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Rotary Actuators
Published in John S. Cundiff, Michael F. Kocher, Fluid Power Circuits and Controls, 2019
John S. Cundiff, Michael F. Kocher
Ranking of the various bent axis design advantages is problematic. One designer (Hull, 1999) gives the following guidelines for justifying the added cost of a bent axis variable displacement motor. Stroke ratio. If the wider displacement range from minimum to maximum is needed, this is a powerful reason to choose the bent axis design.Maximum operating speed. If the higher speed can be used to meet a functional objective, this advantage adds to the cost competitiveness.Other factors. Factors such as stall torque efficiency and size limitation are not as significant as the stroke ratio or operating speed. They add to the decision to choose a bent axis design, but are not often the deciding factor.
Overview, Background, and History
Published in John B. Heywood, Eran Sher, The Two-Stroke Cycle Engine, 2017
Table 1-6 compares some major features of two-stroke cycle automotive engines that have evolved during this century with those of these direct-injection spark-ignited two-stroke engines now being developed. Note that the scavenging process has improved remarkably (as evidenced by the increases in specific power), while the overall geometry—the bore-to-stroke ratio of the engine—has not changed at all. The scavenging process has been primarily improved by refining the geometry of the engine ports. One of the more recent engines listed in Table 1-6 is valved rather than ported (Toyota) and three (Toyota, Subaru, and Orbital IES) use an external blower. Accordingly they can use a conventional four-stroke cycle engine crankshaft design and wet-sump lubrication system.
Refrigeration Cycles
Published in Kavati Venkateswarlu, Engineering Thermodynamics, 2020
A food freezing system requires 20 tonnes of refrigeration at an evaporator temperature of −35°C and condenser temperature of 25°C. Refrigerant R-12 is subcooled by 4°C before entering the expansion valve, and vapor is superheated by 5°C before leaving the evaporator. A six-cylinder single-acting compressor (bore-to-stroke ratio, B/L = 1), operating at 1500 rpm, is used. Determine (i) refrigerating effect, (ii) flow rate of R-12, (iii) cylinder dimensions if volumetric efficiency is 80%, (iv) power required to drive the compressor, and (v) COP. Take cpg = 1.235 kJ/kg K and cpl = 0.733 kJ/kg K.
A theoretical study of the mechanism with variable compression ratio and expansion ratio
Published in Mechanics Based Design of Structures and Machines, 2018
As an essential parameter, bore-to-stroke ratio determines the size of engines with the same displacement. Thus, the ratio affects the gas force and the inertia force on the piston. On the other hand, the eccentric sleeve is an essential part of VR/LE. The size of eccentric sleeve is limited by the strength of pinion gears that drive the eccentric sleeve rotate, and thus limited by the force on the piston that depends on the max pressure in the cylinder especially for most turbocharged engines. Therefore, both the range of VCR and the effect of Atkinson are related to the bore-to-stroke ratio.