DK174031B1

DK174031B1 - Hydraulically actuated exhaust valve for an internal combustion engine

Info

Publication number: DK174031B1
Application number: DK199700619A
Authority: DK
Inventors: Henning Lindquist; Poul Cenker
Original assignee: Man B & W Diesel As
Priority date: 1997-05-29
Filing date: 1997-05-29
Publication date: 2002-04-29
Also published as: JP2002502475A; JP3763851B2; WO1998057048A1; DK61997A; AU7639498A

Description

DK 174031 B1 iDK 174031 B1 i

Opfindelsen angår en hydraulisk aktiveret udstødsventil til en forbrændingsmotor med en hydraulisk aktuator anbragt koaksialt i forlængelse af udstødsventilens spindel, hvilken aktuator har en stationær 5 cylinder og i det mindste et primært trykkammer, der ved hjælp af en styreventil kan forbindes skiftevis til en højtrykskilde for hydraulikvæske eller til et tilbageløb, samt et aktuatorstempel omfattende i det mindste en første stempeldel og en anden stempeldel.BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a hydraulically actuated exhaust valve for an internal combustion engine with a hydraulically actuated coaxial extension of the spindle of the exhaust valve, which actuator has a stationary cylinder and at least one primary pressure chamber which or for a return, as well as an actuator piston comprising at least a first piston part and a second piston part.

10 Fra DK-B 154165 kendes en sådan udstødsventil, der udover et primært trykkammer også har et sekundært trykkammer. Aktuatorstemplet er todelt for at de to dele kan udføre en meget begrænset indbyrdes bevægelse ved starten af vent il åbningen. I hovedparten af ud-15 stødsventilens åbningsbevægelse forskydes de to stempeldele i en fælles bevægelse. Afskæringskanter i den stationære cylinder styrer stemplernes start- og slutstillinger. I løbet af åbningsbevægelsen afskærer den ene af stempeldelene det ene af trykkamrene fra 20 højtrykskilden, så højtrykket kun er virksomt i det andet kammer. Stempellængderne og afstandene mellem afskæringskanterne i den stationære cylinder er faste, hvilket betyder, at aktuatoren kun passer til en bestemt længde på ventilspindlen.From DK-B 154165 such an exhaust valve is known which, in addition to a primary pressure chamber, also has a secondary pressure chamber. The actuator piston is two-piece so that the two parts can perform a very limited mutual movement at the start of the vent opening. In the majority of the opening movement of the outflow valve, the two piston parts are displaced in a common movement. Cutting edges of the stationary cylinder control the start and end positions of the pistons. During the opening movement, one of the piston parts cuts off one of the pressure chambers from the 20 high pressure source, so that the high pressure is only effective in the other chamber. The piston lengths and distances between the cut-off edges of the stationary cylinder are fixed, which means that the actuator fits only a certain length of the valve spindle.

25 Fra DE-A 2151331 kendes en elektronisk styret og hydraulisk aktiveret ventilaktuator til en udstødsventil i en reverserbar skibsmotor. Den elektroniske styring er baseret på en kamaktivering af en elektrisk signalgiver, der aktiverer styreventilen. Der er kun et 30 aktuatorstempel, der gennem en stødstang ligger an mod oversiden af ventilspindlen. Stødstangen er forsynet med en radialt udragende krave, der ved afslutningen af både åbne- og lukkebevægelserne passerer ind i et dæmperkammer beliggende i den stationære aktuator-35 cylinder. Stødstangen har fast længde, og aktuator- 2 DK 174031 B1 stemplet passer dermed kun til en bestemt længde af ventiIspindlen.25 DE-A 2151331 discloses an electronically controlled and hydraulically actuated valve actuator for an exhaust valve in a reversible ship engine. The electronic control is based on a comb activation of an electrical signal encoder activating the control valve. There is only one 30 actuator piston which, through a thrust bar, abuts the upper side of the valve stem. The thrust bar is provided with a radially projecting collar which, at the end of both the opening and closing movements, passes into a damper chamber located in the stationary actuator cylinder. The thrust bar has a fixed length, and the actuator piston therefore only fits a certain length of the valve stem.

Fra US-A 3 209 737 kendes en hydraulisk aktiveret udstødsventil, hvor aktuatorstemplet er todelt i en 5 første stempeldel med stor diameter, der omgiver en anden stempeldel, som er udført i et stykke med ventilspindlen. Den anden stempeldel har en opstående tap, der ved afslutningen af lukkebevægelsen passerer op i et dæmperkammer, hvorved ventilens lukkebevægelse 10 bremses. Efter en indledende åbningsbevægelse træffer den første stempeldel et stop, hvorefter højtrykket i aktuatorens trykkammer kun kan bevæge den anden stempeldel. Da det andet stempel er fast forbundet med ventilspindlen, passer aktuatoren kun på en ventilspin-15 del med en bestemt længde.From US-A-3 209 737 a hydraulically actuated exhaust valve is known in which the actuator piston is divided into a first large diameter piston part which surrounds a second piston part which is integral with the valve spindle. The second piston member has an upright pin which, at the end of the closing movement, passes into a damper chamber, thereby slowing the closing movement of the valve 10. After an initial opening movement, the first piston part stops, after which the high pressure in the actuator pressure chamber can only move the second piston part. Since the second piston is firmly connected to the valve spindle, the actuator fits only on a valve spindle part of a certain length.

Det er energimæssigt fordelagtigt at anvende en aktuator med to stempler, hvoraf det ene standses efter en indledende åbningsbevægelse, fordi forbruget af højtryks hydraulikvæske derved mindskes i løbet af den 20 resterende del af åbningsbevægelsen.It is economically advantageous to use an actuator with two pistons, one of which is stopped after an initial opening movement because the consumption of high pressure hydraulic fluid is thereby reduced during the remaining part of the opening movement.

Ved driften af motoren kan der forekomme en delvis nedbrydning af ventilens sædeflader som følge af korrosive angreb forårsaget af de aggessive forbrændingsprodukter. Hvis nedbrydningen medfører større 25 lokale utætheder i sædefladerne, er det nødvendigt at foretage en slibning af sædefladerne, hvilket medfører, at toppen af ventilspindlen kommer til at ligge højere oppe, når ventilen er lukket, fordi de to sædeflader har mindre tykkelse efter slibningen. Ved store totakts 30 dieselmotorer, der typisk anvendes som fremdrivnings-motorer i skibe, er dimensionerne af udstødsventilen så store, at der kan forekomme mærkbare længdeændringer af ventilspindlen fra den kolde starttilstand til den varme driftstilstand. Disse uundgåelige længdeændringer 35 medfører, at de kendte ventilaktuatorer giver betydelig DK 174031 B1 3 risiko for uønsket hårde venti1lukninger, navnlig ved udstødsventiler, der har været længe i drift.During operation of the engine, partial breakdown of the valve seat surfaces may occur due to corrosive attacks caused by the aggessive combustion products. If the degradation causes greater local leakage in the seat surfaces, it is necessary to grind the seat surfaces, which causes the top of the valve stem to lie higher when the valve is closed, because the two seat surfaces have less thickness after grinding. For large two-stroke diesel engines typically used as propulsion engines in ships, the dimensions of the exhaust valve are so large that noticeable length changes of the valve stem from the cold start state to the hot operating state can occur. These unavoidable length changes 35 cause the known valve actuators to present a considerable risk of unwanted hard valve closures, especially for exhaust valves which have been in operation for a long time.

Den foreliggende opfindelse har til formål at anvise en hydraulisk aktiveret udstødsventil, der så 5 vidt muligt giver ensartet gode og repeterbare ventil-bevægelser.The present invention has for its object to provide a hydraulically actuated exhaust valve which provides uniformly good and repeatable valve movements as far as possible.

Med henblik herpå er udstødsventilen ifølge opfindelsen ejendommelig ved, at et første anslag på. den stationære cylinder fastlægger en udgangsstilling 10 for den første stempeldel, at et positioneringsstempel og en positioneringscylinder i en positioneringsenhed afgrænser et væskekammer, der er forbundet med det primære trykkammer via en kanal, der er lukket, når udstødsventilen står åben, og står åben, når udstødsven-15 tilen er lukket, at spillerum mellem vent i Ispindlen og aktuatorstemplet er udlignet ved at positionerings-stemplets effektive areal i positioneringscylinderen er større end aktuatorstemplets effektive areal i det primære trykkammer og/eller at en mekanisk trykfjeder 20 i væskekammeret holder positioneringsenhedens cylinder og stempel i anlæg mod aktuatorstemplet og spindlen, og at positioneringsenheden står i kraftoverførende forbindelse med aktuatorstemplet og udstødsventilens spindel, når udstødsventilen er lukket.To this end, the exhaust valve according to the invention is characterized by a first stop of. the stationary cylinder defines an initial position 10 of the first piston member that a positioning piston and positioning cylinder in a positioning unit define a liquid chamber connected to the primary pressure chamber through a duct closed when the exhaust valve is open and open when the exhaust valve is closed so that clearance between vent in the shaft and actuator piston is offset by the effective area of the positioning piston in the positioning cylinder being greater than the effective area of the actuating piston in the primary pressure chamber and / or a mechanical pressure spring 20 in the liquid chamber holding the positioning unit cylinder and piston in abutment against the actuator piston and spindle, and that the positioning unit is in power transmission with the actuator piston and the exhaust valve spindle when the exhaust valve is closed.

25 Væskekammeret i positioneringsenheden er aktivt, når udstødsventilen er lukket, og kanalen står åben for at trykket i det primære trykkammer forplanter sig ned i væskekammeret. Som følge af trykket og eventuelt en mekanisk trykfjeder i væskekammeret påvirker positio-30 neringsenheden den første stempeldel med en opadrettet kraft, der er større end den nedadrettede kraft på aktuatorstemplet, frembragt af væsketrykket i det primære trykkammer. Den opadrettede kraft presser den første stempeldel opad, indtil den ligger an mod det 35 første anslag. Dette giver aktuatorstemplet en vel- 4 DK 174031 B1 defineret og repeterbar udgangsstilling, der er uafhængig af ventilskaftets position i ventilens lukkede stilling.The liquid chamber in the positioning unit is active when the exhaust valve is closed and the duct is open for the pressure in the primary pressure chamber to propagate down into the liquid chamber. Due to the pressure and optionally a mechanical pressure spring in the liquid chamber, the positioning unit affects the first piston part with an upward force greater than the downward force on the actuator piston generated by the liquid pressure in the primary pressure chamber. The upward force pushes the first piston part upwards until it is in contact with the first stop. This gives the actuator piston a well-defined and repeatable starting position independent of the position of the valve stem in the closed position of the valve.

Positioneringsenheden påvirker samtidig ventil-5 spindlen med en lige så stor nedadrettet kraft, hvorved et eventuelt spillerum mellem ventilspindlen og aktua-torstemplet udlignes, ved at positioneringsstemplet skubbes lidt væk fra den indre bund i positioneringscylinderen, samtidig med at væskekammeret efterfødes 10 med hydraulikvæske fra det primære trykkammer.The positioning unit simultaneously influences the valve spindle with an equally downward force, thereby compensating for any clearance between the valve spindle and the actuator piston by pushing the positioning piston slightly away from the inner bottom of the positioning cylinder, while also re-feeding the liquid chamber 10 with hydraulic fluid from it. primary pressure chamber.

Positioneringsenheden kompenserer således automatisk for ændringer i udstødsventilens længde, så de ovennævnte problemer forårsaget af slid og temperaturændringer er helt undgået. Samtidig opnås den væsent-15 lige fremstillingsmæssige fordel, at alle de dele, der indgår i udstødsventilen, dennes hus og de oveniiggende husdele til og med aktuatorens stationære cylinder ikke behøver at blive fremstillet med specielt fine tolerancer, som det hidtil har været krævet for at opnå 20 korrekt funktion af udstødsventiler.The positioning unit thus automatically compensates for changes in the length of the exhaust valve, so that the aforementioned problems caused by wear and temperature changes are completely avoided. At the same time, the essential manufacturing advantage is obtained that all the parts included in the exhaust valve, its housing and the overlying housing parts up to and including the actuator's stationary cylinder need not be manufactured with particularly fine tolerances as hitherto required to achieve 20 proper functioning of exhaust valves.

Når trykket i det primære trykkammer efter styre-ventilens tilslutning af højtrykskilden vokser, og ventilåbningen initieres, lukkes forbindelsen mellem væskekammeret og det primære trykkammer, og væskemæng-25 den i væskekammeret spærres inde, så positionerings-enheden fikseres i en fast længde i løbet af udstødsventilens åbne periode. Når styreventilen efterfølgende forbinder det primære trykkammer med tilbageløbet, og udstødsventilen lukkes, åbner kanalen igen for væske-30 strømning fra det primære trykkammer til væskekammeret.As the pressure in the primary pressure chamber after the control valve's connection to the high pressure source increases and the valve opening is initiated, the connection between the fluid chamber and the primary pressure chamber is closed and the amount of fluid in the fluid chamber is blocked so that the positioning unit is fixed for a fixed length over time. the exhaust valve open period. When the control valve subsequently connects the primary pressure chamber to the reflux and the exhaust valve is closed, the duct opens again for fluid flow from the primary pressure chamber to the liquid chamber.

Det er muligt at placere positioneringsenheden på ethvert sted i kraftoverførelsesbanen mellem den første stempeldel og ventilspindlen, men det foretrækkes at placere den ene del af enheden oven på ventilspindlen 3 5 for derved at opnå en enkel udformning af aktuator- 5 DK 174031 B1 stemplet. Det er særlig fordelagtigt at placere positioneringscylinderen på toppen af spindlen, og at anbringe positioneringsstemplet på en af aktuatorens stempeldele, fordi positioneringscylinderen dermed er 5 orienteret som en opad åben kop. Positioneringscylinderen kan placeres, så der er mulighed for indbyrdes radial bevægelse mellem spindlen og aktuatorcylinderen.It is possible to place the positioning unit at any location in the transmission path between the first piston part and the valve spindle, but it is preferable to place one part of the unit on top of the valve spindle 35 so as to obtain a simple design of the actuator piston. It is particularly advantageous to place the positioning cylinder on the top of the spindle and to place the positioning piston on one of the actuator piston parts because the positioning cylinder is thus oriented as an upwardly open cup. The positioning cylinder can be positioned to allow for radial movement between the spindle and the actuator cylinder.

For at mindske antallet af separate dele kan positioneringsstemplet være udformet i ét stykke med aktuator-10 stemplet, men det er klart, at det alternativt kan være en separat enhed, der trykker op mod aktuatorstemplet og er delvis beliggende i et radialtvirkende styr.To reduce the number of separate parts, the positioning piston may be integrally formed with the actuator piston, but it is clear that it may alternatively be a separate unit pushing up against the actuator piston and partially located in a radially acting guide.

I en foretrukken udførelsesform er der til spindlen fikseret en opstående sidevæg med skrå yderside med 15 en tilhørende sensor, der ved bevægelse af spindlen afgiver signaler til en elektronisk styreenhed, der aktiverer styreventilen for den hydrauliske aktuator.In a preferred embodiment, an upright inclined exterior sidewall with an associated sensor is fixed to the spindle which, when moving the spindle, gives signals to an electronic control unit activating the hydraulic actuator control valve.

Den forbedrede ensartethed i ventilbevægelserne, som opnås med ovennævnte positioneringsenhed, kan yderii-20 gere forstærkes med sensoren, der detekterer det præcise tidspunkt for ventilbevægelsens igangsætning og giver styreenheden besked herom, så der løbende kan kompenseres for variationer i det ønskede og det faktiske tidspunkt for ventilens åbning.The improved uniformity of the valve movements achieved with the above positioning unit can be further enhanced by the sensor which detects the precise time of the valve movement and informs the control unit so that variations in the desired and actual time can be continuously compensated. valve opening.

25 I en udførelsesform er positioneringsstemplets effektive areal, dvs. det areal, der er aktivt udsat for trykket i væskekammeret, større end aktuatorstem-plets effektive areal, der er påvirket af trykket i det primære trykkammer, og kanalen indeholder en trykstyret 30 kontraventil. Med denne udformning kan undgås anvendelsen af en trykfjeder inde i positioneringsenhedens væskekammer. Når trykket i det primære trykkammer er større end et forudbestemt tryk, er kontraventilen lukket. Kontraventilen kan være af typen med en fjeder-35 belastet kugle, eller en ventilglider.In one embodiment, the effective area of the positioning piston, i.e. the area actively exposed to the pressure in the liquid chamber is greater than the effective area of the actuator piston which is affected by the pressure in the primary pressure chamber and the duct contains a pressure controlled check valve. With this design, the use of a compression spring within the fluid chamber of the positioning unit can be avoided. When the pressure in the primary pressure chamber is greater than a predetermined pressure, the non-return valve is closed. The check valve can be of the type with a spring-loaded ball or a valve slide.

6 DK 174031 B16 DK 174031 B1

Det er ønskeligt, at de to stempeldele er indbyrdes bevægelige og har forskellige vandringslængder for derved at opnå den i og for sig kendte fordel, at den første stempeldel kun giver et forbrug af hydrau-5 likvæske i den indledende del af udstødsventilens åbningsbevægelse, hvor der kræves stor åbnekraft for overvindelse af forbrændingskammerets opadrettede trykkraft på undersiden af ventiltallerkenen. Dette er i en foretrukken udførelsesform opnået derved, at den 10 første stempeldel har en ringformet væg, hvis yderside er længdeforskydeligt styret i en cylinderboring i den stationære cylinder, og hvis inderside udgør styreflade for i det mindste den anden stempeldel, at den første stempeldel har en radialt udragende krave, der er 15 beliggende i et ringformet kammer, hvis længde er mindre end længden af udstødsventilens vandring fra lukket til fuldt åben stilling, og hvis kammerloft udgør det første anslag, der fastlægger den første stempeldels udgangsstilling, at den anden stempeldel 20 står i forbindelse med positioneringsenheden, og at den nedre ende af den første stempeldel ligger oven over en opadvendende flade på positioneringsenheden. Problemet ved en sådan aktuator med flerdelt stempel er at sikre tilbageføringen af stempeldelene til eksakt den samme 25 udgangsstilling uafhængig af udstødsventilens aktuelle driftsforhold og slidtilstand. Hvis tilbageføringen ikke er helt præcis, er det nødvendigt at udføre aktuatorstemplet med en ekstra vandringslængde for at sikre fuld ventilåbning i det tilfælde, at ventilåb-30 ningen starter på et tidspunkt, hvor en af stempeldelene ikke er helt i topstillingen. En sådan ekstra vandringslængde medfører et uhensigtsmæssigt stort forbrug af hydraulikvæske og for stor energitilførsel til udstødsventilen, når stempeldelene faktisk starter 35 fra topstillingen. Disse problemer er helt undgået ved 7 DK 174031 B1 hjælp af positioneringsenheden. Når udstødsventilen er ført tilbage til lukket stilling, og kontraventilen er åbnet, presser trykket i væskekammeret den opadvendende flade på positioneringsenheden op til anlæg mod den 5 nedre ende af den første stempeldel, hvorved den anden stempeldel er positioneret præcist i sin udgangsstilling, og den opadrettede kraft på den første stempeldel presser denne op til anlæg mod det første anslag, hvorved også den første stempeldel er positioneret 10 præcist i sin udgangsstilling. Stempeldelene kan i· .* følgelig udformes med netop de vandringslængder, der på den aktuelle motor giver udstødsventilen det mest fordelagtige åbningsforløb.It is desirable that the two piston parts be mutually movable and have different lengths of travel so as to obtain the per se known advantage that the first piston part provides only a consumption of hydraulic fluid in the initial portion of the opening movement of the exhaust valve, where high open force is required to overcome the upward pressure of the combustion chamber on the underside of the valve plate. This is achieved in a preferred embodiment in that the first piston part has an annular wall, the outside of which is longitudinally displaceable in a cylinder bore in the stationary cylinder, and the inside of which forms a guide surface for at least the second piston part, that the first piston part has a radially projecting collar located in an annular chamber the length of which is less than the length of the outlet valve passage from closed to fully open position, and whose chamber ceiling constitutes the first stop defining the initial position of the first piston part, communicates with the positioning unit and that the lower end of the first piston portion is above an upwardly facing surface of the positioning unit. The problem with such a multi-part piston actuator is to ensure the return of the piston parts to exactly the same starting position, regardless of the exhaust valve's current operating conditions and wear condition. If the return is not entirely accurate, it is necessary to perform the actuator piston with an additional travel length to ensure full valve opening in the event that the valve opening starts at a time when one of the piston parts is not fully in the top position. Such extra travel length results in an unduly large consumption of hydraulic fluid and excessive energy supply to the exhaust valve when the piston parts actually start 35 from the top position. These problems are completely avoided by the positioning unit. When the exhaust valve is returned to the closed position and the non-return valve is opened, the pressure in the liquid chamber presses the upwardly facing surface of the positioning unit up to abut the lower end of the first piston part, whereby the second piston part is precisely positioned in its initial position and the upwards force on the first piston part pushes it up against the first stop, whereby also the first piston part is positioned 10 precisely in its initial position. Accordingly, the piston parts can be formed with precisely the lengths of travel which provide the most advantageous opening for the exhaust valve on the current motor.

I en videreudvikling af udførelsesformen er den 15 anden stempeldel beliggende centralt i aktuatoren og har en øvre stempel top og et langsgående skaft, der forbinder positioneringsenheden med stempeltoppen.In a further development of the embodiment, the second piston member is centrally located in the actuator and has an upper piston top and a longitudinal shaft connecting the positioning unit to the piston top.

Denne udførelsesform er fremstillingsmæssigt fordelagtig enkel, idet positioneringsenhedens stempel eller 20 cylinder er udført i et stykke med den anden stempel-del, og indebærer, at den anden stempeldel udgør det sidste aktive stempeltrin i åbningsbevægelsen. Alternativt er det muligt at udføre den anden stempeldel som et ringstempel ligesom den første stempeldel.This embodiment is advantageously simple in manufacture, in that the piston or cylinder of the positioning unit is integral with the second piston part, and implies that the second piston part constitutes the last active piston step in the opening movement. Alternatively, it is possible to perform the second piston part as a ring piston just like the first piston part.

25 Energiforbruget til åbning af udstødsventilen er fordelagtigt lille i en yderligere udførelsesform, der er således udformet, at skaftet har et recessafsnit med større aksial længde end kammeret med det første anslag og med mindre diameter end det skaftafsnit, der er 30 styret af den første stempeldels inderside, at en ringformet, tredie stempeldel rager ind i recessafsnittet og rager ud i en cylindrisk recess i den første stempeldels inderside, og at den tredie stempeldels overside står i forbindelse med det primære trykkammer, 35 når udstødsventilen er lukket. Den tredie stempeldel er 8 DK 174031 B1 styret af recessafsnittene på de to andre stempeldele og ligger optaget mellem disse. Den tredie stempeldel har større vandringslængde end den første stempeldel og mindre vandringslængde end den anden stempeldel og 5 udgør således det andet trin i den tretrins ventilaktu-ator. I løbet af åbningsbevægelsen standses den tredie stempeldel ved anlæg mod bunden af recessafsnittet i den første stempeldels inderside. Ved lukkebevægelsen gribes undersiden af det tredie stempeltrin af bunden 10 af recessafsnittet på skaftet og føres samtidig med den .. i anden stempeldel tilbage til sin veldefinerede udgangsstilling .The energy consumption for opening the exhaust valve is advantageously small in a further embodiment, which is designed such that the shaft has a recess section of greater axial length than the chamber with the first stop and smaller diameter than the shaft section controlled by the first piston part. on the inside, that an annular third piston member projects into the recess section and protrudes into a cylindrical recess on the inside of the first piston member, and that the upper face of the third piston member communicates with the primary pressure chamber when the exhaust valve is closed. The third piston part is 8 DK 174031 B1 controlled by the recess sections of the other two piston parts and is occupied between them. The third piston part has a greater travel length than the first piston part and less travel length than the second piston part and thus constitutes the second stage of the three-stage valve actuator. During the opening movement, the third piston part is stopped by abutment towards the bottom of the recess section on the inside of the first piston part. In the closing movement, the underside of the third piston stage is gripped by the bottom 10 of the recess section of the shaft and, simultaneously with the second piston part, is returned to its well-defined starting position.

Det foretrækkes, at hastigheden i den opadgående lukkebevægelse af ventilspindlen mindskes, inden 15 spindlens sædeområde lander på sædeområdet på den stationære ventilpart. Dette kan hensigtsmæssigt opnås ved at udforme aktuatoren således, at den første stempeldel mellem sin overside og den udragende krave har en radialt udadvendende kammervæg med mindre aksial 2 0 længde end længden af det ringformede kammer, og at kammervæggen sammen med den udragende krave og et øverste vægafsnit i det ringformede kammer sammen med kammerloftet danner et første dæmperkammer, når den første stempeldel nærmer sig det første anslag. Pla-25 ceringen af den udragende krave i en afstand fra oversiden af den første stempeldel, der er mindre end den aksiale længde af det ringformede kammer, giver den fordel, at den første stempeldel i den første del af returbevægelsen op mod udgangsstillingen er frit be-30 vægelig, fordi det ringformede kammer over den udragende krave er fuldt åbent ud til det primære trykkammer. I den sidste del af stempelbevægelsen passerer stemplets kammervæg op forbi loftet i det ringformede kammer, så der mellem kammervæggen og indersiden af den 35 stationære cylinder fremkommer en ringformet spalte, 9 DK 174031 B1 hvorigennem væske i dæmperkammeret skal udpresses.It is preferred that the speed of the upward closing movement of the valve spindle is reduced before the seat region of the spindle lands on the seat region of the stationary valve member. This may conveniently be achieved by designing the actuator such that the first piston portion between its upper side and the protruding collar has a radially outwardly extending chamber wall of less axial length than the length of the annular chamber, and that the chamber wall together with the protruding collar and a top wall sections of the annular chamber together with the chamber ceiling form a first damper chamber as the first piston member approaches the first stop. The placement of the protruding collar at a distance from the upper side of the first piston part smaller than the axial length of the annular chamber gives the advantage that the first piston part in the first part of the return movement towards the initial position is freely supported. -30, because the annular chamber above the protruding collar is fully open to the primary pressure chamber. In the latter part of the piston movement, the chamber wall of the piston passes up past the ceiling of the annular chamber, so that an annular gap is formed between the chamber wall and the inside of the stationary cylinder, through which liquid in the damper chamber is pressed.

Dette får trykket i dæmperkammeret til at stige væsentligt op over trykket i det primære trykkammer, hvorved oversiden af den udragende krave påføres en nedadrettet 5 kraft, som bremser ventilspindlen.This causes the pressure in the damper chamber to rise substantially above the pressure in the primary pressure chamber, thereby applying a downwardly directed force to the upper side of the protruding collar which slows the valve stem.

Det foretrækkes, at i det mindste den øverste del af kammervæggen på den første stempeldel har nedefter voksende diameter. En sådan skrå afskæring af den fra den udragende krave opstående kammervæg medfører, at 10 bredden af den ringformede spalte mellem kammervæggen og kanten af kammerloftet bliver mindre, efterhånden som den første stempeldel nærmer sig udgangsstillingen.It is preferred that at least the upper portion of the chamber wall of the first piston portion has downwardly increasing diameter. Such an oblique cut of the chamber wall raised from the protruding collar causes the width of the annular gap between the chamber wall and the edge of the chamber ceiling to decrease as the first piston part approaches the initial position.

Derved undgås en slagagtig påvirkning på den første stempeldel, når dæmpningen træder i funktion, og 15 dæmpningen afpasses samtidig efter udstødsventilens hastighed og masse.This prevents a shock-like effect on the first piston part when the damping takes effect, and the damping is simultaneously adjusted according to the speed and mass of the exhaust valve.

En fordelagtig videreudvikling er således udformet, at der i den stationære cylinder er et antal kanaler, der forbinder det primære trykkammer med 20 udløbsåbninger beliggende i kammerloftet, og at en under udløbsåbningerne beliggende flad ring er aksialt forskydelig mellem en øvre stilling, hvor ringen dækker udløbsåbningerne, og en nedre stilling, hvor ringen ligger i afstand fra udløbsåbningerne. Det er ganske 25 vist muligt at give den ovennævnte ringformede spalte såpas stor bredde, at hydraulikvæsken kan stømme passende hurtigt ind i dæmperkammeret ved åbningen af ventilen, men dette begrænser den opnåelige dæmpervirkning ved ventillukningen. Det foretrækkes derfor, at 3 0 der ved hjælp af kanalerne og den flade ring frembringes en kontraventil, der tillader fri indstrømning af væske fra det primære trykkammer, når ventilen skal åbne, men afspærrer forbindelsen til det primære trykkammer, når dæmperkammeret er aktivt ved ventilluk-35 ningen. Kontraventilen giver samtidig den fordel, at 10 DK 174031 B1 det fulde aktiveringstryk på aktuatorstemplet vedvarende overføres til ventilspindlen, når denne sættes i bevægelse.An advantageous further development is such that in the stationary cylinder there are a plurality of ducts connecting the primary pressure chamber with 20 outlet openings located in the chamber ceiling and that a flat ring located below the outlet openings is axially displaceable between an upper position where the ring covers the outlet openings. , and a lower position where the ring is spaced from the outlet openings. While it is possible to give the aforementioned annular gap such a wide width that the hydraulic fluid can flow suitably into the damper chamber at the opening of the valve, but this limits the attainable damper effect on the valve closure. It is therefore preferred that, by means of the channels and the flat ring, a check valve be provided which allows free flow of liquid from the primary pressure chamber when the valve is to open, but shuts off the connection to the primary pressure chamber when the damper chamber is active at valve closure. -35 things. At the same time, the check valve provides the advantage that the full actuating pressure on the actuator piston is continuously transmitted to the valve stem when it is moved.

Udstødsventilen kan være hydraulisk tilbageført 5 til lukket stilling ved hjælp af et opadvirkende aktuatorstempel. Udstødsventilen kan i stedet være fjederbelastet i lukkeretningen, eksempelvis ved hjælp af en pneumatisk fjeder. Fjederen påvirker vedvarende udstødsventilen med en opadrettet lukkekraft, hvis 10 størrelse kan være voksende i løbet af ventilens nedadgående bevægelse. Denne kraft afbremser udstødsventilen til standsning i den fuldt åbne stilling.The exhaust valve may be hydraulically returned to the closed position by an upward actuating piston. The exhaust valve may instead be spring loaded in the closing direction, for example by means of a pneumatic spring. The spring continuously affects the exhaust valve with an upward closing force, the size of which 10 may be increasing during the downward movement of the valve. This force slows the exhaust valve to stop in the fully open position.

For at opnå en passende samvirkning mellem den pneumatiske fjeder og aktuatoren i den sidste del af åbnings-15 bevægelsen foretrækkes, at et andet anslag begrænser den anden stempeldels nedadgående bevægelse, at den anden stempeldel nær sin stempeltop har et rundtgående, radialt fremspring, der inden den anden stempeldel når ned til det andet anslag passerer ned i et dæmperafsnit 2 0 på den første stempeldel, og at i det mindste den øverste del af dæmperafsnittet på indersiden af den første stempeldel har nedefter aftagende diameter. Når det radiale fremspring på stempeltoppen i sin nedadgående bevægelse når frem til dæmperafsnittet, frem-25 kommer der mellem stempeltoppen og indersiden af den første stempeldel en ringformet spalte, hvorigennem den under stempeltoppen værende væske skal udpresses, inden den anden stempeldel lander på det andet anslag.In order to achieve a suitable interaction between the pneumatic spring and the actuator in the latter part of the opening movement, it is preferred that a second stop restricts the downward movement of the second piston part, that the second piston part has a circumferential radial projection near its piston top. the second piston member reaches down to the second stop passing down an attenuator portion 20 on the first piston member, and that at least the upper portion of the damper portion on the inside of the first piston member has downward decreasing diameter. As the radial protrusion of the piston top in its downward movement reaches the damper section, an annular gap is formed between the piston top and the inside of the first piston part, through which the liquid under the piston top must be pressed out before the second piston part lands on the second stop. .

Samtidig med udpresningen stiger væsketrykket på 30 stempeltoppens underside, hvilket frembringer en opadrettet kraft på den anden stempeldel, så dennes hastighed aftager, og den nedadrettede åbnekraft på ventil spindlen mindskes. Det skrå forløb af dæmperafsnittets øverste del medfører et gradvist stigende 35 væsketryk under stempeltoppen og dermed en gradvis 11 DK 174031 B1 aftagen af åbnekraften, hvilket giver den pneumatiske fjeder tid til at afbremse udstødsventilen i takt med den aftagende åbnekraft, så toppen af spindlen ikke slipper undersiden af positioneringsenheden.At the same time as the pressing, the liquid pressure on the underside of the piston top increases, which produces an upward force on the second piston part so that its speed decreases and the downward opening force on the valve spindle is reduced. The oblique course of the upper part of the damper section causes a gradually increasing liquid pressure under the piston top and consequently a gradual decrease in the opening force, which gives the pneumatic spring time to slow the exhaust valve in line with the decreasing opening force, so that the top of the spindle does not release. the underside of the positioning unit.

5 En udførelsesform, der tager sigte på at give den tredie stempeldel et helt entydigt og repeterbart bevægeIsesforløb ved ventillukningen, er således udformet, at den anden stempeldels recessafsnit er afsluttet opadtil i en aksialvendende flade, at der i 10 den anden stempeldels øvre ende er et antal kanaler, der forbinder det primære trykkammer med udløbsåbninger beliggende i den aksialvendende flade, og at en under udløbsåbningerne beliggende flad ring er aksialt forskydelig mellem en øvre stilling, hvor ringen dækker 15 udløbsåbningerne, og en nedre stilling, hvor ringen ligger i afstand fra udløbsåbningerne. Denne kontraventil ved toppen af den anden stempeldels recessafsnit bevirker, at den tredie stempeldel ved aktuator-stemplets returbevægelse efterlades ved bunden af 20 recessafsnittet på den første stempeldel, indtil bunden af recessafsnittet på den anden stempeldel griber fat i undersiden af den tredie stempeldel og trækker denne med op til udgangsstillingen.An embodiment which aims to give the third piston part a completely unambiguous and repeatable course of movement at the valve closure, is designed such that the recess section of the second piston part is closed upwardly in an axially facing surface that at the upper end of the second piston part there is a a plurality of channels connecting the primary pressure chamber with outlet openings located in the axially facing surface and a flat ring located below the outlet openings being axially displaceable between an upper position where the ring covers the outlet openings and a lower position where the ring is spaced from the outlet openings . This check valve at the top of the recess section of the second plunger causes the third plunger part to be left at the bottom of the recess section of the actuator plunger at the bottom of the first plunger section until the bottom of the recess section of the second plunger section grips the underside of the third plunger section. with up to the starting position.

Eksempler på udførelsesformer ifølge opfindelsen 25 forklares herefter nærmere med henvisning til den skematiske tegning, hvorpå fig. 1 viser en skitse af en cylinder i en totakts krydshovedmotor, med et cylinderdæksel vist i tværsnit, fig. 2 et længdesnit gennem en første udførelses-30 form for en aktuator til en udstødsventil i cylinderen i fig. 1, fig. 3 i større skala en første udførelsesform for en kontraventil, fig. 4 et forstørret udsnit af vægdele i en første 35 og en anden stempeldel i aktuatoren i fig. 2, 12 DK 174031 B1 fig. 5 i delvist længdesnit gennem en anden udførelsesform for aktuatoren, fig. 6 et forstørret længdesnit gennem den øverste del af den anden stempeldel i aktuatoren i fig. 5, og 5 fig. 7 et diagram til anskueliggørelse af energi forbruget anvendt til åbning af udstødsventilen.Examples of embodiments according to the invention are explained in greater detail with reference to the schematic drawing, in which fig. 1 shows a sketch of a cylinder in a two-stroke cross-head motor, with a cylinder cover shown in cross section; FIG. 2 is a longitudinal section through a first embodiment of an actuator for an exhaust valve in the cylinder of FIG. 1, FIG. 3 shows on a larger scale a first embodiment of a non-return valve; FIG. 4 is an enlarged section of wall portions of a first 35 and a second piston portion of the actuator of FIG. 2, 12 DK 174031 B1 fig. 5 is a partial longitudinal section through another embodiment of the actuator; FIG. 6 is an enlarged longitudinal section through the upper portion of the second piston portion of the actuator of FIG. 5 and 5 in FIG. 7 is a diagram showing the energy consumption used to open the exhaust valve.

I fig. 1 ses en cylinder 1, der er af længdeskyl-let type og har skylleluftporte 2, der er beliggende i en luftkasse 3, som fra en ikke vist skylleluf treceiver 10 forsynes med skylleluft, der er tryksat, eksempelvis af en turbolader.In FIG. 1, there is seen a cylinder 1 which is of longitudinally flushing type and has flushing air ports 2 located in an air box 3 which is provided with a flushing air, which is pressurized, for example from a turbocharger, not shown.

En udstødsventil 4 er monteret centralt i toppen af cylinderen i et cylinderdæksel 24' , Ved afslutningen af ekspansionsslaget åbner udstødsventilen, inden et 15 motorstempel 5 passerer ned forbi skylleluftportene, hvorved forbrændingsgasserne i et forbrændingskammer 6 over stemplet strømmer ud gennem en udstødspassage 7, der udmunder i en udstødsreceiver 8. Udstødsventilen lukker igen under stemplets opadgående bevægelse på et 20 indstilleligt tidspunkt, der kan afhænge af det ønskede effektive kompressionsforhold for den efterfølgende forbrænding. Under lukkebevægeleen drives udstødsventilen opad af en pneumatisk fjeder 23.An exhaust valve 4 is mounted centrally at the top of the cylinder in a cylinder cover 24 '. At the end of the expansion stroke, the exhaust valve opens before a motor piston 5 passes down past the purge air ports, whereby the combustion gases in a combustion chamber 6 flow out through an exhaust gas 7 through in an exhaust receiver 8. The exhaust valve closes again during the upward movement of the piston at an adjustable time which may depend on the desired effective compression ratio for the subsequent combustion. Under the closing movement, the exhaust valve is driven upwards by a pneumatic spring 23.

Af hensyn til ventilens holdbarhed og til en 25 fordelagtig nøjagtig styring af forholdene i forbrændingskammeret og dermed af motorens virkningsgrad kan udstødsventilen med fordel styres meget præcist. Udstødsventilen åbnes ved hjælp af en aktuator 9, der er hydraulisk drevet. Hydraulikvæsken leveres gennem en 30 trykledning 10, der forbinder en væsketilgang og -afgang 11 på aktuatoren med en styreport på oversiden af en fordelerblok 12, der er båret af en konsol 13. Konsollen er tilsluttet en høj tryksledning 14 for hydraulikvæske, der fra en ikke vist pumpestation 35 forsynes med hydraulikvæske ved et tryk, der eksempel- 13 DK 174031 B1 vis kan være beliggende i intervallet fra 125 til 325 bar. Trykket kan være fast, men er fortrinsvis regulerbart i afhængighed af motorens belastning. Pumpestationen kan forsynes fra en lagertank, og hydraulikvæsken 5 kan eksempelvis være en standard hydraulikolie, men det foretrækkes, at motorens smøreolie anvendes som hydraulikvæske, og at systemet fødes fra motorens oliesump.In view of the durability of the valve and of an advantageously accurate control of the conditions in the combustion chamber and thus of the efficiency of the engine, the exhaust valve can advantageously be controlled very precisely. The exhaust valve is opened by means of an actuator 9 which is hydraulically driven. The hydraulic fluid is supplied through a pressure line 10 which connects a fluid inlet and outlet 11 of the actuator to a control port on the upper side of a distributor block 12 carried by a bracket 13. The console is connected to a high pressure line 14 for hydraulic fluid which The pump station 35 shown is supplied with hydraulic fluid at a pressure which may, for example, be in the range of 125 to 325 bar. The pressure may be fixed, but is preferably adjustable depending on the load of the motor. The pump station may be supplied from a storage tank, and the hydraulic fluid 5 may, for example, be a standard hydraulic oil, but it is preferred that the engine lubricating oil be used as a hydraulic fluid and that the system be fed from the engine oil sump.

Forbrændingsmotoren kan være en mellemhastigheds firtaktsmotor, men er typisk en langsomtgående totakts 10 krydshovedmotor, der kan være fremdrivningsmotor i et skib eller en stationær drivenhed i et kraftværk.The internal combustion engine may be a medium-speed four-stroke engine, but is typically a slow-moving two-stroke 10 head motor which may be a propulsion engine in a ship or a stationary drive unit in a power plant.

Motoren kan udformes i forskellige størrelser med ydelser per cylinder fra 400 kW til 5500 kW, og den kan have omdrejningstal ved fuldlast beliggende i inter-15 vallet fra 50 til 600 rpm, typisk højst 200 rpm.The motor can be designed in various sizes with performance per cylinder from 400 kW to 5500 kW, and it can have full load rpm in the range of 50 to 600 rpm, typically at most 200 rpm.

Hver cylinder på motoren er tilknyttet en elektronisk styreenhed 15, der modtager overordnede synkroniserings- og styresignaler gennem ledninger 16 og afgiver elektroniske styresignaler til blandt andet en 20 styreventil 17 gennem en ledning 18. Der kan være en styreenhed 15 per cylinder, eller flere cylindre kan være tilknyttet samme styreenhed. Styreenheden kan også modtage signaler for en overordnet styreenhed, der er fælles for alle cylindrene.Each cylinder of the motor is associated with an electronic control unit 15 which receives overall synchronization and control signals through wires 16 and outputs electronic control signals to, inter alia, a 20 control valve 17 through a conduit 18. There may be one control unit 15 per cylinder, or several cylinders may be associated with the same controller. The control unit may also receive signals for an overall control unit common to all the cylinders.

25 I konsollen leder en afgrenet kanal 19 fra høj tryksledningen den tryksatte hydrauliske væske frem til en højtryksport på styreventilen 17. Kanalen 19 er forsynet med et antal væskeakkumulatorer 20, der leverer hovedparten af væskemængden, når styreventilen 3 0 åbner, og efterfødes fra høj tryksledningen, mens styreventilen er lukket. En styreport på styreventilen er via en kanal 21 i fordelerblokken forbundet med afgangsporten på blokkens overside. Styreventilen har endvidere en tankport, der via et kanalformet tilba-35 geløb 22 er forbundet med en returledning for brugt 14 DK 174031 B1 hydraulikvæske. Alternativt kan tilbageløbet være forbundet med et dræn ved atmosfæretryk, eksempelvis en drænledning førende til motorens oliesump. Trykket i tilbageløbet kan være fra atmosfæretryk til nogle få 5 bars overtryk. For at undgå indtrængning af luft i aktuatoren foretrækkes, at der er overtryk i tilbageløbet, eksempelvis mindst 1 bars overtryk, så der opretholdes overtryk i trykledningen 10, mens hydraulikvæsken bortledes fra aktuatoren.In the console, a branched duct 19 from the high pressure line directs the pressurized hydraulic fluid to a high pressure port on the control valve 17. The duct 19 is provided with a plurality of fluid accumulators 20 which supply most of the fluid quantity when the control valve 30 opens and is reborn from the high pressure line. , while the control valve is closed. A control port on the control valve is connected via a channel 21 in the distributor block to the outlet port on the upper side of the block. The control valve further has a tank port which is connected via a duct-shaped reflux 22 to a return line for used hydraulic fluid. Alternatively, the reflux may be connected to a drain at atmospheric pressure, for example a drain line leading to the engine oil sump. The pressure in the reflux can be from atmospheric pressure to a few 5 bar overpressures. In order to avoid the entry of air into the actuator, it is preferred that there is overpressure in the reflux, for example at least 1 bar overpressure, so that overpressure is maintained in the pressure line 10 while the hydraulic fluid is discharged from the actuator.

10 Når udstødsventilen skal åbnes, aktiverer et styresignal fra styreenheden 15 styreventilen 17 til den stilling, hvor højtryksporten er forbundet med styreporten, så høj tryksvæsken har fri adgang til trykledningen 10 og dermed til væsketilgangen 11. Når 15 udstødsventilen 4 skal lukkes, aktiveres styreventilen til den stilling, hvor den til tilbageløbet sluttede tankport er forbundet med styreporten, hvorved højtrykket i ledningen 10 drænes bort.10 When the exhaust valve is to be opened, a control signal from the control unit 15 activates the control valve 17 to the position where the high pressure port is connected to the control port, so that the high pressure liquid has free access to the pressure line 10 and thus to the liquid inlet 11. When the exhaust valve 4 is closed, the control valve is activated to the position where the refueling port connected to the reflux is connected to the control port, whereby the high pressure in line 10 is drained away.

Styreventilen 17 kan være af enhver sædvanlig 20 type, såsom en enkelt, elektronisk aktiveret ventil med tre porte og to stillinger. For at opnå meget hurtige, præcise ventilindstillinger foretrækkes dog, at styreventilen 17 er sammensat af to ventiler, nemlig en elektronisk aktiveringsventil 17a og en hovedventil 17b 25 for venti1aktuatoren. Aktiveringsventilen 17a kan have tre porte og to stillinger. Den kan eksempelvis være af typen med magnetisk låsning i yderstillingerne, hvor ventilen aktiveres ved magnetisering af en af to spoler beliggende ved hver ende af en ventilglider af ferro-30 magnetisk materiale. Som sikkerhed i tilfælde af svigt ved magnetiseringen af de to spoler kan en fjeder forbelaste ventilglideren til indtagelse af en inaktiv stilling, hvor tankporten til tilbageløbet 22 er den aktive tilgangsport. Aktiveringsventilen kan alterna-35 tivt være en sædvanlig solenoideventil. Aktiverings- 15 DK 174031 B1 ventilens afgangsport er forbundet med en mellemkanal, der kommunikerer trykket til en stempelflade på den ene ende af hovedventilen 17b's glider, hvis anden ende har en stempelflade med mindre areal, der er i permanent 5 forbindelse med højtryksledningen. I aktiveringsventilens ene stilling presser højtrykket på det mindre stempelareal hovedglideren til den stilling, hvor returledningen via tilbageløbet 22 er tilsluttet hoved-. ventilens afgangsport, der fører til trykledningen 10.The control valve 17 can be of any conventional type, such as a single, electronically activated valve with three gates and two positions. However, to achieve very fast, precise valve settings, it is preferred that the control valve 17 is composed of two valves, namely an electronic actuation valve 17a and a main valve 17b 25 for the valve actuator. The actuating valve 17a can have three ports and two positions. It may, for example, be of the type of magnetic locking in the outer positions where the valve is actuated by magnetizing one of two coils located at each end of a valve slider of ferro-magnetic material. As safety in the event of failure in the magnetization of the two coils, a spring can preload the valve slider to assume an inactive position, the refueling port tank 22 being the active inlet port. The actuating valve may alternatively be a conventional solenoid valve. The outlet port of the actuating valve is connected to an intermediate channel which communicates the pressure to a piston surface on one end of the main valve 17b's slider, the other end of which has a piston surface with a smaller area which is permanently connected to the high pressure line. In the one position of the actuating valve, the high pressure on the smaller piston area pushes the main slide to the position where the return line is connected via the return flow 22 to the main. the outlet port of the valve leading to the pressure line 10.

10 Når aktiveringsventilen 17a er aktiveret til sin anden stilling med mellemkanalen tilsluttet højtryksledningen 14, presser højtrykket på den større stempelflade hovedventilens glider til dennes anden stilling, hvor højtrykket ledes til trykledningen 10, så aktuatoren 15 åbner udstødsventilen.When the actuating valve 17a is actuated to its second position with the intermediate channel connected to the high pressure line 14, the high pressure on the larger piston surface presses the main valve slider to its second position, where the high pressure is directed to the pressure line 10, so that the actuator 15 opens the exhaust valve.

Herefter beskrives aktuatoren 9 og den pneumatiske fjeder nærmere. I beskrivelsen af udførelsesformerne vist på tegningen anvendes for nemheds skyld ens henvisningstal for elementer med til hinanden svarende 20 virkemåde i udførelsesformerne.Next, the actuator 9 and the pneumatic spring are described in more detail. In the description of the embodiments shown in the drawing, for convenience, similar reference numerals are used for elements having similar operation in the embodiments.

Udstødsventilen har en fra ventiltallerkenen opstående spindel 24, der ved sin øvre ende bærer et fast påmonteret fjederstempel 25, der er tryktætnende og længdeforskydeligt monteret i en luftcylinder 26, så 25 der under fjederstempiet er et fjederkammer 27, der er tilsluttet en ikke vist trykluftstilførsel, der holder fjederkammeret fyldt med trykluft ved et forudbestemt minimumstryk på eksempelvis 4,5 bars overtryk. Andre lufttryk er også anvendelige, såsom fra 3 til 10 bar.The exhaust valve has a spindle 24 emerging from the valve plate, which carries at its upper end a fixedly mounted spring piston 25 which is pressure-sealing and longitudinally displaced in an air cylinder 26, so that 25 there is a spring chamber 27 connected to a compressed air supply under the spring temperature. holding the spring chamber filled with compressed air at a predetermined minimum pressure of, for example, 4.5 bar overpressure. Other air pressures are also applicable, such as from 3 to 10 bar.

30 Minimumstrykket vælges efter den ønskede fjederkarakteristik af den pneumatiske fjeder. Det er muligt at forbinde fjederkamrene på flere forskellige cylindre med hinanden, men det foretrækkes, at hvert fjederkammer er separat afspærret af en kontraventil ved tryk-35 lufttilførslen. Lufttrykket i fjederkammeret påvirker 16 DK 174031 B1 fjederstemplet 25 med en vedvarende opadrettet kraft.30 The minimum pressure is selected according to the desired spring characteristic of the pneumatic spring. It is possible to connect the spring chambers on several different cylinders with each other, but it is preferred that each spring chamber is separately shut off by a check valve at the compressed air supply. The air pressure in the spring chamber affects the spring piston 25 with a sustained upward force.

Hvis fjederkammeret er afspærret vokser den opadrettede kraft, når fjederstemplet forskydes nedad og komprimerer luften i fjederkammeret.If the spring chamber is shut down, the upward force grows as the spring piston shifts downward and compresses the air in the spring chamber.

5 Et hus 28 afgrænser et hulrum 29 omkring og over den pneumatiske fjeder. Hulrummet er tilsluttet et ikke vist dræn ved en åbning 30, så der hersker atmosfæretryk i hulrummet.5 A housing 28 defines a cavity 29 around and above the pneumatic spring. The cavity is connected to a drain (not shown) at an opening 30, so that atmospheric pressure prevails in the cavity.

Aktuatoren 9 er opbygget af to faste dele i form 10 af en stationær cylinder 31, der er understøttet af oversiden af huset 2 8 og et på cylinderen monteret dæksel 32, der ved hjælp af dækseltappe 33 er spændt fast til huset 28. Dækslet afgrænser et primært trykkammer 34, der står i forbindelse med væsket ilgangen og 15 -afgangen 11. En udluftningskanal 35 fører til en i dækslet monteret udluftningsventil 36. Det primære trykkammer er gennem kanaler 37 forbundet med et ringformet kammer 38 i den stationære cylinder. Et afspærringsorgan 39 lukker enden af den ene af kanaler-20 ne 37.The actuator 9 is made up of two fixed parts in the form 10 of a stationary cylinder 31 supported by the upper side of the housing 2 8 and a cover 32 mounted on the cylinder, which is secured to the housing by means of cover pin 33. primary pressure chamber 34, which is connected to the liquid inlet and outlet 15. A vent channel 35 leads to a vent valve 36 mounted in the cover. The primary pressure chamber is connected through channels 37 to an annular chamber 38 in the stationary cylinder. A shut-off member 39 closes the end of one of the channels 20.

Et aktuatorstempel omfatter en første stempeldel 40 med en ringformet væg, hvis yderside er længdeforskydeligt styret i en gennemgående cylinderboring 41, der fra kammeret 3 8 fører ned til undersiden af den 25 stationære cylinder, og en anden, cylindrisk stempeldel 42, der er længdeforskydeligt styret af en cylindrisk styreflade 43 på indersiden af den første stempeldel.An actuator piston comprises a first piston portion 40 with an annular wall, the outside of which is longitudinally controllable in a through-going bore 41 leading from the chamber 38 to the underside of the 25 stationary cylinder, and a second cylindrical piston portion 42 longitudinally displaceable of a cylindrical guide surface 43 on the inside of the first piston member.

De to stempeldele er således teleskopagtigt forskydeligt lejret i den stationære cylinder.The two piston parts are thus telescopically slidably mounted in the stationary cylinder.

30 En positioneringsenhed indeholder et væskekammer 44, der er afgrænset af en positioneringscylinder 45, som ligger løst an mod oversiden af spindlen 24, og et positioneringsstempel 46, der er tryktætnende og længdeforskydeligt lejret i positioneringscylinderen og 3 5 er udført ud i et med den nedre ende af den anden 17 DK 174031 B1 stempeldel 42. Et indadragende, aftageligt stop 47 ved overenden af cylinderen 45 holder stemplet 46 på plads i cylinderen, hvis denne skulle slippe anlægget mod spindlen 24.A positioning unit contains a liquid chamber 44 which is bounded by a positioning cylinder 45 loosely abutting the top of the spindle 24, and a positioning piston 46 which is pressure-sealing and longitudinally displaceable in the positioning cylinder and is integrally formed with the lower one. end of the second piston part 42. An inwardly extending, removable stop 47 at the upper end of the cylinder 45 holds the piston 46 in place in the cylinder should it release the abutment against the spindle 24.

5 Den forste stempeldel er opadtil lukket af en stempeltop 48, der er udført ud i et med den ringformede væg. Indersiden af stempeltoppen udgør endebund i et sekundært trykkammer 49, der i den viste udgangsstilling for stempeldelene via en central boring 50 og 10 tværgående kanaler 51 i den anden stempeldel er forbundet med det primære trykkammer gennem opad åbne, lodrette boringer 52 og tværgående gennemboringer 53 i det første stempeldels ringvæg.5 The first piston portion is closed upwardly by a piston top 48 formed integrally with the annular wall. The inside of the piston top forms the end bottom of a secondary pressure chamber 49 which, in the indicated starting position of the piston parts via a central bore 50 and 10 transverse channels 51 in the second piston part, is connected to the primary pressure chamber through upwardly vertical vertical bores 52 and transverse bores 53 in the ring wall of the first piston part.

Den centrale boring 50 i den anden stempeldel er 15 gennemgående og er i sin nedre ende forsynet med en kontraventil 54, der er trykstyret, som det herefter forklares med henvisning til fig. 3. Kontraventilen omfatter en ventilglider 55, der er længdeforskydelig i et ventilhus 56 og har en central gennemgående boring 20 57, der fra boringen 50 fører ned til ventilgliderens underside, der ved åben kontraventil ligger i kort afstand fra en lukkeflade 58 på toppen af et fremspring 59 i ventilhusets nedre part. Ventilglideren har en udragende krave, der virker som fjederstyr for en 25 trykfjeder 60, der påfører ventilglideren en opadrettet åbnekraft. En nedad åben boring 61 og en tværboring 62 i fremspringet 59 forbinder væskekammeret 44 med hulrummet omkring fjederen.The central bore 50 of the second piston portion is 15 through and is provided at its lower end with a non-return valve 54 which is pressure controlled, as will be explained with reference to FIG. The non-return valve comprises a valve slider 55 which is longitudinally displaceable in a valve housing 56 and has a central through bore 20 57 which leads from the bore 50 down to the underside of the valve slider, which, at open check valve, is a short distance from a closing surface 58 on top of a projections 59 in the lower part of the valve body. The valve slider has a protruding collar which acts as a spring guide for a compression spring 60 which applies an upward opening force to the valve slider. A downwardly open bore 61 and a transverse bore 62 in the projection 59 connect the liquid chamber 44 to the cavity around the spring.

Når udstødsventilen er lukket er trykket i det 30 primære trykkammer tilnærmelsesvis af samme størrelse som trykket i væskekammeret 44, og fjederen 60 kan holde kontraventilen åben. Positioneringsstemplet har større diameter end cylinderboringen 41 i den stationære cylinder, der bestemmer det opadvendende effektive 35 areal på aktuatorstemplets dele, og positionerings- 18 DK 174031 B1 stemplet har dermed et større trykpåvirket nedadven-dende areal i væskekammeret end aktuatorstemplets opadvendende areal. Da trykkene i de to kamre er tilnærmelsesvis lige store presses positioneringcylin-5 deren nedad mod spindlen 24, og positioneringsstemplet presses opad til anlæg mod den nedre ende af det første stempel og påvirker dette med en resulterende opadret-tet kraft, der sikrer, at aktuatorstemplet står i den viste udgangsstilling, inden udstødsventilen åbnes.When the exhaust valve is closed, the pressure in the primary pressure chamber is approximately the same as the pressure in the liquid chamber 44, and the spring 60 can hold the check valve open. The positioning piston has a larger diameter than the cylinder bore 41 in the stationary cylinder, which determines the upwardly effective area of the actuator piston parts, and the positioning piston thus has a greater pressure-acting downward area in the liquid chamber than the upwardly facing area of the actuator piston. Since the pressures in the two chambers are approximately equal, the positioning cylinder 5 is pressed downwardly against the spindle 24 and the positioning piston is pressed upwardly to abut the lower end of the first piston and affects this with a resultant upward force which ensures that the actuator piston is in the initial position shown before opening the exhaust valve.

10 Når trykket i det primære trykkammer pludselig stiger fra omkring 1,5 bar til eksempelvis 250 bar, fordi væsketilgangen 11 tilsluttes høj tryksledningen, forplanter højtrykket sig ned gennem boringen 50 og påvirker overenden af ventilglideren med en nedadrettet 15 kraft, som overvinder åbnekraften fra fjederen 60 og får kontraventilen til at lukke. Trykstigningen i boringen 50 sker så hurtigt, at kontraventilen lukker, inden trykket forplanter sig til hulrummet omkring fjederen 60. Når udstødsventilen igen står i lukket 20 stilling, genåbner fjederen 60 kontraventilen.10 When the pressure in the primary pressure chamber suddenly rises from about 1.5 bar to, for example, 250 bar, because the fluid inlet 11 is connected to the high pressure line, the high pressure propagates down through the bore 50 and affects the upper end of the valve slider with a downward force which overcomes the open force from the spring. 60 and causes the check valve to close. The pressure rise in bore 50 occurs so rapidly that the check valve closes before the pressure propagates to the cavity around the spring 60. When the exhaust valve is in the closed position again, the spring 60 reopens the check valve.

Den første stempeldel har på sin yderside en udragende krave 63, der rager ud i det ringformede kammer 38. Den opadrettede kraft på den første stempeldel presser oversiden af kraven op mod en flad ring 64 2 5 (se fig. 5) , der ligger an mod kammerloftet og sammen med dette fastlægger et første anslag, der begrænser den første stempeldels opadgående bevægelse, hvorved den første stempeldel har en veldefineret udgangsstilling. Da oversiden af positioneringsstemplet 3 0 presser op mod den nedre ende af den første stempeldel, er den anden stempeldels udgangsstilling også veldefineret .The first piston member has on its outside a protruding collar 63 protruding into the annular chamber 38. The upward force of the first piston member presses the upper side of the collar up against a flat ring 64 2 5 (see Fig. 5), against the chamber ceiling and together with this establishes a first stop which restricts the upward movement of the first piston part, whereby the first piston part has a well-defined starting position. As the upper side of the positioning piston 30 pushes up against the lower end of the first piston part, the starting position of the second piston part is also well defined.

Når udstødsventilen skal åbnes, og styreventilen 17 tilfører højtrykket til det primære og det sekundære 35 trykkammer, presses de to stempeldele samtidigt nedad, 19 DK 174031 B1 og den udragende krave forskydes nedad i det ringformede kammer 38 samtidig med, at den flade ring flyttes lidt væk fra kammerloftet, så der gennem flere kanaler 65, der forbinder det primære trykkammer med udløbsåb-5 ninger i kammerloftet, kan strømmme væske ned i kammeret 38 på oversiden af den udragende krave.When the exhaust valve is to be opened and the control valve 17 applies the high pressure to the primary and secondary 35 pressure chambers, the two piston parts are simultaneously pressed downwards, and the protruding collar is moved downwards in the annular chamber 38 while at the same time moving the flat ring slightly away from the chamber ceiling, so that through multiple ducts 65 connecting the primary pressure chamber with outlet openings in the chamber ceiling, liquid can flow into the chamber 38 on the upper side of the protruding collar.

Når den udragende krave nærmer sig kammerbunden, passerer den et udragende, rundtgående fremspring på kammerets inderside, hvorved der fremkommer en snæver 10 ringspalte mellem fremspringet og ydersiden af kraven 63, hvorigennem den under kraven værende væske skal udpresses. Dette giver en anslagsdæmpning, som bremser den første stempeldel, inden kravens underside ligger an mod kammerbunden.As the protruding collar approaches the chamber bottom, it passes a protruding, circumferential protrusion on the inside of the chamber, creating a narrow annular gap between the protrusion and the outside of the collar 63, through which the liquid under the collar is to be extruded. This provides an abutment damping, which brakes the first piston part before the underside of the collar abuts the chamber bottom.

15 Når den nedadgående bevægelse af den første stempeldel er standset, tilføres det sekundære trykkammer 49 højtryksvæske gennem kanalen 51 og boringen 52, så aktiveringstrykket på den anden stempeldel oprethol des. Den anden stempeldel forskydes derefter nedad, 20 indtil væsketilførslen til det sekundære trykkammer afbrydes, fordi kanalen 51 bevæges ned under gennemboringen 53 .When the downward movement of the first piston part is stopped, the secondary pressure chamber 49 is supplied with high pressure fluid through the duct 51 and the bore 52 so that the activation pressure on the second piston part is maintained. The second piston portion is then displaced downwardly 20 until the liquid supply to the secondary pressure chamber is interrupted because the duct 51 is moved down during the piercing 53.

Den anden stempeldel afbremses, inden den når sin nedre yderstilling, så den pneumatiske fjeder kan 25 standse udstødsventilen i netop den ønskede fuldt åbne stilling. Dette sker ved en gradvis afskæring af forbindelsen til det sekundære trykkammer, som det herefter forklares med henvisning til fig. 4, der viser den anden stempeldel i en position, hvor bremsningen er 30 begyndt. Den første stempeldel 40 står stille, og gennemboringen 53 er udefter afspærret af indersiden 41, så væsken kun tilledes gennem boringen 52. Linien a markerer den nedre rand af gennemboringen 53, og denne ligger i figuren ud for den øvre rand af kanalen 35 51. Der kan stadig strømme væske ind i kammeret 49, men 20 DK 174031 B1 kun gennem en smal spalte 66, der er frembragt af, at den anden stempeldels yderside har en skrå afskæring 67 i området over kanalen 51, så der i dette område er en opad tilspidsende recess, som ved den videre nedad-5 gående stempelbevægelse giver en fremadskridende indsnævring af spalten 66, indtil den øvre ende af afskæringen 67 er bevæget ned til linien a, hvor det sekundære trykkammer 49 er helt afspærret. Bremselængden s kan tilpasses den konkrete udstødsventil både ved 10 at gøre afskæringen dybere og ved at ændre dens hældning. Modstanden mod væskeindløb i kammeret 49 medfører, at kammertrykket falder. Der kan være en enkelt skrå afskæring med tilhørende opad tilspidsende recess, hvor afskæringen er rundtgående på den anden stempel-15 del, eller der kan være flere skrå afskæringer med tilhørende recesser, hvor de er beliggende enkeltvis over deres tilhørende kanal 51.The second piston member is decelerated before it reaches its lower outer position, so that the pneumatic spring can stop the exhaust valve in precisely the desired fully open position. This is done by a gradual cutting of the connection to the secondary pressure chamber, which is then explained with reference to FIG. 4, showing the second piston part in a position where the braking has begun. The first piston portion 40 is stationary, and the bore 53 is outwardly blocked by the inside 41 so that the liquid is supplied only through the bore 52. The line a marks the lower edge of the bore 53, and this is in the figure opposite the upper edge of the channel 35 51. Fluid may still flow into chamber 49, but only through a narrow slot 66, which is caused by the outer face of the second piston member having an inclined cut-off 67 in the region over channel 51, so that in this region there is a upwardly tapering recess, which, with the further downward piston movement, provides a progressive narrowing of the slot 66 until the upper end of the cutter 67 is moved down to the line a, where the secondary pressure chamber 49 is completely closed off. The brake length s can be adjusted to the concrete exhaust valve both by deepening the cut and by changing its inclination. The resistance to liquid inlet into chamber 49 causes the chamber pressure to decrease. There may be a single inclined cut with associated upwardly tapering recess, the cut being circumferential on the second piston portion, or there may be multiple inclined cuts with associated recesses located individually over their associated channel 51.

Højtrykket i det primære trykkammer holder udstødsventilen i den fuldt åbne stilling. Når ventilen 20 skal lukkes, aktiveres styreventilen 17 af styreenheden 15 til at forbinde det primære trykkammer 34 til tilbageløbet 22, så kammertrykket og dermed holdekraften på aktuatorstemplet pludseligt mindskes, så den opadrettede lukkekraft fra den pneumatiske fjeder 23 25 bevæger spindlen 24 opad under samtidig løftning af den anden stempeldel 42, som forskydes op i den første stempeldel, der samtidig kun bevæges en anelse opad som følge af, at brændslet skal strømme ind under den udragende krave 63 via den snævre spalte ved frem-30 springet 53. Når oversiden af positioneringsstemplet 46 træffer den nedre ende af den første stempeldel, overføres hele lukkekraften til denne, der hurtigt accellereres opad mod udgangsstillingen. Nær udgangsstillingen, bevæges en opstående, radialt udadvendende 35 kammervæg 68, der er beliggende mellem den udragende 21 DK 174031 B1 kraves overside og oversiden af stempeldelen (se fig.The high pressure in the primary pressure chamber keeps the exhaust valve in the fully open position. When the valve 20 is to be closed, the control valve 17 is actuated by the control unit 15 to connect the primary pressure chamber 34 to the return 22, so that the chamber pressure and thus the holding force of the actuator piston is suddenly reduced, so that the upward closing force of the pneumatic spring 23 25 moves up the spindle 24 upwards simultaneously. of the second piston part 42 which is displaced into the first piston part, which at the same time only moves slightly upwards as the fuel must flow under the protruding collar 63 via the narrow gap at the projection 53. When the upper side of the positioning piston 46 hit the lower end of the first piston part, the entire closing force is transferred to it, which is rapidly accelerated upward toward the initial position. Near the initial position, an upright radially outwardly extending chamber wall 68 is moved between the upper side of the protruding collar and the upper side of the piston member (see FIG.

5) , op forbi kammerloftet, hvorved der over den udragende krave 63 fremkommer et dæmperkammer med en ringformet udløbsspalte mellem kammervæggen 68 og en 5 sidevæg 69 i det primære trykkammer. Udløbsspalten modvirker tømningen af dæmperkammeret, så trykket heri stiger, og ringen 64 presses opad og afspærrer udløbsåbningerne fra kanalerne 65. Kammervæggen 68's øverste del 70 er skråt afskåret til en konisk flade, 10 så bredden af udløbsspalten gradvist mindskes. Både dybden og hældningen af den skrå afskæring kan tilpasses efter den aktuelle udstødsventil, så udstødsventilen opnår en præcis og blid kontakt mellem sine sædeflader i lukkeøjeblikket.5), up past the chamber ceiling, whereby a damper chamber with an annular outlet gap between the chamber wall 68 and a side wall 69 of the primary pressure chamber is formed above the protruding collar 63. The outlet slot prevents the emptying of the damper chamber so that the pressure therein increases and the ring 64 is pressed upwardly and closes the outlet openings from the ducts 65. The upper portion 70 of the chamber wall 68 is obliquely cut to a tapered surface 10 so that the width of the outlet slot is gradually reduced. Both the depth and the inclination of the inclined cut-off can be adapted to the actual exhaust valve, so that the exhaust valve achieves precise and gentle contact between its seat surfaces at the closing moment.

15 Fjederstemplet 25 bærer på sin overside en opad åben, kopformet og rotationssymmetrisk skærm med en sidevæg 71, der har opefter aftagende vægtykkelse. I huset 28 er på diametralt modstående sider af sidevæggen monteret to sensorer 72, der gennem ledninger 73 20 afgiver signaler til styreenheden 15. Signalerne kan eksempelvis være en spænding, hvis størrelse afhænger af afstanden mellem sensorens ende og ydersiden af sidevæggen 71. Da denne er skrå, vokser afstanden, når fjederstemplet bevæges nedad, og sensorerne giver 25 således styreenheden tilbagemelding om den øjeblikkelige position af udstødsventilen 4.The spring piston 25 carries on its upper side an upwardly open, cup-shaped and rotationally symmetrical screen with a side wall 71 having upwardly decreasing wall thickness. In the housing 28 are mounted on diametrically opposite sides of the side wall two sensors 72 which, through wires 73 20, give signals to the control unit 15. The signals may, for example, be a voltage, the size of which depends on the distance between the end of the sensor and the outside of the side wall 71. oblique, the distance increases as the spring piston moves downwardly, and the sensors thus provide the controller with feedback on the instantaneous position of the exhaust valve 4.

Herefter beskrives den anden udførelsesform for aktuatoren vist i fig. 5, hvor figurens højre og venstre halvdele viser aktuatorstemplet i henholdsvis 30 udgangsstillingen og i stillingen, hvor udstødsventilen er fuldt åben. Der beskrives kun de træk, der afviger fra den første udførelsesform. Aktuatoren i fig. 5 udmærker sig ved at være en tretrinsaktuator, hvilket giver de nedenfor forklarede fordele. I forhold til den 35 første udførelsesform, hvor den første stempeldel udgør 22 DK 174031 B1 første trin og den anden sterapeldel udgør andet trin i aktuatorbevægeIsen, udgør den anden stempeldel 42 tredie trin i tretrinsaktuatoren. Det andet trin udgøres af en tredie stempeldel 74, der er et simpelt 5 ringformet legeme med firkantet tværsnit som ligger mellem den første og den anden stempeldel. Som følge af de tre trin har det ringformede kammer 38 kortere længde end i den første udførelsesform. Den første stempeldels aktive vandring i første trin er markeret 10 ved afstanden A, den tredie stempeldels aktive vandring i andet trin er markeret ved afstanden B, og den anden stempeldels aktive vandring i det tredie trin er markeret ved afstanden C.Next, the second embodiment of the actuator shown in FIG. 5, where the right and left halves of the figure show the actuator piston in the initial position and in the position where the exhaust valve is fully open. Only those features that deviate from the first embodiment are described. The actuator of FIG. 5 is distinguished by being a three-stage actuator, which provides the advantages explained below. In relation to the first embodiment, where the first piston part constitutes the first stage and the second steroid part forms the second stage of the actuator movement, the second piston part 42 constitutes the third stage of the three-stage actuator. The second stage is constituted by a third piston member 74, which is a simple annular body of square cross-section lying between the first and second piston members. As a result of the three steps, the annular chamber 38 has a shorter length than in the first embodiment. The first piston part active walk in the first step is marked 10 at distance A, the third piston active walk in the second step is marked at distance B, and the second piston part active walk in the third step is marked at the distance C.

Trykket i det primære trykkammer 34 påvirker alle 15 tre stempeldele, når de udfører deres aktive vandring.The pressure in the primary pressure chamber 34 affects all 15 three piston parts as they carry out their active migration.

Dette giver den forenkling, at det sekundære trykkammer med tilhørende forbindelseskanaler er udeladt. Det ringformede kammer er i udgangsstillingen forbundet med det primære trykkammer gennem tværkanaler 75 i den 20 ringformede væg af den første stempeldel. Tværkanalerne ligger et stykke under undersiden af den udragende krave 63, så der er dæmpning til bremsningen af den første stempeldels nedadgående bevægelse.This gives the simplification that the secondary pressure chamber with associated connection ducts is omitted. In the initial position, the annular chamber is connected to the primary pressure chamber through transverse channels 75 in the annular wall of the first piston member. The transverse channels are located slightly below the underside of the protruding collar 63 so that there is damping to the downward movement of the first piston part.

Den anden stempeldel 42 har en øvre stempeltop 76, 25 der er udsat for trykket i det primære trykkkammer og er boltet fast til et skaft, der er udført i et stykke med positioneringsstemplet 46. Skaftet har et skaftafsnit 77, der er styret af den første stempeldels som styreflade virkende inderside 43, der er beliggende i 30 det nederste stykke af stempeldelen. Oven over skaftafsnittet 77 har skaftet et recessafsnit 78, der har større længde end kammeret 38 og er opadtil begrænset af en aksialvendende flade 79 og er nedadtil begrænset af en bundflade 80.The second piston part 42 has an upper piston top 76, 25 which is exposed to the pressure in the primary pressure chamber and is bolted to a shaft which is integral with the positioning piston 46. The shaft has a shaft portion 77 which is controlled by the first piston part acting as a guide surface inside 43 located in the lower portion of the piston part. Above the shaft section 77, the shaft has a recess section 78 which is longer in length than the chamber 38 and is upwardly restricted by an axially facing surface 79 and is downwardly restricted by a bottom surface 80.

35 Den første stempeldel 40 er opadtil åben og har en 23 DK 174031 B1 cylindrisk recess 81, der er nedadtil begrænset af en bundflade 82 og har større indre diameter end indersiden 43. I den øvre ende af den'første stempeldel har recessen 81 et dæmperafsnit for den anden stempeldel.The first piston part 40 is open upwards and has a cylindrical recess 81 downwardly restricted by a bottom surface 82 and having a larger internal diameter than the inside 43. At the upper end of the first piston part, the recess 81 has a damper section. for the second piston part.

5 Den øverste del 83 af dæmperafsnittet er konisk med nedefter aftagende diameter, så der ved afslutningen af den anden stempeldels nedadgående bevægelse mellem stempeltoppen IS' s yderrand 84 og den øverste del 83 fremkommer en ringspalte, hvis bredde aftager, så der 10 opnås en gradvist tiltagende dæmpning ved udpresningen af væsken under stempeltoppen, svarende til det ovenfor beskrevne i forbindelse med fig. 4.The upper portion 83 of the damper section is conical with downward decreasing diameter so that at the end of the downward movement of the second piston member between the outer edge 84 of the piston top IS and the upper portion 83 a ring gap whose width decreases so that a gradual increasing attenuation in the extruding of the liquid below the piston top, similar to that described above in connection with FIG. 4th

Den tredie stempeldel 74 er indsat delvis i recessafsnittet 78, delvis i recessen 81. Et hulrum 85 15 under undersiden af stempeldelen 74 sikrer via en trykaflastningskanal 86, der fører ned gennem den første stempeldels ringvæg og udmunder i hulrummet 29, opretholdelse af atmosfæretryk under den tredie stempeldel. Under åbningsbevægelsen standses den første 20 stempeldel af bunden i det ringformede kammer, den tredie stempeldel standses, når den rammer bundfladen 82, og den anden stempeldel standses, når den aksial-vendende flade 79 lander på oversiden 87 af den stillestående tredie stempeldel. Oversiden 87 udgør således 25 et andet anslag, der definerer udstødsventilens fuldt åbne stilling. Ved lukkebevægelsen trækkes den tredie stempeldel med op til en veldefineret udgangsstilling ved sit anlæg mod bundfladen 80 på den anden stempel-del.The third piston portion 74 is inserted partially into the recess section 78, partly to the recess 81. A cavity 85 15 below the bottom of the piston portion 74 ensures, via a pressure relief channel 86, which leads down through the annular wall of the first piston portion and opens into the cavity 29, maintaining atmospheric pressure below it. third piston part. During the opening movement, the first 20 piston part is stopped from the bottom of the annular chamber, the third piston part is stopped when it hits the bottom surface 82, and the second piston part is stopped when the axially facing surface 79 lands on the upper side 87 of the stationary third piston part. Thus, the upper side 87 constitutes another stop defining the fully open position of the exhaust valve. In the closing movement, the third piston part is pulled up to a well-defined starting position at its abutment against the bottom surface 80 of the second piston part.

30 I den anden udførelsesform er kontraventilen 54 placeret i toppen af den anden stempeldel. Kontraventilen omfatter en ventilglider 88, der har et øvre, cylindrisk afsnit 89 beliggende i en øvre cylinderboring 90 og et nedre, cylindrisk afsnit 91, der har 35 større diameter end det øvre afsnit og er beliggende i 24 DK 174031 B1 en nedre cylinderboring 92. Mellem de to afsnit er der en radialt udragende krave 93 med et underliggende ringrum 94, dannet af en inddrejning under kraven. En central boring 95 med en nedre tværkanal forbinder det 5 primære trykkammer med ringrummet. Trykfjederen 60 er beliggende i den nedre cylinderboring, der via en trykaflastningskanal 96 er forbundet med hulrummet 29, så der opretholdes atmosfæretryk på undersiden af ventilglideren 88. Væskekammeret 44 er via en gennem-10 gående boring 97 forbundet med et lille kammer 98 omkring kraven 93. Den trykstyrede ventilglider virker på følgende måde. Trykket i det primære trykkammer ledes gennem boringen 95 ned i ringrummet 94 og påvirker vedvarende det opadrettede, ringformede, dif-15 ferensareal frembragt af diameterforskellen mellem det nedre afsnit 91 og det øvre afsnit 89 med en nedadret-tet kraft. Trykfjederen 60 påvirker vedvarende ventilglideren med en opadrettet åbnekraft. Når trykket i det primære trykkammer pludselig stiger, overvindes åb-20 nekraften af den nedadrettede kraft, og ventilglideren bevæges til den viste lukkede stilling, hvor kraven 93 afspærrer strømningsforbindelsen mellem ringrummet 94 og boringen 97 til væskekammeret i positioneringsenheden. Ventilglideren bevæges opad til den åbne 25 stilling, når trykket i det primære trykkammer falder såpas meget, at åbnekraften fra fjederen overvinder den nedadrettede kraft fra væsketrykket.In the second embodiment, the check valve 54 is located at the top of the second piston member. The check valve comprises a valve slider 88 having an upper cylindrical section 89 located in an upper cylinder bore 90 and a lower cylindrical section 91 having a larger diameter than the upper section and located in a lower cylinder bore 92. Between the two sections is a radially projecting collar 93 with an underlying annular space 94 formed by a recess below the collar. A central bore 95 with a lower cross channel connects the 5 primary pressure chamber to the annulus. The compression spring 60 is located in the lower cylinder bore which is connected to the cavity 29 via a pressure relief channel 96, so that atmospheric pressure is maintained on the underside of the valve slide 88. The liquid chamber 44 is connected via a through bore 97 to a small chamber 98 around the collar 93. The pressure controlled valve slider works as follows. The pressure in the primary pressure chamber is passed through the bore 95 into the annulus 94 and continuously affects the upward, annular, diffraction area produced by the diameter difference between the lower section 91 and the upper section 89 with a downward force. The compression spring 60 continuously affects the valve slider with an upward opening force. When the pressure in the primary pressure chamber suddenly increases, the open force is overcome by the downward force and the valve slider is moved to the closed position shown, with the collar 93 blocking the flow connection between the annulus 94 and the bore 97 to the liquid chamber in the positioning unit. The valve slider moves upward to the open position when the pressure in the primary pressure chamber drops so much that the open force from the spring overcomes the downward force from the fluid pressure.

Diagrammet i fig. 7 illustrerer fordelene ved at anvende en flertrins aktuator. Den skrå linie E viser 30 den faktisk målte opadrettede kraft på en udstødsventil, hvor kraften er målt på skillefladen mellem toppen af ventilspindlen og bunden af positioneringscylinderen. Kraften er vist som funktion af ventilspindlens afstand til den lukkede stilling, dvs. vandringen i 35 åbningsbevægelsen. I åbningsøjeblikket, hvor ventilen 25 DK 174031 B1 sættes i bevægelse, er den opadrettede kraft omtrent 53 kN, hvorefter den falder tilnærmelsesvis lineært ned til omtrent 15 kN umiddelbart før den fuldt åbne stilling, hvor ventilen er bevæget 70 mm bort fra 5 udgangsstillingen. For at åbne udstødsventilen skal aktuatoren frembringe en nedadrettet kraft, der er større end den opadrettede kraft på 53 kN, eksempelvis en kraft på 56 kN, markeret ved den vandrette linie F.The diagram of FIG. 7 illustrates the advantages of using a multi-stage actuator. The oblique line E shows the actual measured upward force on an exhaust valve, where the force is measured on the interface between the top of the valve stem and the bottom of the positioning cylinder. The force is shown as a function of the distance from the valve stem to the closed position, ie. the walk in the 35 opening movement. At the opening moment when the valve 25 DK 174031 B1 is set in motion, the upward force is approximately 53 kN, after which it drops approximately linearly to approximately 15 kN immediately before the fully open position where the valve is moved 70 mm away from the initial position. To open the exhaust valve, the actuator must produce a downward force greater than the upward force of 53 kN, for example a force of 56 kN, marked by the horizontal line F.

Hvis aktuatoren kun har et trin opretholdes denne kraft 10 under hele åbningsforløbet. Hvis aktuatoren i stedet har to trin, kan åbnekraften afhængig af de valgte trinlængder eksempelvis følge trinkurven G, vist med punkteret linie. Arbejdet og dermed energiforbruget ved ventilåbningen er repræsenteret ved arealet under 15 kurverne. Det ses umiddelbart, at der ved anvendelsen af en totrinsaktuator ved hver ventilaktivering spares det arbejde, der er markeret ved skravering, hvilket svarer til en besparelse på omtrent 18%. Hvis aktuatoren har tre trin, kan åbnekraften eksempelvis følge 20 Trinkurven H, vist med priklinie. Dette giver en arbejdsbesparelse i forhold til ettrinsaktuatoren på omtrent 26%. I det viste eksempel er den opadrettede lukkekraft fra den pneumatiske fjeder tilnærmelsesvis konstant omtrent 14 kN, vist ved linien I.If the actuator has only one step, this force 10 is maintained throughout the opening process. If, instead, the actuator has two steps, the opening force, depending on the selected step lengths, can, for example, follow the step curve G, shown in dotted line. The work and thus the energy consumption at the valve opening is represented by the area under the 15 curves. It is readily apparent that the use of a two-stage actuator with each valve actuation saves the work marked by shading, which corresponds to a saving of about 18%. For example, if the actuator has three steps, the open force can follow 20 Step curve H, shown by a dotted line. This gives a saving of approximately 26% compared to the one-stage actuator. In the example shown, the upward closing force of the pneumatic spring is approximately constant at about 14 kN, shown by line I.

25 Træk fra de to udførelsesformer kan kombineres til nye udførelsesformer, ligesom der kan foretages andre variationer inden for opfindelsens område. Det er således muligt at placere en mekanisk trykfjeder i væskekammeret for at holde positioneringsenhedens 30 cylinder og stempel i anlæg mod aktuatorstemplet og spindlen, når motoren er standset og uden hydrauliktryk. Det er også muligt at modificere udførelsesformen i fig. 5 til en totrinsaktuator ved at udelade den tredie stempeldel og recessafsnittet i skaftet.Features of the two embodiments may be combined into new embodiments, as may other variations within the scope of the invention. Thus, it is possible to place a mechanical compression spring in the fluid chamber to hold the cylinder and piston of the positioning unit 30 against the actuator piston and the spindle when the engine is stopped and without hydraulic pressure. It is also possible to modify the embodiment of FIG. 5 to a two-stage actuator by omitting the third piston part and the recess section of the shaft.

3535

Claims

26 DK 174031 B1

1. Hydraulically actuated exhaust valve (4) for an internal combustion engine with a hydraulic actuator (9) arranged coaxially in extension of the stem of the exhaust valve 5, which actuator has a stationary cylinder (31) and at least one primary pressure chamber (34) which of a control valve (17) may be connected alternately to a high pressure source of hydraulic fluid or to a reflux, as well as an actuator piston comprising at least a first piston part (40) and a second piston part (42), characterized in that a first stop on the stationary cylinder, an initial position of the first piston member determines that a positioning piston (46) and a positioning cylinder (45) 15. a positioning unit defines a liquid chamber (44) connected to the primary pressure chamber (34) via a channel which is closed when the exhaust valve (4) is open-ended, and is open when the exhaust valve is closed, that clearance between the valve stem (24) and the actuator-20 piston is offset by that the effective area of the positioning piston (46) in the positioning cylinder (45) is greater than the effective area of the actuating piston in the primary pressure chamber (34) and / or that a mechanical pressure spring in the liquid chamber (44) holds the positioning cylinder and piston of the positioning unit against the actuator. the piston and the spindle, and that the positioning unit is in power-transmitting connection with the actuator piston and the exhaust valve spindle (24) when the exhaust valve (4) is closed.

Hydraulically actuated exhaust valve according to claim 1, characterized in that an upright side wall (71) with an inclined outer side (71) is fixed to the spindle (24) which, when moving the spindle, gives signals to an electronic control unit 35 (15) activating the control valve (17) for the hydraulic actuator.

Hydraulically actuated exhaust valve according to claim 1 or 2, characterized in that the positioning cylinder (45) is located on the top of the spindle and that the positioning piston (46) is located on one of the piston parts (40, 42) of the actuator, preferably formed in one piece.

4. Hydraulically actuated exhaust valve according to one of the. claims 1-3, characterized in that the effective area of the positioning piston (46) in the positioning cylinder (45) is greater than the effective area of the actuator piston in the primary pressure chamber (34), and that the duct contains a pressure controlled check valve (54), preferably in form of a valve slide.

Hydraulically actuated exhaust valve according to one of claims 1-4, characterized in that the first piston part (40) has an annular wall, the outside of which is longitudinally displaceable in a cylinder bore (41) in the stationary cylinder (31) and whose inside constitutes 20 guide surface (43) for at least the second piston member (42), said first piston member having a radially projecting collar (63) located in an annular chamber (38) the length of which is less than the length of the outlet valve passage from closed to fully open position, and 25 whose chamber ceiling constitutes the first stop defining the initial position of the first piston part (40), that the second piston part (42) communicates with the positioning unit and that the lower end of the first piston part is above the over an upwardly facing surface of the positioning unit.

Hydraulically actuated exhaust valve according to claim 5, characterized in that the second piston part (42) is located centrally in the actuator and has an upper piston top (76) and a longitudinal shaft connecting the positioning unit to the piston top. 28 DK 174031 B1

Hydraulically actuated exhaust valve according to claim 6, characterized in that the shaft has a recess section (78) of greater axial length than the chamber (38) with the first stop and of less diameter than the shaft section (77) controlled by it. the inside of the first piston part (43), that an annular third piston part (74) projects into the recess section and protrudes into a cylindrical recess (85) in the first piston part. on the inside, and that the upper face (87) 10 of the third piston part communicates with the primary pressure chamber (34) when the exhaust valve is closed.

Hydraulically actuated exhaust valve according to any one of claims 5-7, characterized in that the first piston part (40) between its upper side and the protruding collar (63) has a radially outwardly extending chamber wall (68) with a smaller axial length than the length thereof. annular chambers, and that the chamber wall together with the protruding collar and an upper wall section of the annular chamber together with the chamber ceiling form a first damper chamber 20 when the first piston member approaches the first stop.

Hydraulically actuated exhaust valve according to claim 8, characterized in that at least the upper part (70) of the chamber wall of the first piston part (40) has a downwardly increasing diameter.

Hydraulically actuated exhaust valve according to claim 8 or 9, characterized in that in the stationary cylinder (31) there are a plurality of ducts (65) connecting the primary pressure chamber (34) with outlet openings located in the chamber ceiling and the flat rings (64) located at the outlet openings are axially displaceable between an upper position where the ring covers the outlet openings and a lower position where the ring is spaced from the outlet openings.

Hydraulically actuated exhaust valve according to one of claims 6 to 10, characterized in that a second stop restricts the downward movement of the second piston part, that the second piston part near its piston top (76) has a circular radial projection which before the second plunger portion reaches down to the second abutment passes down into a damper section of the first plunger portion and at least the upper portion (83) of the damper section on the inside of the first plunger portion (40) has decreasing diameter below.

Hydraulically actuated exhaust valve according to one of claims 7-11, characterized in that the recess section (78) of the second piston part is closed upwardly in an axially facing surface (79), that there are a plurality of channels at the upper end of the second piston part. connecting the primary pressure chamber (34) with outlet openings located in the axially facing surface and a flat ring located below the outlet openings being axially displaceable between an upper position where the ring covers the outlet openings and a lower position where the ring is spaced from outlet ports.

Hydraulically actuated exhaust valve according to one of claims 6-10, characterized in that the annular wall of the first piston part is connected to a piston top (48) which forms the end bottom of an upwardly closed secondary pressure chamber (49), wherein the second piston part 25 is positioned that a plurality of ducts (52, 53) in the annular wall connect the primary pressure chamber to a plurality of radially extending inlet ducts (51) located in the second plunger portion and that the outer surface of the second plunger portion is provided with at least one upwardly tapering end recess in the area immediately above the access channels (51).