Heating with the seatbelt saves energy

ZF Lifetec has further developed its heated seat belt. A new algorithm and an optional electronic control unit (ECU) ensure that the Heat Belt 2.0 quickly adjusts its heat output. The low energy consumption of the Heat Belt 2.0 has a positive effect on the range of battery electric vehicles - according to ZF, this can be increased by up to six percent, particularly during the warm-up phase of the vehicle interior.

The Heat Belt 2.0 complements existing surface heating systems such as seat or steering wheel heating and ensures a pleasant temperature in the upper body area - without any draughts or fan noise. Thanks to the low mass of the belt, the feeling of warmth sets in after about a minute. After warming up, an automatic adjustment of the heat output ensures a lasting pleasant feeling of warmth. Despite the additional woven-in technology, the belt itself is only 1.3 millimetres thick. It contains four fine heating wires of the required length to cover the occupant's pelvis and chest area. The maximum heat output is 60 watts, with an average of around 20 watts. Starting from -5 degrees, the heat belt reaches a temperature of 40 degrees in less than two minutes.

At the heart of the system is a patent-pending algorithm. It calculates the optimum heating output, taking into account the body core temperature (approx. 37 degrees) and skin temperature (32 to 34 degrees), the outside and inside temperature as well as the solar radiation, which is recorded by vehicle sensors. The data from the automatic air conditioning system (HVAC) is also included in the temperature calculation - unlike the previous version, a temperature sensor in the seat belt is no longer required. A major advantage for vehicle occupants: The heat output is regulated automatically, so no manual readjustment is necessary.

Using the Heat Belt 2.0 together with other heating systems close to the body enables new heat management concepts that reduce energy requirements in cold seasons - especially in battery electric vehicles. The interior temperature in the vehicle can be lowered by around three degrees through the targeted supply of heat to the body. The energy saving results from lower heat loss to the environment and a reduced energy requirement for heating the interior, while maintaining the same level of comfort for the occupants.

In a short-distance scenario, for example when shopping, the warm-up phase dominates and requires the maximum heating output of the air conditioning system in order to reach a comfortable cabin temperature within ten to 20 minutes. With heating close to the body, comfort for the occupants is achieved more quickly, meaning that the heating output of the air conditioning system can be reduced by up to 1000 W. This has a positive effect on the range of electric vehicles. The heating belt also enables the use of smaller air conditioning systems. Even on longer journeys of more than an hour with a heated interior, a saving of around 200 W can be achieved, as the air conditioning system only has to compensate for the heat loss to the environment.

The Heat Belt 2.0 can be seamlessly integrated into a wide range of vehicle models, from small cars to luxury models. In vehicles with a proximity sensor, the system can optionally be set so that the preheating function is activated as soon as the user approaches the vehicle. The pleasant warmth also motivates people in the vehicle to wear their seat belts correctly and to refrain from wearing thick winter clothing. This contributes to greater safety. (aum)