Compression type refrigerator

A compression type refrigerator has an evaporator, a condenser, a compressor for compressing a refrigerant gas, an oil tank for storing a lubricating oil, and an oil supply device connected to the oil tank for supplying the lubricating oil to the compressor by an oil pump. The discharge side of the oil pump is connected to the oil tank through an ejector. A pipe connected at one end to the evaporator to remove a refrigerant liquid, is connected at the other end to a negative pressure generation portion of the ejector.

BACKGROUND OF THE INVENTION 
The present invention relates to a compression type refrigerator, such as a 
turbo type refrigerator or a displacement type refrigerator. 
In a conventional compression type refrigerator having an evaporator, a 
condenser and a compressor, as disclosed in, for example, Japanese 
Unexamined Utility Model Publication No. 54-50240, a refrigerant liquid 
containing a large amount of lubricating oil is introduced into a vessel 
via a pipe connected to the evaporator to remove the refrigerant liquid 
therefrom. A coil is provided in the vessel, and a gas such as, for 
example, the refrigerant gas discharged from the compressor flows through 
the coil so that the heat of the gas is utilized to vaporize the 
refrigerant liquid contained in the vessel. The concentrated lubricating 
oil in the vessel is returned to the oil tank by operation of a valve. 
The above-described conventional compression type refrigerator is operated 
in manually performed batch processing, with a result that a continuous 
operation thereof requires troublesome operations, thus preventing 
reduction in human efforts because of required maintenance. 
SUMMARY OF THE INVENTION 
An object of the present invention is to provide a compression type 
refrigerator which enables a lubricating oil mixed in a refrigerant liquid 
to be automatically continuously collected. 
To achieve the above object, the present invention provides a compression 
type refrigerator comprising an evaporator, a condenser, a compressor for 
compressing a refrigerant gas, an oil tank for storing a lubricating oil, 
and an oil supply device connected to the oil tank and including an oil 
pump for supplying the lubricating oil to the compressor. A discharge side 
of the oil pump is connected to the oil tank through an ejector, and a 
pipe, connected at an end to the evaporator to remove a refrigerant 
liquid, is connected at the other end to a negative pressure generation 
portion of the ejector. 
The prevent invention further provides a compression type refrigerator 
including an evaporator, a condenser, a compressor for compressing a 
refrigerant gas, an oil tank for storing a lubricating oil, and an oil 
supply device connected to the oil tank, with the oil supply device 
including an oil pump for supplying the lubricating oil to the compressor. 
A first pipe for removing the compressed refrigerant gas is connected to 
the oil Lank through an ejector, and a second pipe, connected at one end 
to the evaporator to remove a refrigerant liquid, is connected to a 
negative pressure generation portion of the ejector. 
The above and other features, objects and advantages of the present 
invention will become more apparent from the following description of 
embodiments with reference to the accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
As shown in FIG. 1, a compression type refrigerator includes an evporator 
1, a condenser 2, a compressor 3 for compressing a refrigerant, a pipe 4 
for connecting the evaporator 1, the condenser 2 and the compressor 3 with 
each other to convey a refrigerant liquid or a refrigerant gas, and a 
throttling valve 5 provided in the pipe 4 between the evaporator 1 and the 
condenser 2. The compressor includes an impeller 6, a driving machine 7, a 
gear train 8 for transmitting a driving force of the driving machine 7 to 
the impeller 6, an oil tank 9 for storing a lubricating oil, and a pipe 10 
for connecting a suction side of the impeller 6 to a rear side of the 
impeller adjacent the oil tank 9 to balance the pressure between the 
suction side and the rear side of the impeller. The compressor 3 is 
further provided with an oil supply device 11 which includes an oil pump 
12, an oil cooler 13, an oil strainer 14, and a pipe 15 for connecting the 
oil pump 12, the oil cooler 13 and the oil strainer 14 to each other to 
supply the lubricating oil from the oil tank 9 to a portion where 
lubrication is required, such as the gear train 8 and bearings (not 
shown). A pipe 16 branches off the pipe 15 of the oil supply device 11 at 
a discharge side of the oil pump 12 (in the embodiment, at the outlet side 
of the oil strainer 14) and is connected to the oil tank 9 via an ejector 
17. A pipe 21 extends between a portion of the evaporator 1 near a level 
of the refrigerant liquid when the evaporator 1 is filled with the 
refrigerant liquid and a negative pressure generating portion of the 
ejector 17 so as to allow the refrigerant liquid to be removed from the 
evaporator 1 via a filter drier 19 and a check valve 20. 
When the driving machine 7 begins to drive the refrigerator, the 
refrigerant gas in the evaporator 1 is suctioned by the impeller 6. The 
gas compressed by the impeller 6 is introduced into the condenser 2 and is 
liquified thereby. The refrigerant liquid is cooled as it passes through 
the throttling valve 5. The cooled refrigerant liquid enters the 
evaporator 1, where it extracts heat from cooling water which flows 
through a pipe, to thereby vaporize. The refrigerant vapor is again 
suctioned by the impeller 6, thus completing one cooling cycle. 
Thereafter, this cooling cycle is repeated. The filter drier 14 prevents 
the water content or dust in the refrigerant liquid from flowing into the 
oil tank 9. The check valve 20 prevents flow of the lubricating oil into 
the pipe 21, which would occur due to the clogging of the ejector 17. 
In the oil supply device 11, the oil pump 12 circulates the lubricating oil 
from the oil tank 9 to the gear train 8, the bearings and so on and back 
into the oil tank 9 and repeats the circulation. 
Further, the part of the refrigerant liquid which stays near the level 
thereof in the evaporator 1 contains a large amount of lubricating oil 
having a smaller specific gravity. This part of the refrigerant liquid is 
suctioned into the pipe 21 by the effects of the ejector 17. After the 
refrigerant liquid is mixed with the lubricating oil in the ejector 17, 
the mixture is returned to the oil tank 9. Consequently, even if mist of 
the lubricating oil flows through the pipe 10 into the suction side of the 
impeller 6 together with the refrigerant vapor, the amount of lubricating 
oil in the oil tank 9 remains the same. 
To avoid excessive supply of the refrigerant liquid from the evaporator 1 
to the oil tank 9, the diameter of the port of the ejector 17 is set to an 
adequate value. In this manner, the oil in the oil tank 9 can be kept at 
an adequate level. 
According to the embodiment of FIG. 1 it is possible to automatically and 
continuously collect the lubricating oil mixed in the refrigerant liquid. 
FIG. 2 shows another embodiment which employs a high-pressure refrigerant 
gas discharged from the impeller 6 in place of the lubricating oil 
pressurized by the pump 12. 
A pipe 22 branches off the pipe 4 between the discharge side of the 
impeller 6 and the condenser 2. The pipe 22 is connected to the oil tank 9 
via a pressure-reducing valve 23 and the ejector 17. The pipe 21, 
connected to a portion of the evaporator 1 near the level of the 
lubricating oil contained in the evaporator 1, is connected to the 
negative pressure generating portion of the ejector 17 to return the 
refrigerant liquid containing a large amount of lubricating oil, located 
near the level of the refrigerant liquid in the evaporator 1, to the oil 
tank 9. The pressure-reducing valve 23 prevents the occurrence of the 
pressure loss which would occur by bypassing the refrigerant gas at an 
unduly high rate but assures a minimum amount of pressure required to 
activate the ejector 17. 
According to the embodiment of FIG. 2 it is possible to reduce the capacity 
of the oil pump from that required in the embodiment shown in FIG. 1. 
It is possible according to the present invention to automatically and 
continuously collect the lubricating oil mixed in the refrigerant liquid.