Note: Descriptions are shown in the official language in which they were submitted.
~ack~round of the Invention
This invention relates to a means for drivingly intercon-
necting a first assembly to a second assembly. In particular, it
relates to interconnecting the Elywheel of a heavy construction
vehicle to a hydrostatic transmission in the vehicle.
Interconnection of the power plant of a vehicle to the drive
train of the vehicle presents a unique problem in alignment since
the drive train which usually includes a transmission is usually a
separate unit from the vehicle engine. Since any misalignment be-
tween the power plant and the vehicle drive train results in friction
losses during operation of the power plant and drive train9 minimization
of the misalignment is not only desirable, but necessary. In certain
instances it has boen found appropriate to utilize flexible or resilient
members between the power plant and the vehicle transmission. However,
such flexible members can impart an undesirable load to the associated
bearings causing premature failure.
Flexible or resilient interconnecting means between the vehicle
engine and the vehicle drive train also present problems in assembly of
the two components. It is generally necessary to provide access to
both sides of the flexible member if the flexible member is to be dis-
assembled in the field. However, since the flexible member may bemolded, it may be more appropriate to provide a disassembly point on
either side of the flexible member. In any event, the flexible
member is an expedient that has not proved in all cases to be appro-
priate.
Space and weight are generally problems in the construction of
any type of vehicle. The drive train length should, therefore, be
made as short as possible commensurate with vehicle design without loss
of efficiency. It is also important in internal combustion engines
to include a large rotating mass to provide momentum to the engine
crank shaft. This can be accomplished in any one of a number of ways.
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For example9 in an aircraft engine the mass may be in the form of a
propeller. In certain types of heavy equipment, the mass may be a
large rotating portion of the drive train. In many engines it is
appropriate to include a flywheel affixed to the crank shaft. In
those engines which include a flywheel affixed to the crank shaft,
connection oE the engine f]ywheel to the transmission has been accom-
plished in some installations through the use of the resilient flexi-
ble fitting noted above. Since the entire drive train is generally
separated from the engine at a point proximate the flywheel, it has
proved appropriate to form the flywheel housing in two portions so
that the drive train and transmission may be separated coincident with
the separation of the flywheel housing. This type of separation may
introduce a misalignment problem between the transmission and the
flywheel. Accordingly, such misalignment should be readily absorbed
in the interconnecting drive member. If the interconnecting drive
member were such that separation of the transmission required a
separate effort on the part of the separating mechanic to disconnect
the interconnecting drive member, the length which is important, and
in some instances critical, would of necessity be increased. Accord-
ingly, it i5 appropriate to design the interconnecting drive memberwith the shortest possible length.
In providing a short length interconnecting link between a
fl~heel and a transmission, it would be desirable for the inter-
connecting link to remain with either the flywheel or the transmission
during disconnection of one from the other. As a corollary function
to a retention means to meet this need, it has been found that the
retention means may prevent a sheared interconnecting shaft from dis-
associating itself from the flywheel in the event of failure of the
shaft.
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Finally, in design of any machinery element, ;t is appropriate
to prevent errors which may take place during assembly. Such errors in a
non-symmetrical shaft member which has similar, but not identical con-
struction at both ends may occur when the mechanic inadvertently places
the non-symmetrical drive shaft in the machine in -the wrong orientation.
The most common ~ay to prevent an assemb ly error is to ensure that the
two ends of the shaft are visually dissimilar. This has the inherent
drawback that the assembling mechanic may be forced to refer to an assembly
drawing to determine the proper orientation of the part. A second means
for insuring proper orientation at assemkly is to utilize similar
structure at either end of an interconnecting shaft, but to differ the
shaft dimension 50 that assembly is only possible in one orientation.
This type of structure results ïn the drawback that a minor dimension
difference could result in a mechanic attempting to force assembly of the
structure.
According to one aspect of the invention there is provided a
drive connection comprising a housing having a first portion and a second
portion, said second portion removably associatable with said first
portion; a first assembly mounted for rotation in said first portion;
a second assembly mounted for rotation in said second portion of said
housing and substantially axially aligned with said first assembly, said
second assemkly including a source of lubricant; a symmetrical splined
drive shaft drivingly positionable in said fi`rst assem~ly and drivingly
connacting said first assembly with said second assembly; and retention means
for fixedly retaining said splined drive shaft in said first assembly; said
first assembly including a drive shaft rotatingly mounted in the first portion
of the housing; and further wherein the first assembly includes a flywheel
first portion removably-affixed to said drive shaft and rotatable in said
housing, and an axially- socketed second portion axially disposed in said
flywheel first portion for rotation therewith; said axially socketed second
.
portion defining an axial bore with at least a portion of said axial
bore having a plurality of inwardly extending splines adapted to receive
either end of the splined drive shaft; said splined drive shaft defining
an axial bore and an enlarged center portion, said enlarged center portion
forming a shoulder generally at the midpoint of said splined drive shaft,
said shoulder circumferentlally surrounding said splined drive shaft and
positionable in the axial bore of tfie socketed second portion of the
flywheel assembly, said axial bore of said splined drive shaft for
communicating lubricant from the second assembly to the axial bore of the
socketed second portion.
According to another aspect of the invention, there is provided
a drive connection comprising: a housing having a first portion and a
second portion, said second portion removably associatable with said first
portion; a drive shaft rotatably mounted in said first portion of the
housing; a flywheel first portion removably affixed said drive shaft and
rotatable in said housing; an axially socketed second portion axially
disposed in said flywheel first portion for rotation therewith, said axially
socketed second portion defining an axi`al bore with at least a portion of
said axial bore having a plurality of inwardly extending splines; a
symmetric splined drive shaft drivingly positionable in said axially
socketed second portion for drivingly connecting said axially socketed
second portion with said second assembly, said splined drive shaft defining
an axial bore therethrough; retention means for fixedly retaining said drive
shaft in said axially socketed second portion; cap means for sealing the
end of the axial bore of the axially socketed second portion adjacent
the drïve shaft; and a first seal member disposed about said splined drive
shaft interior of the axial bore of said axially socketed second portion;
said second portion of said housing including a source of lubricant, said
splined drive shaft defining an enlarged center portion forming a shoulder
generally at the midpoint thereof, said shoulder circumferentially surround-
ing said splined drive shaft and positionable in said axial bore of socketed
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second portion, said axial bore of said splined drive shaft for
communicating lubricant from said second assembly to said axial bore of
said socketed second portion.
Brief Descrlption of the Drawing
The sole figure accompanying this application depicts partly
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in section an elevation of one embodiment of a connection according
to the invention.
Detailed Description
Depicted in the sole drawing, is a housing 10 comprised of a
first portion 12 which may be affixed to a frame 13 by bolts or the
like and a second portion 14 which may be substantially aligned with
first portion 12 by means such as flange 15 or the like and affixed
thereto by bolt means or the like. First portion 12 of housing 10
substantially encompasses a first assembly mounted for rotation therein
and which includes flywheel assembly 16 driven by a drive shaft 18.
Drive shaft 18 may be the extension of a crankshaft of an internal
combustion engine such as a diesel engine or the like.
Journaled for rotation in second portion 14 by a bearing such
as tapered bearing 20 is a second assembly including driven member 22
which may drive a transmission such as a hydrostatic transmission or
the like. Driven member 22 is in substantial axial alignment with
flywheel assembly 16. Other bearing means such as tapered bearing 24
may further support driven member 22. Driven member 22 may be
associated with a source of lubricant under relatively low pressure
such as 5 lbs. per square inch (3.5 x 104 Pa3, such lubricant being
provided to an axial bore 26 formed in driven member 22.
Flywheel assembly 16 may be formed of a first portion 28 and
a second portion 30 affixed to first portion 28 by a plurality of
bolts 32. First portion 28 may in turn be affixed to drive shaft 18
by a plurality of bolts 34. A sealing member 36 may be disposed be-
tween flywheel first portion 28 and drive shaft 18 so that an oil
seal 38 may be utili~ed between first portion 12 of housing 10 and
sealing member 36. A similar oil seal 40 may be disposed between
driven member 22 and second portion 14 of housing 10.
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Flywheel second portion 30 is formed with a stepped axial bore
42 which terminates generally with an internal spline 44 at the end
proxmiate drive shaft 18 and which serves to receive one end of a
symmetrical splined drive shaft 56. The stepped axial bore 42 is
formed with a first counterbore 46 at the end distal of internal spline
44. Intermediate the end of axial bore 42 is a counterbore 47 of
relatively less diameter than counterbore 46 which in turn is followed
by a third counterbore 48 distal of counterbore 46 and of relatively
less diameter than counterbore 47. Formed in counterbore 46 and proxi-
mate the outer end thereof is an annular groove 49, the purpose ofwhich will become apparent in the following discussion. Proximate
internal spline 44 and formed in flywheel second portion 30, is a
counterbore 50 in which a cup like plug 52 may be disposed to retain
oil, as will become apparent in the ensuing discussion.
Axial bore 26 of driven member 22 has formed at the end ad-
jacent second portion of housing 10 an internal spline 54 adapted to
receive the other end of the symmetrical splined drive shaft 56 thus
interconnecting the flywheel assembly 16 with the second assembly 22.
Symmetrical splined drive shaft 56 is formed with a spline 58
at either end thereof which serve to allow a small misalignment be-
tween the flywheel assembly 16 and the driven assembly 22. Since
drive shaft 56 is symmetrical, it is appropriate to refer to the
features of one end only. The symmetry of the splined drive shaft
permits installation, either as indicated in the figure or in a
reverse of the indication in the figure. Thus, the spline 58 may mate
either with the spline 54 of the driven member or the spline 44 of
the second portion 30 of flywheel assembly 16. The symmetrical splined
drive shaft 56 has formed generally at the mid-point thereof a shoulder
60 circumferentially surrounding the drive shaft. Shoulder 60 is
formed on center portion 62 of drive shaft 56. Center section 62
;
extends in either direction from shoulder 60 to an intermediate porti~n
64 of drive shaft 56 and of lesser diameter than center section 62.
Intermediate portions 64 are adapted to fit either the axial bore 26
of the driven member 22 or the third counterbore 48 of flywheel second
portion 30, while the center portion 62 is adapted to be received in
the second counterbore 47 of the flywheel second portion with the
shoulder 60 adapted to be received in the first counterbore 46 of
the flywheel second portion.
An annular groove 66 is formed in each intermediate portion 64
and may have disposed therein a seal member such as 0-ring 68. 0-ring
68 serves to seal axial bore 26 of driven assembly 22 and the corres-
ponding 0-ring 68, when disposed in third counterbore 48, serves to seal
stepped third axial bore 42 of second portion 30.
In use the syrnmetrical splined shaft is positioned in the
socketed flywheel second portion 30, as indicated in the figure, and
retained therein by a retention means such as split ring 70 disposed
in annular groove 49. At the opposite end splines 58 mate with splines
54 of driven member 22. The splines 58 mating with the flywheel second
portion splines 44 are lubricated by an axial bore 72, communicating
lubricating fluid from axial bore 26 of driven member 22 to the
splines 44. The cup-like plug 52 serves to retain the lubricating
fluid in the vicinity of the splines 44. Due to the limited amount of
friction developed in this coupling, a pressurized lubricating system
is not necessary. ~owever, the slight pressure maintained in axial
bore 26 is sufficient to provide lubricant to the splines. Since
housing 10 may be a dry housing, that is a housing in which lubricant
is not accumulated, a drain port 64 may be provided to drain leakage
lubricant from housing 10. It should be apparent to those in the
art that the use of the splines 58 on the symmetrical drive shaft and
the mating with the splines 44 and 54 allows for a certain degree of
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misalignment between the flywheel's second portion 30 and the driven
member 22 without imparting an unnecessary load to either the bearing
20 or the bearing 24. In addition to the normal spline 58, it has
been found appropriate to provide a certain degree of "crowning" to
each spline which may be seen in exaggerated form in the drawing as
the curved outer portion of the spline. This crowning allows for a
certain additional amount of misalignment between the two elements,
as noted above.
The split ring 70 serves several useful purposes. During
assembly, the symmetrical splined drive shaft 56 is positioned in
the flywheel second portion. As previously noted, the symmetry of
the splined drive shaft is such that a mechanic need not worry about
which end is positioned in socketed flywheel second portion 30. The
socketed portion permits lubricant to be received at the splined end
through the hollow splined drive shaft 56 while a split ring 70 is
positioned in the annular groove 49 to act on shoulder 60. Thus, the
symmetrical splined drive shaft 56 is retained in the flywheel second
portion in the manner indicated in the figure. The driven member 22
and the housing 14, which may have been previously preassembled, may
then be mated with the symmetrical drive shaft 56 with the spline 58
mating with the spline 54 of the driven member. During this assembly
it should be apparent that the symmetrical splined drive shaft 56 will
be retained in the flywheel second portion 30 thus preventing damage
occurring to the splines during such assembly or if the drive shaft
were inadvertently dropped during subsequent withdrawal of the driven
mernber.
In the past, it has been appropriate to provide access to the
interconnecting means analagous to symmetrical splined drive shaft 56
before the driven member is disassembled from the driving member in
order to prevent damage to the interconnecting member. This is
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obviated in this invention by providing the elongated symmetrical splined
drive shaft fitted in the socketed flywheel second portion and retained
therein by retainer 70. Finally, the retainer 70 serves to retain a
portion of the symmetrical splined drive shaft 56 in the event the
splined drive shaft is sheared during operation. Since shear would
normally occur at the smallest diameter point, that is annular groove
66, a break at either annular groove will retain at least the major
portion of the symmetrical splined drive shaft 56 within the flywheel
second porti.on without the remaining portion damaging the flywheel
housing or the like.
Although this invention has been described in relation to a
particular embodiment, it is considered that the invention shouLd be
not so limited, but rather should be limited only by the appended
claims.
