Note: Descriptions are shown in the official language in which they were submitted.
a
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Description
MOTOR GRADER STEERABLE BY A JOYSTICK
AND A STEERING WHEEL
Technical Field
This invention relates generally to a motor
grader and specifically to a motor grader that
includes dual steering controls.
Background Art
This invention relates generally to a motor
grader that includes two mechanisms for controlling
the steering of the motor grader.
Motor graders include many hand-operated
controls to perform functions such positioning an
implement or a blade in several orientations,
articulating the frame of the grader, and adjusting
other grader settings. In most graders steering is
accomplished by means of a steering wheel that acts
through the hydraulic system of the motor grader.
Current motor graders require numerous hand-
operated controls because typically each hand-operated
control is used to control only one or two functions.
Often, the operator of the motor grader must steer the
grader while performing many other functions, such as
adjusting the blade tip, adjusting the blade angle
relative to the frame, and adjusting the articulation
of the grader frame. Performing all of these
functions using hand-operated controls while steering
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the vehicle with the steering wheel is difficult,
inefficient, and fatiguing for the operator. The
operator must frequently remove one or both hands from
the steering wheel to operate the other controls. To
reduce difficulty, increase efficiency, and reduce
operator fatigue, it is desirable to provide an
apparatus that permits an operator to steer a motor
grader without requiring the operator to release the
hand-operated controls that control motor grader
implements. Also it is desirable to provide an
apparatus that is ergonomically advantageous for
controlling both steering and these other functions.
Disclosure of the Invention
The present invention provides an efficient
and ergonomic steering control system for a motor
grader. The system permits the motor grader to be
steered by one of two mechanisms that can be selected
by the operator.
In a preferred embodiment, the steering
mechanism comprises an electro-hydraulic control
system and a joystick that is movable on a plurality
of axes including a first axis. The electro-hydraulic
control system comprises an electronic control
computer, a plurality of electro-hydraulic actuators,
a hydraulic right steering cylinder associated with
one of the plurality of electro-hydraulic actuators
and a hydraulic left steering cylinder associated with
another of the plurality of electro-hydraulic
actuators. The hydraulic right steering cylinder and
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the hydraulic left steering cylinder are each
connected to one of a pair of front tires of the motor
grader. Movement of the joystick a first direction on
the first axis transmits a first electronic input
S signal to the electronic control computer and the
electronic control computer transmits a first control
signal to the electro-hydraulic actuators associated
with the hydraulic right steering cylinder and the
hydraulic left steering cylinder in response to the
first electronic input signal. The first control
signal actuates the electro-hydraulic actuators
associated with the hydraulic right steering cylinder
and the hydraulic left steering cylinder, and the
hydraulic right steering cylinder and the hydraulic
left steering cylinder rotate the pair of front tires
a first rotational direction in response to actuation
of the associated electro-hydraulic actuators by the
first control signal. Movement of the joystick on the
first axis a second direction opposite the first
direction transmits a second electronic input signal
to the electronic control computer and the electronic
control computer transmits a second control signal to
the electro-hydraulic actuators associated with the
hydraulic right steering cylinder and the hydraulic
left steering cylinder in response to the second
electronic input signal. The second control signal
actuates the electro-hydraulic actuators associated
with the hydraulic right steering cylinder and the
hydraulic left steering cylinder and the hydraulic
right steering cylinder and the hydraulic left
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steering cylinder rotate the pair of front tires a
second rotational direction in response to actuation
of the associated electro-hydraulic actuators by the
second control signal. The second rotational
direction is opposite to the first rotational
direction.
In a most preferred embodiment, the steering
control system further includes a steering wheel
hydraulically connected to the hydraulic right
steering cylinder and the hydraulic left steering
cylinder. Rotation of the steering wheel a first
direction actuates the right steering cylinder and the
left steering cylinder to rotate the pair of front
tires the first rotational direction. Rotation of the
steering wheel a second direction actuates the right
steering cylinder and the left steering cylinder to
rotate the pair of front tires the second rotational
direction.
Thus, the present invention permits an
operator to steer a motor grader while maintaining
control of an electronic hand control that is used to
control other motor grader functions. In addition,
the present invention permits the operator to utilize
the steering wheel when it is advantageous.
Brief Description of the Drawings
Figure 1 is a side view of a motor grader;
Figure 2 is a top view of the motor grader;
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Figure 3 is a schematic block diagram of an
electro-hydraulic control system for the motor grader;
and
Figure 4 is a side perspective of an
electronic hand control designed in accordance with
the present invention.
Best Mode for Carrying Out the Invention
Referring to the Figures, wherein like
numerals indicate like or corresponding parts
throughout the several views, a motor grader is shown
generally at 10 in Figures 1 and 2. The motor grader
10 is used primarily as a finishing tool to sculpt a
surface of earth 11 to a final arrangement. Rather
than moving large quantities of earth in the direction
of travel like other machines, such as a bulldozer,
the motor grader 10 moves relatively small quantities
of earth from side to side.
The motor grader 10 includes a front frame
12, a rear frame 14, and a blade 16 having a top 15
and a cutting edge 17. The front and rear frames 12
and 14 are supported by front tires 18 and rear tires
19. An operator cab 20 containing the many controls
including a steering wheel 80 and a plurality of
electronic hand controls 90 necessary to operate the
motor grader 10 is mounted on the front frame 12. An
engine, shown generally at 21, is used to drive or
power the motor grader 10. The engine 21 is mounted
on the rear frame 14. The blade 16, sometimes
referred to as a moldboard, is used to move earth.
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The blade 16 is mounted on a linkage assembly shown
generally at 22. The linkage assembly 22 allows the
blade 16 to be moved to a variety of different
positions with respect to the motor grader 10.
Starting at the front of the motor grader 10 and
working rearward toward the blade 16, the linkage
assembly 22 includes a drawbar 24.
The drawbar 24 is mounted to the front frame
12 with a ball joint. The position of the drawbar 24
is controlled by three hydraulic cylinders, commonly
referred to as a right lift cylinder 28, a left lift
cylinder 30, and a center shift cylinder 32. A
coupling, shown generally at 34, connects the three
cylinders 28, 30, and 32 to the front frame 12. The
coupling 34 can be moved during blade repositioning
but is fixed stationary during earthmoving operations.
The height of the blade 16 with respect to the surface
of earth 11 below the motor grader 10, commonly
referred to as the blade height, is controlled
primarily with the right lift cylinder 28 and the left
lift cylinder 30. Each lift cylinder, 28 and 30,
functions to raise and lower the associated end of the
blade 16. Thus, the right lift cylinder 28 raises and
lowers the right end of blade 16. The center shift
cylinder 32 moves the drawbar 24 from side to side
relative to the front frame 12.
The drawbar 24 includes a large, flat plate
commonly referred to as a yoke plate 36, as shown in
Figure 2. Beneath the yoke plate 36 is a large gear,
commonly referred to as a circle 38. The circle 38 is
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rotated by a hydraulic motor commonly referred to as a
circle drive 40, as shown in Figure 1. Rotation of
the circle 38 by the circle drive 40 pivots the blade
16 about an axis A fixed to the drawbar 24. The blade
16 is mounted to a hinge (not shown) on the circle 38
with a bracket (not shown). A hydraulic blade tip
cylinder 46 is used to pitch the bracket forward or
rearward and thus pitch the top 15 of the blade 16
forward and rearward relative to the cutting edge 17.
The blade 16 is mounted to a sliding joint in the
bracket allowing the blade 16 to be slid or shifted
from side to side with respect to the bracket. A
hydraulic side shift cylinder 50, shown in Figure 2,
is used to control the side to side shift of the blade
16.
Referring now to Figure 2, a right
articulation cylinder, shown generally at 52, is
mounted to the right side of the rear frame 14 and a
left articulation cylinder, shown generally at 54, is
mounted to the left side of the rear frame 14. The
right and left articulation cylinders 52 and 54 are
hydraulic and used to rotate the front frame 12 about
an axis B shown in Figure 1. The axis B is commonly
referred to as the articulation axis. In Figure 2,
the motor grader 10 is positioned in a neutral or zero
articulation angle. The rear tires 19 are driven by a
differential (not shown) as is well known in the art.
Adjacent the front tires is a hydraulic right steering
cylinder 82 and a hydraulic left steering cylinder 84.
The right steering cylinder 82 and the left steering
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cylinder 84 are used to control the position of front
tires 18 and thus steer motor grader 10. In a
conventional motor grader 10 rotation of the steering
wheel 80 is used to actuate the right steering
cylinder 82 and the left steering cylinder 84. As
would be understood by one of ordinary skill in the
art, the front tires 18 could be rotated using only a
single steering cylinder mounted to either the left or
the right front tire 18.
Figure 3 is a schematic block diagram of an
electro-hydraulic control system 60 for the motor
grader 10. The control system 60 is designed to
operate the various hydraulic controls of the motor
grader 10 described above. The system 60 includes a
plurality of electronic hand controls 90 (see
Figure 4) represented by block 62, which transform the
actions of an operators hands on the hand controls 90
into a plurality of electrical input signals. These
input signals carry operational information to an
electronic control computer, represented by block 64.
The control computer 64 receives the
electrical input signals produced by the hand controls
62, processes the operational information carried by
the input signals, and transmits control signals to a
plurality of drive solenoids, each of which is located
in an electro-hydraulic actuator, represented by block
66.
The hydraulic portion of the control system
60 requires both high hydraulic pressure and low pilot
pressure. High hydraulic pressure is provided by a
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hydraulic pump, represented by block 68. The
hydraulic pump 68 receives a rotary motion, typically
from the engine 21 of the motor grader 10, and
produces high hydraulic pressure. Low pilot pressure
is provided by a hydraulic pressure reducing valve,
represented by block 70. The hydraulic pressure
reducing valve 70 receives high hydraulic pressure
from the hydraulic pump 68 and supplies low pilot
pressure to the electro-hydraulic actuators 66.
Each electro-hydraulic actuator 66 includes
an electrical drive solenoid and a hydraulic valve.
The solenoid receives control signals from the
electronic control computer 64 and produces a
controlled mechanical movement of a core stem of the
actuator 66. The hydraulic valve receives both the
controlled mechanical movement of the core stem of the
actuator 66 and low pilot pressure from the hydraulic
pressure reducing valve 70 and produces controlled
pilot hydraulic pressure for hydraulic valves,
represented by block 72.
The hydraulic valves 72 receive both
controlled pilot hydraulic pressure from the electro-
hydraulic actuators 66 and high hydraulic pressure
from the hydraulic pump 68 and produce controlled high
hydraulic pressure for hydraulic actuators, cylinders,
and motors, represented by block 74.
The hydraulic actuators, cylinders, and
motors 74 receive controlled high hydraulic pressure
from the hydraulic valves 72 and produce mechanical
force to move the front frame 12 of the grader 10 and
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several mechanical linkages, represented by block 76.
As described above, movement of the front frame 12 of
the grader 10 with respect to the rear frame 14 of the
grader 10 establishes the articulation angle.
Movement of the mechanical linkages establishes the
position of the blade 16 or other implements.
Each hydraulic actuator, cylinder, and motor
74, such as the lift cylinders 28 and 30 and the
circle drive motor 40, includes an electronic position
sensor, represented by block 78. The electronic
position sensors 78 transmit information regarding the
position of its respective hydraulic actuator,
cylinder, or motor 76 to the electronic control
computer 64. In this manner, the control computer 64
can, for example, determine the articulation angle of
the grader 10 and position the blade 16. With such
information, the control computer 64 can perform
additional operations.
In Figure 4 an electronic hand control is
generally shown at 90. Hand control 90 comprises a
joystick 92. Joystick 92 is movable along a first
axis 94 and a second axis 96, which is generally
perpendicular to the first axis 94. Joystick 92 is
also movable along axes that are intermediate between
the first axis 94 and the second axis 96. Joystick 92
is rotatable about a third axis 98 that is
perpendicular to both first axis 94 and second axis
96. In this specification and the accompanying claims
the phrase movable on an axis encompasses both linear
movement of joystick 92 on either the first axis 94 or
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the second axis 96 and rotation of joystick 92 about
third axis 98.
The hydraulic right steering cylinder 82 and
the hydraulic left steering cylinder 84 are controlled
through the electro-hydraulic control system 60 by
movement of joystick 92 on first axis 94, second
axis 96, or about third axis 98. Both the hydraulic
right steering cylinder 82 and the hydraulic left
steering cylinder 84 are each associated with one of
the electro-hydraulic actuators 66. Movement of
joystick 92 a first direction on one of the axes 94,
96 or 98, transmits a first electronic input signal to
the electronic control computer 64. The electronic
control computer 64 then transmits a first control
signal to the electro-hydraulic actuators 66
associated with the hydraulic right steering cylinder
82 and the hydraulic left steering cylinder 84 in
response to the first electronic input signal. The
first control signal actuates the electro-hydraulic
actuators 66 associated with the hydraulic right
steering cylinder 82 and the hydraulic left steering
cylinder 84. Actuation of these electro-hydraulic
actuators 66 causes hydraulic right steering cylinder
82 and hydraulic left steering cylinder 84 to rotate
the pair of front tires 18 a first rotational
direction. Preferably, the rotation of front tires 18
is intuitive so that, for example, movement of
joystick 92 left or rotation of joystick 92 to the
left rotates front tires 18 to the left. It is to be
understood that a manufacturing decision must be made
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of which axis, first axis 94, second axis 96, or third
axis 98 will be used to control steering. The non-
steering axes are then available for other functions
as described below.
Moving joystick 92 a second direction,
opposite the first direction, on the same axis
transmits a second electronic input signal to the
electronic control computer 64, which then transmits a
second control signal to the electro-hydraulic
actuators 66 associated with the hydraulic right
steering cylinder 82 and the hydraulic left steering
cylinder 84. The second control signal actuates the
electro-hydraulic actuators 66 associated with the
hydraulic right steering cylinder 82 and the hydraulic
left steering cylinder 84 to cause them to rotate the
pair of front tires 18 a second rotational direction
opposite to the first rotational direction. Thus, an
operator can steer the motor grader 10 with out
needing to remove a hand from an electronic control to
rotate the steering wheel 80. The steering wheel 80
can still be used if desired. Rotation of steering
wheel 80 overrides control of steering of motor
grader 10 by joystick 92. Thus, if steering wheel 80
is rotated, front tires 18 are rotated in the
direction indicated by the position of steering
wheel 80 even if the position of joystick 92 would
rotate front tires 18 a different direction.
As described above, joystick 92 is movable
along the first axis 94, the second axis 96, or the
third axis 98. Movement of joystick 92 along either
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of the other axes not used for steering motor
grader 10 also transmits electrical input signals to
the electronic control computer 64. The electronic
control computer 64 then transmits a control signal to
at least one of the electro-hydraulic actuators 66 in
response to each input signal. As described above,
actuating one of the electro-hydraulic actuators 66
actuates either a hydraulic cylinder, a hydraulic
motor, or a hydraulic actuator 74 such as the blade
tip cylinder 46. Movement of joystick 92 along an
axis intermediate to the first axis 94 and the second
axis 96 produces a combination electrical input signal
that reflects proportionally the angle of movement of
the joystick 92 between the first axis 94 and the
second axis 96. The combination signal is used to
simultaneously perform the functions associated with
each axis. Thus, joystick 92 can be used to both
steer motor grader 10 and control other motor
grader 10 functions.
Industrial Applicability
The present invention relates generally to a
steering system for a motor grader 10. Motor
grader 10 is provided with a dual mechanism for
steering control that comprises a joystick 92 and a
steering wheel 80. Joystick 92 is moveable on a
plurality of axes. Movement of joystick 92 in a first
direction on one of the axes transmits a first
electronic input signal to an electronic control
computer 64. The electronic control computer 64
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transmits a first control signal to an electro-
hydraulic actuator 66 associated with a hydraulic
right steering cylinder 82 and an electro-hydraulic
actuator 66 associated with a left steering cylinder
84. The first control signal actuates these electro-
hydraulic actuators 66 and causes the left steering
cylinder 84 and right steering cylinder 82 to rotate
the front wheels 18 of the motor grader 10 a first
rotational direction. Movement of the joystick 92 on
the first axis a second direction, opposite the first
direction, transmits a second electrical input signal
to the electronic control computer 64 which in turn
transmits a second control signal to the electro-
hydraulic actuators 66 associated with the right
steering cylinder 82 and the left steering cylinder
84. Actuation of these electro-hydraulic actuators 66
by the second control signal causes the right steering
cylinder 82 and the left steering cylinder 84 to
rotate the front tires 18 of the motor grader 10 a
second rotational direction opposite the first
rotational direction. In addition, the front tires 18
can be moved in the first rotational direction and the
second rotational direction by rotation of a steering
wheel 80 as is conventional in motor graders.
Movement of the joystick 92 on any of the other axes
also transmits electrical input signals to the
electronic control computer 64 which in turn transmits
appropriate control signals to actuate electro-
hydraulic actuators 66 associated with hydraulic
cylinders, hydraulic actuators or hydraulic motors 74
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that control a variety of other implements on a motor
grader 10. Thus, the present invention enables an,
operator of a motor grader 10 to maintain steering
control of the motor grader 10 while also maintaining
hand contact with implement control levers.
The present invention has been described in
accordance with the relevant legal standards, thus the
foregoing description is exemplary rather than
limiting in nature. Variations and modifications to
the disclosed embodiment may become apparent to those
skilled in the art and do come within the scope of
this invention. Accordingly, the scope of legal
protection afforded this invention can only be
determined by studying the following claims.
