EP3318759A1

EP3318759A1 - Scroll compressor

Info

Publication number: EP3318759A1
Application number: EP16866107.2A
Authority: EP
Inventors: Masahiro Taniguchi; Yoshiyuki Kimata; Hajime Sato; Yogo Takasu; Youhei Hotta; Taichi Tateishi; Takuma YAMASHITA; Akihiro KANAI
Original assignee: Mitsubishi Heavy Industries Thermal Systems Ltd
Current assignee: Mitsubishi Heavy Industries Thermal Systems Ltd
Priority date: 2015-11-20
Filing date: 2016-10-25
Publication date: 2018-05-09
Also published as: JP2017096145A; WO2017086105A1; EP3318759A4; CN107850069A; CN107850069B

Abstract

A scroll compressor is equipped with: a scroll compression mechanism that is housed in a housing and compresses a low-pressure gas; a motor that is linked to the scroll compression mechanism by a rotary shaft and that drives the scroll compression mechanism; an upper bearing and a lower bearing that support the rotary shaft in a rotatable manner; and an oil supply pump that draws in lubricating oil due to the rotation of the rotary shaft and supplies the lubricating oil to sliding parts. The oil supply pump is a positive-displacement pump which is capable of operating in an operating region wherein the rotational frequency of the motor is 150 rps or higher, and for which an inclination indicating the rate of increase in the amount of oil supplied per unit time with respect to the rotational frequency decreases as the rotational frequency increases.

Description

Technical Field

The present invention relates to a scroll compressor which is used in a refrigerator, an air-conditioning device, or the like.

Background Art

In general, a scroll compressor is widely known, which includes a scroll compression mechanism which is accommodated in a housing and a drive motor which drives the scroll compression mechanism. The scroll compression mechanism is configured to include a fixed scroll member and an orbiting scroll member on which spiral wraps are provided on a surface of a disk-shaped end plate, and in the scroll compression mechanism, a fixed scroll and an orbiting scroll face each other in a state where the spiral wraps mesh with each other and the orbiting scroll revolves around the fixed scroll. In addition, a fluid (gas refrigerant) in the space is compressed by decreasing a volume of a compression space formed between wraps of both scrolls according to orbiting of the orbiting scroll.
In the scroll compressor, in order to prevent seizing of the scroll compression mechanism or a bearing, or to perform cooling, it is necessary to lubricate each sliding portion. In addition, in a case where a fluid leaks from a minute gap between wraps of the fixed scroll and the orbiting scroll, performance of the compressor decreases. Accordingly, a configuration is adopted, in which a lubricant oil is stored in a bottom portion of a housing, a lubricant oil pump is provided in the vicinity of a lower end portion of a rotary shaft of a drive motor, and the lubricant oil pump draws the lubricant oil by a rotation of the rotary shaft to supply the lubricant oil to each sliding portion. In the related art, a scroll compressor in which a supply amount of the lubricant oil can be changed according to a rotational frequency of the drive motor is suggested (for example, refer to PTL 1).
After the lubricant oil drawn by the lubricant oil pump is supplied to each sliding portion, the lubricant oil falls and is returned to the bottom portion of the housing to circulate through the housing. In this case, the fluid introduced into the housing is suctioned into a portion between a fixed scroll and an orbiting scroll while winding up the lubricant oil, and thus, the lubricant oil is mixed in the fluid. Accordingly, the lubricant oil mixed in the fluid seals a minute gap between the wraps of the fixed scroll and the orbiting scroll, and thus, a decrease in an operation efficiency of the compressor is prevented.

Citation List

Patent Literature

[PTL 1] Japanese Unexamined Patent Application Publication No. 08-177773

Summary of Invention

Technical Problem

In recent years, improvement of ability of a refrigerator or an air-conditioning device using a scroll compressor is demanded. Accordingly, it is studied that an upper limit value of the rotational frequency (operation frequency) of the scroll compressor increases from 100 to 140 rps (for example, 150 rps or more) in the related art and the scroll compressor is operated in a wider rotational frequency range. In this case, from the viewpoint of supplying lubricant oil, it is necessary to require the following conditions (A) and (B).
(A) For example, in order to prevent a decrease in an operation efficiency by sealing a gap between wraps during a low speed operation of approximately 50 rps, it is necessary to supply a sufficient amount of lubricant oil to each sliding portion. (B) Meanwhile, for example, in a case where the amount of the lubricant oil discharged to the outside of the housing along with the fluid increases during a high speed operation of 150 rps or higher, there is a concern that the lubricant oil stored in the housing is insufficient, and thus, it is necessary to decrease the amount of the discharged lubricant oil. However, in a case where the amount supplied to each sliding portion increases, in general, the amount of the discharged lubricant oil also increases, and thus, it is difficult to satisfy both of the conditions (A) and (B).
The present invention is made in consideration of the above-described circumstances, and an object thereof is to provide a scroll compressor capable of preventing a decrease in an operation efficiency of the compressor during a low speed operation and decreasing an amount of lubricant oil discharged from the compressor during a high speed operation.

Solution to Problem

In order to solve the above-described problems and achieve the object, according to an aspect of the present invention, there is provided A scroll compressor, including: a housing into which a low-pressure gas flows; a scroll compression mechanism which is accommodated in the housing and compresses the low-pressure gas; a drive motor which is connected to the scroll compression mechanism by a drive shaft to drive the scroll compression mechanism; a bearing portion which supports the drive shaft in a rotatable manner; and a lubricant oil pump which draws a lubricant oil stored in a bottom portion of the housing by a rotation of the drive shaft to supply the lubricant oil to each sliding portion of the scroll compression mechanism and the bearing portion, in which the lubricant oil pump is a positive-displacement pump which is operable in an operation region in which a rotational frequency of the drive motor is at least 150 rps or higher and an inclination indicating a rate of increase of an amount of oil supplied per unit time with respect to the rotational frequency decreases as the rotational frequency increases.
According to this configuration, it is possible to prevent an operation efficiency of the compressor from decreasing during a low speed operation and decrease an amount of the lubricant oil discharged from the compressor during a high speed operation, and the operation can be performed in a wider rotational frequency region. In addition, the low-pressure gas flows into the housing, and thus, a pressure difference between the lubricant oil pump and each sliding portion can be maintained small, and it is possible to prevent the lubricant oil from being excessively supplied due to a pressure difference.
In addition, preferably, in the lubricant oil pump, in a case where an amount of oil supplied by the lubricant oil pump per revolution of the lubricant oil pump is defined as Q (cc / rev) and scroll displacement per revolution of the scroll compression mechanism is defined as Vs (cc/ rev), Q / Vs > 0.006 is satisfied in an operation region in which the rotational frequency of the drive motor is 0 rps to 60 rps, and 0.003 ≤ Q / Vs ≤ 0.006 is satisfied in an operation region in which the rotational frequency of the drive motor is at least 150 rps to 200 rps. According to this configuration, it is possible to decrease the supply amount of the lubricant oil during the high speed operation while sufficiently securing the supply amount of the lubricant oil to each sliding portion during the low speed operation.
Moreover, the scroll compressor may include an oil supply passage through which the lubricant oil supplied to the sliding portion flows and a return oil passage through which excess lubricant oil supplied to the sliding portion is returned into the housing, in which in a case where a minimum diameter in the oil supply passage is defined as d1, an equivalent diameter of the return oil passage is defined as d2, and an inner diameter of a suction port of the lubricant oil pump is defined as D, the inner diameter of the suction port of the lubricant oil pump may satisfy d1 ≤ D s d2. According to this configuration, the minimum diameter d1 in the oil supply passage is equal to or less than the inner diameter D of the suction port, and thus, it is possible to reliably supply the lubricant oil drawn by the lubricant oil pump to the sliding portion. In addition, the equivalent diameter d2 of the return oil passage is equal to or more than the inner diameter D of the suction port, and thus, an excess lubricant oil is prevented from staying in the return oil passage, and it is possible to prevent the lubricant oil stored in the bottom portion of the housing from being insufficient.
In addition, the lubricant oil pump may be a rolling piston type lubricant oil pump. According to this configuration, in the rolling piston type lubricant oil pump, a suction loss is generated during a high speed rotation, and thus, an amount of the supplied oil during a high speed operation of the compressor can be effectively suppressed.

Advantageous Effects of Invention

According to the present invention, the lubricant oil pump is the positive-displacement pump which is operable in the operation region in which the rotational frequency of the drive motor is at least 150 rps or higher and the inclination indicating the rate of increase of the amount of oil supplied per unit time with respect to the rotational frequency decreases as the rotational frequency increases. Accordingly, it is possible to prevent an operation efficiency of the compressor from decreasing during a low speed operation and decrease an amount of the lubricant oil discharged from the compressor during a high speed operation, and the operation can be performed in a wider rotational frequency region.

Brief Description of Drawings

Fig. 1 is an overall sectional view of a scroll compressor according to the present embodiment.
Fig. 2 is a cross sectional view of an oil supply pump included in the scroll compressor.
Fig. 3 is a graph showing a relationship between an amount Q of oil supplied by a pump / scroll displacement Vs and a rotational frequency of a drive motor.
Fig. 4 is a graph showing a relationship between an amount of oil supplied per unit time of a pump and the rotational frequency of the drive motor.

Description of Embodiments

Hereinafter, an embodiment according to the present invention will be described in detail with reference to the drawings. In addition, the present invention is not limited to the embodiment. Moreover, constituent elements of the following embodiment include those which can be easily replaced by a person skilled in the art or substantially the same as those.
Fig. 1 is an overall sectional view of a scroll compressor according to the present embodiment. A scroll compressor 1 compresses a suctioned fluid (for example, refrigerant) and discharges the compressed fluid, and in the present embodiment, the scroll compressor 1 is interposed between refrigerant flow paths through which the refrigerant circulates in an air-conditioning device, a refrigerator, or the like.
As shown in Fig. 1, the scroll compressor 1 includes a motor (drive motor) 5 which is driving means and a scroll compression mechanism 7 which is driven by the motor 5 in an interior space of a housing 3.
The housing 3 includes a tubular housing main body 3a which vertically extends, a bottom portion 3b which closes a lower end of the housing main body 3a, and a cover portion 3c which closes an upper end of the housing main body 3a, and is a pressure container that is sealed in its entirety. A suction pipe 9 through which the refrigerant (low-pressure gas) is introduced into the housing 3 is provided on the side portion of the housing main body 3a. A discharge pipe 11 through which the refrigerant (high-pressure gas) compressed by the scroll compression mechanism 7 is discharged is provided on the upper portion of the cover portion 3c. In the housing 3, a discharge cover 13 is provided between the housing main body 3a and the cover portion 3c, and the interior space of the housing 3 is divided into a low-pressure chamber 3A positioned below the discharge cover 13 and a high-pressure chamber 3B positioned above the discharge cover 13. In the discharge cover 13, an opening hole 13a which communicates with the low-pressure chamber 3A and the high-pressure chamber 3B is formed and a discharge reed valve 13b which opens and closes the opening hole 13a is provided. In addition, a bottom inside the housing 3 (low-pressure chamber 3A) is configured as an oil reservoir 41 in which a lubricant oil 40 is stored.
The motor 5 includes a stator 15, a rotor 17, and a rotary shaft (drive shaft) 19. The stator 15 is fixed to an inner wall surface of the housing main body 3a at an approximately intermediate portion in a vertical direction of the housing main body 3a. The rotor 17 is rotatably provided to the stator 15. A rotary shaft 19 is disposed above and below the rotor 17 in the longitudinal direction. Power is supplied to the motor 5 from the outside of the housing 3 to rotate the rotor 17, and thus, the rotor 17 and the rotary shaft 19 are rotated. In the present embodiment, for example, the motor 5 is configured such that an operation frequency can be controlled by an inverter (not shown) and the motor 5 can be operated in a wide range from a low rotational frequency region to a high rotational frequency region.
The rotary shaft 19 is provided such that end portions protrude upward and downward from the rotor 17, and an upper end portion of the rotary shaft 19 is rotatably supported on the housing main body 3a by an upper bearing (bearing portion) 21 and a lower end portion thereof is rotatably supported on the housing main body 3a by a lower bearing (bearing portion) 23 about an axis CE extending in the vertical direction. In the rotary shaft 19, an eccentric pin 25 which protrudes upward along an eccentricity LE eccentric to the axis CE is formed on an upper end of the rotary shaft 19. The scroll compression mechanism 7 is connected to the upper end of the rotary shaft 19 having the eccentric pin 25. In addition, the rotary shaft 19 and the eccentric pin 25 have an oil supply hole (oil supply passage) 27, which vertically penetrates the rotary shaft 19 and the eccentric pin 25, inside the rotary shaft 19 and the eccentric pin 25. The oil supply hole 27 includes an upper oil supply hole (oil supply passage) 27a and a lower oil supply hole (oil supply passage) 27b, which communicate with the oil supply hole 27 and penetrate the rotary shaft 19 in a radial direction, at height positions corresponding to heights of the upper bearing 21 and the lower bearing 23. Moreover, an oil supply pump (lubricant oil pump) 29 in which the oil reservoir 41 is disposed is provided on the upper end of the rotary shaft 19. The oil supply pump 29 draws the lubricant oil 40 stored in the oil reservoir 41 according to a rotation of the rotary shaft 19. The drawn lubricant oil is supplied to the sliding portions between the upper bearing 21 and the lower bearing 23 and the rotary shaft 19, and the scroll compression mechanism 7 through the oil supply hole 27, the upper oil supply hole 27a, and the lower oil supply hole 27b of the rotary shaft 19.
The upper end portion of the rotary shaft 19 penetrates the upper bearing 21, and thus, the upper bearing rotatably supports the rotary shaft 19. In the upper bearing 21, a recessed portion 21a is formed on an upper surface of the upper bearing 21 to surround an upper end portion of the rotary shaft 19 penetrating the upper bearing 21. A slide bush 37 described later is accommodated in the recessed portion 21a, and the lubricant oil 40 fed via the oil supply hole 27 by the oil supply pump 29 is stored in the recessed portion 21a. In addition, the stored lubricant oil 40 is supplied to the scroll compression mechanism 7.
Moreover, in the upper bearing 21, a notch 21b is formed on a portion of an outer periphery to have a gap between an inner wall surface of the housing main body 3a of the housing 3 and the upper bearing 21, and the oil drain hole (return oil passage) 21c which communicates with the notch 21b and the recessed portion 21a is formed. Moreover, a cover plate 31 is provided below the notch 21b of the upper bearing 21. The cover plate 31 is provided to extend in the vertical direction. The cover plate 31 is formed such that both side ends are curved toward the inner wall surface of the housing main body 3a so as to cover the vicinity of the notch 21b, and is formed such that a lower end of the cover plate 31 is gradually curved toward the inner wall surface of the housing main body 3a. In addition, the lubricant oil 40 excessively stored in the recessed portion 21a is discharged from the notch 21b to the outer periphery of the upper bearing 21 through the oil drain hole 21c. The cover plate 31 receives the lubricant oil 40 discharged from the notch 21b and guides the lubricant oil 40 toward the inner wall surface of the housing main body 3a. The lubricant oil 40 guided toward the inner wall surface by the cover plate 31 is returned to the oil reservoir 41 on the bottom inside the housing 3 along the inner wall surface by the cover plate 31.
In the interior space of the housing 3, the scroll compression mechanism 7 is disposed above the upper bearing 21 in the low-pressure chamber 3A below the discharge cover 13, and includes a fixed scroll 33, an orbiting scroll 35, and a slide bush 37.
In the fixed scroll 33, a spiral fixed wrap 33b is formed on an inner surface (lower surface in Fig. 1) of the fixed end plate 33a fixed to the interior space of the housing 3. A discharge hole 33c is formed at the center portion of the fixed end plate 33a.
In the orbiting scroll 35, a spiral movable wrap 35b is formed on an inner surface (upper surface in Fig. 1) of a movable end plate 35a facing the inner surface of the fixed end plate 33a in the fixed scroll 33. In addition, the movable wrap 35b of the orbiting scroll 35 and the fixed wrap 33b of the fixed scroll 33 mesh with each other with their phases shifted from each other, and thus, a compression chamber which is partitioned by the end plates 33a and 35a and the wraps 33b and 35b is formed. Moreover, in the orbiting scroll 35, a cylindrical boss 35c to which the eccentric pin 25 of the rotary shaft 19 is connected and an eccentric rotation of the eccentric pin 25 is transmitted is formed on the outer surface (lower surface in Fig. 1) of the movable end plate 35a. In addition, the orbiting scroll 35 is revolved while being prevented from rotating on the basis of the eccentric rotation of the eccentric pin 25 by a rotation prevention mechanism 39 such as a well-known Oldham link disposed between the outer surface of the movable end plate 35a and the upper bearing 21.
The slide bush 37 is accommodated in the recessed portion 21a of the above-described upper bearing 21, is interposed between the eccentric pin 25 of the rotary shaft 19 and the boss 35c of the orbiting scroll 35, and transmits the rotation of the eccentric pin 25 as an orbiting movement of the orbiting scroll 35. In addition, the slide bush 37 is provided to be slidable in a radial direction of the eccentric pin 25 to maintain meshing between the movable wrap 35b of the orbiting scroll 35 and the fixed wrap 33b of the fixed scroll 33.
In the scroll compression mechanism 7, by the revolution of the orbiting scroll 35, a low-pressure refrigerant introduced into the low-pressure chamber 3A in the housing 3 via the suction pipe 9 is compressed while being suctioned into the compression chamber between the fixed scroll 33 and the orbiting scroll 35. Here, a portion of the lubricant oil 40 discharged into the housing 3 through the oil drain hole 21c is wound up by a low-pressure refrigerant in the low-pressure chamber 3A, is mixed in the low-pressure refrigerant to be suctioned to the portion between the fixed scroll 33 and the orbiting scroll 35, and is supplied to the sliding portion between the fixed scroll 33 and the orbiting scroll 35. Accordingly, the lubricant oil 40 mixed in the refrigerant seals a minute gap between the wraps 33b and 35b, and thus, the refrigerant is prevented from leaking from the gap, and the operation efficiency of the scroll compressor 1 is prevented from decreasing.
The compressed high-pressure refrigerant is discharged from the discharge hole 33c of the fixed scroll 33 to the outer surface side of the fixed end plate 33a, and the discharge reed valve 13b of the discharge cover 13 is opened by the pressure of the refrigerant. Accordingly, the refrigerant flows from the opening hole 13a into the high-pressure chamber 3B and is discharged to the outside of the housing 3 via the discharge pipe 11.
In recent years, a refrigerator or air-conditioning device using the scroll compressor 1 tends to be required to improve refrigerating ability or an air conditioning capacity. In general, in the scroll compressor, it is known that an upper limit value of the rotational frequency (operation frequency) is set to 100 to 140 rps. However, it is studied that the upper limit value increases to be a larger value (for example, 150 rps or higher) than the value of the related art such that the scroll compressor is operated at a wider rotational frequency region. In a case where an operable rotational frequency region is widened, from the viewpoint of supplying the lubricant oil, firstly, for example, during a low speed operation (low rotation region) of approximately 50 rps, in order to prevent the decrease of the operation efficiency by sealing the gap between the wraps 33b and 35b, it is necessary to supply the lubricant oil 40 having a sufficient amount to each sliding portion. In addition, secondly, for example, during a high speed operation (high rotation region) of approximately 150 rps or higher, the amount of the lubricant oil 40 discharged to the outside of the housing 3 along with the refrigerant increases, and thus, in order to prevent shortage in the amount of the lubricant oil stored in the housing 3, it is necessary to decrease the amount of the discharged lubricant oil. However, in general, in a case where the rotational frequency of the motor 5 increases and the supply amount of the lubricant oil 40 increases, the amount of the lubricant oil discharged to the outside of the housing 3 increases, and thus, it is difficult to satisfy both of the above-described first and second conditions. In the scroll compressor 1 according to the present embodiment, both preventing the operation efficiency from decreasing during the low speed operation and decreasing the amount of the lubricant oil discharged to the outside of the housing 3 during the high speed operation are satisfied.
Fig. 2 is a cross sectional view of the oil supply pump. The oil supply pump 29 is a so-called rolling piston (positive-displacement) oil supply pump, and as shown in Fig. 1, the oil supply pump 29 is provided in the lower bearing 23. The oil supply pump 29 includes a cylinder chamber 45 of which a lower opening portion is closed by a cover body 44 attached to the lower surface portion of the lower bearing 23. The cover body 44 integrally includes a suction nozzle 43 extending downward, and a suction port 43A communicating with the cylinder chamber 45 is formed in the suction nozzle 43. As shown in Figs. 1 and 2, a rotor 47 fitted to an eccentric shaft portion 46 formed on the lower end of the rotary shaft 19 is accommodated in the cylinder chamber 45, and the rotor 47 revolves while sliding on the inner peripheral surface of the cylinder chamber 45 according to the rotation of the rotary shaft 19. As shown in Fig. 2, a plate 47A which divides the interior space of the cylinder chamber 45 into an oil supply chamber 45A and an oil discharge chamber 45B is integrally provided in the rotor 47. According to the revolution of the rotor 47, the lubricant oil 40 stored in the oil reservoir 41 is suctioned to the oil supply chamber 45A through the suction port 43A of the suction nozzle 43 and an oil supply port 48, is discharged from the oil discharge chamber 45B to the oil discharge port 49, and is fed to the oil supply hole 27 of the rotary shaft 19 via a communication passage 50 (refer to Fig. 1). In the rolling piston oil supply pump 29, a suction loss is generated during the high speed rotation, and thus, it is possible to effectively suppress the amount of the supplied oil during the high speed operation of the motor 5 (compressor 1). In addition, the above-described rolling piston oil supply pump 29 is only an example, and oil supply pump having other configurations may be adopted as long as they are positive-displacement oil supply pumps.
As described above, the lubricant oil 40 drawn by the oil supply pump 29 through the suction port 43A flows to the oil supply hole 27 of the rotary shaft 19, and a portion of the lubricant oil 40 is supplied to the sliding portions between the upper bearing 21 and the lower bearing 23 and the rotary shaft 19 through the upper oil supply hole 27a and the lower oil supply hole 27b. In addition, a portion of the lubricant oil 40 is stored in the recessed portion 21a of the upper bearing 21 to be supplied to the sliding portion between the recessed portion 21a and the orbiting scroll 35, and excess lubricant oil 40 is returned to the oil reservoir 41 through the oil drain hole 21c.
In the present embodiment, a relationship among an inner diameter D of the suction port 43A of the oil supply pump 29, the minimum diameter d1 of the oil supply hole 27 including the upper oil supply hole 27a and the lower oil supply hole 27b, and an equivalent diameter d2 of the oil drain hole 21c satisfies d1 ≤ D s d2.
Here, the minimum diameter d1 of the oil supply hole 27 indicates a diameter of a portion of the oil supply hole 27 having the narrowest inner diameter for supplying the oil from the oil supply pump 29 to each sliding portion (upper bearing 21, recessed portion 21a, and lower bearing 23), and in the present embodiment, the inner diameter of each of the upper oil supply hole 27a and the lower oil supply hole 27b becomes the minimum diameter d1. In addition, the equivalent diameter d2 of the oil drain hole 21C is an parameter which is represented by d2 = 4 x A/L in a case where a sectional area of the oil drain hole 21c is defined as A and an outline length of the oil drain hole 21c is defined as L.
According to this configuration, the minimum diameter d1 (the inner diameter of each of the upper oil supply hole 27a and the lower oil supply hole 27b) of the oil supply hole 27 is equal to or less than the inner diameter D of the suction port 43A, and thus, the lubricant oil 40 drawn by the oil supply pump 29 can be reliably supplied to the sliding portions between the upper bearing 21 and the lower bearing 23 and the rotary shaft 19. In addition, the equivalent diameter d2 of the oil drain hole 21c is equal to or more than the inner diameter D of the suction port 43A, the excess lubricant oil 40 is prevented from staying in the recessed portion 21a and the oil drain hole 21c, and the lubricant oil stored in the oil reservoir 41 of the bottom portion of the housing 3 from being insufficient.
In the positive-displacement oil supply pump 29, in general, a pressure loss tends to increase as the rotational frequency increases. However, the inner diameter D of the suction port 43A of the oil supply pump 29 is set to satisfy d1 ≤ D ≤ d2, and thus, it is possible to further increase the pressure loss.
Fig. 3 is a graph showing a relationship between an amount Q of oil supplied by a pump with respect to scroll displacement Vs and the rotational frequency of the motor. In addition, Fig. 4 is a graph showing a relationship between an amount of oil supplied per unit time of a pump and the rotational frequency of the motor. The amount Q (cc / rev) of oil supplied by a pump is a value indicating an amount of oil supplied (discharged) per revolution of the oil supply pump 29, and the scroll displacement Vs (cc / rev) is a value indicating an amount of displacement (discharge) per revolution of the scroll compression mechanism 7. In the present embodiment, a theoretical value of the amount Q of oil supplied by a pump / the scroll displacement Vs in the oil supply pump 29 becomes 0.008.
Fig. 3 shows that the amount Q (cc / rev) of oil supplied by a pump of the oil supply pump 29 having the above-described performance is measured in a state where the rotational frequency is changed. As shown in Fig. 3, compared to the theoretical value, an actual measurement value of the amount Q of oil supplied by a pump / the scroll displacement Vs tends to decrease as the rotational frequency of the motor 5 increases. Specifically, Q / Vs > 0.006 is satisfied during the low speed operation (low rotation region) in which the rotational frequency of the motor 5 is 0 rps to 60 rps. Meanwhile, the actual measurement value decreases to a range satisfying 0.003 ≤ Q / Vs ≤ 0.006 during the high speed operation (high rotation region) in which the rotational frequency of the motor 5 is at least 150 rps to 200 rps. In general, OCR (a ratio of an amount of discharged oil to an amount of a circulating refrigerant) tends to increase exponentially with respect to the rotational frequency of the motor 5 (compressor). Accordingly, in the range in which the rotational frequency of the motor 5 is 0 rps to 60 rps, the OCR decreases, and the amount of the oil supplied by the oil supply pump 29 greatly affects the efficiency.
In this configuration, the amount Q of oil supplied by a pump / the scroll displacement Vs satisfies Q / Vs > 0.006 during the low speed operation, and thus, as shown in Fig. 4, the actual measurement value of the amount V (cc / s) of the oil supplied per unit time during the low speed operation can keep a deviation from the theoretical value small. Accordingly, it is possible to sufficiently secure the amount of the lubricant oil mixed in the refrigerant, and this lubricant oil seals the minute gap between wraps 33b and 35b. Therefore, the refrigerant is prevented from leaking from the gap, and it is possible to prevent the operation efficiency of the scroll compressor 1 from decreasing. In addition, in a case where the amount Q of oil supplied by a pump / the scroll displacement Vs satisfies Q / Vs ≤ 0.006 during the low speed operation, it is not possible to supply the lubricant oil having the amount sufficient to seal the minute gap between the wraps 33b and 35b, and thus, the operation efficiency of the scroll compressor 1 decreases.
Meanwhile, the amount Q of oil supplied by a pump / the scroll displacement Vs satisfies 0.003 ≤ Q / Vs ≤ 0.006 during the high speed operation, and thus, as shown in Fig. 4, the actual measurement value of the amount V (cc / s) of the oil supplied per unit time during the high speed operation can increase the deviation from the theoretical value compared to the low speed operation. Accordingly, the amount V (cc / s) of the oil supplied per unit time during the high speed operation can decrease, and thus, it is possible to decrease the amount of the lubricant oil discharged from the scroll compressor 1 by the decreased amount. Therefore, it is possible to prevent the operation efficiency of the scroll compressor 1 from decreasing during the low speed operation, it is possible to decrease the amount of the lubricant oil discharged from the scroll compressor 1 during the high speed operation, and thus, the operation can be performed in a wider rotational frequency region.
The present embodiment is configured such that the amount Q of oil supplied by a pump / the scroll displacement Vs satisfies 0.003 ≤ Q / Vs ≤ 0.006 during the high speed operation. In the range of Q / Vs < 0.003, the amount of the lubricant oil supplied to each sliding portion decreases, a cooling failure of the scroll compression mechanism 7, the upper bearing 21, or the lower bearing 23 occurs, and there is a concern that seizing of the scroll compression mechanism 7, the upper bearing 21, or the lower bearing 23 may occur. In addition, in the range of 0.006 < Q / Vs, the amount of the lubricant oil discharged from the scroll compressor 1 is increased by increasing the amount of the lubricant oil supplied from the oil supply pump 29, and as a result, the amount of the lubricant oil stored in the housing 3 decreases, the cooling failure of the scroll compression mechanism 7, the upper bearing 21, or the lower bearing 23 occurs, and there is a concern that seizing of the scroll compression mechanism 7, the upper bearing 21, or the lower bearing 23 may occur.
In addition, in the present embodiment, as shown in Fig. 4, in the graph showing the actual measurement value of the amount V of oil supplied per unit time, an inclination 0 indicating a rate of increase in the amount of the supplied oil decreases as the rotational frequency increases. Accordingly, it is possible to decrease the supply amount of the lubricant oil during the high speed operation and it is possible to sufficiently secure the supply amount of the lubricant oil to each sliding portion during the low speed operation.
Hereinbefore, the embodiment of the present invention is described. However, the embodiment is presented as an example, and it is not intended to limit the scope of the invention. The present embodiment can be embodied according to various aspects, and various omissions, replacements, and modifications can be applied to the present invention within a scope which does not depart from the gist of the present invention. The present embodiment and modifications thereof are included in the invention described in the claims and the equivalent scope thereof as well as being included in the scope and the gist of the invention.

Reference Signs List

1: scroll compressor
3: housing
3a: housing main body
5: motor (drive motor)
7: scroll compression mechanism
9: suction pipe
11: discharge pipe
13: discharge cover
19: rotary shaft (drive shaft)
21: upper bearing (bearing portion)
21c: oil drain hole (return oil passage)
23: lower bearing (bearing portion)
27: oil supply hole (oil supply passage)
27a: upper oil supply hole (oil supply passage)
27b: lower oil supply hole (oil supply passage)
29: oil supply pump (lubricant oil pump)
31: cover plate
33: fixed scroll
33a: fixed end plate
33b: fixed wrap
33c: discharge hole
35: orbiting scroll
35a: movable end plate
35b: movable wrap
35c: boss
37: slide bush
39: rotation prevention mechanism
40: lubricant oil
41: oil reservoir
43: suction nozzle
43A: suction port
44: cover body
45: cylinder chamber
45A: oil supply chamber
45B: oil discharge chamber
46: eccentric shaft portion
47: rotor
47A: plate
48: oil supply port
49: oil discharge port
50: communication passage
D: inner diameter
d1: minimum diameter
d2: equivalent diameter

Claims

A scroll compressor, comprising:
a housing into which a low-pressure gas flows;

a scroll compression mechanism which is accommodated in the housing and compresses the low-pressure gas;

a drive motor which is connected to the scroll compression mechanism by a drive shaft to drive the scroll compression mechanism;

a bearing portion which supports the drive shaft in a rotatable manner; and

a lubricant oil pump which draws a lubricant oil stored in a bottom portion of the housing by a rotation of the drive shaft to supply the lubricant oil to each sliding portion of the scroll compression mechanism and the bearing portion,

wherein the lubricant oil pump is a positive-displacement pump which is operable in an operation region in which a rotational frequency of the drive motor is at least 150 rps or higher and an inclination indicating a rate of increase of an amount of oil supplied per unit time with respect to the rotational frequency decreases as the rotational frequency increases.
The scroll compressor according to claim 1,
wherein in the lubricant oil pump, in a case where an amount of oil supplied by the lubricant oil pump per revolution of the lubricant oil pump is defined as Q (cc / rev) and scroll displacement per revolution of the scroll compression mechanism is defined as Vs (cc/ rev),
Q / Vs > 0.006 is satisfied in an operation region in which the rotational frequency of the drive motor is 0 rps to 60 rps, and
0.003 ≤ Q / Vs s 0.006 is satisfied in an operation region in which the rotational frequency of the drive motor is at least 150 rps to 200 rps.
The scroll compressor according to claim 1 or 2, further comprising:
an oil supply passage through which the lubricant oil supplied to the sliding portion flows and a return oil passage through which excess lubricant oil supplied to the sliding portion is returned into the housing,

wherein in a case where a minimum diameter in the oil supply passage is defined as d1, an equivalent diameter of the return oil passage is defined as d2, and an inner diameter of a suction port of the lubricant oil pump is defined as D,

the inner diameter D of the suction port of the lubricant oil pump satisfies d1 ≤ D ≤ d2.
The scroll compressor according to any one of claims 1 to 3,
wherein the lubricant oil pump is a rolling piston type lubricant oil pump.