Note: Descriptions are shown in the official language in which they were submitted.
12~1 07(1
HORIZONTAL SHAFT OIL PUMP
,
- This invention pertains to an oil pump,, and more
particularly to an oil pump for use in a horizontal
rotary compressor.
In some compressors, the crankshaft is vertically
disposed in the compressor housing and has its lower
end portion submerged in an oil sump. A helical
groove is provided in the crankshaft, and upon
rotation of the crankshaft by the motor, oil is
delivered upwardly through the groove along the
crankshaft for lubricating bearings and other moving
parts. Generally, some type of impeller means is
also provided at the lower end of the crankshaft to
assist in urging oil upwardly through the helical
groove.
In contrast to the above compressors wherein oil
is delivered upwardly by a helical groove in the
vertically mounted crankshaft, the crankshaft in a
horizontal piston or rotary compressor cannot directly
elevate the oil upwardly through a helical groove in
the crankshaft. This has posed numerous problems in
properly lubricating bearings and other moving parts
in a horizontally disposed compressor. The fact that
such horizontal compressors are presently in use
indicates that some means have been provided in the
prior art to deliver lubricant to a rotating horizontal
crankshaft, however, problems continue to exist in
adequately lubricating bearings and moving parts 7 as
well as an inability to adequately self-prime the oil
pump during start-up.
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One earlier method for delivering lubricant
upwardlv to a rotating horizontal crankshaft uses a
disc or plate attached to the crankshaft to rotate
- therewith and which has its lower portion disposed in
the oil sump. A circular groove is provided in the
f]at surfaces of the disc, and upon rotation of the
crankshaft, the disc rotates through the oil sump and
carries lubricant in the grooves upwardly to a cavity
or chamber adjacent the crankshaft. The lubricant is
1~ then delivered from the chamber by means of a series
of passages to the crankshaft for lubricating bearings.
Several drawbacks exist with this type of oil pump,
one of the drawbacks being the inability to delîver a
desired amount of lubricant to the crankshaft and
associated bearings. Other drawbacks include additional
expense in materials and labor in providing the
grooved disc and a chamber in the crankcase with oil
passages leading to the crankshaft and bearings.
Another type of oil pump for use with horizontal
motor-compressor units utilizes a wick device disposed
in the oil sump ~nd in contact along several axial
points of the crankshaft. The wick device delivers
oil upwardly from the oil sump and through the wick
to the crankshaft for further delivery along the
crankshaft and bearings. An obvious drawback with
this type of oiling device is that the wick may
shrink down away from the crankshaft during prolonged
use, thereby preventing proper lubrication of the
crankshaft and bearings. Moreover, small pieces of
the wick may eventually break off and clog oil
passages or lodge between moving parts preventing
proper movement.
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In yet another type of horizontal compressorl a
portion of the crankcase is submerged in the oil sump
and has a passageway leading from the oil sump
- upwardly to a chamber provided between an eccentric
reduced portion of the crankshaft and crankcase.
Rotation of the crankshaft causes oil to be drawn
upwardly through the crankcase passageway into the
chamber and through an axially extending passage in
the cr~nksha~t. One of the problems associated with
this particular type of oil pump is that the axiall~
extending passage in communication with the chamber
does not fully utilize the centrifugal force of the
rotating crankshaft to efficiently deliver desired
amounts of lubrication along the crankshaft for
lubricating bearings.
In still another type of oil pump system for a
rotating horizontal shaft, the center portion of the
shaft is enlarged and tapers radially inwardly toward
the remote ends. A pair of oppositely angularly
disposed helical grooves are provided on the respective
tapering surfaces of the enlarged center portion and
have their axially outermost ends in communication
with an oil supply. Upon rotation of the shaft and
helical grooves therein, oil is delivered axially
inwardly along the grooves to the center of the shaft
for lubrication thereof. One of the undesired
features with this type of oil pump is that the oil
supply is required to be disposed at the same height
as the ends of the rotating horizontal shaft. In
virtually all horizontal rotary compressors, the
crankshaft is disposed above the surface of the oil
sump in the compressor housing.
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In view of the above, it is quite clear
that a need still exists for an oil pump in a horizontal
motor compressor unit that efficiently delivers
- lubricant upwardly to the crankshaft and horizontally
along its length for proper lubrication of bearings
and other moving parts, and which has a selF-priming
feature.
The ~orizontal shaft oil pump of the present
invention eliminates the use of any type of disc or
plate or wicking device for delivering lubricant
upwar~ly to the crankshaft, and in place thereof
provides a generally vertically disposed passageway
in a portion of the crankcase disposed in the oil
sump, the passageway communicating with the oil sump
and leading upwardly to the crankshaft. A portion of
the crankshaft is reduced in diameter so as to form
between the crankshaft and the crankcase an annular
chamber in communication with the crankcase passage-
way. Upon rotation of the crankshaft, a low pressure
area is developed in the annular chamber to draw
lubricant from the oil sump upwardly throu~h the
crankcase passageway to the annular chamber.
The horizontal shaft oil pump of the present
invention overcomes the general inability of many of
the prior art oil pumps to efficiently supply a
requisite amount of lubricant along the horizontal
crankshaft for lubricating bearings and moving parts.
This inability is overcome by providing a pair of
oppositely oriented helical grooves on opposite sides
of the annular chamber and which form between the
crankshaft and crankcase a pair of oppositely
oriented helical passages in communication with and
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leading away from the annular chamber. The helical
passages are oppositely disposed to deliver oil in
opposite directions from the annular chamber. Upon
- rotation of the horizontal crankshaft, the low
pressure area created in the annular chamber draws
lubricant from the oil sump upwardly through the
crankcase passageway into the annular chamber.
Lubricant is then deli~ered by the respective helical
passages along the crankshaft for lubricating
bearings and other moving parts.
The dimensions of each helical groove are such
as to provide adequate oil flow for sufficient
lubrication of bearings and to enable self-priming of
the pump upon start-up.
In one form of the invention there i5 provided a
compressor comprising a housing having an inlet,
outlet, ana an oil sump in the hottom thereof. A
motor-compressor unit is mounted in the housing and
includes a crankcase with a generally vertically
disposed passageway in communication with the oil
sump, a rotatable crankshaft, and means for compressing
refrigerant. The crankshaft is generally horizontally
disposed and rotatably received in the crankcase, and
has a reduced diameter portion forming between the
crankshaft and crankcase an annular chamber in
communication with the crankcase passageway. The
crankshaft further includes a helical groove forming
between the crankshaft and crankcase a helical
passage between the annular chamber and compressing
means. Upon rotation of the crankshaft, a low
pressure area is created in the annular chamber to
draw lubricant upwardly through the crankcase
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passageway and into the annular chamber, from which
oil is delivered by the helical passage axially along
the crankshaft for lubricating the crankshaft
- bearings.
It is an object of the present invention to
provide an improved horiæontal shaft oil pump that
efficiently delivers a desired amount of lubricant
upwardly from an oil sump and horizontally along the
crankshaft for lubricating bearings and other moving
parts.
Another object of the present invention ls to
provide an improved horizontal shaft oil pump that is
self-priming.
Yet another object of the present invention is
to provide an improved horizontal shaft oil pump that
is inexpensive to manufacture and easily assembled.
Further objects of the present invention will
appear as a description precedes.
The above mentioned and other features and
objects of this invention and the manner of attaining
them, will become more apparent and the invention
itself will be better understood by reference to the
following description of an embodiment of the invention
taken in conjunction with the accompanying drawings,
wherein~
Fig. l is a longitudinal cross-sectional view of
a preferred embodiment of the present invention;
Fig. 2 is a partially broken-away end elevational
view of the embodiment in Fig. l;
Fig. 3 is an elevational view of the crankshaft
in the embodiment of Fig. l;
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Fig. 4 is a top plan view of the crankshaft of
Fig. 3;
Fig. 5 is an end elevational view of the crankshaft
in
Fig. 4;
Fig. 6 is a partially broken-away cross-sectional
view of a helical groove in the crankshaft of Fig. 3,
and
Fig. 7 is a partially broken-away exploded view
of the embodiment in Fig. 1 illustrating the flow of
lubricant.
Referring to Figs. 1 and 2, a rotary compressor
is indicated at 10 incorporating horizontal shaft oil
pump 11 of the present invention. Although the
present invention will be described in terms of
rotary compressor 10, horizontal shaft oil pump 11 of
can also be incorporated with other types of compressors
requiring lubrication of rotating horizontal shafts.
The motor-compressor unit 8 of rotary compressor
10 comprises motor 13 having rotor 15 and stator 14
with windings 16, and cylindrical housing 12 shrunk
down on stator 14. The opposite ends of housing 12
are closed by end plates 18, 20 welded thereto. End
plate 18 includes terminal pin assembly 22 and
discharge outlet 24 having discharge tube 26 connected
thereto by connector 28. End plate 20 includes
opening 30 through which is received suction inlet
tube 32 indicated in dashed lines. A pair of mounting
brackets 34, 36 are welded to the opposite ends of
housing 12, and each includes a pair of support
members, such as resilient grommets 36, 38.
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Mounted within interior 40 of housing 12 is
crankcase 42 including main bearing block 44 having
oil passageway 46 generally vertically disposed
- therein. Housing 12 includes oil sump 48, and the
lower portion of main bearing block 44 is submerged
therein to provide communication between oil passageway
46 and horizontally disposed bore 50 in crankcase 42.
For purposes of the present application, the term
"vertically disposed" as it applies to passaqeway 46
is to be construed broadly and means that oil must
flow upwardly therein from sump 48 against the force
of gravity.
Crank~haft 52 is horizontally rotatably received
in bore 50, and rotor 56 is shrunk down on portion 54
of crankshaft 52 to rotate crankshaft 52 upon application
of electrical current to motor 13 through terminal
pin assembly 22.
The opposite end portion of crankshaft 42
includes eccentric 58 having slot 59 and is received
in cylinder plate 60, which is connected to main
bearing block 44 by screws 66. Roller 62 is rotatably
received about eccentric 58 in cylinder 59, and valve
plate or back plate 64 is attached to cylinder 60 by
means of screws 66. Discharge muffler 68 is attached
to back plate 64 by screws 66, and back plate 64
includes hole 70 in axial alignment with crankshaft
52 and opening 72 in mu~fler 68. Vane 63 is slidably
received in slot 67 in cylinder plate 60 and is
biased against roller 62 by C-shaped spring ~5, which
3n is secured to cylinder plate 60. Cylinder plate 60
has inlet 69 with which suction inlet tube 32
communicates.
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g
A valve assembly 74 permits compressed refrigerant
to flow from cylinder 59 through back plate 64 and
into discharge muffler 68. Valve assembly 7~ includes
opening 76 in back plate 64 which communicates
between cylinder 59 and muffler 68~ A leaf valve 78
is secured in place over opening 76 by valve retainer
80 and screw 82 (Fig. 2) received through valve
retainer 80, valve 78, and threadedly secured in back
plate 64.
Referring now to Figs. 1, 3-6, crankshaft 52 has
a reduced diameter center portion 84 which forms
annular chamber 86 between crankshaft 52 and
crankcase 42, annular chamber 86 communicating with
oil passageway 46. Disposed in crankshaft 52 are a
pair of helical grooves 88, 90 on opposite sides of
and in communication with annular chamber 86.
Referring particularly to Figs. 3 and 4, it can
be seen that grooves 88 and 90 are oppositely oriented
in crankshaft 52 to deliver lubricant from annular
chamber 86 in opposite directions along crankshaft
52. The radial dimension or depth and the axial
dimension or length of each groove 88, 90 is
predetermined as a function of several variables,
among which are the diameter and length of the
crankshaft, the vertical height of the crankshaft
above the oil sump, and the like. Grooves 88, 90 are
machined in crankshaft 52 to provide sufficient
bearing surface between ridges 92 and the inner
surface of crankcase bore 50, while at the same time
efficiently supplying a desired amount of lubricant
along crankshaft 52. In the disclosed embodiment,
each groove 88, 90 has a bottom surface 94 with
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upwardly extending sides 96, 98 which diverge radially
outwardly from bottom surface 94 to ridges 92 for
ease of machining.
~ Given in the following are dimensions of a
typical working embodiment of crankshaft 52 in the
present invention, and are exemplary only and do not
limit the scope of the invention:
Compressor horsepower 1/4
Crankcase bore ID .5014-.5017
Crankshaft OD .5008-.5011"
Crankshaft axial length
excluding eccentric 58 3.380-3.385"
Reduced diameter center
portion 84 OD .451-.461"
Groove radial depth .005-.007"
Bottom surface 94
axial width .035-.045"
Angular inclination of
sides 96, 98 43-47
Grooves 88, 90 are machined in crankshaft 52 at four
threads per inch, and as illustrated in Fig. 1, form
between crankshaft 52 and crankcase 44 helical
passages 100,102, respectively, in communication with
annular chamber 86. Passage 102 also communicates
with slot 59 in eccentric 58 (Fig. 4).
In operation, electrical current is supplied to
terminal pin assembly 22 to rotate rotor 15 and
crankshaft 52, and refrigerant is supplied through
suction inlet tube 32 and inlet 69 into cylinder 59.
As crankshaft 52 rotates, eccentric 58 rotates roller
62 in cylinder 60 to compress the supplied refrigerant.
Compressed refrigerant is discharged through valve
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ll
assembly 74 into muffler 68, and then through an
opening (not shown) in muffler 68 into the interior
40 of housing 12. The compressed refrigerant passes
over motor 13 to cool motor 13 and is then discharged
through outlet 24 into discharge tube 26.
Referring to Figs. 1, 4, and 7, lubrication is
provided as soon as crankshaft 52 is rotated. The
rotation of crankshaft 52 creates a partial vacuum or
low pressure area in annular chamher 86 which draws
lubricant upwardly from oil sump 48 through oil
passageway 46 into chamber 86. From annular chamber
86, lubricant is delivered in opposite directions by
helical passages 100, 102. Lubricant is discharged
from helical passage 100 on to rotor 56, which will
throw the lubricant outwardly against the inner
surface of housing 12 for cooling and return to oil
sump 48.
Lubricant delivered by helica~ passage 102
lubricates bore 50 of crankcase 42, and exits passageway
102 through slot 59 in eccentric 58. Lubricant
delivered to slot 59 lubricates the mutually engaging
surfaces of eccentric 58 and roller 62. From slot
59, lubricant is then delivered through hole 70 in
back plate 64 and opening 72 in discharge muffler 68
for return to oil sump 48.
If desired, an outboard bearing (not shown) may
be provided with eccentric 58 to rotate within bore
70 in back plate 64. Any such outboard bearing may
include an oil passage in communication with slot 59
in eccentric 58 to deliver lubricant through the
outboard bearing and to oil sump 48.
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12
While this invention has been described as
having a preferred embodiment, it will be understood
that it i9 capable of further modifications. This
- application is therefore intended to cover any
variations, uses, or adaptations of the invention
following the general principles thereof, and including
such departures from the present disclosure as come
within known or customary practice in the art to
which this invention pertains and fall within the
limits of the appended claims.
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