Investigation into a novel pressure-balanced free-piston engine as a high efficiency chemical energy convertor

研究新型压力平衡自由活塞发动机作为高效化学能转换器

• 批准号: 2283557
• 金额: --
• 依托单位: University of Bath
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2019
• 资助国家: 英国
• 起止时间: 2019 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2283557
• 关键词: Investigation; into; novel; pressure; balanced

The opposed-piston 2-stroke (OP2S) engine has historically been applied to aircraft propulsion as well as engines for power generation and rail traction with great success. More recently, Achates Power have shown the potential of the OP2S engine for automotive applications. The low surface area to volume ratio of the combustion chamber in OP2S engines, combined with its lack of a cylinder head, results in lower heat losses yielding high exhaust gas energy, making it an ideal candidate for turbocharging, as well as increased brake thermal efficiency. However, due to the requirement for a positive delta pressure across the cylinder at all operating points (intake manifold pressure must be higher than exhaust manifold pressure) to ensure the scavenging performance of 2-stroke engines, crankcase scavenging is typically used instead as, unlike a turbocharger-driven charging system, it guarantees a positive delta pressure gradient at all operating points. Nevertheless, other scavenging systems, such as a supercharger in conjunction with a turbocharger, have been shown to provide effective scavenging performance whilst utilising the otherwise wasted exhaust gas energy. Moreover, the use of a combined supercharger/turbocharger charging system with an OP2S architecture provides greater flexibility in the air-fuel-ratio control and exhaust temperature management, whereas conventional 4-stroke engines are expected to require the use of cylinder deactivation or other thermal management strategies to meet the low emissions standards. Furthermore, the use of electrically assisted turbochargers not only increases this flexibility but also provides a means of extracting excess work from the turbine by turbocompounding, whilst simplifying the intake air path.

对置活塞二冲程 (OP2S) 发动机历来应用于飞机推进以及发电和铁路牵引发动机，并取得了巨大成功。最近，Achates Power 展示了 OP2S 发动机在汽车应用中的潜力。 OP2S 发动机燃烧室的表面积与体积比较低，加上没有气缸盖，可降低热损失，产生较高的废气能量，使其成为涡轮增压的理想选择，并提高制动热效率。然而，由于在所有工作点都要求气缸内有正压差（进气歧管压力必须高于排气歧管压力）以确保二冲程发动机的扫气性能，因此通常使用曲轴箱扫气，这与涡轮增压器驱动的增压系统，可保证所有工作点上的正压力梯度。然而，其他扫气系统，例如与涡轮增压器结合的增压器，已被证明可以提供有效的扫气性能，同时利用否则会浪费的废气能量。此外，使用具有 OP2S 架构的组合式机械增压器/涡轮增压器充电系统可在空燃比控制和排气温度管理方面提供更大的灵活性，而传统的四冲程发动机预计需要使用停缸或其他热控制技术。满足低排放标准的管理策略。此外，电动辅助涡轮增压器的使用不仅增加了这种灵活性，而且还提供了一种通过涡轮复合从涡轮机中提取多余功的方法，同时简化了进气路径。