Motor termic adaptiv

[WLF]

Daca proiectul este cu adevarat viabil, ai putea sa il contactezi pe inginerul de la Arena Leilor, nu mai tin minte numele lui, dar este cel care a brevetat acel scaner pentru TIR-uri. Cu siguranta te-ar ajuta daca proiectul este ok.

[AL2012]

Si mai este ceva ...

Multi zic ca viitorul motorului cu ardere interna este pesimist avand in vedere terminarea rezervelor de combustibili fosili si ca viitorul este al motoarelor electrice .

Bun - este o tehnologie curata dar ce te faci cu actionarea utilajelor agricole, de constructii acolo unde se cer puteri mari si nu ai posibilitati de incarcare a bateriilor electrice ?

Cunosc preocupari ale unor firme de a dezvolta noi combustibili sintetici care sa inlocuiasca combustibilii fosili.

Asa ca proiectul meu are un viitor prin dezvoltarea conceptului de economie a combustibilului prin variatia raportului de compresie si a cilindreei, precum si prin utilizarea de combustibili diferiti pe acelasi motor

[WLF]

Mircea Tudor, proprietarul MB Telecom. http://www.capital.ro/detalii-articole/stiri/roboscan-zboara-spre-nivelul-urmator-172079.html

[AL2012]

L-am contactat pe M T(am acord de confidentialitate semnat) si pe altii de la Arena Leilor, dar, dorind sa dezvoltam intreg know-how, s-a speriat de cat a investit Peugeot ...

[DYC88]

Nu am acum timp sa ma uit la documentatia prezentata de tine, insa tot ce pot spune este ca un moderator ar trebui sa curete poluarea facuta de unii membrii pe acest topic care prezinta niste inovatii si cere un solicita un sprijin legal.

[AL2012]

Ai dreptate stimate domn ... chiar in lipsa documentarii ... si-ti onorezi deviza !!! Edited December 2, 2012 by AL2012

[Calin SL]

Draga domnule,

 

Mai ramane decat sa le facem ....

 

 

mai ramane doar sa le facem

***succes cu proiectul !!!***

[Similea]

Dyc, pentru mine poluant e unul care habar n-are sa scrie. Iar abuzul de i-uri este ....

Hm. Cum se face ma ca tocmai voi sunteti cei mai virulenti?

 

In plus, mie, care in viata reala nu sunt chiar un jalon ca multi dintre voi, nu-mi inspira deloc incredere un ...inventator care cere bani pe forumuri. Cata vreme vii sa CERI, atitudinea asta condescendenta este cel putin hilara. Cum la fel de hilar e modul in care unul ca tine, Dyc, care nu stie ce se ascunde in spatele povestii asteia, vine agresiv si tipa in sprijinul unei fete morgana, numai ca sa aiba ceva de spus. Paradoxal, chiar de-ai vrut sa ajuti, mai rau ai facut.

 

Cata vreme postezi pe forum si ceri lovele... iti asumi si intrebarile. Ca foar nu-mi faci nicio favoare.

[BOASKA]

nu ai timp sau nu te pricepi?

atata timp cat se scrie la subiect si nu se vorbeste ca in rahova nu vad de ce sa stearga posturile celor pe care tu nu-i suporti

 

daca credeti ca prin marirea raportului de compresie obtineti altceva in afara de topirea si griparea motorului, supraincalzirea excesiva, pierderea drastica de putere respectiv a randamentului,scaderea plansei de turatie,posibilitatea reinversarii sensului de mers al motorului nu aveti nimic de-a face cu tehnica

calculul randamentului se face dupa formule si functioneaza da?

un front de detonare haotic poate distruge motorul,gazele mai tb si evacuate, cine stie despre transformarile adiabatice din capitolul de mecanica si ceva despre tuningul auto, remapari isi poate da seama clar ca o modificare mai mare de 1-2% al parametrilor poate avea efecte directe asupra fiabilitatii motorului

odata cu marirea compresiei creste posibilitatea de creare a detonatiilor, o ardere uscata si cate altele

si mie mi se pare corect sa-si expuna proiectele dar nu st de acord ca burzuleste pe toti care nu vor sa-i dea bani si au alte pareri

[DYC88]

@ Similea, ultimul post al lui Boaska da si niste explicatii insa in primele posturi sunt niste mistouri care izgonesc multe persoane din comunitate.

Tu nu ai avut contact in viata reala cu fosti/actuali membri care au renuntat la BMWClub sau stau si doar privesc fara sa se implice numai din cauza catorva care nu fac decat sa ia la misto orice initiativa. In cazul de fata nu este un topic gen tata urs/mers serpuit etc...

 

@Boaska, am suficiente cunostiinte incat sa inteleg ceea ce sugerezi tu, poate daca spuneai asta din primul post si nu sa proiecteze o clanta se intelegea altceva.

[AL2012]

Pentru dl BOASCA ca-i mai "priceput" pe tehnica

Daca nu pricepe si se considera in continuare mai destept decat toti astia de mai jos, atunci sa revina dar nu prea repede ca mi s-au gatat "gloantele" = nr de postari

 

AVANTAJE VCR&VCC

 

Variable Compression Ratio Technology for CO2 Reduction of Gasoline Engines in Passenger Cars

Project VCR

European Commision 2002

Three different VCR solutions, the Controlled Crankshaft Positioning – VCR, the Variable Connecting Rod and the Alvar-VCR were manufactured and tested in 1-cylinder engines.

Out of the engine test results depending on the technology used up to 9 % fuel saving can be reached out of running the engine with the optimal compression ratio under all load and speed conditions.

Additional to up 18 % fuel saving can be reached by reducing the engine displacement for about 40 % but keeping torque and performance constant by high boosting. The base for comparison is an engine with 3 L displacement. So, overall a fuel consumption reduction up to 27 % is visible with the new technology without disadvantage in drivability, pollutant emissions and with only moderate production cost increase.

 

Performance Analysis of Variable Compression Ratio Engine using Diesel

K.Manikanta1, K.Anil2, B.Manoj Prabhakar3

1,2,3 MVGR College of Engineering/Mechanical Engineering, Vizianagaram, India.

manikathala@gmail.com

anilkalangi@gmail.com

shiny_hawkins@yahoo.co.in

Proc. of. Int. Conf. on Advances in Mechanical Engineering 2010

In the current study an attempt is made to find an optimum compression ratio for diesel engine with diesel oil. With respect to brake power the optimum compression ratio was found as 17. But with respect to brake thermal efficiency and specific fuel consumption the optimum compression ratio is found to be 18. Therefore it is understood that the optimum compression ratio for the current diesel engine will be around 17.5. The volumetric efficiency of the diesel engine is varies by 1% with different compression ratios. The air fuel ratio of the engine is in the range of 45:1 to 15:1 between the compression ratios 15 to 19.

 

Concept Development of a Variable Compression Ratio Engine Using TRIZ

Hong-Wook Lee, Won Gyu Kim, Jin Woo Cho, Myung Rae Cho, Sang Hee Lee

Hyundai•Kia Motor Company

Effect of Variable Compression Ratio

VCR+Turbo Engine improves 20~30% of Fuel Consumption in comparison with the same power of NA Engine.

 

Fundamental Research in Russia on Development of Engines with Variable Compression Ratio

The value of this experience is in the fact that practically for the first time were shown possibilities of drastic increase of engine power density, maintaining its economy and providing minimum fuel consumption while engine running on low and average loads.

Engineering decisions and ways of regulation for engine compression ratio can be different, however it’s undoubtedly, that this trend can really improve fuel economy and exhaust emission by 20 – 30%.

 

Demonstrating the Performance and Emission Characteristics of a Variable Compression Ratio, Alvar- Cycle Engine

Olof Erlandsson, Gunnar Lundholm, Fredrik SĂśderberg and Bengt Johansson

Lund Institute of Technology, Sweden

Victor W. Wong

Massachusetts Institute of Technology, U.S.A.

SAE TECHNICAL PAPER SERIES 982682

The results indicate that at part load, high compression ratio, a relatively high increase in efficiency can be achieved and this without any direct increase in emissions.

A further study in this field, and especially high compression ratio and its effect on EGR –tolerance together with EGR and its effect on the knock limit, would be very interesting. Information from such tests would be very valuable when optimizing an engine for efficiency.

• Variable compression ratio renders a possibility for increasing the efficiency at part load conditions.

• At high compression ratio: It is not critical in terms of efficiency if the spark advance has to be reduced from MBT timing to avoid knock. It will bring the benefits of lower NOx – emissions.

• Variable compression ratio gives a possibility to increase the maximum power output through lower compression ratio and high boost pressure.

• The Alvar engine is a possibility in achieving variable compression ratio and it has shown to give the expected benefits of such a engine.

• The Alvar engine does not give higher HC-emissions than a standard engine, contrary to what was expected.

 

CHANGING THE SQUEEZE

The technologies and control of variable compression ratio engines.

by Julian Edgar

http://www.autospeed.com/A_110204/cms/article.html

An engine with a higher compression ratio is more efficient - it gains more energy from the fuel being burnt. However, like all good things, there is a limit to how far the compression ratio (CR) can be increased before the disadvantages start to more than offset the advantages. Specifically, an engine with a CR above about 11-12:1 starts to suffer because the ignition timing has to be pulled back in order that detonation is avoided.

However, that's at full throttle - but at part-throttle the situation's very different. Because the volumetric efficiency (the amount of air that is breathed by the engine each intake stroke, compared with its capacity) dramatically drops at part-throttle, the combustion pressures are also much lower. This means the CR and ignition timing detonation limits that apply at wide open throttle no longer apply at part throttle.

Simply put, at part-throttle an engine can have a much higher compression ratio and/or more advanced ignition timing than at full-throttle. Given that the vast majority of car use is at part-throttle, an efficiency boost created by a higher CR during part-throttle operation results in real-world improvements in fuel consumption and CO2 emissions.

Engines with variable compression ratios have the potential to improve engine efficiency in real-world conditions. Further, they can be teamed with high-boost forced induction to allow the downsizing of engines without a reduction in power or efficiency. Finally, coming technologies such as combined starter/generators - which can provide electric assist at low road speeds - combine well with turbocharged variable CR engines, where low-rpm boost is not available.

 

MAYFLOWER'S VARIABLE ENGINE TECHNOLOGY

http://www.sae.org/automag/techbriefs/01-2002/page2.htm

It is called the Mayflower e3 Variable Motion Engine, and it could bring a new dimension to the efficiency of the internal-combustion engine, say its inventors and developers. Mayflower Corp., a British automotive and specialist engineering and manufacturing company, with operations in the UK, Continental Europe, Asia, and North America, claims that initial test results indicate a fuel-consumption improvement of 40%, with a 50% reduction in emissions. Variable compression ratio and engine "capacity on demand" are other elements of the technology.

 

Benefits and Challenges of Variable Compression Ratio (VCR)

Martyn Roberts

Prodrive Ltd

Copyright © 2002 Society of Automotive Engineers, Inc.

VARIABLE CAPACITY

As indicated earlier, some VCR designs (e.g. Mayflower, fig 9) combine variation in stroke with variation in CR either as a by-product of the geometry change or a stated aim of the mechanism.

The potential change in swept volume is limited by crankshaft geometry at one extreme and engine silhouette at the other ; practical VCR devices are unlikely to enable capacity changes greater than 20% which falls well short of the 50% achieved by cylinder de-activation.

Unless more extreme variations in capacity can be engineered, downsized engines are still likely to require pressure charging to meet customer expectations for WOT performance. In such circumstances, there appears to be little justification for variation in capacity.

VCR offers the largest potential improvement in part throttle fuel efficiency and CO2 emissions when compared to other competing technologies, if applied to highly pressure-charged downsized engines.

VCR is highly synergistic with FAS/CSG systems which can offer torque enhancement at low rpm when boost systems are least effective. FAS/CSG systems can also provide a 42v power source for VCR actuation hardware.

The main obstacles to adoption of VCR are incompatibility with major components in current production and difficulties of combining VCR and non- VCR manufacturing within existing plant. As environmental pressure on the automobile increases and investment plans for new products are put in place, the justification for VCR will become more evident.

 

Grant: Autoturism echipat cu motor cu raport de comprimare variabil (VCR)

http://www.scritube.com/tehnica-mecanica/Grant-Autoturism-echipat-cu-mo2151614912.php

Raport de Cercetare

Grant: Autoturism echipat cu motor cu raport de comprimare variabil (VCR)

Autor: CLENCI ADRIAN CONSTANTIN

Universitatea: UNIVERSITATEA din PITESTI

O caracteristica importanta a motoarelor de automobil este marea varietate a regimurilor de functionare. Printre acestea, regimurile de sarcini mici si mijlocii au un rol esential, deoarece functionarea la aceste regimuri este definitorie pentru economicitatea motorului. Din nefericire, la aceste regimuri randamentul termic este mult diminuat ĂŽn comparatie cu cel ĂŽnregistrat la sarcina plina. Ăn concluzie, ar trebui cautate solutiile constructive care actioneaza ĂŽndeosebi ĂŽn zona acestor regimuri, pentru a determina o crestere a randamentului termic.

Ăn cazul motoarelor cu aprindere prin scĂŽnteie, controlul cantitativ al sarcinii prin obturarea canalului de admisie determina nu numai pierderile prin pompaj dar si micsorarea raportului real de comprimare al gazelor (εp). Datorita valorii fixe (invariabile ĂŽn timpul functionarii) a raportului geometric de comprimare (εv), masa mai mica de ĂŽncarcatura proaspata, ce rezulta ĂŽn urma scaderii nivelului de sarcina, va ocupa acelasi volum la sfĂŽrsitul cursei de comprimare, astfel ca amestecul va fi mai putin comprimat fata de situatia ĂŽnregistrata la sarcina plina. Acesta constituie principalul dezavantaj al motoarelor cu aprindere prin scĂŽnteie. Rezulta, deci, ca devine economica cresterea raportului geometric de comprimare (εv) cu scaderea nivelului de sarcina, ĂŽn acest mod gradul sau raportul real de comprimare al gazelor (εp) fiind refacut.

Ăn etapele sale de evolutie motorul a trecut de la un reglaj manual al avansului la aprindere, la deja perimatul ruptor-distribuitor care ĂŽnseamna un reglaj automat ĂŽn functie de sarcina si turatie. De asemenea, carburatorul a devenit din ce ĂŽn ce mai sofisticat, iar ĂŽn cele din urma s-a trecut la actualul sistem de injectie electronica de benzina, ĂŽn care dozajul se face ĂŽn functie de sarcina, turatie, temperatura si alti parametri de functionare - adica tot la un sistem automat. Ăn plus fata de acestea, renuntarea la sistemul de distributie fixa, optimizat pentru un singur regim de functionare (de regula, regimul sarcinii pline) si trecerea la un sistem de distributie variabila cu sarcina si cu turatia a fost deja facuta.

 

Saab's Variable Compression Engine

Supercharged, intercooled - and with a comp ratio of up to 14:1!

By Saab Automobile AB

It is this variable compression, in combination with considerable overboost and a scaled-down cylinder displacement, that makes the SVC design so strong and at the same time so fuel-efficient.

Generous over boost means it is possible to supply more fuel to the engine as and when needed. This in turn promotes both greater torque and higher power output. A smaller cylinder

displacement also means that the engine is lighter and operates with lower friction, so it uses fuel more efficiently compared to a conventional engine. Fuel consumption can be reduced by up to 30 percent - while still retaining existing performance levels.

Due to its variable compression ratio, the SVC engine can be run at the optimum compression ratio of 14:1 at low load (ie steady highway speed) in order to put the energy in the fuel to best possible use. The compression ratio can then be reduced to 8:1 at high load (ie under hard acceleration) to enable the engine performance to be raised by supercharging without the problem of engine knocking occurring. The variable compression ratio also gives the engine great fuel flexibility. Since the compression ratio can be varied and adjusted to suit the properties of the fuel, the engine will always run at the compression ratio best suited to the fuel. The various functions of the SVC engine are controlled by a special version of Saab's Trionic engine management computer.

 

MCE-5 VCRi Pushing back the fuel consumption reduction limit

http://www.mce-5.com/

 

 

MCE-5 Variable Compression Ratio Engine: 1.5-Liter With Torque Like a V8!

http://capellossiiv.*.com/2009/02/mce-5

At the upcoming 79th International Motor Show in Geneva, France-based MCE-5 Development will showcase its first vehicle application (a Peugeot 407) of a prototype 1.5-liter MCE-5 VCRi (variable compression ratio) gasoline engine. The four-cylinder 1.5L VCRi, equipped with a two-stage turbocharger, develops 220 hp (164 kW) of power (comparable to that of a 3.0L V6 engine), and 420 Nm (310 lb-ft) of torque at 1,500 rpm (comparable to a V8 gasoline engine).

Fuel consumption on the NEDC is 6.7 L/100 km (35 mpg US) with 158 g CO2/km. The technology can be applied to smaller displacements, MCE-5 notes.

What's interesting is that this prototype is not "equipped with GDI (gasoline direct injection) or optimized combustion chambers." The 2010 version of the engine should have these improvements and bring fuel economy to 6.0 L/100 km (39 mpg US) while producing 50 hp more!

Imagine a small car that doesn't need 200+ hp. A 0.8-liter version (or whatever) could probably get very good MPG, possibly running on cellulosic ethanol made from agricultural waste. Not a silver bullet, but this technology would certainly be an improvement on the engines that we have now.

 

Geneva 2009 – Motorul viitorului

http://www.totalauto.ro/2009/02/19/geneva-2009-motorul-viitorului/

Autor: Iulian Senos 19 februarie 2009

Avantajele noului benzinar sunt urmatoarele:

1 – Creste puterea motorului. Cu o cilindree de 1,5 litri in 4 cilindri, se vor putea obtine puteri de

pana la 220 CP (165 kW) si un cuplu maxim de 420 Nm la o turatie de doar 1500 rpm.

2 - Este cu doar 200-300 € mai scump decat motoarele clasice cu functionare in ciclu Otto.

3 - Pastreaza 80% din componentele motoarelor clasice cu scanteie. Sub aspectul productiei industriale, se pot adapta si seta usor noile linii de productie.

4 – Este mai silentios.

5 - Scade consumul foarte mult, cu aproximativ 30%. In cazul cilindreei de 1,5 litri si 220 CP, consumul de benzina (in ciclu mixt NEDC) ar fi de cca. 6,7 l/100km, ceea ce ar presupune emisii de CO2 de doar 156 g/km.

Adica este exact ce isi doreste Uniunea Europeana in acest moment, in cursa sa de inverzire a batranului continent. Prototipul primei generatii VCRi va echipa un Peugeot 407 la Salonul Auto de la Geneva.

Prima oara s-a facut cunoscut acum 18 luni, cu ocazia Salonului Auto de la Geneva din 2009. Motorul viitorului, MCE-5, a devenit in toamna lui 2010 prototip functional. Propulsorul cu

raport volumetric variabil (concept VCR – Variable Compression Ratio), este tot mai aproape de momentul industrializarii, intrand de curand in faza de testare pe drum.

Sunt studiate in paralel 2 versiuni. Prima, in 4 cilindri pe benzina, 1484 cmc cu injectie indirecta, dezvolta 217 CP (160kW) in plaja de 4000-5000 rpm si un cuplu maxim de 420 Nm la turatia de 1500 rpm. Supraalimentarea motorului intra in grija a doua turbocompresoare (joasa si inalta presiune), montate in serie si functionand intr-o maniera secventiala. Fiecare din cele doua turbocompresoare beneficiaza si de serviciile cate unui cooler, pentru a creste masa aerului destinat amestecului combustibil. Coolerele sunt dedicate.

A doua versiune este cu injectie directa si dezvolta 245 CP (180 kW) intre 4000-5000 rpm, cuplul maxim fiind obtinut la 1800 rpm: 480 Nm. Presiunea (absoluta) de spraalimentare 3.5 bari. Tehnologia VCR permite pe o plaja mare de turatii obtinerea unui consum excelent, de 220g/kWh, corespunzator unui randament mecanic de aproape 40%.

 

Hefleypower

http://www.hefleypower.com/animation1.php

http://www.carlhefley.com/

Patents US # 7270092 The Hefley Patented engine. Europe: 06801330.9

First of all, it has a variable displacement design (sometimes called variable stroke). It gets extra economy because it virtually becomes a small engine when low power is needed than becomes a large powerful engine when more power is needed. Turbo chargers also work extra efficiently.

The basic version of our engine has been tested by the University of Michigan. Test number is ICES2009-76113.

It was concluded that our basic variable stroke engine can get 20 percent more economy than current conventional engines.

The rotary version is also variable displacement with all the extras of the basic engine, but additionally converts all the energy going to constantly reversing the pistons’ stroke to useable power.

WITH THE TOUCH OF A BUTTON OUR ENGINES CAN ADJUST QUICKLY TO EFFICIENTLY USE gasoline, ethanol, hydrogen, diesel, bio-diesel and fuels not yet invented

[BOASKA]

din pacate mi s-au sters din posturi,

prezentasem acolo cateva solutii tehnice arhiprezente peste tot in motoare optimizari de genul valvetronic

egr

multistage injection system

unghiuri dispunere supape ptr obtinerea unui randament maxim

sisteme de apindere moderne etc

slava domnului sunt solutii tehnice destule si foarte utile

sisteme de omogenizare amestec combustibil aer

dar au fost sterse

 

ti-am spus povestile astea le-am vazut la ovidius si mi se par grotesti de bizare si hilare

am fost aspru mustruluit cand nu am fost de acord cu un proiect in care se vroia montarea unui sistem de preamorsare a instalatiei de ungere la motorul de dacie, cand le-am recomandat sa foloseasca un ulei corespunzator si le-am spus ca arborele lucreaza in pelicula de ulei si ca o complicatie de genul cu pompe electrice pe sist in baie este inutila etc au zis ca suntem ingineri sau ce?

si cate alte tampenii, o dacie cu flotoare si zbaturi pe care mergea masina mi-a fost rusine

cand au lansat-o in surighiol, speram sa se scufunde

de genul acestora este si proiectul de mai sus

 

proiectul cu roata magnetica si convertizorul acela de hidrogen st solutii 100% functionale

mai st si alte cateva mii, dar repet asta nu e o sol viabila si punct.

 

prietene vezi ca tu tb sa prezinti proiectul tau cutiuta cu lagare

lasa materiale adunate de pe net cu sisteme biturbo supraalimentate si alte optimizari, despre asta am spus eu ca sunt deja inventate si complet functionale

tu ramai la tema ta, invarte in cutiuta si prezinta-ti proiectul tau in val de 22mii euro da?

Edited December 2, 2012 by BOASKA

[AL2012]

din pacate mi s-au sters din posturi,

prezentasem acolo cateva solutii tehnice arhiprezente peste tot in motoare optimizari de genul valvetronic

egr

multistage injection system

unghiuri dispunere supape ptr obtinerea unui randament maxim

sisteme de apindere moderne etc

slava domnului sunt solutii tehnice destule si foarte utile

sisteme de omogenizare amestec combustibil aer

dar au fost sterse

 

ti-am spus povestile astea le-am vazut la ovidius si mi se par grotesti de bizare si hilare

am fost aspru mustruluit cand nu am fost de acord cu un proiect in care se vroia montarea unui sistem de preamorsare a instalatiei de ungere la motorul de dacie, cand le-am recomandat sa foloseasca un ulei corespunzator si le-am spus ca arborele lucreaza in pelicula de ulei si ca o complicatie de genul cu pompe electrice pe sist in baie este inutila etc au zis ca suntem ingineri sau ce?

si cate alte tampenii, o dacie cu flotoare si zbaturi pe care mergea masina mi-a fost rusine

cand au lansat-o in surighiol, speram sa se scufunde

de genul acestora este si proiectul de mai sus

 

proiectul cu roata magnetica si convertizorul acela de hidrogen st solutii 100% functionale

mai st si alte cateva mii, dar repet asta nu e o sol viabila si punct.

 

GLONTUL DE ARGINT

 

Boasca, daca esti inginer, de ce te pronunti inainte de a cunoaste solutia tehnica ?

[ifx]

Sa ma lumineze si pe mine cineva cum poate varia raportul ala de compresie de la o valoare la alta valoare. Ce schimbari au loc in motor?

[BOASKA]

DECI CE TREABA ARE BITURBO DUAL STAGE IN PREZENTAREA CHESTIEI ALEIA HIDOASE????????

despre asta am spus eu in primele posturi, iei un motor il supraalimentezi si il tii in boost unde vrei....vrei sa ma citez pe mine?

prietene vrei mortis sa ai dreptate sau ce?

du-te frate deaci cu dastea

[BOASKA]

cine pariaza ca se gripeaza lagarele de la depunerile de carbon si ca se va pierde din etansare, plus ca se vor uza extrem de rapid, jocul creat de la uzura va deregla sist de gestionare a masinii, cum va reactiona la socuri detonatie?

daca se rup ce se intampla?

:bye: :bye: :bye: :bye: