U.S. patent application number 10/090881 was filed with the patent office on 2002-10-10 for scroll type compressor.
Invention is credited to Asou, Shinsuke, Fujita, Yoshio, Iguchi, Masao, Mori, Tatsushi, Yoshida, Yoshiharu.
Application Number | 20020146340 10/090881 |
Document ID | / |
Family ID | 18919464 |
Filed Date | 2002-10-10 |
United States Patent
Application |
20020146340 |
Kind Code |
A1 |
Mori, Tatsushi ; et
al. |
October 10, 2002 |
Scroll type compressor
Abstract
A scroll type compressor has a fixed scroll member and a movable
scroll member. The fixed scroll member has a fixed scroll base
plate and a fixed scroll wall extending from the fixed scroll base
plate. The movable scroll member has a movable scroll base plate
and a movable scroll wall extending from the movable scroll base
plate. The fixed scroll member and the movable scroll member
cooperatively form a compression region. The movable scroll member
orbits relative to the fixed scroll member to compress refrigerant
in the compression region. Each scroll wall is formed in a taper
shape from each base plate toward each distal end of the scroll
wall. The distal end is non-contact with the opposing scroll base
plate. Clearance between the distal end and the opposing scroll
base plate is less than or equal to the limit clearance value which
maintains airtight performance.
Inventors: |
Mori, Tatsushi; (Kariya-shi,
JP) ; Iguchi, Masao; (Kariya-shi, JP) ; Asou,
Shinsuke; (Kariya-shi, JP) ; Fujita, Yoshio;
(Kariya-shi, JP) ; Yoshida, Yoshiharu;
(Kariya-shi, JP) |
Correspondence
Address: |
MORGAN & FINNEGAN, L.L.P.
345 Park Avenue
New York
NY
10154
US
|
Family ID: |
18919464 |
Appl. No.: |
10/090881 |
Filed: |
March 4, 2002 |
Current U.S.
Class: |
418/55.2 |
Current CPC
Class: |
F04C 18/0269
20130101 |
Class at
Publication: |
418/55.2 |
International
Class: |
F04C 018/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 5, 2001 |
JP |
P2001-059976 |
Claims
What is claimed is:
1. A scroll type compressor comprising: a fixed scroll member
having a fixed scroll base plate and a fixed scroll wall extending
from the fixed scroll base plate; and a movable scroll member
having a movable scroll base plate and a movable scroll wall
extending from the movable scroll base plate, wherein the fixed
scroll member and the movable scroll member cooperatively form a
compression region, and wherein the movable scroll member orbits
relative to the fixed scroll member to compress refrigerant in the
compression region, and wherein each scroll wall is formed in a
taper shape from each base plate toward each distal end of the
scroll wall, the distal end being non-contact with the opposing
scroll base plate, clearance between the distal end and the
opposing scroll base plate being less than or equal to the limit
clearance value which maintains airtight performance between the
distal end and the opposing scroll base plate.
2. The scroll type compressor according to claim 1 wherein the side
surface of the fixed scroll wall and the side surface of the
movable scroll wall, which are facing each other, have an equal
inclination angle with respect to the direction of an axis which is
perpendicular to the base plate.
3. The scroll type compressor according to claim 2 wherein the side
surfaces of the fixed scroll wall and the movable scroll wall have
an equal inclination angle with respect to the direction of the
axis.
4. The scroll type compressor according to claim 1 wherein the
limit clearance value is less than or equal to 60 .mu.m when
circulating oil exists in the compression region.
5. The scroll type compressor according to claim 4 wherein the
limit clearance value is less than or equal to 36 .mu.m.
6. The scroll type compressor according to claim 1 wherein the
limit clearance value is less than or equal to 47 .mu.m when no
circulating oil exists in the compression region.
7. The scroll type compressor according to claim 6 wherein the
limit clearance value is less than or equal to 30 .mu.m.
8. The scroll type compressor according to claim 1 wherein each
scroll wall is formed in a taper shape from each base plate toward
each distal end of the scroll wall by utilizing a draft upon
casting.
9. A scroll fluid machine comprising: a fixed scroll member having
a fixed scroll base plate and a fixed scroll wall extending from
the fixed scroll base plate; and a movable scroll member having a
movable scroll base plate and a movable scroll wall extending from
the movable scroll base plate, wherein the fixed scroll member and
the movable scroll member cooperatively form a compression region,
and wherein the movable scroll member orbits relative to the fixed
scroll member to compress fluid in the compression region, and
wherein each scroll wall is formed in a taper shape from each base
plate toward each distal end of the scroll wall, the distal end
being non-contact with the opposing scroll base plate, clearance
between the distal end and the opposing scroll base plate being
less than or equal to the limit clearance value which maintains
airtight performance between the distal end and the opposing scroll
base plate.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a scroll type compressor
and more particularly to structure of a fixed scroll member and a
movable scroll member which constitute a compression mechanism in a
volute shape.
[0002] In general, the scroll type compressor has a housing in
which the fixed scroll member and the movable scroll member are
provided. The fixed scroll member has a fixed scroll base plate and
a fixed scroll wall that extends from the fixed scroll base plate.
The movable scroll member has a movable scroll base plate and a
movable scroll wall that extends from the movable scroll base
plate. Each scroll wall is engaged with each other. The fixed
scroll member and the movable scroll member cooperatively form a
plurality of compression chambers as a compression region. As the
movable scroll member orbits about an axis of the fixed scroll
member, the compression chambers move radially inward while their
volume decreases.
[0003] Since bending moment is applied to each scroll wall by high
pressure generated in the compression chambers due to the
compression performance, the bending moment deforms each scroll
wall. Therefore, clearance between the scroll walls is increased
and compressed fluid leaks through the clearance.
[0004] Accordingly, high compression performance is not
obtained.
[0005] To obtain the high compression performance by preventing the
compressed fluid from leaking, as shown in FIG. 4A, a scroll wall 1
was conventionally created in a taper shape from a joining portion
to a base plate 2 toward a distal end of the scroll wall 1.
[0006] Still referring to FIG. 4A, in the above constitution, the
scroll wall 1 is strengthened against bending moment. Therefore,
clearance between the scroll walls 1 was effectively restrained
from increasing. There, such a constitution was employed that a tip
seal 3 slides the surface of the opposing base plate 2 to ensure
sealing performance in the clearance between the distal end of the
scroll wall 1 and the opposing base plate 2.
[0007] However, as it is taken into consideration that the
compressor used in high speed vehicles is nowadays required to be
compact and lightweight for its fuel efficiency, the following
problem has occurred in the above prior art. The thickness of the
scroll wall 1 is increased when the tip seal 3 is used. As a
result, configuration of the compressor is increased in size.
[0008] As shown in FIG. 4A, when the distal end of the scroll wall
1 is provided with the tip seal 3, thickness c of the distal end of
the scroll wall 1 is determined as follows. c=a+2*b where width of
the tip seal 3 is expressed by a, and thickness of an outer wall of
a groove formed in the distal end is expressed by b. Thickness of
the portion joining to the scroll wall 1, which is expressed by d,
is also determined to be relatively thick due to increase of the
thickness c.
[0009] On the contrary, as shown in FIG. 4B, when the distal end of
the scroll wall 1 has similar thickness to the width a of the tip
seal 3 in size, thickness e of the portion joining to the base
plate 2 becomes relatively small. Accordingly, the compressor
including the scroll wall 1 shown in FIG. 4A, has less capacity in
the compression chambers than that of FIG. 4B, because of an
increase in thickness of the scroll wall 1 provided with the tip
seal 3. To maintain the capacity in the compression chambers, the
configuration of the compressor is inevitably increased in
size.
SUMMARY OF THE INVENTION
[0010] The present invention addresses a scroll type compressor
which is hard, compact and lightweight with high quality sealing
performance.
[0011] According to the present invention, A scroll type compressor
has a fixed scroll member and a movable scroll member. The fixed
scroll member has a fixed scroll base plate and a fixed scroll wall
extending from the fixed scroll base plate. The movable scroll
member has a movable scroll base plate and a movable scroll wall
extending from the movable scroll base plate. The fixed scroll
member and the movable scroll member cooperatively form a
compression region. The movable scroll member orbits relative to
the fixed scroll member to compress refrigerant in the compression
region. Each scroll wall is formed in a taper shape from each base
plate toward each distal end of the scroll wall. The distal end is
non-contact with the opposing scroll base plate. Clearance between
the distal end and the opposing scroll base plate is less than or
equal to the limit clearance value which maintains airtight
performance between the distal end and the opposing scroll base
plate.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] The features of the present invention that are believed to
be novel are set forth with particularity in the appended claims.
The invention together with objects and advantages thereof, may
best be understood by reference to the following description of the
presently preferred embodiments together with the accompanying
drawings in which:
[0013] FIG. 1 is a diagram in a cross-sectional view illustrating a
first preferred embodiment of the scroll type compressor according
to the present invention;
[0014] FIG. 2 is a diagram in a partial enlarged view illustrating
first and second preferred embodiments of the scroll type
compressor according to the present invention;
[0015] FIG. 3 is a graph illustrating a relation between clearance
in the direction of an axis and a ratio of COP according to the
present invention;
[0016] FIG. 4A is a diagram in a partial cross-sectional view
illustrating a scroll wall with a tip seal according to the prior
art; and
[0017] FIG. 4B is a diagram in a partial cross-sectional view
illustrating a scroll wall without a tip seal according to the
present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0018] A scroll type compressor according to a first preferred
embodiment of the present invention will be described with
reference to FIGS. 1 through 3.
[0019] As shown in FIG. 1, a front housing 30, a center housing 31
and a rear housing 32 are connected to form a configuration of the
compressor. A fixed scroll member 35 is integrally formed with the
center housing 31. The fixed scroll member 35 has a fixed scroll
base plate 33 and a fixed scroll wall 34 that extends from the
fixed scroll base plate 33. An inlet 36 for introducing refrigerant
is also formed in the center housing 31 and is connected to an
external refrigerant circuit. A movable scroll member 39 is
accommodated in a space defined by the center housing 31 and the
front housing 30. The movable scroll member 39 has a movable scroll
base plate 37 and a movable scroll wall 38 that extends from the
movable scroll base plate 37. The fixed scroll wall 34 and the
movable scroll wall 38 engage with each other. Thereby, a plurality
of compression chambers 40 is defined as a compression region
between the fixed scroll member 35 and the movable scroll member
39. A discharge hole 42 is formed substantially at the center of
the fixed scroll base plate 33. Compressed refrigerant in the
compression chambers 40 is discharged into a discharge chamber 41
defined between the center housing 31 and the rear housing 32
through the discharge hole 42. An outlet 43 is formed in the rear
housing 32 to flow refrigerant in the discharge chamber 41 into the
external refrigerant circuit.
[0020] Still referring to FIG. 1, one end of a drive shaft 45 is
rotatably supported in the front housing 30 by bearing 44 and the
other end of the drive shaft 45 extends outside of the
configuration of the compressor. A crankshaft 46 is mounted on one
end of the drive shaft 45. The crankshaft 46 is received by a
bushing 47, which is inserted in a boss 48 of the movable scroll
member 39. A self rotation preventing mechanism 49 prevents the
movable scroll member 39 from rotating about its axis, while
allowing the movable scroll member 39 to orbit about an axis of the
fixed scroll member 35.
[0021] As shown in FIG. 2, the fixed scroll wall 34 and the movable
scroll wall 38 are respectively formed in a taper shape from
portions joining to the scroll base plates 33 and 37 toward the
respective distal ends. The fixed scroll wall 34 has a pair of side
surfaces 34a and 34b which incline by angles of .theta..sub.1 and
.theta..sub.2 with respect to the direction of an axis of the drive
shaft 45 (which is perpendicular to the scroll base plates 33 and
37), respectively. In a similar manner, the movable scroll wall 38
has a pair of side surfaces 38a and 38b which incline by angles of
.theta..sub.3 and .theta..sub.4 with respect to the direction of
the axis of the drive shaft 45 (which is perpendicular to the
scroll base plates 33 and 37), respectively. At this time, the side
surfaces 34b and 38a which face each other are equal in inclination
angle. That is, .theta..sub.2 equals .theta..sub.3. In a similar
manner, the side surfaces 34a and 38b which face each other are
also equal in inclination angle. That is, .theta..sub.1 equals
.theta..sub.4. In addition, when the side surfaces 34a and 34b of
the fixed scroll wall 34 are equal in inclination angle,
.theta..sub.1 equals .theta..sub.2. In a similar manner, when the
side surfaces 38a and 38b of the movable scroll wall 38 are equal
in inclination angle, .theta..sub.3 also equals .theta..sub.4. In
this case, the fixed scroll wall 34 and the movable scroll wall 38
are equal in inclination angle. The above inclination angle is
formed not only by cutting but also by utilizing a draft upon
casting.
[0022] Still referring to FIG. 2, when the compressor is assembled
by engaging the movable scroll member 39 with the fixed scroll
member 35, the distal end of the fixed scroll wall 34 and the
opposing surface of the movable scroll base plate 37 are maintained
to have clearance G.sub.1 therebetween so as not to contact with
each other. In a similar manner, the distal end of the movable
scroll wall 38 and the opposing surface of the fixed scroll base
plate 33 are maintained to have clearance G.sub.2 therebetween so
as not to contact with each other. The clearance G.sub.1 generally
equals the clearance G.sub.2.
[0023] Now, a method for searching the optimal value of the
clearance G.sub.1 and G.sub.2 will be explained with reference to
FIG. 3. In this graph the value of x-axis represents length of
clearance G.sub.1 and G.sub.2 in the direction of the axis
expressed by unit of micrometer or .mu.m and the value of y-axis
represents a ratio of Coefficient of Performance or COP of a
compressor according to the present invention, which is not
provided with the tip seal, to that of a compressor which is
provided with the tip seal. In both cases that oil circulating
inside exists and doesn't exist, relation between the length of
clearance and the ratio of COP is respectively drawn by line graph.
Even in the case that the distal end is provided with the tip seal,
the length of the clearance represents distance between the distal
end of the scroll wall and the opposing surface of the scroll base
plate.
[0024] Still referring to FIG. 3, note that efficiency of load L
which is required due to a heat absorption in an evaporator is
generally expressed by COP as follows. COP=Q.sub.er/L, where
Q.sub.er denotes efficiency of refrigeration.
[0025] In view of total performance of the compressor, the ratio of
COP is allowable if it is more than or equal to 0.9. At this time,
in the case that the oil circulating inside exists, FIG. 3 reads
that the length of the clearance is less than or equal to 60 .mu.m.
In the case that no oil circulating inside exists, FIG. 3 reads
that the length of the clearance is less than or equal to 47 .mu.m.
Accordingly, it is required that the clearance G.sub.1 and G.sub.2
are each less than or equal to the above upper limit value.
[0026] Then, function of the first preferred embodiment will be
explained. As shown in FIG. 1, when the drive shaft 45 that extends
outside of the configuration of the compressor is rotated by
driving force of an external drive source such as a vehicle engine,
which is connected to the drive shaft 45 through a pulley which is
not shown, the movable scroll member 39 orbits about the axis of
the fixed scroll member 35. Refrigerant gas introduced from the
external refrigerant circuit through the inlet 36 is compressed to
be predetermined pressure in the compression chambers 40 and
discharged into the discharge chamber 41 through the discharge hole
42 by the orbital movement. The pressurized refrigerant gas
discharged into the discharge chamber 41 is sent to the external
refrigerant circuit through the outlet 43.
[0027] As shown in FIG. 2 in combination with FIG. 1, during the
above compression process, bending moment is applied to the scroll
walls 34 and 38 due to compression movement in the compression
chambers 40. In this constitution, however, the fixed scroll wall
34 and the movable scroll wall 38 are respectively formed in a
taper shape from the portions joining to the scroll base plates 33
and 37 toward the respective distal ends, while having relatively
sufficient thickness of the portions. Accordingly, the fixed scroll
wall 34 and the movable scroll wall 38 are restrained from being
deformed, thus effectively maintaining a sealing performance
therebetween.
[0028] Still referring to FIG. 2, while the distal ends of the
fixed scroll wall 34 and the movable scroll wall 38 are not in
contact with the respective opposing surfaces of the movable scroll
base plate 37 and the fixed scroll base plate 33, sealing
performance is respectively ensured since the distance therebetween
is less than or equal to the upper limit clearance value which
maintains airtight performance. Thus, total sealing performance in
the compression region is relatively and sufficiently maintained.
Therefore, high compressing performance is obtained. Besides, since
the distal ends of the scroll wall 34 and 38 and the respective
opposing surfaces of the scroll base plates 37 and 33 are prevented
from directly contacting, power loss is also restrained to be
extremely small while the compressor is driven.
[0029] Especially, as shown in FIG. 3 in combination with FIG. 1,
in the case that the oil circulating inside exists when the
clearance in the direction of the axis of the drive shaft 45 is
less than or equal to 36 .mu.m, the ratio of COP is more than or
equal to 1. In a similar manner, in the case that no oil
circulating inside exists when the clearance in the direction of
the axis of the drive shaft 45 is less than or equal to 30 .mu.m,
the ratio of COP is also more than or equal to 1. These mean that
the compressor according to the present invention has superior
efficiency of refrigeration to the compressor provided with the tip
seal when the clearance G.sub.1 and G.sub.2 are less than or equal
to the foregoing upper limit value. This is regarded because the
compressor provided with the tip seal losses power due to sliding
friction generated between the tip seal and the opposing surface of
the scroll base plate. Accordingly, in the above description while
the clearance G.sub.1 and G.sub.2 are less than or equal to 60
.mu.m, more preferably, in the case that the oil circulating inside
exists, the clearance G.sub.1 and G.sub.2 are less than or equal to
36 .mu.m. In a similar manner, while the clearance G.sub.1 and
G.sub.2 are less than or equal to 47 .mu.m, more preferably, in the
case that no oil circulating inside exists, the clearance G.sub.1
and G.sub.2 are less than or equal to 30 .mu.m.
[0030] Referring back to FIG. 2, in this embodiment, since the
distal ends of the scroll walls 34 and 38 are not provided with the
tip seal, while provided in the prior art, the thickness of the
distal ends of the scroll walls 34 and 38 is prevented from
inevitably increasing by providing the tip seal. Accordingly, the
thickness of the scroll wall is determined to be minimized. In
spite of the relatively sufficient thickness of the joint portion,
the configuration of the compressor is not increased in size.
[0031] In this embodiment the following effects are obtained.
Firstly, still referring to FIG. 2, since the scroll walls 34 and
38 are restrained from being deformed to resist to bending moment
by relatively and sufficiently ensuring the thickness of the joint
portions of the scroll walls 34 and 38, sealing performance is
ensured. In addition, sealing performance is also ensured in
clearance between the distal ends of the scroll walls 34 and 38,
and the respective opposing surfaces of the scroll base plates 37
and 33. As a result, total sealing performance in the compression
region is relatively and sufficiently maintained. Thus, high
compressing performance is obtained.
[0032] Secondly, since sealing performance is sufficiently ensured
therebetween while the distal ends of the scroll walls 34 and 38
are not in contact with the respective opposing surfaces of the
scroll base plates 37 and 33, relatively sufficient efficiency of
compression is ensured by the distal ends of the scroll walls 34
and 38 with necessary minimal thickness, and the scroll walls 34
and 38, as a whole, have necessary minimal thickness. Accordingly,
capacity in the compression region is increased, and in its turn,
the compressor is, as a whole, reduced in size and weight.
[0033] Thirdly, the side surface 34a of the scroll wall 34 and the
side surface 38b of the scroll wall 38 facing each other are equal
in inclination angle. Also, the side surface 34b of the scroll wall
34 and the side surface 38 a of the scroll wall 38 facing each
other are equal in inclination angle. Therefore, airtight
constitution in the compression region is easily obtained by a
draft upon casting. In addition, the side surfaces 34 a and 34 b of
the scroll wall 34 are each equal in inclination angle. Also, the
side surfaces 38 a and 38 b of the scroll wall 38 are equal in
inclination angle. Moreover, since these side surfaces 34 a, 34 b,
38 a and 38 b are each set to be equal in inclination angle even
between the scroll members 35 and 39, molding for casting is easily
manufactured.
[0034] Fourthly, since the inclination angles of the side surfaces
34 a, 34 b, 38 a and 38 b of the scroll walls 34 and 38 are formed
by utilizing a draft upon casting, cutting process is not required.
Therefore, person-hour for manufacturing is reduced. In addition,
since casting surface or surface as forged is used in this case,
the compressor which is high in surface hardness and durability is
obtained.
[0035] A scroll type compressor according to a second preferred
embodiment of the present invention will be described with
reference to FIG. 2. In this embodiment, the side surfaces 34 a, 34
b of the scroll wall 34 are different in inclination angle. Also,
the side surfaces 38 a, 38 b of the scroll wall 38 are different in
inclination angle. That is, inclination angles .theta..sub.1,
.theta..sub.2 of the side surfaces 34 a, 34 b of the scroll wall 34
are different from each other. Also, inclination angles
.theta..sub.3, .theta..sub.4 of the side surfaces 38 a, 38 b of the
scroll wall 38 are different from each other. However, the side
surfaces 34 a, 38 b and 34 b, 38 a of the scroll walls 34 and 38
which are facing each other are equal in inclination angle. That
is, the relation between .theta..sub.1, .theta..sub.2,
.theta..sub.3 and .theta..sub.4 is expressed as follows.
.theta..sub.2=.theta..sub.3. .theta..sub.1=.theta..sub.4.
[0036] As described above, side surfaces of a scroll wall are
different in inclination angle. When the scroll member is formed,
for example, by casting, it may be required that the side surfaces
of the scroll wall are different in draft in a casting plan.
Accordingly, inclination angles of the side surfaces predetermined
differently. The other constitution of the second embodiment is
similar to the constitution of the first embodiment, and the
overlapped explanation is omitted.
[0037] As constituted above, since each pair of side surfaces 34 a,
38 b and 34 b, 38 a of the scroll walls 34 and 38 facing each other
is equal in inclination angle even if the side surfaces 34 a, 34 b
and 38 a, 38 b of the scroll walls 34 and 38 are each different in
inclination angle, sealing performance in the compression chambers
40 is ensured. Thus, compression cycle in the compression chambers
40 is performed without obstruction.
[0038] In this embodiment, the above described effects of the first
embodiment are obtained. In addition, the following effect is also
obtained.
[0039] Since it is possible that each side surface of the scroll
wall of the scroll member is different in inclination angle, a
design in a casting plan is relatively freely performed. As a
result, the scroll member is easily manufactured.
[0040] In the present invention, the following embodiment is also
practiced. The scroll type compressor according to the above
embodiments has the drive shaft which protrudes outside of the
configuration of the compressor and is operatively connected to the
external drive source such as an engine. However, the above
external drive source may be built in type or canned motor type.
That is, electric motor for driving the drive shaft may be
installed in the compressor.
[0041] As described above, in the present invention, since
thickness of the joint portion of the scroll wall is larger than
that of the distal end of the scroll wall, the scroll wall is
prevented from being deformed. In addition, sealing performance is
ensured in clearance between the distal end of the scroll wall and
the opposing surface of the scroll base plate. Therefore, airtight
performance in the compression region is, as a whole, maintained.
As a result, high compressing performance is obtained. Moreover,
since the distal end is not provided with the tip seal, the scroll
wall has, as a whole, relatively small thickness. As a result, the
scroll wall becomes compact and lightweight. Thus, various
prominent effects are obtained.
[0042] The present examples and preferred embodiments are to be
considered as illustrative and not restrictive and the invention is
not to be limited to the details given herein but may be modified
within the scope of the appended claims.
* * * * *