U.S. patent application number 16/995767 was filed with the patent office on 2020-12-03 for vehicle control systems and methods.
The applicant listed for this patent is MTD Products Inc. Invention is credited to Tim Dilgard, Axel Schaedler.
Application Number | 20200377151 16/995767 |
Document ID | / |
Family ID | 1000005021643 |
Filed Date | 2020-12-03 |
View All Diagrams
United States Patent
Application |
20200377151 |
Kind Code |
A1 |
Schaedler; Axel ; et
al. |
December 3, 2020 |
Vehicle Control Systems and Methods
Abstract
Systems for controlling the speed and direction of vehicles such
as tractors, including vehicles that have low to zero turning
radius capability. Systems include steering and speed coordination
systems that control the direction and speed of rotation of vehicle
drive units.
Inventors: |
Schaedler; Axel; (Olmsted
Township, OH) ; Dilgard; Tim; (Ashland, OH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
MTD Products Inc |
Valley City |
OH |
US |
|
|
Family ID: |
1000005021643 |
Appl. No.: |
16/995767 |
Filed: |
August 17, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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16102525 |
Aug 13, 2018 |
10745048 |
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16995767 |
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14613102 |
Feb 3, 2015 |
10046797 |
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16102525 |
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13425095 |
Mar 20, 2012 |
8944191 |
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14613102 |
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12055668 |
Mar 26, 2008 |
8136613 |
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13425095 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
Y10T 74/20073 20150115;
B62D 9/00 20130101; B62D 11/006 20130101; B60K 17/10 20130101; B62D
7/09 20130101; Y10T 74/20012 20150115; B62D 11/02 20130101; B62D
7/08 20130101; B62D 11/24 20130101 |
International
Class: |
B62D 11/00 20060101
B62D011/00; B60K 17/10 20060101 B60K017/10; B62D 7/08 20060101
B62D007/08; B62D 7/09 20060101 B62D007/09; B62D 11/02 20060101
B62D011/02; B62D 11/24 20060101 B62D011/24; B62D 9/00 20060101
B62D009/00 |
Claims
1. A vehicle control system for a vehicle having a steering wheel,
left and right front steerable non-driving wheels, and left and
right rear drivable wheels, the vehicle control system comprising:
a first gear pair that turns the right front steerable non-driving
wheel following a steering input from a steering wheel
corresponding to a zero-radius turn from a straight-ahead position;
a second gear pair that turns the left front steerable non-driving
wheel following the steering input; a pair of links, each link
having a slot that is straight over substantially all of the length
of the slot; a first follower positioned in the slot of one of the
links, the first follower movable in an arc following the steering
input; a second follower positioned in the slot of the other of the
links, the second follower movable in an arc following the steering
input; a pair of speed cams, one speed cam coupled to one of the
links and the other speed cam coupled to the other of the links,
each speed cam including a curved slot and being pivotable
following a speed input from a speed pedal; where pivoting of the
speed cams following the speed input while the first and second
followers are in respective positions corresponding to the
zero-radius turn will cause each link to move in a plane that is
parallel to any flat surface on which vehicle is positioned,
causing the left and right drivable wheels to rotate in opposite
directions.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This is a continuation of co-pending U.S. patent application
Ser. No. 16/102,525, filed Aug. 13, 2018, which will issue as U.S.
Pat. No. 10,745,048, on Aug. 18, 2020, which is a continuation of
U.S. patent application Ser. No. 14/613,102, now U.S. Pat. No.
10,046,747, filed Feb. 3, 2015, which is a continuation of U.S.
patent application Ser. No. 13/425,095, now U.S. Pat. No.
8,944,191, filed Mar. 20, 2012, which is a continuation of U.S.
patent application Ser. No. 12/055,668, now U.S. Pat. No.
8,136,613, filed Mar. 26, 2008, all of which are specifically
incorporated by reference without disclaimer.
BACKGROUND
[0002] Embodiments of the invention relate generally to vehicles
that have low to zero turning radius capability. In the art, zero
turning radius vehicles are often described as ZTR vehicles,
although this name has also been used to described vehicles capable
of a turning radius that is not precisely zero. More specifically,
embodiments of the invention relate to steering systems for such
vehicles, to steering and speed coordination systems for such
vehicles, and to vehicles that comprises one or both types of
systems.
SUMMARY
[0003] Some embodiments of the present vehicle control system
comprise: a steering input member; a first control member
operatively engaged with the steering input member; a first
steering link coupled to the first control member and to a steering
system for a first steered wheel; and a first integration link
coupled to the first control member and to a control system for a
first drive unit. Certain embodiments may also comprise: a second
control member operatively engaged with the steering input member;
a second steering link coupled to the second control member and to
a steering system for a second steered wheel; and a second
integration link coupled to the second control member and to a
control system for a second drive unit. In specific embodiments,
the first drive unit may be a first hydrostatic transmission and
the second drive unit may be a second hydrostatic transmission.
[0004] In particular embodiments, the first control member and the
second control member are laterally oriented. The first and second
integration links may each includes a slot, and the slot may be
straight in certain embodiments. Certain embodiments may also
comprise a first coupling member coupling the first integration
link to the first control member, and a second coupling member
coupling the second integration link to the second control member,
where the first coupling member engages the slot of the first
integration link and the second coupling member engages the slot of
the second integration link.
[0005] In certain embodiments, the first integration link may be
directly coupled to the first control member via the first coupling
member and the second integration link may be directly coupled to
the second control member via the second coupling member. In
particular embodiments, the first and second control members can be
configured to rotate in the same plane in response to a rotation of
the steering input member. In specific embodiments, the steering
input member may be located between the first and second control
members. Particular embodiments may further include a first speed
input member and a first speed input coupling member that couples
the first integration link to the first speed input member. In
specific embodiments, the speed input member may include a slot,
and the first speed input coupling member may translate across the
slot as the steering input member rotates. Certain embodiments may
also include a first speed input coupling member that couples the
first integration link to the first speed input member.
[0006] Some embodiments of the present vehicle control systems
comprise: a steering input member; a first control member
operatively engaged with the steering input member; a first
steering link coupled to the first control member and to a steering
system for a first steered wheel; a first speed input member
coupled to a speed control device; and a first integration link
coupling the first control member to the first speed input member.
In certain embodiments, the first integration link may also be
coupled to a control mechanism for a first drive unit, and the
vehicle control system being may be configured such that a steering
input received through the steering input member is transferred
through the steering input member to the first control member. In
certain embodiments, the steering input may then be transferred
through the first control member to the steering system and through
the first integration link to the first speed input member, which
can then transfer a speed input received from the speed control
device through the first integration link and to the first drive
unit as a driving and steering signal.
[0007] Certain embodiments may also comprise: a second control
member operatively engaged with the steering input member and a
second steering link coupled to the second control member and to a
steering system for a second steered wheel. Particular embodiments
may also comprise a second speed input member coupled to the speed
control device and a second integration link coupling the second
control member to the second speed input member. In specific
embodiments, the second integration link may also be coupled to a
control mechanism for a second drive unit. In particular
embodiments, the vehicle control system may be configured such that
a steering input received through the steering input member is
transferred through the steering input member to the second control
member, then through the second control member to the steering
system for the second steered wheel and through the second
integration link to the second speed input member, which can then
transfer a speed input received from the speed control device
through the second integration link and to the second drive unit as
a driving and steering signal.
[0008] In specific embodiments, a manipulation of the steering
input member while the speed control device is in a neutral
position will not result in a change in the speed input. In the
first drive unit is a first hydrostatic transmission and the second
drive unit is a second hydrostatic transmission. Particular
embodiments may also include a first coupling member coupling the
first integration link to the first control member, and a second
coupling member coupling the second integration link to the second
control member, where the first coupling member engages the slot of
the first integration link and the second coupling member engages
the slot of the second integration link.
[0009] In certain embodiments, the first integration link is
directly coupled to the first control member via the first coupling
member and the second integration link is directly coupled to the
second control member via the second coupling member. In particular
embodiments, the first and second integration links each includes a
slot. In specific embodiments, the slot in the first second
integration link is straight and the slot in the second integration
link is straight.
[0010] In particular embodiments, the first and second control
members are configured to rotate in the same plane in response to a
rotation of the steering input member. In certain embodiments, the
steering input member may be located between the first and second
control members. In specific embodiments, the first and second
speed input members each include a slot. In certain embodiments,
the first speed input coupling member may translate across the slot
as the steering input member rotates.
[0011] Some embodiments of the present vehicle control systems
comprise: a pair of integration links, where each integration link
has a slot that is straight over substantially all of the length of
the slot and each integration is configured to lie in a plane
parallel to any flat surface on which a vehicle that incorporates
the steering control system is used, and each integration link is
configured to transmit a drive signal that is a product of any
received steering input and any received speed input.
[0012] Certain embodiments comprise: a first speed input member
configured to pivot about a first axis; a second speed input member
configured to pivot about a second axis; a first control member
configured to pivot about a third axis; and a second control member
configured to pivot about a fourth axis, where the first, second,
third and fourth axes are parallel to each other and are normal to
any flat surface on which a vehicle that incorporates the steering
control system is used.
[0013] Any embodiment of any of the present systems may consist of
or consist essentially of--rather than
comprise/include/contain/have--the described features. Thus, in any
of the claims, the term "consisting of" or "consisting essentially
of" may be substituted for any of the open-ended linking verbs
recited above, in order to change the scope of a given claim from
what it would otherwise be using the open-ended linking verb.
[0014] Details associated with these embodiments and others are
provided below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] The following drawings illustrate by way of example and not
limitation. Identical reference numerals do not necessarily
indicate an identical structure. Rather, the same reference numeral
may be used to indicate a similar feature or a feature with similar
functionality. Every feature of each embodiment is not always
labeled in every figure in which that embodiment appears, in order
to keep the figures clear. At least FIGS. 2-14 are drawn to scale,
meaning the sizes of the depicted elements are accurate relative to
each other for at least one set of embodiments of the present
devices and systems.
[0016] FIG. 1 is a perspective view of a lawn and garden type
vehicle;
[0017] FIG. 2 is a perspective view of the chassis and control and
steering assemblies of the vehicle of FIG. 1;
[0018] FIG. 3 is a partial perspective view of the control and
steering assemblies of the vehicle of FIG. 1;
[0019] FIG. 4 is a partial exploded view of the control and
steering assemblies of the vehicle of FIG. 1;
[0020] FIG. 5 illustrates a top view of the control and steering
assemblies of the vehicle of FIG. 1 with a neutral steering input
and a neutral speed input;
[0021] FIG. 6 illustrates a top view of the control and steering
assemblies of the vehicle of FIG. 1 with a left turn steering input
and a neutral speed input;
[0022] FIG. 7 illustrates a top view of the control and steering
assemblies of the vehicle of FIG. 1 with a right turn steering
input and a neutral speed input;
[0023] FIG. 8 illustrates a top view of the control and steering
assemblies of the vehicle of FIG. 1 with a neutral steering input
and a forward speed input;
[0024] FIG. 9 illustrates a top view of the control and steering
assemblies of the vehicle of FIG. 1 with a left turn steering input
and a forward speed input;
[0025] FIG. 10 illustrates a top view of the control and steering
assemblies of the vehicle of FIG. 1 with a right turn steering
input and a forward speed input;
[0026] FIG. 11 illustrates a top view of the control and steering
assemblies of the vehicle of FIG. 1 with a neutral steering input
and a reverse speed input;
[0027] FIG. 12 illustrates a top view of the control and steering
assemblies of the vehicle of FIG. 1 with a left turn steering input
and a reverse speed input;
[0028] FIG. 13 illustrates a top view of the control and steering
assemblies of the vehicle of FIG. 1 with a right turn steering
input and a reverse speed input; and
[0029] FIG. 14 illustrates a perspective view of a control
mechanism for a drive unit of the vehicle of FIG. 1.
DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
[0030] The terms "comprise" (and any form of comprise, such as
"comprises" and "comprising"), "have" (and any form of have, such
as "has" and "having"), "contain" (and any form of contain, such as
"contains" and "containing"), and "include" (and any form of
include, such as "includes" and "including") are open-ended linking
verbs. Thus, a vehicle that "comprises" a steering input member; a
first control member operatively engaged with the steering input
member; a first steering link coupled to the first control member
and to a steering system for a first steered wheel; and a first
integration link coupled to the first control member and to a
control system for a first drive unit, is a vehicle that possesses
the listed elements, but is not prohibited from possessing elements
that are not listed (such as an additional steerable
structure).
[0031] Likewise, an element of an apparatus that "comprises,"
"has," "contains" or "includes" one or more features possesses
those one or more features, but is not limited to possessing only
those one or more features. Furthermore, a structure that is
configured in a certain way must be configured in at least that
way, but also may be configured in a way or ways that are not
specified.
[0032] The terms "a" and "an" are defined as one or more than one
unless this disclosure explicitly requires otherwise. The terms
"substantially" and "about" are defined as at least close to (and
includes) a given value or state (preferably within 10% of, more
preferably within 1% of, and most preferably within 0.1% of).
[0033] General Configuration
[0034] Referring now to the figures, FIG. 1 illustrates a vehicle
10, such as a lawn and garden tractor. The vehicle 10 includes a
prime mover 12, such as an engine, that is mounted to a structural
frame or frame 14. The vehicle 10 includes drive wheels 16, such as
left and right rear drive wheels that are coupled to the frame 14.
The drive wheels 16 are operatively coupled to the engine 12
through a transmission system to provide locomotion to the vehicle
10. The vehicle 10 also has steerable structures 18, such as right
and left front ground-engaging wheels, which may be non-driving
wheels. Other embodiments of the vehicles have only one steerable
structure (e.g., three-wheeled all-terrain vehicles). Furthermore,
in some embodiments, steerable structures such as skis may be used
instead of wheels.
[0035] The frame 14 supports an operator station comprising a seat
22. Vehicle 10 also includes a mower deck 26 mounted to the vehicle
10 in any suitable manner. In some embodiments, the invention is
applicable to other types of vehicles, including but not limited to
utility vehicles, off road vehicles, tractors, golf carts, and even
automobiles.
[0036] As shown in FIGS. 1-2, the front wheels 18 are coupled to
the frame of the vehicle through a pivotable connection to a front
axle 19 mounted on the frame 14. The front wheels 18 are also
coupled to a steering assembly 20, which is configured to control
the direction they turn as discussed more fully below. In the
embodiment of the present vehicles shown in the figures, the front
wheels are the steerable wheels 18 and the rear wheels are the
drive wheels 16. However, one skilled in the art will understand
that the rear wheels may be the steerable wheels and the front
wheels may be the drive wheels in other embodiments. Likewise, the
front wheels may be both the steerable wheels and the drive
wheels.
[0037] A steering input device 24 (which is part of the embodiment
of the steering assembly 20 shown in the figures) and a speed
control device 28 (which is part of the embodiment of the speed
control assembly 21 discussed below) are located near the seat 22
(FIG. 1) so that they are accessible to the operator of the
vehicle. An operator may apply a steering input to the steering
input device 24, which transfers the steering input to the steering
assembly 20. Steering input device 24 may take the form of a
conventional steering wheel. However, the steering input device 24
may be another suitable steering device, including, but not limited
to, a steering rod or joystick (not shown).
[0038] The speed control device 28 provides a speed input to the
balance of the speed control assembly 21, and (at least in part)
regulates the forward and reverse speed of the vehicle 10. Speed
control device 28 may take the form of a single pedal, such as a
treadle pedal arrangement mounted on a single shaft. In such an
embodiment, the speed control device 28 is rocked forward to select
forward drive, or rocked backward to select reverse drive. The
speed control device 28 may be biased toward a central position
that corresponds to a neutral or stationary condition.
[0039] Vehicle 10 also includes a control system 40 that is
configured to integrate a steering input received by the steering
assembly 20 via the steering input device 24 with a speed input
received by the speed control assembly 21 (discussed below) via the
speed control device 28 to drive and steer the vehicle 10. The
configurations of the present steering assemblies, speed control
assemblies and integration devices allow the vehicle to make small-
to zero-radius turns.
[0040] The left and right drive wheels 16 are driven through a
transmission system that, in the depicted embodiment, comprises
left and right drive units 29. Vehicle 10 includes a speed control
assembly 21 that controls the direction and magnitude of rotation
of the rear drive wheels 16. The drive units 29 may be
transmissions of the continuously variable type, capable of
providing a continuous range of ratios from forward to reverse.
Examples of a suitable transmission utilizing a ratio
varying-device, or variation, in conjunction with an epicyclic
shunt gear to provide a geared neutral facility is described in
International Application PCT/GB03/00332, published under WO
03/064892, and International Application PCT/GB03/02332, published
under WO 03/100295, both of which are incorporated by reference for
those descriptions. Alternately, the drive units 29 may be
hydrostatic transmissions (HST) or electric motors, both of which
are well known in the art. The drive units 29 may be used to
independently drive the drive wheels 16.
[0041] The driver dictates the speed and direction of the vehicle
10 by manipulating the steering input device 24 and the speed
control device 28, which transmit the steering and speed inputs
received from the driver to control system 40. The manner in which
the steering and speed control assemblies work together through
control system 40 to drive and steer the vehicle is described in
more detail below. In the embodiment of vehicle 10 shown in the
figures, the amount of torque that the rear drive wheels must
produce to turn the vehicle 10 is reduced because front wheels 18
are steerable. In contrast, the drive wheels 16 of some
conventional ZTR vehicles with non-steerable castor wheels must
produce significant torque to cause the castor wheels to react and
point in the desired direction. Furthermore, a certain amount of
familiarity and skill is required to prevent skidding the inboard
drive wheel and tearing the grass under the wheel.
[0042] In the embodiment of vehicle 10 shown in the figures, the
right and left drive wheels 16 are coupled to frame 14 such that
their direction is fixed and their rotational axes are in constant
alignment. In contrast, the front steerable wheels 18 are coupled
to the frame 14 in a way that gives them the ability to change
direction. The use of a substantially-true Ackermann steering
geometry (which can be achieved using some of the embodiments
discussed below) can help to avoid scrubbing rubber from the tire
tread on the outboard wheel or damaging vegetation under the front
wheels.
[0043] Steering Assembly
[0044] Aspects of steering assembly 20 are depicted in, e.g., FIGS.
2-13. One function of the steering assembly 20 is to couple the
steering input device 24 to the front steerable wheels 18 to aid in
guiding vehicle 10. Another function of the steering assembly 20 is
to provide a steering input to the control system 40, which can
coordinate that steering input with a speed input received through
speed control device 28. Another function of the steering assembly
20 is its ability to turn the vehicle 10, even in a zero turning
radius mode (or a small turning radius mode), while receiving an
input from a conventional steering input device such as a steering
wheel.
[0045] In one embodiment, the steering assembly 20 includes a
steering shaft 30 extending downwardly from the steering input
device 24 and terminating in a steering input member 32. In certain
exemplary embodiments steering input member 32 may be a pinion gear
or other device suitable for imparting motion from the steering
input device 24 to downstream components (as discussed more fully
below). The steering shaft 30 is rotatably coupled to the frame 14
with a bushing 34 or any other suitable means. The steering shaft
30 and steering input member 32 take the steering input received
through the steering input device 24 and take part in transmitting
it to front wheel assemblies 50, which convert the steering input
into desired steering angles of the front wheels 18, as explained
below. In certain exemplary embodiments, front wheel assemblies 50
are configured to provide Ackermann steering so that the inner
front wheel turns about a smaller radius than the outer front
wheel.
[0046] In one embodiment, the coupling between the steering shaft
30 and the front wheel assemblies is accomplished using, in part,
left and right control members 36. In certain exemplary
embodiments, control members 36 have a toothed or geared surface on
part of their outer circumference. In specific exemplary
embodiments, control members 36 are laterally oriented so that they
move in a plane generally horizontal or parallel to the ground
below vehicle 10. The steering input member 32 is positioned
between, and simultaneously engages, the left and right control
members 36 such that rotation of the steering input member 32
causes simultaneous rotation of the left and right control members
36. In certain exemplary embodiments, the steering input device 24
and steering input member 32 may be rotated through about 120
degrees of movement. For example, the steering input device 24 may
be selectively rotated 60 degrees in a first direction with respect
to a neutral steering position and 60 degrees in a second
direction. However, the steering input device 24 and steering input
member 32 may be configured for rotation through any range of
angles suited to a given application.
[0047] Rotating the steering input device 24 and steering input
member 32 in a first direction causes one of the control members 36
to rotate clockwise and the other control member 36 to rotate
counter-clockwise (when viewed from above vehicle 10). The left and
right control members 36 are coupled to right and left steering
links 42 and right and left integration links 44. In exemplary
embodiments, both right and left steering links 42 and right and
left integration links 44 are closely coupled to control members
36. In specific exemplary embodiments, the ends of steering links
42 that are closest to control members 36 are approximately 0.5 to
2.0 centimeters from control members 36 (shown as dimension B in
FIG. 3). In certain embodiments, control system 40 can be
configured so that steering link 42 is closely spaced to control
member 36. Such a configuration may reduce a torque that steering
link 42 can place on control member 36 during operation, which
could tend to twist control member 36 out of the horizontal plane.
In addition, steering link 42 may pass underneath integration link
44 in some positions (shown in FIG. 6, for example). Therefore,
reducing the space between control member 36 and steering link 42
can reduce the distance needed between control member 36 and
integration link 44.
[0048] In addition, integration links 44 are spaced approximately
1.0 to 3.0 centimeters from control members 36 (shown as dimension
C in FIG. 3) in specific exemplary embodiments. The lateral
orientation of components such as control members 36 and
integration links 44 can reduce the amount of space that steering
assembly 20 and control system 40 occupy. Preferably, the right and
left sides of the steering assembly 20 are substantially identical
but mirror images of each other.
[0049] As control members 36 rotate, right and left steering links
42 are also shifted longitudinally (towards the front or back of
vehicle 10) and laterally (towards one side of vehicle 10). As
shown in FIG. 5, the ends of steering links 42 that are opposite of
control members 36 are coupled to front wheel assemblies 50.
Therefore, steering links 42 can be moved to manipulate front wheel
assemblies 50
[0050] Speed Control Assembly
[0051] Referring now to FIG. 2, speed control assembly comprises
speed control device 28 coupled to rod 81 and lever 82. As speed
control device 28 is rotated forward or backward, so are rod 81 and
lever 82, which is oriented perpendicular to rod 81. For purposes
of this discussion, "forward" rotation is clockwise rotation when
viewed from the right side of vehicle 10, and "backward" rotation
is counter-clockwise rotation when viewed from the right side of
vehicle 10. Lever 82 is in turn pivotally coupled to link 83, which
is perpendicular to both lever 82 and rod 81, and which is also
coupled to speed input member 48. Link 83 is pivotally coupled to
speed input member 48 at a point proximal to outer end 51 of a slot
47. Although not visible in FIG. 2, left side speed input member 48
has linkage that is equivalent to, but a mirror image of, the
linkage coupling rod 81 to right side speed input member 48.
[0052] As shown in FIG. 3, slot 43 comprises a center axis 143 that
forms an angle A with a line 147 that is tangential to the arc
formed by slot 47. Line 147 is drawn to form a tangent with slot 47
at approximately the point where integration link 44 is coupled to
slot 47. In the embodiment shown in FIG. 3, angle A is
approximately 90 degrees when speed input member 48 is in the speed
neutral position. As steering input device 24 is manipulated to
provide a steering input, integration link 44 will be moved so that
it is coupled to slot 47 at a different location than that shown in
FIG. 3. As integration link 44 moves, the angle between center axis
143 and line 147 will not be changed if speed input member 48 is in
the speed neutral position. However, if speed input member 48 is
not in the speed neutral position, the angle between center axis
143 and line 147 will change as steering input device 24 is
manipulated to provide a steering input. In exemplary embodiments,
the angle between center axis 143 and line 147 will vary from
between approximately 70 and 110 degrees. A biasing member 63 is
coupled to a neutral lever 64 and biases speed input members 48 to
the neutral position when a user does not provide a speed
input.
[0053] As shown in FIGS. 2 and 3, right and left speed input
members 48 each comprise a pivot member 84 that extends through the
bottom portion of speed input member 48. As a result, when speed
control device 28 is rotated forward, speed input members 48 will
pivot or rotate about pivot member 84 so that an outer end 51 of
slot 47 is also moved forward and inner end 49 is moved backward.
Furthermore, as speed control device 28 is rotated backward, speed
control assembly 21 will cause speed input member 48 to pivot so
that outer end 51 is also moved backward and inner end 49 is moved
forward.
[0054] As steering input device 24 is rotated to initiate a turn,
steering shaft 30, steering input member 32, and control members 36
also rotate about pivot members 39. Pivot members 84 (for speed
input members 48) and pivot members 39 (for control members 36) are
oriented normal to a laterally-oriented plane that includes frame
14. As a result, speed input members 48 and control members 36
rotate about axes that are parallel to each other and normal to a
flat surface on which a vehicle incorporating control system 40 is
used. In the embodiment shown, integration links 44 are comprised
of upper and lower halves (shown in the exploded view in FIG. 4)
with slots 43. In certain embodiments, integration links 44 are
coupled to control members 36 via coupling members 45 that engage
the slots 43 in integration links 44 and holes (not visible) in
control members 36. In certain embodiments, slots 43 are straight
and allow coupling members 45 to move in a linear path. In some
embodiments, coupling member 45 can directly couple integration
link 44 to control member 36 by extending vertically through a
portion of both integration link 44 and control member 36. Coupling
members 45 may be bolts or pins with threaded ends that may be
coupled to integration links 44 with nuts 46 and guide members 57.
In other embodiments, coupling member 45 may be permanently
attached to control member 36 (for example, through brazing or
welding) and extend through slot 43 to directly couple control
member 36 and integration link 44. In still other aspects, coupling
member 45 may be integral to coupling member 36 and directly couple
control member 36 to integration link 44 by extending through slot
43.
[0055] In the depicted embodiments, coupling members 45 are coupled
to control members 36, so that as control members 36 rotate,
coupling members 45 move in an arc, which movement includes both a
forward or a backward component (towards the front or back of
vehicle 10) and a lateral component (towards one side of vehicle
10). As a result, coupling members 45 can slide forward or back
within slots 43 and can also cause integration links 44 to
translate in a sideways manner by exerting a force on the side of
slots 43.
[0056] Integration links 44 are also coupled to speed input members
48 via speed input coupling members 85. In one embodiment, speed
input coupling members 85 are pins that extend vertically through
integration links 44 and speed input members 48.
[0057] Coupling members 45 act on right and left integration links
44, which are translated so that they engage slots 47 of speed
input members 48 in different locations within slots 47. For
example, when steering input device 24 is placed in a neutral
position as shown in FIG. 5, integration links 44 are arranged so
that they are proximate to the inner ends 49 of slots 47. However,
as steering input device 24 is turned to the left as shown in FIG.
6, left integration link 44 (and speed input coupling member 85) is
moved proximate to outer end 51 of slot 47, while right integration
link 44 is moved sideways toward outer end 51 to a lesser degree.
Similarly, when steering input device 24 is turned to the right, as
shown in FIG. 7, right integration link 44 is moved proximate to
outer end 51 of slot 47, while left integration link 44 is moved
sideways toward outer end 51 to a lesser degree.
[0058] As discussed more fully below, the manipulation of speed
control device 28, along with steering input device 24, affects the
rotational speed of drive wheels 16.
[0059] Control System
[0060] FIGS. 5-7 illustrate views of control system 40 in a neutral
speed position for speed control device 28 and with different
steering inputs from steering input device 24. With speed control
device 28 in a neutral speed position, control system 40 is
configured so that manipulation of steering input device 24 does
not cause right or left integration link 44 to be shifted towards
the front or rear of vehicle 10. For example, each slot 47 is
slightly curved at a radius equivalent to the combined effective
length of integration link 44 and drive rod 104 (i.e., the distance
between slot 47 and the connection point where drive rod 104
connects to drive unit 29). Therefore, right and left drive units
29 will not be manipulated to cause rotation of either drive wheel
16 based on a steering input alone. The relationship between the
position of integration links 44 and the output of drive units 29
is discussed more fully below.
[0061] As shown in FIG. 14, integration link 44 is coupled to a
drive rod 104, which is in turn coupled to a control mechanism 106
for drive unit 29. Integration link 44 and drive rod 104 may be
integral components in certain exemplary embodiments. As explained
more fully below, integration link 44 delivers an integrated
steering and speed signal to drive unit 29 that controls the
rotational speed and direction of the attached drive wheel 16. The
integrated steering and speed signal is affected by the steering
input from steering input device 24 and the speed input of speed
control device 28.
[0062] Integration link 44 can be moved from a neutral position
longitudinally toward drive unit 29 (i.e., toward the rear of
vehicle 10). With such movement, control mechanism 106 is
manipulated so that drive unit 29 rotates its corresponding drive
wheel 16 in a forward direction. Conversely, if integration link 44
is moved away from drive unit 29 from a neutral position, control
mechanism 106 is manipulated so that drive unit 29 rotates drive
wheels 16 in a reverse direction. If integration link 44 is not
moved from a neutral position longitudinally toward or away from
drive unit 29, control mechanism 106 will not be manipulated.
Consequently, drive unit 29 will not cause forward or reverse
rotation of drive wheel 16. In other embodiments, drive rod 104 may
be coupled to control mechanism 106 such that rearward movement of
integration link 44 causes reverse, rather than forward, rotation
of drive wheel 16 (and forward movement of integration link 44 may
cause forward rotation of drive wheel 16).
[0063] FIGS. 8, 9 and 10 illustrate views of control system 40 with
a full forward speed input from speed control device 28 and
neutral, left turn, and right turn steering inputs, respectively,
from steering input device 24. As shown in the comparison of FIGS.
5 and 8, when speed control device 28 is provided with a forward
speed input, outer ends 51 of slots 47 are moved towards the front
end of vehicle 10, and inner ends 49 of slots 47 are moved towards
the rear of vehicle 10.
[0064] As shown in FIG. 8, with neutral steering and full forward
input from speed control device 28, both integration links 44 are
pushed toward the rear of vehicle 10 an equal amount. With right
and left integration links 44 moved from a speed-neutral position
toward drive units 29, both drive units 29 will cause drive wheels
16 to rotate in a forward direction. As shown in FIG. 8, steering
input device 24 is in a neutral position, therefore both front
wheel assemblies 50 are positioned so that the front wheels 18 (not
shown in FIG. 8) would direct vehicle 10 straight ahead. In FIG. 8,
each integration link 44 is placed in an equivalent relative
position within slot 47. Therefore, each integration link 44 is
moved an equivalent amount towards the rear of vehicle 10 when
speed control device 28 is manipulated. As a result, the drive
units 29 are manipulated to rotate drive wheels 16 at equivalent
rotational speeds. Drive wheels 16 will therefore work in
conjunction with front wheels 18 to cause vehicle 10 to maintain a
path straight ahead.
[0065] However, as steering input device 24 is manipulated to cause
a right or left turn for vehicle 10, control system 40 causes right
and left drive wheels 16 to rotate at different speeds. By rotating
the right and left drive wheels 16 at different speeds, the drive
wheels are able to assist vehicle 10 in turning. In particular, the
outside drive wheel 16 (the drive wheel farthest from the center of
the turning arc) can rotate at a faster rotational speed than the
inside drive wheel. In sharp turns, the outside and inside drive
wheels may also rotate in opposite directions. When the rotation of
right and left drive wheels 16 is coordinated with the angle of
front wheels 18, vehicle 10 can make small- or zero-radius turns
and reduce the likelihood of a wheel skidding and damaging the turf
or vegetation below vehicle 10.
[0066] Referring now to FIG. 9, speed control device 28 is placed
in the full forward position, and steering input device 24 has been
manipulated so that control system 40 and steering assembly 20
configure front wheel assemblies 50 for a left turn. Control system
40 is therefore configured for a full-forward speed left turn in
FIG. 9. Comparing FIG. 9 (full-forward speed left turn) to FIG. 6
(neutral speed input, left turn), right integration link 44 has
been shifted rearward from the neutral position in FIG. 9. In
addition, left integration link 44 has been shifted forward. As a
result, right drive wheel 16 will rotate in a forward direction,
while left drive wheel 16 will rotate in a reverse direction. This
combined rotation of the drive wheels 16 in opposite directions
will assist vehicle 10 in making a small- or zero-radius turn.
[0067] As shown in FIGS. 8 and 9, outer ends 51 (rather than inner
ends 49) of slots 47 are closer to the front of vehicle 10.
Therefore, as steering input device 24 is turned and integration
links 44 are translated sideways, integration links 44 and drive
rods 104 will also be moved forward towards the front of vehicle
10. Each control mechanism 106 will therefore also be rotated away
from its respective drive unit 29, so that the forward rotational
speed of each drive wheel 16 is reduced. The geometry of control
system 40 is such that integration link 44 associated with inner
drive wheel 16 will be shifted forward more than integration link
44 associated with outer drive wheel 16. Consequently, the forward
rotational speed of inner drive wheel 16 will be reduced more than
that of outer drive wheel 16. When steering input device 24 is
provided with a sufficient amount of input, the inner drive wheel
16 will eventually cease forward rotation and begin reverse
rotation. This combined rotation of the drive wheels 16 in opposite
directions will assist vehicle 10 in making a small- or zero-radius
left turn.
[0068] Referring now to FIG. 10, control system 40 is configured
for a full-forward speed input and a full right turn. This
configuration is equivalent to FIG. 9, with the exception that
steering input device 24 (shown in FIG. 3) has been turned to the
right instead of the left. In this configuration, right integration
link 44 is positioned so that right drive unit 29 will provide a
reverse rotation of inner (right) drive wheel 16. Vehicle 10 can
therefore perform a small- or zero-radius turn to the right.
[0069] Referring now to FIGS. 11-13, speed input member 28 has been
positioned to provide a reverse speed input to control system 40.
In FIG. 11, control system 40 is configured for a neutral steering
input. In FIGS. 12 and 13, control system 40 is configured for a
left-turn and a right-turn, respectively. In FIGS. 11-13, speed
input members are positioned so that inner ends 49 (rather than
outer ends 51) are closer to the front of vehicle 10. Therefore, as
integration links 44 move outward in response to a steering input,
they will also move backward toward the rear of vehicle 10. As a
result, control mechanism 106 will reduce the reverse rotational
speed of each drive wheel 16. If a sufficient steering input is
provided, integration link 44 associated with inside drive wheel 16
will be pushed far enough rearward to cause inside drive wheel to
cease reverse rotation and begin forward rotation. Inside drive
wheel 16 can therefore rotate forward and outside drive wheel 16
can rotate in reverse during a full turn with a reverse speed
input.
[0070] In FIG. 12, control system 40 is positioned for a left turn
and speed control device 28 is positioned for a reverse speed
input. The left integration link 44 is pushed sufficiently rearward
so that left (inside) drive wheel 16 will rotate forward. Right
integration link 44 is placed sufficiently forward so that outer
(right) drive wheel 16 will rotate in reverse. With this
configuration, vehicle 10 can make a small or zero-radius reverse
left turn.
[0071] Referring now to FIG. 13, control system 40 is positioned
for a right turn with speed control device 28 providing a reverse
speed input. The right integration link 44 is pushed sufficiently
rearward so that right (inside) drive wheel 16 will rotate forward.
Left integration link 44 is placed sufficiently forward so that
outer (left) drive wheel 16 rotates in reverse. With this
configuration, vehicle 10 can make a small- or zero-radius reverse
right turn.
[0072] Descriptions of well known manufacturing and assembly
techniques, components and equipment have been omitted so as not to
unnecessarily obscure the present systems and devices in
unnecessary detail. Further, the present systems and devices are
not intended to be limited to the particular forms disclosed.
Rather, they are to cover all modifications, equivalents, and
alternatives falling within the scope of the claims.
[0073] For example, the control members may be configured
differently than shown in the figures. In alternative embodiments,
the control members may be segments of a circle rather than a
complete circle. Furthermore, the drive rods and the integration
links may be a single component rather than separate components.
Moreover, the guide members for the integration links may engage
the slots in the integration links rather than the outer portions
of the integration links. In still other embodiments, the linkage
coupling the speed control device to the speed input members may be
a different configuration from that shown. For example, the linkage
may be coupled to a single speed input member, which in turn
provides an input to the other speed input member via a geared
engagement at the ends of the speed input members.
[0074] The appended claims are not to be interpreted as including
means-plus-function limitations, unless such a limitation is
explicitly recited in a given claim using the phrase(s) "means for"
and/or "step for," respectively.
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