Claims:
1. A camshaft gear mechanism, wherein the camshaft gear mechanism comprising:
a gear (01), wherein the gear (01) comprises a cut-out along the circumference of the gear, and a plurality of first boss located in the cut-out;
a damper element (02), wherein the damper element (02) is disposed in the cut-out, and wherein the inner circumference of the damper element (02) comprises a first semi-circular sections;
a hub (03), wherein the hub (03) comprises a flange, wherein the flange comprises a second semi-circular sections disposed along the circumference of the flange, wherein upon assembly the first semi-circular sections and the second semi-circular sections enclose the plurality of first boss and the plurality of second boss; and
a cover (04), wherein the cover (04) comprises a plurality of second boss located along the circumference of the cover (04), wherein during assembly the plurality of second boss and the plurality of first boss are coupled by fasteners (05).

2. The camshaft gear mechanism as claimed in claim 1, wherein the damper element (02) is made of rubber.

3. The camshaft gear mechanism as claimed in claim 1, wherein the plurality of boss are located equidistance to each other.

4. The camshaft gear mechanism as claimed in claim 1, wherein the fastener (05) is a bolt.

5. The camshaft gear mechanism as claimed in claim 1, the first boss and the second boss are located at circular pitch circle dimeter.

6. The camshaft gear mechanism as claimed in claim 1, the number of first boss and second boss is 12.

7. The camshaft gear mechanism as claimed in claim 1, wherein during operation the torque is transferred from the gear (01) via the damper element (02) and the flange to the hub (03).

, Description:FORM 2

THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENT RULES, 2003

COMPLETE SPECIFICATION
(See Section 10 and Rule 13)

Title of invention:
A RUBBER DAMPED CAMSHAFT GEAR MECHANISM

Applicant:
Tata Motors Limited
A company Incorporated in India under the Companies Act, 1956
Having address:
Bombay House, 24 Homi Mody Street,
Hutatma Chowk, Mumbai 400001,
Maharashtra, India

The following specification describes the invention and the manner in which it is to be performed.

CROSS-REFERENCE TO RELATED APPLICATIONS AND PRIORITY
[001] The present application does not claim priority from any patent application.
TECHNICAL FIELD
[002] The present disclosure in general relates to the field of gear drive system. More particularly, the present subject matter relates to a camshaft gear mechanism in gear drive system.
BACKGROUND
[003] Generally, in a gear pair, torque is transmitted from one gear to another through engagement of gears teeth with each other. These mating gears teeth engage and disengage as the gears rotate. There is clearance called backlash between the mating teeth of gears. During disengagement, faces of the gear teeth collide with each other and manifest in the form of impact energy. This impact energy gets transmitted partly to the supporting structure of the gear and the remaining energy gets radiated from gear surface as rattling noise. Such rattling noise is unpleasant and decrease customer experience. The rattling noise is more prominent in spur gears as compared to helical gears.
SUMMARY
[004] Before the present a camshaft gear mechanism are described, it is to be understood that this application is not limited to a particular a camshaft gear mechanism, as there may be multiple possible embodiments, which are not expressly illustrated in the present disclosures. It is also to be understood that the terminology used in the description is for the purpose of describing the particular implementations, versions, or embodiments only, and is not intended to limit the scope of the present application. This summary is provided to introduce aspects related to a camshaft gear mechanism. This summary is not intended to identify essential features of the claimed subject matter nor is it intended for use in determining or limiting the scope of the claimed subject matter.
[005] In one embodiment, camshaft gear mechanism comprises a gear, a damper element, a hub, and a cover. In one example, the gear comprises a cut-out along the circumference of the gear, and a plurality of first boss located in the cut out. Further, the damper element is disposed in the cut-out, and the inner circumference of the damper element comprises a first semi-circular sections. The hub comprises a flange comprising a second semi-circular sections disposed along the circumference of the flange. The cover comprises a plurality of second boss located along the circumference of the cover, and during assembly the plurality of second boss and the plurality of first boss are coupled by fasteners. In the example, upon assembly the first semi-circular sections and the second semi-circular sections enclose around the plurality of first boss and the plurality of second boss.
BRIEF DESCRIPTION OF DRAWINGS
[006] The foregoing detailed description of embodiments is better understood when read in conjunction with the appended drawings. For the purpose of illustrating the present subject matter, an example of construction of the present subject matter is provided as figures; however, the present subject matter is not limited to the specific a camshaft gear mechanism disclosed in the document and the figures.
[007] The present subject matter is described in detail with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the drawings to refer various features of the present subject matter.
[008] Figure 1 illustrates a cross section of a camshaft gear mechanism, in accordance with an embodiment of the present subject matter.
[009] Figure 2 illustrates an exploded view of the camshaft gear mechanism, in accordance with an embodiment of the present subject matter.
DETAILED DESCRIPTION
[0010] Some embodiments of this disclosure, illustrating all its features, will now be discussed in detail. The words "comprising," "having," "containing," and "including," and other forms thereof, are intended to be open ended in that an item or items following any one of these words is not meant to be an exhaustive listing of such item or items, or meant to be limited to only the listed item or items. It must also be noted that as used herein and in the appended claims, the singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise. Although any camshaft gear mechanism and, similar or equivalent to those described herein may be used in the practice or testing of embodiments of the present disclosure, the exemplary, camshaft gear mechanism are now described.
[0011] Various modifications to the embodiment will be readily apparent to those skilled in the art and the generic principles herein may be applied to other embodiments. However, one of ordinary skill in the art will readily recognize that the present disclosure is not intended to be limited to the embodiments described, but is to be accorded the widest scope consist in this regard, in a generic sense.
[0012] As described above, generally, in conventional gear drive mechanisms, gear rattling noise is observed which is undesirable and a drawback. Typically, the rattling is a result of conventional gears having solid metallic body with no provision to damp the impact energy to attenuate the rattling noise.
[0013] Some conventionally gears comprise rubber moulding on the surface of the gear and some other conventionally gears completely separate the gear teeth rim from the core of the gear by moulding rubber between it. But the problem is with these conventional gears is that the strength of the rubber is less and not sufficient to withstand the torsional forces thereby making it non-usable for medium to high torque application. Moreover, such convention gear with rattling noise damping methods have limitations in terms of durability, life, maintenance and torque transmission capability.
[0014] In the present subject matter, embodiments of a camshaft gear mechanism, is disclosed. In one embodiment, the camshaft gear mechanism comprises a gear, a damper element, a hub, and a cover. In one more embodiment, the gear comprises a cut-out along the circumference of the gear, and a plurality of first boss located in the cut-out. Further, the damper element comprises on the inner circumference a first semi-circular sections and the damper element is is disposed in the cut-out. Furthermore, the hub comprises a flange. In one example, the flange comprises a second semi-circular sections disposed along the circumference of the flange, and the cover comprises a plurality of second boss located along the circumference of the cover. In one example, during assembly the plurality of second boss and the plurality of first boss are coupled by fasteners and upon assembly the first semi-circular sections and the second semi-circular sections enclose the plurality of first boss and the plurality of second boss.
[0015] Further, in the embodiment, based on the above described subject matter the limitation of torque withstanding capacity of rubber damped gear is overcome based on carving out a special shape (cut-out) from within the gear core and filling the same with rubber. Further, torque/power transmission is taken care by the metal part of the gear assembly and not directly by rubber thereby overcoming the issue of durability. Furthermore, a special shaped rubber is made and it is covered with a gear cover to avoid its direct contact with lubrication oil during operation. The rubber absorbs this impact energy and dissipates it in the form of heat. In the subsequent section, more details and advantages of the present subject matter are explained.
[0016] Now referring to the figures, Figure 1 illustrates a cross section of a camshaft gear mechanism. Referring next figure, Figure 2 illustrates an exploded view of the camshaft gear mechanism. In the subsequent section the present subject matter is explained with jointly reference to figure 1 and figure 2.
[0017] In one embodiment, of the present subject matter, the camshaft gear mechanism comprises a gear 01, a damper element 02, a hub 03, and a cover 04. The gear 01 comprises a special shape is carved out (metal removal), also referred to as the cut-out with 12 equidistance first boss at circular pitch circular dimeter (PCD) to accommodate damper element 02. In other words, to reduce gear rattling noise, a rubber damper 02 is placed inside gear 01 which absorbs and damps the impact energy. In one example, the inner circumference of the damper element 02 comprises a first semi-circular sections, such that the profile of the first semi-circular section can partially enclose the first boss. Further, shape of the damper element enables maximum damping and contact with hub 03, gear 01 and cover 04.
[0018] Further, the gear 01 along with damper element 02 is mounted on the hub 03. Hub 03 has special shape i.e. a flange with second semi-circular sections so that the torque transfer is possible from gear 01 to the camshaft as hub 03 is mounted on camshaft. The profile of the second semi-circular sections is such that it can partially enclose the first boss. Further, the cover 04 with same profile as that of the gear 01, and comprising a plurality of second boss located along the circumference of the cover, is used to hold damper element 02 at its place. Furthermore, the gear 01, damper element 02, hub 03, and cover 04 are held together with 12 fastening screws 05 which are placed equidistant on circular PCD. In other words, the gear 01 and the hub 03 are made as separate parts which are fastened by fastening screws 05 to each other with rubber damper 02 sandwiched between the gear 01 and cover 04. In one example, threading is provided on gear 01.
[0019] Exemplary embodiments discussed above may provide certain advantages. Though not required to practice aspects of the disclosure, these advantages may include the following:
[0020] Some embodiments of the present subject matter disclose a camshaft gear mechanism that damps the noise generated because of teeth impacts during power transmission with gear drive.
[0021] Some embodiments of the present subject matter disclose a camshaft gear mechanism that can be easily dismantled and rubber element can be changed.
[0022] Some embodiments of the present subject matter disclose a camshaft gear mechanism that reduces noise from gears.
[0023] Some embodiments of the present subject matter disclose a camshaft gear mechanism that have improved NVH characteristic of engine.
[0024] Some embodiments of the present subject matter disclose a camshaft gear mechanism comprises damping rubber element that absorbs the impact energy and damps the noise.
[0025] Some embodiments of the present subject matter disclose a camshaft gear mechanism with rubber damper element with high durability and serviceability.
[0026] Some embodiments of the present subject matter disclose a camshaft gear mechanism, with rubber damper element is introduced in the path of energy transfer between gear and gear hub which substantially enhances the damping property.
[0027] Although implementations for a camshaft gear mechanisms have been described in language specific to structural features and/or system, it is to be understood that the appended claims are not necessarily limited to the specific features or described. Rather, the specific features are disclosed as examples of implementations.