An altitude control system for an unmanned aerial vehicle includes a compressor assembly defining a plenum therein, a passive valve assembly coupled to a first portion of the compressor assembly and in fluid communication with the plenum, and an active valve assembly coupled to a second portion of the compressor assembly and in fluid communication with the plenum. A method of controlling an altitude of an unmanned aerial vehicle and an unmanned aerial vehicle are also provided.

Embodiments of a direct-drive fan system and a variable process control system are disclosed herein. The direct-drive fan system and the variable process control system efficiently manage the operation of fans in a cooling system such as a wet-cooling tower or air-cooled heat exchanger (ACHE), HVAC systems, mechanical towers or chiller systems.

An industrial automation controller includes a housing with a forced convection chamber. First and second fans are releasably connected to the housing and are adapted to induce airflow through the forced convection chamber. The first and second fans are each connected to the housing by respective first and second latch systems that each include a primary latch and a secondary latch. The secondary latch imposes a time delay during removal and replacement of a fan to facilitate hot swapping of the fan with a replacement fan. A make-last/break-first contact system is provided for each fan such that the fan is shutdown in a controlled manner prior to removal of the fan from the housing. The controller monitors internal temperature and fan speed. The controller initiates, logs, and reports fault conditions based upon the monitored temperature and/or fan speed. The controller is shut down if the monitored temperature exceeds a select temperature level.

A shaft seal for an exhaust fan. The seal limits leakage from within an exhaust fan housing around an exhaust fan drive shaft that extends between a rotational power source exterior to the exhaust fan housing and a position within the exhaust fan housing. The seal comprises a plenum generally positioned about the exhaust fan drive shaft at the point where the shaft extends into the fan housing; an auxiliary blower comprising a housing, an internal blade driven by an auxiliary blower drive shaft, and an auxiliary blower drive to rotate the drive shaft where the auxiliary blower drive is operatively associated with the rotational power source such that operation of the rotational power sources causes a rotation of the exhaust fan drive shaft and the auxiliary blower drive shaft; and a duct fluidly connecting the auxiliary blower housing to the plenum.

A fan brake circuit includes a semiconductor switch unit, a motor, a motor drive circuit, an isolation unit, a charging/discharging unit and a control unit. One end of the motor, the semiconductor switch unit and the control unit serves to receive an input power. When the fan is powered off, the semiconductor switch unit disconnects from the motor and the motor drive circuit receives the operation voltage provided by the charging/discharging unit and transmits the drive signal to the motor, whereby the motor forms a short-circuit to brake. By means of the design of the fan brake circuit, when the fan is powered off, the fan can quickly brake and stop and the cost is lowered.

A fan system includes a motor, a rotatable hub, and a plurality of fan blades. The motor is coupled with the hub by a hollow drive shaft, such that the drive system of the fan system is gearless. The motor is controlled by a PFC-based control module, which is in communication with sensors that are configured to sense parameters associated with operation of the fan system. The control module is configured to react in certain ways to certain conditions detected by the sensors, such that the fan system uses feedback-based control algorithms. A remote control panel is in communication with the control module. The remote control panel is operable to display fault conditions detected by the sensors. Blade retainers prevent fan blades from falling when a fan blade breaks free from the hub. Pins prevent the hub from falling when the hub breaks free from the rotor.

An inflatable product includes an integrated axial-flow pump which produces a high rate of inflation. The pump includes a cover mounted to a body of the pump and selectively configurable between open and closed positions. In the open position, air is allowed to flow between the inflatable chamber and the ambient air through the pump body. When the cover is closed, the air chamber of the inflatable product is sealed with respect to the ambient air such that air is retained within the inflatable chamber when inflated. A power switch is positioned to be deactivated by the cover when the cover is mounted to the body of the pump, such that replacement of the cover during inflation or deflation of the inflatable product automatically deactivates the pump.

A method of detecting the angular positions of blades of a rotor wheel of a turbine engine, in which the turbine engine has first and second rotor wheels including respective first and second numbers of blades regularly distributed around their circumferences, includes: detecting the passage of each blade of the first wheel past a first sensor; detecting the passage of each blade of the second wheel past a second sensor; calculating the time intervals between the passage of a blade of the first wheel and the passages of each of the blades of the second wheel; and determining the relative angular position of each blade of the first wheel relative to the angular positions of the blades of the second wheel, the first number and the second number being distinct and mutually prime.

An electric air pump system includes a housing in fluid communication with an inflatable body, a first valve, a first air pump for inflating and deflating the inflatable body, a second air pump for inflating the inflatable body, an air pressure sensor configured to detect the inner pressure of the inflatable body, and first and second prompting devices. The system also includes a control device electrically coupled to the first and second air pumps, the air pressure sensor, and the first and second prompting devices. The first prompting device outputs a first indication signal when the inner pressure is less than or equal to a first air pressure threshold and the second prompting device outputs a second indication signal when the second air pump inflates the inflatable body.

A fan brake circuit includes a semiconductor switch unit, a motor, a motor drive circuit, an isolation unit, a charging/discharging unit and a control unit. One end of the motor, the semiconductor switch unit and the control unit serves to receive an input power. When the fan is powered off, the semiconductor switch unit disconnects from the motor and the motor drive circuit receives the operation voltage provided by the charging/discharging unit and transmits the drive signal to the motor, whereby the motor forms a short-circuit to brake. By means of the design of the fan brake circuit, when the fan is powered off, the fan can quickly brake and stop and the cost is lowered.