Note: Descriptions are shown in the official language in which they were submitted.
CA 02637823 2008-07-30
Description
Technical Field
The present invention is a planetary drive system primarily used in vehicles
that operate
on multiple terrains such as asphalt roads, agricultural farms and
construction sites. It
gives the vehicle the ability to select between driving units to best
negotiate the different
underlying terrain. For example, it can use rubber tires on road and crawler
tracks off-
road. A choice of driving units may also be required in the case of multi-
purpose
vehicles.
Background and prior art
Application and underlying terrain mainly dictate the choice of the driving
unit for a
vehicle. Vehicles operating on multiple underlying terrain and/or being used
for multiple
applications have an inherent need for conversion between driving units for
optimum
performance. For instance, farm tractors would be functionally at their best
on steel
crawler tracks when off-road in the fields and would be ideally on rubber
tires while
plying on road. Hence the utility of these vehicles is significantly enhanced
when the
vehicle has the ability to change drives, tires to crawler tracks and vice
versa.
In the prior art, attempts have been made to enhance the utility of vehicles
with
modifications such as fitting steel crawler tracks with rubber pads while
plying on road,
rubber tires fitted with circumventing steel chains while on snow, removable
rubber
tracks fitted on tandem rubber wheels and many more. In all these known
attempts, the
changeover is cumbersome and time-consuming with limited improvements.
The present invention caters to the need for selection between multiple drives
that should
be easy for changeover and should avoid involvement of assembly, disassembly
and/or
modification.
Summary of the Invention
The concept of the present invention resides in a planetary drive system. A
vehicle could
have one or more such planetary drive systems fitted on the rear, front and/or
intermediate axles.
The planetary system comprises of multiple drive units such as a rubber tire,
roller and/or
chain crawler arranged in a planetary manner about an axis of rotation X. The
planetary
system is able to rotate about the axis X, resting the vehicle on the
underlying surface
using any one or more of the drives. For example, the vehicle operator can
select crawler
tracks for use in fields and when the vehicle comes on asphalt road he can
select rubber
tires.
The invention is described in greater detail in the subsequent section with
reference to
exemplary embodiments, which are illustrated in drawings, in which:
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Fig. I shows the plan and side view of two positions of a farm tractor fitted
with two
planetary drive systems at both ends of the rear axle. Position A shows the
vehicle driven
on crawler tracks and Position B shows the vehicle on rubber tires.
Fig. 2 shows various stages during conversion of the tractor in figure 1, from
a crawler
track driven vehicle to a rubber tire driven vehicle.
Fig. 3 shows side view and plan view of the farm tractor for detailed
explanation of
mechanisms in the exemplary embodiment.
Fig. 4 shows sectional view J-J of the planetary drive system shown in figure
3.
Fig. 5 shows sectional view J-J of an exemplary embodiment of the rear axle
fitted with
planetary drive systems at both ends and differential unit in the center.
Fig. 6 shows a vehicle fitted with four planetary drive systems at both ends
of front and
rear axles.
Fig. 7 shows an exemplary embodiment of the planetary drive system with two
planets,
rubber tire and crawler tracks, angular spaced at 150 degrees from each other
demonstrating that the planets are not constrained to being diametrically
opposite to each
other as in fig 3.
Fig. 8 shows the planets with different orbital planes V and W, demonstrating
that the
orbital planes of the planets need not be aligned to each other and can be
laterally spaced
in the direction of the axis X, but still constitute as planets of the
planetary drive system.
Fig. 9 shows a planetary drive system with three planets, a crawler track, a
rubber tire and
steel roller in different drive selection positions. In position CC, two
drives are selected at
one point of time for driving the vehicle demonstrating that multiple drives
can be used
simultaneously.
Fig. 10 shows an exemplary embodiment of the planetary drive system with two
planets,
a rubber track and a rubber tire.
Fig. 11 shows an exemplary embodiment planetary drive system with two planets,
a
rubber tire and a steel roller.
Fig. 12 shows an exemplary embodiment of planetary drive system with three
planets, a
rubber tire, a steel roller and a stone wheel. Position QQ demonstrates the
use of two
drives selected simultaneously for driving the vehicle.
Fig. 13 shows an exemplary embodiment with two planets, a rubber tire and a
steel roller
driven by means of independent hydraulic motors.
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Fig. 14 shows an exemplary embodiment of planetary drive system with two
planets, a
rubber tire and a steel roller. Here the axis X of the planetary drive system
is not the same
as centerline Y of the vehicle axle demonstrating that the rotational axis X
of the
planetary drive system is not constrained to alignment with the vehicle axle
centerline.
Description of the preferred embodiments
In figure 1, a farm tractor 3 fitted with two planetary drive systems 4 fitted
at each of the
two ends of the rear axle is shown. In position A, the tractor is driven on
steel crawler
tracks and on rubber tires in position B. The front axle has rubber tires like
any other
conventional farm tractor. In this embodiment, each planetary drive system 4
consists of
two driving units: a steel crawler track 1 and a rubber tire 2, arranged like
planets in orbit
about the axis X. In position A, the planetary drive systems are resting on
crawler tracks
and hence the tracks provide drive to the tractor in this position. Each
planetary drive
system is able to rotate independently about axis X, so as to changeover from
crawler
drive 1 in position A to tire drive 2 in position B. The detailed mechanism of
the
planetary drive system is explained in subsequent paragraphs of the
description. The
changeover capability facilitates selection between driving units in the
planetary
arrangement that forms the core of this invention.
In figure 2, the stages of conversion of planetary drive system from crawler
track drive 1
in position C to rubber tire drive 2 in position F are shown. During
conversion of drives,
the farm tractor 3, on crawler track 1 in position C, is first brought to a
halt resting on
firm ground. The rear axle of the tractor 3 is lifted as shown in position D
using a
mechanical or hydraulic lifting jack 5. Such lifting jacks are known in
principle and not
discussed, as they are not of interest here. The rear axle is lifted to a
height so that the
entire planetary drive system has room to make a 180-degree turn about axis X.
A
hydraulic motor driven pinion-gear arrangement (items 6, 7 and 14 in figures 3
and 4) is
used to rotate the planetary drive system about axis X through 180-degrees in
the
counter-clockwise direction as shown in position E so that rubber tire 2 now
takes the
position of crawler tracks. The lifting jack 5 is lowered so that the tractor
rear axle rests
on rubber tires 2 as shown in position F.
Similarly the planetary drive system can change over from rubber tire drive 2
in position
F to crawler track drive 1 in position C as shown in stages G and H by
rotating the
planetary drive system in clockwise direction about axis X.
This change over illustrated in positions C, D, E, F, G and H constitutes a
complete
change over from crawler track drive to tire drive and vice versa. The ease
and flexibility
of selection between drives in the planetary drive system is one of the key
concepts of the
present invention.
In figures 3, 4 and 5, the detailed mechanism of planetary drive system 4
mentioned in
the above section is shown. The farm tractor 3 is driven on crawler tracks 1
of planetary
drive system 4 in figure 3 Section J-J of one planetary drive system is shown
in figure 4.
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Figure 5 shows section J-J across the entire rear axle of tractor 3 with two
planetary
systems at both ends and differential unit in the center.
As shown in figure 4, two transmission chain sprockets 11 and 18, fitted at
the outward
end of rear axle 12, provide drive to driving units 1 and 2 of the planetary
drive system
respectively. Sprocket 18 drives the rubber tire axle by means of transmission
chain 20
and sprocket 9. Similarly sprocket 11 drives the crawler track-driving
sprocket by means
of transmission chain 8 and sprocket 10. Fabricated frame 19 holds the entire
assembly of
the planetary driving system. This frame is supported on bearings 21 and 22 on
the rear
axle housing 13 so that it is free to rotate relative to the rear axle housing
during drive
change over. The frame 19 has bearing housing 15 for rubber tire 2 and crawler
track
carriage 23. The frame 19 has gear 7 that meshes with the pinion 6 driven by
hydro-
motor 14. this hydro-motor is fixed to the rear-axle housing 13 (mounting not
shown in
the drawing) so that frame 19 can be rotated relative to the rear axle housing
when the
motor 14 is actuated. The rear ale 12 is supported on outer-end bearings 24 in
rear axle
housing 13.
In figure 5, the other end of the rear axle is shown coming out of rear axle
differentia125.
This gives an idea of the rear axle of farm tractor 3 fitted with planetary
drive systems at
both ends. While the vehicle is moving, sprocket 18 drives sprocket 9 that
drives the
chain track propelling the vehicle in desired direction. When the drive system
is jacked
up for change over between drives, hydro-motor 14 is actuated to cause the
pinion 6 and
gear 7 to rotate, hence rotating the entire drive system through desired angle
for drive
selection. In this arrangement, the tire 2 and crawler track 1 are always in
motion when
the vehicle is moving though only one of them is in contact with the
underlying surface.
In practice, the drive that is not in use, i.e. not in contact with the
underlying surface, can
be disengaged using a mechanism that is not discussed since it is known in
principle and
not of interest here. Also not discussed over here are mechanisms for braking,
idler
sprockets that maintain tension in transmission chains and transfer of power
from the
differential to the rear axle, as these are known in principle. This exemplary
embodiment
shows that transmission chains are used to drive the planets, but in practice
gears,
propeller shafts or any combination of these could be used. Also instead of
hydro-motor
pinion-gear drive to rotate the planetary system, mechanisms such as levers
actuated with
hydraulic cylinders or hydraulic cylinder actuated rack and pinion can be
employed in
practice. If the planets are statically weight balanced about axis X, then
very little effort
is required in rotation of the system. This planetary rotation can then be
done manually
after the axle has been lifted.
In figure 6, a farm tractor 26 with 4 such planetary drive systems at both
ends of front
and rear axles are shown. Position K shows all the four drive systems using
crawlers to
drive the tractor. All these four can be converted to tire drives as shown in
position L.
The rear axle drive systems and the front axle drive systems are independent
of each
other and hence the conversion can take place independent of each other. Also
the front
drive systems can be using a different drive system than the rear drive
systems, for
example front axle can be driven on tires while the rear axle is driven on
crawler tracks.
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This figure illustrates the use of multiple planetary drive systems. A vehicle
could
employ one or more such planetary drive systems depending on its application.
In figures 7 to 14, only exemplary embodiments of planetary drive systems are
shown
without the vehicles on which they fit.
Figure 7 is used to illustrate that the arrangement of different planetary
drives could be at
any angle to each other about axis X. In figures 1 to 6, tire 2 and crawler
track 1 were
diametrically opposite to each other about axis X. In fig 7, tire 2 is a 150-
degrees from
crawler track 1 in arrangement. Positions M and N, along with end views P and
Q, show
the change over between rubber tire drive to crawler track drive. In practice,
vehicle
designs could employ any angular spacing between planetary drives depending on
their
application and utility.
In figure 8, planets 1 and 2 have different vertical planes of orbit V and W
about axis X.
In figures 1 to 7, tire 2 and track 1 are aligned in the same vertical plane Z
(shown in fig.
7) that forms the plane of rotation/orbit during conversion. In figure 8, the
two drives are
not aligned in the plane of rotation, but are offset to each other in planes V
and W.
Position R shows the vehicle driven on crawler tracks and position S shows the
vehicle
on tires with the crawler out of action after conversion. This figure
illustrates that the
drives can exist as planets in different orbital planes perpendicular to axis
X and are not
constrained to alignment in the same orbital plane about axis X.
Figure 9 is an exemplary planetary drive system where three planets i.e.
rubber tire 2,
steel roller/tire 27 and a crawler track are arranged in a planetary fashion
about axis X.
Crawler tracks drive the vehicle in position AA. After conversion to position
BB, runner
tires drive the vehicle. Further angular rotation of the planetary drive
system causes the
steel roller 27 and rubber tire 2 to rest on the ground as shown in position
CC and hence
both provide propulsive drive to the vehicle. This illustrates that more than
one planetary
driving unit viz. steel roller and rubber tire, could be used for driving at
any given point
of time. On further rotation, only the steel roller 27 drives the vehicle.
Figure 10 shows an exemplary planetary drive system with rubber track 28 and
rubber
tire 2 forming planets of the drive system. In functionality or arrangement,
this system is
similar to Fig 1, with rubber track 28 used instead of steel crawler track 1
as a planetary
drive unit. Position FF and GG show the inter-conversion between rubber tire
and rubber
track.
Figure 11 shows an exemplary planetary arrangement where steel roller 27 and
rubber
tire 2 form two driving units of the planetary system. Inter-conversion
between position
HH resting on rubber tire and position JJ resting on steel roller is shown in
the figure
along with sections KK and LL.
Figure 12 shows three planetary drives in the system, namely steel roller 27,
stone wheel
29 and rubber tire 2. The inter-conversion between these is also demonstrated
in the
positions MM, NN, PP and QQ. In positions MM, NN and PP, rubber tire 2, steel
roller
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27 and stone wheel 29 are shown driving the system independently. In position
QQ,
rubber tire 2 and steel roller 27 are used in combination to drive the
vehicle. This
illustrates the use of multiple driving units simultaneously.
Figure 13 shows two driving planets, steel roller 27 and rubber tire 2,
arranged
diametrically opposite to each other about axis X. Independent hydraulic
motors 32 and
34 fitted directly on bearing housings 33 and 35 respectively drive each
planet. Frame 31
of the planetary drive system is mounted on bearings on the end of vehicle
body 30.
Frame 31 is free to rotate about axis X with respect to the vehicle body 30,
hence
allowing the planetary drive system to rotate for drive conversion. The
mechanism to
rotate the planetary drive system is nit shown in the figure, as it could be
similar in
principle to hydraulic motor gear-pinion arrangement (items 6, 7 and 14 in
figure 4). This
exemplary embodiment illustrates that the planetary drive system can be driven
by
independent hydraulic motors and/or electric propulsive drive and is not
constrained to
transmission chain-sprocket drive from axle of the vehicle. Also one or more
of the
planets can serve as idler wheels/rollers/tracks instead of providing
propulsive drive to
the vehicle. These idler planetary units find application in trailers where no
drive is
required.
Figure 14 shows a planetary drive system with two planets 2 and 27 spaced
angularly at
60 degrees from each other about axis X. In this embodiment, axis Y of vehicle
axle 41 is
not aligned and is offset to axis X of the planetary drive system. In figures
1 to 12, the
vehicle axle matches axis X of the planetary drive system. In figure 14,
transmission
chain sprockets 36 and 40 fitted on vehicle axle 41 provide drive to the
planets. Position
AB shows rubber tire 2 resting on the ground, hence driving the vehicle. In
position AC,
the planetary drive system is rotated so that steel roller 27 is in action.
Since axis X for
planetary rotation is different from centerline Y of vehicle axle, planetary
rotation causes
the distance between planets and axis Y to change. Sprocket 36 drives sprocket
39 by
means of transmission chain 38. Idler sprocket 37 is provided to accommodate
for the
change in distance between sprockets 36 and 39 during planetary rotation.
Idler 37 is
mounted on its axle shown in bearing housing 48. Here bearing housing 48 is
shown
rigidly mounted on frame 44 of axle housing 42. In practice, the idler can be
mounted on
a hydraulic cylinder that can maintain the tension in the transmission chain.
It is nit
shown over here, since this is known in principle and not of interest here.
Similarly,
sprocket 40 on axle 41 drives sprocket 47 by means of transmission chain 46
and idler 45
thus driving steel roller 27 and also accommodating for changing center
distances
between sprockets during planetary rotation.
Figure 14 illustrates that centerline Y of vehicle axle providing propulsive
drive to the
planetary drive can be different from planetary rotational axis X.
The planetary drive systems described in exemplary embodiments above have
extensive
applications in agricultural tractors, earth movers, excavators, road rollers
that need to ply
on tires on-roads and off-roads on crawler tracks/steel rollers in farms or
construction
sites. The use of different type of driving units such as rubber tires, steel
rollers, wheels,
rubber tracks, crawler tracks in the planetary drive system has also been
described.
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Completely new vehicles can be designed using planetary drive systems or
wheels/tracks
of existing vehicles can be replaced with planetary drive systems to enhance
their
capabilities.
