FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE 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
Mr.Rajapure D.M, Mr. Devikar Umesh and Mr. Murthy Venkatesh
All 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 particularly describes the invention and manner in which it is
to be performed.

FIELD OF INVENTION
The present invention relates to a sub frame structure for vehicles and more particularly to 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 CO2, CO, NOx. There is a limit in meeting these requirements with the combustion of fossil liquid fuel in conventional engines. In recent years there is an increased demand for use of gaseous fuel as a fuel source in both compression and spark ignition engines. The 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. The 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.
The CNG tanks must be secured to vehicles in such 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 the conventional arrangement cluster arrangement of cylinders cannot be made. It is very difficult to mount the cylinders independently on the mounting structure. Moreover there is a need to increase the ground clearance of the mounting structure and to reduce the

cost of manufacturing of the cylinder mounting structure for vehicles. 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.
OBJECT 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 mount the CNG cylinders independently.
Yet another object of the present invention is to increase the ground clearance of the cylinder mounting structure.
Yet another object of the present invention is to provide a CNG cylinder mounting structure which can be easily fitted and removed.
Yet another object of the present invention is to reduce the cost of manufacturing of the CNG cylinder mounting structure.
Yet another objective of the present invention is to provide good accessibility for regular operation and maintenance work.
SUMMARY OF THE INVENTION
The present invention provides a sub-frame structure for securing fuel-carrying cylinders in vehicles. The sub-frame structure is provided to hold said fuel-carrying cylinders in a cluster on the outer sides of said vehicular frame structure, said sub frame structure
4
comprising: plurality of longitudinal members mounted on a chassis frame; plurality of transverse beams with reinforcements connected to said longitudinal members, a plurality of vertical members with an upper cylinder resting and holding means and a lower cylinder resting and holding means, and a first end restraining structure with stopper means mounted at one end of said cylinder cluster; and a second end restraining structure with stopper means mounted at the other end of the said cylinder cluster.

In a preferred embodiment said upper cylinder resting and holding means comprises an plurality of U-bolts pointing upwards. A rubber package is provided on inner portion of said U-bolt by using synthetic bonding technique and a similar rubber package is provided below said transverse beam; said plurality of vertical members being positioned parallel to and at a distance away from each other such that a space is formed in between said plurality of vertical members and said upper cylinders are mounted in said upper projecting U-bolts.
In a preferred embodiment said lower cylinder resting and holding means comprises a plurality of U-bolts pointing downwards. A rubber package is provided on inner portion of said U-bolt by using synthetic bonding technique and a similar rubber package is provided above said lower plate; said vertical members being positioned parallel to and at a distance away from each other such that a space is formed in between said vertical members and said lower cylinders are mounted in said spaces formed between said plurality of downwardly projecting U-bolt.
In a preferred embodiment the said upwardly projecting U-bolts are connected to said transverse beam and said downward projecting U-bolts are connected to said lower plate. In a further preferred embodiment, the cylinders are tightened by means of straps.
In a further embodiment the first end restraining structure comprises a pluarlity of end stopper plates. Said stopper plates are fixed at an angle to mate with curvature surface of end portion of said cylinders. The first end restraining structure is formed as space-grid structural frame and is connected to a transverse support member mounted on said longitudinal member.
In a preferred embodiment, the second end restraining structure comprises tighteners for each of the said cylinders. Said tighteners located on said second restraining structure are adjustable and has a stopper connected to a threaded fastener to enable independent tightening of each of said cylinder. The second end restraining structure is also formed as space-grid structural frame and is connected to one of said transverse beam.

BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows an isometric view of the sub-frame structure according to pres /ention.
FIG. 2 shows a side view of the supporting structure of FIG. 1
FIG. 3 shows a front view of the supporting structure of FIG. 1
FIG. 4 shows a rear view of the supporting structure of FIG. 1
FIG. 5 shows an exploded isometric view of the sub-frame structure of FIG. 1
FIG. 6 shows a perspective view of the arrangement of the U-bolts in between vertical
members, according to present invention.
DETAILED DESCRIPTION OF THE INVENTION
This application is addition to our earlier application 652/Mum/2008 filed on 26/03/2008. According to the present invention a sub-frame structure is provided to hold fuel-carrying cylinders in a cluster on the outer sides of said vehicular frame structure. The sub-frame consists of a plurality of longitudinal members 3 and a plurality of transverse members 5 connected to the longitudinal members 3 for supporting said cylinders 15; cylinder holding structures are connected to said longitudinal members 3 and end restraining structures 10 and 11 are provided to hold the cylinders 15 in position.
Referring to FIG. 1, a sub-frame structure 1 seated on chassis frame 2 of the vehicle. The sub-frame structure also acts as a sub-frame to the load body. The sub-frame structure consists of at least two longitudinal beam members 3 mounted on the chassis frame 2 by means of 'U' bolts 6. At least two transverse beams 4 with reinforcement for supporting cylinder 15 mounting structures are connected, preferably welded, to said longitudinal members 3.
Referring to FIG. 2 to 5, a cylinder holding structure, consists of a plurality of U-bolts 6 projecting upwards and a plurality of U-bolts 6 projecting downwards. A rubber package 9 is provided on inner portion of said U-boIt 6 by using synthetic bonding technique and a rubber package 14 is provided below said transverse beam 4 and above lower plate 7. The U-bolts 6 are provided to rest said CNG cylinders. Further, pluralities of vertical members 8 are positioned in parallel and at a distance away from each other such that a space is formed in between said vertical members 8. The upward projecting U-bolts 6 are connected to the transverse beam 4 and the lower projecting U-bolt 6 is connected to the

lower plate 7. The upper cylinders are rested in the space between the upper projecting U-bolt 6 and rubber package 14. The lower cylinders are rested in the space between lower projecting U-bolts 6 and rubber package 14.
FIG. 3, 4 and 5 show the first retaining structure 10 and a second end restraining structure 11 mounted at both ends of the cylinders 15. In figure 4, the first restrain structure 10 includes an end stoppers for stopping the cylinders. The outlet end of the upper and lower cylinders is located at the first end restrain structure 10. Two stopping plates 12 and 12' are located on the restraining structure 10 to stop the longitudinal movement of the each cylinder 15. The stopper plates are fixed at an angle to mate with curvature surface of the end portion of the cylinder 15. The first restrain structure 10 is formed as space-grid structural frame and attached to a transverse support member 5 mounted on the longitudinal member 3. In FIG. 3, the second restraining structure 11 is shown to have adjustable tighteners 13 for ensuring independent tightening of the each cylinder. The adjustable tightener has 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. The number of space-grids in the second restraining structure is reduced compared to the conventional space grid structure.
FIG. 5 is an exploded view of the sub-frame structure. FIG. 6 shows a perspective view of the arrangement of the U-bolts in between vertical members, according to present invention. It shows a plurality of U-bolts 6 projecting upwards and a plurality of U-bolts 6 projecting downwards. The rubber package 9 is provided on inner portion of said U-bolt 6 by using synthetic bonding technique and the rubber package 14 is provided below said transverse beam 4 and above lower plate 7. The U-bolts 6 are provided to rest the upper and lower CNG cylinders.
The foregoing description is a specific embodiment of the present invention, it should be appreciated that this embodiment is described for purpose of illustration only, and that numerous alterations and modifications may be practiced by those skilled in the art without departing from the spirit and scope of the invention. it is intended that all such modifications and alterations be included insofar as they come within the scope of the invention as claimed or the equivalents thereof.

ADVANTAGE:
• The present invention provides a lightweight, stackable mounting structure where CNG cylinders can be mounted and tightened independently.
• The sub frame structure according to present invention increases the ground clearance of the cylinder mounting structure.
• It reduces the cost of manufacturing of the CNG cylinder mounting structure.
• To provide good accessibility for regular operation and maintenance work.

We Claim;
1. A sub-frame structure for securing fuel-carrying cylinders in vehicles said sub-frame
structure provided to hold said fuel-carrying cylinders in a cluster on the outer sides of
said vehicular chassis frame structure, said sub frame structure comprising:
plurality of longitudinal members mounted on a chassis frame;
plurality of transverse beams with reinforcements connected to said longitudinal members and a lower plate ;
plurality of vertical members connected between said transverse beams and lower plate;
resting and holding means connected to said transverse beam and said base plate to support upper and lower cylinder members;
a first and second restraining structures mounted to said transverse beams;
said first restraining structure with stopper means located at one end of said cylinders;
said second restraining structure with an adjustable stopper means located at the other end of the said cylinders.
2. The sub-frame structure as claimed in claim 1, wherein said resting and holding means having a plurality of U-bolts projecting upward and downwards, said plurality of vertical members being positioned parallel to and at a distance away from each other such that a space is formed in between said plurality of vertical members and said cylinders are mounted on said U-bolts projecting upwards and downwards.
3. The sub-frame structure as claimed in claim 1, wherein said plurality of U-bolts projecting upwards is connected to said transverse beams to support the upper cylinders in a cluster and said plurality of U-bolts projecting downwards is connected to lower plate to support lower cylinders in a cluster.
4. The sub-frame structure as claimed in claim 1, wherein said plurality of U-bolts includes a rubber package on its inner surface to hold the cylinder in place.
5. The sub-frame structure as claimed in claim 1, wherein a rubber package is provided below said transverse beam and above said lower plate to accommodate said upper and lower cylinder members.

6. The sub-frame structure as claimed in claim 1, wherein said first restraining structure is formed as space-grid structural frame and is connected to said transverse support member mounted on said longitudinal member.
7. The sub-frame structure as claimed in claim 1, wherein said first restraining structure, configured to restrain the outlet end of said cylinders from longitudinal movement comprises a plurality of end stopper plates fixed at an angle to mate with curvature surface of said outlet end of said cylinders.
8. The sub-frame structure as claimed in claim 1, wherein said second restraining structure is formed as space-grid structural frame having tighteners for each cylinders and is connected to one of said transverse beam.

9. The sub-frame structure as claimed in claim 8 wherein said adjustable tighteners have stoppers connected to a threaded fastener to enable independent tightening of each of said cylinder.
10. A sub-frame structure for securing fuel-carrying cylinders in vehicles as claimed and largely as described in the specification and as illustrated in the accompanying figures.