CN101239582A - Vapor Recovery System for Vehicle Fuel Tanks - Google Patents

Abstract

A vehicle fuel tank vapor recovery system comprising a container defining at least one chamber containing an adsorbent material for adsorbing fuel from air charged with fuel vapor, the container having an inlet in communication with the upper space of the vehicle's fuel tank, a vent in communication with the atmosphere outlet and a discharge outlet in communication with the air intake of the vehicle engine, a first flow path between the inlet and the vent outlet, and a second flow path between the inlet and the discharge outlet, wherein the second flow path has a Greater flow restriction and/or dwell time in the flow path.

Description

Vapor Recovery System for Vehicle Fuel Tanks

technical field

This invention relates to a vapor recovery system for a vehicle fuel tank comprising a container containing an adsorbent material, such as carbon, for absorbing fuel from fuel vapor laden air and in particular to a vapor recovery system suitable for use without a discharge valve.

Background technique

In the upper part of the fuel tank of the vehicle, a venting air space (called the head space) is required to avoid air lock-up when the fuel tank is empty in use, when the fuel is injected into the fuel tank when the air is exhausted from the head space during the filling process, and to compensate for the The change in pressure in the headspace of evaporation and subsequent condensation as the ambient temperature changes.

However, vehicle emission standards set limits on evaporative emissions of fuel vapors from the vehicle's fuel tank and fuel system. In order to achieve these emission standards, most modern vehicles are equipped with emission and vapor recovery systems to prevent the release of fuel vapor during refueling, while the vehicle is in operation and when the vehicle is stationary, while allowing the volume of air and fuel vapor in the tank to increase with the volume of fuel. changes with changes.

As shown in Figures 1 and 2, a typical vapor recovery system consists of an adsorption vessel 1 containing activated carbon filter material 2 with an inlet 3 connected to the headspace discharge channel of the fuel tank to collect fuel vapor while allowing air to The passage is through vent 4 to atmosphere. Periodically, while the vehicle is in operation, the adsorbed fuel vapors accumulated in the container are removed by drawing air through the container through the discharge outlet 5 communicating with the air intake system of the engine, so that the desorbed fuel vapors are combusted in the engine. The desorbed hydrocarbons are delivered to the engine and burned.

The primary function of the container is to absorb vapors from the fuel system and reduce environmental pollution due to evaporative emissions from gasoline powered engines.

Typically, the vapor recovery system includes a discharge valve 6 between the vessel discharge outlet 5 and the engine. For most systems the discharge valve 6 (usually a solenoid control valve) is controlled by the ECU. The ECU periodically opens a valve to allow hydrocarbons to flow to the engine. Periodic work is required to limit the amount of hydrocarbons sent to the engine. This is extremely important for engine performance, drive function and vehicle exhaust emissions.

In order to avoid an air passage directly from the ventilation outlet to the discharge outlet, a partition wall 7 extends within the container 1 between the ventilation outlet and the discharge outlet.

In some applications, such as powered two-wheelers, mechanical valves are used instead of solenoid-controlled valves to simplify the system and reduce overall cost. In this arrangement, the valve does not provide means for hydrocarbon control during engine operation. Its function is limited to on/off operation. The valve is always open during exhaust and remains closed when the engine is stopped, restricting the flow of vapors from the vessel to the engine piping and reducing vapor emissions.

However, for low cost applications it is desirable to eliminate the need for a bleed valve.

Contents of the invention

According to the present invention there is provided a vapor recovery system for a vehicle fuel tank comprising a container defining at least one cavity containing an adsorbent material for adsorbing fuel from fuel vapor filled air, the container having an upper space for contact with the vehicle fuel tank a communicating inlet, a vent outlet communicating with atmosphere and a discharge outlet communicating with an air intake of a vehicle engine, a first flow path between the inlet and the vent outlet and a second flow path between the inlet and the discharge outlet, wherein The second flow path has a greater flow restriction and/or dwell time than the first flow path.

Due to the higher restriction and/or greater residence time of the flow path between the metalware inlet and the discharge outlet, steam preferentially flows from the vessel inlet to the vent outlet. This eliminates the need for a discharge valve associated with the discharge outlet.

In one embodiment the cross-sectional area of the first flow passage is greater than the cross-sectional area of the second flow passage. Preferably the minimum cross-sectional area of the first flow path is greater than the minimum cross-sectional area of the second flow path. Alternatively, or in addition, the sorbent material located in the second flow path has a higher restriction to the passage of air than the sorbent material located in the first flow path.

The container may be provided with a further inlet to connect to atmosphere for supplying atmosphere to said second flow path.

The container is preferably divided into first and second chambers, each of said first and second chambers having an inlet end in communication with said container inlet, said vent outlet being provided at the outlet end of said first chamber while at said The discharge outlet is provided at the outlet end of the second chamber, wherein the first flow passage including the adsorption flow passage is defined through the first chamber, while the second flow passage including the discharge flow passage is defined through the first flow passage. Two chambers are defined.

The second chamber may have at least one region of restricted cross-sectional area to provide flow restriction in the discharge flow path and at least one region of larger cross-sectional area to provide increased adsorption capacity. The second chamber can be provided with fresh air inlets in its side regions.

Description of drawings

Embodiments of the invention are now described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a schematic view of a known vapor recovery system during a cycle of container load, such as when the vehicle is not in operation.

Fig. 2 is a schematic view of the vapor recovery system of Fig. 1 during a container discharge cycle.

Fig. 3 is a schematic view of a vapor recovery system according to a first embodiment of the present invention.

Fig. 4 is a schematic view of a vapor recovery system according to a second embodiment of the present invention.

Fig. 5 is a schematic view of a vapor recovery system according to a third embodiment of the present invention.

Fig. 6 is a schematic view of a steam recovery system according to a fourth embodiment of the present invention.

Detailed ways

In a first embodiment of the invention, as shown in FIG. 3, a vehicle fuel tank vapor recovery system comprises a container 10 divided into first and second chambers 11, 12, each containing a body of adsorbent material 18. , such as activated carbon, used to absorb fuel from air filled with fuel vapor. The container 10 has an inlet 13 for connection to the headspace of the vehicle's fuel tank, a vent outlet 14 for communication with the atmosphere and a discharge outlet 12 for communication with the air intake of the vehicle's engine. The first chamber 11 defines a sorption flow path 16 between the inlet and the vent outlet while the second chamber 12 defines a discharge flow path 17 between the inlet and the discharge outlet. In the embodiment shown in Figure 3, the first chamber 11 is wider than the second chamber 12 so that the discharge flow path has a greater flow restriction than the adsorption flow path.

The discharge flow path 17 is at least twice as restrictive in flow as the sorption flow path 16 , so that steam-laden air from the headspace of the fuel tank preferably flows through the sorption flow path 16 from the inlet 13 to the vent outlet 14 .

During shutdown, the drain flow path 17 remains very clean because the sorbent material 20 absorbs very little fuel vapor from the fuel tank. When the engine is started, vapor from the container first chamber 11 flows through the sorbent material in the exhaust flow path 17 due to the vacuum created at the engine intake. In this condition, the exhaust flow path 17 acts as a delay line so the engine can warm up before the fuel vapors from the reservoir reach the engine. This improves engine performance and helps control exhaust emissions.

In a second embodiment of the invention shown in Figure 4, the second chamber 12 defining the discharge flow path 17 contains a sorbent material 20b having a greater resistance than the sorbent material 20a contained in the first chamber, To further throttle the flow of steam through the discharge flow path.

In a third embodiment shown in FIG. 5, the second chamber 12 incorporates narrower cross-sectional areas 22, 23 to provide confinement of flow in the discharge flow path, and a wider cross-sectional area of increased volume 24 therebetween. to provide a larger adsorption capacity. This improves the performance of the vapor recovery system. The large cross-sectional area 24 of the second chamber 12 increases the vapor residence time within the second chamber 24 , thus reducing the peak concentration of hydrocarbons at the discharge outlet 15 .

In a fourth embodiment shown in Figure 6, dilution means may be provided to further improve system performance. A fresh air inlet 30 is provided in the side area of the second chamber 12 to enable fresh air to be drawn into the discharge flow path 17 to further reduce the peak concentration of hydrocarbons at the discharge outlet 15 .

The vapor recovery system of the present invention can be used on simple systems, like powered two-wheelers in developing countries, to avoid the use of control valves, reduce the overall cost of the vapor recovery system and improve the reliability of the system since no movable parts.

Modifications or variations may be made to the embodiments of the invention by a person skilled in the art without departing from the scope of the invention as defined in the appended claims. While this invention has been described in conjunction with preferred embodiments, it should be understood that it is not intended to limit the invention.

Claims (8)

1, the vapor-recovery system of vehicle fuel tank, comprise and limit the container that at least one contains the chamber of sorbent material, to adsorb fuel oil from the air that is filled with fuel-steam, this container has the inlet that is communicated with the vehicle fuel tank upper space, aeration vent that is communicated with atmosphere and the exhaust outlet that is communicated with the vehicle motor air inlet, first flow passage between inlet and the aeration vent, and second flow passage between inlet and the exhaust outlet, wherein second flow passage has flow limitation and/or the dwell time bigger than first flow passage.

2, vapor-recovery system as claimed in claim 1, wherein the cross-sectional area of first flow passage is bigger than the cross-sectional area of second flow passage.

3, vapor-recovery system as claimed in claim 1, wherein the smallest cross-section area of first flow passage is bigger than the smallest cross-section area of second flow passage.

4, as the described vapor-recovery system of any aforementioned claim, the sorbent material that wherein is in second flow passage has the higher restriction for air by-pass passage than the sorbent material that is in first flow passage.

5, as the described vapor-recovery system of any aforementioned claim, wherein container is provided with another inlet to be connected to atmosphere in order to supply with atmosphere in described second flow passage.

6, as the described vapor-recovery system of any aforementioned claim, this container is separated into first and second chamber, each of described first chamber and second chamber has the arrival end that is communicated with described inlet at its first end place, described aeration vent is set at the exit end place in first chamber at the exit end place in described second chamber described exhaust outlet is set simultaneously, wherein saidly comprise that first flow passage that adsorbs path is defined described second flow passage that comprises the discharge flow path simultaneously and is defined through described second chamber through described first chamber.

7, vapor-recovery system as claimed in claim 6, wherein second chamber has the zone of the cross-sectional area of at least one restriction, so that the flow restriction in the discharge flow path to be provided, and the zone of at least one comparatively large cross-sectional area, so that the adsorption capacity of increase to be provided.

8, as claim 6 or the described vapor-recovery system of claim 7, wherein said second chamber is provided with the fresh air inlet in its side regions.

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