The press day for the 76th International Geneva Motor Show (public open day: March 2–12, 2006) kicked off on February 28, and the event has already started to attract attention. In my previous newsletter, I speculated about the safety features of the Lexus LS460, but this time, I'm focusing more on the appearance of a new generation of direct injection engines. Over the past few years, hybrid and diesel vehicles have dominated discussions around reducing fuel costs in the automotive industry. Especially in Europe, it's widely believed that diesel engines can significantly lower fuel consumption. With the rising popularity of diesel vehicles, many manufacturers in Europe and the U.S. have announced their first steps into the hybrid market, entering Japan’s automotive scene.
However, it's commonly thought that gasoline engines can only improve efficiency through hybrid systems. Now, two automakers have introduced a third-generation gasoline direct injection engine known as "Spray Guided Direct Injection." Earlier reports highlighted similar engines from BMW and DaimlerChrysler, both using the same technology. To summarize the evolution of direct injection engines:
1. Wall Guided Direct Injection, which uses airflow to stratify fuel for lean-burn operation.
2. Stoichiometric Direct Injection, which runs at a theoretical air-fuel ratio.
3. Spray Guided Direct Injection, which uses fuel spray to create a stratified charge.
The main advantage of Spray Guided over Stoichiometric is improved fuel efficiency. However, achieving proper fuel stratification requires precise control—fine injection amounts, high pressure, and multiple injections. This is why both companies are using piezo injectors, typically found in diesel engines. Compared to solenoid injectors, piezoelectric ones offer better sensitivity and control, but they come with a higher cost.
In large diesel trucks, where the engine cost runs into millions of yen, the added expense might be justified. But for passenger cars, especially luxury models like the Mercedes-Benz CL350, the use of piezo injectors makes sense. For regular petrol engines, however, cost remains a major concern. Automakers know that direct injection increases production costs. Plus, lean-burn engines require expensive NOx catalysts, another barrier to widespread adoption.
So, it's still unclear if piezo injectors will replace solenoid valves across all models. Unless solenoid injectors can match the performance of piezo ones, the transition may not happen soon. That said, even though these new direct injection engines differ in combustion methods—some spark-ignited, others compression-ignited—their injection systems and combustion chambers are becoming more similar to diesel designs. With injection pressures reaching up to 20MPa (200 times atmospheric pressure), these engines are pushing the limits of traditional petrol technology. If they can achieve the same efficiency improvements as diesel engines, it might not be long before piezo injectors become the standard.
HANXHOSA (SUZHOU) LIMITED COMPANY , https://www.pvcplant.com