DK148664B

DK148664B - HYDRAULIC ACTIVATION MECHANISM FOR A DISC VALVE

Info

Publication number: DK148664B
Application number: DK543182A
Authority: DK
Inventors: Erik Rosenlund Hansen
Original assignee: B & W Diesel As
Priority date: 1982-12-07
Filing date: 1982-12-07
Publication date: 1985-08-26
Also published as: DK148664C; JPH0146690B2; DK543182A; KR840007132A; JPS59113228A; KR910000667B1

Description

i 148664in 148664

Opfindelsen angår en hydraulisk aktiveringsmekanisme til åbning af en i lukkeretningen fjederbelastet tallerkenventil i en stempelmaskine, navnlig en udstødsventil i en dieselmotor. Mekanismen er 5 af den art, som omfatter en aktiveringscylinder med tilhørende stempel i drivforbindelse med tallerkenventilens spindel, en fremløbsledning fra en kilde for hydraulikvæske under højt tryk til aktiveringscylinderens arbejdskammer og en første styreventil 10 i f remløbs ledningen, en returledning fra arbe jdskamme-ret og en anden styreventil i returledningen, samt en styreenhed, der ved forudbestemte værdier af krumtapvinklen giver ordresignaler til åbning og lukning af de to styreventiler.The invention relates to a hydraulic actuating mechanism for opening a spring-loaded plate valve in a piston machine, in particular an exhaust valve in a diesel engine. The mechanism is 5 of a kind comprising an actuating cylinder and associated piston in drive communication with the plate valve spindle, a supply line from a high pressure hydraulic fluid source to the actuating cylinder's working chamber and a first control valve 10 in the belt flow line, a return line from the working chamber and a second control valve in the return line, and a control unit which, at predetermined values of the crank angle, gives order signals for opening and closing the two control valves.

15 Fra dansk patentskrift nr. 104 206 kendes en mekanisme af denne art, hvor den første og den anden styreventil er sammenbygget, således at den ene ventil åbner, når den anden lukker og omvendt. Aktiveringsstemplet består af to koaksiale og indbyrdes 20 forskydelige delstempler, af hvilke det ydre ringformede stempel har mindre slaglængde end det indre stempel. Højtryksvæsken virker da i den første del af tallerkenventilens løftebevægelse på det samlede stempelareal og i den sidste del af bevægelsen kun 25 på det indre stempel. Som følge heraf begrænses forbruget af trykvæske og dermed effektforbruget til ventilbevægelsen.15 From Danish patent specification 104,206, a mechanism of this kind is known in which the first and second control valves are assembled so that one valve opens when the other closes and vice versa. The actuating piston consists of two coaxial and 20 slidable pistons, of which the outer annular piston has less stroke than the inner piston. The high-pressure fluid then acts in the first part of the plate valve lifting movement on the total piston area and in the latter part of the movement only 25 on the inner piston. As a result, the consumption of pressure fluid and thus the power consumption is limited to the valve movement.

En aktiveringsmekanisme ifølge nærværende opfindelse er ejendommelig ved, at styreenheden er 30 programmeret til at afgive ordresignalet til lukning af den første styreventil, endnu inden tallerkenventilen er fuldt åben, og at aktiveringscylinderens arbejdskammer er sluttet til en anden kilde for hydraulikvæske, hvor trykket er lavere end i højtryks-35 kilden, gennem en anden fremløbsledning, hvori der er 2 148664 indbygget en tredje styreventil, som er indrettet til at åbne samtidig med, at den første styreventil lukker, og til at lukke, når tallerkenventilen er fuldt åben.An actuating mechanism according to the present invention is characterized in that the control unit is programmed to output the order signal for closing the first control valve even before the plate valve is fully open and that the actuating cylinder's working chamber is connected to another source of hydraulic fluid where the pressure is lower than in the high-pressure source, through a second supply line, in which is installed a third control valve, which is adapted to open at the same time as the first control valve closes and to close when the plate valve is fully open.

5 Virkemåden af en mekanisme ifølge opfindelsen afviger fra den omtalte kendte mekanismes virkemåde ved, at tallerkenventilen i den indledende del af sin løftebevægelse får en så høj acceleration og tilsvarende kinetisk energi, at den resterende del af 10 bevægelsen kan gennemføres helt uden yderligere tilførsel af energi. Det relativt lave tryk i den anden kilde skal blot være højt nok til at sikre efterfyld-ning af aktiveringscylinderens arbejdskammer under den afsluttende del af løftebevægelsen. Mekanismens 15 konstruktion er også betydelig enklere b.a. fordi der anvendes et simpelt, udelt aktiveringsstempel. Endvidere er det muligt, ved ændring af tidspunktet for ordresignalet til lukning af den første styreventil, at tilpasse størrelsen af kraftimpulsen fra højtryks-20 væsken efter varierende driftsforhold, såsom et belastningsafhængigt gastryk i en motorcylinder, og derved opnå minimalt effektforbrug i mekanismen ved forskellige motorbelastninger.The operation of a mechanism according to the invention differs from the operation of the said known mechanism in that the plate valve in the initial part of its lifting movement has such a high acceleration and corresponding kinetic energy that the remaining part of the movement can be carried out completely without further supply of energy. . The relatively low pressure in the second source just needs to be high enough to ensure replenishment of the actuating cylinder's working chamber during the final portion of the lifting movement. The construction of the mechanism is also considerably simpler, e.g. because a simple undivided activation stamp is used. Furthermore, by changing the timing of the order signal for closing the first control valve, it is possible to adjust the magnitude of the power pulse from the high pressure fluid to varying operating conditions, such as a load-dependent gas pressure in a motor cylinder, thereby obtaining minimal power consumption in the mechanism at different engine loads. .

Den nævnte tilpasning af kraftimpulsens stør-25 relse kan i en foretrukket udførelsesform opnås ved hjælp af en første detektor, som registrerer ventiltallerkenens maksimale løft og giver et indgangssignal til styreenheden, som i afhængighed heraf udfører en eventuelt nødvendig korrektion af tidspunktet for 30 ordresignalet til lukning af den første styreventil. Korrektionen består i, at styreventilens lukning forsinkes, hvis tallerkenventilen i en forudgående løftebevægelse ikke nåede en ønsket maksimal åbning (som eventuelt kan være belastningsafhængig) og om-35 vendt fremskyndes, hvis løftebevægelsen var større end ønskeværdien.Said adjustment of the magnitude of the power pulse can be achieved in a preferred embodiment by means of a first detector which records the maximum lift of the valve plate and provides an input signal to the control unit which, as a result, performs a necessary correction of the timing signal for closing. of the first control valve. The correction consists in delaying the closing of the control valve if the plate valve in a prior lifting movement did not reach a desired maximum opening (which may be load dependent) and vice versa if the lifting movement was greater than the desired value.

3 1486643 148664

Mekanismen kan have en anden detektor, som registrerer, at tallerkenventilen er løftet fra sit sæde og giver et indgangssignal til styreenheden, som i afhængighed heraf udfører en eventuel nødvendig 5 korrektion af tidspunktet for ordresignalet til åbning af den første styreventil. Med denne foranstaltning kan det sikres, at ventilløftet altid begynder ved den ønskede krumtapvinkel, uanset den eventuelt varierende og mere eller mindre uberegnelige længde af 10 intervallet mellem ordresignalet fra styreenheden og den faktiske begyndelse af tallerkenventilens løftning.The mechanism may have a second detector which detects that the disc valve is lifted from its seat and provides an input signal to the control unit which, as a result, performs any necessary correction of the timing of the order signal for opening the first control valve. By this measure, it can be ensured that the valve lift always starts at the desired crank angle, regardless of the possibly varying and more or less erratic length of the interval between the order signal from the control unit and the actual beginning of the plate valve lifting.

Når lukkefjederen er en pneumatisk fjeder, kan dens arbejdskammer være sluttet til et trykluft-15 reservoir via en i retning mod kammeret åbnende kontraventil, og styreenheden kan være indrettet til at justere trykket i reservoiret i afhængighed af stempelmaskinens driftsparametre. Herved er det muligt at influere på forløbet af tallerkenventilens åbning og 20 lukning, idet et højere begyndelsestryk i den pneumatisk fjeder giver en stivere fjeder og dermed hurtigere åbning - når størrelsen af kraftimpulsen på aktiveringsstemplet forøges tilsvarende - og lukning af ventilen.When the closing spring is a pneumatic spring, its working chamber may be connected to a compressed air reservoir via a check valve opening towards the chamber and the control unit may be adapted to adjust the pressure in the reservoir depending on the piston machine operating parameters. Hereby it is possible to influence the course of the plate valve opening and closing, since a higher initial pressure in the pneumatic spring gives a stiffer spring and thus faster opening - when the magnitude of the force pulse on the actuating piston increases accordingly - and closing the valve.

25 Opfindelsen forklares i det følgende nærmere under henvisning til tegningen, på hvilken fig. 1 viser et skema over en udførelsesform for en aktiveringsmekanisme ifølge opfindelsen, fig. 2 et muligt tidsforløb af ventilløftet 30 og det hydrauliske tryk i aktiveringscylinderen samt åbningen og lukningen af styreventilerne, og fig. 3 et skematisk billede af styreenheden med tilhørende indgående og udgående signalledninger.The invention will now be explained in more detail with reference to the drawing, in which 1 shows a diagram of an embodiment of an activation mechanism according to the invention; FIG. 2 shows a possible time course of the valve lift 30 and the hydraulic pressure in the actuating cylinder as well as the opening and closing of the control valves; and FIG. 3 is a schematic view of the controller with associated input and output signal lines.

4 148664 I fig. 1 er med henvisningstallet 1 rent skematisk vist en cylinder med tilhørende topstykke i en stempelforbrændingsmotor, f.eks. en længdeskyllet dieselmotor med udstødsventil i topstykket. Ud-5 stødsventilen 2, der er vist i delvis åben stilling, omfatter en ventiltallerken 3, som samvirker med et sæde 4 i topstykket til styring af en udstrømningspassage 5 fra cylinderens forbrændingskammer 6.In FIG. 1, reference numeral 1 is a schematic representation of a cylinder and associated cylinder head in a piston combustion engine, e.g. a long-flush diesel engine with exhaust valve in the cylinder head. The ejector 5 valve 2 shown in the partially open position comprises a valve plate 3 which cooperates with a seat 4 in the head to control an outflow passage 5 from the combustion chamber 6 of the cylinder.

Til den øverste ende af ventilen 2's spindel 10 7 er fastgjort et aktiveringsstempel 8, som er tætsluttende forskydeligt i en hydraulisk aktiveringscylinder 9. Til det på stemplet 8's overside afgrænsede arbejdskammer 10 i cylinderen 9 er sluttet en ledning 11, gennem hvilken hydraulikvæske 15 kan strømme til og fra arbejdskammeret 10.Attached to the upper end of the valve 2 7 of the valve 2 is an actuating piston 8 which is tightly slidable in a hydraulic actuating cylinder 9. A conduit 11 through which hydraulic fluid 15 can flow through the upper chamber defined on the upper side of the piston 8 is connected. to and from the work chamber 10.

Til ventilspindlen 7 er endvidere fastgjort et stempel 12, som er tætsluttende forskydeligt i en cylinder 13, og som på sin underside afgrænser et arbejdskammer 14, der gennem en ledning 15 20 er sluttet til en trykluftbeholder 16. Ledningen 15 indeholder en kontraventil 17, der åbner i retning mod arbejdskammeret 14.To the valve stem 7 is furthermore attached a piston 12 which is tightly slidable in a cylinder 13 and which defines on its underside a working chamber 14 which is connected through a conduit 15 20 to a compressed air container 16. The conduit 15 contains a check valve 17 which opens towards the working chamber 14.

En kilde 18 for hydraulikvæske ved højt tryk, f.eks. en hydropneumatisk trykakkumulator, er gennem 25 en ledning 19 sluttet til tilgangsporten af en hurtigåbnende styreventil 20, f.eks. en pilotstyret solenoideventil, og ledningen 11 er sluttet til styreventilen 20's afgangsport. En fra ledningen 11 udgående grenledning 21 er sluttet til tilgangs-30 porten af en anden hurtigåbnende styreventil 22, hvis afgangsport gennem en ledning 23 er sluttet til en kilde 24 for hydraulikvæske, hvori der opretholdes et overtryk, som er væsentlig lavere end trykket i kilden 18. Væskekilden 24 er i strøm- 5 148664 ningsforbindelse med kilden 18 gennem en ledning 25, som indeholder en pumpe 26, der tilvejebringer den omtalte trykforskel.A source 18 for high pressure hydraulic fluid, e.g. a hydropneumatic pressure accumulator, through a conduit 19 is connected to the inlet port of a quick-opening control valve 20, e.g. a pilot controlled solenoid valve and the conduit 11 is connected to the outlet port 20 of the control valve. A branch line 21 extending from the conduit 11 is connected to the inlet port of another fast-opening control valve 22, the outlet port of which is connected through a conduit 23 to a source 24 for hydraulic fluid, maintaining an overpressure substantially lower than the pressure in the source. 18. The liquid source 24 is in flow communication with the source 18 through a conduit 25 which contains a pump 26 which provides the pressure difference referred to.

Væskeledningerne 11 og 23 er i indbyrdes 5 forbindelse gennem endnu to ledninger 27 og 28, af hvilke ledningen 27 indeholder en styreventil 29 af lignende konstruktion som ventilerne 20 og 22, medens ledningen 28 indeholder en kontraventil 30, der åbner i retning mod det hydrauliske arbejds-10 kammer 10. Mellem ventilen 29 og tilslutningen til ledningen 23 indeholder ledningen 27 endvidere et, fortrinsvis indstilleligt, drøvleorgan 31.The fluid conduits 11 and 23 are interconnected through two more conduits 27 and 28, of which conduit 27 contains a control valve 29 of a similar construction to valves 20 and 22, while conduit 28 contains a non-return valve 30 which opens in the direction of the hydraulic work. The chamber 27 further includes a, preferably adjustable, throttle member 31 between the valve 29 and the connection to the conduit 23.

En til trykluftbeholderen 16 sluttet pumpe 32 sørger for opretholdelse af et ønsket lufttryk i 15 beholderen, og størrelsen af dette tryk kan ændres fra den nedenfor beskrevne elektroniske styreenhed ved hjælp af et styresignal, som føres til pumpen 32 gennem en signalledning 33. Gennem en signalledning 34 kan styreenheden give et ordresignal 20 til væskepumpen 26 med henblik på at opretholde ønskede værdier af væsketrykket i de to trykkilder 18 og 24. Fra styreenheden udgår endvidere signalledninger 35, 36 og 37 for overføring af ordresignaler til åbning og lukning af ventilerne, hen-25 holdsvis 20, 22 og 29.A pump 32 connected to the compressed air container 16 provides for maintaining a desired air pressure in the container and the magnitude of this pressure can be changed from the electronic control unit described below by means of a control signal which is fed to the pump 32 through a signal line 33. Through a signal line 33 34, the control unit may provide an order signal 20 to the liquid pump 26 in order to maintain desired values of the fluid pressure in the two pressure sources 18 and 24. Furthermore, the control unit emits signal lines 35, 36 and 37 for transmitting order signals for opening and closing the valves. 25, 20, 22 and 29, respectively.

En til det pneumatiske stempel 12 fastgjort stang 38 påvirker en stationær detektor 39, som derved kontinuerligt (analogt) registrerer positionen af ventilen 2 i forhold til dens sæde 4 og 30 afgiver et hertil svarende positionssignal gennem en signalledning 40 til styreenheden.A rod 38 attached to the pneumatic piston 12 actuates a stationary detector 39, thereby continuously (analogously) detecting the position of the valve 2 relative to its seat 4 and 30, delivering a corresponding position signal through a signal line 40 to the controller.

Ved en flercylindret motor vil luftbeholderen 16 og væskebeholderne 18 og 24 samt signalledningerne 33 og 34 være fælles for hele motoren, medens 6 148664 det viste arrangement af luft- og væskeledninger med . tilhørende ventiler, signalledninger og positionsdetektor er gentaget i forbindelse med hver motorcylinder . Dette er i fig. 1 skematisk antydet ved kor-5 te ledningsstykker mærket henholdsvis 15', 19' og 23*.In a multi-cylinder engine, the air reservoir 16 and the liquid reservoirs 18 and 24, as well as the signal lines 33 and 34, will be common to the entire engine, while the arrangement of air and liquid lines shown. associated valves, signal lines and position detector are repeated in connection with each engine cylinder. This is shown in FIG. 1 is schematically indicated by short wires marked 15 ', 19' and 23 * respectively.

Fig. 2 anskueliggør i kurveform funktionen af den beskrevne aktiveringsmekanisme i forbindelse med åbning og lukning af ventilen 2. Tiden t er afsat 10 . som abscisse, og øverst i fig. 2 er som ordinat afsat henholdsvis ventilens løftehøjde repræsenteret af en kurve 41 og det hydrauliske tryk i arbejds-kammeret 10 repræsenteret af en kurve 42. tinder disse to kurver er åbnings- og lukningstidspunkterne 15 for de tre styreventiler 20, 22 og 29 vist.FIG. 2 illustrates in curve form the function of the described actuation mechanism in connection with opening and closing the valve 2. The time t is allocated 10. as abscissa, and at the top of fig. 2, as the ordinate is plotted, respectively, the lifting height of the valve represented by a curve 41 and the hydraulic pressure in the working chamber 10 represented by a curve 42. If these two curves are shown, the opening and closing times 15 for the three control valves 20, 22 and 29 are shown.

Til tidspunktet t ligger ventiltallerkenen 3 an mod sædet 4 under påvirkning af lufttrykket i kammeret 14, og de tre styreventiler 20, 22 og 29 er alle lukket. Trykket i arbejdskammeret 10 er 20" i det væsentlige lig med trykket i mellemtrykskilden 24. Til tidspunktet t^ modtager ventilen 20 gen-.nem sin signalledning 35 et ordresignal til åbning, og herved stiger trykket i kammeret 10 hurtigt op til eh maksimumværdi svarende til trykket i højtryks-25 kilden 18. Udstødsventilen. 2 begynder at åbne med gradvis voksende hastighed, betinget dels af det høje tryk på aktiveringsstemplet 8, dels af faldet i det modtryk, som forbrændingsgasserne i forbrændings-kammeret 6 udøver på ventiltallerkenen 3, Til tids-30 punktet . modtager styreventilen 20 ordresignal til lukning, hvorved trykket i arbejdskammeret 10 falder brat, og som følge heraf åbner kontraventilen 30, således at der nu strømmer hydraulikvæske ind i U8666 7 arbejdskammeret 10 fra mellemtrykskammeret 24. Ventilen 2 fortsætter sin løftebevægelse i kraft af den kinetiske energi, som den modtog i ventilen 20's åbningsperiode, og indstrømningen af væske fra kamme-5 ret 24 sker i takt med ventilbevægelsen. Som følge af det pneumatiske modtryk i kammeret 14 og gastrykket i forbrændingskammeret 6 aftager ventilen 2's hastighed, indtil dens bevægelse til sidst standser. Kontraventilen 30 træder da i funktion til at 10 fastholde ventilen 2 i åben stilling, eftersom den hindrer udstrømning af væske fra kammeret 10.At time t, the valve plate 3 abuts the seat 4 under the influence of the air pressure in the chamber 14, and the three control valves 20, 22 and 29 are all closed. The pressure in the working chamber 10 is 20 "substantially equal to the pressure in the intermediate pressure source 24. At the time t, the valve 20 receives through its signal line 35 an order signal for opening, thereby increasing the pressure in the chamber 10 to a maximum value corresponding to the pressure in the high pressure source 18. The exhaust valve 2 starts to open at a gradually increasing rate, partly due to the high pressure on the actuating piston 8 and partly to the decrease in the back pressure exerted by the combustion gases in the combustion chamber 6 on the valve plate 3. The control valve 20 receives an order signal for closing, whereby the pressure in the working chamber 10 drops abruptly, and as a result, the check valve 30 opens, so that hydraulic fluid now flows into the working chamber 10 from the intermediate pressure chamber 24. The valve 2 continues its lifting movement in force. of the kinetic energy which it received during the opening period of valve 20 and the flow of liquid from chamber 24 occurs with tilbevægelsen. Due to the pneumatic back pressure in the chamber 14 and the gas pressure in the combustion chamber 6, the velocity of the valve 2 decreases until its movement eventually stops. The check valve 30 then functions to hold the valve 2 in the open position, since it prevents the flow of liquid from the chamber 10.

Ventilen 2's lukkebevægelse indledes ved, at styreventilen 22 til tidspunktet t3 modtager ordresignal til åbning gennem sin signalledning 36.The closing movement of the valve 2 is initiated by the control valve 22 receiving, at time t3, an order signal for opening through its signal line 36.

15 På samme tid - eller eventuelt senere, men dog medens ventilen 22 stadig er åben - får ventilen 29 ordresignal til åbning gennem sin signalledning 37. Under påvirkning af de førnævnte opadrettede kræfter begynder ventilen 2 nu sin lukkebevægelse mod 20 det i kammeret 10 herskende, relativt lave overtryk lig med trykket i væskekilden 24. Inden ventilen 2 er fuldt lukket, lukkes ventilen 22 til tidspunktet t^, hvorefter væske nu kun kan strømme ud fra kammeret 10 gennem ledningen 27 med drøv-25 leorganet 31. Herved sker der en forbigående stigning af trykket i kammeret 10 og en tilsvarende hydraulisk afbremsning eller dæmpning af lukkebevægelsen, indtil ventiltallerkenen 3 igen ligger mod sit sæde 4. Når ventilen 2 er helt lukket, lukkes 30 også styreventilen 29 til tidspunktet t^.At the same time - or possibly later, but while valve 22 is still open - valve 29 receives an order signal for opening through its signal line 37. Under the influence of the aforementioned upward forces, valve 2 now begins its closing movement toward 20 prevailing in chamber 10. relatively low overpressures equal to the pressure in the liquid source 24. Before the valve 2 is fully closed, the valve 22 is closed to the time t 2, after which liquid can now only flow out of the chamber 10 through the conduit 27 with the throttle member 31. A transient increasing the pressure in the chamber 10 and a corresponding hydraulic braking or damping of the closing movement until the valve plate 3 is again against its seat 4. When the valve 2 is fully closed, the control valve 29 is also closed at the time t ^.

Fig. 3 viser rent skematisk den for hele motoren fælles styreenhed 43 med tilhørende signalledninger for indgangs- og udgangssignaler. Som styreenhed kan anvendes en mikrocomputer eller mikro-35 processor, der er forprogrammeret til at optimere 148664 - 8 forløbet af ventilerne 2's bevægelser, herunder deres åbnings- og lukningstidspunkter og det maksimale ventilløft, i afhængighed af relevante parametre for motorens drift, eksempelvis dens omdrej-5 ningstal, belastning, og/eller ladetryk samt omdrejningstallet for motorens turboladere. yindlæsningen af de nævnte driftsparametre i - styreenheden 43 er i fig. 3 symboliseret ved en enkelt, indgående signalledning 44. Gennem en anden 10 indgående signalledning 45 modtager styreenheden løbende information om den aktuelle krumtapvinkel, som er udgangspunktet for fastlæggelsen af åbnings-og lukningstidspunkterne for de enkelte ventiler 2.FIG. 3 is a schematic representation of the control unit 43 common to the entire motor with associated signal lines for input and output signals. As a control unit, a microcomputer or micro-processor pre-programmed to optimize the course of the movements of the valves 2, including their opening and closing times and the maximum valve lift, may be used, depending on relevant parameters for the operation of the motor, for example its rotation. -5 speed, load, and / or charge pressure as well as the speed of the engine's turbochargers. the input of said operating parameters into the control unit 43 is shown in FIG. 3, symbolized by a single incoming signal line 44. Through another 10 incoming signal line 45, the controller receives continuous information about the current crank angle, which is the starting point for determining the opening and closing times of the individual valves 2.

Endelig modtager styreenheden indgangssignaler gen-15 nem de før omtalte signalledninger 40, hvoraf der som nævnt findes én i forbindelse med hver motorcylinder til angivelse af ventilen 2's øjeblikkelige position.Finally, the controller receives input signals through the previously mentioned signal lines 40, one of which, as mentioned, is associated with each motor cylinder to indicate the instantaneous position of valve 2.

Ved forarbejdning af de omtalte indgangssigna-20 ler frembringer styreenheden 43 dels udgangssignaler til hver enkelt motorcylinders styreventiler 20, 22 og 29 gennem de ovenfor omtalte signalledninger 35, 36 og 37. Pra styreenheden udgår endvidere de ligeledes ovenfor omtalte signalledninger 33 og 34 25 ’ til styring af henholdsvis af luftpumpen 32 og væskepumpen 26.In processing the aforementioned input signals 20, the control unit 43 partly produces output signals for each motor cylinder control valves 20, 22 and 29 through the above mentioned signal lines 35, 36 and 37. The control unit further extends the signal lines 33 and 34 25 'also referred to above. control of the air pump 32 and the liquid pump 26 respectively.

Styreenheden 43 kan være en analog eller digital enhed, og tilsvarende kan de tilførte indgangssignaler være analoge eller digitale. Eksempelvis 30 kan den analoge detektor 39 erstattes af to eller flere digitale detektorer, af hvilke den ene regi-- strerer et begyndende ventilløft (f.eks. af størrelsesordenen 1-2 mm), medens den eller de øvrige registrerer, om ventilens maksimale løft stemmer 35 overens med den ønskede værdi.The control unit 43 may be an analog or digital unit, and correspondingly the input signals supplied may be analog or digital. For example, the analog detector 39 may be replaced by two or more digital detectors, one of which records a starting valve lift (e.g., of the order of 1-2 mm) while the other (s) record the maximum lift of the valve 35 matches the desired value.

9 1486649 148664

Praktisk anvendelige værdier af de hydrauliske tryk i mekanismen kan være 200-300 bar i højtrykskilden 18 og omkring 10 bar i mellemtrykskilden 24. Afhængigt af den pneumatiske cylinder 131 s diameter 5 og den ønskede stivhed af lukkefjederen kan lufttrykket i beholderen 16 ligge på 5-10 bar.Practically applicable values of the hydraulic pressures in the mechanism may be 200-300 bar in the high pressure source 18 and about 10 bar in the medium pressure source 24. Depending on the diameter 5 of the pneumatic cylinder 131 and the desired stiffness of the closing spring, the air pressure in the container 16 may be 5- 10 bar.

Claims

148664

A hydraulic actuating mechanism for opening a spring-loaded plate valve (2) in a piston machine, in particular an exhaust valve in a diesel engine, comprising an actuating cylinder (9) and associated piston (8) in drive with the plate valve spindle (7), supply line (19, 11) from a high pressure hydraulic fluid source (18) for actuation cycle. 10 the working chamber (10) of the winder and a first control valve (20) in the flow line, a return line (21, 23) from the working chamber and a second control valve (22) in the return line, and a control unit (43) which at predetermined 15 values of the crank angle gives order signals for opening and closing the two control valves (20, 22), characterized in that the control unit (43) is programmed to output the order signal for closing the first control valve (20), even before the plate-valve (2) is full open, and that the actuating cylinder working chamber (10) is connected to a second source (24) for hydraulic fluid, where the pressure is lower than that of the high pressure source (18), through a second supply line (23, 28), in which 25 a third control valve is incorporated. (30) which is adapted to open at the same time as the first control valve (20) closes and to close when the disc valve (2) is fully open.

Mechanism according to claim 1, characterized in that a first detector (39) for the maximum lift of the valve plate (3) gives an input signal to the control unit (43) which, if necessary, produces a necessary correction of the time. (t2) for the order signal for closing the first control valve (20).

3. A mechanism according to claim 2, characterized in that a second detector (39) detects that the disc valve (2) is lifted from its seat (4) and provides an input signal to the control unit (43) which, as a result, performs any necessary correction of the timing (t ^) of the order signal for opening the first control valve (20).

Mechanism according to claim 3, characterized in that the first and second detectors are a common analog detector (39) which continuously records the position of the valve plate (3) in relation to its seat (4).

Mechanism according to any one of claims 1-4, characterized in that the third control valve (30) is a non-return valve which opens in the direction towards the working chamber (10) of the actuating cylinder,

Mechanism according to any one of claims 1-5, characterized in that the return line (21, 23) from the working chamber (10) is connected to the second source (24).

Mechanism according to any one of claims 1-6, 25, characterized in that a second return line (27) containing a throttle member (31) and a fourth control valve (29) is provided from the actuating cylinder (10) and the control unit (29). 43) provides an order signal for opening this valve (29) 30 simultaneously or slightly later than the signal for opening. the second control valve (22).

A mechanism according to any one of claims 1-7, wherein the closing spring is a pneumatic spring, characterized in that the working chamber of the closing spring