HK1167373B - Wheel of polymeric material - Google Patents

Description

Polymer material wheel

Technical Field

The present invention relates to a new construction for a tyre wheel for application to several vehicles, such as cars, light and heavy utility vehicles, motorcycles, tricycles, quadricycles, vehicles for internal transportation of loads and personnel, agricultural vehicles and vehicles for other applications, said wheel being made of a thermoplastic composite material.

Background

As is known in the art, polymer composites are those in which two or more materials are associated to achieve synergy of property and performance optimization, and thus, better characteristics than a single material. Composite materials often result from the association of a polymer matrix with one or more reinforcing materials.

In industry, there is a significant need for products: the product provides weight reduction associated with the feature improvements, performance optimization and differential vision aspects provided by design freedom. In addition to these aspects, it is contemplated that: increased productivity, improved quality, eco-friendly because of recyclability, more comfort and safety, greater autonomy, reduced pollutant emissions, etc.

Light weight alloy wheels are manufactured as a single piece casting and steel wheels are made from stamped rims and discs, requiring welds in which oxidation points can occur, compromising the durability and safety of the product. Another aspect to be considered is that metallic materials have a higher specific gravity than polymeric materials, implying a greater mass for the wheels made with such materials, and therefore heavier vehicles and higher energy and/or fuel consumption.

In addition to the above disadvantages, these known wheels may have permanent deformation (plastic deformation) in the event of an impact, resulting in serious or even permanent damage to the product and the systems associated with the product. In particular, the process of casting light weight alloy wheels increases the likelihood of failure due to the porosity present in the material, which is difficult to control and inherent to the manufacturing process. The subsequent machining step is an expensive and tedious process that produces a lot of oil residues and scrap metal. Furthermore, when analyzing the entire production cycle of a wheel, there is a high consumption of electrical energy, water and other inputs inherent to the casting process.

Attempts have been made to produce polymer wheels reinforced with glass fibers by several processes and often using thermoset materials (non-recyclable), which attempts failed in validation testing or are considered commercially infeasible.

An example of the prior art is described in patent US 4,900,097, which uses a disc inserted between the fixing bolts and the braking system, which disc has the purpose of dissipating heat. In this configuration, the wheel disc can be separated from the plastic rim.

Patent US 3,811,737 suggests the use of metal plates to avoid excessive tightening of the bolts in resins with low compression resistance.

Patent US 3,917,352 has several continuous glass filaments to reinforce the plastic structure, but the manufacturing process is expensive and difficult, making the final product economically unfeasible or not competitive.

In patent US 4,072,358, the wheel is moulded in a process of compressing a Polyamide (PI) sheet with cut glass fibres.

Patent US 5,826,948 has a wheel made in two pieces bonded to each other, requiring two injection molding dies, which increases the production cost.

Patent US 5,268,139 discloses a design to avoid knit lines of different polymer flow lines in the weakened areas, which is a large limitation on the design freedom of the wheel and its plastic form to be adapted to each design requirement.

Known vehicle wheels formed in plastic material are generally obtained from polymer materials, the composition of which has drawbacks in terms of their structural resistance, resistance to weather conditions, ageing, ability to withstand large fastening, and retention in the end of the shaft (in which the wheel is mounted), and also involves complexity of manufacture and adaptation of their structural design to the aesthetic and functional requirements in each application.

Disclosure of Invention

In the face of the drawbacks presented by the vehicle wheels for pneumatic tyres known so far, the object of the present invention is to provide a polymer composite wheel which is easy to manufacture, has high productivity and high versatility of design, also has high resistance to tension, compression, bending and impacts, and ensures a long useful life, even when it is subjected to harmful climatic conditions and chemical attacks during its use in vehicles.

The frontal characteristics achieved by the wheel of the type of single-piece construction proposed herein, which comprises a single body formed by a central wheel disc provided with a window ("decorative hole"), a central hole to be mounted on the end of the axle of the vehicle, a plurality of holes for the passage of fixing bolts, and a peripheral rim configured to hold the vehicle tyre, and comprising, in a homogeneous mixture, 40% to 70% of a thermoplastic polymer matrix (preferably Polyamide (PA)), 30% to 60% of synthetic fibres (preferably synthetic glass fibres combined with carbon fibres), 10% to 30% of an impact modifier, 0.01% to 10% of an additive, a reinforcing material, and a new polymer mixture for injection-moulding a single-piece body, are made possible thanks to suitable items for the product envisaged, which are initially and virtually effective, and to a new polymer mixture for injection-moulding a single-piece body, Stabilizer, lubricant and pigment, wherein the sum of the percentage contents of the components is less than or equal to 100 percent.

In addition to the structural and functional features of the new wheel, it will be appreciated that the body manufactured by the injection molding process allows for reduced production cycle times, elimination of subsequent steps of molding, reduced waste and energy consumption of raw materials, reduced cost, and makes the product economically viable.

The development of the product in terms of aesthetics (design) and functionality (construction) is linked to computer simulations, such as analyses in terms of structure, fatigue and morphology (machinability) by using software for Finite Element Analysis (FEA); interactive analysis between design/product/raw material/process and tool; and virtual simulation of physical test bed testing, which speeds up the analysis of product performance, thereby avoiding trial and error.

Such simulation reduces the time and cost involved in the steps of conception, development and approval of the product. Finally, laboratory and fatigue tests associated with durability and field testing can approve products that comply with specific application requirements. However, due to the lack of specific national and international regulations and guidelines for products of this polymer composite type, performance evaluations have been performed based on the specifications and guidelines of SAE, ISO and NBR (brazilian regulations) applied to existing products, which are typically manufactured in metal materials and their alloys, except for the requirements of some vehicle manufacturers.

Another point to be considered is that the vehicle does not need to be modified to receive the wheel of the present invention.

Drawings

The invention will be described below with reference to the accompanying drawings given as illustrations of possible embodiments for the present wheel, and in which:

FIG. 1 depicts a partial cut-away perspective view of a wheel construction without an insert;

FIG. 2 depicts a perspective view, partially in section, of a wheel construction provided with an insert of a metal alloy attached to the inside of the central bore of the central wheel disc to cover the entire axial extension of the central bore;

FIG. 3 depicts a perspective view similar to FIG. 2, but illustrating the eccentric bore of the middle disk being internally covered by an insert of a metal alloy throughout its axial extension;

FIG. 4 depicts a perspective view similar to FIG. 3, but illustrating the eccentric bore of the middle disk being internally covered by an insert in a portion of its axial extension;

FIG. 5 depicts a perspective view similar to FIGS. 2 and 4, with the central bore being internally covered throughout its extension by a respective metal alloy insert and with the eccentric bore being internally covered by a respective metal alloy insert only in a portion of its extension; and

FIG. 6 depicts a perspective view similar to FIG. 5, but illustrating a configuration in which the central bore insert and the eccentric bore insert are formed as a single piece upon which the polymeric material forming the wheel body is injection molded.

Detailed Description

As already mentioned and illustrated in the figures, the present wheel is of the type comprising: a body C formed by a central disc 10 provided with a central hole 11 to be mounted on the axle end of the vehicle and a plurality of eccentric holes 12 for the passage of fixing bolts, and a rim 20 configured to hold the tire of the vehicle. In the illustrated construction, the central bore 11 has a generally cylindrical and axially innermost mounting portion 11a which is mounted about a respective axial end of the vehicle. The eccentric hole 12, on the other hand, has an axially innermost cylindrical portion 12a, which acts as a guide for the body of the bolt for attaching the wheel to the vehicle, and an axially outermost frusto-conical portion 12b, the inside of which houses a conical region of a hexagonal bolt or nut operatively associated with the fastening bolt or nut of the wheel.

According to the invention, the body C is a monolithic piece injection-molded in a polymer composite material that is a homogeneous mixture comprising 40% to 70% of a thermoplastic polymer matrix, 30% to 60% of synthetic fibers, and 0.01% to 10% of additives, the sum of the percentages of the thermoplastic polymer matrix, the synthetic fibers and the additives being less than or equal to 100%.

Preferably, the polymer matrix is obtained by Polyamide (PA), the synthetic fibers being defined by fine flexible long glass fiber filaments, having a high resistance to tension, bending and impacts.

In addition, the preferred additives for forming the body C of the wheel are defined by compatibility agents, aging resistors, heat stabilizers, UV additives/absorbers, flame retardants, processing aids, primary and secondary antioxidants and pigments.

Depending on the forces to which the wheel is subjected during its useful life of the vehicle, it may be convenient and even necessary to provide reinforcing elements, which are constructed in a metal alloy and which take the form of inserts 30, 40 provided only inside the central hole 11 or only inside the eccentric hole 12, or even inside the central hole 11 and the eccentric hole 12, to impart a higher structural resistance to the portion of the body C in direct contact with the end of the shaft of the vehicle or with the bolts used to fasten the wheel to the vehicle.

In the configuration illustrated in fig. 1, the body C does not have the inserts 30, 40.

In the configuration illustrated in fig. 2, only the mounting portion 11a of the central hole 11 is internally covered by the respective insert 30. It should be understood that the insert 30 may extend through the entire axial extension of said mounting portion 11a of the central hole 11, or only through a portion of said extension.

In the configuration of fig. 3, only the eccentric holes 12 are covered internally by the respective tubular inserts 40. In this figure, both the cylindrical portion 12a and the frusto-conical portion 12b of each eccentric hole 12 are completely covered internally by a respective insert 40, the shape of the insert 40 conforming to the form of said portion of the eccentric hole 12.

Fig. 4 illustrates a variant of the configuration of fig. 3, in which the metallic insert 40 does not internally cover the entire frustoconical portion 12b of the respective eccentric orifice 12, but only the adjacent region of the cylindrical portion 12a of said eccentric orifice.

Fig. 5 depicts a configuration in which the central hole 11 has the entire axial extension of its mounting portion 11a covered by the insert 30, while the eccentric holes 12 have only a portion of their axial extension covered by the respective insert 40, as illustrated in fig. 4.

Fig. 6 depicts a construction which incorporates the features defined in the solution of fig. 5, but in which all the inserts 40 of the eccentric holes 12 are joined as a single piece with the insert 30 covering the mounting portion 11a of the central hole 11. It should be understood that the configuration of fig. 5 and 6 also envisages the use of a tubular insert 40, occupying the entire axial extension of the respective eccentric hole 12.

When applied, the metal inserts 30, 40 are over-injected (over-injected) so as to be positioned in the mould before the injection moulding of the polymer composite material, involving these elements and ensuring their positioning and mechanical fixing; or the metal insert is mounted after the injection molding process by means of suitable means for monitoring the displacement and force of the insert. The mechanical fixing is facilitated by the intervention defined by the difference between the diameter of the hole portions 11a, 12b and the outer diameter of the metallic inserts 30, 40, also in the case of the insert 40 of the eccentric hole 12, in relation to the tapering effect of the insert and the product and to the configuration of the knurls applied to the outer wall of said insert. The requirements and configuration of each product will determine which process is best for each type of insert.

The above described construction allows the wheel to be produced as a single element (and not as a later joined module) and, if necessary or required by the project, may include an insert of metal alloy in the region of mounting to the vehicle to prevent the tension relaxation effect which could eventually cause the fixing bolts/nuts to lose their torque.

The wheel is formed by thermoplastic injection moulding, which allows for greater precision, repeatability and productivity, enabling a single piece to be obtained, with a large degree of freedom in design and using recyclable materials.

Thereby ensuring the quality of the final product, with greater precision and repeatability, higher productivity, elimination and reduction of the subsequent steps and processes of moulding, reduction of waste of raw materials and with less energy consumption, thus enabling to obtain a single piece, with a large freedom of design and by using recyclable materials.

Virtual analyses (virtual simulations) and physical laboratory tests according to SAE, ISO and NBR rules show positive results, in some cases superior to the test results typically present in alloy-made wheels. The result of this success is due to the design and structure of the body C and to the correct choice of a polymer composite material having mechanical properties superior to those of the commonly used alloys, such as resistance to the tensile forces associated with yielding/breaking, which confers high energy absorption properties (elastic deformation) to the product without damage (plastic deformation). Furthermore, the weight can be reduced by 20 to 40% and 30 to 50% compared to light weight alloy and steel wheels, respectively.

Claims (5)

1. A polymeric material wheel, of the type comprising: a body (C) formed by a central wheel disc (10) and a wheel rim (20) configured to hold a vehicle tyre, said central wheel disc having a central hole (11) to be mounted on an axle end of a vehicle and a plurality of eccentric holes (12) for the passage of fixing bolts, said body (C) of said wheel being injection-molded in a single piece from a polymer composite material, said polymer composite material being a homogeneous mixture comprising 40% to 70% of a thermoplastic polymer matrix, 30% to 60% of synthetic fibers and 0.01% to 10% of an additive, the sum of the percentages of said thermoplastic polymer matrix, said synthetic fibers and said additive being less than or equal to 100%, said central hole (11) having an axially innermost mounting portion (11a) and said eccentric holes (12) having an axially innermost cylindrical portion (12a) and an axially outermost frusto-conical portion (12b), at least one of the portions defined by the mounting portion (11a) of the central hole (11) and the eccentric hole (12) is internally covered, in at least a portion of its axial extension, by a respective insert (30, 40) of a metal alloy, which is axially and radially attached to the central disc (10) of the body (C) of the wheel, characterized in that all the inserts (40) of the eccentric hole (12) are joined in a single piece with the tubular insert (30) covering the mounting portion (11a) of the central hole (11).

2. A wheel as claimed in claim 1, wherein said thermoplastic polymer matrix is Polyamide (PA).

3. A wheel as claimed in claim 2, wherein said additive is defined by at least one of the following ingredients: compatibility agents, ageing inhibitors, heat stabilizers, UV absorbers, flame retardants, processing aids, primary and secondary antioxidants and pigments.

4. A wheel as claimed in claim 1, wherein the polymer composite forming said body (C) of said wheel is moulded around at least one insert (30, 40).

5. Wheel according to claim 1 or 4, wherein only the adjacent areas of said cylindrical portion (12a) and of said frusto-conical portion (12b) of said eccentric orifice (12) are internally covered by respective inserts (40).