DE102017125699B3 - Roller tappet for a high-pressure fuel pump - Google Patents

Abstract

Proposed is a roller tappet (1) for a high-pressure fuel pump, with a extruded housing (2), on the inner wall (3) a bridge piece (4) is integrally connected, wherein above the drive-side end (5) of the bridge piece (4) has a role ( 6) is arranged for a cam counterbore and on the driven-side end (7) of the bridge piece (4) a raised area (8) with a pump piston system (9) is integrally formed, which raised area a bar-like from the bridge piece (4) projecting material thickening (8 ), which passes parallel to the roller axis of the inner wall (3) to inner wall (3), wherein side walls (10) of the material thickening (8) from the bridge piece (4) away wedge-like run towards each other.

Description

The invention relates to a roller tappet for a high-pressure fuel pump, with a flow-molded housing, on the inner wall of a bridge piece is integrally connected, wherein above the drive-side end of the bridge piece a roller for a cam counter is arranged and on the output side end of the bridge piece a raised area with a pump piston system is formed in one piece.

Extruded roller tappets have the advantage of better NVH performance (noise, vibration, harshness ...) compared to their plate counterparts. However, in the case of the same load cases and the same boundary conditions as installation dimensions, the extrusion ram tappets must be designed significantly more strongly, in particular in the section of the bridge piece, than in the case of sheet metal designs, as in US Pat DE 10 2010 026 361 A1 shown. Here, the ever-increasing injection pressures in high-pressure fuel pumps for quality- or quantity-controlled internal combustion engines play a major role.

It can be seen in o. G. Document that the one piece tailpiece bridge is comparatively massive. It consists of a wall-side thick-ring section, to which a cylindrical center shoulder for the pump piston contact is connected. The roller for the cam counter is a roller-shaped body, which is slidably mounted in a shell piece, which in turn sits on top of the bridge piece.

The o. G. massive design of the bridge piece has a detrimental effect on the total mass of the plunger and is disadvantageous in the friction work. Such a massive design can also be represented only with greatly increased effort with increased tool wear fluency. In addition, the skilled artisan recognizes that the roller-shaped roller due to their complex sliding bearing in the separate shell piece has only a comparatively small diameter, so that when the cam contact the hertzian pressure is unnecessarily high and premature wear is expected.

In addition, on the DE 10 2013 202 129 A1 directed. This discloses, for example, in 4 also a roller tappet for a high-pressure fuel pump. Its solid bridge piece with uniformly continuous height is a separate component.

It is therefore an object of the invention to present an extrusion ram that is easy to build and at the same time withstands high loads.

According to the invention, this object is achieved in that the raised area is a beam-like projecting from the bridge piece material thickening, which passes parallel to the roller axis from inner wall to inner wall, side walls of the material thickening away from the bridge piece wedge-like run towards each other and wherein at the longitudinal center of the bridge piece is the pump piston system ,

Thus, there is a die-pressed roller tappet without the disadvantages mentioned above. The targeted material accumulation only parallel to the axial line leads to a rigid plunger with significantly reduced total mass and at the same time good extrusion properties.

The wedge-shaped or trapezoidal design of the side walls of the material thickening, whereby an arcuate or purely rectangular design, in each case in cross-section questioned, represents an excellent support in the design of the rigid roller tappet is. Transitions of the side walls in the output side end of the bridge piece or transitions of the latter to the inner wall of the housing in this case are expediently clearly rounded to reduce the notch effect.

At the same time can be in the remaining thin-walled Brückenstückbereich, laterally outside the material thickening, now very easy through holes for media such as air or fuel, eg. By drilling, "cutout" or the like. Apply, as it is the subject of a subclaim.

According to an advantageous development of the invention, the bridge piece outside the bar-like material thickening should have a height which is less than / equal to 0.7 times the height in the material thickening. Thus, another contribution towards lightweight construction is made.

The pump piston system on the output side of the material thickening is proposed in concretization of the invention merely as a cylindrical projection. Only this would thus be required after measuring an actual installation dimension, before a final assembly of the roller tappet on the high-pressure fuel pump, if necessary, be ground. A sanding of the entire bottom of the bridge piece is eliminated. It is also contemplated to provide rams that are grouped with respect to a height of their pump piston system.

Although it is conceivable and intended to store the roller for the cam contact achsfrei in a shell in the drive-side end of the bridge piece. It is more advantageous, however, this on one Bolt via a roller bearing as a needle bearing (alternatively also slide bearing) to arrange which pin sits end in recordings of indented flax of the lateral surface of the housing. The flax are expediently pressed in during the extrusion process of the housing with. They can also have a stiffening effect on the entire structure.

If necessary, the receptacles for the roller in the flax can also be partially open in the direction of the drive-side annular end of the housing so that they have a U-like geometry. Thus, height can be saved. The bolt is thereby snapped or pressed into the receptacles.

It is advantageous to represent tab-like elevations on the drive-side annular end of the housing in the circumferential section of the flax, in which sections the receptacles for the bolt extend in sections. This allows the housing to build low.

From a manufacturing point of view it is advantageous to connect the bridge piece to this at approximately half the height of the housing. Thus, during extrusion as in reverse flow extrusion, there is an approximately equal flow of material in both directions.

Due to the shell-like indentation described in further development of the invention in the drive-side end of the bridge piece, it is possible to set the role "lower", which saves height. In case of load, and this is ultimately a 3-point load before (force via the bolt in the flax), this arch form can also act as stiffening.

The roller tappet according to the invention can also be used in pump or compressor drives of any kind and in valve trains of internal combustion engines application.

• • 1 zeigt einen Rollenstößel in räumlicher Ansicht, teilaufgeschnitten;
• • 2 zeigt einen Längsschnitt durch den Rollenstößel entlang dessen Rolle und
• • 3 zeigt einen Längsschnitt wie vorgenannt, jedoch um 90° gedreht.

To the drawing:

• • 1 shows a roller tappet in a spatial view, partially cut;
• • 2 shows a longitudinal section through the roller tappet along its role and
• • 3 shows a longitudinal section as mentioned above, but rotated by 90 °.

Out 1 goes out a roller tappet 1 for a high-pressure fuel pump. This has a housing manufactured by extrusion 2 with one on the inside wall 3 one-piece tailpiece bridge piece 4 (Sat. 2 . 3 ).

It can be seen in all figures that above a drive-side forehead 5 of the bridge piece 4 a role 6 is arranged for a cam counterflow. The role 6 runs over a rolling bearing designed as a needle bearing 14 on a bolt 15 , The latter sits in the end of recordings 16 of the housing 2 , More precisely, the recordings are 16 in opposite to an outer wall 12 of the housing 2 indented flax 13 , The latter stand out with tab-like elevations 20 opposite the remaining drive-side annular end face 11 from. In other words, the ring is forehead 11 outside a peripheral region of the recordings 16 discontinued.

On a driven-side forehead 7 of the bridge piece 4 is a bar-shaped raised area 8th (Material thickening) with a pump piston system 9 (cylindrical supernatant) formed in one piece (see also 2 ). The material thickening 8th extends as well out of the 1 . 2 shows, parallel to the roller axis of the inner wall 3 to inner wall 3 , Out 3 here is still removable, that sidewalls 10 the material thickening 8th from the bridge piece 4 away from each other like a wedge.

Outside the bar-shaped material thickening 8th , so on both sides this, has the bridge piece 4 several through holes 17 , These serve to pass fuel such as diesel fuel or air.

The drive-side forehead 5 of the bridge piece 4 also has a shell-like indentation 18 into which the role 6 partially recruits. The indentation 18 can also serve as a lubricant reservoir.

LIST OF REFERENCE NUMBERS

1)

roller plunger

2)

casing

3)

inner wall

4)

bridge piece

5)

drive-side forehead

6)

role

7)

output-side forehead

8th)

Area, material thickening

9)

Pump piston system

10)

Side wall

11)

drive-side annular end

12)

outer wall

13)

Flat

14)

roller bearing

15)

bolt

16)

admission

17)

Through opening

18)

indentation

19)

not forgiven

20)

increase

Claims (8)

Roller tappet (1) for a high-pressure fuel pump, with a flow-pressed housing (2), on the inner wall (3) a bridge piece (4) is integrally connected, wherein above the drive-side end (5) of the bridge piece (4) has a roller (6) for a recirculating cam is arranged and on the output side end (7) of the bridge piece (4) a raised portion (8) with a pump piston system (9) is integrally formed, characterized in that the raised portion of a bar-like away from the bridge piece (4) protruding material thickening ( 8) which passes parallel to the roller axis from inner wall (3) to inner wall (3), wherein side walls (10) of the material thickening (8) from the bridge piece (4) away wedge-like run towards each other and wherein at the longitudinal center of the bridge piece (4) the pump piston system (9) is located. Roller follower to Claim 1 , characterized in that the bridge piece (4) outside its material thickening (8) has a height which is less than / equal to 0.7 times the height at the material thickening (8). Roller follower to Claim 1 characterized in that, starting from the drive-side annular end face (11) of the housing (2), two flanges (13) engaged with respect to its outer wall (12) are diametrically opposed, in which a roller (6) is secured via a roller bearing (14). bearing bolt (15) is received. Roller follower to Claim 3 , characterized in that the drive-side annular end (11) of the housing (2) in the peripheral portion of the flax (13) has two tab-like elevations (20), wherein receptacles (16) for the bolt (15) axially at least partially in the elevations (20 ) lie. Roller follower to Claim 1 , characterized in that the pump piston system (9) is a cylindrical projection. Roller follower to Claim 1 , characterized in that the bridge piece (4) outside its material thickening (8) has one or more passage openings (17). Roller follower to Claim 1 , characterized in that the bridge piece (4) on the housing (2) is connected at about half its height. Roller follower to Claim 1 , characterized in that the drive-side end (5) of the bridge piece (4) has a shell-like indentation (18), in which the roller (6) protrudes.

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