P83.40-5546-79
Heating circuit on vehicles with combustion engine (shown schematically) |
1 | Coolant expansion reservoir | 10 | Transmission oil cooler circulation pump | |
2 | Stationary heater | 11 | Turbocharger | |
3 | Engine oil heat exchanger | 12 | Coolant pump | |
4 | Switchover valve | 13 | Radiator | |
5 | Circulation pump | 14 | Check valve | |
6 | Heating system heat exchanger | a | High temperature cooling circuit | |
7 | Coolant thermostat | b | Filling line | |
8 | Motor | c | Ventilation of high-temperature cooling circuit | |
9 | Transmission oil heat exchanger |
Heating circuit for electric vehicles |
1 | Condenser, water-cooled |
2 | Heating circuit shutoff valve |
3 | High-voltage PTC heater |
4 | Heating system heat exchanger |
5 | Heater circuit coolant circulation pump |
A | Transition to refrigerant circuit |
B | Transition from refrigerant circuit |
C | Transition to low-temperature circuit for high-voltage battery |
D | Transition from low-temperature circuit for high-voltage battery |
P83.40-A019-82
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.