WO1995023072A1 - Ground engaging support means for a vehicle - Google Patents

Ground engaging support means for a vehicle Download PDF

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Publication number
WO1995023072A1
WO1995023072A1 PCT/CA1995/000107 CA9500107W WO9523072A1 WO 1995023072 A1 WO1995023072 A1 WO 1995023072A1 CA 9500107 W CA9500107 W CA 9500107W WO 9523072 A1 WO9523072 A1 WO 9523072A1
Authority
WO
WIPO (PCT)
Prior art keywords
tread
ground engaging
element
structures
support means
Prior art date
Application number
PCT/CA1995/000107
Other languages
French (fr)
Inventor
Robert L. Hagerman
Original Assignee
Airboss Of America Corp.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to CA 2116495 priority Critical patent/CA2116495A1/en
Priority to CA2,116,495 priority
Application filed by Airboss Of America Corp. filed Critical Airboss Of America Corp.
Publication of WO1995023072A1 publication Critical patent/WO1995023072A1/en

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Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B60VEHICLES IN GENERAL
    • B60BVEHICLE WHEELS; CASTORS; AXLES FOR WHEELS OR CASTORS; INCREASING WHEEL ADHESION
    • B60B15/00Wheels or wheel attachments designed for increasing traction
    • B60B15/02Wheels with spade lugs
    • B60B15/021Wheels with spade lugs made of resilient material

Abstract

A non-pneumatic resilient wheel for an offroad vehicle has a tire defined by a row of rubber ground engaging elements (36) each of which has a pair of similar tread structures which are spaced from a median plane to define a central channel (39) into which mud is funnelled when the wheel is in use. The tread structures are also offset from one another angularly about the tire to avoid clogging with mud. A hollow cavity (44) extends transversely through each tread structure for providing the required resiliency. The cavity is distorted inwardly as the element flexes in use so that mud within the cavity tends to be squeezed into the central channel.

Description

Title; GROUND ENGAGING SUPPORT MEANS FOR A VEHICLE

FIELD OF THE INVENTION

This invention relates generally to ground engaging support means for vehicles and is particularly concerned with a wheel or endless track for work vehicles such as earthworking machines, agricultural machines, military vehicles, and other vehicles used in rough terrain. BACKGROUND OF THE INVENTION Wheels or endless tracks which are resilient in character have certain performance benefits and in particular they provide cushioning so as to offer some resistance to vibration and jarring. While pneumatic tires provide cushioning, they do have the disadvantage of being susceptible to puncturing.

There have been various proposals to provide wheels or endless tracks which can resiliently x ex co provide cushioning but which are not pneumatic. One such proposal is disclosed in United Kingdom Patent No. 857439 which is directed to a vehicle ground engaging means in the form of a wheel having a plurality of pieces of flexible tubing circumferentially spaced around its periphery and extending crosswise of the direction of travel. Although the provision of the flexible tubing is intended to provide the wheel with some cushioning characteristics, it is believed that tubing would not perform altogether satisfactorily in practice. This is because the side wall strength required of the tubing to avoid collapsing or excessive deformation under normal load conditions would be such that the tubing would in all probability not flex sufficiently to provide satisfactory cushioning.

Proposals have also been made for a non- pneumatic but resilient vehicle wheel which has a tire formed of a plurality of individual modular ground engaging elements or segments. Reference may be made by way of example to United States Design Patents Nos. 329,413 issued September 15, 1992 to Chandler, 342,526 issued December 21, 1993 also to Chandler and 325,209 issued April 7, 1992 to Robinson.

The present invention has been devised specifically (although not exclusively) for use in connection with above-ground mobile irrigation systems. Systems of this type are used extensively in North America, as well as in other parts of the world to increase crop yields. A typical system includes a number of wheeled vehicles called irrigation pivots which support water spray equipment. The irrigation pivots are spaced quite widely from one another across an area to irrigated and are driven so as to advance progressively across the area as the irrigation proceeds. Each pivot normally has at least two wheels that are conventionally provided with pneumatic tires. In practice, these systems have severe flat tire problems due to prolonged exposure to the elements, which results in side wall cracking and corresponding losses in air pressure. Flat tires are difficult and expensive to repair or replace in the field. In addition, these systems often operate in extremely difficult soil conditions and, in many instances, require much better traction than current pneumatic tires can provide.

Accordingly, one aim of the invention is to provide a non-pneumatic but resiliently flexible tire structure which is particularly suitable for application in this field. It should, however, be clearly understood that the invention is not limited to this particular application. SUMMARY OF THE INVENTION Broadly, the invention provides ground engaging support means for a vehicle, comprising a support movable in a defined direction and a plurality of ground engaging elements mounted on the support. Each element has a base portion which is coupled to the support and a pair of similar tread structures which extend outwardly of the base portion and are spaced from one another transversely with respect to the said defined direction and offset from one another in that direction. Each of the structures includes a tread portion for engagement with the ground and an intermediate portion which extends between the tread portion and the base portion and which is resiliently flexible so as to deflect under load.

The support means provided by the invention may be a wheel, in which case the ground engaging elements form a tire of the wheei. The support may be a wheel rim or a circular band adapted to be fitted to a separate rim. In an alternative embodiment applied to an endless track, the support may oe a πexible endless band or belt which is guided around rollers or drums on the vehicle in use. Preferably, the ground engaging elements are arranged on the support in end-to-end relationship in the said defined direction. In other words, each element preferably occupies and defines the entire transverse extent of the ground engaging portion of the support means (e.g. the width of the tire where the support means is a wheel) . Preferably, the ground engaging elements are identical with one another.

The fact that the tread structures of each ground engaging element are spaced from one another transversely of the support provides a distinct channel along the tread surface formed by successive ground engaging elements. It has been found that this tends to have a "funnelling" effect on mud over which the vehicle may be moving, and keeps the mud within the footprint of the tire or track. This contrasts with conventional offroad type tires which are designed to push the mud outwardly to the sides of the tire. This tends to cause the tire to make a deep trough in the ground, which can lead to difficulties in traction and the tire "bogging down". The invention adopts the opposite approach of attempting to keep the mud within the footprint.

The fact that the tread structures are offset from one another in the direction of movement of the tire or the like tends to avoid mud building up on the individual structures. In other words, the tire is to some extent "self-cleaning".

The respective tread structures of each ground engaging element are preferably symmetrically disposed about the longitudinal centerline of the element and the structures themselves are preferably arranged in a chevron-like configuration pointing in the direction of movement of the tire or the like. The tire is then αirectional.

The tread portions of the structures are preferably tread bars that extend at least generally transversely of the support and preferably in the said chevron configuration so as to in effect provide paddle- wheel like arrangement for good traction.

Resilient flexibility may be provided by arranging for the intermediate portions of the respective tread structures of each ground engaging element to be hollow. Preferably, each intermediate portion has a single hollow cavity that extends from end-to-end of the structure (generally transversely of the element itself) and which has front and rear side walls that are capable of deflecting under load. Such deflection effectively changes the shape of the cavity itself and tends to squeeze out any mud that has entered the cavity. Since the cavity is open-ended, some of this mud will squeeze into the center channel of the tire or the like, which further aids in keeping the mud within the tire footprint as discussed previously. In very viscous mud or in water, this has the effect of increasing the flotation effect of the tire. In this respect, the effect is opposite the effect desired with some prior art tires where the intention is to decrease flotation in water.

Preferably, the ground engaging elements are removably mounted on the support so that individual elements can be replaced in the event of damage or deterioration.

Each element is preferably, integrally formed of suitable resilient materials such as rubber. The rubber will normally be moulded. The moulding preferably incorporates bolt holes, bolts or other formations that allow the element to be attached to the support. BRIEF DESCRIPTION OF DRAWINGS

In order that the invention may be more clearly understood, reference will now made to the accompanying drawings which illustrate a particular preferred embodiment of the invention by way of example, and in which:

Fig. 1 is a perspective view from one end of part of a mobile irrigation system provided with wheels in accordance with the present invention; Fig. 2 is a perspective view of one of the wheels used in the system of Fig. 1;

Fig. 3 is a perspective view from above of a ground engaging element of the wheel;

Fig. 4 is a perspective view of the element as seen from one end and above;

Fig. 5 is a perspective view similar to Fig. 4 but from a lower elevation;

Fig. 6 is a plan view as seen from slightly to one side; Fig. 7 is a similar view as seen from the opposite side; and.

Fig. 8 is an underneath plan view. DESCRIPTION OF PREFERRED EMBODIMENT

Fig. 1 shows part of a mobile irrigation system which includes a pair of so-called irrigation pivots, individually denoted by reference numeral 20. The pivots are spaced from one another and act as supports for spray equipment generally denoted 22. The irrigation system is shown simply to illustrate a possible environment in which the wheel provided by the invention may be used and forms no part of the present invention. Accordingly, neither the irrigation system nor the individual irrigation pivots will be described in detail. Suffice it to say that the irrigation pivots are self-propelled and travel slowly in synchronism on parallel paths while water is delivered from the spray equipment 22. For the purposes of the present invention, it is relevant to note only that the individual pivots u are provided with' wheels 24 that have offroad-type tires 26 in accordance with the present invention.

One of those wheels is shown individually in Fig. 2 and comprises a rim 28 which is essentially of conventional form and includes a cylindrical outer band 30 which supports the tire 26. The tire is formed by an assembly of individual ground engaging elements 32 that are bolted to the band 30. The elements are shown individually in Figs. 3 to 8 (which will be described later). With reference to Fig. 2, it is important to note that the support formed by the rim 28 is movable in a defined direction. The rim 28 may be rotatable in the direction indicated by arrow 34 or in the opposite direction of rotation (not shown) . The individual ground engaging elements 32 are arranged end-to-end in a continuous assembly forming the tire with each element defining the entire lateral extent of the tire. It is also useful to note from Fig. 2 that each element has a generally chevron-like overall configuration and includes a pair of similar tread structures 36 that are spaced from one another transversely with respect to the defined direction 34 and are offset from one another in that direction. These features are shown in more detail in Figs. 3 to 8, which will now be described.

Referring now more particularly to Fig. 3, one of the ground engaging elements 32 is shown individually; the same element is in fact shown in Figs. 4 to 8, as seen from different viewpoints. In any event, with continued reference to Fig. 3, the element is shown to comprise a generally flat base portion 38 that has a somewhat chevron-shaped overall configuration. The defined direction of movement indicated by arrow 34 in Fig. 2 is similarly indicated in Fig. 3 and it will be seen that the element is symmetrical about a median plane that is normal to oase portion 38 and that includes arrow 34.

The two tread structures 36 extend upwardly from base portion 38 and are spaced from one another transversely of the element, i.e. are on opposite sides of the median plane of the element. The hollow structures are spaced by an amount selected to provide a defined channel along the centerline of the tire, as is generally indicated at 39 in Fig. 2. In Fig. 3, the part of the channel defined by the spacing between the two tread structures 36 of the individual element 32, is similarly denoted 39. Channel 39 has substantial depth and width and is able to accommodate significant quantities of movable ground material such as mud, as may be seen from the drawings. It extends a substantial radial depth into the tire from the tread structures 36 down to the outer surface of the base portion 38, which base portion is relatively thin as compared with the radial thickness or depth of the tread structures 36. It is also clearly apparent from Fig. 3 that the two structures 36 are offset from one another in direction 34 so that each structure extends over only slightly less than half of the overall width of the element, with the other half of the element being open. The elements are mounted on rim 28 so as to "nest" into one another in end- to-end relationship so that these open portions of the elements remain unobstructed, as is apparent from Fig. 2. Referring back to Fig. 3, the two tread structures 36 are essentially identical with one another. Each structure is of uniform cross-sectional shape throughout its length and has an outer portion denoted 40 that forms a tread bar for engagement with the ground. It will be seen that the two tread bars 40 of the respective hollow structures extend generally transversely of the tread of the tire but angled slightly towards one another to reflect the overall chevron-like shape of the element, while still presenting upright, laterally extending surfaces of substantial extent for providing good traction. It will be seen from Fig. 2 that these tread portions are designed to impart to the overall tire a paddle-wheel like overall configuration.

Each of the tread structures 36 also includes a hollow intermediate portion 42 between the tread bar 40 and the base portion 38 of the element. Portion 42 has a generally arch-shaped configuration as seen in cross- section with respective side limbs 42a that form sidewalls of a cavity 44 that extends from end-to-end of the hollow structure. The sidewalls are resiliently flexible so as to deflect under load, imparting resilient riding characteristics to the tire not unlike those that are achieved with a pneumatic tire. As may be seen from Figures 3 to 8 of the drawings, cavity 44 has a cross section which takes up a substantial proportion of the total area of the tread structure's section having a width which considered generally is greater than the width of the side limbs 42a, and a depth, or height, which is substantially greater than the thickness of the base portion 38. In this embodiment, the ground engaging element is formed integrally from a material having appropriate characteristics of resiliency to allow appropriate deflection of the sidewalls 42a, while providing adequate strength for the tread bars 40 and resisting undue deflection of the base portion 38. In a specific example, the ground engagement element is moulded in a rubber material of appropriate hardness.

The exposed areas of the base portion 38 opposite the respective hollow structures 36 are provided with openings 46 for receiving bolts for securing the element to the rim 28. Two additional openings are provided within the respective cavities (see Fig. 8).

It the element is chevron-shaped, then when the tire rotates in the direction represented by arrow 34, then the leading portion of each chevron-shaped element 32 is the tip of the transversely extending leading surface. This tip is located where central channel 39 intersects the leading surface. When the tire rotates in the opposite direction, the leading portion is the transversely positioned outside edges of each element. A trough is located at the intersection of central channel 39 and the transversely extending leading surface.

In the tire that is formed by the assembly of ground engaging elements 32 on the rim 28, the design features of the elements described above tend to cause mud that is encountered by the tire as it rotates to be funnelled into the central channel 39 defined between the spaced tread structures 36 of the respective elements. This has the effect of keeping the mud within the footprint of the tire instead of pushing the mud to the side as in conventional offroad tires, and avoiding the trough that is formed by the tire becoming too deep, which can lead to the tire "bogging down". Mud that accumulates within the cavities 44 of the respective tread structures tends to be squeezed out into the center channel as the cavities are distorted inwardly under load. At the same time, the fact that the structures 36 are offset from one another in the direction of movement of the tire (34) means that the tire to some extent tends to be self- cleaning and does not clog up with mud.

It has surprisingly been found that when the tire rotates in the opposite direction to that indicated by arrow 34, that the self-cleaning action of the tire is greatly improved. When a tire comprising a plurality of chevron-shaped elements is operated in this direction, tread structures 36 act to pump mud into central channel 39. The leading surface of each element is preferably etrectively V-shaped. The tread elements pump the mud into the trough of this V-shaped surface thus helping to ensure a continuous supply of mud to the central channel. As the tire rotates, cavities 44 tend to deform. The pumping of mud into central channel 39 allows mud to flow outwardly through cavities 44 while ensuring the continual presence of mud in central channel 39. This pumping action assists the continuous self-cleaning function of the tire.

It will of course be appreciated that the preceding description relates to a particular preferred embodiment and that many modifications are possible within the broad scope of the invention. For example, the particular chevron-like configuration of the element is not essential. The tread bars or other ground engaging formations could extend strictly transversely of the tire surface. While the drawings show the ground engaging elements extending end-to-end in a single row for forming the circumference of the tire, two or even more laterally adjacent rows of elements could be provided if required by particular applications for the tire.

It has also previously been mentioned that, while specific reference has been made to a tire, ground engaging elements of the form provided by the invention can be used to form an endless track for a tracked vehicle. In this case, the support for the ground engaging elements, instead of being the wheel rim 28 shown in Fig. 2 would be an endless belt or band on which the ground engaging elements would be mounted.

Claims

I CLAIM;
1. Ground engaging support means for a vehicle, comprising a support movable in a defined direction, and a plurality of ground engaging elements mounted on said support, each said element having a base portion coupled to the support and a pair of similar tread structures which extend outwardly of the base portion and are spaced from one another transversely with respect to said defined direction and offset from one another in said defined direction, each of said tread structures including a tread portion for engagement with the ground, and an intermediate portion which extends between the tread portion and the base portion and which is resiliently flexible so as to deflect under load.
2. Support means as claimed in claim 1, wherein said tread structures are symmetrical about a longitudinal median plane which is co-incident with said defined direction, wherein the tread structures are each spaced from said plane by an amount sufficient to form a defined central channel extending longitudinally of said plurality of ground engaging elements.
3. Support means as claimed in claim 1, wherein each said tread structure is of uniform cross-sectional shape throughout its length and defines a tread bar forming said tread portion and extending at least generally transversely with respect to said defined direction, whereby said tread bars of said plurality of ground engaging elements together define a paddle-like configuration.
4. Support means as claimed in claim 1, wherein each of said tread structures is of uniform cross- sectional shape throughout its length and wherein said intermediate portion of the tread structure includes an open ended cavity which extends longitudinally of the structure and generally transversely of with respect to said defined direction, the cavity being defined by respective front and rear sidewalls which are capable of deflecting under load to provide said resilient flexibility of the element.
5. Support means as claimed in claim 4, wherein said intermediate portion has an arch-shaped configuration as seen in cross-section, and wherein said tread portion comprises a tread bar extending upwardly generally centrally of the arch.
6. Support means as claimed in claim 1, wherein each of said ground engaging elements is integrally formed m one piece.
7. Support means as claimed in claim 2, wherein each of said ground engaging elements has generally a chevron-shaped configuration, said tread structures each extending at an acute angle with respect to said longitudinal median plane and converging in said defined direction.
8. Support means as claimed in claim 7, wherein the base portion of each ground engaging element has a chevron-like shape selected so that the base portions of adjacent elements can nest together end-to-end in a row extending in said defined direction.
9. Support means as claimed in claim 1, in the form of a wheel, wherein the said ground engaging elements co- operate to form a tire of the wheel, and wherein said support comprises a cylindrical wheel rim member.
10. A ground engaging element adapted to be mounted on a support for forming ground engaging support means for a vehicle, said element having a base portion adapted to be coupled to the support and a pair of similar tread structures which extend outwardly of the base portion and are spaced from one another in a direction transverse to a defined direction in which the ground engaging element is intended to move in use, said tread structures additionally being offset from one another in said defined direction, wherein each of said tread structures includes a tread portion for engagement with the ground and an intermediate portion which extends between the tread portion and the base portion and which is resiliently flexible so as to deflect under load.
11. A non-pneumatic resilient venicie wheel comprising; a) a rim having a rim surface extending about an axis of rotation of the wheel; b) a tire comprising a plurality of load-bearing ground engaging elements mounted on and extending around said rim surface in end-to-end relationship with each element extending transversely of said surface generally in the direction of said axis, each of said grounding engaging elements comprising a base portion coupled to said rim surface to transmit ground engaging loads thereto and a pair of similar tread structures on said base portion, said tread structures being spaced from one another transversely of the element and offset longitudinally in the direction of movement of the element as the wheel rotates in use, each said structure including: a tread portion for engaging the ground, said tread portion being positioned radially outwardly of said rim surface and base portion; and load-bearing bendable side walls in spaced relationship to each other and extending transversely of the element from said tread portion to said base portion and defining an open cavity therebetween, said bendable sidewalls being adapted to permit reduction in the dimension of said cavity in the inward direction in response to the application of an inward force to said structure.
PCT/CA1995/000107 1994-02-25 1995-02-27 Ground engaging support means for a vehicle WO1995023072A1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
CA 2116495 CA2116495A1 (en) 1994-02-25 1994-02-25 Ground engaging support means for a vehicle
CA2,116,495 1994-02-25

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
AU18034/95A AU1803495A (en) 1994-02-25 1995-02-27 Ground engaging support means for a vehicle

Publications (1)

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WO1995023072A1 true WO1995023072A1 (en) 1995-08-31

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Family Applications (1)

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PCT/CA1995/000107 WO1995023072A1 (en) 1994-02-25 1995-02-27 Ground engaging support means for a vehicle

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AU (1) AU1803495A (en)
CA (1) CA2116495A1 (en)
WO (1) WO1995023072A1 (en)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2807304A (en) * 1956-03-02 1957-09-24 Samuel C Pellegrino Adjustable tread for wheel and tire assemblies
GB857439A (en) * 1958-11-05 1960-12-29 Carl Georg Wadell Improvements in ground-engaging means for vehicles
US4261622A (en) * 1979-08-01 1981-04-14 Miller James B Automotive vehicle wheel for travel on ice or snow
WO1990000983A1 (en) * 1988-07-19 1990-02-08 Altrack Limited Wheel or endless track

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2807304A (en) * 1956-03-02 1957-09-24 Samuel C Pellegrino Adjustable tread for wheel and tire assemblies
GB857439A (en) * 1958-11-05 1960-12-29 Carl Georg Wadell Improvements in ground-engaging means for vehicles
US4261622A (en) * 1979-08-01 1981-04-14 Miller James B Automotive vehicle wheel for travel on ice or snow
WO1990000983A1 (en) * 1988-07-19 1990-02-08 Altrack Limited Wheel or endless track

Also Published As

Publication number Publication date
CA2116495A1 (en) 1995-08-26
AU1803495A (en) 1995-09-11

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