Language selection

Search

Patent 2540792 Summary

Third-party information liability

Some of the information on this Web page has been provided by external sources. The Government of Canada is not responsible for the accuracy, reliability or currency of the information supplied by external sources. Users wishing to rely upon this information should consult directly with the source of the information. Content provided by external sources is not subject to official languages, privacy and accessibility requirements.

Claims and Abstract availability

Any discrepancies in the text and image of the Claims and Abstract are due to differing posting times. Text of the Claims and Abstract are posted:

  • At the time the application is open to public inspection;
  • At the time of issue of the patent (grant).
(12) Patent: (11) CA 2540792
(54) English Title: LUBRICATION OF A HERMETIC CARBON DIOXIDE COMPRESSOR
(54) French Title: LUBRIFICATION D'UN COMPRESSEUR HERMETIQUE A GAZ CARBONIQUE
Status: Deemed expired
Bibliographic Data
(51) International Patent Classification (IPC):
  • F04B 39/02 (2006.01)
  • F04B 23/00 (2006.01)
  • F04C 29/02 (2006.01)
  • F04D 29/063 (2006.01)
(72) Inventors :
  • DREIMAN, NELIK I. (United States of America)
  • BUNCH, RICK L. (United States of America)
(73) Owners :
  • TECUMSEH PRODUCTS COMPANY (United States of America)
(71) Applicants :
  • TECUMSEH PRODUCTS COMPANY (United States of America)
(74) Agent: SIM & MCBURNEY
(74) Associate agent:
(45) Issued: 2009-08-04
(22) Filed Date: 2003-06-10
(41) Open to Public Inspection: 2003-12-11
Examination requested: 2006-03-21
Availability of licence: N/A
(25) Language of filing: English

Patent Cooperation Treaty (PCT): No

(30) Application Priority Data:
Application No. Country/Territory Date
10/166,646 United States of America 2002-06-11

Abstracts

English Abstract

A hermetic compressor comprises a housing having an oil containing sump, a motor and a compression mechanism in the housing, a bearing in a stationary frame and a drive shaft supported by the bearing. The drive shaft operatively couples the motor and the compression mechanism and a longitudinal oil supply passageway extends through the drive shaft in fluid communication with the sump. A chamber, located at a first end of the drive shaft, is in fluid communication with the oil supply passageway. Oil from the sump is provided to the chamber through the oil supply passageway. An oil return passageway extends from the chamber to an annulus formed between the bearing and the drive shaft and extends at least partially through the stationary frame. Lubricating oil is provided to the annulus through the oil return passageway so that the bearing and drive shaft interface is lubricated.


French Abstract

Un compresseur hermétique comprenant un boîtier muni d'un carter d'huile, d'un moteur et d'un mécanisme de compression à l'intérieur, d'un roulement dans un cadre fixe et d'un arbre d'entraînement soutenu par le roulement. L'arbre d'entraînement accouple le moteur et le mécanisme de compression, et un conduit d'alimentation en huile est acheminé dans l'arbre d'entraînement pour établir un lien avec le carter. Une chambre, située à la première extrémité de l'arbre d'entraînement, est en lien avec le conduit d'alimentation en huile. L'huile dans le carter est acheminée vers la chambre par le conduit d'alimentation en huile. Un conduit de retour d'huile relie la chambre et un espace annulaire entre le roulement et l'arbre d'entraînement et passe partiellement par le cadre fixe. L'huile de lubrification est acheminée vers l'espace annulaire par le conduit de retour d'huile afin que l'interface roulement et arbre d'entraînement soit lubrifié.

Claims

Note: Claims are shown in the official language in which they were submitted.



WHAT IS CLAIMED IS:


1. A hermetic compressor comprising:

a housing having an oil containing sump formed therein;
a motor mounted in said housing;
a compression mechanism located in said housing;
a bearing disposed in a stationary frame;
a drive shaft supported by said bearing and having first and second ends, said
drive
shaft operatively coupling said motor and said compression mechanism, a
longitudinal oil
supply passageway extending through said drive shaft in fluid communication
with said
sump;
a chamber located at said first end of said drive shaft in fluid communication
with
said oil supply passageway, oil from said sump being provided to said chamber
through said
oil supply passageway; and

an oil return passageway extending from said chamber to an annulus formed
between
said bearing and said drive shaft, and extending at least partially through
said stationary
frame, lubricating oil being provided to said annulus through said oil return
passageway,
whereby the bearing and drive shaft interface is lubricated.


2. The compressor of claim 1, wherein said compression mechanism further
comprises a
cylinder block having opposite sides, said frame positioned adjacent a first
side of said
cylinder block, and an outboard bearing positioned adjacent a second side of
said cylinder
block, said first end of said drive shaft being rotatably supported by said
outboard bearing.


3. The compressor of claim 2, wherein said oil return passageway is formed by
a first
passage extending through said outboard bearing from said chamber, a second
passage
extending through said cylinder block, and a third passage extending through
said frame to
said bearing.


4. The compressor of claim 2, wherein said bearing has a groove formed
therein, the oil
in said annulus being directed by said groove to upper and lower ends of said
bearing.


16


5. The compressor of claim 2, wherein said annulus is formed in said drive
shaft.


6. The compressor of claim 2, wherein excess oil in said annulus flows over
portions of
said motor into said sump, whereby said motor is cooled.


7. The compressor of claim 2, further comprising a second compression
mechanism
located at said second end of said drive shaft, said second compression
mechanism including
a second cylinder block having opposite sides, a second outboard bearing
adjacent a first side
of said second cylinder block, and a second frame comprising the second
outboard bearing
adjacent a second side of said second cylinder block.


8. The compressor of claim 7, wherein said second bearing has a port extending

therethrough through which oil being returned to said sump passes.


17

Description

Note: Descriptions are shown in the official language in which they were submitted.



CA 02540792 2003-06-10

LUBRICATION OF A HERMETIC CARBON DIOXIDE COMPRESSOR
BACKGROUND OF THE INVENTION
The present invention relates to hermetic compressors and more particularly to
two
stage compressors using carbon dioxide as the working fluid.
Conventionally, multi-stage compressors are ones in which the compression of
the
refrigerant fluid from a low, suction pressure to a high, discharge pressure
is accomplished in
more than one compression process. The types of refrigerant generally used in
refrigeration
and air conditioning equipment include chlorafluorocarbons (CFCs) and
hydrochlorofluorocarbon (HCFC). Additionally, carbon dioxide may be used as
the working
fluid in refrigeration and air conditioning systems. By using carbon dioxide
refrigerant,
ozone depletion and global warming are nearly eliminated. Further, carbon
dioxide is non-
toxic, non-flammable, and has better heat transfer properties than CFCs and
HCFC, for
example. The cost of carbon dioxide is significantly lower than CFC and HCFC.
Additionally, it is not necessary to recover or recycle carbon dioxide which
contributes to
significant savings in training and equipment.
In a two stage compressor, the suction pressure gas is first compressed to an
intermediate pressure. The intermediate pressure gas can be directed to the
second stage
suction side or cooled in the unit heat exchanger before delivery to the
second stage suction.
The intermediate pressure gas is next drawn into a second compressor mechanism
where it is
compressed to a higher, discharge pressure for use in the remainder of a
refrigeration system.
The compression mechanisms of the two stage compressor may be stacked atop one
another on one side of the motor, or positioned with one located on each side
of the motor.
When the compression mechanisms are located on opposite sides of the motor,
each
compression mechanism is provided with an oil sump which provides lubricating
oil to the
respective compressor components. Oil in the lower, main sump provides
lubrication to the
first compression mechanism and is drawn through a passage in the drive shaft
to lubricate
the second compression mechanism. Oil from the upper sump also provides
lubrication to
the second compression mechanism.

Problems may occur if the excess oil does not return to the main oil sump
during
compressor operation and collects in the upper sump. Such problems include
overfilling of
the upper sump and depleting the supply of oil in the lower, main sump. If the
amount of oil
in the lower sump is reduced, the amount of oil required to lubricate the
bearing surfaces may
be insufficient.


CA 02540792 2003-06-10

During shutdown of the compressor, a portion of the unused or excess oil may
return
to the main oil sump by gravity. The amount of oil between bearing surfaces is
significantly
reduced or eliminated. When the compressor is restarted, the bearings surfaces
come into
contact with one another which can damage these surfaces.
It is desired to provide a two stage hermetic compressor which uses carbon
dioxide as
the working fluid and is provided with a lubrication system that improves
lubrication during
startup and operation of the compressor.
SUMMARY OF THE INVENTION
The present invention relates to a two stage hermetic compressor which uses
carbon
dioxide as the working fluid. The compressor has a pair of compression
mechanisms located
at opposite ends of an electric motor. The compression mechanisms and motor
are housed in
separate housings forming modules which are secured to one another during
assembly of the
compressor. A drive shaft operatively connects the motor and compression
mechanisms. An
oil sump containing lubricating oil is formed in eacll compression mechanism
module. The
drive shaft is provided with a longitudinal passageway through which oil from
the lower
sump passes to supply a plurality of radially extending passageways in the
shaft. Extending
from the radial passageways are inclined oil accumulating cavities which store
oil during
compressor shutdown. The oil is immediately supplied the bearing surfaces upon
startup of
the compressor to prevent metal-to-metal contact between bearing surfaces.
The compressor of the present invention further includes an oil return system
including a recess formed at the upper end of the drive shaft. The oil in the
recess is directed
to an oil annulus formed in the drive shaft via passageways formed in the
outboard bearing,
cylinder block, and main bearing of the upper compression mechanism module.
The oil in
the annulus then passes through the motor module and returns to the lower
sump.
The compressor of the present invention also includes a discharge tube mounted
in the
upper compression mechanism module. The discharge tube is provided with a
plurality of
apertures located near the bottom thereof. If the level of the oil in the
upper sump is at or
above the level of the apertures in the discharge tube, oil is aspirated into
the discharge
pressure gas entering the refrigeration system.

Accordingly, in one aspect of the present invention there is provided a
hermetic
compressor comprising:
a housing having an oil containing sump formed therein;
2


CA 02540792 2008-12-08
a motor mounted in said housing;
a compression mechanism located in said housing;
a bearing disposed in a stationary frame;

a drive shaft supported by said bearing and having first and second ends, said
drive
shaft operatively coupling said motor and said compression mechanism, a
longitudinal oil
supply passageway extending through said drive shaft in fluid communication
with said
sump;

a chamber located at said first end of said drive shaft in fluid communication
with
said oil supply passageway, oil from said sump being provided to said chamber
through said
oil supply passageway; and

an oil return passageway extending from said chamber to an annulus formed
between
said bearing and said drive shaft, and extending at least partially through
said stationary
frame, lubricating oil being provided to said annulus through said oil return
passageway,
whereby the bearing and drive shaft interface is lubricated.
One advantage of the present invention is that the lubrication system provides
oil
accumulating cavities in the drive shaft and on the eccentric which supply
bearing surfaces
with sufficient lubrication during startup and operation of the compressor.

An additional advantage of the present invention is the oil return portion of
the
lubrication system which directs oil after lubrication of the upper
compression mechanism to
the lower, main sump to prevent the main sump from being depleted of its oil
supply.
Another advantage of the present invention is that the discharge outlet of the
compressor is provided with a bleed aperture through which oil is aspirated
and carried with
the discharge gas into the refrigeration system to further prevent overfilling
of the upper
sump.

BRIEF DESCRIPTION OF THE DRAWINGS
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:

Figure 1 is a sectional side view of a compressor assembly in accordance with
the
present invention;

Figure 2 is a sectional view of a cylinder block of the compressor assembly of
Figure
l;

3


CA 02540792 2003-06-10

Figure 3 is a sectional view of the cylinder block of Figure 2, showing an
alternative
intake passage;
Figure 4 is a fragmentary sectional view of the compressor assembly of Figure
1,
showing the upper compression mechanism having an alternative intake passage;
Figure 5 is a fragmentary sectional view of the compressor assembly of Figure
1,
showing the lower compression mechanism;
Figure 6A is a top plan view of a thrust bearing having lubrication grooves
therein;
Figure 6B is a side view of the thrust bearing of Figure 6A taken along line
6B-6B.
Figure 7 is a side view of a discharge valve of the compressor assembly of
Figure 1;
Figure 8 is perspective view of the discharge valve of Figure 7;
Figure 9 is a sectional side view of a discharge valve assembly of a
compression
mechanism of the compressor assembly of Figure 1, shown in its closed
position;

Figure 10 is sectional side view of the discharge valve assembly of Figure 9,
shown in
its open position;
Figure 11 is a fragmentary sectional view of the upper drive shaft of the
compressor
assembly of Figure 1; and
Figure 12 is a fragmentary sectional view of the lower drive shaft of the
compressor
assembly of Figure 1.
Corresponding reference characters indicate corresponding parts throughout the
several views. Although the drawings represent embodiments of the present
invention, the
drawings are not necessarily to scale and certain features may be exaggerated
in order to
better illustrate and explain the present invention.

DETAILED DESCRIPTION OF THE INVENTION
Referring to Figure 1, positive displacement, two stage rotary hermetic
compressor 20
includes lower end compression module 22 and upper end compression module 24
which are
coaxially coupled to opposite axial ends of the electric motor module 26.
Compression
modules 22 and 24 are affixed to motor module 26 using any suitable method
including
welding, brazing, or the like as at 28. Compression modules 22 and 24 are
hermetically
sealed by caps 30 and 32 which are secured to substantially cylindrical
compression
mechanism housing walls 34 and 36, respectively, by welds 28, for example.
Lower housing
wall 34 further includes annular flange 38 extending substantially
perpendicularly from the

4


CA 02540792 2003-06-10

outer surface thereof. Annular flange 38 is provided to support compressor 20
in a
substantially vertical position.
The working fluid used for the refrigeration system of the present invention
may be
carbon dioxide, for example. When carbon dioxide is compressed, the pressures
produced
are significantly greater than those produced when using HCFC refrigerant, for
example. In
order to accommodate for the high working pressures of carbon dioxide, walls
36 of upper
compression module 24 are constructed to be thick enough to withstand the
higher pressure
gas. Walls 36 are thicker than walls 34 of lower compression module 22 as the
pressures
produced during the first stage of compression are substantially lower than
produced during
the second stage of compression.
The use of carbon dioxide in commercial, residential, automotive, and military
applications has been analyzed and the results presented in a publication by
Kruse H.,
Hedelck R., and Suss J., "The Application of Carbon Dioxide as a Refrigerant",
IIR Bulletin,
Vol. 1999-1, and pp. 2-21. Additionally, a publication by Lorenz, G., et al.,
"New Possibility
for Non-CFC Refrigeration", Proc. IIR, 1992, vol. 21, no. 3, pp. 147-163
discusses further
applicability of carbon dioxide.
Located within electric motor module 26 is electric motor 40 including stator
42 and
rotor 44. Stator 42 is interference fitted within cylindrical housing 43 of
module 26 at
substantially the axial center thereof by a method such as shrink fitting, for
example. Axial
cylindrical aperture 46 is located centrally through rotor 44 for receiving
cylindrical sleeve 62
disposed about drive shaft 48 which is mounted therein for rotation with rotor
44. The lower
and upper ends of drive shaft 48 are drivingly connected to first and second
stage
compression mechanisms 50 and 52 housed in lower and upper end compression
modules 22
and 24, respectively.
Drive shaft 48 is constructed from lower drive shaft 54 and upper drive shaft
56.
Integrally formed near the joint ends of drive shafts 54 and 56 are keys 58
and 60,
respectively. Keys 58 and 60 are cut to form a semi-cylindrical end, which
slidingly
interlock to rotatably fix the lower and upper drive shafts and form the
complete cylinder of
drive shaft 48. Cylindrical sleeve 62 is mounted onto drive shaft 48 by any
suitable method
including shrink fitting, over the coupling between lower and upper drive
shafts 54 and 56.
Sleeve 62 is interference fitted within aperture 46 for rotation with rotor
44. Integrally
formed near the outer ends of drive shafts 54 and 56 are eccentric portions 64
and 66,



CA 02540792 2003-06-10

respectively. Drive shafts 54 and 56 are coupled to one another such that
eccentric portions
64 and 66 are radially offset by 180 to achieve better dynamic balance and
motor loading.
Referring to Figures 1, 4, and 5, first stage compression mechanism 50 and
second
stage compression mechanism 52 are mounted within modules 22 and 24. The
modular
design provides motor 40 and compression mechanisms 50 and 52 with individual
housings,
each being maintained at a substantially different pressure. The modular
design also reduces
the cost of assembly of compressor 20 and facilitates flexibility of design by
providing
respective modules 22 and 24 of different capacities.
As shown in Figures 1 and 5, first stage compression mechanism 50 includes
cylinder
block 68 located between outboard bearing 70 and frame or main bearing 72
which is
integrally formed with housing walls 34. Fasteners 74 extend through outboard
bearing 70
and cylinder block 68 to secure bearing 70 and cylinder block 68 to main
bearing 72. Lower
drive shaft 54 is rotatably mounted in main bearing 72 by journa176. As
illustrated in
Figures 1 and 4, second stage compression mechanism 52 includes cylinder block
781ocated
between outboard bearing 80 and frame or main bearing 82 which is integrally
formed with
housing walls 36. Fasteners 74 secure outboard bearing 80 and cylinder block
78 to main
bearing 82. Upper drive shaft 56 is mounted in main bearing 82 by journal 84.
Eccentric
portions 64 and 66 of drive shafts 56 and 58 are received in cylinder blocks
68 and 78 to
drive compression mechanisms 50 and 52.

Referring to Figures 1, 6A, and 6B, located between sleeve 62 and upper planar
surface 98 of main bearing 72 is circular thrust bearing 100 provided to
accept axial loading.
Thrust bearing 100 is provided with aperture 101 through which drive shaft 48
extends when
assembled thereto. Circular thrust bearing 100 is constructed from any
suitable material
having a sufficiently low coefficient of static and kinetic friction so that
rotation of sleeve 62
and thus drive shaft 48 is not hindered. Lubrication oil is delivered to the
thrust-bearing
surface through grooves (not shown) in main bearing 72, thereby further
reducing the
coefficient of friction during compressor start-up and operation. The circular
shape of thrust
bearing 100 helps to form a circumferential, continuous pattern of the oil
film between the
thrust surfaces which prevents metal-to-metal contact.
In order to determine the type of material appropriate for thrust bearing 100,
the
pressure-velocity (PV) loading of the thrust bearing can be used. The pressure-
velocity (PV)
6


CA 02540792 2008-12-08

loading may be computed for numerous external and internal diameters. The
following
parameters are used in these calculations:

P= 4W/B(D 02 - d; 2)

where P is the static loading per unit area, psi (kg/cm2); W is the static
load acting on thrust
bearing 100, lb (kg). Referring to Figures 6A and 6B, D is the outer diameter
and d; is the
inner diameter of thrust bearing 100, in (cm). The static loading per unit
area (P) is first
calculated using the above equation. In order to calculate the surface
velocity (V) of thrust
bearing 100, the following equation is used:

V = B (D,,, N)

where V has the units in/min (cm/min); N is the speed of rotation of thrust
bearing 100, rpm
(cycles/min), which rotates with drive shaft 48; Dtõ is the average diameter,
in (cm),
calculated by the following equation:
Do + &
2
The Pressure-Velocity loading of thrust bearing 100 is then calculated by
multiplying the
static loading per unit area (P) and surface velocity (V) to get the pressure-
velocity loading
(PV), psi-ft/in2 min (kg-m/cm2sec). These calculations are then used to select
an appropriate
material for bearing 100.

One type of suitable material for thrust bearing 100 includes a polyamide such
as
VESPELTM SP-21, which is a rigid resin material available from E.I. DuPont de
Nemours
and Company. The polyamide material has a broad temperature range of thermal
stability,
capable of withstanding approximately 300,0001b. ft/in. with a maximum contact
temperature of approximately 740 F(393 C) when unlubricated. For a machined
thrust
bearing 100 constructed from a material such as VESPELTM, the allowable
pressure (P)
should not exceed 6,600 psi. The PV limit for unlubricated bearing under
conditions of
continuous motion should not exceed 300,000 lb ft/in2 min. In this embodiment
of the
present invention, the ratio of the outside diameter to the inside diameter
(D/d) of thrust
bearing 100 should not exceed 2.

Thrust bearing 100 is provided with radially extending grooves 102 on both
surfaces
of bearing 100 in contact with surface 98 of main bearing 72 and sleeve 62.
Grooves 102 are
provided in thrust bearing 100 for communicating lubricating oil between
thrust bearing 100
and the interfacing surfaces.

7


CA 02540792 2003-06-10

Referring to Figures 1, 4, and 5, first and second stage compression
mechanisms 50
and 52 are illustrated as rotary type compression mechanisms, however,
compression
mechanisms 50 and 52 may be reciprocating, rotary, or scroll type compressors.
Rotary
compressors generally include a vane slidingly mounted in the cylinder block,
which divides
compression chamber 118 located between cylinder blocks 68, 78 and rollers
220, 222
surrounding eccentrics 64, 66 of drive shafts 54, 56. The vane reciprocates
into and out of
the cylinder block as it orbits about the drive shaft. Referring to Figure 2,
cylinder block 68
is provided with aperture 86 in which eccentric portion 64 surrounded by
roller 220 is
received. Radially extending from aperture 86 is intake passage 88 through
which gas to be
compressed is drawn into compression chamber 118. Once the refrigerant gas is
compressed
to a higher pressure, it is discharged through radially extending discharge
passage 104.
Alternatively, as shown in Figure 3, the intake passage may be located
substantially axially to
aperture 86 such as intake passage 92. Referring to Figure 1, refrigerant gas
is drawn into
compression chamber 118 defined in upper cylinder block 78 via axially
oriented inlet
passage 94 extending through main bearing 82. Alternatively, refrigerant gas
may be
provided to compression chamber 118 of second stage compression mechanism 52
via radial
tube 96 as shown in Figure 4. Discharge pressure gases exit compression
mechanism 52
through axially extending passage 106.

Referring to Figures 1 and 2, cylinder block 68 of first stage compression
mechanism
50 is provided with radially extending discharge passage 104 having discharge
valve 108
mounted therein. As shown in Figure 1, outboard bearing 80 of second stage
compression
mechanism 52 is provided with discharge passage 106 which extends axially
therethrough.
Even though discharge passages 104 and 106 are illustrated as being directed
radially and
axially through cylinder block 68 and outboard bearing 80, respectively, the
discharge
passages may be in any suitable configuration through any of the cylinder
block, outboard
bearing, or main bearing.

Referring to Figures 1, 7, 8, 9, and 10, one discharge valve 108 is mounted in
each
discharge passage 104 and 106. During compressor operation, discharge valve
108
reciprocates within discharge passages 104 and 106 so that discharge gases may
pass through
passages 104 and 106 and around valve 108. These discharge gases are then
released into
discharge tube 152 extending from first stage compression mechanism 50 or
discharge
pressure compartment 154 formed in upper compression mechanism module 24, for
example.

8


CA 02540792 2003-06-10

Discharge valve member 108 is an integral one piece valve-spring-retainer
assembly formed
from one piece of material having semi-spherical head portion 110, rectangular
wire spring
122, and valve support 124 including coupling attachment 126. Discharge valve
108 is
formed from a single piece of material having elasticity, fatigue, and
corrosion resistance
qualities. The material must also have spring-like qualities so that spring
122 may be biased
into a closed position and may be compressed to open valve 108. Materials
possessing such
characteristics may include high strength materials such as 17-4PH corrosion
resistant steel,
15-5 PH, C-300, BETA C Titanium, 7075-T6 Aluminum, or like.
Integral discharge valve 108 includes semi-spherically shaped head portion 110
which
faces semi-spherically shaped seating surface 112 (Figures 9 and 10) formed on
the interior
of the outlet end of discharge passages 104 and 106. Semi-spherical seating
surface 112
provides a valve seat for discharge valve 108 and defines cylindrically shaped
outlet 114
(Figures 9 and 10) operable by discharge valve 108. Semi-spherical valve head
portion 110
includes sealing surface 116 which engages semi-spherical seating surface 112,
substantially
filling outlet 114 when in a closed position (Figure 9), thereby reducing the
gas reexpansion
volume of the outlet 114.
Substantially the entire surface of semi-spherical sealing surface 116 facing
compression chamber 118 of compression mechanisms 50 and 52 is exposed to
fluid pressure
generated during compressor operation. The semi-spherical shape of sealing
surface 116
provides a larger surface area than a flat surface of the same diameter. The
semi-spherical
shape provides more area to be affected by discharge pressure refrigerant
which accelerates
the discharge valve opening, thereby increasing compressor efficiency.

Semi-spherical valve seat 112 has substantially the same radius of curvature
as that of
spherical sealing surface 116, so shifting, cocking, tilting or other
dislocations of discharge
valve 108 will not affect sealing contact during valve closing. The radial
inner edge of
discharge outlet 114 has round chamfer 120 (Figures 9 and 10) which helps to
smooth fluid
flow through discharge outlet 114, reducing turbulence that may affect
compressor
efficiency.

Discharge valve 108 is fixed inside discharge passages 104 and 106 by coupling
attachment 126 affixed to valve support 124. Coupling attachment 126 includes
bore 128
extending longitudinally through valve support 124 which is aligned with bores
130 in
cylinder block 68 or outboard bearing 80 to receive spring pin 132. Spring pin
132 secures

9


CA 02540792 2003-06-10

discharge valve 108 within passages 104 and 106 such that valve spring 122 is
slightly
prestessed to prevent leakage during the gas compression process. Discharge
valve 108
reciprocates between a first, closed position (Figure 9) in which sealing
surface 116 engages
semi-spherical seating surface 112 and a second, open position (Figure 10)
with sealing
surface 116 spaced longitudinally away from seating surface 112. During valve
opening and
compression of spring 122, the longitudinal movements of the discharge valve
108 toward the
second position stops when gaps 134, having normally separated facing surfaces
136, of
rectangular wire spring 122 are closed.
Guide member 138 may be provided to guide and maintain the longitudinal
movement of spring 122, when the compression load applied to rectangular wire
spring 122
is high, for example. Guide member 138 is substantially cylindrically shaped
having a
diameter smaller than the inner diameter of spring 122. Front end 140 of guide
member 138
is rounded, forming an additional valve stop. Rear end 142 of guide member 138
has bore
143 drilled therethrough which is aligned with bores 128 and 130 to receive a
portion of
spring pin 132. The alignment of bores 128, 130, and 143 to receive pin 132
provides for
easy assembly of discharge valve 108 and guide member 138 within the
respective cylinder
block, main bearing, or outboard bearing. Clearance space 144 is provided
between outer
surface 146 of guide member 138 and inner surface 148 of spring 122. Clearance
space 144
permits predetermined pivotal movements of valve spring 122 without friction
which can
delay opening and closing of the valve.
In an attempt to reduce the weight of the discharge valve 108, spherical or
conical
cavity 150 is formed in the backside of discharge valve 108. Cavity 150
increases the surface
area affected by backpressure within discharge passages 104 and 106. Cavity
150 increases
the area to which fluid pressure is applied, thus accelerating closure of
discharge valve 108.
Referring now to Figures 1, 11, and 12, the lubrication system of the present
invention
is formed primarily in drive shaft 48, including lower and upper drive shafts
54 and 56
coupled together by sleeve 62. Oil delivery channels 156 and 158 are formed in
fluid
communication centrally along the axis of rotation through drive shafts 54 and
56,
respectively. At the upper end of oil channel 158, formed in outboard bearing
80, is chamber
184. Located at the lower end of lower drive shaft 54 is positive displacement
oil pump 186
(Figure 1) which is operably associated with outboard bearing 70 and oil
channels 156 and
158. The lower end of drive shaft 54, outboard bearing 70, and oil pump 186
are submerged



CA 02540792 2003-06-10

in oil sump 188 formed in lower compression module 22. The lubricating oil in
sump 188
also supplies oil to the reciprocating vane of compression mechanism 50.
Further, the oil in
sump 189 of upper end compression module 24 is necessary for providing
lubrication to the
reciprocating vane of compression mechanism 52.
Referring to Figures 11 and 12, lower drive shaft 54 includes portion 160
supportingly
received in bore 162 of outboard bearing 70 and oil annulus 164 defined by
recessed area

166. Lower and upper journals 167 and 168 are formed on shaft 54 adjacent
annulus 164 and
are supportingly received in main bearing bore 170 of main bearing 72. Journal
76 is
positioned between lower shaft 54 and main bearing bore 170, in contact with
journals 167
and 168 to rotatably support shaft 54 in main bearing 72. Upper drive shaft 56
includes
portion 172 rotatably received in bore 174 of outboard bearing 80. Oil annulus
176 is defined
by recessed area 178 in upper drive shaft 56. Lower and upper journals 179 and
180 are
formed on upper shaft 56 adjacent annulus 176 and are supportingly received in
main bearing
bore 182 of main bearing 82. Journal 84 is positioned between shaft 56 and
main bearing
bore 182, in contact with journals 179 and 180 to rotatably support shaft 56
in main bearing
82.

Rotation of drive shaft 48 operates positive displacement pump 186 to draw oil
from
sump 188 into oil supply passageway 190 formed by oil delivery channels 156
and 158 and
into chamber 184. The pumping action of pump 186 is dependent upon the
rotational speed
of drive shaft 48. Oil in oil supply passageway 190 flows into a series of
radially extending
passages 192 and 194 located in lower shaft 54 by centrifugal force created
during rotation of
shaft 48. Passages 192 are associated with eccentric 64 and passages 194 are
formed in
journal 167 and annulus 164. The lubrication oil delivered through oil supply
passageway
190 also flows into a series of radially extending passages 196 and 198
located in upper shaft
56 and into chamber 184. Passages 196 are locating in eccentric 66 with one
passage 198
being formed in journal 179 and one in oil annulus 176.
Referring to Figure 11, downwardly inclined channel 200 is formed in outboard
bearing 80 extending from chamber 184 to one end of axial channe1202 formed in
cylinder
block 78 of second stage compression mechanism 52. Extending from a second end
of axial
channel 202 is downwardly inclined channel 204 formed in main bearing 82 which
is in fluid
communication with oil annulus 176 defined in upper drive shaft 56. Oil
annulus 176 is in
fluid communication with helical oil groove 205 formed in the inner wall of
journal 84,

11


CA 02540792 2003-06-10

compartment 206 in electric motor module 26, annular cavity 208 formed in
journal 84, and
annular cavity 210 formed in outboard bearing 80.
Oil supplied to chamber 1841ocated at the top end of upper drive shaft 56
flows
through channels 200, 202, and 204 to oil annulus 176 and combines with oil
supplied by
radially extending passage 196. At least a portion of the oil flows upwardly
to lubricate
upper journal 180 and downwardly to lubricate lower journal 179 through
helical journal
groove 205. The excess lubricating oil is returned to the oil sump 188 by
traveling through
electric motor module 26 and passages 212 (Figure 1) extending through main
bearing 72.
Referring to Figure 12, oil passing through oil supply passageway 190 enters
radial passage
194 to fill annulus 164. Helical groove 207 may be formed in journa176 to
direct the
lubricating oil in annulus 164 to lower and upper journals 167 and 168.
Due to extended length of oil supply passageway 190, lubrication of lower
journal
bearings 76, 167, and 168, and particularly upper journal bearings 84, 179,
and 180, can be
delayed, preventing the formation of an oil film to separate the interfacing
bearing surfaces.
The expected life of bearings is partially related to the oil film thickness
between the

interfacing bearing surfaces. The required clearance for mating parts of
rotary compressors is
in the range of 0.0005 inches to 0.0011 inches, thus the thickness of the oil
film is very small.
During initial operation of compressor 20, there is no oil film located
between the interfacing
bearing surfaces and thus, the bearing surfaces are in metal-to-metal contact.
During peak
load operation of the compressor, the frequency of starting and stopping the
compressor is
high, and some of the oil used to form the film will return to oil sump 188
due to gravity. A
portion of the oil will remain between the interfacing bearing surfaces,
however, the amount
of oil is not great enough to support formation of adequate film thickness.
The contact
between the interfacing bearing surfaces will cause locally high stresses
resulting in fatigue
of the bearing material.
In prior art compressors, oil retaining recesses are used to contain the
lubricating oil
flowing from the journal surface when the compressor stops frequently,
however, these
recesses will not provide lubricating oil to the bearings at start-up.
Further, the prior art
compressors have been provided with circumferential grooves which form the oil
retaining
recesses. These grooves may weaken the drive shaft.

In order to provide lubricating oil to the interfacing bearings surfaces
during initial
start-up and frequent starting and stopping of the compressor, drive shafts 54
and 56 of the
12


CA 02540792 2003-06-10

present invention are provided with oil accumulating cylindrical cavities 214.
Cavities 214
are formed in drive shafts 54 and 56 being inclined downwardly from the
external oil deliver
end of radially extending passages 192, 194, 196, and 198. Cavities 214 are
"blind" bores
meaning that the bores do not extend completely through drive shafts 54 and 56
and are not
in fluid communication with oil supply passageway 190. Cavities 214 are
located beneath
with each radially extending passage 192, 194, 196, and 198 with the opening
of each cavity
214 being at least partially located in one of the radially extending
passages. Cavities 214
and passages 192, 194, 196, and 198 are radially aligned with the passage
being located
directly above the cavity.

The outlet part of each radially extending passages 192, 194, 196, and 198 is
fluid
communication with annular recess cavities 208, 210, oil annulus recesses 164,
176, and
cavities 216, 218. Cavities 216, 218 are formed between rollers 220, 222 and
eccentrics 64,
66. Rollers 220, 222 are mounted to drive shafts 54, 56 in surrounding
relationship of
eccentrics 64, 66 to help drive compression mechanisms 50, 52. When the
compressor is
stopped, the oil accumulated in the cavities 208, 210, 164, 176, 216, and 218
will tend to flow
downwardly due to gravity. A portion of the oil collected in cavities 208,
210, 164, 176, 216,
and 218 will be directed to the oil sump 188 while a portion of the oil in
these cavities will be
directed to oil accumulating cavities 214. During start-up of compressor 20,
lubricant stored
in cavities 214 is drawn out of cavities 214 by centrifugal force to supply
lubrication to the
interfacing bearing surfaces before the oil being forced through oil supply
passageway 190 by
oil pump 186 can reach these surfaces. Additionally, upper compression module
24 is
charged with lubricating oil during compressor assembly which also provides
compression
mechanism 52 with lubrication during compressor start-up. This eliminates the
metal-to-
metal contact between bearing surfaces at start-up and improves reliability of
the compressor.
Oil accumulating recesses 224 and 226 are formed in the upper planar surfaces
of lower and
upper shaft eccentrics 64 and 66 to receive oil as the compressor stops. The
oil in recesses
224 and 226 is immediately supplied to the contacting surfaces of rollers 220,
222 and
eccentrics 64, 66 at compressor start-up.

Referring to Figure 1, during compressor operation, the flow of fluid through
compressor 20 is as follows. Low pressure suction gas is supplied directly to
first stage
compression mechanism 50 of lower end compression module 22 via suction inlet
88 or 92
(Figures 2 and 3). As drive shaft 48 rotates, compression mechanism 50 is
driven to

13


CA 02540792 2003-06-10

compress the low pressure suction gas to an intermediate pressure. The
intermediate pressure
gas is discharged through discharge port 90 (Figure 2), past discharge valve
108 in discharge
passage 104 and into discharge tube 152. The intermediate pressure gas flows
along tube 152
into a unit cooler (not shown) located outside of the compressor casing.
Subsequently, the
cooled intermediate pressure refrigerant gas is introduced into compartment
206 of electric
motor module 26 through inlet tube 228. Compartment 206 is in fluid
communication with
compartment 230 of lower end compression module 22 through oil passages 212,
which
allow oil to be reclaimed by oil sump 188. Introduction of the cooled
refrigerant gas into
electric motor compartment 206 helps to cool electric motor 40. Further, by
cooling the
intermediate pressure gas, the amount of heat transfer between the lubricant
and the
refrigerant gas is reduced due to the minimal temperature difference between
the two fluids.
Conically shaped baffle 234 separates incoming lubricating oil from the
intermediate pressure
gas entering upper compression module 24 and prevents suction port 94 formed
in main
bearing 82 from direct suction of oil coming from motor stator-rotor gap 238.
Baffle 234 is
secured to surface 236 of main bearing 82, being concentric with drive shaft
48. The
intermediate pressure refrigerant gas entering second stage compression
mechanism 52 is
compressed to a higher, discharge pressure. The high pressure gas is then
discharged past
discharge valve 108 located in discharge passage 106 into high pressure
discharge
compartment 154 defined in upper end compression module 24 and through
discharge tube
242 mounted in cap 32 to the refrigeration system (not shown). Outboard
bearing 80 acts to
separate oil supply passageway 190 and chamber 184 from the high pressure
fluid in cavity
150. The high pressure, discharge gas from second stage compression mechanism
52
contains some oil. A portion of this oil is separated from the discharge gas
and is trapped in
oil sump 189 of upper end compression module 24 before the gas is discharged
through gas
inlet 241 located at the inner end of tube 242. Discharge tube 242 includes a
series of inlet
holes 244 and bleed hole 246 located near the bottom of tube 242. As oil level
in the sump
reaches the height of bleed hole 246, gas inlet 241 is submersed in the oil.
The discharge
pressure gas then enters discharge tube 242 through inlet holes 244. Oil is
aspirated through
hole 246 and into discharge tube 242 under action of the discharge flow
through inlet holes
244.

While this invention has been described as having an exemplary design, the
present
invention may be further modified within the spirit and scope of this
disclosure. This

14


CA 02540792 2003-06-10

application is therefore intended to cover any variations, uses, or
adaptations of the invention
using its general principles. Further, this application is intended to cover
such departures
from the present disclosure as come within known or customary practice in the
art to which
this invention pertains.


Representative Drawing
A single figure which represents the drawing illustrating the invention.
Administrative Status

For a clearer understanding of the status of the application/patent presented on this page, the site Disclaimer , as well as the definitions for Patent , Administrative Status , Maintenance Fee  and Payment History  should be consulted.

Administrative Status

Title Date
Forecasted Issue Date 2009-08-04
(22) Filed 2003-06-10
(41) Open to Public Inspection 2003-12-11
Examination Requested 2006-03-21
(45) Issued 2009-08-04
Lapsed 2014-06-10

Abandonment History

There is no abandonment history.

Payment History

Fee Type Anniversary Year Due Date Amount Paid Paid Date
Request for Examination $800.00 2006-03-21
Registration of a document - section 124 $100.00 2006-03-21
Application Fee $400.00 2006-03-21
Maintenance Fee - Application - New Act 2 2005-06-10 $100.00 2006-03-21
Maintenance Fee - Application - New Act 3 2006-06-12 $100.00 2006-03-21
Maintenance Fee - Application - New Act 4 2007-06-11 $100.00 2007-06-11
Maintenance Fee - Application - New Act 5 2008-06-10 $200.00 2008-04-28
Final Fee $300.00 2009-05-13
Maintenance Fee - Application - New Act 6 2009-06-10 $200.00 2009-05-13
Maintenance Fee - Patent - New Act 7 2010-06-10 $200.00 2010-05-13
Maintenance Fee - Patent - New Act 8 2011-06-10 $200.00 2011-05-16
Maintenance Fee - Patent - New Act 9 2012-06-11 $200.00 2012-05-15
Owners on Record

Note: Records showing the ownership history in alphabetical order.

Current Owners on Record
TECUMSEH PRODUCTS COMPANY
Past Owners on Record
BUNCH, RICK L.
DREIMAN, NELIK I.
Past Owners that do not appear in the "Owners on Record" listing will appear in other documentation within the application.
Documents

To view selected files, please enter reCAPTCHA code :



To view images, click a link in the Document Description column. To download the documents, select one or more checkboxes in the first column and then click the "Download Selected in PDF format (Zip Archive)" or the "Download Selected as Single PDF" button.

List of published and non-published patent-specific documents on the CPD .

If you have any difficulty accessing content, you can call the Client Service Centre at 1-866-997-1936 or send them an e-mail at CIPO Client Service Centre.


Document
Description 
Date
(yyyy-mm-dd) 
Number of pages   Size of Image (KB) 
Claims 2008-12-08 2 63
Description 2008-12-08 15 840
Drawings 2008-12-08 5 220
Abstract 2008-12-08 1 22
Abstract 2003-06-10 1 23
Description 2003-06-10 15 838
Claims 2003-06-10 2 61
Drawings 2003-06-10 5 223
Representative Drawing 2006-05-25 1 26
Cover Page 2006-07-06 2 69
Representative Drawing 2009-07-09 1 30
Cover Page 2009-07-09 2 69
Assignment 2003-06-10 4 111
Correspondence 2006-04-26 1 37
Fees 2009-05-13 1 57
Fees 2008-04-28 1 58
Fees 2007-06-11 1 53
Prosecution-Amendment 2008-06-17 2 67
Prosecution-Amendment 2008-12-08 9 326
Correspondence 2009-05-13 1 56