Connecting device between a lubricated motor and a rotating electric machine

The connecting device is interposed between a rotating electric machine and a toothed lubricated device of the speed-reducer or multiplier type, this device comprising an output shaft of the electric machine, a screen, for opposing the propagation, towards the electric machine, of eventual lubricant leak in the vicinity of the shaft of the toothed device, closes, on one side, a cavity at the end of the casing of this toothed device and whereby this cavity presents on its lower portion an outlet hole for discharging the lubricant leaks, and the rotating screen presents a cylindrical projection directed towards the inside of the cavity and disposed so as to deviate towards the discharge hole the lubricant particles escaping from the toothed device. Application to the connection of the electric starter with an aeroplane or helicopter motor.

BACKGROUND OF THE INVENTION 
The invention concerns a connection device between a lubricated motor and a 
rotating electric machine, this device comprising a screen in order to 
prevent propagation of the lubricant towards the vicinity of the electric 
machine. 
BACKGROUND OF THE PRIOR ART 
The starting of the compressor of the turbine in aeroplanes or helicopters 
is carried out by using an electric motor which, after starting has been 
achieved, is utilized as an electricity generator. In general, the 
compressor rotates at a speed distinctly faster than that which could be 
supported by the motor-generator assembly (hereinafter referred to, for 
simplicity's sake, as "the starter"). This is the reason why a meshing or 
gearing device is foreseen to serve as a speed-multiplier during starting 
and as a speed-reducer during normal running. 
The functioning of the starter could be disturbed by lubricating oil leaks 
issuing from the gearing device. 
Until now, in order to prevent these leaks, a screen mounted on the output 
shaft of the starter has been foreseen that closes, on one side, a cavity 
at the end of the gear-case or casing of the gearing device, and this 
cavity has, on its lower portion, an outlet hole for discharging said 
lubricant. This screen, which can be in the shape of a disk, forms, for 
example, the armature of a damping device or vibration and/or 
shock-absorber in torque. 
But, it has been observed that these measures can, for important leaks, be 
only partially effective. 
BRIEF DESCRIPTION OF THE INVENTION 
The present invention allows to reduce to a large extent the risks of 
propagation of the lubricating oil towards the vicinity of the starter. 
One object of the present invention is that the rotating screen is directed 
towards the inside of the cavity and disposed so as to deviate towards the 
outlet hole the particles of the lubricant escaping from the periphery of 
the shaft of the gearing device. The invention results, in fact, from the 
observation that in the connecting devices of the prior art, the lubricant 
particles escape from the periphery of the shaft and are carried along to 
the periphery of the screen by centrifugal force created by the rotation, 
and they thus surround the screen and are propagated towards the vicinity 
of the starter through the clearance that is necessarily provided between 
the periphery of this rotating screen and the inside surface of an 
attachment clip mounted at the end of the casing of the gearing device. 
In one preferred embodiment of the invention, the projection is 
cylindrical, having the same axis as the shaft. In this case, in order to 
further reduce the risks of propagation of the lubricant, the attachment 
clip or clamp of the starter terminates in a nose-piece penetrating a 
cavity and to this nose-piece is attached, towards the inside of the 
cavity, a wall having an opening, the edge of which is separated by a 
small distance, for example about 0.8 mm, from the periphery of the 
cylindrical projecting wall of the rotating screen. Thus between the 
periphery of the shaft and the periphery of the screen are formed baffled 
elements that render effectively more difficult the propagation of the 
particles of lubricant towards the periphery of the screen. Furthermore, 
the wall of the attachment clip of the starter increases, at the lower 
portion, the volume of the lubricant that can be accumulated, prior to its 
evacuation through the discharge hole, thereby further reducing the risks 
of propagation of the lubricant towards the vicinity of the starter. 
In one variation the opening of the wall of the attachment clip of the 
starter has, directed towards the vicinity of the gearing device, an edge 
in the form of a spout or shoot so as to guide towards the discharging 
hole the particles projected by the centrifugal force against the wall.

The following example is described with reference to an electric starter 
for aeroplane or helicopter turbine engines, this starter also functioning 
as an electricity generator once starting has been achieved. 
The figure represents the end of electric starting motor 10 as well as the 
end of toothed reducer-multiplier device 11, interposed between starter 10 
and the compressor (not represented) of the turbine of the aeroplane. 
The connection of output shaft 12 of starter 10 to the shaft of device 11 
is obtained by foreseeing that shaft 12 presents an end 13 with slots of 
axial direction penetrating the complementary grooves inside an opening 14 
at the end of shaft 15 of device 11. Furthermore, shaft 12 presents an end 
cavity 16 intended to ensure the lubrication of end 13 of shaft 12. At the 
vicinity of the end of shaft 15 is provided, between the inside surface of 
opening 14 and shaft 12 a sealing ring 17 in order to prevent the 
propagation of the lubricating oil of device 11 towards starter 10. But 
oil leaks are, normally, unavoidable. Furthermore, arrows 18 represent the 
direction and flow sense of the oil leaks issuing from opening or cavity 
14. Oil, also generally escapes by the periphery of shaft 15 as 
represented by arrows 19; this oil issues from a rotating sealing ring 60 
assembled on shaft 15. 
Shaft 15 terminates inside a central cavity 20 that has an end 21 of the 
casing of device 11. The cavity 20 is limited by a cylindrical wall 22 
having the same axis 23 as shafts 12 and 15 and receives end 24 of an 
attachment clip 25 of starter 10. 
End 24 has the shape of a nose-piece at the external cylindrical surface 
with a peripheral groove 26 houslng a sealing ring 27, which is also 
applied against cylindrical surface 22. 
To cylindrical wall 24.sub.1 of the end of the clip is attached, according 
to the invention, a wall 28 perpendicular to axis 23 with a circular 
opening 28.sub.1 of a diameter substantially larger than the outside 
diameter of shaft 15 at its end. Opening 28 presents, towards the inside 
of cavity 20, an annular flange 29 with a return 30 distancing away from 
axis 23 in a delimited manner, between face 31 of wall 28 that is directed 
towards recess 20 and this return 30, a spout 32 the purpose of which will 
be explained hereinbelow. 
End 24 of clip 25 is attached to a wall 33, also forming part of clip 25, 
that is applied against end face 34 of casing 21 of device 11 through the 
intermediary of a metal plate 35, that is fixed against face 34 forming 
part of a cover or cowling 37. Wall 33 is connected to the end of the 
housing of starter 10 by arms 36 forming a sleeve and which are surrounded 
by cover 37 sheet metal which terminates with said plate 35. This cover 37 
is open on its lower portion and is extended by an aeration vent 39 made 
of a single piece with cover 37 and plate 35. 
Shaft 12 is coaxial with slotted end 13 a disk 40 includes annular wall 50 
having a diameter slightly smaller than that of opening 28 with a 
periphery 41 at a small distance away from bevelled face 42 limiting the 
connecting part 43 of nose-piece 24 to wall 33. 
Disk 40 forms an armature of dampener 45 that comprises a second armature 
46 with a crown of substantially the same diameter as disk 40 and 
separated from said disk by active element 47 of the dampening in torque. 
According to the invention, disk 40, which constitutes a screen closing 
cavity 20 to be opposed to the propagation of the particles of lubricant 
towards the vicinity of starter 10, is projecting, towards the inside of 
cavity 20, a cylindrical wall 10 having an axis 23, the outside diameter 
of which is very slighty smaller than the diameter of opening 28.sub.1. In 
the example, the distance between the external surface of cylinder 50 and 
the edge of opening 28 is about 0.8 mm. In this example, the distance 
separating wall 28 from disk 40 is about 3 mm and cylindrical wall 50 is, 
inside cavity 20, slightly projecting with respect to edge 29. Shaft 15 
slightly projects inside cavity 20 to the extent that its end 14.sub.1 is 
closer to starter 10 than end 50.sub.1 of wall 50. 
Furthermore, at its lower portion, the end of casing 21 comprises a outlet 
hole 51 to discharge oil 52 that can be accumulated in the lower portion 
of cavity 20. In this lower portion of cavity 20 is thus formed a tank 
limited by a vertical wall that is constituted by the lower portion of 
wall 28 and another vertical wall 53 of casing 21. 
The system functions as follows: 
When the lubricant leaks occur oil droplets escape from device 11 with a 
course that begins according to arrows 18 and 19. The rotation provokes a 
centrifugal force that projects these droplets onto the inside surface of 
cylindrical wall 50 and towards surface 22 (non-rotating) as well as 
towards the inside surface of wall 28 (which is also non-rotating). In the 
upper portion the oil tends to gather together in spout 32 from which it 
is guided towards the lower portion in order to flow into the 
above-mentioned tank from which it is discharged through outlet hole 51. 
Thus, wall 50 constitutes an obstacle to be opposed to the propagation of 
the oil towards periphery 41 of disk 40, i.e. towards starter 10. 
Furthermore, this cylindrical wall 50 with edge 29 constitutes baffle 
elements which also oppose the propagation of the oil towards starter 10. 
It should also be noted that wall 28, which was not foreseen in connecting 
devices of the prior art, increases the volume of the oil accumulation 
tank at the lower portion, which is also favorable to minimizing 
propagation. Further, the invention can also be applied to opposing the 
propagation of oil towards starter 10 when the motor is cut out.