IT202000005560A1 - PUMPING GROUP TO FEED FUEL, PREFERABLY DIESEL, TO AN INTERNAL COMBUSTION ENGINE - Google Patents

Description

DESCRIPTION

of the patent for industrial invention entitled:

? PUMPING GROUP TO FEED FUEL, PREFERABLY DIESEL OIL, TO AN INTERNAL COMBUSTION ENGINE?

The present invention? relating to a pumping unit for feeding fuel, preferably diesel, to an internal combustion engine.

In particular, the present invention? relating to a pumping unit of the type comprising a high pressure pump, normally a piston pump, suitable for supplying fuel to an internal combustion engine; a low pressure pump, normally 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 low pressure pump, the high pressure pump, and the internal combustion engine.

The piston pump comprises a pump body; at least two cylinders formed in the pump body and slidingly engaged by respective pistons; and an actuation device for moving the pistons along the relative cylinders with a reciprocating rectilinear motion comprising a stroke of intake of the fuel in the cylinders and a stroke of delivery of the fuel to the internal combustion engine.

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

The driving device? configured in such a way as to simultaneously move one piston with its suction stroke and the other piston with its delivery stroke.

The hydraulic circuit comprises a first branch for connecting the containment tank and the gear pump to each other; a second branch for connecting the gear pump and the piston pump together; and a third branch for connecting the piston pump and the internal combustion engine together.

The second branch comprises a feed manifold and, for each cylinder, a respective intake duct for connecting the feed manifold with the cylinder itself.

Generally, the hydraulic circuit also comprises a metering solenoid valve mounted along the feed manifold to selectively control the instantaneous flow rate of fuel supplied to the piston pump as a function of the values of a plurality of fuel. of operating parameters of the internal combustion engine.

The hydraulic circuit also comprises a fourth branch, which extends between the internal combustion engine and the containment tank, and allows the fuel flow in excess of that necessary for the internal combustion engine to be discharged into the containment tank.

The hydraulic circuit also has a fifth branch, which extends between the second branch and the fourth branch, and? connected to the second branch upstream of the metering solenoid valve in a direction of advancement of the fuel along the second branch itself.

The fifth branch? equipped with an overflow valve to discharge in the fourth branch and, therefore, in the containment tank at least part of the fuel flow in excess of that supplied to the piston pump when the metering solenoid valve? open and substantially the entire flow of fuel coming from the gear pump when the dosing solenoid valve? closed.

The hydraulic circuit also has a sixth branch, which extends between the second branch and the inlet of the gear pump, and connected to the second branch downstream of the metering solenoid valve in a direction of advancement of the fuel along the second branch itself.

The sixth branch? equipped with a drain valve to discharge the fuel leaking through the dosing solenoid valve at the inlet of the gear pump when the dosing solenoid valve? closed.

The known pumping units of the type described above have some drawbacks mainly deriving from the fact that the pump body? made of aluminum for foundry, it must be subjected to machining by chip removal for the realization of part of the hydraulic circuit, and is, therefore, relatively complex, heavy, and expensive.

Purpose of the present invention? to provide a pumping unit for supplying fuel, preferably diesel oil, 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 is provided for feeding fuel, preferably diesel oil, to an internal combustion engine as claimed in the attached claims.

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

figure 1? a hydraulic diagram of a preferred embodiment of the pumping unit of the present invention;

figure 2? a schematic sectional view, with parts removed for clarity, of a pumping unit according to the state of the art;

figure 3? a schematic perspective view of a detail of the pumping unit of Figure 1; And

Figures 4 and 5 are two schematic perspective views, with parts removed for clarity, of a detail of Figure 3.

With reference to Figure 1, with 1? indicated, as a whole, a pumping unit for feeding fuel, preferably diesel oil, from a containment tank 2 to an internal combustion engine 3, in this case a Diesel internal combustion engine.

The engine 3 comprises a fuel distribution manifold 4, commonly indicated with the term? Common rail ?, and a plurality of? of injectors 5 connected to the manifold 4 and adapted to nebulize the fuel inside the relative combustion chambers (not shown) of the engine 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? different from two, in particular equal to one, 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 for moving the pistons 11 with their delivery stroke and, for each piston 11, a respective spring 14 (Figure 2) for moving the piston 11 itself with its intake stroke.

About the above? it should be noted that the tree 13? 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 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.

Branch 17? 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 selectively control the instantaneous flow rate of fuel fed to the pump 6 as a function of the values of a plurality of fuel of motor operating parameters 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 fuel flow in excess of that necessary for the injectors 5 to be discharged into the branch 16.

The circuit 15 also has a fifth branch 25, which extends between the branch 17 and the branch 16,? connected to branch 17 downstream of the solenoid valve 20 in direction 21, and d? provided with a discharge valve 26 to feed the fuel leaking through the solenoid valve 20 to the inlet of the pump 7 when the solenoid valve 20 itself? closed.

The circuit 15 also has a sixth branch 27, which extends between the branch 17 and the branch 24,? connected to branch 17 upstream of the solenoid valve 20 in direction 21, and d? provided with an overflow valve 28 to discharge in the branch 24 and, therefore, in the tank 2 the flow of excess fuel when the solenoid valve 20? open and substantially the entire flow of fuel when the solenoid valve 20? closed.

Figure 2 illustrates an embodiment made according to the state of the art prior to the invention.

In it, the pump body 8? made of foundry aluminum,? provided with a central hole 29 having a longitudinal axis 30 perpendicular to the axes 10, and? furthermore provided with two lateral holes 31 coaxial to the same axes 10.

Each hole 31? facing the hole 29, and houses inside a tubular head 32, which? fixed to the pump body 8, protrudes inside the hole 31, and extends around the relative axis 10.

Each head 32 defines a relative cylinder 9,? engaged in a sliding manner by a relative piston 11, it houses a relative intake valve 22 and a relative delivery valve 23, and? closed by a relative lid 33.

The device 12 comprises, for each piston 11, a respective tubular sleeve 34, which? engaged in a sliding manner inside the relative hole 31, extends around the relative cylinder 9, and has an annular flange 35, which protrudes radially inside the sleeve 34 to divide it into two cylindrical portions 36, 37, of which the portion 37? facing hole 29.

The device 12 also comprises, for each sleeve 34, a respective tappet 38 comprising a substantially cylindrical-shaped coupling block 39, which? inserted inside the relative portion 37,? disposed in contact with the relative flange 35, and d? blocked by interference inside the relative portion 37 itself.

The tappet 38 further comprises a tappet roller 40, which protrudes from the block 39 towards the hole 29, and? rotatably coupled to block 39 to rotate, with respect to block 39 itself, around its own rotation axis 41 substantially perpendicular to the relative axis 10.

The portion 36 houses internally an annular plate 42, which extends around the piston 11 coaxially to the axis 10, and has an internal perimeter edge facing axially to the head of the piston 11 itself and an external perimeter edge facing the flange 35.

The spring 14 associated with each piston 11? mounted inside the relative hole 31, and extends between the relative head 32 and the relative sleeve 34 coaxially to the relative axis 10.

The springs 14 are interposed between the relative heads 32 and the relative plates 42 to move, and normally maintain, the plates 42 in contact with the relative flanges 35 and the relative pistons 11, the pistons 11 in contact with the relative tappets 38, and the relative rollers 40 in contact with respective cams 43 obtained on an external surface of shaft 13, which is mounted through the hole 29 to rotate, with respect to the pump body 8, about the axis 30.

Figures 3, 4, and 5 illustrate a preferred embodiment of the invention. The elements common to the embodiment illustrated in Figures 3, 4, and 5 and to the embodiment illustrated in Figure 2 will be identified with the same reference number.

The pumping unit 1 comprises a metal support structure 44 integrated in a metal foam matrix 45.

Structure 44 includes:

a tubular element 46 for housing the shaft 13 inside;

for each head 32, a respective tubular element 47, which protrudes from element 46, communicates with element 46, and houses inside an assembly defined by head 32 and relative piston 11, spring 14, sleeve 34, tappet 38, and plate 42;

for each head 32, a respective pair of threaded tubular elements 48, which are distributed around the relative axis 10, and are able to be engaged by respective tightening screws (not shown) suitable for locking the head 32 on the element 47;

two annular coupling flanges 49, 50 formed around the ends? free of the element 46 to couple with a coupling flange (not shown) of the motor 3 and, respectively, with a coupling flange (not shown) of the pump 7; a plurality? of threaded tubular elements 51 distributed around the flange 49 and able to be engaged by respective tightening screws (not shown) to lock the motor 3 on the structure 44;

a plurality? of threaded tubular elements 52 distributed around the flange 50 and able to be engaged by respective tightening screws (not shown) to lock the pump 7 on the structure 44;

a pair of tubular elements 53 and an elongated channel 54 connected to each other to define at least part of the branch 16;

a pair of tubular elements 55 connected to each other to define at least part of a portion of the branch 17 extending between the pump 7 and the filtering device 19;

a tubular element 56 defining at least part of a portion of the branch 17 extending between the device 19 and the metering solenoid valve 20;

a tubular element 57, which defines part of a portion of the branch 17 extending between the solenoid valve 20 and the cylinders 9, and connected with element 56 at a seat 58 for the solenoid valve 20 itself;

a plurality? of tubular elements 59 distributed around the seat 58 and able to be engaged by respective tightening screws (not shown) to lock the solenoid valve 20 on the structure 44;

for each head 32, a respective tubular element 60, which? connected to the element 57, and defines at least part of a fuel supply duct from the element 57 to the relative intake valve 22;

a tubular element 61, which extends between the element 57 and the channel 54, defines the branch 25, and houses the discharge valve 26 inside it;

a pair of tubular elements 62, which are connected to the seat 58, define at least part of the branch 27, and house the overflow valve 28 inside;

a tubular element 63 connected to the valve 28 and to the element 46 to feed the fuel into the element 46 itself;

a pair of tubular elements 64 connected to the element 46 and to the branch 24 to discharge the fuel leaking into the tank 2 through the support bearings of the shaft 13;

a plurality? of tubular elements 65 connected to each other and to element 46 to define a lubrication channel for the support bearings of the shaft 13; and a tubular element 66 defining a fuel recirculation channel.

The structure 44 also comprises a plurality of of tie rods 67 to connect together the elements 46-48, 51-53, 55-57, and 59-66, the flanges 49, 50, the channel 54, and the seat 58.

The structure 44 is arranged inside a mold (not shown) with the flanges 49 and 50, the channel 54, and the ends? elements 46, 47, 48, 51, 52, 53, 55, 56, 58, 59, 60, 62, 64 in contact with the walls of the mold (not shown) itself.

According to a variant not shown, the channel 54 and the ends? elements 46, 47, 48, 51, 52, 53, 55, 56, 58, 59, 60, 62, 64 are plugged before inserting the structure 44 into the mold (not shown).

Once inserted into the mold (not shown), the structure 44 is stabilized inside the matrix 45.

The pumping unit 1 has some advantages mainly deriving from the fact that the structure 44 has a relatively high mechanical resistance, does not require machining by chip removal, and is therefore relatively simple and economical and that the matrix 45 guarantees relatively acoustic emissions. reduced and has a relatively low weight.

Claims (1)

CLAIMS 1.- Pumping group for feeding fuel, preferably diesel oil, to an internal combustion engine (3), the pumping group comprising a high pressure pump (6) for feeding fuel to the internal combustion engine (3), the pump high pressure (6) comprising, in turn, at least one head (32) defining a cylinder (9) and a piston (11) slidably engaged in the cylinder (9) itself; a low pressure pump (7) for supplying fuel from a containment tank (2) to the high pressure pump (6); a hydraulic feed circuit (15) for feeding the fuel from the containment tank (2) to the internal combustion engine (3); and an actuation device (12) for moving each piston (11) with a reciprocating rectilinear motion along the relative cylinder (9); and being characterized in that it further comprises a support structure (44) comprising, in turn, a plurality of of tubular elements defining at least part of the hydraulic supply circuit (15), a seat for the head (32), and a seat for at least part of the actuation device (12), and a metal foam matrix (45) formed around the support structure (44) itself. 2.- Pumping unit according to Claim 1, in which the support structure (44) further comprises a plurality of elements. of tie rods (67) to connect at least part of the tubular elements together. 3.- Pumping unit according to Claim 1 or 2, wherein the support structure (44) comprises a first tubular element (46) for housing inside a transmission shaft (13) of the actuation device (12) and , for each head (32), a respective second tubular element (47), which protrudes from the first tubular element (46) to define the seat for the head (32), and houses inside a tappet (38) of the device drive (12) interposed between the transmission shaft (13) and the relative piston (11). 4.- Pumping unit according to Claim 3, wherein the support structure (44) further comprises, for each second tubular element (47), a respective plurality of elements. of third tubular elements (48), which are distributed around the second tubular element (47), and are able to be engaged by respective first tightening screws to lock the relative head (32) on the second tubular element (47) itself. 5.- Pumping unit according to Claim 3 or 4, in which the support structure (44) further comprises a plurality of elements. of fourth tubular elements (52), which are distributed around a first extremity? free of the first tubular element (46), and are able to be engaged by respective second tightening screws to lock the low pressure pump (7) on the support structure (44). 6.- Pumping unit according to any one of claims 3 to 5, in which the support structure (44) further comprises a plurality of elements. of fifth tubular elements (51), which are distributed around a second extremity? free of the first tubular element (46), and are able to be engaged by respective third tightening screws to lock the internal combustion engine (3) on the support structure (44). 7.- Pumping unit according to any one of claims 3 to 6, wherein the support structure (44) further comprises a pair of coupling flanges (49, 50), which extend around the ends? of the first tubular element (46), and are able to couple with corresponding coupling flanges of the internal combustion engine (3) and of the low pressure pump (7). 8.- Pumping unit according to any one of claims 3 to 7, wherein the high pressure pump (6) comprises two heads (32) and, therefore, two cylinders (9); the support structure (44) further comprising at least a sixth tubular element (57) defining a manifold for feeding fuel to the cylinders (9) and, for each cylinder (9), a respective seventh tubular element (60) for supplying the fuel from the sixth tubular element (57) to the cylinder (9) itself. 9.- Pumping unit according to claim 8, wherein the sixth tubular element (57)? configured to define a seat (58) for a metering solenoid valve (20) of the fuel to the cylinders (9). 10.- Pumping unit according to Claim 9, wherein the support structure (44) further comprises a plurality of elements. of eighth tubular elements (59) adapted to be engaged by respective fourth tightening screws to lock the metering solenoid valve (20) on the support structure (44). 11.- Pumping unit according to claim 9 or 10, wherein the support structure (44) further comprises a ninth tubular element (56) connected to the seat (58) and a tenth tubular element (55) connected to the low pressure pump (7) and adapted to feed the fuel to the ninth tubular element (56) itself. 12.- Pumping unit according to any one of claims 9 to 11, wherein the support structure (44) further comprises an eleventh tubular element (62), which? connected with the seat (58) to feed fuel from the seat (58) to the containment tank (2), and defines a seat for an overflow valve (28). 13.- Pumping unit according to claim 12, wherein the support structure (44) further comprises a twelfth tubular element (63) connected with the eleventh tubular element (62) and with the first tubular element (46) to feed the fuel into the first tubular element (46) itself. 14.- Pumping unit according to any one of claims 8 to 13, wherein the support structure (44) further comprises a thirteenth tubular element (61), which extends starting from the sixth tubular element (57) to feed the fuel to the inlet of the low pressure pump (7), and? configured to house a drain valve (26) inside. 15.- Pumping unit according to any one of claims 3 to 14, wherein the support structure (44) further comprises a fourteenth tubular element (64) connected with the first tubular element (46) to discharge into the containment (2) the fuel leaking through the support bearings of the propeller shaft (13). 16.- Pumping unit according to any one of claims 3 to 15, wherein the support structure (44) further comprises a fifteenth tubular element (53, 54) to feed the fuel from the containment tank (2) to the low pressure pump (7). 17. Pumping unit according to any one of claims 3 to 16, wherein the support structure (44) further comprises a sixteenth tubular element (65) connected to the first tubular element (46) to define at least part of a hydraulic circuit for lubricating the actuation device (12). 18. Pumping unit according to any one of claims 3 to 17, wherein the support structure (44) further comprises a seventeenth tubular element (66) defining a fuel recirculation channel through the first tubular element (46 ).