WO2013002654A2

WO2013002654A2 - A self-powered person carrier

Info

Publication number: WO2013002654A2
Application number: PCT/NZ2012/000110
Authority: WO
Inventors: Duncan Maxwell FOX
Original assignee: MCINTOSH, Kerry
Priority date: 2011-06-27
Filing date: 2012-06-27
Publication date: 2013-01-03
Also published as: WO2013002654A3; AU2012276396A1; AU2012276396B2

Abstract

The person carrier has two hydraulically driven wheels at the front and two trailing castor wheels behind and is powered by a small gasoline engine through a pump inside a hydraulic module. Beside the forward-facing seat is a single hand control knob for causing proportional forward or backward motion and steering. Knob movement is translated into hydraulic module controls so that appropriate movements are made. The long range vehicle is adapted for off-road use and will proceed through snow, mud, dry sand, long grass, and over hills. An optional electric motor provides an alternative for silent motion indoors.

Description

TITLE: A self-powered person carrier.

The invention relates to a self-powered vehicle adapted for carrying usually one person who is in control, serving as (without limitation) a wheelchair, a mobility scooter, a self-powered chair, or a ride-on mower and refers in particular to control means for controlling the movement of such a vehicle. The person carrier does not rely on electricity as the prime mover.

DEFINITIONS

"Zero turn radius" or "zero turning circle" is a property of a vehicle which is capable of turning about an axis vertically perpendicular to a line joining two main or driving wheels together. "Translator" as used herein refers to means to receive a mechanical movement made by an operator holding preferably a single handle or knob - and to translate that controlling movement into a set of movements adapted to control separate hydraulic valves within a hydraulic controller. The translator may be mechanical, or include an electronic interface.

"Self-powered vehicle" of types relevant to this specification includes without limitation electric wheelchairs, mobility chairs, mobility scooters, lawn tractors, rear engine riders, and ride-on mowers.

BACKGROUND

Electric wheelchairs and mobility chairs powered by internal batteries are well known, yet they have some disadvantages such as (a) limited range, (b) internal complexity which is expensive to provide and difficult to maintain in the absence of expert staff, and (c) limited power. They are rarely seen away from footpaths or pavements, or crossing roads. Recharging is a lengthy process. The specific energy in a litre of fuel is significantly larger than that in an equivalent volume of storage battery.

Some people used to have an active life on an animal or horticultural farm for example, and may no longer be mobile. The standard electric wheelchair does not cater for farm use, and the standard "quad bike" is poorly adapted to use by an infirm person. Disability may be caused by war injuries or accidents, or obesity perhaps related to diabetes or other diseases.

None of the known prior art describes a powered chair having two drive wheels at the front and beneath the chair, and castor wheels at the rear; using a hydraulic drive derived from a pump operated by an internal combustion engine, associated with an effective and simple control mechanism capable of controlling speed in either direction, and at the same time making small or large adjustments to steering. US6076619 Hammer describes a tracked vehicle for a similar purpose. Column 9 line 38-46 show that both hand controls 204 must be used at the same time for straight line motion, including hydraulic motors which can be run in series or in parallel from a pump driven by an internal combustion engine 160.

US2009078480 Liberty et al describe a skid-steer wheeled vehicle, including hydraulic motors which can be run in series or in parallel from a pump driven by an internal combustion engine. This resembles a small truck rather than a wheelchair.

US 2003209372 Campbell describes a tracked snowmobile in which a hydraulic motor attached to the rear drive track is supplied from a pump driven by an internal combustion engine. The front skid is used for steering.

PROBLEM TO BE SOLVED

There exists a niche in the market for a versatile, self-powered vehicle capable of transporting a person passively seated upon the vehicle through a variety of ground conditions. Further, there is a need for a control means for such a vehicle which is simple, intuitive, and cheap. Even further, there is a need for self-powered vehicles of this type to be simply constructed so that they may be easily repaired and maintained. Electrically powered vehicles have difficulty in providing sufficient power and range and recharging is slow.

There is a need for the person to traverse roadside kerbs and cover rough ground; through a park, through mud or snow, or on a farm through vegetation, sand and mud. The rising incidence of obesity and of diabetes in Western civilizations will provide many persons who are slightly disabled yet who want to go places and carry out a normal life.

A versatile, self-powered vehicle such as is described below may permit many slightly disabled persons including war veterans to remain active and usefully employed.

OBJECT

An object of the present application is to provide an easily controlled, self-powered vehicle having a seat for carrying a person, who may be disabled, or at least to provide the public with a useful choice. A supplementary objective is to provide a self-powered vehicle which has a zero turning radius, and a long range over rough terrain.

SUMMARY OF INVENTION In a first broad aspect the invention provides a self-powered person carrier comprising a vehicle including a chassis having a front and a rear wherein the vehicle has a pair of separately driven front wheels at the front, a pair of castor wheels at the rear and a seat for the person, the vehicle includes an internal combustion engine driving at least one controllable hydraulic pump module capable when in use of controllably supplying hydraulic oil in either direction to a reversible hydraulic motor directly driving each front wheel, and has a single pivotally mounted control knob; movement of which in a first axis provide, when in use, control over steering and which, in a second axis, provide control over velocity.

Preferably the at least one controllable hydraulic pump module has a first control shaft or pintle for controlling the amount and direction of hydraulic fluid supplied to a first hydraulic motor and a second control shaft or pintle for controlling the amount and direction of hydraulic fluid supplied to a second hydraulic motor, wherein movements of the single knob in forward or backward and left or right directions are translated by a translation mechanism into movements of the first and the second control shafts of the controllable hydraulic pump module so that the vehicle may be driven and steered by the person.

In a first alternative aspect, the translation mechanism is mechanical and includes a hand knob fixedly attached to a housing containing a quadrant pivotally mounted upon a support rod extended from a first coaxial shaft mounted across the vehicle and connected to the first control shaft, the quadrant slidably enclosing, within a slot, a support rod extended from a second coaxial shaft mounted across the vehicle and connected to the second control shaft, thereby providing, when in use, that a forwards or backwards movement of the knob causes both coaxial shafts to turn by an equal amount, but a side to side movement of the knob causes the coaxial shafts to turn by an unequal amount.

In one option the user's handle lies close to an operator's right hand when the operator is seated upon the seat.

In another option the user's handle lies close to an operator's left hand when the operator is seated upon the seat.

In a third option the machine is provided with both a left-hand knob and a right-hand knob although control is achieved with motion of one only of the knobs.

Preferably the first and second control shafts are each provided with resilient means capable of applying a graded force tending to return the hand knob to a neutral position in an absence of a force applied by the operator. Preferably movement of the user's handle from side to side when the vehicle is stationary causes one drive wheel to turn in a direction opposite to that of the second drive wheel so that the vehicle may turn in a zero turning circle.

In a second alternative aspect the translation mechanism is electronic and includes means to interpret both velocity and steering commands as applied to a movable two-axis joystick control into a first and a second separate voltages, each voltage causing a corresponding pintle of the controllable hydraulic pump to be rotated by a corresponding amount, so that, when in use, the hydraulic motors are supplied with an appropriate flow of hydraulic fluid..

Preferably the electronic controller uses analogue components in order to drive one rotatable and servo-controlled drive connected on to each of the two pintles of the hydraulic controller.

Preferably all wheels are fitted with pneumatic tyres.

Optionally at least the tyres of the drive wheel are partially filled with water or a freeze-resistant liquid.

Preferably the pair of castor wheels at the rear are supported from the ends of a walking beam, pivotally mounted to the chassis at the centre of the beam.

In a second major aspect the hydraulic pump may from time to time be connected to and operated by an electric motor driven from a storage battery so that the internal combustion engine may be turned off yet the vehicle remains self-powered.

Preferably the internal combustion engine and the electric motor remain engaged with a drive belt and are selectively engaged or disengaged through clutches.

In one option both clutches are one-way clutches.

In another option the clutch to the electric motor is an electromagnetic clutch thereby allowing the motor to be turned and act as a dynamo in order to recharge the storage battery.

PREFERRED EMBODIMENT

The description of the invention to be provided herein is given purely by way of example and is not to be taken in any way as limiting the scope or extent of the invention.

Throughout this specification unless the text requires otherwise, the word "comprise" and variations such as "comprising" or "comprises" will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps. Each document, reference, patent application or patent cited in this text is expressly incorporated herein in their entirety by reference. Reference to cited material or information cited in the text should not be understood as a concession that the material or information was part of the common general knowledge or was known in New 130 Zealand or in any other country.

DRAWINGS

Fig 1 : shows a schematic view of the active parts of the vehicle.

Fig la: is a schematic view of a park brake mechanism.

Fig 2: is a drawing of the front view of the vehicle.

Fig 3: is a left front perspective view

Fig 4: is a left rear perspective view

Fig 5: shows detail of the handle and quadrant of the mechanical single-hand translator, as a sectional drawing through lines B— B of Fig 5a.

Fig 5a: is a sectional drawing through lines A-A

140 Fig 6: shows detail of the rotational parts of the single-hand command translator.

Fig 6a: shows an optional second single-hand driver knob.

Fig 7: is a diagram of the spring centre-return for the linkage to the hydraulic module.

Fig 8: is a circuit diagram for an electronic single-hand translator.

Fig 9: is a diagram to show how the source of power can be switched between engine and electric motor.

EXAMPLE 1 (Internal combustion: gasoline engine)

Refer to Figs 1-4. Fig 1 is a schematic top view of the functional components 100 of the vehicle, while Figs 2 (final prototype), and Figs 3 and 4, of a prototype chassis having an earlier

150 command translation system show the preferred physical layout. Driving wheels 105, 107 at the front, and castor wheels 119A and 119B support the chassis 102 which in turn supports a user's seat 101 having arm rests 112 and 113. A hinged foot plate 1 14 supports the user's feet. A small internal -combustion engine 103 supplied with petrol or gasoline from a tank 104 drives, through a reducing belt drive 111, a hydraulic pump inside a commercial hydraulic control module 110. An optional extra gasoline tank extends the range of the vehicle to at least 80 km. Assuming that the engine is running, the rider can indirectly control the hydraulic control module 110 by means of two shafts 106 and 108 connected to pintles arising from within the control module, after the user's hand movements which are applied to a single knob 116 have been decoded or translated by an apparatus 117 into appropriate movements that rotate the pintles. The single knob may be

160 placed on the left side or the right side, or may be repeated on both sides. Note that in Figs 3 and 4, an earlier control apparatus having two hand controls 116A and 116B; one for each engine and requiring simultaneous use is seen. The hand movement decoding apparatus 117 (mechanical) or 117A (electronic) is described in detail below.

The hydraulic control module 110 (see below for make and model) as used in this example is capable of supplying hydraulic fluid in either direction to either or both hydraulic motors 105A (via ports PI and P2 and through the unlabelled hoses to the motor) and 107A (via ports P3 and P4 and through the unlabelled hoses to the motor), from the internal pump. A reservoir of hydraulic fluid 109 is also connected to the hydraulic control module 110 by a pipe or hose through port P5. Module 110 could be replaced by separate parts, as is well known to those 170 skilled in hydraulic control systems, but the integrated form was preferred for this embodiment because it provides a convenient solution to the objective of providing a simple and easily maintained vehicle. Each hydraulic motor, which is bolted to frame 102, includes bearing means for rotatably supporting the drive wheels 105, 107 on stub axles. Trailing castor wheels are preferred, although a trailing skid, float or ski is a possibility in some environments. Each of the castor wheels 119A and 119B is pivotally mounted, as shown at 1 19C, upon a walking beam rear axle pivotally mounted to the chassis 102 at 118, so that all four wheels normally bear weight on to the ground below. In this arrangement the vehicle is fore-and-aft stable since the weight of the engine and chassis is between the drive and castor wheels, although the weight of the operator is upon or slightly behind the drive wheels.

180 There is no springing or other suspension apart from that provided by a pneumatic tyre on each wheel. The inventor prefers that the drive wheels are partially filled with water, or antifreeze such as glycol, or a mixture for extra mass and momentum, and a more sure grip. The drive wheels may have a toothed tread (as shown) to improve all-terrain performance. Wide tyres may be used to improve all-terrain performance, such as in snow.

As a result of the design and location of the wheels on the chassis and as a result of the command translation means used to operate the hydraulic control module 110, the vehicle can be controlled by its rider with considerable ease. The zero turn radius property of this vehicle arises from the possibility of driving one hydraulic motor forwards and the other in reverse, while the castor wheels, which serve to support most of the weight of the motor and part of the 190 weight of the rider and chassis simply follow.

Top speed is preferably limited to about 10 km/hr by (a) the reduction in the belt drive, and (b) a governor on the motor. Hydraulic motor selection also affects speed. Figs 2, 3 and 4 do not show other controls such as a handbrake (though see Fig la) , throttle, on/off switch and motor start button for the electric starter. Fig la shows a typical brake assembly, useful since some hydraulic oil bleed through the motor and control unit may be expected if the vehicle is parked on a slope. A transverse shaft 152 extends between drive wheels and is rotatably mounted against the chassis. Mounts are not shown and only one brake shoe 155 made of a friction-generating composite is shown. The brake shoe is rotatably mounted at 156 on to the eccentric extension 154 of shaft 152 that may 200 be welded on at 1153. In Fig la the shaft 152 is rotated by operation of an electric actuator 150, such as a solenoid or linear actuator. A mechanical hand brake with a ratchet may be substituted.

A hydraulic reservoir 109 is mounted in the lower hull of the chassis and is covered by a U shaped removable tray (103A) which carries the engine 103. The hydraulic control module 110 and control rods 106, 108 for operating the module and the translation device 117 are mounted forward of the engine, attached to the chassis.

Module 110 in this Example is a commercially available integrated hydraulic drive system described by the makers as "Tuff Torq®" Kanzaki Kokyukoki Mfg Co Ltd, Amagasaki, Japan 0.43/0.43 cubic inch displacement. This comprises a finned metal block containing two variable-displacement swash pumps, and an associated priming pump. The pumps are driven by 210 a protruding rotatable shaft to which is attached the pulley 139, and two pairs of ports (PI, P2 and P3, P4) for coupling to the two hydraulic motors. Each variable-displacement pump is independently controllable in flow amount and flow direction by appropriate rotation of the corresponding pintle shaft (106A shown), to which control rods 106 and 108 are connected. Port P5 connects module 110 to the hydraulic reservoir 109. Output of the selected module 110 is rated at up to 6 gallons per minute at 3500 revolutions per minute.

In this Example, pumps in module 110 are driven by a Briggs & Stratton ® vertical shaft 850 series gasoline motor 103. This motor has 190 cc displacement and has an electric self-starter and dynamo. The drive system comprises a toothed belt 111. The pulleys are selected to give a 1.6:1 step-down ratio. In this Example, the selected hydraulic motors 105A, 107A are Sauer 220 Danfoss OMPW 160 motors. These are direct drive units. Each one includes bearings for the stub axle supporting the corresponding independently driven drive wheel 105 or 107. The motors are easily mounted on to a vertical part of the vehicle chassis; further simplifying construction.

The parts described above are commercially available and are used in ride-on mowers. The mechanical movement translation mechanism 117 itself (located between handle 116 and the pintle shafts of the hydraulic control module 110, and mounted upon the chassis 102) will now be described.

MECHANICAL TRANSLATION MECHANISM Refer to Figs 5, 5a, 6, 6a and 7. The two control knobs, if two are provided, repeat the function 230 of each other. Either one alone provides complete control, unlike prior-art machines such as ride-on mowers. This invention provides a translation mechanism including the components shown in these Figures to translate fore and aft, or sideways, or combined movement of the single handle or knob 1 16 as made by the operator into separate movements of two distinct coaxial shafts 126, 127 of Fig 6. Each shaft, through a separate coupling beam shown as one of control rods 106 and 108 in Fig lis pivotally connected to the corresponding pintle shaft upon the hydraulic control module 110 and thereby controls one hydraulic motor directly coupled to one of the two drive wheels. Each of these shafts is pivotally mounted on to the chassis of the vehicle by two bearings 102 (only one shown), which bearings allow rotation of shaft 127 within the bearings, and separate rotation of shaft 126 which slidably encloses shaft 127. A copy 240 of bearing 102 is located at the other end of shafts 126 and 127 so that 127 rides on the bearings and tubular shaft 126 surrounds 127. The shafts are mounted with a common axis across the vehicle and under the front edge of the seat at a height relative to the seat such that the fore-and- aft or speed-controlling locus of the rider's steering and velocity control knob 1 16, which is supported by the shafts, is conveniently placed.

The translation mechanism as shown in detail in Figs 5, 5a and 6 is based on a quadrant comprising a rigid solid form 120, inside a housing 123 which is closed on its upper surface in order to minimise contamination by dust and entry of water. Fig 5a, a vertical section through the housing in line with needle bearing 121A as shown by line A— A in Fig 5, shows the in-use orientation of the housing and line B— B in Fig 5a indicates the plane of the horizontal section

250 shown in Fig 5. A first round aperture 121 through the quadrant provides pivotal mounting of preferably a needle bearing assembly at around 121 A about the end of a first bent shaft 124. That bearing and shaft are secured within the quadrant by central bolt 12 IB. The quadrant 120 to which the handle 116 on shaft 115 is fixed would be free to spin around the upturned end of shaft 124. But the second slot-shaped aperture 122 in quadrant 120 closely yet slidably encompasses the spherical outer housing 122 A of a second needle bearing assembly, placed over the upturned end of the second, bent shaft 125. The upturned end of shaft 125 inside the bearing 122A is restrained only by contact with the side walls of the elongated slot 122. At the other ends, each bent shaft is fixedly secured to the corresponding coaxial shafts 126, 127 such as by welding. Note that the spherical housing 122A on shaft 125 provides close yet slidable

260 contact with the inner walls of slot 122 even if the plane of the sheet 120 of the quadrant is inclined with respect to the perpendicular axis of bearing 122A. The two short rod ends inside the quadrant are typically separated by about 3 to 6 times the diameter of either rod. When in use, the quadrant and the handle are pivotally tied to the free end of shaft 124. If the handle is moved sideways by the rider the quadrant turns about the axis of hole 121 and twists the free end of shaft 125 in relation to the end of shaft 124, causing the rigid shafts 124 and 125 to become non-parallel, even if both shafts are simultaneously being forced in one direction or the other by fore or aft motion of the handle for the purpose of speed control. Differential motion is thereby translated along the coaxial shafts 126 and 127 and via rods 106 and 108, pivotally connected to pintles such as 106A in Fig 7 into required amounts of pump flow

270 supplied to each of the two hydraulic motors 105 A and 107A. The vehicle is thereby steerable regardless of its overall direction of movement. Even if the vehicle is stationary, opposite pump flows cause the vehicle to spin about a perpendicular to a line connecting the axes of the drive wheels, giving a zero turning circle. Scuffing of a lawn or carpet beneath is minimised by the wheel arrangement. When turning sharply, the only "scuffing" that occurs is beneath the drive wheel tyres since the castor wheels simply respond to relative movement of the vehicle against the ground. The shaft 115 has an upward bend so that the resting position of the knob is moved forward. It has been found convenient to bring the shaft 115 around an upwardly directed bend of about 80 degrees and weld it to the front side of the housing 123 of the quadrant assembly, although this may depend on the length of shaft 115, the height of the seat 101 with the arm

280 rests 112, 113, and the physique of the rider. An extendable or telescopic shaft 115 may be advisable.

The operator handle is capable of being moved forwards or backwards, and if required, sideways at the same time. The locus of the handle is a part of a circle centered on the bearing 121A; and of a second circle centered on the axis of shafts 126 and 127. As a result, movement and placement of the vehicle is easily controlled by even a novice operator. A practiced rider can approach a conventional farm gate, unlatch the gate, go in reverse through the opened gate while holding the open gate, approach the latch and latch the gate closed again.

In Fig 6 the bent shafts 124 and 125 are extended towards the right hand of an operator. Two control knobs may exist at the same time, in case the operator needs to change hands from time 290 to time, or to supply a personal carrier suited to either left or right-handed persons from stock. .

A configuration to place a knob in reach of an operator's left hand is shown in Fig 6a, arising from the same coaxial shafts. However shaft 124A emerges from a cutout 129 in the wall of shaft 126, because both knobs must cause the same vehicle movements if moved in the same direction. As previously described in Fig 6, a quadrant is encased in housing 123 A and the housing is manipulated by a knob on the end of shaft 115A so that the shafts 124A and 125A move either together or with a twisted action. Fig 7 shows more detail of the coupling to the preferred hydraulic control unit 110. A first mechanical rod 106 is pivotal ly linked by a projecting arm 126 A on to an outer shaft of a pair of coaxial shafts (126 around 127) of the translation system for use in controlling the first

300 hydraulic motor. (The inner coaxial shaft 127 is likewise produced to a second side arm 127A).

Rod 106 is pivotally linked at pivot 140 through a plate 106B to a first pintle shaft 106A so that movement of the shaft 106 from side to side (as referred to the diagram) will swivel the pintle shaft 106A and control the direction and velocity of the output from the pump within the module 110.

A self-centering device is desirable so that the control knobs will return to a zero position if not being held. An example self-centering mechanism as shown in Fig 7, which has been found to work well. A further shaft 142 which is actually a threaded stud, is pivotally mounted at 141 off the swivelling plate 106B. A compression spring 131 confined on shaft 142 between washers 145A and 146A; each welded on to a tube 142A and 142B respectively. The limits of the tubes 310 are fixed by adjustment of nuts 145 and 146 along the threaded shaft 142 which allow the centre position of the spring 131 within its confining washers to be preset. The washers and the spring in between are contained within a pivotable cage or box or U-shaped bracket 143 that pivots around support 144 fixed on to the housing and encloses shaft 142. This mechanism develops an increasing bias from the spring 131 when the knob is moved further from a centre point, to assist the self-centering function. The person operating the vehicle can feel the increasing spring pressure. A copy of this mechanism is used to carry rotation of the inner coaxial shaft 127 through shaft 108 to the other pintle shaft of the hydraulic controller.

An internal combustion engine is preferred over an electric drive for several reasons, including better power to weight performance, the simplicity of refuelling as compared to recharging, the 320 inherent simplicity and reliability of the combination of motor and hydraulic drive, and in particular because a person servicing the vehicle does not require a knowledge of power electronics. The noise of operation of the silenced engine is not seen as a disadvantage.

Overall dimensions are not critical; however it is useful if the machine can pass through a standard house doorway like an ordinary wheelchair. For example, the widest part of the vehicle should be about 850 mm, although this depends on building practice.

ELECTRONIC TRANSLATION MECHANISM

Refer to Fig 8 for an example of a linear, analogue translation circuit 117A used as one alternative for box 117 in Fig 1. The circuit 117A receives the person's commands from the single knob and translates them into mechanical movements to operate the hydraulic controller 330 110, as rotational movements applied directly on to the two pintles 106A for example. A joystick device under handle 116 receives the person's commands. One or two, duplicated joysticks are used; placed conveniently near the preferred hand or hands. Persons with particular disabilities may require customised adaptations of this interface.

Note that the circuit to be described does not include decoupling, stability, and frequency response control characteristics as are known to those skilled in the relevant arts. Likewise, parts values are not given but are determined either in view of servo loop functions, or as provided by integrated circuit manufacturers. Power connections to the active circuits are not shown. This explanatory diagram assumes a split power supply with zero or ground connected to the ground symbols as is common practice although a single supply option is quite feasible. The analogue 340 computer circuit as outlined here, or an equivalent microprocessor circuit shall be provided with appropriate safety and over-ride facilities so that there is no risk of uncontrolled motion as a result of malfunction, software error, low voltage, initialisation, or parts failure. The circuit may be replaced by a digital equivalent.

Inside the or each joystick, which is preferably provided with a spring or other resilient centering means, a pair of position-to-voltage transducers, such as conventional potentiometers Jl and J2 are physically arranged at right angles to each other. Both are electrically connected across a stable supply of positive and negative voltage as shown by the (+) and (-) symbols, and mechanically connected to a control knob 116. Potentiometers are shown for simplicity although better reliability will be provided by non-contact transducer means such as optical sensing of

350 rotation of an encoded, moveable disk or plate. Jl, the velocity control potentiometer that is placed in a fore-and-aft plane with reference to the vehicle is connected through buffer amplifier Al of gain = + 1 and through R2 to the summing input (-) of power operational amplifier A4. The output of A4 is connected through a DC motor LA (left pintle actuator) that rotates a shaft (not shown in Fig 8) connected to the left-hand motor control pintle of the hydraulic controller 1 10, and also mechanically rotates a shaft of a rotation-to-voltage transducer PI, here assumed to be a potentiometer, the wiper arm of which is connected through a gain control resistor Rl to the summing input (-) of operational amplifier A4. PI indicates current rotation of the pintle. The combination of Rl , A4, PI and LA comprises a servo loop for controlling rotation of the pintle that, when in use, provides the left hydraulic motor with a flow of hydraulic oil in either

360 direction and at a rate according to the currents summed at the (-) input of A4.

A4 and A5 are symbolic representations for real operational amplifier modules and may be partly or fully replaced by discrete components, especially for the output stage. The output of amplifiers A4 and A5 may require to be up to 1 to 5 amperes, depending on the physical construction of LA and RA. A reduction gear between the motor and the shaft allows a smaller motor. The LI 65 3 A operational amplifier is one option (STMicroelectronics). The LM675 (National Semiconductor) is another.

Each rotational actuator is capable of turning with sufficient force to reliably turn the pintle, and is preferably capable of turning sufficiently quickly that there is no perceptible delay in response, such as 0.5 seconds from end to end of its travel.

370 J2, the direction control potentiometer placed so that knob 116 movements in a side-to-side plane move the wiper of J2, is connected through buffer amplifier A2 having a gain of +1 (a voltage follower) and through R4 to the summing input (-) of operational amplifier A4. J2 is also connected through buffer amplifier A3 having a gain of -1, and through R6 to the summing input (-) of operational amplifier A5 which includes RA for the right pintle actuator, P2 as a mechanically linked pintle position sensor, and R5, together comprising a second servo loop to control the right side pintle and hence the right side hydraulic motor. The summing input of A5 also receives current via R3 from the velocity control. Use of A2 and A3 having opposite gains provides the inversion of voltages or currents that results in movement of joystick potentiometer J2 having opposing effects on the two drive motors. The inverted currents are summed with

380 velocity control currents, if any, that are being applied at the same time.

EXAMPLE 2 (Electric alternative drive)

On some occasions a vehicle user may require to enter a closed space indoors, such as around a shopping centre, in a hospital, in a home, or other public or domestic space. The associated noise and exhaust fumes of the operating internal combustion engine would exclude the self- powered person carrier from such places. This option adds a direct-current electric motor which can be used on occasion to turn the hydraulic pump instead of the internal combustion engine.

.Fig 9 shows schematic details of a preferred dual powered version of the self-powered person carrier. If the internal combustion engine 103 is not operating, an added DC electric motor 136, 390 connected to an on-board storage battery 134, is simply switched on or off by switch or contactor 135 to provide rotational power through the belt drive 111 (shown as a dashed line) to the hydraulic pump 110. Preferably the electric motor is selected with respect to its speed under load so that the hydraulic pump will be turned at about the same rate as when the engine is turning the pump. When the motor 136 is on, the same hydraulic controller 110 again provides forward and reverse speed, and steering controls. The person on board uses the same hand control 116 which will retain a similar or the same sensitivity.

Each the internal combustion engine 103 and the electric motor 136 are coupled to separate permanently engaged pulleys through one-way clutches 138 and 137 respectively. These clutches may be incorporated into the centres of the pulleys although they are shown just above 400 the corresponding pulleys for clarity in Fig 9. One-way clutches are also called sprag clutches or free-wheeling clutches. Then the faster turning source of power will drive the pump within hydraulic control module 110 while the slower or stopped source is disengaged. The common drive belt 111 takes a triangular path around the three pulleys, as seen in plan view (not shown). The rider of the self-powered person carrier, or built-in switch logic would ensure that whichever one of the engine and motor is not required is simply turned off. Unlike the internal combustion engine, the electric motor may be switched off whenever the hand control is not requesting motion.

One or more controlled electromagnetic clutches may be used. For instance, the IC engine may have a one-way clutch, while an electromagnetic clutch to the motor can provide a recharge 410 mode in which, from time to time, the electric motor is also turned by the running IC engine and serves as a dynamo to recharge the storage battery if switch 135 is closed. The battery 134 in Fig 9 may be the existing IC engine starter battery, in which case the inventor prefers that there is a safety mechanism to prevent the electric motor from completely discharging battery 134.

An advantage of this option is that there is no electric motor power control means apart from the on/off switch or contactor 135. All control is still carried out within the hydraulic apparatus, even if the interposed hydraulic drive is less efficient than in a normal electric mobility scooter. The motor 136 simply turns the hydraulic pump in one direction at a set speed when required, just as the engine 103 does. The electric motor plus battery and the internal combustion engine plus fuel tank serve as back-up power means for each other.

420

VARIATIONS

The preferred internal combustion engine 103 includes an electric starter, battery and battery charger. The battery may also be used for providing power to one or more of: headlights, warning lights, tail lights, a sound warning device, and user-provided accessories.

Optional safety provisions include a circuit to disable the engine ignition if one or more of: lack of weight of the rider upon the seat, undue tilt, absence of a hand upon the control knob, or pressing of a "panic button" occur. The inventor prefers to limit the number of electric or electronic devices since simple and easy maintenance of the vehicle is desired.

The vehicle may have only one, central castor wheel located behind the drive wheels 105, 107 430 which are placed towards the front of the vehicle. A castored skid or ski, or preferably two skids or skis may be preferred for snow and ice, or mud. The drive wheels are preferably located at the front, not the rear, since if the operator sits between them he or she is not subjected to undue sideways movements when the vehicle is turned.

The integrated, commercially available hydraulic controller 110 is preferred for simple construction and easy maintenance on a remove or replace basis. Its internal functions may be replaced with discrete parts. The translator is ideal for ride-on mowers.

For lawn, garden or small farm tractor applications, some pressurised hydraulic fluid may be provided to operate, for example, a hydraulically driven grass cutter, a pump for spraying, such as for watering or for agricultural chemicals, or a motor for a snow plough.

RESULTS AND ADVANTAGES

The self-powered vehicle is highly convenient to use. For example a person riding the vehicle can approach a farm gate, undo the latch, open the gate, proceed through the opening, turn through 180 degrees and close the latch while operating the vehicle with one hand and holding the latch with the other hand.

The vehicle has sufficient power to surmount obstacles and travel through dry sand, and a good range of 50 km or more, depending on tank size. The top speed is designed to be of the order of 10 km/hr for safety.

When the reserves of energy - the fuel tank or tanks - are emptied, it or they may be refilled with gasoline or other appropriate fuel for the selected internal combustion engine. That is a much more rapid and universally available procedure than recharging a battery and does not require a specially adapted charger. The invention makes use of the high specific energy to weight ratio of hydrocarbon fuel, as compared to batteries.

Absence of electric motor drives to the wheels abolishes the problems of magnetic sand in the motors (a risk in many desert areas), of providing reduction gearing, and provision and maintenance of relatively expensive power electronics.

This option may be made substantially spark-free and suitable for use in mines.

The vehicle is intended to be maintained by a mechanic or at a lawn mower repair shop. The hydraulic elements (motors, electronic translation circuit and hydraulic controller) can be replaced as modules once their design lifetime has been exceeded or when wear is apparent.

The expected production cost is substantially less than that of an off-road electric mobility chair. The vehicle is regarded as a rugged, on-pavement and off-road one-person carrier having an optional carrier for a small amount of luggage, such as grocery shopping, library books, fishing gear, or a bag of golf clubs. Provision of an extra seat or two is of course possible. Provision of a cover to protect the rider or at least the user's control hand against bad weather is a useful option.

Finally it will be understood that the scope of this invention as described and/or illustrated herein is not limited to the specified embodiments. Those of skill will appreciate that various modifications, additions, known equivalents, and substitutions are possible without departing from the scope and spirit of the invention as set forth.

Claims

WHAT IS CLAIMED IS

1) A self-powered person carrier comprising a vehicle including a chassis having a front and a rear characterised in that the vehicle has a pair of separately driven front wheels at the front, a pair of castor wheels at the rear and a seat for the person, the vehicle includes an internal combustion engine driving at least one controllable hydraulic pump module capable when in use of controllably supplying hydraulic oil in either direction to a reversible hydraulic motor directly driving each front wheel, and has a single pivotally mounted control knob; movement of which in a first axis provide, when in use, control over steering and which, in a

480 second axis, provide control over velocity.

2) A self-powered person carrier as claimed in claim 1, the at least one controllable hydraulic pump module has a first control shaft or pintle for controlling the amount and direction of hydraulic fluid supplied to a first hydraulic motor and a second control shaft or pintle for controlling the amount and direction of hydraulic fluid supplied to a second hydraulic motor, characterised in that movements of the single knob in forward or backward and left or right directions are translated by a translation mechanism into movements of the first and the second control shafts controllable hydraulic pump module so that the vehicle may be driven and steered by the person.

3) A self-powered person carrier as claimed in claim 2, characterised in that the translation 490 mechanism is mechanical and includes a hand knob fixedly attached to a housing containing a quadrant pivotally mounted upon a support rod extended from a first coaxial shaft mounted across the vehicle and connected to the first control shaft, the quadrant slidably enclosing, within a slot, a support rod extended from a second coaxial shaft mounted across the vehicle and connected to the second control shaft, thereby providing, when in use, that a forwards or backwards movement of the knob causes both coaxial shafts to turn by an equal amount, but a side to side movement of the knob causes the coaxial shafts to turn by an unequal amount.

4) A self-powered person carrier including a hand knob as claimed in claim 3, characterised in that the first and second control shafts are each provided with resilient means capable of applying a graded force tending to return the hand knob to a neutral position in an absence

500 of a force applied by the operator.

5) A self-powered person carrier including a hand knob as claimed in claim 3, characterised in that movement of the user's handle from side to side when the vehicle is stationary causes one drive wheel to turn in a direction opposite to that of the second drive wheel so that the vehicle may turn in a zero turning circle. 6) A person carrier as claimed in claim 2, characterised in that the translation mechanism is electronic and includes means to interpret both velocity and steering commands as applied to a movable two-axis joystick control into a first and a second separate voltages, each voltage causing a corresponding pintle of the controllable hydraulic pump to be rotated by a corresponding amount, so that, when in use, the hydraulic motors are supplied with an appropriate flow of hydraulic fluid..

7) A self-powered person carrier as claimed in claim 1 characterised in that all wheels are fitted with pneumatic tyres.

8) A self-powered person carrier as claimed in claim 1 characterised in that the pair of castor wheels at the rear are supported from the ends of a walking beam, pivotally mounted to the chassis at the centre of the beam.

9) A self-powered person carrier as claimed in claim 2 characterised in that the pump may from time to time be connected to and operated by an electric motor driven from a battery so that the internal combustion engine may be turned off yet the vehicle remains self-powered.

10) A self-powered person carrier as claimed in claim 9 characterised in that the internal combustion engine and the electric motor remain engaged with a drive belt and are selectively engaged or disengaged through separate clutches.