DE102010026361A1 - Roller tappet, particularly for high-pressure fuel pump or for valve gear of quality or quantity controlled combustion engine, has housing, which has bowl-like receptacle with cam catch roller at its input side - Google Patents

Abstract

The roller tappet (1) has a housing (4), which has a bowl-like receptacle (6) with a cam catch roller (7) at its input side (5) and has an attachment (9) for a tappet follower part at its output side (8). An input sided face surface (10) of the housing finds a start-up at counter pieces of the inner shell (2) of the housing. A contact zone of the respective face of the cam catch roller has a course predominantly deviating from a sphere.

Description

The invention relates to a roller tappet, in particular for a high-pressure fuel pump or for a valve train in each case a quality- or quantity-controlled internal combustion engine, with a projected at its inner shell of a bridge piece housing, which bridge piece on its drive side a cup-like receptacle with a cam roller mounted therein and on its output side has a system for a ram follower part, wherein a drive-side end face of the housing, at least in the peripheral portion of forks of the cam follower roller, is about half their height, find which foreheads on counterparts of the inner shell of the housing a start.

In prior art roller tappets, the respective cam follower roller is not bolt-bearing, but sitting in a shell-like receptacle of a bridge piece internally interdigitated bridge piece, forwards of the cam follower run against counterparts of the inner shell of the housing. During this start-up value is placed on an osculation in the contact zone. In other words, the respective end of the cam roller has a ball portion whose radius is only slightly smaller than a radius on the counterpart of the housing. Exactly at the apex of the ball section (exit region of the axis of rotation of the cam starting roller), the relative speed to the counterpart is equal to zero during rotation of the cam starting roller. Thus, in this section no hydrodynamic sliding bearing with a bearing lubricating film is formed (lubrication eg. By diesel fuel) and it comes to wear. Consequently, it is necessary to apply cost-increasing wear protection coatings in this area.

It is an object of the invention to provide a roller tappet of the aforementioned type, in which the disadvantages are eliminated. In particular, a cost-effective and low-wear lateral start-up of the cam roller is to be created or an alternative solution to the aforementioned prior art should be proposed.

According to the invention, this object is achieved in that a contact zone of the respective end of the cam follower roll on the counterpart of the housing has an at least predominantly deviating from a sphere course, with particularly preferred embodiments of the invention are the subject of the dependent claims 2 or 3.

Thus, there is a solution with a significantly improved lubricating film structure, which can also be represented quite inexpensively.

In the variant according to the dependent claim 2 with the Gothic profile latter can also be applied to the front of the cam roller whose tip is then "capped". A person skilled in the art will be aware at this point of a large number of profile shapes for the representation of the off-center contact zone. Possibly. the counterpart of the housing can also be present as a separate, subsequently attached to the inner shell of the housing component.

A particularly simple and thus inexpensive design of the cam follower roller is described in the dependent claim 3, after which foreheads are this plan. Incidentally, the cam roller can be surface-hardened or fully hardened. Instead of the housing-side ball portion in this solution, which ball portion or its counterpart (forehead of the cam follower roller) can also be recessed centrally, is also on other projections such as cuboid o. The like. Intended.

The proposed in development of the invention shell piece for supporting the cam follower roller can be cost-effective for example. Represent by separating from a available as a mass rolling ring and allows a simple way of balancing angular errors while maintaining very good power in the roller tappet.

Preferably, the housing of the roller tappet is made of a lightweight material such as sheet metal or sheet steel. Alternatively, it may also be made by extrusion or by machining.

The invention will be described with reference to the drawing.

Show it:

1 a plan view of a roller tappet;

2 a spatial view of the roller tappet;

3 a longitudinal section through the roller tappet;

4 an outbreak in the area of the contact zone and

5 an alternative to 4 ,

Shown is a roller tappet 1 for a high-pressure fuel pump. The roller plunger 1 is on the inner jacket 2 his case 4 from a piece of bridge connected in one piece 3 projects through. The latter has on its drive side 5 a bowl-like recording 6 with a cam-mounted roller mounted therein 7 , On a driven side 8th of the bridge piece 3 is a trained as a projection plant 9 shown for a pump piston as a ram successor part.

A drive-side, annular end face 10 of the housing 4 stands, as from the 2 . 3 shows over half the height of foreheads 11 the cam pickup roller 7 , The foreheads 11 run on counterparts 12 of the inner jacket 2 of the housing 4 at.

Furthermore, it can be seen that the aforementioned shell-like recording 6 of the bridge piece 3 from a segment-like shell piece 17 is shown, which is separated from a ring. In the bowl piece 17 runs the cam chuck 7 Sliding directly, with the shell piece 17 via its outer jacket in a complementary cylindrical indentation 18 the drive side 5 of the bridge piece 3 sitting.

Out 4 shows that the respective forehead 11 the cam pickup roller 7 , except for a structurally necessary edge break 15 , is plan. The respective counterpart 12 on the inner jacket 2 of the housing 4 is here as (partly) cylindrical indentation 16 formed, whose axial line is parallel to the ram axis. Thus, there is a line contact, as it were, when the roller is started up, with possibly an area around the axial line of the cam starting roller 7 on one of the elements 16 or 11 can be omitted (not shown).

Alternatively to the above solution is after 5 the respective forehead 11 the cam pickup roller 7 spherically formed. The respective counterpart 12 on the inner jacket 2 of the housing 4 This describes a pointed arch 14 [gothic profile]. Thus, in this embodiment, no central, wear-prone contact is more between the respective forehead 11 the cam pickup roller 7 and the counterpart 12 on the housing 4 in front. The hydrodynamic sliding bearing is formed during rotation of the cam starting roller 7 off-center.

LIST OF REFERENCE NUMBERS

1

roller plunger

2

inner sheath

3

bridge piece

4

casing

5

driving side

6

admission

7

Cam nose role

8th

output side

9

investment

10

drive-side forehead housing

11

Forehead cam roller

12

counterpart

13

contact zone

14

lancet arch

15

chamfer

16

concavity

17

shell pieces

18

indentation

Claims (7)

Roller tappets ( 1 ), in particular for a high-pressure fuel pump or for a valve drive in each case a quality or quantity-controlled internal combustion engine, with a on its inner shell ( 2 ) from a bridge piece ( 3 ) protrude through housing ( 4 ), which bridge piece ( 3 ) on its drive side ( 5 ) a bowl-like receptacle ( 6 ) with a cam roller mounted therein ( 7 ) and on its output side ( 8th ) an annex ( 9 ) has for a ram follower part, wherein a drive-side end face ( 10 ) of the housing ( 4 ), at least in the peripheral portion of foreheads ( 11 ) of the cam roller ( 7 ), about half their height, which foreheads ( 11 ) on counterparts ( 12 ) of the inner jacket ( 2 ) of the housing ( 4 ) find a start, characterized in that a contact zone ( 13 ) of the respective forehead ( 11 ) of the cam roller ( 7 ) on the counterpart ( 12 ) of the housing ( 4 ) has an at least predominantly deviating from a sphere course. Roller tappet according to claim 1, characterized in that the respective forehead ( 11 ) of the cam roller ( 7 ) is spherical, with the respective counterpart ( 12 ) of the housing ( 4 ) in plan view either an ogive ( 14 ) describes [gothic profile] or is represented by more than two circular arcs ( 5 ). Roller tappet according to claim 1, characterized in that the respective forehead ( 11 ) of the cam roller ( 7 ), except for a structurally necessary edge break ( 15 ), at least predominantly flat, whereby the respective counterpart ( 12 ) of the housing ( 4 ) either a cylindrical indentation ( 16 ) is in the direction of the plunger center, whose axial line is parallel to the plunger axis or as in the direction of the plunger center protruding portion like a vaulted spherical section is present ( 4 ). Roller tappet according to claim 1, characterized in that the shell-like receptacle ( 6 ) of the bridge piece ( 3 ) from a bowl piece ( 17 ) is shown as a half or a third shell, which is separated from a ring, in which shell piece ( 17 ) the cam roller ( 7 ) is slidingly mounted, wherein the shell piece ( 17 ) in a complementary indentation ( 18 ) of the drive side ( 5 ) of the bridge piece ( 3 ) sits. Roller tappet according to claim 4, characterized in that for the representation of the shell piece ( 17 ) a standard component such as a Wälzring is used. Roller tappet according to claim 1, characterized in that the bridge piece ( 3 ) in one piece with the housing ( 4 ) connected is. Roller tappet according to claim 1 or 6, characterized in that the housing ( 4 ) is extruded or deep drawing made of sheet steel.

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