The present disclosure relates to a hybrid axle and particularly to a hybrid metal-composite axle for a vehicle.

BACKGROUND

As is already known, an axle is an important part of a transmission system of a vehicle. Considering the various loads acting on the axle in operation, it is critical to ensure that the axle is designed to withstand all these loads, without unnecessarily adding to an overall weight of the vehicle. Figure 1 illustrates a schematic view depicting various loads acting on a conventional axle 100 of a vehicle. As illustrated, there are various factors that need to be taken into consideration while designing the axle.

For example, for increasing a torsional load carrying capacity of the vehicle, a thickness of the axle can be increased with conventional material. However, this would in turn significantly increase the weight of the vehicle, which is a critical factor, as this would lead at least to an increase in energy requirement for the propulsion of the vehicle. Therefore, there are various considerations to be factored in while developing the construction and composition of the axle. Further, it is extremely critical to ensure that the weight of the axle should not be negatively affecting other weight-associated operational parameters of the vehicle.

SUMMARY

This summary is provided to introduce a selection of concepts, in a simplified format, that are further described in the detailed description of the invention. This summary is neither intended to identify key or essential inventive concepts of the invention and nor is it intended for determining the scope of the invention.

In an implementation of the present disclosure, a hybrid metal-composite axle for a vehicle is disclosed. The hybrid metal-composite axle includes a metal bar and a plurality of layers of a bi-directional composite formed on the metal bar. The composite is Fiber-Reinforced Polymer (FRP). The hybrid metal-composite axle further includes an epoxy resin disposed between the metal bar and a surrounding layer of bi-directional composite, and between adjacent layers of the bi-directional composite, from among the plurality of layers of the bi-directional composite. The epoxy resin is adapted to be a binding agent when hardened, forming the hybrid metal-composite axle.

In another implementation of the present disclosure, a method of forming a hybrid metal-composite axle for a vehicle is disclosed. The method includes measuring various dimensions of a metal bar and preparing a composite weave to be formed into a plurality of layers of a bi-directional composite based on the dimensions of the metal bar. The composite is Fiber-Reinforced Polymer (FRP). The method includes applying a coat of epoxy resin on the metal bar and winding the plurality of layers of the bi-directional composite on the coated metal bar with a helix angle of 45 degrees. The epoxy resin is also disposed between adjacent layers of the bi-directional composite, from among the plurality of layers of the bi-directional composite. The epoxy resin is adapted to be a binding agent when hardened, forming the hybrid metal-composite axle.

To further clarify the advantages and features of the present invention, a more particular description of the invention will be rendered by reference to specific implementations thereof, which is illustrated in the appended drawings. It is appreciated that these drawings depict only typical implementations of the invention and are therefore not to be considered limiting of its scope. The invention will be described and explained with additional specificity and detail with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:

Figure 1 illustrates a schematic view depicting various loads acting on a conventional axle of a vehicle;
Figure 2 illustrates a schematic view illustrating a hybrid metal-composite axle depicting a layer of bi-directional composite being wound on a metal bar, according to an implementation of the present disclosure;
Figure 3 illustrates various cross-sectional views of the hybrid metal-composite axle of a vehicle, according to an implementation of the present disclosure;
Figure 4 illustrates a schematic view of the hybrid metal-composite axle disposed in the vehicle, according to an implementation of the present disclosure; and
Figure 5 illustrates a method of forming the hybrid metal-composite axle of the vehicle, according to an implementation of the present disclosure.

Further, skilled artisans will appreciate that elements in the drawings are illustrated for simplicity and may not have necessarily been drawn to scale. For example, the flow charts illustrate the method in terms of the most prominent steps involved to help to improve understanding of aspects of the present invention. Furthermore, in terms of the construction of the device, one or more components of the device may have been represented in the drawings by conventional symbols, and the drawings may show only those specific details that are pertinent to understanding the implementations of the present invention so as not to obscure the drawings with details that will be readily apparent to those of ordinary skill in the art having benefit of the description herein.

DETAILED DESCRIPTION OF FIGURES

For the purpose of promoting an understanding of the principles of the invention, reference will now be made to the implementation illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated system, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skilled in the art to which this invention belongs. The system, methods, and examples provided herein are illustrative only and not intended to be limiting.

Whether or not a certain feature or element was limited to being used only once, it may still be referred to as “one or more features” or “one or more elements” or “at least one feature” or “at least one element.” Furthermore, the use of the terms “one or more” or “at least one” feature or element do not preclude there being none of that feature or element, unless otherwise specified by limiting language including, but not limited to, “there needs to be one or more...” or “one or more element is required.”

Unless otherwise defined, all terms and especially any technical and/or scientific terms, used herein may be taken to have the same meaning as commonly understood by a person ordinarily skilled in the art.

Reference is made herein to some “implementations.” It should be understood that an implementation is an example of a possible implementation of any features and/or elements of the present disclosure. Some implementations have been described for the purpose of explaining one or more of the potential ways in which the specific features and/or elements of the proposed disclosure fulfil the requirements of uniqueness, utility, and non-obviousness.

Use of the phrases and/or terms including, but not limited to, “a first implementation,” “a further implementation,” “an alternate implementation,” “one implementation,” “an implementation,” “multiple implementations,” “some implementations,” “other implementations,” “further implementation”, “furthermore implementation”, “additional implementation” or other variants thereof do not necessarily refer to the same implementations. Unless otherwise specified, one or more particular features and/or elements described in connection with one or more implementations may be found in one implementation, or may be found in more than one implementation, or may be found in all implementations, or may be found in no implementations. Although one or more features and/or elements may be described herein in the context of only a single implementation, or in the context of more than one implementation, or in the context of all implementations, the features and/or elements may instead be provided separately or in any appropriate combination or not at all. Conversely, any features and/or elements described in the context of separate implementations may alternatively be realized as existing together in the context of a single implementation.

Any particular and all details set forth herein are used in the context of some implementations and therefore should not necessarily be taken as limiting factors to the proposed disclosure.

Implementations of the present invention will now be described below in detail with reference to the accompanying drawings.

It is one of the objectives of the present invention to design and develop an axle for a vehicle, which is light weight and has desired mechanical properties, ultimately leading at least to power saving in the propulsion of the vehicle.

Figure 2 illustrates a schematic view illustrating a hybrid metal-composite axle 200 of a vehicle, according to an implementation of the present disclosure. For the sake of readability, the hybrid metal-composite axle 200 is hereinafter interchangeably referred to as the hybrid axle 200. Figure 3 illustrates various cross-sectional views of the hybrid axle 200, according to an implementation of the present disclosure. For the sake of brevity, constructional and operational details of the hybrid axle 200 are explained while collectively referring to Figure 2 and Figure 3.

Referring to Figure 2 and Figure 3, the hybrid axle 200 may include, but is not limited to, a metal bar 202 and a plurality of layers 204 of a bi-directional composite formed on the metal bar 202. Particularly, in the Figure 2, only one of the layers 204 having been wound in multiple turns on the metal bar 202 is illustrated. In an implementation, the composite may include, but is not limited to a Fiber-Reinforced Polymer (FRP). In an implementation, the FRP in the layers 204 of the bi-directional composite is glass fiber.

In an example, each of the layers 204 of the bi-directional composite has a Grams per Square Meter (GSM) of about 350 and a weave factor of 0.5. In an embodiment, mechanical properties of the hybrid axle 200 may be adapted to change based on orientation of fibers in a polymer matrix of the composite, which is not achievable from the conventional monolithic materials. In fact, owing to optimum directional orientation of the fibers, the composite material has better shear strength in comparison to existing metal axles.

The hybrid axle 200 may also include an epoxy resin 302 disposed between the metal bar 202 and a surrounding layer 204 of bi-directional composite. Therefore, the epoxy resin 302 may be adapted to attach a layer 204 of the bi-directional composite to the metal bar 202.

The epoxy resin 302 may also be disposed between adjacent layers 204 of the bi-directional composite. In an implementation, the epoxy resin 302 may be adapted to be a binding agent when hardened, forming the hybrid axle 200. In an implementation, the epoxy resin may include, but is not limited to, a B class epoxy resin. When the epoxy resin is hardened, it forms bondage with the glass fiber.

In an implementation, the hybrid axle 200 may include three layers 204 of bi-directional composite formed on the metal bar 202. Figure 3 particularly illustrates three layers 204 of the bi-directional composite formed on the metal bar 202. As would be appreciated by a person skilled in the art, the scope of the present invention is not limited to 3 layers 204 of the composite. In other implementations, the number of layers 204 formed on the metal bar 202 may vary, say, depending on constructional and operational requirements of the hybrid axle 200, without departing from the scope of the present disclosure.

In an implementation, each layer 204 may be wound on the metal bar 202 with a helix angle (a) of 45 degrees from a central axis of the metal bar 202. As would be appreciated by a person skilled in the art, in other implementations, the helix angle may vary depending on constructional and operational parameters of the metal bar 202 and the bi-directional composite, without departing from the scope of the present disclosure.

In an implementation, a helical length of each layer 204 of the bi-directional composite is determined based on a number of turns, a circumference of the metal bar 202, and a turning pitch. The turning pitch may further be determined based on a diameter of the metal bar 202. Particularly, the turning pitch may be determined as:

Pitch = pD tan?(45 ? ) ---------------------- (1)

Further, the number of turns may be determined based on a length of the metal bar 202 and the turning pitch. Particularly, the number of turns may be determined as:
Number of turns = l / p ------------------- (2)

Furthermore, the helical length of the layers 204 to be wound on the metal bar 202 may be determined as:
The helical length = nv(c^2+p^2 ) --------- (3)

In an implementation, the hybrid axle 200 may be formed of two portions separated by a transmission box, when disposed in the vehicle. Figure 4 illustrates a schematic view of the hybrid axle 200 disposed in the vehicle, according to an implementation of the present disclosure. In an implementation, the hybrid axle 200 may include, but is not limited to, a first portion 402 and a second portion 404 distal to the first portion 402. In the illustrated implementation, the first portion 402 is disposed between a wheel 406 of the vehicle and the transmission box 408 whereas the second portion 404 is disposed between another wheel 410 and the transmission box 408.

In an implementation, the first portion 402 may have a length of 855 mm. In such an implementation, each layer 204 of the bi-directional composite on the first portion 402 may have a helical length of about 1250 mm and a turning pitch of about 90 mm. Further, 10 turns of each layer 204 may be wound around the first portion 402.

Similarly, in an implementation, the second portion 404 may have a length of 365 mm. In such an implementation, each layer 204 of bi-directional composite on the second portion 404 may have a helical length of about 500 mm and a turning pitch of about 90 mm. Further, 4 turns of each layer 204 may be wound around the second portion 404.

In the abovementioned implementations, each layer 204 of bi-directional composite having a GSM of 350 is cut into stripes of (1250 mm x 90 mm) and (500 mm x 90 mm) for the first portion 402 and the second portion 404, respectively.

Figure 5 illustrates a method 500 of forming the hybrid axle 200 of the vehicle, according to an implementation of the present disclosure. For the sake of brevity, the constructional and operational features of the hybrid axle 200 that are already explained in detail in the description of Figure 2, Figure 3, and Figure 4 are not explained in detail in the description of Figure 5.

At a block 502, the method 500 includes measuring various dimensions of the metal bar 202. The dimensions may include, but are not limited to, a length (l) and a diameter (D) of the metal bar 202.

At a block 504, the method 500 includes preparing, based on the dimensions of the metal bar 202, a composite weave to be formed into the plurality of layers 204 of the bi-directional composite. The composite may include, but is not limited to, FRP.

At a block 506, the method 500 includes applying a coat of the epoxy resin 302 on the metal bar 202.

At a block 508, the method 500 includes winding the plurality of layers 204 of the bi-directional composite on the coated metal bar 202 with a helix angle of 45 degrees.

The epoxy resin 302 may be disposed between adjacent layers 204 of the bi-directional composite. Further, the epoxy resin 302 may be adapted to be a binding agent when hardened, forming the hybrid axle 200.

As would be gathered, the hybrid axle 200 of the present disclosure is light weight and can withstand any sort of loads in operation. In the conventional axles, the stresses developed usually remain prominent on the surface, as the loading conditions tend to strain the metal axle resulting in the wear. The solution to increase the strength is via increasing inertial distribution such that surface stresses are overcome by the layer 204 of composite that has more torsional rigidity and load bearing strength as compared to the conventional metal axle. This provides the flexibility in the design of the axle 200 as well. The diameter of the metal bar 202 can be decreased and a significant layer of epoxy 302 and the glass fiber can envelop the metal bar 202. The weight of the overall axle 200 also decreases since the density of glass fiber is less than that of metals.

Further, owing to high strength to weight ratio of the composite, if the thickness of the hybrid axle 200 is increased by depositing more composite, an increase in the weight of the vehicle would be significantly less in comparison to the increase in weight when the thickness increase of the hybrid axle 200 is achieved by depositing more conventional material. Therefore, thickness required for carrying certain torque is more in metal as compared to the hybrid axle 200 of the present disclosure, leading to light weight construction.

Further, with the use of the hybrid axle 200, shear strength as well as fatigue properties are improved. Furthermore, crack propagation in the hybrid axle 200 can be suppressed by using fiber having stiffness higher than the matrix. This would help in limiting the strain within the matrix, resulting in inhibition of initiation of micro cracks. In case the micro cracks are initiated for any other reason, the proposed construction of the hybrid axle 200 would prevent them from transforming into larger cracks.

Generally, possibility of crack becoming critical depends on two parameters – energy release rate (G) and crack resistance (R). If the energy release rate (G) exceeds the crack resistance (R), the crack becomes critical. Since outer layer in the proposed hybrid axle 200 is formed of FRP, more energy is required for the crack to become an unstable crack. Further, to some extent, anelastic deformation at the crack tip is governed by different mechanism, i.e., polymer chains align themselves parallel to each other under high stress and thereafter dissipate energy. On the other hand, since the metal bar 202 is ductile in nature, plastic deformation occurs at the crack tip, leading to the crack tip getting blunt, in turn reducing the stress at the tip.

Also, stress concentration areas in the hybrid axle 200 are less and the creep resistance is high. Moreover, the hybrid axle 200 can operate for longer duration without lubrication. In addition, rust proofing and corrosion resistance of the hybrid axle 200 extends the service life of the hybrid axle 200. Furthermore, from the maintenance perspective, since the outer surface of the hybrid axle 200 is formed of the FRP, if any cracks become critical, it can be easily detected and conveniently repaired, at least in comparison to the existing metal axles.

While specific language has been used to describe the present subject matter, any limitations arising on account thereto, are not intended. As would be apparent to a person in the art, various working modifications may be made to the method in order to implement the inventive concept as taught herein. The drawings and the foregoing description give examples of implementations. Those skilled in the art will appreciate that one or more of the described elements may well be combined into a single functional element. Alternatively, certain elements may be split into multiple functional elements. Elements from one implementation may be added to another implementation.

We Claim:

1. A hybrid metal-composite axle (200) for a vehicle, the axle (200) comprising:
a metal bar (202);
a plurality of layers (204) of a bi-directional composite formed on the metal bar (202), wherein the composite is Fiber-Reinforced Polymer (FRP); and
an epoxy layer (302) disposed between the metal bar (202) and a surrounding layer (204) of bi-directional composite and between adjacent layers (204) of the bi-directional composite, from among the plurality of layers (204) of the bi-directional composite, wherein the epoxy layer (302) is adapted to be a binding agent when hardened, forming the hybrid metal-composite axle (200).

2. The hybrid metal-composite axle (200) as claimed in claim 1, wherein the FRP in the plurality of layers (204) of the bi-directional composite is glass fiber.

3. The hybrid metal-composite axle (200) as claimed in claim 1, wherein each of the plurality of layers (204) of bi-directional composite has a Grams per Square Meter (GSM) of about 350 and a weave factor of 0.5.

4. The hybrid metal-composite axle (200) as claimed in claim 1, wherein the epoxy layer (302) is a B class epoxy layer (302) .

5. The hybrid metal-composite axle (200) as claimed in claim 1, comprising three layers (204) of bi-directional composite formed on the metal bar (202) and having a helix angle of 45 degrees from a central axis of the metal bar (202).

6. The hybrid metal-composite axle (200) as claimed in claim 1, wherein a helical length of each layer (204) of the bi-directional composite is determined based on a number of turns, a circumference, and a turning pitch.

7. The hybrid metal-composite axle (200) as claimed in claim 1, comprising:
a first portion (402) having a length of 855 mm, wherein each layer (204) of bi-directional composite on the first portion (402) has a helical length of about 1250 mm, a turning pitch of about 90 mm, and includes 10 turns; and
a second portion (404) distal from the first portion (402) by a transmission box (408) and having a length of 365 mm, wherein each layer (204) of bi-directional composite on the second portion (404) has a helical length of about 500 mm, a turning pitch of about 90 mm, and includes 4 turns.

8. The hybrid-metal composite axle (200) as claimed in claim 7, wherein each layer (204) of bi-directional composite having a GSM of 350 is cut into stripes of (1250 mm x 90 mm) and (500 mm x 90 mm) for the first portion (402) and the second portion (404), respectively.

9. The hybrid-metal composite axle (200) as claimed in claim 1, wherein constituent mechanical properties are adapted to change based on orientation of fibers in polymer matrix of the composite.

10. A method (500) of forming a hybrid metal-composite axle (200) for a vehicle, the method (500) comprising:
measuring various dimensions of a metal bar (202);
preparing, based on the dimensions of the metal bar (202), a composite weave to be formed into a plurality of layers (204) of a bi-directional composite based on the measurement, wherein the composite is Fiber-Reinforced Polymer (FRP);
applying a coat of epoxy layer (302) on the metal bar (202);
winding the plurality of layers (204) of the bi-directional composite on the coated metal bar (202) with a helix angle of 45 degrees,
wherein the epoxy layer (302) is also disposed between adjacent layers (204) of the bi-directional composite, from among the plurality of layers (204) of the bi-directional composite, wherein the epoxy layer (302) is adapted to be a binding agent when hardened, forming the hybrid metal-composite axle (200).