Title of Invention	A FUEL SUPPLY DEVICE FOR A MOTOR VEHICLE OPERABLE WITH A FUEL CONTAINER WITH MULTIPLE CHAMBERS
Abstract	The invention relates to a fuel-supply unit for a motor vehicle, comprising a fuel container (2) that has several chambers (6, 7). Said unit comprises a transfer pump (5) that is located inside the fuel container (2) for exclusively supplying ejector pumps (9, 10), which are positioned in the chambers (6, 7), with fuel as the pumping fluid. A primary fuel pump (4) that is located outside the fuel container (2) supplies an internal combustion engine (1) of the motor vehicle with fuel. The transfer pump (5) is operated discontinuously to prevent unnecessary power consumption.

Title of Invention

A FUEL SUPPLY DEVICE FOR A MOTOR VEHICLE OPERABLE WITH A FUEL CONTAINER WITH MULTIPLE CHAMBERS

Abstract

The invention relates to a fuel-supply unit for a motor vehicle, comprising a fuel container (2) that has several chambers (6, 7). Said unit comprises a transfer pump (5) that is located inside the fuel container (2) for exclusively supplying ejector pumps (9, 10), which are positioned in the chambers (6, 7), with fuel as the pumping fluid. A primary fuel pump (4) that is located outside the fuel container (2) supplies an internal combustion engine (1) of the motor vehicle with fuel. The transfer pump (5) is operated discontinuously to prevent unnecessary power consumption.

Full Text	PCT/EP2006/050116 - 1 - 2005P00829WOUS Description Fuel supply device for a motor vehicle The invention relates to a fuel supply device for a motor vehicle having a fuel container and having a main fuel pump which is arranged outside the fuel container and has the purpose of sucking in fuel from the fuel container and of feeding the fuel to the internal combustion engine. Such fuel supply devices are frequently used in contemporary motor vehicles in conjunction with fuel containers having a single chamber, and said fuel supply devices are known from practice. In contemporary fuel supply devices, fuel which is not required by the internal combustion engine is frequently fed back in a non-pressurized state into the fuel container. For this reason, it is not possible to connect to the return line any suction jet pumps which can feed fuel from a secondary chamber of the fuel container into a main chamber. However, fuel containers which have a plurality of chambers are frequently used, for example in motor vehicles with all wheel drive. The possibility of using a transfer pump for supplying suction jet pumps arranged in the fuel container has already been considered. Continuous operation of the transfer pump results in a continuous noise level, a high level of power consumption and also in a short service life. The invention is based on the problem of developing a fuel supply device of the type mentioned at the beginning in such a way that it permits operation in conjunction with a fuel container which has a plurality of chambers. PCT/EP2006/050116 - 2 - 2005P00829WOUS. This problem is solved according to the invention in that suction jet pumps for feeding fuel from the chambers of the fuel container to an intake port of the main fuel pump are arranged in said chambers, in that an electrically driven transfer pump is arranged within the fuel container, and in that a pressure side of the transfer pump is connected to nozzles of the suction jet pumps, and in that the transfer pump is switched discontinuously. As a result of this configuration, the transfer pump permits a plurality of suction jet pumps to be supplied with fuel as the propellant and makes available the anticipated propellant pressure for the suction jet pumps. The fuel which is distributed in different chambers of the fuel container is therefore reliably fed to the intake port of the main fuel pump. Fuel which is possibly returned from the internal combustion engine can in this context be returned in an nonpressurized state into the fuel container at any desired point. The returned fuel is preferably fed to the intake port. An operating mode of the fuel supply system according to the invention which is particularly convenient for the users of the motor vehicle can be ensured if the transfer pump is switched discontinuously. As a result of this configuration, the transfer pump is switched off at anticipated times, which results not only in a reduction in the noise level caused by the transfer pump but also in lowering of the power consumption and in a long service life of the transfer pump. The mounting of the fuel supply device according to the invention in the fuel container is particularly easy if the transfer pump and the intake port of the main fuel pump are arranged in a common surge pot. As a result, the transfer pump and the PCT/EP2006/050116 - 3 - 2005P00829WOUS. surge pot can be premounted as a premountable unit outside the fuel container. According to another advantageous development of the invention, reliable supply of fuel to the transfer pump can be easily ensured if the suction jet pumps open into the common surge pot. Particularly low power consumption of the transfer pump can be easily ensured according to another advantageous development of the invention if the transfer pump is controlled by means of filling level sensors which are arranged in the chambers of the fuel container. As a result of this configuration, the transfer pump remains permanently inactive when, for example, the fuel container is full and the fuel can flow independently of the chambers inside the fuel container. If the fuel is separated from the chambers when the fuel container is virtually empty, the transfer pump is switched on only when there is too little fuel at the intake port of the main fuel pump but sufficient fuel in another chamber. As a result, it becomes possible to control the transfer pump in a demand-dependent way in accordance with the filling levels of the fuel in the individual chambers. Controlling the transfer pump by means of a level switch contributes to reducing the structural complexity of the fuel supply device according to the invention. As a result, the transfer pump remains continuously in the switched off state if sufficient fuel is present in the region of the intake port. Such level switches are generally known and they close or interrupt an electrical contact when the fuel exceeds or drops below a filling level. PCT/EP2006/050116 - 4 - 2005P00829WOUS. The level switch is preferably arranged within the surge pot and/or within a connection of the chambers of the fuel container. As a result, it is possible to sense whether fuel is present near to the intake port of the main fuel pump or whether fuel can overflow from one chamber to the other chamber. According to another advantageous development, the level switch is structurally particularly simple if it is embodied as a float switch. The interruption of the feeding of the transfer pump, that is to say when sufficient fuel is present in the chamber which has the intake port of the main fuel pump, requires complex sensing and evaluation of filling levels in the fuel container. According to another advantageous development of the invention, the discontinuous switching of the transfer pump requires particularly little expenditure if the transfer pump has an intermittent switching mode and if the intermittent switching mode is designed to generate an alternating power supply to the transfer pump for successive time periods. Such an intermittent switching mode permits clocked switching of the transfer pump so that an anticipated time period in which the transfer pump is operating is followed by a further anticipated time period in which the transfer pump is switched off. According to another advantageous development of the invention, it is easy to ensure that the suction jet pumps are fed sufficiently if the intermittent switching mode is the ratio of successive time periods of up to 1 to 10 or 20, wherein the power supply to the transfer pump is interrupted in the relatively long time period. PCT/EP2006/050116 - 5 - 2005P00829WOUS. According to another advantageous development, the discontinuous switching of the transfer pump is structurally particularly simple if the transfer pump has an electronic control unit. Connecting the electronic control unit to a relay which is arranged in a power supply of the transfer pump or a transistor circuit contributes to further simplifying the switching of the transfer pump. If the control of the transfer pump fails, it is easily possible to ensure a sufficient supply of fuel to the main fuel pump if the relay or the transistor circuit causes the transfer pump to be supplied with power in the nonactuated state. This ensures an emergency operating property of the fuel supply system according to the invention. The invention permits numerous embodiments. In order to clarify its basic principle further, two of said principles are illustrated in the drawing and will be described below. In said drawing: Figure 1 is a schematic illustration of a fuel supply device according to the invention, Figure 2 is a schematic view of a circuit diagram relating to the means of actuating a transfer pump of the inventive fuel supply device from figure 1, and Figure 3 is a further schematic illustration of the fuel supply device according to the invention. Figure 1 is a schematic view of a fuel supply device for supplying fuel to an internal combustion engine 1, which operates accordingly to the diesel principle, PCT/EP2006/050116 - 6 - 2005P00829WOUS. of a motor vehicle. The fuel supply device has a main fuel pump 4 which sucks in fuel via an intake port 3 which projects into a fuel container 2, and a transfer pump 5 which feeds fuel within the fuel container 2 to the intake port 3 of the main fuel pump 4. This main fuel pump 4 can be, for example, a mechanically driven diesel high pressure pump. The fuel container 2 is embodied as what is referred to as a saddle tank with two chambers. The main fuel pump 4 is arranged outside the fuel container 2, while the intake port 3 and the transfer pump 5 are arranged inside a surge pot 8 which is prestressed against the bottom of the fuel container 2. Suction jet pumps 9, 10 which are supplied with fuel as a propellant from the transfer pump 5 and which feed fuel from the chambers 6, 7 into the surge pot 8 are arranged in the chambers 6, 7. Furthermore, filling level sensors 11, 12 for measuring the filling level of fuel in the respective chambers 6, 7 are arranged in the chambers 6, 7. Figure 2 is a schematic circuit diagram relating to the means of actuating the transfer pump 5 from figure 1. The transfer pump 5 is connected to a power source 15 via a relay 14 which can be actuated by a control unit 13. In the illustrated basic state, the connection is formed between the transfer pump 5 and the power source 15 so that if the control unit 13 fails the transfer pump 5 is continuously supplied with electrical current and it is ensured that fuel is fed to the intake port 3 illustrated in figure 1. The control unit 13 has an intermittent switching mode 16 according to which the relay 14 is actuated after an anticipated first time period and the power supply to the transfer pump 5 is interrupted for an anticipated second time period. This second time period is followed in turn by the first time PCT/EP2006/050116 - 7 - 2005P00829WOUS. period in which the transfer pump 5 is actuated. The ratio of the first time period to the second time period is, for example, 1 to 10 so that the transfer pump 5 is switched off for most of the time. Furthermore, the control unit 13 has an input 17 for signals of the filling level sensors 11, 12. As a result, the transfer pump 5 can, for example, be switched off if the fuel container 2 is completely filled with fuel and fuel can overflow from one chamber 6 into the other chamber 7. Alternatively, the control unit 13 can also evaluate the signals of the filling level sensors 11, 12 in the individual chambers 6, 7 and activate the transfer pump 5 only if the chamber 5 which has the surge pot 8 has virtually no fuel but other chambers have sufficient fuel. Figure 3 shows a further embodiment of the fuel supply device which differs from that in figure 1 only in that a level switch 18, 19 is arranged at the upper edge of the surge pot 8 and within the fuel container 2, respectively. The level switches 18, 19 are embodied as float switches. The transfer pump 5 can be actuated using the signals from the level switches 18, 19 in that, for example, the transfer pump 5 is continuously switched off when the surge pot 8 is filled with fuel. If the filling level in the surge pot 8 drops below the filling level which is provided for the switching of the level switch 18 in the surge pot 8, the transfer pump 5 can be activated. The level switch 19 in the fuel container 2 makes it possible to sense whether fuel can flow to and fro between the chambers 6, 7. In this case, it is not necessary to activate the transfer pump 8 and it is possible to prevent it. Here, as in the first embodiment, the transfer pump 8 can be activated with the control unit 13 according to figure 2 in an intermittent switching mode or a timed switching mode in which the transfer pump 8 is activated for a minimum time PCT/EP2006/050116 - 8 - 2005P00829WOUS. period of, for example, 60 seconds. For this purpose, signals from the level switches 18, 19 are fed to the control unit 13 via the input 17. PCT/EP2006/050116 - 9 - 2005P00829WOUS. Patent claims 1. A fuel supply device for a motor vehicle having a fuel container and having a main fuel pump which is arranged outside the fuel container and has the purpose of sucking in fuel from the fuel container and feeding the fuel to the internal combustion engine, characterized in that suction jet pumps (9, 10) for feeding fuel from the chambers (6, 7) of the fuel container (2) to an intake port (3) of the main fuel pump (4) are arranged in said chambers (6, 7), in that an electrically driven transfer pump (5) is arranged within the fuel container (2), and in that a pressure side of the transfer pump (5) is connected to nozzles of the suction jet pumps (9, 10), and in that the transfer pump (5) is switched discontinuously. 2. The fuel supply device as claimed in claim 1 or 2, characterized in that the transfer pump (5) and the intake port (3) of the main fuel pump (4) are arranged in a common surge pot (8). 3. The fuel supply device as claimed in claim 1 or 2, characterized in that the suction jet pumps (9, 10) open into the common surge pot (8). 4. The fuel supply device as claimed in at least one of the preceding claims, characterized in that the transfer pump (5) is controlled by means of filling level sensors (11, 12) which are arranged in the chambers (6, 7) of the fuel container (2). PCT/EP2006/050116 - 10 - 2005P00829WOUS. 5. The fuel supply device as claimed in at least one the preceding claims, characterized in that the transfer pump (5) is controlled by means of level switch (18, 19). 6. The fuel supply device as claimed in at least one of the preceding claims, characterized in that the level switch (18, 19) is arranged within the surge pot (8) and/or within a connection of the chambers (6, 7) of the fuel container (2). 7. The fuel supply device as claimed in at least one of the preceding claims, characterized in that the level switch (18, 19) is embodied as a float switch. 8. The fuel supply device as claimed in at least one of the preceding claims, characterized in that the transfer pump (5) has an intermittent switching mode (16) , and in that the intermittent switching mode (16) is designed to generate an alternating power supply to the transfer pump (5) for successive time periods. 9. The fuel supply device as claimed in at least one of the preceding claims, characterized in that the intermittent switching mode (16) is the ratio of successive time periods up to 1 to 10 or 20, wherein the power supply to the transfer pump (5) is interrupted in the relatively long time period. 10. The fuel supply device as claimed in at least one of the preceding claims, characterized PCT/EP2006/050116 - 11 - 2005P00829WOUS. in that the transfer pump (5) has an electronic control unit (13). 11. The fuel supply device as claimed in at least one of the preceding claims, characterized in that the electronic control unit (13) is connected to a relay (14) which is arranged in a power supply for the transfer pump (5) or transistor circuit. 12. The fuel supply device as claimed in at least one of the preceding claims, characterized in that the relay (14) or the transistor circuit causes the transfer pump (5) to be supplied with power in the nonactuated state. The invention relates to a fuel-supply unit for a motor vehicle, comprising a fuel container (2) that has several chambers (6,7). Said unit comprises a transfer pump (5) that is located inside the fuel container (2) for exclusively supplying ejector pumps (9, 10), which are positioned in die chambers (6,7), with fuel as the pumping fluid. A primary fuel pump (4) that is located outside the fuel container (2) supplies an internal combustion engine (1) of the motor vehicle with fuel. The transfer pump (5) is operated discontinuously to prevent unnecessary power consumption.

Full Text

PCT/EP2006/050116 - 1 -
2005P00829WOUS
Description
Fuel supply device for a motor vehicle
The invention relates to a fuel supply device for a motor
vehicle having a fuel container and having a main fuel pump
which is arranged outside the fuel container and has the
purpose of sucking in fuel from the fuel container and of
feeding the fuel to the internal combustion engine.
Such fuel supply devices are frequently used in contemporary
motor vehicles in conjunction with fuel containers having a
single chamber, and said fuel supply devices are known from
practice. In contemporary fuel supply devices, fuel which is
not required by the internal combustion engine is frequently
fed back in a non-pressurized state into the fuel container.
For this reason, it is not possible to connect to the return
line any suction jet pumps which can feed fuel from a secondary
chamber of the fuel container into a main chamber. However,
fuel containers which have a plurality of chambers are
frequently used, for example in motor vehicles with all wheel
drive.
The possibility of using a transfer pump for supplying suction
jet pumps arranged in the fuel container has already been
considered. Continuous operation of the transfer pump results
in a continuous noise level, a high level of power consumption
and also in a short service life.
The invention is based on the problem of developing a fuel
supply device of the type mentioned at the beginning in such a
way that it permits operation in conjunction with a fuel
container which has a plurality of chambers.

PCT/EP2006/050116 - 2 -
2005P00829WOUS.
This problem is solved according to the invention in that
suction jet pumps for feeding fuel from the chambers of the
fuel container to an intake port of the main fuel pump are
arranged in said chambers, in that an electrically driven
transfer pump is arranged within the fuel container, and in
that a pressure side of the transfer pump is connected to
nozzles of the suction jet pumps, and in that the transfer pump
is switched discontinuously.
As a result of this configuration, the transfer pump permits a
plurality of suction jet pumps to be supplied with fuel as the
propellant and makes available the anticipated propellant
pressure for the suction jet pumps. The fuel which is
distributed in different chambers of the fuel container is
therefore reliably fed to the intake port of the main fuel
pump. Fuel which is possibly returned from the internal
combustion engine can in this context be returned in an
nonpressurized state into the fuel container at any desired
point. The returned fuel is preferably fed to the intake port.
An operating mode of the fuel supply system according to the
invention which is particularly convenient for the users of the
motor vehicle can be ensured if the transfer pump is switched
discontinuously. As a result of this configuration, the
transfer pump is switched off at anticipated times, which
results not only in a reduction in the noise level caused by
the transfer pump but also in lowering of the power consumption
and in a long service life of the transfer pump.
The mounting of the fuel supply device according to the
invention in the fuel container is particularly easy if the
transfer pump and the intake port of the main fuel pump are
arranged in a common surge pot. As a result, the transfer pump
and the

PCT/EP2006/050116 - 3 -
2005P00829WOUS.
surge pot can be premounted as a premountable unit outside the
fuel container.
According to another advantageous development of the invention,
reliable supply of fuel to the transfer pump can be easily
ensured if the suction jet pumps open into the common surge
pot.
Particularly low power consumption of the transfer pump can be
easily ensured according to another advantageous development of
the invention if the transfer pump is controlled by means of
filling level sensors which are arranged in the chambers of the
fuel container. As a result of this configuration, the transfer
pump remains permanently inactive when, for example, the fuel
container is full and the fuel can flow independently of the
chambers inside the fuel container. If the fuel is separated
from the chambers when the fuel container is virtually empty,
the transfer pump is switched on only when there is too little
fuel at the intake port of the main fuel pump but sufficient
fuel in another chamber. As a result, it becomes possible to
control the transfer pump in a demand-dependent way in
accordance with the filling levels of the fuel in the
individual chambers.
Controlling the transfer pump by means of a level switch
contributes to reducing the structural complexity of the fuel
supply device according to the invention. As a result, the
transfer pump remains continuously in the switched off state if
sufficient fuel is present in the region of the intake port.
Such level switches are generally known and they close or
interrupt an electrical contact when the fuel exceeds or drops
below a filling level.

PCT/EP2006/050116 - 4 -
2005P00829WOUS.
The level switch is preferably arranged within the surge pot
and/or within a connection of the chambers of the fuel
container. As a result, it is possible to sense whether fuel is
present near to the intake port of the main fuel pump or
whether fuel can overflow from one chamber to the other
chamber.
According to another advantageous development, the level switch
is structurally particularly simple if it is embodied as a
float switch.
The interruption of the feeding of the transfer pump, that is
to say when sufficient fuel is present in the chamber which has
the intake port of the main fuel pump, requires complex sensing
and evaluation of filling levels in the fuel container.
According to another advantageous development of the invention,
the discontinuous switching of the transfer pump requires
particularly little expenditure if the transfer pump has an
intermittent switching mode and if the intermittent switching
mode is designed to generate an alternating power supply to the
transfer pump for successive time periods. Such an intermittent
switching mode permits clocked switching of the transfer pump
so that an anticipated time period in which the transfer pump
is operating is followed by a further anticipated time period
in which the transfer pump is switched off.
According to another advantageous development of the invention,
it is easy to ensure that the suction jet pumps are fed
sufficiently if the intermittent switching mode is the ratio of
successive time periods of up to 1 to 10 or 20, wherein the
power supply to the transfer pump is interrupted in the
relatively long time period.

PCT/EP2006/050116 - 5 -
2005P00829WOUS.
According to another advantageous development, the
discontinuous switching of the transfer pump is structurally
particularly simple if the transfer pump has an electronic
control unit.
Connecting the electronic control unit to a relay which is
arranged in a power supply of the transfer pump or a transistor
circuit contributes to further simplifying the switching of the
transfer pump.
If the control of the transfer pump fails, it is easily
possible to ensure a sufficient supply of fuel to the main fuel
pump if the relay or the transistor circuit causes the transfer
pump to be supplied with power in the nonactuated state. This
ensures an emergency operating property of the fuel supply
system according to the invention.
The invention permits numerous embodiments. In order to clarify
its basic principle further, two of said principles are
illustrated in the drawing and will be described below. In said
drawing:
Figure 1 is a schematic illustration of a fuel supply device
according to the invention,
Figure 2 is a schematic view of a circuit diagram relating to
the means of actuating a transfer pump of the
inventive fuel supply device from figure 1, and
Figure 3 is a further schematic illustration of the fuel
supply device according to the invention.
Figure 1 is a schematic view of a fuel supply device for
supplying fuel to an internal combustion engine 1, which
operates accordingly to the diesel principle,

PCT/EP2006/050116 - 6 -
2005P00829WOUS.
of a motor vehicle. The fuel supply device has a main fuel pump
4 which sucks in fuel via an intake port 3 which projects into
a fuel container 2, and a transfer pump 5 which feeds fuel
within the fuel container 2 to the intake port 3 of the main
fuel pump 4. This main fuel pump 4 can be, for example, a
mechanically driven diesel high pressure pump. The fuel
container 2 is embodied as what is referred to as a saddle tank
with two chambers. The main fuel pump 4 is arranged outside the
fuel container 2, while the intake port 3 and the transfer pump
5 are arranged inside a surge pot 8 which is prestressed
against the bottom of the fuel container 2. Suction jet pumps
9, 10 which are supplied with fuel as a propellant from the
transfer pump 5 and which feed fuel from the chambers 6, 7 into
the surge pot 8 are arranged in the chambers 6, 7. Furthermore,
filling level sensors 11, 12 for measuring the filling level of
fuel in the respective chambers 6, 7 are arranged in the
chambers 6, 7.
Figure 2 is a schematic circuit diagram relating to the means
of actuating the transfer pump 5 from figure 1. The transfer
pump 5 is connected to a power source 15 via a relay 14 which
can be actuated by a control unit 13. In the illustrated basic
state, the connection is formed between the transfer pump 5 and
the power source 15 so that if the control unit 13 fails the
transfer pump 5 is continuously supplied with electrical
current and it is ensured that fuel is fed to the intake port 3
illustrated in figure 1. The control unit 13 has an
intermittent switching mode 16 according to which the relay 14
is actuated after an anticipated first time period and the
power supply to the transfer pump 5 is interrupted for an
anticipated second time period. This second time period is
followed in turn by the first time

PCT/EP2006/050116 - 7 -
2005P00829WOUS.
period in which the transfer pump 5 is actuated. The ratio of
the first time period to the second time period is, for
example, 1 to 10 so that the transfer pump 5 is switched off
for most of the time. Furthermore, the control unit 13 has an
input 17 for signals of the filling level sensors 11, 12. As a
result, the transfer pump 5 can, for example, be switched off
if the fuel container 2 is completely filled with fuel and fuel
can overflow from one chamber 6 into the other chamber 7.
Alternatively, the control unit 13 can also evaluate the
signals of the filling level sensors 11, 12 in the individual
chambers 6, 7 and activate the transfer pump 5 only if the
chamber 5 which has the surge pot 8 has virtually no fuel but
other chambers have sufficient fuel.
Figure 3 shows a further embodiment of the fuel supply device
which differs from that in figure 1 only in that a level switch
18, 19 is arranged at the upper edge of the surge pot 8 and
within the fuel container 2, respectively. The level switches
18, 19 are embodied as float switches. The transfer pump 5 can
be actuated using the signals from the level switches 18, 19 in
that, for example, the transfer pump 5 is continuously switched
off when the surge pot 8 is filled with fuel. If the filling
level in the surge pot 8 drops below the filling level which is
provided for the switching of the level switch 18 in the surge
pot 8, the transfer pump 5 can be activated. The level switch
19 in the fuel container 2 makes it possible to sense whether
fuel can flow to and fro between the chambers 6, 7. In this
case, it is not necessary to activate the transfer pump 8 and
it is possible to prevent it. Here, as in the first embodiment,
the transfer pump 8 can be activated with the control unit 13
according to figure 2 in an intermittent switching mode or a
timed switching mode in which the transfer pump 8 is activated
for a minimum time

PCT/EP2006/050116 - 8 -
2005P00829WOUS.
period of, for example, 60 seconds. For this purpose, signals
from the level switches 18, 19 are fed to the control unit 13
via the input 17.

PCT/EP2006/050116 - 9 -
2005P00829WOUS.
Patent claims
1. A fuel supply device for a motor vehicle having a fuel
container and having a main fuel pump which is arranged
outside the fuel container and has the purpose of sucking
in fuel from the fuel container and feeding the fuel to
the internal combustion engine, characterized in that
suction jet pumps (9, 10) for feeding fuel from the
chambers (6, 7) of the fuel container (2) to an intake
port (3) of the main fuel pump (4) are arranged in said
chambers (6, 7), in that an electrically driven transfer
pump (5) is arranged within the fuel container (2), and in
that a pressure side of the transfer pump (5) is connected
to nozzles of the suction jet pumps (9, 10), and in that
the transfer pump (5) is switched discontinuously.
2. The fuel supply device as claimed in claim 1 or 2,
characterized in that the transfer pump (5) and the intake
port (3) of the main fuel pump (4) are arranged in a
common surge pot (8).
3. The fuel supply device as claimed in claim 1 or 2,
characterized in that the suction jet pumps (9, 10) open
into the common surge pot (8).
4. The fuel supply device as claimed in at least one of the
preceding claims, characterized in that the transfer pump
(5) is controlled by means of filling level sensors (11,
12) which are arranged in the chambers (6, 7) of the fuel
container (2).

PCT/EP2006/050116 - 10 -
2005P00829WOUS.
5. The fuel supply device as claimed in at least one the
preceding claims, characterized in that the transfer pump
(5) is controlled by means of level switch (18, 19).
6. The fuel supply device as claimed in at least one of the
preceding claims, characterized in that the level switch
(18, 19) is arranged within the surge pot (8) and/or
within a connection of the chambers (6, 7) of the fuel
container (2).
7. The fuel supply device as claimed in at least one of the
preceding claims, characterized in that the level switch
(18, 19) is embodied as a float switch.
8. The fuel supply device as claimed in at least one of the
preceding claims, characterized in that the transfer pump
(5) has an intermittent switching mode (16) , and in that
the intermittent switching mode (16) is designed to
generate an alternating power supply to the transfer pump
(5) for successive time periods.
9. The fuel supply device as claimed in at least one of the
preceding claims, characterized in that the intermittent
switching mode (16) is the ratio of successive time
periods up to 1 to 10 or 20, wherein the power supply to
the transfer pump (5) is interrupted in the relatively
long time period.
10. The fuel supply device as claimed in at least one of the
preceding claims, characterized

PCT/EP2006/050116 - 11 -
2005P00829WOUS.
in that the transfer pump (5) has an electronic control
unit (13).
11. The fuel supply device as claimed in at least one of the
preceding claims, characterized in that the electronic
control unit (13) is connected to a relay (14) which is
arranged in a power supply for the transfer pump (5) or
transistor circuit.
12. The fuel supply device as claimed in at least one of the
preceding claims, characterized in that the relay (14) or
the transistor circuit causes the transfer pump (5) to be
supplied with power in the nonactuated state.

The invention relates to a fuel-supply unit for a motor vehicle, comprising a fuel container (2) that has several
chambers (6,7). Said unit comprises a transfer pump (5) that is located inside the fuel container (2) for exclusively supplying ejector
pumps (9, 10), which are positioned in die chambers (6,7), with fuel as the pumping fluid. A primary fuel pump (4) that is located
outside the fuel container (2) supplies an internal combustion engine (1) of the motor vehicle with fuel. The transfer pump (5) is
operated discontinuously to prevent unnecessary power consumption.

A FUEL SUPPLY DEVICE FOR A MOTOR VEHICLE OPERABLE WITH A FUEL CONTAINER WITH MULTIPLE CHAMBERS

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