Abstract: An improved motor vehicle automatic climate control methodology develops HVAC commands for transient phase operation independent of the HVAC commands calibrated for steady-state phase operation. At system activation, a transient phase indicator is initialized based on the cabin temperature and the set temperature, and thereafter updated to reflect progress toward steady-state phase operation. The steady-state HVAC commands are based on ambient conditions and the set temperature, and the HVAC commands at system activation are based on the steady-state commands and offsets based on the initial in-car temperature. A transient modifier based on the transient phase indicator brings the initial HVAC commands into correspondence with the steady-state HVAC commands as the cabin temperature approaches the set temperature.

Abstract: A motor vehicle automatic climate control determines HVAC parameter values for satisfying the required heating or cooling effort for steady-state cabin air temperature regulation, and controls the HVAC settings based such parameter values and on the deviation of the cabin air temperature (Tcabin) from the set temperature (TSET). If Tcabin is within a specified control band about TSET, the HVAC settings are controlled in accordance with the determined HVAC parameter values, but when Tcabin overshoots or undershoots the control band, the control enters a quasi-steady-state mode in which the control parameters are reset to drive Tcabin back in to the control band, and then brought into correspondence with the respective determined values based on the degree to which the overall control objective of regulating Tcabin at TSET is achieved.

Abstract: A motor vehicle automatic climate control computes the HVAC power requirement for cabin air temperature regulation, and determines corresponding air discharge temperature and blower motor speed commands using a two-step table look-up procedure. Nominal air discharge temperature and blower motor speed profiles are tabulated as a function of a Power Index generally corresponding to ambient temperature, and used along with the set temperature to form a table of HVAC power requirement vs. Power Index. In vehicle operation, the HVAC power requirement vs. Power Index table is used to retrieve a Power Index corresponding to the computed HVAC power requirement, and the air discharge temperature and blower motor speed tables are then used to retrieve air discharge temperature and blower motor speed commands based on the retrieved Power Index.

Abstract: Optimized control algorithms for a vehicle automatic climate control system (ACCS) are developed using math-based models of the vehicle, the ACCS and a vehicle occupant. The models are cross-coupled in closed-loop fashion with feedback from both vehicle systems and occupant. A first feedback loop including the vehicle and the ACCS, simulates how the ACCS interacts with the cabin environment; and a second feedback loop including the vehicle, the ACCS and the occupant, simulates how the occupant will adjust the ACCS to optimize comfort. When the system arrives at a control algorithm that satisfies control objectives and optimizes occupant comfort, an auto-code generation tool is used to create program code directly from the control model, which may be downloaded into a test vehicle for final system confirmation and calibration.

Abstract: An improved compressor capacity control method selectively overrides a normal capacity control during periods of vehicle acceleration to reduce engine exhaust emissions. The capacity override is invoked when the rate of engine throttle movement exceeds a predefined rate, provided that the load imposed by the compressor is sufficiently high and the vehicle speed is greater than a minimum value. Once invoked, the override reduces the compressor capacity to a predetermined level, and measures the elapsed time. The override is maintained for at least a minimum time period that ensures an emission benefit, after which the vehicle speed is monitored to determine the extent of the acceleration. The override is terminated when the rate of increase in vehicle speed falls below a reference rate, or when the elapsed time exceeds a reference time, whichever occurs first.

Abstract: A control method for a motor vehicle HVAC system categorizes potentially conflicting override commands for at least one control parameter in order to assign a priority of control. Override commands are categorized as being related to occupant safety, vehicle safety or occupant comfort. Highest priority is assigned to override commands categorized as being related to occupant safety, second-highest priority is assigned to override commands categorized as being related to vehicle safety, and third-highest priority is assigned to override commands categorized as being related to occupant comfort. An HVAC controller carrying out the control method then regulates the control parameter in accordance with the override command that has been assigned the highest priority.

Abstract: An improved motor vehicle automatic climate control methodology develops HVAC commands for transient phase operation independent of the HVAC commands calibrated for steady-state phase operation. At system activation, a transient phase indicator is initialized based on the cabin temperature and the set temperature, and thereafter updated to reflect progress toward steady-state phase operation. The steady-state HVAC commands are based on ambient conditions and the set temperature, and the HVAC commands at system activation are based on the steady-state commands and offsets based on the initial in-car temperature. A transient modifier based on the transient phase indicator brings the initial HVAC commands into correspondence with the steady-state HVAC commands as the cabin temperature approaches the set temperature.

Abstract: An improved method of electric window heater activation automatically and independently activates front and rear window heaters at a variable level based on the respective potential of fogging, within the ability of the vehicle electrical system to supply the requested current without discharging the storage battery. A defog controller develops front and rear fog factors indicative of the relative potential of fogging, and activates the respective electric heaters as required to drive the respective fog factor to zero. The fog factors are based on an estimate of the cabin air dewpoint temperature, the temperature of the respective window surfaces, and a temperature interval over which the fog factor signals only partial activation of the respective heater. The temperature interval is biased in a direction to provide preventative activation of the heaters at a relatively low level when the electrical power requirement is limited, and the activation level is limited as required to prevent battery discharging.

Abstract: An energy-efficient air conditioning control method regulates the capacity of a variable capacity refrigerant compressor based on the compressor suction and discharge pressures and a measure of the ambient temperature. A target suction pressure is selected based on the ambient temperature and the sensed discharge pressure, and the capacity of the compressor is adjusted as required to attain the target suction pressure. In a first embodiment of the control method, the ambient temperature is used to select a target evaporator outlet air temperature, which is used along with the sensed discharge pressure to select the target suction pressure, while in a second embodiment of the control method, the target suction pressure is selected directly on the basis of the ambient temperature and the sensed discharge pressure.

Abstract: Optimized control algorithms for a vehicle automatic climate control system (ACCS) are developed using math-based models of the vehicle, the ACCS and a vehicle occupant. The models are cross-coupled in closed-loop fashion with feedback from both vehicle systems and occupant. A first feedback loop including the vehicle and the ACCS, simulates how the ACCS interacts with the cabin environment; and a second feedback loop including the vehicle, the ACCS and the occupant, simulates how the occupant will adjust the ACCS to optimize comfort. When the system arrives at a control algorithm that satisfies control objectives and optimizes occupant comfort, an auto-code generation tool is used to create program code directly from the control model, which may be downloaded into a test vehicle for final system confirmation and calibration.

Abstract: An energy-efficient vehicle air conditioning system includes a variable capacity refrigerant compressor having a capacity control valve with integral refrigerant sensors and control circuitry, and a driver interface panel for selecting the discharge air temperature and inlet air source, and for selecting either a normal control mode or an energy-efficient control mode. When the energy-efficient control mode is selected, control setting indicators prompt the driver to request full-cold discharge air temperature and recirculated cabin air, and the control circuitry initiates a compressor capacity control based on the refrigerant sensor information and a measure of the outside air temperature to produce a suitable discharge air temperature at a reduced power consumption level.

Abstract: An improved method of electric window heater activation automatically and independently activates front and rear window heaters at a variable level based on the respective potential of fogging, within the ability of the vehicle electrical system to supply the requested current without discharging the storage battery. A defog controller develops front and rear fog factors indicative of the relative potential of fogging, and activates the respective electric heaters as required to drive the respective fog factor to zero. The fog factors are based on an estimate of the cabin air dewpoint temperature, the temperature of the respective window surfaces, and a temperature interval over which the fog factor signals only partial activation of the respective heater. The temperature interval is biased in a direction to provide preventative activation of the heaters at a relatively low level when the electrical power requirement is limited, and the activation level is limited as required to prevent battery discharging.

Abstract: An accurate and low cost sensing apparatus for a swash or wobble plate compressor that requires no modifications in compressor design or operation, and which provides a repeatable and accurate measure of compressor speed and stroke. The apparatus includes a sensor module and a stroke sensing circuit. The compressor has an outer housing formed of aluminum or other non-magnetic material, as is customary in automotive air conditioning systems. The sensor module includes a magnetic field responsive sensor such as a Hall Effect or magneto-resistive (MR) sensor, and is attached to the periphery of the housing in proximity to a reciprocating ferrous element such as a bushing shoe on the swash or wobble plate assembly. The sensor produces a quasi-sinusoidal output voltage signal having a frequency proportional to compressor speed, and the stroke sensing circuit determines the compressor stroke by band-pass filtering, amplifying, and peak detecting the signal.

Abstract: In a method for the diagnosis of an air conditioning system having a condenser, an evaporator, an expansion device and a compressor, the stroke of which can be set via a valve, a maximum compressor stroke is set abruptly when the air conditioning system is running and a pressure impulse arising in the high pressure side of the refrigerant circuit is measured in order to determine the degree of filling of the refrigerant circuit.

Abstract: In a method for the temperature regulation of an air conditioning system having a condenser, an evaporator, an expansion device and a compressor, the stroke of which can be set via a valve, the temperature in the region of the air outlet of the evaporator is measured and a desired temperature is set by a controlling of the valve. The temperature regulation additionally takes place in dependence on the refrigerant pressure.

Abstract: An improved control method for an electronically controlled variable displacement refrigerant compressor, where the control has normal and high speed displacement control modes, with smooth transitions between such control modes. The displacement control mechanism is in the form of a solenoid valve, and the valve is pulse-width-modulated (PWM) at a variable duty cycle to regulate displacement of the compressor. When the compressor is operating in a normal speed range, a first control mode determines a normal PWM duty cycle to satisfy cooling demand; when the compressor is operating in a high speed range, a second control mode determines an alternate PWM duty cycle based on compressor speed. The solenoid valve is operated in accordance with the duty cycle corresponding to the lower displacement. A smooth transition from the normal control mode to the high speed control mode is achieved by scheduling the alternate duty cycle as a function of compressor speed.