Rotary-sleeve supporting apparatus in rotary compressor

An apparatus provided in a rotary compressor comprising an air-bearing room (40) defined between the inner periphery of the center housing (22) and the outer periphery of the rotary sleeve (30) to have an air-bearing effect for floatingly supporting the rotary sleeve rotating with a plurality of vanes. The air-bearing room (40) is supplied with air through an inlet passage (45) and/or a connecting passage (49), if necessary. A buffer chamber (47, 57) is formed in the wall of the center housing (22) and opened to the inner periphery of the center housing (22) through tiny bores (48, 58). The rotary sleeve (30) is pushed back to the center by a buffering action of air in the buffer chamber whenever it is put aside toward the center housing (22), thereby being prevented against a direct contact with the inner periphery of the center housing (22).

TECHNICAL FIELDS 
The present invention relates to an apparatus for supporting a rotary 
sleeve rotatable with vanes in a rotary compressor, and more particularly 
to an improved apparatus for supporting the rotary sleeve by an 
air-bearing effect produced in a filmy air-bearing room defined between 
the inner periphery of the center housing of the rotary compressor and the 
outer periphery of the rotary sleeve. 
BACKGROUND ART 
The inventors of this application have previously proposed a vane-type 
rotary compressor provided with a rotary sleeve interposed between a 
center housing and a rotor, under Japanese Patent Application No. 
56-162025 (JP, A, 58-65988). The compressor is particularly suitable for 
use with an automobile engine required to operate over a wide speed range 
because of being substantially free from frictional heat as well as wear 
at the apex of each vane. However, there is the possibility of scuffing 
and seizure troubles if air is highly compressed in the compression 
working space within the compressor to push the rotary sleeve from within 
to the inner periphery of the center housing. 
From a study on the movement of the rotary sleeve, it has been clarified 
that a contact between the rotary sleeve and the center housing takes 
place not at a specific line but in a relatively wide zone. The inventors 
have proposed under patent application No. 58-28608 (JP, A, 59-155589) 
that the air inlet is provided at the starting line of the zone in which 
the rotary sleeve is likely to contact and is internally connected to the 
open air, the discharge chamber, and the compression working space under 
the maximum pressure to increase an amount of air flowing over the zone. 
However, when a sudden change occurs in the rotational speed of the 
internal combustion engine, the rotor is driven to rotate. The rotary 
sleeve abnormally moves to contact the suction side inner periphery of the 
center housing, thereby rotating in a disorderly manner. 
It is the primary object of the invention to provide an apparatus by which 
the rotary sleeve is floatingly supported without contacting the 
compression side inner periphery of the center housing when compressed air 
pushes the rotary sleeve from within to the compression side inner 
periphery and the suction side inner periphery when a sudden change occurs 
in the rotational speed of the rotor to move the rotary sleeve toward the 
suction side inner periphery. 
DISCLOSURE OF INVENTION 
The apparatus of the invention comprises a buffer chamber formed in either 
or both of the compression and suction sides of the center housing. The 
buffer chamber is located in the thickened portion of the center housing 
surrounding the rotary sleeve and is opened to an air-bearing room defined 
between the inner periphery of the center housing and the outer periphery 
of the rotary sleeve through a plurality of tiny bores. 
In addition to the buffer chamber, the apparatus is preferably provided 
with an air passage, as an aerodynamic means, to increase an amount of air 
flowing over the zone which the rotary sleeve is likely to contact. The 
air passage extends to the starting line of the zone from the atmosphere, 
the discharge chamber, or the compression working space which is defined 
by two adjacent vanes and situated just before a position in which the 
space is connected to the discharge chamber.

BEST MODE FOR CARRYING OUT THE INVENTION 
The invention will be explained with reference to drawings which illustrate 
specific embodiments. Referring initially to FIG. 1, the compressor has a 
rotor 10 eccentrically disposed in the rotary sleeve 30. The rotor 10 
rotates in the direction as indicated by an arrow and has a plurality of 
vanes 16 movably fitted in the respective vane grooves 15. The vane 16 has 
its apex in contact with the inner periphery of the rotary sleeve 30. The 
rotary sleeve 30 is floatingly supported in the air-bearing room 40 
confined between the inner periphery of the center housing 22 and the 
outer periphery of the rotary sleeve 30. The radial width of the 
air-bearing room 40 is exaggeratedly shown but really very thin, being 
less than 0.1 mm. 
The working space 43 is defined by the two adjacent vanes 16 to turn round 
within the rotary sleeve. The pressure in the working space 43 is low in 
the suction side and high in the compression side, being maximum when the 
space is just before a position in which it is connected to the discharge 
chamber 41 through the discharge port 42. An extract port 44 is given to 
the working space 43 under the maximum pressure and internally connected 
to the inlet port 71 in the compression side inner periphery of the center 
housing 22 through an inlet passage 45. Although the passage 45 is shown 
as it were outside the center housing 22, it really passes within the 
center housing. 
A buffer chamber is composed of an arcuate groove 46 formed in the 
compression side end surface of the center housing 22, a plurality of 
blind holes 47 extending axially from the arcuate groove 46 into the wall 
of the center housing 22, and tiny bores 48 extending radially from each 
blind hole 47 to the inner periphery of the center housing 22. 
As seen in FIG. 2, the rotor 10 is integrally shaped with a shaft 12 
rotatably supported by bearings 18, 19 in the respective front and rear 
housings 21, 23 and fixed at the front end thereof to a pulley 14 which is 
rotated by a non-illustrated engine. A gasket is interposed between the 
rear housing 23 and the rear cover 24 in which the discharge chamber 41 
and the suction chamber 51 are provided. The embodiment has an arcuate 
groove 46 formed in the rear side end surface of the center housing 22. 
The arcuate groove can be formed in either or both of the paired end 
surfaces of the center housing and the front and rear side housings. The 
blind holes 47 extend axially into the wall of the center housing 22 from 
the arcuate groove 46. The tiny bores 48 are symmetrically disposed with 
respect the central cross-section of the air-bearing room 40 to extend 
radially from the blind holes 47 to the inner periphery of the center 
housing 22. Thus, a connecting passage (49) connects a discharge chamber 
(41) to the air-bearing room (40) through the blind holes (47) and the 
arcuate groove (46). 
As seen in FIG. 3, the inlet passage 45 passes through the rear side 
housing 23 to terminate at the inlet port 71 in the inner periphery of the 
center housing 22. The inlet port 71 axially elongates and opens to the 
radially thin air-bearing room 40. The inlet port 71 is shaped in the form 
of a groove, as the exit of the inlet passage 45. The inlet port is not 
limited to a linear one. For example, it can be shaped in any form of an 
equilateral triangle as seen in FIG. 4, double split linear grooves as 
seen in FIG. 5, and a single groove extending to the vicinity of the 
opposite ends as seen in FIG. 6. 
As the compressor rotates, air in the working space 43 of FIG. 1 is 
pressured to push the rotary sleeve 30 toward the compression side. 
Whenever the rotary sleeve 30 is pushed toward the compression side inner 
periphery in which a buffer chamber is defined by the arcuate groove 46, 
the blind holes 47 and the tiny bores 48, it is pushed back by the 
buffering action of the buffer chamber and prevented from direct contact 
with the inner periphery of the center housing 22. 
High-pressure air is introduced through the inlet port 71 at the starting 
line of the contact zone to increase an amount of air flowing along the 
contact zone which the rotary sleeve 30 is likely to contact. Whenever the 
rotary sleeve is put aside toward the contact zone, the air over the zone 
is pressured to increase the bearing effect and prevent the rotary sleeve 
from contacting the inner periphery of the center housing 22. The 
pressured air enters the blind holes 47 through the tiny bores 48 and then 
spreads over all the blind holes through the arcuate groove 46 to balance 
the bearing effect over all the contact zone, thereby no part of the 
contact zone being in contact with the rotary sleeve 30. 
As seen in FIG. 7, the blind holes 47 are internally connected to the 
discharge chamber 41 through a high-pressure passage 49 extending from the 
discharge chamber 41 to the arcuate groove 46 to increase a buffering 
action of the buffer chamber, thereby the rotary sleeve 30 being more 
effectively prevented from contacting the inner periphery of the center 
housing 22. 
It is preferable for the rotary sleeve 30 to have the outer periphery 
thereof formed with herringbone air-accumulating grooves 39 the section of 
which is shown in FIG. 2 for the purpose of increasing the bearing effect 
of air flowing along the inner periphery of the center housing 22. 
The inlet passage is not always required to be connected to the working 
space under the maximum pressure. As seen in FIG. 8, the inlet passage 45 
can extends from the discharge chamber 41 to the compression side inner 
periphery of the center housing 22. The inlet passage 45 may have as an 
exit an inlet port 71 at the starting line of the zone which the rotary 
sleeve is likely to contact. The rotary sleeve acts as a pump whenever it 
rotates at high speeds, so that an inlet port vent to the atmosphere may 
be useful to increase an amount of air flowing over the contact zone. 
A sudden change in the rotational speed of engine causes an abnormal 
movement of the rotary sleeve with the result that the rotary sleeve 
sometimes occurs to contact the suction side inner periphery of the center 
housing. By way of precaution against a direct contact between the rotary 
sleeve and the suction side inner periphery of the center housing, the 
air-accumulating grooves 9 are preferably provided in the suction side 
inner periphery, opposite to the contact zone, of the center housing 22 as 
seen in FIG. 9. The air-accumulating groove 9 can be shaped in any form of 
a pair of rectilinear grooves as shown in FIG. 9, a single rectilinear 
groove as shown in FIG. 10, a group of herringbone grooves as shown in 
FIG. 11 and a group of narrow linear grooves as shown in FIG. 12. As seen 
in FIGS. 13 and 14, an arcuate groove 56 formed in the suction side end 
surface of the center housing 22, a plurality of blind holes 57 extending 
axially in the wall of the center housing 22, and tiny bores 58 opened to 
the inner periphery of the center housing 22 from the blind holes 57 form 
another buffer chamber to increase the bearing effect in the suction side 
of the air-bearing room 40 and prevent the rotary sleeve more effectively 
from contacting the suction side inner periphery of the center housing 22 
when the rotary sleeve makes an abnormal movement. The arcuate groove 56 
can be formed in either or both of paired surfaces of the center housing 
22 and the front and rear side housings 21, 23. The tiny bores 58 are 
symmetrically disposed with respect to the central cross-section of inner 
periphery of the center housing. 
Whenever the rotary sleeve 30 lies toward the suction side inner periphery 
of the center housing 22, the buffer chamber composed of tiny bores 58 and 
blind holes 57 produce a buffering action to push back the rotary sleeve 
30 toward the center. Air enters the contact zone through the inlet port 
71 of the inlet passage 45 from the discharge chamber 41 or working space 
43 under the maximum pressure to increase the bearing effect of the 
air-bearing room 40 and prevent the rotary sleeve 30 from contacting the 
contact zone of the center housing 22, thereafter going round to the 
suction side opposite to the contact zone. The air enters the blind holes 
57 through the tiny bores 58 to spread in the the buffer chamber through 
the arcuate groove 56, thereby also preventing the rotary sleeve 30 from 
contacting the suction side inner periphery of the center housing 22 when 
an abnormal movement of the rotary sleeve 30 occurs. 
As seen in FIG. 15, the air-bearing room 40 can be provided with a buffer 
chamber composed of two separate portions, one in the compression side of 
the center housing 22 and the other in the suction side. The buffer 
chamber has its compression side portion consisting of an arcuate groove 
46 in the compression side end of the center housing 22, a plurality of 
blind holes 47 extending axially from the arcuate groove into the wall of 
the center housing 22, and tiny bores 48 extending radially from each 
blind hole to the inner periphery of the center housing 22. The arcuate 
groove 46 can be connected to the discharge chamber 41, if a strong 
buffering action is required to push back the rotary sleeve which lies 
toward the compression side inner periphery of the center housing 22. 
The suction side portion consists of an arcuate groove 56 in the suction 
side end of the center housing 22, a plurality of blind holes 57, and tiny 
bores 58 radially branched from each blind hole and opened to the inner 
periphery of the center housing 22 to push back the rotary sleeve 30 to 
the center when the rotary sleeve lies toward the suction side inner 
periphery of the center housing 22. In the embodiment of FIG. 15, the 
maximum-pressure air in the working space 43 enters the air-bearing room 
40 from the inlet port 71 at the starting line of the contact zone through 
the inlet passage 45 to increase the bearing effect. The air also enters 
the compression side of the buffer chamber through the tiny bores 48 to 
produce a more effective buffering action for preventing the rotary sleeve 
from contacting the compression side inner periphery of the center 
housing. Thereafter, the air goes round to enter the suction side of the 
buffer chamber through the tiny bores 58 in the suction side to increase 
the buffering action for preventing the rotary sleeve from contacting the 
suction side inner periphery of the center housing 22. 
The apparatus of the invention has a filmy air-bearing room defined between 
the outer periphery of the rotary sleeve and the inner periphery of the 
center housing and a buffer chamber formed in either or both of the 
compression and suction sides of the center housing to fluidly support the 
rotary sleeve. Therefore, it has an advantage that the buffer chamber 
produces a buffering action to prevent direct contact between the rotary 
sleeve and the center housing both when compressed air pushes the rotary 
sleeve from within to the compression side inner periphery of the center 
housing and when a sudden change in the rotational speed of engine causes 
an irregular motion of the rotary sleeve. This advantage is not obtained 
from the conventional apparatus without a buffer chamber. The apparatus 
can have the inlet port to supply air to the air-bearing room. The 
supplied air increases the bearing effect on the contact zone and then 
enters the buffer chamber to produce a more effective buffering action for 
protection against direct contact between the rotary sleeve and the center 
housing, resulting in another advantage that scuffing troubles between the 
rotary sleeve and the center housing and problems due to an irregular 
rotation of the rotary sleeve are expected to be remarkably reduced as 
compared with the conventional apparatus. 
INDUSTRIAL APPLICABILITY 
The rotary compressor provided with the inventive apparatus for fluidly 
supporting a rotary sleeve which is rotatable with vanes is suitably used 
as a supercharger for an internal combustion engine, especially for an 
automobile engine. The reason for this is that frictional heat as well as 
wear is relatively small during rotation and that it has less scuffing 
troubles under high speed running or sudden speed change operations.