U.S. patent application number 13/624008 was filed with the patent office on 2013-03-21 for scroll compressor.
The applicant listed for this patent is Namkyu CHO, Taemin EARMME, Cheolhwan KIM, Byeongchul LEE. Invention is credited to Namkyu CHO, Taemin EARMME, Cheolhwan KIM, Byeongchul LEE.
Application Number | 20130071277 13/624008 |
Document ID | / |
Family ID | 47880827 |
Filed Date | 2013-03-21 |
United States Patent
Application |
20130071277 |
Kind Code |
A1 |
KIM; Cheolhwan ; et
al. |
March 21, 2013 |
SCROLL COMPRESSOR
Abstract
The present disclosure relates to a scroll compressor. According
to the present disclosure, in a shaft penetration scroll compressor
in which an eccentric portion of the rotation shaft is overlapped
with a orbiting wrap of the orbiting scroll in a radial direction,
when a bearing area between the orbiting scroll and the rotation
shaft is A and an end plate area of the orbiting scroll is B, A/B
may be formed in a range of 0.035-0.085, and thus it may be
possible to obtain a sufficient volume ratio and Sommerfeld number
as well as reducing the overall size of the compressor, thereby
reducing a frictional loss and abrasion in the compressor.
Inventors: |
KIM; Cheolhwan; (Seoul,
KR) ; LEE; Byeongchul; (Seoul, KR) ; EARMME;
Taemin; (Seoul, KR) ; CHO; Namkyu; (Seoul,
KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
KIM; Cheolhwan
LEE; Byeongchul
EARMME; Taemin
CHO; Namkyu |
Seoul
Seoul
Seoul
Seoul |
|
KR
KR
KR
KR |
|
|
Family ID: |
47880827 |
Appl. No.: |
13/624008 |
Filed: |
September 21, 2012 |
Current U.S.
Class: |
418/55.2 |
Current CPC
Class: |
F04C 18/0292 20130101;
F04C 23/008 20130101; F04C 29/023 20130101; F04C 18/0269 20130101;
F04C 2240/56 20130101; F04C 18/0253 20130101; F04C 18/0215
20130101; F04C 29/0057 20130101 |
Class at
Publication: |
418/55.2 |
International
Class: |
F04C 18/02 20060101
F04C018/02 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 21, 2011 |
KR |
10-2011-0095471 |
Claims
1. A scroll compressor, comprising: a fixed scroll having a fixed
wrap; a orbiting scroll configured to have a orbiting wrap engaged
with the fixed wrap to form a first and a second compression
chamber at an inner surface and an outer surface thereof, and
perform a orbiting movement against the fixed scroll; a rotation
shaft configured to have an eccentric portion at an end portion
thereof, and combined with the orbiting scroll such that the
eccentric portion is overlapped with the orbiting wrap in a radial
direction; and a driving unit configured to drive the rotation
shaft, wherein when a bearing area between the orbiting scroll and
the rotation shaft is A and an end plate area of the orbiting
scroll is B, A/B is formed in a range of 0.035-0.085.
2. The scroll compressor of claim 1, wherein the first compression
chamber is formed between two contact points (P1, P2) generated
when an inner surface of the fixed wrap and an outer surface of the
orbiting wrap are brought into contact with each other, and when an
angle having a greater value between angles made by two lines
connecting the center (O) of the eccentric portion to the two
contact points (P1, P2), respectively, is .alpha.,
.alpha.<360.degree. at least prior to starting discharge.
3. The scroll compressor of claim 2, wherein when a distance
between perpendiculars at the two contact points (P1, P2) is I,
I>0.
4. The scroll compressor of claim 1, wherein a rotation shaft
combining portion combined with the eccentric portion at an inner
portion thereof is formed at a central portion of the orbiting
scroll, and a protrusion portion is formed at an inner
circumferential surface of an inner end portion of the fixed wrap,
and a concave portion brought into contact with the protrusion
portion to form a compression chamber is formed at an outer
circumferential surface of the rotation shaft combining
portion.
5. The scroll compressor of claim 1, wherein the rotation shaft
comprises: a shaft portion connected to the driving unit; a pin
portion concentrically formed with the shaft portion at an end
portion of the shaft portion; and an eccentric bearing
eccentrically combined with the pin portion to form the eccentric
portion, wherein the eccentric bearing is rotatably combined with
the rotation shaft combining portion.
6. The scroll compressor of claim 5, wherein the pin portion is
formed to have an asymmetric shape based on the center thereof.
7. A scroll compressor, comprising: a fixed scroll having a fixed
wrap; a orbiting scroll configured to have a orbiting wrap engaged
with the fixed wrap to form compression chambers at an inner
surface and an outer surface thereof, respectively, and perform a
orbiting movement against the fixed scroll; a rotation shaft
configured to have an eccentric portion at an end portion thereof,
and combined with the orbiting scroll such that the eccentric
portion is overlapped with the orbiting wrap in a radial direction;
and a driving unit configured to drive the rotation shaft, wherein
a rotation shaft combining portion is formed at the orbiting scroll
to be combined with the rotation shaft, and an eccentric bearing
combined with the rotation shaft combining portion to form the
eccentric portion is combined with the rotation shaft, and a value
of a bearing area between an inner circumferential surface of the
rotation shaft combining portion and an outer circumferential
surface of the eccentric bearing divided by an end plate area of
the orbiting scroll is formed in a range of 0.035-0.085.
8. The scroll compressor of claim 7, wherein the first compression
chamber is formed between two contact points (P1, P2) generated
when an inner surface of the fixed wrap and an outer surface of the
orbiting wrap are brought into contact with each other, and when an
angle having a greater value between angles made by two lines
connecting the center (O) of the eccentric portion to the two
contact points (P1, P2), respectively, is .alpha.,
.alpha.<360.degree. at least prior to starting discharge.
9. The scroll compressor of claim 8, wherein when a distance
between perpendiculars at the two contact points (P1, P2) is I,
I>0.
10. The scroll compressor of claim 7, wherein a rotation shaft
combining portion combined with the eccentric portion at an inner
portion thereof is formed at a central portion of the orbiting
scroll, and a protrusion portion is formed at an inner
circumferential surface of an inner end portion of the fixed wrap,
and a concave portion brought into contact with the protrusion
portion to form a compression chamber is formed at an outer
circumferential surface of the rotation shaft combining portion.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present disclosure relates to subject matter contained
in priority Korean Application No. 10-2011-0095471, filed on Sep.
21, 2011, which is herein expressly incorporated by reference in
its entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present disclosure relates to a scroll compressor.
[0004] 2. Description of the Related Art
[0005] Scroll compressor may include a fixed scroll having a fixed
wrap and a orbiting scroll having a orbiting wrap. The scroll
compressor provides a method of inhaling and compressing
refrigerant through a continuous volume change of the compression
chamber formed between the fixed wrap and the orbiting wrap while
the orbiting scroll performs a orbiting movement on the fixed
scroll.
[0006] Furthermore, the scroll compressor continuously performs
inhalation, compression and discharge, and thus has excellent
characteristics in the aspect of vibration and noise generated
during its operational process compared to other types of
compressors.
[0007] In a scroll compressor, the behavior characteristic is
determined by its type of the fixed wrap and orbiting wrap. The
fixed wrap and orbiting wrap may have an arbitrary shape, but
typically have an involute curved shape that can be easily
processed. The involute curve denotes a curve corresponding to a
trajectory drawn by a cross section of thread when unloosing thread
wound around a base circle having an arbitrary radius. When using
such an involute curve, the capacity change rate is constant
because a thickness of the wrap is constant and thus the number of
turns should be increased to obtain a sufficient level of
compression ratio, but it may also increase the size of the
compressor.
[0008] On the other hand, the orbiting scroll is typically formed
with a disk shaped end plate and the orbiting wrap at the side of
the end plate. Furthermore, a boss to portion is formed at a rear
surface on which the orbiting wrap is not formed and connected to a
rotation shaft for orbiting the orbiting scroll. Such a shape may
form a orbiting wrap over a substantially overall area of the end
plate, thereby decreasing a diameter of the end plate portion for
obtaining the same compression ratio. However, on the contrary, the
operating point to which a repulsive force of refrigerant is
applied and the operating point to which a reaction force for
cancelling out the repulsive force is applied are separated from
each other in an axial direction, thereby causing a problem of
increasing vibration or noise while the orbiting scroll is tilted
during the operational process.
[0009] As a method for solving such problems, there has been
disclosed a so-called shaft penetration scroll compressor which is
a type that a position at which the rotation shaft and the orbiting
scroll are combined with each other is formed on the same surface
as the orbiting wrap. In such a type of compressor, the operating
point of a repulsive force and the operating point of the reaction
force are applied at the same position, thereby solving a problem
that the orbiting scroll is inclined. However, when the rotation
shaft is extended to a orbiting wrap portion in such a manner, an
end portion of the rotation shaft is located at a central portion
of the orbiting wrap, and accordingly, an intentional compression
ratio can be obtained only when increasing the diameter of the end
plate. As a result, it may increase the size of the compressor.
[0010] Typically, in order to apply the compressor to an air
conditioner, a volume ratio (Vr) of suction volume to discharge
volume should be secured to be equal to or greater than 2.0, and a
Sommerfeld number (Sf) capable of predicting the reliability of a
bearing should be secured to be equal to or greater than 0.005.
However, a bearing between the rotation shaft and the orbiting
scroll penetrates a compression portion in a typical shaft
penetration scroll compressor and thus it may be difficult to
secure the volume ratio (Vr) equal to or greater than 2.0 without
increasing the size of the compressor. Even so, when the size of
the bearing is decreased to secure the volume ratio (Vr), the
Sommerfeld number is also reduced, thereby causing a problem that
the reliability of the bearing is decreased while generating a
solid friction.
SUMMARY OF THE INVENTION
[0011] An object of the present disclosure is to provide a scroll
compressor capable of obtaining a sufficient volume ratio and
Sommerfeld number as well as reducing the overall size of the
compressor.
[0012] In order to accomplish the objective of the present
disclosure, there is provided a scroll compressor including a fixed
scroll having a fixed wrap; a orbiting scroll configured to have a
orbiting wrap engaged with the fixed wrap to form a first and a
second compression chamber at an inner surface and an outer surface
thereof, and perform a orbiting movement against the fixed scroll;
a rotation shaft configured to have an eccentric portion at an end
portion thereof, and combined with the orbiting scroll such that
the eccentric portion is overlapped with the orbiting wrap in a
radial direction; and a driving unit configured to drive the
rotation shaft, wherein when a bearing area between the orbiting
scroll and the rotation shaft is A and an end plate area of the
orbiting scroll is B, NB is formed in a range of 0.035-0.085.
[0013] Furthermore, there is provided a scroll compressor including
a fixed scroll having a fixed wrap; a orbiting scroll configured to
have a orbiting wrap engaged with the fixed wrap to form
compression chambers at an inner surface and an outer surface
thereof, respectively, and perform a orbiting movement against the
fixed scroll; a rotation shaft configured to have an eccentric
portion at an end portion thereof, and combined with the orbiting
scroll such that the eccentric portion is overlapped with the
orbiting wrap in a radial direction; and a driving unit configured
to drive the rotation shaft, wherein a rotation shaft combining
portion is formed at the orbiting scroll to be combined with the
rotation shaft, and an eccentric bearing combined with the rotation
shaft combining portion to form the eccentric portion is combined
with the rotation shaft, and a value of a bearing area between an
inner circumferential surface of the rotation shaft combining
portion and an outer circumferential surface of the eccentric
bearing divided by an end plate area of the orbiting scroll is
formed in a range of 0.035-0.085.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The accompanying drawings, which are included to provide a
further understanding of the invention and are incorporated in and
constitute a part of this specification, illustrate embodiments of
the invention and together with the description serve to explain
the principles of the invention.
[0015] In the drawings:
[0016] FIG. 1 is a cross-sectional view schematically illustrating
the internal structure of a scroll compressor according to an
embodiment of the present disclosure;
[0017] FIG. 2 is a partial cross-sectional view illustrating a
compression unit in the embodiment illustrated in FIG. 1;
[0018] FIG. 3 is an exploded perspective view illustrating a
compression unit illustrated in FIG. 2;
[0019] FIG. 4 is a plan view illustrating a first and a second
compression chamber immediately subsequent to inhalation and
immediately prior to discharge in a scroll compressor having a
orbiting wrap and a fixed wrap with an involute shape;
[0020] FIG. 5 is a plan view illustrating a type of orbiting wrap
in a scroll compressor having a orbiting wrap and a fixed wrap with
another involute shape;
[0021] FIG. 6 is a plan view illustrating a orbiting wrap and a
fixed wrap obtained by another envelope line;
[0022] FIG. 7 is an enlarged plan view illustrating a central
portion thereof in FIG. 6;
[0023] FIG. 8 is a plan view illustrating a configuration in which
the orbiting wrap is located prior to 150.degree. starting
discharge in the embodiment illustrated in FIG. 6;
[0024] FIG. 9 is a plan view illustrating a time point at which
discharge is started from the second compression chamber in the
embodiment illustrated in FIG. 6;
[0025] FIG. 10 is a schematic view illustrating a bearing area and
an end plate area shown in a distinguished manner in the present
embodiment; and
[0026] FIG. 11 is a graph illustrating a relation between a ratio
of a bearing area divided by an end plate area, a volume ratio and
a Sommerfeld number in the embodiment illustrated in FIG. 10.
DETAILED DESCRIPTION OF THE INVENTION
[0027] Hereinafter, a scroll compressor according to the present
disclosure will be described in detail based on an embodiment
illustrated in the accompanying drawings.
[0028] Referring to FIG. 1, a scroll compressor according to the
present embodiment has a cylindrically shaped casing 110, and an
upper shell 112 and a lower shell 114 for covering an upper portion
and a lower portion of the casing, respectively. The upper shell
and lower shell are bonded to the casing to form one confined space
together with the casing.
[0029] A discharge pipe 116 is provided at an upper portion of the
upper shell 112. The discharge pipe 116 corresponds to a path
through which compressed refrigerant is discharged to the outside,
and an oil separator (not shown) for separating oil mixed with the
discharged refrigerant may be connected to the discharge pipe 116.
Furthermore, a suction pipe 118 is provided at a lateral surface of
the casing 110. As a path through which refrigerant to be
compressed flows, the suction pipe 118 is located at a boundary
surface between the casing 110 and the upper shell 112 in FIG. 1,
but the location may be set at discretion. Moreover, the lower
shell 114 may also function as an oil chamber for storing oil
supplied to operate the compressor in an efficient manner.
[0030] A motor 120 as a driving unit is provided at a substantially
central portion of the inner portion of the casing 110. The motor
120 may include a stator 122 fixed to an inner surface of the
casing 110 and a rotor 124 located at an inner portion of the
stator 122 to be rotated by an interaction with the stator 122. A
rotation shaft 126 is combined with the center of the rotor 124 and
rotated together with the rotor 124.
[0031] An oil passage 126a is formed at an central portion of the
rotation shaft 126 to be extended along a length direction of the
rotation shaft 126, and an oil pump 126b for supplying oil stored
in the lower shell 114 to the upper portion thereof is provided at
a lower end portion of the rotation shaft 126. The oil pump 126b
may have a shape in which a spiral groove is formed or a separate
impeller is provided at an inner portion of the oil passage, and a
separate capacity type pump may be provided therein.
[0032] An enlarged diameter portion 126c inserted into an inner
portion of the boss portion formed on the fixed scroll which will
be described later is formed at an upper end portion of the
rotation shaft 126. The enlarged diameter portion is formed to have
a diameter larger than the other portion thereof, and a pin portion
126d forming an eccentric portion together with the eccentric
bearing 128 which will be described later is formed at an end
portion of the enlarged diameter portion. The eccentric bearing 128
is inserted into the pin portion 126d to form an eccentric portion,
and referring to FIG. 3, the eccentric bearing 128 is eccentrically
inserted with respect to the pin portion 126d, and a combining
portion for both is asymmetrically formed in a substantially "D"
shape based on the center of the pin portion such that the
eccentric bearing 128 is not rotated with respect to the pin
portion 126d.
[0033] A fixed scroll 130 is mounted on a boundary portion between
the casing 110 and upper shell 112. The fixed scroll 130 is pushed
and fixed between the casing 110 and the upper shell 112 in a
shrink fit manner or combined together with the casing 110 and
upper shell 112 by welding.
[0034] A boss portion 132 into which the foregoing rotation shaft
126 is inserted is formed at a bottom surface of the fixed scroll
130. A penetration hole through which the pin portion 126d of the
rotation shaft 126 passes is formed at an upper side surface (based
on FIG. 1) of the boss portion 132 and thus the pin portion 126d is
protruded in the upward direction of the end plate portion 134 of
the fixed scroll 130 therethrough.
[0035] A fixed wrap 136 engaged with the orbiting wrap which will
be described later to form a compression chamber is formed at an
upper portion surface of the end plate portion 134, and a space
portion for accommodating the orbiting scroll 140 which will be
described later is formed, and a lateral wall portion 138 adjoining
an inner circumferential surface of the casing 110 is formed at an
outer circumferential portion of the end plate portion 134. A
orbiting scroll support portion 138a on which an outer
circumferential portion of the orbiting scroll 140 is placed is
formed at an inner side of the upper end portion of the lateral
wall portion 138, and the height of the orbiting scroll support
portion 138a is formed to have the same height as the fixed wrap
136 or to have a height slightly less than that of the fixed wrap,
and thus an end portion of the orbiting wrap can be brought into
contact with a surface of the end plate portion of the fixed
scroll.
[0036] The orbiting scroll 140 is provided at an upper portion of
the fixed scroll 130. The orbiting scroll 140 is formed with a
substantially orbiting shaped end plate portion 142 and a orbiting
wrap 144 engaged with the fixed wrap 136. A substantially orbiting
shaped rotation shaft combining portion 146 rotatably inserted and
fixed to the eccentric bearing 128 is formed at a central portion
of the end plate portion 142. An outer circumferential portion of
the rotation shaft combining portion 146 is connected to the
orbiting wrap to perform the role of forming a compression chamber
together with the fixed wrap during the compression process. It
will be described later.
[0037] On the other hand, the eccentric bearing 128 is inserted
into the rotation shaft combining portion 146 and thus an end
portion of the rotation shaft 126 is inserted through the end plate
portion of the fixed scroll, and the orbiting wrap, fixed wrap and
eccentric bearing 128 are provided to be overlapped with one
another in the radial direction of the compressor. During
compression, a repulsive force of refrigerant is applied to the
fixed wrap and orbiting wrap, and a compression force is applied
between the rotation shaft support portion and eccentric bearing as
a reaction force thereto. As described above, when part of the
shaft is overlapped with the wrap in a radial direction through the
end plate portion, the repulsive force and compression force of
refrigerant are applied to the same surface based on the end plate,
and thus they are cancelled out by each other. Due to this, it may
be possible to prevent the inclination of the orbiting scroll by
the operation of the compression force and repulsive force.
[0038] Furthermore, though not shown in the drawing, a discharge
hole is formed on the end plate portion 142 and thus compressed
refrigerant may be discharged to an inner portion of the casing.
The location of the discharge hole may be set at discretion by
taking a required discharge pressure or the like into
consideration.
[0039] Furthermore, an oldham ring 150 for preventing the rotation
of the orbiting scroll is provided at an upper side of the orbiting
scroll 140. The oldham ring 150 may include a substantially
orbiting shaped ring portion 152 inserted into a rear surface of
the orbiting scroll 140 and a pair of first key 154 and second key
156 which are protruded on a lateral surface of the ring portion
152. The first key 154 is protruded farther than the thickness of
an outer circumferential side of the end plate portion 142 of the
orbiting scroll 140, and inserted into an inner portion of the
first key groove 154a formed over an upper end of the lateral wall
portion 138 of the fixed scroll 130 and the orbiting scroll support
portion 138a. Moreover, the second keys 156 are combined with the
second key grooves 156a, respectively, formed at an outer
circumferential portion of the end plate portion 142 of the
orbiting scroll 140 in the state of being inserted therein.
[0040] Here, the first key groove 154a is formed to have a vertical
portion extended in the upward direction and a horizontal portion
extended in the left/right direction, and a lower side end portion
of the first key 154 always maintains a state of being inserted in
the horizontal portion of the first key groove 154a, but an outer
side end portion of the first key 154 in the radial direction is
formed to be released from the vertical portion of the first key
groove 154a during the orbiting movement of the orbiting scroll. In
other words, a coupling between the first key groove 154a and the
fixed scroll is made in the vertical direction, thereby reducing
the diameter of the fixed scroll.
[0041] Specifically, a clearance as much as corresponding to a
orbiting radius should be secured between an end plate of the
orbiting scroll and an inner wall of the fixed scroll. If a key of
the oldham ring is combined with the fixed scroll in the radial
direction, then the length of a key groove formed on the fixed
scroll should be at least greater than the orbiting radius to
prevent the oldham ring from being released from the key groove
during the orbiting process, and it may be a cause of increasing
the size of the fixed scroll.
[0042] On the contrary, as in the above embodiment, if the key
groove is extended to a lower space between the end plate and the
orbiting wrap in the orbiting scroll, it may be possible to secure
a sufficient length of the key groove and reducing the size of the
fixed scroll.
[0043] Moreover, in the above embodiment, all keys are formed at a
lateral surface of the ring portion, and thus the height of the
compression unit in the axial direction can be reduced compared to
a case that keys are formed, respectively, in both lateral surfaces
thereof.
[0044] On the other hand, a lower frame 160 for rotatably
supporting a lower side of the rotation shaft 126 is provided at a
lower portion of the casing 110, and the orbiting scroll and an
upper frame 170 for supporting the oldham ring 150 are provided,
respectively, at an upper portion of the orbiting scroll. A hole
communicated with a discharge hole of the orbiting scroll 140 to
discharge compressed refrigerant to the side of the upper shell is
formed at the center of the upper frame 170.
[0045] FIG. 4 is a plan view illustrating a compression chamber
immediately subsequent to inhalation and a compression chamber
immediately prior to discharge in a scroll compressor having a
orbiting wrap and a fixed wrap formed with an involute curve, and
having a configuration that part of the shaft penetrates the end
plate. FIG. 4A is a view illustrating a change of the first
compression chamber formed between an inner lateral surface of the
fixed wrap and an outer lateral surface of the orbiting wrap, and
FIG. 4B is a view illustrating a change of the second compression
chamber formed between an inner lateral surface of the orbiting
wrap and an outer lateral surface of the fixed wrap.
[0046] In the scroll compressor, the compression chamber is created
between two contact points generated when the fixed wrap and
orbiting wrap are brought into contact with each other, and in case
of the fixed wrap and orbiting wrap with an involute curve, two
contact points defining one compression chamber as illustrated in
FIG. 4 are located on a straight line. In other words, the
compression chamber is disposed over 360.degree. with respect to
the center of the rotation shaft.
[0047] Considering a volume change of the first compression chamber
in FIG. 4A, the volume of the compression chamber immediately
subsequent to inhalation located at the outside is gradually
reduced while moving to the central portion thereof by a orbiting
movement of the orbiting scroll, and thus has a minimum value when
reaching an outer circumferential portion of the rotation shaft
combining portion located at the center of the orbiting scroll. In
case of the fixed wrap and orbiting wrap with an involute curve,
the volume reduction rate is linearly reduced as increasing the
rotation angle of the rotation shaft, and thus the compression
chamber should be moved closely to the center if possible, to
obtain a high compression ratio, but in case where the rotation
shaft exists at the center as described above, it can be moved only
to an outer circumferential portion of the rotation shaft. Due to
this, the compression ratio is reduced, and the compression ratio
is about 2.13 in FIG. 4A.
[0048] On the other hand, the second compression chamber
illustrated in FIG. 4B has a lower compression ratio compared to
the first compression chamber, and thus has a value of about 1.46.
However, in case of the second compression chamber, when a
connecting portion between the rotation shaft combining portion (P)
and the orbiting wrap is formed with a orbiting arc shape as
illustrated in FIG. 5A, a compression path of the second
compression chamber is lengthened, thereby increasing the
compression ratio up to a level of 3.0. In this case, the second
compression chamber has a range of less than 360 degrees
immediately prior to discharge. However, such a method cannot be
applicable to the first compression chamber.
[0049] Accordingly, in case of the fixed wrap and orbiting wrap
with an involute shape, an intentional level of compression ratio
can be obtained in case of the second compression chamber, but it
is impossible in case of the first compression chamber, and as a
result, in case that there is a remarkable difference of
compression ratio between the two compression chambers, it will
affect a bad effect on the operation of the compressor.
[0050] In order to solve the foregoing problem, the fixed wrap and
orbiting wrap may be formed to have another curve other than the
involute curve. Referring to FIGS. 6 and 7, when the center of the
rotation shaft combining portion 146 is "O", and two contact points
are "P1, P2", respectively, it is seen that an angle a defined by
two straight lines connecting the two contact points (P1, P2) to
the center (O) of the rotation shaft combining portion is less than
360.degree., and also a distance "I" between perpendicular vectors
at each contact point has a value greater than "0". Due to this,
the first compression chamber immediately prior to discharge has a
volume less than a case of the fixed wrap and orbiting wrap formed
with an involute curve, thereby increasing the compression ratio.
Furthermore, the orbiting wrap and fixed wrap illustrated in FIG. 6
have a configuration in which the diameter and starting point
thereof are connected to a plurality of different orbiting arcs,
and the outermost curve has a substantially oval shape having the
major and minor axes.
[0051] Furthermore, a protrusion portion 137 protruded to the side
of the rotation shaft combining portion 146 is formed adjacent to
an inner side end portion of the fixed wrap, and a contact portion
137a formed to be protruded from the protrusion portion is
additionally formed on the protrusion portion 137. In other words,
the inner side end portion of the fixed wrap is formed to have a
thickness greater than the other portion thereof. Due to this, a
strength of the inner side end portion of the wrap receiving the
highest compression force on the fixed wrap can be enhanced,
thereby enhancing the durability.
[0052] On the other hand, the thickness of the fixed wrap is
gradually decreased from the contact point (P1) located at an inner
side between the two contact points forming the first compression
chamber at a discharge start time point as illustrated in FIG. 7.
Specifically, a first decreasing portion 137b adjacent to the
contact point (P1) and a second decreasing portion 137c adjacent to
the first decreasing portion are formed, and a thickness reduction
rate at the first decreasing portion is greater than that at the
second decreasing portion. Furthermore, the thickness of the fixed
wrap is increased for a predetermined section subsequent to the
second decreasing portion.
[0053] Furthermore, when a distance between an inner surface of the
fixed wrap and the axial center (O') of the rotation shaft is DF,
the DF is decreased after being increased as moving in a counter
clockwise direction (based on FIG. 7) from the P1, and the section
thereof is shown in FIG. 8. FIG. 8 is a plan view illustrating the
location of the orbiting wrap prior to 150.degree. starting
discharge, and the orbiting wrap reaches a configuration
illustrated in FIG. 6 when the rotation shaft is further rotated by
150.degree. from the configuration of FIG. 8. Referring to FIG. 8,
the contact point is located at an upper side of the rotation shaft
combining portion 146, and the DF is increased and then decreased
during the section between P1 of FIGS. 6 and P1 of FIG. 8.
[0054] A concave portion 145 engaged with the protrusion portion is
formed at the rotation shaft combining portion 146. A lateral
surface of the concave portion 145 is brought into contact with the
contact portion 137a of the protrusion portion 137 to form a side
contact point of the first compression chamber. When a distance
between the center of the rotation shaft combining portion 146 and
an outer circumferential portion of the rotation shaft combining
portion 146 is "Do", the "Do" is increased and then decreased
during the section between P1 of FIGS. 6 and P1 of FIG. 8.
Similarly, the thickness of the rotation shaft combining portion
146 is also increased and then decreased during the section between
P1 of FIGS. 6 and P1 of FIG. 8.
[0055] Furthermore, a side wall of the concave portion 145 may
include a first increasing portion 145a in which the thickness
thereof is drastically increased in a relatively high rate and a
second increasing portion 145b connected to the first increasing
portion in which the thickness is increased in a relatively low
rate. They correspond to the first decreasing portion and the
second decreasing portion, respectively. The first increasing
portion, first decreasing portion, second increasing portion, and
second decreasing portion are obtained as a result of bending the
envelope line toward the rotation shaft combining portion. Due to
them, an inner side contact point (P1) forming the first
compression chamber is located at the first increasing portion and
second increasing portion, and as a result, the compression ratio
can be increased by decreasing the length of the first compression
chamber immediately prior to discharge.
[0056] The other side wall of the concave portion 145 is formed to
have a orbiting arc shape. The diameter of the orbiting arc is
determined by a wrap thickness of the end portion of the fixed wrap
and a orbiting radius of the orbiting wrap, and the diameter of the
orbiting arc is increased as increasing the thickness of the end
portion of the fixed wrap. Due to this, the thickness of the
orbiting wrap around the orbiting arc is also increased to secure
the durability, and the compression path is lengthened and thus has
an advantage of increasing the compression ratio of the second
compression chamber as much as the lengthened path.
[0057] Here, a central portion of the concave portion 145 forms
part of the second compression chamber. FIG. 9 is a plan view
illustrating the location of the orbiting wrap when discharge is
started from the second compression chamber, and the second
compression chamber is located adjacent to a orbiting shaped side
wall of the concave portion in FIG. 9, and when the rotation shaft
is further rotated, an end portion of the second compression
chamber passes through a central portion of the concave
portion.
[0058] On the other hand, as described above, in order to apply the
compressor to an air conditioner, a ratio (Vr) of suction volume to
discharge volume should be secured to be equal to or greater than
2.0, and a Sommerfeld number (Sf) should be secured to be equal to
or greater than 0.005, but it is not easy to satisfy the condition
without increasing the size of the compressor in a shaft
penetration scroll compressor. However, as illustrated in FIG. 7,
in case where A/B is formed to be in a range of 0.035-0.085 when a
bearing area between the orbiting scroll and rotation shaft is A
and an end plate area of the orbiting scroll (including the bearing
area) is B, it may be expected to have a result of satisfying the
above condition.
[0059] FIG. 10 is a schematic view illustrating a bearing area and
an end plate area shown in a distinguished manner in the present
embodiment, and FIG. 11 is a graph illustrating a relation between
a value (hereinafter, area ratio) of a bearing area divided by an
end plate area, a volume ratio and a Sommerfeld number. As
illustrated in the drawing, the volume ratio has a relation that
the Sommerfeld number is in inverse proportion to the area ratio.
In other words, the Sommerfeld number is decreased as increasing
the volume ratio whereas the volume ratio is decreased as
increasing the Sommerfeld number at the same area ratio.
Accordingly, in order to secure a proper volume ratio and
Sommerfeld number, it is preferable to secure a proper area ratio
(NB) as illustrated in FIG. 11. When the area ratio (NB) is
designed to maintain 0.035-0.085 in the present embodiment, it may
be possible to obtain a sufficient volume ratio and Sommerfeld
number, thereby performing the compressor performance required for
an air conditioner without increasing the size of the compressor as
well as reducing a frictional loss and abrasion in the orbiting
scroll and rotation shaft.
[0060] The area ratio according to the present embodiment may be
uniformly applicable to all shaft penetration scroll
compressors.
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