FIELD OF THE INVENTION
The present invention relates to the oil dispensing machines, particularly oil dispensing machines with dispensing gun actuated under air pressure., more particularly, the dispensing machines with a maintenance-free concentric air and hydraulic oil hose and having an air-pressure actuated dispensing gun.
BACKGROUND OF THE INVENTION
Normally, in oil dispensing machines, oil is filled in the tank through a hosepipe. A pneumatic valve is attached to the dispensing point near the oil dispensing gun, which is operated at the time of filling oil, e.g. diesel. This oil-dispensing gun is operated by air to open the nozzle for oil delivery to the transmission tank.
DISADVANTAGES WITH THE PRIOR ART
The problem with the conventional oil-dispensing system is that in the oil dispensing machine, oil is filled in the transmission tank through an oil-hose. A valve is attached to the dispensing point near the oil-dispensing gun, which is operated by air at the time of filling oil.
The air hose-pipe used for operating the pneumatic valve is routed from outside the oil-hose and running parallel to the oil-hose. However, in this oil dispensing process, the air hose-pipe easily gets externally damaged due to abrasion from floor etc., thereby necessitating frequent replacements thereof. Similarly, the control cable used for controlling the oil-delivery is also frequently damaged for the same reason. Therefore, there is an existing need to prevent damage to this air hose-pipe for effective oil-dispensing operation of the oil-dispensing guns. There is also a need for a compact oil-dispensing arrangement, free from damages even while being used in a harsh environment as in the existing oil dispensing pumps, e.g. petrol/diesel pumps.

An analysis of the problems existing with the conventional oil dispensing machine was carried out, which involved the following stages:
a) Oil dispenser was found not working
b) Pilot valve not operating
c) Pipe line leak
d) Control cable damaged
e) Abrasion from floor
f) External routing of pilot pipe carrying air.
After completing the above stages, it was proposed to externally attach a spring conduit around the pilot pipe carrying air, which was rubbing against the floor. However even after providing this spring conduit over the pilot pipe, there was significant damage caused to due to external routing of the pilot pipe. Then, it was conceived to configure an internal routing of the pilot pipe inside the oil hose itself, thereby eliminating any external routing and thereby of external damages to air pipe.
Accordingly, in the pneumatically operated oil dispensing machine, this new connector includes internal routing of pneumatic air-inlet and air-exit pipes, i.e. inside the same hydraulic hose through which oil is flowing coaxially.
This avoids the use of currently available spring conduit provided with such pneumatically operated oil dispensing machine and obviates any damage to the pneumatic hose supplying air by potential abrasion from external elements in such harsh working environments. Although, this type of coaxial arrangement are found in heat exchangers, they are used for heat exchange between the two liquid passing through two conduits in single pack carrying two physically different fluid circuits.
It was further proposed to use radio-frequency (RF) based module for omitting the control cable, which was also prone to serious damage due to harsh working environment at the oil-dispensing stations.

OBJECTS OF THE INVENTION
Some of the objects of the present invention - satisfied by at least one embodiment of the present invention - are as follows:
An object of the present invention is to provide a cost-effective device for supplying air for pneumatically operated oil dispensing machines.
Another object of the present invention is to provide a simple device for supplying air for pneumatically operated oil dispensing machines.
A further object of the present invention is to provide a maintenance-free device for supplying air for pneumatically operated oil dispensing machines.
Yet another object of the present invention is to provide a sturdy and compact device for pneumatically operated oil dispensing machines used in harsh external environments, such as in petrol/diesel pumps.
These and other objects and advantages of the present invention will become more apparent from the following description when read with the accompanying figures of drawing, which are, however, not intended to limit the scope of the present invention in any way.
SUMMARY OF THE INVENTION
In accordance with the present invention, there is provided a liquid dispensing system with a concentric pipe-in-pipe arrangement of air and liquid conduits for dispensing liquids, the arrangement comprising:
- a pneumatic circuit, which consists of at least a pair of air-supply and air-return pipe connected to the respective pair of air-supply line and air-return line by means of a T connector,
- a hydraulic circuit consists of at least one first liquid-supply hose connected at first flat end of the first T connector connecting the first

liquid-supply hose to the liquid reservoir disposed at one end of the hydraulic circuit and at least one second liquid-supply hose connected via a second T connector to the liquid dispenser disposed at the other end of the hydraulic circuit, and
- a control circuit for operating the liquid dispensing system by continuous electronic monitoring of the liquid flow from the liquid dispenser by means of a radio frequency (RF) module and by controlling liquid supply via a liquid flow-meter disposed on the first liquid-supply hose between the first T connector and the liquid reservoir,
wherein, the pipe-in-pipe arrangement consists of at least one pair of air-supply pipe and air-return pipe, which is completely disposed within the second liquid-supply hose and the respective air-supply and air-return pipes are connected to the T connectors in a leak-proof manner.
Typically, the T connector comprises at least two through holes for conducting liquid-supply therethrough.
Typically, the connector further comprises a lateral opening on either side of the circumference thereof for connection to an air-supply line and an air-return line respectively by means a respective hex-connector.
Typically, each lateral opening opens into an air-supply channel configured with a blind hole on the first liquid-supply hose side and a through hole on the second liquid-supply hose side, the air supply channels configured perpendicular to the respective lateral openings.
Typically, the through holes for conducting liquid supply therethrough are configured substantially larger than the air-supply channel and air-return channel.
Typically, the through holes for conducting liquid supply therethrough are disposed in the same plane but at right angles to the air-supply and air-return channels.

Typically, the radio frequency (RF) module comprises at least one pair of radio frequency (RF) transmitter for transmitting data related to liquid flow from the liquid dispenser and a radio frequency (RF) receiver to receive the liquid flow data.
Typically, the radio frequency (RF) module further comprises a programmable logic controller (PLC) coupled to the radio frequency (RF) receiver for controlling the liquid- supply from the liquid reservoir and for manipulating air-supply through the second liquid-supply hose for obtaining the desired liquid flow from the liquid dispenser.
Typically, the T connector comprises at least two through holes, a lateral opening on either side of the circumference thereof, each lateral openings opening into an air-supply channel configured with a blind hole on the first liquid-supply hose side and a through hole on the second liquid-supply hose side, the air supply channels being configured perpendicular to the respective lateral openings.
Typically, the through holes are disposed in the same plane, however at right angles to the air-supply and air-return channels and configured substantially larger than the air-supply channel and air-return channel.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The present invention will be briefly described with reference to the accompanying drawings, which include:
Figure 1 shows a conventional pneumatic oil dispenser carrying air and oil in separate hoses or conduits.
Figure 2 shows another view of the arrangement of a conventional pneumatic as shown in Figure 1.
Figure 3 shows a preferred embodiment of pneumatic oil dispensing hose carrying air in an internal concentric hose routed through oil carrying hose.

Figure 4 shows two different views of the pipe-in-pipe type connectors used for connecting oil and air hoses as per the present invention shown in Fig. 3.
Figure 5 shows the schematic arrangement of the pneumatic, hydraulic and electronic circuits in accordance with the present invention.
DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS
In accordance with the present invention, a preferred embodiment of the arrangement of concentrically disposed pneumatic and oil dispensing hoses is provided, which will now be described in more details with reference to the accompanying drawings. However, it should be understood that the following description indicating the preferred embodiments and specific details thereof are given only by way of illustration and not of limitation.
Many changes and modifications may be readily made within the scope of the embodiments described and represented herein without departing from the ambit and spirit of the present invention. All these possible changes/modifications are included within this disclosure.
The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, these examples should not be construed as limiting the scope of the embodiments herein.
Figure 1 shows the conventional arrangement of a pneumatic oil dispenser carrying air and oil in separate hoses or conduits. The combined oil and air supply line 10 includes an oil hose 12 with a dispensing end 14. Two small diameter pneumatic pipes 16 for air-supply and exit respectively are attached externally on this oil hose 12 by means of a masking tape 26 to keep the two hoses together and intact. This also prevents any damage to air-pipe pipe 16 to some extent, however cannot completely protect it in rough and casual handling on the harsh working environment, e.g. present in a petrol/diesel

pumping station. A handle 18 and an oil dispensing lever 20 are provided at the dispensing end 14. The oil-hose 12 is also provided with a connector 22 for attaching air pipe 16 thereto near the oil dispensing end 14. The electrical connection cable 24 is provided over the oil hose 12 at the other end thereof. The oil hose 12, air pipe 12 and the electrical connection cable 24 are covered by means of a masking tape 26 for keeping them together during movements of the dispensing arrangement on the shop floor. In spite of the masking tape 26 covering the air pipe 16 and electrical connection cable 24 externally attached on the oil hose 12 for their safety, it requires frequent replacements due to rough handling and excessive damages caused by exposed surfaces at the harsh working area at the oil-dispensing station.
Figure 2 shows another view of the conventional pneumatic arrangement shown in Figure 1. However, it clearly indicates the spring conduit 25 externally placed over the entire length of the oil hose 12 and secured by means of masking tape 26.
Figure 3 shows an arrangement of the preferred embodiment of a pneumatic oil dispenser hose or conduit 100 carrying air in a separate pipe 116 but internally routed through the oil carrying hose 128. In contrast to the conventional arrangement shown in Figure 1, in this embodiment of the invention, the air pipe 116 is also provided with two connectors 112 and 122 at the two ends thereof. Both these connectors have T shaped configurations for carrying air for the pilot line based on pipe-in-pipe configuration. The connector 112 has an oil entry ports 102 and an oil exit port 102 (not shown) provided in the connector 122 disposed at its other end. These ports are connected to a solenoid switch for controlling the air supply for operating the oil dispensing unit. Both the connectors 112 and 122 are connected to the oil hose 128 in a leak proof manner. Air laterally enters through the air-entry port 104 on the connector 112 and flows in and then turned in the oil flow direction inside the oil-hose 128 by means of a right angled passage configured in T connector 112 to facilitate air flow in the oil-hose 128. The air exits through the air exit port on the connector 112 and

completes the air-supply circuit. The air-pipes 116 and the oil-pipe 128 are also internally connected to another T connector 122 disposed at the other end of this arrangement. This T' connector 122 is directly connected to the oil supply end 118 of the oil dispenser 114. A lateral arm of the connector 122 is connected at connection point 132 to a 'U' arm 130 of the air supply to the dispenser 114 provided with a transmitter circuit or RF module 106 for dispensing oil under a pneumatic pressure by means of a dispensing lever 120 controlled by a solenoid switch (not shown here). The RF module 106 eliminates the need for a control cable (electrical connection cable 24) of the conventional arrangement shown in Figures 1 and 2. This novel arrangement obviates any damage to air-pipes 116, which is now completely concealed within the main oil-hose 128. Use of electronic RF module instead of the conventional electrical connection cable eliminates any operational interruptions due to damaged electrical control cables, which was also routed externally.
Figure 4 shows a first view (a) of the connector 140 of the pipe-in-pipe connectors 140 (representing connectors 112, 122 of Figure 3) as seen at about the cross-section A - A marked in Figure 3 and a second view (b) seen from the direction of oil entry 102. The connector 140 is used for internally connecting air pipes 116 in the oil-hose 128. Connector 140 has hex-connector 142 for connecting air supply 104 disposed one ends thereof. The air exits via an air-exit port connecting the connector 140 to the air-supply circuit by means of another hex-connector 142. In view (a), there are four holes seen in the connector 140. Out of these, two smaller holes 146 are provided for connecting air supply 104 to the air-supply exit pipes 116 disposed inside the oil-hose 128 (by means of the pipe-in-pipe arrangement shown in Figure 3). These holes 146 are blind holes, i.e. ending just above the point of turning of the air supplied/exited from air-entry/exit port 104 in inside the oil-hose 128. The other two larger holes 144 are provided for oil supply through the oil hose 128. Whereas, the larger holes 144 shown in view (b) are through holes and oil supply hoses 102 can be connected at one ends 150 of these larger through holes 144 and other end of these through

hole 144 can be connected to oil hose 128. This pipe-in-pipe arrangement according to the present invention completely eliminates any potential damage to the air-pipes 116 due to harsh external environment at the oil-pumping stations. Since the air-pipes are completely surrounded by the pipe hose 128, in fact encompassed within it, there is no need for any extra spring conduit 25 or masking tape 26, as shown in the conventional arrangement of Figs. 1 and 2.
Figure 5 shows the schematic arrangement of the hydraulic, air and electronic circuits in accordance with the present invention. The hydraulic circuit consists of oil pump 101 supplying oil (e.g. petrol, diesel etc.) through oil supply hose 128 via a flow meter 111 to the dispenser 114. The air-circuit consists of air-supply 115 via a solenoid valve 121 connected to two air-pipes, i.e. an air-supply pipe 116S and an air-return pipe 116R respectively passing completely internally through the oil hose 128 and connected to the dispenser 114 in the manner already discussed in respect of Figures 3 and 4 above. The electronic circuit includes a programmable logic controller (PLC) 131 coupled to a solenoid valve 121 provided on pneumatic-circuit. PLC 131 is also coupled to trigger of RF module 106 provided with radio-frequency (RF) transmitter on the dispenser 114 via RF receiver in order to regulate oil-supply from dispenser 114. This PLC 131 is also coupled to oil-pump 101 and oil-flow meter 111 on the hydraulic circuit. Accordingly, the oil-supply and air-supply can be manipulated by means of PLC 131for delivering desired quantity of oil from dispenser 114. This does not require any electrical cable as in the conventional systems, which was also prone to frequent damage.
WORKING OF THE INVENTION
In accordance with the present invention, the air pipes 116S and 116R (for operating the pneumatic valve actuated by the solenoid valve 121) are internally routed through the oil carrying hose 128 and running substantially parallel and concentric to this oil hose 128 and air is forced via air-supply pipe 116S to create pneumatic pressure for dispensing oil, e.g. petrol or diesel. The air pipes 116S and 116R are connected to the connectors 112,

122 by using special hex-connectors 142 (Figure 4). Since the air-pipes 116S and 116R are completely inside the oil-hose 128, there is no possibility of damage to the air-pipes as was observed in the conventional oil-dispensing arrangements. Moreover, dispensing with the control cable and instead using RF module in its place also eliminates any operational and control limitations due to damage to control cables in such harsh working environments at oil-dispensing stations.
TECHNICAL ADVANTAGES AND ECONOMIC SIGNIFICANCE
• Oil and air are carried coaxially within the same oil-hose.
• Safeguards air-pipes by disposed them within oil-hose itself.
• No spring conduit needed over the main oil hose/pipe.
• No masking tape required over the main oil hose/pipe for securing the air-pipes over the oil hose.
• The main oil hose/pipe itself acts as the guard for small diameter pneumatic air-pipes.
• Offers a cost-effective device for supplying air for pneumatically operated oil dispensing machines.
• Provides a simple device for supplying air for pneumatically operated oil dispensing machines.
• Makes available a maintenance-free device for supplying air for pneumatically operated oil dispensing machines.
• Control cable completely eliminated by installing a RF module at the dispenser end.
Throughout this specification the word "comprise", or variations such as "comprises" or "comprising", shall be understood to implies including a described element, integer or method step, or group of elements, integers or method steps, however, does not imply excluding any other element, integer or step, or group of elements, integers or method steps.

The use of the expression "a", "at least" or "at least one" shall imply using one or more elements or ingredients or quantities, as used in the embodiment of the disclosure in order to achieve one or more of the intended objects or results of the present invention.
The exemplary embodiments described in this specification are intended merely to provide an understanding of various manners in which this embodiment may be used and to further enable the skilled person in the relevant art to practice this invention.
The description provided herein is purely by way of example and illustration. The various features and advantageous details are explained with reference to this non-limiting embodiment in the above description in accordance with the present invention. The descriptions of well-known components and manufacturing and processing techniques are consciously omitted in this specification, so as not to unnecessarily obscure the specification.
While considerable emphasis has been placed on the specific features of the preferred embodiment described here, it will be appreciated that many additional features can be added and that many changes can be made in the preferred embodiments without departing from the principles of the invention. These and other changes in the preferred embodiment of the invention will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.

We claim:
1. An liquid dispensing system with a concentric pipe-in-pipe arrangement
of air and liquid conduits for dispensing liquids, the arrangement
comprising:
- a pneumatic circuit, which consists of at least a pair of air-supply and air-return pipe connected to the respective pair of air-supply line and air-return line by means of a T connector,
- a hydraulic circuit consists of at least one first liquid-supply hose connected at first flat end of the first T connector connecting the first liquid-supply hose to the liquid reservoir disposed at one end of the hydraulic circuit and at least one second liquid-supply hose connected via a second T connector to the liquid dispenser disposed at the other end of the hydraulic circuit, and
- a control circuit for operating the liquid dispensing system by continuous electronic monitoring of the liquid flow from the liquid dispenser by means of a radio frequency (RF) module and by controlling liquid supply via a liquid flow-meter disposed on the first liquid-supply hose between the first T connector and the liquid reservoir,
wherein, the pipe-in-pipe arrangement consists of at least one pair of air-supply pipe and air-return pipe, which is completely disposed within the second liquid-supply hose and the respective air-supply and air-return pipes are connected to the T connectors in a leak-proof manner.
2. Liquid dispensing system as claimed in claim 1, wherein the T connector comprises at least two through holes for conducting liquid-supply therethrough.
3. Liquid dispensing system as claimed in claim 2, wherein the connector further comprises a lateral opening on either side of the circumference thereof for connection to an air-supply line and an air-return line respectively by means a respective hex-connector.

4. Liquid dispensing system as claimed in claim 3, wherein each lateral openings opens into an air-supply channel configured with a blind hole on the first liquid-supply hose side and a through hole on the second liquid-supply hose side, the air supply channels configured perpendicular to the respective lateral openings.
5. Liquid dispensing system as claimed in claims 2 to 4, wherein the through holes for conducting liquid supply therethrough are configured substantially larger than the air-supply channel and air-return channel.
6. Liquid dispensing system as claimed in claims 2 to 5, wherein the through holes for conducting liquid supply therethrough are disposed in the same plane but at right angles to the air-supply and air-return channels.
7. Liquid dispensing system as claimed in claims 1 to 6, wherein the radio frequency (RF) module comprises at least one pair of radio frequency (RF) transmitter for transmitting data related to liquid flow from the liquid dispenser and a radio frequency (RF) receiver to receive the liquid flow data.
8. Liquid dispensing system as claimed in claims 1 to 7, wherein the radio frequency (RF) module further comprises a programmable logic controller (PLC) coupled to the radio frequency (RF) receiver for controlling the liquid- supply from the liquid reservoir and for manipulating air-supply through the second liquid-supply hose for obtaining the desired liquid flow from the liquid dispenser.
9. Liquid dispensing system as claimed in claim 1, wherein the T connector comprises at least two through holes, a lateral opening on either side of the circumference thereof, each lateral openings opening into an air-supply channel configured with a blind hole on the first liquid-supply hose side and a through hole on the second liquid-supply hose side, the air supply channels being configured perpendicular to the respective lateral openings.

10. Liquid dispensing system as claimed in claims 2 to 5, wherein the through holes are disposed in the same plane, however at right angles to the air-supply and air-return channels and configured substantially larger than the air-supply channel and air-return channel.