A turbo-compressor apparatus in which the turbine section and the compressor section are placed back-to-back. A non-rotating shaft axially supported in the apparatus supports an anti-friction bearing which, in turn, rotationally supports a rotor assembly. A separating member preferably comprised of a material of low thermal conductivity is provided between the turbine section and the compressor section. A fully floating, non-rotating sleeve bearing incorporating both thrust and radial surfaces is allowed to float freely on the shaft. Thus, thrust forces from the spinning rotor are initially absorbed at the large radial bearing surfaces located at approximately the center of the bearing and are thereby transferred to the small areas at either end of the sleeve bearing. The thrust forces are finally transferred from the sleeve bearing to the stationary shaft. The mechanically locked sleeve bearing also serves to retain the rotor on the stationary shaft. In the preferred embodiment, the stationary shaft is supported at only one of its ends, the unsupported end extending into a cylindrical opening in the rotor assembly which opening may be a blind hole.

TECHNICAL FIELD 
The present invention relates to turbo-compressor apparatus. In particular, 
it relates to such apparatus wherein a rotor assembly rotates on a 
stationary shaft. 
BACKGROUND OF THE INVENTION 
Conventional turbo-compressor apparatus, especially those designed to be 
used as turbosuperchargers for internal combustion engines, are generally 
constructed so as to have a compressor section, a turbine section and a 
bearing housing separating these sections. Lubricating oil is supplied to 
provide lubrication for a bearing in this housing in which a common shaft 
for the compressor impeller and turbine wheel rotates. The bearings in 
such a conventional turbo-compressor apparatus are generally fully 
floating sleeve type bearings which rotate at approximately half the 
rotational speed of the shaft. In U.S. Pat. No. 3,043,636 to MacInnes, 
however, a non-rotating sleeve bearing is used. This bearing, however, is 
a semi-floating device because a flange located at one end of the bearing 
is pinned to the bearing housing. 
Turbo-compressors, according to these conventional designs, have an oil 
seal at each end of the bearing to prevent lubricating oil supplied to the 
bearing from entering the compressor section or the turbine section of the 
apparatus. The oil seal disposed near the turbine end of the bearing 
generally operates at relatively high temperatures and is a possible 
source of failure of the apparatus. 
U.S. Pat. No. 2,911,138 to Birmann discloses a turbo-compressor in which a 
non-rotating shaft extends into a rotor assembly. Ball bearings rather 
than sleeve bearings are used in this design. Such bearings may present 
practical engineering difficulties if the apparatus is operated at a 
rotational speed close to its critical speed. Birmann attempts to solve 
this problem by providing means for mounting the stationary shaft and 
constraining it to move only substantially parallel to itself under 
stresses imparted to the shaft by the rotor. The shaft is supported by 
leaf spring members which converge towards the center of gravity of the 
rotor. Damping means in the form of elastic O-rings absorb vibrational 
energy imparted to the shaft. 
Another design for a stationary shaft turbo-compressor type apparatus is 
disclosed in U.S. Pat. No. 3,692,436 to Connor et al. 
While conventional turbo-compressors and various design modifications to 
these conventional devices have been relatively successful, they are 
generally comprised of a large number of machined components. These 
devices are in themselves expensive, costly to assemble and require 
substantial maintenance. Also, conventional stationary shaft designs do 
not themselves lend at all to down sizing due to the size restrictions and 
rotor speed (RPM) limitations imposed by ball type bearings. 
BRIEF DESCRIPTION OF THE INVENTION 
The present invention provides a turbo-compressor apparatus that is simple, 
reliable, inexpensive, and can be built in small sizes. The central 
bearing housing used in conventional turbo-compressors is eliminated by 
placing the turbine section and the compressor section back-to-back. A 
stationary or non-rotating shaft axially supported in the apparatus 
supports an antifriction bearing which, in turn, rotationally supports a 
rotor assembly which has a turbine wheel disposed within the turbine 
section and a compressor impeller disposed within the compressor section. 
A separating member is provided between the turbine section and the 
compressor section. This separator extends into an annular recess in the 
rotor assembly separating the turbine wheel from the compressor impeller. 
The separating member is preferably comprised of a material of low thermal 
conductivity (so as to reduce heat flow from the turbine section to the 
closely adjacent compressor section) and is preferably refractory in 
nature. 
A bearing surface for the rotor assembly is defined by a cylindrical 
axially extending opening in the rotor. A single bearing means may be 
provided for both thrust and rotation. The bearing means is preferably a 
fully floating, non-rotating sleeve bearing disposed between the shaft and 
the cylindrical bearing surface. The rotor and sleeve bearing may be 
configured with a radially extending annular member located at 
approximately the center of the sleeve bearing and a complementary annular 
recess receiving the member where the member and the recess have parallel 
generally radial surfaces. These surfaces, of relatively large area, may 
act as thrust bearings transferring axial loads from the spinning rotor to 
small areas at the ends of the sleeve bearings, which loads are then 
transferred to the non-rotating shaft. Preferably, the sleeve bearing is 
configured with an annular member extending radially outward and the rotor 
is configured with an outwardly extending annular recess which accepts the 
outwardly extending annular member. 
In the preferred embodiment of the invention, the shaft is supported at 
only one of its ends, the unsupported end extending into the cylindrical 
opening in the rotor assembly. The cylindrical opening may be a blind hole 
with a bottom defining the length of that cylindrical opening. The 
unsupported portion may extend to substantially the bottom of the 
cylindrical opening. 
Advantageously, the shaft extends into the cylindrical opening from the 
compressor side of the rotor assembly. A source of pressurized lubricating 
fluid which provides a lubricating film upon which the bearing is 
supported also feeds lubricating fluid between the end of the unsupported 
portion of the shaft and the bottom of the cylindrical opening. The bottom 
of the cylindrical opening may thus serve as an additional thrust surface. 
Hydraulic pressure, generated by the fluid, provides an axial thrust which 
opposes the axial thrust exerted on the rotor assembly resulting from the 
pressure difference between the turbine section and compressor section. 
A cylindrical extension member which circumferentially surrounds the sleeve 
bearing may be fixed to rotate with the rotor assembly and extend toward 
the supported end of the shaft. This member may have a radially, inwardly 
extending annular flange with a radial wall. A shoulder in the sleeve 
bearing with a second radial wall which is disposed in facing relationship 
to the radial wall of the annular flange would then be provided. This 
arrangement may provide an additional thrust bearing surface. As a result 
of pressurized lubricating fluid being introduced, an additional axial 
thrust is produced on the rotor assembly. The area of the radial wall of 
the annular flange may be selected so that the sum of the axial thrust 
produced on this radial wall and the axial thrust due to the 
above-mentioned pressure differential is closer to being equal to the 
axial thrust due to the hydraulic force of the lubricating fluid on the 
bottom of the cylindrical opening than would be the case in the absence of 
this structure. 
In the preferred embodiment of the invention, a shaft supporting member is 
located within the air intake structure of the compressor housing portion 
so that it is in the path of air drawn into the compressor. Two or more 
ribs extending from a peripheral portion of the air intake structure 
support the shaft supporting member. Passageways within the ribs are 
provided for conducting lubricating fluid to and from the bearing 
structure. The cooling properties of the low pressure air at the inlet 
passing around the ribs aids in maintaining the lubricating fluid at a 
cooler operating temperature before entering the bearing thus tending to 
prolong service life. 
The apparatus of this invention may be combined with a combustor and other 
necessary components to serve as an energy source that is, for example, a 
prime mover.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now to the drawings, wherein like numerals indicate like 
elements, there is shown in FIG. 1 a turbo-compressor constructed in 
accordance with the present invention and designated generally as 10. 
Turbo-compressor 10 includes a compressor section 12 and a turbine section 
13. Compressor section 12 is defined by a compressor housing section 14 
preferably comprised of a cast aluminum alloy or plastic material. Turbine 
section 13 is defined by a turbine housing section 15 and is preferably 
comprised of a cast iron, such as ductile iron. Turbine section 13 is in 
back-to-back relation with compressor section 12 by virtue of compressor 
housing section 14 and turbine housing section 15 being secured to one 
another by use of a V-band clamp 16 of a type well known in the art. An 
annular groove 18 formed in compressor housing section 14 is fitted with 
an O-ring 20 and receives a mating annular member 21 formed on the turbine 
housing section 15. Elements 18, 20 and 21 cooperate to align housing 
sections 14, 15 and to provide a resilient seal therebetween. 
A supported portion 22A of stationary shaft 22 (formed of mild steel or 
stainless steel) extends through a shaft support member 24 in the axial 
direction of turbo-compressor 10. A steel washer 26 is disposed between 
annular shoulder member 27 of shaft 22 and shaft support member 24 
providing a hard abutment surface in lieu of the relatively soft material 
of shaft support member 24 which is an integral part of the casting of 
compressor housing section 14. A nut 28 is threaded onto the end of shaft 
22 and is tightened by an appropriate tool which engages flat surfaces 30 
(see FIG. 2) of nut 28. Nut 28 has generally an aerodynamic or bullet 
shape so as not to unduly disturb the flow of input air into air intake 
structure 32. Also in the path of intake air to the compressor section 12 
are aerodynamically shaped radial support ribs 34 and 36 which support 
shaft supporting member 24 centrally within the air intake structure 32. 
Surrounding substantially the remaining unsupported portion 22B of shaft 22 
is a fully floating sleeve bearing 38 which is preferably machined from a 
suitable quality bearing material such as aluminum or bronze. Sleeve 
bearing 38 is axially secured on shaft 22 by the head 44 of a screw 40 
which is threaded into an axially extending passageway 42 in shaft 22. 
Tolerances on the length of sleeve bearing 38 and the unsupported portion 
of shaft 22 between head 44 and annular shoulder member 27 are selected so 
that sleeve bearing 38 fully floats on shaft 22 with a small amount of 
axial play, for example, 0.006 inch. Radial clearance between the internal 
diameter of sleeve bearing 38 and the outer diameter of shaft 22 is 
preferably approximately 0.0005. 
To absorb thrust and prevent rotation of sleeve bearing 38 on areas too 
small to handle rotating thrust loads, such as the radially extending 
surface of annular shoulder member 27, the head 44 of screw 40 is 
generally rectangular (see FIGS. 4 and 5) and fits into two 
circumferential cutouts 46 at the end of sleeve bearing 38 as best shown 
in FIG. 3. 
An alternate means (not shown) of securing sleeve bearing 38 loosely to 
shaft 22 in fully floating relationship may comprise a pin fitting through 
a diametrically extending hole in shaft 22 and extending into 
corresponding diametrically opposed openings is sleeve bearing 38. 
The assembly of shaft 22 and sleeve bearing 38 extends into a cylindrical 
opening in a rotor assembly 48 comprised of a turbine wheel 49, a 
compressor impeller 56 and a cylindrical connecting portion 54. Radial 
clearance between the inner diameter of this cylindrical opening and the 
outer diameter of sleeve bearing 38 is preferably approximately 0.0005 
inch. Turbine wheel 49 has a webbing or core member 50 which is integrally 
formed with turbine blades 52 and cylindrical connecting portion 54. 
Although many possible designs may be used for the turbine wheel 49, a 
radial or mixed flow turbine of straight blade design with curved exducer 
outlet is preferred. The blades and the core member 50 may be formed from 
high temperature exotic alloys such as Stellite 31 or Inconel 713C. 
Compressor impeller 56 is fitted to cylindrical connecting portion 54 by 
either press fitting or by shrink fitting. Impeller 56 has a series of 
impeller blades 58 which serve to compress air aspirated into air intake 
structure 32. While many compressor designs may be used, the compressor of 
the apparatus of the invention is preferably a centrifugal flow compressor 
of straight or curved blade design with a curved inlet inducer. 
The compressor section 12 and turbine section 13 of the apparatus are 
separated by member 60 which is preferably disk shaped and radially 
supported in an annular recess 53 defined between compressor section 12 
and turbine section 13 as illustrated in FIG. 1. Member 60 occupies 
substantially the entire space of an angular recess 55 in rotor assembly 
48 formed by the axial spacing between the facing backsides of turbine 
wheel 49 and compressor impeller 56. Member 60 is preferably formed of a 
low thermal conductivity and refractory material. By low thermal 
conductivity, it is meant a material with a thermal conductivity 
significantly below those of most metals such as the thermal conductivity 
of ceramics or graphite. Thus, in addition to providing a seal between the 
compressor section 12 and turbine section 13, member 60 serves as a heat 
insulator reducing the amount of heat transferred from the hot turbine 
section 13 to the compressor section 12. 
A circular recess 62 may be provided in member 60 facing the backside of 
compressor impeller 56. The clearance between the bottom of recess 62 and 
the backside of the impeller 56 is typically in the order of 0.008 to 
0.010 inch while the clearance between the backside of turbine wheel 49 
and member 60 is typically approximately 0.040 inch. Clearance between the 
outer circumference of cylindrical connecting portion 54 and member 60 is 
typically approximately 0.002 inch. These clearances normally provide an 
adequate seal between the compressor section 12 and the turbine section 
13. If this seal is not adequate for a particular design, a closely 
fitting labyrinth type seal 64 of a type well known in the art may be 
provided to seal the outer circumference of cylindrical connecting portion 
54 to member 60. Labyrinth type seals (not shown) may also be provided on 
the radial back surfaces of compressor impeller 56. 
Lubrication is provided to sleeve bearing 38 from a source of pressurized 
lubricating fluid which is typically derived from the oil supply source 
associated with an internal combustion engine. Such an engine may be 
turbosupercharged using the apparatus of this invention by having the 
exhaust gases of the engine drive the turbine and having the compressor 
supply compressed air to the air intake port of the engine. 
A conduit supplying lubrication oil is attached to fitting 66 thus 
supplying oil to passageway 68 through rib 34. Passageway 68 feeds oil to 
an annular groove 70 in shaft support member 24 thus supplying oil to a 
short passageway 71 in shaft 22, regardless of the final, assembled 
rotational position of shaft 22. Passageway 71 connects to axially 
extending passageway 42. A series of radially extending diametrically 
drilled passageways 73 are provided to allow lubricating fluid from 
axially extending passageway 42 to enter the region between stationary 
shaft 22 and sleeve bearing 38. Screw 40 may also be provided with a 
central axially extending passageway 72 (FIGS. 3-5) along its length to 
permit lubricating oil to flow directly from passageway 42 to the area 
between head 44 of screw 40 and the bottom wall 51 of the cylindrical 
opening of rotor assembly core 50 in which the assembly of stationary 
shaft 22 and sleeve bearing 38 is disposed. Lubricating fluid may also 
reach this area, if an axial bore is not provided within screw 40 as 
described below. In either event, a thrust tending to push the rotor 
assembly 48 toward the turbine section of the housing (to the right in 
FIG. 1) is produced. This thrust operates in the direction opposite the 
axial thrust generally produced upon a rotor assembly in a 
turbo-compressor due to pressure differentials between the compressor 
section 12 and the turbine section 13 during normal operation. 
Sleeve bearing 38 is configured with an integral radially outwardly 
exending annular member 74. A mating recess 75 for annular member 74 is 
formed in cylindrical connecting portion 54 of rotor assembly 48 by a 
stepped increase in internal diameter and the introduction of a press 
fitted cylindrical axially extending extension member or thruster 76 which 
extends into the enlarged diameter portion of the cylindrical opening of 
rotor assembly 48 and rotates with rotor assembly 48. The facing radial 
surfaces of annular member 74 and the complementary recess 75 formed in 
the opening in rotor assembly 48 serve as thrust bearing surfaces 
transfering axial loads (thrust) from the rotor assembly 48 to sleeve 
bearing 38. These forces are then transferred to radially extending 
surfaces 39A and 39B at the ends of sleeve bearing 38 to be in turn 
transferred to shaft 22 directly from surface 39A and by means of screw 40 
from surface 39B. 
Thruster 76 is configured with a radially inwardly extending flange 78 
which opposes a shoulder 77 formed in sleeve bearing 38. The radial 
surface of shoulder 77 and the facing radial surface of flange 78 provide 
an additional thrust bearing surface. 
Lubricating fluid which is forced into the space between shaft 22 and 
sleeve bearing 38 is eventually forced through passageways 80, which are 
diametrically extending holes in sleeve bearing 38, to the area between 
sleeve bearing 38 and the internal surface of the opening in rotor 
assembly 48 which accepts the assembly of stationary shaft 22 and sleeve 
bearing 38. Oil distribution grooves (not shown) extending axially along 
the external circumferential surface of sleeve bearing 38 may be provided 
so as to intersect the openings of passageways 80 and thus aid in 
providing fluid along the entire length of sleeve bearing 38. The 
lubricating fluid is forced directly to the thrust bearing surfaces 
defined by the radial surfaces of annular member 74 and recess 75 through 
axially extending passageways 81 which intersect the diametrically 
extending passageways 80 in annular member 74, the distribution of fluid 
being aided by radially extending oil distribution grooves (not shown) 
which intersect the opening of passageways 81 on the radially extending 
surfaces of annular member 74. Lubricating fluid is also forced into the 
region between the outer surface of sleeve bearing 38 and the inner 
circumferential surface of thruster 76. Even if a channel 72 is not 
provided in screw 40, some lubricating fluid will eventually occupy the 
region between the head of screw 40 and the flat bottom of the cylindrical 
opening of rotor assembly 48. 
Flange 78 of thruster 76 also forms a rotational bearing surface 
cooperating with sleeve bearing 38. All of the lubricating fluid pumped 
into the bearing area eventually passes from these surfaces and appears in 
a recess 82 formed in support member 24. A passageway 84 is provided to 
collect this lubricating fluid which is conducted to fitting 86 and then 
back to the pressurized lubricating fluid source. It will be understood by 
one skilled in the art that the high rotational rate of rotor assembly 48 
aids in centrifugally pumping lubricating fluid from the sleeve bearing 38 
into the recess 82 from which it is scavenged. 
A lubricating fluid mechanical seal in the form of an annular graphite ring 
88 is biased by spring 92 against a metal contacting ring 90 which rotates 
with rotor assembly 48. This is a conventional type of fluid seal well 
known in the art. 
A helical thread or windback 94 may also be provided on the external 
circumference of thruster 76 with the sense of the helix being such that 
it effectively acts as a screw pump propelling fluid away from the 
mechanical seal. 
The lubricating fluid dispersed in the manner described will tend to 
produce an axial thrust upon rotor assembly 48 by virtue of its action 
upon the internal radial surface of flange 78. If, in fact, flange 78 is 
provided, the degree to which it extends radially inwardly and therefore 
the area of the internal radial surface may be adjusted so that the sum of 
the hydraulic axial thrust thus created plus the axial thrust created as a 
result of the pressure differential between turbine section 14 and 
compressor section 12 will be approximately equal to the axial thrust 
created by hydraulic pressure on the bottom wall 51 of the blind 
cylindrical opening in rotor assembly 48 which accepts the assembly of the 
shaft 22 and bearing 38. Such a balance would of necessity be approximate, 
however, because the pressure differential between the turbine section and 
the compressor section may vary with operating conditions. 
The first step in assembling turbo-compressor 10 is to place shaft 22 into 
sleeve bearing 38 and secure it with screw 40 by using a suitable tool 
which engages slot 45 of head 44 being certain that head 44 fits into 
cylindrical cutouts 46 of sleeve bearing 38. Rotor core member 50 is then 
placed over this assembly. If member 60 is of single piece construction, 
it is then placed around cylindrical connecting portion 54 of rotor core 
member 50 prior to press fitting of compressor impeller 56 onto 
cylindrical connecting portion 54. Thruster 76 is then press fitted into 
cylindrical portion 54. Contacting ring 90 is then press fitted around 
thruster 76. Annular graphite ring 88 and spring 92 are placed within 
cylindrical recess 82, after washer 26 has been put in place. Shaft 22 is 
then fitted and secured into support member 24 by tightening nut 28. 
Turbine housing section 15 is then assembled onto compressor housing 
section 14 compressing O-ring 20 in annular groove 18, the V-band clamp 16 
being tightened only after the correct relative rotational orientation 
between compressor housing section 14 and turbine housing section 15 for 
the particular installation has been achieved. If member 60 is formed of 
more than one piece, it need not be placed between turbine wheel 49 and 
compressor impeller 56 until just before shaft 22 is secured into support 
member 24. Practical considerations may, in some cases, favor a multipiece 
construction for member 60 in which it is, for example, comprised of two 
half moon-shaped members which are fitted together to form a circular 
seal. Such multipiece construction would be required if the entire rotor 
assembly 48 were of a one-piece construction with turbine wheel 49, 
cylindrical connecting portion 54 and compressor impeller 56 being 
integrally formed of a high temperature exotic alloy. 
In operation, a gas, usually air or a fuel/air mixture, which is to be 
compressed is allowed into the compressor section through air intake 
structure 32 and is compressed into compressor scroll region 96 from which 
it is removed by being conducted into a suitable conduit (not shown) 
attached to the output of compressor section 12. Exhaust gases, on the 
other hand, are conducted to turbine scroll region 98 by a suitable 
conduit (not shown) attached to an input portion of turbine section 13 and 
after giving up energy to the turbine wheel are exhausted through exhaust 
opening 100. 
Unlike most turbo-compressors, which must be operated with the shaft 
horizontally disposed, the bearing and lubrication seal arrangements of 
the present invention permit the turbo-compressor 10 to be installed in 
any desired orientation, as long as the unsupported end of shaft 22 is not 
lower than the supported end, thus assuring that gravity will not aid in 
causing lubricating fluid to reach the mechanical seal. 
While the energy source for driving the apparatus is generally an internal 
combustion engine which serves as a prime mover for a vehicle, it is 
possible to configure the apparatus with a heat source such as a combustor 
so that it itself may become a source of energy. Referring to FIG. 6, a 
source of fuel is supplied into the combuster 102 through a suitable means 
such as a fuel injector 104. Compressed air from compressor section 12 is 
conducted to combustor 102 by a suitable conduit, whereby the fuel from 
fuel injector 104 is ignited by igniter 103 and burned in combuster 102. 
After combustion is initiated exhaust gases of high energy are produced; 
this exhaust gas is provided to turbine section 14 thus driving the 
apparatus. The exhaust gas from turbine section 14 may in itself be 
sufficiently energetic to provide thrust in certain limited applications 
or alternatively means can be provided for obtaining rotational energy 
from the rotor assembly by means of an appropriate turbine rotor and 
shaft. 
The present invention may be embodied in other specific forms without 
departing from the spirit or essential attributes thereof and, 
accordingly, reference should be made to the appended claims, rather than 
to the foregoing specification as indicating the scope of the invention.