Method and apparatus for controlling the pressure in a common rail system
First Claim
1. A method for controlling the rail pressure (pCR) of a common rail system, comprising the steps of:
- determining a rail pressure control deviation (dp) from a comparison of a desired and an actual rail pressure, calculating a rail pressure control value from the rail pressure control deviation (dp) for the operation of a suction throttle control valve (4) via a rail pressure controller (11), wherein fuel admission to a high pressure pump (5) and consequently the rail pressure (pCR) is determined, determining from the rail pressure control value a desired current value (i(SL)) serving as guide value for a current control circuit (14) and for the calculation of a preliminary control value (U2), calculating an actual current value (i(IST)) via filters (22, 23) from a suction throttle valve current (i) which flows through the winding of the suction throttle valve (4), determining a first control value (U1) via a current controller (17) from a current control deviation (di) of the desired current value (i(SL)) from the actual current value (i(IST)), and determining the suction throttle valve current (i) by the first control value (U1) and the preliminary control value (U2).
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Accused Products
Abstract
In a common rail operating method and system, an arrangement for controlling the rail pressure is provided with a rail pressure controller including a current control circuit for controlling a suction throttle valve operating current (i) which valve is arranged in the fuel supply line to a high pressure pump supplying high pressure fuel to the common rail. The suction valve operating current control circuit includes a preliminary control value generator which serves also as an emergency control signal generator for the control of the suction valve if an error occurs in the system at least to permit an orderly engine shutdown procedure.
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Citations
19 Claims
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1. A method for controlling the rail pressure (pCR) of a common rail system, comprising the steps of:
- determining a rail pressure control deviation (dp) from a comparison of a desired and an actual rail pressure, calculating a rail pressure control value from the rail pressure control deviation (dp) for the operation of a suction throttle control valve (4) via a rail pressure controller (11), wherein fuel admission to a high pressure pump (5) and consequently the rail pressure (pCR) is determined, determining from the rail pressure control value a desired current value (i(SL)) serving as guide value for a current control circuit (14) and for the calculation of a preliminary control value (U2), calculating an actual current value (i(IST)) via filters (22, 23) from a suction throttle valve current (i) which flows through the winding of the suction throttle valve (4), determining a first control value (U1) via a current controller (17) from a current control deviation (di) of the desired current value (i(SL)) from the actual current value (i(IST)), and determining the suction throttle valve current (i) by the first control value (U1) and the preliminary control value (U2).
- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
- 15. An arrangement for controlling the rail pressure (pCR) of a common rail system in a rail pressure control circuit (10) comprising a rail pressure controller (11) for calculating a rail pressure control value from a rail pressure control deviation (dp) between a desired rail pressure (pCR(SL)) and an actual rail pressure value (pCR(IST)), a suction throttle valve (4) with a control winding (21) for controlling the supply of fuel to a high pressure pump (4) depending on the rail pressure control value, a current control circuit (14) for controlling the suction throttle control valve current (i) flowing through the control winding (21) of the suction throttle valve (4), the high pressure pump (4) having a pump performance graph (13) which is stored in the rail pressure controller (11) for determining a desired current value (i(SL)) as guide value for the current control circuit (14) and for determining a preliminary control value (U2) depending on the rail pressure control value, filters (22, 23) for determining an actual current value (i(IST)) from the suction throttle current (i), a current controller for calculating a first control value (U1) from a current control deviation (di) of the desired current value (i(SL)) from the actual current value (i(IST)), and a PWM calculation device (20) for determining the suction throttle valve current (i) to be applied to the suction throttle valve (4) depending on the first control value (U1) and the preliminary control value (U2).
Specification