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(11) | EP 1 837 514 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Fuel supply assembly for an internal combustion engine |
| (57) A fuel-supply assembly (1) for an internal-combustion engine is provided with: a
pumping unit (6), designed to draw the fuel from a tank; a filtering device (7), designed
to filter the fuel; a pressure regulator (8); a hydraulic circuit (3), which connects
hydraulically together the pumping unit (6), the filtering device (7), and the pressure
regulator (8); and a housing body (2), which houses inside it the pumping unit (6),
the filtering device (7), the pressure regulator (8), and the hydraulic circuit (3);
the pumping unit (6) has a pumping chamber (9) delimited by a flexible membrane (10),
an eccentric cam (11), designed to deform cyclically the flexible membrane (10), and
an electric motor (12) for driving the eccentric cam (11) in rotation.
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TECHNICAL FIELD
[0002] The invention finds advantageous application an internal-combustion engine of a motor vehicle having a contained displacement (indicatively, 50 cc or 125 cc), to which the ensuing treatment will make explicit reference without this implying any loss of generality.
BACKGROUND ART
[0003] In the sector of fuel-supply assemblies for internal-combustion engines of motor vehicles it is known to provide a fuel-supply assembly comprising a pumping unit designed to draw the fuel from a tank and to feed it in the first place through a filtering unit, then through a pressure-regulating unit, and finally to at least one injector associated to the internal-combustion engine.
[0004] Each of the pumping, filtering, and pressure-regulating units referred to above is housed in a housing seat of its own provided in the bodywork of the motor vehicle and is connected to the other units via connector pipes. Consequently, known fuel-supply assemblies of the type described above present certain serious drawbacks mainly resulting from the fact that their use is relatively complex and costly, in particular for large-scale production, in so far as it entails the bodywork of the motor vehicle being provided with a housing seat for each of the aforesaid pumping, filtering, and pressure-regulating units.
[0005] Known fuel-supply assemblies of the type described above moreover present the further drawback represented by the fact that the connector pipes between the pumping unit, the filtering unit, and the pressure-regulating unit may involve leakages of fuel and are set, in any case, in points of the motor vehicle which are difficult to access, hence entailing both serious difficulties on the part of the staff responsible for their installation/maintenance and relatively long installation/maintenance times.
DISCLOSURE OF INVENTION
[0006] The aim of the present invention is to provide a fuel-supply assembly for an internal-combustion engine, said fuel-supply assembly being free from the drawbacks set forth above.
[0007] In accordance with the present invention, a fuel-supply assembly for an internal-combustion engine is provided according to what is claimed in the annexed claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] The present invention will now be described with reference to the annexed drawing, which illustrates a nonlimiting example of embodiment thereof. The attached figure is a schematic cross-sectional view, with parts removed for reasons of clarity, of a preferred embodiment of the fuel-supply assembly of the present invention.
PREFERRED EMBODIMENTS OF THE INVENTION
[0009] In the attached figure, the reference number 1 designates, as a whole, a fuel-supply assembly for an internal-combustion engine, which is designed to be installed on the bodywork of a motor vehicle for feeding the fuel from a tank to at least one injector of the internal-combustion engine itself.
[0010] The assembly 1 comprises a housing body 2, defined in which is a hydraulic circuit 3, which extends between a fuel-intake pipe 4 receiving the fuel from the tank and an outlet pipe 5 that carries the fuel to the internal-combustion engine and is parallel to the intake pipe 4. Set along the hydraulic circuit 3 are: a pumping unit 6, which is designed to draw the fuel from the tank and is housed in the housing body 2; a filtering device 7, which is designed to filter the fuel, is set downstream of the pumping unit 6, and is housed in the housing body 2; and a pressure regulator 8, which is designed to control the pressure of the fuel, is set downstream of the filtering device 7, and is housed in the housing body 2. In other words, the intake pipe 4 feeds the fuel to the pumping unit 6, and the outlet pipe 5 receives the fuel from the pressure regulator 8.
[0011] The pumping unit 6 comprises a pumping chamber 9 delimited by a flexible membrane 10, an eccentric cam 11 designed to deform the flexible membrane 10 cyclically, and an electric motor 12 for driving the eccentric cam 11 in rotation. Set between the eccentric cam 11 and the flexible membrane 10 is an axially mobile pin 13, which on one side rests against the flexible membrane 10 and on the opposite side rests against the eccentric cam 11. Preferably, set between the pin 13 and the flexible membrane 10 is a rigid bridge 14. Housed in the pumping chamber 9 is a spring 15, which is compressed against the flexible membrane 10 and keeps the flexible membrane 10 itself pressed against the pin 13.
[0012] Preferably, the eccentric cam 11 is coupled to a shaft 16 of the electric motor 12 by means of a roller-bearing cage 17. In this way, any friction on the movement of rotation is reduced to a minimum.
[0013] According to a preferred embodiment, the flexible membrane 10 is preformed and hence has a non-plane section and can present pre-weakened annular areas to favour and guide deformation of the flexible membrane 10 itself. Thanks to the fact that the flexible membrane 10 is preformed, the pressure pulsations generated by the pumping unit 6 are considerably attenuated, the overall noise of the fuel-supply assembly 1 is reduced, and the stroke of the pin 13 is reduced, thus increasing the energy efficiency of the pumping unit 6.
[0014] Finally, the pumping unit 6 has a one-way intake valve 18, which is set between the intake pipe 4 and the pumping chamber 9, and a one-way delivery valve 19, which is set between the pumping chamber 9 and the filtering device 7. The intake valve 18 is coaxial to the delivery valve 19 and to the intake pipe 4. In this way, machining of the housing body 2 is simplified. As emerges clearly evident from the attached figure, the flexible membrane 10 is deformed in a direction perpendicular to the intake valve 18, to the delivery valve 19, and to the intake pipe 4.
[0015] The filtering device 7 comprises a drum filter 20 having a radial fuel inlet from the outside towards the inside and an axial fuel outlet. In particular, outlet of the fuel from the filtering device 7 is coaxial to the outlet pipe 5. In this way, machining of the housing body 2 is simplified. In a position corresponding to the filtering device 7, the housing body 2 has a lid 21 that can be welded in the case where the drum filter 20 never has to be replaced, or else that can be screwed to enable replacement of the drum filter 20.
[0016] The pressure regulator 8 comprises a pressure-regulating chamber 22 delimited by a flexible membrane 23 and from which there originates the outlet pipe 5, a spring 24, which is compressed against the flexible membrane 23 and is set on the opposite side with respect to the pressure-regulating chamber 22, a discharge pipe 25, which originates in the pressure-regulating chamber 22, and a spherical open/close element 26, which is connected to the flexible membrane 23 and is designed to close an inlet mouth of the discharge pipe 25.
[0017] According to the preferred embodiment illustrated in the attached figure, the discharge pipe 25 originates in the pressure-regulating chamber 22 and gives out into the intake pipe 4 and is straight and perpendicular to the intake pipe 4 itself. In this case, the configuration is a returnless one, in which the excess fuel is recirculated within the fuel-supply assembly 1. According to a different embodiment (not illustrated), the discharge pipe 25 originates in the pressure-regulating chamber 22 and gives out into the tank. In this case, the configuration is a classic one, in which the excess fuel is re-introduced into the tank. The returnless configuration is simpler and less expensive to produce, but, on the other hand, tends to heat the fuel to a greater extent; consequently, said configuration can be used only if the fuel has not an excessive tendency to vaporize within the fuel-supply assembly 1.
[0018] According to a different embodiment (not illustrated), set between the filtering device 7 and the discharge pipe 25 is an overpressure valve, which constitutes a redundant safety device in regard to the pressure regulator 8.
[0019] The fuel-supply assembly 1 described above has numerous advantages, in so far as it is simple and inexpensive to produce and above all enables combination in one and the same assembly of the functions of fuel pumping, fuel filtering, and regulation of the pressure of the fuel; in this way, installation of the fuel-supply assembly 1 within a motor vehicle is simple and fast.
[0020] Furthermore, the fuel-supply assembly 1 described above presents an electrical consumption that is very contained and hence can be advantageously used for supplying the fuel to an internal-combustion engine having a small or very small displacement with a contained availability of electric power. By way of example, the fuel-supply assembly 1 described above enables supply of fuel at 300 kPa with a current absorption of approximately 0.6-0.7 A (obviously at a voltage of 12 V), whereas an electric fuel pump currently available on the market would require a current absorption of at least 2 A for supplying the fuel at 300 kPa.
[0021] As a result of the numerous advantages presented by the fuel-supply assembly 1 described above, said fuel-supply assembly 1 can be advantageously used also for applications other than the motorcycle sector; for example, it could be combined to an internal-combustion engine of a machine for agricultural/forestry purposes such as a chainsaw or a mowing machine.
1. A fuel-supply assembly (1) for an internal-combustion engine; the fuel-supply assembly
(1) comprises:
a pumping unit (6), designed to draw the fuel from a tank;
a filtering device (7), which is designed to filter the fuel and is set downstream of the pumping unit (6);
a pressure regulator (8), which is designed to control the pressure of the fuel and is set downstream of the filtering device (7);
a hydraulic circuit (3), which connects hydraulically together the pumping unit (6), the filtering device (7), and the pressure regulator (8) and extends between an intake pipe (4) that feeds the fuel to the pumping unit (6) and an outlet pipe (5) that receives the fuel from the pressure regulator (8); and
a housing body (2), which houses inside it the pumping unit (6), the filtering device (7), the pressure regulator (8), and the hydraulic circuit (3);
the fuel-supply assembly (1) is characterized in that the pumping unit (6) comprises a pumping chamber (9) delimited by a first flexible membrane (10), an eccentric cam (11), designed to deform cyclically the first flexible membrane (10), and an electric motor (12) for driving the eccentric cam (11) in rotation.
2. The fuel-supply assembly (1) according to Claim 1, wherein set between the eccentric
cam (11) and the first flexible membrane (10) is an axially mobile pin (13), which
on one side rests against the first flexible membrane (10) and on the opposite side
rests against the eccentric cam (11).
3. The fuel-supply assembly (1) according to Claim 1 or Claim 2, wherein the eccentric
cam (11) is coupled to a shaft (16) of the electric motor (12) by means of a roller-bearing
cage (17).
4. The fuel-supply assembly (1) according to Claim 1, Claim 2 or Claim 3, wherein the
first flexible membrane (10) is preformed and hence has a non-plane section.
5. The fuel-supply assembly (1) according to any one of Claims 1 to 4, wherein the pumping
unit (6) comprises a first spring (15) compressed against the first flexible membrane
(10).
6. The fuel-supply assembly (1) according to Claim 5, wherein the first spring (15) is
set within the pumping chamber (9).
7. The fuel-supply assembly (1) according to any one of Claims 1 to 6, wherein the pumping
unit (6) has a one-way intake valve (18), which is set between the intake pipe (4)
and the pumping chamber (9), and a one-way delivery valve (19), which is set between
the pumping chamber (9) and the filtering device (7).
8. The fuel-supply assembly (1) according to Claim 7, wherein the intake valve (18) is
coaxial to the delivery valve (19) and to the intake pipe (4).
9. The fuel-supply assembly (1) according to Claim 8, wherein the first flexible membrane
(10) is deformed in a direction perpendicular to the intake valve (18), to the delivery
valve (19), and to the intake pipe (4).
10. The fuel-supply assembly (1) according to any one of Claims 1 to 9, wherein the filtering
device (7) comprises a drum filter (20) having a radial fuel inlet from the outside
inwards and an axial fuel outlet.
11. The fuel-supply assembly (1) according to Claim 10, wherein the outlet of the fuel
from the filtering device (7) is coaxial to the outlet pipe (5).
12. The fuel-supply assembly (1) according to any one of Claims 1 to 11, wherein the pressure
regulator (8) comprises: a pressure-regulating chamber (22), which is delimited by
a second flexible membrane (23) and from which there originates the outlet pipe (5);
a second spring (24) compressed against the second flexible membrane (23) and set
on the side opposite to the pressure-regulating chamber (22); a discharge pipe (25),
which originates in the pressure-regulating chamber (22); and an open/close element
(26), which is connected to the second flexible membrane (23) and is designed to close
an inlet mouth of the discharge pipe (25).
13. The fuel-supply assembly (1) according to Claim 12, wherein the discharge pipe (25)
originates in the pressure-regulating chamber (22) and gives out into the intake pipe
(4).
14. The fuel-supply assembly (1) according to Claim 12, wherein the discharge pipe (25)
originates in the pressure-regulating chamber (22) and gives out into the tank.
15. The fuel-supply assembly (1) according to any one of Claims 1 to 14, wherein the intake
pipe (4) is parallel to the outlet pipe (5).