AIR CONDITIONING SYSTEM (for Automatic Air Conditioning System) SYSTEM DESCRIPTION

  1. GENERAL

    1. The air conditioning system has the following controls.

      Control Outline
      Neural Network Control This control is capable of performing complex control by artificially simulating the information processing method of the nervous system of living organisms in order to establish a complex input/output relationship similar to that of a human brain.
      Outlet Air Temperature Control Based on the temperature set by the temperature control dial, neural network control calculates outlet air temperature based on input signals from various sensors.
      Left and Right Independent Control The temperature settings for the driver and front passenger are controlled independently in order to provide separate vehicle interior temperatures for the right and left sides of the vehicle. Thus, air conditioning that accommodates the occupants' preferences has been realized.
      Blower Control Controls the blower motor in accordance with the airflow volume that has been calculated by neural network control based on the input signals from various sensors.
      Air Outlet Control Automatically switches the air outlets in accordance with the outlet mode that has been calculated by neural network control.
      In accordance with the engine coolant temperature, ambient air temperature, amount of sunlight, required blower, outlet temperature and vehicle speed conditions, this control automatically switches the blower outlet to foot and defroster mode to prevent the windows from becoming fogged up when the ambient air temperature is low.
      Air Inlet Control Automatically controls the air inlet control damper to help achieve the calculated outlet air temperature that is required.
      Drives the air inlet control servo motor according to the operation of the air inlet control switch and moves the dampers to the fresh or recirculation position.
      Compressor Control Through the calculation of the target evaporator temperature based on various sensor signals, the air conditioning amplifier optimally controls discharge capacity by regulating the opening extent of the compressor solenoid valve.
      The air conditioning amplifier compares the pulley speed signals (transmitted by the lock sensor located on the compressor) with the engine speed signal (which are transmitted by the ECM (crankshaft position sensor)). When the air conditioning amplifier determines that the pulley is locked, it turns off the magnetic clutch.*1
      Defroster Control Defroster control logic is used to improve defroster performance.
      Rear Defogger Control

      When the ignition switch is ON and the rear defogger switch is pushed, the system is activated to keep the defogger heater on for approx. 15 minutes. However, the operating time of the rear defogger can be extended up to approx. 45 minutes when both of the following requirements are met:

      • Ambient Temperature: -3°C (27°F) or below

      • Vehicle Speed: 45 km/h (28 mph) or more
      Diagnosis A Diagnostic Trouble Code (DTC) is stored in memory when the air conditioning amplifier detects a problem with the air conditioning system.

      • *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.

    A011S5FE01

  3. MODE POSITION AND DAMPER OPERATION

    1. Mode Position and Damper Operation

      A011R7RE01
      Functions of Main Dampers
      Control Damper Operation Position Damper Position Operation
      Air Inlet Control Damper FRESH A Allows fresh air to enter.
      RECIRCULATION B Causes internal air to recirculate.
      Air Mix Control Damper MAX COLD to MAX HOT Temperature Setting

      C - D - E

      (C' - D' - E')

      T - U - V

      		 Varies the mixture ratio of the warm air and cool air in order to regulate the temperature continuously between hot and cold.
      Air Outlet Control Damper

      DEF

      A011SOF       		F, J, L, P, S, Y Defrosts the windshield through the center defroster, side defrosters and side registers.

      FOOT / DEF

      A011UHV       		G, J, L, P, Q, X Defrosts the windshield through the center defroster, side defrosters, side registers, and rear center register, while air is also blown out from the front and rear footwell register ducts.

      FOOT

      A011QU7       		H, J, L, P, Q, X Air blows out of the front and rear footwell register ducts, and side registers. In addition, air blows out slightly from the center defroster and side defrosters.

      BI-LEVEL

      A011RCR       		I, K, N, O, R, X Air blows out of the front and rear center registers, side registers and front and rear footwell register ducts.

      FACE

      A011RWL       		I, K, M, O, S, W Air blows out of the front and rear center registers, and side registers.

  4. AIR OUTLETS AND AIRFLOW VOLUME

    1. Air Outlets and Airflow Volume

      A011STKE01
      MODE Selection Register Footwell Defroster
      Automatic Manual CTR SIDE RR FR RR CTR SIDE
      A B C D E F G
      FACE-U*1 A011RWL A011TJQ A011TJQ A011UWQ A011UWQ A011UWQ A011SN6 A011SN6 A011SN6 A011SN6
      B/L-U*2 A011RCR A011TJQ A011TJQ A011T4S A011T4S A011T4S A011RJA A011RJA A011SN6 A011SN6
      FOOT-F*3 A011QU7 A011TJQ A011SN6 A011SN6 A011RJA A011RJA A011T4S A011RJA A011R4S A011R4S
      FOOT-R*4 A011TJQ A011TJQ A011SN6 A011RJA A011RJA A011T4S A011T4S A011R4S A011R4S
      FOOT-D*5 A011TJQ A011SN6 A011SN6 A011RJA A011RJA A011RJA A011RJA A011RJA A011RJA
      F/D A011UHV A011TJQ A011TJQ A011SN6 A011RJA A011RJA A011T4S A011T4S A011T4S A011T4S
      DEF A011SOF A011TJQ A011TJQ A011SN6 A011RJA A011SN6 A011SN6 A011SN6 A011SOG A011SOG

      • *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 ○ indicates the ratio of airflow volume.

  5. COMPRESSOR

    1. 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

    2. 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.

    3. 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)

    1. BUS connectors are used in the wire harness that connects the servo motors to the air conditioning amplifier assembly.

      A011S5CE04

    2. 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.

      A011QUKE03

  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.

    A011T6UE04

  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)

    1. 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.

    2. 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.

      A011QW5E09

  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.