Injection system with an emergency operation function and an associated emergency operation method

An injection system for an internal combustion engine, comprising:

• a reciprocating pump,
• a pressure accumulator,
• a sensor for detecting the pressure in the pressure accumulator,
• a control valve, and
• a control unit or regulation unit,
• wherein
• the control unit or regulation unit regulates the pressure in the pressure accumulator by releasing or sealing a passage to a low-pressure area by means of the control valve,
• the control unit or regulation unit executes an emergency operation in the event of a fault in the regulator circuit,
• the control valve is positioned between a low-pressure area and the pressure accumulator,
• said valve is connected to the pressure accumulator via a line,
• a non-return valve for preventing fuel flowing back from the pressure accumulator is positioned in the line in front of the pressure accumulator,
• the reciprocating pump is positioned between the control valve and the non-return valve,
• the control valve includes a valve-closing member which opens a passage proceeding from the low-pressure area in the direction of the pressure accumulator,
• for an emergency operation the control unit or regulation unit de-energizes a coil of the control valve in the event of a fault in the regulator circuit for regulating the pressure in the pressure accumulator in order to keep the valve-closing member free-moving, and
• the reciprocating pump builds up pressure in the line on completion of a take-in stroke so that the passage of the control valve is sealed by means of the valve-closing member and fuel is conveyed into the pressure accumulator.