Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
The present inventiQn relates -to a hydrodyn~nic
power transmission uni-t, -and more particularly, to a
clu-tch comprising a pair of radially extending, bladed,
cup-shaped discs, and to means for direc-ting lubricating
fluid to the bearings of such a clutch and preventing the
in-terference of such lubricating fluid in the drive
components of the clutch.
A hydrodynamic clutch is utilized for driving
the cooling fan in an air-cooled internal combustion engine
in which the drive fluid is metered and injected in the
clutch, and the metering of the fluid is controlled by a
control unit associated with the engine which varies as a
function of the engine operating characteristics as
described in copending Canadian patent applica-tion
Such hydrodynamic clutches for the purpose of driving
cooling fans are, of course, known (German Patent 921,181).
In order to avoid the interference of the lubricating oil
into the driving components of the clutch, such clutches
are mounted on bearings which do not require lubricating
oils, such as roller or needle bearings. However, it has
been found that such bearings can be easily contaminated
and are not sufficiently wear-proof. These bearings are
also expensive.
It is a purpose of the present invention to
provide a hydrodynamic power transmission unit, such as a
hydrodynamic clutch, which can be mounted using low cost,
high wear-resistant bearings which require a continuous
supply of lubricating fluid.
It is a further aim of the present invention to
provide such a hydrodynarnic power transmission un:it mounted
on bearings which require lubricating fluid while preventing
the fluid from interferirlg with the drivlng components of
the hydrodynamic power transmission unitO
It is a further aim of the present invention to
u-tilize -the same fluid for lubricating -the bearings of
the hydrodynamic clutch as for driving the clutch while
isolating the circulation of fluid to the bearings from
the distribution of the fluid under controlled conditions
to the impeller disc of the clutch and thus to the turbine
disc.
A construction in accordance with the present
invention comprises a hydrodynamic power transmission unit
having a drive shaft, a radial cup-shaped impeller disc
mounted on said drive shaft, the drive shaft being journalled
in support bearings, a shaft to be driven being coaxial with
said drive shaft and mounted for ro-tation in support hear-
ings, a radial cup-shaped -turbine disc mounted Oll said drive
shaft and complementing said impeller disc, means for
injecting fluid to an annular outer part of said impeller
disc under controlled conditions, separate means for feeding
such fluid under pressure to said bearings for lubricating
said bearings, conduit means for evacuating said fluid from
said bearings, port means in an inner annular portion of
said impeller and turbine discs, the conduit means
communicating with the port means in the impeller disc,
conduit means communicating with a fluid outlet and the
port means in said turbine disc whereby fluid under pressure
is evacuated from said bearings through said conduits and
port means to the outlet.
In a more specific embodiment, the turbine disc
is provided with an annular recess facing the port means
in the impeller, and includes an annular cylindrical surface
forming the outer wall of the recess, the impeller disc
including an annular rib extending cor-centrically w:ith the
outer wall of the recess and within the recess, -the port
means in the impeller being located within the confines of
the rib, the port means in the turbine disc being within
the confines of the recess.
It is evident that if the lubrica-ting fluid, such
as oil, is allowed to interfere or otherwise leak to the
outer annular portions of the impeller and turbine discs,
the power transmission unit will no-t operate in accordance
with an otherwise meticulously controlled fashion. If the
lubricating oil which is fed under pressure is allowed to
interfere between the operative components of the hydro-
dynamic transmission means, such as a clutch for a cooling
fan motor, the fan will be opera-ted to cool the engine when,
in fact, it should not be operated. The advantage of the
s-tructural arrangement described above is that i-t allows
the completèly separate evacuation of the oil under pressure
from the bearings to its outlet towards a common collector
reservoir. It also allows the use of oil lubrica-ted bear-
ings, thereby reducing the probahility of contarnination of
2~ the bearings and also increasing bearing efficiency at
lower cost. It is also known that pressurized oil
luhricated bearings operate at lower noise levels.
It is also noted that the same oil can be used
hoth for feeding the bearings and for the controlled
fluids for operating the hydrodynamic clutch. The oil can
be drawn for both purposes from the same common container
and can be collected jointly at the outlet of the conduits
from the bearings.
In a more specific embodiment of the present
invention, the torque means provided in the turbine disc
are in the form of elongated annular openings coinciding
with the recess in the turbine disc. F~lrthermore, passa~es
in the disc forming the port means may have a configura-tior
of increasing cross-section downstream of -the flow of the
pressurized oi1 being evacuated from the bearings.
In a still more specific embocliment, -the means
for feeding the oil under pressure to the bearings is in the
form of an axial bore in the drive shaft with radial
passages eommunica-ting the oil under pressure to the
bearings.
Having thus generally described -the nature of the
invention, referenee will now be made to the aceompanying
drawings, showing by way of illustration, a preferred
embodiment thereof, and in whieh:
Figure 1 is an axial cross-seetion of a hydro-
dynamie power transmission unlt in
aceordanee with the presen-t invention
and
Figure 2 is a radial eross-seetion, taken along
line II-II in Figure 1.
A hydrodynamie eluteh 1 for operating a eooling
fan in an air-eooled diesel engine is illus-trated in the
drawings. The eluteh includes a cup-shaped irnpeller disc
2, a eup-shaped turbine dise 3 complementing the impeller
dise. The impeller dise 2 is fixedly mounted to a hollow
drive shaft in the form of a gear wheel 4. The turbine
dise 3 is fixedly mounted to a drive shaft 5 to be driven
by the coupling or cluteh 1. The gear wheel drive shaft 4
may be driven by the internal combustion engine while the
drive shaft 5 is direetly connected to the cooling fan
(not shown).
A eover 6 having a eentral opening 7 is fixed to
the outer periphery of the turbine disc 3 and extencls over
the impeller disc 2. The cover 6 acts as a cGllector for
collecting the spent oil after the oil has been injected
into the clutch. The oil may be drained away from the
cover 6 to a cornmon collec-tor (not shown`i.
An injector nozzle 8, as shown in Figure 1, is
provided which extends within the opening 7 to inject
metered amounts of oil in-to the clutch. The operation of
the clutch by oil injected frorn -the injector 8 is, of
course, well known.
The gear wheel shaft 4 which drives the impeller
disc 2 is concentric with a portion of the drive shaft 5,
as shown in Figure 1. Cylindrical bearings 11 support and
space the -two concentric shafts and allow for relative
rotational movemen-t. The drive shaft 5 is provided wi-th a
central bore 12a which communica-tes with radial passages 12
which will be described in more detail. The central bore
12a communicates with feed lines 13 at one end thereof to
permit oil under pressure to pass through the bore 12a into
the passages 12 to feed the bearings 11 and 9.
An annular passage 14 which has a radial component
communicates with the bearings and the space between the
gear wheel shaft 4 and the drive shaft 5 -to evacuate the
oil under pressure which has been passed through the
bearings 9, 11. The passage 14 also has an angled component
directed towards the hub portion of the turbine disc 3.
The turbine disc 3 is provided with an annular recess 17
having a cylindrical outer wall surface while the impeller
wheel 2 has a rib 16 extending axially therefrom into the
recess 17 so that the cylindrical outer surface of the rib
16 and the cylindrical surface of the recess 17 overlap
each other. The outlet of the passa~es 14 is within the
recess 17 and, therefore, beyond the plane of demarcation
between the impeller disc 2 and the turbine disc 3.
The recess communicates with the rear of -the
turbine disc throuyh elonga-ted annular por-ts 15. I'he
configuration of the por-ts 14 and 15 are shown in Figure 2.
The ports 14 as well as the por-ts 15 can be made such -tha-t
they increase gradually in cross-section as one moves
downstrearn of -these respective por-ts.
Portions of the engine housing are illustrated
at lOa and lOb while the sealing ring 18 seals the oil
passages within the clutch from the exterior of the
housing.
After the oil passes through the ports 15, :it
exits through the radial openings outside of the confines
o.E the clutch and i.s allowed to be collected along with the
oil which has been directed to the operating parts of the
clutch by means of the injector 8. Thus, the above
configuration allows the oil destined for the bearings
to be kept separate from the operating components of the
clutch, that is, the outer annular portion thereof by
means of the passages 14 and 15 as well as the overlapping
lip or rib 16 with the recess 17. This confi~uration makes
it almost impossible for oil fed through the bearings to
feed into the outer operating parts of the clutch.
