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
  • 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
  • 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
  • F04B1/0439—Supporting or guiding means for the pistons

Definitions

• the invention relates to a piston pump, in particular a high-pressure fuel pump, with a housing, a piston, and a drive shaft with an eccentric or cam portion, on which the piston is supported at least indirectly via a plunger element.
• a piston pump of the type mentioned is known from DE 43 00 631 Al.
• the fuel injection pump shown in this publication has a piston which can be displaced by a camshaft in a reciprocating motion. In this case, the piston is acted upon by a spring to the camshaft.
• a plunger body with a roller shoe is attached to a piston foot. On the roller shoe, a roller is rotatably supported and held. The roller runs on the cam track of the cam.
• This assembly comprising a tappet body, a roller shoe and a roller, is referred to as a roller tappet.
• a hydrodynamic sliding bearing is formed, which is lubricated by the fuel present in the interior of the pump housing.
• roller tappet Another undesirable effect with the known from the prior art piston pumps with roller tappet is that the roller can start during operation in the axial direction of, for example, the plunger element or other components of the piston pump, since they are not fixed in the axial direction.
• This uncontrolled axial start of the roller on other components can lead to heavy wear of the components involved. As a result of this wear and the associated metallic abrasion can lead to consequential damage to the piston pump.
• the invention has for its object to provide a piston pump, in particular a high-pressure fuel pump for a fuel injection system of an internal combustion engine, which avoids the known from the prior art disadvantages and still has a simple structure.
• a piston pump in particular a high-pressure fuel pump, with a housing, a piston and a drive shaft with a cam portion on which the piston is at least indirectly supported by a roller, characterized in that the side of the cam portion, a collar is provided, and that the collar protrudes in the radial direction over the cam portion.
• This collar ensures that the roller can not move uncontrollably in the axial direction during operation. As a result, the start of the roller on other components of the piston pump, which are not suitable, prevented and thus occurs on these parts no wear. Since the collar is preferably hardened, as well as the cam track of the cam portion, both the collar and the likewise hardened roller are very resistant to wear, so that the tarnishing of the roller on the collar brings no wear. As a result, the function of the piston pump is not affected by the start of the roller.
• a particularly advantageous effect results from the tarnishing of the roller on the collar, because occurs by the contact of the roller on the collar occurs friction, which exerts a torque on the roller. For this reason, if the pulley should not turn, but slides on the cam portion, it will rotate again by starting at the collar. This causes the roller to slide back onto the roller shoe and the roller rolls on the cam section. Thus, the desired state is restored, in which both between the cam portion and roller and between roller and roller shoe almost no wear occurs and thus the life of the piston pump operated in this way is very high.
• camshaft and collar or cam portion and collar are integrally formed.
• the collar is made together with the cam portion, for example, by grinding from a blank of a drive shaft.
• the collar for example, as a sheet metal blank and firmly connected to the drive shaft or with its cam portion. It is possible to press the collar with the camshaft and / or connect by a weld.
• Figure 1 is a partial section through a piston pump
• Figure 2 is a section along the line II-II of Figure 1;
• Figure 3 is a constructive detail of an embodiment of an inventive
• a piston pump carries the reference numeral 10 as a whole. It comprises a housing 12 in which a drive shaft 14 is mounted via two bearings 16 and 18. As can be seen in particular from FIG. 2, the drive shaft 14 has a cross-sectionally oval cam section 20 between the two bearings 16 and 18.
• the piston pump 10 shown in FIGS. 1 and 2 serves as a high-pressure fuel pump for an internal combustion engine in a motor vehicle. With it, the fuel is compressed to a very high pressure and conveyed to a fuel rail (not shown). The drive shaft 14 of the piston pump 10 is thereby directly from the internal combustion engine driven. Therefore, the drive shaft 14 has a corresponding coupling portion 22 which is disposed outside of the housing 12.
• the piston pump 10 is a 1-cylinder radial piston pump. For reasons of clarity, however, neither the piston nor the delivery chamber bounded by it nor the associated intake and exhaust valves are shown in the two figures. These elements are integrated into a cylinder head, not shown, which can be attached to a cylinder section 24 of the housing 12 that is perpendicular to the longitudinal axis of the drive shaft 14.
• the piston of the piston pump 10 is indirectly driven by the cam portion 20 of the drive shaft 14.
• the term "indirectly” is understood here to mean that the piston does not directly touch the cam section 20, but that a so-called roller tappet 26 is arranged between the piston and the cam section 20. This comprises a plunger body 28 and a roller 30th
• the roller tappet 26 is pressed together with the piston against the cam portion 20 to ensure that the roller 26 does not lift off from the cam portion 20 of the drive shaft 14.
• the plunger body 28 is a sintered part. Alternatively, it could also be an aluminum pressed part or a metal skeleton, which is encapsulated in plastic. As can be seen in particular from FIG. 3, the plunger body 28 comprises a central, cuboid roller shoe or plunger block 34, on whose upper region in FIG. 3 on both sides an outwardly extending projection 36 or 38 is integrally formed.
• a vertically upwardly extending guide portion 40 or 42 is integrally formed on this.
• the two guide portions 40 and 42 engage in the mounting position in corresponding grooves 44 and 46 in the cylinder portion 24 of the housing 12 (see Figure 1), which form the housing-side guide areas. In this way, the plunger body 28 can not rotate about a longitudinal axis of the cylinder portion 24.
• a cylindrical recess 48 is inserted into the plunger block 34, the longitudinal axis of which in the installed position is parallel to the longitudinal axis of the Drive shaft 14 extends.
• the recess is open to the cam portion 20 and extends over the entire width of the plunger body 28. Their maximum depth is approximately equal to the radius of the cylindrical roller 30 so that it protrudes approximately half a diameter beyond the edge of the recess 48.
• Plunger body 28 and plunger block 34 may be formed integrally or as separate components.
• roller 30 is inserted into the recess 48 and is supported with its lateral surface 49 on the wall of the recess 48 from. Roller 30 and recess 48 form a plain bearing.
• the securing element 32 serves to secure the roller 30 in the recess 48 in the tappet body 28 and, in particular, to prevent the roller 30 from falling out of the tappet element 28 during assembly.
• a collar 50 is provided on the drive shaft 14 on both sides of the cam section 20.
• the collar 50 projects in the radial direction over the
• Cam portion 20 out, so that the roller 30 when it travels during operation in the axial direction, against one of the two frets 50 starts. Thereby, the axial movement of the roller 30 is limited during operation to a defined extent.
• care can be taken that by a suitable tribological pairing of the roller 30 and the collars 50, the wear on both the roller 30 and the collar 50 is so small that it does not lead to malfunction or a shortening of the life of the piston pump 10 , This can for example be achieved in that the collar as well as the cam portion 20 and the roller tappet 26 are made of hardened steel.
• an undercut 52 is provided in each case, which ensures that the notch effect at the transition between cam portion 20 and collar 50 is reduced. Furthermore, the undercuts 52 provide for defined contact surfaces between roller 30 and cam portion 20 on the one hand and roller tappet 26 and the collars 50 on the other.
• roller 30 is rotated by the friction that occurs when starting at one of the collars 50, if it does not already by the rolling friction between the cam portion 20 and roller 30 rotates. It has been found in practical experiments that the rolling friction between roller 30 and cam portion 20 is not always sufficient to enable the rollers 30 in rotation, so that not always between the recess 48 in the plunger block 34 and the roller 30 as desired, a hydrodynamic Plain bearing forms. This undesirable effect is avoided in the embodiment of the drive shaft 14 according to the invention.
• a particularly advantageous embodiment of a roller tappet 26 is shown.
• a respective centrally disposed recess 54 is recessed at the end faces (without reference numeral) of the roller 30. This ensures that the roller 30 comes into contact with the collar 50 of the drive shaft 14 only in the region of its outer diameter, so that the torque exerted on the roller 30 by the adhesive or sliding friction between roller 30 and collar 50 is maximum due to the large lever arm becomes.
• FIG. 3 shows a detail of a constructional detail of a further advantageous embodiment of a piston pump according to the invention.
• the collar 50, the cam portion 20 and the drive shaft 14 are integrally formed.
• the collar is designed as a separate component.
• the collar 50 can be formed for example as a sheet metal blank.
• a shoulder 56 is machined laterally of the undercut 52.
• the collar 50 is permanently attached, for example by pressing. It is also possible, alternatively or in addition to the press connection, to fasten the collar 50 to the shoulder 56 by means of a weld 58.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Fuel-Injection Apparatus (AREA)
• Reciprocating Pumps (AREA)
• Jet Pumps And Other Pumps (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (2)

Family

ID=38872090

Family Applications (1)

Country Status (6)

Cited By (2)

Families Citing this family (14)

Family Cites Families (5)

• 2006
  • 2006-10-16 DE DE102006048722A patent/DE102006048722A1/de not_active Withdrawn
• 2007
  • 2007-08-28 EP EP07802934A patent/EP2079923B1/fr not_active Not-in-force
  • 2007-08-28 CN CN2007800385426A patent/CN101529082B/zh not_active Expired - Fee Related
  • 2007-08-28 DE DE502007003793T patent/DE502007003793D1/de active Active
  • 2007-08-28 AT AT07802934T patent/ATE467760T1/de active
  • 2007-08-28 WO PCT/EP2007/058897 patent/WO2008046683A1/fr active Application Filing
  • 2007-08-28 PL PL07802934T patent/PL2079923T3/pl unknown

Non-Patent Citations (1)

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