EP3617514B1

EP3617514B1 - Internal medium pressure type two-stage compression compressor

Info

Publication number: EP3617514B1
Application number: EP18790603.7A
Authority: EP
Inventors: Akira Matsuzaki; Takashi Sato
Original assignee: Panasonic Intellectual Property Management Co Ltd
Current assignee: Panasonic Intellectual Property Management Co Ltd
Priority date: 2017-04-28
Filing date: 2018-04-24
Publication date: 2023-02-22
Anticipated expiration: 2038-04-24
Also published as: EP3617514A4; EP3617514A1; CN110573741A; JP2018188986A; WO2018199061A1

Description

[TECHNICAL FIELD]

The present invention relates to an internal medium pressure type two-stage compression compressor which is suitable especially when carbon dioxide is used as refrigerant.

[BACKGROUND TECHNIQUE]

Patent document 1 discloses an internal medium pressure type two-stage compression compressor.
In patent document 1, a through hole is formed in an intermediate partition plate. According to this, oil is pumped up from an oil reservoir in a bottom in an airtight container, the oil rises through an in-shaft oil supply passage and comes out from the in-shaft oil supply passage, the oil enters the through hole of the intermediate partition plate, the oil passes there, and the oil is supplied toward a low pressure chamber (suction side) of a high-stage side cylinder.
Inner pressure (suction pressure) in the low pressure chamber of the high-stage side cylinder becomes lower than pressure on the side of an inner peripheral edge of the intermediate partition plate by suction pressure loss in suction process. By this pressure difference, oil in the high-stage side cylinder is injected from the in-shaft oil supply passage into the low pressure chamber in the high-stage side cylinder through the through hole of the intermediate partition plate, and the oil is supplied.
Patent document 2 discloses an internal intermediate pressure multistage compression type rotary compressor. A lubrication groove for providing communication between an oil bore and a low-pressure chamber in a cylinder is formed in a surface of an intermediate partitioner that is adjacent to the cylinder of a second rotary compressing element. Furthermore, a through bore for providing communication between a hermetically sealed vessel and an inside of a roller is formed in the intermediate partitioner.
Patent document 3 discloses a rotary compressor, wherein a roller is fitted between an upper cylinder constituting a second rotary compression element and an eccentric portion formed on a rotary shaft of an electric element so as to rotate eccentrically in the upper cylinder. A vane is brought in contact with the roller to divide the upper cylinder into a low pressure chamber and a high pressure chamber. A back pressure chamber is defined to apply back pressure to the vane. A back pressure passage is defined to interconnect the high pressure chamber in the upper cylinder and the back pressure chamber. A check valve is disposed in the back pressure passage to permit a flow of gas from the high pressure chamber in the upper cylinder to the back pressure chamber and to block a flow of gas from the back pressure chamber to the high pressure chamber in the upper cylinder.
Patent document 4 discloses a rolling-piston type compressor, wherein a direction of an intake port for an inner surface of a cylinder is varied without varying a position of an opening of the intake port on an inner surface of the cylinder. Therefore, the shape of the intake port on the inner surface of the cylinder is changed to an elliptical form from its original circular form, and the area of the intake port is increased. Further, the intake port is continuous to the sliding groove on a partitioning plate so that a perfect closing of the intake port by a rotor is prevented.
Patent document 5 discloses a rotary compressor.

[PRIOR ART DOCUMENTS]

[Patent Documents]

[Patent Document 1] Japanese Patent Application Laid-open No.2004-293333
[Patent Document 2] US Patent Application Laid-open No. 2004/0208769
[Patent Document 3] Japanese Patent Application Laid-open No. 2003-254276
[Patent Document 4] Japanese Patent Application Laid-open No. 57-206790
[Patent Document 5] Japanese Patent Application Laid-open No. 2013-185496

[SUMMARY OF THE INVENTION]

[PROBLEM TO BE SOLVED BY THE INVENTION]

Fig. 4(a) is a plan view of essential portions of a compression mechanism on the high-stage side of the internal medium pressure type two-stage compression compressor as disclosed in patent document 1.
Fig. 4(b) is an enlarged plan view of essential portions of Fig. 4(a).
The compression mechanism 100 includes a cylinder 101, a piston 102 placed in the cylinder 101 and a vane 103 which divides an interior of the cylinder 101.
In Figs. 4, an oil supply passage 105 is formed in a suction passage 104 of the compression mechanism 100.
As shown in Fig. 4(b), when the piston 102 turns from a top dead center to a position of the suction passage 104, a closed space 106 is formed between the vane 103, the cylinder 101 and the piston 102.
The closed space 106 is in a negative pressure state, the piston 102 turns to the position of the suction passage 104, and if the closed space 106 comes into communication with the suction passage 104, suction pressure in the suction passage 104 is lowered by the closed space 106.
As a result, a pressure difference between a case inner pressure in the airtight container and suction pressure becomes large, lubricant oil more than a set value flows from the oil supply passage 105 into a compression chamber, and a discharge amount of the lubricant oil from the high-stage side increases adversely.
In the internal medium pressure type two-stage compression compressor, since refrigerant is directly discharged outside of the airtight container from the high-stage side compression mechanism, OCR (lubricant oil circulation ratio) is high as compared with an internal high pressure type two-stage compression compressor which discharges refrigerant into an airtight container and lubricant oil is separated and collected in the airtight container, and compressor volumetric efficiency and refrigeration cycle efficiency are deteriorated.
Thereupon, it is an object of the present invention to provide an internal medium pressure type two-stage compression compressor capable of preventing lubricant oil from flowing into a high-stage side compression chamber more than a set value.

[MEANS FOR SOLVING THE PROBLEM]

The object is achieved by providing an internal medium pressure type two-stage compression compressor as defined in appended claim 1.
The internal medium pressure type two-stage compression compressor of the present invention comprises a motor and a compression mechanism in an airtight container, in which the motor and the compression mechanism are connected to each other through a shaft, the compression mechanism includes a cylinder, a piston placed in the cylinder and a vane for partitioning an interior of the cylinder, the compression mechanism includes a first compression mechanism which carries out first stage low stage compression, and a second compression mechanism which carries out second stage high stage compression, an oil supply passage is formed in a suction passage of the second compression mechanism, refrigerant gas which is compressed by the first compression mechanism is discharged into the airtight container, the refrigerant gas is compressed by the second compression mechanism and discharged outside the airtight container, and oil is supplied to a second compression chamber of the second compression mechanism from the oil supply passage by a pressure difference between case internal pressure in the airtight container and suction pressure in the suction passage of the second compression mechanism, wherein when the piston turns from a top dead center to a position of the suction passage, a closed space is not formed between the vane, the cylinder and the piston.
According to a first embodiment of the present invention, in the internal medium pressure type two-stage compression compressor, a pressure communication groove is formed in a vane-side wall surface located on a side of the vane of the suction passage.
According to a second embodiment of the present invention, in the internal medium pressure type two-stage compression compressor described in the first embodiment, the pressure communication groove is formed from an arc surface centering on a phantom center axis which is parallel to a center axis of the shaft.
According to a third embodiment of the present invention, in the internal medium pressure type two-stage compression compressor described in the second embodiment, the arc surface is formed from one of end surfaces to an other end surface of the cylinder.
According to a fourth embodiment of the present invention, in the internal medium pressure type two-stage compression compressor described in the second or third embodiment, a curved surface having a same curvature as the arc surface centering on the phantom center axis is formed on an anti-vane-side wall surface which is opposed to the vane-side wall surface.
According to a fifth embodiment of the present invention, in the internal medium pressure type two-stage compression compressor of the invention or described in any one of the first to fourth embodiments, a lower end of the shaft includes an oil pickup, an in-shaft oil supply passage through which lubricant oil pumped up by the oil pickup passes is formed in the shaft, an intermediate partition plate is provided between the first compression mechanism and the second compression mechanism, and an in-intermediate partition plate oil supply passage which introduces the lubricant oil of the in-shaft oil supply passage to the oil supply passage is formed in the intermediate partition plate.
According to a sixth embodiment of the present invention, in the internal medium pressure type two-stage compression compressor of the invention or described in any one of the first to fifth embodiments, carbon dioxide is used as refrigerant which is compressed by the compression mechanism.

[EFFECT OF THE INVENTION]

According to the present invention, it is possible to prevent lubricant oil from flowing into a second compression chamber more than a set value, and suppress a discharge amount of lubricant oil from the second compression chamber.

[BRIEF DESCRIPTION OF THE DRAWINGS]

Fig. 1 is a sectional view of an internal medium pressure type two-stage compression compressor according to an embodiment of the present invention;
Fig. 2 is an enlarged sectional view of essential portions of Fig. 1;
Figs. 3 are plan views of essential portions of a high-stage side compression mechanism of the internal medium pressure type two-stage compression compressor; and
Figs. 4 are plan views of essential portions of a high-stage side compression mechanism of a conventional internal medium pressure type two-stage compression compressor.

[MODE FOR CARRYING OUT THE INVENTION]

According to the present invention, when a piston turns from a top dead center to a position of a suction passage, a closed space is not formed between a vane, a cylinder and the piston. By eliminating reduction in suction pressure generated by the closed space, it is possible to prevent lubricant oil from flowing into a second compression chamber more than a set value, and suppress a discharge amount of lubricant oil from the second compression chamber.
In an embodiment of the invention, a pressure communication groove is formed in a vane-side wall surface located on a side of the vane of the suction passage. By forming the pressure communication groove, it is possible to eliminate the closed space which is formed when the piston turns from a top dead center to a position of a suction passage and which is located between the vane, the cylinder and the piston.
In an embodiment of the invention, the pressure communication groove is formed from an arc surface centering on a phantom center axis which is parallel to a center axis of the shaft. Thereby, it is possible to suppress surface pressure of the vane and a vane groove, and form the pressure communication groove.
In an embodiment of the invention, the arc surface is formed from one of end surfaces to an other end surface of the cylinder. Thereby, the pressure communication groove can be formed by a rotary cutting processing.
In an embodiment of the invention, a curved surface having a same curvature as the arc surface centering on the phantom center axis is formed on an anti-vane-side wall surface which is opposed to the vane-side wall surface. Thereby, it is possible to form the pressure communication groove and an excluded volume adjusting space at the same time.
In an embodiment of the invention, a lower end of the shaft includes an oil pickup, an in-shaft oil supply passage through which lubricant oil pumped up by the oil pickup passes is formed in the shaft, an intermediate partition plate is provided between the first compression mechanism and the second compression mechanism, and an in-intermediate partition plate oil supply passage which introduces the lubricant oil of the in-shaft oil supply passage to the oil supply passage is formed in the intermediate partition plate. By utilizing pressure drop when refrigerant is sucked, it is possible to supply lubricant oil in the airtight container to the suction passage of a second compression mechanism.
In an embodiment of the invention, carbon dioxide is used as refrigerant which is compressed by the compression mechanism. Thus, even when carbon dioxide having high refrigerant pressure and having a large pressure difference between suction and discharge is used as refrigerant, since internal pressure of the airtight container is set to medium pressure. Therefore, it is possible to thin a thickness of the airtight container, the airtight container can be reduced in size and weight, and since a pressure difference per one stage is reduced. Hence, volumetric efficiency is enhanced.

[Embodiment]

One embodiment of the present invention will be described below with reference to drawings.
Fig. 1 is a sectional view of an internal medium pressure type two-stage compression compressor according to the embodiment, and Fig. 2 is an enlarged sectional view of essential portions of Fig. 1.
The internal medium pressure type two-stage compression compressor of the embodiment includes a motor 20 and a compression mechanism 30 in an airtight container 10. The motor 20 and the compression mechanism 30 are connected to each other through a shaft 40.
The motor 20 is composed of a stator 21 fixed to an inner surface of the airtight container 10 and a rotor 22 which rotates in the stator 21.
The internal medium pressure type two-stage compression compressor of the embodiment includes, as the compression mechanism 30, a first compression mechanism 30A which carries out first stage low stage compression, and a second compression mechanism 30B which carries out second stage high stage compression.
The first compression mechanism 30A includes a first cylinder 31A, a first piston 32A placed in the first cylinder 31A, and a vane (not shown) which partitions an interior of the first cylinder 31A. If the first piston 32A orbits in the first cylinder 31A, low pressure refrigerant gas is sucked and compressed.
Like the first compression mechanism 30A, the second compression mechanism 30B includes a second cylinder 31B, a second piston 32B placed in the second cylinder 31B, and a vane 33 (see Fig. 3(a)) which partitions an interior of the second cylinder 31B. If the second piston 32B orbits in the second cylinder 31B, medium pressure refrigerant gas is sucked and compressed.
A lower bearing 51 is placed on one of surfaces of the first cylinder 31A, and an intermediate partition plate 52 is placed on the other surface of the first cylinder 31A.
The intermediate partition plate 52 is placed on one of surfaces of the second cylinder 31B, and an upper bearing 53 is placed on the other surface of the second cylinder 31B.
That is, the intermediate partition plate 52 partitions into the first cylinder 31A and the second cylinder 31B. The intermediate partition plate 52 has an opening which is larger than a diameter of the shaft 40.
The shaft 40 is composed of a main bearing 41 which mounts the rotor 22 and which is supported by the lower bearing 51, a first eccentric core 42 which mounts the first piston 32A, a second eccentric core 43 which mounts the second piston 32B, and an auxiliary bearing 44 which is supported by the lower bearing 51.
The first eccentric core 42 and the second eccentric core 43 are formed such that phases thereof are different from each other 180°, and a connecting shaft 45 is formed between the first eccentric core 42 and the second eccentric core 43.
A first compression chamber 34A is formed between an inner peripheral surface of the first cylinder 31A and an outer peripheral surface of the first piston 32A between the lower bearing 51 and the intermediate partition plate 52. A second compression chamber 34B is formed between an inner peripheral surface of the second cylinder 31B and an outer peripheral surface of the second piston 32B between the intermediate partition plate 52 and the upper bearing 53.
An excluded volume ratio of high pressure compression excluded volume of the second compression mechanism 30B to low pressure compression excluded volume of the first compression mechanism 30A is set to 5% to 110%.
An oil reservoir 11 is formed in a bottom in the airtight container 10, and a lower end of the shaft 40 is provided with an oil pickup 12.
An in-shaft oil supply passage 46 is formed in the shaft 40 in its axial direction. A communication passage 47 for supplying oil to a sliding surface of the compression mechanism 30 is formed in the in-shaft oil supply passage 46.
The communication passage 47 is formed in the first eccentric core 42 and the second eccentric core 43.
An oil supply passage 36 is formed in a suction passage 35B of the second compression mechanism 30B.
An in-intermediate partition plate oil supply passage 60 for introducing lubricant oil of the in-shaft oil supply passage 46 to the oil supply passage 36 is formed in the intermediate partition plate 52.
The in-intermediate partition plate oil supply passage 60 is composed of a first passage 61 extending from an inner peripheral surface 52a to an outer peripheral surface 52b of the intermediate partition plate 52, and a second passage 62 whose one end opens into the first passage 61 and whose other end opens into the oil supply passage 36.
A first intake tube 13A and a second intake tube 13B are connected to a side surface of the airtight container 10, and an intermediate pressure discharge tube 14 and a discharge tube (not shown) are connected to the airtight container 10. The intermediate pressure discharge tube 14 is connected to an intermediate pressure discharge port 15.
The first intake tube 13A is connected to a suction passage 35A of the first compression mechanism 30A, and a second intake tube 13B is connected to the suction passage 35B of the second compression mechanism 30B.
The suction passage 35A is connected to the first compression chamber 34A, and the suction passage 35B is connected to the second compression chamber 34B.
The intermediate pressure discharge tube 14 is connected to an intercooler 16 which cools medium pressure refrigerant gas, and the intercooler 16 is connected to the second intake tube 13B.
A lower portion of the lower bearing 51 is provided with a cup muffler 71, and an upper portion of the upper bearing 53 is provided with an upper cover 72. A first silencing chamber 81 is formed between the lower bearing 51 and the cup muffler 71, and a second silencing chamber 82 is formed between the upper bearing 53 and the upper cover 72.
Medium pressure refrigerant gas compressed by the first compression chamber 34A is discharged into the first silencing chamber 81, and high pressure refrigerant gas compressed by the second compression chamber 34B is discharged into the second silencing chamber 82.
The first piston 32A and the second piston 32B orbit in the first compression chamber 34A and the second compression chamber 34B by rotation of the shaft 40.
Gas refrigerant sucked from the first intake tube 13A into the first compression chamber 34A through the suction passage 35A is compressed by the first compression chamber 34A and then, the gas refrigerant is discharged into the first silencing chamber 81 by orbiting motion of the first piston 32A.
Medium pressure refrigerant gas discharged into the first silencing chamber 81 is discharged into the airtight container 10 through the lower bearing 51, the first cylinder 31A, the intermediate partition plate 52, the second cylinder 31B and a refrigerant passage (not shown) formed in the upper bearing 53.
The medium pressure refrigerant gas discharged into the airtight container 10 is introduced from the intermediate pressure discharge port 15 into the intermediate pressure discharge tube 14, the medium pressure refrigerant gas is further cooled by the intercooler 16 and then, the refrigerant gas is introduced into the second intake tube 13B.
Gas refrigerant sucked from the second intake tube 13B into the second compression chamber 34B through the suction passage 35B by the orbiting motion of the second piston 32B is compressed by the second compression chamber 34B and then, the gas refrigerant is discharged into the second silencing chamber 82.
High pressure refrigerant gas discharged into the second silencing chamber 82 is discharged outside the airtight container 10 from the discharge tube (not shown). The high pressure refrigerant gas discharged outside the airtight container 10 through a radiator, a decompressor and an evaporator, becomes low pressure refrigerant gas, and is introduced into the first intake tube 13A.
Lubricant oil sucked from the oil reservoir 11 by rotation of the shaft 40 is supplied from the communication passage 47 into the compression mechanism 30, and lubricates a sliding surface of the compression mechanism 30.
A portion of lubricant oil supplied from the communication passage 47 is introduced from the in-intermediate partition plate oil supply passage 60 into the second compression chamber 34B of the second compression mechanism 30B through the oil supply passage 36 by pressure in the in-shaft oil supply passage 46, i.e., by a pressure difference between case internal pressure in the airtight container 10 and suction pressure in the suction passage 35B of the second compression mechanism 30B.
Fig. 3(a) is a plan view of essential portions of a high-stage side compression mechanism of the internal medium pressure type two-stage compression compressor of the embodiment.
Fig. 3(b) is an enlarged plan view of essential portion of Fig. 3(a).
A pressure communication groove 91 is formed in a vane-side wall surface 35B1 located on the side of a vane 33 of the suction passage 35B.
The pressure communication groove 91 is formed from an arc surface centering on a phantom center axis X which is parallel to a center axis of the shaft 40. The pressure communication groove 91 is formed from one of end surfaces to the other end surface of the second cylinder 31B.
A curved surface having the same curvature as the arc surface of the pressure communication groove 91 centering on the phantom center axis X is formed on an anti-vane-side wall surface 35B2 which is opposed to the vane-side wall surface 35B1. According to this, it is possible to form the pressure communication groove 91 and an excluded volume adjusting space 92 at the same time.
By forming the pressure communication groove 91 in this manner, when the second piston 32B turns from the top dead center to the position of the suction passage 35B, the closed space 106 (see Fig. 4(b)) is not formed between the vane 33, the second cylinder 31B and the second piston 32B.
By eliminating reduction in suction pressure generated by the closed space 106 shown in Fig. 4(b), it is possible to prevent lubricant oil from flowing into the second compression chamber 34B more than a set value, and suppress the discharge amount of the lubricant oil from the second compression chamber 34B.
According to the embodiment, by forming the pressure communication groove 91 from the arc surface centering on the phantom center axis X which is parallel to the center axis of the shaft 40, it is possible to suppress surface pressure of the vane 33 and the vane groove, and form the pressure communication groove 91.
According to the embodiment, by forming the pressure communication groove 91 from the one end surface to the other end surface of the second cylinder 31B, the pressure communication groove 91 can easily be formed by rotary cutting processing.
Further, according to the embodiment, the excluded volume ratio of the high pressure compression excluded volume of the second compression mechanism 30B to the low pressure compression excluded volume of the first compression mechanism 30A is set to 50% to 110%. According to this, a reduction effect of oil discharge amount from the airtight container 10 can be expected.
According to the internal medium pressure type two-stage compression compressor of the embodiment, carbon dioxide can be used as the refrigerant. According to the embodiment, even when carbon dioxide having high refrigerant pressure and having a large pressure difference between suction and discharge is used as the refrigerant, internal pressure of the airtight container 10 is set to medium pressure. Therefore, it is possible to thin a thickness of the airtight container 10, the airtight container 10 can be reduced in size and weight, and a pressure difference per one stage is reduced. Hence, volumetric efficiency is enhanced.

[INDUSTRIAL APPLICABILITY]

Although the present invention has been described based on the internal medium pressure type two-stage compression compressor, the invention can also be applied to a compression chamber having three stages or more.

[EXPLANATION OF SYMBOLS]

10: airtight container
11: oil reservoir
12: oil pickup
13A: first intake tube
13B: second intake tube
14: intermediate pressure discharge tube
15: intermediate pressure discharge port
16: intercooler
20: motor
21: stator
22: rotor
30: compression mechanism
30A: first compression mechanism
30B: second compression mechanism
31A: first cylinder
31B: second cylinder
32A: first piston
32B: second piston
33: vane
34A: first compression chamber
34B: second compression chamber
35A: suction passage
35B: suction passage
36: oil supply passage
40: shaft
41: main bearing
42: first eccentric core
43: second eccentric core
44: auxiliary bearing
45: connecting shaft
46: in-shaft oil supply passage
47: communication passage
51: lower bearing
52: intermediate partition plate
53: upper bearing
60: in-intermediate partition plate oil supply passage
61: first passage
62: second passage
71: cup muffler
72: upper cover
81: first silencing chamber
82: second silencing chamber
91: pressure communication groove
92: excluded volume adjusting space
106: closed space

Claims

An internal medium pressure type two-stage compression compressor comprising a motor (20) and a compression mechanism (30) in an airtight container (10), in which
the motor (20) and the compression mechanism (30) are connected to each other through a shaft (40),

the compression mechanism (30) includes a cylinder (31A, 31B), a piston (32A, 32B) placed in the cylinder (31A, 31B) and a vane (33) for partitioning an interior of the cylinder (31A, 31B),

the compression mechanism (30) includes a first compression mechanism (30A) which carries out first stage low stage compression, and a second compression mechanism (30B) which carries out second stage high stage compression,

an oil supply passage (36) is formed in a suction passage (35B) of the second compression mechanism (30B),

refrigerant gas which is compressed by the first compression mechanism (30A) is discharged into the airtight container (10), the refrigerant gas is compressed by the second compression mechanism (30B) and discharged outside the airtight container (10), and

oil is supplied to a second compression chamber (34B) of the second compression mechanism (30B) from the oil supply passage (36) by a pressure difference between case internal pressure in the airtight container (10) and suction pressure in the suction passage (35B) of the second compression mechanism 30B),

characterized in that when the piston (32B) turns from a top dead center to a position of the suction passage (35B), a closed space is not formed between the vane (33), the cylinder (31B) and the piston (32B).
The internal medium pressure type two-stage compression compressor according to claim 1, wherein
a pressure communication groove (91) is formed in a vane-side wall surface located on a side of the vane (33) of the suction passage (35B).
The internal medium pressure type two-stage compression compressor according to claim 2, wherein
the pressure communication groove (91) is formed from an arc surface centering on a phantom center axis which is parallel to a center axis of the shaft (40).
The internal medium pressure type two-stage compression compressor according to claim 3, wherein
the arc surface is formed from one of end surfaces to an other end surface of the cylinder (31B).
The internal medium pressure type two-stage compression compressor according to claim 3 or 4, wherein
a curved surface having a same curvature as the arc surface centering on the phantom center axis is formed on an anti-vane-side wall surface which is opposed to the vane-side wall surface.
The internal medium pressure type two-stage compression compressor according to any one of claims 1 to 5, wherein
a lower end of the shaft (40) includes an oil pickup,

an in-shaft oil supply passage (46) through which lubricant oil pumped up by the oil pickup passes is formed in the shaft (40),

an intermediate partition plate (52) is provided between the first compression mechanism (30A) and the second compression mechanism (30B), and

an in-intermediate partition plate oil supply passage (60) which introduces the lubricant oil of the in-shaft oil supply passage (46) to the oil supply passage (36) is formed in the intermediate partition plate (52).
The internal medium pressure type two-stage compression compressor according to any one of claims 1 to 6, wherein
carbon dioxide is used as refrigerant which is compressed by the compression mechanism (30).