CLIAMS:1. A level sensing system for a liquid tank, said liquid level sensing system comprising:
o a tubular housing descending from operative top of said tank and having at least a portion of an interior thereof sealed to define a sealed section;
o a float element adapted to be axially movable along length of said tubular housing due to change in level of liquid inside the tank, said float element comprising at least one magnet secured thereto and moving along with said float element;
o a plurality of spaced reed switches disposed along the length of said tubular housing in said sealed section of said tubular housing, wherein said at least one reed switch is actuated when magnetic field associated with said at least one magnet secured to said float element interacts with said at least one reed switch depending upon position of said float element corresponding to the level of liquid inside the tank, and
o a plurality of electrical elements with each electrical element associated with a corresponding reed switch, said reed switches and said electrical element define an electrical circuit such that change in electrical parameters associated with said electrical elements due to actuation of a particular reed switch is received as an output from said electrical circuit that in turn is processed for determining level of liquid in the tank.

2. The level sensing system as claimed in claim 1, wherein said tubular housing is divided into a first section and a second section by a separator extending along the length thereof, said first section is in fluid communication with liquid held inside the tank and said float element is adapted to be received and axially movable within said first section as level of liquid received with said first section changes due to change in level of liquid inside the tank and said second section is sealed to define said sealed section.

3. The level sensing system as claimed in claim 1, wherein said tubular housing is of aluminum material.

4. The level sensing system as claimed in claim 1, wherein said electrical elements are electrical resistors, each electrical resistor is associated with a corresponding reed switch, said reed switches and said resistors define an electrical circuit such that change in an resistance due to actuation of a particular reed switch is received as an output from said electrical circuit that in turn is processed for determining level of liquid in the tank.

5. The level sensing system as claimed in claim 1, wherein a wall of said tubular housing is provided with guide-ways for facilitating guided axial movement of said float element along the length of said tubular housing.

6. The level sensing system as claimed in claim 5, wherein said float element is provided with at least one engaging element that is complementary to and engages with said guide-ways for facilitating axial guided movement of said float element along with length of said tubular housing.

7. The level sensing system as claimed in claim 5 further comprising a stopper configured on said wall of said tubular housing for restraining movement of said float element beyond a pre-determined height from an operative bottom end of said tubular housing.

8. The level sensing system as claimed in claim 1, wherein said plurality of spaced reed switches and said resistors are mounted on a Printed Circuit Board (PCB) to define said electrical circuit, said Printed Circuit Board (PCB) is received within said sealed section.

9. The level sensing system as claimed in claim 1, wherein spacing between said reed switches defines resolution and accuracy of said fuel level sensing system.
10. The fuel level sensing system as claimed in claim 1, wherein said float element further comprises contact elements protruding from external surface thereof for ensuring point contact between said float element and wall of said tubular housing. ,TagSPECI:FIELD

The present disclosure relates to a fuel level sensing system for a fuel tank of an automobile. More particularly, the present disclosure relates to an electronic arrangement for measuring level of fuel in a fuel tank.

BACKGROUND

A typical fuel level sensing systems of an automobile includes a sensing unit which measures the level of fuel in the tank, and a fuel level display device which displays that level to an occupant or driver of the automobile. Generally, the sensing unit is located inside the fuel tank of the automobile. The sensing unit includes a float connected to a thin, metal rod. The float material floats on the surface of the fuel and changes it’s position as the level of the fuel inside the fuel tank changes. The end of the rod is mounted to a variable resistor. More specifically, the variable resistor is a strip of resistive material connected on one side to the ground. As the fuel level inside the fuel tank increases, the float tends to float on top of the fuel level, thereby causing the electrical resistance to change. Specifically, there is a change in electrical resistance for each level of the fuel in the fuel tank. The change in electrical resistance is measured by the fuel level display devices on the vehicle and hence the fuel level is displayed. The conventional float-based fuel level detector requires a large space for the movement of the level. In consequence, in case of the conventional float based fuel level sensor the shape of the fuel tank cannot be freely changed to fit different mechanical devices.

Certain electronic based fuel level sensors are also known. The electronic fuel level sensors utilize two electrodes that are inserted into the fuel tank and kept in contact with the fuel in the fuel tank. The sensor senses the equivalent capacitance value between the two electrodes, and then converts the detected equivalent capacitance value into a reading indicative of the fuel level. Such configuration of the fuel level detector still has drawbacks associated therewith. For example, such electronic based fuel level sensors are complicated. More specifically, in case of such electronic based fuel level sensors it is necessary to measure the capacitance value between the two electrodes when the fuel tank is empty and the capacitance value between the two electrodes when the fuel level of the fuel in the fuel tank is full, and then the relative capacitance value is calculated subject to the height of the fuel tank. This operation procedure is complicated. Further, when the type of the storage fuel oil is changed, an additional compensation electrode must be installed in the fuel tank to compensate the difference.

Further other conventionally known electronic fuel level sensors uses reed switch exposed to liquid and are affected by pressure or depth. In existing fuel level indicator systems utilizing reed switches, a single reed switch is used within a hollow vertical tube and single or multiple ring magnets are used as magnetic elements. Because of the relatively short length over which a ring magnetic can influence the electrical condition of a reed switch, the existing fuel level indicator systems are useful only for measuring liquid level in relatively shallow tanks and for the purpose of indicating when a liquid level passes a predetermined point, such as an empty or dangerously low liquid level in a liquid storage tank. Furthermore, existing systems having a reed switch utilize magnetic rings or other magnetic elements that set up a uniform magnetic field, the reed switch undergoes numerous changes in electrical condition as the tank in which it is utilized is emptied or filled. This repeated change of condition of the reed switch necessitates an elaborate electrical circuit to make the switch condition meaningful.

However, above prior art arrangement used for measuring the level of fuel in a fuel tank is ineffective, inaccurate, requires regular maintenance and is less reliable. More specifically, the use of variable resistor for measuring the fuel levels in the fuel tank leads to inaccuracies. The conventional float based arrangement used for measuring the level of fuel in fuel tank requires large space for the movement of the float. Further, with such configuration of the conventional float based arrangement, the shape of the fuel tank cannot be freely changed to fit different mechanical devices. Further, the conventional electronic fuel level sensing systems are not safe due to chances of electronic circuitry of the fuel level sensing system coming in contact with the fuel. Further, the variable resistor becomes inaccurate with regular use thereof. Further, the prior art arrangement used for measuring the level of fuel in a fuel tank is ineffective when used in a dynamic system and in complex shaped fuel tanks. Further, in case of complex shaped fuel tanks, the prior art arrangement of fuel sensing may fail as the resistive based mechanisms gets damaged when in contact with fuel and as such cannot be fitted inside the fuel tank for measuring the fuel level in the fuel tank. Furthermore, the prior art arrangement used for measuring the level of fuel in a fuel tank are not accurate and gives an approximate reading of the quantity of the fuel in the fuel tank. Still further, the prior art arrangement involves a large number of components, thereby leading to frequent failures and regular maintenance. Further, the prior art arrangement of fuel sensing using float with resistive based mechanisms is expensive and difficult to assemble and dis-assemble. Further, over a period of time, the fuel tank gets scaled and thus there is some slight change in its volume. However, the prior art arrangement used for measuring the level of fuel in a fuel tank do not address inaccuracies in measurement of fuel level inside fuel tank due to such change in volume of the fuel tank.

Accordingly, there is a need for an arrangement for measuring the level of fuel in a fuel tank of an automobile that is effective, accurate, reliable and requires less maintenance. Still further, there is a need for an arrangement for measuring level of fuel in fuel tank that eliminates the use of bulky floats, thereby eliminating the drawbacks associated with use of bulky floats. Further, there is a need for an arrangement for measuring the level of fuel in fuel tank that requires less installation space inside the fuel tank unlike the conventional float based arrangements for measuring fuel level that requires space for the movement of the float inside the fuel tank. Further, there is a need for an arrangement for measuring the level of fuel in a fuel tank that eliminates the use of resistive based mechanisms and disadvantages associated with use thereof. Still further, there is a need for an arrangement for measuring the level of fuel in a fuel tank that can be effectively used in a dynamic system and in complex shaped fuel tanks. Furthermore, there is a need for an electronic fuel level sensing system that is accurate and still ensures safety by preventing contact between the electronic circuitry of the fuel level sensing system and the fuel. Still further, there is a need for an electronic fuel level sensing system that provide accurate fuel level readings by preventing any oscillation of the float. Further, there is a need for an arrangement for measuring the level of fuel in a fuel tank that requires lesser number of components and accordingly requires less maintenance. Still further, there is a need for an arrangement for measuring the level of fuel in a fuel tank that is simple in construction and inexpensive. Furthermore, there is a need for an arrangement for measuring the level of fuel in a fuel tank that is easy to assemble and dis-assemble.

OBJECTS

Some of the objects of the present disclosure, which at least one embodiment herein satisfies are as follows:

It is an object of the present disclosure to ameliorate one or more problems of the prior art or to at least provide a useful alternative.

An object of the present disclosure is to provide a system for sensing level of fuel in a fuel tank that can be used in dynamic environments.

Yet another object of the present disclosure is to provide a system for sensing level of fuel in a fuel tank that accurately senses the level of fuel irrespective of type of fuel held in the fuel tank.
Still another object of the present invention is to provide a system for sensing level of fuel in a fuel tank of complex configuration.

Yet another object of the present disclosure is to provide an electronic fuel level sensing system that provides accurate fuel level readings by preventing any oscillation of the float.

Another object of the present disclosure is to provide an electronic fuel level sensing system that is accurate and ensures safety by preventing contact between the electronic circuitry of the fuel level sensing system and the fuel.

Still another object of the present disclosure is to provide a fuel level sensing system that requires less installation space inside the fuel tank.

Another object of the present disclosure is to provide an effective arrangement for measuring the level of fuel in a fuel tank of an automobile.

Yet another object of the present invention is to provide a precise and reliable system for sensing level of fuel in a fuel tank of an automobile.

Still another object of the disclosure is to provide a fuel level sensing system that that requires lesser number of components.

Another object of the disclosure is to provide a fuel level sensing system that that requires less maintenance.

Yet another object of the present disclosure is to provide a fuel level sensing system for measuring the level of fuel in a fuel tank of an automobile that is simple in construction.

Still another object of the present disclosure is to provide a fuel level sensing system for measuring the level of fuel in a fuel tank that is resistant to wear and tear and exhibits long service life.
Yet another object of the present disclosure is to provide a fuel level sensing system for measuring the level of fuel in a fuel tank that is easy to assemble/dis-assemble.

Other objects and advantages of the present disclosure will be more apparent from the following description when read in conjunction with the accompanying figure, which are not intended to limit the scope of the present disclosure.

SUMMARY

A level sensing system for a liquid tank is disclosed in accordance with an embodiment of the present disclosure. The level sensing system includes a tubular housing, a float element, a plurality of spaced reed switches and a plurality of electrical elements. The tubular housing descends from operative top of the tank and has at least a portion of an interior thereof sealed to define a sealed section. . The float element is axially movable along length of said tubular housing a due to change in level of liquid inside the tank. The float element includes at least one magnet secured thereto and that moves along with the float element. The plurality of spaced reed switches are disposed along the length of the tubular housing in the sealed section of the tubular housing, wherein at least one reed switch is actuated when magnetic field associated with the at least one magnet secured to the float element interacts with the at least one reed switch depending upon position of the float element corresponding to the level of liquid inside the tank. Each electrical element of the plurality of electrical elements is associated with a corresponding reed switch. The reed switches and the resistors define an electrical circuit such that change in electrical parameters associated with the electrical elements due to actuation of a particular reed switch is received as an output from the electrical circuit that in turn is processed for determining level of liquid in the tank.

In accordance with an embodiment of the present disclosure, the tubular housing is divided into a first section and a second section by a separator extending along the length thereof. The first section is in fluid communication with liquid held inside the tank and the float element is received and axially movable within the first section as level of liquid received with the first section changes due to change in level of liquid inside the tank and the second section is sealed to define the sealed section.

Typically, the tubular housing is of aluminum material.

Preferably, the electrical elements are electrical resistors, each electrical resistor is associated with a corresponding reed switch, the reed switches and the resistors define an electrical circuit such that change in an resistance due to actuation of a particular reed switch is received as an output from the electrical circuit that in turn is processed for determining level of liquid in the tank.

Generally a wall of the tubular housing is provided with guide-ways for facilitating guided axial movement of the float element along the length of the tubular housing.

Further, the float element is provided with at least one engaging element that is complementary to and engages with the guide-ways for facilitating axial guided movement of the float element along the length of the tubular housing.

Further, the fuel level sensing system includes a stopper configured on the wall of the tubular housing for restraining movement of the float element beyond a pre-determined height from an operative bottom end of the tubular housing.
Generally, the plurality of spaced reed switches and the resistors are mounted on a Printed Circuit Board (PCB) to define the electrical circuit, wherein the Printed Circuit Board (PCB) is received within the sealed section.

Generally, the spacing between the reed switches defines resolution and accuracy of the fuel level sensing system.
Typically, the float element further includes contact elements protruding there-from for ensuring point contact between the float element and wall of the first tubular housing.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

Other aspects of the present disclosure will become apparent by consideration of the accompanying drawing and their description stated below, which is merely illustrative of a preferred embodiment of the present disclosure and does not limit in any way the nature and scope of the present disclosure.

Figure 1a illustrates a fuel level sensing system in accordance with an embodiment of the present disclosure;

Figure 1b – Figure 1g illustrates different views of the fuel level sensing system of Figure 1a;

Figure 2 illustrates a cross sectional view of the fuel level sensing system of Figure 1;

Figure 3 illustrates an outside view of a tubular housing of the fuel level sensing system of Figure 1, wherein an outside surface of the tubular housing includes a plurality of stopper apertures configured thereon;

Figure 4 illustrates a cross-sectional view of the tubular housing of Figure 3, wherein the interior of the tubular housing is divided into a first section and a second section by a separator extending along the length thereof;

Figure 5 illustrates a side view of a float of the fuel level sensing system of Figure 1, wherein the float has contact elements protruding from external wall thereof for ensuring point contact between the float element and inside wall of the first section;

Figure 6 illustrates an isometric view of the float element of Figure 5;

Figure 7 illustrates a front view of the float element of Figure 5;
Figure 8a illustrates a holding element for holding a Printed Circuit Board inside a second section of the tubular housing;
Figure 8b illustrates a detailed isometric view of the holding element of Figure 8a; and

Figure 9a and Figure 9b illustrates interaction between the magnet mounted on the float and the reed switch for actuation of the reed switch.

DETAILED DESCRIPTION

The present disclosure will now be described with reference to the accompanying drawings which do not limit the scope and ambit of the present disclosure. The description provided is purely by way of example and illustration.

The present disclosure envisages a level sensing system for sensing level of fuel in a fuel tank of an automobile. The fuel level sensing system is an electronic system that accurately senses level of fuel in the fuel tank while still ensures safety by preventing contact between electronic circuitry of the electronic fuel level sensing system and fuel held in the fuel tank. The fuel level sensing system requires less installation space inside the fuel tank. The fuel level sensing system provides accurate fuel level readings by preventing any oscillation of a float element of the fuel level sensing system. Although the level sensing system of the present disclosure is herein explained to be used for sensing level of fuel in a fuel tank of an automobile, however, the level sensing system is not limited for use in sensing level of fuel in a fuel tank and can be used for sensing level of any liquid inside any tank.

Figure 1a illustrates a fuel level sensing system 100 in accordance with an embodiment of the present disclosure. Figure 1b – Figure 1g illustrates different views of the fuel level sensing system 100 The fuel level sensing system 100 includes a tubular housing 10, a float element 20, a plurality of spaced reed switches 30a, 30b….30n and a plurality of resistors 40a….40n (not illustrated in Figure 1). The tubular housing 10 descends from operative top of the fuel tank and interior thereof is divided into a first section 10a, also referred to as the float section and a second section 10b, also referred to as Printed Circuit Board section by a separator 12 extending along the length thereof (as illustrated in Figure 2). Figure 2 illustrates a cross sectional view of the fuel level sensing system 100. As illustrated in Figure 2, the interior of the tubular housing 10 is divided into the first section 10a and the second section 10b. An operative top end of the tubular housing 10 is secured to a flange enclosure 04 that in turn is mounted on the wall of the fuel tank (not illustrated in Figures). Referring to Figure 1a, referral numeral “T” represents pigtail connected to the fuel level sensing system 100. An operative bottom end of the tubular housing 10 is closed by an end cap and grommet assembly 06. The tubular housing 10 is of aluminum material.

The first section 10a is in fluid communication with fuel held inside the fuel tank. The float element 20 is received and axially movable within the first section 10a. The float element 20 moves within the first section 10a as the level of fuel received within the first section 10a changes due to change in level of fuel inside the fuel tank. The float element 20 includes at least one magnet 22 (not shown in figure) secured thereto and that moves inside the first section 10a along with the float element 20. Particularly, the internal wall of the first section 10a of the tubular housing 10 is provided with guide-ways for facilitating receiving and facilitating guided axial movement of the float element 20 within the first section 10a. Further, the float element 20 is provided with at least one engaging element that is complementary to and engages with the guide-ways for facilitating axial guided movement of the float element 20 within the first section 10a of the tubular housing. Figure 5 illustrates a side view of the float element 20 of the fuel level sensing system 100, wherein the float element 20 has contact elements 24 protruding from external wall thereof for ensuring point contact between the float element 20 and inside wall of the first section 10a. In accordance with an embodiment, the external wall of the float element 20 has 4 point contacts configured thereon. With such configuration minimum contact between the float element 20 and the inside wall of the first section 10a is achieved, thereby ensuring minimum friction losses as the float element 20 slides within the first section 10a. Further, the float element 20 is provided with at least one protruding elements, also referred to as float wings 26 that are complementary to and engages with said cavities configured on the inside wall of the first section 10a for preventing oscillation of the float element 20 along the X and Z axis. The float wings 26 engages with the guide configured on tubular housing 10, particularly on inside wall of the first section 10a and avoids rotation of the float element 20 along the Z axis. Further, with such configuration of the float wings 26, the oscillations of the float element within the first section is negligible along X and Z axis. Figure 7 illustrates a front view of the float element 20. The float element 20 slides along the float cavity configured on the first section 10a of the tubular housing when there is a variation of the fluid level in the first section 10a. The float cavity makes point contacts with the float element 20. The Printed Circuit Board (PCB) assembly 70 is placed along the guide body for fluid level indication, and magnet mounted onto the float element 20 activates reed switch of the Printed Circuit Board (PCB) assembly 70 to indicate the fluid level. As fuel level raises, the float element 20 that has the density lower than the fuel tends to float, thereby activating the reed switch circuit, due to this activation of reed switch the resistance values changes, and the electronic circuit provides an output. The float actuation point is controlled by the distance b/w reed switch and magnet.

In accordance with an embodiment the float element is disposed outside the tubular housing and moves axially along the length of the tubular housing and the tubular housing has at least a portion of an interior thereof sealed to define a sealed section that accommodates the Printed Circuit Board (PCB) assembly.

The float element 20 is of Poly urethane (PU) foam material with a peculiar design float wings 26 which arrest the oscillation of the float along X and Z axis when working. The float further includes point contact protrusions for facilitating point contact with inside walls of the first section. The float element 20 along with magnet is the actuating part for PCB circuit. The float wings 26 controls oscillation. The point contact reduces contact area between aluminum tubular housing and the float element.

The plurality of spaced reed switches 30a, 30b… 30n are disposed along the length of the tubular housing 10 in the second section 10b of the tubular housing 10, wherein at least one reed switch is actuated when the at least one magnet secured to the float element 20 interacts with the at least one reed switch depending upon position of the float element 20 corresponding to the level of fuel inside the fuel tank. Each resistor of the plurality of resistors is associated with a corresponding reed switch. The reed switches are a relatively simple and an incredibly reliable device, which are magnetically activated and are used to monitor tank levels. The plurality of spaced reed switches and the resistors are mounted on a Printed Circuit Board (PCB) 70 to define an electrical circuit. The Printed Circuit Board (PCB) 70 is received within the second section 10b. More specifically, the second section 10b includes a slot 18 configured thereon for holding the Printed Circuit Board (PCB) 70 therein. Figure 8a illustrates a holding element 90 for holding the Printed Circuit Board (PCB) 70 inside the second section 10b of the tubular housing 10. Figure 8b illustrates a detailed isometric view of the holding element 90. More specifically, the holding element 90 includes extended profiles 92 for poke yoke and a circular embossed profile 94 for proper fitment of the Printed Circuit Board (PCB) 70 with the flange. The holding element 90 also includes a 5 bolt mounting system 96 and a plastic wall 98 for preventing contact between terminals. The bolt mounting system 96 is as per universal mounting standard for fuel sensors. The fuel level sensing system 100 detects the fuel level when level raises or drains inside the first section 10a of the tubular housing 10, specifically, the magnet carried by the float element 20 activates a reed-switch located at an equivalent vertical position inside the second section 10b of the narrow elongated Aluminum tubular housing 10. The tubular housing 10 is sealed by Grommet at the operative bottom end thereof and the first section 10a receiving the float element 20 separated from the second section 10b that receives reed switches 30a… 30n and resistors 40a… 40n mounted on the Printed Circuit Board (PCB) 70. With such configuration only the float element 20 will be in contact with fuel, and the sealed section 10b accommodates the electrical circuit configured on the Printed Circuit Board (PCB) 70 that has resistor and reed switches mounted thereon.
The reed switch contains a pair (or more) of magnetizable, flexible, metal reeds whose end portions are separated by a small gap when the switch is open. The reeds are hermetically sealed in opposite ends of a tubular glass envelope. One important quality of the switch is its sensitivity, the amount of magnetic field necessary to actuate it. A magnetic field (from an electromagnet or a permanent magnet) will cause the reeds to come together, thus completing an electrical circuit. The stiffness of the reeds causes them to separate, and open the circuit, when the magnetic field ceases. Reed switches can directly switch loads as low as a few microwatts without needing external amplification circuits.

The reed switches and the resistors define the electrical circuit such that change in resistance values due to actuation of a particular reed switch is received as an output from the electrical circuit that in turn is processed for determining level of fuel in the fuel tank. Figure 9a and Figure 9b illustrates interaction between the magnet mounted on the float element 20 and the reed switch for actuation of the reed switch. The spacing between the reed switches 30a, 30b… 30n defines resolution and accuracy of the fuel level sensing system 100. The fuel level sensing system 100 further includes a stopper 60, also referred to as float stopper 60 configured on the internal wall of the tubular housing 10 for restraining movement of the float element 20 beyond a pre-determined height from an operative bottom end of the tubular housing 10. In accordance with an embodiment the float stopper 60 is a plurality of stopper apertures. Referring to Figure 3, an outside surface of the tubular housing 10 includes a plurality of apertures 60 configured thereon that act as stopper. The stopper apertures 60 configured on the tubular housing 10 engage with protrusions provided on the float element 20 for restraining further movement of the float element 20 within the tubular housing 10. The float stopper 60 ensures safety limit of fuel during filling of the fuel. In accordance with an embodiment, float movement is restricted by a plastic pin heat crimped, where it is externally inserted and externally heat crimped.

TECHNICAL ADVANCEMENTS

The fuel level sensing system in accordance with the present disclosure has several technical advantages including but not limited to the realization of:

• a system for sensing level of fuel in a fuel tank that can be used in dynamic environments;
• a system for sensing level of fuel in a fuel tank of complex configuration;
• an electronic fuel level sensing system that provides accurate fuel level readings by preventing any oscillation of the float;
• an electronic fuel level sensing system that is accurate and ensures safety by preventing contact between the electronic circuitry of the fuel level sensing system and the fuel;
• a system for sensing level of fuel in a fuel tank that accurately senses the level of fuel irrespective of fuel held in the fuel tank;
• a fuel level sensing system that requires less installation space inside the fuel tank;
• a fuel level sensing system that is precise, reliable and robust in construction;
• a fuel level sensing system that requires lesser number of components;
• a fuel level sensing system that requires less maintenance;
• a fuel level sensing system that is simple in construction;
• a fuel level sensing system for measuring the level of fuel in a fuel tank that is resistant to wear and tear and exhibits long service life;
• a fuel level sensing system that is easy to assemble/dis-assemble

“Whenever a range of values is specified, a value up to 10 % below and above the lowest and highest numerical value respectively, of the specified range, is included in the scope of the disclosure”.

While considerable emphasis has been placed herein on the preferred embodiments, it will be appreciated that many embodiments can be made and that many changes can be made in the preferred embodiments without departing from the principles of the present disclosure. These and other changes in the preferred embodiments as well as other embodiments of the present disclosure will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the forgoing descriptive matter to be implemented merely as illustrative of the present disclosure and not as limitation.