Heating and Air Conditioning: Description and Operation
AIR CONDITIONING: AIR CONDITIONING SYSTEM:
SYSTEM DIAGRAM
SYSTEM DESCRIPTION
1. GENERAL
The air conditioning system has the following features:
- An ES18 type Electric Inverter Compressor is used. This compressor is driven by an alternating current provided by the A/C inverter, which is built into the inverter of the hybrid system.
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.
- A blower motor controller, which regulates the speed of the blower motor by controlling the output voltage in accordance with the duty cycle signal provided by the air conditioning amplifier, is used.
As a result, the power loss associated with the heat generation of the conventional blower linear controller is reduced, thus realizing low fuel consumption.
- A humidity sensor function is added to the room temperature sensor in order to optimize the amount of dehumidification effort during the operation of the air conditioning system.
- A compact, lightweight and highly efficient RS (Revolutionary Slim) evaporator is used.
- A compact, lightweight and highly efficient MF-IV (Multi Flow-IV) condenser is used.
- A compact, lightweight, and highly efficient electrical water pump is used in order to ensure the proper heater performance while the engine is stopped.
- Fuzzy control is used for calculating the required outlet air temperature (TAO: Temperature Air Outlet) and the blower volume in the automatic air conditioning control system. Accordingly, the air conditioning ECU is able to calculate the outlet air temperature, blower volume, air outlet, and compressor speed that is suited to the operating environment. As a result, the comfort level of the occupants is improved.
2. AIR CONDITIONING OPERATION
- The air conditioning is controlled by using the switches that appear on the air conditioning screen display of the multi-display and the switches provided on the steering pad.
- In addition to the air conditioning screen display, the operating conditions of the AUTO, RECIRCULATION, front DEF, and rear DEF switches are indicated by the indicator lights in the combination meter.
3. HEATER CORE AND PTC HEATER
- A compact, lightweight, and highly efficient straight flow (full-path flow) aluminum heater core is used. A PTC (Positive Temperature Coefficient) heater is built into the heater core tube.
- The PTC heater contains electrodes that are interposed with a PTC element, to which current is applied in order to warm the air that passes through the fins.
- The PTC heater is provided in the air duct at the footwell outlet in front of the air conditioning unit. This PTC heater, which is a honeycomb-shaped PTC thermistor, directly warms the air that flows in the duct.
4. COMPRESSOR
- ES18 Electric Inverter Compressor is actuated by a built-in electric motor.
- The electric motor is actuated by the alternating current power (201.6 V) supplied by the A/C inverter, which is integrated in the hybrid system inverter. As a result, the air conditioning control system is actuated without depending on the operation of the engine, thus realizing a comfortable air conditioning system and low fuel consumption.
- The electric inverter compressor controls the compressor speed at the required speed calculated by the air conditioning amplifier. Thus, cooling, dehumidification performance and power consumption are optimized.
- The suction and discharge hoses at the compressor are low-moisture permeation hoses. This minimizes the entry of moisture into the refrigeration cycle.
- The compressor uses high-voltage alternating current. If a short or open circuit occurs in the compressor wiring harness, the hybrid control ECU will cut off the A/C inverter circuit in order to stop the power supply to the compressor.
- The Electric Inverter Compressor consists of a spirally wound fixed scroll and variable scroll that form a pair, a brushless motor, an oil separator, and a motor shaft.
- 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, thus realizing a reduction in the oil circulation rate.
HINT: In order ensure the proper insulation of the internal high-voltage portion of the compressor and the compressor housing, a compressor oil (ND-OIL 11) with a high level of insulation performance is used. Therefore, never use a compressor oil other than the ND-OIL 11 type compressor oil or its equivalent.
5. WATER PUMP
- An electrical water pump is used. This provides a stable heater performance even if the engine is stopped because of a function of the THS-II.
- A new type of electrical water pump is used in which the water flow resistance has been reduced.
6. ROOM TEMPERATURE SENSOR AND HUMIDITY SENSOR
- A humidity sensor function is used by the room temperature sensor. 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.
- 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.
7. BLOWER MOTOR CONTROLLER
The blower motor controller controls the voltage that is output to the blower motor in accordance with the duty cycle signals that are input by the air conditioning amplifier. It is characterized by a smaller amount of heat generation than the blower controller used on the previous model. As a result, the power loss associated with the heat generation of the conventional blower linear controller has been reduced, thus realizing low fuel consumption.
8. AIR CONDITIONING AMPLIFIER
The air conditioning ECU has the following controls.
9. ELECTRIC INVERTER COMPRESSOR CONTROL
- The air conditioning amplifier calculates the target compressor speed based on the target evaporator temperature (calculated from 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 speed to the hybrid control ECU. The hybrid control ECU controls the A/C inverter based on the target speed data in order to control the compressor to a speed that suits the operating condition of the air conditioning system.
- The air conditioning amplifier calculates the target evaporator temperature, which includes corrections based on the vehicle interior humidity (which is obtained from the humidity sensor) and the windshield glass inner surface humidity (which is calculated from 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.
10. MODEL POSITION AND DAMPER OPERATION
Function of main damper
HINT: *1: During 2-way flow control
*2: Early stage of COOL during AUTO
11. AIR OUTLETS AND AIR VOLUME RATIOS
HINT: 1. The circle size (o) indicates the proportion of the airflow volume.
2. The (-) indicates that the air is not blown out.
3. The (*) indicates the early stage of COOL during AUTO.