provided with an oil level height measuring means for measuring the height of the oil level in the oil reservoir.

6. The refrigeration cycle apparatus according to any one of claims 1 to 5, further comprising a gas pipe, one end of which is connected to the upper part of the side surface of the oil reservoir container and the other end of which is connected to the low-pressure space of the compressor.

7. The refrigeration cycle apparatus according to claim 6, wherein the compressor is provided with an intake pipe from which low-pressure refrigerant is drawn in, and the gas pipe is connected to the intake pipe of the compressor.

8. The refrigeration cycle apparatus according to any one of claims 1 to 7, further comprising an accumulator connected between the evaporator and the compressor, wherein the oil reservoir is housed in a container integrated with the accumulator, and heat exchange is performed between the liquid refrigerant stored in the accumulator and the oil stored in the oil reservoir.

9. The refrigeration cycle apparatus according to any one of claims 1 to 8, wherein an oil pump is connected to the oil return pipe.

10. A refrigeration cycle apparatus according to any one of claims 1 to 9, comprising a plurality of compressors, wherein the plurality of compressors are connected in parallel, and a plurality of return oil pipes connected to the oil storage section provided on each of the plurality of compressors are connected to the oil storage container.

11. The refrigeration cycle apparatus according to any one of claims 1 to 7, further comprising: an accumulator connected between the evaporator and the compressor; an oil drain pipe connecting the accumulator and the inside of the oil reservoir container; and a pressure boosting pipe that pressurizes the fluid of the oil separator and causes it to flow into the oil reservoir container, wherein the oil in the oil reservoir container moves to the accumulator via the oil draining pipe due to the high-pressure fluid flowing in from the pressure boosting pipe.

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