Hybrid and Alternative Fuel Vehicles By James D
Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
OBJECTIVES After studying Chapter 9, the reader should be able to: 1. Explain the operation of the ICE cooling system. 2. Explain the operation of the motor/electronics cooling system in a hybrid electric vehicle. 3. Explain the operation of a coolant heat storage system. 4. Describe the function of a vehicle’s heating and A/C system. 5. Discuss the operation and unique service procedures for electric-drive A/C compressors. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
HYBRID ICE COOLING AND CABIN HEATING The purpose of the ICE (engine) cooling system is to bring the ICE up to an optimum temperature as quickly as possible and then to maintain that temperature under all operating conditions. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
Coolant temperature for the ICE cooling system is maintained in a narrow range for a number of reasons: 1. The ICE is able to run at its highest efficiency and lowest emissions when it is at operating temperature of 195 to 215°F (90 to 101 C°). 2. Vehicle driveabilty (engine performance) is enhanced. 3. Engines that run cold tend to wear out much faster. 4. The ICE cooling system is also responsible for providing heat to the vehicle’s passenger compartment. 5. Overheating the ICE can lead to reduced efficiency and possible catastrophic failure of the mechanical components. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
Temperatures in the ICE combustion chamber can exceed 6000°F (3300°C). A portion of this heat energy (approximately one-third) is converted into mechanical energy to move the vehicle, but the vast majority is released as waste heat. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
Basic Operation All automotive ICEs are liquid-cooled. This means that the cooling systems are sealed and liquid coolant is circulated through the water jacket (internal passages) by a water pump to absorb excess heat. The heated coolant is sent through a radiator to dissipate the heat and lower its temperature. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
A thermostat is used to confine coolant flow to the ICE water jacket and heater core until the coolant reaches approximately 195°F (91°C). Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
Coolant that does not flow through thermostat will enter an internal bypass tube and return to the water pump inlet. If the coolant temperature continues to rise past this point, the electric fan will turn on and circulate air over the radiator to increase the amount of heat that can be dissipated. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
Cooling System Components Water Jackets. The hottest areas of the ICE are around the combustion chambers, so coolant is directed into these areas and the absorbed heat is transported to cooler areas of the ICE as well as the radiator. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
Coolant. Water is mixed 50/50 with ethylene-glycol-based antifreeze. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
There a number of different kinds of automotive antifreeze. The green antifreeze that was used for decades across vehicle lines was based on inorganic additive technology (IAT), which often used silicates as its primary corrosion inhibitor. Silicates are abrasive in nature and can cause damage to water pump seals and cooling system components if they drop out of solution. Deposits formed in the water jacket by silicate dropout can also cause hot spots in the ICE cooling system as they inhibit coolant flow in those areas. Organic acid technology (OAT) and hybrid organic acid technology (HOAT) coolants. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
Most OAT and HOAT coolants are dyed a color other than green. The most recognizable OAT-based coolant is DEX-COOL, which is orange in color and has been used in all General Motors vehicles since 1996. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
Different colors (Ford is yellow; Chrysler is a pink/orange). Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
and HOAT are both extended-life coolants, meaning that they have a typical service life of five years and anywhere from 100, 000 to 150, 000 miles. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
Water Pump. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
The ICE water pump is a non-positive displacement design, meaning that the impeller can turn without any coolant being pumped if a blockage exists in the system. Coolant always enters at the center of the impeller and is “thrown” outward as the water pump is turned. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
Most hybrid electric vehicles utilize an electrically driven helper pump that continues to circulate coolant when the ICE enters auto stop. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
Thermostat. When thermostat opens, coolant is allowed to enter the radiator and dissipate excess heat to the outside air. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
Pressure Cap. The purpose of the pressure cap (also known as radiator cap) is to maintain pressure in the cooling system in order to maximize cooling efficiency. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
For every 1 psi that the system pressure is raised, the boiling point of the coolant rises 3°F. If cooling system pressure rises above the pressure cap’s rating, the pressure valve in the cap opens and allows some coolant to flow to the coolant recovery reservoir. A vacuum valve in the pressure cap opens and allows coolant to flow from the coolant recovery reservoir back into the cooling system. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
Coolant Recovery Reservoir. When the pressure cap allows coolant to exit the system, the coolant flows through the hose and increases the level in the reservoir. As the temperature in the cooling system decreases, coolant is allowed to flow from the reservoir back into the cooling system. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
Surge Tank. Some vehicles use a surge tank instead of a coolant recovery reservoir. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
Heat Exchanger. A liquid-to-air heat exchanger is utilized that dissipates the heat from the coolant to the air passing through it. Coolant flows into the inlet tank and is then directed into dozens of thin tubes that form the core of the heat exchanger. These tubes are designed with cooling fins located between them so that maximum surface area is available to dissipate heat to the outside air. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
Radiators are most often constructed with plastic tanks attached to an aluminum core. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
There are two major designs of radiators: downflow and crossflow. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
Crossflow radiators are made to be installed in vehicles with lower hood lines and have horizontal tubes with tanks attached to each end. If the vehicle is equipped with an automatic transmission, there will often be a transmission oil cooler installed in the outlet tank of the radiator. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
Cooling Fans. If the vehicle is moving slowly or is stopped, the ICE could overheat unless some additional means of moving air across the radiator is provided. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
A thermostatic fan clutch that is designed to slip when cold. The fan itself is still belt-driven, but the fan only engages when it is needed and otherwise reduces the noise and energy consumption associated with a fixed mechanical fan. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
An electric fan can be mounted either behind or in front of the vehicle radiator The fan can be turned on and off through the use of a thermoelectric switch mounted on the radiator tank, or by electronic means using the power train control module (PCM). Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
Using a multiple-speed fan motor, or controlling the current to the motor using pulse-width modulation (PWM). Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
Hoses. Radiator hoses have an inner lining made from synthetic rubber. A number of textile plies are woven over top of the inner lining as reinforcements, and then an outer layer of rubber is placed on top of the reinforcing plies. The rubber outer layer must be capable of resisting damage due to leaking oil or extreme temperatures. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
Coolant Heat Storage System (2004+ Prius) Toyota uses this system in the second- generation Prius (2004 and newer). Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
The coolant heat storage tank is built very similar to a Thermos® bottle. Approximately 3 liters of coolant is stored inside the inner casing, and the coolant can be kept warm for up to three days. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
The water valve is responsible for directing the coolant flow between the coolant storage tank, the ICE, and the vehicle’s heater core. The water valve is controlled by the ECM and consists of an electric motor, drive gears, a rotary valve, and a valve position sensor. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
The storage tank pump is used to move coolant through the heat storage tank at times when the ICE is shut off. This pump is located on the side of the coolant heat storage tank and is plumbed in series with the tank inlet. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
Modes of Operation. 1. Preheat 2. Engine warm-up 3. Storage during driving 4. Storage during ignition off The preheat mode is enabled prior to the starting of the ICE. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
The ICE is started and the coolant heat storage system enters the engine warm-up mode. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
The water valve is moved to allow coolant from the ICE to flow into both the heater core and the coolant heat storage tank. This process replaces the cold coolant in the storage tank with heated coolant, and is known as storage operation (driving). Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
If the ICE is shut off while the coolant heat storage tank is being filled, the water valve stays in the storage position and the storage tank pump is turned on to finish filling the tank. This phase is known as storage operation (ignition off). Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
Cabin Heating Systems Some of the waste heat absorbed by the ICE cooling system can also be dissipated by the heater core in the passenger compartment heating system. The heater core is located in the passenger compartment, inside the plenum chamber (air distribution box) for the vehicle’s heater and air-conditioning components. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
Air entering the plenum chamber must first pass through the A/C evaporator core, and then is directed either through or around the heater core by the blend door (air mix valve). Once the air leaves the heater core, it is blended with any air that has bypassed it and then is sent to its destination through a series of mode valves. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
HEV Heating Systems. When the ICE is first started, it takes some time for the coolant to reach sufficient temperature for heat to be sent to the passenger compartment. The ICE coolant temperature is more difficult to maintain when the ICE enters into idle-stop or the vehicle is operating in electric-only mode. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
One approach is to use PTC heaters built into the heater core itself. PTC heaters convert electrical energy into heat, and this is used to boost heat to the passenger compartment. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
PTC heaters can also be located in the air ducts in the form of a honeycombshaped grid. Air that is leaving the plenum chamber passes through these heaters before it enters the passenger compartment. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
HYBRID ELECTRICAL SYSTEM COOLING Electronic components operate more efficiently as their temperature decreases, but can suffer permanent damage if they overheat. All hybrid electric vehicles have cooling systems for their motors and motor controls, and some utilize air-cooling to remove excess heat from these components. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
System Construction The liquid cooling systems used for the motors and motor controls on hybrid electric vehicles have much in common with conventional ICE cooling systems. Some designs may have the radiator incorporated into the ICE radiator, or it may be separate. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
The coolant is circulated through the various components in the system, which could include the following: Electric motor-generator(s) DC-DC converter Inverter Transmission oil cooler Other high-load control modules Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
Coolant hoses connect to fittings on the transmission case, and these direct coolant in and out of each of the motor-generator assemblies. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
The GM hybrid pickup utilizes a starter-generator control module (SGCM) that plays a similar role to the inverter in other hybrid control systems. This module has its own liquid cooling system, which includes a heat exchanger, electric water pump, a radiator, and a cooling fan. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
The Ford Escape Hybrid has a motor electronics (M/E) cooling system that is similar to the inverter cooling system used in the Toyota Prius. The power electronics for the hybrid drive system are located on top of the transaxle, and the coolant circulated through this unit also removes heat from the transmission fluid used for cooling the electric motors. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
HYBRID AIR-CONDITIONING SYSTEMS Heat energy must be absorbed by a refrigerant (such as R-134 a) in order for it to change from a liquid to a gas, and this property can be utilized effectively in a vehicle’s evaporator to absorb heat from inside the passenger compartment. The gaseous refrigerant is then compressed and sent to the condenser (located ahead of the radiator), where the absorbed heat is then dissipated outside the vehicle. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
In order for the change of state to take place, the liquid propane must absorb heat energy. The propane will absorb heat through the steel walls of the cylinder, creating a chill effect in which condensation and frost form on the outside of the cylinder. The steel cylinder is playing the same role as the evaporator in an air conditioning system. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
Changing the refrigerant from a gas to a liquid requires that it be compressed (by the compressor) and cooled (by the condenser) to remove the excess heat energy. The liquid refrigerant is then directed through a restriction (thermostatic expansion valve or orifice tube) in the line, where a pressure drop takes place. The cycle then starts over again as the refrigerant moves out of the evaporator and into the compressor inlet. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
The belt drive often uses an electrically operated clutch, which allows the compressor pulley to disconnect from the compressor and stop refrigerant flow in the system while the ICE continues to run. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
The fresh air coming into the vehicle is sometimes sent through a cabin filter first, in order to remove particulate matter and prevent clogging of the vehicle’s evaporator. All the incoming air must pass through the A/C evaporator core after leaving the blower motor. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
When in the heat mode, the A/C compressor is turned off and the evaporator operates at ambient temperature. The heater core is part of the ICE cooling system, and hot coolant is circulated through it by the water pump. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
Components Compressors. the most commonly used compressor design in hybrid electric vehicles is the scroll compressor. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
The scroll compressor is a highly efficient and durable design, with very good noise, vibration, and harshness (NVH) characteristics. The movable scroll does not rotate. Instead, it orbits inside the stationary scroll. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
Compressor Drives. Hybrid electric vehicle A/C systems are very similar to those found on vehicles with conventional power trains. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
In order to allow idle stop to take place when the A/C system is on, compressor drives on some HEVs are modified to include an electric motor that is powered by the hybrid high-voltage battery. The electric motor can be “piggybacked” with the conventional belt drive. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
The compressor may be electric-drive only. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
Compressor Oil. Most vehicle manufacturers specify polyalkylene glycol (PAG) oil for R-134 a systems. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
Many different kinds of PAG oil are available, so it is important to select the correct type when servicing a vehicle’s air-conditioning system. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
Some late-model hybrid electric vehicles use high-voltage electric drives for their A/C compressors. This may be in conjunction with a belt drive, or the compressor may be electric-drive only. These compressors often require a nonconductive oil that insulates the high-voltage motor and prevents electrical failures. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
Condensers. The condenser is part of the high-pressure section of the air-conditioning system, and is another type of heat exchanger. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
The condenser can be built with one long cooling tube following a serpentine path. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
Surface area of the condenser is increased by the addition of thin fin material between the tubes, as well as partitioning in the tubes themselves. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
The condenser is typically installed ahead of the vehicle’s radiator and has airflow sent though it either through vehicle movement or by the cooling fan. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
Expansion Devices. In order for the refrigerant to absorb heat in the evaporator, it must go through a change of state in which it changes from a liquid to a gas. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
There are two primary types of expansion devices used in automotive airconditioning systems: thermostatic expansion valve (TXV) and the orifice tube (OT). Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
An expansion valve (TXV) system uses a receiver-drier in the high-pressure side, whereas an orifice tube system has an accumulator on the low-pressure side between the evaporator and the compressor suction port. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
A thermostatic expansion valve uses a sensing bulb on the evaporator outlet to regulate refrigerant flow according to evaporator temperature. The sensing bulb is attached to the expansion valve diaphragm chamber by a capillary tube. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
There a number of different orifice tube designs, but the most common one is the fixed orifice tube. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
Multiple Zones. The auxiliary zone is connected in parallel to the primary zone, so it forms a second path for refrigerant to flow in the system. Zone valves can be used to control refrigerant flow for each zone in the system. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
Ford Escape Hybrid, an orifice-tube system is used for the cooling of the passenger compartment (passenger zone), while a thermostatic expansion valve is used in the auxiliary A/C unit used to cool the high-voltage battery (battery zone). Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
Evaporators. The evaporator is located after the expansion device on the low-pressure side of the A/C refrigerant system. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
Many vehicles use cabin filters to prevent airborne particulate matter from entering the vehicle’s air distribution system. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
The Ford Escape Hybrid also uses a cabin filter in the auxiliary climate control (battery zone) system to prevent particulate matter from collecting on the traction battery cooling passages. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
Refrigerant Lines and Connections. Refrigerant lines are tubes or hoses that are used to connect the various components of the A/C refrigerant system. Two major types of lines are used: rigid and flexible. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
Flexible hoses used with R-134 a systems are called barrier hoses. The molecules of R-134 a refrigerant are smaller than those of R-12; therefore, the lining of the hose must be made of a special nylon material to prevent leakage. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
R-134 a systems use quick-disconnect fittings, with the low-side fitting made smaller than the high-side fitting to prevent the improper connection of equipment. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
SUMMARY 1. The purpose of the ICE cooling system is to bring the ICE up to optimum temperature as quickly as possible and to maintain that temperature under all operating conditions. 2. A thermostat is used to maintain the optimum coolant temperature in the ICE cooling system. 3. OAT (organic acid technology) and HOAT (hybrid organic acid technology) are two types of coolant being used in newer vehicles. 4. Electric helper pumps are used to circulate coolant in the heating system when the ICE enters idle stop mode. 5. The coolant heat storage system is used to limit vehicle emissions during cold starts. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
SUMMARY 6. The electric motors and motor electronics on a hybrid electric vehicle will often have their own liquid-cooling system. 7. Most HEVs use scroll compressors in their air-conditioning systems. 8. Some HEVs use A/C compressors with electric drive or a combination belt-electric drive mechanism. 9. Nonconductive refrigeration oil is used in A/C compressors with electric drives. 10. PTC heaters are used to provide supplemental heat in HEV heating systems. Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
REVIEW QUESTIONS 1. What is the operation of the coolant heat storage system? 2. What is the difference between IAT and OAT/HOAT coolants? 3. Why is the motor-electronics cooling system separate from that of the ICE? 4. What is the function of a PTC heater, and why is it used in an HEV heating system? Hybrid and Alternative Fuel Vehicles By James D Halderman and Tony Martin © 2009 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458
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