[0001] The invention relates to a pumping device for several different, relatively volatile
vehicle fuels. Such a pumping device is generally known as multiproduct dispenser
(MPD) and contains generally 2, 3 or 4 pumping units, one per product. Examples of
these products are leadfree petrol, normal petrol, super petrol and diesel. Generally
each of the pump units feeds two dispensing nozzles.
[0002] The object of the invention is to improve a pumping device of this kind by applying
teachings known from Dutch patent application 9 401 455. This last mentioned publication
shows a pumping device for relatively volatile vehicle of fuel for a single product
dispenser.
[0003] This object is achieved with the pumping device as characterized in claim 1. By using
only one gas pump and several hydrodynamic fuel pumps, a very economic device is obtained,
having only a few moving parts. Furthermore, the device according to the invention
uses only a limited amount of energy for operation and is inherently very robust.
Therefore the costs of investments and also of operation of a multiproduct dispenser
according the invention are markedly reduced relative to the prior art devices.
[0004] As with a pumping device according to the invention at most two discharge nozzles
are used at the same time, the pumping capacity of the gas pump can be limited to
that maximum use. The gas pump will be of the same capacity as a single product dispenser
with two dispensing nozzles.
[0005] A further favourable development of the pumping device according to the invention
is characterized in claim 2. By using only one electric motor the manufacturing costs
of the pumping device are very limited. As the work needed to run a hydrodynamic pump,
more specifically a centrifugal pump depends on the delivered flow rate, the fluid
pumps of the pump units not discharging fuel are in fact idling and do not take up
more energy than to overcome friction losses. Therefore the power of the electric
motor used according to this preferred embodiment is only slightly higher than the
electric motor that would be necessary for driving one fuel pump.
[0006] A favourable embodiment of the pumping device according to the invention is characterized
in claim 3.
[0007] For easy maintenance the characterizing feature of claim 4 is preferably applied.
In case of malfunction of one the fuel pumps it can easily be replaced by a corresponding
pump without fully disassembling the pumping device.
[0008] Proper control of the operation of the pumping device according to the invention
is obtained with the characterizing features of claim 6. When starting the pumping
device the gas pump will raise the fluid level in each of the pump housings to the
required level and, as soon as this level is attained in each of the pump housings,
the suction is shut off by the vacuum shut off valve. Should level drop i.e. due to
air being sucked in, or due to degassing action, the vacuum shut off valve is momentarily
opened, to bring the level again at the required position.
[0009] Should the fluid level drop too low, the discharge valve is closed, so as to prevent
that gas is discharged with the fuel.
[0010] A further improvement is characterized in claim 7. When it takes too much time to
bring the level of the fuel in the pump housing to the required position, apparently
too much gas is being sucked in or some other malfunction occurs, which calls for
shutting off the discharge.
[0011] The invention will be further illustrated in the following description of several
embodiments of pumping devices according to the invention shown in the accompanying
drawings.
- Fig. 1-4
- show schematic views of a pumping device according to the invention, in which the
hydrodynamic fuel pump is embodied as a cartridge.
- Fig. 5-8
- show in schematic views an embodiment with a separate pump housing and fuel pumps.
- Fig. 9-10
- show schematically hydrodynamic fuel pumps of an embodiment of the pumping device
according the invention, in which these pumps are assembled as one unit.
[0012] The pump cartridge 1 becomes a simple centrifugal pump with, for instance, a diameter
of 100 mm if it is a three stage pump. A two stage pump would need a diameter 130
mm. The pump cartridges 1 can easily be exchanged if necessary.
[0013] The total size of the four pumps can be reduced to a space of only 480 x 310 x 280
mm so that the dispenser becomes considerably smaller than the prior art.
[0014] As mentioned before, the four centrifugal pumps are driven with one motor 2, on one
side of which a vacuum pump 3 is mounted and on the other shaft side 4 the pulley
(not shown) to drive the four centrifugal fuel pumps is mounted.
[0015] If vapour recovery is desired, the vacuum pump 3 will be chosen such that it has
a sufficient capacity to provide for degassing and for vapour recovery.
[0016] The pump housing 5 has an intake 6 which is connected to a supply of a specific fuel.
[0017] The fuel pump 1 has a fuel inlet 7 that draws in fuel from the interior of the pump
housing 5.
[0018] A pressure outlet of the pump 1 is connected to a discharge 8 which leads to a dispenser
nozzle via a flow meter.
[0019] Fig. 4 shows the arrangement of the driving gear for the pumping device. The motor
2 drives a double pulley 10 which drivingly engages pulleys 11 and 12 by means of
the V-belts. Each of the pulleys 11 and 12 is connected with a gear that is in meshing
engagement with gears 13 on the shafts of the pump cartridges.
[0020] In the embodiment of fig. 5-8 the centrifugal pump 15 is separated from the degasser
or pump housing which allows a very economic degasser design.
[0021] A non return valve 17 prevents the liquid to flow back to the underground reservoir,
as soon as the pump is switched off. This non return valve is not really necessary.
Two electric valves 25 and 26 in figure 8 close when the motor stops running, making
any flow back of the liquid impossible and keeping at the same time the pump under
underpressure. The vertical shaft position of motor 18 and centrifugal pumps 15 and
the relative positioning of the components as shown in fig. 5, result in a two stage
centrifugal pump having its shaft sealings exposed to the suction side in a favourable
manner. This has the advantage that the pressure drop over the shaft sealings is never
higher than about 0,5 bar and enables the use of simple lip seals. The pressure side
of the pump has no shaft sealings.
[0022] The central motor 18 as shown in fig. 8 drives the, in this case four centrigufal
pumps 15 by a set of gear wheels indicated in fig. 6 with one side of its shaft 21
while with the other shaft extremity 22 a vacuum pump is driven. It will be clear
that instead of 4 pumping units also 3 or 2 pumping units can be used.
[0023] At the moment that a dispensing nozzle is lifted out of the nozzle boot the motor
18 starts to run driving the vacuum pump and the 4 centrifugal pumps 15. The centrifugal
pumps 15 do not have to deliver immediately liquid because it takes a few seconds
before the nozzle is taken to the tank of the vehicle and opened.
[0024] The vacuum pomp however creates immediately an underpressure in the suction pipes
23 with which it is connected to the four pump housings.
[0025] If the level of the liquid in the four pump housings is on its highest, the float
switches by means of their upper read relay keep the four electric vacuum shut off
valves 25 closed and the vacuum pump evacuates only the gas in the suction pipes 23.
[0026] If, however, the level in one or more of the pump housings is lower than maximum,
but higher then its minimum, the upper read relay of the corresponding float switch
24 deactivates the electric vacuum shut off valve 25 which opens and enable the vacuum
pump to restore the level of the liquid at its maximum value by evacuating the gas
on top of the liquid in the corresponding pump housing.
[0027] If the level in one or more of pump housings was reaching its minimum (empty underground
reservoir, excessive degassing, leak etc.) the lower read relay of the corresponding
float switch 24 closes the corresponding electric discharge shut off valve 6 in the
discharge pipe of the centrifugal pump, the flow rate of which drops to zero, while
the vacuum pump evacuates the gas in the pump housing and tries to restore the maximum
liquid level.
[0028] Should this not occur within a preset time, control means would then close the electric
shut off valves in the output of the centrifugal pump 26 and the vacuum shut off valve
25 on top of the pump housing, isolating in that way the problematic pumping unit
from the others which, however, continue to function. At the same time an error signal
can be generated warning an operator of the faulty situation.
[0029] In case a vapour recovery system is also used, the capacity of the vacuum pump is
of course adapted for both degassing and vapour recovery.
[0030] In the embodiment of the figures 9 and 10, the pumps are separated from the pump
housings, in the same way as the embodiment of figures 1-4. The pump housings of this
embodiment therefore can have the same embodiment as that of the pumping device of
these figures 1-4.
[0031] The hydrodynamic liquid pump 30 is here designed as a single stage centrifugal pump.
It is designed with a through-going shaft, such that two, three or more pumps can
be assembled as shown in figure 10. The advantage described for the embodiment of
fig. 1-4 concerning the low pressure drop on the shaft sealings is also valid here.
The two different lengths of grooved shafts 31, 32 shown in figure 10 connect the
respective shafts 33 of the pumps 30 in such a way that the units can be assembled
one against the other.
1. Pumping device for several different, relatively volatile vehicle fuels, comprising
a number of pump units each having a closed pump housing with an intake connected
to a supply of one of the vehicle fuels, at least one discharge connected to a delivery
means of a vehicle fuel station, and a hydrodynamic fuel pump with a fuel inlet drawing
from the interior of the pump housing and a pressure outlet connected to the discharge,
and further comprising one single gas pump with a gas inlet drawing from the pump
housing of each of the pump units.
2. Pumping device according to claim 1, comprising one electric motor, drivingly connected
to the hydrodynamic pumps of each of the pump units and to the gas pump.
3. Pumping device according to claim 2, wherein the electric motor is of the kind having
two engeagable shaft ends, one of these ends being connected to the gas pump and the
other end being connected to drive means connecting each of the hydrodynamic pumps.
4. Pumping device according to one of the preceding claims, wherein the hydrodynamic
pumps are embodied as replaceable cartridges.
5. Pumping device according to one of the preceding claims, wherein the gas pump is separate
from the pump units and connected to the pump housings by conduits.
6. Pumping device according to one of the preceding claims, comprising in the pump housing
of each of the pump units a float switch, a vacuum shut off valve in the connection
with the gas pump and a discharge shut off valve in the connection with the discharge,
said float switch and valves being connected to control means, closing the vacuum
shut off valve with a high end position of the float and closing the discharge shut
off valve with a low end position of the float.
7. Pumping device according to claim 6, wherein the control means include a timer closing
the discharge shut off valve when the vacuum shut off valve has been open during a
set period.