IT201800003229A1 - PUMPING UNIT FOR VEHICLES, IN PARTICULAR TO SUPPLY FUEL, PREFERABLY DIESEL, TO AN INTERNAL COMBUSTION ENGINE - Google Patents

Description

DESCRIPTION

of the patent for industrial invention entitled:

"PUMPING GROUP FOR VEHICLES, IN PARTICULAR TO FEED FUEL, PREFERABLY DIESEL, TO AN INTERNAL COMBUSTION ENGINE"

The present invention relates to a pumping unit for vehicles, in particular for supplying fuel, preferably diesel oil, to an internal combustion engine.

The present invention finds advantageous application in pumping units for feeding fuel, preferably diesel oil, to an internal combustion engine, to which the following discussion will make explicit reference without thereby losing generality.

The pumping unit comprises a high pressure pump, for example a piston pump, suitable for supplying fuel to an internal combustion engine; a pre-feed pump, for example a gear pump, adapted to feed fuel from a containment tank to the piston pump; and a hydraulic circuit to connect together the containment tank, the pre-feed pump, the high pressure pump, and the internal combustion engine.

In this case, the piston pump comprises a pump body, and at least one cylinder formed in the pump body and engaged in a sliding manner by a piston.

The cylinder is associated with a fuel intake valve in the cylinder and a fuel delivery valve to the internal combustion engine.

The pumping unit also comprises an actuation device for moving the piston along the cylinder with a reciprocating rectilinear motion comprising a stroke of intake of the fuel in the cylinder and a stroke of delivery of the fuel to the internal combustion engine.

The actuation device comprises a transmission shaft to move the piston with its delivery stroke and a spring interposed between the pump body and the piston to move the piston itself with its intake stroke.

Generally, the hydraulic circuit is provided with at least one restriction to control the correct supply of fuel along the hydraulic circuit itself.

Since the choke has a fixed geometry, the flow rate of fuel fed through the choke depends solely on, and is directly proportional to, the fuel supply pressure.

Known pumping units of the type described above have some drawbacks mainly deriving from the fact that, when the fuel supply pressure is relatively high, the fuel flow rate fed along the hydraulic circuit is relatively high and not compatible with the operating parameters of the internal combustion engine.

The object of the present invention is to provide a pumping unit for vehicles, in particular for feeding fuel, preferably diesel, to an internal combustion engine, which is free from the drawbacks described above and which is simple and economical to implement.

According to the present invention, a pumping unit for vehicles is provided, in particular for feeding fuel, preferably diesel oil, to an internal combustion engine, as claimed in the attached claims.

The present invention will now be described with reference to the attached drawings, which illustrate a non-limiting example of embodiment, in which:

Figure 1 is a hydraulic diagram of a preferred embodiment of the pumping unit of the present invention; And

Figure 2 is a schematic side view, with parts in section, of a detail of the pumping unit of Figure 1.

With reference to Figure 1, 1 indicates, as a whole, a pumping unit for supplying fuel, preferably diesel, from a containment tank 2 to an internal combustion engine 3, in this case a Diesel internal combustion engine, of a vehicle (not shown).

The engine 3 comprises a fuel distribution manifold 4, commonly indicated with the term "common rail", and a plurality of injectors 5 connected to the manifold 4 and adapted to atomize the fuel inside the relative combustion chambers (not illustrated) of the motor 3 itself.

The pumping unit 1 comprises a high pressure pump 6, ie a piston pump, for supplying fuel to the engine 3; and a low pressure or pre-feed pump 7, i.e. a gear pump, for example electrically operated, to feed the fuel from the tank 2 to the pump 6.

The pump 6 comprises a pump body 8 and, in this case, two cylinders 9, which are formed in the pump body 8, and have respective longitudinal axes 10 substantially parallel to each other.

According to a variant not shown, the number of cylinders 9 is different from two and the axes 10 are not parallel to each other.

The cylinders 9 are engaged in a sliding manner by respective movable pistons 11, under the thrust of an actuation device 12, with a reciprocating rectilinear motion comprising an intake stroke of the fuel in the relative cylinders 9 and a stroke of delivery of the fuel to the engine 3 .

The device 12 comprises a cam transmission shaft 13, which is housed in a first containment chamber 14 obtained in the pump body 8, and is adapted to move the pistons 11 with their delivery stroke.

The device 12 also comprises, for each piston 11, a respective spring (not shown), which is housed in a second containment chamber (not shown) obtained in the pump body 8, and is adapted to move the piston 11 itself with its suction stroke.

Regarding the above, it should be noted that the shaft 13 is configured in such a way as to simultaneously move a piston 11 with its suction stroke and the other piston 11 with its delivery stroke.

The pumping unit 1 also comprises a first hydraulic circuit 15 comprising, in turn, a first branch 16 for connecting the tank 2 and the pump 7 together; a second branch 17 for connecting pump 7 and pump 6 together; and a third branch 18 to connect the pump 6 and the manifold 4 together.

The branch 17 is provided with a filtering device 19 for filtering the fuel fed to the cylinders 9, and also has a metering solenoid valve 20 mounted downstream of the device 19 in a direction 21 for the advancement of the fuel along the branch 17 to control selectively the instantaneous flow rate of fuel supplied to the pump 6 as a function of the values of a plurality of operating parameters of the engine 3.

The branch 17 and the branch 18 are connected to each cylinder 9 by means of an intake valve 22 and, respectively, a delivery valve 23.

The circuit 15 also comprises a fourth branch 24, which extends between the manifold 4 and the branch 16, and allows the flow of fuel in excess of that necessary for the injectors 5 to be discharged into the branch 16; and a fifth branch 25, which extends between the branch 17 and the branch 24, and is connected to the branch 17 downstream of the solenoid valve 20 in the direction 21 to feed the fuel leaking through the solenoid valve 20 to the inlet of the pump 7 when the solenoid valve 20 itself is closed.

The pumping unit 1 also comprises, in this case, a second hydraulic circuit 26 provided with a feed pump (not shown) able to feed lubricating oil from a containment tank (not shown) to the chamber 14 in order to lubricate the transmission shaft 13, in particular a pair of bearings supporting the transmission shaft 13.

As shown in Figure 2, at least one of the circuits 15, 26 is provided with a flow regulator device 27 mounted inside a supply duct 28 for the circuit 15, 26 itself.

The device 27 comprises a plate 29 hinged to the duct 28 to rotate, with respect to the duct 28 itself, around a fulcrum axis 30 between a first operating position (shown in a continuous line in Figure 2) and a second operating position (shown in line dashed in figure 2).

The duct 28 has a cross section with a greater passage when the plate 29 is disposed in its first operative position and a cross section with a smaller passage when the plate 29 is arranged in its second operative position.

The plate 29 is moved, and normally maintained, in its first operating position by a spring 31 interposed between the duct 28 and the plate 29 itself, and is moved to its second operating position by the fuel or lubricating oil fed along the duct 28. .

It should also be noted that the plate 29 is mounted inside the duct 28 so as to be moved around the axis 30 counterclockwise by the spring 31 and clockwise by the fuel or lubricating oil fed along the duct. 28.

In use, the spring 31 is preloaded in such a way that: when the pressure of the fuel or lubricating oil acting on the plate 29 is less than a determined threshold value, the plate 29 is placed in its first operating position; And

when the pressure of the fuel or lubricating oil acting on the plate 29 is greater than the aforementioned threshold value, the plate 29 is placed in its second operating position.

In other words, the plate 29 moves around the axis 30 starting from the first operating position in order to selectively adjust the cross section of the passage of the duct 28 according to the pressure of the fuel or lubricating oil acting on the plate 29 itself.

Obviously, according to variants not shown, the flow rate regulator device 27 can be used in any pumping unit of the vehicle (not shown), in which it is necessary to selectively control the flow rate of fluid supplied to a specific user.

The pumping unit 1 has some advantages mainly deriving from the fact that the flow regulator device 27 allows to selectively control the cross section of the passage of the duct 28 as a function of the supply pressure of the fluid acting on the plate 29, in particular to reduce the section transversal passage of the duct 28 as the supply pressure of the fluid acting on the plate 29 itself increases.

Claims (1)

CLAIMS 1.- Pumping unit for vehicles, in particular for feeding fuel, preferably diesel oil, to an internal combustion engine, the pumping unit comprising at least one pump (7) for feeding a fluid, in particular a liquid fluid, from a tank containment (2) to a user (3; 14) of a vehicle; and a hydraulic circuit (15; 26) to connect the containment tank (2), the pump (7), and the user (3; 14) together; the hydraulic circuit (15; 26) comprising at least one feed duct (28) and a flow rate regulator device (27) for selectively controlling a flow rate of the fluid along the feed duct (28) itself; and being characterized in that the flow rate regulator device (27) comprises a shutter (29) movable inside the supply duct (28) to selectively control a passage cross section of the supply duct (28) as a function of a fluid pressure acting on the shutter (29) itself. 2.- Pumping unit according to claim 1, in which the shutter (29) is movable inside the supply duct (28) between at least two operating positions, in which the supply duct (28) has different cross sections of fluid passage. 3.- Pumping unit according to claim 1 or 2, in which the shutter (29) is arranged in a first operative position when the pressure of the fluid in the supply duct (28) is lower than a determined threshold value, and in a second operative position when the pressure of the fluid in the supply duct (28) is greater than the threshold value itself. 4.- Pumping unit according to any one of the preceding claims and further comprising a spring (31) for moving and normally maintaining the shutter (29) in a first operating position when the pressure of the fluid acting on the shutter ( 29) is less than a determined threshold value; the shutter (29) being configured to move from its first operating position to a second operating position when the pressure of the fluid acting on the shutter (29) is greater than the threshold value itself. 5.- Pumping unit according to any of the previous claims, in which the shutter (29) comprises a plate hinged inside the supply duct (28) to rotate around a fulcrum axis (30). 6.- Pumping unit according to Claim 5 and further comprising a spring (31) interposed between the plate and the supply duct (28) to move and normally maintain the plate in a first operating position. 7.- Pumping unit according to claim 6, in which the plate is hinged inside the supply duct (28) to rotate under the thrust of the spring (31) in a first direction of rotation and under the thrust of the fluid in a second direction of rotation opposite to the first direction of rotation. 8.- Pumping unit according to any one of the preceding claims and comprising a high pressure pump (6) for feeding fuel to an internal combustion engine (3), and a pre-feeding pump (7) for feeding fuel from the containment tank (2) to the high pressure pump (6); the flow rate regulator device (27) being mounted along the hydraulic circuit (15) configured to connect together the containment tank (2), the pre-supply pump (7), the high pressure pump (6), and the motor internal combustion (3). 9.- Pumping unit according to any one of claims 1 to 7 and comprising a high pressure pump (6) for feeding fuel to an internal combustion engine (3), and a pre-feeding pump (7) for feeding the fuel from the containment tank (2) to the high pressure pump (6); the flow rate regulator device (27) being mounted along the hydraulic circuit (26) configured to supply lubricating oil to the high pressure pump (6).