Machine with bearing-mounted rotors and liquid-lubricated bearings

A machine with bearing-mounted rotors includes a housing (1) and two cooperating rotors erected therein which are supported on bearings (8-9 and 11-12, 17-18 and 20-21, respectively) with shafts ends (5 and 5A, 14 and 14A, respectively) at their ends. The shaft ends (5, 14, respectively) of each of the rotors (2 and 3) rest in a pair of bearings (8-9, 17-18, respectively). The bearings (8 and 9) of the one pair are situated opposite the bearings (17 and 18) of the other pair. At least one spray element (27) is erected between the bearings (8 and 9, 17 and 18, respectively) of the pairs (8-9 and 17-18) for spraying lubricating liquid on the bearings (8-9-17-18). Between the bearings (8 and 9, 17 and 18, respectively) of each pair (8-9 and 17-18), a ridged ring (35, 35A respectively) is provided around the shaft and (5, 14, respectively). Each ridged ring (35, 35A) is provided with a protruding ridge (36, 36A, respectively) on its entire outer perimeter. The spray element (27) has nozzles (32, 32A, respectively) directed towards the protruding ridges (36, 36A, respectively) of the ridged rings (35 and 35A).

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention concerns a machine of the type comprising a housing 
and two cooperating rotors erected therein which are bearing-mounted with 
shafts at their ends, whereby on at least one end of the housing the shaft 
of each of the rotors rests in a pair of bearings, whereby the bearings of 
one pair are situated opposite the bearings of the other pair, and whereby 
at least one spray element for spraying lubricating liquid on the bearings 
is erected between the bearings of the pairs. 
2. Description of the Related Art 
Such machines are, for example, compressors, tube expanders and pumps. 
Especially with dry compressors, whereby no lubricating liquid such as oil 
or water is injected on the rotors, the bearings are usually lubricated by 
continuously spraying oil on the bearings. 
In such known compressors, the spray element contains two tubes directed 
diagonally on the shafts which reach between the bearings of one pair, the 
other pair, respectively. The tubes are provided at their ends with 
nozzles directed sideways on the bearings of the respective pair. As a 
result, the construction of this spray element is complicated and the oil 
distribution is not always ideal. 
SUMMARY OF THE INVENTION 
The present invention aims towards a machine with bearing-mounted rotors 
which does not show these and other disadvantages and whereby an effective 
lubrication of the bearings may be obtained with a simple spray element. 
This aim is reached according to the invention in that, between the 
bearings of each pair, a ring is provided around the respective shaft 
which is provided with a protruding ridge on its outer perimeter. A spray 
element with nozzles is directed towards the protruding ridges of the 
ridged rings. 
Thus, the spray element no longer sprays a lubricating liquid directly on 
the bearings, but on the toothed rings which distribute the lubricating 
liquid with the protruding ridges and deliver it to the two bearings 
situated on either side thereof. The ridged rings turn along with the 
shafts and guarantee a good distribution. 
The spray element may contain two radial tubes which reach up between the 
bearings of the two pairs, respectively, and which are preferably 
connected to an axial tube which is connected to a duct that extends 
through the housing. 
The duct may then be connected to a pump or the like via a pipe. 
The above-mentioned aim may also be realized according to another 
embodiment of the invention in that a stationary outer ring and a rotating 
inner ring of one of the bearings of each pair extend on the side of the 
other bearing outside the bearing elements which they hold and in that at 
least two openings are provided in a protruding part of the stationary 
outer ring of the first-mentioned bearing of each pair, whereby in or 
opposite one opening is situated a nozzle of the spray element. 
This spray element may contain two radial tubes, one of which extends into 
one of the openings in the outer ring of the one bearing of one pair and 
the other of which extends into one of the openings in the outer ring of 
one bearing of the other pair. 
The above-mentioned bearing with protruding parts of the inner and outer 
rings is preferably a ball bearing and the protruding part of the rotating 
inner ring of this bearing preferably has a smaller thickness than the 
part of this inner ring situated on the other side in relation to the 
balls.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIG. 1 shows a screw-type compressor of the dry type, i.e., without any 
injection of lubricating liquid, which mainly includes a housing 1 and two 
cooperating rotors which are bearing-mounted therein, namely a first 
female rotor 2 and a second male rotor 3. 
Housing 1 is provided with an air inlet and an outlet for compressed air, 
which are not represented in the figures. 
First rotor 2 has a helical body 4 provided on a shaft with ends 5, 5A 
which are situated in shaft openings 6, 6A, respectively, in housing 1. 
Shaft end 5 is surrounded in shaft opening 6 by a shaft seal 7. On the 
outside of this seal, shaft end 5 is bearing-mounted in a first pair of 
bearings, namely a radial bearing 8, for example a roller bearing, which 
is provided in housing 1, and an axial bearing 9, for example a ball 
bearing, which surrounds shaft end 5 outside shaft opening 6. 
In an analogous manner, shaft end 5A is surrounded at the other end of 
first rotor 2 by a shaft seal 10 and is bearing-mounted in a second pair 
of bearings, namely a radial bearing 11, for example a roller bearing, 
which is situated inside housing 1, and an axial bearing 12, for example a 
ball bearing, which surrounds shaft end 5A. 
Second rotor 3 has a body 13, which is complementary to body 4, provided on 
a shaft with ends 14, 14A which are situated in shaft openings 15, 15A, 
respectively, in housing 1. 
Shaft ends 14 and 14A are bearing-mounted in the same manner as shaft ends 
5 and 5A. 
Shaft end 14 is surrounded in shaft opening 15 by a shaft seal 16, which is 
similar to shaft seal 7, and is bearing-mounted in a third pair of 
bearings, a radial bearing 17 and an axial bearing 18. 
Bearings 17 and 18 of shaft end 14 are situated exactly opposite bearing 8 
and bearing 9, respectively, of shaft end 5. 
Shaft end 14A is surrounded by a shaft seal 19 and is bearing-mounted in a 
fourth pair of bearings, a radial bearing 20, for example a roller 
bearing, and an axial bearing 21, for example a ball bearing. Bearings 20 
and 21 are situated exactly opposite bearing 11 and bearing 12, 
respectively, of shaft end 5A. 
On shaft ends 5 and 14, on one end of rotors 2 and 3, synchronization gears 
22 and 22A are fixed which work in conjunction with one another such that 
second rotor 3 drives first rotor 2 synchronously. 
Gears 22 and 22A are held against axial bearings 9 and 18, respectively, by 
end parts 23 and 23A screwed on shaft ends 5 and 14. Bearings 9 and 18 are 
held against a part of housing 1 by a first ring 24 and a second ring 24A, 
respectively. Bearings 8 and 17 are held countersunk in housing 1 by a 
first corrugated spring 25 and a second corrugated spring 25A, 
respectively. 
Second rotor 3 is driven by a motor via a gear wheel 26 on shaft end 14A. 
Gear wheel 26 is part of a gear wheel transmission, not represented in the 
figures. 
Radial bearings 8, 11, 17 and 20 and axial bearings 9, 12, 18 and 21 are 
lubricated with lubricating liquid, for example oil. 
To this end, the compressor includes a first spray element 27 at one end 
between first pair of bearings 8, 9 on shaft end 5 and third pair of 
bearings 17, 18 on shaft end 14. First spray element 27 is connected via a 
duct 28 through housing 1 to a source of lubricating liquid under 
pressure, not represented in the figures. 
As is represented in FIGS. 2 to 4, first spray element 27 comprises: a tube 
29 which fits in duct 28; a fixing part 30 with which first spray element 
27 is fixed against a part of housing 1; a first and a second sidewardly 
directed or radial tubes 31 and 31A connected thereto which are provided 
with a first nozzle 32, a second nozzle 32A, respectively, at their ends 
and which are connected to the inside of tube 29; and an axial tube 33 
which forms the prolongation of tube 29 and which is provided near its end 
with a sidewardly directed nozzle 34. 
Spray element 27 is directed, with radial tubes 31 and 31A, respectively, 
between bearings 8 and 9 and between bearings 17 and 18, onto a first 
ridged ring 35 which surrounds shaft end 5 between bearings 8 and 9 and 
onto a second ridged ring 35A which surrounds shaft end 14 between 
bearings 17 and 18. 
Ridged rings 35 and 35A are provided on their entire outer perimeter with a 
first protruding ridge 36 and a second protruding ridges 36A, 
respectively, which have an almost triangular section with two sloping 
sides running into one point at the top. 
First corrugated spring 25 and a part of first ring 24 surround first 
ridged ring 35 around shaft end 5, whereas second corrugated spring 25A 
and a part of second ring 24A are situated around second ridged ring 35A. 
Also, radial tubes 31 and 31A partly extend into openings 37 and 37A which 
extend radially through rings 24, 24A, respectively. Diametrically 
opposite opening 37, 37A is a second opening 38, 38A in ring 24, 24A for 
discharging the lubricating oil. 
Lubricating liquid which is sprayed through first nozzle 32 is directed to 
bearings 8 and 9 by first protruding ridge 36 of first ridged ring 35 
which turns along with shaft end 5. Lubricating liquid which is sprayed 
through second nozzle 32A onto second protruding ridge 36A of second 
ridged ring 35A, which turns along with shaft end 14, is directed towards 
bearings 17 and 18. As a result, bearings 8, 9, 17 and 18 are efficiently 
lubricated. 
Through sidewardly directed nozzle 34, lubricating oil is sprayed on 
synchronization gear wheel 22 in order to lubricate synchronization gears 
22 and 22A. 
At the other end of the compressor, bearings 11 and 12 are situated against 
one another and are pushed against one another by an end part 39 screwed 
on shaft end 5A. A stationary outer ring 40 of bearing 12 pushes against a 
part of housing 1. 
Both stationary outer ring 40 and a rotating inner ring 41 of axial bearing 
12, which is formed of a ball bearing, extend on one side of radial 
bearing 11 and are thus longer than in a normal ball bearing so that they 
significantly protrude outside a set of bearing elements, namely balls 42. 
The protruding ring parts have a constant thickness, but the thickness of 
this part on inner ring 41 is smaller than the thickness of inner ring 41 
on the other side of balls 42, as is represented in detail in FIG. 5. 
In the protruding part of stationary outer ring 40, radial openings 43 are 
provided. 
Bearings 20 and 21 of shaft end 14A are designed and mounted in the same 
manner as bearings 11 and 12. They are pushed against one another by end 
part 39 which is screwed on shaft end 14A and with the help of gear wheel 
26, whereby stationary outer ring 40 of bearing 21 pushes against a part 
of housing 1. 
Bearings 11, 12, 20 and 21 are lubricated with oil which is sprayed through 
a second spray element 27A, which is identical to first spray element 27, 
and corresponding parts are indicated with the same reference numerals. 
First radial tube 31 of second spray element 27A extends into one of radial 
openings 43 in outer ring 40 of axial bearing 12, whereas second radial 
tube 31A of second spray element 27A extends into one of radial openings 
43 in stationary outer ring 40 of bearing 21, such that oil is sprayed on 
inner rings 41 and thus on bearings 11 and 12, 20 and 21, respectively, 
via nozzles 32 and 32A. 
Thus is obtained a good lubrication of bearings 11, 12, 20 and 21. 
Thanks to integrated ducts 28 in housing 1 and spray elements 27 and 27A, a 
very well controlled oil distribution may be obtained. 
The present invention is by no means limited to the above-described 
embodiments represented in the accompanying drawings; on the contrary, 
such machines may be made in all sorts of variants while still remaining 
within the scope of the invention.