Latent heat accumulator

The latent heat accumulator (LWS) enables rapid heating of the vehicle interior and engine with the aid of a special heat accumulator and a larger auxiliary water pump.

It starts operation automatically as of ignition lock position 1 and is charged with the cooling water heated by the engine. The valves are activated dependent on the following conditions:

Latent heat accumulator

Operating conditions of the LWS

• Latent heat accumulator switched off
  The latent heat accumulator is switched off if interior heating is not required or the engine temperature is < 45^o C and the LWS temperature is < 30^o C. The changeover valve is open (at zero current) , the shut-off valve is closed (power applied) .
  
• Interior heating with engine:
  The interior is heated by the engine if the engine is switched off, the engine temperature is > 45 ^o C and the water valve timing > 0%. The changeover valve is open (at zero current) , the shut-off valve is closed (power applied) .
  The interior is heated by the engine when the engine is running and the LWS temperature is less than the engine temperature and this is less than 70 ^o C. The changeover valve is open (at zero current) , the shut-off valve is closed (power applied) .
  
• Interior heating with latent heat accumulator:
  The interior is heated by the latent heat accumulator if the LWS temperature is > 30 ^o C, the engine temperature < 45 ^o C and the water valve timing > 0%. The changeover valve and the shut-off valve are closed (power applied to both) .
  
• Engine heating with latent heat accumulator:
  The engine is heated by the latent heat accumulator if the LWS temperature is > 30 ^o C, the engine temperature less than the LWS temperature and the water valve timing = 0%. The changeover valve and the shut-off valve are open (both at zero current) .
  
• Latent heat accumulator heating with engine:
  The latent heat accumulator is heated by the engine if the engine temperature is > 70 ^o C, the LWS temperature is less than the engine temperature and the water valve timing = 0%. The changeover valve and the shut-off valve are open (both at zero current) .
  If the water valve clock cycle time is > 0%, the changeover valve is open (at zero current) and the shut-off valve is closed (power applied).
  

The auxiliary water pump is switched on during operation of the latent heat accumulator when

• Ignition lock position 0 (independent ventilation/residual heat mode), 1 or 2 and water valve timing,_{left or right} > 0%
  
• LWS heating active
  

The auxiliary water pump is switched off during operation of the latent heat accumulator when

• Ignition lock position 0
  
• Water valve timing_{left or right} = 0%
  
• Temperature_LWS > 85 ^o C