DE102008054011A1 - Valve gear of an internal combustion engine with a disconnectable support element - Google Patents

Abstract

Proposed is a valve train (1) of an internal combustion engine with a shut-off support element (2), which has a pot-shaped housing (5) built into a receptacle (3) of a cylinder head (4), in which an axially displaceable pressure piston (7) extends whose head (9) a drag lever (11) is mounted, wherein the pressure piston (7) for displaying a full valve is frictionally supported on a hydraulic fluid column (12) in a high-pressure chamber (13) between the lower end (14) and a bottom (15) of the housing (5) extends, wherein with a Absteueröffnung (16) from the high-pressure chamber (13) cooperating Absteuermittel (17) for selectively relieving the Hydraulikmittelsäule (12) are provided at Nockenhub, so that there is a 0-valve lift, wherein the Absteueröffnung (16) is present as a passage in the lower end (14) of the pressure piston (7), wherein components of the Absteuermittel (17) a valve closing body (18) at the Absteueröffnung (16) , an externally controllable biasing means (19) for the valve closing body (18) and a pressure accumulator (20) in the pressure piston (7) for the controlled hydraulic fluid are, which pressure accumulator (20) immediately above the lower end (14) of the pressure piston (7) extends and is limited by a disc-like pressure pad (21) in the direction of head, that is acted upon by at least one compression spring (22) in the pressure storage direction.

Description

Field of the invention

The The invention relates to a valve train of an internal combustion engine with a disconnectable support element, which in a Picture of a cylinder head built-in pot-like housing having a bore in which an axially displaceable plunger runs, projecting on one edge of the housing Head mounted by a lift cam operated rocker arm is, wherein the pressure piston to represent a full valve lift frictionally is supported on a hydraulic column, in a high pressure room between the forearm and one Bottom of the housing runs, with a discharge opening from the high pressure chamber cooperating Absteuermittel for optional Relieving the hydraulic column provided at Nockenhub are, so that there is a 0-valve lift.

Background of the invention

The DE 40 00 531 A1 discloses a valve train whose support member consists of a pot-like housing which is telescopically mated with an inner member. On one end of the housing superior head of the inner element is at one end a rocker pivotally mounted. The inner element is acted upon from the housing by a compression spring and is supported via a hydraulic medium column relative to the housing. The housing has a discharge opening for the hydraulic medium, which communicates with a control edge attached to a lower side of the inner element. For the purpose of switching off or adjusting the valve lift, the housing can be rotated in the bore in the cylinder head, so that depending on the rotational position of a certain amount of hydraulic fluid can escape via the Absteueröffnung and the inner element collapses to this extent.

Of the The above solution immanent several disadvantages. The Verdrehansteuerung the housing proves to be inaccurate and takes up a relatively large space in the transverse direction in the cylinder head, which space usually extremely is cramped or not available. The support element proves to be due to the high hydraulic column relatively stiff in normal operation, so with an undesirable high sinking of the support element is expected. This Subsidence must be maintained by a corresponding cam contour design become stronger and moreover with occurring foaming of the oil further. In the case of a desired control of the hydraulic column the hydraulic fluid must be expelled from the element into the supply line be displaced in the cylinder head. Especially at very high speeds the internal combustion engine is likely to be available standing time windows are not sufficient. Furthermore, will found that each support element two hydraulic fluid lines be provided in the cylinder head, which increases the construction cost.

Object of the invention

task The invention is therefore a valvetrain of the aforementioned type to create, in which the identified disadvantages are eliminated.

Solution of the task

According to the invention This object is achieved in that the Absteueröffnung is present as a passage in the lower end of the pressure piston, wherein constituents the Absteuermittel a valve closing body the Absteueröffnung, an externally controllable Beaufschlagungsmittel for the valve closing body and a Accumulator in the pressure piston for the diverted hydraulic fluid are, which accumulator immediately above the forehead of the pressure piston and of a disc-like Pressure pad is limited in the head direction, that of at least one Compressive spring is acted upon in the pressure storage direction.

Consequently is a valve train with a compact build, disconnectable Supporting element, in which the disadvantages indicated are eliminated. The abzusteuernde from the high pressure chamber hydraulic fluid becomes in the desired disconnection case thus simply "internally" in passed a pressure accumulator enclosed by the pressure piston. In contrast for the above-mentioned prior art is only one oil supply to Supporting element necessary. At the same time it is stated that the valve train is also in normal mode (connection operation) proves to be relatively stiff. The activation of the closing body (preferably, but not exclusively ball) over preferably as a rod o. The like. Formed Beaufschlagungsmittel proves to be relatively easy and technically easy to control. The urging means may protrude through the head of the plunger and acted upon at its end by an electromagnetic Akttor be, for example, is laterally attached to the cylinder head.

The force of the pressure spring acting on the pressure pad (eg, at least one helical compression spring comprising the urging means) is so strongly dimensioned that a sufficiently rapid emptying of the pressure accumulator in the direction of the high-pressure space occurs during the shutdown case when the cam flank is running, thus leaving the drag lever on the running cam flank. The internal arrangement of the accumulator guarantees that the previously accumulated in the high-pressure chamber hydraulic fluid from reaching quickly dissipated in the pressure chamber. A check valve in the bottom of the housing serves only to suck in leakage. Possibly. the support element can be designed completely hydraulically self-sufficient.

Though should the support element in the valve train preferably as can be switched off. However, it is also conceivable and planned to represent a Hubumschaltung over it. So can the Valve body also after initial Nockenhub be opened so that over here the remaining cam lift is "cut off" to cam tip or the valve lift is cut off immediately at the beginning, passing through early closing of the valve closing body a Resthub to cam tip is generated.

under claim 2 relates to a convenient method of operation a valvetrain according to the main claim. It is shown that in the case of a desired 0-valve lift before or immediately with Cam start of the valve closing body via the Beaufschlagungsmittel is actuated, so that in the high-pressure chamber previously accumulated hydraulic fluid in the pressure chamber of the pressure piston is reduced, at the same time the pressure piston drops to its block size. The gas exchange valve thus remains closed. The charge agent can according to an expedient variant of the invention also on the cam tip stay out open so that the in Pressure chamber accumulated hydraulic fluid through the spring loaded Pressure pad flows back into the high-pressure chamber, whereby thereby the pressure piston with overlying drag lever in the cam direction is relocated.

Conceivable and it is provided, the pressure piston with overlying rocker arm in the case of disconnection, also "to sink", so that the corresponding cam passes virtually empty. As clearly expedient, however, is a permanent return considered the pressure piston in the shutdown case.

Should the gas exchange valve will be switched back on, will be reached of the cam base circle of the valve closing body its pressurizing agent is closed, so that the pressure piston force fit on the accumulated in the high pressure chamber Supported hydraulic column. The gas exchange valve completes a regular with subsequent cam start edge Stroke and the support element acts hydraulically in itself known manner (hydraulic clearance compensation). However, that is it is also intended to provide a valvetrain whose support element does not have a hydraulic play compensation function.

One further subclaim relates to an appropriate Training and arrangement of the valve closing body. So this should be designed as a ball and on a high-pressure chamber side the Absteueröffnung lie. Optionally, this closing body also positioned on the accumulator side or as a plate valve o. Like. Be formed.

One further dependent claim relates to a preferred training the main components of the pressure accumulator in the pressure chamber. So will about one nested shell construction a superb Seal the high-pressure chamber guaranteed. simultaneously can use one between the rod as a pressurizing agent and the pressure pad clamped disc spring ensured be that the valve closing body inactive Actuator its closed position at the Absteueröffnung holds. It can also be provided, the closed position of the valve closing body via the actuator to ensure.

Instead of it is the nested shell construction also conceivable as a pressure pad only a sufficient radial sealed disc, a piston or the like to apply.

Short description of the drawing

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

1 a side view of a valve gear according to the invention with activated support element and

2 the support element from the valve train after 1 , but in its shutdown position.

Detailed description the drawing

1 discloses a valvetrain 1 an internal combustion engine. This has a disconnectable support element 2 which is about his cup-shaped housing 5 in a recording 3 a cylinder head 4 is installed. The housing 5 is telescopic with a two-part plunger here 7 put together, which pressure piston 7 in a hole 6 of the housing 5 runs and on his head 9 a drag lever 11 is pivotally mounted with one end. The latter is from a lift cam 10 acted upon in a conventional manner.

Between a forearm 14 (Sat. 2 ) of the pressure piston 7 and a floor 15 of the housing 5 is a high pressure room 13 with a hydraulic column 12 arranged. This high pressure room 13 can via an axially underlying supply line 25a in the cylinder head 4 being supplied with hydraulic fluid, passing through the floor 15 a hole 24 goes, which high pressure chamber side by a check valve 25 is closed. As can be seen, runs in the high-pressure chamber 13 a compression spring 26 , one end against the forehead 14 of the pressure piston 7 Acts and which other ends on the ground 15 of the housing 5 supported. It is clear to the person skilled in the art that a "normal" hydraulic valve clearance compensation can be represented here in the connection mode.

The two-part pressure piston 7 is centered by a trained as a rod Beaufschlagungsmittel 19 as a component of shut-off devices 17 protrudes, which means of supply over the head 9 protrudes, in a segment-like recess in the drag lever 11 is guided and can be displaced in this end portion, for example, by an electromagnetic actuator, at least in the opening direction.

The charge agent 19 has at its other end designed as a ball valve closing body 18 as another component of the diversion funds 17 , The latter closes after 1 a discharge opening 16 in the pressure piston 7 at its forehead 14 ,

As the figures also disclose, this is the urging means 19 in the area of the head 9 stuck with a sleeve-like body 29 connected. From this is radially on its underside a plate 30 from. The plate 30 is axially a collar 31 opposite, of a thin-walled sheet metal cylinder 32 emanates. The sheet metal cylinder 32 runs on an inside 31b of the pressure piston 7 and is only sealingly attached to the lower half. Between the aforementioned collar 31 and the plate 30 acts a spring element 34 in that it is designed here as a plate spring.

Inside the sheet metal cylinder 32 is a compression spring 22 arranged, with one end on a ring collar 35 supported, the radially inside in a sealing on Beaufschlagungsmittel 19 guided sleeve 36 has continued. With its other end, the compression spring acts 22 against an underside of the aforementioned collar 31 of the sheet metal cylinder 32 , The ring collar 35 in turn, with its underside on a disc-like pressure pad 21 supported, the radially outward into a pipe socket 38 passes on an inner shell 39 of the sheet metal cylinder 32 is guided.

Between a bottom of the pressure pad 21 and the forearm 14 of the pressure piston 7 is a pressure accumulator 20 shown for the hydraulic fluid, which is another component of the Absteuermittel 17 is. The accumulator 20 is in the illustration after 2 filled with hydraulic fluid. It can be seen in 2 in addition, that the pressure piston 7 with his forearm 14 on a ring stop 23 of the housing 5 rests and thus has taken its block position.

To the function: 1 shows the valve train 1 with activated support element 2 , In the high pressure room 13 lies the hydraulic column 12 in front. The pressure piston 7 is on the aforementioned hydraulic column 12 supported. That from the rocker arm 11 acted gas exchange valve performs a full stroke.

If the gas exchange valve is to be switched off, then with the expiration of a Nockengrundkreisphase (s. 2 ) the pressurizing agent 19 actuated axially downwards via the actuator. Thus, the valve closing body gives 18 the discharge opening 16 free and in the high pressure room 13 located hydraulic fluid flows with sinking pressure piston 7 in the overlying accumulator 20 , The compression spring 22 comes with displacement of the pressure pad 21 compressed. Thus, the drag lever completes 11 a downward movement on the side of the support element 2 and the respective gas exchange valve remains closed, wherein the pressure piston 7 on the ring stop 23 sitting.

After the accumulator 20 is filled holds the Aktorbeaufschlagte application means 19 the valve closing body 18 open. With expiring cam edge "relaxes" in the pressure accumulator 20 Accumulated hydraulic fluid through the Absteueröffnung 16 back to the high pressure room 13 , The spring-loaded pressure pad 21 moves towards the forearm 14 , The rocker arm 11 is over the extending pressure piston 7 permanently attached to the lift cam 10 held.

If a full valve lift is required, the valve closing body starts with the starting cam base circle 18 via the agent 19 shifted in its closed position (either via actuation of the actuator or on the force of the spring element 34 with inactive actuator). Thus, this is in the high-pressure chamber 13 accumulated hydraulic fluid held and the pressure piston 7 As a result, it is supported non-positively on the hydraulic fluid column formed therein 12 from. The support element 2 comes after its hydraulic play compensation function, whereby over a leakage gap 28 between pressure piston 7 and housing 5 at Nockenhub each have a minimum amount of hydraulic fluid from the high-pressure chamber 13 is pressed. The gas exchange valve pivots about its pivot point on the head 9 the support element 2 ,

1

valve train

2

supporting

3

admission

4

cylinder head

5

casing

6

drilling

7

pressure piston

8th

edge

9

head

10

lift cams

11

cam follower

12

Hydraulic fluid column

13

High-pressure chamber

14

under head

15

ground

16

spill port

17

Absteuermittel

18

Valve closing body

19

biasing

20

accumulator

21

caul

22

compression spring

23

annular stop

24

drilling

25

check valve

25a

supply

26

compression spring

27

outer sheath

28

leakage gap

29

body

30

Plate

31

collar

31b

inside

32

metal cylinder

33

Not forgive

34

spring element

35

gorget

36

shell

37

outer sheath

38

pipe extension

39

inner sheath

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 4000531 A1 [0002]

Claims (5)

Valve train ( 1 ) an internal combustion engine with a deactivatable support element ( 2 ), which one in a recording ( 3 ) of a cylinder head ( 4 ) built-in pot-like housing ( 5 ) with a bore ( 6 ), in which an axially displaceable pressure piston ( 7 ), on one edge ( 8th ) of the housing ( 5 ) towering head ( 9 ) one of a lift cam ( 10 ) operated drag lever ( 11 ) is mounted, wherein the pressure piston ( 7 ) for representing a full valve lift frictionally on a hydraulic column ( 12 ) supported in a high pressure room ( 13 ) between its lower forehead ( 14 ) and a floor ( 15 ) of the housing ( 5 ), with a Absteueröffnung ( 16 ) from the high-pressure chamber ( 13 ) cooperating Absteuermittel ( 17 ) for selectively relieving the hydraulic column ( 12 ) are provided at Nockenhub, so that there is a 0-valve lift, characterized in that the Absteueröffnung ( 16 ) as a passage in the Unterstirn ( 14 ) of the pressure piston ( 7 ) is present, wherein components of the Absteuermittel ( 17 ) a valve closing body ( 18 ) at the discharge opening ( 16 ), an externally controllable admission means ( 19 ) for the valve closing body ( 18 ) as well as an accumulator ( 20 ) in the pressure piston ( 7 ) are for the diverted hydraulic fluid, which pressure accumulator ( 20 ) immediately above the forehead ( 14 ) of the pressure piston ( 7 ) and by a disc-like pressure pad ( 21 ) is limited in the head direction, of at least one compression spring ( 22 ) is acted upon in pressure storage direction. Method for operating a valve train having the features of claim 1, characterized in that a) for representing the 0 valve lift [switch-off mode] with expiration of a cam base circle edge, the apply means ( 19 ) the valve closing body ( 18 ) opens, so that the Absteueröffnung ( 16 ) is free and the hydraulic fluid from the high-pressure chamber ( 13 ), with simultaneous lowering of the pressure piston ( 7 ) on a ring stop ( 23 ) of the housing ( 5 ), into the accumulator ( 20 ), wherein b) after filling the pressure accumulator ( 20 ) the loading means ( 19 ) the valve closing body ( 18 ) b ₁ ) holds open or b ₂ ) optionally closes, wherein c) with cam tip contact and running cam flank, in the case of b ₂ ) the loading means ( 19 ) additionally the valve closing body ( 18 ) opens again, in both cases according to b) the high pressure space ( 13 ) with the volume of the pressure accumulator thus emptied ( 20 ) is refilled and the pressure piston ( 7 ) extending the drag lever ( 11 ) holds on an outgoing cam edge, and wherein d) d ₁ ) for maintaining the 0-valve lift, the urging means ( 19 ) the valve closing body ( 18 ) holds open in the subsequent cam base circle and wherein d ₂ ) to restore a full valve lift the apply means ( 19 ) the valve closing body ( 18 ) on / in the subsequent cam base circle closes, so that the Absteueröffnung ( 16 ) and the hydraulic column ( 12 ) in the high-pressure space ( 13 ) is held. Valve gear according to claim 1, characterized in that the supporting element ( 2 ) is designed to act hydraulically, wherein in the ground ( 15 ) whose high-pressure space ( 13 ) a hole ( 24 ) is applied, on which high pressure chamber side, a check valve ( 25 ), wherein to the bore ( 24 ) a supply line ( 25a ) from the cylinder head ( 4 ) opens sealingly, with between the bottom ( 15 ) of the housing ( 5 ) and the forearm ( 14 ) of the pressure piston ( 7 ) a compression spring ( 26 ) and between the bore ( 6 ) of the housing ( 5 ) and an outer jacket ( 27 ) of the pressure piston ( 7 ) a leakage gap ( 28 ) for the hydraulic fluid from the high-pressure chamber ( 13 ) is formed. Valve gear according to claim 1, characterized in that the valve closing body ( 18 ) as one on a high pressure chamber side of the discharge port ( 16 ) positioned ball, with a longitudinally through the support element ( 2 ) as well as its head ( 9 ) superior actuator rod as a pressurizing agent ( 19 ) connected to her head ( 9 ) projecting end of an electromagnetic actuator is acted upon or acted upon. Valve gear according to claim 4, characterized in that the pressure piston ( 7 ) from an upper half with the head ( 9 ) and a lower half with the lower forehead ( 14 ), wherein on the head side a sleeve-like body ( 29 ) firmly with the pressurizing agent ( 19 ), which body ( 29 ) on its underside in a radially protruding plate ( 30 ), the latter being a radially inwardly directed collar ( 31 ) of a thin-walled sheet metal cylinder ( 32 ), which, via a separating surface between the two halves of the pressure piston ( 7 ), only on the inside ( 31b ) of the lower half of the pressure piston ( 7 ) is tightly fastened and until just before the forearm ( 14 ), whereby between the plate ( 30 ) and the collar ( 31 ) a spring element ( 34 ) as at least one plate spring is clamped, wherein the compression spring ( 22 ) of the pressure accumulator ( 20 ) as the pressurizing agent ( 19 ) comprehensive compression spring is present and one end against the collar ( 31 ) and at the other end against a ring collar ( 35 ) acting from an underside of a thin-walled sleeve ( 36 ) protrudes radially on the outer shell ( 37 ) of the loading means ( 19 ) is sealingly, but axially movable, wherein a bottom of the annular collar ( 35 ) of the sleeve ( 36 ) on the disc-like pressure pad ( 21 ), which pressure pad ( 21 ) radially outward into a pipe socket ( 38 ) passing on an inner shell ( 39 ) of Blechzylin ders ( 32 ) is guided.