Note: Descriptions are shown in the official language in which they were submitted.
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The invention relates to an oil-lubricating system
for gearboxes. More specifically, the invention relates to
an oil-lubricating system which is intended to provide a
lubricating point in the interior of a rotating gearbox shaft
with sufficient lubri.cating oil.
By means of an oil-lubricating system of this kind,
disclosed in German AS 27 33 294, specific points re~uiring
lubrication,.for example, gears which are difficult to supply
with sufficient oil, are to be uniformly lubricated even
under extreme driving conditions.
Other locations which are difficult -to supply with
lubricating oil are bearing supports in rotating gearbox
shafts in which other shafts are mounted~ It is known to
pass oil collected in pockets, through bores, directly in-to
the interior of a shaft. However, this oil can flow into the
interior only when the shaft is stationary since, when the
shaft is rotating, the centrifugal force acting upon the oil
is too largen Where the gearbox is in continuous operation,
with only brief stops, adequate lubrication of the bearing
supports is not assured.
It is the purpose of the invention to provide an oil-
lubricating system for gearboxes which will provide ade~uate
lubrication for bearing supports within rotating gearbox shaf-ts,
without substantially increasing the size of the gearbox. The
oil~lubricating system is also to be simple and ine~pensive in
assembly and manufacture and to consume littl~ power.
In accordance with the invention there is provided
an oil--lubricati.ng system for gearboxes, which system includes
at least one oil-collecting pocket and an annular collecting
groove open towards the peripheral surface of a rotating gear-
box shaft for lubricant supplied by a pump arranged upon the
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gearbox sha~t. Radial channels are associated wi-th the pump.
The suction point communicates with the oil-collectiny pocket
and at least one channel runs from the annular collecting
groove in the interior o~ the gearbox to at least one point
to be lubricated arranged in the interior of the gearbox
shaft. In accordance with the invention, the pump is in
the form of a centrifugal pump and contains a .substantially
disc-shaped impeller provided with vanes and the radial
channels are in the form of guide-channels, which run ~rom
the pressurized oil-collecting area, and are arranged radially
outwardly upon the centrifugal pump. In addition, the guide
channels are integral with the housing, run radially inwardly,
and communicate with the annular collecting groove.
The guide-channels in the housing make it possible
to displace the point at which the oil is delivered fxom the
outer periphery of the centrifugal pump to the outer periphery
of the rotating shaft. In this way, the pressure produced
by the centrifugal pump is sufficient to allow oil to enter
the interior of the gearbox shaft against centri~ugal force.
The design of the centrifugal-pump impeller is disc-
shaped, and the disc-shaped ~esign of the centrifugal-pump
impeller provides a lubricating device of small axial dimen-
sions. Axial openings in the impeller provide a component
which is pressure-compensated in the axial direction. This
eliminates the need for costly axial bearings ~or the impeller
and also keeps the axial dimensions of the device small. The
impeller is preferably made without machining, i.e. as a die-
casting or a stamped sheet-metal part.
The invention is explained hereinafter in greater
detail in conjunction with the exemplary embodiment illus-
trated in the drawings attached hereto, wherein:
Figure 1 shows a cross-section through a gearbox
comprising the oil-lubricating sys~em according ~o
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the invention,
Figure 2 is a cross-sec-tion through II-II o~ the
gearbox in Figure 1, and
Figure 3 is a cross-section through III-III of the
gearbox in Figure 1.
A gearbox shaft 1 is mounted rotatably in a gear~
box housing 2 by means of a bearing 3. Gears 4 and 5 are
arranged on the said shaft.
Mounted within gearbox shaft 1, by means of a bear-
ing 7, is a further gearbox shaft 6 carrying a gear 8..Shafts 1 and 6 are rotatable in relation to each other.
Bearing 7 comprises point 9 which is to be lubri-
cated and which is located in the interior of rotating gear-
box shaft 1. Such a point could heretofore be lubricated,
only when the drive-shaft was stationary, except at great
expense. In order to ensure adequate lubrication, a centrifu-
gal pump 10 is arranged upon gearbox shaft 1. The centrifugal
pump contains an impeller 11, a guide-member 12 and a cover-
plate 13~ Impeller 11 is secured against rotation in rela-
tion to gearbox shaft 1, while guide-member 12 and cover-
plate 13 are secured to the gearbox housing.
Impeller 11 is of substantially disc-shaped design
and carries vanes 14 on one side. The said impeller runs in
a stationary ch~mber 15 which is defined axially, on the one
hand by a smooth wall of gearbox housing 2 and, on the other
hand, by substantially flat cover-plate 13. The impeller
also comprises axial openings 16 at various locations~ In
the case of an impeller in the form of a stamped sheet-metal
part, each vane 14 has an opening 16. If a different produc-
tion process is used, for example die-casting, the openings,
which provide axial pressure-equalization for the impeller,
may also be located elsewhere. The impeller is designed, in
relation to chamber 15, in such a manner that it does not
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Axial openings 17 are provided at khe outer periphery
of chamber 15 in cover-plate 13. The openings provide a con-
nection between the pressurized-oil collecting chamber formed
at this point in chamber 15 and the guide-channels 18 arranged
in guide-member 12. Channels 18 run radially inwards and are
preferably curved. Located at the radially inward ends of guide
channels 18 is an annular collecting groove l9 which is open
towards the peripheral surface of gearbox shaft 1 and com-
municates through at least one channel 20 with an axi~l bore21 arranged in the interior of the said gearbox shaft. The
said annular collecting ring may be located in the gearbox
shaft or in the guide-member.
Located in what is normally the upper part of gear-
box housing 3 is an oil-collecting pocket 22 which communi~
cates, through at least one collecting channel 23 arranged
in guide-member 12, and an axial opening 24 in cover-plate
13, with a suction-point 25 of centrifugal pump lO, the
said suction-point being arranged at a radially inner loca-
tion in charnber 15.
The oil-lubrication system operates as follows: oil
sprayed into gearbox housing 3 is collected in oil-collecting
pocket 22 and is passed to centrifugal-pump suction-point
25. The oil is brought up to the rotational speed of the
shaft by rotating impeller ll. The pressure achieved in
the oil-ring rotating with the impeller is a function of
the rotational speed of the shaft and the dimensions of the
impeller. The oil-pressure is trans~erred to annular collect-
ing ring l9 by guide~channels 18 arranged in guide~member 12.
This pressure forces the oil into the interior of gearbox
shaft l against the centrifugal forceO
This arrangement of the oil-lubricating system
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makes it possible to use a centrifugal pump having only three
parts, all of which may be produced, without machining, in
the foxm of sheet-metal st~npings ox die-castings. Since
the p~np has no parts which come iIltO contact with each other
as it rotates, there is no wear and no danger of fretting.
Although a particular embodiment has been described,
this was for the purpose of illustrating, buk not limiting
the invention. Various modifications which will come
readily to the mind of one skilled in the art are within
the scope of the invention as defined in the appended claims.
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