CN108980020B

CN108980020B - Method and device for operating a delivery pump

Info

Publication number: CN108980020B
Application number: CN201810548497.9A
Authority: CN
Inventors: R.约希; C.拜尔; J.马克坦德
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2017-06-01
Filing date: 2018-05-31
Publication date: 2022-06-14
Anticipated expiration: 2038-05-31
Also published as: CN108980020A; KR20180131973A; KR102601562B1; DE102017209272A1

Abstract

The invention relates to a method and a device, in particular a control unit, for operating an electric delivery pump designed as a reciprocating diaphragm pump or a reciprocating piston pump, wherein, in order to carry out a delivery stroke by partial actuation within a total cycle duration, during an actuation phase, an actuation voltage is applied to a solenoid coil of the delivery pump within a range of such a long pulse duration that an armature strike of the delivery pump is achieved in a time interval after the actuation phase, and the time of the armature strike is determined by evaluating a current characteristic of a coil current flowing through the solenoid coil, wherein the duration of the time interval is predefined and the end of the pulse duration is selected such that a predefined time interval is observed. In this way, the control scheme for the delivery pump, which is designed to avoid noise, vibrations and jerky operation, can be optimized with regard to the delivery output and/or the noise generation.

Description

Method and device for operating a delivery pump

Technical Field

The invention relates to a method for operating an electric delivery pump designed as a reciprocating diaphragm pump or a reciprocating piston pump, wherein, in order to carry out a delivery stroke by partial actuation within a total cycle duration, during an actuation phase, an actuation voltage is applied to a solenoid coil of the delivery pump within a range of such a long pulse duration that an armature strike of the delivery pump is achieved in a time interval (Delta t) after the actuation phase, and the time of the armature strike is determined by evaluating a current characteristic curve of a coil current flowing through the solenoid coil.

The invention further relates to a device, in particular a control unit, for carrying out the method according to the invention.

Background

To satisfy today's needsFor example, a urea-water solution, which reduces nitrogen oxides, is injected into the exhaust gas tract of an internal combustion engine in a targeted manner by means of a dosing system before the SCR catalytic converter, ammonia being formed in the exhaust gas, which contributes to the NO in the exhaust gas_x-content reduction. SCR stands for "selective catalytic reduction". The SCR system consists of a tank and a delivery unit which sucks the urea-water mixture from the tank via a filter unit, builds up the system pressure and injects it into the exhaust system of the diesel vehicle via a metering valve.

In the current SCR dosing systems such as those disclosed by the applicant for passenger cars under Denoxtronic 5.x, reciprocating diaphragm pumps are used in order to convey urea-water solutions (also known as AdBlue) into the exhaust tract and to the SCR catalyst. The armature of this pump is moved by magnetic force induced via a coil. The magnetic force accelerates the armature, which thereby executes a delivery stroke. The subsequent intake stroke is effected by a spring which moves the armature back into its initial position. The coil is energized for a predetermined time in order to establish the magnetic force. In the current series, this duration is dependent on the movement of the armature. If the armature reaches its final position at the stop, this can be seen in the current signal read off from the solenoid coil. A few milliseconds after this event ends the energization of the electromagnetic coil, the magnetic field decays and the armature moves back into the original position by the spring force. Since the armature is accelerated by the magnetic force during the entire movement of the armature, the armature reaches a certain speed and strikes the stop with a corresponding pulse. Undesirable noise is generated due to such sudden braking of the armature.

Impact noise can be reduced by two measures: slowing down the impact, which has the disadvantage of distorting the current signal and thus the observability of the armature movement; or reduce the armature speed. Instead of activating the current supply to the electromagnetic coil during the entire movement of the armature as in the past, in a second solution the current supply to the coil is switched off shortly before the impact position of the armature. The armature is thus not further accelerated and is even slowed down by the remaining magnetic field and spring force. This results in a lower speed of the armature with a smaller pulse in the stop and thus in a lower noise.

DE 102014225200 a1 describes a method for operating a reciprocating piston pump, wherein the reciprocating piston pump delivers liquid into a pressure region with a pressure accumulator, wherein the pressure in the pressure region is measured and is maintained within a predefined pressure range by the reciprocating piston pump, wherein the reciprocating piston pump is operated by a supply voltage which is periodically switched on and off, and wherein the supply voltage of the reciprocating piston pump is determined. It is provided that the actuation duration for the next stroke of the reciprocating piston pump is determined and predefined at least from the supply voltage applied to the reciprocating piston before the stroke and the pressure prevailing in the pressure region before the stroke. According to DE 102014225200 a1, the actuation of the reciprocating piston pump can be carried out in such a way that the actuation duration of the next stroke is selected in such a way that the armature of the reciprocating piston pump has just reached its impact point or the armature has not just reached its impact point. If the actuation duration is selected such that the armature just reaches its impact point, a full stroke and thus a maximum delivery volume of the reciprocating piston pump per stroke is reached. At the same time, the actuation of the reciprocating piston pump is terminated immediately after the stop is reached, so that the armature falls back into its rest position as quickly as possible and the next stroke can be started. In this way, the maximum delivery capacity for given operating conditions is achieved with simultaneously minimum power losses of the reciprocating piston pump. If the actuation duration is limited in such a way that the armature does not just reach its impact point, the noise generation of the reciprocating piston pump can be significantly reduced relative to the impacting armature. This saves additional costly measures for suppressing noise. Since the actuation is selected such that the flight of the armature is terminated shortly before the impact point of the armature, the complete travel path is almost completed, so that the delivery volume is only slightly reduced in relation to the impacting armature. Furthermore, DE 102014225200 a1 describes that a model-based controlled system is stored as software in a control unit for optimizing the pressure buildup behavior and for calculating the actuation duration of the reciprocating piston pump.

For such a mode of operation, also referred to as acoustic function or NVH: (Noise-Vibration-Harshiness, i.e. the avoidance of noise, vibrations and jerky operation), it is problematic that the current signals generated in such manipulations are difficult to evaluate in terms of armature movement and further information for pump operation and for control of the pump.

Disclosure of Invention

The object of the invention is therefore to provide an alternative control strategy for such a reciprocating diaphragm pump and an algorithm for evaluating such a current signal, in particular with NVH control.

The object of the invention is, furthermore, to provide a corresponding device, in particular a control unit, for carrying out the method.

The task associated with the method is solved by the following features: predetermining the duration of the time interval and selecting the end of the pulse duration such that the predetermined time interval is observed; detecting or determining the actual value of the time interval and adjusting it to a predefinable time interval that is delivered as the target value by selecting the end of the pulse duration; determining the predetermined time interval in accordance with an optimization between the lowest possible noise emission and the most efficient possible transmission power; -delivering the steering voltage as a substantially constant direct voltage or as a pulse width modulated voltage; if the time of the armature impact is not detected from the current characteristic curve, the time of the armature impact is calculated according to a model on the basis of the time for the start of the armature movement and on the basis of the time-based system pressure and the saturation current; determining a delta pressure as a difference between the pressure during the armature impact and the pressure at the beginning of the armature movement and determining therefrom the time of the armature impact with the partial actuation and adjusting the operating mode with the partial actuation on the basis thereof; during the activation of the operating mode with partial actuation and the application of partial actuation to the electrical delivery pump, a full actuation initiated in a specific pressure interval is carried out with a specific pulse time on the basis of the effective stroke determined in the last armature movement, wherein it is checked whether the delta pressure is below an applicable threshold value and, if this is the case, the operating mode with partial actuation is continued; for operating modes with partial actuation, it is to be distinguished during the evaluation and calculation of the pulse duration for the partial actuation whether the time of the armature impact with partial actuation can be ascertained from the current characteristic curve, on the basis of which different calculation strategies can then be used for adjusting the pulse duration; for detecting an armature impact with a partial actuation, a multi-stage numerical detection algorithm is used for determining the time of the armature impact with a partial actuation, which at least partially comprises the following steps: i.) recording the current coil current characteristic during a pump stroke; ii.) extracting a coil current characteristic curve from the moment when the control is stopped until the moment when the coil current is less than an applicable threshold value; iii.) filtering the signal according to step ii); iv.) mirror the filtered signal; v.) forming a second derivative of the signal; vi.) forming a sensed average of the output signals according to step iv); vii.) filtering the output signal according to step v.); viii.) a maximum determination is made on the left side in the output signal of step vi.) and then a minimum determination is made on the right side of the output signal according to step vi.); ix.) calculating the difference between the maximum and minimum values from step viii) and saving said difference and retrieving the first maximum value on the right side of the output signal according to step vi); x.) check if the next maximum point is greater than the last maximum point, and, if this condition is met, then retrieve the minimum point on the right side of the new maximum point; xi.) calculating the difference between the new maximum and the new minimum; xii.) checking the new difference from step xi), whether this new difference is larger than the old difference from step ix), and, if this condition is met, overwriting the old maximum with the new maximum and the old difference from step ix) with the new difference from step xi); xiii.) continue to retrieve and determine the maximum of the curves with the largest difference for the complete curve from left to right; xiv.) checks whether this maximum value is greater than a predefinable threshold value and whether the difference is greater than this threshold value, and, if this condition is fulfilled, identifies an impact point in time for the partial maneuver, and xv.) indicates the impact point in time.

According to the invention, the duration of the time interval (Δ t) is predefined and the end of the pulse duration is selected such that the predefined time interval (Δ t) is observed. This approach has the following advantages: the time interval (Δ t) can be predefined with a noise selection and/or an optimization with respect to the delivery power of the delivery pump, without having to take into account further parameters in detail.

In a preferred method variant, it is provided that the actual value (Δ t) of the time interval is detected or determined_{Practice of}) And is adjusted to a predetermined time interval (Δ t) delivered as a target value by selecting the end of the pulse duration. The end of the pulse duration for compliance (Δ t) can be determined on the basis of a plurality of preceding impact moments or only one preceding impact moment, and the actual value of Δ t can then be adjusted to the target value of Δ t for the next cycle.

In a further preferred variant of the method, the predefined time interval (Δ t) is determined in accordance with an optimization between the lowest possible noise emission and the most efficient possible transmission power. This is advantageous if, depending on the location of use of the delivery pump, different operating phases exist in which, on the one hand, a high delivery capacity is important or, in other cases, noise minimization is important.

In all the above-described method variants, the actuation voltage can be supplied as a substantially constant direct voltage or as a pulse-width-modulated voltage, which can be dependent on the operating phase of the delivery pump.

A method variant provides that, if the time of the armature impact is not detected from the current characteristic curve, the time of the armature impact, which is carried out with partial actuation, is calculated from a model on the basis of the time for the start of the armature movement and on the basis of the time-based system pressure and saturation current. In contrast to DE 102014225200 a1, the pressure determination for the armature actuation is not used during normal operation, but rather the impact time is determined from the current curve, wherein this time can also be determined in the current curve generated with the partial actuation under normal conditions. Only at the beginning of operation or if the impact point in time is not detected from the current curve, it is possible, for example, to also use the pressure or the pressure characteristic curve for determining the point in time. The pressure model is based on the time for the MSP (time of armature impact) and the time for BMP (time of start of armature movement). Will be based on MSP pressure (p) _MSP) With BMP-based pressure (p)_BMP) The difference between them is used to derive a pressure correction value (p)_corr). Using said pressure correction value (p)_corr) Pressure (p) against BMP_BMP) Correction is performed and the final pressure-model value (p) is derived_MDL）。

In this case, the delta pressure (Δ p) can be determined as the difference between the pressure during the armature impact and the pressure at the beginning of the armature movement, and the time of the armature impact with the partial actuation can be determined therefrom, and the operating mode with the partial actuation can be set on the basis thereof.

During the operation mode with partial actuation and the application of partial actuation to the delivery pump, the full actuation initiated in a specific pressure interval can also be carried out with a specific pulse time on the basis of the effective stroke determined during the last armature movement, wherein it is checked whether the delta pressure (Δ p) is below an applicable threshold value and, if this is the case, the operation mode with partial actuation is continued. This is not necessary if the delta pressure (Δ p) is greater than a threshold value and the armature moves slowly enough to reduce sound emissions.

In a further method variant, it can be provided that, for operating modes with partial actuation, during the evaluation and calculation of the pulse duration for the partial actuation, a distinction is made between whether the time of an armature impact with partial actuation can be ascertained from the current characteristic curve, and then a different calculation strategy is applied to adjust the pulse duration accordingly.

For the case in which the time of the armature impact cannot be ascertained from the current characteristic curve, a multi-stage numerical identification algorithm can advantageously be used for identifying the armature impact with partial actuation for determining the time of the armature impact with partial actuation, which multi-stage numerical identification algorithm comprises at least in part the following steps:

i.) recording the current coil current characteristic during a pump stroke;

ii.) extracting a coil current characteristic from the time of the cessation of the actuation up to the time at which the coil current is less than an applicable threshold value;

iii.) filtering the signal according to step ii);

iv) mirroring (Spiegeln) the filtered signal;

v.) forming a second derivative of the signal;

vi.) forming a sensed average of the output signals according to step iv);

vii.) filtering the output signal according to step v.);

viii.) a maximum determination is made on the left side in the output signal of step vi.) and then a minimum determination is made on the right side of the output signal according to step vi.);

ix.) calculating the difference between the maximum and minimum values from step viii) and saving said difference and retrieving the first maximum value on the right side of the output signal according to step vi);

x.) checking if the next maximum point is greater than the last maximum point and, if this condition is met, then retrieving the minimum point on the right side of the new maximum point;

xi.) calculating the difference between the new maximum and the new minimum;

xii.) checking the new difference from step xi), whether this new difference is larger than the old difference from step ix), and, if this condition is met, overwriting the old maximum with the new maximum and the old difference from step ix) with the new difference from step xi);

xiii.) continue to retrieve and determine the maximum of the curves with the largest difference for the complete curve from left to right;

xiv.) checks whether this maximum value is greater than a predefinable threshold value and whether the difference is greater than this threshold value, and, if this condition is fulfilled, identifies the impact point in time for the partial maneuver, and

xv.) indicates the impact time.

A preferred application of the method described above and its variants provides for use in a metering system for actuating a delivery pump, in particular a reciprocating diaphragm pump, which is generally formed by a metering unit having the delivery pump and an injection unit having a metering valve, with which the nitrogen oxides are reduced in the flow direction of the exhaust gas during high-load operation of an internal combustion engine designed as a diesel motor for nitrogen oxide reduction The storage catalyst previously dosed hydrocarbons in the form of diesel fuel into the exhaust gas tract. This metering system is also known as a dieir system and is used in particular for reducing nitrogen oxides in small diesel internal combustion engines, such as are used for example in passenger cars. Diair stands for "Diesel NOx Aftertreatment by Adsorbed Intermediate RReductants "(diesel nox aftertreatment with adsorbed intermediate reducing agents). In the dieir mode, diesel fuel is additionally injected, in particular during high-load operation of the internal combustion engine. Such fuel injection can also be used additionally during the regeneration of a Diesel Particulate Filter (DPF) in order to increase the exhaust gas temperature. An alternative application is intended for use in so-called SCR exhaust gas purification systems. Here, an aqueous urea solution (also known as AdBlue) which reduces nitrogen oxides is introduced in the flow direction of the exhaust gas before the SCR catalyst. Such a system is known, for example, as denox nic 5.x of the applicant. In this case, in particular, reciprocating piston pumps are also used for the return conveyance of the operating medium, which during operation of the reciprocating piston pumps should lead to a noise reduction during their operation. With the method according to the invention, on the one hand, the disruptive "squeaking" that can be heard in the operation according to the prior art can be largely suppressed, and on the other hand, this can be achieved with the method: the thermal load of the switching output stage required for this purpose can be reduced and component aging, in particular capacitor aging, due to high switching frequencies and/or switching currents can also be minimized.

The task related to the device is solved by: the control unit has means for carrying out the method described above, together with variants thereof. This is in particular the means for generating the pulse-width-modulated voltage signal and the means for analyzing the current characteristic of the coil current, such as the ADC unit and the filter function. The embodiment can be provided at least partially on the basis of software, wherein the control unit can be designed as a separate unit or as an integrated component of a higher-level motor control. Usually, no hardware modifications are required for this purpose, since these components are already part of the control unit for controlling the valve, which simplifies the implementation of the method according to the invention.

Drawings

The invention is explained in detail below with the aid of embodiments shown in the drawings. Wherein:

FIG. 1 exemplarily illustrates a technical environment for the present invention;

fig. 2 shows a first graph of the time profile of the coil current of the delivery pump; and is

Fig. 3 shows a control curve for the delivery pump in a second curve diagram.

Detailed Description

Fig. 1 shows an exemplary technical environment in which the method according to the invention can be used. Here, the drawings are limited to components necessary for explaining the present invention.

Fig. 1 shows an exemplary internal combustion engine 1 in the form of a diesel motor, which comprises a motor housing 10 and an exhaust gas duct 30, in which an exhaust gas flow 20 is guided. The exhaust gas duct 30 has an exhaust gas purification device, which in the exemplary embodiment shown, as a catalytically coated component, has an SCR catalytic converter 40 and a diesel particulate filter 50 (DPF) first, arranged in the flow direction of the exhaust gas. An injection unit 70 with which a urea-water solution can be injected is arranged on the exhaust gas duct 30 before the SCR catalyst 40. The injection unit 70 and the dosing unit 80 belong to a dosing system 60, which can be actuated by a control unit 91. The function of the Control unit 91 can be implemented on the basis of software and/or hardware in a higher-level motor Control 90, such as an ecu (electronic Control unit), as is customary for diesel motors. The metering unit 80 has, as a main component, a delivery pump 81, which can be designed as a reciprocating piston pump or as a reciprocating diaphragm pump. When there is a demand for quantity from the metering system 60, a metering valve 71 is opened, which is part of the injection unit 70. The diagnosis, control and monitoring of the hydraulic pressure of the metering system 60 is performed by the control unit 91.

Fig. 2 shows a current characteristic curve 103 for a coil current 101 of the delivery pump 81 in a curve diagram 100 as a function of the time 102 for actuating the stroke of the delivery pump 81 as a part of the total cycle duration until the next actuation. The current characteristic 103 generated with full operation and the current characteristic 104 for a partial operation of the NVH operating mode for noise reduction are shown here.

The current characteristic 103 generated with full actuation shows the characteristic signal disturbance after the maximum value has elapsed after the time 107 (BMP) for the start of the armature movement, the minimum value occurring in this case being evaluated as the time 106 for the impact of the armature with full actuation (MSP-FA). In a further process, a suction stroke 108 is generated, which is caused by the return spring with full actuation, which can be seen as a characteristic local maximum at the coil current 101 and the end 110 of the suction stroke with full actuation can usually be detected very well.

The current characteristic 104 in the NVH operating mode shows that after a maximum value has elapsed after the time 107 (BMP) for the start of the armature movement, no characteristic signal disturbance is present. The time 105 for the armature strike with partial actuation (MSP-PA) occurs later in the course and can be determined by a special search algorithm as disclosed in the present invention. In a further sequence, an intake stroke 109 is also generated with a partial actuation with its intake stroke end 111, the time of occurrence of which is offset (time offset 112) to an earlier time with respect to the intake stroke end 110 with a full actuation.

According to the invention, the duration of time interval 114 (Δ t) is predefined and the time 113 of the end of the pulse duration, i.e. the end of the maneuver produced by partial maneuver 105, is selected such that predefined time interval 114 (Δ t) is observedΔ t). In a specific embodiment, the actual value (Δ t) of the time interval can be detected or determined_{Practice of}) And the predefined time interval 114 (Δ t) to be supplied as the target value is set by the selection of the end of the pulse duration. The predefined time interval 114 (Δ t) is determined in accordance with an optimization between the lowest possible noise emission and the most efficient possible transmission power. The control voltage can be supplied as a substantially constant direct voltage or as a pulse-width-modulated voltage.

Such an NVH operating mode for building up pressure in the system is activated only during the motor-stop phase or when the motor speed is below a threshold value and the vehicle is in a standstill.

In this operating mode, the energy of the armature movement and thus the speed of the armature is reduced before the armature stop (MSP) is reached in order to enable the desired sound reduction. In the normal pump operating mode, when the armature reaches the armature stop MSP, the armature strikes with maximum energy, which leads to high sound emissions.

During the functioning of the NVH operating mode, the actuation of the solenoid coil is used in such a way that the energy supply to the solenoid coil is switched off before the armature reaches the armature stop MSP. In this way, the acceleration of the armature movement can be reduced. Reduced sound emission is produced by a reduction in the impact speed of the armature on the mechanical stop. If, on the other hand, the energy supply of the solenoid of the delivery pump 81 is switched off or reduced too early, an incomplete delivery stroke occurs, which has a negative effect on the volume flow of the medium to be delivered. In the NVH operating mode, it is important that the energy supply or actuation of the solenoid is carried out at the correct time in order to ensure, on the one hand, a full stroke and, on the other hand, to reduce the crash speed in this case in such a way that significantly reduced sound emissions occur.

In the normal pump actuation mode, the pulse time for the next stroke is determined on the basis of the time for the last armature impact in full actuation (MSP-FA — time 105 for the armature impact in full actuation). In the NVH operating mode, the actuation is stopped before MSP-FA occurs, so that the current characteristic 104 in the NVH operating mode may differ from the current characteristic 103 for the coil current 101 of the delivery pump 81 in full actuation.

In order to identify the time for an armature impact with partial actuation (MSP-PA), the time 106 for an armature impact with partial actuation, a new algorithm is required to be able to detect an armature impact with low impact energy. In order to ensure a full stroke with a low impact speed, the time 106 of the armature impact with partial actuation (MSP-PA) within a defined time after the partial actuation should be displayed, which is achieved by the detection of the MSP-PA during this time. If the MSP-PA is not recognized, the partial manipulation is calculated according to the invention on the basis of the time 107 (BMP) for the start of the armature movement and an additional time-based system pressure and from the saturation current.

The pressure model is based on the time instants for MSP and BMP. Will be based on MSP pressure (p)_MSP) With BMP-based pressure (p)_BMP) The difference between them is used to derive a pressure correction value (p)_corr). Using said pressure correction value (p)_corr) Pressure (p) against BMP_BMP) Correction is performed and the final pressure-model value (p) is derived_MDL）。

The NVH operating mode is only activated if the delta pressure (Δ p), which is the difference between the MSP pressure and the pressure BMP, is less than a predefinable threshold value. The NVH operating mode is not required if the delta pressure (Δ p) is greater than the threshold and the armature moves slowly enough for reduced sound emissions.

Fig. 3 shows the actuation curve 203 in a further graph 200, wherein the actuation pattern 201 is shown as a function of the pressure 202. During the NVH operating mode is active and the system loads the pump with a partial actuation 204, for example a full actuation 205 at 1bar step (BMP) with a pulse time based on the stroke active in the last BMP, it is checked whether the delta pressure (Δ p) is less than the threshold value. If this is the case, the NVH mode of operation is activated or continued. A partial manipulation 204 is performed at this stage.

If full control 205 is performed after partial control 204, the pulse duration is determined on the basis of the pulse duration determined in the last stroke in which the BMP was active and from the confidence interval. This confidence interval is calculated from the system pressure and the saturation current. The following applies here:

wherein

Wherein t is_Impuls,_FAIs the pulse duration when the full control is performed, ti_BMP,n-1Is the duration of the pulse in the stroke valid in the last BMP, ti_confiIs the confidence interval, p is the system pressure, and I_satIs the saturation current.

Freezing pressure correction values (p) for pressure model calculations by means of software while the system is executing the full stroke _corr) Until the next full stroke.

The next stroke after the full stroke will be a partial stroke, wherein this stroke is based on the last partial-stroke-duration, and the pressure model calculates the pressure from BMP and the correction pressure (p) at the start time of the partial stroke_corr) Is determined on the basis of the last full stroke. The following applies here:

the calibration pressure is a function of the BMP and MSP pressures, while the pump implements the full stroke:

for the NVH mode of operation, the software utilizes two strategies for operating the transfer pump 81:

-calculating the pulse duration t for the partial steering_Impuls,PAIf the time 106 ti of the armature impact with partial actuation can be verified_MSP,PAThis is done with steps 3 and 4 in the following calculation steps, and

-calculating the pulse duration t for the partial steering_Impuls,PAIf the time 106 ti of the armature impact with partial actuation cannot be verified_MSP,PAThis is done with step 5 in the next calculation step.

The evaluation method comprises the following steps:

1. the first stroke should be a full stroke, and the pulse duration calculation is based on a pressure model and a saturation current

2. Calculating the delta pressure (Δ p) from the first stroke and freezing the correction pressure p for a further stroke_corrUsing this corrected pressure p_corrCalculating the pressure model for the additional stroke until the next full stroke:

3. performing a partial stroke if Δ p is less than said threshold

4. Is calculated on the basis of the following functionsPartially actuated pulse duration t_Impuls,PAIf the moment 106 ti of an armature impact with partial actuation is detected_MSP,PA：

Where Δ t_error,n-1Is the error-time difference and Δ t_PA,meas,nIs the measured time difference

5. Determining the time 106 ti for an armature impact with partial actuation_MSP,PAA target value for the time difference from the final instant of 205, which is derived according to the following formula:

6. moment 106 ti if no armature impact with partial actuation is detected_MSP,PABut Δ p is also always smaller than the defined threshold, an alternative partial maneuver 205 is activated, which is subject to the following conditions:

wherein

Wherein f is₁And f₂Is a factor which is generated on the one hand from the pressure difference at the start of the armature movement (BMP) and on the other hand from the model-stored difference for the saturation current

7. If the point in time 106 ti of an armature impact with partial actuation is detected once in the same pressure build-up cycle and is not detected any more afterwards_MSP,PAIt is provided here that the search algorithm is implemented anew. For this purpose, the pulses are applied on the basis of step 6Reset to a standard value and restart the retrieval algorithm. During the execution of the search algorithm, it should be ensured that the pulse times do not correspond to the pulse times for a full maneuver or that only an incomplete stroke results therefrom. This can be achieved by limiting the pulse duration on the one hand to a maximum time that can be derived from the last full stroke and on the other hand to a minimum time that can be derived from step 6.

Time 106 ti for detecting an armature impact with partial actuation_MSP,PAThe algorithm of numbers of (a) comprises at least the following steps:

1. recording a current coil current characteristic 104 in the NVH operating mode during a pump stroke;

2. extracting a coil current characteristic curve from a time when the manipulation is stopped until a time when the coil current is less than an applicable threshold value;

3. Filtering the signal;

4. mirroring the filtered signal;

5. forming a second derivative of the signal;

6. forming a sensed average of the output signal according to step 4;

7. filtering the output signal of the step 5;

8. the maximum value determination is made on the left side in the output signal of step 6. Performing a minimum determination on the right side of the output signal according to step 6 after the maximum determination;

9. calculating the difference between the maximum and minimum values from step 8 and saving the difference and retrieving the first maximum value on the right side of the output signal according to step 6;

10. if the next maximum point is greater than the last maximum point, retrieving the minimum point on the right side of the new maximum point;

11. calculating a difference between the new maximum value and the new minimum value;

12. if the new difference from step 11 is greater than the old difference from step 9, overwriting the old maximum with the new maximum and overwriting the old difference from step 9 with the new difference from step 11;

13. continuing the search for the complete curve from left to right and determining the maximum of the curves having the largest difference;

14. If this maximum value is greater than a predefinable threshold value and the difference is greater than this threshold value, the time 106 ti of the armature impact with partial actuation is detected for the partial stroke MSP-PA_MSP,PA；

15. The partial stroke MSP-PA indicates the time 106 ti of the armature impact with partial actuation_MSP,PA。

Claims

1. Method for operating an electric delivery pump (81) designed as a reciprocating diaphragm pump or a reciprocating piston pump, wherein, in order to execute a delivery stroke within a total cycle duration by means of a partial actuation (204), during an actuation phase, an actuation voltage is applied to a solenoid of the electric delivery pump (81) within a range of such a long pulse duration that an armature strike of the electric delivery pump (81) is achieved in a time interval (Δ t) after the actuation phase, and the time of the armature strike is determined by evaluating a current characteristic curve (103) of a coil current (101) flowing through the solenoid,

it is characterized in that the preparation method is characterized in that,

the duration of the time interval (Δ t) is predefined, and the end of the pulse duration is selected in such a way that the predefined time interval (Δ t) is observed.

2. The method of claim 1, wherein the step of treating the substrate,

it is characterized in that the preparation method is characterized in that,

detecting or determining the actual value (Δ t) of the time interval_{Practice of}) And the end of the pulse duration is adjusted by selection to a predefinable time interval (Δ t) that is delivered as the target value.

3. The method according to claim 1 or 2,

it is characterized in that the preparation method is characterized in that,

the predetermined time interval (Δ t) is determined in accordance with an optimization between the lowest possible noise emission and the most efficient possible transmission power.

4. The method according to claim 1 or 2,

it is characterized in that the preparation method is characterized in that,

the control voltage is supplied as a substantially constant direct voltage or as a pulse-width-modulated voltage.

5. The method according to claim 1 or 2,

it is characterized in that the preparation method is characterized in that,

if the moment of the armature impact is not detected from the current characteristic curve (103), the moment of the armature impact is calculated (106) in a partial actuation on the basis of the moment of time (107) for the start of the armature movement and on the basis of the time-based system pressure and saturation current on the basis of a model.

6. The method as set forth in claim 5, wherein,

it is characterized in that the preparation method is characterized in that,

A delta pressure (Δ p) is determined as the difference between the pressure during the impact of the armature and the pressure at the beginning of the armature movement, and the time (106) of the impact of the armature with the partial actuation is determined therefrom, and the operating mode with the partial actuation (204) is set on the basis thereof.

7. The method of claim 6, wherein the step of,

it is characterized in that the preparation method is characterized in that,

during the operation mode with the partial actuation (204) is active and the partial actuation (204) is applied to the electrical delivery pump (81), a full actuation (205) initiated in a specific pressure interval is carried out with a specific pulse time on the basis of the effective stroke determined in the last armature movement, wherein it is checked whether the delta pressure (Δ p) is less than an applicable threshold value and, if this is the case, the operation mode with the partial actuation (204) is continued.

8. The method as set forth in claim 5, wherein,

it is characterized in that the preparation method is characterized in that,

for operating modes with partial actuation (204), a distinction is made between the evaluation and the calculation of the pulse duration for the partial actuation (204), whether the time (106) of an armature impact with partial actuation can be ascertained from the current characteristic curve (103), on the basis of which different calculation strategies can then be used for adjusting the pulse duration.

9. The method according to claim 1 or 2,

characterized in that, for the purpose of detecting an armature impact with a partial actuation (204), a multi-stage numerical detection algorithm is used for determining the time of the armature impact with the partial actuation (204), said multi-stage numerical detection algorithm comprising at least in part the following steps:

i.) recording the current coil current characteristic curve during the pump stroke;

ii.) extracting a characteristic curve of the coil current from the time of the actuation cessation up to the time when the coil current is less than an applicable threshold value;

iii) filtering the signal according to step ii);

iv.) mirror the filtered signal;

v.) forming a second derivative of the signal;

vi.) forming a sensed average of the output signals according to step iv);

vii.) filtering the output signal according to step v.);

x.) check if the next maximum point is greater than the last maximum point, and, if this condition is met, then retrieve the minimum point on the right side of the new maximum point;

xi.) calculating the difference between the new maximum and the new minimum;

xiv.) checks whether this maximum value is greater than a predefinable threshold value and whether the difference is greater than this threshold value, and, if this condition is fulfilled, identifies the impact time for the partial maneuver and

xv.) indicates the impact time.

10. Use of a method according to one of the preceding claims 1 to 9 for operating an electric delivery pump (81) designed as a reciprocating diaphragm pump or a reciprocating piston pump, wherein the method is used for operating an electrotransport pump (81) in a dosing system (60), wherein the dosing system is formed by a dosing unit (80) having an electric delivery pump (81) and an injection unit (70) having a dosing valve (71), wherein, during high-load operation of an internal combustion engine (1) designed as a diesel motor, hydrocarbons in the form of diesel fuel are introduced into the exhaust gas duct (30) in the flow direction of the exhaust gas upstream of the nitrogen oxide storage catalyst for nitrogen oxide reduction, or the dosing system is used to dose an aqueous urea solution for reducing nitrogen oxides in the flow direction of the exhaust gas upstream of the SCR catalyst (40).

11. Device for operating an electric delivery pump (81) designed as a reciprocating piston pump or a reciprocating diaphragm pump, wherein the solenoid coils of the electric delivery pump (81) can be actuated with a voltage signal in an actuation phase within a total cycle duration up to the next actuation, and the movement of the armature of the electric delivery pump (81) can be evaluated by evaluating a current characteristic curve (103) of the coil current (101) flowing through the solenoid coils, and wherein the actuation of the solenoid coils can be interrupted in advance at least temporarily during the stroke in order to suppress noise, in order to thereby cause a reduction in the speed of the armature before striking into the final position of the armature, characterized in that the device for operating the electric delivery pump (81) comprises a device for operating an electric delivery pump designed as a reciprocating diaphragm pump or a reciprocating piston pump according to one of claims 1 to 9 (81) The method of (1).

12. The device according to claim 11, characterized in that said device is a control unit (91).

13. The device according to claim 11, characterized in that the means are means for current characteristic curve analysis of the coil current (101).