Note: Descriptions are shown in the official language in which they were submitted.
1
LIMITED-SLIP DIFFERENTIAL SYSTEM
TECHNICAL FIELD
[0001] The present technology relates to limited-slip differential
systems.
BACKGROUND
[0002] Various types of differentials are conventionally used in
vehicles to enable
left wheels and right wheels to move at different speeds. One type of known
differential is
a limited-slip differential, which can transfer engine torque, when a wheel is
slipping, to
the wheel having more traction.
[0003] These limited-slip differentials generally include clutch packs
having clutch
plates that are disposed in a differential carrier. These clutch plates can be
difficult to
lubricate, which can result in high noise generation, increased wear and
reduced torque
transmission.
[0004] Therefore, there is a desire for a limited-slip differential
that can overcome
at least some of the above-described drawbacks.
SUMMARY
[0005] It is an object of the present technology to ameliorate at least
some of the
inconveniences present in the prior art.
[0006] According to one aspect of the present technology, there is
provided a
limited-slip differential system including a housing, a differential carrier,
a differential, a
clutch pack and a pressure system. The housing is configured to partially
receive a drive
shaft, a first axle, and a second axle. The differential carrier is disposed
within the housing,
and is rotatable relative to the housing. The differential carrier includes a
first carrier
portion, and a second carrier portion selectively connected to the first
carrier portion. The
differential is at least partially carried by the differential carrier, and is
operatively
connectable to the drive shaft, to the first axle, and to the second axle. The
differential is
Date Recue/Date Received 2022-06-30
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configured to distribute torque from the drive shaft to the first and second
axles in
accordance with a speed difference between the first and second axles that is
sensed by the
limited-slip differential system. The clutch pack includes a first plurality
of clutch plates
rotationally fixedly connected to one of the first and second carrier
portions, and a second
plurality of clutch plates rotationally fixedly connected to a hub member
fixedly
connectable to one of the first and second axles. The clutch plates of the
first and second
pluralities of clutch plates are sequentially placed relative to one another.
The pressure
system is configured to selectively exert an axial force on the clutch pack
for selectively
causing frictional engagement of the first and second plurality of clutch
plates with one
another. At least one of the first and second carrier portions at least
partially define at least
one lubrication channel extending at least partially radially, the at least
one lubrication
channel fluidly connecting an exterior of the differential carrier to an
interior thereof for
lubricating at least two clutch plates of the clutch pack.
[0007] In some embodiments, the second pressure system includes a
piston in
contact with one of the clutch plates of the clutch pack, and a rotary pump
operatively
connectable between one of the first and second axles and the differential
carrier. The
rotatory pump is configured to selectively exert the axial force on the clutch
pack.
[0008] In some embodiments, in response to the rotary pump generating a
hydraulic pressure, the piston causes the first and second plurality of clutch
plates to
frictionally engage with one another thereby connecting the first and second
axles and
redistributing torque from one of the first and second axles with a higher
angular velocity
to another of the first and second axles with a lower angular velocity.
[0009] In some embodiments, the piston is made of aluminium.
[0010] In some embodiments, the differential is configured to enable
the first and
second axles to rotate at different angular velocities when the speed
difference is below a
predetermined threshold, and limit slip by progressively redistributing torque
to one of the
first and second axles in response to the speed difference between the first
and second axles
exceeding the predetermined threshold, the speed difference being sensed by
the limited-
slip differential system.
Date Recue/Date Received 2022-06-30
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[0011] In some embodiments, the at least one lubrication channel is
arcuate.
[0012] In some embodiments, the at least one lubrication channel is
linear.
[0013] In some embodiments, the at least one lubrication channel is
defined by the
second carrier.
[0014] In some embodiments, the at least one lubrication channel is
configured to
guide lubricant from the exterior of the differential carrier to radial edges
of the at least two
clutch plates.
[0015] In some embodiments, the at least one lubrication channel
includes four
lubrication channels.
[0016] In some embodiments, the four lubrication channels are equally
circumferentially spaced.
[0017] In some embodiments, the four lubrication channels are disposed
symmetrically about a longitudinal plane.
[0018] In some embodiments, the differential includes a drive gear
operatively
connectable to the drive shaft, a ring gear engageable with the pinion gear,
and fixedly
connected to the differential carrier, a first side gear fixedly connected to
the differential
carrier, the first side gear being operatively connectable to the first shaft,
a second side gear
fixedly connected to the differential carrier, the second side gear being
operatively
connectable to the second shaft, and at least one pinion gear connected to the
differential
carrier, and engageable with the first and second side gears.
[0019] In some embodiments, the at least one pinion gear is two pinion
gears, and
the differential carrier includes a cross shaft extending through and fixedly
connected the
differential carrier and anchored therein for rotation therewith, the two
pinion gears being
rotationally mounted on the cross shaft such that the pinions gears configured
to revolve
with the differential case, and also able to rotate about the axis of the
cross shaft to
compensate for the speed difference between the first and second axles.
Date Recue/Date Received 2022-06-30
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[0020] In the context of the present specification, unless expressly
provided
otherwise, the words "first", "second", "third", etc. have been used as
adjectives only for
the purpose of allowing for distinction between the nouns that they modify
from one
another, and not for the purpose of describing any particular relationship
between those
nouns.
[0021] It must be noted that, as used in this specification and the
appended claims,
the singular form "a", "an" and "the" include plural referents unless the
context clearly
dictates otherwise.
[0022] As used herein, the term "about" in the context of a given value
or range
refers to a value or range that is within 20%, preferably within 10%, and more
preferably
within 5% of the given value or range.
[0023] As used herein, the term "and/or" is to be taken as specific
disclosure of
each of the two specified features or components with or without the other.
For example
"A and/or B" is to be taken as specific disclosure of each of (i) A, (ii) B
and (iii) A and B,
just as if each is set out individually herein.
[0024] Implementations of the present technology each have at least one
of the
above-mentioned objects and/or aspects, but do not necessarily have all of
them. It should
be understood that some aspects of the present technology that have resulted
from
attempting to attain the above-mentioned object may not satisfy this object
and/or may
satisfy other objects not specifically recited herein.
[0025] Additional and/or alternative features, aspects, and advantages
of
implementations of the present technology will become apparent from the
following
description, the accompanying drawings, and the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] For a better understanding of the present technology, as well as
other aspects
and further features thereof, reference is made to the following description
which is to be
used in conjunction with the accompanying drawings, where:
Date Recue/Date Received 2022-06-30
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[0027] Figure 1 is a perspective view taken from a top, rear, left side
of a limited-
slip differential system according to an embodiment of the present technology;
[0028] Figure 2 is an exploded top view of the limited-slip
differential system of
Figure 1;
[0029] Figure 3 is a cross-sectional view of the limited-slip
differential system of
Figure 1 taken along a generally horizontal plane passing through a center of
the limited-
slip differential system;
[0030] Figure 4 is a cross-sectional view of the limited-slip
differential system of
Figure 1 taken along a longitudinal plane passing through two lubrication
channels of a
differential carrier;
[0031] Figure 5 is an exploded view of a differential carrier of the
limited-slip
differential system of Figure 1;
[0032] Figure 6 is a perspective view taken from a rear, right side of
the differential
carrier of Figure 5;
[0033] Figure 7 is a rear elevation view of the differential carrier of
Figure 5;
[0034] Figure 8 is a cross-sectional perspective view of the
differential carrier of
Figure 5 taken along the line 8-8 of Figure 7;
[0035] Figure 9 is a perspective view taken from a rear, left side of a
differential
portion of a differential carrier of a limited-slip differential system
according to another
embodiment of the present technology; and
[0036] Figure 10 is a right side elevation view of the differential
portion of Figure
9.
DETAILED DESCRIPTION
[0037] The present disclosure is not limited in its application to the
details of
construction and the arrangement of components set forth in the following
description or
Date Recue/Date Received 2022-06-30
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illustrated in the drawings. The disclosure is capable of other embodiments
and of being
practiced or of being carried out in various ways. Also, the phraseology and
terminology
used herein is for the purpose of description and should not be regarded as
limiting. The
use of "including", "comprising", or "having", "containing", "involving" and
variations
thereof herein, is meant to encompass the items listed thereafter as well as,
optionally,
additional items. In the following description, the same numerical references
refer to
similar elements.
[0038] The present technology discloses a limited-slip differential
system. The
limited-slip differential system includes a housing in which is disposed a
differential
carrier, a differential, a clutch pack and a pressure system. The differential
carrier has two
portions, one of which defines lubrication channels for providing a passage
for lubricant to
flow from the outside of the differential carrier to the inside thereof. This
is notably useful
to lubricate the clutch pack which is disposed within the differential
carrier.
[0039] A limited-slip differential system 20 is shown in Figure 1. The
limited-slip
differential system 20 is operatively connectable to an engine of a vehicle
via a drive shaft
22 (shown schematically). The limited-slip differential system 20 is also
operatively
connectable to left and right wheels (not shown) via, respectively, left and
right axles 24a,
24b (shown schematically). The limited-slip differential system 20 is
configured to
distribute torque to the axles 24a, 24b. As will be described below, the
limited-slip
differential system 20 is configured to enable the axles 24a, 24b to rotate at
different
angular speeds and is further adapted to limit slip of the wheels that are
connected to the
axles 24a, 24b by progressively redistributing torque to the wheel with
greater traction in
response to a difference in angular speed between the axles 24a, 24b exceeding
a
predetermined threshold.
[0040] The limited-slip differential system 20 includes a housing 30
configured to
receive part of the drive shaft 22, and part of the axles 24a, 24b therein.
The housing 30,
as will become apparent from the following description, is also configured to
receive
components of the limited-slip differential system 20 therein. The housing 30
includes
housing portions 32, 34 that are connected to one another via fasteners 36
such that the
Date Recue/Date Received 2022-06-30
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housing portions 32, 34 are selectively connected to one another. Though six
fasteners 36
are shown in the accompanying figures, it is contemplated that there could be
more or fewer
than six fasteners in other embodiments. It is contemplated that in other
embodiments, the
housing portions 32, 34 could be connected to one another differently, for
example via an
adhesive. Though not shown herewith, a seal is provided between the housing
portions 32,
34. The housing portions 32, 34 are shaped differently so as to tightly
surround the
components received therein.
[0041] With reference to Figures 2 to 4, the limited-slip differential
system 20 also
includes a differential 40, a differential carrier 42, a pressure system 44, a
clutch pack 46
and a hub member 48, all of which are, at least partially, housed in the
housing 30. A
description of the differential 40, which includes a drive gear 50, a ring
gear 52, a side gear
54, a side gear 56 and two pinion gears 58a, 58b, will now be provided.
[0042] The drive gear 50 is operatively connectable to the drive shaft
22 such that
in response to the drive shaft 22 rotating, the drive gear 50 rotates. The
drive gear 50 is in
operational engagement with the ring gear 52.
[0043] The ring gear 52 is fixedly connected to the differential
carrier 42 via
fasteners 53. The fasteners 53 are bolts such that the ring gear 52 is
removably connected
to the differential carrier 42. It is contemplated that other fasteners could
be used. In some
embodiments, the ring gear 52 could be permanently connected to the
differential carrier
42. As the ring gear 52 is fixedly connected to the differential carrier 42,
in response to the
ring gear 52 rotating, the differential carrier 42 also rotates.
[0044] The side gears 54, 56 are received in the differential carrier
42. The side
gear 54 is operationally connectable to the axle 24a, whereas the side gear 56
is
operationally connectable to the axle 24b. Thus, in response to the side gear
54 rotating,
the axle 24a rotates and in response to the side gear 56 rotating, the axle
24b rotates.
[0045] The pinion gears 58a, 58b, which are also received in the
differential carrier
42, are interconnected by a cross-shaft 59 that extends through the housing 30
such that the
cross-shaft 59 is fixed relative to the differential carrier 42. As a result,
the ring gear 52,
Date Recue/Date Received 2022-06-30
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the differential carrier 42 and the pinion gears 58a, 58b can all revolve
about an axle axis
26. The axle axis 26 is aligned with the axles 24a, 24b. It is contemplated
that in other
embodiments, there could be more or less than two pinion gears. Furthermore,
the pinion
gears 58a, 58b are operationally engageable with the side gears 54, 56 to
transmit motion
therebetween.
[0046] Referring to Figures 5 to 8, the differential carrier 42 is
generally configured
to carry the ring gear 52, the side gears 54, 56 and the pinion gears 58a,
58b. The differential
carrier 42 is also configured to receive the clutch pack 46, the pressure
system 44 and the
hub member 48 therein. The differential carrier 42 will be described in
greater detail below.
[0047] The pressure system 44, as mentioned, is received in the
differential carrier
42. More precisely, the pressure system 44 is rotatably mounted to the
differential carrier
42. The pressure system 44 includes a rotary pump 60 and a piston 62, both of
which are
configured to be disposed between the axle 24a and the differential carrier
42. It is
contemplated that in other embodiments, the pressure system 44 could be
different from
the one described herewith.
[0048] The pump 60 defines a closed fluid system that is isolated from
fluid
communication from the remaining portions of the limited-slip differential
system 20 (e.g.,
the fluid that lubricates side gears 54, 56 and pinions 58a, 58b). The closed
fluid system of
the pump 60 could utilize silicone gel as the lubricant, for example, because
of its high
viscosity and high thermal expansion rate.
[0049] The piston 62 is operatively connected to the rotary pump 60 and
is in
contact with the clutch pack 46. The piston 62 includes seals that help to
isolate fluid from
the pump 60. The piston 62 is made of aluminum. It is contemplated that in
other
embodiments, the piston 62 could be made of other material. As will be
described in greater
detail below, the piston 62 being made of aluminum instead of plastic can
increase the
locking torque of the limited-slip differential system 20.
Date Recue/Date Received 2022-06-30
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[0050] As will be described below, in response to a difference between
the angular
velocities of the axles 24a, 24b, the pump 60 is configured to produce a
hydraulic pressure
to move the piston 62 to exert an axial force on the clutch pack 46.
[0051] The clutch pack 46, as mentioned above, is configured to be
received in the
differential carrier 42. The clutch pack 46 includes a plurality of clutch
plates, made up of
a plurality of carrier plates 70a and a plurality of hub plates 70b. The
clutch plates 70a, 70b
are sequentially placed relative to one another. In other words, within the
clutch pack 46,
the carrier plate 70a is followed by a hub plate 70b, which is in turn
followed by a carrier
plate 70a, and so on and so forth. The clutch plates 70a, 70b are axially
spaced from one
another.
[0052] Each one of the carrier plates 70a has four locking projections
72a (best
seen in Figure 8) that are equally circumferentially spaced and that project
radially
outwardly from an outer edge of the respective carrier plate 70a. It is
contemplated that in
some embodiments, the four locking projections 72a could have various
circumferential
spacing. The locking protrusions 72a are configured to be received in recesses
104 defined
in the differential carrier 42, and for rotationally fixing the carrier plates
70a to the
differential carrier 42.
[0053] Each one of the hub plates 70b has a plurality of projections
72b (best seen
in Figure 8). The projections 72b project radially inwardly from an inner edge
of the hub
plates 70b. The projections 72b are configured to engage with projections 49
extending
from the hub member 48 and are for rotationally fixing the hub plates 70b to
the hub
member 48.
[0054] In operation, when the piston 62 exerts an axial force on the
clutch pack 46,
the clutch plates 70a, 70b move towards one another until there is frictional
engagement
between the clutch plates 70a, 70b. Eventually, the clutch plates 70a, 70b are
fixed relative
to one another.
[0055] The hub member 48, sometimes referred to as an inner plate
carrier, is
received in the differential carrier 42. The hub member 48 is received in
apertures defined
Date Recue/Date Received 2022-06-30
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in the pump 60 and the piston 62. Also, the hub member 48 has the projections
49 for being
rotationally fixed relative to the hub plates 70b. The hub member 48 is also
operatively
connectable to the axle 24a, such that when the axle 24a rotates, the hub
member 48 also
rotates.
[0056] With continued reference to Figures 5 to 8, the differential
carrier 42 will
now be described in greater detail. The differential carrier 42 includes a
carrier portion 80
and a carrier portion 82. The carrier portions 80, 82 are connected to one
another via
fasteners 84. The fasteners 53 also assist in connecting the carrier portions
80, 82 to one
another (see Figure 2). The fasteners 84 are bolts such that the carrier
portions 80, 82 are
removably connected to one another. It is contemplated that other fasteners
could be used.
[0057] The carrier portion 80 has at a base thereof a connecting
segment 90. The
connecting segment 90 defines apertures 92 which receive the fasteners 53
therein. The
connecting segment 90 also defines apertures 93 which receive the fasteners 84
therein.
Radially inwardly from the connecting segment 90 the carrier portion 80 has an
intermediate segment 94 that is configured to abut the pressure system 44.
Radially
inwardly from the intermediate segment 94, the carrier portion 82 includes a
hub segment
96 that extends axially. The hub segment 96 defines an aperture 98 that is
configured to
receive the axle 24a therein. The hub segment 96 is also engaged with the hub
member 48.
[0058] The carrier portion 82 is longer than the carrier portion 80 and
is generally
shaped like a hollow dome, so as to receive components therein. It is
contemplated that in
other embodiments, the carrier portion 82 could be sized differently.
[0059] At a base thereof, the carrier portion 82 has four connecting
segments 102a,
102b, 102c, 102d. The four connecting segments 102a, 102b, 102c, 102d are
separated by
lubrication channels 120, which will be described in greater detail below.
Each of the four
connecting segments 102a, 102b, 102c, 102d defines axially extending apertures
103a that
receive the fasteners 53. The connecting segments 102a, 102c also define
axially extending
apertures 103b that are configured to receive the fasteners 84. Furthermore,
each of the
connecting segments 102a, 102b, 102c, 102d defines, on a radially inner edge
thereof, a
Date Recue/Date Received 2022-06-30
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locking recess 104 (shown in Figure 8) configured to receive one of the
locking protrusions
72a.
[0060] Extending axially from the connecting segments 92, the carrier
portion 82
has a receiving section 106 configured to receive the side gears 54, 56 and
the pinions 58a,
58b therein. The receiving section 106 defines two apertures 108 opposite to
one another
configured to receive the cross-shaft 59. The receiving section 106 also
defines two access
apertures 110 that are relatively large and enable access to the interior of
the receiving
section. The receiving section 106 further defines two lubrication apertures
112 that
extends axially through the receiving section 106.
[0061] Extending axially from the receiving section 106, the carrier
portion 82 also
has a hub section 114 that defines an aperture 115 configured to receive the
axle 24b
therein.
[0062] The lubrication channels 120 will now be described in greater
detail. The
lubrication channels 120 are defined by the carrier portion 82. It is
contemplated that in
other embodiments, the lubrication channels 120 could be defined by the
carrier portion
80. It is further contemplated that in other embodiments, the lubrication
channels 120 could
be partially defined by both of the carrier portions 80, 82. In the present
embodiment, the
carrier portion 82 defines four lubrication channels 120. It is contemplated
that in other
embodiments, there could be more or fewer than four lubrication channels.
Thus, in some
embodiments, there could be more or fewer than four connecting segments. The
four
lubrication channels 120 are equally circumferentially spaced. It is
contemplated that in
other embodiments, the lubrication channels 120 could have various
circumferential
spacing. Additionally, the lubrication channels 120 are arcuate. As will be
described below,
the lubrication channels 120 being arcuate may help enhance flow of lubricant
therethrough
when the clutch pack 46 rotates.
[0063] The lubrication channels 120 extend radially throughout the
carrier portion
82, such that the lubrication channels 120 provide a passage from an exterior
of the carrier
portion 82 to an interior of the carrier portion 82. In other words, the
lubrication channels
Date Recue/Date Received 2022-06-30
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120 fluidly connect the exterior of the differential carrier 42 to the
interior of the differential
carrier 42.
[0064] The lubrication channels 120 also extend axially along a portion
of the
carrier portion 82. More precisely, the lubrication channels 120 are
configured to be
generally axially aligned with the clutch pack 46 when the limited-slip
differential system
20 is fully assembled (best seen in Figure 4).
[0065] Thus, when there is lubricant in the housing 30, the lubricant
can flow from
outside the differential carrier 42 to the inside thereof by the way of the
lubrication channels
120. Since the lubrication channels 120 extend axially, the lubricant is
guided to flow
across all of the clutch plates 70a, 70b. In some embodiments, the lubrication
channels 120
could be configured to flow across a portion of the clutch plates 70a, 70b. In
the present
embodiment, the lubricant is configured to flow across radial edges of the
clutch plates
70a, 70b. The lubrication channels 120 being arcuate can help enhance
lubricant flow rate
from the outside of the differential carrier 42 to the inside thereof,
particularly when the
clutch pack 46 rotates.
[0066] It is to be noted that when there is lubricant within the
housing 30, the
lubricant can also flow to the inside of the differential carrier 42 through
the lubrication
apertures 112. However, entry of lubricant therefrom is limited by one of the
clutch plates
70a, 70b closest to the lubrication apertures 112.
[0067] Thus, the lubrication channels 120 in some cases could provide
better
lubrication of the clutch plates 70a, 70b. Notably, there may be a reduction
of noise during
operation of the clutch pack 46 compared to clutch packs not equipped with the
herein
described lubrication channels 120.
[0068] Additionally, better lubrication may aid in extending life of
each of the
clutch plates 70a, 70b. Furthermore, the enhanced lubrication of the clutch
plates 70a, 70b
may result in better thermal dissipation, which can also result in improving
the locking
torque differential, and holding maximum torque for longer duties.
Additionally, since, as
mentioned above, the piston 62 is made of aluminum, the piston 62 may also
benefit from
Date Recue/Date Received 2022-06-30
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improved lubrication, in some cases, possible from the presence of the
lubrication channels
120 by having enhanced thermal dissipation. Additionally, in operation, the
lubricant will
expand more while as a temperature thereof rises, therefore increasing the
pressure on the
piston 62. As a result of the increased pressure on the piston 62, the locking
torque of the
clutch plates 70a, 70b will also increase.
[0069] An alternative embodiment of the carrier portion 82, namely
carrier portion
82', is shown in Figures 9 and 10. As the carrier portion 82 is generally
similar to the carrier
portion 82', portions of the carrier portion 82' similar to the carrier
portion 82 will not be
described again herewith.
[0070] The carrier portion 82' differs from the carrier portion 82 in
that the
lubrication channels 120' are linear, extending radially outward from a center
of the carrier
portion 82'. Furthermore, the lubrication channels 120 are disposed
symmetrically about a
plane 121'. The plane 121' passes through a center of the differential carrier
42 (i.e.,
through the apertures 103b). It is contemplated that in some embodiments, the
lubrication
channels 120' could not be defined symmetrically about a symmetry plane.
[0071] It is contemplated that in other embodiments of the present
technology, one
or more of the lubrication channels 120 could be arcuate, and others could be
linear.
[0072] The remainder of the description will be described with
reference to the
carrier portion 82 and the lubrication channels 120, though it is understood
that the same
applies to the carrier portion 82'.
[0073] Briefly, a description of the limited-slip differential system
20 in operation
(i.e., when the limited-slip differential system 20 is connected to the drive
shaft 22 and the
axles 24a, 24h) will be provided.
[0074] In operation, the drive gear 50 which is operatively connected
to the drive
shaft 22 engages the ring gear 52. The ring gear 52 is mounted to the
differential carrier 42
so that when the ring gear 52 revolves about the axle axis 26, the
differential carrier 42 also
revolves about the axle axis 26. Additionally, as the differential carrier 42
revolves, the
pinions 58a, 58b revolve as well. The side gears 54, 56 are rotationally fixed
to the axles
Date Recue/Date Received 2022-06-30
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24a, 24b whereby any rotation of the side gears 54, 56 causes wheels (not
shown)
connected to the axles 24a, 24h to rotate therewith. In this manner, the
limited-slip
differential system 20 operates like a standard open differential. If there is
a difference in
traction between the left and right wheels, the torque from the drive gear 50
will be
transferred to the wheel under less tractions, this will cause a difference in
rotation speed
between the wheels and cause the pinions 58a, 58b to start to rotate about the
axis of cross
shaft 59.
[0075] However, when the speed difference between the respective wheels
of the
axles 24a, 24b, which is sensed by the limited-slip differential system 20,
exceeds a
predetermined threshold (called the "cutting point"), the limited-slip
differential system 20
transmutes from an open differential to a progressive limited-slip
differential. The "cutting
point" has a predetermined value, for example 1 to 15 RPM. It is contemplated
that the
cutting point could have another value in other embodiments. At the cutting
point, the
difference in axle speeds causes the rotary pump 60 to build up a pressure so
as to drive
the piston 62 against the clutch pack 46. Driving the piston 62 against the
clutch pack 46
causes the carrier plates 70a and the hub plates 70b to move towards one
another until the
carrier and hub plates 70a, 70b are frictionally engaged with one another.
This engagement
limits wheel slip by transferring torque to the wheel that has greater
traction (i.e., the wheel
that is spinning less). The greater the difference in angular velocity between
the axles 24a,
24b, the greater is the pressure generated by the pump 60. At the "cutting
point", any further
increase in difference in wheel speed results in a linearly proportional
increase in torque
transfer, producing a progressive differential response.
[0076] Below the cutting point, the torque variation across the clutch
pack may be
zero or a small constant value. Sometimes, the clutch pack 46 is pre-loaded by
a spring 47
(shown in Figures 3 and 4), in which case the torque variation across the
clutch pack 46
(for a difference in wheel speed less than the cutting point) can be a small
constant value.
[0077] Thus, the limited-slip differential system 20 initially
functions practically
like an open differential, allowing optimal steering unencumbered by the
limited-slip
coupling. In response to the difference in wheel speed of respective axles
24a, 24b
Date Recue/Date Received 2022-06-30
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exceeding the "cutting point", the differential 40 engages, progressively
transferring torque
to the wheel with greater traction as a function of the difference in wheel
speed. As the
difference in wheel speed increases, the transfer of torque increases in a
virtually linear
fashion. Unlike the regressive differential, there is no plateau of torque
transfer. Thus, in
extreme conditions, the amount of torque transferred will be much larger than
what could
be transferred under similar circumstances by a regressive-type limited-slip.
[0078]
Modifications and improvements to the above-described embodiments of
the present invention may become apparent to those skilled in the art. The
foregoing
description is intended to be exemplary rather than limiting. The scope of the
present
invention is therefore intended to be limited solely by the appended claims.
Date Recue/Date Received 2022-06-30
