Rotary expansible chamber devices – Working member has planetary or planetating movement – Helical working member – e.g. – scroll
Reexamination Certificate
1998-09-30
2001-02-20
Nguyen, Hoang (Department: 3748)
Rotary expansible chamber devices
Working member has planetary or planetating movement
Helical working member, e.g., scroll
C418S100000
Reexamination Certificate
active
06190148
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates in general to a fluid displacement device. More particularly, it relates to an improved scroll-type fluid displacement device with a “sliding surface thrust bearing” and a “two way suction oil-gas passages” to assure sufficient lubricant supply to the thrust bearing under oil-mist lubrication condition and an “oldham ring with one sided keys” to maximize the working area of the sliding surface thrust bearing for variable speed applications.
Scroll-type fluid displacement devices are well-known in the art. For example, U.S. Pat. No. 801,182 to Creux discloses a scroll device including two scroll members each having a circular end plate and a spiroidal or involute scroll element. These scroll elements have identical spiral geometry and are interfit at an angular and radial offset to create a plurality of line contacts between their spiral curved surfaces. Thus, the interfit scroll elements seal off and define at least one pair of fluid pockets. By orbiting one scroll element relative to the other, the line contacts are shifted along the spiral curved surfaces, thereby changing the volume of the fluid pockets. This volume increases or decreases depending upon the direction of the scroll elements' relative orbital motion, and thus, the device may be used to compress or expand fluids.
Referring to
FIGS. 1
a
-
1
d,
the general operation of conventional scroll compressor will now be described.
FIGS. 1
a
-
1
d
schematically illustrate the relative movement of interfitting spiral-shaped scroll elements,
1
and
2
, to compress a fluid. The scroll elements,
1
and
2
, are angularly and radially offset and interfit with one another.
FIG. 1
a
shows that the outer terminal end of each scroll element is in contact with the other scroll element, i.e., suction has just been completed, and a symmetrical pair of fluid pockets A
1
and A
2
has just been formed.
Each of
FIGS. 1
b
-
1
d
shows the position of the scroll elements at a particular drive shaft crank angle which is advanced from the angle shown in the proceeding figure. As the crank angle advances, the fluid pockets, A
1
and A
2
, shift angularly and radially towards the center of the interfitting scroll elements with the volume of each fluid pockets A
1
and A
2
being gradually reduced. Fluid pockets A
1
and A
2
merge together at the center portion A as the crank angle passes from the state shown in
FIG. 1
c
to the state shown in
FIG. 1
d.
The volume of the connected single pocket is further reduced by an additional drive shaft revolution. During the relative orbit motion of the scroll elements, outer spaces, i.e. the suction chambers, which are shown as open in
FIG. 1
b
and
1
d,
change to form new sealed off fluid pockets in which the next volume of fluid to be compressed is enclosed (
FIGS. 1
c
and
1
a
show these states).
In some applications, such as in automobile air conditioning compressors, the compressor rotates at a speed variable from 800-6000 rpm, which is a big challenge to the thrust bearing of the compressor. It is unreliable to lubricate the thrust bearing in an automobile air conditioning compressor by an oil pump which is used in residential air conditioning compressors. It is because the oil level in the oil sump of an automobile air conditioning compressor constantly changes depending on the posture of the automobile, up hill, down hill or horizontal. Therefore, an oil mist lubrication scheme has been widely used in existing technology of automobile air conditioning compressors. In this scheme the amount of oil supplied to bearings is limited. The sliding surface thrust bearing with sufficient lubrication is inexpensive and capable to provide quiet operation and stable support. It is successfully used in residential scroll air conditioning compressors, but is not used in the automobile scroll air conditioning compressors due to the above mentioned reason. In stead, in an automobile air conditioning compressor, thrust ball bearing is used. The ball thrust bearing, for example, used in the scroll air conditioning compressors made by Sanden Corporation, tolerates less lubrication. However, the ball thrust bearing is expensive. It makes loud noises at high speed and wears out quickly due to the high contact stresses at the contact points between the balls and the races.
The present invention provides an improved scroll-type fluid displacement device. By providing a mechanism of two way suction oil-gas passages, most oil in the oil mist is collected and then directed to the sliding surface thrust bearing to meed the lubrication requirement and at the same time the suction pressure losses is minimized. The sliding surface thrust bearing is capable to operate at rotation speeds variable in a wide range. An oldham ring with one sided keys allows to maximize the working surface of the thrust bearing.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a scroll-type fluid displacement device in which a sliding surface thrust bearing with maximum effective bearing surface is capable to operate at variable rotation speeds.
It is also an object of the present invention to provide a mechanism of two way suction oil-gas passages. The most of oil in the return mixture of the refrigerant and oil mist is collected to form oil rich mixture when passing the passages. The oil rich mixture is directed to lubricate the sliding surface thrust bearing. The most of the refrigerant gas directly flows to the suction ports of the scroll device. Thus, the suction pressure loss is minimized.
In order to implement these and other objects, the disclosed embodiment of the present invention provide a scroll-type fluid displacement device, which includes a housing having a fluid inlet port and a fluid outlet port. A first scroll member has an end plate from which a first scroll element extends axially into the interior of the housing. A second scroll member also has an end plate from which a second scrolled element extends axially. The second scroll member is movably disposed for non-rotative orbital movement relative to the first scroll member. A sliding surface thrust bearing supports the second end plate of the second scroll member.
The first and second scroll elements interfit at an angular and radial offset to create a plurality of line contacts which define at least one pair of sealed fluid pockets. Drive means is operatively connected to the scroll members to effect their relative orbiting motion while preventing their relative rotation by an oldham ring, thus causing the fluid pockets to change volume.
The disclosed embodiments of the present invention provide mechanism of two way suction oil-gas passages. The mixture of refrigerant and oil mist entering the housing through the fluid inlet port can flow along two passages in two different directions. One direction is the direct extension of the inlet port, leading the mixture to the center portion of the housing and the sump. The most of oil mist and droplets flow in this direction due to the large inertia caused by its high density to form a mixture rich in oil mist. The oil rich mixture flows thorough the gaps in the main shaft bearing and through the radial passages at the working surface of the thrust bearing and thus lubricate the thrust bearing surface. The other direction is a sharp running from the inlet port to the suction chambers formed by two scroll members where is at the lowest pressure in entire housing. Most refrigerant gas driven by the pressure differential between the inlet port and the suction chambers makes a sharp turning and flow to the suction chambers. Thus the pressure drop of the return refrigeration gas is minimized.
In another aspect of the present invention the scroll-type fluid displacement device includes a sliding surface thrust bearing which has at least one radial passage on its working surface to allow the oil rich mixture form the gap in the main shaft bearing flowing through and lubricating the working surface of the thrust bearing and, th
Merchant & Gould P.C.
Mindtech Corporation
Nguyen Hoang
LandOfFree
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