Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
  • F02M59/00—Pumps specially adapted for fuel-injection and not provided for in groups F02M39/00 -F02M57/00, e.g. rotary cylinder-block type of pumps
  • F02M59/02—Pumps specially adapted for fuel-injection and not provided for in groups F02M39/00 -F02M57/00, e.g. rotary cylinder-block type of pumps of reciprocating-piston or reciprocating-cylinder type
  • F02M59/10—Pumps specially adapted for fuel-injection and not provided for in groups F02M39/00 -F02M57/00, e.g. rotary cylinder-block type of pumps of reciprocating-piston or reciprocating-cylinder type characterised by the piston-drive
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
  • F02M59/00—Pumps specially adapted for fuel-injection and not provided for in groups F02M39/00 -F02M57/00, e.g. rotary cylinder-block type of pumps
  • F02M59/44—Details, components parts, or accessories not provided for in, or of interest apart from, the apparatus of groups F02M59/02 - F02M59/42; Pumps having transducers, e.g. to measure displacement of pump rack or piston
  • F02M59/48—Assembling; Disassembling; Replacing
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
  • F04B1/00—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders
  • F04B1/04—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinders in star- or fan-arrangement
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
  • F04B1/00—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders
  • F04B1/04—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinders in star- or fan-arrangement
  • F04B1/0404—Details or component parts
  • F04B1/0408—Pistons
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
  • F04B1/00—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders
  • F04B1/04—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinders in star- or fan-arrangement
  • F04B1/0404—Details or component parts
  • F04B1/0426—Arrangements for pressing the pistons against the actuated cam; Arrangements for connecting the pistons to the actuated cam
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
  • F04B53/00—Component parts, details or accessories not provided for in, or of interest apart from, groups F04B1/00 - F04B23/00 or F04B39/00 - F04B47/00
  • F04B53/14—Pistons, piston-rods or piston-rod connections

Definitions

• the present invention relates to a pump unit for feeding fuel, preferably diesel fuel, to an internal combustion engine.
• the present invention relates to a pump unit comprising a pump body; a piston pump designed to feed the fuel to an internal combustion engine; and a gear pump designed to feed the fuel to the piston pump.
• the piston pump comprises at least one cylinder which is formed in the pump body; and a piston engaged slidably inside the cylinder so as to perform an intake stroke for drawing the fuel into the cylinder under the thrust of a spring arranged between the pump body and a support plate mounted on the piston and a compression stroke for compressing the fuel contained inside the cylinder under the thrust of an actuating device.
• the support plate has an opening, which is formed through the support plate, parallel to a longitudinal axis of the piston, and comprises a seat for inserting the piston through the support plate, a seat for engaging the piston in the support plate, and a communicating section for allowing the piston to pass between the insertion seat and the engaging seat.
• the piston is provided with an annular groove, which is formed on the outer surface of the piston and has a diameter slightly greater than a width of the communicating section; the insertion seat has a substantially circular shape and a diameter slightly greater than a diameter of the piston; and the engaging seat has a substantially circular shape and a diameter slightly greater than the diameter of the annular groove.
• the known pump units of the type described above have a number of drawbacks due principally to the fact that assembly of the support plate on the piston may cause damage to the annular groove, separation of metal particles from the piston and, therefore, reduction of the fatigue strength of the piston and seizing of the piston inside the cylinder.
• the object of the present invention is to provide a pump unit for feeding fuel, preferably diesel fuel, to an internal combustion engine, which does not have the drawbacks described above and which is simple and inexpensive to produce.
• a pump unit for feeding fuel, preferably diesel fuel, to an internal combustion engine as claimed in Claims 1 to 12 is provided.
• the present invention also relates to a method for assembling a pump unit for feeding fuel, preferably diesel fuel, to an internal combustion engine.
• a method for assembling a pump unit for feeding fuel, preferably diesel fuel, to an internal combustion engine as claimed in Claims 13 to 17 is provided.
• Figure 1 is a schematic cross-sectional view, with parts removed for the sake of clarity, of a preferred embodiment of the pump unit according to the present invention
• Figure 2 is a side view of a first detail of Figure 1; and Figure 3 is a plan view of a second detail of Figure 1.
• 1 denotes, in its entirety, a pump unit for feeding fuel, in particular diesel fuel, to an internal combustion engine (not shown).
• the pump unit 1 comprises a pump body 2 provided with a central hole (not shown) having a given longitudinal axis 3; a piston pump 4 designed to feed the fuel to the said internal combustion engine (not shown); and a gear pump, known and not shown, designed to feed the fuel to the pump 4.
• the pump 4 comprises a plurality of cylinders 5 (only one of which is shown in Figure 1) which are formed in the pump body 2, are uniformly distributed around the axis 3 and have respective longitudinal axes 6 substantially perpendicular to the axis 3.
• Each cylinder 5 is slidably engaged by an associated piston 7 which is mounted inside the cylinder 5 coaxially with the axis 6, has a diameter Dl and is provided with an annular groove 8 (Figure 2) which is formed on an outer surface of the piston 7 at an intermediate point of the piston 7 itself and has a diameter D2 smaller than the diameter Dl.
• the pistons 7 are displaced with an alternating rectilinear movement along the associated cylinders 5 by an actuating device 9 comprising, in the case in question, a drive shaft (not shown) which extends through the pump body 2 coaxially with the axis 3, is mounted so as to rotate, relative to the pump body 2, about the axis 3 and has an eccentric portion engaged rotatably, via a rolling bearing (not shown), through a sleeve (not shown).
• actuating device 9 comprising, in the case in question, a drive shaft (not shown) which extends through the pump body 2 coaxially with the axis 3, is mounted so as to rotate, relative to the pump body 2, about the axis 3 and has an eccentric portion engaged rotatably, via a rolling bearing (not shown), through a sleeve (not shown).
• the sleeve (not shown) has a longitudinal axis parallel to the axis 3 and is bounded externally by a cylindrical surface provided with a plurality of flat faces equal in number to the number of cylinders 5 and each facing a respective disk element (not shown) arranged between an associated piston 7 and the flat face itself.
• the actuating device 9 furthermore comprises, for each piston 7, a respective spring 10 which is mounted coaxially with the associated axis 6, is arranged between the pump body 2 and a substantially flat support plate 11 mounted on the piston 7, perpendicularly with respect to the associated axis 6, and is designed to displace - and normally keep - the piston 7 itself in contact with the associated disk element (not shown).
• each piston 7 is displaced by the associated spring 10 during an outward intake stroke for drawing the fuel into the associated cylinder 5 and by the eccentric portion of the drive shaft (not shown), by the sleeve (not shown) and by the associated washer (not shown) during a return compression stroke for compressing the fuel contained inside the said associated cylinder 5.
• the plate 11 has an opening 12 which is formed through the plate 11, parallel to the axis 6, has a plane S of symmetry substantially coplanar with the axis 6, is bounded by a shaped side wall 13 and comprises a seat 14 for inserting the piston 7 through the plate 11, a seat 15 for engaging the piston 7 in the plate 11, and a communicating section 16 allowing passage between the seat 14 and the seat 15.
• the seat 14 has a substantially circular shape, a centre CI of curvature different from the axis 6, and a diameter D3 slightly greater than the diameter Dl of the piston 7; and the seat 15 has a substantially circular shape, a centre C2 of curvature substantially arranged along the axis 6, and a diameter D4 which is slightly smaller than the diameter Dl of the piston 7 and slightly greater than the diameter D2 of the groove 8. It should be pointed out, moreover, that the distance between the centres CI and C2 is smaller than the sum of the radii of curvature of the two seats 14 and 15.
• the communicating section 16 is bounded laterally by two elastically deformable arms 17 which project from the wall 13 inside the opening 12, extend on opposite sides of the plane S and have respective free ends 18 provided, in the case in question, with respective holes 19 formed in the plate 11, parallel to the axis 6.
• the arms 17 are arranged, normally, in an initial narrow configuration ( Figure 3) where the section 16 has a width LI, measured perpendicularly with respect to the plane S, which is slightly smaller than the diameter D2 of the groove 8 and where each arm 17 has a substantially V-shaped form and cooperates with the other arm 17 so as to define part of the seat 14 and part of the seat 15.
• the opening 12 further comprises two recesses 20, which are formed on opposite sides of the plane S and are each bounded by the wall 13 and by an associ ated arm 17.
• the piston 7 is inserted into the insertion seat 14; the plate 11 is displaced axially along the piston 7 so as to align radially the groove 8 with the communicating section 16; the arms 17 are splayed inside the associated recesses 20, for example by means of a splaying tool (not shown) engaged inside the holes 19, so as to provide the section 16 with a final widened configuration (not shown), where the section 16 has a width L2, measured perpendicularly with respect to the plane S, greater than the width LI and at least equal to the diameter of the groove 8; the piston 7 is displaced radially from the seat 14 into the engaging seat 15 so as to move the groove 8 through the section 16; and the arms 17 are released so as to radially lock the piston 7 inside the seat 15.
• the groove 8 has, in the case in question, a height H greater than the thickness of the plate 11, the plate 11 is finally displaced axially in contact with the piston 7.
• the final widened configuration of the arms 17 allows the piston 7 to be displaced radially from the seat 14 into the seat 15 without interfering with the section 16 and therefore avoids damage to the groove 8, separation of metal particles from the piston 7, reduction in the fatigue strength of the piston 7 and seizing of the piston 7 inside the cylinder 5.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Fuel-Injection Apparatus (AREA)
• Details Of Reciprocating Pumps (AREA)
• Output Control And Ontrol Of Special Type Engine (AREA)

Priority Applications (5)

Applications Claiming Priority (2)

Publications (1)

Family

ID=43466886

Family Applications (1)

Country Status (7)

Cited By (2)

Families Citing this family (1)

Citations (7)

Family Cites Families (9)

• 2010
  • 2010-09-01 IT ITMI2010A001594A patent/IT1401914B1/it active
• 2011
  • 2011-08-24 JP JP2013526410A patent/JP5654682B2/ja not_active Expired - Fee Related
  • 2011-08-24 EP EP11746265.5A patent/EP2612017B1/en not_active Not-in-force
  • 2011-08-24 CN CN201180040979.XA patent/CN103080530B/zh not_active Expired - Fee Related
  • 2011-08-24 KR KR1020137005394A patent/KR20130103718A/ko not_active Application Discontinuation
  • 2011-08-24 RU RU2013114165/06A patent/RU2573434C2/ru not_active IP Right Cessation
  • 2011-08-24 WO PCT/EP2011/064537 patent/WO2012028507A1/en active Application Filing

Patent Citations (7)

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