Description:FORM 2
THE PATENTS ACT, 1970
[39 OF 1970]
&
THE PATENTS RULES, 2003

COMPLETE SPECIFICATION
[SEE SECTION 10, RULE 13]

REAR AXLE ASSEMBLY, A DYNAMIC DAMPER ASSEMBLY AND A VEHICLE
BY
MAHINDRA & MAHINDRA LIMITED, A COMPANY REGISTERED UNDER THE INDIAN COMPANIES ACT, 1913, HAVING ADDRESS AT MAHINDRA RESEARCH VALLEY (MRV), MAHINDRA WORLD CITY, PLOT NO.41/1, ANJUR P.O., CHENGALPATTU, KANCHIPURAM DISTRICT, TAMILNADU – 603004, INDIA

THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED

TECHNICAL FIELD
[001] The present invention relates to a rear axle assembly for a vehicle having a dynamic mass damper assembly for absorbing vibrations from the vehicle, thereby reducing the body booming noise generated at specific desired frequencies during the vehicle movement.

BACKGROUND
[002] Generally, a suspension system includes a plurality of dampers incorporated in a vehicle to provide a smooth ride while traversing a terrain by damping and contributing stiffness thereby negating one or more conditions of the vehicle that include roll, pitch. Such conventional dampers are commonly static including a damper portion and a spring portion consisting of a mechanical spring, such as a helical or torsion springs. Conventional static dampers are commonly mounted on structures or frames of vehicles which are non-moving fixed portions and dissipate energy by converting kinetic energy of structure’s vibration into heat. The damper in a static condition does not move or change its physical characteristic during vehicle running. The conventional static damper arrangement is a passive system and provides only a fixed amount of damping over a particular range of vehicle frequencies. However, such conventional static dampers fail, are less effective and there still exist limitations of generation of vibrations and a body boom noise at specific frequencies, which inherently cannot be addressed by employment of static dampers.
[003] Therefore, there exists a need to provide a rear axle assembly to overcome one or more of the aforementioned problems.
SUMMARY
[004] Accordingly, an exemplary aspect of the present invention discloses a rear axle assembly for reducing body booming noise of a vehicle, said rear axle assembly comprising: a trailing arm assembly located in a left and a right direction of the vehicle;
a rear twist beam interposed between the left and right trailing arm assembly; a bracket mounted spring seat assembly mounted on each of the trailing arm assembly; a strut mounting bracket mounted on each of the trailing arm assembly opposite and offset to the bracket mounted spring seat assembly; and a dynamic damper assembly mounted on each of the trailing arm assembly, said dynamic damper assembly is tuned to desired frequencies for absorbing vibrations from the vehicle, thereby reducing the body booming noise of the vehicle.
[005] According to another aspect, the present invention discloses a dynamic damper assembly for a vehicle for reducing body booming noise of a vehicle said dynamic damper assembly comprising: a dampener bracket having two fork shaped prongs formed from a U-shaped bar and an extending hanger rod projecting outwards from the center of the U-shaped bar; and a mass damper mounted on the extending hanger rod freely rotatable about a damper axis.
[006] According to still another aspect, the present invention discloses a vehicle comprising a dynamic damper assembly mounted on a rear axle assembly.

BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS
[007] The above and other aspects, features, and advantages of certain exemplary embodiments of the present invention will be more apparent from the following description taken in conjunction with the accompanying drawings in which:
[008] Figure 1 illustrates an isometric view of a rear axle assembly for a vehicle with a dynamic damper assembly, according to an exemplary aspect of the present invention;
[009] Figure 2 illustrates a top view of the rear axle assembly, according to an exemplary embodiment of the present invention;
[010] Figure 3 illustrates an exploded isometric view of the dynamic damper assembly, according to the exemplary embodiment of the present invention; and
[011] Figure 4 illustrates an assembled isometric view of the dynamic damper assembly, according to the exemplary embodiment of the present invention.
[012] Persons skilled in the art will appreciate that elements in the figures are illustrated for simplicity and clarity and may have not been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to the other elements to help improve understanding of various exemplary embodiments of the present disclosure. Throughout the drawings, it should be noted that like reference signs are used to depict the same or similar elements, features, and structures.

DETAILED DESCRIPTION
[013] While this invention is susceptible of embodiments in many different forms, there is shown in the drawings and will herein be described in detail, a preferred embodiment of the invention with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the broad aspects of the invention to the embodiment illustrated.
[014] Other aspects, advantages, and salient features of the invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses exemplary embodiments of the invention. Embodiments of the present disclosure will now be described with reference to the accompanying drawings. Embodiments are provided so as to thoroughly and fully convey the scope of the present disclosure to a person skilled in the art. Numerous details are set forth relating to specific components to provide a complete understanding of embodiments of the present disclosure. It will be apparent to the person skilled in the art that the details provided in the embodiments should not be construed to limit the scope of the present disclosure. In some embodiments, well-known processes, well-known apparatus structures, and well-known techniques are not described in detail.
[015] In general, the present invention discloses a rear axle assembly for a vehicle comprising a dynamic damper assembly mounted on a trailing arm assembly located in a left and a right direction of the vehicle, in-between a bracket mounted spring seat assembly and a rear twist beam for absorbing vibrations from the vehicle, thereby reducing the body booming noise generated at specific desired frequencies during the vehicle movement.
[016] According to an exemplary aspect, the present invention discloses a rear axle assembly for reducing body booming noise of a vehicle, said rear axle assembly comprising a trailing arm assembly located in a left and a right direction of the vehicle, a rear twist beam and a dynamic damper assembly. The rear twist beam is interposed between the left and right trailing arm assembly. The rear axle assembly includes a bracket mounted spring seat assembly mounted on each of the trailing arm assembly. The rear axle assembly includes a strut mounting bracket mounted on each of the trailing arm assembly opposite and offset to the bracket mounted spring seat assembly. The dynamic damper assembly is mounted on each of the plurality of trailing arm assembly and is tuned to desired frequencies for absorbing vibrations from the vehicle, thereby reducing the body booming noise of the vehicle. According to the exemplary embodiment, the dynamic damper assembly is additionally provided in the rear axle assembly for the vehicle which has a static damper assembly. Each of the dynamic damper assembly includes a dampener bracket located in-between the bracket mounted spring seat assembly and the rear twist beam, opposite to the strut mounting bracket. Each of the dynamic damper assembly includes a mass damper mounted on the dampener bracket tuned to desired frequencies for absorbing vibrations from the vehicle, thereby reducing the body booming noise generated at specific desired frequencies during the vehicle movement.
[017] According to an exemplary embodiment of the present invention, each of the dynamic damper assembly is welded to the rear axle assembly.
[018] According to the exemplary embodiment of the present invention, each of the dampener bracket has two fork shaped prongs formed from a U-shaped bar and an extending hanger rod projecting outwards from the center of the U-shaped bar.
[019] According to the exemplary embodiment of the present invention, each of the mass damper is mounted on the extending hanger rod. Each of the extending hanger rod has threaded end for coupling via a fastener and a plain end on the other end for enabling welding with trailing arm assembly.
[020] According to the exemplary embodiment of the present invention, each of the mass damper is tuned for desired frequencies in the range of 70 Hz to 100 Hz. The mass of each dynamic damper is 3 kg and is dependent on desired frequency. Each of the mass damper is made of a rubber integrated with a metallic washer.
[021] According to another aspect, the present invention discloses a dynamic damper assembly for reducing body booming noise of a vehicle. The dynamic damper assembly comprises a dampener bracket having two fork shaped prongs formed from a U-shaped bar and an extending hanger rod projecting outwards from the center of the U-shaped bar; and a mass damper mounted on the extending hanger rod freely rotatable about a damper axis (X-X).
[022] According to still another aspect, the present invention discloses a vehicle comprising a dynamic damper assembly mounted on a rear axle assembly.
[023] The terminology used, in the present disclosure, is only for the purpose of explaining a particular embodiment and such terminology shall not be considered to limit the scope of the present disclosure. The use of the expression “at least” or “at least one” suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the disclosure to achieve one or more of the desired objects or results. As used in the present disclosure, the forms “a,” “an,” and “the” may be intended to include the plural forms as well, unless the context clearly suggests otherwise. The terms “comprises,” “comprising,” “including,” “made of” and “having,” are open ended transitional phrases and therefore specify the presence of stated elements, units and/or components, but do not forbid the presence or addition of one or more other elements, components, and/or groups thereof.
[024] The terms and words used in the following description and claims are not limited to the bibliographical meanings, but are merely used by the inventor to enable a clear and consistent understanding of the invention. Accordingly, it should be apparent to those skilled in the art that the following description of exemplary embodiments of the present invention are provided for illustration purpose only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents. Accordingly, it should be apparent to those skilled in the art that the following description of the rear axle assembly referred in the description are for the purpose of understanding and nowhere limit the invention. The skilled person will be able to devise various structures, shapes and components of the rear axle assembly, although not explicitly described herein, embody the principles of the present invention. All the terms and expressions in the description are only for the purpose of the understanding and nowhere limit the invention. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein may be made without departing from the scope of the invention. Terms like left and right, first, second, top, bottom, extending inwards, extending outwards, forward, rearward, and the like are used to differentiate between objects having the same terminology and are in no way intended to represent a chronological order, unless where explicitly stated otherwise. Moreover, all statements herein reciting principles, aspects, and embodiments of the invention, as well as specific examples thereof, are intended to encompass equivalents thereof. Thus, while particular type of structure, material, thickness, area, height, width, length, shape, diameters, quantity, numbers, mass, frequencies, of trailing arm, mounting brackets, springs, struts, dynamic damper assembly with U-shaped bar and outwardly extending rod, of the rear axle assembly have been disclosed, such components and parameters nowhere limit the invention and are provided for understanding of the invention. It will be appreciated that the embodiments may be manufactured with other design parameters and configurations as well and are not limited to those described herein above may be as per operational requirements by making necessary changes and is not limited to those described herein and nowhere limits the scope of the invention and are provided only for reference and for understating purpose of the invention.
[025] Figures 1-4 disclose a rear axle assembly (100), a bush (102), a wheel end bracket (104), a strut mounting bracket (105), a rear twist beam (110), a trailing arm assembly (115L, 115R), a bracket mounted spring seat assembly (120), a spring (125), a dampener bracket (130), an extending hanger rod (135); a mass damper (140), a fastener (145), a rear strut (150) and a dynamic damper assembly (200).
[026] Figures 1-4, according to an exemplary embodiment, discloses a rear axle assembly (100). The rear axle assembly (100) comprises a trailing arm assembly (115L, 115R) located in a left and a right direction of the vehicle. The rear axle assembly (100) further comprises a rear twist beam (110) interposed between the left and right trailing arm assembly (115L, 115R). Each of the trailing arm assembly (115L, 115R) may include for example but not limited to a bush (102) coupled with a top end of left and right trailing arm assembly (115L, 115R). Each of the trailing arm assembly (115L, 115R) may include for example but not limited to a wheel end bracket (104) coupled with a bottom end of each of the left and right trailing arm assembly (115L, 115R) and a strut mounting bracket (105) coupled intermediate each of the left and right trailing arm assembly (115L, 115R). A bracket mounted spring seat assembly (120) is mounted proximate to the bottom end of each of left and right trailing arm assembly (115L, 115R). Each of the left and right trailing arm assembly (115L, 115R) is located opposite and offset to the bracket mounted spring seat assembly (120).
[027] According to the exemplary embodiment, the rear axle assembly (100) comprises for example, but not limited to, a dynamic damper assembly (200) mounted on a moving part, for example, that includes but not limited to, the rear axle assembly (100) i.e., the rear twist beam (110) which moves along an articulation path in a dynamic condition to reduce the in-cab road inputs while passing through different road conditions when a vehicle is moving to reducing body boom noise by absorbing vibrations at specific desired frequencies.
[028] According to the exemplary embodiment, the dynamic damper assembly (200) may be mounted on each of the trailing arm assembly (115L, 115R). Each of the dynamic damper assembly (200) may include, but not limited to, a dampener bracket (130) located in-between the bracket mounted spring seat assembly (120) and the rear twist beam (110), opposite to the strut mounting bracket (105). The dampener bracket (130) may include for example but not limited to a two-pronged fork shaped with the prongs formed from a U-shaped bar and an extending hanger rod (135) projecting outwards from the center of the U-shaped bar. The dampener bracket (130) may include, for example, but not limited to, a mass damper (140) mounted on the extending hanger rod (135) coupled with a fastener (145), for example, a nut. According to an exemplary embodiment, each of the extending hanger rod (135) may include for example a threaded end for coupling via a fastener (145) and a plain end on the other side for enabling welding with trailing arm assembly (115L, 115R). Also, for example the hanger rod may include a hole or a slot and pin for locking the hole or slot and thereby restricting the mass damper. Further, for example the mass damper may be mounted on the hanger rod with a snap fit arrangement.
[029] According to the exemplary embodiment, the size, shape and number, mass, material of dampener brackets (130), mass dampers (140) depend upon the operational requirements which satisfy the desired specific frequencies for absorbing vibrations from the vehicle, thereby reducing the body booming noise generated at specific desired frequencies during the vehicle movement. For example, the damper (140) is made of rubber and integrated with a metallic washer. Each of the mass damper (140) is configured to rotate freely about a damper axis (X-X) only before torquing. After post torque application, each of the mass damper (140) stops rotating. The location of the dynamic damper assembly (200) mount is critical from vibration damping perspective and is dependent on mass of the damper (140) and frequency. The mass of the damper may depend on the desired frequency. According to the exemplary embodiment, mass of each of the damper (140) is for example but not limited to 3 kg and is dependent on upon the operational requirements which satisfy the desired specific frequencies for absorbing vibrations from the vehicle, thereby reducing the body booming noise generated at desired specific frequencies during the vehicle movement.
[030] According to the exemplary embodiment, the dynamic damper assembly (200), for example, may be coupled directly to an existing rear axle assembly structure without any modification. The rear axle assembly (100) comprises, for example, but not limited to a rear strut (150) coupled to the strut mounting bracket (105) at each of the left and right trailing arm assembly (115L, 115R) via a plurality of fasteners that, for example, include but are not limited to nuts and bolts.
[031] According to the exemplary embodiment, each of the trailing arm assembly (115L, 115R), the rear twist beam (110) and the bracket mounted spring seat assembly (120) may be welded with each other.
[032] According to the exemplary embodiment, a spring (125), a top and a bottom spring seat, a bumper stopper, a cap and a screw and a washer may be removably coupled with the bracket mounted spring seat assembly (120).
[033] According to still another aspect, the present invention discloses a vehicle comprising a dynamic damper assembly (200) mounted on a rear axle assembly.
[034] With the teachings of the present invention, according to the exemplary embodiment, each of the springs (125) and the dynamic damper assemblies (200) with the mass dampers (140) tuned for the specific desired frequencies control motion of mass confirming mass damper (140) movement in controlled manner for absorbing vibrations from the vehicle, thereby reducing the body booming noise generated at specific desired frequencies during the vehicle movement, whereby customer feel while vehicle moves on different road conditions is enhanced. With the teachings of the present invention, for example, when the extending hanger rod (135) and U-shaped bar of the dampener bracket (130) of diameter 12mm of the dynamic damper assembly (200) is welded on each of the left and right trailing arm assembly (115L, 115R) and the dynamic mass damper (140) is tuned for desired frequencies in the range of 70 Hz to 100 Hz, the frequency band of boom noise is narrowed, and the amplitude noise levels are reduced by ~ 1 dB (A) till 100 Hz in the drive seat area and by ~ 2-3 dB (A) till 80 Hz in middle seat area in comparison with conventional rear axle assembly with conventional static dampers.
[035] There have been described and illustrated herein several embodiments of exemplary indicative implementation of a rear axle assembly (100) and dynamic damper assembly (200). It will also be apparent to a skilled person that the embodiments described above are specific examples of a single broader invention, which may have greater scope than any of the singular descriptions taught. There may be many alterations made in the description without departing from the scope of the invention. The present invention is simple in construction and design, integrated, cost effective and easy to manufacture and assemble and integrated with existing vehicles also. While particular embodiments of the invention have been described, it is not intended that the invention be limited to said configuration disclosed thereto, as it is intended that the invention be as broad in scope as the art will allow and that the specification be read likewise not restrictive to the terminology described herein above. Any discussion of embodiments included in this specification is solely for the purpose of providing a context for the disclosure. It is not to be taken as an admission that any or all of these matters form a part of the prior art base or were common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application.

, Claims:
1. A rear axle assembly (100) for reducing body booming noise of a vehicle, said rear axle assembly (100) comprising:
a trailing arm assembly (115L, 115R) located in a left and a right direction of the vehicle;
a rear twist beam (110) interposed between the left and right trailing arm assembly (115L, 115R);
a bracket mounted spring seat assembly (120) mounted on each of the trailing arm assembly (115L, 115R);
a strut mounting bracket (105) mounted on each of the trailing arm assembly (115L, 115R) opposite and offset to the bracket mounted spring seat assembly (120); and
a dynamic damper assembly (200) mounted on each of the trailing arm assembly (115L, 115R), said dynamic damper assembly (200) is tuned to desired frequencies for absorbing vibrations from the vehicle, thereby reducing the body booming noise of the vehicle.

2. The rear axle assembly (100) as claimed in claim 1, wherein each said dynamic damper assembly (200) is welded to each of the trailing arm assembly (115L, 115R) of the rear axle assembly (100).

3. The rear axle assembly (100) as claimed in claim 1 or 2, wherein each said dynamic damper assembly (200) has:
a dampener bracket (130) located in-between the bracket mounted spring seat assembly (120) and the rear twist beam (110), opposite to the strut mounting bracket (105), and
a mass damper (140) freely rotatable about a damper axis (X-X) is mounted on the dampener bracket (130) tuned to desired frequencies.

4. The rear axle assembly (100) as claimed in claim 3, wherein each of the dampener brackets (130) has two fork shaped prongs formed from a U-shaped bar and an extending hanger rod (135) projecting outwards from the center of the U-shaped bar.

5. The rear axle assembly (100) as claimed in anyone of the preceding claims 3-4, wherein each of the mass dampers (140) is mounted on the extending hanger rod (135).

6. The rear axle assembly (100) as claimed in anyone of the preceding claims 3-5, wherein each of the mass dampers (140) is tuned for desired frequencies in the range of 70 Hz to 100 Hz.

7. The rear axle assembly (100) as claimed in anyone of the preceding claims 3-6, wherein mass of damper (140) is dependent on desired frequency.

8. The rear axle assembly (100) as claimed in anyone of the preceding claims 3-7, wherein mass of each damper (140) is 3 kg.

9. The rear axle assembly (100) as claimed in anyone of the preceding claims 3-8, wherein each of the mass dampers (140) is made of a rubber integrated with a metallic washer.

10. A dynamic damper assembly (200) for reducing body booming noise of a vehicle said dynamic damper assembly (200) comprising:
a dampener bracket (130) having two fork shaped prongs formed from a U-shaped bar and an extending hanger rod (135) projecting outwards from the center of the U-shaped bar; and
a mass damper (140) mounted on the extending hanger rod (135) freely rotatable about a damper axis (X-X).

11. The dynamic damper assembly (200) as claimed in claim 10, wherein the mass damper (140) is tuned for desired frequencies in the range of 70 Hz to 100 Hz.

12. The dynamic damper assembly (200) as claimed in claim 10 or 11, wherein mass of the mass damper (140) is dependent on desired frequency.

13. The dynamic damper assembly (200) as claimed in anyone of the preceding claims 10-12, wherein mass of the mass damper (140) is 3 kg.

14. The dynamic damper assembly (200) as claimed in anyone of the preceding claims 10-13, wherein the mass damper (140) is made of a rubber integrated with a metallic washer.

15. A vehicle comprising a dynamic damper assembly (200) mounted on a rear axle assembly as claimed in any one of the preceding claims 1-14.