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:

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