Note: Descriptions are shown in the official language in which they were submitted.
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ORBITAL ACCESSORY DRIVE TENSIONER WITH BIASING MEMBER
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application No.
62/072,872, filed on October 30, 2014, the contents of which are incorporated
herein by
reference in its entirety.
FIELD
[0002] This disclosure relates to tensioners for endless drive members
and, in
particular, to a tensioner that operates to tension an endless drive member
driven by a
vehicular engine.
BACKGROUND OF THE DISCLOSURE
[0003] It is common for vehicle engines to drive a plurality of
accessories using an
accessory drive system that includes a belt. In general, a tensioner is used
to maintain
tension on the belt, to inhibit belt slip during transient events and to
inhibit the belt from
coming off the associated pulleys of the driving and driven components.
[0004] In some vehicles, the engine is the sole means of driving the
belt and the
associated components. Typically, one of the driven components in such a case
is an
alternator, which is driven by the belt to generate electricity that is used
to charge the
vehicle's battery.
[0005] In other vehicles, a secondary motive device is provided for
driving the belt.
The secondary motive device (e.g. a motor/generator unit (MGU)) can be used
for a
number of purposes, such as, for example, driving one or more accessories via
the belt
when the engine is temporarily off while the vehicle is stopped for a short
period of time
(e.g. at a stoplight). Another purpose is for use as part of a belt alternator
start (BAS)
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drive system wherein the MGU is used to start the engine through the belt.
Another
purpose is to supply additional power to the engine when needed (e.g. when the
vehicle
is under hard acceleration).
SUMMARY OF THE DISCLOSURE
[0006] In one embodiment, there is provided a tensioner for maintaining
tension in
an endless drive member. The tensioner includes, but is not necessarily
limited to, a
base, a tensioner arm and a tensioner arm biasing member. The base is
mountable to
a frame of an MGU, or an alternator, or a similar device. The tensioner arm
has a
tensioner pulley thereon, wherein the tensioner arm is mounted for translation
along an
arc relative to the base. The tensioner arm biasing member is elastically
compliant in
compression or extension and has a first end that is engaged with the
tensioner arm
and a second end that is engaged with the base. The tensioner pulley is
positioned to
engage the endless drive member on one side of the MGU, alternator or similar
device.
BRIEF DESCRIPTIONS OF THE DRAWINGS
[0007] For a better understanding of the various embodiments described
herein and
to show more clearly how they may be carried into effect, reference will now
be made,
by way of example only, to the accompanying drawings in which:
[0008] FIG. 1 is a side view of an engine having a tensioner, according to
a first set
of non-limiting embodiments;
[0009] FIG. 2 is a perspective view of the tensioner depicted in FIG. 1;
[0010] FIG. 3 is a side elevation view of the tensioner depicted in FIG.
1;
[0011] FIG. 4 is an exploded view of the tensioner depicted in FIG. 1;
[0012] FIG. 5 is a sectional view of the tensioner depicted in FIG. 1;
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[0013] FIG. 6 is a perspective view of a tensioner, according to a
second set of non-
limiting embodiments;
[0014] FIG. 7 is a top plan view of the tensioner depicted in FIG. 6;
[0015] FIG. 8 is a side elevation view the tensioner depicted in FIG. 6;
[0016] FIG. 9 is a perspective view of a tensioner, according to a third
set of non-
limiting embodiments;
[0017] FIG. 10 is a top plan view of the tensioner depicted in FIG. 9;
[0018] FIG. 11 is a side elevation view of the tensioner depicted in
FIG. 10;
[0019] FIG. 12 is a perspective view of a tensioner, according to a
fourth set of non-
limiting embodiments;
[0020] FIG. 13 is a top plan view of the tensioner depicted in FIG. 12;
and
[0021] FIG. 14 is a side elevation view of the tensioner depicted in
FIG. 14.
DETAILED DESCRIPTION
[0022] Described herein are tensioners that can be used with various engine
accessories, such as a MGU, alternator or similar device. In some embodiments,
the
described tensioners are intended for use in with a non-hybrid engine (i.e.,
one that
does not include a Belt-Alternator Start [BAS] or Belt Starter Generator [BSG]
system),
and which may have a regular alternator. The described tensioners are
"orbital"
tensioners in that in operation the tensioner at least partially surrounds an
axis about
which the tensioner arm rotates, wherein that axis may be coaxial with an axis
of
rotation of an input/output shaft of the associated accessory (also referred
to as an
accessory shaft, or an accessory drive shaft).
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[0023] In some embodiments, the described tensioners can also be used
with hybrid
engine designs having BAS capabilities, which have engine start and stop
capability. In
some embodiments, the tensioner may include a second pulley that is configured
to
engage with a span of an endless drive member on an opposing side of the
associated
accessory, such as an alternator.
[0024] The described tensioners include at least a base, a tensioner
arm, a
tensioner arm biasing member and a tensioner pulley. The tensioner also
includes
hardware associated with the tensioner pulley, including fasteners, such as
bolts, a dust
shield for the pulley, one or more sliding disks and a rear plate. The rear
plate is a
biasing element that is configured to maintain engagement between the base and
at
least one of the sliding disks.
[0025] Reference is made to FIG. 1, which shows an example engine 100 of
a
vehicle (not shown). It will be noted that the engine 100 is shown as a simple
shape for
illustrative purposes. It will be understood that the engine 100 may have any
suitable
shape and may be any suitable type of engine such as a spark-ignition engine
or a
diesel engine. The vehicle may be any suitable vehicle, such as an automobile,
a truck,
a van, a minivan, a bus, an SUV, a military vehicle, a boat or any other
suitable vehicle.
[0026] The engine 100 includes a crankshaft 105. The crankshaft 105 has
a
crankshaft pulley 110 thereon. The crankshaft pulley 110 drives one or more
vehicle
accessories via a belt 115. The term 'belt' is used herein for convenience,
however for
the purpose of the claims and for the scope of this disclosure it will be
understood that
the belt 115 may alternatively be any other type of suitable endless drive
member. It
will further be noted that, in cases where the endless drive member is a belt,
it may be
any suitable type of belt, such as a flat belt, a V belt, a poly-V belt, a
timing belt, or any
other suitable type of belt. The term 'pulley' is similarly used for
convenience and any
other suitable rotary drive member may be used instead, such as a sprocket.
[0027] The accessories may include, for example, an alternator 120, an
air
conditioning compressor 125, a water pump 130 and/or any other suitable
accessories.
In some embodiments, the engine 100 further includes a plurality of idlers
(not shown)
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that are positioned to provide a selected amount of belt wrap about the
pulleys of some
of the accessories.
[0028] In some embodiments, the alternator 120 is replaced with a MGU or
a similar
device. In some such embodiments, the engine 100 may be stopped temporarily in
some situations (such as when the vehicle is stopped at a stoplight) and may
then be
started again via the belt 115 when it is time for the vehicle to move. To
achieve this,
the MGU (or some other suitable secondary motive device engaged with the belt
115) is
operated as an electric motor to drive the crankshaft 105 via the belt 115,
enabling the
engine 100 to be started via the belt 115 (i.e., a belt-alternator start (BAS)
drive
system).
[0029] Each of the driven accessories has a shaft, and a pulley that may
be
connectable and disconnectable from the respective shaft via a clutch. For
example,
the alternator shaft and pulley are shown at 135 and 140 respectively. In
another
example, the air conditioning compressor shaft and pulley are shown at 145 and
150
respectively. Each of the accessories may optionally be clutched to permit
each to be
disconnected when not needed, while the belt 115 is still being driven.
[0030] Providing tension in the belt 115 is beneficial in that it
reduces the amount of
slip that can occur between the belt 115 and the driven accessory pulleys, and
between
the belt 115 and the crankshaft 105. In FIG. 1, the direction of rotation of
the crankshaft
105 is shown at DIR1. Regardless of whether the engine 100 is a hybrid or non-
hybrid
configuration, when the engine 100 is driving the belt 115 it will be
understood that a
relatively higher tension will exist on a first, or 'normally tight-side' belt
span, shown at
115a, and a relatively lower tension will exist on a second, or 'normally
right-side' belt
span, shown at 115b. In cases where the engine 100 is a hybrid engine and the
alternator is replaced with an MGU or the like, the belt span 115a will become
the lower-
tension side and the belt span 115b will become when the MGU is operating.
However,
such events will occur less frequently than when the engine 100 is driving the
belt 115
and the MGU is not operating as a motor.
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[0031] An example of a tensioner 200 is shown in Figure 1. In accordance
with a
first set of embodiments, FIGS. 2 to 5 show an example tensioner 200 for
maintaining
tension in an endless drive member, such as the belt 115, and more
particularly in the
belt span 115b. The tensioner 200 includes a base 205, a tensioner arm 210
having a
tensioner pulley 215 and a tensioner arm biasing member 220.
[0032] The base 205 is mountable to a frame 225 (FIG. 1) of the
alternator 120. In
some embodiments, the base 205 is mountable to a frame of a MGU or similar
device.
In the example shown, the base 205 includes a plurality of fasteners 230 (FIG.
1) which
are received in a plurality of fastener apertures 232 (FIG. 2) for mounting
the base 205
to the frame 225 (also referred to herein as the housing 225 of the alternator
120).
[0033] The tensioner arm 210 is mounted for translation along an arc 235
(FIG. 2)
relative to the base 205. In some embodiments, the arc 235 is generally
concave in a
direction towards the alternator pulley 140. For example, the tensioner arm
210 can be
rotatably mounted to the base 205 in a surrounding relationship with the
alternator shaft
135 of the alternator 120 and, in use, rotates about a tensioner arm axis A
(FIGS. 1 and
4) along the arc 235. As shown in FIG. 1, the tensioner arm axis A may be
coaxial with
the axis of rotation of the alternator shaft 135, which is shown at B. The
tensioner arm
210 may also be made from aluminum or any other suitable material.
[0034] Referring to FIG. 4, which shows an exploded view of the
tensioner 200, and
FIG. 5, which shows a sectional view of the tensioner 200, the tensioner 200
includes a
first sliding disk 240a and a second sliding disk 240b. In some embodiments,
the first
sliding disk 240a and the second sliding disk 240b can be configured to apply
a desired
amount of friction to the tensioner arm 210 to provide a desired amount of
damping to
the movement of the tensioner arm 210 on the base 205. When used to
intentionally
apply a selected amount of damping to the movement of the tensioner arm 210,
the first
sliding disk 240a and the second sliding disk 240b may be referred to as a
first damping
disk 240a and a second damping disk 240b. In some embodiments, the first
sliding disk
240a and the second sliding disk 240b are bushings. Suitable material of
construction
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of the first sliding disk 240a and the sliding disk 240b may be, for example,
polyamide
4.6 or 6.6 or some other suitable polymeric material.
[0035] In the example tensioner 200, a rear plate 245 is provided and
connected to
the tensioner arm 210 such that the rear plate 245 cooperates with the
tensioner arm
210 to clamp the base 205, the first sliding disk 240a and the second sliding
disk 240b
together while still permitting sliding movement of the tensioner arm 210
relative to the
base 205. With this arrangement, the second sliding disk 240b is positioned
between
the rear plate 245 and a first face 250 (FIG. 5) of the base 205, and the
first sliding disk
240a is positioned between the tensioner arm 210 and the a second face 255
(FIG. 5)
of the base 205. During movement of the tensioner arm 210 when the tensioner
200 is
in use, the sliding occurs by the rear plate 245 on the first sliding disk
240a and/or by
the first sliding disk 240a on the base 205, and sliding also occurs by the
tensioner arm
210 on the second sliding disk 240b and/or by the second sliding disk 240b on
the base
205. As a result of the aforementioned sliding movement, the first sliding
disk 240a and
the second sliding disk 240b apply a frictional force (i.e., a damping force)
to the
tensioner arm 210.
[0036] In the example tensioner 200, the first sliding disk 240a and the
second
sliding disk 240b are complete circles, covering the entire circumference of
the
tensioner arm 210 and the base 205. However, in some embodiments, one or more
of
the first sliding disk 240a and the second sliding disk 204b covers less than
the entire
circumference of the tensioner arm 210 and the base 205 (and in some example
embodiments shown, less than 180 degrees of arc). The second sliding disk 240b
is
positioned in a first region of the tensioner 200 that is outside of a second
region that
lies under the belt 115 (FIG. 1). In the first region there is less of a
height constraint on
the tensioner components, whereas in the second region there can be
significant height
constraint. The part of the circumference of the tensioner arm 210 and base
205 where
the second sliding disk 240b is not routed is in the second region of the
tensioner 200,
so as help keep the height of the tensioner 200 sufficiently low to avoid
interference with
the belt 115.
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[0037] The rear plate 245 includes clip portions 260 (FIGS. 4 and 5)
that clip onto
receiving members on the tensioner arm 210. For example, the flange portion
265
(FIG. 4) of the rear plate 245 may be relatively thin in cross-section so as
to render it
resilient, and may be shaped to apply a spring force on the second sliding
disk 240b.
This arrangement can be configured so that a consistent force is applied to
the second
sliding disk 240b by the rear plate 245 reducing the need for assembly worker
expertise.
[0038] It will be further noted that the first sliding disk 240a and the
second sliding
disk 240b also provide damping that is substantially independent of the hub
load
incurred by the tensioner pulley 215. Additionally, it will be noted that the
use of two
sliding disks, the first sliding disk 240a and the second sliding disk 240b,
both of which
are at relatively large diameters (i.e., large moment arms) from the tensioner
arm axis
A, reduces the average amount of force that each of the first sliding disk
240a and the
second sliding disk 240b must apply to achieve a selected damping load.
[0039] The first sliding disk 240a and the second sliding disk 240b may
have surface
properties that provide symmetric damping in the sense that the damping force
exerted
by the first sliding disk 240a and the second sliding disk 240b may the same
irrespective of the direction of movement of the tensioner arm 210.
Alternatively,
however, the first sliding disk 240a and the second sliding disk 240b may be
provided
with surface properties (e.g., a 'fish-scale' effect) that provides lower
damping in one
direction and higher damping in the opposite direction. Other means for
achieving
asymmetrical damping are alternatively possible, such as the use of a ramp
structure
whereby the tensioner arm 210 rides up the ramp structure urging it into
progressively
stronger engagement with a damping member (so as to increase the damping
force)
during rotation in a first direction and wherein the tensioner arm 210 rides
down the
ramp structure urging it into weaker engagement with the damping member
thereby
reducing the damping force during movement in the second direction.
[0040] In other embodiments, the first sliding disk 240a and the second
sliding disk
240b may be configured to provide relatively little frictional resistance
thereby increasing
the responsiveness of the tensioner 200.
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[0041]
Optionally, the rear plate 245 may be threadably connected to the
tensioner arm 210 (e.g., via engagement of threaded fasteners with threaded
apertures
in the tensioner arm 210) so as to permit adjustment of a gap between the rear
plate
245 and the tensioner arm 210, and adjustment of the clamping force
therebetween.
This permits adjustment of a damping force exerted on the tensioner arm 210
via the
first sliding disk 240a and the second sliding disk 240b. In some embodiments,
the first
sliding disk 240a and the second sliding disk 240b are replaced by a single
sliding
member or bushing that is C-shaped and acts between the rear plate 245, the
tensioner
arm 210 and the base 205.
[0042] It will be noted that the first sliding disk 240a and the second
sliding disk
240b have radially extending portions, shown at 270a and 270b respectively
(FIG. 4),
which are the portions of the first sliding disk 240a and the second sliding
disk 240b that
act on the first face 250 and the second face 255 of the base 205.
Additionally
however, the first sliding disk 240a and the second sliding disk 240b further
include
axially extending portions 275a and 275b (FIG. 5) that act between the
radially outer
face 280 of the tensioner arm 210 and the radially inner ring-receiving wall
285 of the
base 205.
[0043]
The tensioner arm 210 has the tensioner pulley 215 rotatably mounted
thereon, for rotation about a tensioner pulley axis P (FIGS. 4 and 5), which
is spaced
from the tensioner arm axis A. Referring to FIG. 1, the tensioner arm 210 is
biased in a
free arm direction towards the leading belt span 115d of the belt 115 on one
side of the
alternator pulley 140. The tensioner arm 210 may be biased in the free arm
direction by
the tensioner arm biasing member 220.
[0044]
The tensioner arm biasing member 220 may be any suitable kind of biasing
member and is elastically compliant in compression, extension, torsion, or in
any other
flexure mode (i.e., the tensioner arm biasing member 220 will return to an
original state,
such an original length, after being stretched, compressed, torqued or
otherwise flexed
under an applied load). The tensioner arm biasing member 220 has a first end
292 that
is engaged with the tensioner arm 210 and a second end 302 that is engaged
with the
base 205 (FIG. 2).
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[0045] For example, as shown in FIGS. 1 to 5, the tensioner arm biasing
member
210 can include a helical compression spring 290 and a strut 310 that is
engaged
between the tensioner arm 210 and the base 205. The strut 310 is coupled to
the base
205 at a first strut end 315a and is coupled to the tensioner arm 210 at a
second strut
end 315b. The first strut end 315a can be coupled to the base 205 via a first
strut
fastener 320a engaged with a first strut lug 325a and the second strut end
315b is
coupled to the tensioner arm 210 via a second strut fastener 320b that is
engaged with
a second strut lug 325b of the strut 310 (FIG. 3). The strut 310 is axially
surrounded by
the helical compression spring 290. The strut 310 includes a piston 330 and a
shaft 335
that is configured to slidably engage the piston 330. The strut 310 is
configured to
provide a selected resistance to the movement of the tensioner arm 210
relative to the
base 205. The strut 310 can be a hydraulic strut that uses any suitable
hydraulic fluid,
including a suitable gas, to provide the selected resistance to the movement
of the
tensioner arm 210 along the arc 235. In some embodiments, the selected
resistance is
such that the strut 310 simply guides the helical compression spring 290. In
some
embodiments, the selected resistance is such that the strut 310 provides a
selected
amount of damping to the movement of the tensioner arm 210 along the arc 235.
It is
understood that a person skilled in the art would be able to determine the
selected
resistance through routine experimentation. In some embodiments, the strut 310
is
replaced with a suitable gas spring.
[0046] The helical compression spring 290 includes a first spring end
295 and a
second spring end 305. The first spring end 295 is engaged with the first
strut end 315a
and the second spring end 305 is coupled to the second strut end 315b. In
particular,
the first spring end 295 engages a first drive surface 300a on the first strut
end 315a
and the second spring end 305 engages a second drive surface 300b on the
second
strut end 315b. Although the tensioner arm biasing member 220 is depicted as a
helical
compression spring, in some embodiments, the tensioner arm biasing member 220
is a
helical extension spring.
[0047] In the example tensioner 200, the tensioner arm biasing member
220 has a
common axis with the arc 235 (FIG. 2). Furthermore, in some embodiments, the
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tensioner arm biasing member 220 generally extends along a linear path. For
example,
the tensioner arm biasing member 220 can be oriented such that the helical
compression spring 290, with the strut 310, extends and contracts along a
biasing axis
C that is generally arcuate about a common axis with the arc 235 (FIGS. 2 and
4). In
some embodiments, the tensioner arm biasing member 220 can extend along a path
that is not necessarily arcuate or that is arcuate but not about a common axis
with the
arc 235.
[0048] The tensioner pulley 215 is positioned to engage the belt 115 on
one side of
the alternator 120. In the example tensioner 200, the tensioner pulley 215 is
positioned
to engage the belt span 115d. However, in some embodiments, the tensioner
pulley
215 is positioned to engage the belt span 115c and the crankshaft pulley 110
rotates in
a direction opposite that of DIR1 shown in FIG. 1.
[0049] During operation, when the tensioner pulley 215 is engaged with
the leading
belt span 115d, the belt span 115d applies a hub load to the tensioner pulley
215. This
hub load acts on the tensioner arm 210 through the tensioner pulley 215. The
force on
the tensioner arm 210 is transferred through the tensioner arm biasing member
220,
and into the base 205 itself. The tensioner arm biasing member 220 resists the
pivoting
of the tensioner arm 210 and urges the tensioner arm biasing member 220 to
pivot
about the tensioner arm axis A in the opposite rotational direction to the
direction of the
pivoting of the tensioner arm 210 to press the tensioner pulley 215 into the
belt 115 and
to maintain tension in the belt 115.
[0050] The tensioner pulley 215 may include a pulley body 340, a bearing
345 and a
pulley mounting fastener 350 that is used to mount (e.g., by threaded
engagement) the
tensioner pulley 215 to the tensioner arm 210 (FIGS.4 and 5). An optional dust
shield
355 is provided to protect the bearing 345 from dust during operation of the
tensioner
200. The dust shield 355 may be a separate component that sandwiches the
bearing
345 to inhibit the migration of dust and debris into the bearing 345. In some
embodiments, the dust shield 355 is provided as an integral portion of the
tensioner arm
210.
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[0051] The bearing 345 may be a ball bearing, as shown, or it may be any
other
suitable type of bearing. The bearing 345 could also be a bushing in some
embodiments.
[0052] FIGS. 6 to 8 depict a second example tensioner, tensioner 400.
The
tensioner 400 differs from the tensioner 200 in that the tensioner arm biasing
member
405 does not include a strut. Instead, the tensioner arm biasing member 405
includes a
helical compression spring 410 having a first spring end 415 that is engaged
with the
tensioner arm 210 and a second spring end 420 that is engaged with the base
205. For
example, the first spring end 415 can engage a first drive surface 425a on the
tensioner
arm 210 and the second spring end 420 can engage a second drive surface 425b
on
the base 205 (FIG. 8).
[0053] As in the tensioner arm biasing member 220, the tensioner arm
biasing
member 405 may be any suitable kind of biasing member and is elastically
compliant in
compression or extension (i.e., the tensioner arm biasing member 405 will
return to an
original state, such an original length, after being stretched or compressed
under an
applied load). For example, instead of a helical compression spring, the
tensioner arm
biasing member 405 can include a helical extension spring. Furthermore, the
stiffness
of the spring included in the biasing member 405 may be varied to require a
selected
amount of force to extend or compress the spring, thereby providing at least
some
control over the translation of the tensioner arm 210 along the arc 235
relative to the
base 205. In some embodiments, the spring is configured to provide a selected
amount
of damping.
[0054] Similarly to the tensioner arm 210, the tensioner arm biasing
member 405 is
positioned has a common axis with the arc 235 (FIG. 7). For example, the
tensioner
arm biasing member 405 can be oriented such that the helical compression
spring 410,
extends and contracts along a biasing axis D that optionally has a common axis
with the
arc 235 (FIG. 7). Furthermore, in some embodiments, the tensioner arm biasing
member 405 can extend along a generally linear path that is tangential to the
arc 235.
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In some embodiments, the tensioner arm biasing member 405 can extend along a
generally linear path that is not necessarily tangential to the arc 235.
[0055] FIGS. 9 to 11 depict a third example tensioner, tensioner 500.
The tensioner
500 includes a tensioner arm 515 and a base 520. The tensioner arm 515 and the
tensioner arm 210 are similarly configured except that the tensioner arm 515
includes
two drive surfaces, a first tensioner arm drive surface 525a and a second
tensioner arm
drive surface 525b, for engagement with a first tensioner arm biasing member
505 and
a second tensioner arm biasing member 510, respectively. The base 520 is
similarly
configured to the base 205 except that the base 520 includes two drives
surfaces, a first
base drive surface 530a and a second base drive surface 530b, for engagement
with
the first tensioner arm biasing member 505 and the second tensioner arm
biasing
member 510, respectively.
[0056] Each of the first tensioner arm biasing member 505 and the second
tensioner
arm biasing member 510 is elastically compliant in compression or extension
(i.e., the
first tensioner arm biasing member 505 will return to an original state, such
an original
length, after being stretched or compressed under an applied load). The first
tensioner
arm biasing member 505 and the second tensioner arm biasing member 510 can be
any suitable type of biasing member. In some embodiments, the first tensioner
arm
biasing member 505 and the second tensioner arm biasing member 510 generally
extend along arcuate paths 555 and 560 (FIG. 10).
[0057] The first tensioner arm biasing member 505 and the second
tensioner arm
biasing member 510 operate in parallel with each other between the tensioner
arm 515
and the base 520. Having two tensioner arm biasing members operating in
parallel can
provide a more compact tensioner package. For example, in the example
tensioner
500, the first tensioner arm biasing member 505 and the second tensioner arm
biasing
member 510 each include an arcuate, helical compression spring, a first
arcuate helical
compression spring 535 and a second arcuate helical compression spring 540.
The first
arcuate helical compression spring 535 includes a first spring end 545a that
is engaged
with the first tensioner arm drive surface 525a and a second spring end 545b
that is
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engaged with the first base drive surface 530a. The second arcuate helical
compression spring 540 includes a first spring end 550a that is engaged with
the
second tensioner arm drive surface 525b and a second spring end 550b that is
engaged
with the second base drive surface 530b. By using two tensioner arm biasing
members
that operate in parallel, springs having smaller diameters may be used to
achieve the
same effective spring rate as a single spring with a larger diameter.
[0058] In some embodiments, the first arcuate helical compression spring
535 and
the second arcuate helical compression spring 540 have the same spring rate.
In some
embodiments, the first arcuate helical compression spring 535 and the second
arcuate
helical compression spring 540 have different spring rates. In some
embodiments, the
first arcuate helical compression spring 535 and the second arcuate helical
compression spring 540 operate in series between the tensioner arm 515 and the
base
520.
[0059] In some embodiments, the tensioner 500 includes more than two
tensioner
arm biasing members.
[0060] In some embodiments, the first tensioner arm biasing member 505
and the
second tensioner arm biasing member 510 include arcuate helical extension
springs
rather than arcuate helical compression springs. In some embodiments, the
first
tensioner arm biasing member 505 and the second tensioner arm biasing member
510
include a combination of arcuate helical compression and arcuate helical
extension
springs.
[0061] The stiffness of the springs included in the first tensioner arm
biasing
member 505 and the second tensioner arm biasing member 510 may be varied
(e.g., by
changing the diameter of the springs) to require a selected amount of force to
extend or
compress the springs, thereby providing at least some control over the
translation of the
tensioner arm 515 relative to the base 520. In some embodiments, the springs
are
configured to provide a selected amount of damping.
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[0062] FIGS. 12 to 14 depict a fourth example tensioner, tensioner 600.
The
tensioner 600 includes a base 605 and a tensioner arm 610. The base 605 and
the
tensioner arm 610 are configured similarly to the base 205 and the tensioner
arm 210.
The tensioner 600 includes a tensioner arm biasing member 615 that is
elastically
compliant in compression or extension (i.e., the tensioner arm biasing member
615 will
return to an original state, such an original length, after being stretched or
compressed
under an applied load). The tensioner arm biasing member 615 may be any
suitable
biasing member. In some embodiments, as shown in FIG. 13, the tensioner arm
biasing member 610 generally extends along an arcuate path 635.
[0063] The tensioner arm biasing member 615 includes a first end that is
engaged
with the tensioner arm 610 and a second end that is engaged with the base 605.
For
example, as shown in FIGS. 12 to 14, the tensioner arm biasing member 615
includes a
single arcuate helical compression spring 620 having a first spring end 625a
that is
engaged with a tensioner arm drive surface 630a and a second spring end 625b
that is
engaged with a base drive surface 630b. Although the tensioner arm biasing
member
615 is depicted as an arcuate helical compression spring, in some embodiments,
the
tensioner arm biasing member 615 is an arcuate helical extension spring.
[0064] The stiffness of the spring included in the tensioner arm biasing
member 615,
such as the arcuate helical compression spring 620, may be varied to require a
selected
amount of force to extend or compress the arcuate helical compression spring
620,
thereby providing at least some control over the translation of the tensioner
arm 610
relative to the base 605. In some embodiments, the spring is configured to
provide a
selected amount of damping.
[0065] Persons skilled in the art will appreciate that there are yet
more alternative
implementations and modifications possible, and that the above examples are
only
illustrations of one or more implementations. The scope, therefore, is only to
be limited
by the claims appended hereto.
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TABLE OF ELEMENTS:
Reference # Item Figure #
100 Engine 1
105 Crankshaft 1
110 Crankshaft Pulley 1
115 Belt (Endless Drive Member) 1
115a Trailing Belt Span (Relative to 1
Crankshaft Pulley)
115b Leading Belt Span (Relative to 1
Crankshaft Pulley)
115c Trailing Belt Span (Relative to
Alternator)
115d Leading Belt Span (Relative to
Alternator)
120 Alternator 1
125 Water Pump 1
130 Air Conditioning Compressor 1
135 Alternator Shaft 1
140 Alternator Pulley 1
145 Air Conditioning Compressor Shaft 1
150 Air Conditioning Compressor Pulley 1
200 (First Example) Tensioner 2 to 5
205 Base 2 to 5
210 Tensioner Arm 2 to 5
215 Tensioner Pulley 2 to 5
220 Tensioner Arm Biasing Member 2 to 4
225 Frame/Housing of the Alternator 1
230 Fasteners (for Mounting the Base to the 1
Frame of the Alternator)
235 Arc (along which the Tensioner Arm 210 2
translates)
A Tensioner Arm Axis 1,4
Axis of Rotation of Alternator Shaft 1
240a First Sliding Disk 4
240b Second Sliding Disk 4
245 Rear Plate 4, 5
250 First Face (of the Base) 5
255 Second Face (of the Base) 5
260 Clip Portions (of the Rear Plate) 5
265 Flange Portion (of the Rear Plate) 4
270a Radially Extending Portion (of First 4
Sliding Disk)
270b Radially Extending Portion (of Second 4
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Sliding Disk)
275a Axially Extending Portion (of the First 5
Sliding Disk)
275b Axially Extending Portion (of the Second 5
Sliding Disk)
280 Radially Outer Face of the Tensioner 5
Arm
285 Radially Inner Ring-Receiving Wall 5
290 Helical Compression Spring 2, 4
292 First End (of the Biasing Member) 2
295 First Spring End (of the Helical 2, 3
Compression Spring 290)
300a First Drive Surface (on the First Strut 3
End)
300b Second Drive Surface (on the Second 4
Strut End)
302 Second End (of the Biasing Member) 2
305 Second Spring End (of the Helical 2
Compression Spring 290)
310 Strut 3
315a First Strut End 3
315b Second Strut End 3
320a First Strut Fastener 3
320b Second Strut Fastener 3
325a First Strut Lug 3
325b Second Strut Lug 3
330 Piston 3
335 Shaft 3
Biasing Axis 2, 4
340 Pulley Body 4, 5
345 Bearing 5
350 Pulley Mounting Fastener 4, 5
355 Dust Shield 4, 5
400 (Second Example) Tensioner 6
405 Tensioner Arm Biasing Member 6
410 Helical Compression Spring 6
415 First Spring End (of Helical 6 to 8
Compression Spring 410)
420 Second Spring End (of Helical 6 to 8
Compression Spring 410)
425a First Drive Surface (on the Tensioner 8
Arm 410)
425b Second Drive Surface (on the Base 205) 8
Biasing Axis 7
500 (Third Example) Tensioner 9
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505 First Tensioner Arm Biasing Member 9
510 Second Tensioner Arm Biasing Member 9
515 Tensioner Arm 9
520 Tensioner Arm Base 9
525a First Tensioner Arm Drive Surface 9
525b Second Tensioner Arm Drive Surface 9
530a First Base Drive Surface 9
530b Second Base Drive Surface 9
535 First Arcuate Helical Compression 9
Spring
540 Second Arcuate Helical Compression 9
Spring
545a First Spring End (of the First Arcuate 11
Helical Compression Spring)
545b Second Spring End (of the First Arcuate 11
Helical Compression Spring)
550a First Spring End (of the Second Arcuate 11
Helical Compression Spring)
550b Second Spring End (of the Second 11
Arcuate Helical Compression Spring)
555 Arcuate Path 10
560 Arcuate Path 10
600 (Fourth Example) Tensioner 12
605 Base 12
610 Tensioner Arm 12
615 Tensioner Arm Biasing Member 12
620 Arcuate Helical Compression Spring 12
625a First Spring End (of the Arcuate Helical 14
Compression Spring)
625b Second Spring End (of the Arcuate 14
Helical Compression Spring)
630a Tensioner Arm Drive Surface 14
630b Base Drive Surface 14
635 Arcuate Path 13
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