Heating Circuit, Basic Function - GF83.20-P-1002A
Model all (CAR)
Heating circuit on vehicles with combustion engine (shown schematically)
Heating circuit for electric vehicles
Overview
This document contains information on:
- General
- Function requirement
- Function
General
The heating circuit is used to heat the vehicle interior at low outside temperatures. It is connected to the coolant circuit and uses the thermal energy from the coolant.
Function requirement
- Engine running (exception: Residual heat utilization).
Function
Vehicles with internal combustion engine:
The following component parts are integrated into the heating circuit:
- Coolant circulation pump
- Heating system heat exchanger
The coolant pump pumps coolant through the engine. There, the coolant absorbs the engine's heat and becomes heated. Then some of the heated coolant flows through the heater core, where the heat is dissipated to the blowby air.
The circulation pump pumps the coolant when the engine is off (e.g. for residual heat utilization), and it supports the coolant pump at low engine speeds. It is actuated by the climate control control system to match the given load.
Electric vehicles:
The following component parts are integrated into the heating circuit:
- Heater circuit coolant circulation pump
- Condenser
- Heating circuit shutoff valve
- High-voltage PTC heater
- Heating system heat exchanger
In the heating circuit, the heating circuit coolant circulation pump delivers the coolant through the condenser, the high-voltage PTC heater and the heater core. At the condenser, heat from the refrigerant circuit is coupled into the heating circuit.
At battery temperatures > 15°C, heat is transferred from the low-temperature circuit of the high-voltage battery via the refrigerant circuit into the heating circuit. If the heat is not sufficient, the high-voltage PTC heater in the heating circuit is patched in.
At battery temperatures < 15°C and ambient temperatures between 5°C and -5°C, the heat is through the high-voltage PTC heater in the heating circuit.
At battery temperatures < 15°C and ambient temperatures < -5°C, the high-voltage PTC heater in the heating circuit heats up the coolant. If the heat is not sufficient, heat is transferred from the low-temperature circuit of the high-voltage battery via the refrigerant circuit into the heating circuit. For this, the high-voltage PTC heater is actuated in the low-temperature circuit of the high-voltage battery.
At battery temperatures < 15°C and ambient temperatures > 5°C, the condensation heat of the evaporator and the waste heat of the compressor is transferred from the refrigerant circuit into the heating circuit. If this heat is not sufficient, the high-voltage PTC heater in the heating circuit is patched in.
If the heat of the condenser cannot be dissipated via the heating circuit (because the vehicle interior temperature is already high enough and should not be heated), the heating circuit shutoff valve closes the circuit to the high-voltage PTC heater and opens it to the cooler in the high-voltage battery low-temperature circuit. From the cooler, the coolant is redirected back into the heating circuit and to the condenser.
| Further basic function | |||
| Climate control, basic function | GF83.00-P-9901A |