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THE PATENTS ACT, 1970
(39 of 1970)
and Patent Rules 2003
PROVISIONAL SPECIFICATION
(See section 10; rule 13)
1. Title
A FUEL TANK CAP WITH RETRACTABLE FUEL MEASURING MECHANISM
2. Applicant
MAHINDRA & MAHINDRA LTD.
1, GATEWAY BUILDING, APOLLO BUNDER, MUMBAI - 400001. AN INDIAN
COMPANY.
The following specification describes the invention.
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Field of Invention
This invention generally relates to fuel tanks of automobile vehicles such as cars, tractors or other farm vehicles, or similar vehicles. More particularly, it relates to method of measuring fuel quantity in the fuel tank.
Background of the Invention (Prior-Art)
Dashboard indicators are commonly used to indicate fuel levels in the fuel tanks of vehicles. These indicators normally give a broad indication of the fuel level such as full, empty, and reserve, which doesn't accurately indicate the quantity of fuel in the fuel tank to the user.
Fuel level measurement gauges used commonly in automobiles detect the fuel level based on the change in resistance of the variable resistance element that is provided in such devices coupled with the buoyancy properties of the floats that are provided in such devices.
One of the drawbacks of these devices is that the change in resistance of the variable resistance element is not linearly proportional to the change in the level of the float towards the extremes of the fuel tank. As a result of this, the fuel gauge shows either full or empty status when the fuel tank is substantially less full than its maximum capacity or not fully empty, respectively. In practical terms, as the level of fuel in fuel tank begins to drop, a typical fuel gauge continues to read full & then drops relatively quickly from full to empty. A similar situation occurs when the tank is near empty. These non linear behaviors of such fuel gauges make them highly inaccurate.
A further limiting feature of the existing fuel gauges is that these require a power supply to be operational.
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In rural areas, particularly of developing nations, vehicle operators are known to use sticks, rods or any other suitable implement to measure the fuel level in the fuel tank. The implement is inserted into the fuel tank till it reaches its bottom. Once taken out of the tank, the operator is able to determine the fuel level by the wet mark on the implement. There are several drawbacks of this method. First, it may not be easy to find a suitable implement readily. Second, a piece of stick might break and fall off into the fuel tank. It is also cumbersome to always carry along a special implement which is not made purposefully for fuel measurement.
Several types of fuel gauges are available. The US patent 2834200 discloses a float actuated liquid fuel gauge for indicating volume of liquid within the fuel tank. US patent 2003/0177828A1 discloses a gauge wherein a vertical float is connected, through a twisted wire, to a needle that moves on a calibrated dial. The position of the needle on the dial shows the fuel level.
A drawback of the gauges described above is that they use a long rigid graduated rod connected to a float which moves vertically through fuel tank opening based on liquid level. While the vehicle is in motion the liquid level in the fuel tank varies constantly. The above mentioned system has an unsupported portion projecting inside or outside the fuel tank. As a result, a further drawback of the system is that the float system is subjected to jerks & vibrations, thereby making it more susceptible to damage & vibrational fatigue failure. A still further drawback of these gauges is that they are prone to higher rate of wear & tear as they are in use for all the time the vehicle is operational.
In case of Agricultural tractor the situation is even worse. This is because the engine vibrations of the agricultural automotive vehicles are much greater than those for normal civilian vehicles, as the agricultural vehicles operate in much harsher conditions. Another problem associated with these systems is during refueling it is necessary to take out the entire assembly along with fuel cap. As these assemblies comprise delicate parts, this becomes a cumbersome task.
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A further drawback of the invention disclosed in US 2003/01778287A1 is that it is useful for tank depths that can be covered in a single rotation of the needle. For tanks of irregular shape or where the tank depth is large, the dial may not give accurate reading if the needle rotation exceeds one turn, thus rendering the gauge unreliable in such circumstances.
US patent 2510663 discloses a device consisting of three concentric telescopic tubes connected to three floats. The accuracy of the measurement depends on smooth sliding of the telescopic tubes inside each other. As a result of the lateral movement of the floats (resulting from the liquid movement and vehicle vibrations) that are attached to the end of the tubes, the clearance between individual tubes gets affected thereby restricting their smooth movement. These gauges are thus prone to damage and malfunctioning.
A further disadvantageous feature of the available gauges is that they indicate a fuel level rather than fuel quantity. A still further disadvantage of the available systems is that the measurements obtained by them are misleading in case of fuel tanks that are irregular in shape or where the depth of the fuel tank (in the direction measured by the gauges) is not linearly proportional to the volume of the tank.
Objectives & Advantages of the Invention
The object of this invention is;
To provide a simple, handy quantity measuring gauge for liquid such as fuel, accommodated within cap body of liquid-container such as fuel tank, which ensures readily & timely availability of the gauge whenever required & indicates liquid volume rather than liquid level.
To provide mechanical fuel gauge, operating independently without external power supply like battery of the vehicle.
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To provide a gauge, which can be used for indicating quantity of liquid such as fuel, for different size & shape of the container such as fuel tank of a vehicle. To provide fuel cap with fuel gauge, which can be easily adopted & retrofitted on existing fuel tank of the vehicle.
Brief Description of Drawings
Figure 1 show the fuel tank cap generally used on the vehicle.
Figure 2 shows the exploded view of fuel tank cap with Retractable Fuel Quantity
Gauge according to the present invention.
Figure 3 shows the isometric view of fuel tank cap during fuel quantity
measurement.
Summary of the Invention
The present invention relates to cap for vehicle fuel tank with objective to provide a fuel gauge to quantify the amount of fuel available inside the fuel tank and also serving its primary objective of forming close chamber for storing and allow continuous escape of fuel fumes accumulating in the tank.
List of Parts:
Fuel Tank Cap (10)
Casing (2)
Spring (4)
Plate (12)
Tape Rule Unit (16 & 17)
Modified Bottom Chamber (11)
Rubber Gasket (6)
Detailed Description of the Preferred Embodiments
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Referring to figures 1, 2 and 3, figures 1 show conventional fuel tank cap (1) generally used on automobile vehicle for forming closed fuel tank (20) chamber and allow continuous escape of fuel fumes accumulating in the fuel tank (20). This fuel tank cap consists of casing (2), which houses bottom chamber (3), and spring (4). The casing (2) is provided with locking arrangement on its outer periphery to hold the bottom chamber (3) against the spring (4) force and lock against fuel tank neck (21). The bottom chamber (3) is provided with a small vent (5) such that it will be exposed to fuel fumes & allow them to escape to atmosphere. To avoid spillage of fuel an additional rubber gasket (6) is provided between the surface of tank neck (21) & side flange (7) of fuel cap (1). Spring (4) is provided between bottom chamber (3) & casing (2) to hold casing (2) & bottom chamber (3) in its position under pressure and ensures sealing of fuel cap (1) on fuel tank neck (21).
The improved fuel tank cap (10) according to the present invention is shown in the figure 2 & 3. An advantageous feature of the present invention is its bottom chamber (11), which is provided such that it will accommodate retractable fuel measuring mechanism such as tape rule unit (16 & 17). A measuring unit (16 & 17) consisting of a graduated and / or marked strip (17) & a spiral coil spring (16) is provided in lower compartment of modified bottom chamber (11). The graduated strip (17) is locked securely with one end of coil spring (16). Another end of coil spring is secured to the pivot (14), positioned at the center of bottom chamber (11). Spiral coil spring (16) along with the graduated strip (17) is wound around the central pivot (14). The bottom chamber (11) body is provided with an opening (18) on its outer periphery through which the graduated strip (17) can be pulled out for measuring the fuel quantity. In its normal position, the graduated strip and the spring coil remain wound loosely around the central pivot. Whenever the graduated strip (17) is pulled out, the spring coil (16) automatically gets wound tightly around the central pivot (14) because of the pull exerted by the graduated strip (17). When the graduated strip (17) is released after measurement, the spiral coil spring (16) acts to retract the graduated strip (17) to the original position that is inside of the
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bottom chamber (11). A plate (12) having a small vent (13) is provided to form a secured closed chamber for tape rule unit (16 & 17).
The graduated strip (17) is provided with fuel quantity / volume indications, which determines the available fuel quantity inside the fuel tank (20). The graduated strip (17) is pre-calibrated depending upon the geometry (size, shape, etc.) of the fuel tank (20). The graduations or the markings on the graduated strip (17) are made in the form of engravings filled with colour, or colour marks directly applied to the strip. Fluorescent material may also be used for improving visibility of graduations or the markings. Any other suitable method of marking the graduations is acceptable. The graduated strip (17) is made of a diesel fuel (or the liquid) -resistant material selected from a group comprising metals, alloys, plastic, or any other like material capable of winding into a coil, but remain sufficiently stiff like a common metal measure-tape strip.
In yet another embodiment of the present invention, a spirit level (22) is in built or attached to the casing (2) as shown in figure 2. The spirit level (22) is so placed that it allows to assess whether the vehicle chassis, thereby the fuel tank (20) is in approximately horizontal position and also whether the graduated strip (17) is in the vertical position at the time of measurement of the fuel. This ensures that the graduated strip (17) is always approximately perpendicular to the fuel level in fuel tank (20), thereby providing the correct measurement.
In still another embodiment of the present invention, the graduated strip (17) is provided with an mechanism where by it can be temporarily locked in any position to facilitate ease of reading.
To measure the quantity fuel in the fuel tank (20), the vehicle is first placed on horizontal ground. This is achieved with the help of the spirit level (22) provided on the fuel cap casing (2). The graduated strip (17) is pulled out sufficiently so that it will cover the depth of fuel tank (20). The strip is inserted into the fuel tank till it
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reaches the bottom of the tank. The spirit level (22) on the fuel tank cap (10) is used to ensure that the graduated strip (17) assumes an approximately vertical position. The graduated strip is pulled out without rolling it back into the cap. The wet mark on the graduated strip (17) is observed to know the fuel volume / quantity in the fuel tank (20).
It is evident that the invention has the following advantageous features:
1. The novel fuel measuring gauge is not battery operated and does not require any source of power to operate.
2. The novel graduations on the graduated strip provide a direct indication of fuel in terms of volume rather than vague indications such as full, half full, quarter full, etc.
3. The simplicity of the device of the invention means the volume measured by the present invention is true volume free of errors resulting from malfunctioning of parts.
4. The fuel cap fits back onto the fuel tank, thus ensures the timely availability & minimizes the chances of getting misplaced.

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