Air Conditioning System (for Automatic Air Conditioning System)
AIR CONDITIONING: AIR CONDITIONING SYSTEM (for Automatic Air Conditioning System): SYSTEM DIAGRAM
AIR CONDITIONING: AIR CONDITIONING SYSTEM (for Automatic Air Conditioning System): SYSTEM DESCRIPTION
1. GENERAL
(a) The air conditioning system has the following features:
* An automatic, dual-control air conditioning system comprising front/rear independent temperature control is used.
* In accordance with the temperature set using the temperature control switch, the air conditioning amplifier determines the outlet temperature based on the input signals from various sensors. In addition, corrections are made in accordance with the signals from the water temperature sensor to control the outlet air temperature.
* This system controls the blower motor in accordance with the airflow volume determined by the air conditioning amplifier based on the input signals from various sensors.
* This system automatically changes the outlets in accordance with the outlet mode ratio that is determined by the air conditioning amplifier based on the input signals from various sensors.
* The A/C amplifier calculates the target speed of the compressor based on the target evaporator temperature (which is calculated by the room temperature sensor, ambient temperature. sensor, and the solar sensor) and the actual evaporator temperature that is detected by the evaporator temperature sensor in order to control the compressor speed.
* The A/C amplifier calculates the target evaporator temperature, which includes corrections based on the room temperature sensor, ambient temperature. sensor, the solar sensor, and evaporator temperature sensor. Accordingly, the A/C amplifier controls the compressor speed to an extent that would not inhibit the proper cooling performance or defogging performance.
* Based on the signals from the ambient temperature sensor, this system calculates the outside temperature and indicates it in the multi-information display.
* The left/right independent temperature control and neural network control make air conditioner control available to suit the persons in the driver seat and in the passenger seat.
* This system turns the rear defogger and outside rear mirror heaters on for 15 minutes when the rear defogger switch is pressed and turns them off if the switch is pressed while they are operating.
* When the blower motor is ON and the engine has been stopped by the THS II system control, the A/C amplifier turns ON the electric water pump in accordance with the judgment of the air mix damper opening.
* This system checks the sensors in accordance with the operation of the air conditioner switches.
* The air conditioning amplifier has the function of controlling the indicator lighting.
* When a high load is applied to the EPS system, the EPS ECU will send a signal to the air conditioning amplifier. After receiving the signal, the air conditioning amplifier may turn off the rear defogger, front deicer, and seat heaters.
2. MODE POSITION AND DAMPER OPERATION
3. AIR OUTLET AND AIRFLOW VOLUME
HINT
* The size of the circle o indicates the proportion of airflow volume.
* -: Not applicable
HINT
* -: Not applicable
* The size of the circle o indicates the proportion of airflow volume.
4. Air Conditioning Control Assembly
(a) For both the front and rear manual and automatic air conditioning, the blower motor speed is steplessly adjustable. Pulse type control is used.
(b) The multi-information display is used as the automatic air conditioning display.
5. Air Conditioning Unit
(a) Front Air Conditioning Unit
(1) The front air conditioning unit consists of the evaporator, heater core, servo motors, evaporator temperature sensor, and blower motor.
* The evaporator and heater core are mounted transversely.
* Bus type communication is used between the servo motors and the air conditioning amplifier.
(b) Rear Air Conditioning Unit
(1) The rear air conditioning unit consists of the evaporator, heater core, air mix control servo motor, mode control servo motor, evaporator temperature sensor, and rear blower motor.
* The evaporator and heater core are arranged horizontally.
* The air outlet control servo motor operates the laminate sliding type mode control door, and the air mix control servo motor controls the full air mix type air mix doors.
* Bus type communication is used between the servo motors and the air conditioning amplifier.
(c) Evaporator
(1) For the evaporator, placing the tanks at the top and the bottom and adopting a micropore tube construction have realized the following effects:
* The heat exchange efficiency is improved.
* The temperature distribution is made more uniform.
* The evaporator is made thinner.
(d) Evaporator Temperature Sensor
(1) The evaporator temperature sensors (No. 1 cooler thermistor for the front air conditioning unit and the rear air conditioning harness for the rear air conditioning unit) each detect the temperature of the cool air immediately past the evaporator based on changes in the resistance of the built-in thermistor. The signal is used by the air conditioning amplifier.
(e) Heater Core
(1) A compact, lightweight, and highly efficient SFA (Straight Flow Aluminum)-II type heater core is used for the front and rear air conditioning units.
(f) Blower Motor
(1) The front blower motor has a built-in blower controller, and the motor speed is controlled by the air conditioning amplifier using duty control.
(2) The rear blower motor speed is controlled by the air conditioning amplifier via a blower motor controller using duty control.
(g) Air Conditioning Harness
(1) The BUS connectors (in the air conditioning harness) have built-in driver ICs that communicate with each servo motor, actuate the servo motor, and have a position detection function. This enables bus communication for the servo motor wire harness, lightweight construction and a reduced number of wires.
(h) Servo Motor
(1) Pulse pattern type servo motors are used. Each servo motor assembly consists of a printed circuit board and a servo motor. The printed circuit board has three contact points, and can transmit two signals (either ON or OFF) using the differing pulse phases. The BUS connector can detect the damper position and movement direction with this signal.
6. Condenser
(a) The condenser consists of two cooling portions: a condensing portion and a super-cooling portion. The condenser also has an integrated gas-liquid separator (modulator). This condenser uses the sub-cool cycle, offering 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 further in the super-cooling portion. Thus, the refrigerant is sent to the evaporator in an almost completely liquefied state.
* The desiccant and filter at the bottom of the modulator remove moisture and debris from the refrigerant.
(b) Service Tip
(1) The point at which the air bubbles disappear in the refrigerant of the sub-cool cycle is lower than the proper amount of refrigerant with which the system must be filled. Therefore, if the system is recharged with refrigerant based on the point at which the air bubbles disappear, the amount of refrigerant would be insufficient. As a result, the cooling performance of the system would be affected. If the system is overcharged with refrigerant, this will also lead to reduced performance. For the proper method of verifying the amount of the refrigerant and for instructions on how to recharge the system with refrigerant.
7. Compressor with Motor Assembly
(a) General
* The compressor with motor assembly is an ES27 motor driven compressor. The basic construction and operation of this compressor are the same as an ordinary scroll compressor, except that it is driven by an electric motor.
* The air conditioning inverter is integrated with the compressor.
* The air conditioning inverter (compressor with motor assembly) is supplied with power from the HV battery at a nominal voltage of DC 288V.
* The electric motor is actuated by 3-phase alternating current (288 V) supplied by the air conditioning inverter. As a result, the air conditioning system is actuated without depending on the operation of the engine, thus realizing a comfortable air conditioning system and low fuel consumption.
* Due to the use of an electric motor to drive the compressor with motor assembly, the compressor speed can be controlled at the required speed calculated by the air conditioning amplifier. Thus, the cooling and dehumidification performance and power consumption are optimized.
* Low-moisture permeation hoses are used for the suction and discharge hoses at the compressor in order to minimize the entry of moisture into the refrigeration cycle.
* The compressor motor uses high-voltage alternating current. If a short or open circuit occurs in the compressor, the hybrid vehicle control ECU will shut off the air conditioning inverter circuit in order to stop the power supply to the compressor motor.
NOTICE:
In order to ensure the proper insulation of the internal high-voltage portion of the compressor and the compressor housing, compressor oil (ND11) with a high level of insulation performance is used. Therefore, never use compressor oil other than the ND11 type compressor oil or a compressor oil that does not have equivalent lubrication and electrical insulation properties.
(b) Construction
* The compressor with motor assembly consists of a spirally wound fixed scroll and variable scroll that form a pair, a brushless motor, an oil separator, a motor shaft and air conditioning inverter.
* The fixed scroll is integrated with the housing. Because the rotation of the shaft causes the variable scroll to revolve while maintaining the same posture, the volume of the space that is partitioned by both scrolls varies to perform the suction, compression, and the discharge of the refrigerant gas.
* Locating the suction port directly above the scrolls enables direct suction, thus realizing improved suction efficiency.
* Containing a built-in oil separator, this compressor is able to separate the compressor oil that is intermixed with the refrigerant and circulates in the refrigeration cycle, reducing the amount of oil that circulates.
* The air conditioning inverter converts the HV battery nominal voltage of DC 288V into AC 288V that is used to operate the compressor.
8. Room Temperature Sensor and Humidity Sensor
(a) The availability of the room temperature sensor and room temperature sensor with built in humidity sensor is as follows.
:
(b) X: Standard, -: Not Equipped
(c) The room temperature sensors detect the room temperature based on changes in the resistance of the built-in thermistor. The signals are used by the air conditioning amplifier.
(d) If equipped with automatic air conditioning, a humidity sensor function is added to the room temperature sensor for the front. By enabling the detection of humidity in the vehicle interior, this function optimizes the amount of dehumidification effort during the operation of the air conditioning system. As a result, the power consumption of the compressor has been reduced and a comfortable level of humidity has been realized in the vehicle interior.
(e) The humidity-sensing resistance film that is built into the humidity sensor absorbs and releases the humidity in the vehicle interior. During the absorption and releasing processes, the humidity-sensing resistance film expands (during the absorption of humidity) and contracts (during drying). The clearance between the carbon particles in the humidity-sensing resistance film expands and contracts during absorption and drying, thus changing the resistance between the electrodes. The air conditioning amplifier determines the humidity in the vehicle interior through the changes in the output voltage of the humidity sensor that are caused by the resistance between the electrodes.
9. Ambient Temperature Sensor
(a) The ambient temperature sensor detects the ambient temperature based on changes in the resistance of its built-in thermistor. This signal is used by the air conditioning amplifier.
10. Heater Water Pump
(a) A heater water pump is used to circulate coolant for the heater core. This provides stable heater performance even if the engine is stopped due to THS-II control.
(b) A pump with low resistance to water flow is used.
11. Solar Sensor
(a) The solar sensor* consists of a photo diode, two amplifier circuits for the solar sensor, and a frequency converter circuit for the light control sensor.
(b) The solar 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 its LH and RH sides (2 directions) and outputs these sunlight strength signals to the air conditioning amplifier.
12. Neural Network Control
(a) In conventional automatic air conditioning systems without neural network control, the air conditioning 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 be felt comfortably warm in a cold climate, or extremely uncomfortable in a hot climate. Therefore, as a technique for performing 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. The air conditioning amplifier can then perform control to provide enhanced air conditioning comfort.
(b) 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 ambient 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 controls the servo motors and blower motor in accordance with the control volumes that have been calculated by the neural network control.
13. Compressor Control (Compressor Speed Control)
(a) The air conditioning amplifier calculates the target compressor speed based on the target evaporator temperature (calculated using the room temperature sensor, humidity sensor*, ambient temperature sensor, and solar sensor*) and the actual evaporator temperature detected by the evaporator temperature sensor. Then, the air conditioning amplifier transmits the target compressor speed to the hybrid vehicle control ECU. The hybrid vehicle control ECU controls the air conditioning inverter based on the target speed data. This control is performed in order make the compressor operate at a speed that suits the operating conditions of the air conditioning system.
(b) The air conditioning amplifier calculates the target evaporator temperature, which includes corrections based on the vehicle interior humidity (obtained from the humidity sensor)* and the windshield glass inner surface humidity (calculated using the humidity sensor*, solar sensor*, room temperature sensor, mode damper position, and wiper operation condition). Accordingly, the air conditioning amplifier controls the compressor speed to an extent that does not inhibit the proper cooling performance or defogging performance. As a result, comfort and low fuel consumption can be realized.