U.S. patent application number 10/592869 was filed with the patent office on 2008-11-06 for rotary expander.
Invention is credited to Eiji Kumakura, Michio Moriwaki, Masakazu Okamoto, Tetsuya Okamoto, Katsumi Sakitani.
Application Number | 20080274001 10/592869 |
Document ID | / |
Family ID | 34975641 |
Filed Date | 2008-11-06 |
United States Patent
Application |
20080274001 |
Kind Code |
A1 |
Okamoto; Masakazu ; et
al. |
November 6, 2008 |
Rotary Expander
Abstract
The upper and lower end surfaces (67b, 67c) of a rotary piston
(67) are formed with annular seal grooves (91) extending along the
annular end surfaces (67b, 67c), and an annular lip seal (92) is
fitted in each of the seal grooves (91). Thereby, the lubricating
oil fed from oil feed grooves (49) in the shaft (40) rarely flows
from between the upper and lower end surfaces (67b, 67c) of the
rotary piston (67) and front and rear heads (61, 62) and into the
fluid chamber (65) of a cylinder (63), so that shortage of
lubricating oil is eliminated.
Inventors: |
Okamoto; Masakazu; (Osaka,
JP) ; Moriwaki; Michio; (Osaka, JP) ;
Kumakura; Eiji; (Osaka, JP) ; Okamoto; Tetsuya;
(Osaka, JP) ; Sakitani; Katsumi; (Osaka,
JP) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Family ID: |
34975641 |
Appl. No.: |
10/592869 |
Filed: |
March 15, 2005 |
PCT Filed: |
March 15, 2005 |
PCT NO: |
PCT/JP2005/004502 |
371 Date: |
July 23, 2008 |
Current U.S.
Class: |
418/140 ;
418/141; 418/142; 418/60 |
Current CPC
Class: |
F16J 15/324 20130101;
F01C 19/08 20130101; F01C 1/3564 20130101 |
Class at
Publication: |
418/140 ;
418/141; 418/142; 418/60 |
International
Class: |
F01C 19/08 20060101
F01C019/08; F04C 27/00 20060101 F04C027/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 16, 2004 |
JP |
2004-074454 |
Claims
1. A rotary expander comprising an expansion mechanism (60) that
includes a cylinder (63) closed at both ends by closing members
(61, 62) and a rotary piston (67) placed in the cylinder (63),
wherein at lease one of the end surfaces of the rotary piston (67)
is provided with a sealing mechanism (90) for sealing the end
surfaces with respect to the closing members (61, 62).
2. The rotary expander of claim 1, further comprising a single
rotary shaft (40) having an eccentric part (41) rotatably fitted in
the rotary piston (67); and said rotary shaft (40) being formed
with an oil feeding channel (49) for feeding lubricating oil to at
least sliding areas formed by the eccentric part (41) and the
closing members (61, 62) and a sliding area between the rotary
piston (67) and the eccentric part (41).
3. The rotary expander of claim 2, wherein the expansion mechanism
(60) includes a plurality of rotary pistons (75, 85), the rotary
pistons (75, 85) are connected to each other through the single
rotary shaft (40) and juxtaposed so that the adjacent end surfaces
of the rotary pistons (75, 85) face each other with an intermediate
partition plate (64) interposed therebetween, and out of the end
surfaces of the plurality of rotary pistons (75, 85), the end
surfaces facing the closing members (61, 62) are individually
provided with the sealing mechanisms (90).
4. The rotary expander of any one of claims 1 to 3, wherein the
sealing mechanism (90) is constituted by a sealing groove (91)
formed in the end surface of the rotary piston (67) and a sealing
member (92) fitted in the sealing groove (91).
5. The rotary expander of claim 4, wherein the sealing member (92)
is a lip seal or a chip seal.
6. The rotary expander of any one of claims 1 to 3, wherein the
sealing mechanism (90) is a labyrinth seal.
7. The rotary expander of claim 4, wherein the sealing member (92)
is made of ethylene tetrafluoride-based resin material.
8. The rotary expander of claim 1, wherein the fit tolerance of the
rotary piston (67) in the axial direction of the rotary shaft (40)
is set at a size of 1/5000 to 1/1000 of the inner diameter D of the
cylinder (63).
Description
TECHNICAL FIELD
[0001] This invention relates to rotary expanders and particularly
relates to preventive measures against oil discharge.
BACKGROUND ART
[0002] Positive displacement expanders including rotary expanders
are conventionally known as expanders for generating power by
expansion of high-pressure fluid. Such a rotary expander is
disclosed, for example, in Published Japanese Patent Application
No. 2003-172244.
[0003] The above rotary expander comprises an expansion mechanism
that includes a cylinder closed at both ends by front and rear
heads and a piston placed in the cylinder. The expansion mechanism
is passed through by a shaft having an eccentric part rotatably
fitted in the piston. In the rotary expander, lubricating oil is
pumped up by an oil pump associated with the shaft and fed to the
expansion mechanism to lubricate it.
PROBLEMS TO BE SOLVED
[0004] In the above known rotary expander, however, excessive
feeding of lubricant oil to the expansion mechanism may cause a
problem that the lubricating oil excessively leaks into the
expansion chamber in the cylinder through between an end surface of
the piston and the front head or rear head. This may in turn create
a problem that the lubricating oil leaks out of the expander
together with refrigerant, i.e., causes a so-called oil discharge,
resulting in shortage of lubricating oil.
[0005] The present invention has been made in view of the above
points and, therefore, its object is to prevent excessive flow of
lubricating oil into the expansion chamber in the expansion
mechanism to eliminate the problem of shortage of lubricating oil,
thereby enhancing reliability.
DISCLOSURE OF THE INVENTION
[0006] The solutions taken by the present invention are as
follows.
[0007] Specifically, the first solution of the invention is
directed to a rotary expander comprising an expansion mechanism
(60) that includes a cylinder (63) closed at both ends by closing
members (61, 62) and a rotary piston (67) placed in the cylinder
(63). Further, at lease one of the end surfaces of the rotary
piston (67) is provided with a sealing mechanism (90) for sealing
the end surfaces with respect to the closing members (61, 62).
[0008] In the above solution, if both the end surfaces of the
rotary piston (67) are provided with sealing mechanisms (90),
respectively, the lubricating oil fed to the sliding areas of the
expansion mechanism (60) can be prevented from excessively leaking
into the expansion space in the cylinder (63) through between both
the end surfaces of the rotary piston (67) and the closing members
(61, 62). Also, if one end surface of the rotary piston (67) is
provided with a sealing mechanism (90), the one end surface
undergoes a higher pressure than the pressure of the lubricating
oil acting on the other end surface provided with no sealing
mechanism (90), so that the rotary piston (67) is pushed toward the
closing member (61, 62) associated with no sealing mechanism (90)
and then brought into substantially close contact with it. Thus,
like the case where both the end surfaces are provided with sealing
mechanisms (90), the lubricating oil can be prevented from
excessively leaking into the expansion space in the cylinder (63)
through between both the end surfaces of the rotary piston (67) and
the closing members (61, 62). Therefore, in either case, the
lubricating oil does not substantially flow out of the expansion
mechanism (60) together with the fluid in the expansion space,
which prevents oil discharge and in turn eliminates shortage of
lubricating oil.
[0009] The second solution of the invention is directed to the
first solution, wherein the rotary expander further comprises a
single rotary shaft (40) having an eccentric part (41) rotatably
fitted in the rotary piston (67). Further, the rotary shaft (40) is
formed with an oil feeding channel (49) for feeding lubricating oil
to at least sliding areas formed by the eccentric part (41) and the
closing members (61, 62) and a sliding area between the rotary
piston (67) and the eccentric part (41).
[0010] The above solution restrains leakage of lubricating oil fed
through the oil feeding channel (49) in the rotary shaft (40) to at
least the sliding areas formed by the eccentric part (41) and the
closing members (61, 62) and the sliding area between the rotary
piston (67) and the eccentric part (41).
[0011] The third solution of the invention is directed to the
second solution, wherein the expansion mechanism (60) includes a
plurality of rotary pistons (75, 85). The rotary pistons (75, 85)
are connected to each other through the single rotary shaft (40)
and juxtaposed so that the adjacent end surfaces of the rotary
pistons (75, 85) face each other with an intermediate partition
plate interposed therebetween. Further, out of the end surfaces of
the plurality of rotary pistons (75, 85), the end surfaces facing
the closing members (61, 62) are individually provided with the
sealing mechanisms (90).
[0012] According to the above solution, in each rotary piston (75,
85), the end surface facing the closing member (61, 62) undergoes a
higher pressure than the pressure of the lubricating oil acting on
the other end surface facing the intermediate partition plate (64),
so that the rotary piston (75, 85) is pushed toward the
intermediate partition plate (64) and then brought into
substantially close contact with it. Thus, even in the
multi-cylinder type expansion mechanism (60), there is no
possibility that during operation of the rotary pistons (75, 85)
the sealing mechanisms (90) are overlapped with the through hole
for the rotary shaft (40) formed in the intermediate partition
plate (64) and thereby damaged. This restrains leakage of
lubricating oil.
[0013] The fourth solution of the invention is directed to any one
of the first to third solutions, wherein the sealing mechanism (90)
is constituted by a sealing groove (91) formed in the end surface
of the rotary piston (67) and a sealing member (92) fitted in the
sealing groove (91).
[0014] According to the above solution, the end surface of the
rotary piston (67) is sealed with respect to the closing member
(61, 62) through close contact of the sealing member (92) with the
closing member (61, 62) and the sealing groove (91).
[0015] The fifth solution of the invention is directed to the
fourth solution, wherein the sealing member (92) is a lip seal or a
chip seal.
[0016] According to the above solution, the lip seal or the chip
seal comes into close contact with the closing member (61, 62) and
the sealing groove (91) by the action of pressure of the
lubricating oil. Thus, the end surface of the rotary piston (67) is
sealed with respect to the closing member (61, 62).
[0017] The sixth solution of the invention is directed to any one
of the first to third solutions, wherein the sealing mechanism (90)
is a labyrinth seal.
[0018] According to the above solution, the end surface of the
rotary piston (67) is sealed with respect to the closing member
(61, 62) by a labyrinth effect derived as from a frictional effect
due to viscosity of the lubricating oil and a contraction effect at
a throttling gap.
[0019] The seventh solution of the invention is directed to the
fourth or fifth solution, wherein the sealing member (92) is made
of ethylene tetrafluoride-based (PTFE-based) resin material.
[0020] According to the above solution, since the ethylene
tetrafluoride-based resin material is a material having excellent
abrasion resistance and heat resistance, the end surface of the
rotary piston (67) is surely sealed with respect to the closing
member (61, 62).
[0021] The eighth solution of the invention is directed to any one
of the first to seventh solutions, wherein the fit tolerance of the
rotary piston (67) in the axial direction of the rotary shaft (40)
is set at a size of 1/5000 to 1/1000 of the inner diameter D of the
cylinder (63).
[0022] According to the above solution, there is no need to
strictly manage the processing precision and the assembly precision
of the rotary piston (67), which provides cost reduction.
EFFECTS
[0023] According to the first solution, since at least one end
surface of the rotary piston (67) is provided with a sealing
mechanism (90) for sealing the end surface with respect to the
closing members (61, 62), this restrains the lubricating oil fed to
the sliding areas of the expansion mechanism (60) from leaking into
the expansion space. Thus, the lubricating oil does not
substantially flow out of the expansion mechanism (60) together
with expanded fluid, which prevents oil discharge and in turn
shortage of lubricating oil. As a result, the reliability of the
rotary expander can be enhanced.
[0024] Furthermore, particularly, if the rotary expander is
integrated with a compressor to form a so-called high-pressure dome
type expander and used, for example, in a refrigerant circuit
operating in a vapor compression refrigeration cycle, the
lubricating oil is heated by high-temperature and high-pressure gas
refrigerant to reach high temperature and the refrigerant flowing
into the expansion mechanism (60) has relatively low temperature.
In this case, since, as described above, the leakage of lubricating
oil into the expansion space is restrained, this hinders the
low-temperature refrigerant from being mixed with the
high-temperature lubricating oil and thereby heated, thereby
preventing heat loss in the course of expansion. As a result, the
operation efficiency can be enhanced.
[0025] According to the second solution, even in the expansion
mechanism (60) having a lubrication system for feeding the
lubricating oil through the oil feeding channel (49) formed in the
rotary shaft (40), the lubricating oil can be restrained from
leakage into the expansion space.
[0026] According to the third solution, since in the multi-cylinder
type expansion mechanism (60) the sealing mechanisms (90) are
provided not at the end surfaces of the rotary pistons (75, 85)
facing the intermediate partition plate (64) but at the end
surfaces thereof facing the closing members (61, 62), there is no
possibility that during operation the sealing mechanisms (90) are
overlapped with the through hole for the rotary shaft (40)
relatively widely formed in the intermediate partition plate (64)
and damaged. This restrains leakage of lubricating oil.
[0027] According to the fourth solution, since the sealing
mechanism (90) is constituted by a sealing groove (91) and a
sealing member (92) fitted in the sealing groove (91), the end
surface of the rotary piston (67) can be sealed with respect to the
closing member (61, 62) through close contact of the sealing member
(92) with the closing member (61, 62) and the sealing groove
(91).
[0028] According to the fifth solution, since the sealing member
(92) is a lip seal or a chip seal, the lip seal or the chip seal
can be surely brought into close contact with the closing member
(61, 62) and the sealing groove (91) by the action of pressure of
the lubricating oil. Thus, the end surface of the rotary piston
(67) can be surely sealed with respect to the closing member (61,
62).
[0029] According to the sixth solution, since the sealing mechanism
(90) is a labyrinth seal, the end surface of the rotary piston (67)
can be surely sealed with respect to the closing member (61, 62) by
a labyrinth effect.
[0030] According to the seventh solution, since the sealing member
(92) is made of ethylene tetrafluoride-based resin material having
excellent abrasion resistance and heat resistance, high sealing
performance can be ensured even during its sliding on the closing
members (61, 62) owing to the rotation of the rotary piston
(67).
BRIEF DESCRIPTION OF DRAWINGS
[0031] FIG. 1 is a piping diagram showing an air conditioner.
[0032] FIG. 2 is a longitudinal cross-sectional view showing a
compression/expansion unit in Embodiment 1.
[0033] FIG. 3 is a horizontal cross-sectional view schematically
showing essential parts of an expansion mechanism in Embodiment
1.
[0034] FIG. 4 is a longitudinal cross-sectional view schematically
showing essential parts of the expansion mechanism in Embodiment
1.
[0035] FIG. 5 illustrates horizontal cross-sectional views showing
the states of the expansion mechanism in Embodiment 1 at every
90.degree. of rotation angle of a rotary shaft, wherein a sealing
mechanism is not given.
[0036] FIG. 6 is a horizontal cross-sectional view schematically
showing essential parts of an expansion mechanism in Embodiment
2.
[0037] FIG. 7 is a longitudinal cross-sectional view schematically
showing essential parts of the expansion mechanism in Embodiment
2.
[0038] FIG. 8 is a horizontal cross-sectional view schematically
showing essential parts of an expansion mechanism in Embodiment
3.
[0039] FIG. 9 is a horizontal cross-sectional view schematically
showing essential parts of an expansion mechanism in Embodiment
4.
[0040] FIG. 10 is a horizontal cross-sectional view schematically
showing essential parts of an expansion mechanism in Embodiment
5.
[0041] FIG. 11 is a longitudinal cross-sectional view schematically
showing essential parts of the expansion mechanism in Embodiment
5.
[0042] FIG. 12 is a longitudinal cross-sectional view showing a
compression/expansion unit in Embodiment 6.
[0043] FIG. 13 is a longitudinal cross-sectional view schematically
showing essential parts of an expansion mechanism in another
embodiment.
BEST MODE FOR CARRYING OUT THE INVENTION
[0044] Embodiments of the present invention will be described in
detail with reference to the drawings.
Embodiment 1 of the Invention
[0045] A description is given of Embodiment 1 of the present
invention. As shown in FIG. 1, the air conditioner (10) in this
embodiment includes a rotary expander according to the present
invention.
[0046] <Overall Structure of Air-Conditioner>
[0047] As shown in FIG. 1, the air conditioner (10) is of so-called
separate type and includes an outdoor machine (11) and an indoor
machine (13). The outdoor machine (11) contains an outdoor fan
(12), an outdoor heat exchanger (23), a first four-way selector
valve (21), a second four-way selector valve (22) and a
compression/expansion unit (30). On the other hand, the indoor
machine (13) contains an indoor fan (14) and an indoor heat
exchanger (24). The outdoor machine (11) is installed outside the
room while the indoor machine (13) is installed in the room. The
outdoor machine (11) and indoor machine (13) are connected through
a pair of connection pipes (15, 16). The details of the
compression/expansion unit (30) will be given later.
[0048] The air conditioner (10) is provided with a refrigerant
circuit (20). The refrigerant circuit (20) is a closed circuit in
which the compression/expansion unit (30) and the indoor heat
exchanger (24) are connected. The refrigerant circuit (20) is
filled with carbon dioxide (CO.sub.2) as a refrigerant.
[0049] The outdoor heat exchanger (23) and the indoor heat
exchanger (24) are each formed of a cross fin type fin-and-tube
heat exchanger. In the outdoor heat exchanger (23), the refrigerant
circulating through the refrigerant circuit (20) exchanges heat
with the outdoor air. In the indoor heat exchanger (24), the
refrigerant circulating through the refrigerant circuit (20)
exchanges heat with the room air.
[0050] The first four-way selector valve (21) has four ports. The
first four-way selector valve (21) is connected at the first port
to a discharge pipe (36) of the compression/expansion unit (30),
connected at the second port to one end of the indoor heat
exchanger (24) through the connection pipe (15), connected at the
third port to one end of the outdoor heat exchanger (23) and
connected at the fourth port to a suction port (32) of the
compression/expansion unit (30). Furthermore, the first four-way
selector valve (21) switches between a position in which the first
and second ports communicate with each other and the third and
fourth ports communicate with each other (the position shown in the
solid lines in FIG. 1) and a position in which the first and third
ports communicate with each other and the second and fourth ports
communicate with each other (the position shown in the broken lines
in FIG. 1).
[0051] The second four-way selector valve (22) has four ports. The
second four-way selector valve (22) is connected at the first port
to an outlet port (35) of the compression/expansion unit (30),
connected at the second port to the other end of the outdoor heat
exchanger (23), connected at the third port to the other end of the
indoor heat exchanger (24) through the connection pipe (16) and
connected at the fourth port to an inlet port (34) of the
compression/expansion unit (30). Furthermore, the second four-way
selector valve (22) switches between a position in which the first
and second ports communicate with each other and the third and
fourth ports communicate with each other (the position shown in the
solid lines in FIG. 1) and a position in which the first and third
ports communicate with each other and the second and fourth ports
communicate with each other (the position shown in the broken lines
in FIG. 1).
[0052] <Structure of Compression/Expansion Unit>
[0053] As shown in FIGS. 2 to 4, the compression/expansion unit
(30) includes a casing (31) that is a vertically long, cylindrical,
enclosed container. Arranged inside the casing (31) are a
compression mechanism (50), an electric motor (45) and an expansion
mechanism (60) in order from bottom to top.
[0054] The discharge pipe (36) is attached to the casing (31). The
discharge pipe (36) is located between the electric motor (45) and
the expansion mechanism (60) and communicated with the inner space
of the casing (31).
[0055] The electric motor (45) is disposed inside a longitudinally
middle portion of the casing (31). The electric motor (45) is
formed of a stator (46) and a rotor (47). The stator (46) is fixed
to the casing (31). The rotor (47) is placed inside the stator (46)
and concentrically passed through by a main spindle (44) of a shaft
(40). The shaft (40) constitutes a rotary shaft and has two lower
eccentric parts (58, 59) formed at its lower end and a single
large-diameter eccentric part (41) formed at its upper end.
[0056] The two lower eccentric parts (58, 59) are formed to have a
larger diameter than the main spindle (44) and to be eccentric with
respect to the axis of the main spindle (44), the lower of them
constitutes a first lower eccentric part (58) and the upper
constitutes a second lower eccentric part (59). The first lower
eccentric part (58) and the second lower eccentric part (59) have
opposite directions of eccentricity with respect to the axis of the
main spindle (44).
[0057] The large-diameter eccentric part (41) is formed to have a
larger diameter than the main spindle (44) and to be eccentric with
respect to the axis of the main spindle (44).
[0058] The compression mechanism (50) is constituted by a
oscillating piston type rotary compressor. The compression
mechanism (50) includes two cylinders (51, 52) and two pistons
(57). In the compression mechanism (50), a rear head (55), the
first cylinder (51), an intermediate plate (56), the second
cylinder (52) and a front head (54) are stacked in order from
bottom to top.
[0059] In the inside of each of the first cylinder (51) and the
second cylinder (52), a single cylindrical rotary piston (57) is
disposed. Though not shown, a tabular blade extends from the side
surface of the rotary piston (57) and is supported through a
rolling bush to the associated cylinder (51, 52). The rotary piston
(57) in the first cylinder (51) engages with the first lower
eccentric part (58) of the shaft (40). On the other hand, the
rotary piston (57) in the second cylinder (52) engages with the
second lower eccentric part (59) of the shaft (40). Each of the
rotary pistons (57, 57) slides with its inner periphery on the
outer periphery of the associated lower eccentric part (58, 59) and
slides with its outer periphery on the inner periphery of the
associated cylinder (51, 52). Thus, a compression chamber (53) is
defined between the outer periphery of each of the rotary pistons
(57, 57) and the inner periphery of the associated cylinder (51,
52).
[0060] The first cylinder (51) and the second cylinder (52) are
formed with single suction ports (32), respectively. Each suction
port (32) radially passes through the associated cylinder (51, 52)
and opens at the distal end into the inside of the cylinder (51,
52). Further, each suction port (32) is extended through a pipe to
the outside of the casing (31).
[0061] The front head (54) and the rear head (55) are formed with
single discharge ports, respectively. The discharge port in the
front head (54) brings the compression chamber (53) in the second
cylinder (52) into communication with the inner space of the casing
(31). The discharge port in the rear head (55) brings the
compression chamber (53) in the first cylinder (51) into
communication with the inner space of the casing (31). Further,
each discharge port is provided at the distal end with a discharge
valve formed of a lead valve and configured to be opened and closed
by the discharge valve. In FIG. 2, the discharge ports and
discharge valves are not given. Gas refrigerant discharged from the
compression mechanism (50) into the inner space of the casing (31)
passes through the discharge pipe (36) and is sent out of the
compression/expansion unit (30).
[0062] The bottom part of the casing (31) forms an oil reservoir
for reserving lubricating oil. At the lower end of the shaft (40),
a centrifugal oil pump (48) is disposed which is immersed in the
oil reservoir. The oil pump (48) is configured to pump up the
lubricating oil in the oil reservoir using the rotation of the
shaft (40). The shaft (40) has an oil feeding channel (49) formed
inside thereof to extend from its lower end to its upper end. The
oil feeding channel (49) is configured to supply the lubricating
oil pumped up by the oil pump (48) to sliding areas of the
compression mechanism (50) and the expansion mechanism (60).
[0063] The expansion mechanism (60) is of so-called oscillating
piston type and constitutes a rotary expander according to the
present invention. The expansion mechanism (60) includes a front
head (61), a rear head (62), a cylinder (63) and a rotary piston
(67). Further, the expansion mechanism (60) is provided with the
inlet port (34) and the outlet port (35).
[0064] In the expansion mechanism (60), the front head (61), the
cylinder (63) and the rear head (62) are stacked in order from
bottom to top. The cylinder (63) is closed at the lower end surface
by the front head (61) and closed at the upper end surface by the
rear head (62). In other words, the front head (61) and the rear
head (62) form closing members for the cylinder (63).
[0065] The shaft (40) passes through the stacked front head (61),
cylinder (63) and rear head (62) and its large-diameter eccentric
part (41) is located inside the cylinder (63).
[0066] The rotary piston (67) is contained in the cylinder (63)
closed at both the upper and lower ends. The rotary piston (67) is
formed in an annular or cylindrical shape and its inner diameter is
approximately equal to the outer diameter of the large-diameter
eccentric part (41). The large-diameter eccentric part (41) is
rotatably fitted in the rotary piston (67) so that the inner
periphery of the rotary piston (67) substantially entirely comes
into sliding contact with the outer periphery of the large-diameter
eccentric part (41).
[0067] The rotary piston (67) comes at the outer periphery into
sliding contact with the inner periphery of the cylinder (63) and
comes at the upper end surface (67b) and the lower end surface
(67c) into sliding contact with the rear head (62) and the front
head (61), respectively. In the cylinder (63), its inner periphery
defines a fluid chamber (65) together with the outer periphery of
the rotary piston (67).
[0068] The rotary piston (67) is integrally formed with a blade
(67a). The blade (67a) is formed into a plate extending radially
from the rotary piston (67) and extends outward from the outer
periphery of the rotary piston (67). The fluid chamber (65) in the
cylinder (63) is partitioned by the blade (67a) into a
high-pressure chamber (66a) of relatively high pressure and a
low-pressure chamber (66b) of relatively low pressure.
[0069] The cylinder (63) is provided with a pair of bushes (68).
Each bush (68) is formed in the shape of a half moon so that its
inside surface is plane and its outside surface is arcuate. The
pair of bushes (68) are fitted in the cylinder wall with the blade
(67a) sandwiched therebetween. The bush (68) slides with the inside
surface on the blade (67a) and slides with the outside surface on
the cylinder (63). The blade (67a) integral with the rotary piston
(67) is supported through the bush (68) to the cylinder (63) and
configured to be free to angularly move about, extend into and
retract from the cylinder (63).
[0070] The inlet port (34) is formed in the front head (61) and
opens at the downstream end into the inside surface of the front
head (61) to communicate with the high-pressure chamber (66a). On
the other hand, the outlet port (35) is formed in the cylinder (63)
and opens at the upstream end into the inner periphery of the
cylinder (63) to communicate with the low-pressure chamber
(66b).
[0071] The oil feeding channel (49) in the shaft (40) is provided
with narrow channels (49a) for feeding oil to each of sliding areas
(A, B) of the expansion mechanism (60). The narrow channels (49a)
are formed mainly for the purpose of feeding oil to the sliding
areas (A) formed by both the end surfaces of the large-diameter
eccentric part (41), the rear head (62) and the front head (61) and
the sliding area (B) between the outer periphery of the
large-diameter eccentric part (41) and the inner periphery of the
rotary piston (67).
[0072] At the upper and lower end surfaces (67b, 67c) of the rotary
piston (67), sealing mechanisms (90) are provided for sealing the
end surfaces with respect to the rear head (62) and the front head
(61). Each sealing mechanism (90) includes a sealing groove (91)
and a sealing member (92) fitted in the sealing groove (91).
[0073] The sealing grooves (91) are individually formed in the
upper end surface (67b) and the lower end surface (67c) of the
rotary piston (67). Each sealing groove (91) has a cross section of
a recessed shape and is formed annularly in plan view, i.e., along
the entire circumference of each end surface (67b, 67c) of the
rotary piston (67).
[0074] The sealing member (92) is constituted by a lip seal that is
a mechanical seal. The lip seal (92) is formed in the cross section
of substantially C-shape opening inwardly and in a continuous round
shape in plan view. Thus, the lip seal (92) is fitted in the
sealing groove (91) so that its opening faces toward the shaft
(40).
[0075] Furthermore, the lip seal (92) is made of ethylene
tetrafluoride-based (PTFE-based) resin material. The ethylene
tetrafluoride-based resin material is a material obtained by adding
a filler, such as glass fibers or carbon fibers, to a pure ethylene
tetrafluoride (PTFE) resin. Since the ethylene tetrafluoride-based
resin material is a material having excellent abrasion resistance
and heat resistance, this ensures a high sealing performance.
[0076] According to the sealing mechanism (90), when each of the
sliding areas (A, B) is excessively lubricated, the lubricating oil
gets into the lip seals (92) through their openings and the
attendant action of pressure of the lubricating oil expands the
openings of the lip seals (92). When the openings of the lip seals
(92) expand, the lip seals (92) come into close contact with the
front head (61) and rear head (62) and also come into close contact
with the bottoms of the sealing grooves (91), thereby sealing the
upper and lower end surfaces (67b, 67c) of the rotary piston (67)
with respect to the rear head (62) and the front head (61). This
substantially prevents the lubricating oil fed to each sliding area
(A, B) from leaking into the fluid chamber (65) of the cylinder
(63).
[0077] Each of the clearance between the upper end surface (67b) of
the rotary piston (67) and the rear head (62) and the clearance
between the lower end surface (67c) thereof and the front head (61)
is set at a size of 1/10000 to 1/2000 of the inner diameter of the
cylinder (63). In other words, the fit tolerance of the rotary
piston (67) in the axial direction of the shaft (67) is set at a
size of 1/5000 to 1/1000 of the inner diameter of the cylinder
(63). This means that since the sealing mechanism (90) described
above provides seals of both the upper and lower end surfaces (67b,
67c) of the rotary piston (67) with respect to the front head (61)
and the rear head (62), there is no need to leave such a small
clearance as conventionally done between the upper end surface
(67b) of the rotary piston (67) and the rear head (62) and between
the lower end surface (67c) thereof and the front head (61).
Therefore, there is no need to strictly manage the processing
precision and assembly precision of the rotary piston (67), which
provides cost reduction.
[0078] --Operational Behaviors--
[0079] Next, a description is given of the behaviors of the air
conditioner (10). Here, the description is given first of the
behavior of the air conditioner (10) in cooling operation, then of
the behavior thereof in heating operation and then the behavior of
the expansion mechanism (60).
[0080] <Cooling Operation>
[0081] In cooling operation, the first four-way selector valve (21)
and the second four-way selector valve (22) are switched to the
positions shown in the broken lines in FIG. 1. When in these
positions the electric motor (45) of the compression/expansion unit
(30) is energized, refrigerant circulates through the refrigerant
circuit (20) to operate in a vapor compression refrigeration
cycle.
[0082] The refrigerant compressed by the compression mechanism (50)
is discharged through the discharge pipe (36) out of the
compression/expansion unit (30). In this state, the refrigerant
pressure becomes higher than the critical pressure. The discharged
refrigerant passes through the first four-way selector valve (21)
and is sent to the outdoor heat exchanger (23). In the outdoor heat
exchanger (23), the refrigerant having flowed therein releases heat
to the outdoor air.
[0083] The refrigerant having released heat in the outdoor heat
exchanger (23) passes through the second four-way selector valve
(22) and flows through the inlet port (34) into the expansion
mechanism (60) of the compression/expansion unit (30). In the
expansion mechanism (60), high-pressure refrigerant expands whereby
its internal energy is converted to the rotational power of the
shaft (40). The low-pressure refrigerant obtained by expansion
flows through the outlet port (35) out of the compression/expansion
unit (30), passes through the second four-way selector valve (22)
and is sent to the indoor heat exchanger (24).
[0084] In the indoor heat exchanger (24), the refrigerant having
flowed therein takes heat from the room air to evaporate, thereby
cooling the room air. The low-pressure gas refrigerant having
flowed out of the indoor heat exchanger (24) passes through the
first four-way selector valve (21) and is sucked through the
suction port (32) into the compression mechanism (50) of the
compression/expansion unit (30). Then, the compression mechanism
(50) compresses the sucked refrigerant again and discharges it.
[0085] <Heating Operation>
[0086] In heating operation, the first four-way selector valve (21)
and the second four-way selector valve (22) are switched to the
positions shown in the solid lines in FIG. 1. When in these
positions the electric motor (45) of the compression/expansion unit
(30) is energized, refrigerant circulates through the refrigerant
circuit (20) to operate in a vapor compression refrigeration
cycle.
[0087] The refrigerant compressed by the compression mechanism (50)
is discharged through the discharge pipe (36) out of the
compression/expansion unit (30). In this state, the refrigerant
pressure becomes higher than the critical pressure. The discharged
refrigerant passes through the first four-way selector valve (21)
and is sent to the indoor heat exchanger (24). In the indoor heat
exchanger (24), the refrigerant having flowed therein releases heat
to the room air to heat the room air.
[0088] The refrigerant having released heat in the indoor heat
exchanger (24) passes through the second four-way selector valve
(22) and flows through the inlet port (34) into the expansion
mechanism (60) of the compression/expansion unit (30). In the
expansion mechanism (60), high-pressure refrigerant expands whereby
its internal energy is converted to the rotational power of the
shaft (40). The low-pressure refrigerant obtained by expansion
flows through the outlet port (35) out of the compression/expansion
unit (30), passes through the second four-way selector valve (22)
and is sent to the outdoor heat exchanger (23).
[0089] In the outdoor heat exchanger (23), the refrigerant having
flowed therein takes heat from the outdoor air to evaporate. The
low-pressure gas refrigerant having flowed out of the outdoor heat
exchanger (23) passes through the first four-way selector valve
(21) and is sucked through the suction port (32) into the
compression mechanism (50) of the compression/expansion unit (30).
Then, the compression mechanism (50) compresses the sucked
refrigerant again and discharges it.
[0090] <Behavior of Expansion Mechanism>
[0091] A description is given of the behavior of the expansion
mechanism (60) with reference to FIG. 5. When supercritical
high-pressure refrigerant flows into the high-pressure chamber
(66a) of the expansion mechanism (60), the shaft (40) rotates
counterclockwise as viewed in diagrams of FIG. 5.
[0092] At an angle of rotation of 0.degree. of the shaft (40), the
downstream end of the inlet port (34) is closed by the end surface
of the large-diameter eccentric part (41). When the shaft (40)
rotates slightly from this state, the inlet port (34) communicates
with the high-pressure chamber (66a) so that high-pressure
refrigerant begins to flow into the high-pressure chamber (66a).
Then, as the angle of rotation of the shaft (40) gradually
increases to 90.degree., 180.degree. and 270.degree., the volume of
the first high-pressure chamber (73) gradually increases. When the
angle of rotation of the shaft (40) reaches approximately
360.degree., the inlet port (34) is closed again by the end surface
of the large-diameter eccentric part (41) so that the flow of the
high-pressure refrigerant into the high-pressure chamber (66a) is
shut off.
[0093] Next, when the angle of rotation of the shaft (40) reaches
0.degree. again, the low-pressure chamber (66b) communicates with
the outlet port (35) so that the refrigerant begins to flow out of
the low-pressure chamber (66b). Then, as the angle of rotation of
the shaft (40) gradually increases to 90.degree., 180.degree. and
270.degree., the volume of the low-pressure chamber (66b) gradually
decreases and, during the time, the refrigerant continues to flow
out through the outlet port (35). Then, when the angle of rotation
of the shaft (40) reaches approximately 360.degree., the outlet
port (35) is closed by the rotary piston (67) so that the flow of
refrigerant from the low-pressure chamber (66b) is shut off. At the
time, the pressure difference between the high-pressure chamber
(66a) and the low-pressure chamber (66b) causes the rotary piston
(67) and the shaft (40) to drive into rotation.
[0094] During operation of the expansion mechanism (60), the
rotation of the shaft (40) causes the lubricating oil in the oil
reservoir to be fed through the oil feeding channel (49) to the
sliding areas of the expansion mechanism (60). Even if during the
time the sliding areas in the expansion mechanism (60) are
excessively lubricated through the narrow channels (49a) to produce
an excess of lubricating oil, the sealing mechanisms (90) restrains
the flow of the excessive lubricating oil into the fluid chamber
(65). This substantially eliminates that the lubricating oil mixes
with the refrigerant in the fluid chamber (65) and flows through
the outlet port (35) out of the compression/expansion unit (30)
together with the refrigerant. As a result, the oil discharge to
the refrigerant circuit (20) can be prevented thereby preventing
the performance deterioration of each heat exchanger (23, 24).
[0095] Furthermore, since the compression/expansion unit (30) in
this embodiment includes the compression mechanism (50) and is
formed as a high-pressure dome type, the lubricating oil in the oil
reservoir is heated by high-temperature and high-pressure gas
refrigerant discharged from the compression mechanism (50).
Therefore, the lubricating oil fed to the expansion mechanism (60)
reaches relatively high temperature. On the other hand, since the
refrigerant circuit (20) operates in a vapor compression
refrigeration cycle, refrigerant flowing into the expansion
mechanism (60) has relatively low temperature. In the expansion
mechanism (60), the sealing mechanisms (90) restrain the
lubricating oil from flowing into the fluid chamber (65) and, in
turn, low-temperature refrigerant in the fluid chamber (65) is not
mixed with the high-temperature refrigerant and heated up.
Therefore, heat loss in the course of expansion can be
prevented.
[0096] Furthermore, since the lip seal (92) is made of ethylene
tetrafluoride-based resin material having excellent abrasion
resistance and heat resistance, it ensures a high sealing
performance even when sliding on the front head (61) or the rear
head (62) owing to the rotation of the rotary piston (67).
Effects of Embodiment
[0097] As described so far, since in Embodiment 1 the upper and
lower end surfaces (67b, 67c) of the rotary piston (67) are
provided with sealing mechanisms (90) for sealing them with respect
to the front head (61) and the rear head (62), this restrains the
lubricating oil fed to each sliding area (A, B) of the expansion
mechanism (60) from leaking into the fluid chamber (65). Thus, it
can be substantially avoided that the lubricating oil flows out of
the compression/expansion unit (30) together with the refrigerant.
Therefore, the oil discharge to the refrigerant circuit (20) can be
prevented, the shortage of lubricating oil in the expansion
mechanism (60) can be eliminated and the performance degradation of
each heat exchanger (23, 24) can be prevented. As a result, the
reliability of the rotary expander can be enhanced.
[0098] Particularly, in the high-pressure dome type
compression/expansion unit (30), the lubricating oil in the oil
reservoir has relatively high temperature. On the other hand, in
the refrigerant circuit (20) operating in a vapor compression
refrigeration cycle, the refrigerant flowing into to the expansion
mechanism (60) has relatively low temperature. As described above,
since the above embodiment restrains the leakage of lubricating oil
into the fluid chamber (65) and in turn prevents that the
low-temperature refrigerant is mixed with the high-temperature
lubricating oil and thereby heated up, heat loss in the course of
expansion can be prevented. As a result, the operation efficiency
can be enhanced.
[0099] Furthermore, since the lip seals (92) are used as the
sealing members, the openings of the lip seals (92) can be expanded
by the action of pressure of the lubricating oil, thereby surely
bringing the lip seals (92) into close contact with the front head
(61), the rear head (62) and the sealing grooves (91). This surely
provides seals of the upper and lower end surfaces (67b, 67c) of
the rotary piston (67) with respect to the front head (61) and the
rear head (62).
[0100] Moreover, since the lip seals (92) are made of ethylene
tetrafluoride-based resin material having excellent abrasion
resistance and heat resistance, it ensures a high sealing
performance even when sliding on the front head (61) or the rear
head (62) owing to the rotation of the rotary piston (67).
[0101] Furthermore, since the fit tolerance of the rotary piston
(67) in the axial direction of the shaft (40) is set at a size of
1/5000 to 1/1000 of the inner diameter of the cylinder (63), this
eliminates the need to strictly manage the processing precision and
assembly precision of the rotary piston (67), which provides cost
reduction.
Embodiment 2 of the Invention
[0102] Next, Embodiment 2 of the present invention is described
with reference to the drawings.
[0103] As shown in FIGS. 6 and 7, Embodiment 2 employs chip seals
as the sealing members (92) instead of lip seals used in Embodiment
1. Specifically, in this embodiment, the sealing mechanism (90) is
constituted by a sealing groove (91) formed in each of the upper
and lower end surfaces (67b, 67c) of the rotary piston (67) and a
chip seal (92) fitted in the sealing groove (91).
[0104] More specifically, the chip seal (92) is a mechanical seal
and is made of metal such as copper. The chip seal (92) is formed
in a rectangular cross section and in a discontinuous round shape
in plan view. In other words, the chip seal (92) is cut radially at
a single point on the circumference (see the point D in FIG. 6).
This cutting is done in order to fit the chip seal (92) being given
a tension into the sealing groove (91) and thereby bias the chip
seal (92) radially outwardly after the fitting.
[0105] If in this case each sliding area (A, B) is excessively
lubricated, the pressure of the lubricating oil acts on the inner
peripheries of the chip seals (92). By the action of the pressure
of the lubricating oil, the chip seals (92) entirely slightly rise
up and are concurrently pushed outward to come into close contact
with the front head (61) and the rear head (62) and the outer
peripheries of the sealing grooves (91). Thus, the upper and lower
end surfaces (67b, 67c) of the rotary piston (67) are sealed with
respect to the rear head (62) and the front head (61),
respectively. The other configurations, behaviors and effects are
the same as in Embodiment 1.
[0106] Though in this embodiment the chip seals (92) are made of
metal, they may be made of ethylene tetrafluoride-based resin
material like Embodiment 1. In this case, the chip seals (92) are
formed in a continuous round shape without being cut.
Embodiment 3 of the Invention
[0107] Next, Embodiment 3 of the present invention is described
with reference to the drawing.
[0108] In Embodiment 3, as shown in FIG. 8, the sealing grooves
(91) and the chip seals (92) differ in shape from those in
Embodiment 2. Specifically, each sealing groove (91) is formed in a
C shape that the annular sealing groove (91) in Embodiment 2 is
discontinued at one point. Likewise, each chip seal (92) is formed,
in plan view, in a C shape corresponding to the sealing groove
(91). In addition, each sealing groove (91) is formed to present a
part (C) corresponding to the opening of the C shape to the
high-pressure chamber (66a) of the fluid chamber (65).
[0109] In the above case, the end surfaces (67b, 67c) of the rotary
piston (67) will not be sealed at their parts (C) each
corresponding to the opening of the C shape with respect to the
front head (61) and the rear head (62). Since, however, the
high-pressure chamber (66a) has substantially the same pressure as
the inside areas of the chip seals (92), this restrains the
lubricating oil from leaking into the high-pressure chamber (66a),
i.e., the fluid chamber (65).
[0110] Furthermore, since the sealing grooves (91) are formed in C
shape, this prevents the chip seals (92) from moving
circumferentially in the sealing grooves (91) owing to sliding
resulting from the rotation of the shaft (40). Thus, the parts (C)
each corresponding to the opening of the C shape are always
presented to the high-pressure chamber (66a), which surely
restrains the leakage of lubricating oil into the fluid chamber
(65). The other configurations, behaviors and effects are the same
as in Embodiment 2.
Embodiment 4 of the Invention
[0111] Next, Embodiment 4 of the present invention is described
with reference to the drawing.
[0112] In Embodiment 4, as shown in FIG. 9, the chip seals (92)
differ in cutting manner from those in Embodiment 2. Specifically,
while in Embodiment 2 the chip seals (92) are cut radially and
linearly at one point, the chip seals (92) in this embodiment are
cut in steps at one point (see the part D). In other words, each
chip seal (92) in this embodiment has an overlap interval at the
cut part (D).
[0113] In the above case, even when the chip seal (92) move
circumferentially in the sealing groove (91) owing to sliding
resulting from the rotation of the shaft (40), the provision of the
overlap interval holds the cut surfaces of the cut part (D) into
contact with each other, i.e., against apart from each other. This
restrains the leakage of lubricating oil into the fluid chamber
(65). The other configurations, behaviors and effects are the same
as in Embodiment 2.
[0114] Though in this embodiment the chip seals (92) are cut in
steps, they may be cut linearly obliquely with respect to the
radial direction. In other words, the chip seals (92) may be cut to
taper the cut profile. To sum up, any cutting manner will do if it
creates an overlap interval at the cut part (D).
Embodiment 5 of the Invention
[0115] Next, Embodiment 5 of the present invention is described
with reference to the drawings.
[0116] In stead of the sealing mechanism (90) in Embodiment 1
constituted by a sealing groove (91) and a sealing member (92), the
sealing mechanism (90) in Embodiment 5 is, as shown in FIGS. 10 and
11, constituted by only a plurality of sealing grooves (93). In
other words, the sealing mechanism (90) in this embodiment is
formed in a labyrinth seal.
[0117] Specifically, the labyrinth seal (90) is constituted by
three sealing grooves (93). The sealing grooves (93) are formed in
a set of three for each of the upper and lower end surfaces (67b,
67c) of the rotary piston (67). The set of three sealing grooves
(93) have a similar shape to the sealing groove (91) in Embodiment
1 and are formed with different diameters from one another, i.e.,
triply in the radial direction of the rotary piston (67).
[0118] The labyrinth seal (90) provides a labyrinth effect derived
as from a frictional effect due to the viscosity of the lubricating
oil and a contraction effect at a throttling gap, thereby sealing
the upper and lower end surfaces (67b, 67c) of the rotary piston
(67) with respect to the rear head (62) and the front head (61),
respectively. In this case, the sealing members (92) themselves and
in turn the assembly of the sealing members (92) can be dispensed
with, which provides cost reduction. The other configurations,
behaviors and effects are the same as in Embodiment 1.
[0119] Though in this embodiment the labyrinth seal (90) is
constituted by three sealing grooves (93) and the sealing grooves
(93) have a rectangular profile, the number and profile of sealing
grooves are not limited to the above. In other words, any number
and profile of sealing grooves are applicable so long as they can
provide a labyrinth effect.
Embodiment 6 of the Invention
[0120] Next, Embodiment 6 of the present invention is described
with reference to the drawing.
[0121] In Embodiment 6, as shown in FIG. 12, the structure of the
expansion mechanism (60) and the placement of the sealing
mechanisms (90) differ from those in Embodiment 1. In other words,
though the expansion mechanism (60) in Embodiment 1 is of so-called
single cylinder type, the expansion mechanism (60) in this
embodiment is of double cylinder type.
[0122] Specifically, the shaft (40) is formed at its upper end with
two large-diameter eccentric parts (41, 42). The lower of the two
large-diameter eccentric parts (41, 42) constitutes a first
large-diameter eccentric part (41) and the upper constitutes a
second large-diameter eccentric part (42). The first large-diameter
eccentric part (41) and the second large-diameter eccentric part
(42) have opposite directions of eccentricity with respect to the
axis of the main spindle (44).
[0123] The expansion mechanism (60) includes two cylinders (71, 72)
and two rotary pistons (75, 85) in two pairs and also includes a
front head (61), an intermediate plate (64) and a rear head (62).
In the expansion mechanism (60), the front head (61), the first
cylinder (71), the intermediate plate (64), the second cylinder
(81) and the rear head (62) are stacked in order from bottom to
top. The first cylinder (71) is closed at the lower end surface by
the front head (61) and closed at the upper end surface by the
intermediate plate (64). On the other hand, the second cylinder
(81) is closed at the lower end surface by the intermediate plate
(64) and closed at the upper end surface by the rear head (62). The
first cylinder (71) and the second cylinder (81) are formed to have
the same inner diameter.
[0124] The shaft (40) passes through the stacked front head (61),
first cylinder (71), intermediate plate (64), second cylinder (81)
and rear head (62). The first large-diameter eccentric part (41) of
the shaft (40) is located inside the first cylinder (71), while the
second large-diameter eccentric part (42) thereof is located inside
the second cylinder (81).
[0125] The first rotary piston (75) and the second rotary piston
(85) are placed in the first cylinder (71) and the second cylinder
(81), respectively. The first cylinder (71) and the second cylinder
(81) are formed in an annular or cylindrical shape and have equal
outer diameters. The first large-diameter eccentric part (41) and
the second large-diameter eccentric part (42) are rotatably fitted
in the first rotary piston (75) and the second rotary piston (85),
respectively.
[0126] The first rotary piston (75) comes at the outer periphery
into sliding contact with the inner periphery of the first cylinder
(71) and comes at the lower end surface (75c) and the upper end
surface (75b) into sliding contact with the front head (61) and the
intermediate plate (64), respectively. In the first cylinder (71),
its inner periphery defines a first fluid chamber (72) together
with the outer periphery of the first rotary piston (75). On the
other hand, the second rotary piston (85) comes at the outer
periphery into sliding contact with the inner periphery of the
second cylinder (81) and comes at the upper end surface (85b) and
the lower end surface (85c) into sliding contact with the rear head
(62) and the intermediate plate (64), respectively. In the second
cylinder (81), its inner periphery defines a second fluid chamber
(82) together with the outer periphery of the second rotary piston
(85).
[0127] In other words, in the expansion mechanism (60) of this
embodiment, the intermediate plate (64) constitutes an intermediate
partition plate for separating the inner space of the first
cylinder (71) from the inner space of the second cylinder (81). The
rotary pistons (75, 85) are connected to each other through a
single shaft (40) and juxtaposed so that the adjacent end surfaces
(75b, 85c) of the rotary pistons (75, 85) face each other with the
intermediate plate (64) interposed therebetween.
[0128] The front head (61) is formed with a first inlet port (34a)
in communication with the high-pressure chamber of the first fluid
chamber (72) and the rear head (62) is formed with a second inlet
port (34b) in communication with the high-pressure chamber of the
second fluid chamber (82). On the other hand, the cylinders (71,
81) are individually formed with outlet ports (35) in communication
with the low-pressure chambers of the fluid chambers (72, 82).
[0129] Sealing mechanisms (90) are individually provided at the
lower end surface (75c) of the first rotary piston (75) and the
upper end surface (85b) of the first rotary piston (75). In other
words, out of the end surfaces of the rotary pistons (75, 85), the
end surfaces (75c, 85b) facing the front head (61) and the rear
head (62) serving as closing members are each provided with the
sealing mechanism (90). Note that the structure of each sealing
mechanism (90) is the same as that in Embodiment 1.
[0130] In this embodiment, when each cylinder (71, 81) is
excessively lubricated, the end surfaces (75c, 85b) provided with
the sealing mechanism (90) undergo higher pressure than the
pressure of the lubricating oil acting on the end surfaces (75b,
85c) facing the intermediate plate (64). Thus, the rotary pistons
(75, 85) are pushed toward the intermediate plate (64) to come into
substantially close contact with the intermediate plate (64).
Consequently, the upper and lower end surfaces (75b, 75c, 85b, 85c)
of the rotary pistons (75, 85) are sealed with respect to the front
head (61), the rear head (62) and the intermediate plate (64).
Since in this manner no sealing mechanism (90) is provided at the
end surfaces (75b, 85c) of the rotary pistons (75, 85) toward the
intermediate plate (64), the sealing performance can be ensured
while the lip seals (92) can be prevented from being pinched into a
through hole (64a) for the shaft (40) formed in the intermediate
plate (64). The other configurations, behaviors and effects are the
same as in Embodiment 1.
Other Embodiments
[0131] The above embodiments of the present invention may have the
following configurations.
[0132] For example, though in Embodiments 2 to 4 a sealing groove
(91) and a chip seal (92) are provided in a single pair for each of
the upper and lower end surfaces (67b, 67c) of the rotary piston
(67), they may be provided in two pairs to form a double seal. In
this case, the sealing performance can be further ensured.
[0133] Though in Embodiments 1 to 5 both the end surfaces (67b,
67c) of the rotary piston (67) are individually provided with
sealing mechanisms (90), either one of them may be provided with a
sealing mechanism (90). In this case, the same sealing effect as in
Embodiment 6 can be obtained. In other words, the present invention
will work if at least one of the end surfaces (67b, 67c) of the
rotary piston (67) is provided with a sealing mechanisms (90).
[0134] It is a matter of course that in Embodiments 1 to 4 and 6
materials other than ethylene tetrafluoride-based resin material
may be used as a material for the sealing member (92).
INDUSTRIAL APPLICABILITY
[0135] As described so far, the present invention is useful as a
rotary expander for generating power by the expansion of
high-pressure fluid.
* * * * *