Patent Application
20190217661
The present invention refers to a wheel system for a vehicle comprising a wheel structure, a core and a tire, and it may be used in vehicles, preferably light vehicles, for example, wheelchairs, bicycles, velocipedes and others.
Currently, a wheel and tire assembly for a two-wheeled vehicle, or for a wheelchair, in most cases, comprises a metal or plastic wheel, and a tire with or without a tube. For example, in the case of a wheelchair, the rear wheels are usually made of plastic resin and generally have two types of tires.
A solid tire, manufactured with a rubber-based blend and various fillers. Wherein such tire is placed by means of a mechanical equipment that stretches it to fit it in the gutter of the wheel.
There is also another type of tire found on bicycles, which is the inflatable tire with tube. This tire is assembled using specific tools.
Inflatable tires can be punctured and uncalibrated, creating an inconvenience for a user with reduced mobility.
In turn, the solid tires, due to the high presence of fillers, which reduce their cost of production, have pronounced wear and mark the floor with carbon blacks (black filler used in high percentage to leave it in the color black and reduce price).
It is noted that the use of fillers is necessary and important for obtaining the desired properties. A filler, according to ISO 1382:1996, is an “ingredient of solid composition usually added in relative large amounts to the rubber or latex compositions for technical or economic reasons”. The fillers are intended to improve mechanical properties (reinforcing fillers) and lower the price of the compound (filling or dilution fillers).
The choice of a filler and its proportion in the compound depends mainly on the properties required to the vulcanizate. The fillers are added to provide hardness, toughness, stiffness, abrasion resistance, electrical conductivity, dynamic properties, lower price, etc. The fillers influence the viscosity of the rubber compound and the contraction. In general, the higher the filler volume, the greater the compound viscosity and production problems. The various types of fillers may be combined in the same rubber compound, depending on the desired properties and the desired price.
The maximum amount of a filler, which may be incorporated into a rubber compound, depends on the elastomer, the type and amount of plasticizer used and the nature and ability to provide reinforcement of the filler.
Carbon black, commonly known as lampblack, is a black reinforcing filler, and together with silica is one of the most used fillers.
In the present specification, it will be discussed, by way of illustration, a wheel assembly to be applied preferably in wheelchairs, however nothing prevents the assembly from being applied to any light vehicle using wheels. For example, in wheels for adult wheelchair, which are generally of 24″, and in bicycle wheels, which range from 12″ to 26″ (12, 14, 16, 18, 20, 22, 24 and 26″). In the latter case, the system of the invention would have to be shaped for each different diameter, but the principle of core would be the same.
It is important to notice that, in addition to the two types previously described, there is still a third type of wheel system, comprising a tire made of a bi-component foam expanded with internal cord, acting as a stretching reducer, which is intended to simulate the Inflatable tire. Such foam makes it solid, makes it comfortable and prevents it from puncturing; however, it has drawbacks as it is used by few due to the high commercial value. In addition, because depigmentation occurs in a short time, it tends to become yellowish. Another drawback is that it is only found in the foreign market and it is difficult to import.
In short, currently, there are three types of tires for use in wheelchairs, the latter being practically unfeasible on account of cost. Thus, the three types are as follows: Solid rubber (it is cheap, it does not puncture, but it is hard and uncomfortable), tire with bicycle type tube (it has a reasonable price, but it punctures and is uncalibrated) and the tire made by an expanded foam, which makes it solid and simulates the inflatable tire, (it does not puncture and it is comfortable, but it is very expensive, difficult to import and it loses color).
Japanese Patent Document JP2009056043, published on Mar. 19, 2009, deals with the provision of a thrust ring connection structure, which connects said thrust ring to a wheel of a wheelchair. The idea of the invention described therein is that, in the connection structure of the thrust ring, screw a support with a first fastening screw (a male screw) into the inner surface of an aluminum ring before the tire is assembled. At the time a protruding part of the support is out of the aluminum ring, the tire is secured to the aluminum ring with the support.
A pressure flange is applied to the thrust ring, contacting the faces of the protruding parts of a plurality of supports, and it is connected to the thrust ring, which contacts the faces with screws. Thus, the thrust ring is physically attached to the wheel.
The invention described in this document is not intended to facilitate the assembly of the tire on the wheel, but rather to facilitate that the thrust ring be assembled and disassembled without the need for full disassembly of the tire and wheel assembly. That is, this is made by the connection structures arranged in a removable manner. Thus, there is no facility for tire replacement on wheels, the same being made in the traditional manner.
Another patent document, U.S. Pat. No. 4,371,213, which was published on Feb. 1, 1983, refers to a dual wheel having a plurality of inner and outer spoke members and fastening assemblies. Each inner spoke member has a ring portion, which comprises a radially inclined surface, and an adjacent radially directed surface oriented in a plane substantially perpendicular to the rotational axis of the wheel. Each outer spoke member has a ring portion, which comprises spaced-apart axially projecting wing portions, providing outwardly facing for pairs of surfaces axially inner and axially outer oriented from axially bent surfaces. Furthermore, a surface is radially directed so as to extend inwardly between the axially inner pair of axially oriented surfaces which are substantially perpendicular to the rotational axis of the wheel, and provide a mounting location for an axially projecting member of a fastening assembly.
One object of the invention described in said prior art document is to enable large diameter tires to be mounted on small diameter rings by means of the fastening assemblies described therein. One of the drawbacks is the difficulty to perform the fastening of the spokes and the rings to the assembly of the tires. In fact, the fastening system requires the tightening of screws, and makes the assembly of the tire and wheel assembly take a long time to be accomplished.
The present invention aims to solve these and other drawbacks, as will be better described below.
It is an object of the invention to cause the replacement, when necessary, of the tire assembly to be made rapidly.
It is an object of the invention to reduce the acquisition costs of the tire assembly.
It is another object of the invention to prevent the surfaces of the floors from being marked by the use of the tires.
It is another object of the invention to provide a wheel assembly having a running with great softness.
It is another object of the invention to increase the durability of the tires.
It is another object of the invention to prevent the tire from escaping from the ring gutter.
It is another object of the invention to provide options of permanent colors, which will not yellow with the use.
It is another object of the invention to provide a tire system which, being solid, with rigid core, does not puncture or becomes uncalibrated and simulates the softness of the pneumatic tire.
The present invention uses materials of thermoplastic resin, or any plastic product, from rigid to flexible, from plastic grain produced in petrochemicals or recyclers.
The tire used in the present invention is made of flexible plastic, but has a quite different construction from those mentioned in the state of the art, since to prevent it from escaping from the wheel gutter, during its manufacture, it is over-injected in an member called core. Thus, a wheel model was developed which, instead of having a gutter for the tire to be simply fitted, it has a “T”-shaped member for the engagement function, wherein the flexible plastic tire and the core are permanently connected and fitted in said member, with no possibility of escape.
Thus, the invention consists of a tire and wheel assembly comprising a part having a substantially rigid material, called a core, wherein the tire will also be permanently attached by over-injection, but it will be attached to the wheel through the core by engagement, so as to ensure that there is no escape, and also by screws. Thus, when the tire is worn, only the tire with the core will simply be detached from the wheel and replaced.
The manufacturing method comprises the following steps: Through a first injection mold the wheel structure is produced and reserved, then in another mold the core is produced, this part (core) is then placed in a third mold that receives the over-injection of the soft plastic that will act as a tire. A tire/core assembly is then produced, wherein only the rigid ends of the core are visible and are then coupled to the wheel. In fact, these parts will then be fitted in the negative of the wheel. It is noticed that to increase the resistance and to prevent the escape from the gutter, such parts can also be screwed to the wheel.
The function of the tire is simply to make contact with the ground, and the core the strong connection between tire and wheel.
During manufacture, when the core enters the third mold, the soft plastic (flexible thermoplastic resin) only fills the “T”-shaped part, joining the two pieces, the indentations of the core, which will be engaged in the wheel, are left out, without receiving this resin.
In a preferred embodiment, the invention comprises a ring-shaped part, with its own structure (core) for locking the resin wherein it is over-injected flexible thermoplastic resin or thermoplastic rubber of hardness between Shore A35 to 90. In this way, it is created a rigid core, inside the flexible tire, with male catches leaving the tire, making it possible to make a connection to the wheel by means of the female recess that is in it. The final attachment can be made by means of snap fit only or the use together with screws. This system, depending on the hardness of the chosen resin, replaces the inflatable tire in terms of shock absorption and, because it is solid, it does not puncture or becomes uncalibrated. As it is not made of a rubber solid, it does not dirty the floor where it passes.
In an alternative embodiment of the invention (not shown in the drawings), the tire assembly comprises a tire injected in PVC (polyvinyl polychloride) of hardness between Shore A 55 to 90, which has a negatives and positives fitting the negatives and positives of the injected wheel. In this way, the wheel and the tire can be easily assembled and disassembled. In order to increase safety, their fastening can be secured by means of plastic pins and screws. The material of the tire has high resistance to wear and it does not dirty the floor. This system replaces the current vulcanized rubber tire.
In fact, the alternative embodiment is an option with lower cost of production, since the rigid core is not used as the tire is directly fitted into the wheel cavities (recesses), which can, in order to increase safety, receive screws that are removed to allow the change when worn.
Both PVC and thermoplastic rubber can be used in the existing embodiments of the present invention, since the decision is associated to the desire of the user.
Following, the invention will be described in more detail with the aid of examples shown in the form of Figures.
The detail of a first embodiment of the core 1 is illustrated in
The core 1 provides the assembly with a physical strength which allows for a more efficient running and a proper fastening when its “T”-shaped indentations 2 are engaged in the recesses 15 (see
It is noticed that the ellipsoidal holes 4 in addition to assisting in the better attachment of the pneumatic member 18 (see
In
The indentation 2A, which is outside the pneumatic member, has through holes 5 so as to allow a screw, to be used in said hole 5, to be inserted therein to give better attachment to the tire 18. The indentation 2 or 2A may have any shape that allows a good fit with a negative (recess 15—
A thrust ring 8 is shown in
In
The wheel 12 is shown in
In
A further detail of the wheel 12 is illustrated in
A full view of the tire and wheel assembly can be seen in
Having been described examples of preferred embodiments, it is to be understood that the scope of the present invention encompasses other possible variations, it being limited only by the content of the appended claims, which includes possible equivalents.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1020180008820 | Jan 2018 | BR | national |
| 1020180752545 | Dec 2018 | BR | national |
