U.S. patent application number 12/136804 was filed with the patent office on 2008-12-11 for scroll fluid machine.
This patent application is currently assigned to Hitachi Appliances, Inc.. Invention is credited to Masashi Miyake, Masaru OHTAHARA, Kazuo Sakurai, Kenji Tojo.
Application Number | 20080304994 12/136804 |
Document ID | / |
Family ID | 40096058 |
Filed Date | 2008-12-11 |
United States Patent
Application |
20080304994 |
Kind Code |
A1 |
OHTAHARA; Masaru ; et
al. |
December 11, 2008 |
Scroll Fluid Machine
Abstract
A scroll fluid machine is configured by engaging a fixed scroll
and an orbiting scroll having spiral bodies formed on base plates.
A seal member is provided between a rear surface of the orbiting
scroll and a frame member arranged opposite thereto to divide a
rear side chamber into an inner space and an outer space. The inner
space inside the seal member is subjected to a pressure
substantially corresponding to a discharge pressure, and the outer
space is subjected to a pressure lower than that of an inner back
pressure chamber to press the orbiting scroll against the fixed
scroll. The scroll members are formed such that the width of a
groove and the thickness of a tooth of the spiral body formed
inside the seal member are larger than those of the spiral body
formed outside the seal member.
Inventors: |
OHTAHARA; Masaru; (Shizuoka,
JP) ; Miyake; Masashi; (Shizuoka, JP) ; Tojo;
Kenji; (Moriya, JP) ; Sakurai; Kazuo;
(Shizuoka, JP) |
Correspondence
Address: |
ANTONELLI, TERRY, STOUT & KRAUS, LLP
1300 NORTH SEVENTEENTH STREET, SUITE 1800
ARLINGTON
VA
22209-3873
US
|
Assignee: |
Hitachi Appliances, Inc.
|
Family ID: |
40096058 |
Appl. No.: |
12/136804 |
Filed: |
June 11, 2008 |
Current U.S.
Class: |
418/55.1 ;
417/410.5; 418/55.2; 418/55.4; 418/55.6 |
Current CPC
Class: |
F04C 18/0215 20130101;
F04C 27/007 20130101; F04C 23/008 20130101 |
Class at
Publication: |
418/55.1 ;
418/55.2; 418/55.4; 418/55.6; 417/410.5 |
International
Class: |
F04C 18/02 20060101
F04C018/02; F04C 29/02 20060101 F04C029/02 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 11, 2007 |
JP |
2007-153467 |
Claims
1. A scroll fluid machine comprising two scroll members each of
which has a spiral body formed on a base plate, the scroll members
being engaged to relatively gyrate such that a hermetic space
formed by both scroll members is increased or reduced to make fluid
expand or compress the fluid, wherein: the scroll fluid machine is
configured such that a seal member is provided between a rear
surface of one of the scroll members and a stationary member to
divide a space formed between the rear surface and the stationary
member into an inner side space and an outer side space, the inner
side space inside the seal member being subjected to a pressure
substantially corresponding to a discharge pressure, the outer side
space outside the seal member being subjected to a pressure lower
than that in the inner side space to press the one scroll member
against the other scroll member; and the shape of the spiral body
of each scroll member is configured such that the width of a groove
of the spiral body of the scroll member and the thickness of a
tooth of the spiral body decrease from a central portion toward an
outer side of the spiral body over a part of or the whole of the
spiral body.
2. The scroll fluid machine according to claim 1, wherein a part of
or the whole of the spiral body of each scroll member is formed by
an involute of a circle (base circle) the radius of which varies
depending on an involute angle.
3. The scroll fluid machine according to claim 1, wherein each
scroll member is formed such that the width of a groove and the
thickness of a tooth of the spiral body formed inside the seal
member are larger than those of the spiral body formed outside the
seal member.
4. The scroll fluid machine according to claim 2, wherein each
scroll member is formed such that a radius of the base circle for
forming the spiral body formed inside the seal member is larger
than that of the base circle for forming the spiral body formed
outside the seal member.
5. The scroll fluid machine according to claim 4, wherein the
spiral body of each scroll member is formed by an involute of a
circle represented by the formula of: a=as+f(.lamda.)
(f'(.lamda.)<0) wherein a is a radius of the base circle,
.lamda. is an involute angle, and as is a radius of the base circle
at a beginning portion of winding of the spiral body.
6. A scroll fluid machine comprising a fixed scroll and an orbiting
scroll each of which has a spiral body formed on a base plate, the
fixed scroll and the orbiting scroll being engaged, wherein: the
scroll fluid machine is configured such that a seal member is
provided between a rear surface of the orbiting scroll and a frame
member arranged opposite to the rear surface to divide a space
formed between the rear surface and the frame member into an inner
side space and an outer side space, the inner side space inside the
seal member being subjected to a pressure substantially
corresponding to a discharge pressure, the outer side space outside
the seal member being subjected to a pressure lower than that in
the inner side space to press the orbiting scroll against the fixed
scroll; and each of the orbiting scroll and the fixed scroll is
formed such that the width of a groove and the thickness of a tooth
of the spiral body formed inside the seal member are larger than
those of the spiral body formed outside the seal member.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a scroll fluid machine
which is a kind of positive displacement fluid machine used for a
compressor, a vacuum pump, an expander and the like, and is
suitable for a scroll compressor in particular.
[0003] 2. Description of Related Art
[0004] Conventional scroll fluid machines are described in
JP-A-08-121366 and JP-A-2004-293531.
[0005] In the one disclosed in JP-A-08-121366, a seal ring is
provided between a seal surface on a wrap opposite side (on a rear
chamber side) of an orbiting scroll member and a frame facing the
seal surface and is held in a ring-shaped groove in the frame, and
this seal ring divides an inner space which is located in the
central portion and is at a pressure substantially equal to a
discharge pressure and in which an oil supply path is opened to
introduce lubricating oil accumulated in a bottom portion in a
hermetic container to an upper portion, from an outer space which
is located in an outer peripheral portion and is maintained at an
intermediate pressure between a suction pressure and the discharge
pressure.
[0006] By this division, pressure acts on the orbiting scroll
member, depending on the pressures of both inner space and outer
space, to press the orbiting scroll member to a fixed scroll member
to achieve sealing between both members.
[0007] Further, a required minimum amount of lubricating oil is
leaked on a top end surface of the seal ring from the inner space
to the outer space by means of pressure difference, and a major
part of residual lubricating oil remaining in the inner space is
returned to the bottom portion in the hermetic container without
allowing the residual oil to be mixed with compressed gas in the
hermetic container. By this configuration, high reliability of a
bearing, excellent compression efficiency, and low oil loss level
can be obtained.
BRIEF SUMMARY OF THE INVENTION
[0008] In the case of the scroll fluid machines described in the
prior arts described in JP-A-08-121366 and JP-A-2004-293531, since
the inner space on the rear chamber side of the orbiting scroll
member is subjected to the discharge pressure, and the outer space
is subjected to the intermediate pressure between the suction
pressure and the discharge pressure, there is the possibility that
pressing force on the central portion side of the orbiting scroll
member to the fixed scroll member becomes excessive to cause
seizing and scoring on sliding surfaces of both scrolls.
[0009] An object of the present invention is to provide a scroll
fluid machine which can prevent occurrence of seizing and scoring
on the sliding surfaces of both scrolls by appropriately adjusting
pressing force by which one scroll member is pressed against the
other scroll member.
[0010] In order to achieve the above object, the present invention
provides a scroll fluid machine in which two scroll members having
spiral bodies formed on base plates are engaged to perform relative
gyrating movement to enlarge or reduce a hermetic space formed by
both scroll members so as to make fluid expand or compress the
fluid, wherein the scroll fluid machine is configured such that the
rear surface of one of the scroll members is divided into an inner
space and an outer space by providing a seal member between the
rear surface and a stationary member, and the inner space inside
the seal member is subjected to a pressure substantially
corresponding to a discharge pressure and the outer space outside
the seal member is subjected to a pressure lower than that in an
inner back pressure chamber so as to be pressed against the other
scroll member, and wherein the shapes of the spiral bodies of the
scroll members are configured such that widths of grooves of the
spiral bodies of the scroll members decrease, and thicknesses of
teeth of the spiral bodies also decrease, from central portions
toward outer sides of the spiral bodies over a part of or the whole
of the spiral bodies.
[0011] Here, it is preferable that a part of or the whole of the
spiral body of the scroll member is formed by an involute of a
circle (a base circle) having a radius which varies depending on an
involute angle.
[0012] In addition, it is preferable that the scroll member is
formed such that the groove width and the tooth thickness of the
spiral body formed inside the seal member are larger than those of
the spiral body formed outside the seal member.
[0013] Further, it is preferable that the scroll member has a
radius where a radius of the base circle for forming the spiral
body formed inside the seal member has a radius larger than that of
the base circle for forming the spiral body formed outside the seal
member. Here, the spiral body of the scroll member is formed
preferably by an involute of a circle represented by:
a=as+f(.lamda.) (f'(.lamda.)<0)
wherein a is a radius of the base circle, .lamda. is an involute
angle, and as is a radius of the base circle at a beginning portion
of winding of the spiral body.
[0014] Another feature of the present invention is that, in a
scroll fluid machine configured by engaging a fixed scroll and an
orbiting scroll having spiral bodies formed on base plates, the
scroll fluid machine is configured such that a seal member is
provided between the rear surface of the orbiting scroll and a
frame member arranged opposite thereto to define an inner space and
an outer space, and the inner space inside the seal member is
subjected to a pressure substantially corresponding to a discharge
pressure and the outer space outside the seal member is subjected
to a pressure lower than that of an inner back pressure chamber to
press the orbiting scroll against the fixed scroll, and wherein the
orbiting scroll and the fixed scroll are formed such that the width
of a groove and the thickness of a tooth of the spiral body formed
inside the seal member are larger those of the spiral body formed
outside the seal member.
[0015] According to the present invention, since the shape of the
spiral body of the scroll member is configured such that the width
of the groove of the spiral body of the scroll member decreases and
the thickness of the tooth of the spiral body also decreases from
the central portion toward the outer side of the spiral body over a
part of or the whole of the spiral body, it is possible to properly
adjust pressing force by which one scroll member is pressed against
the other scroll member, and to obtain a scroll fluid machine which
can prevent occurrence of seizing and scoring on the sliding
surfaces of the scroll members.
[0016] Other objects, features and advantages of the invention will
become apparent from the following description of an embodiment of
the invention taken in conjunction with the accompanying
drawings.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0017] FIG. 1 is a vertical sectional view showing an embodiment of
a scroll fluid machine of the present invention;
[0018] FIG. 2 is a view illustrating pressures acting on an
orbiting scroll; and
[0019] FIGS. 3A and 3B are a plan view and a vertical sectional
view, respectively, of the orbiting scroll shown in FIG. 1.
DETAILED DESCRIPTION OF THE INVENTION
[0020] An embodiment of the present invention will be described
below using the drawings. A part denoted by the same reference
numeral in the figures indicates the same part or a corresponding
part.
Embodiment 1
[0021] An embodiment of the present invention will be described
using FIGS. 1, 2 and 3. FIG. 1 is a vertical sectional view of a
scroll compressor, FIG. 2 is a view illustrating pressures acting
on an orbiting scroll, and FIGS. 3A and 3B are a plan view and a
vertical sectional view of the orbiting scroll shown in FIG. 1,
respectively.
[0022] In a scroll compressor 1, a compression mechanism portion 2,
and a drive portion 3 which drive the compression mechanism portion
and a rotational shaft 300 are accommodated in a hermetic container
700. FIG. 1 shows a vertical type scroll compressor, in which the
drive portion 3 is disposed below the compression mechanism portion
2 via the rotational shaft 300, an oil reservoir 730 is disposed
below the drive portion 3, and the compression mechanism portion 2
and the drive portion 3 are connected via the rotational shaft
300.
[0023] The compression mechanism portion 2 is configured from base
elements of a fixed scroll 100, an orbiting scroll 200 and a frame
400, the frame 400 is fixed to the hermetic container 700, and a
roller bearing 401 supporting the rotational shaft is disposed. The
fixed scroll 100 is configured from base components of a base plate
101, a scroll spiral body 102, a suction port 103 and a discharge
port 104, and is fixed to the frame 400 by a bolt 405. The scroll
spiral body 102 is vertically provided upright on a surface on one
side of the base plate 101. The orbiting scroll 200 is configured
from base components of a base plate 201, a scroll spiral body 202,
an orbiting scroll bearing portion 203 in which a sliding bearing
210 is disposed, and a back pressure hole formed in the base plate
201 to provide communication between a compression chamber and a
back pressure chamber on a base plate rear side. The scroll spiral
body 202 is vertically provided upright on a fixed scroll side of
the base plate 201. The orbiting scroll bearing portion 203 is
formed in the central portion on a spiral body opposite side of the
base plate 201 to protrude vertically. The orbiting scroll 200 is
fabricated by working a cast made of materials such as cast iron
and aluminum.
[0024] The fixed scroll 100 and the orbiting scroll 200 are engaged
to form the compression chamber 130. In the compression chamber
130, the orbiting scroll 200 gyrates to reduce the volume thereof
to perform compression operation. In this compression operation, in
connection with the gyrating movement of the orbiting scroll 200, a
working fluid is sucked into the compression chamber 130 from a
suction pipe 711 and the suction port 103, and the sucked working
fluid is discharged in the hermetic container 700 from a discharge
port 104 of the fixed scroll 100 after the compression process, and
further discharged out of the hermetic container 700 via a
discharge pipe 701. In this way, the space in the hermetic
container 700 is maintained at a discharge pressure. As a working
fluid to be compressed in the compression mechanism portion, an
earth-friendly high pressure refrigerant such as R410A is used
generally.
[0025] The hermetic container 700 has an upper cap 710 and a lower
cap 720, which are fitted to cover an outer side of a middle
cylindrical portion of the hermetic container, and is configured by
heating and welding the fitting end portions by using a welding
torch obliquely from below and obliquely from above. A leg portion
721 is attached to a bottom surface of the hermetic container 700,
and a magnet 722 is disposed inside the lower cap 720 to collect
coarse particulates in the compressor. Further, a hermetic terminal
702 and a terminal cover 703 are provided on a side surface of the
hermetic container 700 so as to be able to supply electric power to
an electric motor 600. The hermetic terminal 702 is provided to
pass through the hermetic container, and is positioned between an
end coil of a stator 601 and the frame 400. In addition, a
discharge pipe 701 is provided on an opposite side to the hermetic
terminal 702 on the side surface of the hermetic container to pass
through the hermetic container, and is provided above a balance
weight 407.
[0026] The drive portion 3 for rotationally driving the orbiting
scroll 200 is configured from base elements of the electric motor
600 having the stator 601 and a rotor 602, the rotational shaft
300, an oil supply pump 900, an Oldham coupling 500 constituting a
rotation-preventing mechanism for the orbiting scroll, the frame
400, roller bearings 401, 803, the orbiting scroll bearing portion
203, the sliding bearing 210 disposed in the orbiting scroll
bearing portion, and the like.
[0027] The rotational shaft 300 is configured from a main shaft
portion 302, a crank pin 301 and an auxiliary bearing support
portion 303. The main shaft portion 302 and the auxiliary bearing
support portion 303 are formed coaxially to constitute a main shaft
part, and further, the oil supply pump 900 is press-fitted into a
lower end portion of the rotational shaft 300. The roller bearings
401, 803 rotatably support the main shaft portion 302 and the
auxiliary bearing support portion 303, respectively, of the
rotational shaft. The sliding bearing 210 is press-fitted in the
orbiting scroll bearing portion 203, and is engaged with the crank
pin 301 of the rotational shaft so as to be movable in an axial
direction and rotatable.
[0028] The roller bearing 401 (the main bearing) is arranged on an
upper side of the electric motor 600, and the roller bearing 803
(the auxiliary bearing) is arranged on a lower side of the electric
motor 600. In the present embodiment, since the rotational shaft
300 is supported by the roller bearings 401, 803 in both sides of
the electric motor 600, it is possible to suppress power loss and
prevent the rotational shaft from tilting.
[0029] A housing 802 is fixed via a bolt 805 to a lower frame 801
fixed to the hermetic container 700, the roller bearing 803 is
inserted in the housing 802 from above, and a housing cover 804 is
further attached thereto from above.
[0030] The oil supply pump 900 is a centrifugal pump attached to
the lower end of the rotational shaft 300, and forcibly supplies
the lubricating oil stored in the oil reservoir 730 to the
auxiliary bearing 803, the orbiting scroll bearing portion 203 and
the main bearing 401 through an oil supply hole 901. The oil
supplied to the oil supply hole 901 is also supplied to sliding
portions of the orbiting scroll and the fixed scroll. The oil
supply hole 901 is provided so as to pass through the rotational
shaft 300 vertically, and has a lower oil supply hole which is
concentric with respect to the axis of the rotational shaft and an
upper oil supply hole which is eccentric with respect to the axis
of the rotational axis. A lateral oil supply hole (the lateral
hole) is provided so as to communicate with the lower oil supply
hole to supply the oil to the auxiliary bearing 803.
[0031] The Oldham coupling 500 is disposed on the rear of the base
plate 201 of the orbiting scroll 200. One of two set of orthogonal
key portions formed in the Oldham coupling slides in a key groove
formed in the frame 400, and the other set slides in a key groove
formed in the rear side of the orbiting scroll spiral body 202. As
a result, the orbiting scroll gyrates with respect to the fixed
scroll 100 in a plane perpendicular to the axial direction in which
direction the scroll spiral body is provided upright, without
rotating on its own axis.
[0032] In the compression mechanism portion 2, when the crank pin
301 eccentrically rotates by rotation of the rotational shaft 300
coupled to the electric motor 600, the orbiting scroll gyrates with
respect to the fixed scroll by the Oldham coupling (the
rotation-preventing mechanism) to suck gas into the compression
chamber 130 formed by the scroll spiral bodies 102 and 202 through
the suction pipe 711 and the suction port 103. By the gyrating
movement of the orbiting scroll, the compression chamber reduces
the volume while moving to the central portion to compress the gas,
and the compressed gas is discharged from the discharge port 104 to
the discharge chamber. The gas discharged to the discharge chamber
passes around the compression mechanism portion 2 to flow into an
electric motor chamber, and is thereafter released from the
discharge pipe 701 to the outside of the compressor.
[0033] A back pressure hole (not shown) providing communication
between the compression chamber 130 and the back pressure chamber
411 on the rear side of the orbiting scroll is provided in the base
plate 201 of the orbiting scroll 200, to maintain the pressure in a
space of the back pressure chamber 411 outside a seal ring at a
pressure (an intermediate pressure) between a suction pressure and
a discharge pressure. The back pressure chamber 411 formed on the
rear side of the orbiting scroll is a space formed by the orbiting
scroll 200, the frame 400 and the fixed scroll 100. The frame 400
also serves as a member for forming the back pressure chamber 411,
and the seal ring 410 provided in a groove of the frame 400
partitions the back pressure chamber 411 into an inner space
substantially at the discharge pressure and an outer space at the
intermediate pressure.
[0034] As shown in FIG. 2, the orbiting scroll 200 is pressed
against the fixed scroll 100 through the seal ring 410 due to the
resultant force by pressures in an inner space (the inner back
pressure chamber) 412 which is substantially under a discharge
pressure and an outer space (the outer back pressure chamber) 413
which is under an intermediate pressure. On the other hand, the
orbiting scroll 200 receives force to be separated from the fixed
scroll 100 by pressure in the compression chamber 130 formed by the
orbiting scroll 200 and the fixed scroll 100. Accordingly, in order
to press the orbiting scroll to the fixed scroll side with a proper
force, the pressure (the intermediate pressure) in the space 413
outside the seal ring is set to satisfy the formula of:
Pressing Force.gtoreq.Separating Force
[0035] As described above, in the present embodiment, while a
pressure substantially corresponding to the discharge pressure acts
in the inner space divided by the seal ring 410, and a pressure (an
intermediate pressure) lower than that in the inner back pressure
chamber acts in the space outside the seal member press the
orbiting scroll against the fixed scroll, since the discharge
pressure acts in the inner space 412, the force pressing the
central portion of the orbiting scroll is far greater than the
force pressing the outer peripheral portion side of the orbiting
scroll. Accordingly, it has been found that there is the problem
that surface pressures on the sliding surface of a tip end of the
orbiting scroll spiral body 202 with respect to the fixed scroll
100 and the sliding surface of a tip end of the fixed scroll spiral
body 102 with respect to the orbiting scroll 200 become excessive,
which easily causes seizing and scoring.
[0036] In order to solve this problem, in the present embodiment,
the shape of the spiral body 202 of the orbiting scroll 200 is
configured such that the groove width of the spiral body decreases
from the central portion toward the outside of the spiral body in a
part of or the whole of the spiral body, and is formed such that
the tooth thickness of the spiral body also decreases, as shown in
FIGS. 3A and 3B. The spiral body 102 of the fixed scroll 100 is
formed also in the same way as the spiral body 202 of the orbiting
scroll.
[0037] It is more preferable to form the groove width and the tooth
thickness of the spiral body formed inside the seal ring 410 to be
larger than the groove width and the tooth thickness of the spiral
body formed outside the seal ring. Such a spiral body shape can be
fabricated by forming a part of or the whole of the spiral body by
an involute of a circle (a base circle) a a radius of which varies
in accordance with an involute angle. More specifically, the base
circle for forming the spiral body formed inside the seal ring 410
is configured to have a radius larger than that of the base circle
for forming the spiral body formed outside the seal ring 410.
[0038] Here, the spiral body of the scroll member can be formed by
an involute of a circle represented by the formula of:
a=as+f(.lamda.) (f'(.lamda.)<0)
wherein a is the radius of the base circle, .lamda. is the involute
angle, and as is the radius of the base circle at the beginning
portion of winding of the spiral body.
[0039] According to the present embodiment, by the above
configuration, it is possible to increase the ratio of the area of
the compression space under a higher pressure inside the seal ring
with respect to the compression space outside the seal ring, so
that depressing force on the orbiting scroll member can be
increased, and as a result, it is possible to prevent pressing
force of the orbiting scroll member from becoming excessively
large. In particular, since the back pressure chamber (the inner
space) inside the seal ring is substantially subjected to a
discharge pressure, pressing force is strong in the central portion
of the orbiting scroll. However, in the present embodiment, the
area of the compression chamber under high pressure on the central
portion side can be made larger among the compression chamber
formed by both scroll members, and therefore separating force on
the central portion side can be increased, and the surface
pressures of the sliding surfaces of the tip ends of the spiral
bodies of both scroll members can be maintained appropriately,
which provide an effect of reliably preventing occurrence of
seizing and scoring on the sliding surfaces.
[0040] In the meanwhile, if the spiral bodies of the scroll members
have a shape in which the groove width and the tooth thickness are
uniform over the whole spiral body from the central portion of the
spiral body toward the outside like a conventional one, since the
outermost diameter of the spiral body becomes large, the base plate
201 becomes large, the area which is subjected to the intermediate
pressure becomes large, and the force to press the whole orbiting
scroll against the fixed scroll becomes large. If the whole
pressing force becomes large, the sliding resistance between the
orbiting scroll base plate and the fixed scroll panel board surface
also becomes large, which further increases the risk of scoring and
seizing. It is conceivable to make the back pressure hole
communicate with the lower pressure side of the compression chamber
so as to set the intermediate pressure to be low, however, if the
back pressure hole communicates with the lower pressure side of the
compression chamber, since pressure fluctuation in that compression
chamber is small, the pressure of the back pressure chamber under
the intermediate pressure remains low even if the separating force
generated by the pressure of the whole compression chamber
fluctuates widely. Therefore, the value of the pressing force can
not sufficiently follow the fluctuation of the separating force,
which makes it impossible to expand the operating range.
[0041] In the present embodiment, since a part of or the whole of
the spiral bodies is formed such that the groove width of the
spiral bodies of both scroll members varies and the tooth thickness
of the spiral bodies of both scroll members decreases from the
center toward the outside of the spiral bodies, the outermost
diameter of the spiral bodies can be made small and the scroll
members can be reduced in diameter. In addition, since the area of
the rear side of the orbiting scroll upon which the intermediate
pressure acts can be made small, the pressure in the back pressure
chamber upon which the intermediate pressure acts can be set
larger. Therefore, according to the present embodiment, it becomes
possible to make the back pressure hole communicate with the higher
pressure side of the compression chamber and to allow the value of
the pressing force to sufficiently follow the fluctuation of the
separating force, so that the operation range can be readily
expanded, and also an effect of further reducing the risk of
scoring and seizing by reducing the sliding resistance between the
orbiting scroll base plate and the fixed scroll panel board
surface. As described above, according to the present embodiment,
since the high pressure region in the back pressure chamber can be
increased in comparison with the conventional scroll spiral bodies,
the equilibrium of the forces in the axial direction of the
orbiting scroll can be kept in a wider operation range.
[0042] Thus, according to the present embodiment, it is possible to
obtain a scroll fluid machine which can improve the efficiency with
high reliability and which can achieve reduction in diameter of
scroll members.
[0043] In the present embodiment, the inner diameter of the seal
ring 410 is smaller than the outer diameter of the roller bearing
401. Therefore, the embodiment is configured such that the roller
bearing 401 is inserted from the electric motor side to the frame
400 and is fixed by a frame cover 403. The frame cover 403 is
provided with a thrust bearing and is fixed to the frame 400 by a
bolt 406. By this bolt fixation, the gap between the frame cover
and the frame can be precisely sealed so that oil leakage from the
oil supply path can be suppressed.
[0044] The balance weight 407 is pressed into the rotational shaft
300 in the electric motor side of the roller bearing 401 to be
fixed there. The maximum outer diameter portion of the balance
weight 407 is provided on an end surface side of the coil end of
the stator 601 and has a diameter larger than the inner diameter of
the coil end.
[0045] Next, the oil supply path will be described. When the
rotational shaft 300 starts rotating, oil in the oil reservoir 730
under discharge pressure is supplied to an oil passage 311 in the
rotational shaft by raising the pressure by the oil supply pump
900. A part of the oil fed to the oil passage 311 flows to the
auxiliary bearing 803 through a lateral hole 312 and thereafter
returns to the oil reservoir 730. The oil reaching an upper portion
of the crank pin 301 through the oil passage 311 lubricates the
sliding bearing (the gyration bearing) 210 and further flows to the
roller bearing 401. Most of the oil having lubricated the roller
bearing 401 returns to the oil reservoir 730 through an oil drain
pipe 408. Since the space inside the seal ring 410 is supplied with
the oil from the oil reservoir 730 which is under the discharge
pressure, the space is filled with the oil substantially under the
discharge pressure.
[0046] An oil supply pocket (a concave groove) 205 is formed in the
end face of the orbiting scroll bearing portion 203. The oil supply
pocket 205 reciprocates across the seal ring 410 between the
outside and inside thereof by the gyrating movement of the orbiting
scroll 200, and conveys a part of the oil existing between the
sliding bearing 210 and the roller bearing 401 to the back pressure
chamber 411 in the space outside the seal ring. The conveyed oil
lubricates the Oldham coupling 500 as well as the sliding surfaces
between a panel board surface 105 of the fixed scroll and the base
plate 201 of the orbiting scroll 200. Thereafter, the oil flows
into the compression chamber 130 through the back pressure hole or
a minute gap of the panel board sliding surface. The oil flowing
into the compression chamber 130 is discharged from the discharge
port 104 together with the compressed refrigerant gas, is separated
from the refrigerant gas in the hermetic container 700, and returns
to the oil reservoir 730. The back pressure chamber 411 in the
space outside the seal ring is substantially under the same
pressure as the compression chamber communicating with the back
pressure hole, that is, under the intermediate pressure between the
discharge pressure and the suction pressure, due to the back
pressure hole.
[0047] As mentioned above, the back pressure chamber of the
orbiting scroll is constituted by the inner space under discharge
pressure inside the seal ring and the outer space under
intermediate pressure outside the seal ring, and the orbiting
scroll receives pressing force according to the sum of the
discharge pressure of the inner space and the intermediate pressure
of the outer space. Since the orbiting scroll also receives
separating force due to the pressure in the compression chamber
formed by both scroll members, the orbiting scroll will be finally
pressed to the fixed scroll side by the pressing force minus the
separating force. Since the inner space is substantially under the
discharge pressure, the pressing force at the central portion of
the orbiting scroll becomes large. However, in the present
embodiment, since the area of the compression chamber under high
pressure on the central portion side among the compression chamber
formed by both scroll members is configured to be larger, the
separating force on the central portion side is also large.
Consequently, the sliding surfaces of the tip ends of the spiral
bodies of both scroll members can be maintained at a proper surface
pressure.
[0048] The flow of oil and refrigerant gas discharged from the
discharge port 104 will be described. The oil and the refrigerant
gas discharged from the discharge port flow through the fixed
scroll 100 and a passage (not shown) provided at the outer
periphery of the frame 400 into a D partition 423 provided in a
lower part of a leg portion 422 of the frame. The D partition 423
has two flow paths which are a window portion provided in the inner
periphery direction of the hermetic container and a minute gap
portion 424 provided at a lower end of the D partition. Most of the
oil and the refrigerant gas flowing into the D partition 423 exit
from the window portion provided in the inner periphery direction
of the hermetic container, and flow in a space between the frame
400 and the stator 601 along the inner periphery of the hermetic
container. A part of the oil and the refrigerant gas flowing out to
the gap portion 424 provided at the lower end of the D partition
423 passes through a stator outer periphery passage (not shown)
provided in the outer peripheral portion of the stator 601 and is
utilized for cooling the stator 601.
[0049] In connection with the oil and refrigerant gas flowing along
the inner periphery of the hermetic container 700, the oil with a
greater specific gravity flows while attaching to the inner
periphery of the hermetic container due to the effect of
centrifugal force, and is separated from the refrigerant gas. The
separated oil returns to the oil reservoir 730 through the stator
outer periphery passage. The refrigerant gas is released out of the
hermetic container through the discharge pipe 701.
[0050] It should be further understood by those skilled in the art
that although the foregoing description has been made on
embodiments of the invention, the invention is not limited thereto
and various changes and modifications may be made without departing
from the spirit of the invention and the scope of the appended
claims.
* * * * *