vehicle cooling system part 1 

   I will introduce the function of the engine radiator in the vehicle and the cooling topology for a specific model, so that everyone can have a deeper understanding of the radiator technically, so that when customizing the production of the radiator, you can know which is the key.

   The following are the chapters introduced.

1. Basic information of the vehicle

2. Basic information of engine and electric motor

3. Cooling topology

4. Cooling system

5. Air conditioning system

6. Air intake system

7. Exhaust system

8. Thermal insulation to components

Vehicle name		Honda 2019 CRV Hybrid 2.0L
Vehicle size	Length, width and height [mm]	4585*1855*1679
	Wheelbase [mm]	2660
Body style		5-door 5-seater SUV
weight		1659kg
Energy type		Hybrid
Engine		2.0L, horsepower 146PS, L4
Gearbox		E-CVT
Electric motor		Front single motor
Power Battery		Li-Ion 1.411Kwh

Vehicle name		Honda 2019 CRV Hybrid 2.0L
Other configuration	Engine start-stop technology	NO
	Skylight type	Panoramic skylight
	Active closed air intake grille	With upper active grille, without lower active grille
	Battery preheating	NO
	AC System	Automatic air conditioning/with rear seat air outlet/with temperature zone control
	Sunshade	Sunshade with rear side window/sunshade without rear windshield

	Vehicle name			Honda 2019 CRV Hybrid 2.0L
	Engine information	Engine Installation		Horizontal
		Boost		NO
		Engine Capacity		2.0L
		Engine configuration		in-line engine
		Number of cylinders		4
		Bore		81mm
		Stroke		96.7mm
		Compression Ratio		13
		Max Horsepower (PS)		146
		Max Power (KW)		107
		Max output (rpm)		6200
		Max. torque (Nm)		175
		Max. torque (rpm)		4000
		Cylinder block/cylinder head material		Aluminum alloy
Vehicle name					Honda 2019 CRV Hybrid 2.0L
Electric motor			Total motor power		135KW
			Total motor torque		315Nm

Cooling system topology:

Engine cooling (red circuit): At the beginning of the engine start, if the engine water temperature is low, the thermostat will be closed, and the engine cooling circuit takes a small cycle, water pump B to engine block to cylinder header to heater to water pumpB , the engine’s heat makes the water warm up. When the water temperature is higher than a certain value (such as 90℃), the engine cooling takes a large cycle, RAD to Thermostat to water pumpA to engine block to cylinder head to RAD. We can see that the EGR cooler is also on the engine cooling circuit. At the same time, the circuit is equipped with an expansion tank. For the specific functions and functions of the expansion tank, please refer to this blog.

PCU cooling circuit (green circuit): Because hybrid models have electric motor, motor controller and IPS, an additional radiator is needed to cool them. You may ask, why is the auxiliary radiator not connected in series with the engine cooling circuit, but a radiator is required independently? The reason is that the inlet temperature of the coolant required for motor and motor controller is generally lower than 60°C, which is much lower than the temperature of the engine coolant, and the temperature of the engine water outlet is generally higher than 90°C, so the same radiator cannot be shared. Due to this reason, the auxiliary radiator is generally arranged in front of the engine radiator。Auxiliary radiator to expansion tank to water pumpC to PCU(including motor, motor controller and IPS) to  Auxiliary radiator.

Air-conditioning circuit (yellow circuit): The air-conditioning circuit is mainly used for air-conditioning and cooling of the passenger compartment. Note that the air-conditioning circuit takes the refrigerant R134a or R1234yf not Ethylene glycol coolant, and the Condensing temperature for condenser is generally 50-60°C, so the condenser also needs to be arranged in front of the engine radiator.

CDS to Expansion valve to Evaporator to compressor to CDS.

The figure above shows the gearbox cooling circuit and the power battery cooling circuit.

gearbox cooling circuit：Oil cooler to oil pump to E-CVT to oil cooler，oil cooler for gearbox.

Power battery cooling circuit：Cabin to blower to power battery to cabin，air cooling for battery. General power battery cooling has three cooling methods: air cooling, liquid cooling and direct refrigerant cooling.

The following table shows the size of various heat exchangers of CRV models for your reference.

Heat exchanger	Size(mm)
Condenser	705*346*11
Auxiliary radiator	550*125*21
Engine radiator	745*420*16
Oil cooler	200*288*32.5
Engine cooling fan	Single fan

Notes:

1. Electronic water pump A is used for engine cooling;

2. The heating system adopts electronic water pump B;

3. The EGR cooler is connected in series in the high temperature circuit;

4. The expansion tank does not participate in the circulation of the coolant;

5. E-CVT adopts oil cooling, PCU adopts water cooling, separate separately;

6. The power battery is air-cooled.