FORM2
THE PATENTS ACT, 1970
(39 of 1970)
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10; rule 13)
1. Title of the invention. - FUEL DISPENSING PUMP WITH AIR
SEPARATION
2. Applicant(s)
(a) NAME : LARSEN & TOUBRO LIMITED
(b) NATIONALITY : Indian .
(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:

FIELD OF THE INVENTION
The present invention relates to a fuel-dispensing pump unit. More particularly, the invention is concerned about a fuel-dispensing pump unit having air separation arrangement being uniquely designed and integrated with the pump unit such that effective separation and effective removal of air from the fuel can be achieved.
BACKGROUND AND THE PRIOR ART
Traditionally for the air separation, the separate apparatus had been used to separate the air which was connected to pump by conduits. Air would get separated passively by rising above to the surface and would get released to the atmosphere. Whilst the fuel accumulated at the bottom would return to the pump. But this process of separation is very slow since it took lot of time for air bubbles to travel to the fuel surface and hence ineffective. Also, since the air separator unit is considerably large, it needed the additional space which contradicts to the compactness demanded in the dispensing systems today.
In the document US 5884809, there is no provision of vortex valve and aeration valve as in the present invention. So when the air is not present in the system, fuel still goes in air elimination chamber, flooding it. Eventually over a period of time if air gets introduced in the system, it doesn't find place in air elimination chamber and hence can't be separated. But in present invention, when air is present, then only the vortex valve is open. When air is not present, owing to its high pressure, vortex valve remains closed preventing fuel flooding the air elimination chamber. All these parts in current invention are integral with pumping unit, making it compact.
In the document US 3715863, there is no protection for any air present within the fuel past the vortex tube. When the pump is started for the first time, there is lot of air in fuel; all of it can not be separated by the air separation means available owing to its limitation. Also, occasionally when very large pockets of air get introduced in the fuel stream, all of air can't be separated at vortex tube and this air is carried away with the fuel ultimately causing inaccuracy. In current invention, there is an aeration valve

provided which allows such large amounts of air traces if not separated at the vortex tube. So we have a two stage separation of air.
In the document US 4222751, the orifice for the aerated fuel to be separated from the vortex tube is kept small and there is no separate mechanism to prevent the fuel free of air to flow into the vent chamber. So if there is too much of air, then only a part of it can get separated. While if there is very less amount of air, then most of the fuel in the central portion will be passed to vent chamber which causes loss in flow rate of fuel pumped out. But in current invention, the shape of vortex tube is having a nozzle like tapered structure that increases the amount of aerated fuel to be passed on to the vent chamber. But at the same time when the amount of air is less, then owing to higher pressure at the central aerated core, the vortex valve will be closed preventing the flow from happening to the vent chamber.
In the document US 2351331, the air separation element supplied is rather large at the downstream of the pump and hence it requires more space. But in the current invention, a small air separator cover can easily fit on the centrifugal chamber which is integral with the pump giving compactness to the design.
To overcome the problems in the prior art, the present invention proposed a fuel dispensing pump having a uniquely designed and integrated air separation arrangement, which provides an effective removal of air from fuel before it gets measured thereby avoiding inaccurate measurements volumes of fuel dispensed.
OBJECTS OF THE INVENTION
One of the basics objects of the present invention is to overcome the disadvantages/problems of the prior art.
Another objective of the invention is to have a housing in such a manner that air separation passage is integrated with the housing itself to avoid the need of additional gaskets and hardware sets required to make assembly compact.

Another object of the present invention is to provide effective centrifugal separation that would separate higher percentages of air from fuel.
Another object of the present invention is to provide effective way to pass air into air elimination chamber.
SUMMARY OF THE INVENTION
According to one aspect of the present invention there is provided a fuel-dispensing pump unit having air separation arrangement in a fuel dispensing system so as to effectively separate and remove air from fuel, said unit comprising:
Housing;
a positive displacement pump being located inside the said housing, said positive displacement pump pumping fuel from a reservoir to a centrifugal chamber;
an air separator cover means intermediately located between said pump and said centrifugal chamber wherein said cover means being profiled to have gradually changing radii on its periphery so as to release the fuel from the pump to the centrifugal chamber in a substantially tangential direction at the top of the centrifugal chamber;
wherein said housing comprising air separation passage such that the passage being the integral part of the housing allows flow of fuel whereby said fuel is made to traverse in helical fashion thereby separating the fuel into an aerated fuel being collected in a tube means and a dense fuel being collected in an outlet manifold means; wherein said air separation passage comprises of a vortex tube with tapered orifice to facilitate easy flow of aerated fuel into vent chamber
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1: illustrates a fuel dispensing system Figure 2: illustrates a Pumping unit Figure 3: illustrates a centrifugal chamber

Figure 4: illustrates a Vortex tube
Figure 5: illustrates an Aeration Valve
Figure 6: illustrates an outlet manifold
Figure 7: illustrates the passage of the fuel from vortex tube up to outlet manifold.
Figure 8: illustrates the schematic diagram of the whole pumping unit
DETAILED DESCRIPTION OF THE INVENTION
A fuel dispensing system is indicating different parts of the system namely a motor (1), a pumping unit (2), a metering unit (3) and a nozzle (4) as shown in fig. (1).
As shown in Fig. (2), the pumping unit (2) is a fuel-dispensing pump unit having air separation arrangement. The pumping unit comprises a positive displacement pump to draw the fuel from an underground tank. The embodiment of the present invention uses a vane pump (5) for the same. However, the present invention can also be performed by using internal gear pump for drawing fuel from the underground tank. The vane pump (5) generates the vacuum at its inlet so that the fuel is drawn from the underground tank. The Fuel containing traces of air is pumped by vane pump towards the centrifugal chamber (6). The area of the channel joining the pump casing and centrifugal chamber (6) is gradually decreasing and at the inlet of centrifugal chamber (6), there is an air separator cover (7). The shape given to the air separator cover(7) decreases gradually and at one point it has least cross section area and eventually as fuel flows through it, its velocity keeps increasing and is maximum at this least cross section. Now centrifugal separation of air is directly related to this velocity with which the fuel enters the centrifugal chamber (6). If this least cross section area is more than as shown in current invention, fuel velocity will decrease and air separation won't be effective. While, if it is lesser than it is shown, then the fuel velocity will increase but pumping unit won't be able to dispense the flow rates required by customer. So the shape has to be such that we can attain maximum fuel velocity and still will be able to generate the required flow rate. So, the air separator cover (7) has a profile with gradually changing radii on its periphery which releases the fuel stream tangentially at the top of centrifugal chamber (6). At this point, fuel has a highest velocity.

As shown in the fig. (3), a helical flow is created in the centrifugal chamber (6) after the fuel enters into it tangentially. The helical flow results into the formation of vortex of aerated fuel.
Pumping unit housing (11) is designed in such a manner that air separation passage including the centrifugal chamber (6) though which the fluid is made to traverse in helical fashion is integral to housing itself This unique design avoids the need of additional pair of gaskets and pairs of hardware sets required. As the numbers of parts are reduced, the assembly has become compact. Further, integral air separation passage makes it easily accessible for any servicing requirements if needed. In turn it helps in reduced downtime of dispensing unit.
Consider a small fuel element in the fuel with mass (m) and density (p) with the tangential velocity (v). If the pressure force and the centrifugal force experienced by the fuel element are equated, neglecting the gravitational force, the following equation can easily be arrived at:
 p= p v2
 r r
Where, dpidr is the pressure gradient in the radial direction.
Thus, it's evident that since the pressure gradient is positive, the pressure increases as radius increases in the radically outward direction because of centrifugal force experienced by the element.
As a result, the aerated fuel tends to diffuse into the central region while dense fuel without any air remains at the periphery. This aerated fuel is collected by a tube means which is a vortex tube (8) and is delivered to vent chamber (9). Here, the air escapes the fuel and is accumulated on the top of fuel. Whereas the dense fuel is collected by an outlet manifold (10) as shown in fig. (6). the outlet manifold (10) comprising an aeration valve (10a) and a spring loaded outlet valve (10b) with dampener (10d)
As shown in fig. (4), aerated fuel is collected by the vortex tube (8) and the vortex tube is operatively connected to a plunger arrangement which has a plunger (8a) seated at

its position with the help of a spring wherein said plunger arrangement being movable in a single degree of freedom so as to block or provide flow path of the fuel to a vent chamber (9) through an opening in the vortex tube (8) and the plunger arrangement; Since aerated fuel is not having much density and pressure, it can't apply enough pressure at the area of plunger (8a) ahead of it and tries to pass through the opening provided in the plunger and finally escapes through vortex tube assembly. But the fuel without air pushes the plunger (8a) against the spring and ultimately blocks the exit path preventing it from passing to the vent chamber (9). The aerated fuel is separated as well as the fuel without air is prevented from entering into the vent chamber (9).
Also, because of the tapered shape of orifice (8b) in the vortex tube, the aerated fuel at the central portion in the centrifugal chamber (6) is offered lesser resistance to flow and is extracted effectively into vent chamber (9). The effectiveness in terms of accuracy was found to be increasing by 10% with the vortex tube with tapered orifice (8b) as compared to vortex tube (8) with normal orifice. With the tapered shape, air in the fuel gets separated more effectively than the earlier design. Ultimately, the error in measurement is decreased by 10 % when vortex tube with tapered shape is used. The benefit of cost effectiveness in manufacturing vortex tube (8) with taper section can be claimed by selecting its material as engineering plastic.
The passage of the fuel from vortex tube up to outlet manifold is as shown in Fig. (7). When the pump starts for the first time in case of new installations or in the event of storage tank becoming empty, the fuel sucked will be very much aerated. Being in abundance, air may remain at the periphery and may escape the vortex tube (8). Hence, as shown in fig (6), leftover aerated fuel in the dense fuel passes onto outlet manifold where the outlet valve (10b) is seated on its seat under the action of a spring. But since the fuel is not pressurized, it can't unseat the outlet valve. (10b). At the top receiving end of the outlet manifold (10), there is aeration valve (10a) which provides a passage to this fuel to the vent chamber (9).
As shown in fig. (5), aeration valve (10a) is having a plunger seated against its seat under the action of spring. The Leftover aerated fuel in the dense fuel passes out to the vent chamber (9) through the clearance between the plunger and valve cavity (10c). But

when pressurized and dense fuel enters the aeration valve (10a), it pushes the plunger and blocks the passage at the top cutting the flow to the vent chamber (9), preventing it from over flowing and the outlet valve (10b) is unseated allowing fuel to flow to the metering unit (3). The fuel then unseats the outlet valvs (10b) and is passed to the fuel meter (3). As shown in fig. (6), because of dampener (I0d) at outlet valve (10b), the opening and closing of the valve under the action of spring is not very abrupt and hence it doesn't generate excessive pressure pulsations. The schematic diagram of the whole pumping unit (2) is as shown in fig. (8).
The structure thus conceived is adaptable to numerous modifications or variations, tn practice the materials and dimensions may be dependant upon specific requirements and that will be comprised within its true spirit.

WE CLAIM
1. A fuel-dispensing pump unit having air separation arrangement in a fuel
dispensing system so as to effectively separate and remove air from fuel, said
unit comprising:
housing;
a positive displacement pump being located inside the said housing, said
positive displacement pump pumping fuel from a reservoir to a centrifugal
chamber;
an air separator cover means intermediately located between said pump and
said centrifugal chamber
wherein said housing comprising air separation passage such that the passage
being the integral part of the housing allows flow of fuel whereby said fuel is
made to traverse in helical fashion thereby separating the fuel into an aerated
fuel being collected in a tube means and a dense fuel being collected in an outlet
manifold means.
2. An air separator cover comprising unique profile having gradually changing radii on its periphery so as to release fluid in a substantially tangential direction ensuring required flow rate form the pumping unit.
3. The fuel dispensing pump unit as claimed in claim 1, wherein said tube means comprises a substantially tapered orifice for effective removal of the aerated fuel from the tube means.
4. The fuel dispensing pump unit as claimed in claim 1, wherein said positive displacement pump is a vane pump or optionally a gear pump.
5. The fuel dispensing pump unit as herein substantially described and illustrated with the accompanying drawings.