DE102007021856A1 - Switchable cam follower of valve gear of combustion chamber - Google Patents

Abstract

The switchable cam follower (1) comprises an outer lever (2) between whose side walls (4, 5) is an associated turnable inner lever (3) that has two spars (6, 7) between which is a counter running surface (8) for cams. The outer lever has a unit (12) for a gas exchange valve on the valve-sided end and a swivel bearing (9, 10) on the other end. The outer lever has a hydraulic support element (11) that is mountable, whilst a coupling (16) is located longitudinally slidable in the inner lever and facilitates the coupling between the inner lever and the outer lever. The longitudinal axis (A) of the swivel bearing is cut by the longitudinal axis (B) of the coupling.

Description

Name of the invention

switchable Drag lever of a valve train of an internal combustion engine

Field of the invention

The The invention relates to a switchable cam follower of a valve train an internal combustion engine, the on different valve strokes for at least one gas exchange valve is switchable, with a Outside lever, between its side walls to this relatively pivotable inner lever is arranged, which having two spaced apart arms, between which a Mating surface runs for a cam, wherein the outer lever at a valve-side end a Plant for a gas exchange valve and at the other end a pivot bearing through which the outer lever on a hydraulic Supporting element is pivotally mounted, and arranged with a longitudinally displaceable in the inner lever Coupling means, through which the outer lever and the inner lever can be coupled to each other, wherein the longitudinal axis of the coupling means the longitudinal axis of the pivot bearing intersects, and wherein the Inner lever and the outer lever by at least one lost-motion spring are braced against each other.

Background of the invention

switchable Drag levers enable switching between two valve lifts to the valve lift switching or between full stroke and zero stroke to the valve or cylinder deactivation in engines with overhead camshaft. As a result, depending on the engine load, the thermodynamic efficiency of the Optimized engine.

switchable Drag levers usually consist of two in one another mounted levers, the so-called inner and outer lever. The inner lever or primary lever rests on a hydraulic support element and the engine valve from. About a located in cam contact role of the small valve lift transferred to the valve. The outside lever or secondary lever is valve side by means of a rotation axis stored on the inner lever. A lost-motion spring tightens the outer lever opposite the inner lever and pushes the inner lever on the valve stem. Both levers are via a coupling mechanism locked together. In the locked state, the large Stroke over sliding surfaces on the outer lever transfer the valve.

From the US 5,54,626 Such a switchable drag lever is known, which has a two-part valve lever, wherein an outer lever is formed overall U-shaped and is supported with its web on a hydraulic valve clearance compensation element. The inner and outer levers are connected to one another via a connecting axle on the valve side and can be coupled to one another on the pivot point side. At the ends of the two arms of the U-shaped outer lever of the inner lever is pivotally mounted, which carries a roller for sensing a cam of the camshaft. The free end of the inner lever can be locked on a web connecting the arms of the outer lever, for which a movably guided in the web of the outer lever piston is moved by means of a supplied from the hydraulic valve lash adjuster hydraulic fluid pressure in a formed on the inner lever recess. When the locking device is locked, the valve lever acts as a one-piece lever that transfers the cam lift to the valve. When the locking device is released, the inner lever plunges into the outer lever, so that the valve is not actuated. On the valve side, a lost-motion spring in the form of a torsion leg spring is positioned in the inner lever or on the outer lever above the valve support.

Similar technical solutions are from the DE 10 2005 037 051 A1 known as well as from the DE 103 45 307 A1 , of the DE 10 2004 007 766 A1 and the DE 10 2004 017 103 A1 , which are particularly concerned with coupling mechanisms, which are each formed there as longitudinally displaceable annular piston.

So is according to the DE 103 45 307 A1 provided that the coupling means designed as an annular piston extends over the outer shell in a continuous smooth through bore of the inner lever and for the coupling case partially in or under a corresponding cam surface of an end side crossbar of the outer lever is hydraulically displaceable, wherein the displacement in Entkoppelstellung on the force of at least one mechanical Spring is realized, wherein in a bore of the coupling means is a cylindrical part such as a piece of pipe which is mounted via a pressed into a bore of this part and this radially expanding element as a ball in the bore, said part of an inner end face of the coupling means via the through hole protrudes beyond and ends there passes into a spring plate, and wherein this part is guided through a bore of a stop sleeve secured in the through hole, said bore being removed at its the coupling means Side passes over an annular shoulder in a diameter extension, wherein at one end of the annular shoulder, the spring is applied, the other end acts against the spring plate.

From the DE 102 20 904 B4 Another switchable drag lever is known, the inner and outer levers are also connected to each other valve side via a connecting axis and pivot point side can be coupled together. As a spring element here no torsion leg spring, but a pair of helical compression springs is used, which are each mounted in a recess of the outer lever and in a recess of the inner lever and act on the inner lever from below in the coupling point and the pivot point with a force.

Another solution is from the DE 101 55 800 A1 known. In this drag lever is provided that the outer lever is made largely fork-like open, wherein the contact surface for the cam on the inner lever is designed as a rotatable roller and the coupling means are one or more transverse to the longitudinal direction of the finger lever slider whose axial line with an axial line for the Role coincides. In addition, it is provided that the pivot center of the inner lever is at least approximately the same length of the finger lever as a pivot center of the outer lever in the region of its complementary surface. There is also proposed there to provide as a complementary surface for supporting the rocker arm on the support a dome or cylindrical surface. It is also proposed in this document to provide the outer lever with the dome for receiving one end of a hydraulic support element and to support the inner lever pivotable on an upper side of this dome.

From the DE 696 14 166 T2 Finally, a lockable rocker arm with inner and outer levers is known, which are mounted on a support element for pivotal movement via a double or tandem calotte arrangement. Inner lever and outer lever are extended to the rear over the pivot point such that between them a helical compression spring is added, which acts on its outer and inner levers with their spring force.

Even though the drag or rocker arms described above each interesting Solution details, it has not yet been possible switchable towing levers to optimize such that a total of compact and low-inertia we kender mechanism arises. For rocker arms with a valve-side connection by a Connection axis, it is disadvantageous that the relatively fulcrum away Arrangement of this connection axis, and usually as a torsion leg spring trained Lost motion spring to a comparatively high moment of inertia and lead a low rigidity of the switchable rocker arm. This has a negative effect on the dynamic valve train behavior high forces and high friction and maximum achievable engine speed off. Furthermore, the technically more complex External lever because of the necessary material accumulation in the locking area not easy and inexpensive be made from a sheet in a stamping and forming process.

at However, these drag levers have the coupling mechanisms in the form proven by longitudinally displaceable piston. alternative technical solutions where the outside lever and the inner lever via a double calotte with each other pivotally connected, so far have the disadvantage, that the coupling mechanisms used there elaborately designed are or also in one the moment of inertia negatively influencing distance to the pivot point of the finger lever are arranged.

The Most known rocker arms also has the disadvantage that the use of sheet metal parts for external levers and internal lever is not always possible, so that expensive milling or castings must be used.

Object of the invention

Of the Invention is based on the object, a switchable drag lever to create, which does not have the disadvantages described. In particular, a drag lever is to be created, the compact is constructed and its functional components for the Locking of outer lever and inner lever as possible are arranged close to the fulcrum.

Summary of the invention

Of the Invention is based on the finding that the asked Task in a surprisingly simple way thereby lets loose that the pivoting connection of outside lever is formed with inner lever as a double calotte, and that at least a Lost-motion spring acts from above on the inner lever, wherein the distance between the longitudinal axis of the lost-motion spring and the longitudinal axis of the pivot bearing is as low as possible.

According to the features of the main claim, the invention is therefore based on a switchable rocker arm of a valve train of an internal combustion engine, which is switchable to different valve lifts for at least one gas exchange valve, with an outer lever, between whose side walls to this relatively pivotable inner lever is arranged, which two to each other having spaced arms, between which a mating surface extends for a cam, wherein the outer lever at a valve end end a system for a gas exchange valve and at the other end a pivot bearing, through which the outer lever is pivotally mounted on a hydraulic support element, and with a in the inner lever arranged longitudinally displaceable Coupling means by which the outer lever and the inner lever are coupled to each other, wherein the longitudinal axis of the coupling means intersects the longitudinal axis of the pivot bearing, and wherein the inner lever and the outer lever are braced against each other by at least one lost-motion spring. In addition, it is provided that the outer lever and the inner lever are pivotally coupled to each other by a double calotte and to the hydraulic support element, and that the at least one lost-motion spring impinges a top side of the inner lever with a force on the pivot point side, wherein a longitudinal axis of the Lost motion -Feder is arranged parallel to the longitudinal axis of the pivot bearing.

By This structure is advantageously achieved that all essential Functional parts, ie pivot or pivot point of the outer lever and inner lever, connection of the lost-motion springs and the coupling agent as far as possible in cover or in the immediate axial Close to by the hydraulic support element formed pivot point are arranged. This is an extremely compact and fast responding drag lever created.

in the Contrary to the otherwise preferred rocker arms are the lost-motion springs so not valve side, but pivot point side mounted and brace Inner lever and outer lever with each other. This is eliminated an otherwise necessary connection axis, whereby the total mass of the rocker arm decreases and thus the inertia This rocker arm is reduced, which is why the maximum speed be increased in such a equipped internal combustion engine can. Furthermore, the outer lever can be used in a cost-effective sheet metal forming or sheet metal forming process are produced.

to Inertia reduction is adjacent to the pivot point side Position of the at least one lost-motion spring also the arrangement the locking device of the rocker arm. It turns out In addition, a good guidance of the inner lever in the outer lever by the same coordinate origin over the said Dual cone. Likewise, investigations have shown that a simplified assembly of at least one lost-motion spring results, because this can be mounted as the last part, while so far just the assembly and clamping of trained mostly as a torsion leg spring Lost motion spring was comparatively expensive.

According to one Design of a drag lever according to the invention is to be provided that the pivot bearing of the outer lever from an inner lever pointing dome and one to the hydraulic Abstützelement directed socket consists, and that formed in a bottom of the inner lever, a socket is, which rests on the calotte of the outer lever, wherein a double dome through the dome of the outer lever and is formed by the socket of the inner lever.

In other practical developments may also be provided be that the at least one lost-motion spring, a helical compression spring is, which is pivot point side against an upper side of the inner lever and against a parallel to the top of the inner lever extending Supported on the outer lever. This embodiment can be supplemented by the fact that the number the lost-motion spring is between one and three.

A Another embodiment of the invention provides that at least a trained as a helical compression spring lost motion spring against a Top of the inner lever and against a parallel to the top of the Inner lever extending board of the outer lever is supported.

These Design can be supplemented by that extended the board of the outer lever from the top Rear wall of the outer lever angled off valve side is and partially covers the inner lever.

Especially Also advantageous is an embodiment of the invention, which is characterized in that the coupling means of a pressurizable Piston consists, which in a longitudinal bore is mounted longitudinally displaceable in the inner lever, wherein a Piston rod of the piston in a hole in a rear wall of the outer lever for coupling the outer lever with the inner lever is insertable.

As well it is within the scope of the invention to provide that the outer lever is designed as a sheet metal part or as Blechtiefziehteil.

A Other practical embodiment of the invention is characterized out that the outer lever and the inner lever by a Doppelkalotte, so by two superposed calotte on External lever or on the inner lever, valve side with each other are coupled.

When Advantageously, it is also judged when the mating surface for the cam of a camshaft of an internal combustion engine is a roller bearing roller.

Brief description of the drawings

The Invention will be described below with reference to the accompanying drawings an embodiment explained in more detail. It shows

1 a longitudinal section through an embodiment of a finger lever according to the invention,

2 the drag lever off 1 in plan view,

3 a drag lever similar to the one 1 in a perspective view,

4 the drag lever off 3 in longitudinal section,

5 the drag lever off 3 from the front,

6 the drag lever off 3 from behind,

7 the drag lever off 3 from underneath,

8th the drag lever off 3 from one side,

9 the drag lever off 3 from the other side, and

10 the drag lever off 3 from above.

Detailed description the drawing

In the 1 to 10 is in each case an embodiment of a switchable rocker arm 1 shown for a valve drive, not shown, of an internal combustion engine. The rocker arm 1 has an outside lever 2 and an inner lever 3 on, the latter between two side walls 4 . 5 of the outer lever 2 is arranged and stored. The inner lever 3 has two spaced apart arms 6 . 7 on, between which a roller bearing roller 8th as a mating surface for a cam, not shown, of a camshaft runs. The outside lever 2 has at one end at a bottom as a dome 9 or joint socket 10 trained pivot bearing on. Above this is the outside lever 3 on a in 1 only indicated hydraulic support element 11 pivotable storable. At the other end, the outer lever has an attachment at the bottom 12 for preferably a gas exchange valve.

In a bottom 13 of the inner lever 3 is also a dome or a socket 14 incorporated, which on the outer circumferential surface of the dome 9 the outer lever is seated. As a result, the outer lever 2 and the inner lever 3 through the connection via a so-called double dome 15 pivotable with each other and with the hydraulic support element 11 coupled so that the fulcrum of the outer lever 2 with the pivot point of the inner lever 3 coincides. However, it is within the scope of the invention also possible, the outer lever 2 and the inner lever 3 through such a double dome 15 to be coupled with each other on the valve side (not shown).

A coupling agent 16 in the form of a piston-cylinder arrangement has a piston 17 on, in a longitudinal bore 18 in the inner lever 3 is stored. The coupling agent 16 or the piston 17 is so in the hole 18 of the inner lever 3 stored that the longitudinal axis of the piston 17 the longitudinal axis of the support element 11 or the longitudinal axis of the pivot bearing 9 . 10 cuts. The piston 17 is by a helical compression spring 19 , which are against a disc 20 supported with axial approach, permanently loaded with a force. The piston 17 can be switched by an injectable hydraulic fluid, ie against the pressure of the helical compression spring 19 move axially. For this purpose, the hydraulic fluid through the head of the support element 11 , a hole 21 in the outer lever 2 and a hole 29 in the inner lever 3 into the hole 18 of the coupling agent 16 fed.

There is no hydraulic pressure on the piston 17 on, so presses the helical compression spring 19 a piston rod 22 of the piston 17 into a hole 23 in a back wall 24 of the outer lever 2 , causing the outer lever 2 and the inner lever 3 coupled together.

If the piston rod 22 by hydraulic pressure in the direction of the helical compression spring 19 is shifted, is the coupling of outside lever 2 and inner lever 3 lifted, leaving the inner lever 3 by means of the socket 14 on the calotte 9 of the outer lever 2 can pivot when on the roll 8th acting cam the inner lever 3 forces you to swivel down.

So the inner lever 3 after the action of the cam can return to its original position, are the inner lever 3 and the outside lever 2 through lost-motion springs 25 in the form of two helical compression springs 26 braced against each other. The helical compression springs 26 support themselves against a top 27 of the inner lever 3 and against a parallel to the top 27 of the inner lever 3 running board 28 of the outer lever 2 from. The board 28 is from the upwardly extended rear wall 24 of the outer lever 2 angled towards the valve and covers the inner lever 3 partially off. Instead of two helical compression springs 26 It is also possible to choose a different number, for example a helical compression spring 26 , or three or more helical compression springs 26 ,

In contrast to the otherwise preferred rocker arms are the lost-motion springs 25 . 26 so not valve side, but pivot point side and brace there the inner lever 3 and the outside lever 2 up to today. This eliminates an otherwise necessary connection axis whereby a mass inertia reduction compared to conventional rocker arms is realized. Furthermore, the outer lever 2 be produced in a low-cost Blechumform- or Blechtiefziehverfahren.

The longitudinal axis A of the pivot bearing 9 . 10 or the support element 11 , the longitudinal axis B of the coupling agent 16 and the longitudinal axis C of the lost-motion spring 25 . 26 are in 4 shown. It can be seen in particular that the longitudinal axis C of the lost-motion spring 25 . 26 parallel and at a small distance from the longitudinal axis A of the support element 11 or the pivot bearing 9 . 10 runs. However, it is also possible to bring the two longitudinal axes A and C in coincidence, that is, to extend coaxially.

For inertia reduction further contributes that all essential functional parts, ie pivot or pivot point of the outer lever 2 and inner lever 3 , Connection of the lost motion springs 25 respectively. 26 , as well as the coupling agent 16 as far as possible in cover or in the immediate axial proximity to the hydraulic support element 11 arranged pivot point are arranged or concentrated there. This is an extremely compact and responsive drag lever 1 created, which can increase the maximum speed of a so-equipped internal combustion engine.

The outside lever 2 can be used in addition to the illustrated embodiments as a common part for standard valve trains.

1

cam follower

2

external lever

3

internal lever

4

Side wall of the outer lever

5

Side wall of the outer lever

6

poor of the inner lever

7

poor of the inner lever

8th

role

9

dome

10

socket

11

hydraulic supporting

12

investment

13

bottom of the inner lever

14

socket

15

dual cone

16

coupling means

17

piston

18

Bore of the coupling agent 16 in the inner lever 2

19

Helical compression spring

20

disc

21

drilling to outside lever

22

piston rod

23

drilling

24

rear wall of the outer lever

25

Lost-motion spring

26

Helical compression spring

27

top of the inner lever

28

shelf

29

drilling on the inner lever

A

longitudinal axis

B

longitudinal axis

C

longitudinal axis

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• US 554626 [0005]
• - DE 102005037051 A1 [0006]
• - DE 10345307 A1 [0006, 0007]
• - DE 102004007766 A1 [0006]
• - DE 102004017103 A1 [0006]
• - DE 10220904 B4 [0008]
• - DE 10155800 A1 [0009]
• - DE 69614166 T2 [0010]

Claims (10)

Switchable drag lever ( 1 ) of a valve drive of an internal combustion engine, which is switchable to different valve lifts for at least one gas exchange valve, with an outer lever ( 2 ), between its side walls ( 4 . 5 ) a to this relatively pivotable inner lever ( 3 ), which has two mutually spaced arms ( 6 . 7 ), between which a mating surface ( 8th ) for a cam, wherein the outer lever ( 2 ) at a valve-side end a plant ( 12 ) for a gas exchange valve and at the other end a pivot bearing ( 9 . 10 ), through which the outer lever ( 2 ) on a hydraulic support element ( 11 ) is pivotally storable, and with a in the inner lever ( 3 ) longitudinally displaceable coupling means ( 16 ), through which the outer lever ( 2 ) and the inner lever ( 3 ) can be coupled to each other, wherein the longitudinal axis (B) of the coupling means ( 16 ) the longitudinal axis (A) of the pivot bearing ( 9 . 10 ), and wherein the inner lever ( 3 ) and the outer lever ( 2 ) by at least one lost-motion spring ( 25 ) are braced against each other, characterized in that the outer lever ( 2 ) and the inner lever ( 3 ) by a double dome ( 15 ) pivotally with each other and with the hydraulic support element ( 11 ) and that the at least one lost-motion spring ( 25 ) pivot side an upper side ( 27 ) of the inner lever ( 3 ) is acted upon by a force, wherein a longitudinal axis (C) of the lost-motion spring ( 25 ) parallel to the longitudinal axis (A) of the pivot bearing ( 9 . 10 ) is arranged. Drag lever according to claim 1, characterized in that the pivot bearing ( 9 . 10 ) of the outer lever ( 2 ) from one to the inner lever ( 3 ) pointing calotte ( 9 ) and from one to the hydraulic support element ( 11 ) directed socket ( 10 ) and that in an underside ( 13 ) of the inner lever ( 3 ) a socket ( 14 ) formed on the calotte ( 9 ) of the outer lever ( 2 ), whereby a double dome ( 15 ) through the calotte ( 9 ) of the outer lever ( 2 ) and through the socket ( 14 ) of the inner lever ( 3 ) is formed. Drag lever according to claim 1 or 2, characterized in that the at least one lost-motion spring ( 25 ) a helical compression spring ( 26 ), which pivot point side against a top ( 27 ) of the inner lever ( 3 ) and against a parallel to the top ( 27 ) of the inner lever ( 3 ) running board ( 28 ) of the outer lever ( 2 ) is supported. Cam follower at least according to claim 3, characterized in that the number of the lost-motion spring ( 25 . 26 ) is between one and three. Drag lever according to at least one of claims 1 to 3, characterized in that at least one lost-motion spring ( 25 . 26 ) against a top ( 27 ) of the inner lever ( 3 ) and against a parallel to the top ( 27 ) of the inner lever ( 3 ) running board ( 28 ) of the outer lever ( 2 ) is supported. Cam follower according to claim 5, characterized in that the board ( 28 ) of the outer lever ( 2 ) from the upwardly extended rear wall ( 24 ) of the outer lever ( 2 ) is angled off valve side and the inner lever ( 3 ) partially covers. Drag lever according to at least one of claims 1 to 6, characterized in that the coupling means ( 16 ) from a pressurizable piston ( 17 ), which in a longitudinal bore ( 18 ) in the inner lever ( 3 ) is mounted longitudinally displaceable, wherein a piston rod ( 22 ) of the piston ( 17 ) into a hole ( 23 ) in a back wall ( 24 ) of the outer lever ( 2 ) for coupling the outer lever ( 2 ) with the inner lever ( 3 ) is insertable. Cam follower at least according to claim 1, characterized in that the outer lever ( 2 ) is designed as sheet metal forming part or as sheet deep drawing part. Cam follower at least according to claim 2, characterized in that the outer lever ( 2 ) and the inner lever ( 3 ) by a double dome ( 15 ), so by two superimposed calottes of outer lever ( 2 ) and inner lever ( 3 ), valve side coupled together. Drag lever at least according to claim 2, characterized in that the mating surface for the cam a roller bearing roller ( 8th ).