U.S. patent number RE30,842 [Application Number 06/138,766] was granted by the patent office on 1982-01-05 for tensioning apparatus.
This patent grant is currently assigned to Dayco Corporation. Invention is credited to Billy L. Speer.
United States Patent |
RE30,842 |
Speer |
January 5, 1982 |
Tensioning apparatus
Abstract
A tensioning apparatus for an endless power transmission device
is provided and utilizes the elastic properties of an elastomeric
material to provide the tensioning action and such apparatus is
supported adjacent the endless power transmission device to be
tensioned and has components thereof operatively associated with
the elastomeric material and with the device.
Inventors: |
Speer; Billy L. (Springfield,
MO) |
Assignee: |
Dayco Corporation (Dayton,
OH)
|
Family
ID: |
26836524 |
Appl.
No.: |
06/138,766 |
Filed: |
April 9, 1980 |
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
Reissue of: |
591206 |
Jun 27, 1975 |
03975965 |
Aug 24, 1976 |
|
|
Current U.S.
Class: |
474/135; 403/226;
474/94; 74/411 |
Current CPC
Class: |
F16H
7/1281 (20130101); Y10T 403/456 (20150115); Y10T
74/19633 (20150115); F16H 2007/0819 (20130101) |
Current International
Class: |
F16H
7/12 (20060101); F16H 7/08 (20060101); F16H
007/12 () |
Field of
Search: |
;474/101,117,135,138,94,902,903 ;403/225,226,359 ;64/27NM
;74/411 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
904843 |
|
Feb 1954 |
|
DE |
|
585102 |
|
Jan 1947 |
|
GB |
|
262556 |
|
Mar 1968 |
|
SU |
|
Primary Examiner: Husar; C. J.
Assistant Examiner: Berman; Conrad
Attorney, Agent or Firm: Bricker; Charles E.
Claims
What is claimed is:
1. .[.A.]. .Iadd.In a .Iaddend.tensioning apparatus for an endless
power transmission belt comprising, an elastomeric material, means
supporting said elastomeric material adjacent an associated power
transmission belt, and means operatively connected between said
elastomeric material and said power transmission belt by engaging
said elastomeric material and said power transmission belt and
employing the elastic properties of said elastomeric material to
exert a controlled tensioning force against said endless power
transmission belt.Iadd., the improvement in which said means
operatively connected between said elastomeric material and said
belt comprises, shaft means disposed within and fixed against said
elastomeric material, said shaft means comprising a shaft having at
least one fin-like protrusion fixed thereto and extending radially
therefrom, a lever having one end portion fixed to said shaft, and
an idler roller engaging said power transmission belt and being
carried on said lever, said elastomeric material being displaced
from a normal relaxed condition thereof by said roller acting
through said lever and shaft means so that the elastomeric material
utilizes its elastic properties to transmit a force through said
shaft means, lever, and roller to exert said controlled tensioning
force against said belt.Iaddend..
2. An apparatus as set forth in claim 1 in which said elastomeric
material is a rubber compound.
3. An apparatus as set forth in claim 1 in which said elastomeric
material is a synthetic plastic material.
4. An apparatus as set forth in claim 3 in which said synthetic
plastic material is a urethane elastomer.
5. An apparatus as set forth in claim 1 in which said means
supporting said elastomeric material comprises a housing containing
said elastomeric material and means for supporting said
housing.
6. An apparatus as set forth in claim .[.1 in which said means
operatively connected between said elastomeric material and said
belt comprises shaft means engaging said elastomeric material by
being fixed thereagainst; a lever having one end portion detachably
fixed to said shaft means, and belt-engaging means engaging said
power transmission belt and being carried on said lever, said
elastomeric material being displaced from a normal relaxed
condition thereof by said belt-engaging means acting through said
lever and shaft means so that the elastomeric material utilizes its
elastic properties to transmit a force through said shaft means,
lever and belt-engaging means to exert a controlled tensioning
force against said belt.]. .Iadd.5 in which said housing has an
inside surface and said elastomeric material is disposed with its
exposed surface against said inside surface, and further comprising
means fixing said elastomeric material within said
housing.Iaddend..
7. An apparatus as set forth in claim .[.6.]. .Iadd.1 .Iaddend.in
which said shaft means .Iadd.further .Iaddend.comprises .[.a shaft
having.]. at least .[.one.]. .Iadd.another .Iaddend.fin-like
protrusion .[.extending therefrom, said shaft and its fin-like
protrusion being fixed against said elastomeric material by being
embedded therein.]. .Iadd.fixed to said shaft and extending
radially therefrom in angularly spaced relation from said one
protrusion, said shaft and its protrusions being embedded within
and bonded against said elastomeric material which serves as a
matrix therefor.Iaddend..
8. An apparatus as set forth in claim .[.6.]. .Iadd.1 .Iaddend.in
which said .[.belt-engaging means comprises a belt-engaging.].
roller .Iadd.is .Iaddend.rotably mounted at the outer end portion
of said lever.Iadd., said elastomeric material is a self supported
mass, and said means supporting said elastomeric material comprises
a flange defined as an integral part of said mass and having at
least one opening therein, said opening being adapted to receive a
fastener therethrough to support said flange and mass of
elastomeric material adjacent said belt.Iaddend..
9. An apparatus as set forth in claim 5 in which said means
supporting said elastomeric material further comprises a flange
fixed to said housing and having a plurality of openings therein,
said openings being adapted to receive fasteners therethrough for
fastening said flange and housing into position.
10. An apparatus as set forth in claim .[.6.]. .Iadd.5 .Iaddend.in
which said elastomeric material is displaced from a normal
condition thereof .[.and placed in a condition of shear.]. .Iadd.to
provide a shear loading therein .Iaddend.by said .].belt-engaging
means.]. .Iadd.roller .Iaddend.acting through said lever and shaft
means.Iadd., and said apparatus further comprises integral means
for changing said loading an infinite number of loading values and
indicating the amount of said tensioning force applied by said
elastomeric material against said belt.Iaddend..
11. .[.An.]. .Iadd.In an .Iaddend.endless power transmission belt
drive system comprising; at least one driving sheave; at least one
driven sheave; an endless power transmission belt operatively
connected between said sheaves; and a tensioning apparatus for said
belt comprising, an elastomeric material, means supporting said
elastomeric material adjacent said belt, and means operatively
connected between said elastomeric material and said belt by
engaging said elastomeric material and said belt and employing the
elastic properties of said elastomeric material to exert a
controlled tensioning force against said belt, .Iadd.the
improvement in which said means operatively connected between said
elastomeric material and said belt comprises, shaft means disposed
within and fixed against said elastomeric material, said shaft
means comprising a shaft having at least one fin-like protrusion
fixed thereto and extending radially therefrom, a lever having one
end portion fixed to said shaft, and an idler roller engaging said
power transmission belt and being carried on said lever, said
elastomeric material being displaced from a normal relaxed
condition thereof by said roller acting through said lever and
shaft means so that the elastomeric material utilizes its elastic
properties to transmit a force through said shaft means, lever, and
roller to exert said controlled tensioning force against said
belt.Iaddend..
12. A system as set forth in claim 11 in which said elastomeric
material is a rubber compound.
13. A system as set forth in claim 11 in which said elastomeric
material is a synthetic plastic material.
14. A system as set forth in claim 13 in which said synthetic
plastic material is a urethane elastomer.
15. A system as set forth in claim 11 in which said means
supporting said elastomeric material comprises a housing containing
a mass of said elastomeric material and means for supporting said
housing.
16. A system as set forth in claim .[.11 in which said means
operatively connected between said elastomeric material and said
belt comprises shaft means engaging said elastomeric material by
being fixed thereagainst, a lever having one end portion detachably
fixed to said shaft means, and belt-engaging means engaging said
power transmission belt and being carried on said lever, said
elastomeric material being displaced from a normal relaxed
condition thereof by said belt-engaging means acting through said
lever and shaft means so that the elastomeric material utilizes its
elastic properties to transmit a force through said shaft means,
lever, and belt-engaging means to exert a controlled tensioning
force against said belt.]. .Iadd.15 in which said housing has an
inside surface and said elastomeric material is disposed with its
exposed surface against said inside surface, and further comprising
means fixing said elastomeric material within said
housing.Iaddend..
17. A system as set forth in claim .[.16.]. .Iadd.11 .Iaddend.in
which said shaft means .Iadd.further .Iaddend.comprises .[.a shaft
having.]. at least .[.one.]. .Iadd.another .Iaddend.fin-like
protrusion .[.extending therefrom, said shaft and its fin-like
protrusion being fixed against said elastomeric material by being
embedded therein.]. .Iadd.fixed to said shaft and extending
radially therefrom in angularly spaced relation from said one
protrusion, said shaft and its protrusions being embedded within
and bonded against said elastomeric material which serves as a
matrix therefor.Iaddend..
18. A system as set forth in claim .[.16.]. .Iadd.11 .Iaddend.in
which said .[.belt-engaging means comprises a belt-engaging.].
roller .Iadd.is .Iaddend.rotatably mounted at the outer end portion
of said lever.Iadd., said elastomeric material is a self supported
mass, and said means supporting said elastomeric material comprises
a flange defined as an integral part of said mass and having at
least one opening therein, said opening being adapted to receive a
fastener therethrough to support said flange and mass of
elastomeric material adjacent said belt.Iaddend..
19. A system as set forth in claim 15 in which said means
supporting said elastomeric material further comprises a flange
fixed to said housing and having a plurality of openings therein,
said openings being adapted to receive fasteners therethrough for
fastening said flange and housing into position.
20. A system as set forth in claim .[.16.]. .Iadd.11 .Iaddend.in
which said elastomeric material is displaced from a normal
condition thereof .[.and placed in a condition of shear.]. .Iadd.to
provide a shear loading therein .Iaddend.by said .[.belt-engaging
means.]. .Iadd.roller .Iaddend.acting through said lever and shaft
means, said elastomeric material also serves .[.serving.]. as
vibration-dampening means.Iadd., and said apparatus further
comprises integral means for changing said loading an infinite
number of loading values and indicating the amount of said
tensioning force applied by said elastomeric material against said
belt.Iaddend..
21. .[.A.]. In a tensioning apparatus for an endless power
transmission device comprising, an elastomeric material, means
supporting said elastomeric material adjacent an associated power
transmission device, and means operatively connected between said
elastomeric material and said power transmission device by engaging
said elastomeric material and said power transmission device and
employing the elastic properties of said elastomeric material to
exert a controlled tensioning force against said endless power
transmission device.Iadd., the improvement in which said means
operatively connected between said elastomeric material and said
device comprises, shaft means disposed within and fixed against
said elastomeric material, said shaft means comprising a shaft
having at least one fin-like protrusion fixed thereto and extending
radially therefrom, a lever having one end portion fixed to said
shaft, and an idler roller engaging said power transmission device
and being carried on said lever, said elastomeric material being
displaced from a normal relaxed condition thereof by said roller
acting through said lever and shaft means so that the elastomeric
material utilizes its elastic properties to transmit a force
through said shaft means, lever, and roller to exert said
controlled tensioning force against said device.Iaddend..
22. In .Iadd.a .Iaddend.combination.[.:.]. .Iadd.comprising
.Iaddend.an endless power transmission device and a tensioning
apparatus for said endless power transmission device, said
apparatus comprising, an elastomeric material, means supporting
said elastomeric material adjacent said device, and means
operatively connected between said elastomeric material and device
by engaging said elastomeric material and said device and employing
the elastic properties of said elastomeric material to exert a
controlled tensioning force against said device.Iadd., the
improvement in which said means operatively connected between said
elastomeric material and said device comprises, shaft means
disposed within and fixed against said elastomeric material, said
shaft means comprising a shaft having at least one fin-like
protrusion fixed thereto and extending radially therefrom, a lever
having one end portion fixed to said shaft, and an idler roller
engaging said power transmission device and being carried on said
lever, said elastomeric material being displaced from a normal
relaxed condition thereof by said roller acting through said lever
and shaft means so that the elastomeric material utilizes its
elastic properties and to transmit a force through said shaft
means, lever, and roller to exert said controlled tensioning force
against said device.Iaddend..
23. A combination as set forth in claim 22 in which said device
comprises a sprocket chain.
24. A combination as set forth in claim 22 in which said device
comprises a timing belt.
25. A combination as set forth in claim 22 in which .[.said means
operatively connected between said elastomeric material and said
device comprises a shaft engaging said elastomeric material by
being embedded therein,.]. said elastomeric material .[.being.].
.Iadd.is .Iaddend.in the form of a self supported .[.cylindrical.].
mass .[.serving as a matrix for said shaft,.]. .Iadd.and
.Iaddend.said means supporting said elastomeric material comprises
a flange defined as an integral part of said .[.cylindrical.]. mass
and having at least one opening therein, said opening being adapted
to receive a fastener therethrough to support said flange and
elastomeric material adjacent said device.[., a lever having one
end portion detachably fixed to said shaft, and device-engaging
means engaging said device and being carried on said lever, said
elastomeric material being displaced from a normal relaxed
condition thereof by said device-engaging means acting through said
lever and shaft so that the elastomeric material utilizes its
elastic properties to transmit a force through said shaft, lever,
and device-engaging means to exert a controlled tensioning force
against said device.]..
26. A combination as set forth in claim .[.25.]. .Iadd.22
.Iaddend.in which said shaft has external splines thereon, and said
one end portion of said lever has an internally splined opening
therein which receives said external splines of said shaft
therethrough.
27. A combination as set forth in claim .[.25.]. .Iadd.22
.Iaddend.in which said shaft has an internally splined opening
therein which is adapted to receive a cooperating splined
.[.member.]. .Iadd.portion .Iaddend.comprising said one end portion
of said lever.
28. A combination as set forth in claim 22 in which said
elastomeric material is a rubber compound.
29. A combination as set forth in claim 22 in which said
elastomeric material is a synthetic plastic material.
30. A combination as set forth in claim 29 in which said synthetic
plastic material is a urethane elastomer. .Iadd. 31. An apparatus
as set forth in claim 1 in which said elastomeric material is
defined as a mass having opposed ends, said fin-like protrusion has
opposed end edges, and said protrusion is embedded within and
bonded against said elastomeric material which serves as a matrix
therefor with the end edges of said protrusion being disposed
axially inwardly of the opposed ends of said elastomeric material,
said protrusion assuring that said shaft means and mass of
elastomeric material are prevented from relative movement
therebetween including both relative rotary as well as relative
axial movement. .Iaddend..Iadd. 32. An apparatus as set forth in
claim 1 in which said elastomeric material is defined as a
substantially tubular mass which has a particular wall thickness
and is disposed outwardly of said shaft, and said fin-like
protrusion has a radial dimension which extends through the major
part of said wall thickness. .Iaddend. .Iadd. 33. In a tensioning
apparatus for an endless power transmission device comprising, an
elastomeric material, means supporting said elastomeric material
adjacent an associated power transmission device, and means
operatively connected between said elastomeric material and said
power transmission device by engaging said elastomeric material and
said power transmission device and employing the elastic properties
of said elastomeric material to exert a controlled tensioning force
against said endless power transmission device, the improvement in
which said elastomeric material is a self supported mass and said
means supporting said elastomeric material comprises integral
flange means adapted to be used in fastening said mass of
elastomeric material adjacent said device. .Iaddend.
Description
BACKGROUND OF THE INVENTION .Iadd.
1. Field of the Invention
This invention relates to a tensioning apparatus of the idler
roller type for endless power transmission devices, such as,
endless belts, sprocket chains, timing belts, and the like.
2. Prior Art Statement .Iaddend.
In numerous applications where endless power transmission devices
are employed it is often desirable or necessary to control the
tension in such devices during movement thereof around associated
sheaves, pulleys, sprockets or the like, to assure optimum
operating efficiency.
For example, in the automobile industry where a single endless
power transmission belt is used to drive various automobile
accessories, a belt tensioning device is required to assure
satisfactory performance of the accessories as well as assure
satisfactory service life of the belt.
Numerous tensioning devices such as belt tensioning devices have
been proposed heretofore and most of these devices employ metal
spring devices, hydraulic devices, or pneumatic devices to provide
the tensioning action whereby such devices are comparatively
complicated and expensive and require considerable maintenance.
.Iadd.
It has also been proposed heretofore to employ rubber under loaded
or stressed conditions as a resilient spring means in various
applications, including tensioning apparatus for endless power
transmission devices. However, rubber thus used heretofore has
either resulted in comparatively complicated and expensive
tensioning apparatus or in such apparatus which requires a skilled
mechanic to install same on associated equipment to assure
satisfactory performance of such equipment and the tensioning
apparatus. .Iaddend.Accordingly, there is a need for a simple and
inexpensive tensioning apparatus .Iadd.for an endless power
transmission device .Iaddend.capable of providing reliable
performance over an extended service life .Iadd.and capable of
being installed on associated equipment by a comparatively
unskilled person. .Iaddend.
SUMMARY
Accordingly, one embodiment of this invention provides a tensioning
apparatus for an endless power transmission belt and a belt system
using same wherein such tensioning apparatus comprises an
elastomeric material, means supporting the elastomeric material
adjacent an associated power transmission belt, and means
operatively associating with the elastomeric material and the power
transmission belt and employing the elastic properties of the
elastomeric material to exert a controlled tensioning force against
the belt.
It is a feature of this invention to provide a simple, economical,
and reliable belt tensioning apparatus capable of operating
maintenance free over an extended service life and which is
particularly adapted to be used in lieu of complicated tensioning
apparatus proposed heretofore.
Another feature of this invention is to provide a tensioning
apparatus capable of being used with endless belts of all types,
sprocket chains, timing belts, and similar endless devices.
Accordingly, it is an object of this invention to provide an
improved belt tensioning apparatus and belt system using same and
an improved combination of endless device and tensioning apparatus
having one or more of the novel features set forth above or
hereinafter shown or described.
Other details, features, objects, uses, and advantages of this
invention will become apparent from the embodiments thereof
presented in the following specification, claims, and drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings show present preferred embodiments of
this invention in which,
FIG. 1 is a perspective view illustrating one exemplary embodiment
of an endless power transmission belt drive system used on an
internal combustion engine such as an automobile engine with such
belt drive system using one exemplary embodiment of the belt
tensioning apparatus of this invention to provide a controlled
tension in its associated belt;
FIG. 2 is a perspective view with parts in cross-section and parts
broken away particularly illustrating the exemplary belt tensioning
apparatus of FIG. 1;
FIG. 3 is a fragmentary view taken essentially on the line 3--3 of
FIG. 2;
FIG. 4 is a cross-sectional view taken essentially on the line 4--4
of FIG. 2;
FIG. 5 is a perspective view illustrating the manner in which the
belt tensioning apparatus of this invention may be installed or set
to provide a controlled tension;
FIG. 6 is a view similar to FIG. 4 illustrating a modification of
the apparatus of this invention;
FIG. 7 is a fragmentary perspective view illustrating the belt
tensioning apparatus of this invention being utilized with an
endless power transmission device in the form of an endless timing
belt;
FIG. 8 is a view similar to FIG. 7 illustrating the apparatus of
this invention being utilized with an endless power transmission
device in the form of an endless sprocket chain;
FIG. 9 is a perspective view similar to FIG. 2 illustrating another
modification of the belt tensioning apparatus of this invention;
and
FIG. 10 is a fragmentary perspective view illustrating still
another modification of the belt tensioning apparatus of this
invention.
DESCRIPTION OF ILLUSTRATED EMBODIMENTS
Reference is now made to FIG. 1 of the drawings which illustrates a
prime mover or an internal combustion engine in the form of an
automobile engine 20 which utilizes an endless power transmission
belt drive system 21 and such drive system 21 comprises a single
endless power transmission belt 22 and a plurality of five belt
pulleys or sheaves including a driving sheave 23 and a plurality of
driven sheaves which are designated by the reference numerals 24,
25, 26, and 27. The sheaves 24-27 are suitably operatively
connected to associated assemblies or accessories to drive such
accessories and in this example the sheaves of the system 21 are
constructed and arranged such that the belt 22 operates
substantially in a common plane. The engine 20 and hence drive
system 21 utilizes one exemplary embodiment of a belt tensioning
apparatus of this invention which is designated generally by the
reference numeral 30.
Referring now to FIG. 2, it will be seen that the apparatus 30
utilizes an elastomeric material 31 and means designated generally
by the reference numeral 32 for supporting the elastomeric material
adjacent the endless belt 22. Further, the apparatus 30 has means
designated generally by the reference numeral 33 operatively
associating with the elastomeric material 31 and the belt 22 while
employing or utilizing the elastic properties of the elastomeric
material 31 to exert a controlled tensioning force against the belt
22.
The means 32 for supporting the elastomeric material 31 comprises a
housing 34 which contains the elastomeric material 31, and the
manner in which such elastomeric material 31 is introduced and
fixed within the housing 34 will be described in detail
subsequently. The housing 34 is suitably fixed as by welding, for
example, to a supporting flange 35 which in this example defines a
supporting base 35 for the apparatus 30 enabling such apparatus to
be easily detachably mounted on the engine 31.
The means 33 operatively associating with the elastomeric material
and the belt 22 comprises shaft means 36 which is suitably fixed in
an embedded manner in the elastomeric material 31, a lever 37
having opposite end portions 40 and 41, and a rotatable
belt-engaging roller 42. The end portion 40 of lever 37 is
detachably fixed to the shaft means 36 and the roller 42 is
rotatably mounted on opposite end portion 41 whereby the roller 42
is particularly adapted to engage the outside surface of the belt
22 to exert a tensioning force thereagainst. In particular, the
apparatus 30 is suitably installed on the engine 20 such that the
elastomeric material 31 is displaced from a normal relaxed
condition thereof by the roller 42 engaging the belt 22. The
displaced elastomeric material 31 has elastic properties or an
elastic memory and thus it tends to return or move to its normal
relaxed or unstressed condition whereby it imparts a force to lever
37 (through shaft means 36) and to the roller 42 causing such
roller to engage and deflect the belt 22 inwardly as illustrated at
43 in FIG. 1 and thereby provide a controlled tensioning of such
belt.
The housing 34 of the apparatus 30 has a substantially right
circular cylindrical main body 44 which is provided with an
integral end 45 which in this example, is substantially planar, and
the end 45 has an inwardly projecting tubular flange 46 extending
within the housing 44 a controlled dimension indicated at 47. The
main body 44 has an opposite end portion provided with threads 50
in the form of external threads which are particularly adapted to
threadedly receive internal threads of a cap 51 in the manner shown
in FIG. 2.
The cap 51 has a flat or substantially planar outside surface 49
and central opening therethrough defined by an inwardly projecting
tubular flange 52 which corresponds to the tubular flange 46
extending inwardly into the housing 34 from the opposite wall 45.
The purpose of the tubular flanges 46 and 52 will be described
subsequently.
The shaft means 36 of this exemplary apparatus 30 comprises a shaft
53 having at least one fin-like projection and in this example a
plurality of four fin-like projections or fins 54 which extend from
the outer periphery of such shaft 53. The fins 54 are angularly
spaced 90.degree. apart and have their inner portions received
within associated slots 55 in the shaft 53 and are suitably fixed
in position as by welding, or the like. The shaft 53 of the shaft
means 36 has reduced diameter opposite end portions 56 and 57 with
the reduced diameter portion 56 being received within the tubular
flange 46 and the reduced diameter portion 57 being received within
the tubular flange 52. The reduced diameter portions 56 and 57
defined parallel annular ledges each designated by the same
reference numeral 60 which are particularly adapted to be engaged
by the terminal inner edges of the flanges 46 and 52 to prevent
axial movement of the shaft means 36 once the cap 51 is threadedly
fastened in position.
The flange 35 has a plurality of openings therethrough with each
opening being designated by the same reference numeral 63 and each
opening is particularly adapted to receive a threaded bolt 64
therethrough, see FIG. 1, and enable fastening of the flange 35 and
hence the entire apparatus 30 on the engine 20 as illustrated at
65.
The lever 37 has its end portion 40 detachably fastened to the
shaft 53 of the shaft means 36 by means of a splined end portion 66
on the shaft 53 and internally splined arms 67 defining end portion
40. The arms 67 define a bifurcate end having an enlarged opening
provided with parallel tooth-like projections 70, see FIG. 5. The
projections 70 are particularly adapted to be received within
grooves in the splined end portion 66. The arms 67 have a threaded
allen screw 71 extending through a plain or smooth opening in the
arm 67 adjoining the screw head and a cooperating threaded opening
in the remote arm. To fasten the end portion 40 of the lever 37 to
the splined end 66 the screw 71 is unthreaded allowing the arms 67
to spring apart whereupon the end portion 40 and lever 37 may be
moved axially away from the splined end portion 66. Once it is
desired to fasten the lever 37 to the splined end portion 66, the
end portion 40 is moved so that the enlarged opening therein
receives the splined end portion 66 therethrough whereupon the
screw 71 is tightened to fasten the lever 37 and shaft means 36
together.
The lever 37 has roller 42 suitably rotatably supported at its
opposite end portion 41 by a shaft-like bolt 72 which has an
enlarged head portion 73 and a threaded portion at the opposite end
thereof which is threadedly received within a threaded opening
provided in the end portion 41. Thus, the roller 42 is prevented
from inward axial movement by the lever 37 and is prevented from
outward axial movement by the head 73. The roller 42 may be
provided with a pair of oppositely arranged side flanges 74 for
receiving a belt therewithin.
The apparatus 30 may also be provided with means 75 for indicating
the amount of tension being exerted by the elastomeric material 31
and in this example such means is in the form of an arrow 76 which
may be provided on the shaft means 36 and in particular on the
terminal end of the shaft 53. The tension indicating means includes
a scale device 77 which may be suitably fixed in position at the
end of the housing 34 associated with the arrow 76. The manner in
which the tension indicating means is employed will now be
described.
The housing 34 of apparatus 30 is suitably detachably fixed on the
engine 20 using the flange 35 and as illustrated at 65 and with its
lever 37 disconnected. In this position the elastomeric material 31
is in its normal relaxed position. A simple L-shaped tool 80, shown
in FIG. 5, and having an allen-type end 86 may be employed and
inserted within a cooperating opening 81 provided in the splined
end portion 66 of the shaft 53 and with the screw 71 unthreaded the
arms 67 and lever 37 are moved outwardly along the tool 80 as shown
at 82. The tool 80 is then rotated in the direction of the arrow 83
thereby moving the arrow 76 to the dotted line position opposite
the scale mark 84 in FIG. 3 to provide a loading or displacement of
the material 31 in housing 34 from its normal relaxed condition
whereupon the lever 37 is moved so that the arms 67 are positioned
around the splined end 66. The threaded screw is then tightened
thereby attaching the lever 37 and its roller 42 in position. The
tool 80 may then be gradually released allowing the elastic
character of the elastomeric material 31 to move the roller 42 into
engagement with the belt as illustrated at 43 in FIG. 1. If the
belt 22 has the correct tension applied thereagainst the arrow 76
will be within the zone 85 on the scale device. In the event the
arrow 76 is not within the zone 85 the tool 80 is again used to
remove the lever 37 and roller 42 and the operation is repeated by
loading or stressing the elastomeric material more or less, as
required, so that once the tool is finally removed the arrow 76
will be within zone 85 indicating the correct precise belt tension
is being applied.
The elastomeric material 31 is selected so that when loaded in the
manner described above, it will provide the correct tension. For
example, it has been found that a urethane elastomer manufactured
by E. I. DuPont de Nemours Company of Wilmington, Del., and sold
under the trade designation of Adiprene 100 may be used with
excellent results when cured to a Shore Durometer hardness of 90 as
measured on the A-scale.
It will be appreciated that the elastomeric material 31 may be
specially formulated with great precision for each belt tensioning
application to provide any desired tension in a controlled
acceptable range.
The belt tensioning apparatus 30 is shown in FIGS. 2 and 4 as using
elastomeric material in the form of a plastic material. However, it
will be appreciated, as illustrated at 88 in FIG. 6, that the
elastomeric material 31 may be a suitable rubber compound including
natural rubber and synthetic rubber.
In this disclosure of the invention, the housing 34 is shown
provided with a threaded cap 51; however, it will be appreciated
that the housing need not necessarily be provided with a threaded
cap but may be provided with any suitable means to close the
opposite end of the housing 34. It will also be appreciated that
the apparatus of this invention lends itself to easy assembly in
that an empty housing 31 may be supported on its end portion 45
followed by installation of the shaft means 36 whereupon a suitable
elastomeric material whether in the form of a plastic material or a
rubber compound may be poured in position. The threaded cap may
then be fastened in position and the entire assembly suitably
allowed to set or cure to embed the shaft means 36 in the
elastomeric material 31.
In this example of the invention, the elastic properties of the
elastomeric material are employed by loading such material so as to
place the material in shear. However, it will be appreciated that
such material need not necessarily be placed in shear but may be
placed in tension or compression by providing and employing
suitable components of an apparatus 30, or the like, which
cooperate in such a manner that the properties of the elastomeric
material may be employed to provide the precisely controlled
tensioning action.
In this disclosure of the invention, the shaft means 36 is shown as
utilizing a plurality of four spaced fin-like projections or fins
54 which are suitably mechanically fixed in position and the
purpose of the fins 54 is to provide an increased amount of area on
the shaft means for engagement by the elastomeric material.
However, it will be appreciated that such shaft means need not
necessarily be provided and that a plain shaft 53 may be suitably
fixed or bonded in position by chemical action, mechanical action,
or both, or any other suitable technique.
It will also be appreciated that the elastomeric material 31 is
suitably fixed in position within the housing 34. In this example
of the invention, the elastomeric material 31 is suitably
chemically or adhesively bonded against the housing as illustrated
at 90 in FIG. 4 by suitable adhesive means 91 applied to the inside
of the housing means 34; however, it will be appreciated that the
elastomeric material may be fixed or bonded to the housing using
any suitable means such as threaded screws, for example, which
project through the housing wall and into the elastomeric material
as illustrated by dotted lines at 92, for example.
The above description has been made utilizing the belt tensioning
apparatus 30 for the purpose of tensioning an endless power
transmission device in the form of a belt which is shown being used
on an internal combustion engine, such as an automobile engine, for
example; however, it will be appreciated that the basic tensioning
apparatus of this invention may also be employed in tensioning an
endless power transmission device in the form of a timing belt.
Thus, FIG. 7 illustrates a suitably toothed wheel or sheave 95
which has a timing belt 96 operatively associated therewith and the
belt 96 is particularly adapted to be operatively associated with
other parts of an endless system (not shown) and in a manner well
known in the art. The timing belt 96 is tensioned by the apparatus
30 of this invention and such apparatus has its belt engaging
roller 42 arranged such that it engages the timing belt 96 and
provides a controlled tension.
Reference is now made to FIG. 8 of the drawings which illustrates a
typical belt tensioning apparatus 30 of this invention being used
to provide a controlled tensioning of an endless power transmission
device in the form of a sprocket chain 101. The sprocket chain 101
is operatively associated with a sprocket wheel 100 which together
with the chain 101 comprise two components of an endless power
transmission system and the remaining components of such an endless
system are not shown. The apparatus 30 of FIG. 8 utilizes a
sprocket chain engaging roller which is also designated by the
reference numeral 42; and, the apparatus 30 provides tensioning of
the sprocket chain 101 in a similar manner as previously described
in connection with the belt 22 of FIG. 1.
It will also be appreciated that the elastomeric material utilized
to provide the tensioning action in the apparatus 30 need not
necessarily be confined or disposed within an outer housing. For
example, FIG. 9 illustrates elastomeric material which is preshaped
or formed in the form of a self supported cylindrical mass and
designated by the reference numeral 102. The cylindrical mass 102
with its elastomeric material 31 serves as a matrix for the shaft
53 of the apparatus 30, and it will be seen that the means
supporting the elastomeric material or cylindrical mass 102 is a
flange 103 defined as an integral part of the cylindrical mass 102
and extending therebeneath. The mass 103 has at least one opening
therein and in this example a plurality of two openings 103A and
each opening 103A is adapted to receive an associated fastener
therethrough to support the flange and elastomeric material
adjacent an associated endless device such as the belt 22, timing
belt 96, sprocket chain 101, or a similar endless device.
The elastomeric material which is made in the form of a cylindrical
mass 102 is cross-hatched in FIG. 9 to indicate that it is a rubber
material; however, it will be appreciated that the cylindrical mass
102 may be made of a suitable synthetic plastic material, if
desired.
The shaft 53 is illustrated in each of FIGS. 2 and 9, for example,
as having external splines thereon adapted to receive an associated
end portion of a lever which has an internally splined opening
therein which receives the external splines of the shaft
therethrough. However, it will be appreciated that instead of
providing external splines on the shaft 53 of apparatus 30, the
shaft 53 may have an internally splined opening 104 therein as
shown in the modification of the apparatus 30 shown in FIG. 10. The
opening 104 is particularly adapted to receive a cooperating
splined portion or member comprising an end portion of a lever
adapted to be detachably fastened to the shaft. In this latter type
of connection, any suitable means known in the art may be provided
to prevent axial movement between the splined member and internally
splined opening in the shaft 53.
In this disclosure, the above description of the elastomeric
material 31 of the apparatus 30 has been directed to use of the
elastic properties thereof to provide a tensioning action; however,
the elastomeric material 31 also serves, with great effectiveness,
as a vibration dampener thereby reducing the amount of vibration
transmitted to the associated endless device whether it be the belt
22, timing belt 96, sprocket chain 101, or similar endless
device.
While present exemplary embodiments of this invention, and methods
of practicing the same, have been illustrated and described, it
will be recognized that this invention may be otherwise variously
embodied and practiced within the scope of the following
claims.
* * * * *