Compressor system having an oil separator

In a compressor system, a compressor main unit compresses air taken in and exhausts the compressed air with oil. The compressed air and the oil exhausted from the compressor main unit are stored in a reservoir. A head tank has an internal space and is coupled to the compressed main unit and the reservoir. An oil separator which is installed in the head tank separates the oil exhausted from the head tank from the compressed air.

BACKGROUND OF THE INVENTION 
The present invention relates to a compressor system, and more 
particularly, to a compressor system having an improved structure so that 
noise and vibrations are reduced and miniaturization is easily achieved. 
A type of compressor which increases the pressure of a gas and exhausts the 
compressed gas is a rotor-type compressor. The rotor-type compressor has a 
pair of rotors, female and male which are respectively installed on two 
axes in parallel and rotate interlockingly. While rotating, the female and 
male rotors take in, compress and exhaust gas. In doing so, oil is 
supplied to reduce abrasion and heating occurring due to friction between 
the rotating female and male rotors. 
FIG. 1 schematically shows a conventional rotor-type compressor system. 
Reference numeral 27 indicates a housing for accommodating elements of the 
compressor system in which a grilled air passage 28 is formed at one side 
surface. Reference numeral 3 indicates a compressor main unit in which a 
pair of rotors 3a for compressing air taken in through an air cleaner 4 
are installed. The rotors 3a are rotated by a driving motor 1, and the air 
compressed by the rotor 3a is supplied to an accumulator 5 via an exhaust 
pipe 3b. The accumulator 5 is usually fabricated by molding or welding 
several metal plates. A cooling oil is supplied to the rotor 3a through a 
first oil supply pipe 21 to reduce abrasion and heating due to the pair of 
rotors 3a which rotate while interlocking with each other, and thermal 
expansion of the rotor 3a due to the heat. 
An oil separator 7 is installed inside the accumulator 5 and separates oil 
6a included in the compressed air which is supplied through the exhaust 
pipe 3b. That is, a portion of the oil which is splashed together with the 
compressed air to the accumulator 5 precipitates down and then is stored 
in the accumulator 5, and the remaining portion of the oil sticks to the 
oil separator 7. The oil stuck to the oil separator 7 is supplied to a 
bearing (not shown) installed on the axis of the rotor 3a via an auxiliary 
oil line 25. 
The compressed air passed through the oil separator 7 is supplied to a 
desired location via a pressure valve 8, an air pipe 11, an air cooler 10 
and a service pipe 12. The pressure valve 8 being operated by a pressure 
switch 17 opens when the pressure in the accumulator 5 is beyond a preset 
value. 
The oil 6a which is exhausted from the accumulator 5 through a first oil 
transmission pipe 23 is selectively supplied by a temperature regulator 15 
to the first oil supply pipe 21 and a second oil transmission pipe 24. 
That is, during the initial operation of the compressor, when the 
temperature of the oil 6a is relatively low, the oil is transferred 
through the first oil supply pipe 21 and supplied to the rotor 3a. When 
the temperature of the oil 6a is relatively high, the oil is supplied to 
the oil cooler 20 through the second oil transmission pipe 24. The oil 
supplied to the oil cooler 20 is cooled and then supplied to the 
temperature regulator 15 through a second oil supply pipe 22. The oil 
passes through an oil filter 16 and flows into the first oil supply pipe 
21 by the operation of the temperature regulator 15. 
The above conventional compressor system has the following problems. 
First, since the compressor main unit 3, the temperature regulator 15 and 
the oil filter 16 are connected to the accumulator 5 by the exhaust pipe 
3b and the first oil transmission pipe 23, the compressor system is 
complicated and the size is large. Thus, loss of pressure in the pipes 
increases, the system becomes susceptible to vibrations, and a great 
amount of oil is required. 
Second, since the accumulator 5 is usually fabricated by molding or welding 
several metal plates, the production thereof is slow. 
Third, since the output of the exhaust pipe 3b is installed at a place 
adjacent to the inlet of the oil separator 7, most of the oil included in 
the compressed air splashed to the accumulator 5 does not precipitate but 
passes through the oil separator together with the compressed air. Thus, 
the efficiency of oil separation is lowered and also the life span thereof 
is shortened. 
SUMMARY OF THE INVENTION 
To overcome the above problems, it is an objective of the present invention 
to provide a compressor system which has simplified structure and which is 
capable of being miniaturized. 
It is another objective of the present invention to provide a compressor 
system in which the performance of an oil separator is improved. 
Accordingly, to achieve the above objectives, there is provided a 
compressor system comprising: a compressor main unit for compressing air 
which is taken in and exhausting the compressed gas with oil; a reservoir 
in which the compressed air and the oil exhausted from the compressor main 
unit are stored; a head tank having an internal space and being interposed 
between and coupled to the compressed main unit and the reservoir so that 
the internal space of the head tank is opened to the compressor main unit 
and the reservoir; and an oil separator, installed in the head tank, for 
separating the oil exhausted from the head tank from the compressed air. 
In the above compressor system, a first opening to which the compressor 
main unit is coupled is formed at one side of the head tank and a second 
opening to which the reservoir is coupled is formed at the other side 
thereof. 
The compressor system further comprises an exhaust pipe, installed in the 
compressor main unit to extend via the head tank and to the inside of the 
reservoir, for guiding the compressed air and the oil exhausted from the 
compressor main unit, in which an outlet end portion of the exhaust pipe 
is bent upward. 
Preferably, the outlet portion of the exhaust pipe is spiral and the end 
portion of the outlet portion is bent upward. 
It is preferable in the present invention that the compressor main unit of 
a compressor system comprise a rotor casing having an intake chamber into 
which air is taken and female and male rotors interlockingly rotating is 
accommodated; and an exhaust casing coupled to the rotor casing and having 
an exhaust chamber into which the compressed air flows from the rotor 
casing, in which the exhaust pipe is installed in the exhaust casing. 
Also, the compressor main unit of the compressor system further comprises a 
rotor flange which is installed between the rotor casing and the exhaust 
casing and is coupled to a flange formed around the first opening of the 
head tank. 
According to another embodiment of the present invention, a compressor 
system is provided, in which the compressor main unit comprises: a rotor 
casing having an intake chamber into which air is taken and female and 
male rotors interlockingly rotating is accommodated; and an exhaust casing 
coupled to the rotor casing and having an exhaust chamber into which the 
compressed air flows from the rotor casing, in which the rotor casing is 
integrally formed with the head tank. 
According to yet another embodiment of the present invention, a compressor 
system is provided in which a first opening coupled to the compressor main 
unit and a second opening coupled to the reservoir are separately formed 
at the same side of the head tank. 
Thus, in the compressor system according to the present invention, since 
various elements such as the compressor main unit, the oil filter, and the 
oil separator are installed together in the head tank, miniaturization of 
the system is facilitated. Furthermore, manufacturing costs decrease, and 
vibrations and loss of pressure are minimized by reducing the lengths of 
the compressed air line and the oil line.

DETAILED DESCRIPTION OF THE INVENTION 
In FIG. 2, reference numeral 30 indicates a compressor main unit which 
includes a rotor casing 31 and an exhaust casing 32 which is combined with 
the rotor casing 31. 
In the rotor casing 31, a pair of female and male rotors (not shown) are 
installed on two parallel shafts 31a and 31b to rotate while being engaged 
with each other. Shafts axis 31b is driven while coupled to a driving 
motor 40 by a belt 41. An intake chamber (not shown) into which air is 
taken is formed in the rotor casing 31 and an exhaust chamber (not shown) 
from which air is exhausted is formed in the exhaust casing 32. Also, an 
air cleaner 35 which filters the air taken into the intake chamber is 
installed in the rotor casing 31. 
An accumulator 70 coupled to the compressor main unit 30 includes a 
reservoir 60 for accommodating compressed air and oil exhausted from the 
exhaust chamber and a head tank 50 having an inner space and coupled to 
the reservoir 60 and the compressor main unit 30. 
The reservoir 60 is formed of a metal plate by a pressing process, and a 
flange portion 61 having coupling holes spaced apart at predetermined 
intervals is formed at the edge of an inlet of the reservoir 60. 
The structure of the head tank 50 is shown in detail in FIGS. 4 through 6. 
Referring to the drawings, a flange portion 51 which is coupled to the 
flange portion 61 of the reservoir 60 (see FIG. 2) by bolts is formed on 
one side surface of the head tank 50. Also, a first opening 57 coupled to 
the compressor main unit 30 is formed on one side of the head tank 50 and 
a second opening 58 coupled to the reservoir 60 is formed on the other 
side thereof. 
A rotor flange 33 (see FIG. 2) is installed between the rotor casing 31 and 
the exhaust casing 32. The rotor flange 33 is coupled using bolts with a 
plate 56 formed around the first opening 57 of the head tank 50 so that 
the compressor main unit 30 is fixed to the head tank 50. Alternatively, 
without the plate 56, the rotor flange 33 can be directly coupled to the 
head tank 50 through screw holes (not shown) radially formed at 
predetermined intervals around the first opening 57. Also, the rotor 
casing 31 and the head tank 50 can be integrally formed by welding or 
molding, as shown in FIG. 7. 
A drain 52 for expelling sediment in the reservoir 60 is formed at the 
bottom portion of the head tank 50. An oil gauge 130 which indicates the 
amount of oil in the reservoir 60 is installed at the flank surface of the 
head tank 50. The oil gauge 130 includes a translucent tube connected to 
the head tank 50 at the upper and lower portions thereof to communicate 
with the inside of the head tank 50. 
In FIG. 3, the structural elements of the compressor system are shown with 
emphasis on the function and arrangement of the elements with respect to 
the path of air and oil. For instance, it can be seen from FIG. 2 that the 
oil filter 80 is actually coupled to the head tank 50. 
As shown in the drawing, the compressor system according to the present 
invention includes an air cooler 110 and an oil cooler 120 for 
respectively cooling compressed air and oil which are exhausted from the 
accumulator 70. On the head tank 50, an oil separator 90, the oil filter 
80 and a regulator 100 are installed. The oil separator 90 is for 
separating the oil included in the compressed air in the reservoir 60. The 
oil filter 80 is for filtering the oil exhausted from the reservoir 60 and 
the oil passing through the oil cooler 120. The regulator 100 is for 
controlling the selective transfer of the oil exhausted from the reservoir 
60 to the oil filter 80 or the oil cooler 120 according to the temperature 
of the oil. The oil filter 80, oil separator 90 and regulator 100 are 
installed at coupling portions 53, 54 and 55, respectively, (see FIGS. 4 
and 5) of the head tank 50. 
Also, a pressure valve 91 is installed in the oil separator 90 which opens 
when the compressed air in the reservoir 60 is beyond a preset pressure. 
A cooling unit which cools the air cooler 110 and the oil cooler 120 is 
comprised of a fan 140 rotated by the driving motor 40 and a duct 135 
which guides the flow of air generated by the fan 140. 
An exhaust pipe 36 for guiding the exhausted compressed air and oil is 
coupled to the exhaust casing 32 and the outlet end portion of the exhaust 
pipe 36 is bent upward. Further, as shown in FIG. 2 and FIG. 7, the outlet 
portion of the exhaust pipe may have a spiral shape like a pig's tail. The 
compressed air discharged from the exhaust pipe 36 is supplied to the oil 
separator 90 installed in the head tank 50 through the reservoir 60. Thus, 
the oil included in the compressed air can be effectively separated. 
The operation of the compressor system according to an embodiment of the 
present invention structured as above will now be described with reference 
to FIGS. 2 and 3. 
When the female and male rotors (not shown) installed on the two axes 31a 
and 31b in the rotor casing 31 are rotated by the driving motor 40, the 
air taken in through the air filter 35 is compressed and exhausted to the 
reservoir 60. Also, the fan 140 is rotated by the driving motor 40 to cool 
the air cooler 110 and the oil cooler 120. 
In the rotor casing 31, oil is supplied through the main oil supply pipe 
104 and the auxiliary oil supply pipe 95 to prevent abrasion and heating 
due to the rotation of the rotors. Thus, the oil splashes when the air 
compressed by the rotation of the rotors is exhausted through the exhaust 
pipe 36 and a portion of the splashed oil precipitates inside the 
reservoir 60. Here, the compressor main unit 30 is directly coupled to the 
head tank 50 without additional piping so that loss of pressure of the 
compressed air due to friction while passing through the additional piping 
is minimized. 
The compressed air and the splashed oil in the reservoir 60 pass through 
the oil separator 90. At this time, oil is supplied to the rotor casing 31 
through the auxiliary oil supply pipe 95 after being filtered, and the 
compressed air is transferred to the air cooler 110 through an air pipe 93 
to be cooled and then is exhausted through a service pipe 94. 
During the initial operation of the compressor, when the oil in the 
reservoir 60 is below the set temperature, the oil is transferred through 
a first oil supply pipe 101 by the operation of the temperature regulator 
100. When the temperature of the oil is beyond the set temperature during 
operation of the compressor, the oil passes through the first oil supply 
pipe 102 and the oil cooler 120 to be transferred to the oil filter 80. 
In FIG. 8, major elements of a compressor system according to another 
embodiment of the present invention is schematically illustrated. Here, 
the same reference numerals represent the same elements in this drawing 
and the previous drawings. According to a characteristic feature of this 
embodiment of the present invention, a first opening 57' and a second 
opening 58' to which the compressor main unit 30 and the reservoir 60 are 
coupled respectively are formed together at one side of a head tank 50'. 
That is, since both the compressor main unit 30 and the reservoir 60 are 
coupled to the head tank 50' at one side thereof, the compressor system 
can be made compact. 
The coupling of the compressor main unit 30 and the head tank 50' and the 
reservoir 60 and the head tank 50' are performed by the same method as 
described in the previous embodiment. However, due to a limitation in the 
work space to couple the exhaust pipe 36 to the exhaust casing 32, the 
rotor casing 31 and the head tank 50' cannot be fabricated in one body. 
As shown in FIG. 9, a partitioning member 50a is preferably installed 
inside the head tank 50' to separate the exhaust pipe 36 and an entrance 
90a of the oil separator 90 (see FIG. 8). In this case, the compressed air 
and the splashed oil exhausted from the exhaust pipe 36 arrive at the oil 
separator 90 after passing through the reservoir 60 as indicated by the 
arrow in the drawing. Here, a portion of the splashed oil precipitates in 
the reservoir 60 and the remaining oil sticks to the oil separator 90. 
The compressor system according to the preferred embodiment of the present 
invention as described above has the following advantages. 
First, since the compressor main body, the oil filter, the oil separator, 
the temperature regulator are all installed in the head tank, loss in the 
pipe can be reduced, leakage of compressed air and oil due to vibrations 
and impact can be prevented, and simultaneously the system itself can be 
miniaturized. 
Second, since the reservoir is formed of a metal plate by a pressing 
process, productivity can be improved. 
Third, since a portion of the splashed oil from the exhaust pipe 
precipitates and is stored in the reservoir and only the remaining oil 
reaches the oil separator, the efficiency of oil separation of the oil 
separator can be increased and the life span thereof can be extended. 
It is noted that the present invention is not limited to the preferred 
embodiment described above, and it is apparent that variations and 
modifications by those skilled in the art can be effected within the 
spirit and scope of the present invention defined in the appended claims. 
For instance, another sort of gas, instead of air, can be used for the 
above compressor.