More functions, performance and comfort for an at-tractive system cost price: BERU engineers develop the new PTC model series Basic Line.

Automobile manufacturers in the whole world place their trust in the innovative PTC auxiliary heater systems from Beru. The Ludwigsburg-based company meets a large number of require-ments with its three tailor-made product lines.

(Ludwigsburg, August 31, 2005) Modern diesel and gasoline engines have an enormously greater degree of effectiveness due to direct in-jection, and therefore also lose considerably less heat to the cooling water. The consequence: an insufficient thermal yield, above all when the outside temperatures are low. BERU AG has therefore developed, together with its joint venture partner BERU Eichenauer in Kan-del/Palatinate, an innovative PTC auxiliary heater system for the direct heating of the interior air, with which the Ludwigsburg-based company already supplies automobile manufacturers such as Audi, Ford, Hyundai, Kia, Mazda, Seat, Skoda, Volvo and VW for series production. The electronics within the PTC systems is manu-factured on a state of the art, fully automatic SMT (surface mounted technology) line within BERU Electronics GmbH in Bretten.

Three model series for an optimum range of uses

As global market leader in the field of electronically controlled auxiliary heaters, BERU now has, with the newly developed Basic Line, three PTC model series that can be adapted to meet any customer requirements in an optimum manner due to their flexible construction principle:

• Relay Line: BERU PTC auxiliary heater with relay circuit,
• Basic Line: BERU PTC auxiliary heater with analog electronics,
• Comfort Line: BERU PTC auxiliary heater with electronic con-trol unit and microprocessor.

Relay Line: strong thermal yield for a low basic price

PTC systems such as the BERU Relay Line work with relay circuit without electronics. Their advantage is found in the low basic price for the PTC unit. Additionally however, manufacturers of automobiles or air conditioning systems must expect additional costs and restrictions in terms of comfort and performance.

Basic Line: greater functions for an attractive system cost price

The newly developed BERU PTC model series Basic Line with analogue electronics is freely adjustable and cooperates with the vehicle power management system, adapting itself individually to meet its re-quirements. Additional advantage in comparison with the relay solu-tion: component and system cost price are identical. This is why the BERU Basic Line – depending on the design – is an attractively priced alternative to auxiliary heaters without electronics, if one considers the overall costs.

The decisive advantages in the new BERU Basic Line at a glance:

• Plug & play solution. Additional costs for installation, wir-ing, extra signal ports and other system costs are considera-bly lower,
• No additional costs for the relay, its installation, high current and signal wiring, for electric fusing measures, tests and validation,
• No switching noise in the air conditioning duct,
• Slow start of the PTC auxiliary heater due to limited starting current, preventing external variations in the board network,
• Longer service life due to a lack of mechanical wear parts,
• Homogeneous temperature profile for all performance re-quirements across the entire heating surface; no hotspots,
• Ideal adaptation with the power management of modern ve-hicles.

In addition, PTC auxiliary heaters in the new BERU Basic Line have a series of internal diagnosis functions. Among others, these include:

• Temperature monitoring for the printed circuit boards,
• Deactivation in the event of excess or negative voltage,
• Monitoring of temperature, voltage and current on the per-formance semiconductors,
• An inverse poling protection and
• Monitoring of the PTC for short circuits.

Comfort Line: high tech solution for the highest demands

Perfection in terms of function, performance and comfort can also be found in the plug & play Comfort Line of the BERU PTC auxiliary heaters. In this series, a microprocessor controls the heating element that individually and freely adjustably controls the thermal yield to-gether with the semiconductor circuits. The total heater power con-sumption is controlled by periodic activation and deactivation of the individual heating rods, each using one semiconductor circuit. The en-tire heat management was designed by the BERU developers in such a way that constant communication with the vehicle power management consistently prevents overloading the board network.

Freely adjustable power setting, control and diagnosis in the BERU Comfort Line take place using standard bus systems such as CAN, LIN and HSCAN. For example, the microprocessor receives from the air conditioning control unit thermal yield instructions or transmits di-agnosis responses via these interfaces. In turn, these responses can be accessed during servicing using standard diagnosis testers. Any possi-ble error reports are saved by this BERU PTT system along with the matching error number in the error memory management system (EEPROM).

Robust, efficient and tested construction

The heat exchangers in all BERU PTC model series consist of heating rods and superimposed lamellas made of an anti-corrosive aluminum alloy. The heating rods consist of just a few individual components, and the PTC ceramic elements are pressed in a rectangular, aluminum pipe. This ensures optimum contacts and very low thermal and electric transfer resistance over the entire service life.

The ends of the heating rods can be sealed with a compound. This cre-ates a hermetically sealed system, protected against damaging gases, dirt particles and moisture. The BERU auxiliary heaters are standardized systems, developed by the Ludwigsburg-based company in coopera-tion with automobile manufacturers and air conditioning system manu-facturers in such a way that the vast majority of modern air condition-ing systems can be fitted with them. Despite the essential standardiza-tion, the performance of the PTC heaters can be tailor made to meet the individual customer requirements due to their unique constructive principle.