SCROLL COMPRESSOR

TECHNICAL FIELD

The present disclosure relates to measures to improve reliability of scroll compressors.

BACKGROUND ART

Conventionally, scroll compressors have been widely used to compress, e.g., refrigerants or air. For example, Patent Document 1 discloses a hermetic scroll compressor. Here, the structure of the scroll compressor (500) disclosed in Patent Document 1 is described with reference to FIG. 9.

The scroll compressor (500) includes a vertically oriented cylindrical casing (510) in which a compression mechanism (520) and a motor (515) are housed. The compression mechanism (520) is disposed above the motor (515), and a driving shaft (550) connects the compression mechanism (520) to the motor (515).

The compression mechanism (520) includes a fixed scroll (525), an orbiting scroll (530), and housing (540). The orbiting scroll (530) has an end plate (531), a lap (532) projecting from the front side of the end plate (531), and a cylindrical portion (533) projecting from the backside of the end plate (531). In the compression mechanism (520), the lap (532) of the orbiting scroll (530) is engaged with a lap (526) of the fixed scroll (525), thereby forming compression chambers (521). The end plate (531) of the orbiting scroll (530) has a thrust sliding surface (536) which is in sliding contact with a thrust sliding surface (527) of the fixed scroll (525). The driving shaft (550) has an eccentric portion (551) inserted in the cylindrical portion (533) of the orbiting scroll (530). When the driving shaft (550) rotates, the orbiting scroll (530) performs orbital motion and a refrigerant sucked in the compression chambers (521) is compressed,

In the scroll compressor (500), the driving shaft (550) includes an oil supply passage (555) formed therein. A lubricating oil having flowed from a bottom portion of the casing (510) into the oil supply passage (555) is supplied to a bearing portion through a first branch passage (556) and a second branch passage (557). Part of the lubricating oil flowing through the oil supply passage (555) comes out of a terminal end of the oil supply passage (555) which opens at an upper end of the eccentric portion (551).

The pressure of the refrigerant present in the compression chambers (521) acts on the front side of the end plate (531) of the orbiting scroll (530). Accordingly, an increase in the pressure of the refrigerant in the compression chambers (521) causes the orbiting scroll (530) to be pushed down, and thereby reduces air tightness of the compression chambers (521).

On the other hand, the scroll compressor (500) includes a seal ring (541) provided between the housing (540) and the orbiting scroll (530). The pressure present inside the seal ring (541) is substantially equal to the pressure of the lubricating oil having flowed out from the terminal end of the oil supply passage (555) (consequently, substantially equal to the pressure of the refrigerant discharged from the compression mechanism (520)). Accordingly, the orbiting scroll (530) is upwardly pushed by the pressure acting on the backside of the end plate (531). The orbiting scroll (530) is consequently pressed against the fixed scroll (525), and the air tightness of the compression chambers (521) is ensured.

However, the force pressing the orbiting scroll (530) against the fixed scroll (525) sometimes becomes too strong. In such a case, the friction force generated between the thrust sliding surface (536) of the orbiting scroll (530) and the thrust sliding surface (527) of the fixed scroll (525) becomes strong, resulting in an increase in power consumption of the motor (515).

On the other hand, the scroll compressor (500) includes an oil groove (534) and a communication passage (535) which are formed on the end plate (531) of the orbiting scroll (530). The oil groove (534) is a groove which opens on the thrust sliding surface (536) of the end plate (531) and surrounds the lap (532).

The oil groove (534) communicates with the inner space of the cylindrical portion (533) through the communication passage (535). Accordingly, the pressure inside the oil groove (534) is substantially equal to the pressure of the lubricating oil having flowed out from the terminal end of the oil supply passage (555). The pressure of the compression chamber (521) adjacent to the oil groove (534) is approximate to the pressure of the low-pressure refrigerant sucked in the compression chamber (521) and lower than the pressure of the oil groove (534). Accordingly, a pressure difference between the oil groove (534) and the compression chamber (521) causes a sufficient amount of the lubricating oil to be supplied to the thrust sliding surfaces (527, 536). Consequently, the friction force between the thrust sliding surface (536) of the orbiting scroll (530) and the thrust sliding surface (527) of the fixed scroll (525) becomes weak, and accordingly, the power consumption of the motor (515) is kept low.

CITATION LIST
Patent Document

PATENT DOCUMENT 1: Japanese Patent No. 3731068

SUMMARY OF THE INVENTION
Technical Problem

In the orbiting scroll (530) of the scroll compressor (500), the internal pressure of the compression chambers (521) acts on the lap (532) projecting from the front side of the end plate (531), and a load from the driving shaft (550) acts on the cylindrical portion (533) projecting from the backside of the end plate (531). The line of action of the gas pressure acting on the lap (532) and the line of action of the load acting on the cylindrical portion (533) intersect the axial direction of the orbiting scroll (530) at right angles but do not intersect each other. Accordingly, a moment acts on the orbiting scroll (530) in a direction tilting the orbiting scroll (530).

If the pressure acting on the backside of the end plate (531) (specifically, the pressure inside the seal ring (541)) is sufficiently high, the orbiting scroll (530) is strongly pressed against the fixed scroll (525), and accordingly, the orbiting scroll (530) is not tilted even by the moment acting thereon. However, in an operational state where the pressure acting on the backside of the end plate (531) is insufficiently high (for example, in an operational state where the pressure of the refrigerant discharged from the compression mechanism (520) is very low), the orbiting scroll (530) is sometimes tilted, resulting in an increase in the clearance between the thrust sliding surface (536) of the orbiting scroll (530) and the thrust sliding surface (527) of the fixed scroll (525). In the scroll compressor (500) shown in FIG. 9, the increase in the clearance between the thrust sliding surfaces (527, 536) may disadvantageously cause the pressure in the oil groove (534) to drop abruptly.

In the conventional scroll compressor (500) shown in FIG. 9, the oil groove (534) communicates with the bearing portion of the compression mechanism (520) through the communication passage (535) and the oil supply passage (555). Therefore, when the orbiting scroll (530) is tilted and the pressure in the oil groove (534) abruptly drops, the pressure of the oil supply passage (555) communicating with the oil groove (534) decreases, and accordingly, the lubricating oil may disadvantageously flow backward from the bearing portion to the oil supply passage (555) through the branch passages (556, 557). This back-flow of the lubricating oil from the bearing portion to the oil supply passage (555) may cause a shortage of lubrication in the bearing portion and troubles such as seizure.

It is therefore an object of the present disclosure to improve reliability of scroll compressors.

Solution to the Problem

A first aspect of the present disclosure relates to a scroll compressor including: a casing (15); a compression mechanism (20) housed in the casing (15) and including a fixed scroll (30) and an orbiting scroll (40); and a driving shaft (60) housed in the casing (15) and engaged with the orbiting scroll (40), in which the compression mechanism (20) is configured to discharge a compressed fluid into the casing (15) and to generate a pressing force which presses the orbiting scroll (40) against the fixed scroll (30). According to the first aspect, an end plate (41) of the orbiting scroll (40) and the fixed scroll (30) respectively include a thrust sliding surface (45) and a thrust sliding surface (35) which are in sliding contact with each other, the thrust sliding surface (45) of the orbiting scroll (40) or the thrust sliding surface (35) of the fixed scroll (30) includes an oil groove (80) into which a lubricating oil flows, and the scroll compressor is provided with a bearing oil supply passage (70) which is not in communication with the oil groove (80) and is configured to supply the lubricating oil in an oil reservoir (18) located in the casing (15) to a bearing provided in the compression mechanism (20) for the driving shaft (60), and a groove communication passage (85) which connects the oil groove (80) to the oil reservoir (18) in the casing (15).

According to the first aspect of the present disclosure, when the driving shaft (60) drives the orbiting scroll (40), the fluid is sucked into the compression mechanism (20) to be compressed therein. The compression mechanism (20) then discharges the compressed fluid into the casing (15). Accordingly, the lubricating oil stored in the casing (15) has a pressure which is substantially equal to a pressure of the fluid discharged from the compression mechanism (20). The lubricating oil in the casing (15) passes through the bearing oil supply passage (70) to be supplied to the bearing in the compression mechanism (20).

In the compression mechanism (20) of the first aspect, the orbiting scroll (40) is pressed against the fixed scroll (30) in order to ensure air tightness of compression chambers. Further, the thrust sliding surface (45) of the orbiting scroll (40) slides on the thrust sliding surface (35) of the fixed scroll (30). In the compression mechanism (20), the thrust sliding surface (45) or the thrust sliding surface (35) includes the oil groove (80) formed thereon. The oil groove (80) communicates with the oil reservoir (18) in the casing (15) through the groove communication passage (85). Accordingly, the pressure of the lubricating oil in the oil groove (80) becomes substantially equal to the pressure of the lubricating oil stored in the casing (15). The lubricating oil having flowed from the oil reservoir (18) into the oil groove (80) through the groove communication passage (85) is supplied to the thrust sliding surface (45) and the thrust sliding surface (35).

In the compression mechanism (20) of the first aspect, the orbiting scroll (40) may be sometimes tilted. In such a case, a clearance between the thrust sliding surface (45) and the thrust sliding surface (35) increases, and consequently, the pressure of the oil groove (80) may abruptly drop. On the other hand, in the first aspect of the present disclosure, since the bearing oil supply passage (70) is not in communication with the oil groove (80), the abrupt pressure drop of the oil groove (80) does not cause the pressure of the bearing oil supply passage (70) to change.

A second aspect of the present disclosure relates to the scroll compressor of the first aspect, wherein the bearing oil supply passage (70) is provided with an oil supply pump (75) which is driven by the driving shaft (60) and configured to suck the lubricating oil from the oil reservoir (18) in the casing (15) and to discharge the lubricating oil, and the groove communication passage (85) is configured such that the lubricating oil is caused to flow through the groove communication passage (85) only by a pressure difference between the oil reservoir (18) in the casing (15) and the oil groove (80).

According to the second aspect, when the orbiting scroll (40) is tilted and the pressure of the oil groove (80) decreases during operation of the compression mechanism (20), the lubricating oil in the oil reservoir (18) is caused to flow through the groove communication passage (85) toward the oil groove (80) by the pressure difference between the oil reservoir (18) in the casing (15) and the oil groove (80). On the other hand, the bearing oil supply passage (70) is provided with the oil supply pump (75). The oil supply pump (75) is driven by the driving shaft (60), sucks the lubricating oil from the oil reservoir (18) in the casing (15), and discharges the lubricating oil. The lubricating oil discharged by the oil supply pump (75) is supplied to the bearing in the compression mechanism (20).

A third aspect of the present disclosure relates to the scroll compressor of the second aspect, wherein the groove communication passage (85) is provided with at least one throttle for controlling a flow rate of the lubricating oil.

When the orbiting scroll (40) is tilted during operation of the compression mechanism (20), the clearance between the thrust sliding surface (45) and the thrust sliding surface (35) increases. Consequently, the lubricating oil easily flows out from the oil groove (80), and the flow rate of the lubricating oil in the groove communication passage (85) may become excessively high.

To address this problem, the groove communication passage (85) of the third aspect is provided with the throttle. Accordingly, even in a state where the clearance between the thrust sliding surface (45) and the thrust sliding surface (35) has increased, the throttle controls the flow rate of the lubricating oil in the groove communication passage (85).

A fourth aspect of the present disclosure relates to the scroll compressor of the third aspect, wherein the throttle is at least one rod member (89) which is disposed in the groove communication passage (85) and includes, on its outer circumference, a spiral groove (89e) through which the lubricating oil is allowed to flow.

According to the fourth aspect, the rod member (89) having the spiral groove (89e) is disposed in the groove communication passage (85), thereby forming a narrow spiral channel on the outer circumference of the rod member (89) disposed in the groove communication passage (85). The narrow spiral channel on the outer circumference of the rod member (89) controls the flow rate of the lubricating oil having flowed o the groove communication passage (85).

A fifth aspect of the present disclosure relate to the scroll compressor of the fourth aspect, wherein the at least one rod member (89) includes a plurality of rod members (89), and the plurality of rod members (89) are disposed in a plurality of locations of the groove communication passage (85).

According to the fifth aspect, the rod members (89) serving as the throttles are disposed in the plurality of locations in the groove communication passage (85). If the groove communication passage (85) was provided with only one rod member (89), the rod member (89) provided in the passage (85) would need to be a long one because the narrow channel would need to be long to some extent in order to control the flow rate of the lubricating oil sufficiently. On the other hand, providing the plurality of rod members (89) in the plurality of locations in the groove communication passage (85) as described above results in that the narrow channels have a large length in total although each of the rod members (89) is short.

A sixth aspect of the present disclosure elate to the scroll compressor of the fifth aspect, further including a bearing (55) which is provided separately from the compression mechanism (20) and supports the driving shaft (60) in a rotatable manner, wherein the bearing (55) and the fixed scroll (30) respectively include therein a communicating path (83) and another communicating path (81) which form part of the groove communication passage (85), and each of the communicating paths (83, 81) is provided with an associated one of the rod members (89).

According to the sixth aspect, the bearing (55) and the fixed scroll (30) respectively include therein the communicating path (83) and the communicating path (81) which form part of the groove communication passage (85), and each of the communicating paths(83, 81) is provided with the associated one of the rod members (89) serving as the throttles. If any one of the bearing (55) and the fixed scroll (30) was provided with one of the rod members (89), the narrow channel would need to be long to some extent to control the flow rate of the lubricating nil sufficiently, and the rod member (89) and the communicating path where the rod member (89) is disposed would need to be long. However, since both of the bearing (55) and the fixed scroll (30) include therein the communicating paths (83, 81) which are each provided with the rod member (89), the narrow channels have a large length in total although each of the rod members (89) and the communicating paths (83, 81) is short.

A seventh aspect of the present disclosure relates to the scroll compressor of any of the first through the sixth aspects, further including: a motor (50) configured to drive and rotate the driving shaft (60); and a connection pipe (84) which is provided between the casing (15) and the motor (50) and forms part of the groove communication passage (85), wherein the connection pipe (84) is a resin pipe made of a resin material or a metal pipe having the outer circumferential surface coated with a resin material.

According to the seventh aspect, the connection pipe (84) which forms part of the groove communication passage (85) is provided between the casing (15) and the motor (50).

If a metal pipe was provided on a side of the motor (50), it would be necessary to space the metal pipe from the motor (50) at a distance which ensures insulation, and accordingly, the diameter of the casing (15) would need to be increased in accordance with the distance between the metal pipe and the motor (50).

In contrast, according to the seventh aspect, the connection pipe (84) is a resin pipe made of a resin material or a metal pipe having the outer circumferential surface coated with a resin material. Therefore, it is possible to ensure insulation without distancing the connection pipe (84) from the motor (50).

An eighth aspect of the present disclosure relates to the scroll compressor of any of the first through the seventh aspects, wherein a lubricating oil inlet (88) of the groove communication passage (85) is located higher than a suction inlet (76) of the bearing oil supply passage (70).

Part of the lubricating oil supplied from the oil reservoir (18) in the casing (15) to the thrust sliding surface (45) and the thrust sliding surface (35) through the oil groove (80) flows into compression chambers, and then, is discharged together with compressed refrigerant to the outside of the casing (15). Accordingly, the amount of the lubricating oil in the oil reservoir (18) in the casing (15) decreases and the oil level is becoming low. When the oil level of the oil reservoir (18) in the casing (15) has become lower than the lubricating oil inlet (76) of the bearing oil supply passage (70) and the lubricating oil inlet (88) of the groove communication passage (85), it is no longer possible to supply the lubricating oil from the oil reservoir (18) to the bearing of the driving shaft (60) and the oil groove (80).

An insufficient amount of lubricating oil supplied to the bearing of the driving shaft (60) may cause seizure and failure of the bearing. On the other hand, an insufficient amount of lubricating oil supplied to the oil groove (80) may cause an increase in friction force generated between the thrust sliding surface (45) of the orbiting scroll (40) and the thrust sliding surface (35) of the fixed scroll (30), and accordingly, an increase in power consumption of the motor.

When an insufficient amount of the refrigeration oil is supplied to the bearing of the driving shaft (60), even for a short time, the bearing may be fatally damaged and the compressor may become unable to operate properly. On the other hand, when an insufficient amount of the refrigeration oil is supplied to the oil groove (80) only for a short time, the compressor does not suffer fatal damage although the performance is temporary reduced by insufficient sealing of the thrust sliding surfaces (35, 45). That is, an oil shortage of the bearing of the driving shaft (60) must be dealt with more quickly than an oil shortage of the oil groove (80).

To address this problem, the eighth aspect has the configuration in which the lubricating oil inlet (88) of the groove communication passage (85) is located higher than the lubricating oil inlet (76) of the bearing oil supply passage (70). With this configuration, when the lubricating oil in the oil reservoir (18) in the casing (15) decreases, the oil level of the oil reservoir (18) first becomes lower than the inlet (88) of the groove communication passage (85), and supply of the lubricating oil to the oil groove (80) is stopped. Consequently, he amount of the lubricating oil discharged together with the refrigerant to the outside of the casing (15) decreases, and lowering of the oil level of the oil reservoir (18) in the casing (15) is alleviated.

Advantages of the Invention

According to the first aspect of the present disclosure, any one of the thrust sliding surface (45) of the orbiting scroll (40) or the thrust sliding surface (35) of the fixed scroll (30) includes the oil groove (80) formed thereon. The bearing oil supply passage (70) which supplies the lubricating oil to the bearing in the compression mechanism (20) is not in communication with the oil groove (80). Accordingly, even when the orbiting scroll (40) is tilted and the pressure of the oil groove (80) abruptly drops during operation of the compression mechanism (20), the pressure of the bearing oil supply passage (70) remains unchanged.

If the oil groove (80) and the bearing oil supply passage (70) communicated with each other, an abrupt pressure drop of the oil groove (80) would cause a decrease in the pressure of the bearing oil supply passage (70). The pressure decrease of the bearing oil supply passage (70) would cause the lubricating oil to flow backward from the bearing in the compression mechanism (20) to the bearing oil supply passage (70), and would lead to a shortage of the lubricating oil for the bearing.

In contrast, the bearing oil supply passage (70) of the first aspect is not in communication with the oil groove (80). An abrupt pressure drop of the oil groove (80) does not cause the pressure of the bearing oil supply passage (70) to change. Therefore, according to the first aspect, even when the orbiting scroll (40) has been tilted and the pressure of the oil groove (80) has abruptly dropped, the lubricating oil is not allowed to flow backward from the bearing in the compression mechanism (20) to the bearing oil supply passage (70), and it is accordingly ensured that the lubricating oil continues to be supplied to the bearing in the compression mechanism (20) through the bearing oil supply passage (70). Consequently, lubrication of the bearing in the compression mechanism (20) is ensured, and troubles such as seizure are prevented, thereby enabling improvement of the reliability of the scroll compressor (10).

According to the second aspect of the present disclosure, the lubricating oil discharged from the oil supply pump (75) driven by the driving shaft (60) passes through the bearing oil supply passage (70), which is not in communication with the oil groove (80), to be supplied to the bearing in the compression mechanism (20). Accordingly, even in a state where the orbiting scroll (40) has been tilted and the pressure of the oil groove (80) has abruptly dropped during operation of the compression mechanism (20), the lubricating oil can be supplied to the bearing in the compression mechanism (20) in a stable manner. Therefore, according to the second aspect, it can be ensured that the lubricating oil is supplied to the bearing in the compression mechanism (20) regardless of the pressure of the oil groove (80), thereby enabling improvement of the reliability of the scroll compressor (10).

According to the third aspect of the present disclosure, the groove communication passage (85) is provided with the at least one throttle. Accordingly, even in a state where the orbiting scroll (40) has been tilted and the clearance between the thrust sliding surface (45) and the thrust sliding surface (35) has increased, the throttle controls the flow rate of the lubricating oil in the groove communication passage (85).

Here, tilting of the orbiting scroll (40) during operation of the compression mechanism (20) may reduce a pressure loss caused when the lubricating oil passes through the clearance between the thrust sliding surface (45) and the thrust sliding surface (35), and accordingly, the pressure acting on the thrust sliding surfaces (35, 45) increases to become approximate to the pressure of the lubricating oil in the oil groove (80). In such a case, a force separating the orbiting scroll (40) from the fixed scroll (30) becomes strong, and the air tightness of the compression chambers (21) may be reduced.

To address this problem, the groove communication passage (85) of the third aspect is provided with the throttle. Accordingly, even in a state where the orbiting scroll (40) has been tilted, the flow rate of the lubricating oil flowing from the groove communication passage (85) into the oil groove (80) and the pressure of the oil groove (80) are kept low. Consequently, even when the orbiting scroll (40) has been tilted during operation of the compression mechanism (20), the pressure acting on the thrust sliding surfaces (35, 45) is kept low, and the force separating the orbiting scroll (40) from the fixed scroll (30) is not allowed to become excessively strong. On the other hand, the pressing force acts on the orbiting scroll (40) to press the orbiting scroll (40) against the fixed scroll (30). Therefore, the orbiting scroll (40) which has been tilted during operation of the compression mechanism (20) quickly restores the original position by receiving the pressing force. According to the third aspect, it is possible to cause the orbiting scroll (40) which has been tilted during operation of the compression mechanism (20) to quickly restore the original position, and accordingly, decrease in performance of the scroll compressor (10) can be alleviated by ensuring air tightness of the compression chambers (21).

According to the fourth aspect of the present disclosure, the throttle which controls the flow rate of the lubricating oil in the groove communication passage (85) can be easily provided simply by inserting into the groove communication passage (85) the rod member (89) having the spiral groove (89e) formed on the outer circumference. Furthermore, the cross-sectional area of the groove communication passage (85) can be easily varied simply by changing the cross-sectional shape of the spiral groove (89e) formed on the outer circumference of the rod member (89). That is, use of the rod member (89) as the throttle increases the degree of freedom of design and makes it easy to change the design.

When using the rod member (89) having the spiral groove (89e) on the outer circumference as the throttle for controlling the flow rate of the lubricating oil in the groove communication passage (85), the narrow channel formed with the spiral groove (89e) needs to be long to some extent in order to obtain a sufficient throttle effect. Increasing the length of the narrow channel by using a longer rod member (89), however, requires a longer space in which the longer rod member (89) is placed. In addition, installation of the longer rod member (89) may require much time and effort.

To address this problem, the fifth embodiment of the present disclosure is configured such that, a plurality of rod members (89) serving as the throttles are provided in a plurality of locations of the groove communication passage (85). Accordingly, it is possible to increase the total length of the narrow channels by using the rod members (89) each of which is short, and the flow rate of the lubricating oil in the groove communication passage (85) can be sufficiently controlled. In other words, providing the plurality of rod members (89) in the plurality of locations of the groove communication passage (85) makes it possible to reduce the length of each of the rod members (89). Consequently, it is unnecessary to ensure long spaces for installation of the rod members (89), and the rod members (89) can be easily installed.

According to the sixth aspect of the present disclosure, both of the bearing (55) and the fixed scroll (30) include the communicating paths (83, 81) which form part of the groove communication passage (85) and are provided with the rod members (89) serving as the throttles. Accordingly, even if each of rod members (89) and each of the communicating paths (81, 83) is short, the narrow channels can have a large length in total. Consequently, the flow rate of the refrigeration oil in the groove communication passage (85) can be sufficiently controlled. In other words, designing each of the bearing member (55) and the fixed scroll (30) to include the associated communicating path (83, 81) and the associated rod member (89) provided in the associated communicating path enables reduction of the length of each of the rod members (89). Consequently, it is unnecessary to ensure long spaces for installation of the rod members (89), and the rod members (89) can be easily installed.

According to the seventh aspect of the present disclosure, a resin pipe made of a resin material or a metal pipe having the outer circumferential surface coated with a resin material is used as the connection pipe (84) which is provided between the casing (15) and the motor (50) and forms part of the groove communication passage (85). Accordingly, it is possible to ensure insulation without distancing the connection pipe (84) from the motor (50). It is consequently possible to design the casing (15) to have a smaller diameter, and to downsize the scroll compressor.

The eighth aspect of the present disclosure has the configuration in which the lubricating oil inlet (88) of the groove communication passage (85) is located higher than the lubricating oil inlet (76) of the bearing oil supply passage (70). With this configuration, when the lubricating oil in the oil reservoir (18) in the casing (15) decreases, supply of the lubricating oil to the oil groove (80) is first stopped, and accordingly, the amount of the lubricating oil discharged together with the refrigerant to the outside of the casing (15) is reduced. Consequently, lowering of the oil level of the oil reservoir (18) in the casing (15) is alleviated. Therefore, according to the eighth aspect, even if the oil level of the oil reservoir (18) in the casing (15) begins to lower, lowering of the oil level of the oil reservoir (18) in the casing (15) is alleviated by stopping oil supply to the oil groove (80). As a result, the oil level of the oil reservoir (18) does not become lower than the lubricating oil inlet (76) of the bearing oil supply passage (70), and oil supply to the bearing of the driving shaft (60) can be ensured. That is, the oil supply to the bearing of the driving shaft (60) is given a higher priority than the oil supply to the oil groove (80), and accordingly, fatal failures of the bearing of the driving shaft (60) caused by seizure can be prevented.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal cross-sectional view illustrating an overall configuration of a scroll compressor according to Embodiment 1.

FIG. 2 is a longitudinal cross-sectional view illustrating a configuration of a main portion of the scroll compressor of Embodiment 1.

FIG. 3 is a transverse cross-sectional view illustrating a configuration of a compression mechanism of the scroll compressor of Embodiment 1.

FIG. 4 is s longitudinal cross-sectional view illustrating a configuration of a main portion of a scroll compressor of Embodiment 2.

FIG. 5 is a longitudinal cross-sectional view illustrating an overall configuration of a scroll compressor according to Embodiment 3.

FIG. 6 is a longitudinal cross-sectional view illustrating configurations of first and second connection passages of the scroll compressor of Embodiment 3.

FIG. 7 is a longitudinal cross-sectional view illustrating a configuration of a third connection passage of the scroll compressor of Embodiment 3.

FIG. 8 is a longitudinal cross-sectional view illustrating a configuration of a connection pipe of the scroll compressor of Embodiment 3.

FIG. 9 is a longitudinal cross-sectional view illustrating a main portion of a conventional scroll compressor.

DESCRIPTION OF EMBODIMENTS

Embodiments of the present disclosure will be described in detail with reference to the drawings.

Embodiment

Embodiment 1 of the present disclosure is now described. A scroll compressor (10) of this embodiment is a hermetic compressor. The scroll compressor (10) is connected to a refrigerant circuit which performs a refrigerating cycle, and configured to suck and compress the refrigerant of the refrigerant circuit.

As illustrated in FIG. 1, the scroll compressor (10) includes a casing (15), and a compression mechanism (20), a motor (50), a lower bearing member (55), and a driving shaft (60) are housed in the inner space of the casing (15). The casing (15) is a hermetic container having a vertically oriented cylindrical shape. In the inner space of the casing (15), the compression mechanism (20), the motor (50), and the lower bearing member (55) are arranged in this order from top to bottom. The driving shaft (60) is disposed such that the axial direction of the driving shaft (60) is along the vertical direction of the casing (15). The structure of the compression mechanism (20) will be detailed later.

The casing (15) is provided with a suction pipe (16) and a discharge pipe (17). Both of the suction pipe (16) and the discharge pipe (17) penetrate the wall of the casing (15). The suction pipe (16) is connected to the compression mechanism (20). The discharge pipe (17) opens in room between the motor (50) and the compression mechanism (20) in the inner space of the casing (15).

The lower bearing member (55) includes a central cylindrical portion (56), and is provided with three arms (57), only one of which is illustrated in FIG. 1. The central cylindrical portion (56) has a nearly cylindrical shape. Each of the arms (57) extends outwardly from the outer circumferential surface of the central cylindrical portion (56). The angles formed between adjacent ones of the three arms (57) provided on the lower bearing member (55) are substantially equal to one another. The end of each of the arms (57) is secured to the casing (15). A bearing metal (58) penetrates a part of the central cylindrical portion (56) near its upper end. The bearing metal (58) is penetrated by an auxiliary journal portion (67) of the driving shaft (60) which will be described later. The central cylindrical portion (56) forms a journal bearing which supports the auxiliary journal portion (67).

The motor (50) includes a stator (51) and a rotor (52). The stator (51) is secured to the casing (15). The rotor (52) is disposed coaxially with the stator (51). The rotor (52) is penetrated by a main shaft portion (61) of the driving shaft (60) which will be described later.

The driving shaft (60) includes the main shaft portion (61), a balance weight (62), and an eccentric portion (63). The balance weight (62) is located in an intermediate part in the axial direction of the main shaft portion (61). Part of the main shaft portion (61) located below the balance weight (62) penetrates the rotor (52) of the motor (50). Part of the main shaft portion (61) located above the balance weight (62) forms a main journal portion (64). The auxiliary journal portion (67) is located below the part of the in shaft portion (61) penetrating the rotor (52). The main journal portion (64) penetrates a bearing metal (28) provided in a central bulge portion (27) of a housing (25). The auxiliary journal portion (67) penetrates the bearing metal (58) provided in the central cylindrical portion (56) of the lower bearing member (55).

The eccentric portion (63) has a circular column shape having a diameter smaller than the diameter of the main journal portion (64), and projects from the upper end surface of the main journal portion (64). The shaft center of the eccentric portion (63) is parallel with and eccentric relative to the shaft center of the main journal portion (64) (i.e., the shaft center of the main shaft portion (61)). The eccentric portion (63) penetrates a bearing metal (44) provided in a cylindrical portion (43) of an orbiting scroll (40).

The driving shaft (60) has an oil supply passage (77) formed therein. The oil supply passage (77) includes a main passage (74) and three branch passages (71-73). The main passage (74) extends along the shaft center of the driving shaft (60), and has an end which opens at the lower end of the main shaft portion (61) and the other end which opens on the upper end surface of the eccentric portion (63). The first branch passage (71) is located in the eccentric portion (63). The first branch passage (71) outwardly extends from the main passage (74) in a radial direction of the eccentric portion (63) and opens on the outer circumferential surface of the eccentric portion (63). The second branch passage (72) is located in the main journal portion (64). The second branch passage (72) outwardly extends from the main passage (74) in a radial direction of the main journal portion (64) and opens on the outer circumferential surface of the main journal portion (64). The third branch passage (73) is located in the auxiliary journal portion (67). The third branch passage (73) outwardly extends from the main passage (74) in a radial direction of the auxiliary journal portion (67) and opens on the outer circumferential surface of the auxiliary journal portion (67).

An oil supply pump (75) is mounted at the lower end of the driving shaft (60). The oils supply pump (75) is a trochoid pump which is driven by the driving shaft (60). The oil supply pump (75) is disposed near the starting end of the main passage (74) of the oil supply passage (77). The oil supply pump (75) has, at the lower end, a suction inlet (76) which opens downwardly and through which a refrigeration oil serving as lubricating oil is sucked. Note that the oil supply pump (75) is not limited to the trochoid pump and may be any displacement e pump driven by the driving shaft (60). Accordingly, the oil supply pump (75) may be a gear pump, for example. The oil supply pump (75) and the oil supply passage (77) together form a bearing oil supply passage (70) which supplies the refrigeration oil to journal bearings of the compression mechanism (20) which will be described later. The suction inlet (76) of the oil supply pump (75) serves as a refrigeration oil inlet for the bearing oil supply passage (70).

The refrigeration oil serving as lubricating oil is stored in a bottom portion of the casing (15). That is, the casing (15) has an oil reservoir (18) in its bottom portion. When the driving shaft (60) rotates, the oil supply pump (75) sucks the refrigeration oil from the oil reservoir (18) and discharges the same. The refrigeration oil discharged from the oil supply pump (75) flows through the main passage (74). The refrigeration oil flowing through the main passage (74) is supplied to the lower bearing member (55) and sliding parts of the compression mechanism (20) and the driving shaft (60). Since the oil supply pump (75) is a displacement pump, the rate of the refrigeration oil in the main passage (74) is proportional to the rotation speed of the driving shaft (60).

As illustrated in FIG. 2, the compression mechanism (20) includes the housing (25), a fixed scroll (30), and the orbiting scroll (40). The compression mechanism (20) is provided with an Oldham's coupling (24) for controlling rotation of the orbiting scroll (40).

The housing (25) has a disk shape with a large wall thickness, and the outer circumferential edge of the housing (25) is secured to the casing (15). The housing (25) has a central recess (26) and an annular projection (29) formed in its central part. The central recess (26) is a recess which has a circular column shape and opens on the upper surface of the housing (25). The annular projection (29) surrounds the central recess (26) and projects from the upper surface of the housing (25). The annular projection (29) has a flat top surface on which a ring-shaped groove is formed along the circumference of the annular projection (29). A seal ring (29a) is fitted in this groove.

The housing (25) has the central bulge portion (27) formed thereon. The central bulge portion (27) is located below the central recess (26) and bulges downward. The central bulge portion (27) has a through hole which vertically penetrates the central bulge portion (27). The bearing metal (28) penetrates through this through hole. The main journal portion (64) of the driving shaft (60) penetrates the bearing metal (28) of the central bulge portion (27). The central bulge portion (27) forms the journal bearing which supports the main journal portion (64).

The fixed scroll (30) and the orbiting scroll (40) are disposed on the housing (25). The fixed scroll (30) is secured to the housing (25) with, e.g. bolts. On the other hand, the orbiting scroll (40) is engaged with the housing (25) via the Oldham's coupling (24), and is provided movably relative to the housing (25). The orbiting scroll (40), which is engaged with driving shaft (60), performs orbital motion,

The orbiting scroll (40) is a component into which an end plate (41), a lap (42), and the cylindrical portion (43) are integrated. The end plate (41) of the orbiting scroll (40) has a disk-like shape. The lap (42) of the orbiting scroll (40) is formed in a spiral-shaped wall, and projects from the front side of the end plate (41) (i.e. from the upper surface of the end plate (41) in FIGS. 1 and 2). The cylindrical portion (43) has a cylindrical shape and projects from the backside of the end plate (41) (i.e. from the lower surface of the end plate (41) in FIGS. 1 and 2).

The backside of the end plate (41) of the orbiting scroll (40) is in sliding contact with the seal ring (29a) disposed on the annular projection (29) of the housing (25). On the other hand, the cylindrical portion (43) of the orbiting scroll (40) downwardly penetrates the central recess (26) of the housing (25). The bearing metal (44) penetrates the cylindrical portion (43). The eccentric portion (63) of the driving shaft (60) which will be detailed later upwardly penetrates the bearing metal (44) of the cylindrical portion (43). The cylindrical portion (43) forms the journal bearing which slides on the eccentric portion (63).

The fixed scroll (30) is a component into which an end plate (31), a lap (32), and an outer circumferential portion (33) are integrated. The end plate (31) of the fixed scroll (30) has a disk-like shape. The lap (32) of the fixed scroll (30) is formed in a spiral-shaped wall, and projects from the front side of the end plate (31) (i.e. from the lower surface of the end plate (31) in FIGS. 1 and 2). The outer circumferential portion (33) has a ring shape with a large wall thickness, and downwardly extends from the outer circumference of the end plate (31) to surround the lap (32).

The end plate (31) has a discharge port (22) formed therein. The discharge port (22) is a through hole formed near the center of the end plate (31), and penetrates the end plate (31) in the thickness direction. The suction pipe (16) penetrates a part of the end plate (31) near the outer circumference.

The compression mechanism (20) has a discharged gas passage (23) formed therein. The discharged gas passage (23) has the starting end which communicates with the discharge port (22). Although not shown, the discharged gas passage (23) extends from the fixed scroll (30) to the housing (25), and has the other end which opens on the lower surface of the housing (25).

In the compression mechanism (20), the fixed scroll (30) and the orbiting scroll (40) are disposed such that the front side of the end plate (31) faces the front side of the end plate (41), and the lap (32) and the lap (42) are engaged with each other. Accordingly, in the compression mechanism (20), a plurality of compression chambers (21) are formed by engagement of the laps (32, 42).

In the compression mechanism (20), the end plate (41) of the orbiting scroll (40) is in sliding contact with the outer circumferential portion (33) of the fixed scroll (30). Specifically, on the front side of the end plate (41) (i.e. on the upper surface of the end plate (41) in FIGS. 1 and 2), a part located outward relative to the lap (42) serves as a thrust sliding surface (45) which is in sliding contact with the fixed scroll (30). On the other hand, on the outer circumferential portion (33) of the fixed scroll (30), the top surface (i.e., the lower surface of the outer circumferential portion (33) in FIGS. 1 and 2) is in sliding contact with the thrust sliding surface (45) of the orbiting scroll (40). In the outer circumferential portion (33), a part which is in sliding contact with the thrust sliding surface (45) serves as a thrust sliding surface (35) of the fixed scroll (30).

As illustrated in FIGS. 2 and 3, the outer circumferential portion (33) of the fixed scroll (30) has an oil groove (80) and a connection passage (86) formed therein. The oil groove (80) is a groove formed by depressing the thrust sliding surface (35) of the outer circumferential portion (33), and has a ring shape surrounding the lap (32). The connection passage (86) has an end which communicates with the oil groove (80). The connection passage (86) extends from the end toward the outer circumference of the outer circumferential portion (33). A capillary tube (87) which will be detailed later is connected to a part near the other end of the connection passage (86). The connection passage (86) and the capillary tube (87) together form a groove communication passage (85).

The capillary tube (87) is a thin copper tube with an inside diameter of 0.5-1.0 mm, and serves as a throttle. The capillary tube (87) extends along the inner surface of the casing (15). Specifically, the capillary tube (87), which passes through a through hole formed in the housing (25) and penetrates the outer circumferential portion (33) of the fixed scroll (30), has the upper end communicating with the connection passage (86). The capillary tube (87) also penetrates through a core-cut part formed in the stator (51) of the motor (50) to reach the oil reservoir (18). Thus, the capillary tube (87) has the lower end soaked in the refrigeration oil stored in the bottom portion of the casing (15).

The lower end opening (88) of the capillary tube (87) serves as a refrigeration oil inlet through which the refrigeration oil is caused to flow into the groove communication passage (85). The lower end opening (88) of the capillary tube (87) is located higher than the suction inlet (76) of the oil supply pump (75). In this embodiment, the lower end opening (88) of the capillary tube (87) is located about 10 mm above the suction inlet (76) of the oil supply pump (75). That is, the inlet of the groove communication passage (85) is located higher than the refrigeration oil inlet of the bearing oil supply passage (70).

In this embodiment, the groove communication passage (85) constituted by the connection passage (86) and the capillary tube (87) connects the oil groove (80) only to the oil reservoir (18) in the casing (15). Accordingly, in this embodiment, the oil supply passage (77) formed in the driving shaft (60) is not in communication with the oil groove (80) located on the fixed scroll (30). That is, the bearing oil supply passage (70) is not in communication with the oil groove (80).

Operation

Operation by the scroll compressor (10) is now described.

In the scroll compressor (10), when the motor (50) is supplied with electricity, the driving shaft (60) drives the orbiting scroll (40). Since rotation of the orbiting scroll (40) is controlled by the Oldham's coupling (24), the orbiting scroll (40) only performs orbital motion without rotating.

When the orbiting scroll (40) performs orbital motion, the gaseous refrigerant with a low pressure having flowed into the compression mechanism (20) through the suction pipe (16) is sucked into the compression chamber (21) from the portions near the outer circumferential ends of the lap (32) and the lap (42). When the orbiting scroll (40) further moves, the compression chamber (21) becomes isolated from the suction pipe (16) to enter a completely closed state. The compression chamber (21) then moves along the lap (32) and the lap (42) toward the inner circumferential ends of the laps (32, 42). During this movement, the volume of the compression chamber (21) gradually decreases, and accordingly, the gaseous refrigerant in the compression chamber (21) is compressed in a gradual manner.

After the gradual decrease in the volume of the compression chamber (21) caused by the movement of the orbiting scroll (40), the compression chamber (21) comes into communication with the discharge port (22). The compressed refrigerant (i.e., the gaseous refrigerant with a high pressure) in the compression chamber (21) flows through the discharge port (22) to enter the discharge gas passage (23), and then is discharged to the inner space of the casing (15). In the inner space of the casing (15), the high-pressure gaseous refrigerant having been discharged from the compression mechanism (20) is initially guided to room below the stator (51) of the motor (50), and then, allowed to flow upwardly through, e.g., a gap between the rotor (52) and the stator (51). Thereafter, the gaseous refrigerant passes through the discharge pipe (17) to flow out to the outside of the casing (15).

In room below the housing (25) located in the inner space of the casing (15), the high-pressure gaseous refrigerant having been discharged from the compression mechanism (20) is flowing, and the room below the housing (25) has a pressure substantially equal to the pressure of the high-pressure gaseous refrigerant. Accordingly, the refrigeration oil stored in the oil reservoir (18) in the casing (15) has a pressure substantially equal to the pressure of the high-pressure gaseous refrigerant.

On the other hand, room above the housing (25) located in the inner space of the casing (15), although not shown, communicates with the suction pipe (16), and has a pressure approximate to the pressure of the low-pressure gaseous refrigerant sucked into the compression mechanism (20). Accordingly, in the compression mechanism (20), room near the outer circumference of the end plate (41) of the orbiting scroll (40) has a pressure approximate the pressure of the low-pressure gaseous refrigerant.

During operation of the scroll compressor (10), the driving shaft (60) rotates and drives the oil supply pump (75), and the refrigeration oil stored in the bottom portion of the casing (15) is sucked and supplied to the main passage (74) of the oil supply passage (77). Part of the refrigeration oil flowing through the main passage (74) flows into the branch passages (71-73) and the remainder of the refrigeration oil flows out from the upper end of the main passage (74).

The refrigeration oil having flowed into the first branch passage (71) is supplied to a gap between the eccentric portion (63) and the bearing metal (44) to be used to lubricate and cool the eccentric portion (63) and the bearing metal (44). The refrigeration oil having flowed into the second branch passage (72) is supplied to a gap between the main journal portion (64) and the bearing metal (28) to be used to lubricate and cool the main journal portion (64) and the bearing metal (28). The refrigeration oil having flowed into the third branch passage (73) is supplied to a gap between the auxiliary journal portion (67) and the bearing metal (58) to be used to lubricate and cool the auxiliary journal portion (67) and the bearing metal (58). In addition, in the compression mechanism (20), the sliding parts of the orbiting scroll (40) and the Oldham's coupling (24) and the sliding parts of the orbiting scroll (40) and the fixed scroll (30) are supplied with the refrigeration oil.

The compression mechanism (20) of this embodiment is configured such that the orbiting scroll (40) is pressed against the fixed scroll (30) by using the refrigeration oil supplied from the oil reservoir (18) located in the casing (15).

Specifically, in the compression mechanism (20), the backside of the end plate (41) of the orbiting scroll (40) is in sliding contact with the seal ring (29a). The refrigeration oil having flowed out from the terminal end of the main passage (74) of the oil supply passage (77) is present in the central recess (26) located inside that seal ring (29a). This refrigeration oil has a pressure approximate to the pressure of the refrigeration oil in the oil reservoir (18).

In the orbiting scroll (40), the pressure of the refrigeration oil having flowed out from the main passage (74) acts on a part of the backside of the end plate (41) located inside the seal ring (29a), and on the surface of the cylindrical portion (43). Consequently, a pressing force toward the fixed scroll (30) (i.e., an upward force in this embodiment) acts on the orbiting scroll (40). As a result, also during operation of the compression mechanism (20), the orbiting scroll (40) is kept pressed against the fixed scroll (30), thereby ensuring air tightness of the compression chambers (21).

However, the pressing force acting on the orbiting scroll (40) sometimes becomes too strong. The excessively strong pressing force increases the friction force acting between the orbiting scroll (40) and the fixed scroll (30), and accordingly, causes an increase in power consumption of the motor (50).

To address this problem, the scroll compressor (10) of this embodiment includes the oil groove (80) which communicates with the oil reservoir (18) in the casing (15) through the groove communication passage (85) and which is kept filled with the high-pressure refrigeration oil. On the other hand, the compression chamber (21) adjacent to the oil groove (80) (i.e., the compression chamber (21) formed near the outermost parts of the laps (32, 42)) has a pressure approximate to the pressure of the low-pressure refrigerant sucked into the compression chamber (21) and which is lower than the pressure of the refrigeration oil in the oil groove (80). Consequently, the refrigeration oil in the oil groove (80) gradually flows out to enter a clearance between the thrust sliding surface (45) and the thrust sliding surface (35) to be used to lubricate the thrust sliding surfaces (35, 45).

In this manner, the scroll compressor (10) of this embodiment ensures that the refrigeration oil is supplied to the clearance between the thrust sliding surface (45) and the thrust sliding surface (35). Accordingly, even in a state where the orbiting scroll (40) is strongly pressed against the fixed scroll (30), the friction force between the thrust sliding surface (45) and the thrust sliding surface (35) does not become excessively strong.

In the orbiting scroll (40) of the scroll compressor (10), the internal pressure of the compression chambers (21) acts on the lap (42) projecting from the front side of the end plate (41), and a load from the eccentric portion (63) acts on the cylindrical portion (43) projecting from the backside of the end plate (41). The line of action of the gas pressure acting on the lap (42) and the line of action of the load acting on the cylindrical portion (43) intersect the axial direction of the orbiting scroll (40) at right angles but do not intersect each other. Accordingly, during operation of the compression mechanism (20), a moment acts on the orbiting scroll (40) in a direction tilting the orbiting scroll (40). If the pressing force acting on the orbiting scroll (40) is sufficiently strong, the orbiting scroll (40) is not tilted even by the moment acting thereon.

However, in an operational state where the pressing force is insufficiently strong, the orbiting scroll (40) is sometimes tilted, thereby increasing the clearance between the thrust sliding surface (45) and the thrust sliding surface (35). For example, the pressing force may become insufficiently strong in an operational state where the pressure difference between the low-pressure gaseous refrigerant sucked into the compression mechanism (20) and the high-pressure gaseous refrigerant discharged from the compression mechanism (20) is small, or in an operational state where the rotation speed of the driving shaft (60) is considerably low (e.g., 10-20 rotations per second).

As described above, in the compression mechanism (20), the pressure of the room near the outer circumference of the end plate (41) is approximate to the pressure of the low-pressure gaseous refrigerant sucked into the compression mechanism (20). On the other hand, when the orbiting scroll (40) is tilted and the clearance between the thrust sliding surface (45) and the thrust sliding surface (35) increases, a flow resistance in the clearance between the thrust sliding surfaces (35, 45) decreases. Accordingly, tilting of the orbiting scroll (40) may cause a large amount of the refrigeration oil to spout out from the oil groove (80) to the room near the outer circumference of the end plate (41).

In addition, tilting of the orbiting scroll (40) may reduce a pressure loss caused when the refrigeration oil passes through the clearance between the thrust sliding surface (45) and the thrust sliding surface (35), and accordingly, the pressure acting on the thrust sliding surfaces (35, 45) increases to become approximate to the pressure of the refrigeration oil in the oil groove (80). In such a case, a force separating the orbiting scroll (40) from the fixed scroll (30) becomes strong, and the air tightness of the compression chambers (21) may be reduced.

To address this problem, the scroll compressor (10) of this embodiment includes the capillary tube (87) provided in the groove communication passage (85). Even in a state where the orbiting scroll (40) has been tilted and the clearance between the thrust sliding surface (45) and the thrust sliding surface (35) has increased, the capillary tube (87) controls the flow rate of the refrigeration oil in the groove communication passage (85).

In this manner, in the compression mechanism (20) of this embodiment, even in a state where the orbiting scroll (40) has been tilted, the flow rate of the refrigeration oil flowing from the groove communication passage (85) to the oil groove (80) and the pressure of the oil groove (80) are kept low. Consequently, even if the orbiting scroll (40) is tilted during operation of the compression mechanism (20), the pressure acting on the thrust sliding surfaces (35, 45) is kept low, and the force separating the orbiting scroll (40) from the fixed scroll (30) is not allowed to become excessively strong. On the other hand, the pressing force acts on the orbiting scroll (40) to press the orbiting scroll (40) against the fixed scroll (30). Therefore, the orbiting scroll (40) which has been tilted during operation of the compression mechanism (20) quickly restores the original position by receiving the pressing force.

Here, if the pressure loss caused when the refrigeration oil moves from one end to the other end of the groove communication passage (85) is too small and tilting of the orbiting scroll (40) causes the pressure in the oil groove (80) to decrease, the flow rate of the refrigeration oil in the groove communication passage (85) abruptly increases and a large amount of the refrigeration oil spouts from the terminal end of the groove communication passage (85). On the other hand, if the pressure loss caused when the refrigeration oil moves from an end to the other end of the groove communication passage (85) is too large, it may take a longer time for the pressure of the oil groove (80) to become sufficiently high after tilting of the orbiting scroll (40) has been eliminated, and an insufficient amount of the refrigeration oil may be supplied to the clearance between the thrust sliding surface (45) and the thrust sliding surface (35).

To address this problem, in this embodiment, the connection passage (86) and the capillary tube (87) together form the groove communication passage (85). According to this embodiment, the inside diameter and the length of the capillary tube (87) are adjusted such that the pressure loss caused when the refrigeration oil moves from one end to the other of the groove communication passage (85) becomes an appropriate value.

As described above, in the scroll compressor (10) of this embodiment, the refrigeration oil in the oil groove (80) gradually flows out to enter the clearance between the thrust sliding surface (45) of the orbiting scroll (40) and the thrust sliding surface (35) of the fixed scroll (30) to be used to lubricate the thrust sliding surfaces (35, 45). Part of the refrigeration oil having been used to lubricate the thrust sliding surfaces flows into the compression chamber (21) adjacent to the oil groove (80), and is then discharged together with the gaseous refrigerant to the inner spacer of the casing (15). The discharged refrigeration oil and the gaseous refrigerant are dispersed within the inner space of the casing (15), and then, are initially guided to room below the stator (51) of the motor (50). Part of the refrigeration oil drops to be stored in the oil reservoir (18) whereas the remainder of the refrigeration oil and the gaseous refrigerant flow upwardly through, e.g., a gap between the rotor (52) and the stator (51) to be discharged to the outside of the casing (15) through the discharge pipe (17).

The refrigeration oil which has been discharged together with the gaseous refrigerant to the outside of the casing (15) in the above described manner circulates, together with the refrigerant, through the refrigerant circuit to which the scroll compressor (10) is connected, and then, is sucked again into the scroll compressor (10). The refrigeration oil having been sucked into the scroll compressor (10) is discharged together with the compressed gaseous refrigerant to the inner space of the casing (15). Part of the refrigeration oil is returned to the oil reservoir (18) in the casing (15).

Meanwhile, depending on operational states, return of the refrigeration oil to casing (15) of the scroll compressor (10) is sometimes impeded. For example, a low temperature of an evaporator causes an increase in the viscosity of the refrigeration oil. This increase in the viscosity causes the refrigeration oil to easily accumulate in the evaporator, and results in an impediment to return of the refrigeration oil to the scroll compressor (10). When this operation state continues, the amount of the refrigeration oil discharged together with gaseous refrigerant from the casing (15) becomes larger than the amount of refrigeration oil returned to the casing (15). Accordingly, the amount of the refrigeration oil in the oil reservoir (18) decreases, resulting in that the oil level is lowered. When the oil level of the oil reservoir (18) in the casing (15) becomes lower than the suction inlet (76) of the oil supply pump (75) (i.e., the refrigeration oil inlet of the bearing oil supply passage (70)) and the lower end opening (88) of the capillary tube (87) (i.e., the refrigeration oil inlet of the groove communication passage (85)), it becomes impossible to supply the refrigeration oil from the oil reservoir (18) to the journal bearings and the oil groove (80) of the compression mechanism (20).

An insufficient amount of the refrigeration oil supplied to the journal bearings of the compression mechanism (20) may cause seizure and failure of the journal bearings. On the other hand, an insufficient amount of the refrigeration oil supplied to the oil groove (80) may cause an increase in the friction force between the thrust sliding surface (45) of the orbiting scroll (40) and the thrust sliding surface (35) of the fixed scroll (30), and an increase in the power consumption of the motor.

When an insufficient amount of the refrigeration oil is supplied to the bearing of the driving shaft (60), even for a short time, the journal bearings may be fatally damaged and the compressor may become unable to operate properly. On the other hand, when an insufficient amount of the refrigeration oil is supplied to the oil groove (80) only for a short time, the compressor does not suffer fatal damage although the performance is temporary reduced by insufficient sealing of the thrust sliding surfaces (35, 45). That is, an oil shortage of the journal bearings of the compression mechanism (20) must be dealt with more quickly than an oil shortage of the oil groove (80).

To address this problem, the scroll compressor (10) of this embodiment has the configuration in which the lower end opening (88) of the capillary tube (87) serving as the refrigeration oil inlet of the groove communication passage (85) is located higher than the suction inlet (76) of the oil supply pump (75) serving as the refrigeration oil inlet of the bearing oil supply passage (70). With this configuration, when the refrigeration oil in the oil reservoir (18) in the casing (15) decreases, the oil level of the oil reservoir (18) first becomes lower than the lower end opening (88) of the capillary tube (87), and supply of the refrigeration oil to the oil groove (80) is stopped. Thus, even when the oil level of the oil reservoir (18) in the casing (15) is lowered, the stop of supply of the refrigeration oil to the oil groove (80) causes a decrease in the amount of the refrigeration oil discharged together with the refrigerant to the outside of the casing (15). Consequently, the amount of the refrigeration oil discharged to the outside of the casing (15) falls short of the amount of the refrigeration oil returned to the inside of the casing (15), and lowering of the oil level of the oil reservoir (18) in the casing (15) is alleviated. In this manner, lowering of the oil level of the oil reservoir (18) in the casing (15) is alleviated such that the oil level of the oil reservoir (18) will not become lower than the suction inlet (76) of the bearing oil supply passage (70) and oil supply to the journal bearings of the compression mechanism (20) is ensured.

Advantages of Embodiment 1

According to this embodiment, the fixed scroll (30) has the oil groove (80) formed on the thrust sliding surface (35). The bearing oil supply passage (70) supplying the refrigeration oil to the journal bearings of the compression mechanism (20) is not in communication with the oil groove (80). Therefore, even when the orbiting scroll (40) is tilted and the pressure of the oil groove (80) abruptly drops during operation of the compression mechanism (20), the pressure of the bearing oil supply passage (70) remains unchanged.

If the oil groove (80) and the bearing oil supply passage (70) communicated with each other, an abrupt pressure drop of the oil groove (80) would cause a decrease in the pressure of the bearing oil supply passage (70). The pressure decrease of the bearing oil supply passage (70) would cause the refrigeration oil to flow backward from the journal bearings of the compression mechanism (20) to the bearing oil supply passage (70), and would lead to a shortage of the lubricating oil for the journal bearings.

In contrast, the bearing oil supply passage (70) of this embodiment is not in communication with the oil groove (80). An abrupt pressure drop of the oil groove (80) does not cause the pressure of the bearing oil supply passage (70) to change. Therefore, according to this embodiment, even if the orbiting scroll (40) is tilted and the pressure of the oil groove (80) abruptly drops, the refrigeration oil is not allowed to flow backward from the journal bearings of the compression mechanism (20) to the bearing oil supply passage (70), and it is accordingly ensured that the refrigeration oil continues to be supplied to the journal bearings of the compression mechanism (20) through the bearing oil supply passage (70). Consequently, lubrication of the journal bearings of the compression mechanism (20) is ensured, and troubles such as seizure are prevented, thereby enabling improvement of the reliability of the scroll compressor (10).

In this embodiment, the refrigeration oil discharged from the oil supply pump (75) driven by the driving shaft (60) passes through the bearing oil supply passage (70), which is not in communication with the oil groove (80), to be supplied to the journal bearings of the compression mechanism (20). Accordingly, even in a state where the orbiting scroll (40) has been tilted and the pressure of the oil groove (80) has abruptly dropped during operation of the compression mechanism (20), the refrigeration oil can be supplied to the journal bearings of the compression mechanism (20) in a stable manner. Therefore, according to this embodiment, supply of the refrigeration oil to the journal bearings of the compression mechanism (20) is endured regardless of the pressure of the oil groove (80), and accordingly, it can be ensured that troubles such as seizure of the journal bearings are avoided.

When the orbiting scroll (40) is tilted under conditions in which the pressure loss caused when the refrigeration oil moves from one end to the other of the groove communication passage (85) is too small, the clearance between the thrust sliding surface (45) and the thrust sliding surface (35) is increased by the tilting of the orbiting scroll (40), and consequently, a large amount of the refrigeration oil spouts from the terminal end of the groove communication passage (85). Under conditions in which the pressure loss caused when the refrigeration oil moves from one end to the other of the groove communication passage (85) is too large, it may take a longer time for the pressure of the oil groove (80) to become sufficiently high after tilting of the orbiting scroll (40) has been eliminated, and an insufficient amount of the refrigeration oil may be supplied to the clearance between the thrust sliding surface (45) and the thrust sliding surface (35).

To address this problem, in this embodiment, the capillary tube (87) forms part of the groove communication passage (85) such that the pressure loss caused when the refrigeration oil moves from one end to the other of the groove communication passage (85) is adjusted to an appropriate value. Accordingly, even in a state where the orbiting scroll (40) has been tilted, it is possible to prevent the flow rate of the refrigeration oil in the groove communication passage (85) from increasing excessively. Consequently, even when the orbiting scroll (40) is tilted, the pressure of the oil groove (80) can be kept low by controlling the flow rate of the refrigeration oil flowing from the groove communication passage (85) into the oil groove (80), and accordingly, it is possible to cause the tilted orbiting scroll (40) to restore the original position quickly. In addition, once the orbiting scroll (40) has restored the original position, the pressure of the oil groove (80) can be quickly increased to ensure that a sufficient amount of the refrigeration oil is supplied to the clearance between the thrust sliding surface (45) and the thrust sliding surface (35).

In the scroll compressor (10) of this embodiment, the lower end opening (88) of the capillary tube (87) serving as the refrigeration oil inlet of the groove communication passage (85) is located higher than the suction inlet (76) of the oil supply pump (75) serving as the refrigeration oil inlet of the bearing oil supply passage (70). Accordingly, lowering of the oil level of the oil reservoir (18) in the casing (15) first stops supply of the refrigeration oil to the oil groove (80), and the amount of the refrigeration oil discharged together with the refrigerant to the outside of the casing (15) is reduced. Consequently, the amount of the refrigeration oil discharged to the outside of the casing (15) falls short of the amount of the refrigeration oil returned to the inside of the casing (15), and lowering of the oil level of the oil reservoir (18) in the casing (15) is alleviated. Therefore, according to the scroll compressor (10) of this embodiment, even if the oil level of the oil reservoir (18) in the casing (15) begins to lower, lowering of the oil level of the oil reservoir (18) in the casing (15) is alleviated by stopping supply of the refrigeration oil to the oil groove (80) such that the oil level of the oil reservoir (18) will not become lower than the inlet (76) of the oil supply pump (75), and the oil supply to the journal bearings of the compression mechanism (20) can be ensured. That is, the oil supply to the journal bearings of the compression mechanism (20) is given a higher priority than the oil supply to the oil groove (80), and fatal failures of the journal bearings can be prevented.

Embodiment 2

Embodiment 2 of the present disclosure will be described below, focusing on differences between a scroll compressor (10) of Embodiment 2 and that of Embodiment 1.

As illustrated in FIG. 4, in a compression mechanism (20) of this embodiment, an oil groove (80) is formed not on a fixed scroll (30) but on an orbiting scroll (40). Specifically, the oil groove (80) of this embodiment is located on an end plate (41) of the orbiting scroll (40). The oil groove (80) is a groove formed by depressing a thrust sliding surface (45) of the end plate (41), and has a ring shape surrounding a lap (42) of the orbiting scroll (40). In this embodiment, a terminal end of a connection passage (86) opens on a thrust sliding surface (35) of the fixed scroll (30). The terminal end of the connection passage (86) has a large width such that the connection passage (86) can continue to communicate with the oil groove (80) even when the orbiting scroll (40) moves,

According to this embodiment, in a manner similar to Embodiment 1, a bearing oil supply passage (70) is not in communication with the oil groove (80), a refrigeration oil is caused to flow through the groove communication passage (85) only by a pressure difference between an oil reservoir (18) in a casing (15) and the oil groove (80), and a capillary tube (87) forms part of the groove communication passage (85). Accordingly, this embodiment provides advantages similar to those of Embodiment 1.

Embodiment 3

Embodiment 3 of the present disclosure will be described below, focusing on differences between a scroll compressor (10) of Embodiment 3 and that of Embodiment 1.

As illustrated in FIG. 5, in this embodiment, a central cylindrical portion (56) of a lower bearing member (55) is different from that of Embodiment 1. Specifically, the central cylindrical portion (56) extends along an auxiliary shaft portion (67) which forms a lower end part of a driving shaft (60), from the upper end to the lower end of auxiliary shaft portion (67). The central cylindrical portion (56) has a recess formed in an upper end part thereof, and a rolling bearing (54) is provided in the recess. The rolling bearing (54) is penetrated by the auxiliary shaft portion (67) of the driving shaft (60). With this configuration, the central cylindrical portion (56) serves as an auxiliary bearing which supports the auxiliary shaft portion (67).

Further, in this embodiment, a first connection passage (81) formed in a fixed scroll (30), a second connection passage (82) formed in a housing (25), a third connection passage (83) formed in the lower bearing member (55), and a connection pipe (84) connecting the second connection passage (82) to the third connection passage (83) together form a groove communication passage (85).

As illustrated in FIG. 6, the first connection passage (81) located in an outer circumferential portion (33) of a fixed scroll (30), and includes an inner vertical communicating path (81a) which vertically extends in an inner edge part of an outer circumferential portion (33), a transverse communicating path (81b) which radially extends in the outer circumferential portion (33), and an outer vertical communicating path (81c) which vertically extends in an outer edge part of the outer circumferential portion (33).

The inner vertical communicating path (81a) has an upper end which opens on the upper surface of an end plate (31) and a lower end which opens in an oil groove (80) formed on a thrust sliding surface (35). The inner vertical communicating path (81a) has a female thread (81d) formed on the wall of its upper end part. A rod member (89) which will be detailed later is provided in the inner vertical communicating path (81a), and a head (89d) of the rod member (89) closes the upper end of the communicating path (81a).

The transverse communicating path (81b) radially outwardly extends from a point located immediately below the female thread (81d) of the inner vertical communicating path (81a), and has an outer end which opens on the outer circumferential surface of the fixed scroll (30). The opening of the outer end of the transverse communicating path (81b) is closed with a plug member.

The outer vertical communicating path (81c) extends downwardly from a point located slightly inward relative to the outer end of the transverse communicating path (81b), and has a lower end which opens on the lower end surface of the fixed scroll (30).

Thus, the inner vertical communicating path (81a), the transverse communicating path (81b), and the outer vertical communicating path (81c) successively communicate with each other, and thereby together form the first connection passage (81) which connects the oil groove (80) to the lower end surface of the fixed scroll (30).

The second connection passage (82) vertically extends in an outer circumferential part of the housing (25). An upper end of the second connection passage (82) opens on the upper end surface of the housing (25) and corresponds to the outer vertical communicating path (81c) of the first connection passage (81), and thereby causes the second connection passage (82) to communicate with the first connection passage (81). On the other hand, a lower end of the second connection passage (82) opens on the lower end surface of the housing (25). The second connection passage (82) has a diameter which is slightly larger than that of the outer vertical communicating path (81c) of the first connection passage (81). The second connection passage (82) includes, in a lower end part, a smaller diameter section which has a diameter slightly smaller than the diameter of the other part. As will be detailed later, an upper end part (84a) of the connection pipe (84) and an upper part (91b) of a coupling pipe (91) are pressed into the smaller diameter section. With this configuration, the second connection passage (82) connects the first connection passage (81) to the connection pipe (84).

As illustrated in FIG. 7, the third connection passage (83) includes an inner vertical communicating path (83a) which vertically extends in the central cylindrical portion (56) of the lower bearing member (55), a transverse communicating path (83b) which radially extends from the central cylindrical portion (56) to enter an arm (57), and an outer vertical communicating path (83c) which vertically extends in an outer edge part of the arm (57).

The inner vertical communicating path (83a) has an upper end which is connected to the recess and opens below the rolling bearing (54) provided in the recess, and a lower end which opens at the lower end of the central cylindrical portion (56) located in an oil reservoir (18). The inner vertical communicating path (83a) has a female thread (83d) formed on the wall of its upper end part. Another rod member (89) which will be detailed later is provided in the inner vertical communicating path (83a), and the head (89d) of the rod member (89) closes the upper end of the inner vertical communicating path (83a).

The transverse communicating path (83b) radially outwardly extends from a point located immediately below the female thread (83d) formed in the upper end part of the inner vertical communicating path (83a), and has an outer end which opens on the outer circumferential surface of the arm (57). The opening of the outer end of the transverse communicating path (83b) is closed with a plug member. The outer vertical communicating path (83c) has an upper end which opens on the upper end surface of the arm (57), and a lower end which opens on the lower end surface of the arm (57). The outer vertical communicating path (83c) communicates with the transverse communicating path (83b) at a point located slightly inward relative to the outer end of the transverse communicating path (83b).

A lower end part (84b) of the connection pipe (84) is inserted in an upper part of the outer vertical communicating path (83c), whose lower end opening is closed with a plug member. The outer vertical communicating path (83c) has, in its upper end part, a larger diameter section which has a diameter larger than that of a main middle part of the communicating path (83c). In the larger diameter section, the upper half has a diameter which is further larger than that of the lower half. A projection (93a) of a pressing member (93) is inserted in the upper half, and an O-ring (92) is provided in the lower half.

The pressing member (93) is a plate-like piece of metal having a penetration hole (93b) through which the connection pipe (84) penetrates and a bolt hole (93c) through which a bolt penetrates. The pressing member (93) has a projection (93a) which continues from the peripheral wall of the penetration hole (93b) and projects downwardly relative to the other part of the pressing member (93). The pressing member (93) is fastened to the a (57) of the lower bearing member (55) with the bolt penetrating through the bolt hole (93c) in such a manner that the projection (93a) penetrates the larger diameter section of the outer vertical communicating path (83c) while pressing the O-ring (92). The pressing member (93) as described above presses the O-ring (92), through which the connection pipe (84) penetrates, against the outer vertical communicating path (83c). In this manner, sealing between the inner space of the casing (15) and the outer vertical communicating path (83c) is accomplished.

Thus, the inner vertical communicating path (83a), the transverse communicating path (83b), and the outer vertical communicating path (83c) successively communicate with each other, and thereby together form the third connection passage (83) which connects the oil reservoir (18) to the connection pipe (84).

The connection pipe (84) is a resin pipe made of a resin material. As illustrated in FIG. 8, in the connection pipe (84), the upper end part (84a) has a diameter which is larger than that of a main middle part whereas the lower end part (84b) has a diameter which is smaller than that of the main middle part. A lower part (91a) of the coupling pipe (91) which is made of stainless steel is pressed into the upper end part (84a) having the larger diameter.

In the coupling pipe (91), the lower part (91a) located lower relative to the axial midpoint has a diameter which is smaller than that of the upper part (91b) located upper relative to the axial midpoint. Specifically, the lower part (91a) of the coupling pipe (91) has an outside diameter which is slightly larger than an inside diameter of the upper end part (84a) of the connection pipe (84), and is slightly smaller than an outside diameter of the upper end part (84a) of the connection pipe (84). On the other hand, the upper part (91b) has an outside diameter which is substantially equal to the outside diameter of the upper end part (84a) of the connection pipe (84).

As illustrated in FIG. 6, the lower part (91a) of the coupling pipe (91) is pressed into the upper end part (84a) of the connection pipe (84), and the upper end part (84a) is pressed into the smaller diameter section located in the lower end part of the second connection passage (82). Accordingly, the upper end part (84a) of the connection pipe (84) and the upper part (91b) of the coupling pipe (91) are in contact with wall of the smaller diameter section in the lower end part of the second connection passage (82). Consequently, sealing between the inner space of the casing (15) and the second connection passage (82) is accomplished by the connection pipe (84) and the coupling pipe (91). In this manner, the second connection passage (82) communicates with the connection pipe (84) through the coupling pipe (91) without communicating with the inner space of the casing (15).

On the other hand, as illustrated in FIG. 7, the lower end part (84b) of the connection pipe (84) penetrates an upper part of the outer vertical communicating path (83c) of the third connection passage (83). Specifically, the lower end part (84b) of the connection pipe (84) penetrates through the penetration hole (93b) of the pressing member (93) and the O-ring (92), and the tip of the connection pipe (84) is positioned near the point where the outer vertical communicating path (83c) and the transverse communicating path (83b) of the third connection passage (83) communicate with each other. This configuration in which the connection pipe (84) penetrates through the O-ring (92) and then in the outer vertical communicating path (83c) of the third connection passage (83) allows the third connection passage (83) to communicate with the inside of the connection pipe (84) without communicating with the inner space of the casing (15).

As shown enlarged in FIGS. 6 and 7, each of the rod members (89) provided in the inner vertical communicating path (81a) of the first connection passage (81) and the inner vertical communicating path (83a) of the third connection passage (83) includes a body part (89a), a smaller diameter part (89b), a screw part (89c), and the head (89d), all of which are continuously formed from the tip toward the base of the rod member.

The body part (89a) is a rod-like member in a circular column shape and has a spiral thin groove (89e) with a width of about 0.5-1.0 mm formed on its outer circumference. The body part (89a) configured in this manner causes a narrow spiral channel to be formed between the wall of each of the inner vertical communicating paths (81a, 83a) and the body part (89a). The smaller diameter part (89b) has a diameter smaller than the diameters of the inner vertical communicating paths (81a, 83a) and causes an annular passage to be formed between the wall of each of the inner vertical communicating paths (81a, 83a) and the smaller diameter part (89b). The inner end of each of the transverse communicating paths (81b, 83b) opens in the associated annular passage. The screw part (89c) is a rod-like member in a circular column shape, and has on its outer circumference a male thread which is threadedly engaged with the female threads (81d, 83d) formed in the upper end parts of the inner vertical communicating paths (81a, 83a). The head (89d) is in a disc shape having a diameter larger than the diameters of the inner vertical communicating paths (81a, 83a).

The rod member (89) as described above causes, by means of the body part (89a), the narrow spiral channel be formed in each of the inner vertical communicating paths (81a, 83a) where the rod member (89) is disposed. The narrow spiral channel formed on the outer circumference of the rod member (89) controls flow rate of the refrigeration oil which has flowed into each of the inner vertical communicating paths (81a, 83a). That is, each of the rod members (89) serves as a throttle for controlling the flow rate of the refrigeration oil in the groove communication passage (85).

In this embodiment, the groove communication passage (85), which includes the first, second, third connection passages (81-83) and the connection pipe (84), connects the oil groove (80) only to the oil reservoir (18) in the casing (15). Accordingly, in a manner similar to Embodiment 1, this embodiment is also configured such that an oil supply passage (77) formed in the driving shaft (60) is not in communication with the oil groove (80) formed on the fixed scroll (30). Thus, a bearing oil supply passage (70) is not in communication with the oil groove (80), and the refrigeration oil is caused to flow through the groove communication passage (85) only by a pressure difference between the oil reservoir (18) in the casing (15) and the oil groove (80).

Specifically, the refrigeration oil in the oil reservoir (8) flows through the groove communication passage (85), by passing consecutively through the third connection passage (83), the connection pipe (84), the second connection passage (82), and the first connection passage (81), and then, is supplied to the oil groove (80). Consequently, the oil groove (80) is filled with the refrigeration oil with a high pressure, and the refrigeration oil in the oil groove (80) gradually flows out to enter a clearance between the thrust sliding surface (45) and the thrust sliding surface (35) to be used to lubricate the thrust sliding surfaces (35, 45).

Thus, also in this embodiment, it is ensured that the refrigeration oil is supplied to the clearance between the thrust sliding surface (45) and the thrust sliding surface (35). Accordingly, even in a state where the orbiting scroll (40) is strongly pressed against the fixed scroll (30), the friction force generated between the thrust sliding surface (45) and the thrust sliding surface (35) is not allowed to become excessively strong.

Further, the groove communication passage (85) of this embodiment is also equipped with the throttles, i.e. the rod members (89), for controlling the flow rate of the refrigeration oil. Accordingly, also in this embodiment, even in a state where the orbiting scroll (40) has been tilted and the clearance between the thrust sliding surface (45) and the thrust sliding surface (35) has increased, the flow rate of the refrigeration oil having flowed into the groove communication passage (85) is controlled by the narrow spiral channels formed on the outer circumferences of the rod members (89).

Thus, also in this embodiment, even in a state where the orbiting scroll (40) has been tilted, the flow rate of the refrigeration oil flowing from the groove communication passage (85) into the oil groove (80) and the pressure of the oil groove (80) are kept low. Accordingly, even when the orbiting scroll (40) is tilted during operation of the compression mechanism (20), the pressure acting on the thrust sliding surfaces (35, 45) is kept low, and the force separating the orbiting scroll (40) from the fixed scroll (30) is not allowed to become excessively strong. On the other hand, pressing force acts on the orbiting scroll (40) to press the orbiting scroll (40) against the fixed scroll (30). Accordingly, the orbiting scroll (40) which has been tilted during operation of the compression mechanism (20) quickly restores the original position by receiving the pressing force. Consequently, this embodiment provides advantages similar to those of Embodiment 1.

Further, according to this embodiment, the throttle which controls the flow rate of the refrigeration oil in the groove communication passage (85) can be easily provided simply by inserting into the groove communication passage (85) the rod member (89) having the spiral groove (89e) formed on the outer circumference. Furthermore, the cross-sectional area of the groove communication passage (85) can be easily varied simply by changing the cross-sectional shape of the spiral groove (89e) formed on the outer circumference of the rod member (89). That is, use of the rod member (89) as the throttle increases the degree of freedom of design and makes it easy to change the design.

When using the rod member (89), which has the spiral groove (89e) on the outer circumference as described above, as the throttle for controlling the flow rate of the refrigeration oil in the groove communication passage (85), the narrow channel formed with the spiral groove (89e) needs to be long to some extent in order o obtain a sufficient throttle effect. Increasing the length of the narrow channel by using a longer rod member (89), however, requires a longer space in which the longer rod member (89) is placed. In addition, installation of the longer rod member (89) may require much time and effort.

To address this problem, in this embodiment, a plurality of the rod members (89) serving as the throttles are provided in a plurality of locations of the groove communication passage (85). Accordingly, it is possible to increase the total length of the narrow channels by using the rod members (89) each of which is short, and the flow rate of the lubricating oil in the groove communication passage (85) can be sufficiently controlled. In other words, providing the plurality of rod members (89) in the plurality of locations of the groove communication passage (85) makes it possible to reduce the length of each of the rod members (89). Consequently, it is unnecessary to ensure long spaces for installation of the rod members (89), and the rod members (89) can be easily installed.

Furthermore, in this embodiment, both of the lower bearing member (55) and the fixed scroll (30) include the connection passages serving as the communicating paths which form part of the groove communication passage (85), and are provided with the throttles. Specifically, each of the third connection passage (83) in the lower bearing member (55) and the first connection passage (81) in the fixed scroll (30) is provided with the rod member (89) serving as the throttle. Accordingly, even if each of rod members (89) and each of the communicating paths (i.e. the third connection passage (83) and the first connection passage (81)) is short, the narrow channels can have a large length in total. Consequently, the flow rate of the refrigeration oil in the groove communication passage (85) can be sufficiently controlled. In other words, designing each of the lower bearing member (55) and the fixed scroll (30) to include the associated communicating path (i.e. the third connection passage (83) or the first connection passage (81)) and the associated rod member (89) provided in the associated communicating path enables reduction of the length of each of the rod members (89). Consequently, it is unnecessary to ensure long spaces for installation of the rod members (89), and the rod members (89) can be easily installed.

According to this embodiment, the connection pipe (84) forming part of the groove communication passage (85) is provided between the casing (15) and a motor (50). If the connection pipe (84) provided on a side of the motor (50) was a metal pipe, it would be necessary to space the connection pipe (84) from the motor (50) at a distance which ensures insulation, and the diameter of the casing (15) would need to be increased in accordance with the distance between the connection pipe (84) and the motor (50). In this embodiment, however, the connection pipe (84) provided on a side of the motor (50) is a resin pipe made of a resin material. Accordingly, it is possible to ensure insulation without distancing the connection pipe (84) from the motor (50). It is consequently possible to design the casing (15) to have a smaller diameter, and to downsize the scroll compressor.

The connection pipe (84) may he a metal pipe having only an outer circumferential surface coated with a resin material, instead of the pipe entirely made of a resin material as described above.

Note that the foregoing embodiments have been set forth merely for purposes of substantially preferred examples, and are not intended to limit the scope, applications, and use of the present disclosure.

INDUSTRIAL APPLICABILITY

As described above, the present disclosure is useful for the scroll compressors for compressing, e.g., a refrigerant.

DESCRIPTION OF REFERENCE CHARACTERS

10 Scroll compressor

15 Casing

18 Oil reservoir

20 Compression mechanism

30 Fixed scroll

35 Thrust sliding surface of fixed scroll

40 Orbiting scroll

41 End plate of orbiting scroll (End plate)

45 Thrust sliding surface

60 Driving shaft

70 Oil supply passage (Bearing oil supply passage)

75 Oil supply pump

80 Oil groove

85 Groove communication passage

87 Capillary tube (Throttle)

SCROLL COMPRESSOR

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Date Filed

Date Published

Inventors

CPC

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Abstract

Description

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Priority Claims (1)

PCT Information