BACKGROUND OF THE INVENTION
1. FIELD OF THE INVENTION
The present invention relates to scroll compressors for
use in, for example, air conditioners and refrigerators, and
particularly to a scroll compressor having a pin-and-ring
rotation-preventing mechanism.
2. DESCRIPTION OF RELATED ART
A scroll compressor having a pin-and-ring rotation-
preventing mechanism is disclosed in, for example, Japanese
Unexamined Patent Application, Publication No. 5-321850.
This type of scroll compressor undesirably exhibits
decreased compression performance as a result of increased
compression leakage due to improper engagement between gear
surfaces of an orbiting scroll and a fixed scroll if a
theoretical orbiting radius ρth defined by the scrolls (the
engagement between the gear surfaces of the orbiting scroll
and the fixed scroll) is larger than an orbiting radius ρpin
defined by pins and rings.
The scroll compressor also exhibits decreased compression
performance as a result of increased compression leakage due
to twisting of the orbiting scroll (rotation relative to the
fixed scroll) if the orbiting radius ρpin defined by the pins
and the rings is larger than the theoretical orbiting radius

ρth defined by the scrolls.
BRIEF SUMMARY OF THE INVENTION
In light of the circumstances described above, an object
of the present invention is to provide a scroll compressor
that can achieve excellent engagement between gear surfaces of
fixed and orbiting scrolls and minimize compression leakage to
avoid a decrease in compression performance.
To achieve the above object, the present invention
provides the following solutions.
A scroll compressor according to the present invention
includes an orbiting scroll engaged with a front case by pins
and rings or ring holes to prevent rotation of the orbiting
scroll. The rings or the ring holes have such an inside
diameter that an orbiting radius defined by the pins and the
rings or the ring holes is larger than a theoretical orbiting
radius defined by engagement between gear surfaces of a fixed
scroll and the orbiting scroll. The pins, the rings, or the
ring holes are shifted in such a direction as to relieve
twisting of the orbiting scroll relative to the fixed scroll.
This scroll compressor can prevent engagement failure
between the gear surfaces of the fixed scroll and the orbiting
scroll because the orbiting radius is larger than the
theoretical orbiting radius.
The scroll compressor can also minimize twisting of the

orbiting scroll (rotation relative to the fixed scroll)
because the pins, the rings, or the ring holes are shifted in
such a direction as to relieve the twisting of the orbiting
scroll relative to the fixed scroll.
The scroll compressor can thus provide increased ease of
assembly and minimize compression leakage to avoid a decrease
in compression performance.
Another scroll compressor according to the present
invention includes an orbiting scroll engaged with a front
case by pins disposed on an outer end surface of the orbiting
scroll and rings or ring holes disposed on an inner end
surface of the front case to prevent rotation of the orbiting
scroll. The rings or the ring holes have such an inside
diameter that an orbiting radius defined by the pins and the
rings or the ring holes is larger than a theoretical orbiting
radius defined by engagement between gear surfaces of a fixed
scroll and the orbiting scroll. The pins are shifted in such
a direction as to relieve twisting of the orbiting scroll
relative to the fixed scroll.
This scroll compressor can prevent engagement failure
between the gear surfaces of the fixed scroll and the orbiting
scroll because the orbiting radius is larger than the
theoretical orbiting radius.
The scroll compressor can also minimize twisting of the
orbiting scroll (rotation relative to the fixed scroll)

because the pins are shifted in such a direction as to relieve
the twisting of the orbiting scroll relative to the fixed
scroll, that is, in the same direction as a direction in which
the orbiting scroll orbits.
The scroll compressor can thus provide increased ease of
assembly and minimize compression leakage to avoid a decrease
in compression performance.
Another scroll compressor according to the present
invention includes an orbiting scroll engaged with a front
case by pins disposed on an outer end surface of the orbiting
scroll and rings or ring holes disposed on an inner end
surface of the front case to prevent rotation of the orbiting
scroll. The rings or the ring holes have such an inside
diameter that an orbiting radius defined by the pins and the
rings or the ring holes is larger than a theoretical orbiting
radius defined by engagement between gear surfaces of a fixed
scroll and the orbiting scroll. The rings or the ring holes
are shifted in such a direction as to relieve twisting of the
orbiting scroll relative to the fixed scroll.
This scroll compressor can prevent engagement failure
between the gear surfaces of the fixed scroll and the orbiting
scroll because the orbiting radius is larger than the
theoretical orbiting radius.
The scroll compressor can also minimize twisting of the
orbiting scroll (rotation relative to the fixed scroll)

because the rings or the ring holes are shifted in such a
direction as to relieve the twisting of the orbiting scroll
relative to the fixed scroll, that is, in the direction
opposite to a direction in which the orbiting scroll orbits.
The scroll compressor can thus provide increased ease of
assembly and minimize compression leakage to avoid a decrease
in compression performance.
Another scroll compressor according to the present
invention includes an orbiting scroll engaged with a front
case by rings or ring holes disposed on an outer end surface
of the orbiting scroll and pins disposed on an inner end
surface of the front case to prevent rotation of the orbiting
scroll. The rings or the ring holes have such an inside
diameter that an orbiting radius defined by the pins and the
rings or the ring holes is larger than a theoretical orbiting
radius defined by engagement between gear surfaces of a fixed
scroll and the orbiting scroll. The pins are shifted in such
a direction as to relieve twisting of the orbiting scroll
relative to the fixed scroll.
This scroll compressor can prevent engagement failure
between the gear surfaces of the fixed scroll and the orbiting
scroll because the orbiting radius is larger than the
theoretical orbiting radius.
The scroll compressor can also minimize twisting of the
orbiting scroll (rotation relative to the fixed scroll)

because the pins are shifted in such a direction as to relieve
the twisting of the orbiting scroll relative to the fixed
scroll, that is, in the direction opposite to a direction in
which the orbiting scroll orbits.
The scroll compressor can thus provide increased ease of
assembly and minimize compression leakage to avoid a decrease
in compression performance.
Another scroll compressor according to the present
invention includes an orbiting scroll engaged with a front
case by rings or ring holes disposed on an outer end surface
of the orbiting scroll and pins disposed on an inner end
surface of the front case to prevent rotation of the orbiting
scroll. The rings or the ring holes have such an inside
diameter that an orbiting radius defined by the pins and the
rings or the ring holes is larger than a theoretical orbiting
radius defined by engagement between gear surfaces of a fixed
scroll and the orbiting scroll. The rings or the ring holes
are shifted in such a direction as to relieve twisting of the
orbiting scroll relative to the fixed scroll.
This scroll compressor can prevent engagement failure
between the gear surfaces of the fixed scroll and the orbiting
scroll because the orbiting radius is larger than the
theoretical orbiting radius.
The scroll compressor can also minimize twisting of the
orbiting scroll (rotation relative to the fixed scroll)

because the rings or the ring holes are shifted in such a
direction as to relieve the twisting of the orbiting scroll
relative to the fixed scroll, that is, in the same direction
as a direction in which the orbiting scroll orbits.
The scroll compressor can thus provide increased ease of
assembly and minimize compression leakage to avoid a decrease
in compression performance.
In the scroll compressors described above, the pins, the
rings, or the ring holes are preferably shifted
circumferentially in a direction that is the same as or
opposite to the direction in which the orbiting scroll orbits.
Such scroll compressors can minimize twisting of the
orbiting scroll relative to the fixed scroll to minimize
compression leakage and thus a decrease in compression
performance.
In the scroll compressors described above, the pins, the
rings, or the ring holes are preferably shifted along a
tangent to a circle passing through the pins, the rings, or
the ring holes in a direction that is the same as or opposite
to the direction in which the orbiting scroll orbits.
Such scroll compressors can achieve increased ease of
processing and reduced production costs.
Another scroll compressor according to the present
invention includes orbiting scroll pins disposed on an outer
end surface of an orbiting scroll and front case pins disposed

on an inner end surface of a front case. The orbiting scroll
pins and the front case pins extend in opposite directions and
are engaged with inner circumferential surfaces of common
rings to prevent rotation of the orbiting scroll. The rings
have such an inside diameter that an orbiting radius defined
by the orbiting scroll pins, the front case pins, and the
rings is larger than a theoretical orbiting radius defined by
engagement between gear surfaces of a fixed scroll and the
orbiting scroll. The orbiting scroll pins and the front case
pins are shifted in such a direction as to relieve twisting of
the orbiting scroll relative to the fixed scroll.
As described above, the present invention can also be
applied to a scroll compressor including pins protruding from
an orbiting scroll and pins protruding from a front case which
are engaged with inner circumferential surfaces of rings to
prevent rotation of the orbiting scroll.
The scroll compressors according to the present invention
have the advantage of achieving excellent engagement between
gear surfaces of fixed and orbiting scrolls and minimizing
compression leakage to avoid a decrease in compression
performance.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE ACCOMPANYING DRAWINGS
Fig. 1 is a sectional view of a scroll compressor
according to a first embodiment of the present invention;

Fig. 2 is a view of the scroll compressor in a direction
indicated by arrow A of Fig. 1, showing the relationship
between rings disposed on an inner end surface of a front case
and pins disposed on an outer end surface of an orbiting
scroll;
Fig. 3 is a view, similar to Fig. 2, of a scroll
compressor according to a second embodiment of the present
invention;
Fig. 4 is a view, similar to Fig. 2, of a scroll
compressor according to a third embodiment of the present
invention;
Fig. 5 is a view, similar to Fig. 2, of a scroll
compressor according to a fourth embodiment of the present
invention;
Fig. 6 is a diagram showing a direction in which pins or
rings and ring holes are shifted;
Fig. 7 is a diagram showing a direction in which pins or
rings and ring holes are shifted;
Fig. 8 is a partial sectional view of an end plate of an
orbiting scroll and its vicinity; and
Fig. 9 is a sectional view taken along arrow a-a of Fig.
8.
DETAILED DESCRIPTION OF THE INVENTION
A scroll compressor according to a first embodiment of

the present invention will now be described with reference to
Figs. 1 and 2. Fig. 1 is a sectional view of the scroll
compressor according to this embodiment. Fig. 2 is a view of
the scroll compressor in a direction indicated by arrow A of
Fig. 1, showing the relationship between rings disposed on an
inner end surface of a front case and pins disposed on an
outer end surface of an orbiting scroll.
In Fig. 1, a scroll compressor 1 includes a fixed scroll
2 fixed to a housing 7 with bolts 12 and an orbiting scroll 3
that orbits without rotating relative to the fixed scroll 2 to
compress, for example, a refrigerant.
A front case 6 is fixed to the housing 7 on the outer
side of the orbiting scroll 3 (on the left in Fig. 1) to
receive a thrust force from the orbiting scroll 3. The front
case 6 has ring holes 4 (four ring holes 4 arranged every 90°
circumferentially in this embodiment) in an inner end surface
of the front case 6 (a substantially annular surface in
contact with an outer end surface of the orbiting scroll 3)
and rings 11 press-fitted or loosely fitted into the ring
holes 4.
Pins 5 protruding from the outer end surface of the
orbiting scroll 3 (the surface in contact with the inner end
surface of the front case 6) are loosely inserted into the
corresponding rings 11. The number of pins 5 corresponds to
the number of ring holes 4 (four pins 5 in this embodiment).

A crank chamber 10 is defined in the center of the inner side
of the front case 6 to accommodate an eccentric shaft 9 and a
balance weight 8.
The orbiting scroll 3 engages with the front case 6 via
the pins 5 loosely inserted into the rings 11 so as not to
rotate while being made to orbit by the eccentric shaft 9.
The pins 5 orbit along inner circumferential surfaces of the
rings 11 in the same direction as the orbiting scroll 3 does.
In this embodiment, as shown in Fig. 2, the rings 11 and
the ring holes 4 have such inside diameters that an orbiting
radius ρpin defined by the rings 11 and the pins 5 is slightly
larger than a theoretical orbiting radius ρth defined by the
scrolls 2 and 3 (engagement between gear surfaces of the
orbiting scroll 3 and the fixed scroll 2) by a length of, for
example, 0.05 to 0.2 mm. In addition, the pins 5 are slightly
shifted in a direction opposite to the direction indicated in
Fig. 6, that is, circumferentially (along an arc) in the same
direction as the direction in which the orbiting scroll 3
orbits, by a distance of, for example, 0.05 to 0.2 mm.
The scroll compressor 1 according to this embodiment can
prevent engagement failure between the gear surfaces of the
fixed scroll 2 and the orbiting scroll 3 because the orbiting
radius ρpin is larger than the theoretical orbiting radius ρth.
The scroll compressor 1 can also minimize twisting of the
orbiting scroll 3 (rotation relative to the fixed scroll 2)

because the pins 5 are slightly shifted circumferentially
(along an arc) in the same direction as the direction in which
the orbiting scroll 3 orbits.
The scroll compressor 1 can thus provide increased ease
of assembly and minimize compression leakage to avoid a
decrease in compression performance.
A scroll compressor according to a second embodiment of
the present invention will be described with reference to Fig.
3, wherein the same reference numerals as used in the first
embodiment indicate the same components. A scroll compressor
20 shown in Fig. 3 according to this embodiment differs from
the scroll compressor 1 according to the first embodiment as
follows. In Fig. 3, the rings 11 and the ring holes 4 have
such inside diameters that the orbiting radius ρpin defined by
the rings 11 and the pins 5 is slightly larger than the
theoretical orbiting radius ρth defined by the scrolls 2 and 3
(the engagement between the gear surfaces of the orbiting
scroll 3 and the fixed scroll 2) by a length of, for example,
0.05 to 0.2 mm. In addition, the rings 11 and the ring holes
4 are slightly shifted in the direction indicated in Fig. 6,
that is, circumferentially (along an arc) in the direction
opposite to the direction in which the orbiting scroll 3
orbits, by a distance of, for example, 0.05 to 0.2 mm. The
other components are the same as used in the first embodiment
and will not be described herein.

The scroll compressor 20 according to this embodiment can
prevent engagement failure between the gear surfaces of the
fixed scroll 2 and the orbiting scroll 3 because the orbiting
radius ρpin is larger than the theoretical orbiting radius ρth.
The scroll compressor 20 can also minimize twisting of
the orbiting scroll 3 (rotation relative to the fixed scroll
2) because the rings 11 and the ring holes 4 are slightly
shifted circumferentially (along an arc) in the direction
opposite to the direction in which the orbiting scroll 3
orbits.
The scroll compressor 20 can thus provide increased ease
of assembly and minimize compression leakage to avoid a
decrease in compression performance.
A scroll compressor according to a third embodiment of
the present invention will be described with reference to Fig.
4, wherein the same reference numerals as used in the previous
embodiments indicate the same components. A scroll compressor
30 shown in Fig. 4 according to this embodiment differs from
those according to the previous embodiments as follows. In
Fig. 4, the scroll compressor 30 has the pins 5 on the inner
end surface of the front case 6 and the rings 11 and the ring
holes 4 on the outer end surface of the orbiting scroll 3.
The rings 11 and the ring holes 4 have such inside diameters
that the orbiting radius ρpin defined by the rings 11 and the
pins 5 is slightly larger than the theoretical orbiting radius

ρth defined by the scrolls 2 and 3 (the engagement between the
gear surfaces of the orbiting scroll 3 and the fixed scroll 2)
by a length of, for example, 0.05 to 0.2 mm. In addition, the
pins 5 are slightly shifted in the direction indicated in Fig.
6, that is, circumferentially (along an arc) in the direction
opposite to the direction in which the orbiting scroll 3
orbits, by a distance of, for example, 0.05 to 0.2 mm. The
other components are the same as used in the previous
embodiments and will not be described herein.
The scroll compressor 30 according to this embodiment can
prevent engagement failure between the gear surfaces of the
fixed scroll 2 and the orbiting scroll 3 because the orbiting
radius Vin is larger than the theoretical orbiting radius ρth.
The scroll compressor 30 can also minimize twisting of
the orbiting scroll 3 (rotation relative to the fixed scroll
2) because the pins 5 are slightly shifted circumferentially
(along an arc) in the direction opposite to the direction in
which the orbiting scroll 3 orbits.
The scroll compressor 30 can thus provide increased ease
of assembly and minimize compression leakage to avoid a
decrease in compression performance.
A scroll compressor according to a fourth embodiment of
the present invention will be described with reference to Fig.
5, wherein the same reference numerals as used in the first
and second embodiments indicate the same components. A scroll

compressor 40 shown in Fig. 5 according to this embodiment
differs from those according to the first and second
embodiments as follows. In Fig. 5, the scroll compressor 40
has the pins 5 on the inner end surface of the front case 6
and the rings 11 and the ring holes 4 on the outer end surface
of the orbiting scroll 3. The rings 11 and the ring holes 4
have such inside diameters that the orbiting radius ρpin
defined by the rings 11 and the pins 5 is slightly larger than
the theoretical orbiting radius ρth defined by the scrolls 2
and 3 (the engagement between the gear surfaces of the
orbiting scroll 3 and the fixed scroll 2) by a length of, for
example, 0.05 to 0.2 mm. In addition, the rings 11 and the
ring holes 4 are slightly shifted in the direction opposite to
the direction indicated in Fig. 6, that is, circumferentially
(along an arc) in the same direction as the direction in which
the orbiting scroll 3 orbits, by a distance of, for example,
0.05 to 0.2 mm. The other components are the same as used in
the first and second embodiments and will not be described
herein.
The scroll compressor 40 according to this embodiment can
prevent engagement failure between the gear surfaces of the
fixed scroll 2 and the orbiting scroll 3 because the orbiting
radius ρpin is larger than the theoretical orbiting radius ρth.
The scroll compressor 40 can also minimize twisting of
the orbiting scroll 3 (rotation relative to the fixed scroll

2) because the rings 11 and the ring holes 4 are slightly
shifted circumferentially (along an arc) in the same direction
as the direction in which the orbiting scroll 3 orbits.
The scroll compressor 40 can thus provide increased ease
of assembly and minimize compression leakage to avoid a
decrease in compression performance.
The pins 5 or the rings 11 and the ring holes 4 do not
necessarily have to be shifted in the direction that is the
same as or opposite to the direction indicated in Fig. 6, that
is, circumferentially at the same radius in the direction that
is the same as or opposite to the direction in which the
orbiting scroll 3 orbits. For example, the pins 5 or the
rings 11 and the ring holes 4 may be shifted in a direction
that is the same as or opposite to the direction indicated in
Fig. 7, that is, linearly (along a tangent to a circle passing
through the pins 5, the rings 11, or the ring holes 4) in the
direction that is the same as or opposite to the direction in
which the orbiting scroll 3 orbits.
If the pins 5 or the rings 11 and the ring holes 4 are
shifted as shown in Fig. 7, increased ease of processing and
reduced production costs can be achieved.
Either the pins 5 or the rings 11 and the ring holes 4
are shifted in the embodiments described above. However, the
present invention is not limited to these embodiments; both
the pins 5 and the rings 11 and the ring holes 4 may be

shifted.
The four pins 5, the four rings 11, and the four ring
holes 4 are provided in the embodiments described above.
However, the present invention is not limited to these
embodiments; at least three pins 5, at least three rings 11,
and at least three ring holes 4 may be provided (for example,
five or six) .
The rings 11 are press-fitted or loosely fitted into the
ring holes 4 in the embodiments described above. However, the
present invention is not limited to these embodiments; it may
also be applied to the case where the rings 11 are not
provided in the ring holes 4, that is, where the pins 5 orbit
along the inner circumferential surfaces of the ring holes 4
or the ring holes 4 orbit along the outer circumferential
surfaces of the pins 5.
The present invention may also be applied to a scroll
compressor having a rotation-preventing mechanism shown in
Figs. 8 and 9.
Fig. 8 is a partial sectional view of an end plate of the
orbiting scroll 3 and its vicinity. Orbiting scroll pins 21
(one of them is shown in Fig. 8) protrude from the outer side
of the orbiting scroll 3 while front case pins 22 (one of them
is shown in Fig. 8) protrude from the inner side of a wall
portion of the front case 6. The orbiting scroll pins 21 and
the front case pins 22 extend in opposite directions.

Rings 24 (one of them is shown in Fig. 8) corresponding
to the pins 21 and 22 are disposed between the end plate of
the orbiting scroll 3 and the front case 6. Each of the rings
24 has one corresponding pair of pins 21 and 22 engaged with
the inner circumferential surface thereof (see Fig. 9).
The inside diameter of the rings 24 is determined so that
the orbiting radius defined by the rings 24 and the
corresponding pairs of pins 21 and 22 is larger than the
theoretical orbiting radius defined by the engagement between
the gear surfaces of the fixed scroll 2 and the orbiting
scroll 3. This prevents engagement failure between the gear
surfaces of the fixed scroll 2 and the orbiting scroll 3.
In addition, the pins 21 and 22 are shifted in such a
direction as to relieve twisting of the orbiting scroll 3
(rotation relative to the fixed scroll 2), thus minimizing the
twisting of the orbiting scroll 3.

We Claim:
1. A scroll compressor comprising:
a fixed scroll;
a front case having inner circumferential surfaces disposed in an inner end surface of the front
case;
an orbiting scroll engaged with the front case and configured to orbit the fixed scroll by
operation of a driving member;
a single pin paired with each one of the inner circumferential surfaces, the single pin engaging
the orbiting scroll via the paired circumferential surface of the front case, the paired pins and
inner circumferential surfaces configured to prevent rotation of the orbiting scroll;
wherein
an orbiting radius, defined by the pins and the inner circumferential surfaces, is larger than a
theoretical orbiting radius defined by engagement between gear surfaces of the fixed scroll and
the orbiting scroll; and
wherein the pins or the inner circumferential surfaces are shifted in a direction as to relieve
twisting of the orbiting scroll relative to the fixed scroll.
2. A scroll compressor as claimed in claim 1, wherein
the said front case is fixed to the fixed scroll;
pins are disposed on an outer end surface of the orbiting scroll such that a single pin and one
of the inner circumferential surfaces forms a pair,
a plurality of pairs of single pins and inner circumferential surfaces engage the orbiting scroll
with the front case to prevent rotation of the orbiting scroll; and
wherein
the inner circumferential surfaces have an inside diameter.

3. A scroll compressor as claimed in claim 2, wherein
each of the pins, disposed on an outer end surface of the orbiting scroll, is paired with a
different one of the inner circumferential surfaces;
each said pin and the inner circumferential surface engaging the orbiting scroll with the front
case;
the pairs of pins and inner circumferential surfaces being configured to prevent rotation of the
orbiting scroll; and
the inner circumferential surfaces being shifted in a direction as to relieve twisting of the
orbiting scroll relative to the fixed scroll.
4. A scroll compressor as claimed in claim 1, wherein
pins are disposed on an inner end surface of the front case,and
inner circumferential surfaces are disposed on an outer end surface of the orbiting scroll
so that each of the pins is associated with a different one of the inner circumferential surfaces,
forming a pair of a single pin and a single inner circumferential surface, and the pairs of pins
and the inner circumferential surfaces engage the orbiting scroll with the front case.
5. A scroll compressor as claimed in claim 4, wherein
each of the inner circumferential surfaces is paired with a different one of the pins, so that
the pairs of pins and inner circumferential surfaces engage the orbiting scroll with the front
case to prevent rotation of the orbiting scroll.
6. The scroll compressor as claimed in any of Claims 1 to 5, wherein
the pins or the inner circumferential surfaces are shifted circumferentially in a direction that is
the same as, or opposite to, a direction in which the orbiting scroll orbits.

7. The scroll compressor as claimed in any of claims 1 to 5, wherein
the pins or the inner circumferential surfaces are shifted along a tangent to a circle passing
through the pins or the inner circumferential surfaces in a direction that is the same as, or
opposite to, a direction in which the orbiting scroll orbits.
8. The scroll compressor as claimed in Claim 1,
wherein the pins or the inner circumferential surfaces are shifted in such a direction that the pins
or the inner circumferential surfaces are shifted circumferentially or tangentially in a direction
that is the same as, or opposite to, a direction in which the orbiting scroll orbits so as to relieve
twisting of the orbiting scroll relative to the fixed scroll.
9. The scroll compressor as claimed in Claim 2,
wherein the pins are shifted in such a direction that the pins are shifted circumferentially or
tangentially in a direction that is the same as, or opposite to, a direction in which the orbiting
scroll orbits so as to relieve twisting of the orbiting scroll relative to the fixed scroll.
10. The scroll compressor as claimed in Claim 3,
wherein the inner circumferential surfaces are shifted in such a direction that the inner
circumferential surfaces are shifted circumferentially or tangentially in a direction that is the
same as, or opposite to, a direction in which the orbiting scroll orbits so as to relieve twisting of
the orbiting scroll relative to the fixed scroll.

11. The scroll compressor as claimed in Claim 4,
wherein the pins are shifted in such a direction that the pins are shifted circumferentially or
tangentially in a direction that is the same as, or opposite to, a direction in which the orbiting
scroll orbits so as to relieve twisting of the orbiting scroll relative to the fixed scroll.

ABSTRACT OF THE DISCLOSURE

TITLE : A SCROLL COMPRESSOR HAVING A PIN-AND-RING ROTATION PREVENTING MECHANISM
A scroll compressor includes an orbiting scroll engaged
with a front case by pins and rings or ring holes to prevent
rotation of the orbiting scroll. The rings or the ring holes
have such an inside diameter that an orbiting radius defined
by the pins and the rings or the ring holes is larger than a
theoretical orbiting radius defined by engagement between gear
surfaces of a fixed scroll and the orbiting scroll. The pins,
the rings, or the ring holes are shifted in such a direction
as to relieve twisting of the orbiting scroll relative to the
fixed scroll.