Compressor

In a compressor in which a compression mechanism incorporated in a housing is driven by a drive shaft penetrating the housing, and the compression mechanism is lubricated by mist-form lubricating oil contained in a low-pressure gas refrigerant sucked into the housing, the lubricating oil in a space is prevented from entering a bearing and deteriorating grease in the bearing. An equalizing hole is formed to allow the space to communicate with the atmosphere, the space being defined between the bearing pivotally supporting the outer end of the drive shaft on the housing and a shaft seal disposed on the inside of the bearing to seal a gap between the drive shaft and the housing.

FIELD OF THE INVENTION AND RELATED ART STATEMENT 
The present invention relates to a compressor mounted in an air conditioner 
and other machines. 
One example of a scroll type compressor is shown in FIG. 2. 
A housing 1 of the scroll type compressor consists of a cup-shaped body 2 
and a front housing 6 fastened thereto with bolts (not shown). 
A drive shaft 7 penetrates the front housing 6 in a substantially 
horizontal direction, and an inner-end large-diameter portion 7a is 
pivotally supported via a main bearing 9, and an outer-end small-diameter 
portion 7b is pivotally supported via a bearing 8. 
A gap between the drive shaft 7 and the front housing 6 is sealed by a 
shaft seal 35 on the inside of the bearing 8. 
The housing 1 incorporates a scroll type compression mechanism C consisting 
of a fixed scroll 10, an orbiting scroll 14, and other elements. 
The fixed scroll 10 is provided with an end plate 11 and a spiral wrap 12 
erected on the inside surface of the end plate 11, and the end plate 11 is 
fastened to the cup-shaped body 2 with bolts 13. 
The interior of the housing 1 is partitioned by bringing the outer 
peripheral surface of the end plate 11 into contact with the inner 
peripheral surface of the cup-shaped body 2. A discharge cavity 31 is 
defined on the outside of the end plate 11, and a suction chamber 28 is 
defined on the inside of the end plate 11. 
Also, a discharge port 29 is formed in the center of the end plate 11, and 
the discharge port 29 is opened and closed by a discharge valve 30. 
The lift of the discharge valve 30 is restricted by a valve guard 32, and 
the base end of the discharge valve 30 and the valve guard 32 is fastened 
to the end plate 11 with a bolt 33. 
The orbiting scroll 14 is provided with an end plate 15 and a spiral wrap 
16 erected on the inside surface of the end plate 15, and the spiral wrap 
16 has substantially the same shape as that of the spiral wrap 12 of the 
fixed scroll 10. 
The orbiting scroll 14 and the fixed scroll 10 are off-centered by a 
predetermined distance, and engaged with each other with the phase being 
shifted 180 degrees as shown in FIG. 2. 
A tip seal 17 is embedded in the tip end face of the spiral wrap 12, and a 
tip seal 18 is embedded in the tip end face of the spiral wrap 16. The tip 
seals 17 come into contact with the inside surface of the end plate 15, 
the tip seals 18 come into contact with the inside surface of the end 
plate 11, and the side surfaces of the spiral wraps 12 and 16 touch each 
other linearly, by which a plurality of compression chambers 19a, 19b are 
formed so as to be in substantially point symmetry with respect to the 
center of the spiral. 
A cylindrical boss 20 projects at the center of the outside surface of the 
end plate 15, and a drive bush 21 is rotatably fitted in the boss 20 via 
an orbiting bearing 23. The drive bush 21 is formed with slide grooves 24, 
and an eccentric drive pin 25, projecting eccentrically at the inner end 
of the drive shaft 7, is slidably fitted in the slide grooves 24. 
A thrust bearing 36 and an Oldham's link 26 are interposed between the 
outer peripheral edge of outside surface of the end plate 15 and the inner 
end surface of the front housing 6. 
To correct the dynamic imbalance caused by the orbital motion of the 
orbiting scroll 14, a balance weight 27 is fixed to the drive bush 21, and 
a balance weight 37 is fixed to the drive shaft 7. 
Thus, when the drive shaft 7 is rotated, the orbiting scroll 14 is driven 
via an orbiting drive mechanism consisting of the eccentric drive pin 25, 
slide grooves 24, drive bush 21, orbiting bearing 23, boss 20, and the 
like. The orbiting scroll 14 performs orbital motion along a circular 
orbit with an orbiting radius while the rotation thereof is checked by the 
Oldham's link 26. 
Then, the linearly touching portion of the side surfaces of the spiral 
wraps 12 and 16 moves gradually toward the center of the spiral. As a 
result, the compression chambers 19a, 19b move toward the center of the 
spiral while decreasing the volume thereof. 
Accordingly, a low-pressure gas refrigerant sucked into the suction chamber 
28 through a suction passage 37 is introduced into the compression 
chambers 19a, 19b through an opening defined by the outer end of the 
spiral wraps 12 and 16, reaching a central chamber 22 while being 
compressed. From here, the refrigerant, passing through the discharge port 
29, is discharged into the discharge cavity 31 by pushing to open the 
discharge valve 30, and flows out from this cavity through a not 
illustrated discharge port. 
Mist-form lubricating oil contained in the low-pressure gas refrigerant 
sucked into the suction chamber 28 lubricates the compression mechanism C, 
main bearing 9, shaft seal 35, drive bush 21, orbiting bearing 23, 
Oldham's link 26, thrust bearing 36, and other elements. 
When the above-mentioned compressor is being operated, the low-pressure gas 
refrigerant sucked into the suction chamber 28 and the mist-form 
lubricating oil contained therein pass through a seal gap of the shaft 
seal 35 and enter a space 38. 
When the compressor is stopped, the gas refrigerant is liquefied in the 
space 38, and accumulates as a liquid refrigerant. 
When the operation of compressor is restarted, the liquid refrigerant in 
the space 38 is evaporated by the temperature rise of the bearing 8. Then, 
the pressure in the space 38 is increased, and the lubricating oil in the 
space 38 intrudes into the bearing 8, so that there arises a problem in 
that grease in the bearing 8 is diluted and deteriorated by the 
lubricating oil in the space 38. 
OBJECT AND SUMMARY OF THE INVENTION 
The present invention was made to solve the above problem. Accordingly, the 
present invention provides a compressor in which a compression mechanism 
incorporated in a housing is driven by a drive shaft penetrating the 
housing, and the compression mechanism is lubricated by mist-form 
lubricating oil contained in a low-pressure gas refrigerant sucked into 
the housing, characterized in that an equalizing hole is formed to allow a 
space to communicate with the atmosphere, the space being defined between 
a bearing pivotally supporting the outer end of the drive shaft on the 
housing and a shaft seal disposed on the inside of the bearing to seal a 
gap between the drive shaft and the housing. 
Also, the present invention is characterized in that the equalizing hole is 
open at the upper part of the space. 
In the present invention, the equalizing hole is formed to allow the space 
to communicate with the atmosphere, the space being defined between the 
bearing pivotally supporting the outer end of the drive shaft on the 
housing and the shaft seal disposed on the inside of the bearing to seal 
the gap between the drive shaft and the housing, so that the pressure in 
this space can be prevented from increasing. Therefore, the lubricating 
oil in this space can be prevented from entering the bearing, so that 
grease in the bearing can be prevented from being diluted and deteriorated 
by the lubricating oil. 
Also, if the equalizing hole is open at the upper part of the space, a 
liquid refrigerant and lubricating oil in the space can be prevented from 
overflowing through the equalizing hole.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
FIG. 1 shows a compressor in accordance with an embodiment of the present 
invention. 
The space 38 is defined between the bearing 8, which pivotally supports the 
outer-end small-diameter portion 7b of the drive shaft 7, and the shaft 
seal 35 disposed on the inside of the bearing 8, and an equalizing hole 40 
for allowing the upper part of the space 38 to communicate with the 
atmosphere is formed vertically so as to penetrate the front housing 6. 
Other configurations are the same as the conventional ones shown in FIG. 2. 
Therefore, the same reference numerals are applied to the corresponding 
elements, and the explanation thereof is omitted. 
In this embodiment, when the compressor is being operated, the low-pressure 
gas refrigerant sucked into the suction chamber 28 and the mist-form 
lubricating oil contained therein pass through the seal gap of the shaft 
seal 35 and enter the space 38. 
When the compressor is stopped, the gas refrigerant is liquefied in the 
space 38, and accumulates as a liquid refrigerant together with the 
lubricating oil. In this embodiment, since the equalizing hole 40 is open 
at the upper part of the space 38, the liquid refrigerant and lubricating 
oil do not overflow to the outside through the equalizing hole 40. 
When the operation of compressor is restarted, the liquid refrigerant in 
the space 38 is evaporated by the temperature rise of the bearing 8. 
However, since the refrigerant vapor is discharged to the atmosphere 
through the equalizing hole 40, the pressure in the space 38 does not 
increase. Therefore, according to the compressor of this embodiment, the 
lubricating oil in the space 38 can be prevented from entering the bearing 
8. 
Although an example in which the present invention is applied to a scroll 
type compressor has been described in this embodiment, it is a matter of 
course that the present invention can be applied to a compressor 
incorporating any type of compression mechanism in the housing thereof, 
not limited to the scroll type compressor.