FIELD OF THE INVENTION
The present invention relates to a fuel tank isolation valve. More specifically, the present invention is directed towards an improved fuel tank isolation valve with an independent pressure holding chamber that has a robust structure, reduces rejection in production line and helps in maintaining spring (over pressure condition) installation load.
BACKGROUND OF THE INVENTION
A fuel tank isolation valve (FTIV) is an essential part of an evaporative emission control system that is generally present in hybrid automobiles and responsible for controlling fuel vapor flow from a fuel tank to the carbon canister. The fuel tank isolation valve is assembled with a mechanical bypass to discharge a certain amount of pressure or vacuum from the fuel tank in case it exceeds a pre-set threshold value. The flow of the vapors is controlled by a feature known as the integrated flow limitation feature already available in the fuel tank isolation valve. The installation of the valve is in such a manner that one port is connected to the fuel tank of the vehicle and the other port is assembled to the canister of the vehicle. At the time of over pressure condition inside the fuel tank flow happens from fuel tank side to canister side of the vehicle whereas on over vacuum condition flow happens from canister side of the vehicle to tank side of the vehicle. At the time of refueling, flow happens from tank side to canister side of the vehicle.
The fuel tank isolation valve works well in refueling conditions, as it offers a balanced amount of pressure among the fuel tank and atmosphere. There are two sceneries in the fuel tank isolation valve i.e. over pressure condition (OPR), in which the pressure level crosses the pre-set threshold valve and over vacuum condition over (OVR) in which the vacuum level crosses the pre-set threshold valve.
Several modifications and improvements were done in the fuel tank isolation valve to resolve the drawbacks to provide an ideal valve for hybrid vehicles and pressurized fuel systems with features like compact and lightweight inline design, rapid depressurization, reduces vapor permeation, flexible mounting orientation and pressure sensing technique. But mechanical opening points in over pressure condition is controlled with the help of mechanical compression springs. Due to lower tolerance band of specification of opening point, desired spring load to meet the specification has also a low manufacturing tolerance band which is very difficult to maintain in manufacturing.
US9518677B2 discloses a method and system for adjusting a fuel tank isolation valve in which the valve is adjusted to create a vacuum in the fuel system or increase fuel tank pressure above a threshold pressure by using electrical pulses. But this invention does not provide an optimal, cost friendly solution to reduce rejection in production line and helps in maintain spring installation load.
US20170036531A1 discloses a fuel tank isolation valve with bypass configuration that vents vapor from the fuel tank to a canister including components like a fuel tank, a purge canister, a valve assembly that is fluidly coupled between the fuel tank and the purge canister and that selectively controls fuel vapor flow between the fuel tank and the purge canister; and a bypass means that selectively bypasses fuel vapor around at least a portion of the valve assembly from the fuel tank to the purge canister. But this invention does not provide a robust, optimal and cost friendly solution to reduce rejection in production line and helps in maintain spring installation load.
Therefore, due to the aforementioned drawbacks, there is a need to provide a robust, optimal and cost friendly solution to reduce rejection in production line by introducing an improved fuel tank isolation valve with an independent pressure holding chamber with enhanced adjustment mechanism in which spring (OPR) installation load is adjusted or maintained at the target value to get desired performance of valve in over pressure condition and the pressure holding chamber is compact size pressure holder, which perform over pressure condition that is independently tested and assembled it with the final assembly of the valve.
OBJECT OF THE INVENTION
The main object of the present invention is to provide an improved fuel tank isolation valve with an independent pressure holding chamber that has a robust, optimal and cost friendly structure.
Another object of the present invention is to provide an improved fuel tank isolation valve with an independent compact size pressure holding chamber.
Yet another object of the present invention is to provide an improved fuel tank isolation valve with an independent pressure holding chamber through which spring (OPR) installation load is maintained at the target value to get desired performance of valve in over pressure condition.
Yet another object of the present invention is to provide an improved fuel tank isolation valve with an independent pressure holding chamber that offers enhanced tolerance band for manufacturing of springs.
Still another object of the present invention is to provide an improved fuel tank isolation valve with an independent pressure holding chamber to reduce rejection in production line.
SUMMARY OF THE INVENTION
The present invention relates to an improved fuel tank isolation valve with an independent pressure holding chamber that has a robust, optimal and cost friendly structure through which spring (OPR) installation load is maintained at the target value to get desired performance of valve in over pressure condition to reduce rejection in production line.
In an embodiment, the present invention provides an improved fuel tank isolation valve with an independent pressure holding chamber, comprising of a solenoid assembly, a spring for over vacuum relief (OVR) condition, a spring for over pressure relief (OPR), at least one electrical connector, at least two mounting holes a tank port, a flow limiter and a canister port, a seal sub assembly for over vacuum relief (OVR) condition with sealing lip wherein the improved fuel tank isolation valve includes an independent pressure holding chamber that comprises of a seal assembly of over pressure relief (OPR) condition with a sealing lip of over pressure relief (OPR), an adjustable cover, and the spring for over pressure relief (OPR) which is adjusted by the help of a stopper present in the independent pressure holding chamber.
The above objects and advantages of the present invention will become apparent from the hereinafter set forth brief description of the drawings, detailed description of the invention, and claims appended herewith.
BRIEF DESCRIPTION OF THE DRAWINGS
An understanding of the of the present invention may be obtained by reference to the following drawing:
Fig. 1 is an outer view of the improved fuel tank isolation valve with an independent pressure holding chamber according to an embodiment of the present invention.
Fig. 2 is a cross sectional view of the improved fuel tank isolation valve with an independent pressure holding chamber according to an embodiment of the present invention.
Fig. 3 is another cross sectional view of the improved fuel tank isolation valve with an independent pressure-holding chamber in idle off condition according to an embodiment of the present invention.
Figs. 4, 5, and Fig. 6 are perspective views of the improved fuel tank isolation valve with an independent pressure-holding chamber in over pressure relief (OPR) condition according to an embodiment of the present invention.
Figs. 7, 8, and Fig. 9 another perspective views of the improved fuel tank isolation valve with an independent pressure holding chamber in over vacuum relief (OVR) condition according to an embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
The present invention will now be described hereinafter with reference to the accompanying drawings in which a preferred embodiment of the invention is shown. This invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiment set forth herein. Rather, the embodiment is provided so that this disclosure will be thorough, and will fully convey the scope of the invention to those skilled in the art.
Many aspects of the invention can be better understood with references made to the drawings below. The components in the drawings are not necessarily drawn to scale. Instead, emphasis is placed upon clearly illustrating the components of the present invention. Moreover, like reference numerals designate corresponding parts through the several views in the drawings. Before explaining at least one embodiment of the invention, it is to be understood that the embodiments of the invention are not limited in their application to the details of construction and to the arrangement of the components set forth in the following description or illustrated in the drawings. The embodiments of the invention are capable of being practiced and carried out in various ways. In addition, the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting.
The present invention provides an improved fuel tank isolation valve with an independent pressure holding chamber that offers an enhanced adjustment mechanism in which spring (OPR) installation load is adjusted or maintained at the target value to get desired performance of valve in over pressure condition and the pressure holding chamber is compact size pressure holder, which perform over pressure condition that is independently tested and assembled it with final assembly of the valve.
Referring to Fig. 1, an outer view of the improved fuel tank isolation valve with an independent pressure holding chamber is shown. The improved fuel tank isolation valve (100) is divided into two sections i.e. upper section or valve section and lower section i.e. solenoid section. The improved fuel tank isolation valve (100) with an independent pressure holding chamber, comprises of a solenoid assembly (10), a spring (1) for over vacuum relief (OVR) condition, a spring (4) for over pressure relief (OPR), a tank port (8), a flow limiter (11), at least one electrical connector (16), at least two mounting flanges (15) and a canister port (9), wherein the improved fuel tank isolation valve (100) includes an independent pressure holding chamber (7) that comprises of a sealing lip (2) and seal (3) for over pressure relief (OPR), a seal sub assembly (5) with a sealing lip (6) for over vacuum relief (OVR) condition, an adjustable cover (12), and the spring (4) for over pressure relief (OPR) which is adjusted by the help of a stopper (13) present in the independent pressure holding chamber as shown in Fig. 2.
In the idle condition the improved fuel tank isolation valve (100) with an independent pressure holding chamber the spring (1) for over vacuum relief (OVR) retains the seal sub assembly (5) of over vacuum relief (OVR) upwards and is attached with the sealing lip (6). The spring (4) for over pressure relief (OPR) retains the sealing lip (2) of over pressure relief (OPR) in contact with the seal (3) and thereby keeps the improved fuel tank isolation valve (100) closed as depicted in Fig. 3.
During refueling, solenoid is switched turned ON and due to the magnetic field moving core (14) moves downward causing seal sub assembly (5) of over vacuum relief (OVR) open the seal (5) & seal (2) of over pressure relief (OPR) remain closed. At this moment, the moving core (14) force due to magnetic field is greater than the spring (1) for over vacuum relief (OVR) force. So, due to this magnetic force, the moving core (14) moves downwards and seal sub assembly (5) gets detach from the sealing lip (6). In this way, port is opened and connect the tank port (8) to canister port (9) at the time of actuation during refueling. In this way in idle condition, both the openings are closed and tank port (8) is not connected to the canister port (9) of the improved fuel tank isolation valve (100) and till the pressure inside the tank is with in safety limit vapors remains inside the fuel tank.
Referring to Figs. 4 to 6, perspective views of the improved fuel tank isolation valve with an independent pressure-holding chamber are depicted in over pressure relief (OPR) condition. Pressure is built inside the independent pressure holding chamber (7) and the spring (4) for over pressure relief (OPR) keeps the seal (3) in contact with the sealing lip (2) for keeping the improved fuel tank isolation valve (100) in closed condition (Shown in Figure 4). When the pressure increases beyond the protection point limit, the pressure force compresses the spring (4) for over pressure relief (OPR) and lifts the seal (3) from sealing lip (2). Due to the lifting of seal (3) the port opens and permits the flow from the tank port (8) to the canister port (9). During opening excess fuel vapors go to canister and when the pressure again come down the safety limit port is closed, (shown in Figs. 5 and 6).
Referring to Figs. 7 to 9, another perspective view of the improved fuel tank isolation valve with an independent pressure holding chamber are depicted in over vacuum relief (OVR) condition. When the vacuum is built inside the independent pressure holding chamber (17) of the improved fuel tank isolation valve (100), the spring (1) for over vacuum relief (OVR) keeps the seal sub assembly (5) of over vacuum relief (OVR) in contact with the sealing lip (6) keeping the improved fuel tank isolation valve (100) in closed condition (shown in Fig. 7). When the vacuum increases beyond the protection point limit, vacuum force compresses the spring (1) and the seal sub assembly (5) moves in a downwards direction that outcomes in opening of the ports and smooth flow from the canister port (9) to tank port (8). During this opening, the vacuum is released from the tank and again when the vacuum comes within safety limit, the ports are closed (shown in Figs. 8 and 9).
Therefore, the present invention provides an improved fuel tank isolation valve (100) with an independent pressure holding chamber that offers an advanced adjustment mechanism, where the spring (OPR) installation load is maintained at the target value to get desired performance of valve (100) in over pressure condition. The independent pressure holding chamber (7) is compact size pressure holder, by which an operator separately checks the performance of pressure holder in over pressure condition without assembly with improved fuel tank isolation valve (100) and after testing, the operator assembles the pressure holder with improved fuel tank isolation valve (100) which reduces rejection in the production line.
The present invention provides a provision of flexible installation of spring for (OPR) at any height where the targeted opening point can be achieved and more tolerance band is provided for manufacturing of springs. This working mechanism of the present invention may be adopted in all kinds of valves where mechanical opening points of the valve are controlled with the help of compression springs. Manufacturing tolerances of other parts are also balanced.
Many modifications and other embodiments of the invention set forth herein will readily occur to one skilled in the art to which the invention pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the invention is not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.
The foregoing description of embodiments of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of the invention. The embodiments were chosen and described in order to explain the principals of the invention and its practical application to enable one skilled in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated.

CLAIMS

We claim:
1. An improved fuel tank isolation valve (100) with an independent pressure holding chamber, comprising of:
an independent pressure holding chamber (7);
a tank port (8);
a canister port (9); and
a moving core (14);
wherein:
said independent pressure holding chamber (7) having compact size includes a sealing lip (2) and a seal (3) for over pressure relief (OPR), a seal sub assembly (5) with a sealing lip (6) for over vacuum relief (OVR), an adjustable cover (12) and a spring (4) for over pressure relief (OPR) which is adjusted by a stopper (13);
said spring (4) keeps the seal (3) in contact with said sealing lip (2) when pressure is built inside and increases beyond a protection point limit and said spring (4) compresses and lift said seal (3) in an upward direction and permits the flow from said tank port (8) to said canister port (9) in an over pressure relief (OPR) condition; and
said independent pressure holding chamber (7) includes a spring (1) for said over vacuum relief (OVR) which keep said seal sub assembly (5) in contact with said sealing lip (6) when vacuum is built inside and increases beyond a protection point limit and said spring (1)moves said seal sub assembly (5) in downwards direction which permits the flow from said tank port (8) to said canister port (9) in an over vacuum relief (OVR) condition.

2. The improved fuel tank isolation valve (100) with an independent pressure holding chamber as claimed in claim 1, wherein said improved fuel tank isolation valve (100) includes a flow limiter (11), at least one electrical connector (16), at least two mounting brackets (15).
3. The improved fuel tank isolation valve (100) with an independent pressure holding chamber as claimed in claim 1, wherein said independent pressure holding chamber (7) having said spring (1) retains said seal sub assembly (5) upwards and is attached with said sealing lip (6) and retains said sealing lip (2) in contact with said seal (3) and thereby keeps said improved fuel tank isolation valve (100) closed in idle condition.

4. The improved fuel tank isolation valve (100) with an independent pressure holding chamber as claimed in claim 1, wherein said moving core (14) moves downwards due to the magnetic field as a solenoid (10) is switched ON that causes said seal sub assembly (5) to open and said sealing lip (2) remains close, while said seal sub assembly (5) gets detach from said sealing lip (6) connecting said tank port (8) to said canister port (9) at the time of actuation during refuelling.
5. The improved fuel tank isolation valve (100) with an independent pressure holding chamber as claimed in claim 1, wherein said spring (4) having provision of flexible installation at any height where a targeted opening point is achieved and more tolerance band is provided.