FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
PROVISIONAL SPECIFICATION
(See Section 10; rule 13)
TITLE OF THE INVENTION
A Sub-Frame Structure For CNG Vehicles
APPLICANTS
TATA MOTORS LIMITED, an Indian company
having its registered office at Bombay House,
24 Homi Mody Street, Hutatma Chowk,
Mumbai 400 001 Maharashtra, India
INVENTORS
Pandharinath Namdeo Khatmode & K. Thangaraj
An Indian Nationals
of TATA MOTORS LIMITED,
an Indian company having its registered office
at Bombay House, 24 Homi Mody Street, Hutatma Chowk,
Mumbai 400 001 Maharashtra, India
PREAMBLE TO THE DESCRIPTION
The following specification describes the invention.

FIELD OF INVENTION
This invention relates to sub frame structure for a vehicle and more particularly a sub frame structure for CNG vehicles to hold the CNG cylinders.
BACKGROUND OF INVENTION
Recently, importance has been placed on the cleanliness of exhaust gas and reduction in the discharge of CO 2, co , NOX There is a limit in meeting these requirements with the combustion of fossil liquid fuel in conventional engines. So recent years have seen an increased demand for use of gaseous fuel as a fuel source in both compression and spark ignition engines. Gaseous fuels combustion engines that burn natural gas produces less emission from tail pipe.
Natural gas, as delivered through pipelines, cannot be used directly as a mobile vehicular fluid and must be first physically compressed, liquefied or adsorbed. Compressed natural gas (CNG) for use in CNG-fueled vehicles is compressed between 3,000 and 3600 psi (20.77-24.92 MPa) and stored in cylinders-usually ferrous, aluminum or non-ferrous liners wrapped in a fiber-reinforced tensile composite.
CNG tanks must be secured to vehicles in such as a way as to prevent damage from road hazards, slippage, loosening or rotation, using a method capable of withstanding a static force, in the six principle directions (up, down, left, right, forwards, backwards), of 20 times the weight of a fully pressurized container. For moving vehicles this equates to impose relative acceleration or deceleration on the tank of 20 times gravity (20g).
When a vehicle accelerates or decelerates, the inertia of an attached tank resists the change in velocity, restrained to follow the vehicle's change in velocity only by its mounting means. A rear-ending situation or head-on collision can impose


significant forces on the mounting means. If they are not capable of restraining the tank, it could conceivably be sheared from the vehicle and become a projectile. In conventional vehicles cylinders are mounted directly to the structure by means of 'U' bolts. The 'U' bolt holds the cylinder in position by friction due to the line contact between them. In the conventional arrangement cylinders cluster arrangement cannot be made.
For commercial trucks, structural weight and cylinder mounting arrangement plays prime role in operating economics of vehicle as it is directly linked with pay load in vehicle.
SUMMARY OF THE INVENTION
The objective of the present invention is to provide a lightweight mounting structure for CNG cylinders.
Another objective of the present invention is to mounting each cylinders independently.
Yet another objective of the present invention is to provide good accessibility for regular operation and maintenance work.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 shows the isometric view of the sub-frame structure
Figure 2 shows the side view of the supporting structure
Figure 3 shows the front view of the supporting structure
Figure 4 shows the rear view of the supporting structure
Figure 5 shows the exploded isometric view of the sub-frame structure.


DETAILED DESCRIPTION OF THE INVENTION
Sub-frame consist of two longitudinal members, transverse members are connected to the longitudinal members for supporting cylinders, cylinder holding structures connected to longitudinal members and end restrains to hold the cylinders in position.
Referring to figure 1, a sub-frame structure (1) seated on chassis frame (2) of the vehicle. The sub-frame structure also acting a sub-frame to the load body. The sub-frame structure consists of two longitudinal members mounted on the chassis frame by means of 'U' bolts. Two transverse beam with reinforcement for supporting cylinder (15) mounting structures welded to longitudinal member.
A cylinder holding structure, consist of an upper (6) and lower plate (7). Cylinders are resting on the plates and tightened using straps (14). Further vertical members are welded on upper plates and projecting upward (8) and downward (9). The upward projecting vertical members (8) are connected to the transverse beam (4) and the lower plate (7) is connected to the downward projecting vertical members (9). Cylinders are located in space between the vertical members. The top cylinders are resting on the upper plate (6) and tightened using a strap (14). Whereas bottom cylinders are tightened to lower plate (7) and the plate is connected to the bottom vertical member (9) of the upper plate (6).
End restraining structuring (10, 11) mounted both end of the cylinders. First end restrain structure (10) having end stoppers for stopping cylinders. The outlet end of the cylinders located at the first restrain structure (10). Three stopping plate (12, 12', 12") are located on the restraining structure to stop longitudinal movement of the each cylinder. These stoppers plates are fixed in an angle to mate with curvature surface of the end portion (outlet) of the cylinder. The first end restrain structure (10) is formed as space-grid structural frame and attached to a transverse support member (5) mounted on the longitudinal member (3). Second end restraining


structure (11) having adjustable tighteners (13) for ensuring independent tightening of the each cylinder. The adjustable tighterner is having a stopper connected to a threaded bolt. The stopper is in contact with the end portion of the cylinder and whenever required the stopper can be tightened by rotating the bolt. The structure is formed as space-grid structural frame and attached to the transverse beam (4).