Abstract: An improved blower motor speed control resistor array in which the resistor elements are defined by multiple optimally sized patches of resistive ink deposited onto opposite sides of a thin flat ceramic substrate. The array comprises three resistive patches connected in series via fusing elements to provide three reduced blower motor speeds MH, M and L. The thin ceramic substrate is flat on both of its faces, and each face comprises a terminal region for attachment of the resistive patches to the terminal elements, and a resistor region for deposition of the three resistive patches. The resistive patch of lowest resistivity (the MH resistor) is deposited on the entire resistor region of a first side of the substrate. The resistor patches of intermediate and highest resistivity (the M and L resistors, respectively) share the resistor region of the other side of the substrate in relation proportion to their respective resistivities.

Abstract: A control method for a variable capacity automotive air conditioning compressor in which the compressor operating point is tailored to the nonlinear control characteristics of variable displacement compressors. When the error between the desired and actual values of a specified system parameter is relatively large, the operating point is determined by a coarse gain closed-loop control. When the error is within a fine control range defined in relation to the desired value, the control point is set to one of three predetermined values for effecting small displacement increases, small displacement decreases, or no change in displacement. An adaptive tuning technique is used to update the predetermined control point values to compensate for compressor-to-compressor differences and changes in the operating conditions of a given compressor system. An anticipation technique shortens the transition from coarse control to fine control by minimizing gross overshoots of the specified system parameter.

Abstract: A low charge protection method for an electronically controlled variable displacement compressor. In each period of compressor operation, a low charge test sequence is carried out to monitor the system performance once the system control pressure has been reduced below a specified level. In a set-up phase of the test, the compressor is down-stroked to near-minimum displacement for a predetermined time or until the system control pressure rises above a reference level. At such point, the compressor is up-stroked to near-maximum displacement to initiate a pull-down phase of the test. If the system pressure is reduced by specified amount within a reference interval, a failed test is indicated and the count in a nonvolatile counter is incremented. If the pull-down duration exceeds the reference interval, a passed test is indicated, and the count, if any, is decremented.

Abstract: A control method for a variable capacity automotive engine driven air conditioning compressor in which the onset of an overspeed condition is anticipated in relation to the compressor speed and acceleration for the purpose of initiating an override of the normal control setting to quickly destroke the compressor so long as the overspeed condition is indicated. In normal operation, the control setting for the air conditioning system is chosen in relation to the current compressor speed. The compressor capacity is electrically controlled in relation to the error between the control setting and an actual or measured setting. Concurrently, a secondary control setting is determined based on an estimate of a future compressor speed, given the current rate of change in compressor speed. When the secondary control setting would produce more destroke than the primary control setting, the secondary control overrides the primary control to protect the compressor should the current conditions continue.