Note: Descriptions are shown in the official language in which they were submitted.
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This invention concerns a four-stage gas compressor, i.e. a machine
which compresses gaseous substances such as air, nitrogen or methane and raises
them from atmospheric pressure (or from any other pressure whether higher or
lower) to a much higher pressure through said machine's four compression
stages.
The prior art includes four-stage compressors operated by electric
motors or internal combustion engines through crank mechanisms with heavy and
cumbersome flywheels to prevent angular speed oscillations. Said prior art
also includes one and two stage linear compressors hydraulically operated from
the inside of the compressor itself: the two-stage compressors consist of two
one-stage linear compressors interconnected with each other.
An object of the present invention is the provision of a relatively
compact, single assembly machine which is both four-stage and hydraulically
operated.
The present invention provides a four-stage gas compressor including:
a double-acting piston operable by pressurised oil and provided with first and
second hollow opposed piston rods the first of which is connected to a first-
stage piston and the second of which is connected to a second-stage piston;
said first- and second-stage pistons being arranged to slide in first and
second jackets respectively; said first and second hollow piston rods being
coupled with a sliding fit to first and second cylindrical bodies acting as
fixed pistons of the third and fourth stage respectively; said first and
second cylindrical bodies being fixed to first and second opposed heads; said
first cylindrical body being axially provided with a first suction and delivery
duct; said second cylindrical body being axially provided with a second suction
and delivery duct; a third stage chamber being defined between said first
cylindrical body and one face of said double-acting piston; said first suction
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and delivery duct leading into said third stage chamber; a fourth stage
chamber being defined between said second cylindrical body and the other face
of said double-acting piston; said second suction and delivery duct leading
into said fourth stage chamber.
The invention described herein employs a single mobile element,
axially equipped with a double-action hydraulic engine piston, and, in addi-
tion, with two pistons for the first and second gas-compression stages, with
the gas-compression chambers for the third and fourth stages situated inside
the rods of these two pistons, and with the compression itself occurring by
means of these same rods. The machine itself has an aligned, coaxial overall
design.
The advantages of such a machine are: simplicity and compactness and
reduced overall radial and longitudinal dimensions, despite the existence of
four stages in a single unit.
By way of example only, a preferred embodiment of the present invention
is described in detail with reference to the accompanying drawing, which shows
a schematic longitudinal sectional view through a compressor in accordance
with the present invention.
Referring to the drawing, a head disc 1 is connected to an intermediate
head disc 2 by means of a 3ac~et 3 equipped with a liquid or air cooling sys-
tem and centred and fixed to the head disc 1 by screws 4. A cylindrical body
5 acts as a
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fixed third stage piston, and is equipped with a head 6
connecting it to the outside of the head di~c ~ by means of
screws 7. A cylindrical tubular element 8 coupled with a
sliding fit to the body 5 forms the rod of a piston 9, which
is fixed to the tubular element 8, to compress the gas in the
first stage. A bush 10 is fixed to the intermediate disc 2
by screws 11 and it is internally coupled to the external
surface of the tubular element 8 and acts as an oil seal. An
end face 12 of the cylindrical body 5 compresses the gas in
its third stage.
A double-action piston 13 is internally screwed to the
end of the tubular element 8 on the side opposite to the
piston 9; this piston 13 creates the alternating motion
deriving from the action of the oil contained in the chambers
14 and 15, said oil being pressurised by a hydr~ulic power
unit. A jacket 16 surrounds the hydraulic element in which
the piston 13 slides and, on one side, it is centred in an
annular projection 17 of the disc 2; on the other side, it
it centred in an annular projection 18 of ~n intermediate
head 19. A cooling jacket 21, equipped with liquid or air
cooling system, is centred in the annular projection of the
head 19, opposite to the projection 18, and in a head disc
22, and houses the second compression stage~
The assembly consisting of the jacket 16, the head 19,
the jacket 21 and the head 22 is all axially joined to the
disc 2 by tie rods 23. A cylindrical tubular element 24,
analogous and opposite to the cylindrical body 5, acts as
the fixed piston of the fourth stage and has a head 25 for
connection to the disc 22 by means of scre~Js 26. A cylindrical
tubular element 27 is coupled with a sliding fit to the body
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24 and constitutes the rod of a piston 28 o~ the second
compression stageO A bush 29, analogous to the bush 10, is
fixed to the disc 19 by means of screws 30 and is internally
coupled to the exterior surface of the tubular element 27,
to act also as an oil seal. An interior end face 31 of the
cylindrical body 24, analogous and opposite to the face 12,
compresses the gas in the fourth stage. A reduced diameter
threaded end 32 of the piston 13, opposite to the end to which
the cylindrical element 8 is screwed, is screwed to the end
of the cylindrical tubular element 27, opposite to the end
screwed to the piston 28.
A first-stage suction valve 33 connects the tank of gas
to be compressed (not shown) to a chamber 34. A first-stage
delivery valve 35 connects the chamber 34 to a second_stage
chamber 36, via a cooling coil 37, through a suction valve
38. A second-stage delivery valve 39 connects the chamber
36 to a thir~-stage chamber 40, via a cooling coil 41, through
a suction valve 42 and an axial suction delivery duct 43.
located in the bod~ 5. A third stage delivery valve 44
connects the chamber 40 to a fourth-stage chamber 45, via
cooling coil 46, through a fourth-stage suction valve 47 and
an axial suction and delivery duct 48, located in the cylindrical
body 24. A delivery valve 49 connects the chamber 45, via
a cooling coil 51, to a user 50 which can be a tank.
~ he chamber 52, opposite to the first_stage chamber
34, has an outlet port 53 in the disc 2, which vents into
the atmosphere any leakage of gas, and an outlet port 54 to
discharge any leakage of oil from the bush 10. A chamber 55
is opposite to the second-stage chamber 36 and has an outlet
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port 56 in the head 19, to vent into the atmosphere any
leaka~e Or gas, and a port 57 to discharge an~ leakage of
oil from the bush 29~ Gas seals 5~ are secured to the
piston 28 and oil seals 59 are inserted into the piston 13.
The piston 9 is provided with a locking nut 60 to be used
if the piston has to be screwed to the tubular element 8.
A locking nut 61, analogous to the locking nut 60, fixes
the piston 28 to the tubular element 27. The numbers 62
and 63 indicate the oil inlet and drain ports of the chambers 14 and 15 respectively.
The compressor operates as follows: once the oil i6
delivered under pressure to the chamber 14, the piston 13
moves, lowering the volume of the chamber 15, pulling the
first-stage piston 9 and pushing the second-stage piston 28.
The movement of the piston 9 increases the volume of the
chamber 34 and causes gas to be compressed to be sucked
into it th~gh the valve 33. ~he movement of the piston
28 reduces the volume of the chamber 36 and causes the
, compression necessary to feed the third-stage chamber 40,
through the valves 39 and 42. At the same time, the volu~e
of the fourth_stage chamber 45 is reduced, causing the gas
. to be compressed to pass through the valve 49 and into the
user.
If, on the contrary, the oil is delivered under pressure
to the chamber 15, the volume of the chamber 14 is reduced,
pushing the first-stage piston 9 and pulling the second
. stage piston 28~ ~he movement of the piston 9 reduces the
volume of the chamber 34, compressing the gas therein which
. . then is fed into the second-stage chamber 36 through the
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valves 35 and 38. Likewise, the volume of the third_star~e
chamber 40 is reduced, compressing the gas therein which then
is fed into the fourth stage chamber 45 through the valves
44 and 47~ '~his sequence is repeated in the following cycles.
It will be appreciated that the compression ratios of
the above compressor stages may be varied if necessary:-
for example, each stage may have a compression ratio of 1:~,
resulting in an overall compression ratio of 44=256.
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