[0041] figure 1 The technical environment is shown as an example, in which the method according to the invention can be used. Here, the illustrations are limited to components necessary for explaining the present invention.
[0042] in figure 1 Exemplarily shows an internal combustion engine 1 configured as a diesel motor, which includes a motor cylinder 10 and an exhaust passage 30 in which an exhaust gas flow 20 is guided. The exhaust duct 30 has an exhaust gas purification device, which in the illustrated embodiment as a catalytically coated component, when arranged along the flow direction of the exhaust gas, first has an SCR catalyst 40 and Diesel Particulate Filter 50 (DPF). Before the SCR catalyst 40, an injection unit 70 is arranged on the exhaust passage 30, and the urea-water solution can be injected by the injection unit. The injection unit 70 and the metering unit 80 belong to a metering system 60 which can be controlled by the control unit 91. The functions of the control unit 91 can be implemented in a higher-level motor control mechanism 90 such as an ECU (Electronic Control Unit) as common for diesel motors on the basis of software and/or hardware. The metering unit 80 has a delivery pump 81 as a main component, which can be configured as a reciprocating piston pump or a reciprocating diaphragm pump. When there is a demand for the amount of the metering system 60, a metering valve 71 is opened, which is a component of the injection unit 70. The diagnosis, control, and monitoring of the hydraulic pressure of the metering system 60 are performed by the control unit 91.
[0043] figure 2 In the graph 100, the current characteristic curve 103 for the coil current 101 of the delivery pump 81 is shown as part of the total cycle duration until the next operation based on the time 102 for operating the stroke of the delivery pump 81 . The current characteristic curve 103 generated with full control and the current characteristic curve 104 for partial control of the NVH operating mode for noise reduction are shown here.
[0044] The current characteristic curve 103 generated with full control shows the characteristic signal disturbance after the maximum value has passed after the time 107 (BMP) for the start of the armature movement, where the minimum value occurring here is evaluated as It is used for the time 106 of armature impact with full control (MSP-FA). In a further process, a suction stroke 108 caused by the return spring with full control is generated, which can be seen as a characteristic local maximum at the coil current 101 and the end of the suction stroke 110 with full control is usually Can detect well.
[0045] The current characteristic curve 104 in the NVH operating mode shows that there is no characteristic signal disturbance after the maximum value has passed after the time 107 (BMP) for the start of the armature movement. The moment 105 (MSP-PA) for the armature impact with partial control appears later in the profile and can be determined by a specific search algorithm as disclosed in the present invention. In the further process, an inhalation stroke 109 with its end point 111 of the inhalation stroke is also generated with partial manipulation, and the appearance time of the end of the inhalation stroke is shifted to an earlier time relative to the end point 110 of the inhalation stroke in full manipulation ( Time offset 112).
[0046] According to the present invention, the duration of the time interval 114 (Δt) is predetermined, and the end of the pulse duration is selected in this way, that is, the time 113 at which the control generated by the partial control 105 ends, so that the predetermined Time interval 114 (Δt). In a specific embodiment, the actual value of the time interval (Δt actual ) And the predetermined time interval 114 (Δt) delivered as the target value is adjusted by selecting the end of the pulse duration. The predetermined time interval 114 (Δt) is determined in accordance with the optimization between the lowest possible noise emission and the most effective transmission power. The control voltage can basically be delivered as a constant direct voltage or as a pulse width modulated voltage.
[0047] This NVH operating mode for building pressure in the system is only activated in the motor-stop phase or when the motor speed is below the threshold and the vehicle is in a stopped state.
[0048] In this operating mode, the energy of the armature movement and thus the speed of the armature is reduced before reaching the armature stop (MSP) in order to be able to achieve the desired sound reduction. In the normal pump-operation mode, when the armature reaches the armature stop MSP, the armature strikes with maximum energy, which results in high sound emission.
[0049] During the period when the NVH operating mode is active, the control of the electromagnetic coil is applied so that the energy supply to the electromagnetic coil is cut off before the armature reaches the armature stop MSP. In this way, the acceleration of the armature movement can be reduced. The reduction in the impact speed of the armature on the mechanical stop results in a reduced sound emission. However, if the energy loading of the electromagnetic coil of the delivery pump 81 is cut off or reduced too early, an incomplete delivery stroke will occur, and the incomplete delivery stroke will have a negative impact on the volume flow of the medium to be delivered. That is, in the NVH operating mode, it is important that the energy supply or control of the electromagnetic coil is carried out at the correct time, in order to ensure the full stroke on the one hand and on the other hand to reduce the collision speed in such a way that a significant reduction occurs. The sound emission.
[0050] In the normal pump operation mode, the time for the last armature impact with full control (MSP-FA=the time of armature impact with full control 105) is determined for the next stroke The pulse time. In the NVH operating mode, the control is stopped before the occurrence of MSP-FA, so the current characteristic curve 104 in the NVH operating mode may be different from the coil current for the delivery pump 81 performed in full control. 101的current characteristic curve 103.
[0051] In order to identify the moment for armature impact with partial manipulation (MSP-PA = time 106 of armature impact with partial manipulation), a new algorithm is needed for detecting armatures with small impact energy Hit. In order to ensure the full stroke at a small collision speed, the moment 106 of the armature impact (MSP-PA) with the partial operation within the defined time after the partial operation should be displayed. MSP-PA detection is realized. If the MSP-PA is not recognized, the part is calculated from the saturation current on the basis of the time 107 for the start of the armature movement (BMP) and the additional time-based system pressure according to the invention Manipulation.
[0052] The pressure model is based on the time used for MSP and BMP. Will be based on MSP pressure (p MSP ) And BMP-based pressure (p BMP ) Is used to derive the pressure correction value (p corr ). Use the pressure correction value (p corr ) Pressure based on BMP (p BMP ) To correct and derive the final pressure-model value (p MDL ).
[0053] If the delta pressure (Δp), which is the difference between the MSP pressure and the pressure BMP, is less than a predefinable threshold value, only the NVH operating mode is activated. The NVH operating mode is not required, if the delta pressure (Δp) is greater than the threshold value and the armature movement is slow enough to be used to reduce sound emissions.
[0054] image 3 The control profile 203 is shown in another graph 200, wherein the control pattern 201 is shown as a function of the pressure 202. During the period during which the NVH operating mode is active and the system loads part of the control 204 on the pump, such as full control 205 in 1 bar steps (based on BMP) with a pulse time based on the stroke effective in the last BMP, where Check whether the delta pressure (Δp) is less than the threshold. If this is the case, activate or continue the NVH operating mode. Part of the manipulation 204 is performed in this phase.
[0055] If the full maneuver 205 is performed after the partial maneuver 204, the pulse duration is determined based on the pulse duration ascertained in the stroke effective in the last BMP and from the confidence interval. This confidence interval is calculated from the system pressure and the saturation current. Apply here:
[0056]
[0057] among them
[0058]
[0059] Where t Impuls , FA Is the pulse duration during full control, ti BMP,n-1 Is the pulse duration in the stroke valid in the last BMP, ti confi Is the confidence interval, p is the system pressure, and I sat Is the saturation current.
[0060] When the system executes the full stroke, the pressure correction value (p corr ) Until the next full stroke.
[0061] The next stroke after the full stroke will be a partial stroke, where this stroke is based on the last partial-stroke-duration, and the pressure model calculates the pressure from the BMP at the start time of the partial stroke and the corrected pressure ( p corr ) Is determined on the basis of the last full stroke. Apply here:
[0062]
[0063] The correction pressure is a function of the BMP pressure and the MSP pressure, and the pump performs the full stroke:
[0064]
[0065] For the NVH operating mode, the software uses two strategies for operating the delivery pump 81:
[0066] -Calculate the pulse duration t for partial control Impuls, PA , If it can be verified that the moment of armature impact with partial control 106 ti MSP,PA , This is done using steps 3 and 4 in the next calculation step, and
[0067] -Calculate the pulse duration t for partial control Impuls, PA , If the moment of armature impact with partial control cannot be verified 106 ti MSP,PA , This is done with step 5 in the next calculation step.
[0068] The evaluation method includes the following steps:
[0069] 1. The first stroke should be a full stroke, and the pulse duration calculation is based on the pressure model and saturation current
[0070]
[0071] 2. Calculate the delta pressure (Δp) from the first stroke and freeze the corrected pressure p for another stroke corr , Use this to correct the pressure p corr Calculate the pressure model for the additional stroke until the next full stroke:
[0072]
[0073] 3. Perform a partial stroke, if Δp is less than the threshold
[0074] 4. Calculate the pulse duration t for partial control based on the following function Impuls, PA , If the moment of armature impact with partial control is identified 106 ti MSP,PA :
[0075]
[0076] Where Δt error,n-1 Is the error-time difference and Δt PA,meas,n Is the measured time difference
[0077] 5. Determine the moment 106 ti for the armature impact with partial control MSP,PA The target value of the time difference between and the final moment of 205, which is derived according to the following formula:
[0078]
[0079] 6. If the moment of armature impact with partial control is not detected 106 ti MSP,PA , But Δp is always less than the defined threshold, then an alternative partial control 205 is activated, which is subject to the following conditions:
[0080]
[0081] among them
[0082]
[0083] Where f 1 And f 2 Is a factor, which is generated on the one hand from the pressure difference at the beginning of the armature motion (BMP) and on the other hand from the difference stored according to the model for the saturation current
[0084] 7. If in the same pressure build-up cycle, the moment of armature impact with partial control is recognized once and then no longer recognized 106 ti MSP,PA , It is stipulated here to re-implement the search algorithm. To this end, on the basis of step 6, reset the pulse time to a standard value and restart the search algorithm. During the execution of the retrieval algorithm, it should be ensured that the pulse time does not match the pulse time for full control or only an incomplete stroke is generated therefrom. This can be achieved on the one hand by limiting the pulse duration to the maximum time that can be derived from the last full stroke, and on the other hand by limiting the pulse duration to the maximum time that can be derived from step 6. Minimum time.
[0085] Used to detect the moment of armature impact with partial control 106 ti MSP,PA The digital algorithm at least includes the following steps:
[0086] 1. Record the current coil current characteristic curve 104 in the NVH operating mode during the pump stroke;
[0087] 2. Extract the coil current characteristic curve from the time when the control is stopped to the following time, at which the coil current is less than the applicable threshold;
[0088] 3. Filter the signal;
[0089] 4. Mirror the filtered signal;
[0090] 5. Form the second derivative of the signal;
[0091] 6. Form the induced average value of the output signal according to step 4;
[0092] 7. Filter the output signal of step 5;
[0093] 8. Determine the maximum value on the left side in the output signal of step 6. After the maximum value is determined, the minimum value is determined on the right side of the output signal according to step 6;
[0094] 9. Calculate the difference between the maximum value and the minimum value from step 8, and save the difference value, and retrieve the first maximum value on the right side of the output signal according to step 6;
[0095] 10. If the next largest point is greater than the last largest point, retrieve the smallest point on the right side of the new largest point;
[0096] 11. Calculate the difference between the new maximum value and the new minimum value;
[0097] 12. If the new difference from step 11 is greater than the old difference from step 9, then use the new maximum to overwrite the old maximum, and use the new difference from step 11 to overwrite the Old difference
[0098] 13. Continue to search for the complete curve from the left to the right, and determine the maximum value of the curve with the largest difference;
[0099] 14. If this maximum value is greater than a predetermined threshold value and the difference is greater than this threshold value, the moment of armature impact with partial control 106 ti is identified for the partial stroke MSP-PA MSP,PA;
[0100] 15. For the part of the stroke MSP-PA, indicate the moment of armature impact with partial control 106 ti MSP,PA.
