Abstract: A system and method are provided for monitoring the levels of combustible gas in a gas stream. The system includes means for controlling the relative humidity of the the gas stream to maintain a humidity level in the performance range of combustible gas sensors. A number techniques are illustrated for achieving the humidity control, including, secondary phase separations, mixing the gas with dry air and adjusting of the gas stream temperature.

Abstract: A system and method are provided for monitoring the levels of combustible gas in a gas stream. The system includes means for controlling the relative humidity of the the gas stream to maintain a humidity level in the performance range of combustible gas sensors. A number techniques are illustrated for achieving the humidity control, including, secondary phase separations, mixing the gas with dry air and adjusting of the gas stream temperature.

Abstract: An exhaust brake for an internal combustion engine is disclosed. The exhaust brake includes a main valve and a bypass valve for restricting the flow of exhaust gas. The main valve may be selectively closed, while the bypass valve is biased into a closed position with a selective biasing force. Closing the main valve may cause exhaust back pressure to build against the bypass valve until the biasing force is overcome. When the biasing force is surpassed by the exhaust back pressure, the bypass valve opens to relieve the back pressure. The bypass valve closes when back pressure falls below the biasing force. The biasing force may be varied to operate the exhaust brake at a maximum back pressure for a given engine speed and/or engine condition. A method of operating the exhaust brake is also disclosed.

Abstract: An exhaust restriction device for an internal combustion engine is disclosed. The exhaust restriction device includes a main valve and a bypass valve for restricting the flow of exhaust gas. The main valve is located in a main passage and may be selectively closed. The bypass valve is located in a bypass passage and is biased into a position closing a port connecting the main passage and the bypass passage. Closing the main valve may cause exhaust back pressure to build against the bypass valve and an actuator therefor until the biasing force is overcome. When the biasing force is surpassed by the exhaust back pressure, the bypass valve opens to relieve the back pressure. The bypass valve closes when back pressure falls below the biasing force. A method of operating the exhaust restriction device is also disclosed.

Abstract: A system and method for controlling a vacuum operated exhaust brake. A vehicle may be provided with service brake assistance and an exhaust brake, each of which may be driven by a common vacuum source. In the event the available vacuum is likely to be insufficient to meet the demand of the service brake assistance system, the exhaust brake may be selectively isolated from the vacuum source. Exhaust brake isolation may be responsive to a sensed vacuum parameter, such as the magnitude of the vacuum and/or the rate of change of the vacuum. Vacuum communication between the exhaust brake and the vacuum source may be reestablished responsive to the sensed vacuum parameter.

Abstract: An exhaust brake for an internal combustion engine is disclosed. The internal surfaces of the exhaust brake are aerodynamically shaped and sized to reduce the incidence of turbulent flow through the exhaust brake. The shape of the internal passage through the brake housing may be dictated by the requirement of maintaining as close to a laminar flow through the passage as possible when the brake valve is open. The ideal brake housings of the internal passage may be determined for exhaust brakes of various shapes and sizes. The ideal shapes may be typified as having non-uniform wall thicknesses. The ideal shapes of the internal brake surfaces, including that of the valve, may also be typified by the elimination of square edges (which trigger turbulence). Ideal flow through the exhaust brake may also be obtained by the reduction of bulk in the exhaust flow (minimization of the profile of the valve in the flow when the valve is open).