FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
SCROLL COMPRESSOR;
MITSUBISHI ELECTRIC CORPORATION, A CORPORATION ORGANISED AND
EXISTING UNDER THE LAWS OF JAPAN, WHOSE ADDRESS IS 7-3,
MARUNOUCHI 2-CHOME, CHIYODA-KU, TOKYO 100-8310, JAPAN
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION
AND THE MANNER IN WHICH IT IS TO BE PERFORMED.

2
DESCRIPTION
5 Technical Field
[0001]
The present disclosure relates to a scroll compressor used in air-conditioning
apparatuses, refrigerators, and other apparatuses.
Background Art
10 [0002]
Scroll compressors used in air-conditioning apparatuses, refrigerators, and
other apparatuses include a compression mechanism unit to compress refrigerant in
a compression chamber defined by a combination of a fixed scroll and an orbiting
scroll, and a shell accommodating the compression mechanism unit. The fixed scroll
15 and the orbiting scroll each include a wrap projected from a base plate. The
respective wraps of these scrolls mesh with each other to define the compression
chamber. As the orbiting scroll is caused to orbit, the compression chamber moves
while decreasing in volume, and thus refrigerant is suctioned into and compressed in
the compression chamber. To reduce the size and cost of this type of scroll
20 compressors, an increasingly important aim of technological developments for such
scroll compressors is to maximize suction volume of the compression chamber to the
extent possible with the diameter of the shell unchanged to thereby increase
compressor capacity. Increasing the suction volume of the compression chamber
with the diameter of the shell unchanged requires careful designing of the spiral
25 shape of the wraps.
[0003]
In some techniques, the spiral shape of the scroll compressor is defined by the
involute curve of a base circle that is a perfect circle with a predetermined radius, and
the wraps are formed with a circular overall outline. By contrast, in some recent
30 techniques, the overall outline of the wraps is flattened rather than circular, and the
3
spiral shape of the wraps is also flattened (see, for example, Patent Literature 1).
Citation List
Patent Literature
[0004]
5 Patent Literature 1: Japanese Unexamined Patent Application Publication No.
10-54380
Summary of Invention
Technical Problem
[0005]
10 Although Patent Literature 1 describes that the outline and spiral shape of each
wrap are flattened, Patent Literature 1 does not describe a specific definition of the
spiral shape. As for the spiral shape of the wrap, as described above, techniques
exist in which the spiral shape is defined by the involute curve of a base circle that is
a perfect circle with a predetermined radius. In this regard, it is necessary, for cases
15 where the wrap has a flattened spiral shape as well, to specifically define the spiral
shape in manufacturing the wrap.
[0006]
An introduction channel is disposed close to the compression mechanism unit
of the scroll compressor. The introduction channel is a channel through which
20 refrigerant to be compressed in the compression chamber is introduced into a suction
space. It is desirable that, irrespective of rotation phase, the introduction channel be
not closed by the wrap and base plate of each of the fixed and orbiting scrolls.
[0007]
In the case of a design in which, as in Patent Literature 1, the outline and spiral
25 of each wrap have a flattened shape with a major axis and a minor axis, two empty
spaces opposite to each other at 180 degrees are defined between a pair of
respective edges opposite to each other in the direction of the minor axis, and the
inner periphery surface of the shell. To maximize the channel area of the
introduction channel to the extent possible for such a design with two empty spaces
30 defined as described above, the introduction channel is to be provided in each of the
4
empty spaces. In other words, plural introduction channels are provided. Providing
plural introduction channels, however, increases the number of machining processes
during manufacture. This leads to increased manufacturing cost.
[0008]
5 One effective manner to avoid such an increase in manufacturing cost is to
consolidate empty spaces in which to provide an introduction channel into a single
location, and dispose, in the single empty space, an introduction channel provided
with sufficient channel area. To consolidate empty spaces in which to provide an
introduction channel into a single location while allowing each wrap to have a
10 flattened spiral shape, it is conceivable to form the spiral shape by a combination of
plural flattened shapes with different flattening ratios. That is, it is conceivable to
provide such an empty space by, for example, making one flattened shape more
squashed than the other flattened shape, by locating the one flattened shape close to
where the empty space is to be provided, and by locating the other flattened shape
15 close to where no empty space is to be provided. However, there are currently no
techniques known in the art that allow such a shape to be defined by equations.
[0009]
The present disclosure aims to address the above-noted issues. It is thus an
object of the present disclosure to provide a scroll compressor in which the spiral
20 shape of each wrap having an outline formed by a combination of plural flattened
shapes with different flattening ratios is defined by equations.
Solution to Problem
[0010]
According to an embodiment of the present disclosure, there is provided a
25 scroll compressor including a fixed scroll having a fixed wrap projected from a fixed
base plate, and an orbiting scroll having an orbiting wrap projected from an orbiting
base plate. The scroll compressor is configured to compress refrigerant in a
compression chamber defined by the fixed wrap and the orbiting wrap meshing with
each other. One of an outer curve and an inner curve of each of the fixed wrap and
30 the orbiting wrap is a curve that is an involute of a base circle and defined in an x-y
5
coordinate system by equation (1) and equation (2) by using an involute angle . A
base-circle radius a() of the base circle in the equation (1) and the equation (2) has a
term representing a product of a "function varying in a sinusoidal or cosine manner
with a period of  [rad] corresponding to the involute angle " and a "coefficient
5 represented by a step function with a period of  [rad]".
x = a()(cos + ·sin) (1)
y = a()(sin − ·cos) (2)
Advantageous Effects of Invention
[0011]
10 According to an embodiment of the present disclosure, the spiral shape of each
wrap is defined in the x-y coordinate system by equation (1) and equation (2) by using
the involute angle . The base-circle radius a() in equation (1) and equation (2) has
a term representing the product of a "function varying in a sinusoidal or cosine
manner with a period of  [rad] corresponding to the involute angle " and a
15 "coefficient represented by a step function with a period of  [rad]". As a result, the
spiral shape of each wrap having an outline formed by a combination of plural
flattened shapes with different flattening ratios is defined by equations.
x = a()(cos + sin) (1)
y = a()(sin − cos) (2)
20 Brief Description of Drawings
[0012]
[Fig. 1] Fig. 1 is a schematic longitudinal sectional view of a scroll compressor
according to Embodiment 1, illustrating the overall configuration of the scroll
compressor.
25 [Fig. 2] Fig. 2 is a transverse sectional view of a compression mechanism unit
of the scroll compressor according to Embodiment 1.
[Fig. 3] Fig. 3 is a plan view of a fixed wrap and an orbiting wrap of the
compression mechanism unit of the scroll compressor according to Embodiment 1.
[Fig. 4] Fig. 4 illustrates a compression process, depicting operation during one
30 revolution of the orbiting scroll in the scroll compressor according to Embodiment 1.
6
[Fig. 5] Fig. 5 illustrates how to draw each spiral shape of the compression
mechanism unit of the scroll compressor according to Embodiment 1.
[Fig. 6] Fig. 6 illustrates exemplary characteristics related to a base-circle
radius a() used in drawing the spiral shape of each wrap in the scroll compressor
5 according to Embodiment 1.
[Fig. 7] Fig. 7 illustrates changes in the flattening ratio of the outer curve of
each wrap in a scroll compressor according to Embodiment 2.
[Fig. 8] Fig. 8 illustrates each wrap in a scroll compressor according to
Embodiment 3.
10 [Fig. 9] Fig. 9 illustrates a compression process, depicting operation during one
revolution of an orbiting scroll in the scroll compressor illustrated in Fig. 8(b).
[Fig. 10] Fig. 10 illustrates characteristics related to the base-circle radius a()
of each wrap in a scroll compressor according to Embodiment 4.
Description of Embodiments
15 [0013]
A scroll compressor according to embodiments is described below with
reference to the drawings or other illustrations. In the drawings below including Fig.
1, elements designated by the same reference signs represent the same or
corresponding elements throughout the following description of embodiments. The
20 specific arrangements of components described throughout the specification are
intended to be illustrative only and not restrictive.
[0014]
Embodiment 1
Fig. 1 is a schematic longitudinal sectional view of a scroll compressor
25 according to Embodiment 1, illustrating the overall configuration of the scroll
compressor.
The scroll compressor according to Embodiment 1 includes a compression
mechanism unit 8, a motor mechanism unit 110, which drives the compression
mechanism unit 8 via a rotary shaft 6, and other components. These components
30 are accommodated in a hermetic shell 100 that defines the exterior of the scroll
7
compressor. The compression mechanism unit 8 is disposed in an upper portion of
the interior of the hermetic shell 100, and the motor mechanism unit 110 is disposed
below the compression mechanism unit 8.
[0015]
5 A frame 7 and a sub-frame 9 are further disposed in the hermetic shell 100
such that the frame 7 and the sub-frame 9 face each other with the motor mechanism
unit 110 between the frame 7 and the sub-frame 9. The frame 7 is disposed over the
motor mechanism unit 110 and located between the motor mechanism unit 110 and
the compression mechanism unit 8. The sub-frame 9 is disposed under the motor
10 mechanism unit 110. The frame 7 is secured to the inner periphery surface of the
hermetic shell 100 by shrink-fitting, welding, or other methods. The sub-frame 9 is
secured via a sub-frame holder 9a to the inner periphery surface of the hermetic shell
100 by shrink-fitting, welding, or other methods.
[0016]
15 A pump element 112 including a positive displacement pump is mounted below
the sub-frame 9. The pump element 112 supplies refrigerating machine oil stored in
an oil reservoir 100a in the bottom portion of the hermetic shell 100 to sliding parts of
the compression mechanism unit 8, such as a main bearing 7a described later. The
pump element 112 supports, on its top end face, the rotary shaft 6 in the axial
20 direction.
[0017]
The hermetic shell 100 is provided with a suction pipe 101 for sucking
refrigerant, and a discharge pipe 102 for discharging refrigerant.
[0018]
25 The compression mechanism unit 8 is configured to compress refrigerant
suctioned through the suction pipe 101, and discharge the compressed refrigerant to
a high-pressure part provided in an upper portion of the interior of the hermetic shell
100. The compression mechanism unit 8 includes a fixed scroll 1, and an orbiting
scroll 2.
30 [0019]
8
The fixed scroll 1 is secured via the frame 7 to the hermetic shell 100. The
orbiting scroll 2 is disposed under the fixed scroll 1, and supported by an eccentric
shaft part 6a of the rotary shaft 6, which will be described later, in a manner that
allows orbital motion of the orbiting scroll 2.
5 [0020]
The fixed scroll 1 includes a fixed base plate 1a, and a fixed wrap 1b in the
form of a spiral projection projected from one surface of the fixed base plate 1a. The
orbiting scroll 2 includes an orbiting base plate 2a, and an orbiting wrap 2b in the form
of a spiral projection projected from one surface of the orbiting base plate 2a. The
10 fixed scroll 1 and the orbiting scroll 2 are disposed in the hermetic shell 100 in a
symmetrical spiral arrangement such that the fixed wrap 1b and the orbiting wrap 2b
are intermeshed in an opposite phase relationship to each other. The fixed wrap 1b
and the orbiting wrap 2b define a compression chamber 71 between the fixed wrap
1b and the orbiting wrap 2b, which have a volume that progressively decreases from
15 a radially outer portion toward a radially inner portion as the rotary shaft 6 rotates.
[0021]
A baffle 4 is secured to a surface of the fixed base plate 1a of the fixed scroll 1
opposite to the surface facing the orbiting scroll 2. The baffle 4 has a through-hole
4a in communication with a discharge port 1c of the fixed scroll 1. A discharge valve
20 11 is provided over the through-hole 4a. A discharge muffler 12 is attached to the
baffle 4 such that the discharge muffler 12 covers the discharge port 1c.
[0022]
The frame 7 has a thrust surface to which the fixed scroll 1 is secured and that
axially supports a thrust force acting on the orbiting scroll 2. The frame 7 has an
25 introduction channel 7c penetrating the frame 7 and through which refrigerant
suctioned through the suction pipe 101 is introduced into the compression
mechanism unit 8.
[0023]
An Oldham ring 14 is disposed on the frame 7 to prevent the orbiting scroll 2
30 from rotating on its own axis during its orbital motion. The Oldham ring 14 has a key
9
part 14a disposed under the orbiting base plate 2a of the orbiting scroll 2.
[0024]
The motor mechanism unit 110 provides a rotational drive force to the rotary
shaft 6. The motor mechanism unit 110 includes a motor stator 110a, and a motor
5 rotor 110b. To obtain electric power from outside, the motor stator 110a is connected
by a lead wire (not illustrated) to a glass terminal (not illustrated) located between the
frame 7 and the motor stator 110a. The motor stator 110a is secured to the rotary
shaft 6 by shrink fitting or other methods. To provide overall balancing of the
rotational system of the scroll compressor, a first balancing weight 60 is secured to
10 the rotary shaft 6, and a second balancing weight 61 is secured to the motor stator
110a.
[0025]
The rotary shaft 6 includes the eccentric shaft part 6a defining an upper
portion, a main shaft part 6b defining an intermediate portion, and a sub-shaft part 6c
15 defining a lower portion. The eccentric shaft part 6a is eccentric with its center offset
from the center of the axis of the rotary shaft 6. The eccentric shaft part 6a is
engaged with the orbiting scroll 2 via a balancing-weight-attached slider 5 and an
orbiting bearing 2c. This allows the orbiting scroll 2 to make orbital motion as the
rotary shaft 6 rotates. The main shaft part 6b is engaged with the main bearing 7a
20 via a sleeve 13, and the main bearing 7a is disposed on the inner periphery of a
cylindrical boss part 7b provided to the frame 7. The main shaft part 6b slides
against the main bearing 7a with an oil film between the main shaft part 6b and the
main bearing 7a that is created by refrigerating machine oil. The main bearing 7a is
secured in the boss part 7b such as by press-fitting of a bearing material used for a
25 slide bearing such as a copper-lead alloy.
[0026]
A sub-bearing 10 in the form of a ball bearing is provided over the sub-frame 9.
The sub-bearing 10 radially supports the rotary shaft 6 in a rotatable manner under
the motor mechanism unit 110. As the sub-bearing 10, a bearing other than a ball
30 bearing may be used to support the rotary shaft 6 in a rotatable manner. The sub-
10
shaft part 6c is engaged with the sub-bearing 10, and slides against the sub-bearing
10 with an oil film between the sub-shaft part 6c and the sub-bearing 10 that is
created by refrigerating machine oil. The main shaft part 6b and the sub-shaft part
6c are coaxial with the rotary shaft 6.
5 [0027]
The internal space of the hermetic shell 100 is defined as follows. The
internal space of the hermetic shell 100 includes a first space 72 defined as a space
located closer to the motor rotor 110b than is the frame 7. The internal space also
includes a second space 73 defined as a space enclosed by the inner wall of the
10 frame 7 and by the fixed base plate 1a. The internal space also includes a third
space 74 defined as a space located closer to the discharge pipe 102 than is the fixed
base plate 1a. The second space 73 includes a suction space 73a defined as a
space located outside a structure formed by a combination of the fixed wrap 1b and
the orbiting wrap 2b. Refrigerant to be compressed in the compression chamber 71
15 is introduced through the introduction channel 7c into the suction space 73a.
[0028]
Reference is made below to how various components of the compression
mechanism unit 8 are arranged in the hermetic shell 100.
Fig. 2 is a transverse sectional view of the compression mechanism unit of the
20 scroll compressor according to Embodiment 1. Fig. 3 is a plan view of the fixed wrap
and the orbiting wrap in the compression mechanism unit of the scroll compressor
according to Embodiment 1. In Fig. 2 and Fig. 3, the orbiting wrap 2b of the orbiting
scroll 2 is shown dotted to facilitate the differentiation between the fixed wrap 1b of
the fixed scroll 1 and the orbiting wrap 2b of the orbiting scroll 2. The same applies
25 to figures that will be described later.
[0029]
The hermetic shell 100 has the shape of a perfect circle in plan view. In the
hermetic shell 100, the outer periphery surface of the frame 7 is secured in contact
with the inner periphery surface of the hermetic shell 100. Thus, the outer periphery
30 surface of the frame 7 also has the shape of a perfect circle.
11
[0030]
According to Embodiment 1, the orbiting base plate 2a has a flattened outer
shape. Thus, by forming the orbiting wrap 2b, which is projected from the orbiting
base plate 2a, such that its spiral shape is also flattened, the space on top of the
5 orbiting base plate 2a is effectively utilized. This allows for more efficient space
usage. The same applies to the fixed base plate 1a. That is, the fixed base plate
1a is formed with a flattened outer shape, and the fixed wrap 1b is formed with a
flatted spiral shape. Increasing space efficiency in this manner helps to ensure that
the compression chamber 71 is increased in volume with the size of the hermetic
10 shell 100 unchanged, and thus compressor capacity is improved. Conversely
speaking, the size of the hermetic shell 100 required to provide the same compressor
capacity is reduced. In the following description, the term "wrap" or "wraps" is used
to generically refer to both the fixed wrap 1b and the orbiting wrap 2b when no
distinction is to be made between these wraps. The same applies to the base
15 plates. That is, the term "base plate" or "base plates" is used to generically refer to
both the fixed base plate 1a and the orbiting base plate 2a when no distinction is to
be made between these base plates.
[0031]
Embodiment 1 is characterized in that each wrap has a spiral shape formed by
20 a combination of two flattened shapes with different flattening ratios. Specifically, the
flattened spiral shape according to Embodiment 1 is such that a region A and a region
B differ in flattening ratio as illustrated in Fig. 3. As described above, according to
Embodiment 1, the flattening ratio is varied between the region A and the region B.
As a result, the flattened shape in one of the two regions, which in this example is the
25 region B, appears more squashed than the flattened shape in the region A. This
configuration allows an empty space to be created between the flattened shape in the
region B and the inner circumferential surface of the hermetic shell 100. The
introduction channel 7c is disposed in this empty space. In this regard, exemplary
flattened shapes also include oblong and elliptical shapes. That is, a flattened shape
30 generically refers to any shape that is more flattened than the shape of a perfect
12
circle. More details about spiral shapes formed as described above will be given
again later.
[0032]
Reference is made below to operation of the scroll compressor.
5 [0033]
Fig. 4 illustrates a compression process, depicting operation during one
revolution of the orbiting scroll in the scroll compressor according to Embodiment 1.
Fig. 4(a) illustrates the position of each wrap at a rotation phase of 0 [rad] (2 [rad]).
Fig. 4(b) illustrates the position of each wrap at a rotation phase of /2 [rad]. Fig.
10 4(c) illustrates the position of each wrap at a rotation phase of  [rad]. Fig. 4(d)
illustrates the position of each wrap at a rotation phase of 3/2 [rad].
[0034]
When the motor stator 110a of the motor mechanism unit 110 is energized, the
motor rotor 110b receives a rotational force and rotates. Accordingly, the rotary shaft
15 6 secured to the motor rotor 110b is rotationally driven. The rotational motion of the
rotary shaft 6 is transmitted to the orbiting scroll 2 via the eccentric shaft part 6a.
The orbiting wrap 2b of the orbiting scroll 2 makes orbital motion with an orbit radius
while having its rotation restricted by the Oldham ring 14. The term orbit radius
means the amount of eccentricity of the eccentric shaft part 6a with its center offset
20 from the main shaft part 6b.
[0035]
Driving of the motor mechanism unit 110 causes refrigerant to flow from an
external refrigeration cycle into the first space 72 in the hermetic shell 100 through the
suction pipe 101. Low-pressure refrigerant entering the first space 72 passes
25 through the introduction channel 7c defined in the frame 7, and flows into the suction
space 73a. Upon entering the suction space 73a, the low-pressure refrigerant is
suctioned into the compression chamber 71 because of the relative orbital movement
between the orbiting wrap 2b and the fixed wrap 1b in the compression mechanism
unit 8. As illustrated in Fig. 4, the refrigerant suctioned into the compression
30 chamber 71 is raised from a low pressure to a high pressure because of geometrical
13
changes in the volume of the compression chamber 71 associated with the relative
movement between the orbiting wrap 2b and the fixed wrap 1b. The refrigerant
raised to a high pressure then passes through the discharge port 1c of the fixed scroll
1 and the through-hole 4a of the baffle 4, and pushes open the discharge valve 11 to
5 be discharged to the interior of the discharge muffler 12. The refrigerant discharged
to the interior of the discharge muffler 12 is discharged into the third space 74, and
then discharged through the discharge pipe 102 to the outside of the compressor as
high-pressure refrigerant. The arrows in Fig. 1 represent the flow of refrigerant
mentioned above.
10 [0036]
According to Embodiment 1, as described above, the respective outlines of the
orbiting wrap 2b and the fixed wrap 1b are flattened, and their respective spiral
shapes are also flattened. In the compression mechanism unit 8 with each wrap
having a flattened spiral shape as described above, when the orbiting wrap 2b is
15 caused to move in an orbit with a predetermined radius as illustrated in Fig. 4, the
orbiting wrap 2b moves with its outward-facing and inward-facing surfaces
respectively making contact with the corresponding inward-facing and outward-facing
surfaces of the fixed wrap 1b.
[0037]
20 Embodiment 1 is characterized in that the spiral shape of each wrap having an
outline formed by a combination of plural flattened shapes with different flattening
ratios is defined by equations. The spiral shape of the wrap is determined by an
outer curve and an inner curve, the outer curve is a curve that determines the
outward-facing surface of the wrap, and the inner curve is a curve that determines the
25 inward-facing surface of the wrap. In defining the spiral shape of the wrap by using
equations, specifically, one of the outer curve and inner curve of the wrap is
represented by a curve that is the involute of a base circle and defined in the x-y
coordinate system by equation (1) and equation (2) below by using an involute angle
.
30 [0038]
In equations (1) and (2)
represented in equation (3) below, t
expression having a term repre
sinusoidal or cosine manner with a period of
5 angle " and a "coefficient 
[rad]". The coefficient  represents
of each wrap having an outline
with different flattening ratios
the base-circle radius a() is
10 [0039]
[Math. 1]
[0040]
[Math. 2]
15
[0041]
[Math. 3]
[0042]
20 In equation (3), a0 denotes a base
be referred to as reference radius
with a period of  [rad] refers to a real variable function whose
corresponding to the involute angle
exist, and the step function
25 functions. Specifically, the s
alternately every /2 with a period of
() alternates every /2 between
the involute angle  is in the range from
involute angle  is in the range from
30 = 1 is satisfied when the involute angle
14
equations (1) and (2), a() represents the radius of the base circle.
represented in equation (3) below, the base-circle radius a() is given by a
representing the product of a "function varying in a
sinusoidal or cosine manner with a period of  [rad] corresponding to
 represented by a step function () with a period of
represents the degree of flattening. Thus, the spiral shape
an outline formed by a combination of plural flattened shapes
with different flattening ratios is defined by equations. According to
is defined to be varied as in, for example,
denotes a base-circle radius that is used as a reference
be referred to as reference radius hereinafter). In equation (3), a step function
refers to a real variable function whose graph is stepped
involute angle . Indicator functions with a period of
the step function () is represented by linear combination of such indicator
Specifically, the step function () is a function whose value changes
/2 with a period of  [rad]. In the present example, the value of
between 1 and 2. That is, () = 1 is satisfied
is in the range from 0 to /2, and () = 2 is satisfied
is in the range from /2 to . Likewise, in the next cycle as well,
when the involute angle  is in the range from  to 3
base circle. As
is given by a function
function varying in a
to the involute
) with a period of 
Thus, the spiral shape
ed by a combination of plural flattened shapes
ccording to Embodiment 1,
varied as in, for example, equation (3).
as a reference (to
a step function ()
graph is stepped
ndicator functions with a period of  [rad]
linear combination of such indicator
is a function whose value changes
In the present example, the value of
is satisfied when
is satisfied when the
Likewise, in the next cycle as well, ()
3/2, and () =
15
2 is satisfied when the involute angle  is in the range from 3/2 to 2.
[0043]
In equation (3), N is a natural number greater than or equal to 1. Symbol 
denotes a constant [rad]. The constant  represents an involute angle for a
5 combination of the following flattened shapes: a flattened shape with () in equation
(3) set as 1 (to be referred to as "flattened shape based on 1" hereinafter); and a
flattened shape with () in equation (3) set as 2 (to be referred to as "flattened
shape based on 2" hereinafter).
[0044]
10 By changing the coefficient  in equation (3), the flattening ratio of the outline of
each wrap is set as desired. Specifically, as the value of  increases, the flattening
ratio of the wrap outline increases, resulting in a more flattened shape. The spiral
shape of each wrap according to Embodiment 1 is formed by a combination of two
flattened shapes, one is a flattened shape based on 1, and the other is a flattened
15 shape based on 2. In Fig. 3, the flattened shape in the region A represents a case
where 1 is 0.3. The flattened shape in the region B represents a case where 2 is
−0.2. Further, in Fig. 3, N has a value of 1, and  has a value of 0. Changes in the
shape of each wrap with varying values of  will be described later with reference to
Embodiment 3.
20 [0045]
Reference is made below to a method for drawing the respective spiral shapes
of the fixed wrap 1b and the orbiting wrap 2b. The fixed wrap 1b and the orbiting
wrap 2b are drawn by the same method. Accordingly, a method for drawing the
orbiting wrap 2b is described below as a representative example. As described
25 above, the orbiting wrap 2b has a spiral shape formed by a combination of two
flattened shapes with different flattening ratios. In this regard, each flattened shape
itself is drawn by the same method.
[0046]
As described above, the spiral shape of each wrap is determined by an outer
30 curve that determines the outward-facing surface of the wrap, and an inner curve that
16
determines the inward-facing surface of the wrap. A method for drawing a spiral
shape with an outer curve defined by equation (1) and equation (2) is described
below with reference to Fig. 5.
[0047]
5 Fig. 5 illustrates how to draw each spiral shape of the compression mechanism
unit of the scroll compressor according to Embodiment 1. In Fig. 5, the spiral shape
is drawn by steps (a), (b), (c), and (d).
[0048]
First, as illustrated in Fig. 5(a), an involute 30 of a base circle is drawn. As
10 described above, a() increases in a sinusoidal manner with a period of  [rad]
corresponding to the involute angle . The involute 30 thus drawn is used as the
outer curve. The value of a() is set as 1.
[0049]
Subsequently, an inner curve is drawn by steps illustrated in Fig. 5(b) to Fig.
15 5(d). That is, first, as illustrated in Fig. 5(b), a curve 31 is drawn, which is a curve
obtained by rotating the involute 30 drawn in step (a) by  [rad] about the base-circle
center O. As an inner curve is to be created at this time, a portion of the curve 31
located outside the curve 30 (the dotted portion in Fig. 5(b)) is not used in the
subsequent drawing steps.
20 [0050]
Subsequently, as illustrated in Fig. 5(c), plural circles 32 are drawn. The
circles 32 each have a center lying on the curve 31 drawn in step (b) and are of a
radius equal to the orbit radius of the orbiting scroll 2.
[0051]
25 Subsequently, as illustrated in Fig. 5(d), an outer envelope 33 to the group of
circles drawn in step (c) is drawn. The curve 33 thus drawn in step (d) is used as the
inner curve.
[0052]
As described above, the curve 30 drawn in step (a) is used as the outer curve
30 of the orbiting wrap 2b, and the curve 33 drawn in step (d) is used as the inner curve
17
of the orbiting wrap 2b. One of two regions obtained by splitting the dotted region
illustrated in step (d) into two, left and right regions, at the base-circle center O
represents the cross-section of one of the two spiral shapes of the orbiting wrap 2b.
[0053]
5 Likewise, a spiral shape with a() set as 2 is drawn by the steps in Fig. 5(a) to
Fig. 5(d). The other one of the two regions obtained by splitting the dotted region
illustrated in step (d) into two, left and right regions, at the base-circle center O
represents the cross-section of the other one of the two spiral shapes of the orbiting
wrap 2b. The spiral shape of the orbiting wrap 2b is drawn as described above.
10 [0054]
With regard to the fixed wrap 1b, steps similar to those for the orbiting wrap 2b
mentioned above are followed. For specifications in which the fixed wrap 1b has a
wall thickness equal to that of the orbiting wrap 2b, the fixed wrap 1b has a shape
obtained by rotating the shape of the orbiting wrap 2b by  [rad].
15 [0055]
Although the foregoing description is directed to the method for drawing a spiral
shape with an outer curve defined by equation (1) and equation (2), basically the
same method is used for drawing a spiral shape with an inner curve defined by
equation (1) and equation (2). When the inner curve is a curve defined by equation
20 (1) and equation (2), the outer curve is only required to be drawn as follows. First,
the step in Fig. 5(a) is performed, followed by the step in Fig. 5(b). In the step in Fig.
5(b), a portion of the curve 30 located outside the curve 31 is not used in the
subsequent drawing steps. Then, plural circles 32 are drawn. The circles 32 each
have a center lying on the curve 31 and are of a radius equal to the orbit radius of the
25 orbiting scroll 2. An inner envelope to the group of circles is used as the outer curve.
[0056]
Fig. 6 illustrates exemplary characteristics related to the base-circle radius a()
used in drawing the spiral shape of each wrap in the scroll compressor according to
Embodiment 1. In Fig. 6, the vertical axis represents the ratio of the base-circle
30 radius a() to the reference radius a0. The horizontal axis in Fig. 6 represents the
18
involute angle  [rad].
[0057]
Fig. 6 illustrates periodic changes in base-circle radius a() corresponding to
the involute angle  when, as in Fig. 3, the value of () in equation (3) is set as 1 =
5 0.3 and 2 = −0.2, the value of N is set as 1, and the value of  is set as 0. In the
waveform of the base-circle radius a() illustrated in Fig. 6, a greater value of a()/a0
indicates a greater wall thickness of the wrap. Thus, the wrap has an increased wall
thickness at /4, 5/4, and 9/4. Further, in the waveform of the base-circle radius
a(), the wrap is elongated in the direction of involute angles corresponding to peaks
10 exceeding 1.0. Accordingly, in the example in Fig. 6, peaks exceeding 1.0 are at
involute angles of /4, 5/4, and 9/4, and thus the resulting shape of the wrap is
such that the wrap is elongated in the lateral direction as illustrated in Fig. 3.
[0058]
As described above, according to Embodiment 1, the spiral shape of each wrap
15 is defined by equation (1) and equation (2) mentioned above by using the involute
angle . Further, the base-circle radius a() in equation (1) and equation (2) has a
term representing the product of a "function varying in a sinusoidal or cosine manner
with a period of  [rad] corresponding to the involute angle " and a "coefficient 
represented by a step function () with a period of  [rad]". Thus, the spiral shape
20 of each wrap having an outline formed by a combination of plural flattened shapes
with different flattening ratios is defined by equations.
[0059]
According to Embodiment 1, with the base-circle radius a() given as equation
(3), the respective outlines of the fixed wrap 1b and the orbiting wrap 2b are set as
25 desired.
[0060]
According to Embodiment 1, () is a function whose value changes alternately
every /2 with a change period of  [rad]. As  is thus used as two values, a spiral
shape for each wrap that allows empty spaces to be consolidated into a single
30 location is defined by equations. Specifically, by making one value of  smaller than
19
the other value of , an empty space is created close to the flattened space defined
by using the one value of . The introduction channel 7c is provided in this empty
space. Therefore, for a case where a single introduction channel 7c is to be
provided, the introduction channel 7c is designed to have a large channel area.
5 [0061]
Embodiment 2
The following description of Embodiment 2 is directed to changes in the
flattening ratio of the outline of each wrap corresponding to the value of  in equation
(3) mentioned above. Embodiment 2 is described below with focus on features
10 different from those according to Embodiment 1, and features not described with
reference to Embodiment 2 below are similar or identical to those according to
Embodiment 1.
[0062]
Various spiral shapes of each wrap with varying values of  in equation (3)
15 mentioned above are described below with reference to Fig. 7.
[0063]
Fig. 7 illustrates changes in the flattening ratio of the outer curve of each wrap
in a scroll compressor according to Embodiment 2. Fig. 7(a) represents a case
where 1 = 0 and 2 = 0 are satisfied, Fig. 7(b) represents a case where 1 = 0.3
20 and 2 = 0 are satisfied, and Fig. 7(c) represents a case where 1 = 0.3 and 2 =
−0.2 are satisfied.
[0064]
As illustrated in Fig. 7, by changing the value of , the flattening ratio of the
outline of each wrap is set as desired. As illustrated in Fig. 7(a), a flattening ratio
25 refers to the ratio (D11 + D12) / D2 between the length D11 + D12 of the major axis,
and the length D2 of the minor axis. The flattening ratio for the region A in Fig. 7 of
the above-mentioned outline, that is, a region with each spiral formed by using 1, is
given as (D11  2) / D2. The flattening ratio for the region B in Fig. 7, that is, a
region with each spiral formed by using 2, is given as (D12  2) / D2.
30 [0065]
20
Specifically, the flattening ratio increases with increasing value of . As is
apparent from a comparison of the flattened shape in the region A between Fig. 7(a)
and Fig. 7(b), the flattened shape in Fig. 7(b) with the greater value of 1 has a
greater flattening ratio than does the flattening shape in Fig. 7(a). Further, as is
5 apparent from a comparison of the flattened shape in the region B between Fig. 7(b)
and Fig. 7(c), the flattened shape in Fig. 7(b) with the greater value of 2 has a
greater flattening ratio than does the flattened shape in Fig. 7(c).
[0066]
As is apparent from Fig. 7, the respective flattening ratios of the flattened
10 shapes in the regions A and B in Fig. 7 are set independently by the values of 1 and
2.
[0067]
According to Embodiment 2, an effect similar to Embodiment 1 is obtained.
Additionally, the respective flattening ratios of individual flattened shapes are set as
15 desired by the values of 1 and 2. Therefore, by setting 1 and 2 suitable to the
space in which to dispose the introduction channel 7c, even when a single
introduction channel 7c is to be provided, the introduction channel 7c is designed to
have a large channel area.
[0068]
20 Embodiment 3
The following description of Embodiment 3 is directed to a case where the
involute angle  is varied. Embodiment 3 is described below with focus on features
different from those according to Embodiment 1, and features not described with
reference to Embodiment 3 below are similar or identical to those according to
25 Embodiment 1.
[0069]
Fig. 8 illustrates each wrap in a scroll compressor according to Embodiment 3.
Fig. 8(a) represents a case where 1 = 0.3, 2 = −0.2, and  = 0 [rad] are satisfied,
and Fig. 8(b) represents a case where 1 = 0.3, 2 = −0.2, and  = /4 [rad] are
30 satisfied. As described above,  represents an involute angle for a combination of a
21
flattened shape based on 1 and a flattened shape based on 2. For each of the
spirals in Fig. 8(a) and Fig. 8(b), the region A in Fig. 8 represents a flattened shape
based on 1, and the region B represents a flattened shape based on 2. It is
apparent from Fig. 8 that changing the value of  causes the spiral shape as a whole
5 to change in its orientation.
[0070]
Fig. 9 illustrates a compression process, depicting operation during one
revolution of the orbiting scroll in the scroll compressor illustrated in Fig. 8(b). Fig.
9(a) illustrates the position of each wrap at a rotation phase of 0 [rad] (2 [rad]). Fig.
10 9(b) illustrates the position of each wrap at a rotation phase of /2 [rad]. Fig. 9(c)
illustrates the position of each wrap at a rotation phase of  [rad]. Fig. 9(d) illustrates
the position of each wrap at a rotation phase of 3/2 [rad]. As illustrated in Fig. 9,
even for a case where the value of  is set to a phase other than 0 [rad], a
compressing operation is achieved in the same manner as in the case of Fig. 4
15 described above with reference to Embodiment 1.
[0071]
According to Embodiment 3, an effect similar to Embodiment 1 and
Embodiment 2 is obtained. Additionally, by changing the value of , the orientation
of the spiral shape as a whole is changed suitably to where the introduction channel
20 7c is to be disposed.
[0072]
Embodiment 4
The following description of Embodiment 4 is directed to other function
expressions for the base-circle radius a(). Embodiment 4 is described below with
25 focus on features different from those according to Embodiment 1, and features not
described with reference to Embodiment 4 below are similar or identical to those
according to Embodiment 1.
[0073]
Fig. 10 illustrates characteristics related to the base-circle radius a() of each
30 wrap in a scroll compressor according to Embodiment 4. Fig. 10(a) to Fig. 10(d)
correspond to function expressions
(3), which is described above with reference to Embodiment 1, and equations (4) to
(6) below. In Fig. 10, the vertical axis represents the ratio of the base
a() to the reference radius a
5 angle  [rad]. In each of Fig. 10
0 are satisfied.
[0074]
[Math. 4]
10 [0075]
[Math. 5]
[0076]
[Math. 6]
15
[0077]
For the base-circle radius
equation (3) mentioned above with reference to
base-circle radius a() as in
20 wrap 1b and the orbiting wrap 2b
[0078]
Although the foregoing description of Embodiments 1
where the scroll compressor is of a low
100 is filled with low-pressure
25 likewise obtained for a case where the scroll compresso
type in which the hermetic shell 100 is filled with
Reference Signs List
[0079]
1: fixed scroll, 1a: fixed base plate, 1b: fixed wrap, 1c: discharge port, 2:
30 orbiting scroll, 2a: orbiting base plate
22
function expressions for the base-circle radius a() given as equation
above with reference to Embodiment 1, and equations (4) to
(6) below. In Fig. 10, the vertical axis represents the ratio of the base
) to the reference radius a0. The horizontal axis in Fig. 10 represents
Fig. 10(a) to Fig. 10(d), 1 = 0.3, 2 = −0.2, N
circle radius a(), equations (4) to (6) are used in addition to
above with reference to Embodiment 1. By changing the
in equations (3) to (6), the respective outline
wrap 1b and the orbiting wrap 2b are set as desired.
Although the foregoing description of Embodiments 1 to 4 is directed to a case
where the scroll compressor is of a low-pressure shell type in which
pressure refrigerant, the same effects as mentioned above
case where the scroll compressor is of a high
the hermetic shell 100 is filled with high-pressure refrigerant
1: fixed scroll, 1a: fixed base plate, 1b: fixed wrap, 1c: discharge port, 2:
orbiting scroll, 2a: orbiting base plate, 2b: orbiting wrap, 2c: orbiting bearing, 4: baffle,
) given as equation
above with reference to Embodiment 1, and equations (4) to
(6) below. In Fig. 10, the vertical axis represents the ratio of the base-circle radius
The horizontal axis in Fig. 10 represents the involute
.2, N = 1, and  =
used in addition to
By changing the
outlines of the fixed
to 4 is directed to a case
the hermetic shell
the same effects as mentioned above are
r is of a high-pressure shell
refrigerant.
1: fixed scroll, 1a: fixed base plate, 1b: fixed wrap, 1c: discharge port, 2:
, 2b: orbiting wrap, 2c: orbiting bearing, 4: baffle,
23
4a: through-hole, 5: balancing-weight-attached slider, 6: rotary shaft, 6a: eccentric
shaft part, 6b: main shaft part, 6c: sub-shaft part, 7: frame, 7a: main bearing, 7b: boss
part, 7c: introduction channel, 8: compression mechanism unit, 9: sub-frame, 9a: subframe holder, 10: sub-bearing, 11: discharge valve, 12: discharge muffler, 13: sleeve,
5 14: Oldham ring, 14a: key part, 30: involute, 32: circle, 33: outer envelope, 60: first
balancing weight, 61: second balancing weight, 71: compression chamber, 72: first
space, 73: second space, 73a: suction space, 74: third space, 100: hermetic shell,
100a: oil reservoir, 101: suction pipe, 102: discharge pipe, 110: motor mechanism
unit, 110a: motor stator, 110b: motor rotor, 112: pump element
10
We Claim :
[Claim 1]
A scroll compressor comprising
a fixed scroll having a fixed wrap projected from a fixed base plate
5 an orbiting scroll having an orbiting wrap projected from an orbiting base plate,
the scroll compressor being configured to compress refrigerant in a
compression chamber defined by
each other,
one of an outer curve and an inner curve of each of the fixed wrap and the
10 orbiting wrap being a curve that is an involute of a base circle and defined in
coordinate system by equation (1) and equation (2) by using an involute angle
[Math. 1]
[Math. 2]
15
,
a base-circle radius a(
(2) having a term representing
cosine manner with a period of
20 "coefficient represented by a step function with a period of
[Claim 2]
The scroll compressor of claim 1,
by one of equation (3) to equation (6)
[Math. 3]
25
[Math. 4]
[Math. 5]
30 [Math. 6]
24
A scroll compressor comprising:
a fixed scroll having a fixed wrap projected from a fixed base plate
orbiting scroll having an orbiting wrap projected from an orbiting base plate,
scroll compressor being configured to compress refrigerant in a
compression chamber defined by the fixed wrap and the orbiting wrap meshing with
one of an outer curve and an inner curve of each of the fixed wrap and the
curve that is an involute of a base circle and defined in
coordinate system by equation (1) and equation (2) by using an involute angle
radius a() of the base circle in the equation (1) and the equation
representing a product of a "function varying in a sinusoidal or
cosine manner with a period of  [rad] corresponding to the involute angle
"coefficient represented by a step function with a period of  [rad]".
The scroll compressor of claim 1, wherein the base-circle radius
equation (3) to equation (6):
a fixed scroll having a fixed wrap projected from a fixed base plate; and
orbiting scroll having an orbiting wrap projected from an orbiting base plate,
scroll compressor being configured to compress refrigerant in a
the fixed wrap and the orbiting wrap meshing with
one of an outer curve and an inner curve of each of the fixed wrap and the
curve that is an involute of a base circle and defined in an x-y
coordinate system by equation (1) and equation (2) by using an involute angle :
) of the base circle in the equation (1) and the equation
a product of a "function varying in a sinusoidal or
the involute angle " and a
circle radius a() is given
,
where a0 is a base-circle radius
function, N is a natural number greater than or equal to 1,
5 [Claim 3]
The scroll compressor of claim 2, wherein
whose value changes alternately
[Claim 4]
The scroll compressor of any one of claims 1 to 3,
10 wherein when the curve defined by the
outer curve, the inner curve of each of the
envelope to a group of circles,
orbit radius of the orbiting scroll and having a center lying on a curve
by rotating the outer curve by
15 wherein when the curve defined by t
inner curve, the outer curve of each of the fixed wrap and the orbiting wrap is an inner
envelope to a group of circles, the
orbit radius of the orbiting scrol
by rotating the inner curve by
[Claim 5]
The scroll compressor of any one of claims 1 to
plate has a flattened outer shape.