Note: Descriptions are shown in the official language in which they were submitted.
' ' , ' . CA 02321606 2000-10-02
The invention concerns a fuel supply arrangement for an internal
combustion engine, for example as a fuel supply arrangement in
conjunction with a motor vehicle fuel tank. The invention further concerns a
fuel pump for an internal combustion engine, more especially for a fuel
supply arrangement in a motor vehicle.
A representative form of a fuel supply arrangement for an internal
combustion engine, which can be used more especially as a fuel supply
arrangement in conjunction with a motor vehicle fuel tank for use in a
motor vehicle, comprises at least one electrically operated fuel pump which
is disposed in a surge pot, for conveying fuel from the surge pot into a fuel
feed line leading to the internal combustion engine. The arrangement
further includes at least one fuel return line for returning fuel from the
engine, under conditions when such fuel is not required and is thus excess
to the engine needs.
Fuel supply arrangements of that kind are used both in relation to
motor vehicles with Otto-cycle or four-stroke engines and also motor
vehicles with diesel engines. In regard to the design of fuel supply
arrangements of that kind, it is important that the injector valves of the
engine are always reliably supplied with fuel under all operational travel
and environmental conditions. For that purpose, it is necessary above all to
ensure that there is always an adequate supply of fuel at the point where
the fuel pump picks up fuel from the tank, even when the amount of fuel
remaining in the tank is slight and also in extreme operating situations, for
example when the motor vehicle in which the arrangement is fitted is
inclined at an extreme angle in a transverse or longitudinal direction or a
combination thereof. In order to guarantee that, the usual practice is for
the fuel pump to be arranged in a chamber which is referred to as a surge
pot and which serves as a reserve container from which fuel can be
continuously supplied to the engine. The intention is that the surge pot
should be filled with fuel in any operational situation of the vehicle, and
this
is generally implemented by suction jet pumps which are disposed in the
fuel tank and which are operated by way of a fuel return line from the
engine or, in the case of a fuel supply system which does not involve a fuel
1
CA 02321606 2000-10-02
return from engine to tank, by way of a return which is branched off the
fuel feed line by means of a by-pass. Those suction jet pumps acting as
ancillary pumps continuously deliver fuel from the tank into the surge pot.
Over and above the maximum full-load amount of fuel demanded by
an engine, a fuel pump must therefore also deliver the return flow for
feeding such a suction jet pump and possibly also a further amount for
compensating for the drop in delivery in hot conditions.
There are also some fuel supply arrangements in which the fuel
pump continuously supplies a constant amount of fuel to the engine,
i0 irrespective of whether the engine is being operated under full load or
partial load. In the partial load mode of operation, that results in a
comparatively high level of return flow of fuel which however under some
circumstances is not necessary at all as just a low level of return flow of
fuel would be adequate under partial load conditions, to fill the surge pot.
i5 In contrast, when the engine is operating under full load, a high flow by
volume has to be conveyed from the tank into the surge pot as the fuel
pump is delivering fuel at a high rate to the engine from the surge pot. It is
precisely in that situation however that there is then a comparatively low
return flow because the engine is burning a great deal of fuel.
20 In such systems therefore the pump has to be designed to afford a
maximum possible delivery.
A maximum delivery of that nature is not desirable in particular
having regard to the increasing demands made in terms of the levels of
emission from fuel supply systems. From the point of view of the energy
25 involved it is also not desirable to convey a fuel excess which is not
actually
required. Finally, under some circumstances, evaporation losses and
emissions can be increased due to unnecessary amounts of hot fuel flowing
back into the tank. Although that problem does not arise in the case of fuel
supply systems which do not have a return, the fuel pump nonetheless still
30 has to deliver a maximum amount in such systems.
The most widely varying endeavours have therefore been undertaken
to control or regulate fuel pumps, on the basis of the respective needs
concerned. Such design configurations provide for a reduction in the level
2
CA 02321606 2000-10-02
of load on the on-board electrical system of a motor vehicle. For example,
adaptation of the quantitative delivery of the pump to the current demand
for fuel can be achieved by way of an electronic device for regulating the
speed of rotation of the pump. It is also known for the pump to be operated
only cyclically, using a hydraulic fuel intermediate storage means for
supplying the injector valves therefrom.
The above-outlined systems for regulating or controlling fuel pumps
are comparatively complex and accordingly expensive. For example,
suitable interfaces with the electronic engine management system have to
be provided. Furthermore, additional separate control units are required,
which have to be connected between the electronic system of the engine
and a fuel pump or a fuel delivery module.
In accordance with the invention there is provided a fuel supply
arrangement for an internal combustion engine, for example as a fuel
supply arrangement in conjunction with a motor vehicle fuel tank,
comprising a surge pot for accommodating fuel, a fuel feed line for feeding
fuel to the engine, at least one fuel return line, at least one electrically
operated fuel pump in the surge pot and operable to convey fuel from the
surge pot into the fuel feed line to the engine, the fuel pump including an
2o electronic control means and at least one hydraulic control input, and
means connecting the hydraulic control input of the fuel pump to the fuel
feed line and/or the fuel return line.
As will be seen from a description hereinafter of preferred
embodiments of the invention, the invention advantageously makes use of
the items of information which are available in the tank, that is to say the
fuel pressures from the feed or the return, and which are transmitted
directly to the electronic control system which is integrated into the fuel
pump. That means that there is no longer any need for the fuel pump to be
coupled to an electronic engine management system.
3o In a preferred feature of the invention, the control means of the fuel
pump is combined therewith to form a structural unit so that essential
components of the fuel supply arrangement can be arranged in the fuel
tank. Those advantages are attained in particular when the fuel pump is
3
CA 02321606 2000-10-02
driven by an electronically switched do motor. It will be noted that units of
this kind are comparatively small and include an electronic control system
which is arranged in the immediate proximity of the motor.
In a further preferred feature, the fuel pump has at least one
pressure sensor operatively connected to the control input of the fuel
pump. The pressure sensor can respond either to the system pressure, that
is to say the pressure in the fuel feed line, or the dynamic pressure in the
return.
It should be particularly stressed at this point that the term return
herein does not necessary denote only fuel which is running or flowing back
from the engine, but rather the term return in accordance with the
invention is also used to denote a volume flow which is branched off in the
tank from the feed flow of fuel to the engine, to provide for the operation of
a suction jet pump as referred to hereinbefore. The invention can also be
applied to fuel supply systems which are generally referred to as return-
less systems.
In a preferred feature of the invention, provided in the fuel return
line is a calibration means whose dynamic pressure is applied to the
hydraulic control input of the fuel pump.
z0 A further preferred feature of the invention, by way of example,
provides that a suction jet pump is connected to the return line, for filling
the surge pot during operation of the fuel pump, with the suction jet pump
being in the form of or serving as the calibration means. On the basis of the
variation in pressure at the suction jet pump, it is possible to ascertain the
z5 magnitude of the amount of fuel which is not consumed by the engine.
When that dynamic pressure acts on the pressure sensor of the fuel pump,
the return pressure or the amount of fuel for operating the suction jet
pump can be kept constant and the fuel pump is adapted to the respective
current level of consumption. That reliably ensures that, in the event of an
30 increased fuel consumption at the engine, for example under full-load
conditions, the amount of fuel delivered into the surge pot does not
decrease or too little fuel is not fed to the engine.
4
CA 02321606 2000-10-02
It will be noted that it is not possible for the fuel pump to be
completely shut down as a certain minimum level of flow of fuel
therethrough is required to cool the electric motor of the fuel pump.
In a further feature of the invention it can also be provided for
example that the suction jet pump is so designed that the pressure in the
return line can correspond to the pressure in the feed line so that the
pressure of the entire system is taken off for the purposes of controlling the
fuel pump. That configuration makes it possible to eliminate an additional
return pressure regulating valve between the engine and the tank.
It is also possible for a suction jet pump for filling the surge pot to be
integrated in a housing with the fuel pump and the associated electronic
control system, in which case the suction jet pump can communicate by
way of a reference bore with the pressure sensor provided in the pump
housing.
Further in accordance with the invention there is provided a fuel
pump for an internal combustion engine, for example for a fuel supply
arrangement of a motor vehicle, comprising a unit for a through flow of fuel
including a do motor and a pump device, means for controlling the pump,
said control means including at least one hydraulic control input and being
combined with the pump device and the do motor to form an assembly,
preferably being disposed in a housing.
Preferably, the control means includes at least one pressure sensor.
The do motor can be an electronically switched do motor.
Motors of that kind are described for example in US patents Nos 4
949 000, 5 659 217 and 5 874 796 to which attention is accordingly
directed for incorporation as appropriate of the contents thereof herein.
More particularly a do motor as set forth in US patent No 5 659 217 with a
radial gap arrangement is preferred in the context of the present invention.
Embodiments of the invention will now be described by way of
example, with reference to the accompanying drawings in which:
Figure 1 is a diagrammatic view of a first embodiment of a fuel
supply arrangement according to the invention with a fuel return line and
5
CA 02321606 2000-10-02
regulation of the fuel pump by way of the dynamic return pressure of a
suction jet pump,
Figure 2 is a diagrammatic view of a second embodiment of a fuel
supply arrangement according to the invention with a fuel return line and
regulation of the fuel pump by way of the dynamic system pressure,
Figure 3 is a diagrammatic view of a fuel pump according to the
invention, and
Figure 4 is a diagrammatic view in section of a suction jet pump.
Reference will firstly be made to Figures 1 and 2 jointly to describe
common components of a fuel supply arrangement according to the
invention for an internal combustion engine, for example as a fuel supply
arrangement in conjunction with a motor vehicle fuel tank.
Thus, the illustrated fuel supply arrangement includes a fuel tank
generally denoted by reference numeral 1, with a fuel feed line 2 to a
motor vehicle engine 3 and a fuel return line 4 from the engine 3 back into
the tank 1.
Disposed in the tank 1 is a fuel pump 5 which is arranged in a surge
pot 6 which is only diagrammatically illustrated. The tank 1 also contains a
suction jet pump 7 which is operated by way of the fuel return line 4 and
which delivers fuel from the tank 1 into the surge pot 6 as long as the fuel
pump 5 is being operated.
Reference will be made hereinafter to Figure 4 for a more detailed
description of the suction jet pump 7.
In the embodiment of the invention as shown in Figure 1, fuel is
conveyed from the fuel pump 5 by way of a fuel filter 8 and a pressure
regulator 9 to the engine 3. System pressure of the order of magnitude of
between 2 and 6 bars obtains between the engine 3 and the pressure
regulator 9. The pressure in the return line 4 is markedly lower. The flow of
fuel in the return line 4 operates the suction jet pump 7, with the fuel of
the return line 4 which flows through a nozzle indicated at 10 in Figure 4 of
the suction jet pump 7 forming a propulsion jet indicated at 11 in Figure 4
which entrains a suction jet of fuel 12 out of the tank 1 and into the surge
pot 6.
6
CA 02321606 2000-10-02
Looking still at Figure 1, the fuel pump 5 has a hydraulic control
input which is generally identified by reference numeral 13 and which acts
on a pressure sensor indicated at 14 in Figure 3. In the Figure 1
embodiment, the control input 13 is connected to the return line 4, more
specifically between the pressure regulator 9 and the suction jet pump 7.
The nozzle 10 of the suction jet pump 7 acts as a calibration device in the
form more specifically here of a calibration nozzle, so that the dynamic
pressure of the suction jet pump 7 is applied to the control input 13 of the
fuel pump 5. Regulation of the fuel pump 5 is desirably effected in such a
way that the delivery volume flow of the suction jet pump 7 is constant.
In the case of the embodiment of the fuel supply arrangement as
shown in Figure 2, it will be seen that the arrangement does not have the
pressure regulator indicated at 9 in Figure 1. The nozzle 10 of the suction
jet pump 7 is of a comparatively small diameter so that the design pressure
for the suction jet pump 7 is equal to the desired system pressure in the
feed line 2. In that way the system pressure can be directly controlled by
way of the fuel pump S. It is this configuration that renders redundant the
pressure regulator 9 of the Figure 1 embodiment.
To limit pressure peaks due to the fuel for example increasing in
temperature when the fuel pump 5 is switched off and in order to be able to
maintain the system pressure in the feed line 2 when the fuel pump 5 is
switched off, an electrically actuable shutoff valve 15 is provided in the
return line 4 between the suction jet pump 7 and the engine 3.
Attention is now directed to Figure 3 diagrammatically showing the
structure of the fuel pump 5 according to the invention. As can be seen
therefrom, the fuel pump 5 includes a pump mechanism or device which is
generally identified by reference numeral 17 and which is illustrated here in
the form of a side channel pump device, an electronically commutated do
motor 17 and an electronic control system 18 for the do motor 17. The
electronic control system 18, the do motor 17 and the pump device 16 are
disposed in a housing 19. Reference 20 denotes the fuel inlet and reference
21 denotes the fuel outlet. The electronic control system 18 includes the
pressure sensor 14 which can be addressed by way of the control input 13.
7
' , . CA 02321606 2000-10-02
Fuel flows entirely through the fuel pump 5 from the fuel inlet 20 to the fuel
outlet 21, with the fuel cooling the do motor 17 in operation of the
assembly.
In both of Figures 1 and 2 reference numeral 22 denotes a check
valve which, when the pump is switched off, prevents the feed line 2 from
suffering from a pressure drop therein or prevents the feed line 2 from
running empty.
While the control input 13 of the pump 5 is connected to the return
line 4 as illustrated, it may be connected to the feed line 2 or to both the
i0 feed line 2 and the return line 4.
It will be seen from the foregoing that the present invention provides
an improved fuel supply arrangement which ensures comparatively simple
and operationally reliable regulation of the fuel pump, while also being of a
simple design configuration and giving an improved response characteristic
to operational conditions of the engine. The fuel pump for an internal
combustion engine, for example for a fuel supply arrangement in a motor
vehicle, is of a compact structure and enjoys enhanced responsiveness in
terms of fuel control.
It will be appreciated that the above-described embodiments of the
invention have been set forth solely by way of example and illustration of
the principles thereof and that various modifications and alterations may be
made therein without thereby departing from the spirit and scope of the
invention.
8
