Mechanical Components

A Superfluid Pulse Tube Refrigerator Without Moving Parts for Sub-Kelvin Cooling

A report describes a pulse tube refrigerator that uses a mixture of 3He and superfluid 4He to cool to temperatures below 300 mK, while rejecting heat at temperatures up to 1.7 K. The refrigerator is driven by a novel thermodynamically reversible pump that is capable of pumping the 3He–4He mixture without the need for moving parts.

Posted in: Mechanics, Mechanical Components, Briefs, TSP

Read More >>

Sapphire Viewports for a Venus Probe

A document discusses the creation of a viewport suitable for use on the surface of Venus. These viewports are rated for 500 °C and 100 atm pressure with appropriate safety factors and reliability required for incorporation into a Venus Lander. Sapphire windows should easily withstand the chemical, pressure, and temperatures of the Venus surface. Novel fixture designs and seals appropriate to the environment are incorporated, as are materials compatible with exploration vessels. A test cell was fabricated, tested, and leak rate measured. The window features polish specification of the sides and corners, soft metal padding of the sapphire, and a metal C-ring seal. The system safety factor is greater than 2, and standard mechanical design theory was used to size the window, flange, and attachment bolts using available material property data. Maintenance involves simple cleaning of the window aperture surfaces. The only weakness of the system is its moderate rather than low leak rate for vacuum applications.

Posted in: Mechanics, Mechanical Components, Briefs, TSP

Read More >>

Compact, Low-Force, Low-Noise Linear Actuator

This actuator has potential uses in military and automotive applications. Actuators are critical to all the robotic and manipulation mechanisms that are used in current and future NASA missions, and are also needed for many other industrial, aeronautical, and space activities. There are many types of actuators that were designed to operate as linear or rotary motors, but there is still a need for low-force, low-noise linear actuators for specialized applications, and the disclosed mechanism addresses this need.

Posted in: Mechanics, Tech Briefs, Mechanical Components, Motion Control, Briefs

Read More >>

Ultra-Compact Motor Controller

Applications include industrial robotic arms, industrial machinery, and automobiles. This invention is an electronically commutated brushless motor controller that incorporates Hall-array sensing in a small, 42-gram package that provides 4096 absolute counts per motor revolution position sensing. The unit is the size of a miniature hockey puck, and is a 44-pin male connector that provides many I/O channels, including CANbus, RS-232 communications, general-purpose analog and digital I/O (GPIO), analog and digital Hall inputs, DC power input (18–90 VDC, 0–l0 A), three-phase motor outputs, and a strain gauge amplifier.

Posted in: Mechanics, Tech Briefs, Mechanical Components, Motion Control, Briefs

Read More >>

Modular, Rapid Propellant Loading System/Cryogenic Testbed

The Cryogenic Test Laboratory (CTL) at Kennedy Space Center (KSC) has designed, fabricated, and installed a modular, rapid propellant-loading system to simulate rapid loading of a launch-vehicle composite or standard cryogenic tank. The system will also function as a cryogenic testbed for testing and validating cryogenic innovations and ground support equipment (GSE) components. The modular skid-mounted system is capable of flow rates of liquid nitrogen from 1 to 900 gpm (≈3.8 to 3,400 L/min), of pressures from ambient to 225 psig (≈1.5 MPa), and of temperatures to –320 °F (≈–195 °C). The system can be easily validated to flow liquid oxygen at a different location, and could be easily scaled to any particular vehicle interface requirements.

Posted in: Mechanics, Mechanical Components, Briefs, TSP

Read More >>

Compact, Low-Force, Low-Noise Linear Actuator

This actuator has potential uses in military and automotive applications. Actuators are critical to all the robotic and manipulation mechanisms that are used in current and future NASA missions, and are also needed for many other industrial, aeronautical, and space activities. There are many types of actuators that were designed to operate as linear or rotary motors, but there is still a need for low-force, low-noise linear actuators for specialized applications, and the disclosed mechanism addresses this need.

Posted in: Mechanics, Mechanical Components, Briefs, TSP

Read More >>

Loop Heat Pipe With Thermal Control Valve as a Variable Thermal Link

New arrangement reduces energy demands while maintaining circuits and batteries within optimal temperature range. Future lunar landers and rovers will require variable thermal links that allow for heat rejection during the lunar daytime and passively prevent heat rejection during the lunar night. During the lunar day, the thermal management system must reject the waste heat from the electronics and batteries to maintain them below the maximum acceptable temperature. During the lunar night, the heat rejection system must either be shut down or significant amounts of guard heat must be added to keep the electronics and batteries above the minimum acceptable temperature. Since guard heater power is unfavorable because it adds to system size and complexity, a variable thermal link is preferred to limit heat removal from the electronics and batteries during the long lunar night. Conventional loop heat pipes (LHPs) can provide the required variable thermal conductance, but they still consume electrical power to shut down the heat transfer. This innovation adds a thermal control valve (TCV) and a bypass line to a conventional LHP that proportionally allows vapor to flow back into the compensation chamber of the LHP. The addition of this valve can achieve completely passive thermal control of the LHP, eliminating the need for guard heaters and complex controls.

Posted in: Mechanics, Mechanical Components, Briefs

Read More >>

White Papers

Liquid Silicone Rubber Takes the Heat
Sponsored by Proto Labs
Interaction of Intermodulation Products between DUT and Spectrum Analyzer
Sponsored by Rohde and Schwarz A and D
Looking at Ceramic Carbides in a New Light
Sponsored by Goodfellow
Removing the Gap Between ECAD and MCAD Design
Sponsored by Mentor Graphics
Are you tired of maintaining UPS Systems?
Sponsored by Falcon
High Reliability Flexible Circuits for the Medical Marketplace
Sponsored by Tech Etch

White Papers Sponsored By: