System Description
HEATING / AIR CONDITIONING: AIR CONDITIONING SYSTEM (for Automatic Air Conditioning System): SYSTEM DESCRIPTION
1. GENERAL
(a) The air conditioning system has the following controls.
* *1: for 2GR-FE
2. NEURAL NETWORK CONTROL
* In the previous automatic air conditioning systems, the air conditioning amplifier assembly 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 air conditioning amplifier assembly. The air conditioning amplifier assembly 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 room 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 air conditioning amplifier assembly 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
* *1: Air blows out of registers only
* *2: Regular bi-level mode
* *3: Regular foot mode
* *4: Foot mode with large airflow volume from the rear footwell resister ducts
* *5: Foot mode with large airflow volume from defrosters
* The size of each circle o indicates the ratio of airflow volume.
5. COMPRESSOR
(a) General:
(1) The compressor is a continuously variable capacity type in which its capacity can be varied in accordance with the cooling load of the air conditioning system.
(2) The compressor consists of a pulley, shaft, lug plate, swash plate, piston, shoe, crank chamber, cylinder, solenoid valve with built-in Crank chamber to Suction passage (CS) valve, A/C flow sensor, oil separator and variable suction side throttle.
(3) The A/C pulley with built-in magnetic clutch has an A/C lock sensor that detects whether the compressor is locked.*1
(4) A solenoid valve is provided to enable the suction pressure to be controlled as desired.
(5) The Crank chamber to Suction passage (CS) valve, built into the solenoid valve, operates in accordance with the suction pressure.
(6) The oil separator is installed in the refrigerant passage to separate compressor oil from the refrigerant that is discharged. This helps to prevent the compressor oil from flowing into the air conditioning system and reducing cooling effectiveness.
* *1: for 2GR-FE
(b) Solenoid Valve Operation:
(1) The crank chamber is connected to the suction passage. A solenoid valve is provided between the suction passage (low pressure) and the discharge passage (high pressure).
(2) The solenoid valve operates under duty cycle control in accordance with the signals from air conditioning amplifier assembly.
(3) When the solenoid 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 swash plate. As a result, the piston stroke increases and the discharge capacity also increases.
(4) When the solenoid 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 swash plate. As a result, there is no piston stroke, and the discharge capacity is reduced.
(c) CS Valve Operation:
(1) The CS valve consists of passage A and passage B. If the vehicle is left parked for a long period, refrigerant may accumulate in the crank chamber due to the heat capacity difference.
(2) The solenoid control valve is controlled by the air conditioning amplifier assembly. While the compressor is operating, the solenoid control valve pushes down the CS valve rod and open passage A.
(3) Under the above condition, only if the refrigerant accumulates in the crank chamber, the crank chamber pressure will become high. As a result, the bellows will contract because of the pressure difference with its internal pressure (vacuum), and opens passage B.
(4) This causes the accumulated refrigerant to be drawn in via passage A and B, clearing the accumulated refrigerant earlier and ensuring a more immediate cooling effect.
6. A/C FLOW SENSOR
The A/C flow sensor, which is mounted on the compressor, is used to detect the amount of refrigerant flow. The A/C flow sensor converts the amount of refrigerant flow that is detected to a voltage value to send it to the air conditioning amplifier assembly. The voltage value sent from the A/C flow sensor changes depending on the amount of refrigerant flow. As the amount of refrigerant flow becomes larger, the voltage becomes lower. As the amount of refrigerant flow becomes smaller, the voltage becomes higher. The air conditioning amplifier assembly supplies 5 V to the A/C flow sensor and monitors changes in the voltage value sent from the A/C flow sensor. The air conditioning amplifier assembly then sends a signal to the ECM via CAN communication to allow the ECM to control the engine speed while the air conditioning is on.
7. A/C LOCK SENSOR (for 2GR-FE)
The A/C lock sensor sends A/C pulley speed signals to the air conditioning amplifier assembly. The air conditioning amplifier assembly determines whether the A/C compressor is locked or not by using those signals and engine speed signals.
8. EVAPORATOR TEMPERATURE SENSOR (NO. 1 COOLER THERMISTOR)
The evaporator temperature sensor (No. 1 cooler thermistor) detects the temperature of the cool air immediately through the evaporator in the form of resistance changes, and outputs it to the air conditioning amplifier assembly.
9. BLOWER WITH FAN MOTOR SUB-ASSEMBLY
The blower motor has a built-in blower controller, and is controlled using duty control performed by the air conditioning amplifier assembly.
10. BUS CONNECTOR (AIR CONDITIONING HARNESS ASSEMBLY)
(a) BUS connectors are used in the wire harness that connects the servo motors to the air conditioning amplifier assembly.
(b) Each BUS connector has a built-in communication/driver IC which communicates with the air conditioning amplifier assembly, 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.
11. SERVO MOTOR
The pulse pattern type servo motor consists of a printed circuit board and a servo motor. The printed circuit board has three contact points, and can transmit two ON-OFF signals to the air conditioning amplifier assembly based on the difference of the pulse phases. The BUS connector can detect the damper position and movement direction with these signals.
12. ROOM TEMPERATURE SENSOR (COOLER THERMISTOR)
The room temperature sensor (cooler thermistor) detects the cabin temperature based on changes in the resistance of its built-in thermistor and sends a signal to the air conditioning amplifier assembly.
13. AMBIENT TEMPERATURE SENSOR (THERMISTOR ASSEMBLY)
The ambient temperature sensor (thermistor assembly) detects the outside temperature based on changes in the resistance of its built-in thermistor and sends a signal to the air conditioning amplifier assembly.
14. SOLAR SENSOR (AUTOMATIC LIGHT CONTROL SENSOR)
(a) The solar sensor (automatic light control sensor) consists of a photo diode, two amplifier circuits for the solar sensor (automatic light control sensor), and frequency converter circuit for the light control sensor.
(b) The solar sensor (automatic light control sensor) detects (in the form of changes in the current that flows through the built-in photo diode) the changes in the amount of sunlight from the LH and RH sides (2 directions) and outputs these sunlight strength signals to the air conditioning amplifier assembly.
15. AIR CONDITIONING PRESSURE SENSOR
The air conditioning pressure sensor detects the refrigerant pressure and outputs it to the air conditioning amplifier assembly in the form of voltage changes.