DE2814270A1 - Closed fuel system with vacuum assist - has filler pipe for simultaneously conducting stream of vapour from vehicle tank and supplying fuel - Google Patents

Abstract

The closed fuel system for conducting vaporisable liquid fuel from a source includes a storage tank, into a receiving fuel tank having a filler pipe, and for concurrently conducting a stream of vapour from the receiving tank to the storage tank during a fuel transfer operation, whereby to stabilise the closed system, and a fuel dispending nozzle removably connected with the tank filler pipe. A hydraulic motor has an inlet communicated with the fuel storage tank to receive a stream of liquid fuel from it and has a discharge port communicated with the dispensing nozzle. A vapour pump has an inlet port communicated with the fuel receiving tank to receive vapours displaced from it as liquid fuel enters the receiving tank, and has a discharge port communicated with the storage tank.

Description

FUEL FILLING SYSTEM

The invention relates to a fuel transfer system for transferring vaporizable, liquid fuel from a fuel tank into a fuel container and for the simultaneous transfer of vapors from the fuel tank to the Fuel tank.

When passing over a volatile liquid such as e.g.

Gasoline or another fuel of equivalent properties A storage tank is placed between the outlet pipe and the container to be filled normally an unsealed connection is made. During the transition process vapors and air contained in the container normally escape into the container unhindered The atmosphere.

Regulations are proposed by many state and local authorities or have been enacted which make it mandatory to reduce these emissions or at least to make it controllable. A regulation of this kind corresponding Procedure consists in the formation of a completely closed system between the fuel source or storage tank and the container to be filled.

Such a closed system usually includes a fuel line, a manually operable tap is arranged at the outlet end. The tap can be removed from the filler neck of the container to be filled introduce and has means for producing a sealing connection between the outlet pipe and the filler neck on the container.

In many cases the system is not closed either, but rather vented to atmosphere. If with such a arrangement Liquid is pumped, two cases can occur: If the dispensed by the system Fuel is not immediately replaced by vapors from the container to be filled, air is sucked into the system.

If, on the other hand, too much steam comes out of the tank to be filled If the container is sucked in, some of the vapors must be vented.

To create the necessary vapor-tight, but detachable connection Several advantageous sealing arrangements have already been proposed on the discharge pipe been.

One method of making the required seal is to a cylindrical sealing element with flexible walls such as a rubber shoe or Like. To connect in such a position with the tap that it is the spout completely surrounds in the filling position. When inserting the discharge pipe into the filler neck of the container to be filled with this arrangement, the walls of the flexible one Deformed, i.e. compressed and / or stretched. The shoe forms an annular vapor passage with its elastically deformable edge facing the sealing system comes against the filler neck.

Such an arrangement has proven to be highly effective in practice. When introducing fuel from the outlet pipe into the container to be filled a slight overpressure is generated in this through the fuel vapors and air be displaced from the container. These vapors pass up through the annulus between the spout and the flexible sealing element and can then via the tap and by means of a separate line to the fuel source or can be transferred to a steam collector.

The efficiency of this system depends to a large extent on the mechanical Compatibility of the vehicle with the discharge pipe, i.e. whether a faultless Sealing can be made at the contact surface.

If for any reason the edge of the sealing shoe coming into contact does not rest on the outlet pipe on the filler neck, it does not come to the formation of a Seals and a leak results or develops.

Another potential source of vapor leakage are those mentioned above Container vents on some vehicles, especially from the production years before 1971, are present. If it comes to the formation of a leak path, a Part of the steam escaping from the container will be released into the atmosphere.

Vacuum auxiliary devices are also already available for closed fuel systems has been developed, by means of which the vapor collection system under a low Negative pressure works. As a result, there is a tendency for air to be drawn into the system through any existing or emerging leakage paths. In addition, this will result in the release of steam largely prevented from entering the open atmosphere. Such vacuum auxiliary devices however, often have the disadvantage that they suck in too large amounts of air, which in turn can lead to undesirable mixture formation in the vapor space. aside from that Excessive exhaust emission may occur due to the degree of saturation the excess air that passes through the system in contact with the fuel.

The invention is therefore based on the object of a fuel transfer system to create that does not suffer from the aforementioned disadvantages and optimally to the different Operating conditions such as different throughput rates and speeds, pressures, temperatures and temperature differences in the system is adapted.

The fuel transfer system proposed to solve the problem posed of the type mentioned above is characterized according to the invention by a removable fuel tap that can be connected to a filler neck on the fuel tank, one that can be connected to the fuel tank on the inlet side when fuel is passed over can be charged with liquid fuel and on the outlet side with the fuel tap connected hydraulic motor and one that can be connected to the fuel tank on the inlet side, with displaced from this when fuel enters the fuel tank Fuel vapors that can be charged and are connected to the fuel tank on the outlet side, Steam pump coupled to the hydraulic motor in terms of drive.

The fuel transfer system proposed according to the invention is characterized is made up of, among other things, 1) a sealing connection in the connection area between the vehicle filler neck on the fuel tank and outlet pipe on the tap for all suitably equipped Vehicles, 2) a vacuum auxiliary device, which in vehicles, their fuel tanks are not sealingly connectable, causes the collection of the vapors, and 3) a Positive displacement hydraulic motor driven by the fuel dispensed will. This hydraulic motor in turn drives a positive displacement vapor pump, see above that the volume of the amount of steam pumped in relation to the volume of the dispensed Fuel controlled and also the pumping time on the period of fuel delivery is restricted.

4) A bypass line with a valve through which the emergence from Overpressure or underpressure in the vapor space between the vehicle's fuel tank and the steam pump is limited.

According to a further embodiment, the mode of operation can be adapted of the overall system to different operating conditions parallel to the displacement steam pump a bypass line with valve can be provided through which vapors in the bypass flow can be fed to the suction side of the pump or removed from it.

The fuel transfer system proposed according to the invention is shown below explained in more detail using the exemplary embodiments shown in the drawing.

Figures 1 and 2 are schematic representations of an inventive Fuel transfer system, with different parts in both views of the system are shown in a safe manner.

Fig. 3 is a schematic representation of a second embodiment of the fuel transfer system according to the invention.

The fuel storage tank 10 shown in FIGS. 1 and 2 corresponds, for example, to the fuel tank normally found in petrol stations, which is provided with an electrically driven fuel pump 15 which Petrol or another fuel or, in general, a corresponding one, promotes volatile liquid. This fuel pump can be above ground or as shown here as a submersible pump in the fuel itself arranged be.

The fuel feed pump 15 delivers fuel via the line 33 to the inlet side of a hydraulic motor 11, which in turn has a long hose line or fuel line 12 with tap 13 with filler neck 16 on a fuel tank 14 is connectable.

When the tap 13 is inserted into the filler neck 16, a Sealing element in the form of a shoe 17 with an elastic wall is deformed and formed an annular channel or chamber 18 between itself and that within the shoe located outflow pipe 19 from.

when passing fuel through the hydraulic motor 11 to the tap 13 shows the formation of a vapor crom directed in the opposite direction supported by 4e second steam line 21 by means of a steam pump 22, which directly or, if necessary, via a corresponding power transmission through the hydraulic motor 11 is driven. Through the transfer of fuel into the fuel tank 14 the steam delivery from this container is initiated: 3.

Inlet and outlet side of the steam pump 22 are via a bypass flow or bypass line 23 connected to one another with valve. This bypass line 23 is used to adjust the steam pressure. If, for example, a perfect seal is formed by the shoe 17 and emerging from the fuel tank 14 Vapor volume exceeds the displacement capacity of the vapor pump 22 Part of the vapors are bypassed by the steam pump 22 in the bypass flow to the Limit system pressure.

On the other hand, when the vapor volume is lower than the displacement power of the vapor pump 22, one becomes sufficient high amount of steam from the The outlet to the inlet side of the vapor pump is circulated around the in the fuel tank 14 to limit the resulting negative pressure.

The fuel tank 14 to be filled normally consists of the usual fuel tank in a motor vehicle or watercraft for inclusion of the liquid fuel, the container either being hermetically sealed or is provided with a vent. Located on such a fuel tank is generally one or more filler neck 16, which has a predetermined Protrude from the container. The filler neck 16 is normally through a lid, not shown here, closed with a vent, so that only a limited amount of vapor can accumulate within the fuel tank 14.

Such a system avoids the creation of too high a Dawtpf pressure, especially at higher ambient temperatures. The filler neck 1C can be bent1 curved or, as shown here, relatively straight-lined. The fuel tank can only hold unleaded! Fuel as currently be common in many motor vehicles from ¢ biluet. The inlet end of the filler neck 16 may be provided with an edge 26 which is used to receive the engagement surface of the a ventilation cover is used.

The tap 13 corresponds to the design customary in petrol stations and allows the hand-controlled power gate delivery. He's also using an automatic Feed lock provided. The latter consists of arranged inside the tap, pressure responsive devices that control the main flow control valve 27 over the filling process of the fuel tank 14 or when it occurs higher pressure within the fuel system.

The tap 13 consists of an elongated housing 28 which is designed as a handle for convenient handling of the tap. The housing has an inner channel 31 for supplying liquid fuel the fuel line 12 in the fuel tank 14 and is also with a further inner channel 29 is provided through which the vapors from the fuel tank 14 can be fed back into the fuel tank 10.

In addition, the housing 28 has connections at its rear end for the fuel line 12 and for a steam line 21. At the front end of the housing 28 is an elongated outflow pipe 19, which is connected to the inner channel 31 is connected and is of sufficient length to be before starting a fuel dispensing process to be introduced into the filler neck 16. On the outlet pipe 19 are also means that can be brought into engagement with the filler neck, such as an outer ring or Like. Provided. As a result, the outlet pipe is inserted into the filler neck secured in this or on this in its position.

On the side of the outlet pipe 19 is located on the tap housing 28 an elongated shoe 17 with an elastic wall, for example in the form of a Bellows-shaped rubber part with walls of sufficiently high flexibility and pressure-dependent Deformability. One end of the cylindrical shoe 17 is sealed to the nozzle body 28 attached, and the other, open end has an edge flange sufficiently high Elasticity to the Sealing system against the outer surface of the Filler neck 16 can be brought.

When a perfect connection is established, the shoe forms 17 with an elastic wall an annular chamber 18 surrounding the outflow pipe 19, in which the inner channel 29 opens, so that from the fuel tank 14 into this annular chamber entering fuel vapors can be fed to the fuel tank 10.

The fuel tank exists as is usual at most petrol stations primarily from one or more underground fuel tanks 10 included in corresponding time intervals with a tank truck or corresponding supply vehicle be refilled. One electrically powered and above ground within one Petrol pump 32 or, as shown here, immersed in the fuel tank 10 Fuel feed pump 15 is on its suction side with one at the bottom of the fuel tank 10 located filter 34 or another filter device in connection. the The outlet side of the fuel feed pump 15 is connected via a fuel riser pipe 33 connected to the hydraulic motor 11, which, as mentioned, is a displacement type is that by the throughput of the fuel supplied from the fuel tank 10 is driven.

The fuel feed pump 15 is operated by a lever operated switch or a corresponding actuator which can be actuated from outside the fuel dispenser 32 controlled so that the pumping operation can be initiated at any time for a filling process can. The outlet side of the hydraulic motor 11 is via an elongated fuel line 12 is connected to the housing 28 of the tap 13.

The vapor pump 22 is on its outlet side via a line 36 with the fuel tank 10 is connected. The latter need not necessarily be underground be arranged, but can of course also be in an above ground Location. In the latter case, however, would change due to temperature fluctuations Set very high changes in vapor pressure within the fuel tank 10.

The vapor pump 22 is via a connecting shaft or a coupling 37 with the hydraulic motor 11 in connection, so that they are driven by the hydraulic motor 11 and when filling fuel into the fuel tank 14 at the same time Sucks fuel vapors and air from it.

The steam line 21 connects the inlet or suction side of the steam pump 22 with the tap 13 and is combined with the fuel line 12. the However, both lines 12 and 21 need in view of the operation of the fuel transfer system according to the invention not in the manner shown here to be arranged, but can also run separately from each other.

Under normal circumstances displaced when filling in fuel the fuel tank 14 the in this rising fuel those present in the tank Fuel fumes and buft. The fuel vapors contain a certain amount of air, depending on the ambient temperature, as well as whether the tank has a vent is provided or not, and depends on other factors.

The transferred from the fuel tank 10 to the fuel tank 14 The amount of liquid fuel is not in constant proportion to the in the fuel tank 10 transferred amount of steam.

In practice, the ratio of vapors to liquid fluctuates in Depending on the temperature and other factors within wide limits. In general however, this ratio is normally less than 1. Therefore, the fuel system must be stabilized by introducing air or dispensing fuel. the Fuel vapors escaping through the filler neck 16 enter the annular chamber 18, and pass from this into the inner channel 29 in the tap 13.

The steam pump 22 causes a forced discharge of steam the annular chamber 18, so that it is always kept under a negative pressure. Consequently favors the load on the connection between the discharge pipe and the filler neck atmospheric pressure the formation of a vapor-tight connection.

To maintain the vacuum support at the annular chamber 18 and to stabilize or balance the fuel system regardless of the amount of steam withdrawn from the fuel tank during a filling process is the Steam pump 22 is provided with a bypass line 23, which is the inlet or suction side the pump connects to its outlet or delivery side. One in this bypass line Flow control valve 38 arranged in 23 has two modes of operation.

If in the annular chamber due to very large amounts of fuel vapors If the pressure in the fuel tank 14 is very high, the valve 38a opens. Since the steam pump 22 only deliver a predetermined amount of steam due to its displacement can, excess steam flows through the valve 38a in the bypass flow the pump 22 and arrives immediately in the fuel tank 10.

So that the steam pump 22 can have a limited pressure within the Annular chamber 18 maintained, and also all of the fuel tank 14 escaping vapors included.

If, on the other hand, the steam pressure prevailing in the annular chamber 18 during a filling process with a closed or with a vent provided system falls below a predetermined minimum pressure value, the by the hydraulic motor 11 driven steam pump 22 further. Since the steam flow from the fuel tank 14 is thus lower than the displacement of the vapor pump 22, the valve 38b is opened while the valve 38a is in the closed position remains. Due to this valve actuation, vapors are released from the outlet side of the Steam pump 22 rolled back to the suction side of the pump. Again, this is the fuel system stabilized, and the negative pressure in the connection area between the outlet pipe and The filler neck is maintained.

When filling a fuel tank, the fuel transfer system is therefore practically always in balance.

In addition, a higher negative pressure can be maintained in the system. The actuation of the vapor pump 22 together with the entry of fuel into the Fuel tank 14 effectively regulates and stabilizes the entire fuel transfer system and reduces the need to maintain system balance Supply or discharge of steam into or out of the system.

In a vented fuel system, therefore, there will be vapor emissions reduced to a minimum, while in a closed system a constant State is maintained.

Technically speaking, the steam pump 22 and the hydraulic motor 11 preferably arranged close together for a simple drive connection to enable. These two units can also be in an additional housing in the field the main pump be arranged. As shown in Fig. 1, the pump and hydraulic motor existing unit also together with the existing ones Place components inside a dispenser.

In the second embodiment of the fuel transfer system shown in FIG. 3 are parts corresponding to those of the embodiment of FIGS. 1 and 2, respectively denoted by the same reference numerals, a renewed description unnecessary. In this embodiment, the hydraulic motor 11 has an elongated, cylindrical housing which forms an inner chamber 49 in which a piston 40 slidably guided back and forth and to maintain the seal the inner chamber 49 is sealed against the housing wall by a sliding seal. The piston 40 is inside via a linkage 50 with a corresponding piston 39 the steam pump 22 is drivingly connected. The chamber 49 is hydraulically sealed and allows the piston 40 to move freely depending on how further the introduction of liquid into the chamber described below.

Allow openings formed at opposite ends of the chamber 49 the introduction or delivery of liquid into or out of the chamber. These Openings are connected to a common line 43 via valves 41 and 42, which in turn is connected to the riser pipe 33 leading to the fuel tank 10.

The valves 41 and 42 are mechanically coupled to the piston 40 and are dependent on the piston position controlled. fuel is thus dependent on the position of the piston 40 by the appropriate Openings are either pumped into the chamber 49 or discharged from it.

The flow of fuel through the riser 33 drives the hydraulic motor 11 as a function of the flow rate through the fuel pump 15 pumped liquid.

The fuel flow is in each case via one of the two lines 44 and 46, both of which are connected to the fuel line 12, from the chamber 49 discharged so that through the fuel line 12 a continuous flow of fuel to the outflow pipe 19.

The amount of fuel dispensed is usually measured, where at the same time the price is displayed. The fixtures are here not shown. The measurements are carried out in the manner customary for petrol stations.

The directly into the fuel line as shown 12 introduced fuel is correspondingly replaced by further, not shown here Passing through measuring or recording devices for the throughput.

The vapor pump is located in the vapor return section of the fuel transfer system 22 mainly consists of a cylindrical housing which forms a steam chamber 47, in which a piston 39 is slidably guided back and forth.

Just as with the hydraulic motor 11, the steam pump 22 comprises a piston rod, via a corresponding seal in the pump end wall with the linkage 50 connected is. The two pistons 40 and 39 are therefore displaced relative to one another synchronized and is coordinated with the adjustment of the valves 41 and 42.

Under normal operating conditions and with a small temperature difference between the fuel in fuel tank 14 and fuel tank 10 the vapors emerging from the fuel tank 14 pass through the annular chamber 18, the inner channel 29 and the steam line 21 to a vacuum upper pressure valve 48, which is in the closed position, so that the vapors through the valve 51 in enter the steam chamber 47. In these circumstances the piston 39 will displace in the direction of the arrow, the piston 40 also shifting in this direction, so that the valve 51 is moved into the open position. Arrive on a flexitime basis those expressed by the piston 39 at the opposite end of the vapor chamber 47 and vapors exiting via line 54 through the in the open position Valve 35 through into line 56, and from there via line 36 into the Fuel tank 10.

In these circumstances it can be assumed that the dated Fuel tank 14 delivered vapor throughput in terms of volume essentially the corresponds to the amount of liquid supplied. However, these circumstances depend primarily Line from the temperature of the ambient air and the temperature of the fuel tank 10 located liquid fuel. Under certain conditions, the Filling fuel into the fuel tank 14 is practically zero Steam release from this take place, which is the case, for example, when the supplied liquid fuel is colder than that still present in the fuel tank 14 Fuel. In this case they are normally taken from the fuel tank displaced fuel vapors through contact with the relatively cold fuel liquefied, so that practically no or only a very small amount of vapor escapes the fuel tank 14 takes place.

In this case, a steam throughput through the return flow circuit To ensure the vapor pump 22 is designed in such a way that the pumped Vapors are circulated back through the steam chamber 47. The pressure on the upstream side the steam line 21 is then relatively low. The associated with the steam pump 22 Valves are then in the following position: valve 51 is open, valve 52 is closed, valve 57 is closed and valve 53 is open. As a result of the reduced pressure in the steam line 21 is the vacuum relief valve 48 in the open position. The pumped vapors therefore pass through the line 56 and the valve 48 and again into the steam chamber 47 via the valve 51.

The steam circuit including the steam pump 22 therefore rolls continuously Steam through the steam chamber 47.

Since there is a low pressure in the steam line 21, none Vapors are released via line 36 to fuel tank 10.

When the temperature of the ambient air is evaporation during fuel delivery favored by liquid fuel within the fuel tank 14, this gives Fuel tank produces a very large amount of vapor when liquid fuel enters away. Since the vapor pump 22 is a positive displacement pump, as I said, provision is made that a certain amount of steam from the steam line 21 in the bypass flow can pass directly to the fuel tank 10 past the vapor pump 22.

The vapor pump 22 will thus have such an amount of vapors released that the pump can pick up, and these vapors pass through the line 21 and the valve 51 into the steam chamber 47. The valve 57 is adjusted to the open position, so that excess amounts of steam through the lines 56 and 36 can reach the fuel tank 10 directly. The by the steam pump The amount of steam passed through 22 also passes through the valve 53 and the lines 56 and 36 to fuel tank 10.

The arrangement of Fig. 3 causes a vacuum support of the balanced fuel transfer system among three different ones Operating conditions, namely when the steam inflow from the fuel tank 14 to create a favorable vapor-liquid ratio between vapor- and liquid flow rate is sufficient, 2) when the vapor-liquid ratio is substantial is less than the value required for positive displacement vapor pump 22, and 3) when an excessive amount of vapors is emitted from the fuel tank 14 and thus a reduction in overpressure due to the direct introduction of vapors into the fuel tank 10 is required.

Claims (8)

Claims: Fuel transfer system for transferring vaporizable, liquid fuel from a fuel tank to a fuel tank and to simultaneous transfer of vapors from the fuel tank to the fuel tank, not shown by a removable filler neck (16) on the fuel tank (14) connectable fuel tap (13), one on the inlet side can be connected to the fuel tank (10) when liquid fuel is passed over Fuel can be charged and is connected on the outlet side to the fuel tap (13) Hydraulic motor (11) and one which can be connected to the fuel tank (14) on the inlet side, with displaced from this when fuel enters the fuel tank Fuel vapors which can be charged and are connected to the fuel tank (10) on the outlet side, Steam pump (22) which is drive-coupled to the hydraulic motor (11). 2. Fuel transfer system according to claim 1, characterized in that that the hydraulic motor (11) a function of the fuel flow through the hydraulic motor reciprocable first piston (40), and the steam pump (22) one which can be moved back and forth in a cylinder and is drivingly connected to the first Piston (40) connected, second piston (39). 3. fuel transfer system according to claim 1 or 2, characterized in that that the steam pump (22) via lines (23, 56) with the steam flow control through the lines connecting the fuel tank (14) to the fuel tank (10) serving valves (38, 38, 51, 52, 53, 57) is connected. 4. fuel transfer system according to claim 3, characterized in that that by means of the valves (38, 48, 51, 52, 53, 57) at least part of the the fuel tank (14) emitted vapor flow directly into the fuel tank (10) can be introduced. 5. fuel transfer system according to claim 3 or 4, characterized in that that the valves (38, 48, 51, 52, 53, 57) are located in the lines, for control of the steam flow through these lines depending on one within the System prevailing pressure state serving pressure relief valve (48). 6. Fuel transfer system according to one of claims 1-5, characterized characterized in that the valves are two in the lines, for steam flow control Valves (38a, 38b) serving in opposite directions through the lines include. 7. Fuel transfer system according to one of claims 1-6, characterized characterized in that the tap (13) is one when it is connected to the filler neck (16) of the fuel tank (14) a chamber (18) forming elastic sealing element (17). 8. fuel transfer system according to claim 7, characterized in that that the steam pump (22) is in communication on the inlet side with the chamber (18).