DE102021116845A1 - Roller tappet for a high-pressure fuel pump - Google Patents

Abstract

Proposed is a roller tappet (1) for a high-pressure fuel pump of an internal combustion engine, with a housing piece (2) separated from a profile tube, formed from two axially continuous, diametrically opposite flats (3) which are connected by two axially continuous cylinder segments (4), the flax (3) having a greater wall thickness than the cylinder segments (4), the housing piece (2) receiving a cam roller (6) at its edge (5) on the drive side, the supporting bolts (7) of which are located in receptacles (8) of the flax ( 3) is seated, with the housing piece (2) being penetrated axially below the cam roller (6) by a bridge piece (9), the lower face (10) of which acts as a support for a pump piston (11) and the flat (3) having two of one output-side edge (12) of the housing piece (2) and have opposite pocket-like clearances (13), which serve to radially protrude a spring plate (14) connected to the pump piston (11). n.

Description

The invention relates to a roller tappet for a high-pressure fuel pump of an internal combustion engine.

A generic roller tappet with a separated from a profile tube housing piece is from DE 10 2013 204 178 A1 famous. Two diametrically opposite flats extend from a drive side of the housing piece and extend in sections over a length of the housing piece.

More roller tappets are in the documents DE 10 2009 013 132 A1 and DE 10 200 022 318 A1 described.

The task is to create a roller tappet that can cope with high loads / speeds with a low mass and is also compact.

According to the invention, this object is achieved by the features of claim 1. Accordingly, a roller tappet for a high-pressure fuel pump of an internal combustion engine is proposed, with a housing piece separated from a profile tube, formed from two axially continuous, diametrically opposite flats, which are connected by two axially continuous cylinder segments, the flats having a greater wall thickness than the cylinder segments, wherein the housing piece accommodates a cam roller on its drive-side edge, the supporting bolt of which sits in receptacles in the flat, wherein the housing piece is penetrated axially below the cam roller by a bridge piece, the underside of which acts as a support for a pump piston and the flat is two by a driven-side edge of the Have housing piece outgoing and opposite pocket-like exemptions, which serve a radial projection of a spring plate connected to the pump piston.

The roller tappet according to the invention is significantly lighter than the profiled tube tappet mentioned at the outset and is at the same time able to withstand the high loads in today's very high-speed pump drives with correspondingly high injection pressures.

The new types of clearances in the output-side edge of the housing piece guarantee that the spring plate, which is firmly connected to the pump piston, protrudes radially with its return spring, so that comparatively large return springs can be used without the diameter of the housing piece having to be increased. The axially continuous flats of the housing piece are in a section of strong force application (support bolt with cam roller), whereas the remaining, thin-walled cylinder segments can be found in a section of lower force application. It is clear that due to the compared to the St. d. T. axially continuous flax whose subsequent introduction to attach the support bolt is saved, which reduces production costs.

Depending on the requirements, housing pieces of different lengths can be cut from the profile tube. In addition, it is conceivable and intended to let the housing piece “end” directly at the level of the transverse chords, so that the edge on the output side is not stepped, which is a further contribution towards lightweight construction and reduction of the oscillating masses.

According to an expedient further development of the invention, provision is made to apply window-like recesses in the cut-outs, in which the bridge piece, for example designed as a beam, is seated. A simple receiving area for the bridge piece is thus created, which, according to a further specification, can also be held axially here by positive locking. A trapezoidal cross section in the comprehensive area is thought of as an example of the form-fitting fixation.

A simple axial fixation of the bridge piece is the subject of a further dependent claim. Accordingly, the through-hardened bridge piece, for example, can be caulked on the outside face or wobble or radial point riveted (similar to the supporting bolt). A "classic" press or welded connection is also being considered. In this case, the bridge piece does not necessarily have to protrude axially beyond the housing piece.

A good angle or tolerance compensation is present when a drive-side contact area of the bridge piece is shell-like on transverse edges of the recesses. In contrast, a planar design is very good in terms of force application/surface pressure.

Finally, it is proposed to tolerate the outer lateral surfaces of the flax and the cylinder segments of the housing piece in relation to their guide bore in the high-pressure fuel pump drive in such a way that the flax has a larger guide play than the cylinder segments. Such a different tolerance is not possible with circumferentially cylindrical housing pieces. The advantage here is that with increasing thermal expansion (guide hole made of aluminum, housing piece made of steel), the greater play lengthwise to the camshaft to compensate for alignment or perpendicularity errors can be used. On the other hand, the smaller play transverse to the camshaft is advantageous, for example to reduce a turnover play and thus a shock impulse.

• • Figur zeigt den Rollenstößel in einem Längsschnitt;
• • 2 zeigt den Rollenstößel wie vorgenannt, jedoch um 90° um die Axiallinie gedreht;
• • 3 zeigt eine Draufsicht auf den Rollenstößel nach 1 ;
• • 4 zeigt einen Längsschnitt durch eine Baugruppe mit Rollenstößel und Pumpenkolben und
• • 5 zeigt die Baugruppe wie vorgenannt, jedoch um 90° um die Axiallinie gedreht.

About the drawing:

• • Figure shows the roller tappet in a longitudinal section;
• • 2 shows the roller tappet as above, but rotated 90° around the axial line;
• • 3 shows a plan view of the roller tappet 1 ;
• • 4 shows a longitudinal section through an assembly with roller tappet and pump piston and
• • 5 shows the assembly as mentioned above, but rotated by 90° around the axial line.

the 1 until 3 disclose a roller tappet 1 for a high-pressure fuel pump of an internal combustion engine. The roller tappet 1 comprises a housing piece 2 obtained from a profile tube, for example by adiabatic cutting (beating off) or sawing. Can be seen in 3 that the flax 3 has a greater wall thickness than the cylinder segments 4. The wall thicknesses are the same in each case, apart from the transition areas to the respective adjoining segment.

A cam roller 6 is accommodated at a drive-side edge 5 of the housing piece 2 . This slides on a bearing bolt 7 , which sits in receptacles 8 designed as bores in the flax 3 and protrudes slightly beyond an outer lateral surface 20 of the flax 3 .

The flats 3 have two opposing pocket-like openings 13, which start at an output-side edge 12 of the housing piece 2 (see Fig. 1 ), which are obtained by punching. Transverse chords 15 of the exemptions 13 are each provided with a window-like recess 16, in which recesses 16 a beam-like bridge piece 9 sits. A lower face 10 of the bridge piece 9 separated from a profile wire acts as a support for a pump piston 11 which is firmly connected to a spring plate 14 which in turn is acted upon by a restoring spring 24 . The spring plate 14 protrudes into the aforementioned pocket-like openings 13 of the flax 3 on the outer edge with winding areas of the return spring 24 (see also 4 , 5 ).

Can be seen in 1 that the recesses 16 in the transverse chords 15 of the exemptions 13 are trapezoidal, with side edges 25 tapering in the output-side direction. The bridge piece 9 is thus fixed in the recesses 16 via a positive fit. For assembly, it is pushed in from the side and then caulked hard at its outer ends 17 . If necessary, the recesses can also have “straight” side edges 25, in which case the bridge piece 9 is joined to the recesses 16 with a slight oversize.

As in 1 drawn in, a drive-side contact area 18 of the bridge piece 9 on transverse edges 19 of the recesses 16 is designed to be planar for a good introduction of force.

Finally is in 5 an anti-rotation device is also marked with "22", which is firmly seated in one of the cylinder segments 4 of the housing piece 2.

Reference List

1)

roller tappet

2)

housing piece

3)

Flat

4)

cylinder segment

5)

edge (drive side)

6)

cam roller

7)

support bolt

8th)

Recording

9)

bridge piece

10)

lower forehead

11)

pump piston

12)

edge (output side)

13)

exemption

14)

spring plate

15)

transverse chord

16)

recess

17)

outer forehead

18)

investment area

19)

transverse edge

20)

outer surface

21)

outer surface

22)

anti-rotation device

23)

module

24)

return spring

25)

side edge

QUOTES INCLUDED IN DESCRIPTION

This list of the documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• DE 102013204178 A1 [0002]
• DE 102009013132 A1 [0003]
• DE 10200022318 A1 [0003]

Claims (8)

Roller tappet (1) for a high-pressure fuel pump of an internal combustion engine, with a housing piece (2) separated from a profile tube, formed from two axially continuous, diametrically opposite flats (3), which are connected by two axially continuous cylinder segments (4), the flats (3) have a greater wall thickness than the cylinder segments (4), the housing piece (2) accommodating a cam roller (6) at its drive-side edge (5), the supporting bolts (7) of which sit in receptacles (8) of the flat (3). , wherein the housing piece (2) is penetrated axially below the cam roller (6) by a bridge piece (9), the lower face (10) of which acts as a bearing for a pump piston (11) and the flat (3) has two edges ( 12) of the housing piece (2) and have opposite pocket-like openings (13) which serve to radially protrude a spring plate (14) connected to the pump piston (11). roller tappet after claim 1 , wherein transverse chords (15) of the exemptions (13) are provided with a window-like recess (16), in which recesses (16) the beam-like or plate-like bridge piece (9) is accommodated. roller tappet after claim 2 , wherein the bridge piece (9) is fixed via form fit in the recesses (16) of the exemptions (13). roller tappet after claim 3 , wherein the recesses (16) are trapezoidal with side edges (25) tapering in the direction on the output side. roller tappet after claim 2 , wherein the bridge piece (9) is through-hardened and is either caulked or wobble-riveted or radial-point riveted on its outer ends (17) for its longitudinal fixation. roller tappet after claim 1 , wherein the bridge piece (9) has a beam-shaped geometry and is present as a piece separated from a profile wire. roller tappet after claim 2 , wherein a drive-side contact area (18) of the bridge piece (9) on transverse edges (19) of the recesses (16) is either planar or shell-like. roller tappet after claim 1 , wherein the outer lateral surfaces (20, 21) of the flat (3) and the cylinder segments (4) of the housing piece (2) have different tolerances in relation to their guide bore in the high-pressure fuel pump, such that the flat (3) has greater guide play than the the cylinder segments (4).

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