EP1490584A2 - Device for the variable control of gas exchange valves in an internal combustion engine - Google Patents

Device for the variable control of gas exchange valves in an internal combustion engine

Info

Publication number
EP1490584A2
EP1490584A2 EP02747200A EP02747200A EP1490584A2 EP 1490584 A2 EP1490584 A2 EP 1490584A2 EP 02747200 A EP02747200 A EP 02747200A EP 02747200 A EP02747200 A EP 02747200A EP 1490584 A2 EP1490584 A2 EP 1490584A2
Authority
EP
European Patent Office
Prior art keywords
cam
piston
lubricating oil
internal combustion
combustion engine
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP02747200A
Other languages
German (de)
French (fr)
Other versions
EP1490584B1 (en
Inventor
Thomas Sebastian
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Robert Bosch GmbH
Original Assignee
Robert Bosch GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Robert Bosch GmbH filed Critical Robert Bosch GmbH
Publication of EP1490584A2 publication Critical patent/EP1490584A2/en
Application granted granted Critical
Publication of EP1490584B1 publication Critical patent/EP1490584B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
    • F01L1/02—Valve drive
    • F01L1/04—Valve drive by means of cams, camshafts, cam discs, eccentrics or the like
    • F01L1/08—Shape of cams
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L13/00—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations
    • F01L13/0015—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations for optimising engine performances by modifying valve lift according to various working parameters, e.g. rotational speed, load, torque
    • F01L13/0057—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations for optimising engine performances by modifying valve lift according to various working parameters, e.g. rotational speed, load, torque by splittable or deformable cams

Definitions

  • the invention is based on a device for variable control of the gas exchange valves of an internal combustion engine, of which at least one gas exchange valve is controlled by a cam of a camshaft, which has a cam contour with a cam base circle section and a cam summit section, according to the preamble of claim 1.
  • the prior art discloses various approaches for realizing a variable gas exchange valve control.
  • variable Ventil thoroughlyungsvoruzeeh in which the valve lifts in stages changed.
  • a valve control device is described, for example, in EP 0 515 520 B1, which has a tappet made of two concentric cup elements, the inner end of which rests against the valve stem of the gas exchange valve The tappet interacts with the cam of a camshaft, which has three partial cams with different cam tracks.
  • the two outer cam tracks have the same stroke and act on the outer cup element.
  • the middle part cam has a different stroke profile with a lower stroke height and acts on the inner cup element.
  • the two concentric cup elements can be coupled to one another by hydraulic application of a coupling element or can be moved independently of one another in a second switching position of this coupling element.
  • the two cup elements are connected to one another so that they follow the stroke course of the partial cams with a larger stroke. This movement is transmitted to the valve stem via the coupling element and the inner cup element.
  • the two cup elements can be moved independently of one another. In this switching position, the valve stem interacts with the middle partial cam with a smaller stroke.
  • the outer cup element follows the lifting movement of the outer partial cams, but there is no connection to the inner cup element or to the valve stem.
  • Gas exchange valve can be actuated independently of the other gas exchange valves. As a result, infinitely variable valve lifts and variable control times can be implemented for each gas exchange valve. In this case, two control valves are used for actuating the differential piston for each gas exchange valve, so that currently common
  • valve motors per cylinder eight such control valves are necessary, which has a negative impact on the space required and the manufacturing costs due to the large number of components.
  • conventional internal combustion engines can only be converted to the new technology at relatively high cost.
  • the emergency running properties represent a particular problem, since a failure of the hydraulic system usually also causes a total failure of the valve control.
  • Pistons are moved out of or into the assigned cam.
  • the cam contour of the cams is thus infinitely variable, so that any stroke curves of the gas exchange valves can be achieved.
  • the stroke height, valve opening time and speed can be variably adjusted.
  • the retractable and extendable pistons are slidably mounted in the otherwise unchanged cams and no changes are necessary on the tappets anyway, conventional valve drives with minor modifications can be used be converted.
  • no additional space is required for the pistons, which results in a very small space requirement. Since the camshaft remains completely intact as a control element, the functionality of the valve control is guaranteed even if the pressure medium supply fails. Overall, the invention makes it possible to implement an extremely cost-effective valve train compared to the prior art.
  • the end of the piston on the side of the cam summit is spherical.
  • the cam peak can then roll on the associated tappet with little friction in any angular position.
  • the piston is held in a defined position if the pressure medium supply fails.
  • the internal combustion engine can continue to be operated with predetermined control times and valve strokes without damaging operating states being able to occur.
  • a ball that can be rolled on a rolling surface of a tappet that interacts with the relevant cam is rotatably mounted on the end of the piston on the cam summit.
  • a spherical bearing surface corresponding to the radius of the ball, is preferably formed at the end of the piston on the cam summit, the edge of which is flanged radially inward to grip the ball.
  • the bearing surface of the ball is advantageously by the already existing Lubricating oil system of the internal combustion engine is supplied with lubricating oil, so that a hydrodynamic lubricating film which is more favorable in terms of friction and wear can form between the ball and the bearing surface.
  • the piston is actuated by lubricating oil of the internal combustion engine. Because with one
  • the piston is preferably guided linearly through the cam. Its the valve lift and the timing of the associated
  • Radial position influencing the gas exchange valve is preferably adjustable depending on the balance of forces between the pistons, radially inward urging spring forces and the radially outwardly urging pressure forces of the lubricating oil.
  • a continuous stepped bore extending through the center of the cam is provided, with a helical spring being supported on the one hand on a step of the stepped bore on the cam gypsum side and on the other hand on an annular surface of the piston pointing away from a bottom effective piston surface.
  • a pressure chamber for the lubricating oil is formed between the active surface of the piston and an end piece inserted into the end of the stepped bore pointing away from the cam tip section, said pressure chamber being connected to a lubricating oil channel coaxial with the camshaft axis.
  • the piston has a channel connecting the bearing surface with the pressure chamber.
  • a bush inserted into the stepped bore is supported on the closure piece and serves as a radially inner stop for the piston when the internal combustion engine is at rest or in the event of a failure of the pressure medium supply.
  • the coil spring then pushes the piston against the bushing, so that the piston is held in a defined position.
  • the pressure build-up or the pressure decrease in the pressure chambers of the cams provided with retractable and extendable pistons is preferably carried out by a valve arrangement, each of which includes a switching valve upstream of the lubricating oil channel of the camshaft and a switching valve downstream of the lubricating oil channel of the camshaft.
  • FIG. 1 An embodiment of the invention is shown in the drawing and explained in more detail in the following description.
  • the single figure shows a cross-sectional view of a cam as part of a preferred embodiment of a device according to the invention for variable control of the gas exchange valves of an internal combustion engine.
  • cams 1 of a device for variable control of the gas exchange valves of an internal combustion engine are one in the figure.
  • Camshaft 2 shown in cross section.
  • the cam contour of such a cam 1 contains one
  • the cam summit section 6 is in contact with a rolling surface 8 of a cup tappet 10, which transmits the rotary movement of the cam 1 as a linear stroke movement to the associated gas exchange valve.
  • a variable-pressure piston guided by the cam 1 and radially steplessly retractable and extendable piston 12 is provided for variable adjustment of the cam contour, which forms at least part of the cam summit section 6 at the end.
  • the radial position of the piston 12 can be adjusted as a function of the balance of forces between the pistons 12 in the case of spring forces urging radially inwards and the pressure forces of a pressure medium urging it radially outwards.
  • the lubricating oil of the internal combustion engine is preferably used as the pressure medium.
  • the piston 12 is guided in a continuous stepped bore 16 of the cam 1 running in the direction of the cam center axis 14, a helical spring 18 being located on the one hand on a cam-tip step 20 of the stepped bore 16 and on the other hand on an annular surface 24 pointing away from a piston effective surface 22 on the bottom of the piston 12, on which the piston 12 expands in diameter in steps.
  • the piston 12 therefore consists of a smaller-diameter head section 28, which projects into or through a section 26 of the stepped bore 16 on the cam tip side, and a bottom section 30 which contains the active surface 22.
  • the coil spring 18 is then in an annular space 32 between the outer circumference of the Head portion 28 of the piston 12 and the inner periphery of the larger diameter portion 34 of the stepped bore 16 held.
  • a pressure chamber 38 is formed, which is connected to a lubricating oil channel 42 coaxial with the camshaft axis 40, which connects the Pressure chambers 38 of the cams 1 of the camshaft 2 connects to one another.
  • the closure piece 36 can be held in the stepped bore 16, for example by screwing.
  • a bushing 44 which is supported on the cam summit on the closure piece 36 and is open at the ends, serves as a radially inner stop for the piston 12 when the pressure in the pressure chamber 38 drops, for example when the pressure medium supply fails or when the internal combustion engine stops. In such cases, the piston 12 is pushed against the bush 44 by the action of the helical spring 18 and is thus held in a defined position. To keep the flow of lubricating oil into the
  • bushing 44 In order not to impede pressure chamber 38 or the further flow of lubricating oil to the pressure chamber of the next cam, bushing 44 has openings in its peripheral wall aligned with the openings of lubricating oil channel 42. Alternatively, the sleeve 44 could form an integral component with the closure piece 38. Radially outward, the stroke of movement of the piston 12 is limited by the compressed winding package of the helical spring 18, which is supported against the step 20.
  • the end 46 of the piston 12 on the cam tip side is spherical.
  • a ball 48 that can be rolled on the rolling surface 8 of the cup tappet 12 is at the end 46 of the piston 12 on the cam summit side rotatably mounted.
  • a spherical bearing surface 50 corresponding to the radius of the ball 48 is formed on the end 46 of the piston 12 on the cam summit, the edge 52 of which is flanged radially inwards for gripping the ball 48.
  • the bearing surface 50 of the ball 48 is supplied with lubricating oil by the lubricating oil system of the internal combustion engine, for which purpose the piston 12 has a central channel connecting the bearing surface 50 of the ball 48 with the pressure chamber 38 . 54 has.
  • the pressure build-up or the pressure decrease in the pressure chambers 38 of the cams 1 provided with retractable and extendable pistons 12 takes place by a valve arrangement, not shown for reasons of scale, which includes, for example, one switching valve upstream of the lubricating oil channel 42 of the camshaft 2 and one switching valve downstream of the lubricating oil channel 42 ,
  • a lubricating oil pressure for generating compressive forces on the active surfaces 22 of the pistons 12 is set by the engine control in the lubricating oil channel 42 or in the pressure chambers 38 connected to the latter, which in equilibrium with the spring forces of the coil springs 18 a certain common radial position of the Cause piston 12 in relation to the assigned cams 1.
  • the sicr ⁇ eins . tellende radial position of the piston 12 corresponds to the ben 'Ventilhü-- desired, valve opening times and the valve opening speeds.
  • one-way spring means 18 are used to adjust the radial position of the pistons 12.
  • spring means could also act on the pistons 12 on both sides and the pressure medium additionally on one side.
  • pistons could be designed as differential pistons which are pressurized on both sides.
  • spring means can also be provided, which act as a support in one or both directions of movement of the pistons and, if the pressure medium supply fails, urge them into a defined position and hold them there.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Valve Device For Special Equipments (AREA)
  • Valve-Gear Or Valve Arrangements (AREA)

Abstract

The invention relates to a device for the variable control of gas exchange valves in an internal combustion engine. At least one of the gas exchange valves is controlled by the cam (1) of a cam shaft (2), provided with a cam contour with a circular base section (4) and a cam summit section (6). According to the invention, a radially retractable and extractable piston (12) is provided which can be guided through the cam (1) and which can be pressure actuated for variable adjustment of the cam contour, said piston forming, on the end side thereof, at least one part of the cam summit section (6).

Description

Vorrichtung zur variablen Steuerung der Gaswechselventϊle einerDevice for variable control of the gas exchange valves
BrennkraftmaschineInternal combustion engine
Beschreibungdescription
Stand der TechnikState of the art
Die Erfindung geht aus von einer Vorrichtung zur variablen Steuerung der Gaswechselventile einer Brennkraftmaschine, von wel- chen wenigstens ein Gaswechselventil von einem Nocken einer Nockenwelle angesteuert ist, der eine Nockenkontur mit einem Nockengrundkreisabschnitt und einem Nockengipfelabschnitt aufweist, gemäß dem Oberbegriff des Anspruchs 1 . Der Stand der Technik offenbart verschiedene Ansätze zur Realisierung einer variablen Gaswechsel- Ventilsteuerung.The invention is based on a device for variable control of the gas exchange valves of an internal combustion engine, of which at least one gas exchange valve is controlled by a cam of a camshaft, which has a cam contour with a cam base circle section and a cam summit section, according to the preamble of claim 1. The prior art discloses various approaches for realizing a variable gas exchange valve control.
Einerseits sind teil variable Ventilsteuerungsvorrichtungeh ' bekannt, bei welchen die Ventilhübe in Stufen veränderbar sind. Eine solche Ventilsteuerungsvorrichtung ist beispielsweise in der EP 0 515 520 B1 beschrieben, welche einen Stößel aus zwei konzen- trischen Tassenelementen aufweist, von denen das innere mit -seiner einen Stirnseite am Ventilschaft des Gaswechselventils anl iegt Der Stößel wirkt mit dem Nocken einer Nockenwelle zusammen, der drei Teilnocken mit unterschiedlichen Nockenbahnen aufweist. Die beiden äußeren Nockenbahnen haben den gleichen Hubverlauf und wirken auf das äußere Tassenelement. Der mittlere Teilnocken hat einen davon abweichenden Hubverlauf mit geringerer Hubhöhe und wirkt auf das innere Tassenelement. Die beiden konzentrischen Tassenelemente können durch hydraulische Beaufschlagung eines Koppelelements miteinander gekoppelt oder in einer zweiten Schaltstellung dieses Koppelelements unabhängig voneinander bewegt werden. In der gekoppel- ten Stellung sind die beiden Tassenelemente miteinander verbunden, so dass diese dem Hubverlauf der Teilnocken mit größerem Hub folgen. Über das Koppelelement und das innere Tassenelement wird diese Bewegung auf den Ventilschaft übertragen. In der zweiten Schaltstellung des Koppelelements sind die beiden Tassenelemente unab- hängig voneinander beweglich. Der Ventilschaft wirkt in dieser Schaltstellung mit dem mittleren Teilnocken- mit geringerem Hub zusammen. Das äußere Tassenelement folgt der Hubbewegung der äußeren Teilnocken, wobei jedoch keine Verbindung zum inneren Tassenelement bzw. zum Ventilschaft besteht. Ein Vorteil solcher Ventiltriebe liegt dar- in, dass auch bei Ausfall des Schaltmechanismus weiterhin eine ordnungsgemäße Ventilsteuerung durch die Nockenwelle gewährleistet ist, außerdem lassen sich konventionelle Brennkraftmaschinen ohne allzu großen Aufwand umrüsten. Nachteilig ist jedoch, dass die Ventil- _'hübe. und Steuerzeiten lediglich in einer begrenzten Anzahl von Stufen veränderbar sind, wobei der stufenweise Übergang Probleme hinsichtlich Geräusch und Stetigkeit verursacht. Außerdem solche Systeme .mechanisch aufwendig. Zum andern sind aus dem Stand der Technik, beispielsweise aus der DE 39 35 21 8 A1 , vollvariable Ventilsteuerungsvorrichtungen als etektrohydrauiische Ventiltriebe ohne Nockenwelle bekannt, bei welchen der Ventilschaft über eine Kolbenstange mit einem hydraulisch betätigbaren Differentialkolben gekoppelt ist, über den das einzelneOn one hand, some variable Ventilsteuerungsvorrichtungeh 'known, in which the valve lifts in stages changed. Such a valve control device is described, for example, in EP 0 515 520 B1, which has a tappet made of two concentric cup elements, the inner end of which rests against the valve stem of the gas exchange valve The tappet interacts with the cam of a camshaft, which has three partial cams with different cam tracks. The two outer cam tracks have the same stroke and act on the outer cup element. The middle part cam has a different stroke profile with a lower stroke height and acts on the inner cup element. The two concentric cup elements can be coupled to one another by hydraulic application of a coupling element or can be moved independently of one another in a second switching position of this coupling element. In the coupled position, the two cup elements are connected to one another so that they follow the stroke course of the partial cams with a larger stroke. This movement is transmitted to the valve stem via the coupling element and the inner cup element. In the second switching position of the coupling element, the two cup elements can be moved independently of one another. In this switching position, the valve stem interacts with the middle partial cam with a smaller stroke. The outer cup element follows the lifting movement of the outer partial cams, but there is no connection to the inner cup element or to the valve stem. An advantage of such valve drives is that even if the switching mechanism fails, proper valve control is still ensured by the camshaft, and conventional internal combustion engines can also be converted without too much effort. However, a disadvantage is that the valve _ 'strokes. and control times can only be changed in a limited number of stages, the gradual transition causing problems in terms of noise and continuity. In addition, such systems are mechanically complex. On the other hand, fully variable valve control devices are known from the prior art, for example from DE 39 35 21 8 A1, as etektrohydrauiische valve trains without camshaft, in which the valve stem is coupled via a piston rod to a hydraulically actuated differential piston, via which the individual
Gaswechselventil unabhängig von den übrigen Gaswechselventilen direkt betätigbar ist. Infolgedessen sind für jedes Gaswechselventil stufenlos variable Ventilhübe und variable Steuerzeiten realisierbar. Hierbei werden für jedes Gaswechseiventii zwei Steuerventile zur Betäti- gung des Differentialkolbens eingesetzt, so dass bei derzeit gängigenGas exchange valve can be actuated independently of the other gas exchange valves. As a result, infinitely variable valve lifts and variable control times can be implemented for each gas exchange valve. In this case, two control valves are used for actuating the differential piston for each gas exchange valve, so that currently common
Vier-Ventilmotoren je Zylinder acht solcher Steuerventile notwendig sind, was sich aufgrund der hohen Anzahl von Komponenten negativ auf den benötigten Bauraum und die Fertigungskosten auswirkt. Zudem sind konventionelle Brennkraftmaschinen nur mit relativ hohem Aufwand auf die neue Technik umrüstbar. Ein besonderes Problem stellen die Notlaufeigenschaften dar, da ein Ausfall des Hydrauliksystems in der Regel auch einen Totalausfall der Ventilsteuerung bewirkt.Four valve motors per cylinder eight such control valves are necessary, which has a negative impact on the space required and the manufacturing costs due to the large number of components. In addition, conventional internal combustion engines can only be converted to the new technology at relatively high cost. The emergency running properties represent a particular problem, since a failure of the hydraulic system usually also causes a total failure of the valve control.
Vorteile der ErfindungAdvantages of the invention
Abhängig von den Druckverhältnissen des Druckmittels kann derDepending on the pressure conditions of the pressure medium, the
Kolben aus dem zugeordneten Nocken aus- oder in ihn eingefahren werden. Somit ist die Nockenkontur der Nocken stufenlos veränderbar, so dass beliebige Hubkurven der Gaswechselventile erzielbar sind. Insbesondere sind die Hubhöhe, die Ventilöffnungszeit und - geschwindigkeit stufenlos variabel einstellbar. Da die ein- und ausfahrbaren Kolben in den ansonsten unveränderten Nocken verschieblich gelagert und an den Stößeln ohnehin keine Änderungen notwendig sind, können konventionelle Ventiltriebe mit geringen Modifikationen umgerüstet werden. Außerdem ist wegen der Integration in die Nocken kein zusätzlicher Bauraum für die Kolben notwendig, woraus ein sehr geringer Platzbedarf resultiert. Da die Nockenwelle als Steuerorgan vollständig erhalten bleibt, ist auch bei Ausfall der Druckmittelversor- gung die Funktionstüchtigkeit der Ventilsteuerung gewährleistet, insgesamt ist mit der Erfindung gegenüber dem Stand der Technik ein äußerst kostengünstiger Ventiltrieb realisierbar.Pistons are moved out of or into the assigned cam. The cam contour of the cams is thus infinitely variable, so that any stroke curves of the gas exchange valves can be achieved. In particular, the stroke height, valve opening time and speed can be variably adjusted. Since the retractable and extendable pistons are slidably mounted in the otherwise unchanged cams and no changes are necessary on the tappets anyway, conventional valve drives with minor modifications can be used be converted. In addition, because of the integration into the cams, no additional space is required for the pistons, which results in a very small space requirement. Since the camshaft remains completely intact as a control element, the functionality of the valve control is guaranteed even if the pressure medium supply fails. Overall, the invention makes it possible to implement an extremely cost-effective valve train compared to the prior art.
Durch die in den Unteransprüchen aufgeführten Maßnahmen sind vorteilhafte Weiterbildungen und Verbesserungen der im Patent- anspruch 1 angegebenen Erfindung möglich.The measures listed in the subclaims allow advantageous developments and improvements of the invention specified in patent claim 1.
Gemäß einer besonders zu bevorzugenden Maßnahme ist das nockengipfelseitige Ende des Kolbens ballig ausgebildet. Dann kann der Nockengipfel in jeder Winkellage auf dem zugeordneten Stößel reibungsarm abwälzen.According to a particularly preferred measure, the end of the piston on the side of the cam summit is spherical. The cam peak can then roll on the associated tappet with little friction in any angular position.
Besonders vorteilhaft ist weiterhin, dass bei Ausfall der Druckmittelversorgung der Kolben in einer definierten Lage gehalten ist. Hierdurch kann die Brennkraftmaschine mit vorbestimmten Steuerzeiten und Ventilhüben weiter betrieben werden, ohne dass sich schädigende Betriebszustände einstellen können.It is also particularly advantageous that the piston is held in a defined position if the pressure medium supply fails. As a result, the internal combustion engine can continue to be operated with predetermined control times and valve strokes without damaging operating states being able to occur.
Vorzugsweise ist am nockengipfelseitigen Ende des Kolbens eine auf einer Wälzfläche eines mit dem betreffenden Nocken zusammenwirkenden Stößels abroilbare Kugel drehbar gelagert. Hierdurch werden Reibungsverluste und Verschleiß zwischen Stößel und Nocken wesentlich reduziert. Zur Lagerung der Kugel ist am nockengipfelseiti- gen Ende des Kolbens vorzugsweise eine- dem Radius der Kugel- entsprechende sphärische Lagerfläche .ausgebildet, deren Rand zurri Fassen der Kugel nach radial innen gebördelt ist. Die Lagerfiäche der Kugel wird dabei in vorteilhafter Weise durch das bereits vorhandene Schmierölsystem der Brennkraftmaschine mit Schmieröl versorgt, so dass sich zwischen Kugel und Lagerfläche ein bezüglich Reibung und Verschleiß günstiger hydrodynamischer Schmierfilm ausbilden kann.Preferably, a ball that can be rolled on a rolling surface of a tappet that interacts with the relevant cam is rotatably mounted on the end of the piston on the cam summit. This significantly reduces friction losses and wear between the tappet and cam. To support the ball, a spherical bearing surface, corresponding to the radius of the ball, is preferably formed at the end of the piston on the cam summit, the edge of which is flanged radially inward to grip the ball. The bearing surface of the ball is advantageously by the already existing Lubricating oil system of the internal combustion engine is supplied with lubricating oil, so that a hydrodynamic lubricating film which is more favorable in terms of friction and wear can form between the ball and the bearing surface.
Gemäß einer weiteren zu bevorzugenden Maßnahme wird der Kolben durch Schmieröl der Brennkraftmaschine betätigt. Da bei einerAccording to a further preferred measure, the piston is actuated by lubricating oil of the internal combustion engine. Because with one
Brennkraftmaschine ohnehin unter Druck stehendes Schmieröl vorhanden ist, kann auf eine zusätzliche hydraulische Druckmittelversorgung für die Kolbenbetätigung verzichtet werden.If there is already lubricating oil under pressure in the internal combustion engine, there is no need for an additional hydraulic pressure medium supply for the piston actuation.
In bevorzugter Weise wird der Kolben durch den Nocken linear geführt. Seine den Ventilhub und die Steuerzeiten des zugeordnetenThe piston is preferably guided linearly through the cam. Its the valve lift and the timing of the associated
Gaswechselventils beeinflussende radiale Lage ist vorzugsweise abhängig vom Kräftegleichgewicht zwischen den Kolben nach radial innen drängenden Federkräften und ihn nach radial außen drängenden Druckkräften des Schmieröls einstellbar.Radial position influencing the gas exchange valve is preferably adjustable depending on the balance of forces between the pistons, radially inward urging spring forces and the radially outwardly urging pressure forces of the lubricating oil.
Zur Führung des Kolbens im Nocken ist eine in Richtung derTo guide the piston in the cam is one in the direction of
Nockenmittelachse verlaufende, durchgehende Stufenbohrung vorgesehen, wobei sich eine Schraubenfeder einerseits an einer nockengip- felseitigen Stufe der Stufenbohrung und andererseits an einer von einer bodenseitigen Kolbenwirkfläche weg weisenden Ringfläche des Kolbens abstützt.A continuous stepped bore extending through the center of the cam is provided, with a helical spring being supported on the one hand on a step of the stepped bore on the cam gypsum side and on the other hand on an annular surface of the piston pointing away from a bottom effective piston surface.
Gemäß einer Weiterbildung ist zwischen der Wirkfläche des Kolbens und einem in das vom Nockengipfelabschnitt weg weisende - Ende der Stufenbohrung eingesetzten Verschlussstück eine Druckkammer für das Schmieröl ausgebildet, welche mit einem mit der No- ckenwellenachse koaxialen Schmierölkanal in Verbindung steht. ZurAccording to a further development, a pressure chamber for the lubricating oil is formed between the active surface of the piston and an end piece inserted into the end of the stepped bore pointing away from the cam tip section, said pressure chamber being connected to a lubricating oil channel coaxial with the camshaft axis. to
Realisierung einer hydrodynamischen Schmierung an der Lagerfläche der Kugei weist der Kolben einen die Lagerfläche mit der Druckkammer verbindenden Kanal auf. Am Verschlussstück stützt sich eine in die Stufenbohrung eingesetzte Büchse ab, die als radial innerer Anschlag für den Kolben bei ruhender Brennkraftmaschine oder bei einem Ausfall der Druckmittelversorgung dient. Dann drängt die Schraubenfeder den Kolben gegen die Büchse, so dass der Kolben in einer definierten Stellung gehalten wird.Realization of hydrodynamic lubrication on the bearing surface of the Kugei, the piston has a channel connecting the bearing surface with the pressure chamber. A bush inserted into the stepped bore is supported on the closure piece and serves as a radially inner stop for the piston when the internal combustion engine is at rest or in the event of a failure of the pressure medium supply. The coil spring then pushes the piston against the bushing, so that the piston is held in a defined position.
Der Druckaufbau bzw. der Druckabbau in den Druckkammern der mit ein- und ausfahrbaren Kolben versehenen Nocken erfolgt vorzugsweise durch eine Ventilanordnung, welche je ein dem Schmieröl- kanal der Nockenwelle vorgeordnetes und je ein dem Schmierölkanal der Nockenwelle nachgeordnetes Schaltventil beinhalten.The pressure build-up or the pressure decrease in the pressure chambers of the cams provided with retractable and extendable pistons is preferably carried out by a valve arrangement, each of which includes a switching valve upstream of the lubricating oil channel of the camshaft and a switching valve downstream of the lubricating oil channel of the camshaft.
Zeichnungendrawings
Ein Ausführungsbeispiel der Erfindung ist in der Zeichnung dar- gestellt und in der nachfolgenden Beschreibung näher erläutert. Die einzige Figur zeigt eine Querschnittsdarstellung eines Nockens als Teil einer bevorzugten Ausführungsform einer erfindungsgemäßen Vorrichtung zur variablen Steuerung der Gaswechselventile einer Brennkraftmaschine.An embodiment of the invention is shown in the drawing and explained in more detail in the following description. The single figure shows a cross-sectional view of a cam as part of a preferred embodiment of a device according to the invention for variable control of the gas exchange valves of an internal combustion engine.
Beschreibung des AusführungsbeispielsDescription of the embodiment
Von einer Vorrichtung zur variablen Steuerung der Gaswechselventile einer Brennkraftmaschine ist in der Figur aus Maßstabsgründen nur einer von mehreren Nocken 1 einer. Nockenwelle 2 im Querschnitt gezeigt. Die Nockenkontur eines solchen Nockens 1 beinhaltet einenFor reasons of scale, only one of several cams 1 of a device for variable control of the gas exchange valves of an internal combustion engine is one in the figure. Camshaft 2 shown in cross section. The cam contour of such a cam 1 contains one
Nockengrundkreisabschnitt 4 mit Nockengrundkreisradius R sowie einen hierzu exzentrischen Nockengipfelabschnitt -6. In der in der Figur gezeigten Drehlage des Nockens 1 steht der Nockengipfelabschnitt 6 mit einer Wälzfläche 8 eines Tassenstößels 10 in Kontakt, welcher die Drehbewegung des Nockens 1 als lineare Hubbewegung auf das zugeordnete Gaswechselventil überträgt. Erfindungsgemäß ist zur variablen Verstellung der Nockenkontur ein druckmittelbetätigter, durch den Nocken 1 geführter und radial stufenlos ein- und ausfahrbarer Kolben 12 vorgesehen, der endseitig zumindest einen Teil des Nockengipfelabschnitts 6 bildet. In bevorzugter Ausführungsform ist die radiale Lage des Kolbens 12 abhängig vom Kräftegleichgewicht zwischen den Kolben 12 nach radial innen drängenden Federkräften und ihn nach radial außen drängenden Druckkräften eines Druckmittels einstellbar. Als Druckmittel wird vorzugsweise das Schmieröl der Brennkraftmaschine verwendet.Cam base circle section 4 with cam base circle radius R and an eccentric cam summit section -6. In the figure shown rotational position of the cam 1, the cam summit section 6 is in contact with a rolling surface 8 of a cup tappet 10, which transmits the rotary movement of the cam 1 as a linear stroke movement to the associated gas exchange valve. According to the invention, a variable-pressure piston, guided by the cam 1 and radially steplessly retractable and extendable piston 12 is provided for variable adjustment of the cam contour, which forms at least part of the cam summit section 6 at the end. In a preferred embodiment, the radial position of the piston 12 can be adjusted as a function of the balance of forces between the pistons 12 in the case of spring forces urging radially inwards and the pressure forces of a pressure medium urging it radially outwards. The lubricating oil of the internal combustion engine is preferably used as the pressure medium.
Der Kolben 12 ist in einer in Richtung der Nockenmittelachse 14 verlaufenden, durchgehenden Stufenbohrung 16 des Nockens 1 geführt, wobei sich eine Schraubenfeder 18 einerseits an einer nocken- gipfelseitigen Stufe 20 der Stufenbohrung 16 und andererseits an einer von einer bodenseitigen Kolbenwirkfläche 22 weg weisenden Ringfläche 24 des Kolbens 12 abstützt, an welcher sich der Kolben 12 im Durchmesser stufenartig erweitert. Der Kolben 12 besteht daher aus einem durchmesserkleineren, in bzw. durch einen nockengipfeiseitigen Abschnitt 26 der Stufenbohrung 16 ragenden Kopfabschnitt 28 und einem die Wirkfläche 22 enthaltenden, durchmessergrößeren Bodenabschnitt 30. Die Schraubenfeder 18 ist dann in einem Ringraum 32 zwi- sehen dem äußeren Umfang des Kopfabschnitts 28 des Kolbens 12 und dem inneren Umfang des durchmessergrößeren Abschnitts 34 der Stufenbohrung 16 gehalten. Zwischen der bodenseitigen Wirkfläche 22 des Kolbens 12 und einem in das vom Nockengipfelabschnitt 6 weg weisende Ende des durchmessergrößeren Abschnitts 34 der Stufenbohrung 16 eingesetzten Verschlussstück 36 ist eine Druckkammer 38 ausgebildet, welche mit einem mit der Nockenwellenachse 40 koaxialen Schmierölkanal 42 in Verbindung steht, der die Druckkammern 38 der Nocken 1 der Nockenwelle 2 untereinander verbindet. Das Verschlussstück 36 kann in der Stufenbohrung 16 beispielsweise durch Verschraubung gehalten sein. Eine sich nockengipfelseitig am Verschlussstück 36 abstützende, jeweils endseitig offene Büchse 44 dient als radial innerer Anschlag für den Kolben 12 bei Druckabfall in der Druckkammer 38, beispielsweise bei Ausfall der Druckmittelversorgung oder bei Stillstand der Brennkraftmaschine. In solchen Fällen wird der Kolben 12 durch die Wirkung der Schraubenfeder 18 gegen die Büchse 44 gedrängt und somit in ei- ner definierten Lage gehalten. Um den Zustrom von Schmieröl in dieThe piston 12 is guided in a continuous stepped bore 16 of the cam 1 running in the direction of the cam center axis 14, a helical spring 18 being located on the one hand on a cam-tip step 20 of the stepped bore 16 and on the other hand on an annular surface 24 pointing away from a piston effective surface 22 on the bottom of the piston 12, on which the piston 12 expands in diameter in steps. The piston 12 therefore consists of a smaller-diameter head section 28, which projects into or through a section 26 of the stepped bore 16 on the cam tip side, and a bottom section 30 which contains the active surface 22. The coil spring 18 is then in an annular space 32 between the outer circumference of the Head portion 28 of the piston 12 and the inner periphery of the larger diameter portion 34 of the stepped bore 16 held. Between the bottom-side active surface 22 of the piston 12 and a plug 36 inserted into the end of the larger-diameter section 34 of the stepped bore 16 facing away from the cam tip section 6, a pressure chamber 38 is formed, which is connected to a lubricating oil channel 42 coaxial with the camshaft axis 40, which connects the Pressure chambers 38 of the cams 1 of the camshaft 2 connects to one another. The closure piece 36 can be held in the stepped bore 16, for example by screwing. A bushing 44, which is supported on the cam summit on the closure piece 36 and is open at the ends, serves as a radially inner stop for the piston 12 when the pressure in the pressure chamber 38 drops, for example when the pressure medium supply fails or when the internal combustion engine stops. In such cases, the piston 12 is pushed against the bush 44 by the action of the helical spring 18 and is thus held in a defined position. To keep the flow of lubricating oil into the
Druckkammer 38 bzw. das Weiterströmen von Schmieröl zur Druckkammer des nächsten Nockens nicht zu behindern, weist die Büchse 44 in ihrer Umfangswandung mit den Öffnungen des Schmierölkanals 42 fluchtende Durchbrüche auf. Alternativ könnte die Büchse 44 mit dem Verschlussstück 38 ein einstückiges Bauteil bilden. Nach radial außen ist der Bewegungshub des Kolbens 12 durch das ∑usammenge- presste Windungspaket der Schraubenfeder 18 begrenzt, die sich gegen die Stufe 20 abstützt.In order not to impede pressure chamber 38 or the further flow of lubricating oil to the pressure chamber of the next cam, bushing 44 has openings in its peripheral wall aligned with the openings of lubricating oil channel 42. Alternatively, the sleeve 44 could form an integral component with the closure piece 38. Radially outward, the stroke of movement of the piston 12 is limited by the compressed winding package of the helical spring 18, which is supported against the step 20.
Um ein. günstiges Abwälzverhalten des Nockengipfelabschnitts 6 auf der Wälzfläche 8 des Tassenstößels 10 zu gewährleisten, ist das nockengipfelseitige Ende 46 des Kolbens 12 ballig ausgebildet. In bevorzugter Weise ist am nockengipfelseitigen Ende 46 des Kolbens 12 eine auf der Wälzfläche 8 des Tassenstößels 12 abrollbare Kugel 48 drehbar gelagert. Hierzu ist am nockengipfelseitigen Ende 46 des Kolbens 12 eine dem Radius der Kugel 48 entsprechende sphärische Lagerfläche 50 ausgebildet, deren Rand 52 zum Fassen der Kugel 48 nach radial innen gebördelt ist. Das Lagerfläche 50 der Kugel 48 wird durch das Schmierölsystem der Brennkraftmaschine mit Schmieröl versorgt, wozu der Kolben 12 einen die Lagerfläche 50 der Kugel 48 mit der Druckkammer 38 verbindenden mittigen Kanal.54 aufweist.To a . To ensure favorable rolling behavior of the cam tip section 6 on the rolling surface 8 of the cup tappet 10, the end 46 of the piston 12 on the cam tip side is spherical. In a preferred manner, a ball 48 that can be rolled on the rolling surface 8 of the cup tappet 12 is at the end 46 of the piston 12 on the cam summit side rotatably mounted. For this purpose, a spherical bearing surface 50 corresponding to the radius of the ball 48 is formed on the end 46 of the piston 12 on the cam summit, the edge 52 of which is flanged radially inwards for gripping the ball 48. The bearing surface 50 of the ball 48 is supplied with lubricating oil by the lubricating oil system of the internal combustion engine, for which purpose the piston 12 has a central channel connecting the bearing surface 50 of the ball 48 with the pressure chamber 38 . 54 has.
Der Druckaufbau bzw. der Druckabbau in den Druckkammern 38 der mit ein- und ausfahrbaren Kolben 12 versehenen Nocken 1 erfolgt durch eine aus Maßstabsgründen nicht dargestellte Ventilanordnung, welche beispielsweise je ein dem Schmierölkanal 42 der Nockenwelle 2 vorgeordnetes und je ein dem Schmierölkanal 42 nachgeordnetes Schaltventil beinhaltet.The pressure build-up or the pressure decrease in the pressure chambers 38 of the cams 1 provided with retractable and extendable pistons 12 takes place by a valve arrangement, not shown for reasons of scale, which includes, for example, one switching valve upstream of the lubricating oil channel 42 of the camshaft 2 and one switching valve downstream of the lubricating oil channel 42 ,
Vor diesem Hintergrund stellt sich die Funktion der erfindungs- gemäßen Vorrichtung zur variablen Steuerung von Gaswechseiventilen einer Brennkraftmaschine wie folgt dar :Against this background, the function of the device according to the invention for the variable control of gas exchange valves of an internal combustion engine is as follows:
Kennlinienabhängig wird mittels der Ventilanordnung von der Motorsteuerung im Schmierölkanal 42 bzw. in den an diesen angeschlossenen Druckkammern 38 ein Schmieröldruck zur Erzeugung von Druckkräften an den Wirkflächen 22 der Kolben 12 eingestellt, welche im Kräftegleichgewicht mit den Federkräften der Schraubenfedern 18 eine bestimmte gemeinsame radiale Position der Kolben 12 in Bezug zu den zugeordneten Nocken 1 hervorrufen. Die sicrϊeins.tellende radiale Position der Kolben 12 entspricht dabei den' gewünschten Ventilhü-- ben, Ventilöffnungszeiten und Ventilöffnungsgeschwindigkeiten. Zur stufenlosen Verstellung dieser Parameter wird lediglich der Schmieröldruck in den Druckkammern 38 entsprechend angepasst, .so dass sich eine neue radiale Lage der Kolben 12 einstellen kann. Gemäß der vorangehend beschriebenen bevorzugten Ausführungsform der Erfindung werden zur Einstellung der radialen Lage der Kolben 12 einseitig wirkende Federmittel 18 verwendet. Gemäß einer weiteren Ausführungsform könnten auf die Kolben 12 jedoch auch beidseitig Federmittel und zusätzlich einseitig das Druckmittel wirken.Depending on the characteristic curve, a lubricating oil pressure for generating compressive forces on the active surfaces 22 of the pistons 12 is set by the engine control in the lubricating oil channel 42 or in the pressure chambers 38 connected to the latter, which in equilibrium with the spring forces of the coil springs 18 a certain common radial position of the Cause piston 12 in relation to the assigned cams 1. The sicrϊeins . tellende radial position of the piston 12 corresponds to the ben 'Ventilhü-- desired, valve opening times and the valve opening speeds. For the continuous adjustment of these parameters, only the lubricating oil pressure in the pressure chambers 38 is adjusted accordingly, so that a new radial position of the pistons 12 can be set. According to the preferred embodiment of the invention described above, one-way spring means 18 are used to adjust the radial position of the pistons 12. According to a further embodiment, however, spring means could also act on the pistons 12 on both sides and the pressure medium additionally on one side.
Als weitere Variante könnten zumindest einige der Kolben als Differentialkolben ausgeführt sein, welche beidseitig mit Druckmittel beauf- schlagt sind. Hierbei können auch zusätzlich Federmittel vorgesehen sein, welche in einer oder beiden Bewegungsrichtungen der Kolben un- terstützend wirken sowie diese bei Ausfall der Druckmittelversorgung in eine definierte Lage drängen und sie dort halten. As a further variant, at least some of the pistons could be designed as differential pistons which are pressurized on both sides. Here, spring means can also be provided, which act as a support in one or both directions of movement of the pistons and, if the pressure medium supply fails, urge them into a defined position and hold them there.

Claims

Patentansprüche claims
1. Vorrichtung zur variablen Steuerung der Gaswechselventile einer Brennkraftmaschine, von welchen wenigstens ein Gaswechselventil von einem Nocken (1 ) einer Nockenwelle (2) angesteuert ist, der eine Nockenkontur mit einem Nockengrundkreisabschnitt (4) und einem Nockengipfelabschnitt (6) aufweist, dadurch gekennzeichnet, dass zur variablen Verstellung der Nockenkontur ein druckmittelbetätigter, durch den Nocken (1) geführter und radial stufenlos ein- und ausfahrbarer Kolben (12) vorgesehen ist, der endseitig zumindest einen Teil des Nockengipfelabschnitts (6) bildet.1. Device for variably controlling the gas exchange valves of an internal combustion engine, of which at least one gas exchange valve is controlled by a cam (1) of a camshaft (2), which has a cam contour with a cam base circle section (4) and a cam summit section (6), characterized in that that for the variable adjustment of the cam contour, a pressure medium-actuated piston (12) which is guided through the cam (1) and is radially steplessly extendable and retractable is provided, which at the end forms at least part of the cam summit section (6).
2. Vorrichtung nach Anspruch 1 , dadurch gekennzeichnet, dass das no- ckengipfeiseitige Ende (46) des Kolbens (12) im wesentlichen ballig ausgebildet ist.2. Device according to claim 1, characterized in that the end (46) of the piston (12) on the cam tip side is essentially spherical.
3. Vorrichtung nach Anspruch 2, dadurch gekennzeichnet, dass der Kolben (12) bei Ausfall der Druckmittelversorgung in einer definierten Lage gehalten ist.3. Device according to claim 2, characterized in that the piston (12) is held in a defined position in the event of failure of the pressure medium supply.
4. Vorrichtung nach Anspruch 3, dadurch gekennzeichnet, dass am no- ckengipfelseitigen Ende (46) des Kolbens (12) eine auf einer Wälzflä- ehe (8) eines mit dem betreffenden Nocken (1 ) zusammenwirkenden Stößels (10) abrollbare Kugel (48) drehbar gelagert ist.4. The device according to claim 3, characterized in that on the cam tip end (46) of the piston (12) one on a roller surface. before (8) a tappet (10) which can be unrolled with the relevant cam (1) and which can roll off ball (48) is rotatably mounted.
Vorrichtung nach Anspruch 4, dadurch gekennzeichnet, dass am no- ckengipfelseitigen Ende (46) des Kolbens (12) eine dem Radius der Kugel (48) entsprechende sphärische Lagerfläche (50) ausgebildet ist, deren Rand (52) zum Fassen der Kugel (48) nach radial innen gebördelt ist.Apparatus according to claim 4, characterized in that a spherical bearing surface (50) corresponding to the radius of the ball (48) is formed on the end (46) of the piston (12) on the cam summit, the edge (52) of which for gripping the ball (48 ) is flanged radially inwards.
6. Vorrichtung nach Anspruch 5, dadurch gekennzeichnet, dass die Lagerfläche (50) der Kugel (48) durch das Schmierölsystem der Brennkraftmaschine mit Schmieröl versorgt ist.6. The device according to claim 5, characterized in that the bearing surface (50) of the ball (48) is supplied with lubricating oil by the lubricating oil system of the internal combustion engine.
7. Vorrichtung nach Anspruch 6, dadurch gekennzeichnet, dass der Kolben (12) im Nocken (1) linear geführt und durch Schmieröl der7. The device according to claim 6, characterized in that the piston (12) in the cam (1) guided linearly and by lubricating oil
Brennkraftmaschine betätigt ist.Internal combustion engine is actuated.
8. Vorrichtung nach Anspruch 7, dadurch gekennzeichnet, dass die radiale Lage des Kolbens (12) abhängig vom Kräftegleichgewicht zwi- sehen den Kolben (12) nach radial innen drängenden Federkräften und ihn nach radial außen drängenden Druckkräften des Schmieröls einstellbar ist.8. The device according to claim 7, characterized in that the radial position of the piston (12) depending on the balance of forces between see the piston (12) to the radially inward urging spring forces and it is adjustable to the radially outward pressing forces of the lubricating oil.
9. Vorrichtung nach Anspruch 7 oder 8, dadurch gekennzeichnet, dass der Kolben (12) in einer in Richtung der Nockenmittelachse (1.4) verlaufenden, durchgehenden Stufenbohrung (16) geführt ist, wobei sich eine Schraubenfeder (18) einerseits an einer nockengipfelseitigen Stufe (20) der Stufenbohrung (16) und andererseits an einer von einer bo- ' denseitigen Kolbenwirkfläche (22) weg weisenden Ringfläche (24) des Kolbens (12) abstützt.9. The device according to claim 7 or 8, characterized in that the piston (12) in a in the direction of the cam central axis (1.4) extending, continuous step bore (16) is guided, wherein a Helical spring (18) on one side of the stepped bore (16) and on the other hand, on a cam-vertex-side step (20) at one of a bo- 'denseitigen effective piston face (22) pointing away annular surface (24) of the piston (12).
10. Vorrichtung nach Anspruch 9, dadurch gekennzeichnet, dass zwischen der Wirkfläche (22) des Kolbens (12) und einem in das vom No- ckengipfelabschπitt (6) weg weisende Ende der Stufenbohrung (16) eingesetzten Verschlussstück (36) eine Druckkammer (38) für das Schmieröl ausgebildet ist, welche mit einem mit der Nockenwellenachse (40) koaxialen Schmierölkanal (42) in Verbindung steht.10. The device according to claim 9, characterized in that a pressure chamber (38) is inserted between the active surface (22) of the piston (12) and one in the end of the stepped bore (16) facing away from the cam tip section (6) ) is designed for the lubricating oil, which is connected to a lubricating oil channel (42) coaxial with the camshaft axis (40).
11. Vorrichtung nach Anspruch 10, dadurch gekennzeichnet, dass sich am Verschlussstück (36) eine in die Stufenbohrung (16) eingesetzte Büchse (44) abstützt, die als radial innerer Anschlag für den Kolben11. The device according to claim 10, characterized in that on the closure piece (36) in the stepped bore (16) inserted bushing (44) is supported, which acts as a radially inner stop for the piston
(12) dient.(12) serves.
12. Vorrichtung nach den Ansprüchen 4 bis 1 1 , dadurch gekennzeichnet, dass der Kolben (12) einen die Lagerfläche (50) der Kugel (48) mit der Druckkammer (38) verbindenden Kanal (54) aufweist.12. Device according to claims 4 to 1 1, characterized in that the piston (12) has a bearing surface (50) of the ball (48) with the pressure chamber (38) connecting channel (54).
13. ; Vorrichtung nach einem der vorhergehenden Ansprüche, dadurch ge-13.; Device according to one of the preceding claims,
. kennzeichnet, dass der Druckaufbau bzw. der Druckabbau in den, indicates that the pressure build-up or pressure reduction in the
Druckkammern (3fr) der mit ein- und ausfahrbaren Kolben (1 2) verse- henen Nocken (1 ) durch eine Ventilanordπung erfolgt, welche je ein dem Schmierölkanal (42) der Nockenwelle (2) vorgeordnetes und je ein dem Schmierölkanal (42) nachgeordnetes Schaltventil beinhaltet. Pressure chambers (3fr) of the cams (1) provided with retractable and extendable pistons (1 2) are created by a valve arrangement, which has one in front of the lubricating oil channel (42) of the camshaft (2) and one each includes the switching valve downstream of the lubricating oil channel (42).
EP02747200A 2001-08-24 2002-06-08 Device for the variable control of gas exchange valves in an internal combustion engine Expired - Lifetime EP1490584B1 (en)

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DE10141605A DE10141605A1 (en) 2001-08-24 2001-08-24 Device for the variable control of the gas exchange valves of an internal combustion engine
DE10141605 2001-08-24
PCT/DE2002/002092 WO2003018964A2 (en) 2001-08-24 2002-06-08 Device for the variable control of gas exchange valves in an internal combustion engine

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DE10337430A1 (en) 2003-08-13 2005-03-17 Fev Motorentechnik Gmbh Internal combustion engine with shift cam
GB0620446D0 (en) * 2006-10-14 2006-11-22 Powertrain Technology Ltd Improvements to valve mechanisms with hydraulically actuated secondary opening
GB2443690B (en) * 2006-11-09 2011-10-12 Anthony Edgar Blackburn Retractable cam
JP5488512B2 (en) * 2011-03-28 2014-05-14 三菱自動車工業株式会社 Cam structure
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GB239579A (en) * 1924-06-05 1925-09-07 Charles George Garrard Improvements in or relating to cam or like mechanism
DE3705128A1 (en) 1987-02-18 1988-09-01 Opel Adam Ag Camshaft intended for an internal combustion engine
JPH01178710A (en) * 1988-01-06 1989-07-14 Mazda Motor Corp Valve driving device for engine
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