DE102012212048A1 - Variable stroke valve drive for cylinder head of internal combustion engine, has pivot lever, which has cam track on side facing cam, where intermediate element is arranged between cam and cam track and is displaced along cam track - Google Patents

Abstract

The variable stroke valve drive (1) has a pivot lever (2), which is pivotally supported on one side and is supported on an intermediate element (8) on a gas exchange valve (9) in a backlash-free manner. The pivot lever has a cam track (15) on the side facing the cam (10). An intermediate element (16) is arranged between the cam and the cam track and is displaced along the cam track. The intermediate element is a roller, whose position is changed by a gear (17). An independent claim is included for an internal combustion engine with a pressure gas reservoir.

Description

The invention relates to a variable-stroke valve drive for a cylinder head of an internal combustion engine with the features of the preamble of patent claim 1 and an internal combustion engine with a variable-stroke valve drive with the features of claim 10.

For technical environment, for example, the German patent DE 101 29 976 B4 pointed. For this purpose, a self-igniting reciprocating internal combustion engine with at least one cylinder and at least one turbocharger is known. The reciprocating internal combustion engine are assigned means that in addition to the charge air of the turbocharger compressed air in the cylinder can be introduced to accelerate the load connection. The self-igniting reciprocating internal combustion engine is characterized in that for introducing the compressed air in each cylinder each a pressure inlet valve, a so-called. Charging valve is provided, which is by means of a control device in dependence on the piston position in the respective cylinder and is zuusteuerbar, each pressure inlet valve in is arranged in each case a line of a starting pressure air reservoir to the respective cylinder and is provided in each case in the line between the starting pressure air reservoir and the pressure inlet valve operable by means of the control device shut-off.

A disadvantage of the known prior art is that the pressure inlet valve is a completely separate functional unit with completely separate operation, which increases the structural complexity and the production costs.

Further, the technical environment, for example, the international patent application WO 2009/036992 A1 pointed. Reciprocating internal combustion engines are also known from these publications, which can be operated at least partially with the aid of an additional charging valve with compressed air.

Next is in the Motortechnische Zeitschrift MTZ, January 2010/71. Volume, pages 52 to 58, the current state of pneumatic hybridization in the article "The downsizing boost concept based on the pneumatic hybridization of gasoline engines" described.

These publications have in common that the intake and exhaust valves for the gas exchange camshaft controlled, d. H. Conventionally operated, while the charging valves for the compressed air are each fully or partially variable controllable. This disadvantageously makes each a separate fully or partially variable drive, such as an electromagnetic valve train, necessary for the charging valve, which is expensive to build and high production costs.

Next is from the German patent application DE 101 23 186 A1 , from which the present invention proceeds, a variable-stroke valve drive for a cylinder head of an internal combustion engine known, with a pivot lever, on the one hand with a roller element with a swinging fulcrum on a link path of a link and on the other hand with a control track on an intermediate element, a drag lever to a gas exchange valve is supported without play, the pivot lever for stroke adjustment between the support points on the one hand controlled by a cam of a camshaft against a force of a spring pivotally and on the other hand controlled the oscillating pivot point of an adjusting device for height adjustment parallel to the slide track, known. For phase shift, ie for the relative angular displacement of the camshaft to the crankshaft separate camshaft adjusters, so-called. VANOS units are provided.

A disadvantage of this known, variable stroke valve drive, however, is the limited adjustment angle of the camshaft to the position of the crankshaft, so that the control of a charging valve for the compressed air only in limited angular ranges and thus only to a limited extent possible.

Object of the present invention is to show a valve train for a cylinder head of an internal combustion engine with which a generic charging valve for compressed air from a pressure tank in full, d. H. can be operated over a wide Winkelverstellbereich and an internal combustion engine with a variable-stroke valve train.

This object is achieved with a valve train with the features of the characterizing part of patent claim 1 and with an internal combustion engine with a variable-stroke valve drive with the features of claim 10.

Advantageous developments of the invention are described in the subclaims.

The present invention describes how at least the so-called Boost mode for an internal combustion engine, the conventional combustion and the four-stroke pump mode, can be realized inexpensively and easily. Another variant of the invention relates to the fact that one can also represent a compressed-air-assisted start of the internal combustion engine, which is then a modified direct start or else a purely pneumatic start of the internal combustion engine, as well as pneumatic driving in certain operating ranges. All these additional operating modes of the internal combustion engine could in principle be met with a fully variable valve, as known from the prior art, but this would be much too complicated and too expensive. The aim of the invention is to use a camshaft-based system for the charging valve for the compressed air from a pressure tank, which offers maximum functionality but causes a minimum of additional costs. The system design is governed by the prioritized requirements for a reciprocating internal combustion engine operable in four-stroke operation listed below in Table 1 (see also US Pat 3 ): Piston movement: up Down up Down Pneumatic modes 4-stroke pneumatic motor mode LV AV EV 4-stroke pneumatic pump mode LV AV EV Fired modes Conventional combustion ignition AV EV Boost mode LV / Ignition AV EV Piston position: UT OT UT OT UT Table 1

• • Das Ladeventil für die Druckluft aus dem Drucktank muss deaktivierbar sein (konventioneller Brennkraftmaschinen-Modus), der Ventiltrieb soll dabei einen möglichst geringen Energieverbrauch aufweisen;
• • Das Ladeventil für die Druckluft aus dem Drucktank soll ein Boost-Profil ermöglichen, das Aktivieren und Deaktivieren soll sehr schnell sein;
• • Das Boost-Profil soll reduziert werden können (geringerer Hub des Ladeventils und späteres Öffnen, Schließen etwa zum gleichen Zeitpunkt wie beim normalen Boost-Modus);
• • Das Ladeventil für die Druckluft aus dem Drucktank soll ein Pump-Profil ermöglichen (Schließen des Ladeventils kurz nach dem Zünd-OT);
• • Das Pump-Profil soll reduziert werden können, das Ladeventil schließt weiterhin kurz nach dem Zünd-OT, öffnet jedoch später und hat einen geringeren Hub. Dies dient dazu, auch bei höherem Druck im Drucktank noch effizient pumpen zu können;
• • Das Ladeventil für die Druckluft aus dem Drucktank soll ein Start-Profil ermöglichen derart, dass dieses bei Stillstand der Brennkraftmaschine aktiviert werden kann. Idealerweise kann bei dem Aktivierungsvorgang oder dem Deaktivierungsvorgang eine Kollision des Ladeventils mit dem Kolben geometrisch ausgeschlossen werden;
• • Das Start-Profil soll verändert werden können, so dass das Ladeventil früher oder später schließen kann.
• • Der Hub des Ladeventils soll bei der ersten Zylinderfüllung zeitlich variiert werden können.

This results in the following requirements for the valve train:

• • The charge valve for the compressed air from the pressure tank must be deactivatable (conventional engine mode), the valve train should have the lowest possible energy consumption;
• • The charge valve for the compressed air from the pressure tank should allow a boost profile, the activation and deactivation should be very fast;
• • The boost profile should be able to be reduced (lower stroke of the charging valve and later opening, closing at approximately the same time as in normal boost mode);
• • The charge valve for the compressed air from the pressure tank should enable a pump profile (closing of the charge valve shortly after the ignition TDC);
• • The pump profile should be able to be reduced, the charging valve continues to close shortly after the ignition TDC, but opens later and has a lower stroke. This serves to be able to pump efficiently even at higher pressure in the pressure tank;
• • The charging valve for the compressed air from the pressure tank should allow a start-up profile such that it can be activated when the internal combustion engine is at a standstill. Ideally, in the activation process or the deactivation process, a collision of the charging valve with the piston can be geometrically excluded;
• • The start profile should be able to be changed so that the loading valve can close sooner or later.
• • The stroke of the charging valve should be able to be varied in time with the first cylinder filling.

Decisive for the functionality of the valve train are the contour design of the cam of the camshaft, the adjustment of the intermediate lever in the interface area to the cam and its geometric shape and the control track and the oscillating storage in the backdrop. With the configuration of these parameters, the valve train, in particular as a loading valve drive for the compressed air from the pressure tank in stroke and phase position in a very wide range changeable represented.

The bearing point of the roller guide in the region of the slide and the eccentric can be represented in a further embodiment with a simple joint displacement also easier. Backlash and eccentric shaft are not necessarily required for the basic functionality of the valve train, but increase the variability of the valve train.

In subsequent 4 to 8th the settings of the valve train according to the invention for the different operating modes of the internal combustion engine are again shown in detail. However, the exact geometry, for example of the cam track or the cam profile, must, for each valve train, can be determined separately according to the required functionalities and can not be specified on a flat-rate basis.

Summary of the advantages of the valve drive according to the invention:
The elimination of the two camshaft adjusting units (VANOS units) reduces the power requirement to the lubricant pump of the internal combustion engine. The lubricant pump can be adapted to the lower power requirement and thereby opens up new potential for reducing the manufacturing costs. Regardless of the dimensioning of the lubricant pump increases due to their lower power consumption, the efficiency of the internal combustion engine. This can be used advantageously to increase the performance of the internal combustion engine, as well as to reduce the exhaust emissions.

Furthermore, there is a cost savings through the elimination of, for example, an additional camshaft or an additional electromagnetic valve drive. To achieve the full input and Auslaßvariabilität the valve train usually two camshafts are installed (DOHC: double overhead cam). In the operating principle according to the invention, however, the phase adjustment can be implemented not only camshaft but valve-specific. The Gaswechselein- and Gaswechselauslassventile be adjusted independently of each other with a single camshaft in the phase.

The cylinder head width can be significantly reduced by replacing the camshaft adjusting units (VANOS units) and eliminating, for example, a camshaft. This not only increases the power density of the internal combustion engine but also saves weight and material costs.

The phase angle of the intake and exhaust valves can be applied functionally in the presence of an internal combustion engine start-stop function. So far, the phase adjustment is bound to the lubricant pressure and thus the phase position can not be varied at standstill of the internal combustion engine. An electrical adjustment of the transmission and thus the phase angle allow a functionally correct Phasenabstelllage and phase adjustment of the valve train at standstill of the internal combustion engine.

In the following the invention is explained in more detail with reference to eight figures.

1 schematically shows a generically operated internal combustion engine.

2 schematically shows a valve train according to the invention.

3 shows in a diagram a valve lift for different operating modes.

4 schematically shows a valve train according to the invention in a zero-stroke mode.

5 schematically shows the valve gear according to the invention in a boost mode.

6 schematically shows the valve gear according to the invention in a pump mode with a large Ladeventilhub, early.

7 schematically shows the valve gear according to the invention in a pump mode with a small Ladeventilhub, late.

8th shows the valve train according to the invention in a start mode.

• • Viertakt-Pneumatik-Motor-Modus
• • Viertakt-Pneumatik-Pump-Modus, sowie folgende gefeuerte Modi:
• • Konventionelle Verbrennung,
• • Boost-Modus.

1 schematically shows a generic reciprocating internal combustion engine according to the prior art. An unnumbered piston is guided in a liftable manner to an unnumbered cylinder. For a charge change, two exhaust valves (AV) and two intake valves (EV) are provided. In addition to a currently known four-valve internal combustion engine, a charging valve (LV) is provided with which compressed gas can be fed into the cylinder from a pressure tank. With this known from the prior art reciprocating internal combustion engine with pressure tank, can now perform the listed in Table 1 above operating modes:
Pneumatic modes:

• • Four-stroke pneumatic engine mode
• • Four-stroke pneumatic pump mode, as well as the following fired modes:
• • conventional combustion,
• • Boost mode.

The operation of the inlet and outlet valves (EV, AV) and of the charging valve (LV) is shown for each operating mode in one line in each case via the piston position. UT is the bottom dead center and OT is the top dead center of the piston. Between the first UT and the first TDC firing takes place for the fired modes, the first TDC after the ignition shown schematically is the so-called ignition TDC of the piston.

Based on this known prior art, it is an object of the invention to provide a valve train for a cylinder head of an internal combustion engine, with a generic charging valve for compressed air is fully operable.

2 schematically shows a preferred embodiment of a variable stroke valve train according to the invention 1 , The variable stroke valve train 1 is provided for a cylinder head, not shown, of an internal combustion engine, in particular an internal combustion engine with a pneumatic operating mode. The variable stroke valve train 1 has a pivot lever 2 on, on the one hand with a roller element 3 with a swinging fulcrum 4 on a slide track 5 a backdrop 6 and on the other hand with a control track 7 on an intermediate element 8th , a drag lever, to a gas exchange valve 9 crashed without clearance. A valve seat ring is with 14 designated. For actuating the gas exchange valve 9 is the pivot lever 2 between the support points on the one hand by a cam 10 a camshaft 11 against a force of a spring 12 controlled pivoting and on the other hand, the swing pivot point 4 from an adjusting device 13 for lifting height adjustment parallel to the slide track 5 controlled displaceable. In a further, mechanically simpler embodiment, the scenery can also 5 as well as the roller element 3 omitted and the pivot lever 2 be pivotally pivotable by a simple actuator, or by a fixed joint.

According to the invention, the pivot lever 2 on the cam 10 facing side a curved track 15 on, being between the cam 10 and the curved path 15 a displaceable intermediate element 16 , In the present embodiment, a roller is arranged. The role 16 is in the present embodiment, for example, by a transmission 17 along the curved path 15 displaceable. The inventive design, it is possible, in addition to the Hubhöhenverstellung by the adjustment 13 , For example, an eccentric shaft, not only the lifting height of the gas exchange valve 9 to adjust, but also the phase position, ie the position of the opening and closing time of the gas exchange valve with respect to a phase angle of a crankshaft.

3 shows in a diagram as the phase position and the lifting height of a gas exchange valve 9 , such as B. a charging valve with the valve gear according to the invention 1 are changeable. On a Y-axis a Gaswechselventilhub from 0 to 10 in [mm] is plotted. An X-axis shows a crank angle from -180 ° to + 360 ° in [° CA]. At +180 [° CA] on the X-axis is the ignition TDC. In addition, but again to significantly higher manufacturing costs and greater complexity, the valve gear according to the invention 1 additionally, as known from the prior art, combined with camshaft adjusters, so-called VANOS units.

A spotted valve lift curve corresponds to a lift curve of a gas exchange intake valve.

A valve lift curve represented by triangles corresponds to a lift curve of a charge valve in boost mode.

A valve lift curve represented by squares corresponds to a lift curve of a charge valve in pump mode.

A valve lift curve represented by a single line corresponds to a lift curve of a charge valve in the start mode.

A valve lift curve represented by crosses corresponds to a lift curve of a gas exchange outlet valve.

In 3 is the wide adjustment range of the lifting height and the phase angle of a gas exchange valve, in particular a charging valve, recognizable.

The following 4 to 8th show the sake of clarity not quantified valve train according to the invention 1 out 2 for different operating modes of a gas exchange valve 9 , in particular a charging valve:

4 schematically shows the valve gear according to the invention 1 in a zero-stroke mode.

5 schematically shows the valve gear according to the invention 1 in a boost mode.

6 schematically shows the valve gear according to the invention 1 in a pump mode with large loader stroke, early.

7 schematically shows the valve gear according to the invention 1 in a pump mode with a small loader stroke, late.

8th shows the valve gear according to the invention 1 in a startup mode.

From the 4 to 8th are the different arrangements of the intermediate element 16 , in the present embodiment a role, between the cam 10 and the curved path 15 recognizable for the different modes. A displacement direction of the intermediate element 12 is on the gearbox 17 schematically represented by a double arrow. Due to the change in position of the intermediate element 16 with respect to the cam 10 is the action of the cam or the cam profile on the pivot lever 2 shifted in time, whereby the phase angle of the valve lift is shifted with respect to a position crankshaft and the different operating modes are generated.

LIST OF REFERENCE NUMBERS

1

Hubvariabler valve drive

2

pivoting lever

3

roller element

4

Swing fulcrum

5

link path

6

scenery

7

control track

8th

intermediate element

9

Gas exchange valve

10

cam

11

camshaft

12

feather

13

adjustment

14

valve seat

15

cam track

16

intermediate element

17

transmission

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 10129976 B4 [0002]
• WO 2009/036992 A1 [0004]
• DE 10123186 A1 [0007]

Cited non-patent literature

• Motortechnische Zeitschrift MTZ, January 2010/71. Volume, pages 52 to 58, the current state of pneumatic hybridization in the article "The downsizing boost concept based on the pneumatic hybridization of gasoline engines" [0005]

Claims (11)

Hubvariabler valve drive ( 1 ) for a cylinder head of an internal combustion engine, with a pivoting lever ( 2 ), which is pivotally supported on the one hand and on the other hand with a control track ( 7 ) on an intermediate element ( 8th ) to a gas exchange valve ( 9 ) is supported without play, wherein the pivot lever ( 2 ) for stroke adjustment between the support points on the one hand by a cam ( 10 ) a camshaft ( 11 ) against a force of a spring ( 12 ) controlled pivotally and on the other hand by an adjusting device ( 13 ) is controlled for lifting height adjustment, characterized in that the pivot lever ( 2 ) on the cam ( 10 ) facing side a curved path ( 15 ) and between the cam ( 10 ) and the curved path ( 15 ) along the curved path ( 15 ) displaceable intermediate element ( 16 ) is arranged. Hubvariabler valve drive according to claim 1, characterized in that the intermediate element ( 16 ) one of a transmission ( 17 ) is positionally variable role. Hubvariabler valve drive according to claim 1 or 2, characterized in that the curved path ( 15 ) has a curve section (a), wherein the gas exchange valve ( 9 ) is operable in a zero-stroke mode. Hubvariabler valve drive according to one of the claims 1 to 3, characterized in that the curved path ( 15 ) has a curve portion (b), wherein the gas exchange valve ( 9 ) is operable in a boost mode. Hubvariabler valve drive according to one of the claims 1 to 4, characterized in that the curved path ( 15 ) has a curve section (c), wherein the gas exchange valve ( 9 ) is operable in a pump mode with a large valve lift. Hubvariabler valve drive according to one of the claims 1 to 5, characterized in that the curved path ( 15 ) has a curve portion (d), wherein the gas exchange valve ( 9 ) is operable in a pumping mode with a small valve lift. Hubvariabler valve drive according to one of the claims 1 to 6, characterized in that the curved path ( 15 ) has a curve section (e), wherein the gas exchange valve ( 9 ) is operable in a startup mode. Hubvariabler valve drive according to one of the claims 1 to 7, characterized in that the pivot lever on the one hand with a roller element ( 3 ) with a swinging fulcrum ( 4 ) on a slide track ( 5 ) a backdrop ( 6 ) is supported and the oscillating pivot point ( 4 ) parallel to the slide track ( 5 ) is controlled displaced. Hubvariabler valve drive according to one of the claims 1 to 8, characterized in that the gas exchange valve ( 9 ) is a gas exchange inlet valve or a gas exchange outlet valve or a charging valve. Internal combustion engine with a variable-stroke valve drive according to one of the claims 1 to 9, characterized in that the internal combustion engine has a compressed gas storage and the stroke-variable valve train ( 1 ) for actuating a gas exchange valve ( 9 ) is provided for introducing and / or applying compressed gas in and / or from a combustion chamber of the internal combustion engine. Internal combustion engine with a variable-stroke valve drive according to one of the claims 1 to 9, characterized in that the stroke-variable valve train ( 1 ) is provided inlet and / or outlet side.

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