Fuel vapor recovery system

Abstract: The vapor recovery system, for use in a fuel dispensing arrangement, employs two coaxial hoses. The inner hose (205) includes a turbine (203) which rotates in response to fuel flowing therethrough. The outer hose includes a turbine (200) which is coupled, preferably magnetically, to the other turbine (203). Rotation of the turbine (203) in the inner hose (205) causes rotation of the turbine (200) in the outer hose. Rotation of the turbine (200) in the outer hose creates a vacuum which recovers vapors from the fuel being dispensed.

Description: The invention relates to fuel-dispensing systems, and more particularly, to an improved vapor recovery system for use in a fuel-dispensing system. Vapor recovery systems are utilized primarily in fuel dispensing systems, and particularly in consumer gasoline dispensing stations. Vapor recovery systems are intended to reduce harmful vapors which emanate from the fuel as it is dispensed into an automobile. FIG. 1 shows a fuel hose inserted into the gasoline tank of a typical automobile. As the fuel exits nozzle 102 and empties into automobile 103, vapors from the fuel tank and the fuel being dispensed emanate from around the nozzle and specifically from the area labelled 101 in FIG. 1. Typically, prior art vapor recovery systems include a gasket 104 which tends to seal off the vapor from the open atmosphere. The vapors are collected underneath gasket 104 and are pumped through additional channel 105 back to the fuel storage tank. In order to force the vapors back along additional channel 105, several techniques have been used in the prior art. The most straightforward technique is to simply rely upon the pressure created by the fuel filling the automobile's gas tank. Specifically, as the volume of fuel in the automobile's gas tank increases, less space is available for air therein. Accordingly, the air in the gas tank is forced out underneath gasket 104. This in turn forces any vapors up additional channel 105 toward the fuel storage tank (not shown). Other techniques of the prior art have utilized electro-mechanical pumps back at the fuel storage tank or elsewhere in the fuel dispensing plumbing to create a powered vacuum within additional channel 105, thereby sucking the vapors back into the fuel storage tank. Such pumps are usually bulky and expensive. For example DE-U-86 10 860.3, which is considered to be the closest prior art document, discloses apparatus for recovering vapor in a fuel dispensing system, comprising an inner hose disposed within an outer hose which carriers the fuel. The inner hose is connected to a suction pump driven by a fuel metering motor. Ideally, the power forcing the vapors back along additional channel 105 to the fuel storage tank should be proportional to the rate at which fuel is being dispensed, so that as the need for vapor recovery increases, the vacuum will get stronger. U.S. Patent No. 4 082 122 issued to McGahey on April 4, 1978, describes a system which creates a vapor recovery vacuum that is proportional to the rate at which fuel is being dispensed. Disadvantageously, however, the equipment required is bulky and a transmission is required to operate the McGahey arrangement. Another prior art attempt at overcoming the above problem is described in U.S. Patent No. 4 202 385 issued to Voelz, et al., on May 15, 1982. The Voelz arrangement describes a system which includes two parallel hoses, one for dispensing fuel and one for recovering vapors. As shown in FIG. 2 of the Voelz patent, as the gasoline flows it rotates a turbine 56 which is magnetically coupled to a blower 60 in the other hose. The magnetic coupling is arranged so that as the turbine turns, the blower turns in the opposite direction and creates a vacuum in the opposite hose. Thus, as the rate of fuel being dispensed increases, the rotation speed of blower 60 increases, and the vacuum created thereby strengthens. The arrangement of Voelz overcomes many of the problems of the prior art systems previously described herein. However, a new set of problems arise. First, it can be seen from FIG. 2 of the Voelz patent that two parallel hoses are required, making the system more bulky than desirable. Second, the turbine and blower must be permanently installed in the walls of the hose, thereby making it impractical in many present systems. Third, since the axles about which the blower and turbine rotate are installed in the walls of the hose, expensive seals will be required at the axle/hose wall interface to prevent the fuel from leaking. There are other pumps similar to that of Voelz, and all have the same problems. It would therefore be desirable to provide an arrangement whereby a vapor recovery vacuum can be created which is proportional to the rate at which gasoline is being dispensed and which is simple, quick and easy to install in an existing gasoline dispensing hose. The above problems are overcome in accordance with the present invention, which provides apparatus for recovering vapor in a fuel dispensing system, the apparatus comprising an inner hose disposed within an outer hose, : a first turbine disposed within the inner hose; a second turbine disposed outside the inner hose and inside the outer hose; and the turbines being coupled so that rotation of one of the turbines caused by fuel flowing through one of the hoses causes rotation of the other of the turbines, thereby causing vapor recovery through the other of the hoses. Such apparatus can be easily inserted into an existing fuel dispensing system, and creates a vapor recovery vacuum having a strength substantially proportional to the rate at which fluid is being dispensed. In accordance with the teachings of the invention, in a preferred embodiment a section of the hose comprises two concentric cylinders, where the inner cylinder is utilized to dispense fuel, and the space between the inner cylinder and the outer cylinder is utilized to effect vapor recovery. A turbine is disposed in the inner cylinder, which rotates as fuel flows therethrough, and such turbine is preferably magnetically coupled to a turbine disposed outside the inner cylinder and inside the outer cylinder. Rotation of the inner turbine causes rotation of the outer turbine, thereby creating a vacuum in the outer cylinder. The vacuum created in the outer cylinder recovers the vapor. Additionally, guide pipes may be installed in the inner cylinder to ensure that the fuel flowing therein is forced up against the turbine at the proper orientation to cause rotation of the turbine in the proper direction. As an optional enhancement, the magnetic coupling between the turbines may be made weak enough so that after an amount of vapor is recovered into the fuel storage tank which causes vapor pressure in the fuel storage tank to go above a predetermined value, the outer turbine will no longer be able to turn. Therefore, no more vapor will be pumped into the fuel storage tank. Accordingly, the magnetic coupling between the inner and outer turbines operates as a safety clutch which shuts off the vapor recovery pump when a predetermined amount of vapor pressure builds up inside the fuel storage tank. Brief Description of the Drawings FIG. 1 is a typical prior art fuel dispensing hose and nozzle shown dispensing fuel into a conventional automobile gas tank; FIG. 2 is a perspective cut-away view of a vapor recovery pump incorporating the concepts and teachings of the present invention; FIG. 3A is a cross-sectional view of a vapor recovery system arranged for maximum magnetic coupling; and FIG. 3B is a cross-sectional view of a vapor recovery system arranged for relatively little magnetic coupling. Detailed Description of the Preferred Embodiments FIG. 2 depicts a small section of hose incorporating the teachings of the present invention. An inner turbine 203 includes vanes 204. Turbine 203 is disposed within inner hose 205. The flow of fuel within inner hose 205 is intended to be from right to left in FIG. 2. Outer turbine 200 includes vanes 201. Both inner turbine 203 and outer turbine 200 are free to rotate about their common longitudinal axis. Additionally, the inner and outer turbines are magnetically coupled as described hereafter. The turbine 200 and 203 are prevented from sliding longitudinally by any suitable means. For example, an axle-pin type bearing or thrust bearing may be used. The outer turbine is preferably implemented with a thrust bearing. Turbine 203 may be held in place with two small "Y" shaped bearings, one at each end. Each of the three legs of the the Y may be connected to the inside of the inner cylinder, and the junction of the three legs includes a small pin against which the end of the turbine is mounted. By placing one of these Y bearings at each end, the inner turbine may be kept in place, and the outer turbine will be kept in place without any bearings, due to the magnetic force. Optional flow directors 202 are disposed within inner hose 205 and direct the flow of fuel in a direction more perpendicular to the surface of vanes 204. This permits the power from the flowing fuel to be more efficiently translated into rotation of turbine 203. In operation, fuel flows from right to left in FIG. 2. As the fuel flows past turbine 203, turbine 203 rotates, with the speed of rotation being proportional to the rate of flow of the fuel. Rotation of turbine 203 causes rotation of outer turbine 200 due to the magnetic coupling therebetween. The rotation of outer turbine 200 creates a vacuum in a direction opposite to that of the flow of fuel in inner hose 205. Specifically, as fuel flows from right to left in FIG. 2, a vacuum is created within the outer hose which pumps the vapors from left to right. The transfer of energy contained in the fuel flowing from right to left into vacuum power from left to right can be accomplished by arranging the magnetic coupling so that rotation of the inner turbine 203 causes rotation in the same direction of outer turbine. The vanes 201 on the outer turbine are arranged in the opposite direction to the vanes in the inner turbine. Thus, although both turbines 200 and 203 would rotate in the same direction, the force created by the rotation of outer turbine 200 would be opposite to the direction of fuel flow within inner hose 205. In order to more effectively transfer the kinetic energy contained in the flowing fuel to rotational movement of turbine 203, flow directors 202 are optionally installed within inner hose 205. Flow directors 202 are arranged to redirect the flow of fuel in a direction more closely perpendicular to the surface of vanes 204. It is noted that while magnetic coupling has been described, a mechanical coupling between inner turbine 203 and outer turbine 200 may be utilized by providing a linkage, through the wall of inner hose 205, between the two turbines. While such an arrangement is possible, it is not believed to be preferred since dependable and expensive sealing technology would be required in order to ensure that the opening in the inner hose 205 utilized to link turbine 203 to turbine 200 with a mechanical linkage does not leak fuel. Another optional enhancement to the invention allows the two turbines 203 and 200 to function as a safety clutch in order to prevent the vapor pressure within the fuel storage tank from increasing beyond a predetermined value. Specifically, as the vapors are pumped back into the fuel storage tank, the vapor pressure in the fuel storage tank will increase. It is desirable to not allow this vapor pressure to go beyond a predetermined value. It can be appreciated that as pressure builds up in the fuel storage tank, such pressure opposes the rotation of turbine 200, which is attempting to pump more vapor into the fuel storage tank. Accordingly, it can be arranged that the magnetic coupling between turbines 203 and 200 is weak enough so that the force created by the increased vapor pressure in the fuel storage tank inhibits turbine 200 from turning when the vapor pressure becomes too great. In effect, the magnetic coupling "breaks" when it is desirable to shut off the vapor recovery system. The vapors emanated after the maximum vapor pressure is reached are released into the atmosphere. However, when the pressure becomes great enough to break the coupling, the release of the vapors into the atmosphere is safer than building up too great a pressure within the fuel storage tank. While calculations will yield the appropriate magnetic strength, it is believed that experimentation should also be carried out in order to more accurately determine the pressure at which the magnetic coupling breaks. More particularly, the arrangement in FIG. 2 can be installed in any experimental fuel delivery system. The pressure in the fuel storage tank can then be increased until turning of the inner turbine 203 will no longer turn the outer turbine 200. The magnetic force coupling the two turbines can then be varied until the proper strength of the magnetic coupling for a particular system is determined. It should be emphasized that such a safety clutch would only be triggered in the most extreme of circumstances. Most fuel storage tanks include pressure vents to preclude the pressure from building up too high, and therefore, the magnetic safety clutch would only operate upon the failure of such pressure vents. The magnets coupling turbines 200 and 203 may be movable to various different positions thereby creating stronger or weaker magnetic coupling as needed. For example, the magnets can be installed on the surfaces of turbines 200 and 203 so that their relative positions may be varied. When they are aligned exactly, coupling therebetween is the strongest and as they are moved apart, such coupling gets weaker. Such a system is shown in FIGS. 3A and 3B. The hoses and vanes of the turbines have been omitted for purposes of illustration and clarity. Magnets 301 and 302 are installed in the turbines 200 and 203, respectively. Such magnets may be installed directly on the surface of the turbines, may be imbedded within the turbines or may be mounted using any other suitable technique. FIG. 3A shows the magnets being aligned longitudinally for a relatively strong magnetic coupling, while FIG. 3B shows the magnets longitudinally displaced from one another for relatively weak magnetic coupling. It should also be noted that the turbines 200 and 203 may slide longitudinally, relative to each other, rather than moving the magnets to vary the strength of the coupling. Such longitudinal repositioning of the turbines can be accomplished by moving whatever means are utilized to prevent longitudinal movement of the turbines. Normally, the consumer will not adjust the magnetic coupling, but the manufacturer will. The preferred embodiment is fixed position turbines. It may also be desirable to install a check valve on the fuel storage tank where the vapors enter said tank. This results in a situation whereby if the vapor recovery pump stops pumping vapor due to an unexpected failure, the vapor will not leak out of the fuel storage tank through the vapor recovery paths. However, if other check valves are utilized in the system the vapor recovery system may not need one. Returning now to FIG. 2, it is noted that couplings 207 and 208 may be designed to mate with the standard fuel dispensing hose couplings. The entire device in FIG. 2 can then be serially inserted into an existing coaxial fuel dispensing hose without redesigning any of the system. This is an added convenience not found in any prior art products. The vanes on the turbine may be arranged at various angles, contours and orientations, and such turbines may be made of any suitable material. Moreover, the vanes may be installed on the inner or outer wall of the turbines. The outer hose may be used for fuel and the inner hose for vapor recovery, rather than vice-versa as described herein. The device may be disposed anywhere along the fuel-dispensing hose, although it is preferable to install away from the nozzle so that it doesn't make the nozzle more bulky for the consumer to handle.

Claims: Apparatus for recovering vapor in a fuel dispensing system, the apparatus comprising an inner hose (205) disposed within an outer hose, a first turbine (203) disposed within the inner hose (205); a second turbine (200) disposed outside the inner hose (205) and inside the outer hose; and the turbines (200,203) being coupled so that rotation of one of the turbines caused by fuel flowing through one of the hoses causes rotation of the other of the turbines, thereby causing vapor recovery through the other of the hoses. Apparatus according to claim 1, wherein the inner hose (205) is to carry the fuel and the outer hose is to carry the vapor. Apparatus according to claim 1 or 2, wherein the turbines (200,203) are arranged as coaxial cylinders and the hoses are arranged as coaxial cylinders. Apparatus according to any preceding claim, wherein each turbine (200/203) includes a plurality of vanes (201/204) therearound. Apparatus according to any preceding claim, having at its ends couplings (207,208) for mating with standard fuel dispenser couplings. Apparatus according to any of claims 1 to 5, wherein the turbines (200,203) are magnetically coupled. Apparatus according to claim 6, wherein each turbine (200/203) includes at least one magnet (301/302) thereon, and wherein the magnets (301,302) or turbines (200,203) are relatively movable in such a manner that the magnetic coupling may be varied. Apparatus according to any of claims 1 to 5, wherein the turbines are mechanically coupled. Apparatus according to any preceding claim, including a plurality of flow directors (202) for directing the flow of fuel in the fuel-carrying hose at a predetermined angle with respect to the fuel-driven turbine. Apparatus according to any preceding claim, wherein the turbines (200,203) are coupled with a force sufficiently weak that, when rotation of the vapor-driving turbine (200) is opposed by a predetermined amount of vapor pressure built up during recovery of vapors, the coupling is broken and the said turbine (200) no longer rotates as a result of rotation of the other turbine (203).

Inventors: PYLE JAMES H, SIMPSON W DWAIN, PYLE, JAMES H., SIMPSON, W. DWAIN
Applicants: SABER EQUIPMENT CORP, SABER EQUIPMENT CORPORATION
Application year: 1992
Main classification: B67D5
IPC codes: F04D25, B67D7