Articles

Affichage des articles du septembre, 2014

La transmission à variation continue

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If you have ever driven a "moped", you've already dealt with the principle of continuous variation! The speed varies gradually, without gearshift. The most common system is composed of a metal belt and pulleys, the conical winding diameter varies automatically according to the engine speed. Some models are still a batch mode, allowing the driver to pass himself reports using a lever. For now, its high cost of production usually reserve this type of transmission in high-end models. advantages: driving comfort (fresh Conduct) operation totally devoid of jerks range of high variation (equivalent to a minimum of 6 classic reports) auto or sequential mode available cons: overconsumption nervous reactions (literally Braille engine during hard acceleration, and says braille says consumes ...) grip that can be disconcerting no performance driving Some examples: Nissan Xtronic, Autoronic Mercedes, Audi Multitronic ...

The robotised gearbox with double clutch

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Although we found an auto mode and a sequential mode, as a single-clutch AMT, the ISR dual clutch design is very different. It is in fact an assembly of two half-gearboxes. Each has its own clutch. Thus, when a gear is engaged, the following report is pre-committed to him, which authorizes a change extremely fast speed (less than 10 milliseconds). Furthermore, the torque transmission is continuous, thereby avoiding any jerk. In short, dual-clutch AMT combines the advantages of the BVA and ISR single clutch, without their drawbacks. This type of transmission meeting today a success. advantages: driving comfort auto or sequential mode consumption gain passages ultrafast report cons: more expensive to buy than a BVA and a BVR if the passage between the two reports is fast, it is much less so when we want to downshift 2 gears at once and vice versa (uphill). Some examples: Peugeot DSC, EDC at Renault, Mercedes 7G-DCT, DSG / S-Tronic with Volkswagen and Audi ...

The robotized gearbox ("ISR") single clutch

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This is very simply a conventional gearbox on which adapted a device that engages, disengages and changes gear for you. The "robot" is usually composed of very rapid electric actuators. On sports cars, such as hydraulic actuators are faster. The whole is controlled by an electronic increasingly sophisticated, taking into account a multitude of parameters. Two operating modes are available: Automatic: This is the computer that selects the gear that best suits the situation, according to auto-adaptive. Multiple operating modes (city, sport ...) may be available. Sequential: you switch gears yourself with a classic appearance lever or steering wheel paddles. However you do not have to manage the clutch. Note that you can switch from one mode to another as you like, in real time. advantages: auto or sequential mode consumption unchanged from a manual (or even sometimes slightly lower) less expensive than a conventional automatic gearbox because it is actually...

FONCTIONNEMENT ET TYPES DE BOÎTES AUTOMATIQUES 1

Communément appelée « BVA », la boîte de vitesses auto à convertisseur hydraulique est sans doute le type de transmission le plus connu après la boite de vitesses manuelle. Principe : L'embrayage à disques que l'on connaît sur les boites manuelles est remplacé par un « convertisseur de couple hydraulique », qui transmet le couple moteur par l'intermédiaire d'un fluide. De par cette conception, le convertisseur peut « patiner », ce qui assure la fonction « embrayage ». C'est ce patinage qui est l'origine essentielle de la surconsommation de carburant induite par les premières BVA. Pour pallier ce défaut, un embrayage classique (dit « de pontage ») est souvent ajouté de nos jours. Il permet de court-circuiter le convertisseur dès que les conditions de fonctionnement le permettent, abaissant ainsi les pertes de charge et donc la consommation. Il autorise aussi un frein moteur normal, au contraire d'une BVA classique. Le passage des vitesses se fait autom...