Sundstrand Corporation

Stephen S Baits

Richard W Reynolds

A differential transmission mechanism using an output differential for a constant speed drive has desirable characteristics including full utilization of the torque capabilities of the hydraulic trim device associated with the output differential; however, there is a limitation on the utilization of the speed capability of the hydraulic components of the trim device at the low end of the input speed range. The disclosed differential transmission mechanism utilizing an output differential has a hydraulic trim device with a first hydraulic displacement unit having a normally fixed, approximately maximum displacement connected to an element of the output differential and a second hydraulic displacement unit which is of variable displacement connected to a variable speed input shaft. Additional components of the output differential are connected to the input shaft and to an output shaft connectable to a load. A sensing device senses the speed of the output shaft to control the displacement of the variable displacement hydraulic displacement unit to control the displacement thereof to achieve a constant output speed by varying the speed of the normally fixed displacement unit as required. Additionally, a sensor senses the speed of the input shaft and, when the speed of the input shaft is below a predetermined value, controls the displacement of the normally fixed displacement unit to reduce the displacement thereof to effectively make the latter displacement unit a smaller unit which will therefore operate at a faster speed to extend the range of the constant speed drive at the low end of the input speed range.

Differential transmission mechanism for a constant speed drive

For gear boxes, constant speed drives and the like having an airtight housing, a self-pressurization system includes a source of liquid, a pump having a discharge port connected to the housing, a check valve in a conduit extending between atmosphere and the pump intake port, and a valve responsive to the pressure differential between the housing and atmosphere and connected between the source of liquid and the pump intake port to deliver large amounts of liquid to the pump when the pressure differential is high and to deliver air and minimal lubricating amounts of liquid when the pressure differential is low.

Self-pressurization system for gearboxes and the like

An emergency hydraulic power system for aircraft which becomes operable upon aircraft engine failure includes a hot gas turbine for driving a hydraulic pump, a decomposition chamber to provide hot gas for driving the turbine, a normally unpressurized fuel storage tank, and a fuel pump for delivering fuel from the tank to the decomposition chamber. A start system includes a start fuel bottle having a cell filled with fuel and provided with a movable wall, and a cylinder of gas under high pressure which is regulated to put intermediate pressure on the movable wall and expel fuel from the cell, and also to put low pressure on the fuel tank, after a start valve is opened. Both the fuel tank and the start fuel cell communicate with an inlet conduit which goes to the fuel pump inlet, and a valve is provided to prevent start fuel from going into the fuel tank; and there is also means normally blocking communication from the start bottle and the tank to the pump inlet. Upon aircraft engine failure, the start valve is opened and the communication between the cell and the pump inlet is opened so that fuel from the start cell goes through the pump and through a pump outlet conduit to the decomposition chamber. At the same time, low gas pressure is placed upon the fuel in the tank. As the pump speed rises, the pump draws fuel from the tank and forces the fuel into the decomposition chamber, whereupon the start sequence is completed.

Growing community of inventors

Rockford, IL, United States of America

Stephen S Baits