شاحن توأم
الشاحن التوأم Twincharger، refers to a compound forced induction system used on some piston-type internal combustion engines. It is a combination of an exhaust-driven turbocharger and a mechanically driven supercharger, each mitigating the weaknesses of the other. A mechanically driven supercharger offers exceptional response and low-rpm performance as it does not rely on pressurization of the exhaust manifold (assuming that it is a positive-displacement supercharger such as a Roots type or twin-screw and not a Centrifugal compressor supercharger, which does not provide substantial boost in the lower RPM range). A turbocharger sized to move a large volume of air tends to respond slowly to throttle input while a smaller, faster-responding turbo may fail to deliver sufficient volume through an engine's upper RPM range. The unacceptable lag time endemic to a large turbocharger is effectively neutralized when combined with a supercharger which tends to generate substantial boost pressure much faster in response to throttle input. The end result being a zero-lag powerband with high torque at lower engine speeds and increased power at the upper end. Twincharging is therefore desirable for small-displacement motors (such as VW's 1.4TSI), especially those with a large operating rpm, since they can take advantage of an artificially broad torque band over a large speed range.
Twincharging does not refer to a twin-turbo arrangement where two different kinds of compressors are used.
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الوصف التقني
A twincharging system combines a supercharger and turbocharger in a complementary arrangement, with the intent of one component's advantage compensating for the other component's disadvantage. There are two common types of twincharger systems: series and parallel.
السلاسل
التوازي
الكفاءة
العيوب
The main disadvantage of adding any forced induction system is the complexity and expense of components. Usually, to provide acceptable response, smoothness of power delivery, and adequate power gain over a single-compressor system, expensive electronic and/or mechanical controls must be used. In a spark-ignition engine, a low compression ratio must also be used if the supercharger produces high boost levels, negating some of the efficiency benefit of low displacement.
التوافر التجاري
| القدرة | العزم | المركبات |
|---|---|---|
| 103 kW (140 PS; 138 bhp) at 5,600 rpm | 220 N⋅m (162 lbf⋅ft) at 1,500–4,000 rpm | VW Golf V, VW Jetta V, and VW Touran |
| 110 kW (150 PS; 148 bhp) at 5,800 rpm | 220 N⋅m (162 lbf⋅ft) at 1,250–4,500 rpm | SEAT Ibiza IV |
| 110 kW (150 PS; 148 bhp) at 5,800 rpm | 240 N⋅m (177 lbf⋅ft) at 1,500–4,000 rpm | (CNG version) VW Passat VI, VW Passat VII, VW Touran |
| 110 kW (150 PS; 148 bhp) at 5,800 rpm | 240 N⋅m (177 lbf⋅ft) at 1,750–4,000 rpm | VW Sharan II, VW Tiguan, SEAT Alhambra |
| 118 kW (160 PS; 158 bhp) at 5,800 rpm | 240 N⋅m (177 lbf⋅ft) at 1,500–4,500 rpm | VW Eos, VW Golf VI, VW Jetta VI, VW Scirocco III |
| 125 kW (170 PS; 168 bhp) at 6,000 rpm | 240 N⋅m (177 lbf⋅ft) at 1,500–4,500 rpm | VW Golf V, VW Jetta V, VW Touran |
| 132 kW (179 PS; 177 bhp) at 6,200 rpm | 250 N⋅m (184 lbf⋅ft) at 2,000–4,500 rpm | VW Polo V, SEAT Ibiza Cupra, Škoda Fabia II |
| 136 kW (185 PS; 182 bhp) at 6,200 rpm | 250 N⋅m (184 lbf⋅ft) at 2,000–4,500 rpm | Audi A1 |
| القدرة | العزم | المركبات |
|---|---|---|
| 320 PS (235 kW; 316 bhp) at 5,700 rpm | 400 N⋅m (295 lbf⋅ft) at 2,200–5,400 rpm | T6 |
| 367 PS (270 kW; 362 bhp) at 6,000 rpm | 470 N⋅m (347 lbf⋅ft) at 3,100–5,100 rpm | Polestar |
| 408 PS (300 kW; 402 bhp) | 640 N⋅m (472 lbf⋅ft) | T8 (including rear electric motor) |
| القدرة | العزم | المركبات |
|---|---|---|
| 1,104 hp (823 kW; 1,119 PS) at 6,900 rpm | 1,430 N⋅m (1,055 lbf⋅ft) at 4,500 rpm | ST1 |
الأنظمة لابديلة
Anti-lag system
Twincharging's largest benefit over anti-lag systems in race cars is its reliability. Anti-lag systems work in one of two ways: by running very rich AFR and pumping air into the exhaust to ignite the extra fuel in the exhaust manifold; or by severely retarding ignition timing to cause the combustion event to continue well after the exhaust valve has opened. Both methods involve combustion in the exhaust manifold to keep the turbine spinning, and the heat from this will shorten the life of the turbine greatly.
Variable geometry turbocharger
A variable-geometry turbocharger provides an improved response at widely varied engine speeds. With variable-incidence under electronic control, it is possible to have the turbine reach a good operating speed quickly or at lower engine speed without severely diminishing its utility at higher engine speed.
Twin-scroll turbocharger
A turbocharger with two sets of vanes for two operating pressures, can decrease lag by operating at different exhaust pressures.
Sequential twin turbochargers
Sequential turbocharger systems provide a way to decrease turbo lag without compromising ultimate boost output and engine power.
Nitrous oxide
Nitrous oxide (N2O) is mixed with incoming air, providing more oxidizer to burn more fuel for supplemental power when a turbocharger is not spinning quickly. This also produces more exhaust gases so that the turbocharger quickly spools up, providing more oxygen for combustion, and the N2O flow is reduced accordingly. The expense of both the system itself and the consumable N2O can be significant.
Water injection
For more engine power, and to augment the benefits of forced induction (by means of turbocharging or supercharging), an aftermarket water injection system can be added to the induction system of both gasoline and diesel internal combustion engines.
المصادر
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