A fuel tank isolation valve with an improved load adjustment mechanism

Abstract

The present invention relates to a fuel tank isolation valve (1), comprising a housing sub-assembly (18), a compression spring (10), a shaft (9), a main housing (2), a cover (6), a pressure spring (3), a stroke limiter (4), and a flow limiter (5). The pressure spring (3) is coil spring which is secured over said flow limiter (5) and configured to apply a consistent force on said flow limiter (5) for over-pressure relief function. The cover (6) has a modified structure which is easy to adjust for making a load of the pressure spring (3) variable that facilitates in increasing a tolerance band value for a spring manufacturing and for increasing a performance of the fuel tank isolation valve (1).

Description

[0001] “A FUEL TANK ISOLATION VALVE WITH AN IMPROVED LOAD ADJUSTMENT MECHANISM”

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to the field of fuel tank isolation valve. More specifically, the invention relates to a fuel tank isolation valve with an improved mechanism with load adjustment.

[0004] BACKGROUND OF THE INVENTION

[0005] The fuel tank isolation valve (FTIV) is a critical component in vehicle fuel systems which plays a vital role in managing fuel vapour and maintaining the pressure inside the fuel tank within safe and regulated limits, contributing to both emissions control and vehicle safety. In vehicles, fuel tanks are closed and pressurized systems. As fuel evaporates, it creates pressure inside the tank. Maintaining this pressure is important to minimize emissions and prevent fuel leakage. The fuel tank isolation valve helps control the pressure inside the tank by managing fuel tank venting.

[0006] The FTIV basically maintains the pressure inside the tank in a protected pressure range. The fuel tank isolation valve is installed between the fuel tank and a canister as part of the evaporative emission control system. It automatically opens when the pressure inside the tank exceeds certain limits, allowing excess vapour to flow to the canister for containment until it can be processed by the engine. If there's a negative pressure or vacuum generated inside the tank, such as during falling temperatures overnight, the fuel tank isolation valve opens automatically to maintain the pressure within a protected range. This prevents the tank from collapsing and allows fresh air to flow from the canister into the tank. During refuelling, the fuel tank isolation valve is electrically actuated to allow fuel vapour to flow from the tank to the canister, preventing the escape of fuel vapour into the atmosphere.

[0007] The current available fuel tank isolation valve have conical spring buckling issue during assembling process. Further, a spring need to be fit in between the ribs of the cover which makes the assembling process complex. Moreover, the hysteresis value is more in the currently available fuel tank isolation valve. Further, in the field of the fuel tank isolation valve the hysteresis value is a difference between the mechanical opening & closing value of pressure due to exceed in pressure or vacuum inside the fuel tank.

[0008] US11512655 discloses a fuel tank isolation valve (FTIV) and methods of operation are provided. The FTIV includes first and second solenoid valves with the movable valve member of one of the solenoid valves seating against a movable valve member of the other one of the solenoid valves. One of the solenoid valves may be refuelling valve allowing for evacuation of fuel vapour during refuelling operations as well as to allow for purging high vapour pressure within the fuel tank. One of the solenoid valves may be a proportional valve used to control the flow of fuel vapour to an intake manifold of an operating internal combustion engine as well as to reduce a vacuum generated within the fuel tank. However this FTIV may face conical spring buckling issue during the assembling process. Further there is requirement of fitting spring between the ribs of the cover which ultimately makes the assembling process difficult.

[0009] KR10-2023-0097523 discloses fuel tank isolation valve, wherein the upper end of a first spring is inserted into a seating groove formed in a solenoid housing and supported by a core plate therein. By not using a separate spring support member, the internal structure of a valve housing is simplified, the size is reduced, the consumption of injection materials is reduced, the assembly is improved, and the operating performance of the valve is improved. In addition, by using a conical coil spring as the first spring, the position of the central axis of the first spring and the position of the associated armature, valve assembly and the like are kept constant when the first spring extends and retracts of the first spring, thereby improving valve operation performance. However this invention may face conical spring buckling issue during assembling process. Further, a spring need to be fit in between the ribs of the cover which makes the assembling process complex. Also, the structure of this invention also increase the hysteresis value. Therefore, due to the abovementioned drawbacks, there is a need to introduce an improved FTIV that avoids buckling and reduce hysteresis loss.

[0010] OBJECTS OF THE INVENTION

[0011] The main object of the present invention is to provide a fuel tank isolation valve to obviate buckling effect.

[0012] Another object of the present invention is to provide a fuel tank isolation valve with an improved mechanism for load adjustment.

[0013] Yet another object of the present invention is to provide mechanism for load adjustment by adjusting the compression length with improved cover.

[0014] Still another object of the present invention is to provide a stroke limiter to control maximum flow from a valve, preventing issues such as caulking of other inline valves due to high flow.

[0015] SUMMARY OF THE INVENTION

[0016] The present invention introduces an improved mechanism of load adjustment over conventional FTIVs. The mechanism provides load adjustment capabilities by varying the compression length with cover pressing, providing a comprehensive spring load specification for flexible adjustment. Additionally, the invention includes a stroke limiter to control maximum flow from the valve, preventing issues such as caulking of other inline valves due to high flow.

[0017] In an embodiment, the present invention provides a fuel tank isolation valve. The fuel tank isolation valve comprises a housing sub-assembly, a compression spring, a shaft, a main housing, a cover, a pressure spring, a stroke limiter, and a flow limiter. The pressure spring is coil spring which is secured over said flow limiter and configured to apply a consistent force on said flow limiter for over-pressure relief function. The cover has a modified structure which is easy to adjust for making a load of the pressure spring variable that facilitates in increasing a tolerance band value for a spring manufacturing and for increasing a performance of the fuel tank isolation valve. Further, the pressure spring is a helical shape spring that have a reduced length to diameter ratio for preventing buckling issue and said helical shape reduces hysteresis value of said fuel tank isolation valve. Furthermore, the modified structure cover eliminates a rib structure which facilitate in increasing the tolerance band value for a spring manufacturing and for increasing the performance of the fuel tank isolation valve.

[0018] 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.

[0019] BRIEF DESCRIPTION OF THE DRAWING

[0020] An understanding of the fuel tank isolation valve with an improved load adjustment mechanism according to the present invention may be obtained by reference to the following drawing:

[0021] Figure 1 is an exploded view of a fuel tank isolation valve, according to an embodiment of the present invention;

[0022] Figure 2 is a cross-sectional view of a conventional fuel tank valve isolation valve having conventional assembly and cover;

[0023] Figure 3 is a cross-sectional view of a spring and improved flexible cover, according to an embodiment of the present invention; and

[0024] Figure 4 is a cross-sectional view of a fuel tank isolation valve with improved stroke limiter design, according to an embodiment of the present invention.

[0025] DETAILED DESCRIPTION OF THE INVENITON

[0026] 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.

[0027] 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, 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.

[0028] The present invention relates to an improved fuel tank isolation valve with load adjustment mechanism and to eliminate buckling in the FTIV. The improved FTIV comprises a flexible cover, a helical spring, a stroke limiter, a flow limiter, a nozzle, a shaft, a moving core, a housing, a seal and a shock mount. The helical spring of the FTIV has a reduced length to diameter ratio.

[0029] In an embodiment, the present invention provides a fuel tank isolation valve. The fuel tank isolation valve comprises a housing sub-assembly, a compression spring, a shaft, a main housing, a cover, a pressure spring, a stroke limiter, and a flow limiter. The pressure spring is coil spring which is secured over said flow limiter and configured to apply a consistent force on said flow limiter for over-pressure relief function. The cover has a modified structure which is easy to adjust for making a load of the pressure spring variable that facilitates in increasing a tolerance band value for a spring manufacturing and for increasing a performance of the fuel tank isolation valve. Further, the pressure spring is a helical shape spring that have a reduced length to diameter ratio for preventing a buckling issue and said helical shape reduces hysteresis value of said fuel tank isolation valve. Furthermore, the modified structure cover eliminates a rib structure which facilitate in increasing the tolerance band value for a spring manufacturing and for increasing the performance of the fuel tank isolation valve.

[0030] Referring to Figure 1 , an exploded view of an improved fuel tank isolation valve with an improved pressure spring, according to an embodiment of the present invention, is depicted. The fuel tank isolation valve with an improved load adjustment mechanism a housing sub-assembly (18), a compression spring (10), a shaft (9), apair of torque limiter and shock mount (14, 15), a main housing (2), a cover (6), a pressure spring (3), a stroke limiter (4), a flow limiter (5) and a compression shaft (13).

[0031] The housing sub-assembly (18) includes a moving core (7) and a compression spring (10) for over- vacuum relief (OVR) function. The compression spring (10) is placed on said compression shaft (13) and said compression spring (10) holds said moving core (7) in an upward position and keeps a seal (8) of said moving core (7) attached with a sealing surface of said flow limiter (5) and keeps said fuel tank isolation valve (1) in a closed condition. The shaft (9) is assembled with said moving core (7) for linear movement of said flow limiter (5).

[0032] The main housing (2) is provided with a a seal and a shock mount (14, 15) and a nozzle (16) that is connected to tank and a nozzle (17) is connected to canister of the vehicle, and said main housing (2) is mounted over a housing sub-assembly (18).

[0033] The flow limiter (5) is placed under said stroke limiter (4) and accommodated inside said main housing (2) configured to control the maximum flow by controlling operating stroke of said flow limiter (5).

[0034] The cover (6) is secured above said main housing (2) to close said fuel tank isolation valve (1) and maintains the installation height of said pressure spring (3). The cover (6) has an internal circular protrusion (19) to hold one end of said pressure spring (3) around a periphery of said internal circular protrusion (19) and another end of said pressure spring (3) is secured over said flow limiter (5) which simplifies an assembling process.

[0035] The pressure spring (3) is coil spring which is secured over said flow limiter (5) and configured to apply a consistent force on said flow limiter (5) for over-pressure relief function. The pressure spring (3) is a helical shape spring that have a reduced length to diameter ratio for preventing buckling issue and said helical shape reduces hysteresis value of said fuel tank isolation valve (1).

[0036] The cover (6) has a modified structure which is easy to adjust for making a load of the pressure spring (3) variable that facilitates in increasing a tolerance band value for a spring manufacturing and for increasing a performance of the fuel tank isolation valve (1). The modified structure cover (6) eliminates a rib structure which facilitate in ease of assembly & also during cover pressing by adjusting the pressing height it increases the tolerance band value for a spring manufacturing and for increasing the performance of the fuel tank isolation valve (1).

[0037] Referring to Figure 2, a cross-sectional view of a conventional fuel tank valve isolation valve having a conventional spring and a cover is depicted. The conventional fuel tank valve isolation valve (1’) include a conventional spring (3’) . The conventional spring (3’) is a conical spring which raises buckling issue during an assembling process, when the conventional spring (3’) has to be fitted between one or more ribs (6A) of the conventional spring (3’). Ultimately, the hysteresis value is more in the conventional fuel tank valve isolation valve (1’).

[0038] Referring to Figure 3, a cross-sectional view of an improved pressure spring with adjustable cover, according to an embodiment of the present invention is depicted. The pressure spring (3) is helical in shape with a reduced length-to-diameter ratio. Further, the helical structure of pressure spring eliminates the need to fit springs between the ribs that makes the assembly simpler. The pressure spring (3), along with the improvised cover (6) configured to adjust the spring load by varying compression length with cover pressing. Thus, such an arrangement achieves flexible adjustment of cover to vary the spring load, increasing the tolerance band for spring manufacturing. Thus, enhancing the performance through load adjustment.

[0039] Referring to Figure 4, a cross-sectional view of a fuel tank isolation valve (1) with a stroke limiter (4), according to an embodiment of the present invention, is depicted. The stroke limiter (4) for valve system is used to restrict maximum flow from the valve and prevent caulking of other inline valves due to high flow. Under the condition of maximum flow, the flow limiter touches the stroke limiter, and flow then only passes through the holes in the flow limiter.

[0040] The improved spring mechanism with load adjustment and stroke limiter offers a novel solution to address assembly complexities, hysteresis issues, and flow control challenges in valve systems. This invention aims to enhance efficiency, performance, and ease of use in mechanical applications.

[0041] EXAMPLE 1

[0042] Preferred Implementation of the Present Invention

[0043] The present invention provides a fuel tank isolation valve (1) with an improved mechanism with load adjustment in which an improved pressure spring (3) is utilized which is in helical shape or a coil spring shape which avoid the buckling issue during the assembling process. Moreover, the cover (6) of the present invention has a modified structure, without any rib structure which also eliminates the buckling issue. The conventional structure (1’) of the fuel tank isolation valve (1) include rib structure (6 A) in the cover and a conical spring (3’) was utilized which caused buckling issues during assembling process.

[0044] Further, the length to diameter ratio is reduced in the present invention which helps to prevent the buckling issue.

[0045] The utilization of the helical shaped pressure spring (3) refers to unwanted bending or misalignment of the spring when subjected to compressive forces. Additionally, the modified structure of the cover (6) makes the spring load specification of the present invention comprehensive which also makes the present invention more flexible to use. The modified structure of the cover (6) is easily adjusted to make the load of spring variable that further facilities in increasing the tolerance band for the spring manufacturing.

[0046] Therefore, the present invention provides a fuel tank isolation valve with an improved mechanism with load adjustment in which an improved pressure spring is utilized which is in helical shape or a coil spring shape which avoid the buckling issue during the assembling process. Also, the cover of the fuel tank isolation valve have a modified structure, without any ribs which facilitates in preventing the buckling issue.

[0047] 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.

[0048] 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

CLAIMSWe claim:

1. A fuel tank isolation valve (1) comprising: a housing sub-assembly (18); a compression spring (10); a shaft (9); a main housing (2); a cover (6); a pressure spring (3); a stroke limiter (4); and a flow limiter (5); wherein: said pressure spring (3) is a coil spring which is secured over said flow limiter (5) and configured to apply consistent force on said flow limiter (5) for overpressure relief function; and said cover (6) has a modified structure that facilitates in adjusting load of the pressure spring (3) variable that facilitates in increasing tolerance band value for a spring manufacturing and for increasing performance of the fuel tank isolation valve (1).

2. The fuel tank isolation valve (1) as claimed in claim 1, wherein said housing sub-assembly (18) includes a moving core (7) and a compression spring (10) for over-vacuum relief (OVR) function.

3. The fuel tank isolation valve (1) as claimed in claim 1, wherein said compression spring (10) holds said moving core (7) in an upward position and keeps a seal (8) of said moving core (7) attached with a sealing surface of said flow limiter (5) and keeps said fuel tank isolation valve (1) in a closed condition.

4. The fuel tank isolation valve (1) as claimed in claim 1, wherein said shaft (9) is assembled with said moving core (7) for linear movement of said flow limiter (5).

5. The fuel tank isolation valve (1) as claimed in claim 1, wherein said main housing (2) is provided with a seal and a shock mount (14, 15) and a nozzle (16) that is connected to a tank and a nozzle (17) is connected to a canister of the vehicle, and said main housing (2) is mounted over a housing subassembly (18).

6. The fuel tank isolation valve (1) as claimed in claim 1, wherein said flow limiter (5) is placed under said stroke limiter (4) and accommodated inside said main housing (2) configured to control the maximum flow by controlling operating stroke of said flow limiter (5).

7. The fuel tank isolation valve (1) as claimed in claim 1, wherein said cover (6) is secured above said main housing (2) to close said fuel tank isolation valve (1) and maintains the installation height of said pressure spring (3).

8. The fuel tank isolation valve (1) as claimed in claim 1, wherein said cover (6) has an internal circular protrusion (19) to hold one end of said pressure spring (3) around a periphery of said internal circular protrusion (19) and another end of said pressure spring (3) is secured over said flow limiter (5) which reduces a length to diameter ratio.

9. The fuel tank isolation valve (1) as claimed in claim 1, wherein said pressure spring (3) is a helical shape spring with a reduced length to diameter ratio for preventing buckling issue and said helical shape reduces hysteresis value of said fuel tank isolation valve (1).

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