Rotating compressor bearing with dual taper

Details Rotating compressor bearing with dual taper Rotating compressor bearing with dual taper

1999-05-10

2001-01-02

Vrablik, John J. (Department: 3748)

Rotary expansible chamber devices

Working member has planetary or planetating movement

Helical working member, e.g., scroll

C384S192000

Utility Patent

active

06168403

ABSTRACT:

BACKGROUND OF THE INVENTION
This invention relates to improvements in a rotating compressor shaft to support the shaft when it becomes misaligned.
Compressors typically have an electric motor or other means driving a shaft. The shaft, in turn, drives a compressor pump unit. Other rotating devices will also utilize this basic construction to drive a rotating device.
In many such applications the shaft becomes misaligned. The shaft is supported in a series of bearings in most applications. When the shaft becomes misaligned, it abuts surfaces of the various bearings at line contact points. This will result in wear on the bearing or shaft. Also, high loads are applied to those surfaces. This is undesirable.
One specific type of compressor which has this problem is a scroll compressor. A scroll compressor
20
is shown in
FIG. 1
including a pump unit
22
. A shaft
30
drives an orbiting scroll
26
. The orbiting scroll member orbits relative to a second scroll
24
. The two scrolls each have a base with a generally spiral wrap extending from the base. The orbiting scroll
26
is driven by motor
36
to orbit relative to the other scroll
24
, and compression chambers are reduced in size as this orbiting movement occurs. This compresses an entrapped fluid.
An eccentric
28
is driven by shaft
30
to cause the orbiting scroll
26
to orbit. A crank case housing
32
supports the orbiting scroll
26
and the shaft
30
. A shaft bearing
34
is received in the crank case
32
.
A force generated by the entrapped fluid is applied to orbiting scroll
26
which transfers the force through a bearing
27
to eccentric
28
. The shaft
30
will deflect in the direction of the force, both by moving through the clearance in bearing
34
, and by flexing or bending elastically in response to the force. Thus, once a scroll compressor is loaded, the shaft becomes misaligned.
As shown in
FIG. 2
, the shaft
30
becomes misaligned within the bearing
34
. When this occurs, there is line contact at points
38
and
40
at the extreme ends of the bearing. This line contact is undesirable, and may result in bearing or shaft damage.
SUMMARY OF THE INVENTION
In a disclosed embodiment of this invention, a shaft for a rotating machine has a pair of tapered surfaces extending above and below a transition surface. The tapered surfaces are positioned on the shaft such that they will move into contact with bearing surfaces when the shaft is misaligned. The tapered surfaces are thus designed to come into contact with the bearing when the shaft is misaligned. One tapered surface contacts one end of the bearing and the other tapered surface contacts the other end of the bearing. The two tapered surfaces provide contact area, rather than line contact, between the bearing and shaft.
In one preferred embodiment, the tapered surface that is closer to the driven member is longer than the tapered surface spaced from the driven member. The tapered surfaces have generally equal angles of taper such that when one abuts one side of the bearing, the other will be abutting the other side of the bearing.
In another embodiment of this invention, the transition surface actually includes a pair of curved surfaces (i.e., of varying taper) of different radius. Preferably, the transition surfaces extend sufficiently relative to the tapered surfaces such that those surfaces do provide support in the bearing before misalignment occurs.
The above disclosed invention is particularly advantageous in a scroll compressor. A scroll compressor will have its shaft somewhat misaligned once the compressor is fully loaded and thus benefits from this design.


REFERENCES:
patent: 5222881 (1993-06-01), Sano et al.
patent: 5531577 (1996-07-01), Hayase et al.
patent: 107213 (1927-09-01), None
Translation of Austria Patent 107,213 dated Sep. 1927, copy in 384/192.*

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