U.S. patent application number 10/991564 was filed with the patent office on 2005-09-22 for fuel pump for an internal combustion engine.
This patent application is currently assigned to Magneti Marelli Powertrain S.p.A.. Invention is credited to Cristiani, Marcello, Lamberti, Cecilia, Lolli, Massimo, Mattioli, Massimo, Pasquali, Paolo.
Application Number | 20050207912 10/991564 |
Document ID | / |
Family ID | 34466446 |
Filed Date | 2005-09-22 |
United States Patent
Application |
20050207912 |
Kind Code |
A1 |
Lolli, Massimo ; et
al. |
September 22, 2005 |
Fuel pump for an internal combustion engine
Abstract
In a fuel pump for an internal combustion engine, a pumping
device is adapted to vary the volume of a first chamber containing
the fuel and is formed by a second chamber adapted to contain oil,
a deformable diaphragm for the leak-tight separation of the
chambers from one another, and by a piston mounted to slide within
the second chamber and comprising an active end surface bounding
this second chamber; the diaphragm being adapted to be deformed to
vary the volume of the first chamber under the action of the thrust
exerted by the oil contained in the second chamber following an
alternating movement of the piston within this second chamber.
Inventors: |
Lolli, Massimo; (Bologna,
IT) ; Cristiani, Marcello; (Imola, IT) ;
Pasquali, Paolo; (Castelmaggiore, IT) ; Lamberti,
Cecilia; (Bologna, IT) ; Mattioli, Massimo;
(Castelmaggiore, IT) |
Correspondence
Address: |
HOWREY LLP
C/O IP DOCKETING DEPARTMENT
2941 FAIRVIEW PARK DRIVE, SUITE 200
FALLS CHURCH
VA
22042-7195
US
|
Assignee: |
Magneti Marelli Powertrain
S.p.A.
Corbetta
IT
|
Family ID: |
34466446 |
Appl. No.: |
10/991564 |
Filed: |
November 18, 2004 |
Current U.S.
Class: |
417/395 ;
417/390; 417/471 |
Current CPC
Class: |
F04B 43/0054 20130101;
F04B 43/067 20130101 |
Class at
Publication: |
417/395 ;
417/390; 417/471 |
International
Class: |
F04B 009/08; F04B
035/02 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 25, 2003 |
IT |
BO2003A000712 |
Mar 12, 2004 |
IT |
BO2004A000141 |
Claims
1. A fuel pump for an internal combustion engine; which pump
comprises: a first variable-volume chamber (13) adapted to contain
fuel, this first chamber (13) being provided with an intake valve
(14) and a delivery valve (15); pumping means (28) to vary the
volume of the first chamber (13) and comprising a second chamber
(20) adapted to contain oil, a piston (18) mounted to slide within
the second chamber (20), actuator means (23) adapted to provide the
piston (18) with an alternating movement within this second chamber
(20), and separator means (12) to separate the first and second
chambers (13, 20) from one another in a leak-tight manner; wherein
the piston (18) has an active end surface (19) bounding the second
chamber (20), and the separator means (12) comprise a deformable
diaphragm (12) adapted, in use, to be deformed to vary the volume
of the first chamber (13) under the action of the thrust exerted by
the oil contained in the second chamber (20) following the
alternating movement of the piston (18) within this second chamber
(20); and at least one stiffening member (40a, 40b) secured to a
central portion (39) of the diaphragm (12), mounted within the
second chamber (20) and adapted to be disposed, in use, in contact
with a wall (41) bounding this second chamber (20); the fuel pump
is characterised in that the second chamber (20) is provided with a
plurality of channels (42) for the passage of the oil provided
through the stiffening member (40a, 40b).
2. A fuel pump as claimed in claim 1, in which the diaphragm (12)
and the active surface (19) of the piston (18) comprise a first and
second surface respectively, the ratio between the first and the
second surface being at least equal to five.
3. A fuel pump as claimed in claim 1, in which the second chamber
(20) is provided with a maximum pressure valve (22) adapted to be
disposed in an open position when the value of the pressure of the
oil within the second chamber (20) is substantially equal to a
predetermined value.
4. A fuel pump as claimed in claim 1, in which the diaphragm (12)
is a steel diaphragm.
5. A fuel pump as claimed in claim 1, in which the alternating
movement of the piston (18) comprises an outwards stroke and a
return stroke, the actuator means (23) comprising first thrust
means to provide the piston (18) with its outward stroke and second
thrust means to provide the piston (18) with its return stroke.
6. A fuel pump as claimed in claim 5, in which the first thrust
means comprise resilient thrust means.
7. A fuel pump as claimed in claim 5, in which the second thrust
means comprises a cam and a tappet roller (27) mounted on the
piston (18) and cooperating with this cam (25).
8. A fuel pump as claimed in claim 1, in which the second chamber
(20) is provided with a further intake valve (21) adapted to
maintain a quantity of oil contained in this second chamber (20)
substantially constant.
9. A fuel pump as claimed in claim 1, in which the alternating
movement of the piston (18) comprises an outward stroke to increase
the volume of the first chamber (13) and control the opening of the
intake valve (14) and a return stroke to decrease the volume of the
first chamber (13) and enable the opening of the delivery valve
(15), flow regulation means (29; 43) being provided in order
selectively to control the opening of the delivery valve (15)
during the return stroke.
10. A fuel pump as claimed in claim 9, in which the flow regulation
means (29) comprises further actuator means (30) adapted to open
the intake valve (14) during the return stroke, the delivery valve
(15) being configured to open, during the return stroke, only when
the intake valve (14) is closed.
11. A fuel pump as claimed in claim 10, in which the further
actuator means (30) comprise an electromagnetic actuator.
12. A fuel pump as claimed in claim 9, in which the flow regulation
means (43) comprise a supply valve (43) adapted selectively to
control the supply of oil to the second chamber (20).
13. A fuel pump as claimed in claim 12, in which the supply valve
(43) comprises a shutter (51), third thrust means (53) adapted
normally to maintain the shutter (51) in a position closing the
supply valve (43) and fourth thrust means (50) adapted to displace
the shutter (51) from the closed position to an open position of
the supply valve (43).
14. A fuel pump as claimed in claim 13, in which the fourth thrust
means (50) comprise a further electromagnetic actuator.
15. A fuel pump as claimed in claim 13, in which the third thrust
means (53) are calibrated in order to maintain the shutter (51) in
the closed position with a force which is in all cases lower than
the force of opposite direction exerted on the shutter (51) by the
oil contained in the second chamber (20) when the value of the
pressure of the oil within this second chamber (20) is
substantially equal to a predetermined value.
16. A fuel pump as claimed in claim 1, in which the second chamber
(20) is provided with a plurality of channels (42) for the passage
of the oil provided on the wall (41).
Description
[0001] The present invention relates to a fuel pump for an internal
combustion engine.
[0002] The present invention relates more particularly to a fuel
pump for a unit for the direct injection of fuel, in this case
petrol, to which the following description will refer without
entering into superfluous detail.
BACKGROUND OF THE INVENTION
[0003] In the sector of direct petrol injection units, it is known
to use a petrol pump of the type comprising a cylinder having a
predetermined longitudinal axis, a piston mounted to slide within
the cylinder and actuator means adapted to provide the piston with
an alternating rectilinear movement along this cylinder.
[0004] The piston comprises an active end surface which is disposed
transversely with respect to the above-mentioned axis and defines,
together with the cylinder, a first variable-volume chamber adapted
to contain the petrol, is configured so as to define, together with
the cylinder, a second chamber of substantially constant volume
adapted to contain oil, and is lastly provided with an annular
gasket keyed on the piston in order to separate the first chamber
from the second chamber in a leak-tight manner.
[0005] Since the piston has to have a diameter substantially equal
to a diameter of the cylinder in order to reduce leakage of the
petrol and oil along the piston, known petrol pumps of the type
described above have some drawbacks due chiefly to the fact that
the contaminant particles which are inevitably present within the
cylinder may cause the piston to jam within this cylinder.
[0006] Known pumps of the type described above also have a further
drawback as the presence of the above-mentioned contaminant
particles entails relatively high wear of the annular gasket.
[0007] U.S. Pat. No. 5,520,523-A1 discloses a diaphragm-type pump
including a disk-like diaphragm made of an elastic material which
is held between an upper housing and a lower housing. In this
diaphragm-type pump, the diaphragm, which has a flat shape before
it is mounted in the pump, is bent along a diaphragm stopper and
mounted in the pump; consequently, an urging force is constantly
applied to the diaphragm in such a direction as to press it on the
diaphragm stopper. The diaphragm is deformed in response to
reciprocation of a plunger, and when the plunger reaches the bottom
dead center and a cylinder chamber is decreased in pressure, the
diaphragm is pressed on the diaphragm stopper by the urging force
toward the diaphragm stopper and a feed pressure of a feed pump
[0008] U.S. Pat. No. 6,071,089-A1 discloses a high pressure
hydraulic diaphragm pump having a pressure chamber on one side of a
diaphragm and a fluid delivery chamber on the other side of the
diaphragm with a reciprocating piston assembly including a piston
member being provided for pressurizing the hydraulic fluid in the
pressure chamber and having the pressure chamber connected with a
pressure regulator which maintains the desired discharge pressure
of the fluid and in which the piston assembly is combined with a
diaphragm positioning mechanism for maintaining the diaphragm at a
desired position relative to the piston member so as to assure full
stroke of the diaphragm during normal operation of the pump
[0009] GB-849557-A discloses a hydraulically actuated diaphragm
pump; a hydraulic pressure chamber is placed in communication with
a hydraulic reservoir by means of a valve secured to a diaphragm
and having a part open to the chamber and connecting with either of
parts which communicate through valves with the reservoir so that
excess liquid is discharged or deficiency made up. In the event of
excess pressure on the pumping side of the diaphragm a face carried
by the diaphragm seats on a face on the housing. The pumping
chamber communicates through a pair of inlet valves with inlet
conduits and through a pair of outlet valves with outlet conduits.
The pump may comprise a plurality of diaphragm chambers.
[0010] U.S. Pat. No. 6,554,578-B1 relates to a diaphragm pump with
a device for controlling the position of a diaphragm separating the
conveying chamber from the displacement chamber. As a replacement
of the mechanical control of the refilling process, a pressure
sensor is arranged in the displacement chamber, which is connected
with an evaluation unit designed for generating a refill signal,
which is switched so it actuates a refill valve through an
operative connection; advantageously, a second sensor for detecting
the piston travel is provided, whose signal is linked with the
signal from the pressure sensor.
SUMMARY OF THE INVENTION
[0011] The object of the present invention is to provide a fuel
pump for an internal combustion engine which is free from the
drawbacks described above and is simple and economic to embody.
[0012] The present invention therefore relates to a fuel pump for
an internal combustion engine as claimed in the attached
claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The present invention is described below with reference to
the accompanying drawings, which show non-limiting embodiments
thereof, and in which:
[0014] FIG. 1 is a diagrammatic longitudinal section through a
preferred embodiment of the fuel pump of the present invention;
[0015] FIG. 2 is a diagrammatic longitudinal section through a
variant of the fuel pump of FIG. 1;
[0016] FIG. 3 is a plan view of a detail of FIG. 2.
DETAILED DESCRIPTION OF THE INVENTION
[0017] In FIG. 1, a petrol pump for an internal combustion engine
(not shown) of the direct petrol injection type is shown overall by
1.
[0018] The pump 1 comprises a cylindrical body 2 having a
predetermined longitudinal axis 3 and comprising, in turn, a first
plate 4 which is coaxial with respect to the axis 3, is limited
axially by two plane surfaces 5, 6 at right angles to the axis 3
and has a cylindrical cavity 7 which opens externally at the
location of the plate 6 and is closed by a second plate 8 disposed
in contact with the surface 6 and secured to the plate 4.
[0019] The plate 8 is bounded axially by two plane surfaces 9, 10
at right angles to the axis 3, the surface 9 being disposed in
contact with the surface 6 and having a cylindrical cavity 11 which
is obtained through the plate 8 coaxially with respect to the axis
3, and opens externally at the location of the both the surface 9
and the surface 10.
[0020] The cavities 7 and 11 are separated from one another by
means of a deformable diaphragm 12 which is made from stainless
steel, is welded between the plates 4 and 8 at the location of its
peripheral edge, and defines, together with the cavity 7, a
variable-volume chamber 13 adapted to contain the petrol provided
with an intake ball valve 14 and a delivery ball valve 15 of known
type.
[0021] The cavity 11 comprises a widened portion 16 disposed in a
position facing the diaphragm 12 and a contracted portion 17
engaged in a sliding manner by a piston 18 having an active end
surface 19 which extends at right angles to the axis 3 in order
axially to limit this piston 18 and defines, together with the
cavity 11 and the diaphragm 12, a chamber 20 of substantially
constant volume adapted to contain the oil of the engine (not
shown).
[0022] The chamber 20 is provided with an intake valve 21 of known
type adapted to supply the chamber 20 with a quantity of oil
substantially equal to the quantity of oil emerging from this
chamber 20 by drawing between the portion 17 and the piston 18 and
therefore adapted to maintain the quantity of oil in the chamber 20
constant, and a maximum pressure valve 22 adapted to be disposed in
an open position when the value of the oil pressure within the
chamber 20 is substantially equal to a predetermined value.
[0023] The piston 18 may move along the portion 17 in order to
perform, under the thrust of an actuation device 23, an alternating
rectilinear movement comprising an outward stroke, during which the
diaphragm 12 is displaced from an operational pumping position
(shown by a continuous line in the accompanying Figure) to a rest
position (shown in dashed lines in the accompanying Figure) and the
volume of the chamber 13 increases in order to cause the opening of
the intake valve 14, and a return stroke, during which the
diaphragm 12 is displaced from its rest position to its operational
pumping position and the volume of the chamber 13 decreases in
order to cause the opening of the delivery valve 15.
[0024] The device 23 comprises a spring 24, which is keyed on the
piston 18 coaxially with respect to the axis 3, and is interposed
between the plate 8 and the piston 18 in order to provide this
piston 18 with its outward stroke, and a cam 25 which is mounted in
a rotary manner to rotate about its longitudinal axis 26
perpendicular to the axis 3, and cooperates with a tappet roller 27
coupled in a rotary and axially fixed manner to the piston 18 in
order to provide this piston 18 with its return stroke.
[0025] The diaphragm 12, the chamber 20, the piston 18 and the
actuation device 23 form a pumping device 28 adapted to use the oil
in the chamber 20 to deform the diaphragm 12 and thus to vary the
volume of the chamber 13. The deformation of the diaphragm 12 is
controlled selectively by providing the diaphragm 12 and the piston
18 such that the value of the ratio between the surface of the
diaphragm 12 and the surface of the face 19 is at least equal to
five.
[0026] The opening of the valve 15 during the return stroke of the
piston 18 and, therefore, the quantity of petrol supplied via the
valve 15 at each operating cycle of the pump 1 are controlled
selectively by a flow regulation device 29 comprising an
electromagnetic actuator 30 mounted at the location of the valve
14. The actuator 30 comprises an output rod 31 which extends within
the valve 14 parallel to the axis 3, and is mounted in a sliding
manner in order to move between an operating position (shown in
dashed lines in the accompanying Figure), in which the rod 31 is
disposed so as to cause the opening of the valve 14, and a rest
position (shown in continuous lines in the accompanying Figure), in
which the rod 31 is disposed so as to enable the closure of the
valve 14.
[0027] Since the valve 15 is calibrated so as to open, during the
return stroke of the piston 18, only when the valve 14 is closed,
the actuation of the actuator 30 makes it possible selectively to
control the opening of this valve 15.
[0028] The operation of the pump 1 can be readily deduced from the
above description and no further explanation is required.
[0029] The variant shown in FIG. 2 relates to a pump 32 which
differs from the pump 1 in that the intake ball valve 14 is
replaced by an intake valve 33 comprising a plate 34 which is
mounted at right angles to a longitudinal axis 35 of a duct 36
supplying petrol to the chamber 13 and is provided with a plurality
of supply holes 37 obtained through the plate 34 parallel to the
axis 35, and a deformable sheet 38 which is secured to the plate 34
at its peripheral edge, is normally disposed in a position closing
(FIG. 2) the holes 37, and moves, during the outward stroke of the
piston 18, from the closed position to an open position (not shown)
of these holes 37 in order to enable the petrol to enter the
chamber 13.
[0030] The pump 32 also differs from the pump 1 in that the
diaphragm 12 comprises a central portion 39 clamped between two
substantially cup-shaped stiffening members 40, one of which
(designated hereafter by 40a) is disposed in the chamber 13 and the
other of which (designated hereafter by 40b) is disposed in the
chamber 20.
[0031] As shown in FIG. 2, the member 40b is shaped so as to be
disposed in contact, during the outward stroke of the piston 18,
with a wall 41 bounding the chamber 20 and thus to control the
deformation of the diaphragm 12 and is further provided with a
plurality of radial channels 42 adapted to enable the oil to pass
through the member 40b when this member 40b is disposed in contact
with the wall 41.
[0032] According to a variant which is not shown, the channels 42
are replaced by a plurality of supply channels obtained on the wall
41.
[0033] The pump 32 lastly differs from the pump 1 in that the
intake valve 21, the maximum pressure valve 22 and the
electromagnetic actuator 30 are replaced by a single
electromagnetic valve 43 mounted within a cavity 44 which is
provided in the plate 8, has a longitudinal axis 45 transverse to
the axis 3 and communicates with the chamber 20 via a hole 46
obtained through this plate 8.
[0034] The valve 43 comprises an outer tubular jacket 47 which is
substantially cup-shaped, is housed within the cavity 44 coaxially
with respect to the axis 45, and is provided with a plurality of
radial holes 48 uniformly distributed about the axis 45 in order to
enable oil to be supplied into this jacket 47 and with an axial
hole 49.
[0035] The jacket 47 is closed axially by an electromagnet 50 and
houses a ball shutter 51 which is coupled in a sliding manner to
the jacket 47 and has a ball 52 closing the hole 49. The shutter 51
and therefore the ball 52 are normally disposed, under the thrust
of a spring 53 interposed between the electromagnet 50 and the
shutter 51, in a position (FIG. 2) closing the hole 49, and are
displaced by the electromagnet 50, against the action of the spring
53, into a position (not shown) opening the hole 49 in which the
oil is supplied to the hole 49 by means of a plurality of supply
channels 54 obtained on the outer surface of the ball 52 parallel
to the axis 45.
[0036] In an initial phase of filling of the chamber 20, the
electromagnet 50 is excited in order to displace the shutter 51 and
therefore the ball 52 into their position opening the hole 49 so as
to supply a predetermined initial quantity of oil to the hole 46
and therefore to the chamber 20. The initial quantity of oil
supplied to the chamber 20 may be maintained constant, in use, by
selectively opening the valve 43 in order to supply the chamber 20
with a quantity of oil substantially equal to the quantity of oil
emerging from time to time from the chamber 20 as a result of
leakage between the portion 17 and the piston 18.
[0037] It will be appreciated from the above that the pressure
exerted on the diaphragm 12 during the return stroke of the piston
18 and therefore the displacement of the diaphragm 12 from its rest
position to its operational pumping position, i.e. the opening of
the delivery valve 15, depend on the quantity of oil contained in
the chamber 20 and are selectively controlled by means of the valve
43.
[0038] The positioning of the valve 43 within the oil supply
circuit to the chamber 20 makes it possible to supply the petrol
suctioned into the chamber 13 directly to the delivery valve 15 and
to prevent, in contrast to what happens when using the
electromagnetic actuator 30, the losses of energy deriving from the
reflux of the petrol suctioned into the chamber 13 through the
intake valve 14.
[0039] The spring 53 is also calibrated so as to thrust the shutter
51 into its position closing the hole 49 with a force which is in
all cases lower than the force of opposite direction exerted on the
shutter 51 by the oil contained in the chamber 20 and in the hole
46 when the value of the pressure of the oil in the chamber 20 is
substantially equal to a predetermined value. In this way, the oil
is discharged through the holes 48 thus avoiding breakages of the
diaphragm 12.
* * * * *