DE102008032720A1 - Valve gear for internal combustion engine, has outer common spring with spring collar, which is connected with shaft by coupling unit in extended condition and is arranged above spring collar of inner common spring - Google Patents

Abstract

The gear (1) has a switchable outer common spring (5) and a non-switchable inner common spring (6) with ends (8), and supported against a cylinder body (9) in a location-attached manner. Separate spring collars (11, 12) of the outer and inner springs directly run at shaft (4), and are applied to the springs. The spring collar of the outer common spring is axially moved against the shaft, is connected with the shaft by a coupling unit (13) in an extended condition, and is arranged above the spring collar of the non-switchable inner common spring.

Description

Field of the invention

The The invention relates to a valve train of an internal combustion engine with a switchable double spring device for a gas exchange valve, the shaft of an outer and an inner Entire spring enclosed and acted upon by a cam follower is what total springs with their one end against a cylinder head and act with their other end against a respective spring plate, wherein one of the total springs can be switched off.

Background of the invention

Valve springs are usually designed for the rarely driven range of maximum speed, ie the spring rate is chosen very high, in order to guarantee a safe valve closing even at maximum speeds. This is a her ago that the valve springs for the stochastically seen mostly driven medium to low speed range (<4000 rev / min) are significantly oversized and thus leads to increased friction or high wear. In order to eliminate this deficiency, the experts have tried to adapt the valve spring force to the speed-dependent demand of the internal combustion engine. So revealed the DE 101 55 106 A1 a double spring valve drive, the inner valve spring is hydraulically switched off / lowered. The disadvantage of this device that costly changes to the cylinder head itself must be made (large volume depression), this exactly in an area where anyway little space is available. Furthermore, the indicated hydraulic impingement proves to be complex and subject to leakage.

Object of the invention

task The invention is therefore a valvetrain of the aforementioned type in which the cited disadvantages are eliminated.

Solution of the task

According to the invention solved this problem by the fact that the total springs with its one end supported stationary against the cylinder head the other end being a separate one for each is applied directly on the shaft extending spring plate and wherein the spring plate of the turn-off outer total spring axially movable relative to the shaft and over at least one coupling agent in its "extended" state with connectable to the shaft and above the spring plate of the non-disconnectable, inner total spring is arranged.

Consequently is a valve train created in which the disadvantages indicated are eliminated. The valve train is required in the cylinder head area only little space, so that usually the cylinder head or not only slightly changed. Furthermore the proposed valve train is relatively simple and with a simple external admission via an actor provided, for example, electromagnetic or hydraulic Nature can be.

When respective total spring is at least one helical compression spring or provided a helical compression spring package. It is also conceivable, at least to represent one of the total springs as an air spring.

When Cam follower, which acts on the valve stem at least indirectly, For example, a towing, oscillating or rocker arm in question. Furthermore, an impingement by a bucket tappet possible. The aforementioned rocker arm can also be part be a push rod drive.

at the proposed Entkoppelmechanismus are only minor changes required at the gas exchange valve itself, so that also gas exchange valves can be used with a very small shaft diameter. For engagement of the coupling means is only on the outer jacket the shaft to provide an annular groove or the like. Conveniently, should be used as a coupling agent at least one ball or the like become. Conceivable are in this place also roles, pens, etc., where it is advantageous if the recess for this purpose on the outer jacket the valve stem is shown complementary.

Though It is proposed according to the invention, the rotary valve over to relocate an external actuator that faces from a sidewall of the Cylinder head emanates and, for example, driven electromagnetically may be, but may also be a hydraulic Raising or lowering of the longitudinal slide in the upper spring plate respectively. The longitudinal slide, but also at least the upper one Federteller, as a simple extrusion or Deep-drawn parts be executed. If necessary, too the outer casing of the valve stem in the region of a sliding contact of the upper spring plate (switch-off case) with separate wear protection measures be provided. Due to the wedge-like profile of the ring slide different positions of the coupling agent can be compensated become. The angle of the clamping portion of the annular slide is so chosen that in the coupling case of a perfectly safe Clamping effect is achieved.

The aforementioned annular groove in the shaft of the gas exchange valve can be conveniently prepared by a process such as rolling or turning. In this case, the annular groove, at least at its upper side expediently has a conical profile, whereby tolerances can be perfectly compensated.

A simple measure of a connection of the lower spring plate with the gas exchange valve is the subject of another subclaim. Therefore can the lower spring plate in its support direction (cam follower direction) on a simple projection such as a locking ring or the like abut with its upper end face.

Of Another is a stop for the upper, axially movable Spring plate Subject of a subclaim. This stop is in an advantageous manner as the bottom of a thin-walled Executed sheet metal housing, which is the inventive Doppelfedervorrichtung einhaust and with its lower bottom sitting on the cylinder head. If necessary, also external, come from the cylinder head over the upper spring plate extending Attacks in question. The aforementioned sheet metal housing can again be presented in a simple thermoforming process. Its upper bottom becomes, after all components like Spring plate with total springs, coupling means, longitudinal slide are mounted with compression spring, bent like a collar radially inwards.

Short description of the drawing

The Invention is suitably with reference to the drawing explained in more detail. Show it:

1 a longitudinal section through a valve train with a switchable double spring device in the coupled state and cam lift and

2 the aforementioned valve train in an enlarged view, in the decoupling mode and cam lift.

Detailed description the drawing

Shown is a valve train 1 with a switchable double spring device 2 for a gas exchange valve 3 , A shaft 4 of the gas exchange valve 3 is from an inner overall spring 6 includes, in turn, an outer overall spring 5 is enclosed. The total springs 5 . 6 support themselves with their one, lower end 8th on a lower ground 33 a thin-walled housing 32 from. The housing 32 thus houses the double spring device 2 one. An upper floor 34 of the housing 32 serves as a stop part 31 for the upper spring plate 11 (Decoupling mode, see below). Over the bottom floor 33 the housing sits 32 on a cylinder head 9 ,

The aforementioned outer total spring 5 acts with her other end 10a against the upper spring plate 11 , The inner total spring 6 works with its other end 10b against a lower spring plate 12 disk-like geometry. The latter is with the shaft 4 in the area of its upper end face 30 through a circlip 30a connected. It has the outer overall spring 5 optionally a higher spring rate than the inner total spring 6 ,

The spring plate 11 the outer overall spring 5 is axially movable with respect to the shaft 4 held. It has an annular recess open in the direction of the cam follower 14 on. Radial inside he goes into one on the outer jacket 26 the shaft 3 adjoining pipe section 23 over which one with a bore 28 directly on the outer jacket 26 runs.

Within the aforementioned ring recess 14 sits a ring slide 15 , whose inner coat 16 is formed zweigestuft. He has a lower, tapering in the valve direction clamping portion 17 , which at its upper side in a ring-shaped enlarged receiving space 18 passes over, from the top of a radial collar 19 projects. Against a bottom of the aforementioned radial collar 9 a compression spring acts 21 in Ausschiebenesinn, the other ends against a floor 22 the ring recess 14 is supported.

The inner jacket 16 of the slide ring 15 comprises circumferentially distributed and formed as balls coupling means 13 , For example, two diametrically opposite or three circumferentially distributed balls (optionally also in respective pockets) may be applied.

1 discloses the coupling state of the double spring device 2 at cam lift. It can be seen that the ring slide 15 over the compression spring 21 is ejected in the cam follower direction. Thus, the coupling agents 13 over the underlying, conical clamping section 17 in sections in a shaft 4 extending annular groove 25 held. Both total springs 5 . 6 are thus "active" (high speed of the internal combustion engine). The coupling agent 13 thereby run on an upper forehead 24 of the pipe section 23 of the upper spring plate 11 ,

Should the outer total spring 5 be deactivated (low speed of the internal combustion engine ...), then the base follower of the cam follower 7 acting Hubnockens 36 an actor 27 (S. 2 ) on the radial collar 19 of the slide ring 15 pivoted so, the latter is moved in the valve direction and the coupling means 13 the recording room 18 on the inner jacket 16 of the slide ring 15 are opposite. During the subsequent cam lift, the coupling means become 13 , with downwardly moving gas exchange valve 3 , above a conically shaped top of the annular groove 25 in the shaft 4 "Pushed out" and into the recording room 18 relocated. The upper spring plate 11 with outer total spring 5 is thereby decoupled from the gas exchange valve 3 and accomplishes a Leerhubbewegung relative to this. Thus, only the weaker, inner total spring 6 in the closing direction of the gas exchange valve 3 active.

Should the outer total spring 5 with upper spring plate 11 be switched, then the actor 27 in his in 1 swung away rest position shown. In the cam base circle, in which then the coupling means 13 turn the ring groove 25 opposite, the compression spring 21 of the slide ring 15 active and displaced in such a way in the cam follower direction that the coupling means 13 over the clamping section 17 in sections in the annular groove 25 in the shaft 4 are relocated.

As the expert readily recognizes, a so-called drag lever drive is graphically disclosed. This consists of a drag lever as a cam follower 7 at one end on a support element 35 is stored and the other end on the shaft 4 of the gas exchange valve 3 acting in the hovering sense. Approximately in the area of a center is the cam follower 7 from the lift cam 36 contacted. In the contact area a Rollenabgriff is provided.

1

valve train

2

Double spring device

3

Gas exchange valve

4

shaft

5

outer total spring

6

inner total spring

7

cam follower

8th

one End of total feathers

9

cylinder head

10a, b

other End of total feathers

11

upper spring plate

12

lower spring plate

13

coupling means

14

ring recess

15

annular slide

16

inner sheath annular slide

17

clamping section

18

accommodation space

19

radial collar

20

bottom radial collar

21

compression spring

22

ground

23

pipe section

24

upper forehead

25

ring groove

26

outer sheath

27

actuator

28

drilling

29

front

30

front

30a

circlip

31

stop part

32

casing

33

lower ground

34

upper ground

35

supporting

36

lift cams

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

• - DE 10155106 A1 [0002]

Claims (10)

Valve train ( 1 ) an internal combustion engine with a switchable double spring device ( 2 ) for a gas exchange valve ( 3 ) whose shaft ( 4 ) of an outer and an inner total spring ( 5 . 6 ) and by a cam follower ( 7 ), which total springs ( 5 . 6 ) with one end ( 8th ) against a cylinder head ( 9 ) and with its other end ( 10 ) against a respective spring plate ( 11 . 12 ), one of the total springs ( 5 . 6 ), characterized in that the total springs ( 5 . 6 ) with one end ( 8th ) immovable relative to the cylinder head ( 9 ), while at the other end for each total spring ( 5 . 6 ) a separate, directly on the shaft extending spring plate ( 11 . 12 ) is applied and wherein the spring plate ( 11 ) the turn-off outer total spring ( 5 ) axially opposite the shaft ( 4 ) and at least one coupling agent ( 13 ) in its "extended" state with the shaft ( 4 ) and above the spring plate ( 12 ) of the non-disconnectable inner total spring ( 6 ) is arranged. Valve gear according to claim 1, characterized in that in an open in the direction of cam follower annular recess ( 14 ) of the upper spring plate ( 11 ) a ring slide ( 15 ) whose inner shell ( 16 ) a valve section tapering in the valve direction ( 17 ) for the coupling agent ( 13 ), the top in a ring-shaped extended receiving space ( 18 ) for the coupling agent ( 13 ), from whose upper edge a radial collar ( 19 ) protrudes, against the underside ( 20 ) at one end a compression spring ( 21 ), the other ends against a ground ( 22 ) of the ring recess ( 14 ), the latter being radially inward into one of the shafts ( 4 ) adjacent pipe section ( 23 ), either on an upper forehead ( 24 ) or in a window of the pipe section ( 23 ) the coupling agent ( 13 ), where a) for the coupling case [both total springs ( 5 . 6 ) active] the ring slide ( 15 ) via its compression spring ( 21 ) is pushed out in the direction of the cam follower, in such a way that on the inner jacket ( 16 ) extending coupling agents ( 13 ) via the clamping section ( 17 ) in sections in a radially inner opposite annular groove ( 25 ) in the outer jacket ( 26 ) of the shaft ( 4 ) of the gas exchange valve ( 3 ) and wherein b) for the decoupling case [only inner total spring ( 6 ) active] the ring slide ( 15 ) via one of its radial collars ( 19 ) contacting actuator ( 27 ) in the cam base circle in such a way in its annular recess ( 14 ) that the coupling agent ( 13 ) the receiving space ( 18 ) and with incipient cam lift in this, an annular surface between the shaft ( 4 ) and a bore ( 28 ) of the pipe section ( 23 ) of the upper spring plate ( 11 ) no longer spanning, is shifted in sections. Valve gear according to claim 1 or 2, characterized in that as a coupling agent ( 13 ) a plurality of circumferentially distributed slider are applied as balls. Valve gear according to claim 2, characterized in that as an actuator ( 27 ) on the radial collar ( 19 ) aufschwenkbarer, at least indirectly on a side wall of the cylinder head ( 9 ) fixed finger is provided which is electromagnetically acted upon in at least one pivoting direction. Valve gear according to claim 2, characterized in that the annular groove ( 25 ) in the shaft ( 4 ) is made by a process such as curling or turning out. Valve gear according to claim 1, characterized in that mutually facing end faces ( 29 . 30 ) the spring plate ( 11 . 12 ) are slightly spaced apart in the coupling case, wherein a compound of the lower spring plate ( 12 ) with the gas exchange valve ( 3 ) over one on the shaft ( 4 ) fixed projection like a circlip ( 31 ) is shown, on which the lower spring plate ( 12 ) with a front side ( 30 ) is present. Valve gear according to claim 1, characterized in that the upper spring plate ( 11 ) in its extended axial position [cam base circle] on one with the cylinder head ( 9 ) connected stop part ( 31 ) is present. Valve gear according to claim 7, characterized in that the two total springs ( 5 . 6 ) with their spring plates ( 11 . 12 ) in a housing ( 32 ), the total springs ( 5 . 6 ) with one end ( 8th ) against an inside of a first floor ( 33 ) of the housing ( 32 ) acting on the cylinder head ( 9 ) and wherein the spring plate ( 11 ) of the outer total spring ( 5 ) against an inside of a second floor ( 34 ) of the housing ( 32 ) in its extended axial position, which second floor ( 34 ) as the abutment part ( 31 ) acts. Valve gear according to claim 8, characterized in that the housing ( 32 ) is present as a thin-walled sheet metal part whose second floor ( 34 ) after a final assembly of the components [spring plate ( 11 . 12 ) with total springs ( 5 . 6 ), Coupling agents ( 13 ), Ring calipers ( 15 ) with compression spring ( 21 )] radially inwardly to the representation of the stop member ( 31 ) is bent. Valve gear according to claim 1, characterized in that the outer total spring ( 5 ), consisting of one or more compression springs, a high spring rate and the inner total spring ( 6 ), consisting of one or more compression springs, a contrast has low spring rate.