DESC:Field of the invention:
The present invention relates to a carbon canister that are used in the evaporative emission control system and more particularly it relates to easy to install carbon canister with a convenient arrangement for keeping the bed of adsorbent material in compact condition, in case of expansion of cannister casing.
Background of the invention:
A carbon canister is used to trap and adsorb fuel vapor emissions from the fuel tank of a vehicle. It is part of the evaporative emission control system used to reduce air pollution. The carbon canister is usually located in the engine compartment or near the fuel tank. In an internal combustion engine, fuel vapors are generated from the fuel tank due to temperature change and agitation. When the engine shuts off, fuel vapors flow from the fuel tank into the carbon canister. The activated charcoal in the carbon canister traps or adsorbs the fuel vapors. These vapors contain volatile organic compounds that contribute to air pollution and the formation of smog. The carbon canister is designed to adsorb these vapors and prevent them from escaping into the environment. Later, when the engine starts, fresh air flows through the carbon canister and picks up the fuel vapors. The air with the trapped fuel vapor then flows into the intake manifold and becomes part of the air/fuel mixture entering the engine cylinder. A carbon canister installed vehicle reduces air pollution by preventing hydrocarbon vapors from escaping into the atmosphere. Further, carbon canister improves fuel economy by preventing hydrocarbon vapors from being drawn into the engine. It also prevents from the formation of smog.
The basic design of carbon canister includes a closed canister housing filled with a fuel vapor adsorbent material, preferably activated charcoal/ carbon granules. The bed of activated carbon is usually retained in the canister housing by an end plate that is pressed into the end face of the carbon bed to keep it tightly packed. The end plate is sized based on the nominal size of the perimeter of the inner surface of the canister housing. Canister housings are subject to expansion both from water absorption and heat, since the canisters are normally mounted in an environment that is subject to high heat and water splash. Also, due to vibrations the carbon bed settles down. Due to the expansion of the canister housing, the carbon bed becomes loose, since it does not expand in volume correspondingly. Due to looseness of carbon bed, vapor adsorption is reduced and the canister is more likely to leak vapors into the atmosphere when the engine is not running. This can lead to air pollution and can also damage the environment. This lowers the performance of the canister and leads to the problems such as engine stalling and poor fuel economy. Carbon canisters with loosened carbon bed are more likely to be damaged if they are subjected to a lot of vibration. This can lead to leaks and other problems. Further, they are not as effective at preventing the release of harmful pollutants into the atmosphere. To overcome the problem of loosening of carbon bed, the end plate is made movable such that it is continually biased into the face of the carbon bed so that it remains tightly packed. The end plate is made movable by arranging a volume change compensator that maintains the packing of the carbon bed.
In the existing designs of the carbon canisters, the volume change compensator is a spring that is placed between the end plate and the carbon bed. The volume change compensator/ spring is a separate component that needs a special care while installing in the canister assembly, as the volume change compensator needs to be properly aligned between the end plate and the carbon bed. Further, the overall cost of such spring installation is high. Accordingly, there exists a need to provide an easy to assemble carbon canister that overcomes the drawbacks in the prior art.
Objects of the invention:
The primary object of present invention is to provide an easy to install carbon canister with convenient arrangement for keeping the bed of adsorbent material in compact condition, in case of expansion of volume of the cannister.
Another object of the present invention is to regulate the flow of vapor from the fuel tank to the atmosphere through a carbon canister.
Still another object of the present invention is to prevent the release of harmful pollutants into the atmosphere by making the carbon canister leakage proof.
Further object of the present invention is to avoid chances of de-aligning of volume change compensation spring while installing a carbon canister.
Summary of the invention
The present invention discloses a carbon canister provided with an arrangement for compensation in volume change of the canister, that maintains the adsorbent material bed in compact condition. The carbon canister comprises a casing filled with an adsorbent material, a compression plate and an end cap. The bed of adsorbent material is compactly held between a first filter mesh and a second filter mesh. The casing receives fuel vapor and atmospheric air from one end and it is fitted with an end cap at the other end. The compression plate is arranged between the end cap and the second filter mesh. The end cap is having a volume change compensation element integrated thereto. The volume change compensation element is arranged in compressed state between the compression plate and the end cap with a biasing force acting on the compression plate, compactly holding the bed of the adsorbent material. The end cap with integrated volume compensation element is a single component, made by plastic injection molding process. The end cap seals the carbon canister in compact condition and the volume compensation element integrated thereto maintains the adsorbent material in compact condition even in case the canister body expands due to water absorption or heat and in case the adsorbent material bed settles down due to vibrations.
Brief description of the drawings:
The objects and advantages of the present invention will become apparent when the disclosure is read in conjunction with the following figures, wherein
Figure 1 shows a perspective view of a carbon canister integrated with a spring, in accordance with an embodiment of the present invention;
Figure 2 shows the expanded view of spring integration in bottom cover, in accordance with an embodiment of the present invention.
Detailed description of the embodiments:
The foregoing objects of the invention are accomplished and the problems and shortcomings associated with the prior art techniques and approaches are overcome by the present invention as described below in the preferred embodiment.
The present invention provides an arrangement for compensating change in the volume of a compact carbon bed in a carbon canister. The volume change compensation arrangement maintains the bed of adsorbent material, usually a bed of activated carbon, in compact condition and regulates the flow of vapor from the fuel tank to the atmosphere. The volume change compensation arrangement is a spring element that is integrated with a carbon canister cover by injection molding process.
The present invention is illustrated with reference to the accompanying drawings, throughout which reference numbers indicate corresponding parts in the various figures. These reference numbers are shown in bracket in the following description and in the table below.
Table:
Ref No: Component Ref No: Component
1 Casing 6 Second filter mesh
2 End cap 7 Volume change compensation element
3 Compression plate 8 Adsorbent material
4 Liquid trap 9 Fuel vapor inlet port
5 First filter mesh 10 Atmospheric air inlet port
Referring to figures 1 and 2, a carbon canister (100) with arrangement for compensation of change in volume of the adsorbent material bed, in the canister. hereinafter referred as “the carbon canister (100)”) is shown. The carbon canister (100) comprises a casing (1), an end cap (2), a compression plate (3) and an adsorbent material (8).
The casing (1) is filled with an adsorbent material (8), compactly held between a first filter mesh (5) and a second filter mesh (6). At one end, the casing (1) is fitted with a liquid trap (4), a fuel vapor inlet port (9) and an atmospheric air inlet port (10). The fuel vapor including a minor amount of liquid fuel enters the canister (100) through the liquid trap (4) at fuel vapor port (9), where the fuel vapor is separated from any liquid fuel. Through the first filtering mesh (5), the fuel vapor passes on to the adsorbent material (8) where it is adsorbed on the adsorbent material (8). In an embodiment, the adsorbent material is an activated charcoal. The liquid trap (4) is a small chamber that traps liquid fuel therein. The liquid trap (4) stores the condensed fuel vapors in liquid form and avoids entry of liquid fuel in carbon canister (100). The liquid fuel in the liquid trap (4) eventually evaporates and gets drawn into the adsorbent material (8). The adsorbent material (8) absorbs the fuel vapors/ hydrocarbons, preventing them from escaping into the atmosphere. The liquid trap (4) is made of plastic and its directly connected to fuel tank.
The compression plate (3) is arranged next to the second filter mesh (6). The compression plate (3) is made of a stiff plastic material forming a stable support to the second filtering mesh (6) and to the adsorbent material (8).
In an embodiment, each of the first filter mesh (5) and the second filter mesh (6) is a non-woven media having a porous fiber bonding structure. The pore size determines the size of the particles that can pass through the filter. In a preferred embodiment of the invention, the second filter mesh (6) is positioned next to the compression plate (3) and the first filter mesh (5) is disposed next to the liquid trap (4). The first filter mesh (5) and the second filter mesh (6) act as a mechanical barrier that captures dirt particles and prevents them from reaching and clogging the more delicate adsorbent material (8). Further, the first filter mesh (5) and the second filter mesh (6) block the dirt and ensure the air that enters the carbon canister (100) is clean and free of contaminants. The filtering meshes (5, 6) with micro holes allow the passage of air or gas, provide efficient and proper ventilation during adsorption and desorption of the granules while blocking larger particles from entering the canister.
The end cap (2) is fitted to the other end of the casing (1) compactly sealing the casing (2). The end cap (2) is having a volume change compensation element (7) integrated thereto. The end cap (2) is fitted to the other end of the casing (1) in a way that the volume change compensation element (7) is arranged in compressed state between the compression plate (3) and the end cap (2). The adsorbent material (8) compactly held between the first filter mesh (5) and the second filter mesh (6) is constantly in compressed condition and held stably, due to biasing force of the volume compensation element (7). In an embodiment, the volume compensation element (7) is a spring. In an embodiment, the end cap (2) with integrated volume change compensation element (7) is a single component made of plastic material, by injection molding process.
The end cap (2) helps the carbon canister operation and enables to function it properly and avoids harmful vapor leakage into the atmosphere. In a preferred embodiment of the invention, the end cap (2) with the volume compensation element (7) integrated thereto, is made of plastic of any grade such as a high-density polyethylene (HDPE) or polypropylene (PP), Polyamide 6 (PA6), Polyamide 6-6 (PA66) material. The plastic materials are selected for their durability, chemical resistance, and ability to withstand the harsh conditions within the canister.
The end cap (2) with integrated volume compensation element (7) is a single component, made by plastic injection molding process. However, it is understood that the end cap (2) with integrated volume compensation element (7) can be made by any other suitable process.
The end cap (2) seals the carbon canister in compact condition and the volume compensation element (7) integrated thereto maintains the adsorbent material (8) in compact condition even in case the canister (100) expands due to water absorption and heat.
The end cap (2) with integrated volume compensation element (7) also regulates the flow of vapor from the fuel tank to the atmosphere. When the engine is not running, the volume compensation element (7) keeps the vapor in the canister from flowing back into the fuel tank. In absence of the volume compensation element (7), the vapor containing harmful pollutants can contribute to air pollution. The end cap (2) with integrated volume compensation element (7) always keeps the bed of adsorbent material in compact condition and prevents canister performance deteriorations.
Advantages of the invention:
The bed of adsorbent material in carbon canister (100) of the present invention is maintained in compact condition during its use and prevents harmful gases releasing to the atmosphere.
The carbon canister (100) of the present invention offers simple installation and does not require special care.
No additional machine and material required to for manufacturing of the end cap (2) with volume compensation element (7).
The carbon canister (100) having an end cap (2) integrated with the volume compensation element (7) is durable, re-cyclable and relatively inexpensive.
The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the present invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the present invention and its practical application, and to thereby enable others skilled in the art to best utilize the present invention and various embodiments with various modifications as are suited to the particular use contemplated. It is understood that various omissions and substitutions of equivalents are contemplated as circumstances may suggest or render expedient, but such omissions and substitutions are intended to cover the application or implementation without departing from the scope of the claims of the present invention.
,CLAIMS:We claim:
1. A carbon canister (100) with volume change compensation arrangement, the carbon canister (100) comprising:
a casing (1) filled with an adsorbent material (8), the bed of adsorbent material (8) compactly held between a first filter mesh (5) and a second filter mesh (6), the casing (1) receiving fuel vapor and atmospheric air from one end and fitted with an end cap (2) at the other end; and
a compression plate (3) arranged between the end cap (2) and the second filter mesh (6);
characterized in that,
the end cap (2) is having a volume change compensation element (7) integrated thereto, the volume change compensation element (7) arranged in compressed state between the compression plate (3) and the end cap (2) with a biasing force acting on the compression plate (3) for compactly holding the bed of the adsorbent material (8), wherein the end cap (2) with integrated volume compensation element (7) is a single component.
2. The carbon canister (100) as claimed in claim 1, wherein the casing (1) receives fuel vapor through a liquid trap (4) at a fuel vapor port (9).
3. The carbon canister (100) as claimed in claim 1, wherein the compression plate (3) is made of a stiff plastic material forming a stable support to the second filtering mesh (6) and to the adsorbent material (8).
4. The carbon canister (100) as claimed in claim 1, wherein each of the first filter mesh (5) and the second filter mesh (6) is a non-woven media having pores
5. The carbon canister (100) as claimed in claim 1, wherein the end cap (2) with the volume compensation element (7) integrated thereto, is made of a plastic material selected from: a high-density polyethylene (HDPE), polypropylene (PP), a polyamide 6 (PA6) material and a Polyamide 6-6 (PA66) material.
6. The carbon canister (100) as claimed in claim 1, wherein the volume compensation element (7) is a spring.
7. The carbon canister (100) as claimed in claim 1, wherein the adsorbent material is activated charcoal.
8. The carbon canister (100) as claimed in claim 1, wherein the end cap (1) with integrated volume compensation element (7) is made by injection molding process.