Rotary compressor

Abstract

The rotary compressor according to the present disclosure intermittently communicates between an inner circumferential side space 106i of a piston 106 and a suction chamber 110 to increase an oil supply amount by using an opening time of an oil supply groove 117 to the suction chamber 110 under a low rotation condition on which an amount of oil supply is desirably increased, and by using a pressure difference under a high differential pressure condition. Thus, an oil supply amount is made appropriate in a wide operation range, and high efficiency and high reliability can be achieved simultaneously.

Description

[TECHNICAL FIELD]

[0001] The present invention relates to a rotary compressor.[BACKGROUND TECHNIQUE](Knowledge etc. forming the basis of this disclosure)

[0002] Conventionally, there exists a hermetic rotary type compressor as described in Patent Document 1, for the purpose of improving high performance and high reliability of compressors.

[0003] This hermetic rotary type compressor includes, within a hermetic container, an electric element having a stator and a rotor, a drive shaft having an eccentric part for transmitting rotation by the electric element, and a compression element for compressing a working fluid by rotation of the eccentric part of the drive shaft.

[0004] The compression element includes a cylinder with a cylindrical inner peripheral surface open at both ends, a roller fitted to the eccentric part of the drive shaft inside the cylinder, a vane which divides the inside of the cylinder into a suction chamber and a compression chamber accompanying the eccentric motion of the roller, an end plate closing the opening of the cylinder, an oil supply mechanism for supplying lubricating oil to the inside of the roller via the drive shaft, and a lubricating oil supply mechanism.

[0005] The lubricating oil supply mechanism has a cut-out part for taking in lubricating oil supplied to an inside of the roller, and a recess for holding the lubricating oil from the cut-out part, and the recess alternately communicates with the space inside the roller and the suction chamber.

[0006] In the hermetic rotary compressor described in Patent Document 1, the lubricating oil inside the roller is accumulated in the recess provided on the end plate by rotation of the drive shaft, and then the accumulated lubricating oil is supplied to the suction chamber when the recess communicates with the suction chamber. Therefore, regardless of the compressor's rotation speed or compression ratio, the amount of oil supply is determined only by the volume of the recess, maintaining a constant amount of oil supply per rotation.[PRIOR ART DOCUMENT][PATENT DOCUMENT]

[0007] [Patent Document 1] Japanese Patent No. 4110781[SUMMARY OF THE INVENTION][PROBLEM TO BE SOLVED BY THE INVENTION]

[0008] An amount of refrigerant leakage from such as gaps between the roller and end plate depends on the compressor's rotation speed and pressure difference, increasing especially under low rotation or high differential pressure conditions. Therefore, it is desirable to increase the amount of oil supply per rotation under the low rotation or high differential pressure conditions. However, in the hermetic rotary compressor described in Patent Document 1, since the amount of the oil supply per rotation is constant, if the oil supply amount is determined to suit the low rotation or high differential pressure conditions, there is concern about excessive oil supply under high rotation or low differential pressure conditions, leading to decreased volumetric efficiency and increased OCR. Conversely, if the oil supply amount is determined to suit the high rotation or low differential pressure conditions, there is a concern about insufficient oil supply under low rotation or high differential pressure conditions, leading to increased leakage loss due to deteriorated sealing and decreased reliability due to deteriorated sliding conditions.

[0009] Therefore, the present disclosure provides a rotary compressor that has high efficiency and improved reliability over a wide operating range by increasing an amount of oil supply under low rotation and high differential pressure conditions and suppressing the oil supply under high rotation and low differential pressure condition.[MEANS FOR SOLVING THE PROBLEM]

[0010] A rotary compressor of this disclosure includes, inside a hermetic container, a rotary type compression mechanism that compresses refrigerant, an electric mechanism that drives the rotary type compression mechanism, and an oil reservoir that stores lubricating oil at a bottom of the hermetic container. The rotary type compression mechanism has a piston, a cylinder, a vane, an upper end plate, and a lower end plate. A compression chamber and a suction chamber are formed by dividing the space formed by the piston and the cylinder with the vane. The upper end plate and the lower end plate close the upper and lower opening surfaces of the compression chamber and the suction chamber. An oil supply groove that intermittently communicates an inner circumferential side space of the piston with an outer peripheral space of the piston is formed on at least one of either the upper end plate or the lower end plate. Oil is supplied from the inner circumferential side space of the piston to the suction chamber through the oil supply groove.[EFFECT OF THE INVENTION]

[0011] The rotary compressor of this disclosure intermittent communicates the inner circumferential side space of the piston with the suction chamber, thereby increasing the oil supply amount by using an opening time of the oil supply groove to the suction chamber under low rotation conditions where it is desirable to increase oil supply, and utilizing the pressure difference under high differential pressure conditions. This allows for optimization of oil supply amount over a wide operating range, simultaneously achieving high efficiency and high reliability.[BRIEF DESCRIPTION OF THE DRAWINGS]

[0012] Fig. 1 is a vertical sectional view of a rotary compressor according to a first embodiment; Fig. 2 is an enlarged view of essential parts of a rotary type compression mechanism in the first embodiment; Fig. 3 are figure showing volume changes of a suction chamber and a compression chamber in the rotary type compression mechanism of the first embodiment; Fig. 4 is a vertical sectional view of a compressor according to a second embodiment; Fig. 5 is an enlarged view of essential parts of a low-stage rotary type compression mechanism and a high-stage rotary type compression mechanism in the second embodiment; Fig. 6 are compression operation explanation diagrams of the low-stage rotary type compression mechanism in the second embodiment; Fig. 7 are compression operation explanation diagrams of the high-stage rotary type compression mechanism in the second embodiment; Fig. 8 are explanation diagrams of a relationship between an opening angle and OCR and COP in the high-stage rotary type compression mechanism or the rotary compressor in the second embodiment; Fig. 9 is a B-B cross-sectional view of Fig. 7 in the second embodiment; Fig. 10 is variation 1 of the oil supply groove in the second embodiment; Fig. 11 is variation 2 of the oil supply groove in the second embodiment; and Fig. 12 are variation 3 of the oil supply groove in the second embodiment. [MODE FOR CARRYING OUT THE INVENTION]

[0013] The following describes the embodiments in detail with reference to the drawings. However, unnecessarily detailed explanations may be omitted. For example, detailed explanations of well-known matters or substantially identical configurations may be omitted. This is to avoid making the following description unnecessarily redundant and to facilitate understanding by those skilled in the art.

[0014] The accompanying drawing and the following description are provided so that a person skilled in the art can sufficiently understand the present disclosure, and it is not intended that they limit the subject matter described in claims.(First Embodiment)

[0015] A first embodiment will be described below using Fig. 1 to 3.[1-1. Configuration]

[0016] Fig. 1 shows a vertical sectional view of a rotary compressor 100 in this embodiment. The rotary compressor 100 includes, a hermetic container 101 having therein a rotary type compression mechanism 102 that compresses refrigerant, an electric mechanism 103 that drives the rotary type compression mechanism 102, and an oil reservoir 101a that stores lubricating oil at the bottom of the hermetic container 101.

[0017] An interior of the hermetic container 101 is a high-pressure atmosphere of discharge pressure discharged from the rotary type compression mechanism 102.

[0018] The electric mechanism 103 includes a stator 103a fixed to the hermetic container 101 and a rotor 103b placed inside the stator 103a, with a drive shaft 104 fixed to the rotor 103b.

[0019] Fig. 2 shows an enlarged view of essential parts of the rotary type compression mechanism 102, which is driven by the drive shaft 104.

[0020] Fig. 3 shows volume changes of a suction chamber 110 and a compression chamber 111 in the rotary type compression mechanism 102, which change in a direction of the arrow.

[0021] As shown in Fig. 2 and 3, the rotary type compression mechanism 102 has a cylinder 105, a piston 106 and a vane 107 sandwiched between an upper end plate 108 and a lower end plate 109. The suction chamber 110 and the compression chamber 111 are formed by dividing a space formed between the cylinder 105 and the piston 106 with the vane 107. An eccentric shaft 104a is housed inside the cylinder 105. The piston 106 is rotatably fitted to the eccentric shaft 104a.

[0022] A suction passage 112 is formed in the cylinder 105. The suction passage 112 communicates with a suction pipe 113 (see Fig. 1) and the suction chamber 110. A discharge hole (not shown) equipped with a check valve (not shown) is formed in the upper end plate 108. A cover 114 is fastened to the upper end plate 108. The discharge hole is covered by the cover 114, forming a discharge space 115 between the upper end plate 108 and the cover 114. The compression chamber 111 communicates with the interior of the hermetic container 101 through the discharge hole. The hermetic container 101 is equipped with a discharge pipe 116 (see Fig. 1). Refrigerant inside the hermetic container 101 is discharged through the discharge pipe 116.

[0023] In this embodiment, the upper end plate 108 serves as an upper bearing, and the lower end plate 109 serves as a lower bearing.

[0024] An oil supply groove 117 is provided on at least one of either the upper end plate 108 or the lower end plate 109. As shown in Fig. 3, the oil supply groove 117 intermittently communicates an inner circumferential side space 106i of the piston 106 with the suction chamber 110 as the piston 106 rotates eccentrically. At a crank angle where the inner circumferential side space 106i of the piston 106 and the suction chamber 110 are in communication with each other through the oil supply groove 117, oil is supplied from the inner circumferential side space 106i of the piston 106 to the suction chamber 110. By altering a position of the oil supply groove 117, the crank angle to communicate between the inner circumferential side space 106i and the suction chamber 110 can be set arbitrarily. Here, the crank angle during a state where the inner circumferential side space 106i of the piston 106 is communicated to the suction chamber 110 through the oil supply groove 117 is referred to as a communication angle.

[0025] However, in this embodiment, the oil supply groove 117 is provided on the lower end plate 109, but the oil supply groove 117 may be provided on the upper end plate 108. Also, the oil supply groove 117 may be provided on both the upper end plate 108 and the lower end plate 109.

[0026] The following explains an operation of the rotary compressor 100 configured as described above.[1-2-1. Compression Operation]

[0027] When the electric mechanism 103 is energized and the drive shaft 104 rotates, the eccentric shaft 104a rotates eccentrically in the cylinder 105, and the piston 106 performs a rotational motion while in contact with the vane 107, whereby the refrigerant is repeatedly sucked and compressed. The suction chamber 110 becomes the compression chamber 111 when it is not in communication with the suction passage 112.

[0028] Low-temperature, low-pressure suction refrigerant sucked from the suction pipe 113 through the suction passage 112 into the suction chamber 110 is compressed as the suction chamber 110 becomes the compression chamber 111. The compressed hightemperature, high-pressure discharge refrigerant is discharged from the discharge hole into the discharge space 115, led to the interior of the hermetic container 101, and discharged to the outside of the hermetic container 101 through the discharge pipe 116.[1-2-2. Oil Supply Operation]

[0029] The lubricating oil is stored in the oil reservoir 101a at the bottom of the hermetic container 101, and normally, the lubricating oil is immersed up to the height of the upper end of the cylinder 105 of the rotary type compression mechanism 102. A lubricating oil passage 118 is provided in the axial direction inside the drive shaft 104. The lubricating oil sucked up from a lower end into the lubricating oil passage 118 by an oil pump mechanism reaches the inner circumferential side space 106i of the piston 106 through an oil supply hole 119 provided in the eccentric shaft 104a while lubricating a sliding part of the eccentric shaft 104a. After that, the lubricating oil lubricates journal bearing sliding parts of the upper end plate 108 and lower end plate 109 before being discharged outside the rotary type compression mechanism 102.

[0030] A portion of the lubricating oil that reaches the inner circumferential side space 106i of the piston 106 is supplied to the suction chamber 110 which intermittently communicates by the oil supply groove 117, lubricating the sliding parts between the piston 106 and the upper end plate 108 and lower end plate 109, and sealing minute gaps in the sliding parts. The lubricating oil supplied to the suction chamber 110 continues to seal the minute gaps in the sliding parts even after the suction chamber 110 becomes the compression chamber 111, and is discharged from the discharge hole along with the refrigerant.[1-3. Effects]

[0031] As described above, in this embodiment, the rotary compressor 100 includes the rotary type compression mechanism 102, the electric mechanism 103, and the oil reservoir 101a that stores lubricating oil at the bottom of the hermetic container 101. The rotary type compression mechanism 102 has the cylinder 105, the piston 106, the vane 107, the upper end plate 108, and the lower end plate 109. The vane 107 divides the space formed by the cylinder 105 and the piston 106 into the suction chamber 110 and the compression chamber 111. The upper end plate 108 and lower end plate 109 close the upper and lower opening surfaces of the suction chamber 110 and compression chamber 111. Also, at least one of either the upper end plate 108 or the lower end plate 109 has the oil supply groove 117 that intermittently communicates the inner circumferential side space 106i of the piston 106 with the suction chamber 110 as the piston 106 rotates eccentrically, and oil is supplied from the inner circumferential side space 106i of the piston 106 to the suction chamber 110 through the oil supply groove 117.

[0032] The oil supply from the inner circumferential side space 106i of the piston 106 to the suction chamber 110 is performed intermittently accompanying the eccentric rotation of the piston 106. Therefore, under low rotation conditions where it is desirable to increase the oil supply amount to improve sealing, an oil supply amount can be increased due to the longer opening time. Under high differential pressure conditions, the oil supply amount can be increased by utilizing a pressure difference. Consequently, it is possible to suppress performance degradation due to increased leakage loss, and seizure of sliding surfaces due to insufficient lubrication, that are caused by insufficient oil supply. On the other hand, under high rotation or low differential pressure conditions, it is possible to suppress the oil supply amount, thereby suppressing volumetric efficiency decrease and OCR increase that are caused by excessive oil supply. This enables the realization of a highly efficient and highly reliable compressor over a wide operating range.

[0033] Also, in this first embodiment, the rotary compressor 100 sets the position of the oil supply groove 117 such that the communication angle θ, which is the angle at which the inner circumferential side space 106i of the piston 106 and the suction chamber 110 communicate, satisfies 0° < θ ≤ 180°.

[0034] More preferably, the position of the oil supply groove 117 is set such that the communication angle satisfies 60° ≤ θ ≤ 100°.(Second Embodiment)

[0035] The following explains a second embodiment using Fig. 4 to 8.[2-1. Configuration]

[0036] Fig. 4 shows a vertical sectional view of a rotary compressor 200 in this embodiment. The rotary compressor 200 of the second embodiment differs from the rotary compressor 100 of the first embodiment in that the rotary compressor 200 is composed of at least two cylinders, a low-stage cylinder 205L and a high-stage cylinder 205H, with a partition plate 209 provided between the low-stage cylinder 205L and the high-stage cylinder 205H.

[0037] The rotary compressor 200 includes a low-stage rotary type compression mechanism 202L that compresses refrigerant, a high-stage rotary type compression mechanism 202H that compresses the refrigerant compressed by the low-stage rotary type compression mechanism 202L, an electric mechanism 203 that drives the low-stage rotary type compression mechanism 202L and the high-stage rotary type compression mechanism 202H, and an oil reservoir 201a that stores lubricating oil at a bottom of a hermetic container 201.

[0038] The interior of the hermetic container 201 is an intermediate pressure atmosphere between low-stage suction pressure sucked into the low-stage rotary type compression mechanism 202L and high-stage discharge pressure discharged from the high-stage rotary type compression mechanism 202H.

[0039] The electric mechanism 203 includes a stator 203a fixed to the hermetic container 201 and a rotor 203b placed inside the stator 203a, with a drive shaft 204 fixed to the rotor 203b.

[0040] Fig. 5 shows an enlarged view of essential parts of the low-stage rotary type compression mechanism 202L and the high-stage rotary type compression mechanism 202H. Fig. 6 shows a compression operation of the low-stage rotary type compression mechanism 202L, and Fig. 7 shows a compression operation of the high-stage rotary type compression mechanism 202H.

[0041] The low-stage rotary type compression mechanism 202L sandwiches the low-stage cylinder 205L, a low-stage piston 206L, and a low-stage vane 207L between the partition plate 209 and a lower end plate 208L. A space formed between the low-stage cylinder 205L and the low-stage piston 206L is divided by the low-stage vane 207L into a low-stage suction chamber 210L and a low-stage compression chamber 211L. A low-stage eccentric shaft 204L is housed inside the low-stage cylinder 205L, and the low-stage eccentric shaft 204L is rotatably fitted to the low-stage piston 206L.

[0042] The high-stage rotary type compression mechanism 202H, which is stacked and installed on the axially upper part of the low-stage rotary type compression mechanism 202L, sandwiches the high-stage cylinder 205H, a high-stage piston 206H, and a high-stage vane 207H between the partition plate 209 and an upper end plate 208H. A space formed between the high-stage cylinder 205H and the high-stage piston 206H is divided by the high-stage vane 207H into a high-stage suction chamber 210H and a high-stage compression chamber 211H. A high-stage eccentric shaft 204H is housed inside the high-stage cylinder 205H, and the high-stage eccentric shaft 204H is rotatably fitted to the high-stage piston 206H.

[0043] A low-stage cover 213L is placed on the axially lower part of the lower end plate 208L, forming a low-stage discharge space 214L between the lower end plate 208L and the low-stage cover 213L. The low-stage discharge space 214L communicates with the low-stage compression chamber 211L through a low-stage discharge hole (not shown) equipped with a low-stage check valve (not shown). The low-stage discharge space 214L also communicates with the interior of the hermetic container 201 through a low-stage discharge passage (not shown) that passes axially from a high-stage cover 213H to the lower end plate 208L.

[0044] The high-stage cover 213H is placed on the axially upper part of the upper end plate 208H, forming a high-stage discharge space 214H between the upper end plate 208H and the high-stage cover 213H. The high-stage discharge space 214H communicates with the high-stage compression chamber 211H through a high-stage discharge hole (not shown) equipped with a high-stage check valve (not shown).

[0045] In this embodiment, the upper end plate 208H serves as an upper bearing, and the lower end plate 208L serves as a lower bearing.

[0046] A low-stage suction pipe 215L is inserted into the low-stage cylinder 205L, communicating with the low-stage suction chamber 210L through a low-stage suction passage 212L. A low-stage discharge pipe 216L is connected to the hermetic container 201, communicating with the interior of the hermetic container 201.

[0047] A high-stage suction pipe 215H is inserted into the upper end plate 208H, communicating with the high-stage suction chamber 210H through a high-stage suction passage 212H. A high-stage discharge pipe 216H is also inserted into the upper end plate 208H, communicating with the high-stage discharge space 214H.

[0048] The low-stage cover 213L separates the intermediate pressure low-stage discharge pressure refrigerant compressed immediately after the low-stage rotary type compression mechanism 202L from the lubricating oil stored in the oil reservoir 201a, preventing the lubricating oil from flowing out of the hermetic container 201 due to agitation by the low-stage discharge pressure refrigerant.

[0049] The high-stage cover 213H separates the intermediate pressure low-stage discharge pressure refrigerant inside the hermetic container 201 from the discharge pressure refrigerant inside the high-stage discharge space 214H.

[0050] The high-stage cover 213H, the upper end plate 208H, the high-stage cylinder 205H, the partition plate 209, the low-stage cylinder 205L, the lower end plate 208L, and the low-stage cover 213L are fastened in the axial direction by multiple fastening bolts (not shown).

[0051] As shown in Fig. 7, an oil supply groove 217 intermittently communicates the inner circumferential side space 206i of the high-stage piston 206H with the high-stage suction chamber 210H as the high-stage piston 206H rotates eccentrically. At a crank angle where the inner circumferential side space 206i of the high-stage piston 206H and the high-stage suction chamber 210H are in communication with each other through the oil supply groove 217, oil is supplied from the inner circumferential side space 206i of the high-stage piston 206H to the high-stage suction chamber 210H. By altering a position of the oil supply groove 217, the crank angle to communicate between the inner circumferential side space 206i and the high-stage suction chamber 210H can be set arbitrarily. Here, the crank angle during the state where the inner circumferential side space 206i of the high-stage piston 206H is communicated to the high-stage suction chamber 210H through the oil supply groove 217 is referred to as the communication angle.

[0052] However, in this embodiment, the oil supply groove 217 is provided on the partition plate 209, but the oil may be provided on the upper end plate 208H. Also, the oil supply groove 217 may be provided on both the upper end plate 208H and the partition plate 209.[2-2-1. Compression Operation]

[0053] The compression operation of the rotary compressor 200 including low-stage rotary type compression mechanism 202L and high-stage rotary type compression mechanism 202H is similar to that of the rotary compressor 100 in the first embodiment. However, the low-stage rotary type compression mechanism 202L and the high-stage rotary type compression mechanism 202H perform compression in reverse phase.

[0054] The low-stage suction refrigerant at the suction pressure sucked from the low-stage suction pipe 215L is sucked into the low-stage suction chamber 210L through the low-stage suction passage 212L, compressed to intermediate pressure by the low-stage rotary type compression mechanism 202L, and then discharged into the low-stage discharge space 214L. This intermediate pressure low-stage discharge refrigerant flows out to the interior of the hermetic container 201 through the low-stage discharge passage passing axially from the lower end plate 208L to the high-stage cover 213H, and is discharged to the outside of the hermetic container 201 through the low-stage discharge pipe 216L. The low-stage discharge refrigerant is either sucked directly into the high-stage suction chamber 210H from the high-stage suction pipe 215H after passing through a gas cooler, or mixed with refrigerant from an injection circuit and then sucked into the high-stage suction chamber 210H from the high-stage suction pipe 215H.

[0055] The high-stage suction refrigerant sucked into the high-stage suction chamber 210H is compressed to discharge pressure by the high-stage rotary type compression mechanism 202H, and then discharged to the outside of the hermetic container 201 through the high-stage discharge space 214H and the high-stage discharge pipe 216H.

[0056] When incorporating an injection circuit into the refrigeration cycle, an economizer cycle can be constructed, enabling further capacity improvement as well as improving refrigeration cycle efficiency by reducing temperature of the high-stage discharge refrigerant of the rotary compressor 200.

[0057] While the rotary compressor 100 in the first embodiment is a single-stage compression method that compresses from suction pressure to discharge pressure in one rotary type compression mechanism 102, the rotary compressor 200 in the second embodiment is a two-stage compression method that compresses with the low-stage rotary type compression mechanism 202L and the high-stage rotary type compression mechanism 202H.[2-2-2. Oil Supply Operation]

[0058] The lubricating oil is stored in the oil reservoir 201a at the bottom of the hermetic container 201, and normally, the lubricating oil is immersed at least up to the height of the upper end of the low-stage cylinder 205L of the low-stage rotary type compression mechanism 202L. A lubricating oil passage 218 is provided in the axial direction inside the drive shaft 204. Lubricating oil sucked up from the oil reservoir 201a into the lubricating oil passage 218 by an oil pump mechanism reaches the inner circumferential side space 206i of the high-stage piston 206H through a low-stage oil supply hole 219L provided in the low-stage eccentric shaft 204L and a high-stage oil supply hole 219H provided in the high-stage eccentric shaft 204H, while lubricating the sliding parts of the low-stage eccentric shaft 204L and the high-stage eccentric shaft 204H. After that, the lubricating oil lubricates journal bearing sliding parts of the lower end plate 208L and the upper end plate 208H before being discharged outside the low-stage rotary type compression mechanism 202L and the high-stage rotary type compression mechanism 202H.

[0059] A portion of the lubricating oil that reaches the inner circumferential side space 206i of the high-stage piston 206H is intermittently supplied to the high-stage suction chamber 210H through the oil supply groove 217, lubricating the sliding parts between the high-stage piston 206H and the upper end plate 208H and the partition plate 209, and sealing minute gaps in the sliding parts. The lubricating oil supplied to the high-stage suction chamber 210H continues to seal the minute gaps in the sliding parts even after the high-stage suction chamber 210H becomes the high-stage compression chamber 211H, and is discharged from the high-stage discharge hole along with the refrigerant.[2-3. Effects]

[0060] Normally, in a two-stage compressor where the interior of the hermetic container 201 becomes an intermediate pressure atmosphere, it is difficult to supply lubricating oil from the interior of the hermetic container 201 to the high-stage compression chamber 211H because pressure of the refrigerant compressed in the high-stage rotary type compression mechanism 202H becomes higher than the intermediate pressure inside the hermetic container 201.

[0061] Also, if a path is provided to return excess lubricating oil contained in the refrigerant to the interior of the hermetic container 201 in a process of discharging the refrigerant compressed by the high-stage rotary type compression mechanism 202H to the outside of the hermetic container 201, the pressure inside the hermetic container 201 increases as the lubricating oil and the refrigerant at pressure higher than the intermediate pressure return to the inside of the hermetic vessel 201, resulting in a decrease in the compressor efficiency. Therefore, it is difficult to provide an oil return path, and the lubricating oil supplied to the high-stage rotary type compression mechanism 202H is discharged to the outside of the hermetic container 201 without modification. For these reasons, in the two-stage compressor where the interior of the hermetic container 201 becomes the intermediate pressure atmosphere, it is important to properly maintain the amount of oil supply to the high-stage rotary type compression mechanism 202H.

[0062] Since this embodiment supplies the oil to the high-stage suction chamber 210H through the oil supply groove 217, it is possible to supply the lubricating oil necessary for sealing the minute gaps and lubricating sliding parts to the high-stage compression chamber 211H. Therefore, it can achieve improved sealing of the high-stage rotary type compression mechanism 202H and improved reliability through lubrication of sliding parts.

[0063] Furthermore, the structure allows for intermittent oil supply as the high-stage piston 206H eccentrically rotates, the amount of the oil supply can be adjusted by opening time and pressure difference. This allows for increased oil supply under low rotation conditions or high differential pressure conditions where it is desirable to increase the oil supply amount, and conversely, suppression of oil supply under high rotation conditions or low differential pressure conditions. As a result, it is possible to properly maintain the oil supply amount to the high-stage rotary type compression mechanism 202H over the wide operating range, achieving high efficiency, high reliability, and expansion of the operating range. Additionally, by adjusting the oil supply amount to the high-stage rotary type compression mechanism 202H, it is possible to suppress the amount of lubricating oil flowing out to the refrigeration cycle, which is also effective in improving the efficiency of the refrigeration cycle.

[0064] Also, the rotary compressor 200 of this second embodiment sets the position of the oil supply groove 217 such that the communication angle θ, which is the angle at which the inner circumferential side space 206i of the high-stage piston 206H and the high-stage suction chamber 210H communicate during one rotation, satisfies 0° < θ ≤ 180°.

[0065] More preferably, the position of the oil supply groove 217 is set such that the communication angle satisfies 60° ≤ θ ≤ 100°.

[0066] Fig. 8 shows OCR ratio and COP ratios when the horizontal axis is the communication angle of the oil supply groove 217 or the oil supply groove 117 in the high-stage rotary type compression mechanism 202H or the rotary compressor 200 and the vertical axis is the opening angle is 0° at 100%. As shown in Fig. 8, if θ = 0°, it becomes impossible to supply lubricating oil to the high-stage suction chamber 210H, and performance deterioration due to deteriorated sealing performance occurs under low rotation conditions where it is desirable to increase the oil supply amount. There is also concern about seizure of sliding parts due to insufficient oil supply to the sliding parts. On the other hand, in the present invention, since θ > 0°, the lubricating oil can be reliably supplied to the high-stage suction chamber 210H, preventing the performance deterioration due to the deteriorated sealing performance under low rotation conditions. It can also prevent seizure of sliding parts by supplying lubricating oil, thereby expanding the operating range at low rotations.

[0067] Also, if θ > 180°, the oil supply amount to the high-stage suction chamber 210H would become excessive under high rotation conditions, and the performance deterioration due to decreased volumetric efficiency occurs. There is also concern about decreased cycle efficiency due to increased OCR and increased amount of lubricating oil discharged outside the hermetic container 201. On the other hand, in the present invention, since θ ≤ 180°, it is possible to suppress the performance deterioration and OCR increase under the high rotation conditions, enabling expansion of the operating range at high rotations.

[0068] From the above, by setting 0° < θ ≤ 180°, high efficiency and high reliability of the rotary compressor 200 can be realized over a wider range of rotation speeds.

[0069] Regarding the OCR ratio, little change is observed from an opening angle of 0° to around 180°. On the other hand, regarding the COP ratio, it peaks at around 60° to 180° at the low rotations, and at around 60° to 100° at the high rotations.

[0070] From this, the communication angle of 60° to 100° is more preferable as it can suppress the rise in OCR and maintain high COP over the wide operating range.

[0071] Also, in this second embodiment, the cross-section perpendicular to a flow direction of the oil supply groove 217 formed in the rotary compressor 200 is shaped to satisfy 0.3 mm ≤ A ≤ 1.5 mm with a hydraulic diameter as A.

[0072] Here, the hydraulic diameter refers to a diameter of a circular pipe equivalent to the cross-section of the oil supply groove 217. For example, Fig. 9 shows the cross-section perpendicular to the flow direction of the oil supply groove 217 in the second embodiment. Fig. 9 is a B-B cross-section of Fig. 7, and a groove width h and a groove height t shown in Fig. 9 satisfy the above range of the hydraulic diameter A.

[0073] If A < 0.3 mm, the oil supply effect due to pressure difference becomes small, and performance deterioration due to deteriorated sealing performance occurs under high differential pressure conditions where it is desirable to increase the oil supply amount. On the other hand, according to the present invention, a predetermined amount of lubricating oil can be supplied to the high-stage suction chamber 210H, enabling expansion of the operating range under high differential pressure conditions.

[0074] Also, if A > 1.5 mm, the oil supply amount to the high-stage suction chamber 210H would become excessive under low differential pressure conditions, leading to performance deterioration due to decreased volumetric efficiency and decreased cycle efficiency due to increased OCR. On the other hand, according to the present invention, by setting A ≤ 1.5 mm, it is possible to suppress the oil supply amount to the high-stage suction chamber 210H, enabling the expansion of the operating range under the low differential pressure conditions.

[0075] From the above, by setting 0.3 mm ≤ A ≤ 1.5 mm, the high efficiency and high reliability of the rotary compressor 200 can be realized over a wider range of a compression ratio conditions.

[0076] However, while the B-B cross-sectional shape of the oil supply groove 217 in this embodiment is a rectangular shape, it is not limited to the rectangular shape. For example, it may be a V-shape as shown in Fig. 10, or a shape with curvature as shown in Fig. 11.

[0077] Also, while the oil supply groove 217 in this embodiment is a straight shape, it is not limited to the straight shape. For example, it may be a non-linear shape as shown in Fig. 12.

[0078] Further, natural refrigerants, HFC refrigerants, HCFC refrigerants, HC refrigerants, or HFO refrigerants can be used as refrigerants. Particularly when using carbon dioxide, which tends to have a large pressure difference between the inner circumferential side space 206i of the high-stage piston 206H and the high-stage compression chamber 211H, and where a refrigerant leakage from end faces of the high-stage piston 206H and the upper end plate 208H and partition plate 209 tends to increase, it is possible to reduce the refrigerant leakage from the upper and lower end faces of the high-stage piston 206H. Also, by enabling oil supply to the sliding surfaces between the high-stage piston 206H and the upper end plate 208H and partition plate 209, the sliding condition on the sliding surfaces described above can be alleviated, to achieve the high efficiency and high reliability more effectively.

[0079] It should be noted that the above-described embodiments are for illustrating the technology of this disclosure, and therefore, within the scope of the claims or their equivalents, various changes, substitutions, additions, omissions, etc. can be made.[INDUSTRIAL APPLICABILITY]

[0080] According to the present invention, it is possible to optimize an oil supply amount over a wide operating range and simultaneously achieve high efficiency and high reliability.[DESCRIPTION OF SYMBOLS]

[0081] 100Rotary compressor 101Hermetic container 101aOil reservoir 102Rotary type compression mechanism 103Electric mechanism 103aStator 103bRotor 104Drive shaft 104aEccentric shaft 105Cylinder 106Piston 106iInner circumferential side space 107Vane 108Upper end plate 109Lower end plate 110Suction chamber 111Compression chamber 112Suction passage 113Suction pipe 114Cover 115Discharge space 116Discharge pipe 117Oil supply groove 118Lubricating oil passage 119Oil supply hole 200Rotary compressor 201Hermetic container 201aOil reservoir 202LLow-stage rotary type compression mechanism 202HHigh-stage rotary type compression mechanism 203Electric mechanism 203aStator 203bRotor 204Drive shaft 204LLow-stage eccentric shaft 204HHigh-stage eccentric shaft 205LLow-stage cylinder 205HHigh-stage cylinder 206LLow-stage piston 206HHigh-stage piston 206iinner circumferential side space 207LLow-stage vane 207HHigh-stage vane 208LLower end plate 208HUpper end plate 209Partition plate 210LLow-stage suction chamber 210HHigh-stage suction chamber 211LLow-stage compression chamber 211HHigh-stage compression chamber 212LLow-stage suction passage 212HHigh-stage suction passage 213LLow-stage cover 213HHigh-stage cover 214LLow-stage discharge space 214HHigh-stage discharge space 215LLow-stage suction pipe 215HHigh-stage suction pipe 216LLow-stage discharge pipe 216HHigh-stage discharge pipe 217oil supply groove 218Lubricating oil passage 219LLow-stage oil supply hole 219HHigh-stage oil supply hole

Claims

1. A rotary compressor comprising: a hermetic container having therein a rotary type compression mechanism that compresses refrigerant, an electric mechanism that drives the rotary type compression mechanism, and an oil reservoir that stores lubricating oil at a bottom of the hermetic container; wherein the rotary type compression mechanism has a piston, a cylinder, a vane, an upper end plate, and a lower end plate; a compression chamber and a suction chamber are formed by dividing a space formed by the piston and the cylinder with the vane; the upper end plate and the lower end plate close upper and lower opening surfaces of the compression chamber and the suction chamber; an oil supply groove that intermittently communicates an inner circumferential side space of the piston with the suction chamber is formed on at least one of either the upper end plate or the lower end plate, and oil is supplied from the inner circumferential side space of the piston to the suction chamber through the oil supply groove.

2. A rotary compressor comprising: a hermetic container having therein a low-stage rotary type compression mechanism that compresses refrigerant, a high-stage rotary type compression mechanism that compresses refrigerant compressed by the low-stage rotary type compression mechanism, an electric mechanism that drives the low-stage rotary type compression mechanism and the high-stage rotary type compression mechanism, and an oil reservoir that stores lubricating oil at a bottom of the hermetic container; wherein the high-stage rotary type compression mechanism has a high-stage piston, a high-stage cylinder, a high-stage vane, an upper end plate, and a partition plate; the low-stage rotary type compression mechanism has a low-stage piston, a low-stage cylinder, a low-stage vane, a lower end plate, and the partition plate; a high-stage compression chamber and a high-stage suction chamber are formed by dividing a space formed by the high-stage piston and the high-stage cylinder with the high-stage vane; the upper end plate and the partition plate close upper and lower opening surfaces of the high-stage compression chamber and the high-stage suction chamber; an oil supply groove that intermittently communicates an inner circumferential side space of the high-stage piston with the high-stage suction chamber is formed on at least one of either the upper end plate or the partition plate, and oil is supplied from the inner circumferential side space of the high-stage piston to the high-stage suction chamber through the oil supply groove.

3. The rotary compressor according to claim 1 or claim 2, wherein the oil supply groove communicates for a communication angle in a range of 0° < θ ≤ 180° during one rotation.

4. The rotary compressor according to claim 1 or claim 2, wherein a cross-section perpendicular to a flow direction of the oil supply groove has a shape that satisfies 0.3 mm ≤ A ≤ 1.5 mm, where A is a hydraulic diameter.

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