Development of a Small Rotary SI/CI Combustion Engine

Abstract

This paper describes the development of small rotary internal combustion engines developed to operate on the High Efficiency Hybrid Cycle (HEHC). The cycle, which combines high compression ratio (CR), constant-volume (isochoric) combustion, and overexpansion, has a theoretical efficiency of 75% using air-standard assumptions and first-law analysis. This innovative rotary engine architecture shows a potential indicated efficiency of 60% and brake efficiency of >50%. As this engine does not have poppet valves and the gas is fully expanded before the exhaust stroke starts, the engine has potential to be quiet. Similar to the Wankel rotary engine, the 'X' engine has only two primary moving partsa shaft and rotor, resulting in compact size and offering low-vibration operation. Unlike the Wankel, however, the X engine is uniquely configured to adopt the HEHC cycle and its associated efficiency and low-noise benefits. The result is an engine which is compact, lightweight, low-vibration, quiet, and fuel-efficient. Two prototype engines are discussed. The first engine is the larger X1 engine (70hp), which operates on the HEHC with compression-ignition (CI) of diesel fuel. A second engine, the XMv3, is a scaled down X engine (70cc / 3HP) which operates with spark-ignition (SI) of gasoline fuel. Scaling down the engine presented unique challenges, but many of the important features of the X engine and HEHC cycle were captured. Preliminary experimental results including firing analysis are presented for both engines. Further tuning and optimization is currently underway to fully exploit the advantages of HEHC with the X architecture engines.

Research on sealing characteristics of annular power cylinder based on twin-rotor piston engine

“…The model can be used to calculate the flow rate of jet flow with an escape coefficient. If P 1 � P 2 , the gas flows from chamber 1 to chamber 2, and the mass flow rate Q 1 is positive, which can be expressed as shown in equation (15) If P 1 < P 2 , it can be indicated that gas flows from chamber 2 to chamber 1, and Q 1 is negative. For opening gap 2 of the piston ring, referring to the calculation model of opening gap 1.…”

“…14 Its piston motion inertia is small, and the movement is more stable compared with a reciprocating piston engine. 15 However, due to the small compression ratio and long combustion chamber, the Wankel engine's combustion efficiency is low, and its emission problem is a serious shortcoming. 12 Therefore, Shi et al used CFD to analyze the influence of the Wankel engine's hydrogen volume fraction and injection angle on combustion performance.…”

Combustion Chamber Design Effect on The Rotary Engine Performance - A Review

“…16) and SARM for drones and range extenders. LiquidPiston: a rotary engine, fourstroke of "X" architecture with intake and exhaust through rotor shaft [95][96][97][98] . The LiquidPiston's "X" architecture is a rotary engine that similar in some aspects to the Wankel.…”

Optimal Design for New Rotary Engine with Geometric Shape Functions on Combustion Chamber and Ports

“…The XE combustion chamber can also be installed in a fixed housing with relatively shape-free choice, and over-expansion strokes can be easily realized by appropriately positioning the intake and exhaust ports [11]. A 70-hp water-cooled diesel engine was initially devised to verify XE operation and basic principles [12], and a 70-cc air-cooled gasoline engine was subsequently applied to a small cart [13]. Recent research has continued to improve durability, heat transfer performance, and sealing performance aimed at developing emergency engines (range-extenders) for generators, small aircraft, and electric vehicles [14,15].…”