Pneumatic control system

Pneumatic control system (PRS)

The pneumatic control system (PRS) regulates the pneumatic control of the valves of the fuel supply system. It is connected to the two fill / extraction valves for gaseous and liquefied hydrogen (H2) via two pneumatic control lines and also with the line for active flushing. These fill / extraction valves are pneumatically operated and activated via electrical valves.

To supply the combustion engine in the BMW Hydrogen 7 vehicle with H2, the Clean Energy control unit (CESG) opens the engine shutdown valve and the valve V_PRS_SG. These two valves are opened with a temporal offset. At the start of the hydrogen mode, the valve V_PRS_SF is opened briefly and closed again. On termination of the hydrogen mode, the valves V_PRS_SG and the engine shutdown valve are closed for a certain time after the end of the mode.

Note:

At the start of cold refuelling, the cold valves V_PRS_SG and V_PRS_SF are open.

Pneumatic valve timing

The essential tasks of the PRS are:

• Control of the pressure in the pressure accumulator: air can be pumped into the pressure accumulator via the compressor and the tank valve.
  
• Activation of the H2 fill and extraction valves: the electrical valves V_BEV_F and V_BEV_G are activated via the pneumatic valves V_PRS_G and V_PRS_F.
  
• Flushing the secondary system capsule: with increased H2 concentration, the secondary system capsule (NSK) is flushed with air via the compressor and a valve.
  
• Regeneration: to regenerate the air drier, air is blown off by activation of the valves V_PRS_RV and V_PRS_BV.
  

Component diagnosis

Within the framework of the test modules for these components, the following faults are covered:

• 64B6 partial-flow control valve
  
• 6504 partial-flow control valve
  
• 6509 heat exchanger
  
• 64B7 engine shutdown valve
  
• 6505 engine shutdown valve
  
• 64CE pressure accumulator, PRS valve
  
• 64D4 pressure fault in pressure accumulator
  
• 64D5 pressure build-up fault in pressure accumulator
  
• 64CF NSK flushing PRS valve
  
• 64D7 PRS flushing unsuccessful
  
• 64DB pressure relief valve leaking
  
• 64DC pressure relief valve blocked
  
• 64D1 control valve for withdrawal of liquefied H2
  
• 64D3 pneumatic system, pressure build-up or reduction
  
• 64E7 fill and extraction valve for liquefied H2
  
• 64EA defective partial vacuum on tank filler neck or open blocked fill / extraction valve with no refuelling and no H2 operation
  
• 64D2 control valve for withdrawal of gaseous H2
  
• 64E8 defective partial vacuum on tank filler neck or open blocked fill / extraction valve during H2 refuelling
  
• 64E9 defective partial vacuum on tank filler neck or open blocked fill / extraction valve during H2 operation
  
• 6503 control valve for gaseous H2
  
• 6508 fill and extraction valve for gaseous H2
  
• 64CD additional ventilation valve
  
• 64D0 regeneration of PRS valve