WO2006005405A1

WO2006005405A1 - Hydraulic valve tappet

Info

Publication number: WO2006005405A1
Application number: PCT/EP2005/006386
Authority: WO
Inventors: Oliver Schnell; Peter Sailer; David Kehr
Original assignee: Schaeffler Kg
Priority date: 2004-07-10
Filing date: 2005-06-15
Publication date: 2006-01-19
Also published as: DE102004033499A1

Abstract

The invention relates to a valve tappet (2) for use in the mechanical valve gear of an internal combustion engine, especially for motor vehicles. Said valve tappet (2) is effectively mounted between a gas exchange valve and its periodic drive, is provided with a lateral oil supply and is inserted in a housing. A compensation piston (10) having an oil reservoir (24) is located inside the valve tappet (2) and can be axially displaced to a limited extent. Said oil reservoir (24) comprises on one end an exit (22) controlled by a return valve (20) and on the other end a connecting port (16) connecting the reservoir to an adjacent component of the valve gear. A flow restrictor is disposed inside the compensation piston (10) in the oil reservoir (24) adjacent to the connecting port (16). In order to allow an operationally reliable fixation and to simplify assembly, the flow restrictor is configured as a stationary filter (40) that is pressed into the compensation piston (10).

Description

Name of the invention

Hydraulic valve lifter

description

Field of the invention

The invention relates to a hydraulic valve tappet in the course of a mechanical valve train of an internal combustion engine, in particular for motor vehicles, the valve tappet between a gas exchange valve and its periodi¬ cal drive effectively arranged and provided with a lateral oil supply is inserted into a housing, wherein within the valve stem an axially limited displaceable balance piston with an oil reservoir is arranged an¬, this oil reservoir at one end dominated by a Rückschlagven- til output and the other end has a connection opening to an adjacent component of the valve train, and with a within the balance piston in the oil reservoir adjacent to the connection opening an¬ arranged flow.

Background of the invention

For the operation of internal combustion engines, especially in motor vehicles, there are generally increasing demands on the reliability and longevity of all the components involved. An existing problem area is the lubricating oil supply, in particular that of the valve train. When installing or when the valve gear is off, it can lead to unwanted idling or come to a suppressed oil volume exchange between individual Komponen th.

From US 2002/0096136 A1 a valve tappet in the course of a mechanical valve train of an internal combustion engine is known, wherein the valve tappet zwi¬ rule a gas exchange valve and the periodic drive is an¬ arranged and provided with a lateral oil supply ein¬ set in a housing. Within the valve stem an axially displaceable compensating piston is arranged with an oil reservoir, wherein the Ölvorrats- one spatial extent controlled by a check valve outlet and the other end has a connection opening to an adjacent component of the valve train, a push rod.

Within the balance piston in the oil reservoir adjacent to the connection opening to the push rod, a plate-shaped flow restrictor for oil is arranged. This flow limiter is floatingly mounted in such a way that it can move axially in limited operation. For this purpose, an inner wall of the balance piston carries a radially inwardly facing and circumferential nose on which the plate is caused by gravity, e.g. when the internal combustion engine is stopped, it comes to rest in one of its end positions.

Set in operation under oil pressure, this plate lifts from its seat and ges¬ tattet an oil flow from the oil reservoir of the balance piston in the geodetically overhead push rod. In order to permit an oil return for a first filling after assembly or when the internal combustion engine is turned off, this prior art proposes that the plate be designed in such a way that when it rests on the revolving nose, the blocking function is canceled and a limited oil volume return flow is permitted , For this purpose, it is provided that either a defined opening is formed in the closed plate or lateral recesses or a peripheral configuration are provided. When lifted from the seat operation, the plate is um¬ flows on the radially outer edge. Since the opposing surface lying above the plate is crowned, the plate comes to rest on this surface, but an oil volume outflow against the upward force of gravity is possible.

A disadvantage of this known device is that the plate is difficult to handle during assembly, since it represents a comparatively filigree, manually inserted component. Furthermore, the intended control of the oil return depends on the plate movement, which in turn depends on a variety of tolerances and the particle freedom of the oil. If the adherence to these parameters does not occur over the lifetime of the components, an excessively large oil volume drain must be expected in the event of tilting or jamming of the plate, which can jeopardize the function of the entire internal combustion engine.

Object of the invention

The object of the invention is to design a hydraulic valve tappet in such a way that the oil volume flow flowing into adjacent components is limited to a value ensuring safe operation of the internal combustion engine.

Solution of the task

This object is achieved according to the features of the main claim by a hydraulic valve lifter in the course of a mechanical Ventiltrie¬ bes an internal combustion engine, especially for motor vehicles, the valve stem between a gas exchange valve and its periodic An¬ drive arranged effectively and provided with a lateral oil supply in a Housing is inserted within the valve stem an axially limited slidable balance piston is arranged with an oil reservoir, this oil reservoir at one end controlled by a check valve Aus¬ gang and the other end has a connection opening to an adjacent Bau¬ part of the valve train and within the balance piston in the oil reservoir next to the connecting opening a flow restrictor ange¬ is arranged. This flow restrictor is designed in accordance with the further feature of the invention as sieve pressed into the compensating piston in a fixed position.

This structure has the advantage that during assembly of the flow restrictor can be pressed, whereby it is fixed in place for the lifetime of its operation despite the axial acceleration occurring.

The design as a sieve allows such a design that over the permeability of the sieve, e.g. via mesh sizes, pore sizes or similar a precisely defined oil volume flow is adjustable. This can therefore be adjusted so that an excessive oil drain and, associated therewith, an oil pressure drop which is too high to overload the upstream oil circulation elements, such as e.g. the oil pump can lead, is safely avoided. Therefore, the longevity and reliability is increased.

The subclaims describe preferred developments or Ausgestal¬ lines of the invention.

Thus, in an advantageous embodiment, it can be provided that, in the case of a two-part design of the compensating piston, with a piston upper part assigned to a gas exchange valve and a piston bottom bearing the check valve, the sieve is arranged in the piston upper part. This has the advantage during assembly that the sieve can be pressed into the piston upper part in advance, which can then be connected to the lower piston part and then inserted into the valve tappet housing. Preferably, the piston upper part has a plan-shaped, the Kolbenunter¬ part facing and adjacent to this underside with a kreiszylindri¬'s recess, in which the sieve is arranged pressed. Die¬ ses advantageously has a particularly simple manufacturing or assembly and an immediate control of the connection opening and the volume flow over it ent result.

Another advantageous embodiment provides that the lateral Ölversor¬ supply of the valve stem in the balance piston formed transverse channels, which are arranged lying upstream of the screen in the flow direction. This has the advantage that in any case the entire oil volume flow first flows into the storage space and then the discharge controlled by the sieve can take place.

Short description of the drawing

The invention will be explained in more detail below with reference to the accompanying drawings. Therein, the single figure shows a cross section through an upper part of a hydraulic valve lifter.

Detailed description of the drawing

A known per se and therefore not shown in detail valve train of an internal combustion engine used in a motor vehicle has in its wake, inter alia, a hydraulic valve lifter 2, which is basically of known per se structure with integrated valve clearance compensation. In a bore, not shown, of a cylinder head or Kurbelgehäu¬ ses a housing 4 is inserted, in the inner bore 6, a sleeve 8 is arranged stationary. In this an axially limited sliding two-piece compensating piston 10 is arranged.

A piston upper part 12 carries a pan 14 with a connection opening 16 for oil, wherein a push rod, not shown, engages correspondingly in this pan 14 with the interposition of a ball element indicated in the figure by a line 44.

A lower piston part 18 adjoining the upper piston part 12 carries at the lower end a non-return valve 20 which controls an outlet 22 from an oil reservoir 24 to a high-pressure chamber 26.

The valve tappet 2, which is shown only partially, carries a roller at its lower end, which is not shown, which is periodically driven by cams of a rotating camshaft. The aforementioned ball element transmits the movements by means of the push rod and a rocker arm to a gas exchange valve.

The oil supply of the valve stem 2 takes place laterally such that via a transverse bore 28 in the housing 4, a trained in the sleeve 8 annular channel 30 is filled. This is in turn via an inclined bore 32 with Querkanä¬ len 34 in the balance piston 10 in connection, such that the oil reservoir 24 is filled with pressure oil.

The upper piston part 12 has a flat underside 36 which faces the piston lower part 18 and adjoins it, into which a circular-cylindrical recess 38 is centrally inserted running from the underside 36 in the direction of the rail 14. A sieve 40, as shown in the figure with a dotted line, is pressed into this recess 38 as flow restriction. The screen 40 is located downstream of the oil volume flow immediately before the Ver¬ connection opening and thus controls or controls the oil flow from the oil reservoir 24 out, illustrated by the arrow 42nd

List of reference numbers

2 valve tappets

4 housing

6 hole

8 sleeve

10 balance piston

12 piston upper part

14 pan

16 connection opening

18 piston lower part

20 check valve

22 output

24 oil storage room

26 high pressure room

28 transverse bore

30 ring channel

32 oblique hole

34 cross channel

36 bottom

38 recess

40 sieve

42 arrow

44 line

Claims

claims

1. Hydraulic valve lifter (2) in the course of a mechanical valve train of an internal combustion engine, in particular for motor vehicles, wherein the

Valve tappet (2) between a gas exchange valve and its periodi¬ cal drive arranged effectively and provided with a lateral Ölversor¬ supply is inserted into a housing, wherein within the valve tilsößels (2) an axially displaceable compensating piston (10) with an oil reservoir ( 24), this oil storage space (24) has at one end an outlet (22) controlled by a check valve (20) and at the other end a connection opening (16) to a neighboring component of the valve drive, and with one within the compensating piston (10 ) in the oil reservoir (24) adjacent to the connection opening (16) arranged flow restrictor, characterized ge indicates that the flow restrictor as in the Ausgleichskol¬ ben (10) fixed in place pressed sieve (40) is formed.

2. Valve tappet according to claim 1, characterized in that the compensating piston (10) is formed in two parts, with a Gaswech¬ selventil associated piston upper part (12) and the Rückschlag¬ valve (20) carrying the piston lower part (18), characterized in that the sieve (40) is arranged in the piston upper part (12).

3. Valve tappet according to claim 2, characterized in that the Kol¬ benoberteil (12) has a plan trained, the piston lower part (18) zuge¬ facing and adjacent to this underside (36) having a kreiszylind¬ recess (38), in which the sieve (40) is arranged pressed. Tappet! according to claim 3, characterized in that the seit¬ Liche oil supply in the compensating piston (10) formed transverse channels (34), which are arranged in the direction of flow upstream of the sieve (40) lie¬ lowing.