This paper proposes a structure and control approach for the energy saving servo control of a pneumatic servo system. The energy saving approach is enabled by supplementing a standard four-way spool valve controlled pneumatic actuator with an additional two-way valve that enables flow between the cylinder chambers. The “crossflow” valve enables recirculation of pressurized air, and thus enables...

Results of a high-speed 10-stage axial-flow compressor test involving overall compressor and individual stage performance while stalling and operating in quasi-steady rotating stall are described. Test procedures and data acquisition methods used to obtain the dynamic stalling and quasi-steady in-stall data are explained. Unstalled and in-stall time-averaged data obtained from the compressor op...

The paper describes the design concept of a small, oilfree, reciprocating high pressure compressor which was particularly developed for NGV-applications (NGV = Natural Gas for Vehicles). It is field proven in several thousand installations in various parts of the world. The compressor head is also used in a small hermetically sealed compression unit for technical gases like N2, Air, Ar, He, H2,...

With the aim of developing a method for reducing energy consumption of room air conditioners, we address a higher-efficiency design of the rotary compressor currently most used worldwide. We focused on a new rotary compressor equipped with a mechanism to restrict the rolling motion of the piston, and performed a dynamics analysis. The new rotary compressor has a small pillar at the tip of the v...

There are different technologies to adapt the compressor’s cooling capacity to the changing requirements of the A/C and refrigerant systems when operating with screw compressors. • Distribution of the requirements to several compressors (parallel operation) • Evaporation pressure control with hot gas bypass • Internal bypass in the compressor • Reduction of the compressor displacement by a cont...

The paper presents the CFD model of a load sensing directional control valve. was validated experimentally in terms pressure drop and flow force at different positions spool. spool position imposed manually by means micrometric screw cell used for measuring force. developed with CAD-embedded tool FloEFD®. has been proved to be very reliable estimating drop, moreover quite good results were obta...

A horizontal hermetic scroll compressor has been developed for applications with high heatof-compression gases, including natural gas, air and helium (cryogenics). The compressor is a low profile horizontal design with oil-flooded cooling of the compression process. Combined with components required for oil separation and cooling, this design provides a smooth, continuous compression process fe...

In the design of the small hermetic compressor, the forces acting on the compressor shell are important parameters to study for noise and vibration control. However, the input forces to the shell cannot be measured directly. In this paper, random force spectra on compressor shell has been measured indirectly with in-situ · vibration responses and system information. Three existing techniques of...

This paper describes the concept and the design features of a new, oilfree, reciprocating high pressure compressor for technical gases. The compressor is unique in concept and design, and introduces various new design elements. A magnetic coupling makes the compressor hermetic and allows inlet pressures of up to 16 bar. A new kind of clearance seal in the high-pressure stages allows reliable oi...