A SUPPORTING WHEEL

Abstract: A support wheel comprises central part (10), a wheel rim (11) and an intermediate part (12) interconnecting the central part and the wheel rim. The wheel rim (11) is composed of a plurality of parts (21) which are mutually separated in the peripheral direction of the wheel. Each wheel rim part includes two or more elastic beam elements (24, 25) which are located at mutually different radial distances from the wheel axis (23) and which extend alternatingly towards opposite sides of the wheel, the radially innermost beam element (24) having one end connected substantially rigidly to said intermediate part (12) and the other end thereof connected substantially rigidly to one end of the next following beam element (25). The wheel rim parts (21) are mutually connected by means of a connecting arrangement (28) which transfers substantially solely peripheral forces.

Description: A SUPPORTING WHEEL The present invention relates to a supporting wheel of the kind which includes a central part, a wheel rim which is in- tended to roll against a foundation surface, and an inter¬ mediate part which connects the central part with the wheel rim. More particularly, the invention relates to a non-pneu¬ matic supporting wheel for use, e.g., with vehicles. In the case of road vehicles fitted with conventional pneu¬ matic-type wheels, the internal losses experienced within the tyres at normal road speeds, e.g. speeds of from 70 to 90 km/hour, are responsible for a considerable part, in the order of 20-30 %, of the energy consumed during forward drive. This is because the rubber from which a tyre is con¬ structed is far from being ideally elastic, and because the necessary reinforcing cords or plies, due to their particu¬ lar arrangement, transfer local deformations of the tyre, e.g. tyre deformations that occur in the tyre section in contact with the road surface, to wide adjacent areas of the tyre, with large losses in energy as a result thereof. Furthermore, pneumatic-type vehicle wheels are rather heavy and demand a relatively high price. Consequently, there is a need for non-pneumatic supporting wheels which while having functional properties comparable with those of pneumatic wheels, such as gripping power, contribution to driving comfort, etc., have none of the dis¬ advantages of the pneumatic wheels. The object of the present invention is to provide a novel and useful supporting wheel which will satisfy this need. To this end there is proposed in accordance with the inven- tion a supporting wheel of the aforesaid kind which is charac terized by the combination in which the wheel rim is com¬ posed of a plurality of parts which are made of an elastic material and which are mutually separated from one another in the peripheral direction on the wheel, each of the wheel rim parts including two or more beam elements which are located at mutually different radial distances from the wheel axis and which extend alternatingly towards opposite sides of the wheel, the radially innermost beam element having one end connected substantially rigidly to said inter¬ mediate part and the other end thereof connected substan¬ tially rigidly to one end of the next following beam element which, if not forming the radially outermost beam element, is in turn connected at its other end substantially rigidly to the next following beam element, and so on; in which the centre, distance between said whee] rim parts doe not appreciably exceed, and is preferably smaller than the peripheral extension of the wheel rim section in contact with the foundation surface within the intended loading re¬ gion of the wheel; in which said wheel rim parts are mutually connected by means of a connecting arrangement which transfers substantially solely peripheral forces; and in which said beam elements are so constructed that the radi¬ ally outermost beam elements of said wheel rim parts within the loading region of the wheel exert against the foundation surface a pressure which is distributed substantially uni- formly across the width of said wheel. The arrangement proposed in accordance with the invention affords the advantages of enabling the resilient parts of the wheel to be made from a plastics material that exhibits essentially truly elastic properties, to a much greater extent than was previously possible. A further advantage resides in the fact that local elastic deformation of the supporting wheel in, for instance, that section of the wheel which is in contact with the foundation or road surface, is transferred peripherally to adjacent regions or sections of the wheel rim to essentially a minimum extent. The con¬ necting arrangement that connects together the wheel rim parts at a radial distance from said intermediate part, e.g. in the region of the outermost beam elements, enables said wheel rim parts to have a small extension in the peripheral direction of the wheel in a desirable manner, while at the same time allowing large forces to be transferred to the foundation surface, e.g. when accelerating or decelerating a vehicle supported by such wheels. The design of the wheel should be such that the pressure exerted in any part of the area of contact between the wheel and a horisontal planer foundation or road surface, when said wheel is loaded within its intended loading region, deviates less than 50 % from the average pressure obtained by deviding the total load carried by the wheel with the total contact area. in accordance with one particularly simple embodiment of the supporting wheel according to the invention, the aforesaid connecting arrangement may comprise at least one peripher¬ ally extending traction ring which is embedded in or let- into said wheel rim parts, preferably the outermost beam elements. An advantage is afforded when the connecting arrangement comprises a tread which encircles said wheel rim parts and which while being relatively pliable and resilient cannot be strechted to any appreciable extent in the peripheral direction of the wheel. This arrangement avoids, inter alia, the occurence of vibrations caused by the individual wheel rim parts striking the foundation surface sequentially as the wheel rotates, and therewith avoids the subsequent risk of resonance phenomena, such resonance phenomena having a deliterious effect from a stress aspect and may also result in impermissible or unsuitable noise emission. The emission of noise can be reduced still further when, in accordance with one advantageous feature of the invention, the tread is higher at the edges thereof than at the central region thereof, so that when the wheel rolls against a foundation surface the aforesaid edges will contact this surface earlier than do the central region, whereby noise generated upon contact of the central region with the foundation surface is trapped or enclosed to some extent and therefore prevented from propagating as air-carried sound from the region in which it was generated. The wheel rim parts may be provided with sound absorbing material, for the purpose of absorbing sound transmitted by the rim parts, this material preferably being placed on the inner surfaces of said outermost beam elements. For the purpose of reducing the extent to which vibrations and sound are generated as the supporting wheel runs over a foundation surface or road surface, the afore¬ said beam elements may form an angle with the wheel axis, whe seen from the periphery of the wheel. When using a tread that encircles the wheel rim parts, the tread is preferably perforated with apertures that open into gaps located between mutually adjacent wheel rim parts. This arrangement is effective in leading away any water that may penetrate between the tread and the foundation surface, there by substantially eliminating the risk of aquaplaning on wet roads when using the supporting wheel to support a road vehic For the purpose of avoiding damage to the supporting wheel when subjecting the wheel to heavy, powerful and abrupt load peaks, means can be provided between the beam elements and inwardly of the radially innermost beam elements, for damping and restricting bending of the beam elements. The invention will now be described in more detail with refe- rence to a number of exemplifying embodiments thereof illust¬ rated in the accompanying drawings. Figure 1 is a sectional view of a first embodiment of the supporting wheel according to the invention, taken on the line 1-1 in Figure 2. Figure 2 is a side view of part of the supporting wheel illus rated in Figure 1. Figure 3 is a view which corresponds essentially with the view of Figure 1 , but in which certain component parts have been omitted and which shows beam elements of the supporting wheel in an inwardly sprung state. Figure 4 is a sectional view of a second embodiment of the wheel according to the invention, said view corresponding essentially with the view of Figure 1 and being taken on the line IV-IV in Figure 5. Figure 5 is a side view of a part of the supporting wheel illustrated in Figure 4. Figure 6 is a sectional view of a third embodiment of the wheel according to the invention, said view corresponding essentially with the views of Figures 1 and 4 and being taken on the line VI-VI in Figure 7. Figure 7 is a side view of a part of the supporting wheel illustrated in Figure 6. Figure 8 is a partial view showing a portion of the tread of the supporting wheel illustrated in Figures 6 and 7 when seen from the periphery of the wheel. In Figures 1 and 2 there is illustrated a supporting wheel which comprises a central part, generally identified at 10, a wheel rim generally identified at 11 , and an intermediate part 12 which connects the central part 10 and the wheel rim 11 together. The central wheel part 10 comprises two support members 13, 14, which are preferably made of metal, and a member 15 which is located between said support members and which is preferably made of an elastic plastics material, said member 15 adjoining the intermediate part 12. The supporting wheel is attached to a wheel hub 17, shown in chain lines, with the aid of socket screws 16 which screw onto screw-threaded studs 18 extending outwardly from the hub. Only one socket screw 16 and one stud 18 are shown. The reference numerals 19 and 20 identify respectively a brake disc and a brake shoe holder. As will best be seen from Figure 2, the wheel rim 11 is comprised of a plurality of parts 21 which are mutually separated in the peripheral direction of the wheel such as to present spaces or slots 22 therebetween, these slots optionally extending in the direction of the wheel axis, as with the embodiment illustrated in Figure 1 in which the geometric axis of the wheel is referenced 23, or forming an angle with said axis. The wheel rim 11, and similarly also the intermediate part 12 and the member 15, comprises a material which essentially has truly elastic properties, preferably a plastics material that has essentially truly elastic properties. Each wheel rim part 21 comprises two beam elements 24, 25 which are located at mutually different radial distances from the wheel axis 23 and which extend alternatingly towards opposite sides of the wheel. The radially innermost beam element 24 has at 26 one end connec¬ ted substantially rigidly to the central part 12 of the wheel and at 27 its other end connected substantially rigidly to the radially outer beam element 25. The centre distance between mutually sequential wheel rim parts 21 is preferably small, e.g. from 1/3 - 1/4 of the peripheral extension of the section of the wheel rim 11 in contact with the foundation surface. Although the centre distance may be greater than that aforesaid, however, it should not exceed said extension of the wheel rim section to any appreciable extent. The wheel rim parts 21 are joined together by means of a connecting arrangement 28 which will transfer essentiall only peripheral forces. In the embodiment illustrated in Figures 1 and 2 the connecting arrangement 28 comprises a relatively pliable, elastic tread, e.g. a rubber tread, which encircles the wheel and which is preferably provided with reinforcing cords or plies 29 and may be patterned, as indicated at 30. The beam elements 24, 25 are constructed with regard to their mechanical strength properties in a man¬ ner such that the radially outermost elements 25 of the wheel rim parts within the intended wheel-loading region exert against the road surface a pressure which is distributed sub- stantially uniformly across the width of the wheel. This is best seen from the simplified sectional view presented in Figure 3, which shows solely the intermediate part 12, the member 15, and the wheel rim 11. In the illustration presented in Figure 3 the beam elements 24 and 25 and the tread 28 are drawn in broken lines in their unloaded state and in full lines in their loaded state. It will be seen from this illustration that as a result of the sibstantially rigid attachment of the beam element 25 at 27, the beam element 24 is bent into a slight S-shape when the wheel is uniformly loaded, while the beam element 25 is slightly arched, the opposite ends of the beam element 25 being located at mutually the same distance from the axis 23. As illustrated, the tread 28 is conveniently higher at the edges thereof than at the central region thereof, and conse¬ quently when the wheel is loaded the tread 28 will bear agains the road surface (not shown) with the bearing pressure dis¬ tributed very uniformly over the contacting tread section. It will be understood, however, that if the road surface slopes in relation to the wheel axis 23, the beam elements will follow the road surface -to some extent, thereby maintaini satisfactory contact therewith. In the embodiment illustrated in Figure 1 , the tread 28 is perforated with apertures 31 through which water can be pressed inwardly from the contact area of the wheel with the road surface to the open spaces between the beam elements 24, 25, thereby eliminating the risk of auqaplaning. A tread 28 with which the sides thereof are higher than the central portion of the tread is also advantageous from an acoustic aspect, since noise generated upon contact of the tread with the road surface is, to some extent, trapped or enclosed. Improvements from an acoustic aspect can also be achieved by mounting a sound absorbant material (not shown) on the inner surfaces of the outermost beam elements 25. In order to restrict the extent to which the beam elements 24, 25, are able to bend, damping devices 32, 33 are provided in the form of a ring 32 of soft resilient material encirclin the beam elements 24 and a ring 33 of soft resilient material surrounding the radial outerpart of a collar 34, which ex- tends from the support member 14 to a location in the proxi¬ mity of the inner surfaces of the beam elements 24. The references 10 - 20 and 28 - 31 in ]?igures 4 and 5 indi¬ cate similar components and elements as those in Figures 1 and 2. The wheel rim 11 of the Figure 4 and 5 embodiment is also composed of a plurality of parts 35 which are mutually spaced in the peripheral direction of the wheel to define intermediate spaces or slots 36. Each wheel rim part 35 com¬ prises three beam elements 37, 38, 39 which are located at mutually different distances from the geometric axis 23 of the wheel and extend alternatingly towards opposite sides of the wheel. The radially innermost beam element 37 has at 40 one end connected essentially rigidly to the intermediate par 12 of the wheel and at 41 its other end connected essentially rigidly to one end of the next following beam element 38, whi in turn at 42 has one end connected substantially rigidly to the radially outer beam element 39. The centre distances be¬ tween mutually sequential wheel rim parts are selected in the manner described with reference to Figures 1 or 2, and the wheel rim parts 35 may be joined together by means of a connecting arrangement 28 - 31 which, with the exception of minor differences in the pattern 30, coincides with the arrangement 28 - 31 of the embodiment illustrated in Figures 1 and ' 2. The beam elements 37, 38, 39 of the Figure 4 and 5 embodiment are also constructed with regard to their mechanical strength in a manner such that the radially outermost elements 39 of the wheel rim parts 35 within the intended wheel loading region exert against the road surface a pressure which is substantially uniformly distri¬ buted over the width of the wheel. In order to restrict the extent to which the beam elements 37, 38, 39 are able to bend, damping devices 43, 44, 45 are pro¬ vided in the form of rings 43, 44 of soft, resilient material which encircle the beam elements 37 and 38, and a ring 45 of soft resilient material which encircles the radially outer- part of a collar 46 which extends outwardly from the support member 14 to a location in the proximity of the inner surfaces of the beam elements 37. Instead of, or complimentary to, a tread which is reinforced in the peripheral direction of and extends around the wheel for transferring substantially solely peripheral forces be¬ tween the wheel rim parts 21 or 35, there can be used one or more peripherally extending pull rings which are let-into or embedded in the wheel rim parts, as illustrated at 47 in Figure 4. If, in this regard, a tread layer is desired on the outermost beam elements, this layer may be formed from sepa¬ rate tread sections each covering a respective beam element in the manner illustrated at 48 in Figure 5. The reference numerals 10-12, 17-20, 23, 28-30, 37-39 and 41-44 in Figures 6 - 8 indicate similar components and elements as those in Figures 4 and 5. In the embodiment shown in Figures 6 - 8, the central wheel part 10 and the intermediate part 11 are made from a substantially rigid material, such as aluminum. The supporting wheel is attached to the wheel hub 17 with the aid of nuts 49 (only one nut 49 being shown) . The central wheel part 10 is covered by a removable hub cap 50. The intermediate wheel part 12 is provided with a cylindrical collar portion 51 at its outer periphery, said portion 51 being supported by radial stiffening fins, one of which is shown at 52 in Figure 6. The radial slots 36 of the wheel rim 11 extend completely through the beam elements 39 and 38 and end at 53 at a short distance from the radially inner surface 54 of the wheel rim 11. This radially inner surface 54 of the wheel rim is secured to the radially outer surface of the collar portion 51 with the aid of, e.g., a suitable adhesive. Thus, the radially innermost beam elements 37 are rigidly supported by the collar portion 51, while the beam elements 38 and 39 are able to bend in the manner described with reference to Figures 1 - 3 or 4 and 5. The tread 28 shown in Figures 6 - 8 is patterned, as indicated at 30, and opposite the slots 36 between adjacent wheel rim parts 35 the tread 28 is provided with through- passing recesses 55 which extend from a respective edge of the tread to positions 56 close to the centre of the tread 28. The narrow central tread region shown in cross- section in Figure 6 is flexible so as to allow a narrowing of the slots 36 at one side of the supporting wheel and a widening of said slots at the other side of the wheel, e.g. to prevent relative movement between a road surface and a portion of the tread 28 in contact with said surface when moderately turning the wheel. The invention is not restricted to the described and illustra ted embodiments, but modifications can be made within the scope of the inventive concept defined in the following claims.

Claims: C L A I M S 1. A support wheel comprising a central part (10) , a wheel rim (11) which is intended to roll against a foundation surface, and an intermediate part (12) which connects the central part with the wheel rim, characterized by the com¬ bination in which the wheel rim (11) is composed of a plurality of parts (21; 35) which are made of an elastic material and which are mutually separated from one another in the peripheral direc¬ tion of the wheel, each of the wheel rim parts including two or more beam elements (24, 25; 37, 38, 39) which are located at mutually different radial distances from the wheel axis (23) and which extend alternatingly towards opposite sides of the wheel, the radially innermost beam element (24; 37) having one end connected substantially rigidly to said inter¬ mediate part (12) and the other end thereof connected sub¬ stantially rigidly to one end of the next following beam ele¬ ment (25; 38) which, if not forming the radially outermost beam element, is in turn connected at its other end substan¬ tially rigidly to the next following beam element (39) , and so on; in which the centre distance between said wheel rim parts (21; 35) does not appreciably exceed, and is preferably smaller than the peripheral extension of the wheel rim section in contact with the foundation surface within the intended loading region of the wheel; in which said wheel rim parts (21; 35) are mutually connected by means of a connecting arrangement (28; 47) which transfers substantially solely peripheral forces; and in which said beam elements (24, 25; 37, 38, 39) are so con¬ structed that the radially outermost beam elements (25,' 39) of said wheel rim parts (21; 35) within the loading region of the wheel exert against the foundation surface a pressure which is distributed substantially uniformly across the width of said wheel. 2. A supporting wheel according to Claim 1, characterized in that the connecting arrangement (47) comprises at least one peripherally extending traction ring which is embedded in or let-into said wheel rim parts. 3. A supporting wheel according to Claim 1 or 2, characte¬ rized in that the connecting arrangement (28) includes a relatively soft elastic tread which encircles said wheel rim parts and which is- substantially non-stretchable in the peri- pheral direction of the wheel. 4. A supporting wheel according to Claim 3, characterized in that the tread (28) is higher at the edges thereof than in its central region, such that when the wheel rolls against a foundation surface the edges of the tread will come into con¬ tact with said surface prior to said central tread region. 5. A supporting wheel according to Claim 3 or 4, characte¬ rized in that the wheel rim parts (35) are mutually spaced in the peripheral direction of the wheel to define inter¬ mediate slots (36) , wherein the tread (28) opposite said slots is provided with through-passing recesses (55) which extend from a respective edge of the tread towards the central region thereof, and wherein said central tread region is flexible but substantially non-stretchable in the peripheral direction of the wheel. 6. A supporting wheel according to any of Claims 3 - 5, characterized in that the tread (28) is provided with through-passing apertures (31). 7. A supporting wheel according to any of Claims 1 - 6, characterized in that said beam elements (24, 25; 37, 38, 39) form an angle with the wheel axis (23) when seen from the periphery of the wheel. 8. A supporting wheel according to any of Claims 1 - 7, characterized in that said outermost beam elements (25; 39) have sound absorbing material located on the inner surfaces thereof. 9. A supportinq wheel according to any of Claims 1 - 8, characterized in that damping means (32, 33; 43, 44, 45) are arranged between the beam elements (24, 25; 37, 38, 39) and inwardly of the radially innermost beam elements (24; 37) , for damping and restricting bending of the beam elements.

Inventors: HANSSON HANS-ERIK, HANSSON, HANS-ERIK
Applicants: HANSSON HANS ERIK, HANSSON, HANS-ERIK
Application year: 1987
Main classification: B60B5
IPC codes: B60B5, B60B9, B60C7