U.S. patent application number 12/348769 was filed with the patent office on 2009-07-09 for suspension system.
This patent application is currently assigned to Oshkosh Corporation. Invention is credited to Brian Anderson, Jesse Gander, Jesse Knoble.
Application Number | 20090174158 12/348769 |
Document ID | / |
Family ID | 36282943 |
Filed Date | 2009-07-09 |
United States Patent
Application |
20090174158 |
Kind Code |
A1 |
Anderson; Brian ; et
al. |
July 9, 2009 |
SUSPENSION SYSTEM
Abstract
A vehicle subassembly includes first and second hydraulic
cylinders each having an upper chamber and a lower chamber. A fluid
circuit is hydraulically connected to the first and second
hydraulic cylinders and includes a valve movable between a first
position where the upper chamber of the first hydraulic cylinder
and the lower chamber of the second hydraulic cylinder are
hydraulically connected and the lower chamber of the first
hydraulic cylinder and the upper chamber of the second cylinder are
hydraulically connected, and a second position where the upper
chamber and the lower chamber of the first hydraulic cylinder are
hydraulically connected and the upper chamber and lower chamber of
the second hydraulic cylinder are hydraulically connected. A
control unit is operable to position the valve in at least one of
the first position and the second position based on an operating
variable of the vehicle.
Inventors: |
Anderson; Brian; (Oshkosh,
WI) ; Knoble; Jesse; (Oshkosh, WI) ; Gander;
Jesse; (Larsen, WI) |
Correspondence
Address: |
FOLEY & LARDNER LLP
777 EAST WISCONSIN AVENUE
MILWAUKEE
WI
53202-5306
US
|
Assignee: |
Oshkosh Corporation
|
Family ID: |
36282943 |
Appl. No.: |
12/348769 |
Filed: |
January 5, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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11068513 |
Feb 28, 2005 |
7472914 |
|
|
12348769 |
|
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Current U.S.
Class: |
280/5.507 ;
280/124.159; 280/124.16; 280/5.514 |
Current CPC
Class: |
B60G 2200/144 20130101;
B60G 2400/52 20130101; B60G 2204/8304 20130101; B60G 21/073
20130101; B60G 21/106 20130101; B60G 2800/984 20130101; B60G
2202/154 20130101; B60G 2204/8102 20130101; B60G 2204/129 20130101;
B60G 2204/128 20130101; B60G 17/0195 20130101; B60G 2600/20
20130101 |
Class at
Publication: |
280/5.507 ;
280/124.16; 152/416; 280/124.159; 280/5.514 |
International
Class: |
B60G 17/033 20060101
B60G017/033; B60G 11/26 20060101 B60G011/26; B60G 17/04 20060101
B60G017/04 |
Claims
1. A subassembly for a vehicle, the subassembly comprising: first
and second hydraulic cylinders each having an upper chamber and a
lower chamber; a fluid circuit hydraulically connected to the first
and second hydraulic cylinders and including a valve movable
between a first position where the upper chamber of the first
hydraulic cylinder and the lower chamber of the second hydraulic
cylinder are hydraulically connected and the lower chamber of the
first hydraulic cylinder and the upper chamber of the second
cylinder are hydraulically connected, and a second position where
the upper chamber and the lower chamber of the first hydraulic
cylinder are hydraulically connected and the upper chamber and
lower chamber of the second hydraulic cylinder are hydraulically
connected; a control unit operable to position the valve in at
least one of the first position and the second position based on an
operating variable of the vehicle.
2. The subassembly of claim 1, wherein the operating variable
comprises a lateral acceleration, and the control unit is operable
to position the flow control device in the first position for a
first lateral acceleration and in the second position for a second
lateral acceleration, wherein the first lateral acceleration is
greater than the second lateral acceleration.
3. The subassembly of claim 1, wherein the operating variable
comprises speed, and the control unit is operable to position the
flow control device in the first position for a first speed and in
the second position for a second speed, wherein the first speed is
greater than the second speed.
4. The subassembly of claim 1, wherein the operating variable
comprises a load, and the control unit is operable to position the
flow control device in the first position for a first load and in
the second position for a second load, wherein the first load is
greater than the second load.
5. The subassembly of claim 1, wherein the operating variable
comprises a turning angle, and the control unit is operable to
position the flow control device in the first position for a first
turning angle and in the second position for a second turning
angle, wherein the first turning angle is greater than the second
turning angle.
6. The subassembly of claim 1, wherein the operating variable
comprises a pressure within the fluid circuit, and the control unit
is operable to position the flow control device in the first
position for a first pressure and in the second position for a
second pressure, wherein the second pressure is greater than the
first pressure.
7. A subassembly for a vehicle, the subassembly comprising: a first
hydraulic cylinder having an upper chamber and a lower chamber; a
second hydraulic cylinder having an upper chamber and a lower
chamber; a fluid circuit hydraulically coupled to the first
hydraulic cylinder and the second hydraulic cylinder and including
a flow control device movable between a first position and a second
position, wherein when the flow control device is in the first
position the upper chamber of the first hydraulic cylinder is
hydraulically coupled to the lower chamber of the second hydraulic
cylinder and the lower chamber of the first hydraulic cylinder is
hydraulically coupled to the upper chamber of the second cylinder,
and wherein when the flow control device is in the second position
the upper chamber of the first hydraulic cylinder is hydraulically
coupled to the lower chamber of the first hydraulic cylinder and
the upper chamber of the second hydraulic cylinder is hydraulically
coupled to the lower chamber of the second hydraulic cylinder; a
control unit operable to position the flow control device in at
least one of the first position and the second position in response
to an operating variable of the vehicle.
8. The subassembly of claim 7, wherein the operating variable of
the vehicle comprises a lateral acceleration of the vehicle, and
the control unit is operable to position the flow control device in
the first position in response to a first lateral acceleration and
in the second position in response to a second lateral
acceleration, wherein the first lateral acceleration is greater
than the second lateral acceleration.
9. The subassembly of claim 7, wherein the operating variable of
the vehicle comprises a speed of the vehicle, and the control unit
is operable to position the flow control device in the first
position in response to a first speed and in the second position in
response to a second speed, wherein the first lateral speed is
greater than the second speed.
10. The subassembly of claim 7, wherein the operating variable of
the vehicle comprises a load carried by the vehicle, and the
control unit is operable to position the flow control device in the
first position in response to a first load and in the second
position in response to a second load, wherein the first load is
greater than the second load.
11. The subassembly of claim 7, wherein the operating variable of
the vehicle comprises a turning angle, and the control unit is
operable to position the flow control device in the first position
in response to a first turning angle and in the second position in
response to a second turning angle, wherein the first turning angle
is greater than the second turning angle.
12. The subassembly of claim 7, wherein the operating variable of
the vehicle comprises a pressure within the fluid circuit, and the
control unit is operable to position the flow control device in the
first position in response to a first pressure and in the second
position in response to a second pressure, wherein the second
pressure is greater than the first pressure.
13. The subassembly of claim 7, wherein the flow control device
comprises a valve.
14. A subassembly for a vehicle comprising: first and second
hydraulic cylinders each having an upper chamber and a lower
chamber; a fluid circuit hydraulically coupled to the first and
second hydraulic cylinders and including a valve movable between a
first position and a second position, wherein when the valve is in
the first position the upper chamber of the first hydraulic
cylinder is hydraulically coupled to the lower chamber of the
second hydraulic cylinder and the lower chamber of the first
hydraulic cylinder is hydraulically coupled to the upper chamber of
the second cylinder, and wherein when the valve is in the second
position the upper chamber of the first hydraulic cylinder is
hydraulically coupled to the lower chamber of the first hydraulic
cylinder and the upper chamber of the second hydraulic cylinder is
hydraulically coupled to the lower chamber of the second hydraulic
cylinder; a central tire inflation system having a first setting
representative of a first operation mode and a second setting
representative of a second operation mode; a control unit operable
to move the valve to the first position when the central tire
inflation system is in the first setting and to move the valve to
the second position when the central tire inflation system is in
the second setting.
15. The subassembly for a vehicle of claim 14, wherein the first
operation mode comprises on-road operation and the second operation
mode comprises off-road operation.
16. The subassembly for a vehicle of claim 14, further comprising
at least one accumulator hydraulically coupled to the fluid
circuit.
17. The subassembly for a vehicle of claim 14, further comprising a
first accumulator hydraulically coupled to the fluid circuit
between the upper chamber of the first hydraulic cylinder and the
lower chamber of the second hydraulic cylinder, and a second
accumulator hydraulically coupled to the circuit between the lower
chamber of the first hydraulic cylinder and the upper chamber of
the second hydraulic cylinder.
18. The subassembly for a vehicle of claim 14, wherein the first
and second hydraulic cylinders are hydro-pneumatic springs.
19. The subassembly for a vehicle of claim 14, wherein the vehicle
has a first ride height when the fluid circuit has a first volume
of fluid and wherein the vehicle has a second ride height different
than the first ride height when the fluid circuit has a second
volume of fluid different than the first volume of fluid.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present Application claims the benefit of priority as a
continuation under 35 U.S.C. .sctn. 120 of co-pending U.S. patent
application Ser. No. 11/068,513, titled "Suspension System" filed
on Feb. 28, 2005, the disclosure of which is hereby incorporated by
reference in its entirety.
BACKGROUND
[0002] Suspension systems in which a shock absorber on the right
side of the vehicle is coupled or cross-linked to a corresponding
shock absorber on the left side of the vehicle are known. Such
cross-linking of the shock absorbers on the left and right sides of
the vehicle (e.g., coupling the upper chamber of each shock
absorber to the lower chamber of the corresponding shock absorber
on the other side of the vehicle) generally provides greater roll
resistance than standard suspension systems that utilize an
anti-roll bar in combination with right and left side shock
absorbers that are not coupled to one another and that operate
independently of one another. However, in such cross-linked
suspension systems, the operation of the shock absorber on the left
side of the vehicle is affected by the operation of the shock
absorber on the right side of the vehicle. Accordingly, the ability
of the wheel on the right side of the vehicle (which corresponds to
the shock absorber on the right side of the vehicle) to travel up
and down relative to the wheel on the left side of the vehicle
(which corresponds to the shock absorber on the left side of the
vehicle) is limited. Thus, while the cross-linked configuration may
be beneficial in some situations, such as when the vehicle is
turning a corner on the highway or on a relatively smooth surface,
it may be detrimental in other situations, such as when the vehicle
is traveling off-road or is otherwise traveling over rough or bumpy
terrain. On relatively smooth road surfaces, the independent
movement of the right and left wheels has less effect on ride
quality because the magnitude of the relative up and down movement
between the left and right wheels is likely to be small. When the
vehicle is traveling off road or on rough or bumpy terrain, the
magnitude of the relative up and down movement between the left and
right wheels is likely to be relatively large. In such a situation,
it is more desirable to allow the right and left side shock
absorbers to operate independently of one another, so that each
shock absorber is able to expand or contract to the extent needed
to accommodate the unique bumps, dips, etc. that may be encountered
by the left wheel and by the right wheel.
[0003] Some of the suspension systems that utilize cross-linked
shock absorbers are configured so that the suspension system can be
alternated between a cross-linked configuration and a straight
configuration (e.g., where the upper chamber of each shock absorber
is coupled to its own lower chamber rather than the lower chamber
of the shock absorber on the opposite side of the vehicle). Many of
these systems utilize some type of acceleration sensor that
actuates the system between the straight configuration and the
cross-linked configuration based on the lateral acceleration
experienced by the vehicle. Although these suspension systems avoid
some of the problems of a suspension system that is either always
in the straight configuration or always in the cross-linked
configuration, they introduce other potential problems. For
example, many of the systems utilizing acceleration sensors do not
give the occupant any control over when the system is in a
cross-linked configuration or a straight configuration. Moreover,
with these systems, the sensor may cause the suspension system to
convert to the cross-linked configuration when it may not be
desirable to do so, such as when the vehicle accelerates laterally
as a result of one wheel hitting a bump, for example. Once the
system converts to the cross-linked configuration (such as when the
vehicle is traveling over the bump), the ability of the wheels to
move independently is significantly reduced, which affects ride
quality.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] FIG. 1 is a front view of a vehicle having a suspension
system according to one exemplary embodiment, where a portion of
the suspension system is shown in cross-section.
[0005] FIG. 2 is a perspective view of a portion of the suspension
system according to another exemplary embodiment.
[0006] FIG. 3 is a schematic illustration of a portion of the
suspension system and the central tire inflation system according
to an exemplary embodiment.
[0007] FIG. 4 is a schematic illustration of a portion of the
suspension system according to another exemplary embodiment.
[0008] FIG. 5 is a schematic illustration of a portion of the
suspension system according to another exemplary embodiment.
[0009] FIG. 6 is a schematic illustration of a portion of the
suspension system according to another exemplary embodiment.
DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS
[0010] Before providing the description of the exemplary and
alternative embodiments of the suspension system, it should be
noted that references to "upper," "lower," "left," "right,"
"front," and "rear" in this description are merely used to identify
the various elements as they are oriented in the figures. These
terms are not meant to limit the element which they describe, as
the various elements may be oriented or arranged differently in
various suspension systems.
[0011] For purposes of this disclosure, the term "coupled" means
the joining of two members directly or indirectly to one another.
Such joining may be stationary in nature or moveable in nature
and/or such joining may allow for the flow of fluids, electricity,
electrical signals, or other types of signals or communication
between the two members. Such joining may be achieved with the two
members or the two members and any additional intermediate members
being integrally formed as a single unitary body with one another
or with the two members or the two members and any additional
intermediate members being attached to one another. Such joining
may be permanent in nature or alternatively may be removable or
releasable in nature.
[0012] Referring now to FIG. 1, a vehicle 10 according to one
exemplary embodiment includes a body portion 12, a chassis 14, and
a central tire inflation system 17.
[0013] Body portion 12 is coupled to chassis 14 and generally
includes an enclosed area or cab region that is configured to
accommodate passengers and which generally serves as the location
where an operator of vehicle 10 drives and controls at least some
of the various functions of vehicle 10. Body portion 12 may also
include other portions or structures that facilitate particular
uses of vehicle 10. According to various alternative and exemplary
embodiments, the body portion may take one of a variety of
different configurations that is suitable for one or more of a
variety of different applications. For example, the body portion
may be that of dump truck and include a tilting bed or bucket; it
may be that of a concrete truck and include a concrete mixing drum;
it may be that of a crane and include a boom or a hoist; it may be
that of a fire truck and be configured to accommodate various fire
related equipment such as ladders, water tanks, etc.; it may be
that of a emergency response vehicle and be configured to include
various medical equipment, crowd control equipment, explosion
containment equipment, etc.; it may be that of a military vehicle
and be configured to transport, house, or carry a variety objects;
or it may be the body portion of a variety of other types of
vehicles (heavy duty, medium duty, and light duty) and take one of
a wide variety of configurations.
[0014] Base structure or chassis 14 generally includes the
structure that substantially supports body portion 12 as well as
the mechanisms that propel vehicle 10. According to one exemplary
embodiment, chassis 14 includes a frame 18, a power source 20, a
drivetrain 22, wheel assemblies 24, and a suspension system 16.
[0015] Frame 18 is a substantially rigid structure that provides
vehicle 10 with the structural support and rigidity needed to
support body portion 12 and any cargo vehicle 10 may be carrying.
According to one exemplary embodiment, frame 18 is that of a
heavy-duty vehicle, such as a dump truck, a cement mixing truck, a
fire truck, a military vehicle, etc. According to various
alternative and exemplary embodiments, the frame may take one of a
variety of different configurations depending on the type of
vehicle in which the frame is used. For example, the frame of a
heavy duty vehicle, such as a concrete mixing truck or a dump
truck, may have a different configuration than the frame portion of
a passenger vehicle, such as a common four passenger sedan, due to
the different uses and characteristics of the vehicles.
[0016] Power source 20 is coupled to frame 18 and generally
comprises a source of rotational mechanical energy which is derived
from a stored energy source. Examples include, but are not limited
to, an internal combustion gas-powered engine, a diesel engine, a
turbine, a fuel cell driven motor, an electric motor or any other
type of motor capable of providing mechanical energy.
[0017] Drivetrain 22 is coupled between power source 20 and wheel
assemblies 24 and transfers power (or movement) from power source
20 to wheel assemblies 24 to propel vehicle 10 in a forward or
rearward (or other) direction. According to various alternative and
exemplary embodiments, the drivetrain may include a transmission, a
wheel end reduction unit, and/or a series of motion transferring
devices such as drive shafts, joints, differentials, etc. that are
coupled together to transfer the torque or power provided by power
source 20 to wheel assemblies 24.
[0018] Wheel assemblies 24 are coupled to drivetrain 22 and
generally serve as the members that engage the ground or surface
upon which vehicle 10 is located. Drivetrain 22 causes at least
some of wheel assemblies 24 to spin or rotate which, due to the
friction between the ground and wheel assemblies 24, imparts
translational movement to vehicle 10. Each wheel assembly 24
generally includes a wheel or hub portion 31 that is coupled to
drivetrain 22 and a tire portion 33 that substantially surrounds
wheel portion 31. Tire portion 33 is generally inflated with air
and serves as a shock absorbing device as well as a friction device
that restricts the ability of wheel portion 31 to rotate without a
corresponding translational propulsion of vehicle 10. For purposes
of referring to a particular wheel assembly in the following
discussion, the left front wheel assembly will be referred to as
wheel assembly 24a, the right front wheel assembly will be referred
to as wheel assembly 24b, the left rear wheel assembly will be
referred to as wheel assembly 24c, and the right rear wheel
assembly will be referred to as wheel assembly 24d.
[0019] Suspension system 16 is a system of components that couple
wheel assemblies 24a, 24b, 24c, and 24d to frame 18 in a manner
that limits, controls, or restrains the manner in which wheel
assemblies 24a, 24b, 24c, and 24d are permitted to move relative to
frame 18 and in a manner that generally supports frame 18 above
wheel assemblies 24a, 24b, 24c, and 24d. According to one exemplary
embodiment, suspension system 16 includes a front portion 21 that
corresponds to front wheel assemblies 24a and 24b, a rear portion
23 that corresponds to rear wheel assemblies 24c and 24d, and a
hydraulic system 25 that is coupled to front portion 21 and rear
portion 23 of suspension system 16.
[0020] According to one exemplary embodiment illustrated in FIG. 2,
front portion 21 of suspension system 16 is of the "independent"
suspension configuration (e.g., front wheel assemblies 24a and 24b
are not coupled to a single rigid axle and are permitted to move
independently of one another) and includes a lower control arm 26,
an upper control arm 28, a hub assembly 30, and a cylinder assembly
32 on each side of vehicle 10 to correspond with each of the front
wheel assemblies 24a and 24b.
[0021] Lower control arm 26 and upper control arm 28 generally
control, limit, or restrict, to a certain extent, the movement of
hub assembly 30 (and therefore wheel assemblies 24a and 24b)
relative to frame 18. Lower control arm 26 and upper control arm 28
are each coupled to a portion of frame 18, with upper control arm
28 being located generally above and parallel to lower control arm
26. Lower control arm 26 and upper control arm 28 each have a first
end that is pivotally coupled to a portion of frame 18 and a distal
end that is coupled to opposite sides of hub assembly 30, and
generally allow hub assembly 30 to translate up and down in
response to varying road conditions. According to various
alternative and exemplary embodiments, the portion of the frame to
which the lower and upper controls arms are coupled, the upper
control arm, and/or the lower control arm may take one of a variety
of different shapes, sizes, and configurations depending upon the
characteristics of the vehicle in which suspension system 16 is
incorporated and the configuration of suspension system 16.
[0022] Hub assembly 30 is coupled to lower and upper control arms
26 and 28 and generally includes certain components of the brake
system of the vehicle as well as the structure or hub to which
wheel portion 31 of wheel assembly 24a or 24b is mounted. Hub
assembly 30 may also be coupled to a portion of drivetrain 22
(e.g., in a front wheel drive or four wheel drive vehicle). In
addition to transferring the movement or torque provided by
drivetrain 22 to wheel assemblies 24a and 24b in certain vehicles,
hub assembly 30 generally transfers the movement of wheel
assemblies 24a and 24b to the other components of suspension system
16 (e.g., lower and upper control arms 26 and 28, cylinder assembly
32, etc.). According to various exemplary and alternative
embodiments, the hub assembly may include one or more of a variety
of different components and may take one of a variety of different
configurations.
[0023] Cylinder assembly 32 (e.g., shock, strut,
hydraulic-pneumatic spring, fluid spring, suspension member, etc.)
extends between lower control arm 26 and frame 18 and generally
controls, limits, and/or dampens the movement of lower control arm
26 relative to frame portion 18. Cylinder assembly 32 includes a
cylinder 34, a joint 36, and a mounting apparatus 38.
[0024] Referring again to FIG. 1, cylinder 34 may be any one of a
variety of different cylinders or suspension members, including
those that are commercially available from a variety of different
sources. For example, the cylinder may be a conventional shock
absorber or strut or other type of hydraulic and/or pneumatic
cylinder. According to one exemplary embodiment, cylinder 34 is a
cylinder that has the characteristics of both a spring (similar to
those used in conventional suspension systems) and a shock. One
example of such a cylinder is a hydro-pneumatic spring that is
modified to include a damping valve. According to one exemplary
embodiment, cylinder 34 includes a tube 40, a piston 42, a piston
rod 44, and a cap 46 that each share a longitudinal axis 45. Tube
40 is a generally cylindrical tube having an open end and a closed
end. Piston 42 is inserted into the open end of tube 40 and is
generally configured to slide along the inside of tube 40. Piston
42 seals against the inside diameter of tube 40 (through the use of
a seal, such as an o-ring or other suitable seal) and generally
forms two separate chambers within tube 40: an upper chamber 48
formed between the closed end of tube 40 and piston 42 and a lower
chamber 50 formed between the open end of tube 40 (which is covered
by cap 46) and piston 42. Piston rod 44 is coupled to piston 42 and
extends through the open end of tube 40 and through cap 46. As
piston 42 slides or moves along the length of tube 40, piston rod
44 moves into and out of the open end of tube 40. Cap 46 is coupled
to the open end of tube 40 and includes an aperture through which
piston rod 44 extends. Cap 46 includes sealing members, such as
o-rings or other suitable seals, that allow cap 46 to form seals
against both tube 40 as well as piston rod 44. The seal formed with
piston rod 44 is configured to allow piston rod 44 to slide in and
out of tube 40 without the contents (particularly the highly
pressurized contents) of lower chamber 50 leaking out between
piston rod 44 and cap 46. The overall length of cylinder 34 changes
as piston rod 44 moves into and out of tube 40 in response to the
application of a force, such as a force exerted by hydraulic fluid
within the cylinder 34 or a force exerted by an element coupled to
cylinder 34. According to various exemplary embodiments, the ratio
of the area of piston 42 that faces lower chamber 50 and that is
not covered by piston rod 44 (e.g., the area of piston 42 upon
which the fluid within lower chamber 50 acts) to the area of piston
42 that faces upper chamber 48 is between 0:1 and 1:1, more
particularly between 1:2 and 1:4.
[0025] For purposes of referring to a particular cylinder in the
following discussion, the cylinder corresponding to wheel assembly
24a will be referred to as cylinder 34a, the cylinder corresponding
to wheel assembly 24b will be referred to as cylinder 34b, the
cylinder corresponding to wheel assembly 24c will be referred to as
cylinder 34c, and the cylinder corresponding to wheel assembly 24d
will be referred to as cylinder 34d.
[0026] Referring again to FIG. 2, joint 36 is a member or assembly
that serves to couple cylinder 34 to lower control arm 26 in a
manner that allows cylinder 34 and lower control arm 26 to rotate
or pivot relative to one another as suspension system 16 operates.
One example of a joint is described in copending PCT Application
Serial No. PCT/US2004/028759, filed on Sep. 3, 2004, by Knoble et
al., entitled JOINT, the full disclosure of which is hereby
incorporated by reference herein. According to various alternative
and exemplary embodiments, the joint may take one of a variety of
different shapes, sizes, and configurations.
[0027] Mounting apparatus 38 is a member or assembly that serves to
couple cylinder 34 to a portion of frame 18 in a manner that allows
cylinder 34 to rotate, pivot, or articulate relative to frame 18 as
suspension system 16 operates. One example of a mounting apparatus
is described in copending U.S. patent application Ser. No.
10/933,809, filed on Sep. 3, 2004, by Knoble et al., entitled
MOUNTING APPARATUS, the full disclosure of which is hereby
incorporated by reference herein. According to various alternative
and exemplary embodiments, the mounting apparatus may take one of a
variety of different shapes, sizes, and configurations.
[0028] According to one exemplary embodiment, rear portion 23 of
suspension system 16 is also of the "independent" type and is
configured in much the same way as front portion 23. Although the
control arms, the hubs, and the cylinder assemblies of the rear
portion may have different sizes, shapes, and/or configuration than
those of front portion 21, they operate in the same general manner.
Thus, a further description of the components of rear portion 23
will not be provided. According to one exemplary embodiment,
cylinders 34c and 34d of rear portion 23 are identical to cylinders
34a and 34b of front portion 21. According to various alternative
and exemplary embodiments, the cylinders or other components of the
rear portion of the suspension system may be different sizes and
shapes and may be configured differently than the corresponding
cylinders or components of the front portion of the suspension
system. According to another alternative embodiment, the rear
portion of the suspension system may be of the "dependent" type
(e.g., where rear wheel assemblies 24c and 24d are connected to a
single, rigid axle that prevents them from moving independently of
each other) and may be adapted to suit one or more rigid axles. For
example, the rear portion may include different components that
allow the cylinders to be coupled between the axle and the frame of
the vehicle.
[0029] Suspension system 16 may take one of a variety of different
configurations. For example, front portion 21 of suspension system
16 may be configured differently than rear portion 23 of suspension
system 16, or front portion 21 and rear portion 23 may have the
same configuration. According to various alternative and exemplary
embodiments, the front and rear portions of the suspension system
may both be "dependent," or the rear portion of the suspension
system may be "independent" while the front portion of the
suspension system may be "dependent."
[0030] According to other alternative and exemplary embodiments,
the vehicle may have two front wheel assemblies, four front wheel
assemblies, or any other number of front wheel assemblies that may
or may not be coupled together by one or more single, rigid axles,
and a portion of the suspension system may be provided to
correspond to each front wheel assembly, each pair of front wheel
assemblies, or only a portion of the front wheel assemblies.
According to other various alternative and exemplary embodiments,
the vehicle may have two rear wheel assemblies, four rear wheel
assemblies, eight rear wheel assemblies, or any other number of
rear wheel assemblies that may or may not be coupled together by
one or more single, rigid axles, and a portion of the suspension
system may be provided to correspond to each rear wheel assembly,
each pair of rear wheel assemblies, or only a portion of the rear
wheel assemblies.
[0031] The portion of vehicle 10 that is supported or held up by
cylinders 34a, 34b, 34c, and 34d of suspension system 16, or the
weight of such portion of vehicle 10 (e.g., frame 18, power source
20, drivetrain 22, and body portion 12), is commonly referred to as
the "sprung portion" or the "sprung weight" of vehicle 10. On the
other hand, the portion of vehicle 10 that is not supported or held
up by cylinders 34a, 34b, 34c, and 34d of suspension system 16, or
the weight of such portion of vehicle 10 (e.g., most of the
components of suspension system 16 and wheel assemblies 24a, 24b,
24c, and 24d), is commonly referred to as the "unsprung portion" or
the "unsprung weight" of vehicle 10.
[0032] Referring now to FIGS. 1 and 3, hydraulic system 25 is a
system of fluid lines and other components, such as accumulators,
valves, manifolds, reservoirs, pumps, etc., that are hydraulically
coupled to cylinders 34a, 34b, 34c, and 34d and that serve to
hydraulically couple each of cylinders 34a, 34b, 34c, and 34d to
one or more of the other cylinders 34a, 34b, 34c, and 34d.
According to various exemplary embodiments, hydraulic system 25
includes fluid lines 56a, 56b, 58a, 58b, 60a, 60b, 62a, and 62b, a
valve system 64, one or more accumulators 66, and a control unit 68
that may be arranged in a plurality of different
configurations.
[0033] In each configuration, the fluid lines of each particular
cylinder couple the respective cylinders to the valve system.
Specifically, fluid line 56a hydraulically couples upper chamber 48
of cylinder 34a to valve system 64, fluid line 56b hydraulically
couples lower chamber 50 of cylinder 34a to valve system 64, fluid
line 58a hydraulically couples upper chamber 48 of cylinder 34b to
valve system 64, fluid line 58b hydraulically couples lower chamber
50 of cylinder 34b to valve system 64, fluid line 60a hydraulically
couples upper chamber 48 of cylinder 34c to valve system 64, fluid
line 60b hydraulically couples lower chamber 50 of cylinder 34c to
valve system 64, fluid line 62a hydraulically couples upper chamber
48 of cylinder 34d to valve system 64, and fluid line 62b
hydraulically couples lower chamber 50 of cylinder 34d to valve
system 64.
[0034] Valve system 64 (e.g., manifold, valve arrangement, etc.) is
a system or arrangement of valves that selectively couple one or
more of fluid lines 56a, 56b, 58a, 58b, 60a, 60b, 62a, and 62b to
one another based on the position of the individual valves within
valve system 64. By controlling the individual valves within valve
system 64, the flow of hydraulic fluid (or other fluids or
substances used in the hydraulic system) may be selectively
directed between upper and lower chambers 48 and 50 of cylinders
34a, 34b, 34c, and 34d. How the flow of hydraulic fluid is directed
within hydraulic system 25 affects how cylinders 34a, 34b, 34c, and
34d will operate, and therefore how suspension system 16 will
perform.
[0035] Accumulators 66 are generally coupled to one or more of
fluid lines 56a, 56b, 58a, 58b, 60a, 60b, 62a, and 62b and are
intended to store hydraulic fluid, to maintain the pressure of the
hydraulic fluid, and/or to apply pressure to the hydraulic fluid.
According to one exemplary embodiment, accumulator 66 is a piston
style accumulator and includes an enclosed, cylindrical housing and
a piston that is disposed within the housing and configured to
divide the housing into two separate chambers. One of the chambers
is filled with a compressible gas while the other is filled with
hydraulic fluid. As the pressure (or volume) of the hydraulic fluid
changes, the piston slides within the housing until it reaches a
point where the pressure of the gas is equal to the pressure of the
hydraulic fluid. When the fluid pressure decreases, the piston
slides within the housing to increase the volume of the gas chamber
until the pressure of the gas is substantially equal to the fluid
pressure, which forces fluid out of the chamber. When the fluid
pressure increases, the piston slides within the housing to
decrease the volume of the gas chamber until the pressure of the
gas is substantially equal to the fluid pressure, which allows more
fluid to enter the chamber. According to another exemplary
embodiment, accumulator 66 includes a chamber or housing that forms
an internal volume. A generally flexible bladder that is filed with
a compressible gas (or a diaphragm separating a portion of the
chamber that is filled with a compressible gas) is disposed within
and occupies at least a portion of the volume of the chamber. The
bladder is configured to expand and contract as fluid enters and
leaves the chamber. The bladder generally will expand and contract
until the pressure of the gas within the bladder equals the
pressure of the fluid within the chamber. According to various
alternative and exemplary embodiments, each accumulator may take
one of a variety of different forms and may utilize various
springs, weights, compressed gases, or other potential energy
sources.
[0036] Control unit 68 (e.g., electronic control unit, controller,
computer, microcontroller, control module, etc.) is an electronic
device (or multiple electronic devices coupled together) that
monitors or measures the value of a variable quantity or condition
and that sends signals to, or controls the operation of, valve(s)
64 of hydraulic system 25 based on the value of the variable
quantity or condition. According to one exemplary embodiment,
control unit 68 monitors or measures the condition or state of
central tire inflation system 17 and controls the operation of
valve(s) 64 based on the state of central tire inflation system 17.
Thus, when control unit 68 detects that central tire inflation
system 17 is in a particular state, control unit 68 may cause
valve(s) 64 to move into the cross-linked configuration (described
below). When control unit 68 detects that the state of central tire
inflation system 17 has changed to a different state, control unit
68 may cause valve(s) 64 to move into the straight plumbed
configuration (described below).
[0037] According to various alternative and exemplary embodiments,
the control unit may monitor or measure one of a variety of
different variables or conditions, and may control the operation of
valve(s) 64 (or other portions of hydraulic system 25, such as a
pump or other valve arrangements) based on one or more different
variables such as the load carried by the vehicle, the speed of the
vehicle, the turning angle of the front wheel assemblies, the
lateral acceleration of the vehicle, the ride height of the
vehicle, the pressure of fluid within the hydraulic system or
particular portions of the hydraulic system, etc. According to
other various alternative and exemplary embodiments, the control
unit may take one of a variety of different configurations, and may
control or send signals to, receive signals from, or monitor, one
or more of a variety of different components of vehicle 10.
According to still other various alternative and exemplary
embodiments, the control unit may or may not be programmable.
[0038] According to various alternative and exemplary embodiments,
the components of hydraulic system 25 may be arranged in a variety
of different configurations depending on the desired performance of
suspension system 16. Some of these configurations are described
below.
[0039] According to a first exemplary embodiment illustrated
schematically in FIG. 3, hydraulic system 25 includes two
substantially independent subsystems, a subsystem 52 that
hydraulically couples cylinders 34a and 34b of front portion 21 of
suspension system 16 and a subsystem 54 that hydraulically couples
cylinders 34c and 34d of rear portion 23 of suspension system
16.
[0040] In subsystem 52, fluid lines 56a and 56b hydraulically
couple upper chamber 48 and lower chamber 50 of cylinder 34a,
respectively, to a valve designated as valve 64a, while fluid lines
58a and 58b hydraulically couple upper chamber 48 and lower chamber
50 of cylinder 34b, respectively, to valve 64a. An accumulator 66a
is hydraulically coupled to fluid line 56b and an accumulator 66b
is hydraulically coupled to fluid line 58b. Valve 64a is configured
to be actuated between two different positions. In the first
position, referred to as the "cross-plumbed position" or
"cross-linked position," valve 64a hydraulically couples fluid line
56a to fluid line 58b (e.g., upper chamber 48 of cylinder 34a is
hydraulically coupled to lower chamber 50 of cylinder 34b) and
hydraulically couples fluid line 56b to fluid line 58a (e.g., lower
chamber 50 of cylinder 34a is hydraulically coupled to upper
chamber 48 of cylinder 34b). In the second position, referred to as
the "straight-plumbed position," valve 64a hydraulically couples
fluid line 56a to fluid line 56b (e.g., upper chamber 48 of
cylinder 34a is coupled to lower chamber 50 of the same cylinder)
and hydraulically couples fluid line 58a to fluid line 58b (e.g.,
upper chamber 48 of cylinder 34b is coupled to lower chamber 50 of
the same cylinder).
[0041] Subsystem 54 is configured in the same general manner as
subsystem 52. In subsystem 54, fluid lines 60a and 60b
hydraulically couple upper chamber 48 and lower chamber 50 of
cylinder 34c, respectively, to a valve designated as valve 64b,
while fluid lines 62a and 62b hydraulically couple upper chamber 48
and lower chamber 50 of cylinder 34d, respectively, to valve 64b.
An accumulator 66c is hydraulically coupled to fluid line 60b and
an accumulator 66d is hydraulically coupled to fluid line 62b. Like
valve 64a, valve 64b is configured to be actuated between a
cross-plumbed position and a straight plumbed position. In the
cross-plumbed position, valve 64b hydraulically couples fluid line
60a to fluid line 62b (e.g., upper chamber 48 of cylinder 34c is
hydraulically coupled to lower chamber 50 of cylinder 34d) and
hydraulically couples fluid line 60b to fluid line 62a (e.g., lower
chamber 50 of cylinder 34c is hydraulically coupled to upper
chamber 48 of cylinder 34d). In the straight-plumbed position,
valve 64b hydraulically couples fluid line 60a to fluid line 60b
(e.g., upper chamber 48 of cylinder 34c is coupled to lower chamber
50 of the same cylinder) and hydraulically couples fluid line 62a
to fluid line 62b (e.g., upper chamber 48 of cylinder 34d is
coupled to lower chamber 50 of the same cylinder).
[0042] The ability to move subsystems 52 and 54 of hydraulic system
25 between a cross-plumbed state and a straight plumbed state
allows suspension system 16 to be adjusted to the configuration
that is most suitable for the particular situation encountered by
vehicle 10. When subsystems 52 and 54 are in the straight-plumbed
position, upper chamber 48 of each cylinder 34a, 34b, 34c, and 34d
is hydraulically coupled to lower chamber 50 of the same cylinder.
Accordingly, each of cylinders 34a, 34b, 34c, and 34d operate
substantially independent of one another. The independent operation
of cylinder 34a, 34b, 34c, and 34d is generally desirable when
vehicle 10 is traveling over relatively rough or bumpy terrain,
such as on unpaved roads or on other off road terrain, because each
of wheel assemblies 24a, 24b, 24c, and 24d will be encountering a
unique series of bumps, dips, etc. that will cause each of wheel
assemblies 24a, 24b, 24c, and 24d to move up and down at different
times and at different magnitudes. The independent operation of
cylinders 34a, 34b, 34c, and 34d helps to increase the total
contact wheel assemblies 24a, 24b, 24c, and 24d have with the
ground at any one time and also generally helps to improve the ride
quality of vehicle 10 in rough or bumpy conditions.
[0043] When subsystems 52 and 54 are in the cross-plumbed position,
upper chamber 48 of cylinders 34a and 34c are hydraulically coupled
to the respective lower chambers 50 of the corresponding cylinders
34b and 34d, and the lower chambers 50 of cylinders 34a and 34c are
hydraulically coupled to the respective upper chambers 48 of
cylinders 34b and 34d. Accordingly, the operation of each cylinder
on the left side of the vehicle (cylinders 34a and 34c) is linked
to the operation of the respective cylinders on the right side of
the vehicle (cylinders 34b and 34d). In this configuration,
suspension system 16 tends to improve the cornering and
maneuverability of vehicle 10 when it is traveling at higher speeds
on a relatively smooth roadway, such as a highway or interstate.
Such improvement is the result, at least in part, of the tendency
of suspension system 16 to resist the roll of body portion 12 as
vehicle 10 changes direction, such as when it goes around a curve
or bend in the road. In this situation, allowing for the completely
independent movement of wheel assemblies 24a, 24b, 24c, and 24d is
less important because wheel assemblies 24a, 24b, 24c, and 24d move
up and down in the same general manner due to the relatively smooth
surface over which they are traveling.
[0044] The tendency of suspension system 16 to resist roll when in
the cross-plumbed configuration derives from the interaction of
cylinders 34a and 34c with cylinders 34b and 34d and the
configuration of hydraulic system 25. For example, in connection
with subsystem 52, as vehicle 10 turns left, body portion 12 and
frame 18 tend to lean or roll towards the right side of vehicle 10
due to centrifugal force. This leaning or rolling of frame 18 and
body portion 12 applies compressive forces to cylinder 34b and
tensile forces to cylinder 34a. The compressive forces applied to
cylinder 34b tend to urge piston rod 44 further into tube 40, which
reduces the volume of upper chamber 48 of cylinder 34b and pushes
fluid out of upper chamber 48. At the same time, the tensile forces
applied to cylinder 34a tend to urge piston rod 44 out of tube 40,
which reduces the volume of lower chamber 50 of cylinder 34a and
pushes fluid out of lower chamber 50. Because upper chamber 48 of
cylinder 34b and lower chamber 50 of cylinder 34a are hydraulically
coupled together (through fluid lines 56b and 58a, and valve 64a),
the fluid displaced from upper chamber 48 of cylinder 34b and from
lower chamber 50 of cylinder 34a moves into accumulator 66a. As
fluid moves into accumulator 66a, the fluid compresses the
gas-filled chamber of accumulator 66a (or otherwise acts on the
potential energy device or apparatus utilized by the accumulator),
which increases the pressure of the fluid in upper chamber 48 of
cylinder 34b, lower chamber 50 of cylinder 34a, fluid line 56b,
fluid line 58a, and accumulator 66a. This increase in the pressure
of the fluid in upper chamber 48 of cylinder 34b and lower chamber
50 of cylinder 34a occurs shortly after frame 18 starts to roll and
resists any further movement of piston rod 44 into cylinder 34b and
piston rod 44 out of cylinder 34a, and therefore resists any
further roll of frame 18 toward the right side of vehicle 10.
[0045] When upper chamber 48 of cylinder 34b and lower chamber 50
of cylinder 34a begin to decrease in size, the opposite chambers,
lower chamber 50 of cylinder 34b and upper chamber 48 of cylinder
34a, begin to increase in size. This increase in volume allows
fluid that was formerly stored in accumulator 66b to travel to
lower chamber 50 of cylinder 34b and upper chamber 48 of cylinder
34a. As the volume of the hydraulic circuit formed by lower chamber
50 of cylinder 34b, upper chamber 48 of cylinder 34a, accumulator
66b, fluid lines 56a and 58b, and valve 64a increases due to the
movement of piston rods 44, the fluid exists accumulator 66b, which
allows the gas-filled chamber (or other potential energy device or
apparatus) in accumulator 66b to expand, which in turn, reduces the
pressure within the hydraulic circuit.
[0046] According to one exemplary embodiment subsystem 52 and 54
are always in the same configuration such that both subsystems
switch between the cross-linked configuration and the straight
plumbed configuration at the same time. According to various
alternative and exemplary embodiments, one of subsystems 52 and 54
may be in the cross-linked configuration while the other is in the
straight plumbed configuration and they may switch between the
cross-linked configuration and the straight plumbed configurations
at the same time or at different times.
[0047] According to other various exemplary and alternative
embodiments, only one of subsystems 52 and 54 may be provided on
vehicle 10. For example, vehicle 10 may include just subsystem 52
so that only front portion 21 of suspension system 16 can be
actuated between a cross-linked configuration and a straight
plumbed configuration, while rear portion 23 is configured to
permanently remain in a straight plumbed configuration. Whether it
is desirable to utilize both of subsystems 52 and 54 (or other
subsystems for other pairs or sets of wheel assemblies) or just one
of them will depend on the characteristics of the particular
vehicle in which the subsystems are used. For example, the use of
only subsystem 52 in one vehicle may cause it to perform less
desirable than it would perform if only subsystem 54 were used or
if both subsystems 52 and 54 were used. In a different vehicle, the
use of only subsystem 52 may cause the vehicle to perform more
desirable than it would perform if only subsystem 54 were used or
if both subsystems 52 and 54 were used. How many subsystems should
be used and where will depend on the vehicle within which hydraulic
system 25 will be incorporated.
[0048] According to a second exemplary embodiment illustrated
schematically in FIG. 4, hydraulic system 25 is configured to
accommodate a vehicle having three sets of wheel assemblies (e.g.,
a set of front wheel assemblies and tandem rear axles). In this
configuration, hydraulic system 25 includes the same subsystems 52
and 54 as described above, but in addition includes a third
subsystem 90, which is substantially similar to subsystems 52 and
54. Like each of subsystems 52 and 54, subsystem 90 hydraulically
couples cylinders 34e and 34f (the cylinders corresponding to the
additional set of wheel assemblies 24e and 24f).
[0049] In subsystem 90, fluid lines 92a and 92b hydraulically
couple upper chamber 48 and lower chamber 50 of cylinder 34e,
respectively, to a valve designated as valve 64c, while fluid lines
94a and 94b hydraulically couple upper chamber 48 and lower chamber
50 of cylinder 34f, respectively, to valve 64c. An accumulator 66e
is hydraulically coupled to fluid line 92b and an accumulator 66f
is hydraulically coupled to fluid line 94b. Valve 64c is configured
to be actuated between the cross-plumbed position and the straight
plumbed position. In the cross-plumbed position, valve 64c
hydraulically couples fluid line 92a to fluid line 94b (e.g., upper
chamber 48 of cylinder 34e is hydraulically coupled to lower
chamber 50 of cylinder 34f) and hydraulically couples fluid line
92b to fluid line 94a (e.g., lower chamber 50 of cylinder 34e is
hydraulically coupled to upper chamber 48 of cylinder 34f). In the
straight-plumbed position, valve 64c hydraulically couples fluid
line 92a to fluid line 92b (e.g., upper chamber 48 of cylinder 34e
is coupled to lower chamber 50 of the same cylinder) and
hydraulically couples fluid line 94a to fluid line 94b (e.g., upper
chamber 48 of cylinder 34f is coupled to lower chamber 50 of the
same cylinder).
[0050] This embodiment of hydraulic system 25 operates in the same
general manner as the embodiment of hydraulic system 25 that
includes only subsystems 52 and 54, it simply includes an addition
subsystem (subsystem 90) that is coupled to the additional set of
wheel assemblies 24e and 24f. According to various alternative and
exemplary embodiments, the hydraulic system may not include a
subsystem that is movable between a straight plumbed configuration
and a cross-plumbed configuration for each corresponding pair of
wheel assemblies. Instead, such a subsystem may be provided for
just the front pair of wheel assemblies, for just a rear pair of
wheel assemblies, for each rear pair of wheel assemblies for
vehicles with more than one pair of rear wheel assemblies, or for
just certain pairs of wheel assemblies, and those wheel assemblies
for which such an adjustable subsystem is not provided may be
coupled to cylinders that are configured to remain in the
straight-plumbed condition.
[0051] According to a third exemplary embodiment illustrated
schematically in FIG. 5, hydraulic system 25 is configured to
accommodate a vehicle having three sets of wheel assemblies (e.g.,
a set of front wheel assemblies and tandem rear axles). In this
configuration, hydraulic system 25 includes subsystem 52, as
described above, that cooperates with the front wheel assemblies
and a subsystem 96 that cooperates with the wheel assemblies of the
tandem rear axles. Subsystem 96 is configured so that both of the
cylinders on the left side of vehicle 10 are hydraulically coupled
to one another and to both of the cylinders on the right side of
the vehicle, which are also coupled to one another. Thus, rather
than having a substantially independent subsystem for each pair of
left/right wheel assemblies, which may be actuated between the
cross-plumbed configuration and the straight plumbed configuration
independently of one another, subsystem 96 links the operation of
the two cylinders on each side of the tandem axle of the vehicle
and allows the subsystem to be actuated between a state in which
both cylinders on each side of the tandem axle are coupled together
in a straight plumbed configuration and a state in which both
cylinders on the left side of the tandem axle are cross-plumbed to
both cylinders on the right side of the tandem axle.
[0052] In this configuration, hydraulic system 25 includes the same
general components as used in the second configuration, they are
just arranged differently. Specifically, fluid line 60a of cylinder
34c is coupled to fluid line 92a of cylinder 34e, and the joined
fluid line, shown as fluid line 160a, is coupled to valve 64d. The
coupling together of fluid lines 60a and 92a in this way
hydraulically couples upper chamber 48 of cylinder 34c with upper
chamber 48 of cylinder 34e. Similarly, fluid line 60b of cylinder
34c is coupled to fluid line 92b of cylinder 34e, and the joined
fluid line, shown as fluid line 160b, is coupled to valve 64d. An
accumulator 66c is coupled to fluid line 60b. The coupling together
of fluid lines 60b and 92b in this way hydraulically couples lower
chamber 50 of cylinder 34c with lower chamber 50 of cylinder
34e.
[0053] Cylinders 34d and 34f on the right side of vehicle 10 are
coupled together in the same manner. Specifically, fluid line 62a
of cylinder 34d is coupled to fluid line 94a of cylinder 34f, and
the joined fluid line, shown as fluid line 162a, is coupled to
valve 64d. The coupling together of fluid lines 62a and 94a in this
way hydraulically couples upper chamber 48 of cylinder 34d with
upper chamber 48 of cylinder 34f. Similarly, fluid line 62b of
cylinder 34d is coupled to fluid line 94b of cylinder 34f, and the
joined fluid line, shown as fluid line 162b, is coupled to valve
64d. An accumulator 66d is coupled to fluid line 62b. The coupling
together of fluid lines 62b and 94b in this way hydraulically
couples lower chamber 50 of cylinder 34d with lower chamber 50 of
cylinder 34f.
[0054] Valve 64d is configured to actuate between a cross-plumbed
position and a straight plumbed position. In the cross-plumbed
position, valve 64d couples fluid line 160a (which couples upper
chambers 48 of cylinders 34c and 34e) and fluid line 162b (which
couples lower chambers 50 of cylinders 34d and 34f). Valve 64d also
couples fluid line 160b (which couples lower chambers 50 of
cylinders 34c and 34e) and fluid line 162a (which couples upper
chambers 48 of cylinders 34d and 34f). In the straight plumbed
position, valve 64d couples fluid line 160a (which couples upper
chambers 48 of cylinders 34c and 34e) and fluid line 160b (which
couples lower chambers 50 of cylinders 34c and 34e). Valve 64d also
couples fluid line 162a (which couples upper chambers 48 of
cylinders 34d and 34f) and fluid line 162b (which couples lower
chambers 50 of cylinders 34d and 34f).
[0055] Subsystem 96 of this embodiment of hydraulic system 25
operates in the same general manner as subsystem 52 or subsystem
54, described above. However, instead of cross-linking one of the
front or rear cylinders to the corresponding front or rear cylinder
on the opposite side of the vehicle, this embodiment cross-links
the front and rear cylinders on the left side of the tandem axle
with the front and rear cylinders on the right side of the tandem
axle.
[0056] According to various alternative and exemplary embodiments,
any two or more cylinders on the left side of the vehicle may be
linked to the corresponding two or more cylinders on the right side
of the vehicle in the manner described above. For example, the
vehicle may include two pairs of front wheel assemblies and two
pairs of rear wheel assemblies (e.g., as in a truck having tandem
front and rear axles), with a pair of cylinders corresponding to
each pair of wheel assemblies. The two pairs of cylinders
corresponding to the two pairs of front wheel assemblies and the
two pairs of cylinders corresponding to the two pairs of rear wheel
assemblies may each be coupled together in the manner described
above, where the operation of the two left-hand side cylinders of
the two front pair of wheel assemblies is linked and the operation
of the two right-hand side cylinders of the two front pair of wheel
assemblies is linked, and where the operation of the two left-hand
side cylinders of the two rear pair of wheel assemblies is linked
and the operation of the two right-hand side cylinders of the two
rear pair of wheel assemblies is linked. According to other various
alternative and exemplary embodiments, the hydraulic system may be
configured so that each pair of cylinders operate independently of
one another (e.g., each pair of cylinders forms a substantially
independent subsystem) or so that the operation of the left-hand
side cylinders and the right-hand side cylinders of any two or more
pairs of the cylinders is linked.
[0057] According to a fourth exemplary embodiment illustrated
schematically in FIG. 6, hydraulic system 25 includes two
substantially independent subsystems, a subsystem 97 that
hydraulically couples cylinders 34a and 34d and a subsystem 98 that
hydraulically couples cylinders 34b and 34c.
[0058] In subsystem 97, fluid lines 56a and 56b hydraulically
couple upper chamber 48 and lower chamber 50 of cylinder 34a,
respectively, to a valve designated as valve 64e, while fluid lines
62a and 62b hydraulically couple upper chamber 48 and lower chamber
50 of cylinder 34d, respectively, to valve 64e. An accumulator 66a
is hydraulically coupled to fluid line 56b and an accumulator 66d
is hydraulically coupled to fluid line 62b. Valve 64e is configured
to be actuated between a cross-plumbed or cross-linked position and
a straight-plumbed position. In the cross-plumbed position, valve
64e hydraulically couples fluid line 56a to fluid line 62b (e.g.,
upper chamber 48 of cylinder 34a is hydraulically coupled to lower
chamber 50 of cylinder 34d) and hydraulically couples fluid line
56b to fluid line 62a (e.g., lower chamber 50 of cylinder 34a is
hydraulically coupled to upper chamber 48 of cylinder 34d). In the
straight-plumbed position, valve 64e hydraulically couples fluid
line 56a to fluid line 56b (e.g., upper chamber 48 of cylinder 34a
is coupled to lower chamber 50 of the same cylinder) and
hydraulically couples fluid line 62a to fluid line 62b (e.g., upper
chamber 48 of cylinder 34d is coupled to lower chamber 50 of the
same cylinder).
[0059] Subsystem 98 is configured in the same general manner as
subsystem 97. In subsystem 98, fluid lines 58a and 58b
hydraulically couple upper chamber 48 and lower chamber 50 of
cylinder 34b, respectively, to a valve designated as valve 64f,
while fluid lines 60a and 60b hydraulically couple upper chamber 48
and lower chamber 50 of cylinder 34c, respectively, to valve 64f.
An accumulator 66b is hydraulically coupled to fluid line 58b and
an accumulator 66c is hydraulically coupled to fluid line 60b. Like
valve 64e, valve 64f is configured to be actuated between a
cross-plumbed position and a straight plumbed position. In the
cross-plumbed position, valve 64f hydraulically couples fluid line
58a to fluid line 60b (e.g., upper chamber 48 of cylinder 34b is
hydraulically coupled to lower chamber 50 of cylinder 34c) and
hydraulically couples fluid line 58b to fluid line 60a (e.g., lower
chamber 50 of cylinder 34b is hydraulically coupled to upper
chamber 48 of cylinder 34c). In the straight-plumbed position,
valve 64f hydraulically couples fluid line 58a to fluid line 58b
(e.g., upper chamber 48 of cylinder 34b is coupled to lower chamber
50 of the same cylinder) and hydraulically couples fluid line 60a
to fluid line 60b (e.g., upper chamber 48 of cylinder 34c is
coupled to lower chamber 50 of the same cylinder).
[0060] The ability to move subsystems 97 and 98 of hydraulic system
25 between a cross-plumbed state and a straight plumbed state
allows suspension system 16 to be adjusted to the configuration
that is most suitable for the particular situation encountered by
vehicle 10. When subsystems 97 and 98 are in the straight-plumbed
position, upper chamber 48 of each cylinder 34a, 34b, 34c, and 34d
is hydraulically coupled to lower chamber 50 of the same cylinder.
Accordingly, each of cylinders 34a, 34b, 34c, and 34d operate
substantially independently of one another. As discussed above, the
independent operation of cylinder 34a, 34b, 34c, and 34d is
generally desirable when vehicle 10 is traveling over relatively
rough or bumpy terrain, such as on unpaved roads or on other off
road terrain.
[0061] When subsystems 97 and 98 are in the cross-plumbed position,
upper chamber 48 of cylinders 34a and 34b are hydraulically coupled
to the respective lower chambers 50 of the corresponding cylinders
34d and 34c, and the lower chambers 50 of cylinders 34a and 34b are
hydraulically coupled to the respective upper chambers 48 of
cylinders 34d and 34c. Accordingly, the operation of the front
cylinder on the left side of the vehicle (cylinder 34a) is linked
to the operation of the rear cylinder on the right side of the
vehicle (cylinder 34d) and the operation of the front cylinder on
the right side of the vehicle (cylinder 34b) is linked to the
operation of the rear cylinder on the left side of the vehicle
(cylinder 34c). In this configuration, suspension system 16 tends
to improve the handling and maneuverability of vehicle 10 when it
is traveling at higher speeds on a relatively smooth roadway, such
as a highway or interstate. Such improvement is the result, at
least in part, of the tendency of suspension system 16 to resist
both the roll and pitch of body portion 12 as vehicle 10 changes
direction, accelerates, or decelerates, such as when it goes around
a curve or bend in the road or when it slows down quickly. In these
situations, allowing for the completely independent movement of
wheel assemblies 24a, 24b, 24c, and 24d is less important because
wheel assemblies 24a, 24b, 24c, and 24d move up and down in the
same general manner due to the relatively smooth surface over which
they are traveling.
[0062] According to various alternative or exemplary embodiments,
the hydraulic system may take one of a variety of other
configurations. The cylinders corresponding to any pair of wheel
assemblies may be configured to operate independently of one
another, may be configured so that the system coupling the two
cylinders can be moved between a straight plumbed configuration and
a cross-plumbed configuration, or may be configured so that one
pair of cylinders are coupled to one or more other pairs of
cylinders in such a way that all the linked cylinders on one side
of the vehicle may be straight plumbed or may be cross-plumbed with
all the linked cylinders on the other side of the vehicle.
According to other various alternative and exemplary embodiments,
the cylinders corresponding to one pair of wheel assemblies may be
coupled together in the manner that is different than the manner in
which the cylinders corresponding to another pair of wheel
assemblies are coupled together. According to other various
alternative and exemplary embodiments, one or more accumulators may
be coupled to fluid lines extending from the upper chamber and/or
the lower chamber of the cylinders. According to still other
various alternative and exemplary embodiments, one or more of the
different principles or configurations described above may be
applied to the entire vehicle or may be applied to only a portion
of the vehicle.
[0063] According to one exemplary embodiment, fluid may be added to
or removed from hydraulic system 25 in order to adjust the ride
height of vehicle 10. For example, by adding fluid to subsystem 52,
the ride height of vehicle 10 may be increased, whereas by removing
fluid from subsystem 52, the ride height of vehicle 10 may be
decreased. The addition of fluid to subsystem 52 has the effect of
increasing the equilibrium pressure within subsystem 52, which has
the effect of extending the equilibrium length of cylinders 34a and
34b. Conversely, the removal of fluid from subsystem 52 has the
effect of decreasing the equilibrium pressure within subsystem 52,
which has the effect to decreasing the equilibrium length of
cylinders 34a and 34b. According to one exemplary embodiment,
control unit 68 monitors the ride height and/or system pressure and
causes hydraulic system 25 or its various subsystems (through the
use of a pump and reservoir) to increase or decrease the amount of
fluid within each particular subsystem to adjust the ride
height.
[0064] Referring again to FIG. 3, central tire inflation system 17
(shown schematically) is a system of components that is operably
coupled to wheel assemblies 24a, 24b, 24c, and 24d and that is
configured to monitor and adjust the air pressure within tire
portion 33 of wheel assemblies 24a, 24b, 24c, and 24d based on user
selected settings, terrain, vehicle loads, and/or other operational
characteristics of the vehicle (such as vehicle speed, engine
speed, etc.). By monitoring and adjusting the air pressure within
tire portion 33 of wheel assemblies 24a, 24b, 24c, and 24d, central
tire inflation system 17 is intended to improve the performance of
vehicle 10 in each of the various situations in which vehicle 10
may operate. According to one exemplary embodiment, central tire
inflation system 17 includes an air handling system 70, a control
unit 72, and a switch 74.
[0065] Air handling system 70 is a system of pneumatic components
that couples each of wheel assemblies 24a, 24b, 24c, and 24d to an
air pressure source and that allows for the selective transport of
air to one or more of wheel assemblies 24a, 24b, 24c, and 24d based
on signals received from control unit 72. According to one
exemplary embodiment, air handling system 70 includes an air source
76, a valve or manifold 78, and a series of air lines 80. Air
source 76 may be any one of a variety of different sources of air,
such as a mechanical air pump coupled to the engine of vehicle 10
that may be used to operate other components of vehicle 10 (such as
the brakes, horn, etc.), a tank of pressurized air, an electric air
pump coupled to the battery of vehicle 10, or other sources of air
pressure. Manifold 78 is a valve arrangement that is coupled to air
source 76 and air lines 80 and that is configured to selectively
direct pressurized air to or from one or more of wheel assemblies
24a, 24b, 24c, and 24d (through different air lines 80) based on
input from control unit 72. Air lines 80, which may include various
tubes, pipes, and/or hoses, extend between wheel assemblies 24a,
24b, 24c, and 24d and manifold 78 and allow air from air source 76
to be transported from manifold 78 to any one or more of wheel
assemblies 24a, 24b, 24c, and 24d.
[0066] Control unit 72 (e.g., a controller, computer,
microcontroller, control module, etc.) is an electronic device (or
multiple electronic devices coupled together) that monitors or
measures the value of a variable quantity or condition and that
sends signals to, or controls the operation of, manifold 78 based
on the value of the variable quantity or condition. According to
one exemplary embodiment, control unit 72 monitors or measures the
condition of switch 74 as well as the air pressure of the air
within tire portion 33 of wheel assemblies 24a, 24b, 24c, and 24d
and controls the operation of manifold 78 based on the position of
switch 74 and the air pressures. According to various alternative
and exemplary embodiments, control unit 72 may monitor or measure
one of a variety of different or additional variables or
conditions, including the load carried by vehicle 10, the speed of
vehicle 10, engine speed, transmission shifting, anti-lock braking
systems, axle differential locks, the pressure within various
portions of air handling system 70, etc. According to other various
alternative and exemplary embodiments, the control unit may take
one of a variety of different configurations, and may control or
send signals to one or more of a variety of different components of
vehicle 10. For example the control unit may be configured to
control engine speed, transmission shifting, anti-lock braking
systems, axle differential locks, and other components or devices
of vehicle 10. The control unit of the central tire inflation
system may also be configured to control the operation of the
hydraulic system. According to still other various alternative and
exemplary embodiments, the control unit may or may not be
programmable.
[0067] Switch 74 (e.g., toggle, interface, button, etc.) is an
interface that allows an occupant of vehicle 10 to adjust or set
air handling system 70. Switch 74 is coupled to control unit 72 in
such a way that control unit 72 monitors the position of switch 74
and alters the state or configuration of air handling system 70 as
switch 74 is moved between its different positions. Accordingly,
the occupant is able to selectively adjust the configuration of air
handling system 70 (and ultimately hydraulic system 25, as
discussed below) by moving switch 74 between its different
positions.
[0068] According to one exemplary embodiment, switch 74 is a single
switch that can be moved between four different positions: a
highway position, a cross-country position, a mud-sand-snow
position, and an emergency position. Control unit 72 is preset or
programmed so that when switch 74 is moved to the highway position,
control unit 72 causes manifold 78 to operate in a manner that
makes the resulting configuration of air handling system 70 and
wheel assemblies 24a, 24b, 24c, and 24d appropriate for use of
vehicle 10 on the highway. Similarly, control unit 72 is present or
programmed such that as switch 74 is moved to one of the other
three positions, control unit 72 causes manifold 78 to operate in a
manner that makes the resulting configuration of air handling
system 70 and wheel assemblies 24a, 24b, 24c, and 24d appropriate
for use of vehicle 10 in the condition corresponding to the
particular position of switch 74.
[0069] According to an alternative embodiment, the switch may
additionally include a load selection switch that allows the
occupant to select a load setting that is closest to the actual
load of vehicle 10. Based on the selected terrain and load
settings, the control unit may be programmed to cause manifold 78
to operate in a manner that makes the resulting configuration of
air handling system 70 and wheel assemblies 24a, 24b, 24c, and 24d
appropriate for use of vehicle 10 in the conditions corresponding
to the particular positions of the terrain portion and load portion
of switch 74.
[0070] Using switch 74, the operator of vehicle 10 is able to
adjust air handling system 70 based on the particular type of
terrain over which vehicle 10 is traveling and/or on the load
conditions of vehicle 10. This ability to adjust air handling
system 70 helps improve the overall performance of vehicle 10 in
the different conditions (e.g., terrain and load conditions) it may
encounter.
[0071] Various embodiments of a central tire inflation system are
commercially available from Eaton Corporation and from a variety of
other sources.
[0072] According to one exemplary embodiment, control unit 68 of
hydraulic system 25 is coupled to control unit 72 of central tire
inflation system 17 and is programmed to configure hydraulic system
25 based on the state of central tire inflation system 17. Thus,
when an occupant of vehicle 10 moves switch 74 into the highway
position, for example, control unit 72 of central tire inflation
system 17 causes central tire inflation system 17 to move into a
configuration that is appropriate for use of vehicle 10 on the
highway. Control unit 68 of hydraulic system 25 monitors control
unit 72 so that when central tire inflation system 17 converts to a
configuration that is appropriate for use of vehicle 10 on the
highway, control unit 68 causes hydraulic system 25 to convert to a
configuration that is appropriate for use of vehicle 10 on the
highway.
[0073] According to one exemplary embodiment, control unit 68 is
programmed to cause hydraulic system 25 (e.g., or each subsystem of
hydraulic system 25) to move into the cross-plumbed configuration
when central tire inflation system 17 converts to a configuration
that is appropriate for use of vehicle 10 on the highway, and to
cause hydraulic system 25 to move into the straight plumbed
configuration when central tire inflation system 17 converts to a
configuration that is appropriate for use of vehicle 10 on any
other terrains (e.g., when central tire inflation system 17
converts into cross-country mode, a mud-sand-snow mode, or
emergency mode). According to various alternative and exemplary
embodiments, control unit 68 may cause less than all of the
subsystems of hydraulic system 25 to switch between the
cross-linked position and the straight plumbed position in response
to a change in the state of central tire inflation system 17.
According to another alternative and exemplary embodiment, control
unit 68 may alternatively or additionally be programmed to adjust
the ride height of vehicle 10 based on the configuration of central
tire inflation system 17.
[0074] By linking the configuration of air handling system 70 and
hydraulic system 25 to the type of terrain and/or load conditions
(which correspond to the different switch positions), even a driver
or occupant unfamiliar with how air handling system 70 and
hydraulic system 25 operate and when particular configurations of
air handling system 70 and hydraulic system 25 may be most
appropriate will be able to place air handling system 70 and
hydraulic system 25 in a configuration that is suitable for the
particular situation. Furthermore, a driver familiar with the
operation of central tire inflation system 17 and hydraulic system
25 is able to select a particular configuration of hydraulic system
25 by setting the central tire inflation system 17 to a certain
setting, which gives the driver control over the operation of
hydraulic system 25 that may be beneficial in unusual
circumstances. Moreover, linking the configuration of air handling
system 70 and hydraulic system 25 to the type of terrain and/or
load conditions also helps to reduce the likelihood that hydraulic
system 25 will switch to a cross-plumbed configuration when it is
not desirable to do so (such as when the vehicle is traveling off
road and hits a bump that causes a significant lateral
acceleration) and therefore reduces the need for additional
equipment or components that are intended reduce the likelihood
that the hydraulic system will switch to an undesirable
configuration.
[0075] According to various alternative embodiments, the suspension
system described above may take a variety of different
configurations and may be used with a variety of different
vehicles. According to other alternative embodiments, the
suspension system may be used with a variety of different
components and may be used without one of more of the components
described above, or it may be used in conjunction with components
or elements other than those described above.
[0076] Although the present inventions have been described with
reference to exemplary and alternative embodiments, workers skilled
in the art will recognize that changes may be made in form and
detail without departing from the spirit and scope of the
invention. For example, although different exemplary and
alternative embodiments may have been described as including one or
more features providing one or more benefits, it is contemplated
that the described features may be interchanged with one another or
alternatively be combined with one another in the described
exemplary embodiments or in other alternative embodiments. Because
the technology of the present invention is relatively complex, not
all changes in the technology are foreseeable. The present
invention described with reference to the exemplary and alternative
embodiments and set forth in the following claims is manifestly
intended to be as broad as possible. For example, unless
specifically otherwise noted, the claims reciting a single
particular element also encompass a plurality of such particular
elements.
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