Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
21580
4~463
The present invention relates to compressors used in
air conditioning units of vehicles and the like, such as
motor cars.
In compressors of such type any refrigerant gas
leaking around the peripheral surface of the reciprocating
pistons flows into the rotor chamber and causes the
pressure within the rotor chamber to increase. Conventionally
the leaked refrigerant gas in the rotor chamber is returned
to the suction side. Lubricating oil contained in a sump
withln the rotor chamber is stirred and atomized to lubricate
all portions of the bearings and lubricating oil flows to
the suction side together with the leaked refrigerant gas and
is returned again into the rotor chamber. A disadvantage
arises in that a large amount of lubricating oil is
introduced into the refrigerating machine during the exhaust
strokes and degrades the refrigerating capability while the
temperature within the rotor chamber gradually increases
and causes lowering of the lubricating capability.
Furthermore, as the pressure within the rotor chamber
increases due to the leaked refrigerant gas, it is difficult
to smoothly return the lubricating oil being introduced
into the suction side again to the rotor chamber, and thereby
a large amount of lubricating oil is contained at all times
in the refrigerating cycle, whereby the refrigerating
capability is considerably lowered.
An object of the present invention is to provide a
compressor for a refrigerant gas which avoids the above-noted
disadvantages.
-- 2--
~0484~i3
According to the invention, there is provided a
refrigerant gas compressor having a casing defining a rotor
acting on a rocker plate connected to reciprocate a piston
within a pumping cyl.inder, the rocker plate extending into
a lubricant sump within the rotor chamber, including a
gas and oil separator, a duct extending between said gas
and oil separator and the rotor chamber, a first passage
for returning gas separated by said separator to said
pumping cylinder, and a second passage receiving oil
separated by said separator and which is connected to supply
oil to relatively rotating members of the compressor.
The attached drawing shows one embodiment according to
the present invention, and therein;
Figure 1 is a longitudinal cross-section taken through
the compressor according to the invention, the piston being
in the position just before the starting of the suction
stroke;
Figure 2 is a sectional view taken in line 2-2 in
Figure 1 th~ugh the oil separating chamber;
Figure 3 is a section taken along line 3-3 in Figure 2;
and
Figure 4 is a section taken along line 4-4 in Figure 2.
Referring to the drawing, therein is shown a compressor
for a refrigerant unit comprising a casing 1 in which a
cylinder block 2 is fitted at one end thereof while a rotor
chamber 3 is formed at the other end thereof. A cylinder
head 4 is fixed to that end of the casing receiving the
cylinder block 2 and a valve seat 5 and valve plate 6 are
104t~463
clamped between the cylinder head 4 and the casing 1 and
block 2. The head 4 is formed with an exhaust chamber 7
at the periphery thereof and a suction chamber 8 centrally
thereof. An oil separating chamber 9 is fixed at the
exterior of the cylinder head 4 and is formed with an oil
reservoir 11 and baffle separators 10 and 10' thereabove.
A suction portion 12 for inlet of a refrigerant gas is formed
at the upper end of the oil separating chamber 9 and port 12
communicates with suction chamber 8 through a vent chamber 13
provided between cylinder head 4 and a vertical partitioning
element 13' integrally projecting from the exterior wall of
the cylinder head 4.
A cover body 14 is fixed to the other end of the
casing 1 and is provided with bearings 15 for a rotor
driving shaft 16. A rotor body 17 is fixed to the rotor
driving shaft 16 within the rotor chamber 3 and bears
against inclined rocking plate 20 at inclined surface 18
through bearings 19 to rock the inclined rocking plate by
the rotation of the rotor body 17. The inclined rocking
plate 20 is connected by means of connecting rods 21 and
universal joints 21' with pistons 23 slidably fitted in a
plurality of cylinder bores 22 in cylinder block 2.
A mechanical seal 24 is provided at that portion where
one end of the rotor shaft 16 passes through the cover body 14.
The other end of the rotor shaft 16 is supported by the
cylinder block 2 through bearing 25 and communicates with
oil reservoir 11. A male screw thread 26 is formed on the
external surface of rotor shaft 16 and a threaded bore 28 is
-- 4 --
1()48463
formed in shaft 16 for a purpose to be explained later.
A center screw 16' is secured to block 2 and loosely
engages in bore 28 also for a purpose to be explained
later.
An axial pressure plate 29 is mounted on rotor shaft 16
and acts to urge the rotor body 17 against bearings 34 on
cover body 14 to prevent axial movement of the rotor body 17.
The pressureplate 29 is axially biased by means of an
assembly disposed between plate 29 and cylinder block 2 and
comprising a seating plate 30, a plate spring 31 and thrust
plates 32, 33. The plate 29 applies pressure against the
inclined rocking plate 20 through plate spring 35, thrust
plate 36 and bushing 37.
Numeral 33 designates a suction nipple for the inlet of
refrigerant gas and numer~al~ 39 designates an oil sump
at the bottom of the rotor chamber 3. A trunnion block 40
is attached to the lower end of the inclined rocking plate 20
to ride in a track or slideway in casing 1 to prevent rotation
of the rocking plate 20.
The bushing 37 undergoes high speed rotation while
riding on rocking plate 20 while trunnion block 40 travels at
high speed on the fixed track or slideway in casing 1. In
order to make the bushing 37 and the trunnion block 40
lightweight with maximum wear characteristics, they are
made of aluminum alloy with 20% Si.
A duct 41 is formed in the cover body 14 and
communicates with bearing 15. The duct 41 opens at one end
into communicationwith the oil sump 39 and at the other end
~1)48463
thereof with a longitudinal bore 42 provided in the casing 1.
The bore 42 is in communication with suction port 12. A
throughhole 43 is formed in rotor shaft 16 and rotor body 17
to connect the bottom of female screw thread 28 and the
bushing 37. A communicating bore 44 is formed in the
cylinder block 2 to connect the rotor chamber 3 and the
upper portion of the oil reservoir 11 ~gs. 2 and 3).
The operation of the compressor is as follows:
When the rotor driving shaft 16 is driven from an
external drive source (not shown) the rocking plate 20 is
rocked by the rotor body 17 to cause reciprocation of the
pistons 23 through the universal joints 21' and connecting
rods 21. The refrigerant gas is caused to flow into the
suction chamber 8 from the suction nipple 38 through the
suction port 12 and the vent chamber 13 during the suction
strokes of the pistons 23, and then the refrigerant gas
flows into the cylinder bores 22 via suction ports 50 by
opening of suction valves 51. The refrigerant gas is
discharged into the exhaust chamber 7 via exhaust ports 52
upon opening of exhaust valves 53 at the time of compression
movement of the pistons 23 in the exhaust stroke. Stops 54
secured in chamber 7 serve to limit the degree of displace-
ment of the exhaust valves. The construction of the valve
plate 5 with the integral suction and exhaust valves is
conventional. The discharged refrigerant gas is delivered
forcedly to a refrigerating machine (not shown) such as an
evaporator, condenser, or the like, from an exhaust
nipple 55.
~(~48463
In Figure 1 the piston is at its end of stroke
position of discharge just before starting its suction
stroke. Valves 51 and 53 are thus closed. When the
piston begins its suction stroke, valve 51 opens and
refrigerant gas is sucked in via inlet nipple 38.
Figure 4 shows the piston in the exhaust stroke and therein
suction valve 51 is closed against plate 6 and exhaust
valve 53 is displaced to its open position by the pressure
developed in cylinder 22.
Incperation, some of the refrigerant gas leaks into
the rotor chamber 3 through gaps between the pistons 23 and
the walls of the cylinder bores 22. The lubricating oil
within the oil sump 39 at the bottom of the rotor chamber 3
is agitated by means o the trunnion block 40 secured to the
lower end of the inclined rocking plate 20 to cause atomization
of the lubricant and the formation of atomized drops of
lubricant. The thus at~mized drops act to lubricate the
thrust plates 32, 33, the bearings 19, the bearings 34, the
thrust plate 36, the mechanical seal 24 etc. The atomized
lubricant also flows together with the leaked refrigerant
gas into the oil separating chamber 9 via the duct 41 and
the bore 42 by the suction action of the pistons 23 at the time
of retreat thereof in the suction stroke.
Also at the time of starting, the pressure within the
rotor chamber 3 tends to drop suddenly, causing a boiling
phenomenon in the lubricating oil, and the oil is atomized
and tends to flow into the refrigerating cycle of the
refrigerating machine.
~048463
However, by virtue of the construction according to
the invention, the oil mixed with the refrigerant gas is
separated from the gas by the separator baffle 10 due to
the arrangement whereby the oil is cooled to a low
temperature by the refrigerant gas and forms drops which fall
into the oil reservoir 11. It is to be noted that the incoming
refrigerant gas at port 12 mixes with the mixture of
lubricant and leaked gas coming from bore 42 and after
separation by bafflé separator 10, the refrigerant gas flows
in one passage i.e. vent chamber 13 to the suction chamber 8
for inlet into the cylinder bores 22 whereas the lubricant
cooled by the incoming refrigerant gas and separated by
separator baffle 10 flows in a second passage to the
reservoir 11. The separated refrigerant gas and lubricant
in the two passages are in heat exchange relation via
partition 13'.
The lubricating oil within the oil reservoir 11 is
forcedly delivered into the rotor chamber 3 (for return to
sump 39) via bearing 25 by rotation of the male screw
thread 26 on the outer surface at the end of rotor driving
shaft 16 while the female screw thread 28 in the internal
peripheral surface of the central bore of the shaft 16
delivers the oil through the throughhole 43 and bearings 19
to chamber 3 for return to the oil sump 39. The female screw
head 28 is relatively less effective in oil delivery capacity
as compared to external male thread 26. Hence, the provision
of the fixed center screw 16 with its external male thread
supplements the forced delivery of oil from reservoir 11
through the bore in shaft 16 to the bushing 37 and bearings 19.
~048463
Furthermore, since the pressure in the rotor chamber 3
is relatively high as compared with that in the oil reservoir
11, the oil sometimes tends to flow reversely against the
oil delivering force produced by the male screw thread 26
and the female screw thread 28. To obviate this, the
communicating bore 44 in the cylinder block 2 establishes
equilibrium between the pressure in the rotor chamber 3
and that in the oil reservoir 11.
Instead of the male screw thread 26 or the female
screw thread 28, a positive oil delivering means could be
employed, such as a gear pump or the like to satisfy the
requirements of the invention, and with such oil delivery
means, there will be no need to provide communicating bore 44,
and the oil within the reservoir 11 may be delivered posi-
tively into the throughhole 43 through the central bore in
the driving shaft 16. It also becomes possible to carry out
lubrication by extending the central bore and connecting
the same to bearing 15.
As seen from the above, the present invention is
directed to a refrigeration compressor constructed such that
in the compressor carrying out compressing action by
reciprocating pistons through the rocking of the inclined
rocking plate, the lubricating oil within the rotor chamber
communicates at the suction side of the compressor with the
separator means and the oil reservoir. Furthermore, the end
of the rotor driving shaft communicates with said oil reservoir
and carrië~s oil delivery means so that lubricating oil within
said oil reservoir is delivered forcedly into the rotor
chamber so that lubricating oil which has flowed to the suction
1~4~463
side in admixture with leaked refrigerant gas is separated
by the separator means and flows into the oil reservoir.
Furthermore, the lubricating oil within the oil reservoir
is lowered in temperature and may be positively delivered
forcedly into the rotor chamber by oil delivering means to
prevent the lubricating oil from passing to the refrigeration
machine with the refrigerant gas. This prevents degradation
of the refrigerating capability. The lubricating oil flowing
to the suction side is cooled by means of the incoming
refrigerant gas and thereafter is returned back positively
to the oil sump within the rotor chamber from the oil
reservoir whereby the lubricating capability of the
lubricating oil may be increased considerably.
-- 10 --
