Oilless Piston Engines

活塞式发动机中的润滑油保护了接触部件，但会导致碳氢化合物排放、催化剂中毒、频繁维护和主要的热损失，因为必须保持衬套足够凉爽，以防止过量的机油消耗。许多作者讨论了解决这个问题的必要性，特别是在20世纪80年代和90年代开发所谓的绝热发动机的计划中。然而，从环保的角度来看，无油发动机仍然是非常可取的，因为它们可以实现低排放和高效率。以往不成功的尝试清楚地表明，要实现这一技术突破，仍需解决一些根本问题。当与低压回收热力学循环相结合时，活塞的无接触密封似乎是一个很有前途的选择。

Lubricating oil in piston engines protects the contacting parts, but leads to hydrocarbon emissions, catalyst poisoning, frequent maintenance, and major heat losses as the liner must be kept cool enough to prevent excessive oil consumption. The need to address this problem has been discussed by many authors, especially during the programs to develop the so-called adiabatic engines in the 1980s and 1990s. However, oilless engines remains highly desirable from an environmental perspective as they would achieve low emissions and high efficiencies. Previous unsuccessful attempts clearly indicates that fundamental issues still have to be resolved to achieve this technological breakthrough. Contact-free sealing of the piston appears to be a promising option when combined to a low-pressure recuperated thermodynamic cycle.