U.S. patent application number 17/102799 was filed with the patent office on 2021-03-18 for brake system for mine trucks.
The applicant listed for this patent is Carlisle Brake & Friction, Inc.. Invention is credited to David Burns, Chris Davis, Brad Desatnik, Michael Koerth.
Application Number | 20210079967 17/102799 |
Document ID | / |
Family ID | 1000005237701 |
Filed Date | 2021-03-18 |
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United States Patent
Application |
20210079967 |
Kind Code |
A1 |
Burns; David ; et
al. |
March 18, 2021 |
Brake System For Mine Trucks
Abstract
A brake system for a piece of equipment includes a series of
rotors and stators, and a first brake actuator including at least
one first piston positioned within a first chamber such that
pressurization of the first chamber causes the at least one first
piston to operatively engage at least one of rotors or stators such
that the rotors and stators are compressed together and thereby
create braking torque, and may also include a second brake actuator
including at least one spring operatively coupled to at least one
second piston positioned within a second chamber such that
depressurization of the second chamber causes the at least one
second piston to operatively engage at least one of the rotors or
stators such that the pluralities of rotors and stators are
compressed together and thereby create braking torque.
Inventors: |
Burns; David; (Macedonia,
OH) ; Davis; Chris; (Hinckley, OH) ; Desatnik;
Brad; (Chesterland, OH) ; Koerth; Michael;
(Twinsburg, OH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Carlisle Brake & Friction, Inc. |
Solon |
OH |
US |
|
|
Family ID: |
1000005237701 |
Appl. No.: |
17/102799 |
Filed: |
November 24, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
16034666 |
Jul 13, 2018 |
10851859 |
|
|
17102799 |
|
|
|
|
62537153 |
Jul 26, 2017 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B60Y 2200/417 20130101;
F16D 65/0971 20130101; B60T 13/22 20130101; F16D 2055/0091
20130101; F16D 55/24 20130101; F16D 57/007 20130101; F16D 65/0972
20130101; F16D 2055/0095 20130101 |
International
Class: |
F16D 65/097 20060101
F16D065/097; B60T 13/22 20060101 B60T013/22; F16D 55/24 20060101
F16D055/24 |
Claims
1. A brake system for a piece of equipment having a frame and a
shaft rotatable relative to the frame, the brake system comprising:
a series of rotors and stators, including a plurality of rotors
configured to be operatively coupled to the shaft and configured to
rotate with the shaft relative to the frame, and a plurality of
stators configured to be operatively coupled to the frame and
configured to be fixed against rotation relative to the frame; and
a first brake actuator including at least one first piston
positioned within a first chamber such that pressurization of the
first chamber causes the at least one first piston to operatively
engage at least one of the rotors or stators such that the rotors
and stators are compressed together and thereby create braking
torque.
2. The brake system of claim 1, further comprising: a second brake
actuator including at least one spring operatively coupled to at
least one second piston positioned within a second chamber such
that depressurization of the second chamber causes the at least one
second piston to operatively engage at least one of the rotors or
stators such that the rotors and stators are compressed together
and thereby create braking torque.
3. The brake system of claim 1, wherein at least one of the rotors
or stators comprises a monolithic piece.
4. The brake system of claim 1, wherein at least one of the rotors
or stators comprises carbon-carbon.
5. The brake system of claim 1, wherein the plurality of stators
are arranged in an alternating sequence with the plurality of
rotors.
6. The brake system of claim 1, further comprising: a hub
configured to be mounted to the shaft for rotation therewith,
wherein the plurality of rotors are configured to be operatively
coupled to the shaft via the hub.
7. The brake system of claim 6, wherein each of the plurality of
rotors includes at least one of a key or a keyway and the hub
includes at least one of the other of a key or a keyway for
engaging the at least one key or keyway of the rotors for causing
the plurality of rotors to rotate with the hub and the shaft.
8. The brake system of claim 1, further comprising: a housing
configured to be mounted to the frame and fixed against rotation
relative thereto, wherein each of the plurality of stators includes
at least one of a notch or a ridge and the housing includes at
least one of the other of a notch or a ridge for engaging the at
least one notch or ridge of the stators for fixing the plurality of
stators against rotation relative to the frame.
9. The brake system of claim 1, further comprising: a load
distribution plate positioned between the at least one first piston
and the series of rotors and stators for providing an even
compression of the pluralities of rotors and stators when the at
least one first piston operatively engages the at least one of the
rotors or stators.
10. The brake system of claim 1, wherein the pluralities of rotors
and stators are configured to be free from oil flow.
11. A piece of equipment comprising: a frame; a shaft rotatable
relative to the frame; and a brake system comprising: a series of
rotors and stators, including a plurality of rotors operatively
coupled to the shaft and rotatable with the shaft relative to the
frame, and a plurality of stators operatively coupled to the frame
and fixed against rotation relative to the frame; and a first brake
actuator including at least one first piston positioned within a
first chamber such that pressurization of the first chamber causes
the at least one first piston to operatively engage at least one of
the rotors or stators such that the rotors and stators are
compressed together and thereby create braking torque for resisting
rotation of the shaft relative to the frame.
12. The piece of equipment of claim 11, wherein the brake system
further comprises: a second brake actuator including at least one
spring operatively coupled to at least one second piston positioned
within a second chamber such that depressurization of the second
chamber causes the at least one second piston to operatively engage
at least one of the rotors or stators such that the rotors and
stators are compressed together and thereby create braking torque
for resisting rotation of the shaft relative to the frame.
13. The piece of equipment of claim 11, wherein the shaft is an
axle.
14. The piece of equipment of claim 11, wherein the shaft is a
spindle.
15. The piece of equipment of claim 11, further comprising: at
least one wheel mounted to the shaft and rotatable therewith.
16. The piece of equipment of claim 11, wherein at least one of the
rotors or stators comprises a monolithic piece.
17. The piece of equipment of claim 11, wherein at least one of the
rotors or stators comprises carbon-carbon.
18. The piece of equipment of claim 11, wherein the plurality of
stators are arranged in an alternating sequence with the plurality
of rotors.
19. A brake system for a piece of equipment having a frame, the
brake system comprising: a series of rotors and stators, including
a plurality of rotors configured to be rotatable relative to the
frame, and a plurality of stators configured to be operatively
coupled to the frame and configured to be fixed against rotation
relative to the frame; and a first brake actuator including at
least one first piston positioned within a first chamber such that
pressurization of the first chamber causes the at least one first
piston to operatively engage at least one of the rotors or stators
such that the rotors and stators are compressed together and
thereby create braking torque.
20. The brake system of claim 19, further comprising: a second
brake actuator including at least one spring operatively coupled to
at least one second piston positioned within a second chamber such
that depressurization of the second chamber causes the at least one
second piston to operatively engage at least one of the rotors or
stators such that the rotors and stators are compressed together
and thereby create braking torque.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a Continuation of U.S. patent
application Ser. No. 16/034,666 filed Jul. 13, 2018 (pending),
which claims the benefit of priority to U.S. Provisional Patent
Application Ser. No. 62/537,153 filed Jul. 26, 2017 (expired), the
disclosures of which are incorporated by reference herein in their
entirety.
TECHNICAL FIELD
[0002] The present invention relates to a brake system and, more
particularly, to a brake system for diesel electric vehicles,
including large off-highway equipment vehicles such as mine trucks,
and other pieces of equipment.
BACKGROUND
[0003] Mine trucks and other large off-highway equipment vehicles
are often configured as diesel electric vehicles. Diesel electric
vehicles use a diesel engine to generate electricity, which is used
to power multiple electric motors to propel the vehicle. The
electric motors can also be operated in regenerative mode, where
the motor is used to generate electricity. In regenerative mode,
the electric motors act as brakes, slowing or retarding the
vehicle. The electricity generated by the motors in the braking
process can then either be stored in a battery or discarded as
waste heat.
[0004] As a result of this propulsion system, mechanical brakes on
a diesel electric vehicle have two main functions. First, the
mechanical brakes may serve as emergency brakes. To that end, in
case of electrical or motor failure, the mechanical brakes must be
able to stop an overloaded vehicle moving at full speed. The
vehicles are required to meet the requirements of the ISO 3450
specification. Second, the mechanical brakes may provide final
braking of the vehicle. In this regard, at low speed (e.g., under
10 km/hr), the electric motors are not as effective at retarding or
slowing the vehicle. Thus, the mechanical brakes are used to bring
the vehicle to a complete stop. Typically, these stops are very low
energy.
[0005] Conventional mechanical brakes used on diesel electric
vehicles have one of two designs. Typically, for small to medium
sized trucks (e.g., less than or equal to approximately 200-300
tons), dry caliper brakes are typically used. Such brakes consist
of a caliper, a set of pads, and a steel or cast iron rotor. While
these brakes may be relatively inexpensive, high wear rates can
require the pads to be replaced as frequently as every 6-12 months.
Moreover, these brakes are not capable of passing the ISO 3450
emergency stop specification, when used for heavier vehicles. In
this regard, when energies and temperatures become undesirably
high, increased wear and/or coefficient fade result.
[0006] For medium to large sized trucks (e.g., greater than or
equal to approximately 200-300 tons), wet brakes are typically
used. Such brakes consist of a pack of friction discs and steel
opposing plates. The friction discs include a paper-based friction
material bonded to both sides of a steel core. Grooves are also cut
into the friction material to aid in oil flow and distribution. The
friction discs may include a spline cut into the inner diameter,
while the steel opposing plates may include a spline cut into the
outer diameter. Typically, the friction discs rotate, while the
opposing plates do not. The discs are enclosed in a housing with an
actuating piston on one side. The housing may be partially filled
with oil, or oil may be circulated through the housing by a pump.
When braking is desired, the piston is actuated, thereby
compressing all of the friction and opposing discs to create
braking torque. While these brakes may have a relatively long life
and may readily pass the ISO 3450 specification and emergency
stops, parasitic drag caused by the oil flow in the brake when the
brake is disengaged can rob the engine of horsepower and result in
decreased fuel efficiencies. Moreover, these brakes are
significantly larger and more complex than dry caliper brakes,
requiring oil pumps, reservoirs, heat exchangers, and other
componentry, thereby resulting in greater expense and weight.
[0007] Thus, there is a need for an improved brake system for
off-highway equipment vehicles such as mine trucks that overcome
drawbacks of conventional brake systems discussed above.
SUMMARY
[0008] In one embodiment, a brake system for a piece of equipment
having a frame and a shaft rotatable relative to the frame includes
a series of rotors and stators, including a plurality of rotors
configured to be operatively coupled to the shaft and configured to
rotate with the shaft relative to the frame, and a plurality of
stators configured to be operatively coupled to the frame and
configured to be fixed against rotation relative to the frame. The
brake system also includes a first brake actuator including at
least one first piston positioned within a first chamber such that
pressurization of the first chamber causes the at least one first
piston to operatively engage at least one of the rotors or stators
such that the rotors and stators are compressed together and
thereby create braking torque. The brake system may further include
a second brake actuator including at least one spring operatively
coupled to at least one second piston positioned within a second
chamber such that depressurization of the second chamber causes the
at least one second piston to operatively engage at least one of
the rotors or stators such that the rotors and stators are
compressed together and thereby create braking torque.
[0009] In one embodiment, at least one of the rotors or stators
includes a monolithic piece. In another embodiment, at least one of
the rotors or stators includes carbon-carbon. The plurality of
stators may be arranged in an alternating sequence with the
plurality of rotors.
[0010] In another embodiment, the brake system further includes a
hub configured to be mounted to the shaft for rotation therewith,
wherein the plurality of rotors are configured to be operatively
coupled to the shaft via the hub. Each of the plurality of rotors
may include at least one of a key or a keyway and the hub may
include at least one of the other of a key or a keyway for engaging
the at least one key or keyway of the rotors for causing the
plurality of rotors to rotate with the hub and the shaft.
[0011] In one embodiment, the brake system further includes a
housing configured to be mounted to the frame and fixed against
rotation relative thereto, wherein each of the plurality of stators
includes at least one of a notch or a ridge and the housing
includes at least one of the other of a notch or a ridge for
engaging the at least one notch or ridge of the stators for fixing
the plurality of stators against rotation relative to the
frame.
[0012] In another embodiment, the brake system further includes a
load distribution plate positioned between the at least one first
piston and the series of rotors and stators for providing an even
compression of the pluralities of rotors and stators when the at
least one first piston operatively engages the at least one of the
rotors or stators. In one embodiment, the pluralities of rotors and
stators are configured to be free from oil flow.
[0013] In yet another embodiment, a piece of equipment includes a
frame, a shaft rotatable relative to the frame and a brake system.
The brake system includes a series of rotors and stators, including
a plurality of rotors operatively coupled to the shaft and
rotatable with the shaft relative to the frame, and a plurality of
stators operatively coupled to the frame and fixed against rotation
relative to the frame. The brake system also includes a first brake
actuator including at least one first piston positioned within a
first chamber such that pressurization of the first chamber causes
the at least one first piston to operatively engage at least one of
the rotors or stators such that the rotors and stators are
compressed together and thereby create braking torque for resisting
rotation of the shaft relative to the frame. The brake system may
further include a second brake actuator including at least one
spring operatively coupled to at least one second piston positioned
within a second chamber such that depressurization of the second
chamber causes the at least one second piston to operatively engage
at least one of the rotors or stators such that the rotors and
stators are compressed together and thereby create braking torque
for resisting rotation of the shaft relative to the frame.
[0014] In one embodiment, the shaft is an axle. In another
embodiment, the shaft is a spindle. The piece of equipment may
further include at least one wheel mounted to the shaft and
rotatable therewith.
[0015] In one embodiment, at least one of the rotors or stators
includes a monolithic piece. In another embodiment, at least one of
the rotors or stators includes carbon-carbon. The plurality of
stators may be arranged in an alternating sequence with the
plurality of rotors.
[0016] In still another embodiment, a brake system for a piece of
equipment having a frame includes a series of rotors and stators,
including a plurality of rotors configured to be rotatable relative
to the frame, and a plurality of stators configured to be
operatively coupled to the frame and configured to be fixed against
rotation relative to the frame. The brake system also includes a
first brake actuator including at least one first piston positioned
within a first chamber such that pressurization of the first
chamber causes the at least one first piston to operatively engage
at least one of the rotors or stators such that the rotors and
stators are compressed together and thereby create braking torque.
The brake system may also include a second brake actuator including
at least one spring operatively coupled to at least one second
piston positioned within a second chamber such that
depressurization of the second chamber causes the at least one
second piston to operatively engage at least one of the rotors or
stators such that the rotors and stators are compressed together
and thereby create braking torque.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is a side elevation view of a mine truck including an
exemplary brake system in accordance with the principles of the
present invention.
[0018] FIG. 2 is a detail cross sectional view of the mine truck of
FIG. 1, showing the exemplary brake system coupled to the frame and
rotatable shaft of the mine truck.
[0019] FIG. 3 is an exploded view of the brake system of FIG.
2.
[0020] FIG. 4 is a partial exploded view of the brake system of
FIG. 2, showing the hydraulic fluid pathways of the brake
system.
[0021] FIG. 5 is a partial exploded view of the brake system of
FIG. 2, showing various interlocking features of the brake
system.
[0022] FIG. 6 is a perspective view of the brake system of FIG.
2.
[0023] FIG. 7A is a cross sectional view taken along section line
7A-7A of FIG. 6, showing a first piston of the brake system in a
retracted position.
[0024] FIG. 7B is a cross sectional view similar to FIG. 7A,
showing the first piston in an expanded position.
[0025] FIG. 8A is a cross sectional view taken along section line
8A-8A of FIG. 6, showing a second piston of the brake system in an
expanded position.
[0026] FIG. 8B is a cross sectional view similar to FIG. 8A,
showing the second piston in a retracted position.
DETAILED DESCRIPTION
[0027] Referring now to the drawings, and to FIGS. 1 and 2 in
particular, an off-highway equipment vehicle, such as a mine truck
10 configured as a diesel electric vehicle, includes an exemplary
brake system 12 in accordance with the principles of the present
invention. While a mine truck 10 is shown, the brake system 12 may
be configured for use on any suitable off-highway equipment vehicle
or other piece of equipment, such as a continuous track vehicle.
The illustrated mine truck 10 includes a frame 14, a shaft 16 such
as a front or rear axle or spindle rotatable relative to the frame
14, and at least one wheel 18 mounted to the shaft 16 for rotating
therewith. As set forth in greater detail below, various components
of the brake system 12 are operatively coupled to the frame 14
and/or to the shaft 16 for providing resistance to rotation of the
shaft 16 and wheel 18, and thus to movement of the mine truck 10.
The brake system 12 may provide improved braking performance with
many of the advantages of a wet brake while avoiding many of the
disadvantages of a wet brake. For example, the brake system 12 may
exhibit a low wear rate, and thus a long life, without the
parasitic drag caused by oil in wet brakes and with reduced
complexity, weight, and cost. The features of the brake system 12
are set forth in further detail below to clarify each of these
functional advantages and other benefits provided in this
disclosure.
[0028] Referring now to FIGS. 2 and 3, the brake system 12 includes
a base portion 20, a cage portion 22, a hydraulic separator plate
24, and a cap portion 26 fixedly coupled together to form a housing
and configured to be mounted to the frame 14 of the mine truck 10,
as well as a hub 28 configured to be mounted to the shaft 16. To
that end, the hub 28 includes a central bore 30 having splines 32
for mechanically engaging corresponding splines 34 of the shaft 16
such that the hub 28 may rotate with rotation of the shaft 16.
[0029] The illustrated base portion 20 includes a generally annular
plate 40 and a generally annular platform 42 extending from the
plate 40 toward the cage portion 22 and defining a central bore 44
for receiving the shaft 16 of the mine truck 10. The base portion
20 is configured to be operatively coupled to the frame 14 of the
mine truck 10 so as to be fixed against movement relative to the
frame 14. To that end, the illustrated base portion 20 includes a
plurality of through-bores 46 provided in the plate 40 for
receiving fasteners, such as threaded bolts 48, to couple the base
portion 20 to the frame 14. Notches (not shown) may be provided in
the periphery of the platform 42 for accommodating the heads of the
threaded bolts 48. The illustrated base portion 20 also includes a
plurality of threaded blind bores 50 provided in the platform 42
for threadably receiving fasteners, such as threaded bolts 52, to
couple the cage portion 22 to the base portion 20. As shown, the
platform 42 may include a plurality of air flow slots 54 at or near
its periphery, for reasons discussed below.
[0030] The illustrated cage portion 22 includes a lower ring 60 and
an upper body 62 spaced apart and coupled together by a plurality
of supports 64 separated from each other by openings 66. The upper
body 62 is generally annular and defines a central bore 68 for
alignment with the central bore 44 of the base portion 20 and to
receive the shaft 16 of the mine truck 10. Together, the lower ring
60, upper body 62, and supports 64 define a generally interior
space 70 for receiving the hub 28 and/or other components, which
may be at least partially enclosed on the side adjacent the lower
ring 60 by the platform 42 of the base portion 20. To that end, the
lower ring 60 of the cage portion 22 includes a plurality of
through-bores 72 for receiving the threaded bolts 52 for coupling
with the base portion 20. As shown, a portion of the through-bores
72 extend through the supports 64, and counterbores 74 may be
provided in the supports 64 concentric with such through-bores 72
for receiving the heads of the threaded bolts 52 which couple the
cage portion 22 to the base portion 20. In addition or
alternatively, notches 76 may be provided in the periphery of the
lower ring 60 for accommodating the heads of the threaded bolts 48
which couple the base portion 20 to the frame 14.
[0031] Referring now to FIG. 4, with continuing reference to FIGS.
2 and 3, the upper body 62 of the cage portion 22 includes
pluralities of first and second chambers 80, 82 extending between
first and second surfaces 84, 86 of the upper body 62 such that
each chamber 80, 82 is open to each of the first and second
surfaces 84, 86. In the illustrated cage portion 22, the plurality
of first chambers 80 includes three first chambers 80 and the
plurality of second chambers 82 includes six second chambers 82,
arranged in pairs between the first chambers 80. However, it will
be appreciated that other numbers and/or arrangements of the
chambers 80, 82 may be used. As shown, first and second fluid
bleeder pathways 90, 92 extend along the first surface 84 of the
upper body 62 for bleeding hydraulic fluid from the pluralities of
first and second chambers 80, 82, respectively. The functions and
purposes of the chambers 80, 82 and fluid bleeder pathways 90, 92
are discussed in greater detail below. In any event, the
illustrated cage portion 22 includes a plurality of threaded blind
bores 94 provided in the upper body for threadably receiving
fasteners, such as threaded bolts 96 and/or threaded studs 98, to
couple the separator plate 24 and/or cap portion 26 to the cage
portion 22.
[0032] As shown, the separator plate 24 is generally annular and
defines a central bore 100 for alignment with the central bores 44,
68 of the base and cage portions 20, 22 and to receive the shaft 16
of the mine truck 10. The separator plate 24 includes a plurality
of chamber bores 102 configured for alignment with the plurality of
second chambers 82 of the cage portion 22, and a plurality of fluid
supply openings 104 for alignment with the plurality of first
chambers 80, such that the separator plate 24 partially covers each
of the first chambers 80 and the fluid supply openings 104 allow
hydraulic fluid to enter each of the first chambers 80 from a side
of the separator plate 24 opposite the cage portion 22. The
illustrated separator plate 24 further includes a plurality of
through bores 106 for receiving the threaded bolts 96 and/or
threaded studs 98 which couple the separator plate 24 to the cage
portion 22 and/or cap portion 26.
[0033] When coupled to the upper body 62 of the cage portion 22,
the separator plate 24 bounds the first and second fluid bleeder
pathways 90, 92 in the first surface 84 of the upper body 62 to
generally retain hydraulic fluid therein. As shown, the separator
plate 24 includes fluid bleeder openings 108 for allowing hydraulic
fluid to exit the first and second fluid bleeder pathways 90, 92 to
the side of the separator plate 24 opposite the cage portion
22.
[0034] The illustrated cap portion 26 includes a generally annular
plate 110 having first and second surfaces 112, 114 and pluralities
of first and second towers 116, 118 extending from the second
surface 114 away from the cage portion 22. The plate 110 defines a
central bore 120 for alignment with the central bores 44, 68, 100
of the base portion 20, cage portion 22, and separator plate 24,
and to receive the shaft 16 of the mine truck 10. Pairs of blind
bores 122 extend from the second surface 114 of the plate 110 into
each of the second towers 118 and are configured for alignment with
the chamber bores 102 of the separator plate 24 and the second
chambers 82 of the cage portion 22. As shown, first and second
fluid supply pathways 130, 132 extend along the second surface 114
of the plate 110 for supplying hydraulic fluid to the pluralities
of first and second chambers 80, 82, respectively. First and second
hydraulic fluid inlet ports 140, 142 are provided in one of the
first towers 116 and fluidically communicate with the first and
second fluid supply pathways 130, 132, respectively. Similarly,
first and second hydraulic fluid bleeder ports 144, 146 are
provided in one of the first towers 116 and fluidically communicate
with the first and second fluid bleeder pathways 90, 92,
respectively.
[0035] As shown, the cap portion 26 includes a plurality of through
bores 148 provided in the plate 110 for receiving the threaded
bolts 96 and/or threaded studs 98 which couple the cap portion 26
to the separator plate 24 and/or cage portion 22. When the cap
portion 26 is coupled to the separator plate 24, the separator
plate 24 bounds the first and second fluid supply pathways 130, 132
in the second surface 114 of the plate 110 to generally retain
hydraulic fluid therein. The fluid supply openings 104 in the
separator plate 24 allow fluid to travel from the fluid inlet ports
140, 142 to the corresponding chambers 80, 82.
[0036] Referring now to FIG. 5, with continuing reference to FIGS.
2 and 3, the brake system 12 includes a series or pack 150 of
generally disc-shaped rotors 152 and stators 154 housed within the
interior space 70 of the cage portion 22. The rotors 152 are
operatively coupled to the shaft 16 and configured to rotate with
the shaft 16 relative to the frame 14. To that end, the rotors 152
each include a central bore 160 having a plurality of keys 162
configured to be received by corresponding keyways 164 of the hub
28. When the shaft 16 and hub 28 rotate together, the keyways 164
may mechanically engage the corresponding keys 162, thereby causing
the rotors 152 to rotate with the hub 28 and shaft 16. It will be
appreciated that the rotors 152 may be coupled to the shaft 16 in
various other ways without departing from the scope of the
invention.
[0037] The stators 154 are operatively coupled to the frame 14 and
configured to be fixed against rotation relative to the frame 14.
To that end, the stators 154 each include notches 170 along their
outer peripheries for receiving corresponding ridges 172 of the
cage portion 22, and a central bore 174 sized to clear the hub 28.
In this manner, when the shaft 16 rotates, the engagement between
the ridges 172 and the notches 170 may prevent the stators 154 from
rotating relative to the frame 14, while the hub 28 and/or shaft 16
may rotate freely within the central bore 174. In the embodiment
shown, the ridges 172 are provided on inner surfaces of the
supports 64 of the cage portion 22. It will be appreciated that the
stators 154 may be coupled to the frame 14 in various other ways
without departing from the scope of the invention.
[0038] The rotors 152 and stators 154 are free to move slightly
along the axis of the shaft 16 such that, when the rotors 152 and
stators 154 are spaced apart from each other, the rotors 152 are
permitted to rotate freely with the shaft 16 and such that, when
the rotors 152 and stators 154 are compressed or clamped together,
braking torque may be created by friction generated between the
rotors 152 and stators 154 to thereby resist rotation of the rotors
152. In that regard, each of the rotors 152 and/or stators 154 may
be constructed of a friction material suitable for braking
applications. For example, the rotors 152 and/or stators 154 may
comprise monolithic pieces of carbon fiber reinforcement in a
matrix of carbon, commonly referred to as carbon fiber-reinforced
carbon or carbon-carbon. It will be appreciated that carbon-carbon
may exhibit a low wear rate and thus provide durability to the
rotors 152 and stators 154, and that a monolithic construction may
allow a substantial portion of the thickness of each rotor 152 and
stator 154 to be available as usable material during braking.
However, any other suitable material and/or suitable construction
(e.g., non-monolithic) may be used for the rotors 152 and/or
stators 154. For example, the rotors 152 and/or stators 154 may
include a sintered metallic-based friction material bonded to both
sides of a steel core or manufactured into a monolithic piece. In
one embodiment, the pluralities of rotors 152 and stators 154 are
configured to be free from oil flow during use. In any event, the
braking torque created by compressing the rotors 152 and stators
154 may be transferred from the rotors 152 to the hub 28 via the
keys 162 and keyways 164, and may be transferred from the hub 28 to
the shaft 16 via the splines 32, 34 to resist rotation of the shaft
16 and wheel 18.
[0039] It will be appreciated that substantial heat may be
generated during the creation of braking torque by the rotors 152
and stators 154. The air flow slots 54 in the platform 42 of the
base portion 20 may assist in transferring such away from the brake
system 12. In addition or alternatively, the openings 66 between
the supports 64 of the cage portion 22 may assist in transferring
the heat away from the brake system 12.
[0040] As shown, generally V-shaped flat springs 180 may be
positioned between adjacent stators 154 at or near their
peripheries to bias the stators 154 away from each other and
thereby prevent the stators 154 from inadvertently clamping a rotor
152 therebetween when braking torque is not desired, which would
lead to parasitic drag. For example, the flat springs 180 may be
coupled to peripheral metallic clips 182 positioned over the
stators 154. Such clips 182 may be load-bearing in order to avoid
damaging the stators 154 under loads carried between the stators
154 by the flat springs 180. In the embodiment shown, three rotors
152 and four stators 154 are arranged in an alternating sequence
starting and ending with a stator 154. However, various other
numbers of rotors and stators may be arranged in any suitable
sequence. For example, four rotors and five stators may be arranged
in an alternating sequence. In one embodiment, each front wheel of
the mine truck may be equipped with a brake system having a greater
number of rotors and stators than the brake systems of the rear
wheels due to reduced torque requirements for the rear wheels, such
as when the rear brake systems operate behind a gear box. For
example, the rear brake system may contain three rotors and four
stators, while the front brake system may contain four rotors and
five stators.
[0041] Referring now to FIGS. 6, 7A, and 7B, with continuing
reference to FIG. 3, the brake system 12 includes a service brake
actuator 200 which may be used to compress the rotors 152 and
stators 154 together during operation of the mine truck 10. In the
embodiment shown, the service brake actuator 200 includes three
first pistons 202 positioned within the three first chambers 80 of
the cage portion 22. First fluid inlets and outlets 204, 206 in
fluid communication with the first fluid supply and bleeder
pathways 130, 90, respectively, are provided on a side of each
first piston 202 opposite the rotors 152 and stators 154, such that
pressurization of the first chambers 80 with hydraulic fluid via
the first fluid supply pathway 130 causes the first pistons 202 to
expand from a retracted position (FIG. 7A) toward the rotors 152
and stators 154 to an expanded position (FIG. 7B). While not shown,
it will be appreciated that pressurization of the first chambers 80
may be achieved by opening a valve via a controller, such as a
brake pedal, to allow hydraulic fluid to flow from a reservoir
through the first fluid supply pathway 130 to the first chambers
80. As shown, a gasket 208 may be provided between each first
piston 202 and respective first chamber 80 in order to prevent
hydraulic fluid leakage into the interior space 70 of the cage
portion 22. In any event, when in the expanded position, the first
pistons 202 may operatively engage at least one of the rotors 152
and/or stators 154 to compress or clamp the rotors 152 and stators
154 together against the platform 42 of the base portion 20 to
create braking torque for resisting rotation of the shaft 16.
[0042] In the embodiment shown, a load distribution plate 210 is
positioned between the first pistons 202 and the pack 150 of rotors
152 and stators 154, such that the operative engagement between the
first pistons 202 and the rotor(s) 152 and/or stator(s) 154 is
accomplished via the load distribution plate 210. The load
distribution plate 210 may be fixed against rotation relative to
the frame 14, and may be somewhat similar to a stator 154. In
particular, the load distribution plate 210 may include notches 212
along its outer periphery (FIG. 3) for receiving corresponding
ridges 172 of the cage portion 22, and a central bore 214 sized to
clear the hub 28. In this manner, the load distribution plate 210
may provide generally even compression of the rotors 152 and
stators 154 across their respective surface areas for a consistent
and reliable braking torque. In addition or alternatively, thermal
barrier discs 216 may be coupled to the first pistons 202 via
fasteners, such as threaded bolts 218, in order to insulate the
first pistons 202 and chambers 80 from the heat generated during
the creation of braking torque.
[0043] As shown, pluralities of springs 220 are provided between
each of the first pistons 202 and surfaces of the respective first
chambers 80 on a same side of the first pistons 202 as the rotors
152 and stators 154 in order to bias the first pistons 202 away
from the rotors 152 and stators 154. Thus, a threshold
pressurization of the first chambers 80 may be required to overcome
the bias of the springs 220 in order to expand the first pistons
202 toward the rotors 152 and stators 154. This may prevent the
first pistons 202 from inadvertently compressing the rotors 152 and
stators 154 together, and these springs 220 provide residual
pressure to allow operation of a hydraulic slack adjuster to adjust
piston stroke for ideal application delay based on friction wear.
When the first chambers 80 are depressurized, such as by reducing
or stopping fluid flow in the first fluid supply pathway 130 and
allowing pressure to exit through the first fluid inlet 204, the
first pistons 202 may be urged by the springs 220 away from the
rotors 152 and stators 154, and the flat springs 180 may urge the
stators 154 away from each other to unclamp the rotors 152 and
cease creating braking torque.
[0044] Referring now to FIGS. 8A and 8B, with continuing reference
to FIGS. 3 and 6, the brake system 12 further includes an emergency
or parking brake actuator 230 which may be used to compress the
rotors 152 and stators 154 together during operation of the mine
truck 10, such as in an emergency situation, or when the mine truck
10 is out of use. In one embodiment, the parking brake actuator 230
may include a spring-applied hydraulic-released (SAHR) brake. As
shown, the parking brake actuator 230 includes six second pistons
232 positioned within six corresponding second chambers 82 of the
cage portion 22, and six springs 234 positioned over the second
pistons 232 within blind bores 122 of the three corresponding
towers 118 in order to bias the second pistons 232 toward the
rotors 152 and stators 154. In this manner, the second pistons 232
may operatively engage at least one of the rotors 152 and/or
stators 154 to compress or clamp the rotors 152 and stators 154
together against the platform 42 of the base portion 20 to create
braking torque for resisting rotation of the shaft 16.
[0045] In the embodiment shown, the load distribution plate 210 is
positioned between the second pistons 232 and the series of rotors
152 and stators 154 in a manner similar to that discussed above
with respect to the service brake actuator 200. In addition or
alternatively, thermal barrier discs 236 may be coupled to the
second pistons 232 via fasteners 238 in order to insulate the
second pistons 232 and chambers 82 from the heat generated during
the creation of braking torque.
[0046] Second fluid inlets and outlets 240, 242 in fluid
communication with the second fluid supply and bleeder pathways
132, 92, respectively, are provided on a same side of each second
piston 232 as the rotors 152 and stators 154, such that
pressurization of the second chambers 82 with hydraulic fluid via
the second fluid pathway 132 sufficient to overcome the bias of the
springs 234 causes the second pistons 232 to expand away from the
rotors 152 and stators 154. During normal operation of the mine
truck 10, the second chambers 82 may be pressurized to maintain the
second pistons 232 in the expanded position (FIG. 8A) to prevent
the second pistons 232 from inadvertently compressing the rotors
152 and stators 154 together. When parking the mine truck 10 or
during an emergency situation, the second chambers 82 may be
depressurized, allowing the springs 234 to urge the second pistons
232 toward the rotors 152 and stators 154 to create braking torque
(FIG. 8B). While not shown, it will be appreciated that
depressurization of the second chambers 82 may be achieved by
closing a valve via a controller, such as a parking brake lever, to
slow or prevent hydraulic fluid flow from a reservoir through the
second fluid supply pathway 132 to the second chambers 82. As
shown, gaskets 244 may be provided between each second piston 232
and respective second chamber 82 in order to prevent hydraulic
fluid leakage into the interior space 70 of the cage portion 22. In
addition or alternatively, one or more O-rings 246, 248 may be
provided between each second piston 232 and respective chamber 82
to provide a fluid-tight seal therebetween.
[0047] In the embodiment shown, columns 250 are provided within
each blind bore 122 of the towers 118 and are generally concentric
with the respective springs 234. The outer surfaces of the columns
250 may provide centering for the springs 234 and guide the springs
234 during compression and/or expansion thereof. In addition or
alternatively, the columns 250 may be at least partially hollow,
and the inner surfaces of the columns 250 may guide the second
pistons 232 during retraction and/or expansion thereof. The end
surfaces of the columns 250 proximate to the respective second
pistons 232 may limit the expansion of the second pistons 232 to
stop the second pistons 232 before the springs 234 become
over-compressed and/or damaged.
[0048] Thus, the brake system 12 may provide improved braking
performance with many of the advantages of a wet brake while
avoiding many of the disadvantages of a wet brake. For example, the
brake system 12 may exhibit a low wear rate, and thus a long life.
The absence of oil in the interior space 70 of the cage portion 22
and/or on the rotors 152 and stators 154 avoids the parasitic drag
caused by oil in wet brakes, and further avoids the need for
complex and heavy oil circulation equipment.
[0049] While the present invention has been illustrated by the
description of one or more embodiments thereof, and while the
embodiments have been described in considerable detail, they are
not intended to restrict or in any way limit the scope of the
appended claims to such detail. Additional advantages and
modifications will readily appear to those skilled in the art. The
invention in its broader aspects is therefore not limited to the
specific details, representative apparatus and method and
illustrative examples shown and described. Accordingly, departures
may be made from such details without departing from the scope or
spirit of the general inventive concept.
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