US20040069366A1

US20040069366A1 - Fuel dispensing device with vapour extraction

Info

Publication number: US20040069366A1
Application number: US10/432,192
Authority: US
Inventors: Andre Van Coillie; Ferdinand Nijhof
Original assignee: Centrivac International Bv
Current assignee: Centrivac International Bv
Priority date: 2000-11-21
Filing date: 2001-10-25
Publication date: 2004-04-15
Also published as: CN1482996A; NO20032301L; WO2002042200A1; EP1335877A1; AU2002214409A1; CA2429488A1; JP2004520234A; RU2003118433A; NL1016670C1; NO20032301D0; BR0115521A; MXPA03004501A

Abstract

The invention relates to a method and device for extracting fuel vapour displaced during the simultaneous operation of at least two fuel-dispensing units using a gas pump device. Each fuel-dispensing unit comprises a vapour extraction conduit in which a control valve is arranged. The different vapour extraction conduits are connected to a single gas pump device. The underpressure to be created by the gas pump device and essential for discharge of the correct quantity of vapour is determined, whereafter the control valves are adjusted such that they each allow through the correct quantity of vapour at the specific underpressure.

Description

The invention relates to a method for extracting fuel vapour displaced during the simultaneous operation of at least two fuel-dispensing units using a gas pump device.

In accordance with national and international regulations for limiting environmental pollution, fuel-dispensing devices such as fuel pumps must be provided with a vapour extraction. During filling of the fuel tank of a vehicle the fuel vapour present in this tank is displaced by the fuel carried into the tank. This displaced vapour must be discharged and fed back to the fuel supply tank of the petrol station. The same amount of fuel is discharged from this supply tank as vapour is displaced from the vehicle tank, so that the vapour displaced from the vehicle fuel tank can be readily taken up in the fuel supply tank. When the fuel supply tank is refilled, the displaced vapour is received in similar manner in the fuel tank of the tank truck, which in turn carries this vapour to a fuel depot, where a device is available for processing this vapour. A closed system is thus obtained wherein little or no fuel vapour enters the environment.

In the known fuel-dispensing devices a gas pump is present which extracts the fuel vapour displaced from the vehicle fuel tank and pumps it to the fuel supply tank of the filling station. Because there is an open connection between the extraction conduit and the vehicle fuel tank at the position of the filling opening thereof, the extraction flow rate of the fuel vapour must be precisely adjusted to the flow rate of the fuel being pumped by the dispensing unit into the vehicle tank. In order to achieve this each fuel-dispensing device is provided in the vapour extraction conduit with a gas pump and a control valve. This control valve is set such that the correct quantity of vapour is extracted. The control apparatus comprises for this purpose a memory in which is stored the characteristic of the relation between the position of the control valve and the extracted vapour flow rate.

Devices are known per se with which fuel can be dispensed simultaneously with two fuel-dispensing units. There is then usually also a choice between different types of fuel. These devices are usually designated as multi-product dispensers (MPD). In order to obtain a good extraction of fuel vapours, also when fuel is being dispensed simultaneously with for instance two fuel-dispensing devices, each unit is provided in the prior art with its own gas pump and control valve which is controlled in the above stated manner. The dispensing of fuel on the one “side” then does not influence the extraction on the other “side”. Such a multiple embodiment of the vapour discharge entails a relatively high cost of the fuel-dispensing device.

The invention has for its object to provide a method for extracting the fuel vapour displaced during the simultaneous operation of at least two fuel units using a gas pump device, which method can be performed with a fuel-dispensing device which can be manufactured at lower cost;

This object is achieved according to the invention by applying the method according to the invention as characterized in claim 1. Only one gas pump device is hereby required, even when fuel is being dispensed simultaneously from a plurality of fuel-dispensing units.

When fuel is dispensed simultaneously by a plurality of fuel-dispensing units, the pump device will have to transport more vapour. By applying the method according to the invention a specific underpressure is created by the pump device. The control valve of each fuel-dispensing unit is adjusted such that the correct quantity of vapour, corresponding with the quantity of fuel dispensed by the relevant fuel-dispensing unit, is extracted at the specific underpressure. For this purpose the valve characteristics of each control valve are determined at the specific underpressure.

According to a preferred embodiment of the invention the pump device is controlled such that the specific underpressure is created on the suction side substantially irrespective of the extracted flow rate. The valve characteristic therefore need simply contain only the relation between the valve position and the vapour flow rate allowed through at this specific underpressure. Operation of the control valve is therefore simple.

The method according to claim 3 is preferably applied herein. In order to create the specific underpressure irrespective of the extracted flow rate, a feedback valve is controlled which is received in a feedback line connected to the suction and discharge side of a gas pump of the pump device. The control of this feedback valve takes place such that an underpressure measured on the suction side of the gas pump is held constant.

A suitable further embodiment is characterized in claim 4. Although the control of the control valves is more complicated, a separate feedback valve with associated control is unnecessary in this embodiment.

The invention likewise relates to and provides a device for simultaneous multiple dispensing of fuel as described in claim 5.

Further advantages and features of the invention will become apparent from the following description with reference to the annexed figures of several embodiments. [0012]
FIG. 1 shows a schematic representation of a first embodiment. [0013]
FIG. 2 shows a schematic representation of a second embodiment. [0014]
FIG. 3 shows a cross-section through a part of the pump device according to a third embodiment.[0015]
FIG. 1 shows a first embodiment of the device [0016] 1 for simultaneous multiple dispensing of fuel. The device comprises three double dispensing units 2. Each double dispensing unit 2 can simultaneously dispense a particular fuel, in this case for instance petrol with a low octane number, petrol with a high octane number and unleaded petrol, by means of two dispensing nozzles 3. One of the three dispensing nozzles available is therefore chosen in each case on either side of the double dispensing unit 2.
In a manner which is further per se known and therefore not shown, fuel is carried from a fuel supply reservoir [0017] 6 to the relevant dispensing nozzle 3, from where it is carried into the fuel tank of a vehicle.
Each fuel nozzle [0018] 3 is provided with a vapour conduit 4 which debouches close to the outlet opening of nozzle 3. The fuel vapour displaced from the fuel tank of the vehicle is extracted via this vapour conduit 4. The vapour conduit can be received in the usual manner in the hose which supplies fuel to the nozzle.
Vapour conduit [0019] 4 comprises a valve 5 which is closed when the associated fuel nozzle. 5 is not being used.
Each vapour conduit [0020] 4 is connected to a collector line 9 or 10. Each collector line is situated on one side of the device so that during simultaneous multiple dispensing of fuel with device 1 both collector lines 9, 10 are in use for extraction of vapour. A control valve 11, 12 is received in each collector line 9 and 10. Together with their outlets, the control valves 11, 12 are connected to vapour extraction conduit 7. Accommodated in this vapour extraction conduit is a gas pump device 8 which can draw in gas from the vapour extraction conduit and transport it to supply reservoir 6.
Present for each dispensing nozzle in each of the [0021] dispensing units 2 is a sensor which measures the dispensed fuel flow rate. These sensors are connected via signal lines 15 to control apparatus 16, and more particularly to the counter computer 17 thereof. This counter computer 17 processes the measurement signals in the usual manner such that the dispensed quantity of fuel can be shown on connected counters, optionally simultaneously with the cost associated therewith.
[0022] Counter computer 17 is embodied such that it feeds the flow rate signal for each of the sides of device 1 via signal line 19 to control device 18 of control apparatus 16. Via lines 19 these flow rate signals are fed on the one hand to an AND-port 20 and on the other to a so-called chopper to be further described. Control device 18 further comprises two memories. A first memory 22, which includes a valve characteristic of valves 11 and 12 to be described further, and a second memory 21 which includes a characteristic of gas pump device 8. The quantity of fuel dispensed on both sides of device 1 is therefore totalled in AND-port 20. This totalled quantity of fuel is fed to a part of control device 18 comprising memory 21. The pump characteristic held in this memory concerns the relation between the underpressure on the suction side of pump 8 and the extracted vapour flow rate. As is known, the underpressure on the suction side of gas pump device 8 will decrease as more gas must be extracted by the gas pump device. This relation between the underpressure and the extracted quantity of vapour, which is characteristic for the specific pump 8, is predefined and stored in memory 21.
In [0023] control device 18 is now determined by means of the characteristic in the second memory 21 what the underpressure in conduit 7 will be during the extraction of a quantity of vapour equal to the quantity of fuel supplied. This underpressure signal is fed to the first memory 22 comprising a characteristic of valves 11 and 12. This characteristic concerns the relation between the valve position, the underpressure and the vapour flow rate allowed through. The underpressure which will be set is determined on the basis of the pump characteristic in the second memory 21 and the vapour flow rate for the relevant dispensing unit is likewise fed to the first memory 22. The valve position to be applied at the momentary flow rate and the underpressure follows from the valve characteristic in memory 22. A control signal for this valve position is fed to the relevant control valve 11 or 12 via control line 24.
[0024] Chopper 23 ensures that the flow rates associated with the relevant valves are fed alternatingly to the first memory 22 and the determined control signal is fed simultaneously to the relevant control valve 11 or 12. This takes place using a suitable alternating frequency such that valves 11 and 12 are operated quasi-continuously.
When the dispensed quantity of fuel changes on one or both sides of device [0025] 1, the position of the two control valves 11, 12 is adjusted by control apparatus 16, so that the correct quantity of vapour continues to be discharged for the sides in question. When the fuel dispensing is for instance stopped on the side of device 1 in which control valve 11 is arranged, the quantity of vapour to be extracted is limited to the quantity corresponding with the quantity of fuel dispensed on the other side. The underpressure in extraction conduit 7 will hereby increase and control valve 12 must be controlled in closing direction so as to still allow passage of the same flow rate.
FIG. 2 shows a [0026] second embodiment 31 of the device for simultaneous multiple dispensing of fuel. The device comprises three double dispensing units 32. Each double dispensing unit 32 can simultaneously dispense a particular fuel by means of two dispensing nozzles 33.
Each [0027] fuel nozzle 33 is provided with a vapour conduit 34 which debouches close to the outlet opening of nozzle 33. The fuel vapour displaced from the fuel tank of the vehicle is extracted via this vapour conduit 34 and finally enters fuel supply reservoir 36.
[0028] Vapour conduit 34 comprises a valve 35 which is closed when the associated fuel nozzle 33 is not being used.
Each [0029] vapour conduit 34 is connected to a collector line 39 or 40. Each collector line is situated on one side of the device so that during simultaneous multiple dispensing of fuel using device 31 both the collector lines 39, 40 are in use for extracting vapour. A control valve 41, 42 is arranged in each collector line 39, 40. Together with their outlets, the control valves 41, 42 are connected to vapour extraction conduit 37. Vapour extraction conduit 37 is connected to the suction side of pump device 43. A gas pump 38, a feedback control valve 44 and a pressure measuring device, 45 are arranged in this pump device. Gas pump 38 can draw in gas from the vapour extraction conduit and transport it to supply tank 36. The pressure measuring device 45 is connected to the suction side of pump device 43 and measures the underpressure in vapour extraction conduit 37. The feedback control valve 44 is connected to the suction and discharge side of gas pump 38. Through feedback control valve 44 gas can flow back from the discharge side of gas pump 38 to the suction side.
Present for each dispensing nozzle in each of the dispensing [0030] units 32 is a sensor which measures the dispensed fuel flow rate. These sensors are connected via signal lines 46 to control apparatus 47, and more particularly to counter computer 48 thereof. This counter computer 48 processes the measurement signals in usual manner, and forms the first measuring unit.
The [0031] counter computer 48 is embodied such that it feeds the flow rate signal for each of the sides of device 31 via signal line 49 to a control device 50 of control apparatus 47. Control device 50 comprises a memory 54 which contains the valve characteristic of valves 41 and 42 at the determined specific underpressure. This characteristic concerns the relation between the valve position and the vapour flow rate allowed through. After processing of this information from memory 54, a control signal results for each control valve 41, 42 which determines a position for the relevant control valve in accordance with the required extraction flow rate. This control signal is fed to the relevant valve 41 or 42 via a chopper 52 and control line 53.
[0032] Chopper 52 ensures that the flow rates associated with the relevant valves are fed alternatingly to memory unit 22 and the determined control signal is fed simultaneously to valve 41 or 42. This takes place using a suitable alternating frequency such that valves 41 and 42 are operated quasi-continuously.
[0033] Gas pump 38 has a pump capacity which is sufficient to process the quantity of vapour for extraction at the total maximal flow rate of the fuel-dispensing device. At an underpressure set at 200 mbar the gas pump can for instance extract a quantity of vapour at a combined maximum flow rate of the two fuel nozzles 33 of for instance 2×45 l/min.
The [0034] pressure measuring device 45 measures the underpressure at the intake of gas pump 38. In control unit 50 this measurement signal is compared to a reference signal stored in memory 54. The difference signal is used to control the control valve 44 such that the difference tends toward 0. A fixed underpressure can thus be set at the intake of gas pump 38 using the choice of reference signal.
When the underpressure is too high, the position of [0035] control valve 44 is changed such that the underpressure decreases, and vice versa.
When the dispensed quantity of fuel changes on one or both sides of [0036] device 31, the position of the relevant valve 41 and/or 42 is adjusted by control apparatus 47, so that for the side in question the correct quantity of vapour continues to be discharged. When the fuel dispensing is stopped, for instance on the side of device 1 in which control valve 41 is arranged, the quantity of vapour for extraction is limited to the quantity corresponding to the quantity of fuel dispensed on the other side. In order to maintain the underpressure at the determined specific value, the setting of feedback control valve 44 is modified such that the specific underpressure is reset. The control valve 41 is closed. There is no change for control valve 42.
The pump device can be embodied with a mechanical pressure measuring device and control valve instead of with an electronic control apparatus. [0037]
FIG. 3 shows such a mechanical control apparatus in cross-section. [0038] Assembly 61 comprises a two- part housing 62, 63 with a space divided into two chambers 64, 65. The chambers are separated by a membrane 66. Chamber 64 is connected to both the suction side 67 and discharge side 68 of a gas pump 69. The underpressure created by the gas pump prevails in this chamber 64. In accordance with this underpressure the membrane 66 will make chamber 64 smaller or larger. Membrane 66 is arranged for this purpose between two spring means 70, 71 arranged on both sides of membrane 66 in the two chambers 64 and 65. Spring means 70 comprise a spring 72 arranged between two spring cups 73 and 74. Cup 73 is connected to membrane 66. Cup 74 engages on an adjusting screw 75 which protrudes outward through housing part 63. The adjusting screw 75 can be tightened, whereby spring means 70 and 71 are compressed and the rest position of the membrane is changed.
Using the adjusting screw [0039] 75 a pre-determined specific value can be set for the underpressure in accordance with the function of the pump device as described above.
[0040] Membrane 66 is connected to an end of a lever 76 which is mounted on a protruding arm 77 screwed fixedly into housing part 62. The other end of the lever is connected to a valve member embodied as slide 78. This slide 78 is placed over a tube stub 79 connected to the discharge side 68 of gas pump 69. Tube stub 79 is provided with openings 80 which connect chamber 64 to the discharge side 68 of gas pump 69. Openings 80 and chamber 64 form the feedback conduit. Slide 78 forms the feedback control valve, which opens the feedback conduit to a greater or lesser degree by closing the openings 80 to a greater or lesser degree.
When the underpressure on the suction side becomes too strong, [0041] membrane 66 will move to the left as seen in FIG. 3. Via lever 76 the slide 78 is then moved to the right as seen in FIG. 3, whereby the openings 80 are opened further. More gas will hereby flow from discharge side 68 of gas pump 69 to the suction side 67, whereby the underpressure becomes less strong. When an underpressure is too low, the reverse action occurs, whereby the underpressure is strengthened once again. A substantially constant underpressure is thus maintained on the suction side of gas pump 69, irrespective of the quantity of vapour extracted.
The advantage of this control apparatus and of the apparatus shown in FIG. 2 is that changes in the capacity of the gas pump occurring in the course of time due to for instance wear or fouling are compensated, since the specific underpressure is nevertheless maintained by the control apparatus. [0042]
The mechanical embodiment of FIG. 3 moreover has the advantage of a relatively low cost price. [0043]

Claims

1. Method for extracting fuel vapour displaced during the simultaneous operation of at least two fuel-dispensing units using a gas pump device, comprising of providing a vapour extraction conduit for each fuel-dispensing unit which are each provided with a control valve and are together connected to a suction side of the gas pump device, and further comprising of

measuring the individual fuel flow rate dispensed by each fuel-dispensing unit,

having the pump device create a specific underpressure on the suction side of the pump device, wherein a vapour flow rate substantially equal to the total of the individual fuel flow rates is pumped away,

predetermining a valve characteristic for each control valve of the relation between the valve position and the vapour flow rate allowed through at least at the specific underpressure,

determining on the basis of the valve characteristic for each control valve the valve position at the specific underpressure and the individual fuel flow rate of the fuel-dispensing unit with which the relevant control valve is associated, and

adjusting each control valve to the determined valve position.

2. Method as claimed in claim 1, wherein the pump device is controlled such that the specific underpressure is created on the suction side substantially irrespective of the extracted flow rate.

3. Method as claimed in claim 2, wherein the pump device comprises a gas pump with a suction and discharge side, a feedback conduit provided with a feedback valve and connected to the suction and discharge side, and a pressure measuring device connected to the suction side, and further comprising of

measuring the underpressure on the suction side during operation, and

adjusting the feedback valve such that the specific underpressure is substantially maintained.

4. Method as claimed in claim 1, further comprising of

predetermining a pump characteristic of the relation between different underpressures on the suction side and the extracted vapour flow rate,

wherein the determined valve characteristic comprises the relation between the valve position, the vapour flow rate allowed through and the different underpressures, and

wherein for the specific underpressure the underpressure is taken on the basis of the gas pump characteristic at a vapour flow rate equal to the total of the individual fuel flow rates.

5. Device for simultaneous multiple dispensing of fuel, comprising a number of fuel-dispensing units which each comprise a fuel conduit and a dispensing nozzle connected to the fuel conduit, wherein a fuel pump is arranged in the fuel conduit, a collector line for displaced vapour connected to each dispensing nozzle, in each of which lines is received a control valve, a pump device which is connected on a suction side to the collector lines and which can create a specific underpressure on the suction side, and a control apparatus comprising

a first measuring unit for measuring the fuel flow rates dispensed with each fuel-dispensing unit,

a first memory containing a valve characteristic for each valve of the relation between the valve position and the vapour flow rate allowed through at least at a specific underpressure, and

a first control unit which on the basis of the valve characteristic for each valve can determine the valve position at the specific underpressure and the individual fuel flow rate of the fuel-dispensing unit with which the relevant valve is associated, and can adjust each valve to this determined valve position.

6. Device as claimed in claim 5, characterized in that the pump device comprises gas pump and wherein the first memory contains a valve characteristic for each valve of the relation between a valve position, an underpressure and a vapour flow rate allowed through, and the control apparatus further comprises

a second memory containing a pump characteristic of the relation between the underpressure on the suction side and the extracted vapour flow rate,

a second control unit which on the basis of the pump characteristic can determine the underpressure on the suction side of the gas pump at a vapour flow rate equal to the total of the individual fuel flow rates.

7. Device as claimed in claim 5, characterized in that the pump device comprises a gas pump, a feedback device connected to the suction and discharge side of the gas pump and a pressure measuring device connected to the suction side of the gas pump.

8. Device as claimed in claim 7, characterized in that the feedback device comprises a feedback conduit and a feedback control valve, and the memory also contains a determined specific value for the underpressure, and the control apparatus further comprises

a second measuring unit for measuring the underpressure,

a second control unit which can determine a setting for the feedback control valve such that the specific underpressure can be maintained.

9. Device as claimed in claim 7, characterized in that the feedback device comprises a feedback conduit and a feedback control valve, and the pressure measuring device comprises at least two chambers separated by a membrane, wherein one chamber is connected to the suction side of the gas pump and the feedback conduit such that the underpressure on the suction side can be determined with the position of the membrane, and that the membrane is connected by means of a lever to the feedback control valve to enable adjustment of the feedback control valve so that the specific underpressure can be maintained.

10. Control apparatus evidently intended for a device as claimed in claims 5-9.