F0RM2
THE PATENTS ACT, 1970
(39 of 1970)
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10; rule 13)
1.Title of the invention: INTERLOCK SYSTEM FOR PANEL DOORS


2. Applicant(s)
(a) NAME : Larsen & Toubro Limited
(b) NATIONALITY : An Indian Company.
(c) ADDRESS : L & T House, Ballard Estate, Mumbai 400 001,
State of Maharashtra, India

3. PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed:


TECHNICAL FIELD OF THE INVENTION
The present invention relates to an interlock system for panel doors. In particular the invention is concerned about an interlocking system for panel doors in fuel dispensers which would provide an authorized access to the dispenser system and thereby provide security of dispenser in a cost effective manner.
BACKGROUND AND THE PRIOR ART
Present day fuel dispensers have panel doors made either from sheet metal or moulded Polymer for enclosing the components in the Hydraulic zone and the Electronic Zone. Each one has a lock mounted on itself and can be opened to get an access of the corresponding zone and the components within. This lock is a mechanical one. There is no provision to record the number of time the dispenser components have been accessed for use. A person intending to do fraud or manipulation can easily access the components without getting noticed, i.e. there is no log maintained to find out, who has accessed the door and when.
US 4384428 discloses a security gate or closure for securing an access opening or fire escape against unauthorized entry defined by a frame circumscribing the opening to be secured; a closure therefore; and a locking bar for securing the closure without a key lock which will prohibit and/or deter unauthorized entry and which can be quickly opened to provide for rapid exit in case of fire or other emergency situations.

US 7093999 discloses an interlocking system utilizing upper and lower grooves along the edges of the base of an item to interlock with upper and lower grooves on other items. One item described is a dispenser using a spongy material to force a tape with labels upwardly to be withdrawn. Another item with upper and lower grooves is a storage box.
None of the prior art as described hereinabove provides with a knowledge of interlocking system which could provide a restricted access to authorized users thereby providing security of the components of the system in a cost effective manner.
Therefore, the need exists for a interlocking system for panel doors in fuel dispensers which would provide an authorized access to the dispenser system and thereby provide security of dispenser.
The present inventors have found that an interlocking system having a uniguely designed locking assembly comprising rod and spring arrangement can be provided for fuel dispensers which would provide access of dispenser components in a restricted manner to authorized users.
OBJECTS OF THE INVENTION
Accordingly, one object of the present invention is to overcome the drawbacks of the existing interlocking system used for panels as described in the prior art.

Another object of the present invention is to provide an interlocking system for dispensers which would provide authorized access to the dispensers.
Yet another object of the present invention is to provide a data log for keeping on record details of the personnel opening the dispenser.
Another object of the present invention is to provide a cost effective interlocking system.
SUMMARY OF THE INVENTION
According to one aspect of the present invention there is
provided an interlocking system for panel doors in fuel
dispensers, said system comprising :
plurality of panel door means forming a housing,
wherein one of said door means comprises main lock means so
as to facilitate authorized access to the other panel door
means;
plurality of interlocking means being operatively located on the panel door means such that said interlocking means cannot be opened when said door means provided with the main lock means remains closed;
wherein said interlocking means comprises linkage arrangement comprising plurality of pin means such that said pin means is in operative engagement with a bracket means located at a predetermined position on the panel door means thereby providing locking of the system.

The other objects and advantages of the present invention will be apparent from the description provided hereinbelow with reference to the accompanying figures and detailed description provided hereinbelow.
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to an interlocking system for fuel dispensers. In the present embodiment the interlocking system has been illustrated in respect of fuel dispensers. However, such interlocking system is not restricted to fuel dispensers but can be used for other switching devices, control panel applications, contactors and the like.
The system of the present invention comprises plurality of panels or door means so as to form a housing and enclosing the components of the dispensers. The access to these components is achieved by opening the panels. One of the door means comprises main lock means facilitating authorized access to the other panels. The panel consisting the main lock is termed as 'master door' which has the robust lock which can be either mechanical, electronic or biometric. The robust lock has a data logging and access control facility that ensures that the authorized person gets the access for the panels and in case of such an event the log for the same is created.
Plurality of interlocking means are operatively located on the panel means such that said interlocking means cannot be opened when said door means provided with the main lock means remains closed. The interlocking means comprises

linkage arrangement comprising plurality of links, spring, lock bracket, lock pin and a lock plate. The lock pins are such that they are in operative engagement with the lock bracket located at a predetermined position on the panel means thereby providing locking of the system.
Further description of the construction components of the system of the present invention is described hereinbelow with reference to the figures.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1 illustrates an isometric view of the interlocking system of the present invention for securing fuel dispensers.
Figures 2 to 5 illustrate arrangement of the interlocking system for locking lower panels of the dispensers.
DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Fig 1 gives the general arrangement of the Interlocking arrangement for securing the fuel dispensers. A typical fuel dispensers has a hydraulic zone comprising of a suction pump (in case of centralized system this is absent), metering unit, solenoid valve, and interlinking castings. Access to these components is achieved by opening these panels (5) and (6). The electronic zone consists of electronic cards i.e the PCA's connected by the cables. The access to these components is achieved by opening panels (4) and (3). Component (1), (2), (3) and (4) together

constitute a housing for electronic components. Panels interlocking system comprise of panel (4) which is a master door. The master door can be either of the four panel doors (3), (4), (5), or (6). The interlocking of doors is such that once the master door is opened, only then can the other panel doors be opened. In the invention the master door is panel (4). Panel (3) can be opened by releasing the lock through linkage arrangement. The panel door (3) is locked under spring force by lock element (13) getting pulled against the bracket (14). The linkage arrangement for door (3) comprise of a link support bracket (12), link (10) running throughout the depth of the electronic box, the lock element 13 and a spring (11). The panel door can be opened by rotating the link (10) by 90 degrees. This enables the Pin (17) to come in line with the slot of the bracket (12) causing link to displace under spring force disengaging the lock element from its position. Once disengaged the door can now be opened.
Figures 2 to 5 show a general arrangement for locking the Lower Panels used for enclosing the hydraulic components. This linkage consists of a Link (7), Spring (8), Lock bracket (19), Lock pin (18) and a Lock plate (15). The principle of working is similar to the one above used for locking the Top box door. Once the Master door (4) is opened the access to the linkage system can be sought for opening Lower Panels. To open the Lower panel (5) and (6) the link (7) is pulled upwards against the Spring (8). One of the Pin (18) on the Top of the link (7) rests against the face of Lock Bracket (19). This causes the link (7) to come out of the hole in Lock Plate (15) thus releasing the Lower Panel (5). Similar process is undertaken to open

Lower Panel (6) . If one has to lock back the lower panel, the Link (7) is rotated by 90 degrees so that the Top Pin 18 aligns with the slot in the Lock bracket (19) . The Spring force pushes the link (7) back into the hole of Lock Plate (15) locking the Lower panels.
Working principle :
Fuel Dispensers consists of sheet metal/moulded doors for enclosing the hydraulic and the electrical and electronic components. The hydraulic components include the castings, the valves the pump, and the meter. The electronic components include the PCA's (Electronics cards). The Smart Locking System essentially has an interlocking system for panels. It comprises of a Master Door. This can either be one of the doors in the hydraulic zone or in the electronic zone depending upon the requirements. The master door can be further opened by the authorised person by one of the following three methods:
The authorized entry is possible by use of one of the following methods:
a. Level 1 : A Robust mechanical Lock that can only
be opened by a specific key, unlike a universal
key used currently used that can open any door of
a Sprint Dispensers.
b. Level 2 : An Electronic Lock fitted onto a master
door to provide authorized entry. Suitable logs
about the entry details could be maintained.

c. Level 3 : An Electronic Lock with Biometric Interface.
Once the Master Door is opened by one of the above three methods, the other doors can then be accessed for opening. The Linkage system consisting of a rod and spring arrangement spanning the depth of the electronic box can be accessed and turned in a predetermined way to open the other door of the electronic box. The Doors for the hydraulic zone can be opened by a similar arrangement that runs from the electronic box to the hydraulic zone.
The structure thus conceived is adaptable to numerous modifications or variations. In practice the materials and dimensions may be dependant upon specific requirements and that will be comprised within its true spirit.

WE CLAIM
1. An interlocking system for panel doors in fuel
dispensers, said system comprising :
plurality of panel door means forming a housing,
wherein one of said door means comprises main lock
means so as to facilitate authorized access to the
other panel door means;
plurality of interlocking means being operatively
located on the panel door means such that said
interlocking means cannot be opened when said door
means provided with the main lock means remains
closed;
wherein said interlocking means comprises linkage
arrangement comprising plurality of pin means such
that said pin means is in operative engagement with a
bracket means located at a predetermined position on
the panel door means thereby providing locking of the
system.
2. System as claimed in claim 1 wherein said linkage arrangement comprises link means adapted to be rotated by about 90° so as to facilitate locking and/or unlocking of the panels.
3. System as claimed in claims 1 and 2 further comprises of locking element being operatively engaged with bracket means so as to ensure locking of the panels.
4. System as claimed in claim 2 wherein said link means comprises spring adapted to engage and disengage the pin means with / from the bracket.

System as claimed in claim 1 wherein said main lock means comprises a robust lock being selectively mechanical, electronic or biometric.
System as claimed in claim 5 wherein said robust lock of electronic type comprises data logging and access control facility so as to ensure that authorized person gets access for panels.
System as claimed in any of the preceding claims further comprises of lock plate having a predetermined hole so to accommodate the link means for locking.
An interlocking system for panel doors in fuel dispensers as herein substantially described and illustrated with reference to the accompanying figures.
Dated this 27 th day of November 2008

Abhishek Sen Of S. Majumdar & Co. Applicant's Agent