Gasoline Vapor Recovery System

Abstract

Apparatus for preventing pollution of the atmosphere caused by passage of gasoline fumes thereto. The apparatus is operable in conjunction with a gasoline dispensing pump which connects to the fuel tank of a vehicle. Fumes from the fuel tank are conducted therefrom and introduced to the flow of liquid gasoline as the latter is withdrawn from a storage truck or the like.

Description

The present invention relates to the recovery of fuel vapors liberated in the course of dispensing a normally liquid fuel such as gasoline.

In the necessary course of supplying a fuel tank of an internal combustion engine, by a dispensing nozzle, as, for example, thru an open inlet pipe of a typical automobile, there is some release of lighter volatile fractions in the form of vapors which are displaced from the tank by the inflowing liquid fuel. While in cold weather this can be a negligible factor, in hot weather substantial quantities of vapor can be released to the atmosphere unless otherwise recovered.

Further, under particular atmospheric conditions accumulated vapors can constitute an air polluting factor. Also, even though an accumulated volume of vapors do not contribute noticeably to pollution, they could result in an explosive mixture limited to a minor area.

Motor vehicles can, as a practical matter, be provided with means to receive the displaced vapors and to recover them. The present invention however relates to that type of arrangement wherein this function of vapor recovery is affected rather in connection with a fuel dispenser.

Accordingly, therefore, the present invention contemplates the provision of means for recovering the displaced vapors during the transfer of a volatile liquid fuel, treating the vapors to re-introduce them into the incoming liquid fuel stream and then disposing of the excess air.

This is accomplished by providing a fuel dispensing nozzle which makes a seal with the inlet pipe of a fuel tank during a filling operation. The nozzle is provided with a return line to simultaneously draw off vapors displaced from the tank.

It is generally known to effect recovery of vaporized liquid fuel fractions by substantially pressuring the vapor and reintroducing it into the inflowing, relatively cool supply of fuel.

Such systems are found to operate in a satisfactory manner because of the normally existing, relatively substantial temperature differential (at warm, ambient temperatures) between the temperature at the vehicle fuel tank and the temperature in the normally underground gasoline supply or storage tank which feeds the fuel dispensing mechanism. Thus, it must be remembered that at high summer temperatures, coolant air which moves past a vehicle's radiator and engine, ultimately flows downwardly beneath the vehicle and continuously passes rearwardly into heat exchange with the fuel tank. In addition, the fuel tank is usually in close proximity to the hot exhaust system. Therefore, fuel tank temperatures of 110.degree. F. and above are not at all unusual.

In contrast, temperatures of the fuel rising from a subterranean storage tank, may typically be in the neighborhood of 60.degree. F. and below.

Therefore, substantial compression of final vapors followed by injection into the liquid stream, results in substantial absorption of the vapors.

Because the mass of liquid fuel flowing at 60.degree. F. is ordinarily large compared with the mass of recovered fluid, the cooling effect to the latter is substantial.

The present invention contemplates such a vapor recovery system in an adjunctive unit applicable to a gasoline dispensing pump having a number of important features. First, the fuel dispensing nozzle is adapted for sealing, yet releasable, engagement with the fuel tank. Furthermore, the stream of fuel which is supplied under substantial pressure to the dispensing nozzle is caused to actuate a pumping mechanism for raising the pressure of recovered vapors to a desired level. Said mechanism, at the same time, drives an air pump which continuously diffuses minute amounts of unrecovered fuel vapors to atmosphere, thus preventing accumulation of an explosive mixture. Finally, a level control chamber in the main fuel supply conduit is employed to vent excess air entering the system, without materially impairing the pressure of the main line.

To illustrate the invention by reference to one embodiment thereof, in greater detail, reference is made to the figures of the attached drawing wherein:

FIG. 1 is a perspective elevation of a fuel dispensing system embodying the present invention.

FIG. 2 is another perspective view from a somewhat different angle illustrating a variation in mounting or attachment provisions.

FIG. 3 is a flow sheet indicating diagrammatically the operation of the present device.

It is to be understood that the main fuel or gasoline supply comes via pipe 10 from a typically underground supply reservoir. A pump, meter and recording mechanism which may be more or less diagrammatically represented by reference numeral 12 in FIGS. 1 and 2 are communicated with said supply. While pump 14 (FIG. 3) may be that pump normally associated with the dispensing unit 12, it is, on the other hand, desirable to use a supplemental pump which raises the fluid pressure substantially above the pressure normally determined by the typical dispensing pump. Whereas, the latter pump normally operates at pressures in the neighborhood of 25 psi, it may be desirable, in accordance with the present invention, to employ pressure substantially in excess of this value.

Accordingly, therefore, pipe 10 appears in FIGS. 1 and 2 exiting from the unit 12 and leading into a superimposed unit 16. The latter includes a closure which contains the system more or less diagrammatically represented within the dotted line area of FIG. 3. This includes the pump 14, aforementioned, which discharges into line 18 and which, in turn, feeds a closed surge tank 20 which can be insulated or lagged as at 22.

Surge tank 20 is provided with a float valve 28 mounted on actuable arm 26 which carries float 24. Since valve 28 only opens in response to the lowering of float 24, an event caused by increasing vapor pressure or volume in surge tank 20, it functions to release any air or small remaining quantity of fuel vapor in the system to line 30, without materially affecting the line pressure in the surge tank 20. The main fuel line 32 communicates surge chamber 20 to the suction side or inlet of a mechanical power recovery engine or motor operated thereby, and represented diagrammatically as at 34. Said motor 34, in turn, discharges thru a typical dispensing hose 36 and dispensing nozzle 38 which are sealably communicated with the inlet pipe 40 of a vehicle tank.

Dispensing nozzle 38 is detachably, sealingly engaged with the tank as shown at 42 and is provided with a flexible return line 44 for carrying vapors. Line 44 is closely associated with main hose 36 as shown in FIGS. 1 and 2, being connected in juxtaposition thereto and connected to unit 16, as indicated by the solid line 46 in FIG. 3. The latter is mechanically connected to the drive shaft of compressor pump 48, which raises the pressure of fuel vapors to a predetermined, elevated value and discharges them via line 50 back into the main fuel line 18. The latter can be an injection point, alternately it can take the form of a more sophisticated absorber unit, although such a refinement is usually not necessary.

An important feature of the present invention comprises the means to utilize mechanical energy developed at the motor 34 to drive the pump 48 as indicated by the dotted line 52. It is further noted that in accordance with the present invention, driving means 34 and 52 respectively are used to actuate a second pump 54 which conveys a stream of air thru line 56 into diffusing chamber 58 which receives residual vapors from line 30.

As shown in FIG. 2, diffusing chamber 58 is preferably located in the upper portion of the unit 16, which, as shown, is thoroughly apertured as at 60 and thus open to the atmosphere. Thus, any small, residual fuel vapor is instantaneously dispersed and diluted before it can form an ignitable mixture or accumulation.

In operation, the relatively cool flow of fuel from line 10 is pumped upwardly into line 18 at a pressure of from 25 to 250 psi. Said flow, in turn, picks up the highly compressed vapors from line 50, the combined flow then passing into surge chamber 20. In the latter chamber, air separates and as it accumulates is bled thru needle valve 28 by the action of control float 24 to diffuser 58. Meanwhile, the motor 34 continuously operated by pressure thru flow line 32, keeps a constant draft of air thru the diffuser and at the same time continuously raises the pressure of the outwardly flowing vapors.

The normal temperature differential existing between the fuel supply pipe 10 and the vehicle tank, is sufficient to enable essentially complete absorption of the vapors. Thus, the need for further cooling usually is unnecessary. If, however, further cooling becomes advantageous it can be applied from an external refrigeration source, not shown, to circulate thru cooling coils 62. Also, line 50 carrying fuel vapors, can be cooled by fins or similar means 64, or, alternatively, by an appropriately spaced refrigerant coil.

Claims

We claim:

1. In a fuel dispensing system for transferring a volatile liquid fuel from a source thereof, to a closed fuel tank having an inlet opening (40), a nozzle (38), having a fuel conduit (36) depending therefrom, the latter being communicated with said fuel source, the improvement in said fuel dispensing system for recovering fuel vapors during a transfer operation, which comprises;

a. means for fluid tightly sealing said nozzle (38) with said closed fuel tank inlet opening (40),

b. a vapor release conduit (44) connected to said nozzle (38), and having an inlet communicated with said fuel tank interior when nozzle (38) is disposed in sealing engagement with inlet opening (40),

c. a surge chamber (20) connected intermediate said fuel source and said fuel tank to maintain a reservoir of liquid and vaporous fuel therein,

d. a diffuser compartment (58) communicated respectively with said surge chamber (20) to receive fuel vapors therefrom, and with a source of a diluting gas (54), whereby to form a mixture of said fuel vapors and said diluting gas prior to venting of the mixture into the atmosphere.

2. In a fuel dispensing system as defined in claim 1, including; pump means (54) having a suction inlet communicated with said source of diluting gas, and a discharge outlet (56) communicated with said surge chamber whereby to introduce said diluting gas into said surge chamber (20).

3. In a fuel dispensing system as defined in claim 1, wherein said source of diluting gas is atmospheric air.

4. In a fuel dispensing system as defined in claim 1, including; valve means (28) communicating said surge chamber (20) with said diffuser (58), to regulate passage of vapor to the latter in response to the volume of liquid fuel held within said surge chamber (20).

5. In a fuel dispensing system as defined in claim 1, including; pump means (48) communicated with said vapor release conduit (44), being operable to pump vapors from said fuel tank.

6. In a fuel dispensing system as defined in claim 1, including; conduit means (32, 36) communicating said nozzle (38) with said surge chamber (20) to carry a stream of liquid fuel to said surge chamber, and motor means (34) interposed in said conduit means (32, 36) to be drivingly actuated by said stream of liquid fuel passing therethrough.

7. In a fuel dispensing system as defined in claim 1, wherein said source of diluting gas includes; a pump (54) having suction inlet communicated with and receiving a diluting gas, and a discharge conduit (56) communicated with said diffuser (58), said respective pump means (54) and motor means (34) being drivingly connected to be mutually actuated by said flow of liquid fuel through said conduit (32, 36).

8. In a fuel dispensing system as defined in claim 7, including; pump means (48) having a suction inlet communicated with said vapor release conduit (44), and the discharge thereof communicated with said source of fuel, said pump means (48) being drivingly connected to said motor means (34) whereby to be actuated in response to passage of liquid fuel through said conduit means (32, 36).