System and method for reducing the fuel pressure in a fuel injection system

Claim 3

The method in accordance with claim 1, which comprises triggering the control valves (31, 45) for reducing the pressure in the common rail (7) at high frequencies after the engine has been shut off.

Claim 4

The method in accordance with claim 1, which comprise triggering the control valves (31, 45) provided on the individual injection valve (11) for reducing the pressure in the common rail (7) at high frequencies in succession after the engine has been shut off.

Claim 5

A fuel injection system for reducing a fuel pressure in a fuel injection system for internal combustion engines, comprising a pump (1) for feeding fuel into a common rail (7), a fuel injection valve (11), an injection valve member (15) operative in said fuel injection valve, first and second pressure chambers in said injection valve that act upon the injection valve member (15), said first pressure chamber (23) communicates constantly with the common rail (7) and fuel under pressure urges the valve member in an opening direction, a second pressure chamber forms a control chamber (29) and fuel under pressure urges the valve member (15) in the closing direction, pressure lines (9) lead from said common rail (7) to each of said pressure chambers, a control valve (31) on said injection valve, said control valve controls flow of fuel from said second pressure chamber to a relief line (35) which feeds fuel in said relief line to a supply tank, in that the pressure in the common rail (7) after shutoff of the engine and termination of feeding of the pump (1) is relieved into the supply tank (5) via the control valve (31), the control valve (31) connects the pressure chamber (29, 323) of the injection valve (11) briefly with the common rail (7) or the supply tank (5) so that the pressure acting upon the valve member (15) of the injection valve (11) in the opening direction remains below an opening pressure of the injection valve (11), and this triggering operation of the control valve (31, 323) is repeated until a desired reduced pressure in the common rail (7) is attained.

Claim 6

A fuel injection system for reducing a fuel pressure in a fuel injection system for internal combustion engines, comprising a pump (1) for feeding fuel into a common rail (7), a fuel injection valve (11), an injection valve member (15) operative in said fuel injection valve, first and second pressure chambers in said injection valve that act upon the injection valve member (15), said first pressure chamber (23) communicates constantly with the common rail (7) and fuel under pressure urges the valve member in an opening direction, a second pressure chamber forms a control chamber (29) and fuel under pressure urges the valve member (15) in the closing direction, pressure lines (9) lead from said common rail (7) to each of said pressure chambers, a control valve (31) on said injection valve, said control valve controls flow of fuel from said second pressure chamber to a relief line (35) which feeds fuel in said relief line to a supply tank, in that the pressure in the common rail (7) after shutoff of the engine and termination of feeding of the pump (1) is relieved into the supply tank (5) via the control valve (31), the control valve (31) connects the pressure chamber (29, 323) of the injection valve (11) briefly with the common rail (7) or the supply tank (5) so that the pressure acting upon the valve member (15) of the injection valve (11) in the opening direction remains below an opening pressure of the injection valve (11), and this triggering operation of the control valve (31, 323) is repeated until a desired reduced pressure in the common rail (7) is attained.

Claim 7

A fuel injection system as set forth in claim 4, in which said second pressure chamber communicates constantly with the common rail (7) via a connecting line (49), said connecting line includes a first throttle (47), and said second chamber is made to communicate with the relief chamber (5) by means of the control valve embodied as a 2/2-way valve (45).

Claim 8

A fuel injection system as set forth in claim 4, in which one pressure chamber (323) that urges the valve member (15) in the opening direction is provided on the injection valve (11), and said second pressure chamber is made to communicate with the common rail (7) or a relief chamber (5) by means of the control valve embodied as a 3/2-way valve (31).

Claim 9

A fuel injection system in accordance with claim 6, in which a pressure valve (53) that opens in a direction of the relief chamber (5) is disposed in the relief line (35) leading from the control valve (31) to the relief chamber (5).

Claim 10

A fuel injection system in accordance with claim 4, in which the control valve (31, 45) is connected to an electromagnet (37) that actuates said control valve and is triggered by a control unit (39) that processes operating parameters of the engine.

Claim 11

A fuel injection system in accordance with claim 5, in which the control valve (31, 45) is connected to an electromagnet (37) that actuates said control valve and is triggered by a control unit (39) that processes operating parameters of the engine.

Claim 12

A fuel injection system in accordance with claim 6, in which the control valve (31, 45) is connected to an electromagnet (37) that actuates said control valve and is triggered by a control unit (39) that processes operating parameters of the engine.

Claim 13

A fuel injection system in accordance with claim 8, in which a pressure sensor (43) is connected to the control unit (39) by insertion into the common rail (7) which is connected to the pressure pump (1).

Claim 14

A fuel injection system in accordance with claim 9, in which a pressure sensor (43) is connected to the control unit (39) by insertion into the common rail (7) which is connected to the pressure pump (1).

Claim 15

A fuel injection system in accordance with claim 10, in which a pressure sensor (43) is connected to the control unit (39) by insertion into the common rail (7) which is connected to the pressure pump (1).

Claim 16

A fuel injection system as set forth in claim 4, in which the control valve (31, 45) for reducing the pressure in the common rail (7) are triggered at high frequencies after the engine has been shut off.

Claim 17

A fuel injection system as set forth in claim 4, in which the control valve (31, 45) that are provided on individual injection valves (11) for reducing the pressure in the common rail (7) are triggered in succession after the engine has been shut off.