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EP0334272A1 - Hydraulic valve opening unit in the cylinder-head of an internal combustion engine - Google Patents

Hydraulic valve opening unit in the cylinder-head of an internal combustion engine Download PDF

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Publication number
EP0334272A1
EP0334272A1 EP89104989A EP89104989A EP0334272A1 EP 0334272 A1 EP0334272 A1 EP 0334272A1 EP 89104989 A EP89104989 A EP 89104989A EP 89104989 A EP89104989 A EP 89104989A EP 0334272 A1 EP0334272 A1 EP 0334272A1
Authority
EP
European Patent Office
Prior art keywords
valve
piston
master piston
opening unit
valve opening
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
EP89104989A
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German (de)
French (fr)
Other versions
EP0334272B1 (en
Inventor
Jurij Gartner
Anton Schollweck
Peter Langen
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.)
Bayerische Motoren Werke AG
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Bayerische Motoren Werke AG
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Filing date
Publication date
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Publication of EP0334272A1 publication Critical patent/EP0334272A1/en
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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
    • F01L9/00—Valve-gear or valve arrangements actuated non-mechanically
    • F01L9/10—Valve-gear or valve arrangements actuated non-mechanically by fluid means, e.g. hydraulic
    • F01L9/11—Valve-gear or valve arrangements actuated non-mechanically by fluid means, e.g. hydraulic in which the action of a cam is being transmitted to a valve by a liquid column
    • F01L9/12—Valve-gear or valve arrangements actuated non-mechanically by fluid means, e.g. hydraulic in which the action of a cam is being transmitted to a valve by a liquid column with a liquid chamber between a piston actuated by a cam and a piston acting on a valve stem
    • F01L9/14—Valve-gear or valve arrangements actuated non-mechanically by fluid means, e.g. hydraulic in which the action of a cam is being transmitted to a valve by a liquid column with a liquid chamber between a piston actuated by a cam and a piston acting on a valve stem the volume of the chamber being variable, e.g. for varying the lift or the timing of a valve
    • 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
    • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
    • F01L1/34—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift
    • F01L1/344—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift changing the angular relationship between crankshaft and camshaft, e.g. using helicoidal gear
    • F01L1/3442—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift changing the angular relationship between crankshaft and camshaft, e.g. using helicoidal gear using hydraulic chambers with variable volume to transmit the rotating force
    • F01L2001/34423—Details relating to the hydraulic feeding circuit
    • F01L2001/34446—Fluid accumulators for the feeding circuit

Definitions

  • the invention relates to a hydraulic valve opening unit of the type specified in the preamble of the first claim and is based on the generic DE-OS 36 21 402.
  • Hydraulic valve opening units are known in various designs.
  • a cam actuates a master piston, which acts on a working piston via a hydraulic chamber, the latter resting on the stem of a lift valve.
  • the master piston and the working piston are usually arranged coaxially with one another.
  • this arrangement requires a large amount of space and is very tall.
  • the disadvantages with regard to the hydraulic transmission behavior are evident. Therefore, in the above-mentioned document, the master piston is arranged at right angles to the working piston or to the stroke valve actuated by it.
  • the master piston is arranged spatially between the inlet and outlet valve and its axis not only angled, but also offset from the axis of the inlet valve. This makes it possible to supply the hydraulic fluid acting on the working piston to the latter practically from the side, that is to say tangentially.
  • braking devices are often provided which influence the speed of the valve closing movement caused by the removal of hydraulic fluid.
  • the hydraulic fluid discharged usually flows through a throttle gap.
  • braking device concentrically with the working piston and in particular within it.
  • Claim 4 advantageously develops the cam actuating the master piston.
  • the cam can be designed such that the closing movement of the valve is always caused in all operating points of the internal combustion engine by the removal of hydraulic fluid. This reduces the mechanical load on the master piston and allows it to be simplified or designed to be correspondingly small. The mechanical load on the cam and master piston therefore only has to be taken into account in the initial phase of the valve opening movement. If a hydraulic transmission ratio is integrated in the hydraulic valve opening unit according to the invention, a rapid valve opening movement desired with regard to the dynamics of gas exchange can be achieved even with relatively little acceleration of the master piston - this means low mechanical loads and thus small size.
  • An intake valve 2 is arranged in a cylinder head 1 of an internal combustion engine, and an exhaust valve 3 is arranged at an angle thereto. While the latter is actuated by a cam 5, as is generally the case with the interposition of a hydraulic lash adjuster 4, a hydraulic valve opening unit, designated as a whole by 6, is provided for the inlet valve 2.
  • This consists essentially of a housing 7, a working piston 8 actuating the inlet valve 2, a master piston 9 which is in hydraulic connection with the latter, and a cam 10 acting on the master piston 9.
  • the axis of the master piston 9 is angled and offset from the axis of the working piston 8 or the inlet valve 2.
  • the master piston 9 is arranged within the V-space spanned by the inlet valve 2 and the outlet valve 3, an extremely space-saving arrangement is created. This can also be seen from FIG. 2, two valve opening units according to the invention being shown here in mirror image next to one another.
  • the mode of operation of the hydraulic valve opening unit 6 is as follows: Hydraulic fluid enters a hydraulic chamber 16 via an inlet channel 14 and a check valve 12 Discharge channel 18, which opens into a storage space 20 and can be closed by means of a slide 22. This slide 22 is actuated by an eccentric shaft 26 acting against a tappet 24.
  • the hydraulic chamber 16 is further delimited by the master piston 9, the effective cross section of which is larger than the effective cross section of the working piston 8. If the master piston 9 is now moved by rotation of the cam 10, it displaces hydraulic fluid from the hydraulic chamber 16 via a valve with a check valve 27 provided channel 28 in a pressure chamber 30 (see in particular. Fig. 2). As a result, the working piston 8 is moved and thus causes an opening movement of the inlet valve 2. This process is ended when either the stroke of the master piston 9 is reduced or the control channel 18 is released. For this purpose, the slide 22 can be moved in or against the direction of arrow 32 by rotation of the eccentric shaft 26.
  • the throttle gap 34 is determined by one within the Working piston 8 provided, designated in its entirety with 36 braking device (see in particular. Fig. 2).
  • that braking device 36 consists of a tapered longitudinal groove 37 provided in the outer surface of the working piston 8 and the non-return valve 28 already explained. Since the latter prevents hydraulic medium from being discharged from the pressure chamber 30, the medium flows over the tapered longitudinal groove 37 and the thus narrowing in the course of the valve closing movement, formed together with a projection 35 of the housing 7, throttle gap 34.
  • phase 3 shows an exemplary elevation curve of the master piston as a function of the cam angle ⁇ . That curve is divided into three main phases.
  • the first phase designated I a maximum elevation ⁇ h per cam angle change ⁇ is aimed for. That maximum valve lift increase is determined in particular by the mechanical strength of the cam 10 and the master piston 9. Since, according to the invention, a hydraulic transmission ratio is built into the hydraulic valve opening unit 6, the cross-section of the master piston 9 is therefore larger than the cross-section of the working piston 8, is sufficient to achieve one desired rapid valve opening movement a relatively slower stroke of the master piston 9.
  • the phase II following that first phase represents a transition area to phase III, which in turn has a decreasing master piston stroke h.
  • Phase II also covers a relatively wide cam angle range ⁇ * because that phase represents the usual working range for intake valve 2.
  • the valve closing movement is initiated in the entire operating range of the internal combustion engine by actuating the slide 22 and discharging hydraulic fluid into the storage space 20.
  • This has the advantage that the stroke of the master piston 9 can be designed in phase III taking mechanical aspects into account.
  • an optimal filling process of the pressure chamber 30 can be achieved in interaction with the design of the working piston 8 and the check valve 27. Since low flow velocities are desired in the latter from the point of view of fluid dynamics (vibration behavior and vapor bubble formation), with such a flat cam contour the Phase II long filling times can be realized. Since the valve lift is always deactivated during phase II, narrow tolerances can be avoided in particular in connection with the activation of the eccentric shaft 26 if that phase covers a relatively wide cam angle range ( ⁇ *).

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

In a hydraulic valve opening unit, a transmitting piston (9) is operated by a cam (10) and is hydraulically connected to a working piston which acts on the stem of an inlet valve (2). The closing movement of the inlet valve (2) takes place, as is known, under the influence of a valve spring. According to the invention, the axis of the transmitting piston (5) runs at an angle and offset with respect to the axis of the working piston (8). Furthermore, the transmitting piston (9) is arranged in the V-space which is defined by the inlet and outlet valves (2, 3) that are arranged at an angle with respect to one another. Overall, this results in an extremely space-saving design. <IMAGE>

Description

Die Erfindung betrifft eine hydraulische Ventilöffnungs­einheit der im Oberbegriff des ersten Anspruchs angege­benen Art und geht aus von der gattungsbildenden DE-OS 36 21 402.The invention relates to a hydraulic valve opening unit of the type specified in the preamble of the first claim and is based on the generic DE-OS 36 21 402.

Hydraulische Ventilöffnungseinheiten sind in mannig­fachen Ausführungen bekannt. Dabei betätigt ein Nocken einen Geberkolben, welcher über einen Hydraulikraum auf einen Arbeitskolben einwirkt, wobei letzterer auf dem Schaft eines Hubventiles aufliegt. Zumeist sind dabei der Geberkolben und der Arbeitskolben gleichachsig zueinander angeordnet. Diese Anordnung erfordert jedoch einen hohen Raumbedarf und baut dabei sehr hoch. Vor­geschlagen wurde bereits auch, Geberkolben und Arbeits­kolben parallel nebeneinander anzuordnen. Hierdurch ergeben sich jedoch große Mengen von bewegter Hydrau­likflüssigkeit. Die Nachteile hinsichtlich des hydrau­lischen Übertragungsverhaltens sind evident. Deshalb ist in der o. g. Schrift der Geberkolben rechtwinkelig zum Arbeitskolben bzw. zu dem von diesem betätigten Hubven­til angeordnet.Hydraulic valve opening units are known in various designs. A cam actuates a master piston, which acts on a working piston via a hydraulic chamber, the latter resting on the stem of a lift valve. The master piston and the working piston are usually arranged coaxially with one another. However, this arrangement requires a large amount of space and is very tall. It has also already been proposed to arrange the master piston and the working piston in parallel. However, this results in large amounts of moving hydraulic fluid. The disadvantages with regard to the hydraulic transmission behavior are evident. Therefore, in the above-mentioned document, the master piston is arranged at right angles to the working piston or to the stroke valve actuated by it.

Wenngleich jene Anordnung hinsichtlich des erforder­lichen Bauraumes eine Verbesserung darstellt, erfordert diese immer noch unverhältnismäßig großvolumig bauende Zylinderköpfe. Es ist daher Aufgabe der Erfindung, eine hydraulische Ventilöffnungseinheit der im Oberbegriff des ersten Anspruchs angegebenen Art hinsichtlich des erforderlichen Bauraumes weiter zu optimieren.
Diese Aufgabe wird durch die kennzeichnenden Merkmale des ersten Anspruchs gelöst.Although that arrangement is an improvement in terms of the space required, it still requires disproportionately large cylinder heads. It is therefore an object of the invention to further optimize a hydraulic valve opening unit of the type specified in the preamble of the first claim with regard to the required installation space.
This object is achieved by the characterizing features of the first claim.

Bei winkeliger Anordnung von Einlaßventil und Auslaß­ventil, welche ihrerseits Vorteile hinsichtlich der möglichen Brennraumgestaltung sowie der Ausbildung der Einlaß- und Auslaßkanäle bietet, ist eine besonders kompakt bauende Anordnung erzielbar, wenn zum einen der Geberkolben räumlich zwischen Einlaß- und Auslaßventil angeordnet ist und dabei dessen Achse nicht nur winke­lig, sondern darüber hinaus versetzt zur Achse des Einlaßventiles verläuft. Hiermit ist es nämlich möglich, die auf den Arbeitskolben einwirkende Hydraulikflüssig­keit diesem quasi von der Seite her, also tangential zuzuführen.With an angular arrangement of the inlet valve and outlet valve, which in turn offers advantages with regard to the possible combustion chamber design and the design of the inlet and outlet channels, a particularly compact construction can be achieved if, on the one hand, the master piston is arranged spatially between the inlet and outlet valve and its axis not only angled, but also offset from the axis of the inlet valve. This makes it possible to supply the hydraulic fluid acting on the working piston to the latter practically from the side, that is to say tangentially.

Vorteilhafte Aus- und Weiterbildungen beschreiben die Unteransprüche.
Ist der Querschnitt des Geberkolbens größer als der Querschnitt des Arbeitskolbens, so liegt eine hydrau­lische Übersetzung vor. Hohe Ventil- bzw. Arbeitskol­benhübe sind mit deutlich geringeren Hüben des Geber­kolbens erzielbar. In Achsrichtung des Geberkolbens wird der Raumbedarf somit verringert; auch die den maximalen Geberkolbenhub bestimmende Querschnittsfläche des Nockens kann kleiner gehalten werden.Advantageous training and further education describe the dependent claims.
If the cross section of the master piston is larger than the cross section of the working piston, there is a hydraulic ratio. High valve or working piston strokes can be achieved with significantly lower strokes of the master piston. The space requirement is thus reduced in the axial direction of the master piston; the cross-sectional area of the cam that determines the maximum master piston stroke can also be kept smaller.

In hydraulischen Ventilöffnungseinheiten sind des öfteren Bremsvorrichtungen vorgesehen, welche die durch eine Abfuhr von Hydraulikflüssigkeit hervorgerufene Ventilschließbewegung geschwindigkeitsmäßig beeinflus­sen. Dazu strömt die abgeführte Hydraulikmenge zumeist über einen Drosselspalt. Erfindungsgemäß wird nunmehr vorgeschlagen, jene Bremsvorrichtung konzentrisch zum Arbeitskolben und insbesondere innerhalb diesem anzu­ordnen. Alternativ ist es auch möglich, den Arbeits­kolben innerhalb der entsprechend ausgebildeten Brems­vorrichtung vorzusehen. Beide Varianten reduzieren den erforderlichen Bauraum um ein weiteres.In hydraulic valve opening units, braking devices are often provided which influence the speed of the valve closing movement caused by the removal of hydraulic fluid. For this purpose, the hydraulic fluid discharged usually flows through a throttle gap. According to the invention, it is now proposed to arrange that braking device concentrically with the working piston and in particular within it. Alternatively, it is also possible to provide the working piston within the appropriately designed braking device. Both variants reduce the required installation space by another.

Anspruch 4 bildet den den Geberkolben betätigenden Nocken vorteilhaft weiter. Insbesondere bei Verwendung einer drosselnden Bremsvorrichtung kann der Nocken derart ausgebildet sein, daß die Schließbewegung des Ventiles in allen Betriebspunkten der Brennkraftmaschine stets durch Abfuhr von Hydraulikflüssigkeit hervorge­rufen wird. Dies reduziert die mechanische Belastung des Geberkolbens und erlaubt, diesen vereinfacht bzw. entsprechend kleinbauend auszuführen. Die mechanische Belastung von Nocken und Geberkolben muß somit lediglich in der Anfangsphase der Ventilöffnungsbewegung berück­sichtigt werden. Ist dabei in der erfindungsgemäßen hydraulischen Ventilöffnungseinheit ein hydraulisches Übersetzungsverhältnis integriert, so kann auch bei relativ geringer Beschleunigung des Geberkolbens - dies bedeutet geringe mechanische Belastungen und somit geringe Baugröße - eine im Hinblick auf die Ladungs­wechseldynamik erwünschte schnelle Ventilöffnungsbewe­gung erzielt werden.Claim 4 advantageously develops the cam actuating the master piston. In particular when using a throttling braking device, the cam can be designed such that the closing movement of the valve is always caused in all operating points of the internal combustion engine by the removal of hydraulic fluid. This reduces the mechanical load on the master piston and allows it to be simplified or designed to be correspondingly small. The mechanical load on the cam and master piston therefore only has to be taken into account in the initial phase of the valve opening movement. If a hydraulic transmission ratio is integrated in the hydraulic valve opening unit according to the invention, a rapid valve opening movement desired with regard to the dynamics of gas exchange can be achieved even with relatively little acceleration of the master piston - this means low mechanical loads and thus small size.

Im folgenden wird die Erfindung anhand eines bevorzugten Ausführungsbeispiels näher beschrieben. Es zeigt:

  • Fig. 1 einen Querschnitt durch einen Zylinderkopf einer Brennkraftmaschine mit einer hydrau­lischen Ventilöffnungseinheit,
  • Fig. 2 den Schnitt A-A aus Fig. 1, sowie
  • Fig. 3 einen beispielhaften durch die Nockenform gegebenen Hubverlauf des Geberkolbens.
The invention is described in more detail below with the aid of a preferred exemplary embodiment. It shows:
  • 1 shows a cross section through a cylinder head of an internal combustion engine with a hydraulic valve opening unit,
  • Fig. 2 shows the section AA from Fig. 1, and
  • 3 shows an exemplary stroke profile of the master piston given by the cam shape.

In einem Zylinderkopf 1 einer Brennkraftmaschine ist ein Einlaßventil 2, sowie winkelig zu diesem ein Auslaß­ventil 3 angeordnet. Während letzteres wie allgemein üblich unter Zwischenschaltung eines hydraulischen Spielausgleichselementes 4 von einem Nocken 5 betätigt wird, ist für das Einlaßventil 2 eine ihrer Gesamtheit mit 6 bezeichnete hydraulische Ventilöffnungseinheit vorgesehen. Diese besteht im wesentlichen aus einem Gehäuse 7, einem das Einlaßventil 2 betätigenden Ar­beitskolben 8, einem mit diesem in hydraulischer Ver­bindung stehenden Geberkolben 9, sowie einem auf den Geberkolben 9 einwirkenden Nocken 10.An intake valve 2 is arranged in a cylinder head 1 of an internal combustion engine, and an exhaust valve 3 is arranged at an angle thereto. While the latter is actuated by a cam 5, as is generally the case with the interposition of a hydraulic lash adjuster 4, a hydraulic valve opening unit, designated as a whole by 6, is provided for the inlet valve 2. This consists essentially of a housing 7, a working piston 8 actuating the inlet valve 2, a master piston 9 which is in hydraulic connection with the latter, and a cam 10 acting on the master piston 9.

Erfindungsgemäß liegt die Achse des Geberkolbens 9 winkelig und versetzt zur Achse des Arbeitskolbens 8 bzw. des Einlaßventiles 2. Indem zusätzlich der Geber­kolben 9 innerhalb des von dem Einlaßventil 2 sowie dem Auslaßventil 3 aufgespannten V-Raumes angeordnet ist, ist eine äußerst raumsparende Anordnung geschaffen. Ersichtlich wird dies auch aus Fig. 2, wobei hier zwei erfindungsgemäße Ventilöffnungseinheiten spiegelbildlich nebeneinander gezeigt sind.According to the invention, the axis of the master piston 9 is angled and offset from the axis of the working piston 8 or the inlet valve 2. In addition, the master piston 9 is arranged within the V-space spanned by the inlet valve 2 and the outlet valve 3, an extremely space-saving arrangement is created. This can also be seen from FIG. 2, two valve opening units according to the invention being shown here in mirror image next to one another.

Die Wirkungsweise der hydraulischen Ventilöffnungsein­heit 6 ist dabei wie folgt: über einen Zulaufkanal 14 sowie ein Rückschlagventil 12 gelangt Hydraulikflüssig­keit in eine Hydraulikkammer 16. Diese weist zudem einen Absteuerkanal 18 auf, welcher in einen Speicherraum 20 mündet und mittels eines Schiebers 22 verschließbar ist. Betätigt wird dieser Schieber 22 von einer gegen einen Stößel 24 wirkenden Exzenterwelle 26.The mode of operation of the hydraulic valve opening unit 6 is as follows: Hydraulic fluid enters a hydraulic chamber 16 via an inlet channel 14 and a check valve 12 Discharge channel 18, which opens into a storage space 20 and can be closed by means of a slide 22. This slide 22 is actuated by an eccentric shaft 26 acting against a tappet 24.

Begrenzt wird die Hydraulikkammer 16 desweiteren vom Geberkolben 9, wobei dessen wirksamer Querschnitt größer ist als der wirksame Querschnitt des Arbeitskolbens 8. Wird nun durch Rotation des Nockens 10 der Geberkolben 9 bewegt, so verdrängt er Hydraulikflüssigkeit aus der Hydraulikkammer 16 über einen mit einem Rückschlagventil 27 versehenen Kanal 28 in eine Druckkammer 30 (siehe insbes. Fig. 2). Hierdurch wird der Arbeitskolben 8 bewegt und veranlaßt somit eine Öffnungsbewegung des Einlaßventiles 2. Dieser Vorgang wird beendet, wenn entweder der Hub des Geberkolbens 9 geringer wird oder der Absteuerkanal 18 freigegeben wird. Dazu kann durch Rotation der Exzenterwelle 26 der Schieber 22 in bzw. gegen Pfeilrichtung 32 bewegt werden. Gibt der Schieber 22 den Absteuerkanal 18 frei, so gelangt die Hydraulik­flüssigkeit aus der Druckkammer 30 über einen sich im Verlauf der Schließbewegung des Einlaßventiles 2 ver­engenden Drosselspalt 34 in die Hydraulikkammer 16 und schließlich in den Speicherraum 20. Bestimmt wird der Drosselspalt 34 von einer innerhalb des Arbeitskolbens 8 vorgesehenen, in ihrer Gesamtheit mit 36 bezeichneten Bremsvorrichtung (siehe insbes. Fig. 2). Im wesentlichen besteht jene Bremsvorrichtung 36 aus einer in der Mantelfläche des Arbeitskolbens 8 vorgesehenen, sich verjüngenden Längsnut 37 sowie dem bereits erläuterten Rückschlagventil 28. Da letzteres eine Abfuhr von Hydraulikmedium aus der Druckkammer 30 verhindert, strömt das medium über die sich verjüngende Längsnut 37 und den somit sich im Laufe der Ventilschließbewegung verengenden, zusammen mit einem Vorsprung 35 des Gehäu­ses 7 gebildeten Drosselspalt 34.The hydraulic chamber 16 is further delimited by the master piston 9, the effective cross section of which is larger than the effective cross section of the working piston 8. If the master piston 9 is now moved by rotation of the cam 10, it displaces hydraulic fluid from the hydraulic chamber 16 via a valve with a check valve 27 provided channel 28 in a pressure chamber 30 (see in particular. Fig. 2). As a result, the working piston 8 is moved and thus causes an opening movement of the inlet valve 2. This process is ended when either the stroke of the master piston 9 is reduced or the control channel 18 is released. For this purpose, the slide 22 can be moved in or against the direction of arrow 32 by rotation of the eccentric shaft 26. If the slide 22 releases the control channel 18, the hydraulic fluid passes from the pressure chamber 30 via a throttle gap 34 which narrows in the course of the closing movement of the inlet valve 2 into the hydraulic chamber 16 and finally into the storage space 20. The throttle gap 34 is determined by one within the Working piston 8 provided, designated in its entirety with 36 braking device (see in particular. Fig. 2). Essentially, that braking device 36 consists of a tapered longitudinal groove 37 provided in the outer surface of the working piston 8 and the non-return valve 28 already explained. Since the latter prevents hydraulic medium from being discharged from the pressure chamber 30, the medium flows over the tapered longitudinal groove 37 and the thus narrowing in the course of the valve closing movement, formed together with a projection 35 of the housing 7, throttle gap 34.

Fig. 3 zeigt eine beispielhafte Erhebungskurve des Geberkolbens in Abhängigkeit vom Nockenwinkel φ . Jene Erhebungskurve ist in drei wesentliche Phasen unter­teilt. In der mit I bezeichneten ersten Phase wird eine maximale Erhebung Δh je Nockenwinkeländerung Δφ ange­strebt. Bestimmt wird jene maximale Ventilhubzunahme insbesondere durch die mechanische Festigkeit des Nockens 10 sowie des Geberkolbens 9. Da erfindungsgemäß in der hydraulischen Ventilöffnungseinheit 6 ein hydrau­lisches Übersetzungsverhältnis eingebaut ist, der Querschnitt des Geberkolbens 9 also größer ist als der Querschnitt des Arbeitskolbens 8, genügt zur Erzielung einer erwünschten schnellen Ventilöffnungsbewegung ein relativ langsamerer Hubverlauf des Geberkolbens 9. Somit kann der Geberkolben 9 leicht und insbesondere kompakt­bauend ausgeführt werden.
Die an jene erste Phase anschließende Phase II stellt einen Übergangsbereich zur Phase III dar, welche ihrer­seits einen abnehmenden Geberkolben-Hub h aufweist. Die Phase II überdeckt dabei auch deshalb einen relativ breiten Nockenwinkelbereich φ*, da jene Phase den üblichen Arbeitsbereich für das Einlaßventil 2 dar­stellt. Erfindungsgemäß wird nämlich inm gesamten Be­triebsbereich der Brennkraftmaschine die Ventilschließ­bewegung durch Betätigung des Schiebers 22 sowie Abfuhr von Hydraulikflüssigkeit in den Speicherraum 20 einge­leitet. Dies hat den Vorteil, daß der Hubverlauf des Geberkolbens 9 in der Phase III unter Berücksichtigung mechanischer Gesichtspunkte ausgelegt werden kann. Mit dieser Nockenkontur kann ein optimaler Befüllvorgang der Druckkammer 30 im Zusammenspiel mit der Gestaltung des Arbeitskolbens 8 sowie des Rückschlagventiles 27 erzielt werden. Da an letzterem unter strömungsdynamischen Gesichtspunkten (Schwingungsverhalten sowie Dampfblasen­bildung) geringe Strömungsgeschwindigkeiten erwünscht sind, können mit einer derart flachen Nockenkontur der Phase II lange Befüllzeiten realisiert werden. Da somit während der Phase II stets eine Absteuerung des Ventil­hubes erfolgt, lassen sich zusätzlich enge Toleranzen insbesondere in Zusammenhang mit der Ansteuerung der Exzenterwelle 26 vermeiden, wenn jene Phase einen relativ breiten Nockenwinkelbereich (φ*) überstreicht.3 shows an exemplary elevation curve of the master piston as a function of the cam angle φ. That curve is divided into three main phases. In the first phase designated I, a maximum elevation Δh per cam angle change Δφ is aimed for. That maximum valve lift increase is determined in particular by the mechanical strength of the cam 10 and the master piston 9. Since, according to the invention, a hydraulic transmission ratio is built into the hydraulic valve opening unit 6, the cross-section of the master piston 9 is therefore larger than the cross-section of the working piston 8, is sufficient to achieve one desired rapid valve opening movement a relatively slower stroke of the master piston 9. Thus, the master piston 9 can be made light and in particular compact.
The phase II following that first phase represents a transition area to phase III, which in turn has a decreasing master piston stroke h. Phase II also covers a relatively wide cam angle range φ * because that phase represents the usual working range for intake valve 2. According to the invention, the valve closing movement is initiated in the entire operating range of the internal combustion engine by actuating the slide 22 and discharging hydraulic fluid into the storage space 20. This has the advantage that the stroke of the master piston 9 can be designed in phase III taking mechanical aspects into account. With this cam contour, an optimal filling process of the pressure chamber 30 can be achieved in interaction with the design of the working piston 8 and the check valve 27. Since low flow velocities are desired in the latter from the point of view of fluid dynamics (vibration behavior and vapor bubble formation), with such a flat cam contour the Phase II long filling times can be realized. Since the valve lift is always deactivated during phase II, narrow tolerances can be avoided in particular in connection with the activation of the eccentric shaft 26 if that phase covers a relatively wide cam angle range (φ *).

Claims (4)

1. Hydraulische Ventilöffnungseinheit im Zylinderkopf einer Brennkraftmaschine mit zumindest einem in Schließrichtung federvorgespannten Einlaßventil und einem Auslaßventil je Zylinder, wobei zur Betäti­gung des Einlaßventiles ein Arbeitskolben vorge­sehen ist, welcher mit einem von einem Nocken betätigten Geberkolben in hydraulischer Verbindung steht und wobei die Achse des Einlaßventiles winkelig zur Achse des Geberkolbens verläuft, dadurch gekennzeichnet, daß die Achse des zwischen dem Einlaßventil (2) und dem winkelig zu diesem angeordneten Auslaßventil (3) liegenden Geber­kolbens (9) versetzt zur Einlaßventilachse ver­läuft.1.Hydraulic valve opening unit in the cylinder head of an internal combustion engine with at least one inlet valve spring-biased in the closing direction and one outlet valve per cylinder, a working piston being provided for actuating the inlet valve, which is hydraulically connected to a master piston actuated by a cam and the axis of the inlet valve being angled runs to the axis of the master piston, characterized in that the axis of the master piston (9) lying between the inlet valve (2) and the outlet valve (3) arranged at an angle thereto is offset to the inlet valve axis. 2. Ventilöffnungseinheit nach Anspruch 1,
dadurch gekennzeichnet, daß der hydraulisch wirk­same Querschnitt des Geberkolbens (9) größer ist als der hydraulisch wirksame Querschnitt des Arbeitskolbens (8).2. Valve opening unit according to claim 1,
characterized in that the hydraulically effective cross section of the master piston (9) is larger than the hydraulically active cross section of the working piston (8). 3. Ventilöffnungseinheit nach Anspruch 1 oder 2,
dadurch gekennzeichnet, daß konzentrisch zum Arbeitskolben (8) eine die Abfuhr von Hydraulik­flüssigkeit drosselnde Bremsvorrichtung (36) zur Beeinflussung der Ventilschließgeschwindigkeit angeordnet ist.3. valve opening unit according to claim 1 or 2,
characterized in that a brake device (36) which restricts the discharge of hydraulic fluid is concentric with the working piston (8) Influencing the valve closing speed is arranged. 4. Ventilöffnungseinheit nach einem der vorangegan­genen Ansprüche,
dadurch gekennzeichnet, daß der durch die Nocken­form gegebene Hubverlauf des Geberkolbens (9) in zumindest drei wesentliche Phasen unterteilt ist, wobei die erste Phase durch die mechanisch maximal zulässige Ventilhubzunahme (Δh) je Nockenwinkel (φ) beschrieben ist, wobei die zweite Phase den Übergangsbereich mit stetig abnehmender Ventilhub­zunahme je Nockenwinkel darstellt und wobei die dritte Phase den Hub in einem derart großen Nocken­winkelbereich (φ**) auf den Nullhub reduziert, daß der Schließvorgang des Einlaßventiles (2) im gesamten Betriebsbereich der Brennkraftmaschine durch Abfuhr von Hydraulikflüssigkeit hervorgerufen wird.4. Valve opening unit according to one of the preceding claims,
characterized in that the cam profile of the master piston (9) is subdivided into at least three essential phases, the first phase being described by the mechanically maximum permissible valve lift increase (Δh) per cam angle (φ), the second phase being the transition range represents with steadily decreasing valve stroke increase per cam angle and the third phase reduces the stroke in such a large cam angle range (φ **) to the zero stroke that the closing process of the intake valve (2) is caused in the entire operating range of the internal combustion engine by removing hydraulic fluid.
EP89104989A 1988-03-24 1989-03-21 Hydraulic valve opening unit in the cylinder-head of an internal combustion engine Expired - Lifetime EP0334272B1 (en)

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DE3809953A DE3809953C1 (en) 1988-03-24 1988-03-24
DE3809953 1988-03-24

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EP0334272B1 EP0334272B1 (en) 1991-07-24

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0507521A1 (en) * 1991-04-04 1992-10-07 Ford Motor Company Limited Hydraulic valve control system for internal combustion engines
EP1674673A1 (en) * 2004-12-23 2006-06-28 C.R.F. Società Consortile per Azioni Internal combustion engine with hydraulic variable valves

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH243908A (en) * 1944-11-27 1946-08-15 Schweizerische Lokomotiv Fluid brake with check valve on the passive piston of hydraulically controlled valves of internal combustion engines.
DE3611476A1 (en) * 1986-04-05 1987-10-08 Irm Antriebstech Gmbh Method for the actuation of valves for exhaust and refill in internal combustion engines with direct hydraulic transmission
DE3621402A1 (en) * 1986-06-26 1988-01-14 Kloeckner Humboldt Deutz Ag Hydraulically actuated tappet
DE3625664A1 (en) * 1986-07-29 1988-02-04 Bayerische Motoren Werke Ag Device for influencing the valve stroke controlled by a cam

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2840445C2 (en) * 1978-09-16 1984-10-04 M.A.N. Maschinenfabrik Augsburg-Nürnberg AG, 8500 Nürnberg Hydraulic device for operating a gas exchange valve for internal combustion engines

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH243908A (en) * 1944-11-27 1946-08-15 Schweizerische Lokomotiv Fluid brake with check valve on the passive piston of hydraulically controlled valves of internal combustion engines.
DE3611476A1 (en) * 1986-04-05 1987-10-08 Irm Antriebstech Gmbh Method for the actuation of valves for exhaust and refill in internal combustion engines with direct hydraulic transmission
DE3621402A1 (en) * 1986-06-26 1988-01-14 Kloeckner Humboldt Deutz Ag Hydraulically actuated tappet
DE3625664A1 (en) * 1986-07-29 1988-02-04 Bayerische Motoren Werke Ag Device for influencing the valve stroke controlled by a cam

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0507521A1 (en) * 1991-04-04 1992-10-07 Ford Motor Company Limited Hydraulic valve control system for internal combustion engines
EP1674673A1 (en) * 2004-12-23 2006-06-28 C.R.F. Società Consortile per Azioni Internal combustion engine with hydraulic variable valves
US7140336B2 (en) 2004-12-23 2006-11-28 C.R.F. Societa Consortile Per Azioni Internal combustion engine with valves with variable actuation which are driven by a single pumping piston and controlled by a single solenoid valve for each engine cylinder

Also Published As

Publication number Publication date
ES2024058B3 (en) 1992-02-16
EP0334272B1 (en) 1991-07-24
DE58900184D1 (en) 1991-08-29
DE3809953C1 (en) 1989-08-24

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