The synthesis of structure and parameters of energy efficient pneumatic actuator

Abstract

It is known that compressed air is one of the most expensive energy carriers while a discrete pneumatic actuator with throttle braking of operating unit possesses a rather low degree of energy perfection. Present work posed and solved the problem on the isolation of all unproductive power consumption in the pneumatic actuator. Such power expenditures include losses due to the incompleteness of air expansion in the working cavity, losses in the dead space, losses for throttling, additional losses for the fixation of operating unit, and the losses, related to the work to eject compressed air from the exhaust cavity. Authors designed the circuits for actuators, as well as the principles of their operation, which make it possible to maximally decrease such unproductive power consumption. One more essential shortcoming in the pneumatic actuators with traditional circuit of throttle braking is a rather limited level of inertia load, within which the actuator remains operational. A cardinal solution for these problems in present work is achieved due to the transition from the circuits of throttle braking, which are quite formally transferred from hydraulic drive technique, to the circuits of braking through a change in the structure of commutation connections. Due to this, it was possible for each phase of the motion of operating unit to enable the most rational commutation relations, which allowed us to attain maximum realization of the working capacity of compressed air in pneumatic actuator and to achieve the most preferable form in the transient process. The latter made it possible to substantially increase inertia loads, at which the actuator remains operational. Pneumatic circuits based on the commercially available pneumatic equipment are proposed, which realize these principles. A mathematical model in the dimensionless form with the isolation of criteria of dynamic similarity is developed. Based on this, a region of the rational utilization of the proposed actuators is determined in the plane of criteria of dynamic similarity; and one of the problems is solved on the parametric synthesis in the form of selecting a diameter of cylinder, which provides for the work of actuators in the zone of the most effective energy saving. Authenticity of the obtained theoretical results is confirmed by the oscillograms of transient process in the experimental sample of energy-saving pneumatic actuator.