Heating and Air Conditioning: Description and Operation
System Diagram:
System Diagram:
System Diagram:
SYSTEM DIAGRAM
SYSTEM DESCRIPTION
General
The air conditioning system has the controls shown in the provided table.
Mode Position And Damper Operation
Air Outlet And Airflow Volume
Neural Network Control
- In the previous automatic air conditioning system, the ECU determined the required outlet air temperature and blower air volume in accordance with the calculation formula that has been obtained based on information received from the sensors.
However, because the sensors of a person is situated. For example, a given amount of solar radiation can feel comfortably warm in a cold climate, or extremely uncomfortable in a hot climate. Therefore, as a technique for effecting a higher level of control, a neural network has been adopted in the automatic air conditioning system. With this technique, the data that has been collected under varying environmental conditions is stored in the ECU, which effects control to provide enhanced air conditioning comfort.
- The neural network control consists of neurons in the input layer, intermediate layer, and output layer. The input layer neurons process the input data of the outside temperature, the amount of sunlight, and the cabin temperature based on the outputs of the switches and sensors, and output them to the intermediate layer neurons. Based on this data, the intermediate layer neurons adjust the strength of the links among the neurons. The sum of these is then calculated by the output layer neurons in the form of the required outlet temperature, solar correction, target airflow volume, and outlet mode control volume. Accordingly, Air Conditioning ECU controls the servomotors and blower motor in accordance with the control volumes that have been calculated by the neural network control.
Self-diagnosis
Air Conditioning ECU has a self-diagnosis function. It stores any operation failures in the air conditioning system memory in the form of DTC (Diagnostic Trouble Code).
- There are two methods for reading DTCs. One is to use a hand-held tester, and the other is to read the DTC on the heater control panel switch.
- DTCs are shown on the center display or multi display of the multi-information display, and on the hand-held tester.
Heater Control Panel
Push-button type heater control panel is used. The temperature control switches for the driver and front passenger are provided on the heater control panel to enhance their ease of use.
Air Conditioning Unit
A semi-center location air conditioner unit, in the evaporator and heater core are placed in the vehicle's longitudinal direction, is used. As result, the air conditioning unit is made compact and lightweight.
Evaporator
A revolutionary super-slim structure evaporator is used. Placing the tanks at the top and the bottom of the evaporator and adopting a micropore tube construction have realized the following effects:
- The heat exchanging efficiency is improved.
- The temperature distribution is made more uniform.
- The evaporator is made thinner. 58 mm (2.3 in.) -> 38 mm (1.5 in.)
Heater Core
A compact, lightweight, and highly efficient straight flow (fullpath flow) aluminum heater core is used.
Blower Motor
The blower motor has an in-built blower controller, and is controlled with the duty control from the Air Conditioning ECU.
Bus Connector
A BUS connector is used in the wire harness connection that connects the servomotor from the Air Conditioning ECU.
The BUS connector has an in built communication / drive IC which communicates with each servomotor connector, actuates the servomotor, and position detection function. This enables bus communication for the servo motor wire harness, for a more lightweight construction and a reduced number of wires.
Servo Motor
The pulse pattern type servomotor consists of a printed circuit board and servomotor. The printed circuit board has three contact points, phase. The smart connector detects the damper position and movement direction with this signal.
Clean Air Filter
A clean air filter (micro dust and pollen filter) is used. This filter excels in the removal of dust and pollen.
The filter made be disposed of easily as a combustible material, a feature that is provided in consideration of the environment.
Condenser
The condenser consisting of two cooling portions: a condensing portion and a super-cooling portion, and gas-liquid separator (modulator) all integrated together. This condenser uses a sub-cool cycle that offers excellent heat-exchange performance.
- In the sub-cool cycle, after the refrigerant passes through the condensing portion of the condenser, both the liquid refrigerant and the gaseous refrigerant that could not be liquefied are cooled again in the super-cooling portion. Thus, the refrigerant is sent to the evaporator in an almost completely liquefied state.
A/C Compressor
A/C compressor is continuously variable capacity type in which its capacity varies in accordance with the cooling load of the air conditioning.
- This compressor consists of the shaft, lug plate, piston, shoe, crank, chamber, cylinder, and solenoid control valve.
- A solenoid control valve that adjusts the suction pressure so that the suction pressure can be controlled as desired is provided.
- The crank chamber is connected to the suction passage. A solenoid control valve is provided between the suction passage (LO pressure) and the discharge passage (HI pressure).
- The solenoid control valve operates under duty cycle control in accordance with the signals from A/C ECU.
- When the solenoid control valve closes (solenoid coil is energized), a difference in pressure is created and the pressure in the crank chamber decreases. Then, the pressure that is applied to the right side of the piston becomes greater than the pressure that is applied to the left side of the piston. This compresses the spring and tilts the lug plate. As a result, the piston stroke increases and the discharge capacity increases.
- When the solenoid control valve opens (solenoid coil is not energized), the difference in pressure disappears. Then, the pressure that is applied to the right side of the piston. Thus, the spring elongates and eliminates the tilt of the lug plate. As a result, there is no piston stroke and the discharge capacity turns to decrease.