Air Conditioning System (for Automatic Air Conditioning System)

HEATING / AIR CONDITIONING: AIR CONDITIONING SYSTEM (for Automatic Air Conditioning System): SYSTEM DIAGRAM

SYSTEM DIAGRAM




















HEATING / AIR CONDITIONING: AIR CONDITIONING SYSTEM (for Automatic Air Conditioning System): SYSTEM DESCRIPTION

SYSTEM DESCRIPTION

1. GENERAL
The air conditioning system has the following controls:






2. NEURAL NETWORK CONTROL

- In previous automatic air conditioning systems, the A/C amplifier 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 senses of a person are rather complex, a given temperature is sensed differently, depending on the environment in which the 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 A/C amplifier. The A/C amplifier can then effect 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, the A/C amplifier controls the servo motors and blower motor in accordance with the control volumes that have been calculated by the neural network control.





3. MODE POSITION AND DAMPER OPERATION
(a) Mode position and damper operation





Functions of Main Dampers:





4. AIR OUTLETS AND AIRFLOW VOLUME
(a) Air Outlets and Airflow Volume









The size of the circle o indicates the proportion of airflow volume.
5. BLOWER MOTOR
The blower motor has a built-in blower controller, and is controlled with duty control from the A/C amplifier.
6. BUS CONNECTOR
(a) A BUS connector is used in the wire harness connection that connects the servo motor from the A/C amplifier.
(1) for TMC Made




(2) for NUMMI, TMMC Made





(b) Each BUS connector has a built-in communication/driver IC which communicates with each servo motor connector, actuates the servo motor, and has a position detection function. This enables bus communication for the servo motor wire harness, for a more lightweight construction and a reduced number of wires.





7. SERVO MOTOR
(a) In contrast to the previous type that detects the position using potentiometer voltage, the pulse pattern type servo motor detects the relative position using the 2-bit ON/OFF signals.
The forward and reverse revolutions of this motor are detected by way of two phases, A and B, which output four types of patterns. The air conditioning amplifier counts the number of pulse patterns in order to determine the stopped position.





8. A/C COMPRESSOR
(a) General
(1) The A/C compressor is a continuously variable capacity type in which its capacity varies in accordance with the cooling load of the air conditioning system.
(2) The compressor consists of the shaft, lug plate, piston, shoe, crank chamber, cylinder, and solenoid control valve.
(3) The solenoid control valve is provided to enable the suction pressure to be controlled as desired.
(4) A plastic DL (Damper Limiter) type A/C pulley is used.
(5) A rotary type valve is used to suction refrigerant gas into the cylinder.





(b) Operation
(1) The crank chamber is connected to the suction passage. A solenoid control valve is provided between the suction passage (low pressure) and the discharge passage (high pressure).
(2) The solenoid control valve operates under duty cycle control in accordance with the signals from the air conditioning amplifier.




(3) 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, there is a large piston stroke and the discharge capacity increases.




(4) When the solenoid control valve opens (solenoid coil is not energized), the difference in pressure disappears. Then, the pressure that is applied to the left side of the piston becomes the same as the pressure that is applied to the right side of the piston. Thus, the spring elongates and eliminates the tilt of the lag plate. As a result, there is a small piston stroke and the discharge capacity decreases.





9. ROOM TEMPERATURE SENSOR
The room temperature sensor detects the cabin temperature based on changes in the resistance of its built-in thermistor and sends a signal to the A/C amplifier.
10. AMBIENT TEMPERATURE SENSOR
The ambient temperature sensor detects the outside temperature based on changes in the resistance of its built-in thermistor and sends a signal to the A/C amplifier.
11. EVAPORATOR TEMPERATURE SENSOR
The evaporator temperature sensor detects the temperature of the cool air immediately after the evaporator in the form of resistance changes, and outputs it to the A/C amplifier.
12. SOLAR SENSOR
The solar sensor detects the changes in the amount of sunlight and outputs it to the A/C amplifier in the form of voltage changes.
13. A/C PRESSURE SENSOR
The A/C pressure sensor detects the refrigerant pressure and outputs it to the A/C amplifier in the form of voltage changes.
14. PTC HEATER (w/ PTC Heater)
(a) General
(1) The PTC heater is located above the heater core in the air conditioner unit.
(2) The PTC heater consists of a PTC element, aluminum fin, and brass plate. When current is applied to the PTC element, it generates heat to warm the air that passes through the unit.





(b) PTC Heater Operating Conditions
(1) The PTC heater is turned on and off by the air conditioning amplifier in accordance with the coolant temperature, ambient temperature, engine speed, air mix setting, and electrical load (generator power ratio).
For example, the number of the operating PTC heaters varies by the coolant temperature as in the graph below.