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Air compressor control

Air compressor control description/claims

This patent application is a continuation of pending U.S. patent application Ser. No. 11/010,851 entitled “Air Compressor Control” filed on Dec. 13, 2004, the entire disclosure of which is incorporated by reference as if fully rewritten herein.

The present disclosure relates generally to air compressor control in an internal combustion engine, and more particularly, to controlling activation and deactivation of an air compressor based on a temperature of compressed air.

Modern trucks contain air compressors which are used to charge an air tank from which air-powered systems, such as service brakes, windshield wipers, air suspension, etc., can draw air. In a typical trucking application, an air compressor can run in a loaded or activated state a large percentage of the time. Systems have been developed to reduce the amount of time the air compressor is activated. For example, systems have been developed that activate the compressor when pressure in a reservoir drops below a first predetermined value, and deactivates the compressor when pressure in the reservoir reaches a second, higher predetermined value.

U.S. Pat. No. 6,036,449 to Nishar et al. discloses an air compressor control that monitors the pressure in the reservoir and the head metal temperature of the compressor. When the reservoir is of a pressure between the two set pressures and is in a loaded state, the air compressor will be unloaded after a set time interval that is based on a compressor head metal temperature to maintain threshold temperatures of the compressor head metal within a suitable range. Additionally, the compressor head is evaluated such that whenever the compressor head temperature exceeds a predetermined threshold temperature the air compressor is placed in an unloaded state until the compressor head temperature drops below the predetermined threshold temperature. The head metal temperature is controlled to prevent excessive heating of the head.

The present application relates to controlling air compressors based on a temperature of air compressed by the air compressor. In one method of controlling an air compressor, a temperature of air compressed by the air compressor is sensed. The sensed compressed air temperature is compared with a predetermined threshold temperature. The air compressor is deactivated when the sensed temperature exceeds the threshold temperature. In one embodiment, the air compressor is deactivated when the sensed temperature exceeds the threshold temperature and a sensed reservoir pressure is above the threshold pressure. In one embodiment, the threshold temperature is selected to inhibit carbon formation caused by oil breakdown.

The temperature of the compressed air may be sensed at a variety of locations. For example, the temperature of the compressed air may be sensed in a compressor port, such as an exhaust port, or an unloader valve port. The temperature of the compressed air may be sensed in a compression chamber. In one embodiment, the temperature of the compressed air is sensed by a temperature sensor mounted in a compressor unloader valve that is in fluid communication with a compression chamber.

One air compressor that is adapted for control based on a temperature of the compressed air includes a housing, a head, a piston, and a temperature sensor. The head is mounted to the housing, such that the head and the housing define a compression chamber and a fluid passage in communication with the compression chamber. The piston is disposed in the compression chamber for compressing air in the compression chamber. The temperature sensor is positioned to measure a temperature of air compressed by the piston. In one embodiment, the temperature sensor is substantially isolated from the head and the housing.

One air compressor controller includes an input, a memory, a processor, and an output. The input receives compressor air temperature signals. The memory stores a compressor control algorithm. The processor applies the compressor control algorithm to the compressor air temperature signals. The processor provides an air compressor deactivation signal when the compressor air temperature signal exceeds the threshold temperature signal value. The output communicates the compressor deactivation signal to selectively deactivate a controlled air compressor. Alternatively, the controller can be comprised of discrete electronic components with no processor or memory. For example, the controller could comprise one temperature component integrated circuit could convert input signals to voltages and one voltage comparator component could control the output based on voltage thresholds.

One vehicle air supply system includes a reservoir, an air compressor, a temperature sensor, and a controller. The reservoir stores compressed air provided by the compressor. The temperature sensor is positioned to sense a temperature of the compressed air. The controller is linked to the compressor. The controller compares a sensed temperature of the air compressed by the air compressor with a predetermined threshold temperature and deactivates the air compressor when the sensed temperature exceeds the threshold temperature. In one embodiment, the controller activates the compressor when an air pressure in the reservoir is less than a predetermined threshold pressure and the sensed temperature exceeds the threshold temperature.

Further advantages and benefits will become apparent to those skilled in the art after considering the following description and appended claims in conjunction with the accompanying drawings.

FIG. 1 is a schematic illustration of a vehicle air supply system;

FIG. 2 is a flow chart that illustrates a method of controlling an air compressor based on a temperature of compressed air;

FIG. 3 is a schematic illustration of a vehicle air supply system;

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