U.S. patent application number 12/637567 was filed with the patent office on 2010-06-17 for machine employing cab mounts and method for controlling cab mounts to based on machine location.
This patent application is currently assigned to CATERPILLAR, INC.. Invention is credited to Brett D. Ellen, Steven D. Jones, Ronald B. Warnat.
Application Number | 20100152980 12/637567 |
Document ID | / |
Family ID | 42239202 |
Filed Date | 2010-06-17 |
United States Patent
Application |
20100152980 |
Kind Code |
A1 |
Jones; Steven D. ; et
al. |
June 17, 2010 |
Machine Employing Cab Mounts and Method for Controlling Cab Mounts
to Based on Machine Location
Abstract
A machine employing controllable mounts and a method for
controlling such mounts based on machine location are disclosed.
The controllable mount may include a housing, a pin, rheological
fluid within the housing and coils provided proximate to the
rheological fluid. As current is applied to the coils, the apparent
viscosity of the rheological fluid is increased, and in so doing so
is the stiffness of the controllable mount. Depending on machine
location, however, the operator may want differing levels of
stiffness in one or more of the controllable mounts. For example,
when roading on rocky terrain, the operator may want relatively
loose mounts so as to absorb the large vibration inputs and make
for a more comfortable ride. The present disclosure therefore
identifies the machine location through global positioning
satellite information, topography maps, inclinometers, altimeters,
operator input, and the like and controls the current to the coils,
and thus the relative stiffness and damping of the controllable
mounts, accordingly.
Inventors: |
Jones; Steven D.; (Metamora,
IL) ; Warnat; Ronald B.; (Howell, MI) ; Ellen;
Brett D.; (Peoria Heights, IL) |
Correspondence
Address: |
Caterpillar Inc.;Intellectual Property Dept.
AH 9510, 100 N.E. Adams Street
PEORIA
IL
61629-9510
US
|
Assignee: |
CATERPILLAR, INC.
Peoria
IL
|
Family ID: |
42239202 |
Appl. No.: |
12/637567 |
Filed: |
December 14, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61122490 |
Dec 15, 2008 |
|
|
|
Current U.S.
Class: |
701/49 ;
188/267.2 |
Current CPC
Class: |
B60G 2400/102 20130101;
F16F 9/53 20130101; B60G 17/0165 20130101; B62D 33/0608 20130101;
E02F 9/2025 20130101; F16F 9/532 20130101; B60N 2/0248 20130101;
F16F 9/20 20130101; B60G 2400/252 20130101; F16F 13/08
20130101 |
Class at
Publication: |
701/49 ;
188/267.2 |
International
Class: |
G06F 17/00 20060101
G06F017/00; F16F 9/53 20060101 F16F009/53 |
Claims
1. A machine, comprising: a frame; an operator cab supported by the
frame; a controllable mount operatively connecting the operator cab
to the frame, the controllable mount including: a housing; a pin
mounted within the housing; a rheological fluid within the housing;
and coils positioned relative to the housing to generate a field
through the rheological fluid; and an electronic control unit
operatively associated with the coils and adapted to change a level
of current applied to the coils to adjust an apparent viscosity of
the rheological fluid based on machine location.
2. The machine of claim 1, wherein the operator cab includes an
operator interface through which an operator can input a machine
location.
3. The machine of claim 1, wherein the electronic control unit is
in communication with a global positioning satellite and changes
the level of current applied to the coils based on a location
provided by the global positioning satellite.
4. The machine of claim 1, wherein the electronic control unit is
in communication with a memory storing a topographical map, and
changes the level of current applied to the coils based on the
position of the machine relative to the topographical map.
5. The machine of claim 1, wherein the electronic control unit is
in communication with a memory storing a worksite map identifying
types of ground material over which the machine must traverse, and
the electronic control unit changes the level of current applied to
the coils based on the type of ground material.
6. The machine of claim 1, wherein the electronic control unit
increases the current applied to the coils when the machine is on
uneven ground, and decreases the current applied to the coils when
the machine is on even ground.
7. The machine of claim 1, further including an altitude sensor,
the electronic control unit being adapted to adjust the current
applied to the coils based on sensed altitude.
8. The machine of claim 1, further including a temperature sensor,
the electronic control unit being adapted to adjust the current
applied to the coils based on sensed temperature.
9. The machine of claim 1, further including an incline sensor, the
electronic control unit being adapted to adjust the current applied
to the coils based on sensed incline.
10. The machine of claim 9, wherein the operator cab is supported
by the frame with a plurality of controllable mounts, each of the
controllable mounts being individually adjustable.
11. The machine of claim 10, wherein the plurality of controllable
mounts include at least one forward mount and one rearward mount,
and the controllable mount further includes a pressurized fluid
chamber, the rearward mount being more pressurized than the forward
mount when the vehicle is ascending an incline in a forward
direction, and less pressurized than the forward mount when the
machine is descending an incline in a forward direction as sensed
by a sensor.
12. The machine of claim 10, wherein the plurality of controllable
mounts include at least one left mount and at least one right
mount, and the controllable mount further includes a pressurized
fluid chamber, the left and right mounts being differently
pressurized when ground topography causes the machine 100 to lean
to one side or the other as sensed by a sensor.
13. A method of controlling a cab mount, comprising: connecting a
cab to a machine using a cab mount, the cab mount having a housing,
a pin movable relative to the housing, a volume of rheological
fluid within the housing and coils mounted proximate to the volume
of rheological fluid; receiving information regarding the location
of the machine; and adjusting current flow to the coils based on
the location of the machine.
14. The method of claim 13, wherein the information regarding the
location of the machine is received from a global positioning
satellite.
15. The method of claim 13, wherein the information regarding the
location of the machine is received from a topographical map.
16. The method of claim 13, wherein the information regarding the
location of the machine is received from a worksite map depicting
types of ground material on the worksite.
17. The method of claim 13, wherein the information regarding the
location of the machine is received from a operator manually
entering the information into an operator interface.
18. The method of claim 13, wherein the controllable mount further
includes a gas spring provided in a pressurized fluid chamber
having a mechanical spring surrounded by pressured fluid, the
pressure of the pressurized fluid being adjusted based on the
location of the machine.
19. A control system for controlling a mount operatively connecting
an operator cab to a frame of a machine, comprising: a controllable
mount including a housing, a pin movable within the housing, a
volume of rheological fluid within the housing, and coils mounted
proximate to the rheological fluid; a global positioning
transceiver; and an electronic control unit adapted to receive the
location of the machine via the global positioning transceiver and
adjust a level of current directed to the coils based on the
location of the machine.
20. The control system of claim 19, wherein the controllable mount
further includes a pressurized fluid within a second chamber of the
housing and the electronic control unit changes the pressure of the
pressurized fluid based on the location of the machine.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This is a non-provisional application claiming priority
under 35 USC 119(e) to U.S. Provisional Patent Application Ser. No.
61/122,490 filed on Dec. 15, 2008.
TECHNICAL FIELD
[0002] The present disclosure generally relates to cab mounts and,
more particularly, relates to machines employing cab mounts and
methods for controlling cab mounts.
BACKGROUND
[0003] In many different heavy equipment machines, an operator cab
is supported by a frame of the machine with cab mounts. Cab mounts
are available in many different forms and configurations and
generally try to isolate the cab from the undercarriage of the
machine so as to limit the vibrational impact experienced by the
operator when the machine moves or performs work. For example, with
a loader traveling over rocky terrain, the chassis, undercarriage,
and wheels/track of the loader may be jostled and bounced around
considerably, but as the cab is not fixedly mounted to the frame,
the play afforded by the cab mounts lessens the effect of that
motion on the operator.
[0004] Such mounts can be as simple as a mechanical spring or an
elastomeric shock absorber offering a fixed level of vibration
damping. Other types of mounts are fluid or electro-chemical in
nature. Magneto-Rheological (MR) and Electro-Rheological (ER)
mounts are two examples of such mounts. Taking a MR mount as an
example, generally it includes a housing containing MR fluid, a
structure that moves through the MR fluid, and a coil for providing
a magnetic field across the MR fluid. By directing current to the
coils, not only is the magnetic field created through the MR fluid,
but the apparent viscosity of the MR fluid is increased as well. As
the structure moves through the MR fluid, increasing the apparent
viscosity of the MR fluid makes the mount more rigid.
[0005] One example of a MR mount is disclosed in U.S. Pat. No.
7,063,191. The '191 patent discloses a hydraulic mount that
includes a decoupler sub-assembly, a body filled with MR fluid, a
pumping chamber and a diaphragm chamber. The body may be formed
from a flexible, molded elastomer, such that vibrational inputs
from the engine elastically deform the pumping chamber to cause
fluid transfer between the pumping chamber and the diaphragm
chamber through the decoupler sub-assembly for viscous damping.
While somewhat effective, such a mount provides no feedback
[0006] Another example of a MR mount is disclosed in US Patent
Application Publication No. 2007/0257408, published Nov. 8, 207 to
Kenneth Alan St. Clair. et al. The '408 publication discloses a
strut with a magneto-rheological fluid damper that includes a
tubular housing filled with magneto-rheological fluid and a piston
head movable within the tubular housing along its longitudinal
length.
SUMMARY OF THE DISCLOSURE
[0007] In accordance with one aspect of the disclosure, a machine
is therefore disclosed which comprises a frame, an operator cab
supported by the frame, a controllable mount operatively connecting
the operator cab to the frame and including a housing, a pin
mounted within the housing, a rheological fluid within the housing,
and coils positioned relative to the housing to generate a field
through the rheological fluid, and an electronic control unit
operatively associated with the coils and adapted to change a level
of current applied to the coils to adjust an apparent viscosity of
the rheological fluid based on machine location.
[0008] In accordance with another aspect of the disclosure a method
of controlling a cab mount is disclosed wherein the method
comprises connecting a cab to a machine using a cab mount, the cab
mount having a housing and a pin movable relative to the housing,
receiving information relating to a location of the machine, and
adjusting current flow to the coils based on the machine
location.
[0009] In accordance with yet another aspect of the disclosure a
control system for controlling a mount operatively connecting an
operator cab to a machine frame is disclosed, wherein the control
system comprises a controllable mount including a housing, a pin
movable within the housing, a volume of rheological fluid within
the housing, and coils mounted proximate to the rheological fluid,
a global positioning transceiver, and an electronic control unit
adapted to receive the location of the machine via the global
positioning transceiver and adjust a level of current directed to
the coils based on the location of the machine.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a perspective view of a machine constructed in
accordance with the teachings of this disclosure;
[0011] FIG. 2 is a sectional view of a controllable mount
constructed in accordance with the teachings of this
disclosure;
[0012] FIG. 3 a chart depicting creep in an elastomeric member of
the controllable mount during initial use, over time, and as
corrected;
[0013] FIG. 4 is a schematic representation of a control system
constructed in accordance with the teachings of this
disclosure;
[0014] FIGS. 5a-d are schematic representations of alternative
embodiments for sensing mount displacement;
[0015] FIG. 6 is a block diagram of an operator interface
constructed in accordance with the teachings of this
disclosure;
[0016] FIG. 7 is a graph plotting frequency vs. spectral density,
depicting historical data associated with a controllable mount, and
identifying when a mount should be replaced or repaired;
[0017] FIG. 8 is a graph plotting frequency vs. amplitude, and
depicting stacked algorithms controlling same in accordance with
the teachings of this disclosure;
[0018] FIGS. 9a-e are schematic representations of different mount
location embodiments.
DETAILED DESCRIPTION
[0019] Referring now to the drawings, and with specific reference
to FIG. 1, a machine constructed in accordance with the teachings
of this disclosure is generally referred to by reference numeral
100. The machine 100 includes a frame 102 supporting an operator
cab 104. As shown, the machine 100 is depicted as a track-type
tractor, but is to be understood that the teachings of this
disclosure can be employed with equal efficacy with other heavy
industry and construction machines such as, but not limited to,
backhoe loaders, wheel loaders, tracked loaders, articulated
trucks, off-highway trucks, excavators, motor graders, fork-lifts,
skid steers, or any other machine known in the art that includes a
cab mounted to a frame.
[0020] Referring now to FIG. 2, a cross-sectional view illustrates
an example of one embodiment of a controllable mount 106 for use
with the machine 100 and method disclosed herein. As shown, the
controllable mount 106 may include a housing 108 that may be
mounted to the frame 102 (see FIG. 1) via a mounting flange 110.
The housing 108 may include a first chamber 112 and a second
chamber 114. As will be described in further detail herein, the
first chamber 112 may be filled with a rheological fluid 116 such
as a magneto-rheological (MR) fluid or an electro-rheological (ER)
fluid. The second chamber 114 may be filled with a compressed fluid
118 such as compressed gas including compressed air.
[0021] The controllable mount 106 may also include a pin 120 that
is partially disposed with the housing108 and may be attached to
the cab 104 at a mounting end 122. The pin 120 may be attached to
the housing 108 by an elastomeric member 124 that permits the pin
120 limited axial movement along axis 126 and radial movement
perpendicular to the axis 126. The elastomeric member 124 may
dampen axial as well as radial motion between the pin 120 and the
housing 108.
[0022] As shown, a damping plate 128 may be attached to the pin 120
and be disposed within the rheological fluid 116 of the first
chamber 112. The damping plate 128 may include a plurality of
apertures 130 to permit the rheological fluid 116 to pass through
the damping plate 128. As the damping plate 128 is moved through
the rheological fluid 116, the relative motion between the housing
108 and the pin 120 is damped. The level of damping may be adjusted
by applying a magnetic or electric field to the rheological fluid
116. Moreover, by changing the strength of the magnetic or electric
field, the apparent viscosity of the rheological fluid 116 is
proportionally changed thereby providing a mechanism by which the
degree of damping afforded by the controllable mount 106 can be
tailored to the needs of the operator.
[0023] In order to generate the magnetic or electric field, coils
131 are provided proximate the rheological fluid 116. More
specifically, the coils 131 may be mounted on the housing 108
laterally adjacent the first chamber 112. Leads 132 may extend from
the coils 131 for connection to a controllable power supply 134.
Alternatively, or additionally, the coils 131 may be mounted on the
pin 120 and/or the damping plate 128.
[0024] The pin 120 may also include a plunger 136 that separates
the first chamber 112 from the second chamber 114. The plunger 136
may include a seal 138 that seals against a shaft 140 of the
housing 108. In such a configuration, the plunger 136 and the
second chamber 114 act as a gas spring 142 for positioning the pin
120 at an ideal snubbing height 144, the importance of which will
be described in further detail herein. The pressure of the
compressed fluid 118 within the gas spring 142 may be adjusted by
way of a valve 146. By adjusting the pressure of the compressed
fluid 118, the biasing force of the gas spring 142 applied to the
plunger 136 is adjusted as well. A first hose or tube 148 may be
connected to the valve 146 to supply pressurized fluid 118 to the
second chamber 114. The valve 146 may also include a second hose or
tube 150 to return the pressurized fluid 118 within the second
chamber 114 to a storage tank 152, or to be vented to
atmosphere.
[0025] To assist in biasing the plunger 136 toward the ideal
snubbing height 144, a mechanical spring 154 may also be used. The
spring 154 may be disposed about a guide extension 156 of the pin
120 and extend between the guide extension 156 and a base 158 of
the housing 108. The guide extension 156 may be positioned to
contact the housing 108 and act as a first end stop for the
controllable mount 106.
[0026] The controllable mount 106 may also include a sensor 160 for
generating a signal indicative of the relative displacement between
the cab 104 and the frame 102. In the current embodiment, it does
so by determining the relative displacement between the housing 108
and the pin 120. The sensor 160 may include a strain gauge (not
shown) disposed in a channel 162 provided in the elastomeric member
124. Alternatively, the channel 162 may be filled with a conductive
elastomer 164 having an electrical conductivity and resistance that
changes with elongation and contraction. More specifically, the
strain placed on the conductive elastomer 164 may be correlated to
the resistance exhibited by the conductive elastomer 164. Thus, as
the resistance is measured, the relative displacement between the
housing 108 and the pin 120 may be calculated. Leads 166 may be
used to communicate data from the sensor 160 to an electronic
control unit 168 (see FIG. 4).
[0027] The controllable mount 106 may also include a sensor 170 to
monitor the pressure of fluid 118 within the second chamber 114.
The pressure sensor 170 may be connected to the electronic control
unit 168 as well with leads 172. In general, the pressure sensor
170 may be used to measure pressure spikes and thus wear on the
elastomeric member 124. In so doing, the remaining life and
serviceability of the controllable mount 106 can be calculated. In
addition, failure of either sensor 160 or 170 may indicate that the
controllable mount 106 needs replacement or repair.
[0028] As an alternative or addition to the sensor 160 within the
elastomeric member 124, the pressure sensor 170 may also be used to
determine the displacement of the pin 120 relative to the housing
108. More specifically, the displacement may be determined using
the formula:
V.sub.n=P.sub.i*V.sub.I/P.sub.n [0029] wherein: [0030] V.sub.n is
the new volume; [0031] P.sub.i is the initial pressure; [0032]
V.sub.i is the initial volume; and [0033] P.sub.n is the new
pressure. Initial pressure and initial volume could be initially
calibrated from a known position of the pin 120 and could
correspond to the volume and pressure of the second chamber 114.
New pressure and new volume could correspond to the displacement
from the initial position. The new position may be determined from
the new volume using the formula:
[0033] D=(V.sub.n-V.sub.i)/(.pi.*R.sup.2)
[0034] wherein: [0035] D is the change in displacement; [0036] R is
the radius of the shaft 140; [0037] V.sub.i is again the initial
volume; and [0038] V.sub.n is again the new volume. Temperature
compensation may also be used to increase the accuracy of the
displacement measurement. Alternatively, the displacement may be
determined through stored tables where these calculations have
already been determined.
[0039] This calculated displacement may then be used to provide
feedback in a control algorithm executed by the electronic control
unit 168 controlling the mount 106. More specifically, the
calculated displacement data may be used to adjust the current
applied to the coils 130 of the controllable mount 106 and hence
adjust the apparent viscosity of the controllable mount 106 to
provide improved performance.
[0040] In one embodiment, the apparent viscosity of the rheological
fluid 116 is changed in direct relation to the displacement of the
mount 106. Thus, as the pin 120 moves away from the ideal snubbing
height 144, more current is applied to the coil and the apparent
viscosity of the rheological fluid 116 increases to bias the pin
120 away from engagement with the housing 108. In so doing, the pin
120 and damping plate 128 encounter greater resistance to movement
and thus this feedback control may be used to minimize occurrences
where the pin 120 reaches an endstop, also known as bottoming or
topping out.
[0041] In another embodiment, statistical analysis of the data from
one or more sensors 160, 170 may be used to interpret the
displacement of the controllable mount 106 over time and adapt the
control of the controllable mount 106 to changes in weight in the
cab, i.e., the weight of different operators, their tools and
accessories, and the like. Initial pressure and initial volume may
be determined and calibrated at the factory and during machine
servicing.
[0042] This displacement data may also be statistically analyzed
and kept for long term storage. The historical data may include
average displacements, frequency domain, and power spectral density
data. The historical statistical displacement data may be used to
determine when to replace a specific mount. For example, if the
controllable mount is operating outside of its historical average,
the controllable mount would be deemed to need replacement.
Additionally, the history may be taken over the life of the
controllable mount to develop a long historical average. The long
historical average may be compared to a medium history and a short
history to provide a total error or a point by point error to look
for problems in performance.
[0043] By tracking and maintaining a historical statistical average
of displacement, the set and creep of the elastomeric member 124
may also be determined. As used herein, the "set" and "creep" of
the elastomeric member 124 refers to changes in the elasticity of
the elastomer. Initially, the elastomer will deform predictability
and return to the same shape and strength. Over time and repetitive
motion, however, the elastomer may begin to change at the molecular
level so as not to exhibit the same elasticity. In the present
application this can cause the elastomeric member 124 to begin to
sag over time.
[0044] In graphical form, this means that as the elastomeric member
124 sags, sets, and begins to creep, the elastomeric member 124 may
begin to behave nonlinearly as shown in FIG. 3. As shown, the
elastomeric member 124 may initially behave in a generally linear
fashion as indicated by line 174 between the end stops 176.
However, over time, the elastomeric member 124 may take on a set
and begin to creep as shown by line 178.
[0045] The electronic control unit 168 may be used to compensate
for this change in the material properties, as well as, minimize
the effects of creep. For example, the electronic control unit 168
may be used to adjust the current applied to the coils 130 and
thereby correct for the change in the material properties of the
elastomeric member 124, which is shown as dotted line 180. Thus
more current may be applied to the coils 130 when negative
displacement is determined and less where positive displacement is
determined. In configurations where a pneumatic system is available
to increase the gas pressure within the gas spring 142, the
increased gas pressure may be used to compensate further and bias
the pin 120 toward the ideal snubbing height 144.
[0046] Referring now to FIG. 4, a schematic diagram illustrates a
control system 182 for a machine 100 on which the controllable
mounts 106 may be used. As shown, the system 182 includes the
electronic control unit 168 that is in electrical communication
with machine sensors 186, an operator interface 188, and a power
source 190. The electronic control unit 168 may include a processor
192 and a computer readable media or memory 194 for storing
instructions. Machine sensors 186 may include a wide variety of
sensors including accelerometers, inclinometers, temperature
sensors, pressure transducers, and other sensors known in the art
for use on the machine 100. The operator interfaces 188 may include
joysticks, pedals, switches, buttons, touch screens, keypads, and
other devices known in the art for receiving operator input.
[0047] The electronic control unit 168 may also be in electrical
communication with a plurality of controllable mounts 106 used to
mount the cab 104 to a machine frame 102. Such mounts 106 may
include a right front controllable mount 198, a right rear
controllable mount 200, a left rear controllable mount 202, and a
left front controllable mount 204. The right front controllable
mount 198, right rear controllable mount 200, left rear
controllable mount 202, and left front controllable mount 204 may
each include the features of controllable mount 106 described
above, as well as other features of controllable mounts known in
the art.
[0048] In one embodiment, the controllable mounts 106 may be
identical. However, their physical positions on the machine frame
102 and cab 104 may be different and known via a wiring harness 206
provided between the controllable mounts 106 and the electronic
control unit 168. For example, a series of switches 208 may be
coded to indicate the position of each controllable mount 106 on
the machine frame 102. If four mounts 106 are used, for example,
the following codes of TABLE 1 may be used:
TABLE-US-00001 TABLE 1 Position Switch 1 Switch 2 Cab, forward,
right 0 0 Cab, forward, left 0 1 Cab, rear, right 1 0 Cab, rear,
left 1 1
[0049] The harness codes may provide the switch functionality
through two wires and a ground line (not shown) being run to each
mount location as part of the wiring harness 206. The switches 208
of the above table are then provided for in each connector by
connecting a respective wire to ground to provide a 1 and left open
for a 0. This may be routed through the connector to the
controllable mount 106 so that the controllable mount 106 can
identify its position on the machine frame 102. This positional
information may be used to tune and more precisely control the
controllable mounts 106 on the machine frame 102.
[0050] In another embodiment, the controllable mounts 106 may be
distinct and be configured to receive a specific connector from the
wiring harness 206. Alternatively, a generic wiring harness 206 may
be used and each controllable mount 106 may be given its address by
a technician to communicate its position to the electronic control
unit 168.
[0051] Optionally and as shown, the controllable mounts 106 may
each include the gas spring 142 as discussed above in relation to
FIG. 2. Each gas spring 142 may be pneumatically connected to a
source of pressurized gas, such as a pump 210, and a source of low
pressure gas, such as the tank 152. In the depicted embodiment, the
electronic control unit 168 is shown as being in communication with
the pump 210, but the control need not be electronic. For example a
mechanical valve arrangement can be used. With the electronic
embodiment, however, if the pressure of gas within the gas spring
142 of the right front controllable mount 198 is determined to be
too low, for example, the electronic control unit 168 may command
the pump 210 to provide pressurized gas and command a pneumatic
valve (not shown) of the right front controllable mount 198 to open
and receive the pressurized gas to increase the gas pressure within
the gas spring 142. When the pressure of the gas spring 142 is
sufficient, the electronic control unit 168 may close the valve and
shut down the pump 210. Alternatively, in situations where the
pressure is too high in the gas spring 142, the electronic control
unit 168 may open the valve to the tank 152 and close the valve
when the pressure has been sufficiently reduced.
[0052] Accurate mount displacement measurement permits the
controllable mounts 106 to be maintained at or near the ideal
snubbing height 144 for maximum effectiveness of the controllable
mounts 106. By maintaining each mount at their ideal snubbing
height 144 throughout their useful life, excessive loading and
bottoming out/topping out of the mount 106 during machine operation
may be minimized or prevented. Consequently, fewer replacement
parts of the cab 104 and mounts 106 may be needed over the life of
the machine 100. The present disclosure and its accommodating of
different static loads of the cab 104 may permit different systems
and options to be installed at different times without having to
replace the mounts 106, thus providing a high degree of modularity
and tailoring of the machine 100 to specific applications over the
entire machine life while retaining the same mount package.
[0053] Referring now to FIGS. 5a-d, in addition to the methods and
systems discussed above, controllable mount displacement
measurement can be achieved with other sensors including through
the use of a Hall-effect sensor 214. For example, as shown in FIG.
5a, a permanent magnet 216 may be positioned on the housing 108 of
the controllable mount 106. A sensor chip 218 may be connected to
the cab 104 and positioned to sense the relative position of the
magnet 216. In another embodiment (FIG. 5b), an expandable chamber
220 may house a laser 222 in one end and a receiver 224 in the
other end. Each end may be attached to one of the cab 104 and the
machine frame 102. As the chamber 220 expands and contracts with
the relative movement of the cab 104 and frame 102, accurate mount
displacement measurement may be achieved. In another embodiment, a
bar code reader 226 may be positioned to read a stainless steel or
other corrosion-resistant material bar code display 228, as
depicted in FIG. 5c. The display 228 may be attached to the frame
102 and the bar code reader 226 attached to the cab 104. In yet
another embodiment, a rotary sensor 230 with a gear 232 disposed to
move up and down a rack 234 (see FIG. 5d) may also be used to
determine the displacement.
[0054] In addition to diagnosing and correcting for creep or set in
the elastomeric member 124, the controllable mounts 106 of the
present disclosure also provide a mechanism by which machine
feedback may be provided to the operator. For example, the
controllable mounts 106 can be hardened and thereby selectively
lower damping so as to pass more of the vibration and impact loads
to the cab 104 from the machine frame 102. As indicated above,
hardening the controllable mounts 106 occurs when an electrical
current is provided to coils 131 and the apparent viscosity of the
rheological fluid 116 is increased. Conversely, when machine
feedback is not as desirable as comfort of the operator, the
controllable mount 106 may be softened by removing or reducing the
current to thereby decrease damping. The level of damping may be
manually selected by the operator, programmed to change during
specific intervals of machine operation, and/or based on sensor
inputs as described in greater detail below.
[0055] Another feature of the present disclosure is that the
operator interface 188 may permit the operator significant control
over the controllable mounts 106. For example, as shown
schematically in FIG. 6, the operator interface 188 may include an
on/off switch 236 to enable an operator to turn the controllable
mounts 106 off and thereby provide the softest ride at all times.
In such a situation, the controllable mounts 106 would function
simply as a viscous mount. Alternatively, an operator may adjust
the control algorithm via an incremented switch 238, a touch screen
240, or a keypad 242 to scale the current flow provided by a
control algorithm through the controllable mount 106. For example,
the operator may scale the control algorithm to fifty percent (or
other) in order to obtain a softer ride, which may result in a
different dynamic rate and damping characteristics of the control
system 182.
[0056] In another embodiment, the operator interface 188 may permit
the operator to have to direct control over the current being
applied to each controllable mount 106. For example, four slider
bars 244 (or a different number if a different number of
controllable mounts are used) may respectively represent the four
respective mounts 106 and allow the operator to move the slider 244
on the operator interface 188 to fit his or her personal
preferences. The operator interface 188 may be the touch screen 240
to allow direct control, or a mouse 246 or joystick 248 may be used
to move a cursor over the screen 240 to make the desired changes to
the controllable mount settings.
[0057] Further, the control of the controllable mounts 106 may be
accessible through the menu or operating system 250 of the machine
100. In some embodiments, control of the controllable mounts 106
may be accessible only to a service technician via password
protection or may be preprogrammed as part of an operator
identification device 252 that would adjust settings to the
specific operator. This may be achieved through the use of an RFID
identification card 254, or operator information stored on such
items as a cell phone 256, flash drive 258, personal digital
assistant 260, or other computer readable media or device.
[0058] The operator interface 188 may also permit the operator to
input or automatically input the geographical location of the
machine 100 as well as road and worksite material conditions.
Consequently, the electronic control unit 168 may adjust or
implement a control algorithm to best compensate for the individual
terrain characteristics of the worksite and thereby provide for the
best ride. For example, if a rocky worksite is being traversed, the
electronic control unit 168 may increase the current flow to the
coils 131 to a higher level in each controllable mount 106 in order
to provide the more damping to the cab 104 and operator. In one
example, the machine 100 may operate at fifty percent of maximum
current while traveling over the rocky terrain, and zero percent
over a smooth worksite.
[0059] In a different configuration, and operator may also specify
the type of machine task being performed, in which case different
control algorithms 262 programmed to best damp vibrations when
appropriate and allow feedback at other times may take over. For
example, if the selected task is loading trucks from a pile of
material, a loading algorithm 264 may be selected. The loading
algorithm 264 may provide the controllable mounts 106 with fifty
percent (or other) maximum current while moving between the truck
and the pile, but during bucket loading and when the bucket is
raised above a predetermined height, the electronic control unit
168 may increase the current flow to one hundred percent in order
to provide machine feedback and thus provide better operator
control.
[0060] In another example, an operator may indicate that the
machine 100 is a motor grader and the task to be performed is fine
grading. The electronic control unit 168 may then cause the
controllable mounts 106 to be hard while the transmission of the
machine 100 is in a forward gear, and soft while in a reverse gear.
During fine grading, operators desire as much feedback as possible
in order to more quickly complete the job within specified
tolerances. Additionally, or alternatively, the controllable mounts
106 may be tuned to the desire of the operator for selected
operational settings. For example, the operator may direct the
electronic control unit 168 to pass one hundred percent current
during fine grading, zero percent doing roading, and fifty percent
during snow removal.
[0061] In other example, a wheel loader may keep the controllable
mounts 106 soft during roading and moving around a worksite, but
harden the controllable mounts 106 when the bucket is raised so
that the operator can better feel the operation of the machine. In
yet another example, the controllable mounts of a track-type
tractor may be kept as soft as possible with zero current being
passed through the coils 131 while the machine 100 is being moved
with the bucket and ripper up. The same machine 100 may be
programmed to pass the maximum current when either of those
implements is performing a task.
[0062] Similarly, if the machine 100 is an excavator, when a large
load is being placed, the controllable mounts 106 may be hardened
so as to provide the operator with valuable feedback. In contrast,
when the excavator is being moved, zero current can be passed
through the controllable mounts 106 to provide a softer, more
comfortable ride to the operator. Commonly with excavators, the
controllable mounts 106 may always be soft, except when transients
occur during dumping, digging or other events.
[0063] The teachings of the present disclosure can also be employed
for detecting track slippage in a track-type tractor. By setting
the controllable mounts 106 to a high current setting, the operator
is provided with increased feedback. This feedback may indicate to
the operator that track slippage is occurring. In such an event,
the operator may choose to cease operations so that maintenance can
be performed and thus minimize undercarriage wear.
[0064] The control system 182 of the present disclosure may also
employ any of the control algorithms 262 to most effectively and
expeditiously balance feedback and comfort. In addition to the
loading algorithm 264 mentioned above, a predictive algorithm 266
may be used by the electronic control unit 168 to control the
controllable mounts 106. The controllable mounts 106 may be tuned
to the specific machine use and task being performed, such as
dozing, ripping, grading, or excavating, or to the desired setting
such as improved ride, noise reduction or operator comfort.
Specific machine use and task may be entered by the operator as
indicated above, or may be determined from the position of a blade,
ripper, bucket or other implements 268 of the machine 100 as sensed
by an implement position sensor 269. Alternatively, they may be
inferred from the operator interface 188, hydraulic pressures
gauges 270, worksite maps 272, global positioning system
information 274, laser grading inputs 276, topographical maps 278,
inclinometers 280, determined pitch rates 282, steering signals
284, altimeters 285, articulation joint position 286, and
thermometers 287. For example, shock loads may be anticipated from
the position of a truck in a loading zone and thus the controllable
mount 106 may be adjusted accordingly to absorb as much of the
impact from loading as possible.
[0065] Alternatively, when the bucket of a wheel loader, tracked
loader, excavator or other machine using buckets is lowered and
positioned for engagement with a pile, the controllable mounts 106
may be initially softened and then hardened when the hydraulic
cylinder pressures exceed a predetermined threshold to provide
feedback to the operator while minimizing the impact of the bucket
engaging the pile. In addition, speed of the machine 100 can be
used to predict the desired settings for the controllable mounts
106. For example, at higher speeds, as sensed by a speedometer 288,
the controllable mounts 106 may be softer and then hardened when
the machine slows 100. This hardening and softening may also be
dependent on a transmission 289 of the machine (100), specifically
a gear in which the machine 100 is operating. In first gear a fifty
percent (or other) current may be passed through the coils 131 and
in a second gear forty percent may be passed. In third gear, twenty
five percent current may be passed and in fourth gear zero percent
may be passed. Harder mounts at lower speeds would provide the
operator with a better feedback, while higher speeds would provide
greater comfort.
[0066] The predictive algorithm 266 may also use the sensed speed
of the implement to control the controllable mounts 106. For
example, when a blade is lowered the initial contact with the
ground can jar the operator. Thus, when the blade is being dropped,
the controllable mounts 106 may be softened in anticipation of the
impact and hardened after contact has been made to improve feedback
and control. Generally, the control algorithm 262 may also be set
up to control the vibrational, heave, pitch, roll and yaw modes as
well. The predictive algorithm 266 may also be used to predict that
when an implement 268 is not in use and the machine 100 is moving
at a relatively high rate of speed, this may mean that roading is
taking place and the controllable mounts 106 should be adjusted for
maximum comfort.
[0067] A historical algorithm 290 may also be used. More
specifically, a histogram of the performance of each controllable
mount 106 may be obtained from the sensors associated with each
controllable mount 106. The histogram may be used to continuously
tune each individual controllable mount 106 to current conditions.
In other words, the electronic control unit 168 uses the sensor
histories to adapt the controllable mount 106 to current
performance, thus providing improved performance over time and use.
For example, peak pressure and frequency may be kept to develop a
history of performance to identify when to harden and soften with
decay rate. If the controllable mount 106 undergoes very little
movement over a past history, it can soften itself up to avoid
unnecessary harshness and wasting of energy. As more motion is
seen, the controllable mount 106 can then increase damping. For
example, if while the machine is roading, high frequency small
displacement vibration is sensed, the controllable mounts 106 can
soften up to minimize noise, increase comfort, and save energy.
When the machine 100 begins encountering rough terrain, the
electronic control unit 168 may increase current to change the
damping of the controllable mount 106 to compensate for the larger
low frequency displacement.
[0068] In order to prevent failure of one of the controllable
mounts 106 from causing damage to the other controllable mounts 106
and/or other machine systems through continued use, the sensor data
collected from sensors associated with the controllable mount 106
may be collected and used by the historical algorithm 290 to
provide a history of operation which may then be used to determine
operating tolerances. The current sensor data may be used to
provide the power spectral density of the controllable mount 106
and determine if the controllable mount 106 should be replaced. For
example, and referring to FIG. 7, the dotted lines 292 may
represent the tolerances for acceptable operation for the
controllable mount 106 and the solid line 294 may represent the
actual running power spectral density. A spike 296 outside of a
tolerance zone 298 or an average error which exceeds the tolerance
zone 298 may indicate that the controllable mount 106 should be
replaced. In an alternative, the displacement and acceleration of
the cab 104 relative to the mount 106 or the exact displacement of
the mount components could be used to follow the life of the
controllable mount 106 and feed the historical algorithm 290 to
control the stiffness of the controllable mount 106.
[0069] These control algorithms 262 and the others discussed herein
may be implemented as stacked algorithms 300 as well. For example,
the electronic control unit 168 may use a default algorithm 302, an
end stop algorithm 304, and a resonant control algorithm 306. The
default algorithm 302 may use the controllable mount history to
adjust the current to performance needs. All three algorithms may
be calculated together and priority may be given to the algorithm
that provides the highest force control over the controllable mount
106 under the current circumstances. For example, and referring to
FIG. 8, the machine 100 may be roading during which the default
algorithm 302 may be used to control the controllable mount 106. If
the machine 100 moves over a pothole, that will provide an impulse
to the control system 182 which if undamped is represented by line
308. Line 310 represents the effect produced by the stacked
algorithms 300 in response to the impulse. The default algorithm
302 may control until the endstop algorithm 304 may then be given
priority to control the controllable mount 106. After the endstop
algorithm 304 has acted, the resonant control algorithm 306 may be
given priority to dampen out a resonance caused by the impact with
the pothole. The default algorithm 302 may resume control of the
controllable mount 106 once the resonance has been controlled.
[0070] In addition to operator selected control and the control to
provide operator feedback, the electronic control unit 168 may be
used to provide cab 104 leveling and adjustment. Specifically,
static load adjustment and ride height adjustment may be attained
by adjusting the gas spring 142 to bias the pin 120 of each mount
106 away from engagement with the housing 108 and toward its ideal
snubbing height 144. This therefore avoids having the pin 120
engage the housing 108 in "topping out" or "bottoming out" fashion.
The electronic control unit 168 may monitor the relative
displacement and adjust the gas spring 142 by adding or releasing
gas. If the sensors 160, 170 indicates that the mount 106 is at or
near the ideal snubbing height 144, no action is taken by the
electronic control unit 168 to adjust the pressure within the gas
spring 142.
[0071] This adjustment of the controllable mount 106 may be
beneficial to compensate for different sized operators who may or
may not be carrying tools, food and other equipment in the cab 104.
The different loads may move the controllable mounts 106 away from
the ideal snubbing height 144. In some applications, the machine
100 may be operating on a slope and thus the downside controllable
mounts may bear a larger portion of the load. Thus, the downside
controllable mounts may not be located at their ideal snubbing
heights 144. The pneumatic chamber 114 of each mount 106 may thus
be individually adjusted to return each mount 106 to the ideal
snubbing height 144.
[0072] Changes in altitude and ambient temperature may also move
the controllable mounts 106 from their ideal snubbing heights 144.
For example, a machine 100 that has been operating in zero degree
temperatures at sea level and then taken into the mountains and
used at six thousand feet above sea level in fifty degree
temperatures may have mounts that are no longer disposed at their
ideal snubbing heights 144. The present disclosure may therefore
adjust for this change in altitude and ambient temperature to
return the mounts 106 to their ideal snubbing heights 144.
[0073] A mixed mount arrangement may also be used to provide
reduced cost and complexity while providing many of the benefits
associated with controllable mounts. For example, as shown in FIGS.
9a-e, controllable mounts 106 may be used at some locations to
provide controllability to the cab response while using lower cost
mounts to help support/attach the cab 104 at other locations. In
one embodiment (see FIG. 9a), where pitching of the cab 104 is
desired to be controlled, two passive mounts 312 may be positioned
at a front 314 of the cab 104 and two controllable mounts 106 may
be positioned at rear locations 316. Thus, through selective
hardening of the controllable mounts 106, the pitch and roll motion
may be controlled. The configuration may also be reversed as in
FIG. 9b with two passive mounts 312 positioned at the rear 316 of
the cab 104 and two controllable mounts 106 positioned at the front
314 of the cab 104. As used herein, passive mounts have dampening
characteristics that cannot be altered during operation and
include, for example, viscous and rubber mounts.
[0074] Alternatively, a three-point system may also be possible
with a single passive mount 312 in front 314 and two controllable
mounts 106 positioned at the rear 316 of the cab 104, as shown in
FIG. 9c, so that the structure is less expensive and easier to
manufacture for plane and positional alignment. In yet another
embodiment (see FIG. 9d), two passive mounts 312 may be mounted
near an inertial pitch axis 318 with a third controllable mount 106
being mounted away from the axis 318.
[0075] Another cab mounting arrangement may be used with machines
100 that include an external roll-over protection structure 320.
For example, as shown in FIG. 9e), passive mounts 312 may be
mounted between the cab 104 and the frame 102 of the machine 100.
One or more controllable mounts 106 may be disposed above the cab
104 and mounted between the cab 104 and the external roll-over
protection structure 320. In this configuration, the passive mounts
312 provide noise reduction and the overhead controllable mounts
106 may provide ride control.
INDUSTRIAL APPLICABILITY
[0076] From the foregoing, it can be seen that the teachings of
this disclosure have applicability in a variety of industrial
situations, particularly with machines to which operator cabs are
mounted. Such machines may include, but are not limited to,
track-type tractors, wheel loaders, track loaders, excavators,
motor graders, articulated trucks, off-highway trucks, skid steers,
skidders, and the like. The machines may employ a controllable
mount so as to isolate the vibrations generated by the
undercarriage and engine of the machine from the cab and thus the
operator within the cab.
[0077] In addition, by providing a mount such as that disclosed
herein, the ideal snubbing height of the pin within the housing can
be maintained. In so doing, excessive loading and bottoming out or
topping out of the mount during machine operation can be minimized
or eliminated. This in turn can help to extend the serviceable life
of the mount. Moreover, by monitoring the relative displacement of
the pin with regard to the housing, a diagnostic can be generated
indicating when an elastomeric member of the mount, or the mount
itself, should be replaced.
[0078] The teachings of the present disclosure may also be used to
construct a machine that provides increased feedback to the
operator. By stiffening the mounts, the operator will more acutely
feel vibrations which can prove valuable in performing tasks, such
as fine grading, plowing, or excavating, or sensing conditions such
as track slippage. Conversely, when roading the mounts can be
relaxed to decrease feedback and thus provide better operator
comfort.
[0079] The present disclosure also has applicability in providing a
machine mount control system wherein an operator can select a
desired hardness or feedback level through an appropriate operator
interface. Such an operator interface can also allow the operator
to select the type of task being performed and the control system
can then set the mount accordingly.
[0080] Sensors can also monitor the positions or speeds of the
machine or implements to then predict the type of task being
performed. Once predicted, the appropriate mount settings can be
used. Such a predictive algorithm approach can not only use machine
sensed parameters, but utilize global positioning satellite and
other mapping technology as well to predict the task and desired
mount settings.
* * * * *