Motion Control

Improving Stirling Engine Performance Through Optimized Piston and Displacer Motion

Stirling engines typically achieve high efficiency, but lack power density. Low power density prevents them from being used in many applications where internal combustion engines are viable competitors, and increases system costs in applications that require Stirling engines. This limits their operating envelope in both terrestrial and space applications. Sinusoidal piston and displacer motion is one of the causes of low power density. Previous work proposed solving this problem by replacing sinusoidal waveforms with waveforms that more closely approximate those of the ideal Stirling cycle. However, when working with real engines, imposing ideal waveforms has been shown to reduce power density and efficiency due to increased pressure drop through the regenerator and heat exchangers.

Posted in: Briefs, Mechanical Components, Mechanics, Fluid Handling, Motors & Drives

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Custom Machines Create Engine Lip Skins on Boeing Aircraft

MJC Engineering, a custom machine tool builder in Huntington Beach, CA, specializes in metal-spinning machines for such applications as sheet spinning, flow forming, wheel spinning, and rotary forging. The company was commissioned to build a series of metal-spinning machines for GKN for use at its plants in Camarillo, CA and Orangeburg, SC. These machines produce lip skins for the engine housings on Boeing 777X and 737MAX aircraft. Using CNC from Siemens Industry (Elk Grove Village, IL) and robotic handling technology — in addition to its proprietary servopump-controlled Green Power™ hydraulic power unit that saves up to 40% on energy — the MJC team devised a unique solution to an engineering challenge brought to them by GKN.

Posted in: Application Briefs, Aviation, Motion Control

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Magnetic Relief Valve

A side view of the relief valve sections (left), and a view inside the relief valve (right). A magnetically retained pressure-relief valve enables quick-open on/off operation when overpressure is reached.Inventors at NASA’s Kennedy Space Center have developed a magnetically retained, fast-response pressure relief valve that is designed to fully open at precise cracking pressures, and that operates in a fully open/fully closed manner. The use of a magnetically controlled relief valve, as opposed to a spring-based relief valve, enables quick-open on/off relief operation when overpressure is reached. This is due to the rapid decay of the magnetic field as the fluid medium pushes the valve poppet to an open position. Spring-based relief valves require increasing pressure and force to continually compress the spring and open the relief valve. This requirement greatly complicates the design of a system relief mechanism. A magnetic relief valve reduces these design complexities by eliminating the spring.

Posted in: Briefs, Mechanical Components, Mechanics, Fluid Handling

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Work Piece Cleaning Apparatus and Method with Pulsating Mixture of Liquid and Gas

NASA Goddard’s scientists have developed a novel, volatile organic compound (VOC)-free system for cleaning tubing and piping that significantly reduces cost and carbon consumption. The innovative technology enables the use of deionized water in place of costlier isopropyl alcohol (IPA), and does not create any waste for which costly disposal is usually required. It uses nitrogen bubbles in water, which act as a scrubbing agent to clean equipment. The cleaning system quickly and precisely removes all foreign matter from tubing and piping.

Posted in: Briefs, Mechanical Components, Mechanics, Fluid Handling

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Safety Drain System for Fluid Reservoir

Researchers at NASA’s Marshall Space Flight Center have developed a system that reduces the entrapment risks associated with a pool or spa’s recirculation drain. The technology prevents hazards caused by suction forces on the body, hair, clothing, or other articles. Employing a novel configuration of drainage openings along with parallel paths for water flow, the system redistributes force over a much larger area, minimizing suction force at any localized area. With more efficient drainage and recirculation, the device improves performance, increases safety, and decreases operating costs. The technology can also provide thorough chemical mixing, which improves processes in systems and allows continued operation in the event of localized debris clogging a portion of the recirculation area. All of these benefits come without a protrusive drain cover, leaving the area safe and aesthetically pleasing.

Posted in: Briefs, Mechanical Components, Mechanics, Fluid Handling

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Temperature-Compensating PMT Housing

Shrinking or contracting light guides is a problem when photomultiplier tubes (PMTs) are glued to the guides. If there is no way to allow movement of the PMTs, when the temperature goes down, the light guide contracts and breaks the glue joint. The PMTs cannot be left loose to rattle around inside the detector. They must be held precisely, yet gently, and allowed to move.

Posted in: Briefs, Mechanical Components, Mechanics, Fluid Handling

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Motor Controller Provides Custom Electronic Control Solution

A Fortune 200 company needed a turnkey, DC voltage, agency-compliant electronic control solution capable of providing motion control with memory position capabilities and auto run/sense features for a multi-motor application involving four motors. Particularly important to the design criteria was the development of an interactive system of wireless remote control capabilities and other user interface devices, including iPhone and iPad interconnect devices. It was a complicated job, and the company would need to partner with experts who could deliver a time- and cost-effective solution.

Posted in: Application Briefs, Motors & Drives

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