Classifications

• • 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
• • 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
  • F02M59/102—Mechanical drive, e.g. tappets or cams
• • 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
  • F04B53/16—Casings; Cylinders; Cylinder liners or heads; Fluid connections
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
  • F16C17/00—Sliding-contact bearings for exclusively rotary movement
  • F16C17/10—Sliding-contact bearings for exclusively rotary movement for both radial and axial load
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
  • F16C23/00—Bearings for exclusively rotary movement adjustable for aligning or positioning
  • F16C23/02—Sliding-contact bearings
  • F16C23/04—Sliding-contact bearings self-adjusting

Definitions

• the present invention relates to a high-pressure piston pump for feeding fuel, preferably diesel fuel, to an internal-combustion engine.
• a high-pressure piston pump comprises a pump body; a compression chamber formed in the pump body; a piston movable inside the compression chamber along a first axis; and a shaft rotatable about a second axis so as to actuate the piston along the first axis; and at least one bearing arranged between the shaft and the pump body.
• the shaft is mounted rotatably on the pump body about the second axis, is ope ⁇ rated by means of the internal-combustion engine and transmits the movement to the piston along the first axis.
• the piston during the fuel compression stage in- side the compression chamber, transmits to the shaft forces which are correspondingly greater the higher the operating pressure.
• These forces are substantially aligned with the first axis and perpendicular to the second axis, flexural- Iy deform the shaft and modify the distance between the shaft and bearing, in particular in the vicinity of the edge of the bearing close to the first axis. Moreo- ver, the said forces assume high values in view of the fact that the operating pressure of the fuel is higher than 2000 bar.
• one object of the present intention is to provide a high-pressure piston pump which is able to overcome the drawbacks of the prior art.
• Another object of the present invention is to provide a piston pump able to minimise the wear of the bearing.
• a high-pressure piston pump for feeding fuel, preferably diesel fuel, to an internal-combustion engine
• the piston pump comprising: a pump body; a compression chamber formed in the pump body; a piston movable inside the compression chamber along a first axis; a shaft rotatable about a second axis so as to actuate the piston along the first axis; at least one bearing arranged between the shaft and the pump body and comprising an edge close to the first axis; and a sleeve which is arranged between the shaft and the bearing and is structurally weakened in a zone arranged opposite the said edge.
• the shaft compri ⁇ ses a first cylindrical face, the sleeve being fitted onto the shaft along the first cy- lindrical face and comprising a cylindrical wall weakened in the said zone opposi ⁇ te the said edge.
• the said cylindrical wall has, in the zone arranged opposite the said edge, a thickness which is substantially smaller than that of the remainder of the sleeve.
• FIG. 1 is a cross-sectional view, with parts removed for greater clarity, of a high-pressure piston pump provided according to the present invention
• FIG. 2 is a perspective view, with parts cross-sectioned, of a tubular reinfor ⁇ cing structure of the high-pressure piston pump according to Figure 1; and - Figure 3 is a side elevation view, with parts cross-sectioned, of the tubular reinforcing structure according to Figure 2.
• the reference number 1 denotes in its entirety a high-pressure piston pump for feeding fuel to an internal-combustion engine not shown in Figure 1.
• the pump 1 has the function of feeding diesel fuel at a pressure equal to the operating pressure (generally higher than 2000 bar) and comprises: a pump body 2; three compression chambers 3 (only one of which is shown in Figure 1); three pistons 4 (only one of which is shown in Figure 1); a transmission mechanism 5 for imparting a reciprocating movement to the pistons 4 inside the respective compression chambers 3 along respective axes Al (only one of which is shown in Figure 1); three feed ducts 6 (only one of which is shown in Figure 1) for feeding the fuel to the respective compression chamber 3; three feed valves 7 (only one of which is shown in Figure 1) for regulating feeding of the fuel to the respective compression chamber 3; three delivery ducts 8 (only one of which is shown in Figure 1) for feeding the compressed fuel from a respective compression chamber 3 to the internal-combustion engine, not shown in Figure 1.
• the piston pump 1 also comprises three delivery valves 9 arranged along the delivery ducts 8.
• the term "pump body” refers to the supporting structure which supports the pistons 4 and the transmission mechanism 5 and defines the compression chambers 3.
• the pump body 2 comprises a part 10 and a part 11 which are assembled together and where the parts 9 and 10 con ⁇ sist of metal blocks which support the transmission mechanism 5.
• the part 11 has, formed therein, the compression chambers 3 and houses the respective feed valves 7 and the respective delivery valves 9.
• the transmission mechanism 5 comprises a shaft 12 which is rotatable about an axis A2, is supported by the pump body 2 and comprises: a cylindrical eccentric portion 14 which extends around an axis A3 which is parallel and offset with respect to the axis A2; a polygonal ring 15 mounted rotatably about the eccentric portion 14 via a bearing 16; three intermediate parts 17 (only one of which is shown in Figure 1), each of which is arranged between a respective piston 4 and the polygonal ring 15; three springs 18 (only one of which is shown in Figure 1), each of which is arranged between the part 11 and the piston 4 (only one of which is shown in Figure 1). Each spring 18 has the function of ensuring the in- take stroke of the respective piston 4 and keeping the respective piston 4 in contact with the respective intermediate part 17 and the respective intermediate part 17 in contact with the polygonal ring 15 by means of the respective piston 4.
• the piston pump 1 comprises three compression chambers 3 (only one of which is shown in Figure 1) uniformly distributed around the axis A2 and three pistons 4 (only one of which is shown in Figure 1), each of which operates inside a respective compression chamber 3.
• the polygonal ring 15 is, in fact, a sleeve which has a circular inner seat and three outer flat faces 19 (only one of which is shown in Figure 1), each of which faces a respective compression chamber 3 and moves parallel to itself along a circular path.
• Each piston 4 extends along the axis Al and comprises a piston end 20 seated in the intermediate part 17.
• the pump body 2 supports the shaft 12 by means of two bearings 21 and 22, in particular two sliding bearings, each of which comprises a metal support bush and a lining arranged along the inner face of the bush.
• the pump body 2 has two holes 23 and 24 which respectively receive with an interference fit the two bearings 21 and 22 which are arranged on opposite sides of the axis Al and the eccentric portion 14.
• the shaft 12 has two annular shoulders 25 and 26 which are arranged on opposi ⁇ te sides of the eccentric annular portion 14.
• the pump 1 also comprises two thrust bearings 27 and 28 which are arranged, respectively, between the shoulders 25 and 26 and the pump body 2, and a tubu- lar reinforcing structure 29 arranged between the shaft 12 and the bearing 22 and between the annular shoulder 26 and the thrust bearing 28.
• the annular reinforcing structure 29 comprises a sleeve 30 and an annular flange 31.
• the sleeve 30 extends axially along the axis A2 over a length greater than the length of the bearing 22.
• the bearing 22 comprises an edge 32 close to the axis Al and to the eccentric portion 14 and an edge distant from the axis Al and from the eccentric portion 14.
• the sleeve 30 extends beyond the edge 32 towards the eccentric portion 14 and the axis Al.
• the shaft 12 comprises a cylindrical face 33 along which the sleeve 30 is mounted with an interference fit, said sleeve comprising a cylindrical wall 34 having a cylindrical inner face 35 in contact with the cylindrical face 33 and a cylindrical outer face 36 facing the bearing 22.
• the sleeve 30 is structurally weakened in a zone arranged opposite the edge 32 of the bearing 22.
• the cylindrical wall 34 of the sleeve 30 is weake ⁇ ned in the zone arranged opposite the edge 32.
• the cylindrical wall 34 of the sleeve 32 has, along a section of the sleeve 30, a thickness which is smaller than the thickness of the remainder of the cylindrical wall 34 of the sleeve 30.
• the sleeve 30 comprises a cylindrical inner face 37 having a diameter greater than that of the cylindrical inner face 35 as shown more clearly in Figures 2 and 3.
• the annular flange 31 is integral with the sleeve 30 and comprises an annular wall 38 which has one weakened free end.
• the wall 38 is defined by an annular face 39 facing, at least partly, the thrust bearing 28 ( Figure 1) and adjacent to the outer cylindrical face 36, by an annular face 40 in contact, at least partly, with the eccentric portion 14 opposite the shoulder 26, and by an annular face 41.
• the annular faces 39, 40 and 41 are parallel to each other.
• the distance bet ⁇ ween the annular faces 39 and 40 is greater than the distance between the annu- lar faces 39 and 41.
• the wall 38 of the annular flange 31 is structurally weakened in a region opposite the thrust bearing 28.
• the sleeve 30 and the annular flange 31 form an an- nular chamber 42 around the said shaft 12 and the sleeve 30 has an opening 43 for access to the annular chamber 42.
• the tubular reinforcing structure 29 imparts a rigidity to the shaft 12 and allows, locally, dissipation of the excessive forces.
• tubular reinforcing structure 29 is formed as one piece comprising the sleeve 30 and the annular flange 31.
• the sleeve and the annular flange are two separate parts which are joined together.

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• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Fuel-Injection Apparatus (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=41170136

Family Applications (1)

Country Status (2)

Citations (5)

• 2009
  • 2009-03-13 IT ITMI2009A000392A patent/IT1393676B1/it active
• 2010
  • 2010-01-22 WO PCT/EP2010/050705 patent/WO2010102851A1/en active Application Filing

Patent Citations (5)

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