CN102817735B - The method for correcting of rail pressure feedforward control amount and device in a kind of high pressure co-rail system - Google Patents

Abstract

The invention discloses a method and device for correcting rail pressure feed-forward control in a high-pressure common rail system. Point and the rail pressure value at the end point of the rail pressure drop, calculate the pressure difference value of the rail pressure transient signal; according to the pressure difference value of the rail pressure transient signal, calculate the actual required feedforward control through the preset corresponding relationship Quantity; judge whether the actual required feedforward control quantity is equal to the current feedforward control quantity under the steady-state working condition in the high-pressure common rail system, if not, use the actual required feedforward control quantity to The current feedforward control quantity is corrected to obtain the corrected feedforward control quantity. The invention corrects the feedforward control amount according to the actual fuel consumption of the system, so that the corrected feedforward control amount can follow the change of the actual fuel consumption, thereby realizing fast and accurate control of the rail pressure.

Description

Method and device for correcting rail pressure feed-forward control quantity in high-pressure common rail system

technical field

The invention relates to the field of electronically controlled high-voltage common rail systems, in particular to a correction method and device for rail pressure feedforward control quantities in the high-voltage common rail system.

Background technique

Due to the increasingly serious environmental pollution caused by engine exhaust, countries all over the world have begun to take effective technical measures to reduce and control the emission of pollutants. As a relatively successful new technology for controlling pollution emissions, common rail electronically controlled fuel injection technology has begun to be applied to various engines.

The current electronically controlled high-pressure common rail system mainly includes four major components: electronically controlled high-pressure oil pump, common rail pipe, electronically controlled fuel injector and ECU. Among them, the electronically controlled high-pressure oil pump can use the oil metering unit to control the pump oil flow, thereby controlling the pressure in the common rail pipe. The pressure in the common rail pipe is called rail pressure. In the current electronically controlled high-pressure common rail system, the control of the rail pressure is a closed-loop control realized by signal feedback from the pressure sensor on the common rail pipe, and the output of the control is the sum of the PID control value and the feedforward control value. As shown in Figure 1, the pressure sensor on the common rail pipe provides a feedback signal, and the PID control quantity of the rail pressure is obtained according to the feedback signal; at the same time, because the PID control quantity has a certain delay in the control of the rail pressure, in order to increase the rail pressure The system provides a pre-set feed-forward control amount according to the engine operating conditions. Finally, the PID control quantity and the feed-forward control quantity are summed to obtain the final closed-loop control quantity of the rail pressure, and the final control quantity is used to control the rail pressure.

However, with the aging of the electronically controlled high-pressure common rail system, the fuel injection hole and the oil return hole will become larger, and the actual fuel consumption will increase under the same working conditions. In addition, as the engine running time increases, due to the use of more or less impurities in the oil, the pipes and oil holes of the system may be partially blocked, resulting in changes in the actual fuel consumption. However, in the prior art, the feedforward control amount is preset according to the working conditions. Therefore, when the actual fuel consumption under the same working condition changes due to system aging or blockage, the effect of the feedforward control amount on the rail pressure The control cannot respond quickly to the change of actual fuel consumption, so that the system cannot quickly and accurately control the rail pressure.

Contents of the invention

The problem to be solved by the present invention is to provide a method and device for correcting the rail pressure feedforward control amount of the high-pressure common rail system, so as to overcome the problem that the feedforward control amount of the high-pressure common rail system cannot be shifted after the aging of the high-voltage common rail system in the prior art Rail pressure control is unstable and inaccurate.

In order to achieve the above object, the present invention provides a method for correcting the rail pressure feed-forward control amount of a high-pressure common rail system, the method comprising the following steps:

Step A: Calculate and obtain the pressure difference value of the rail pressure transient signal according to the collected rail pressure values of the rail pressure drop start point and the rail pressure drop end point of the high-pressure common rail system under steady-state working conditions;

Step B: According to the pressure difference value of the rail pressure transient signal, the actual required feedforward control amount is calculated through the preset corresponding relationship;

Step C: judging whether the actual required feed-forward control amount is equal to the current feed-forward control amount under the steady-state working condition in the high-pressure common rail system, and if not, go to step D;

Step D: Correcting the current feedforward control quantity with the actual required feedforward control quantity to obtain a corrected feedforward control quantity.

Preferably, said step A includes:

Step A11, reading the rail pressure values of multiple rail pressure drop start points and the rail pressure drop end points corresponding to each rail pressure drop start point of the high-pressure common rail system;

Step A12, calculating the average value of the rail pressure values at the rail pressure drop start points of the multiple rail pressure drop start points, and the average value of the rail pressure values at the rail pressure drop end points of the multiple rail pressure drop end points;

Step A13, making a difference between the average value of the rail pressure value at the start point of the rail pressure drop and the average value of the rail pressure value at the end point of the rail pressure drop, and taking the difference obtained by making the difference as the pressure difference of the transient signal of the rail pressure value.

Preferably, said step A includes:

Step A21, reading the rail pressure values of multiple rail pressure drop start points and rail pressure drop end points corresponding to each rail pressure drop start point of the high-pressure common rail system;

Step A22, calculating the difference between the rail pressure value at each rail pressure drop start point and the rail pressure drop end point corresponding to the rail pressure drop start point;

Step A23, calculating the average value of the difference obtained in step A22, and using the average value of the difference as the pressure difference value of the rail pressure transient signal.

Preferably, the preset corresponding relationship is a physical model; the physical model is:

$\mathrm{<span\; class="notranslate">\; Q</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; wxya</span>}}{\mathrm{<span\; class="notranslate">\; 120</span>}\mathrm{<span\; class="notranslate">\; \&beta;</span>}}\mathrm{<span\; class="notranslate">\; \&Delta;P</span>}<span\; class="notranslate">\; ;</span>$

In the physical model, Q is the actual required feedforward control quantity, n is the engine speed, v is the volume of the common rail pipe, ΔP is the pressure difference value of the rail pressure transient signal, and β is the elastic modulus of the oil in the common rail pipe .

Preferably, the step D is specifically:

Replace the value of the current feedforward control quantity with the value of the actual required feedforward control quantity to obtain the corrected feedforward correction quantity.

Preferably, the step D is specifically:

Calculate the difference between the actual required feedforward control quantity and the current feedforward control quantity, and add the difference to the current feedforward control quantity to obtain the corrected feedforward control quantity.

Preferably, the current feed-forward control amount is stored in the calibration two-dimensional table MAP, and the step D of adding the difference to the current feed-forward control amount is specifically:

Adding the difference to the modified two-dimensional table MAP in the high-pressure common rail system;

The difference in the modified two-dimensional table MAP is added to the corresponding current feedforward control amount in the calibration two-dimensional table MAP.

Preferably, after the step D, the method further includes: saving the modified two-dimensional table MAP into an EEPROM in the high-voltage common rail system after power-off.

The present invention also provides a correction device for rail pressure feedforward control quantity in a high-pressure common rail system. The device includes a differential pressure value extraction module, an actual required feedforward control quantity calculation module, a judgment module and a correction module;

The pressure difference value extraction module is used to calculate and obtain the rail pressure transient signal according to the collected rail pressure values of the rail pressure drop start point and the rail pressure drop end point of the high-voltage common rail system under steady-state working conditions differential pressure value;

The actual required calculation control quantity calculation module is used to calculate the actual required feedforward control quantity according to the pressure difference value of the rail pressure transient signal through a preset correspondence relationship;

The judging module is used to judge whether the actual required feedforward control quantity is equal to the current feedforward control quantity of the steady-state working condition in the high-pressure common rail system, and if not, send the judgment result to the correction module ;

The correction module is configured to correct the current feedforward control quantity with the actual required feedforward control quantity according to the received judgment result, so as to obtain the corrected feedforward control quantity.

Preferably, the differential pressure value extraction module includes:

The rail pressure value extraction sub-module is used to read the rail pressure values of multiple rail pressure drop start points and each rail pressure drop start point corresponding to the rail pressure drop end point of the high-voltage common rail system;

The rail pressure value average calculation sub-module is used to calculate the average value of the rail pressure drop start points of the multiple rail pressure drop start points, and the rail pressure drop end point of the multiple rail pressure drop end points The average value of point rail pressure;

The first differential pressure value calculation sub-module is used to make a difference between the average value of the rail pressure value at the start point of the rail pressure drop and the average value of the rail pressure value at the end point of the rail pressure drop, and use the difference obtained by making the difference as the The differential pressure value of the rail pressure transient signal.

Preferably, the differential pressure value extraction module includes:

The rail pressure value extraction sub-module is used to read the rail pressure values of multiple rail pressure drop start points and each rail pressure drop start point corresponding to the rail pressure drop end point of the high-voltage common rail system;

The second differential pressure value calculation sub-module is used to calculate the difference between the rail pressure value at each rail pressure drop start point and the rail pressure drop end point corresponding to the rail pressure drop start point;

The differential pressure value average calculation sub-module is used to calculate the average value of the difference obtained by the rail pressure difference calculation module, and use the average value of the difference as the differential pressure value of the rail pressure transient signal.

Preferably, the actual required feedforward control quantity calculation module includes an actual required feedforward control quantity calculation submodule and an acquisition submodule, wherein,

The obtaining sub-module is used to obtain a pre-established physical model as the preset correspondence; the physical model is:

$\mathrm{<span\; class="notranslate">\; Q</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; wxya</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; \&Delta;P</span>}}{\mathrm{<span\; class="notranslate">\; 120</span>}\mathrm{<span\; class="notranslate">\; \&beta;</span>}}<span\; class="notranslate">\; ;</span>$

In the physical model, Q is the actual required feedforward control quantity, n is the engine speed, v is the volume of the common rail pipe, ΔP is the pressure difference value of the rail pressure transient signal, and β is the elastic modulus of the oil in the common rail pipe ;

The actual required feedforward control quantity calculation sub-module is used to calculate the actual required feedforward control quantity according to the physical model and the pressure difference value of the rail pressure transient signal.

Preferably, the correction module is specifically configured to replace the value of the current feedforward control quantity with the value of the actual required feedforward control quantity to obtain the corrected feedforward correction quantity.

Preferably, the correction module includes:

The calculation difference sub-module is used to calculate the difference between the actual required feedforward control quantity and the current feedforward control quantity;

The correction processing sub-module is used to add the difference to the current feedforward control quantity to obtain the corrected feedforward control quantity.

Preferably, the device also includes a calibration two-dimensional table MAP module, which is used to save the current feedforward control amount in the calibration two-dimensional table MAP; the correction processing submodule includes:

The modified two-dimensional table MAP submodule is used to add the difference to the modified two-dimensional table MAP in the high-pressure common rail system;

The addition calculation sub-module is used to add the difference in the modified two-dimensional table MAP to the corresponding current feedforward control quantity in the calibration two-dimensional table MAP to obtain the corrected feedforward control quantity.

Preferably, the device further includes a storage module, configured to store the modified two-dimensional table MAP in an EEPROM in the high voltage common rail system when the power is off.

Compared with the prior art, the present invention has the following advantages:

According to the technical solution of the present invention, the pressure difference value of the transient signal of the rail pressure is calculated by reading the rail pressure values at the start point of the rail pressure drop and the end point of the rail pressure drop under the steady-state working condition in the high-pressure common rail system , and then calculate the actual required feedforward control quantity through the preset corresponding relationship according to the differential pressure value, and finally use the calculated actual required feedforward control quantity to correct the current feedforward control quantity of the corresponding working condition. In this way, the feed-forward control quantity used for rapid response to rail pressure control in the high-pressure common rail system is no longer only preset according to the working conditions, because the pressure difference value of the transient signal of the rail pressure under the steady-state working conditions can reflect the In the actual fuel consumption situation, the feed-forward control amount of the high-pressure common rail system can be corrected according to the actual required feed-forward control amount calculated from the pressure difference value of the rail pressure transient signal under the same working conditions. In this way, The corrected feed-forward control amount can be offset accordingly according to the actual fuel injection situation of the engine. Therefore, when the actual fuel consumption under the same working conditions changes due to the aging or blockage of the high-pressure common rail system, the measured differential pressure value of the rail pressure transient signal changes accordingly, and then the actual required fuel consumption is calculated. The feedforward control quantity changes and the current feedforward control quantity of the high-pressure common rail system is corrected, so that the revised feedforward control quantity can follow the change of the actual fuel consumption, thereby realizing rapid and accurate control of the rail pressure.

Description of drawings

Fig. 1 is a schematic diagram of rail pressure control in a medium-high pressure common rail system in the prior art;

Fig. 2 is the basic flow chart of an embodiment of the feedforward control variable correction method in the high pressure common rail system of the present invention;

Fig. 3 is a schematic diagram of rail pressure values collected under stable working conditions in a specific embodiment of the present invention;

Fig. 4 is the flow chart of another specific embodiment of the feedforward control variable correction method in the high pressure common rail system of the present invention;

Fig. 5 is a structural diagram of an embodiment of the feedforward control variable correction device of the high pressure common rail system of the present invention;

Fig. 6 is a structural diagram of the differential pressure value extraction module in the feedforward control variable correction device of the high-pressure common rail system of the present invention;

Fig. 7 is another structural diagram of the pressure difference value extraction module in the feedforward control variable correction device of the high-pressure common rail system of the present invention;

Fig. 8 is a structural diagram of the actual required feedforward control quantity calculation module in the feedforward control quantity correction device of the high pressure common rail system of the present invention;

Fig. 9 is a structural diagram of the correction module in the feedforward control quantity correction device of the high-pressure common rail system of the present invention;

Fig. 10 is a structural diagram of another embodiment of the feedforward control variable correction device of the high pressure common rail system of the present invention.

Detailed ways

Below we will describe in detail the best implementation of the present invention with reference to the accompanying drawings. First of all, it should be pointed out that the meanings of the terms, words and claims used in the present invention should not be limited to their literal and ordinary meanings, but also include meanings and concepts that are consistent with the technology of the present invention. This is because It is up to us, as inventors, to define terms appropriately in order to best describe our inventions. Therefore, the configurations given in this specification and the accompanying drawings are only preferred implementations of the present invention, rather than enumerating all technical characteristics of the present invention. We need to recognize that there are various equivalents or modifications that could replace ours.

The basic flow of an embodiment of the method for correcting the rail pressure feedforward control amount in the high-pressure common rail system of the present invention is shown in Figure 2, including the following steps:

Step S101, according to the collected rail pressure values of the rail pressure drop start point and the rail pressure drop end point of the high-pressure common rail system under steady-state conditions, calculate the pressure difference value of the rail pressure transient signal:

In this embodiment, for the high-pressure common rail system, since the rail pressure feed-forward control amount is based on the operating conditions of the engine to adjust the rail pressure, only when the engine is in a steady It is only meaningful to correct the rail pressure feed-forward control amount based on the actual fuel consumption of the rail system. Therefore, the present invention is to collect rail pressure values under stable working conditions. The acquisition of the rail pressure value is realized through the pressure sensor on the common rail pipe of the high pressure common rail system. The start point of rail pressure drop refers to the time point when the electronically controlled injector starts fuel injection; the end point of rail pressure drop refers to the time point when the electronically controlled injector ends fuel injection. In the schematic diagram of the rail pressure value under stable working conditions as shown in Figure 3, the waveform in the figure is cyclical, and one working cycle time of the system corresponds to one cycle of the waveform. In the first waveform cycle in Fig. 3, the rail pressure dropped sharply after point 201, and the rail pressure did not stop falling until point 206 and began to rise. It can be seen from this that the fuel injector starts to inject fuel at point 201, so the rail pressure drops sharply, and the fuel injector stops fuel injection at point 206, and the rail pressure begins to rise after point 206. Similarly, it can be seen that in FIG. 3 , the rail pressure drop start points are from point 201 to point 205 , and the rail pressure drop end points are from point 206 to point 210 respectively.

In order to facilitate those skilled in the art to have a clearer understanding of this step, this step will be described in detail below. In this step, when collecting the rail pressure values of the rail pressure drop start point and the rail pressure drop end point of the high-pressure common rail system under steady-state conditions, there are two ways to determine the rail pressure drop start point and the rail pressure drop end point. A specific embodiment.

The first implementation method of collecting rail pressure values is to pre-set the time points of the rail pressure drop start point and the rail pressure drop end point to determine the rail pressure drop start point and the rail pressure drop end point. The specific steps are as follows: The corresponding relationship between rail pressure and time, pre-set the time points corresponding to the start point of rail pressure drop and the end point of rail pressure drop to be collected, and then read the rail pressure value at the preset time point during system operation Get out the rail pressure value as the starting point of rail pressure drop or the end point of rail pressure drop corresponding to this point.

The second way to collect rail pressure values is to use the functional relationship between rail pressure and time to determine the rail pressure drop start point and rail pressure drop end point through the derivatives of rail pressure at each point. The specific process is: through the pressure sensor in N times During the fuel injection process, a rail pressure value is collected and stored at regular intervals, and then the derivatives of the stored rail pressure values at each point are calculated, and the rail pressure values of the first M points among the corresponding points whose derivatives are less than a certain value during each fuel injection process are calculated. The average value is taken as the rail pressure value at the start point of the rail pressure drop, and the rail pressure value at the corresponding point where the first derivative after the rail pressure drop point is positive is taken as the rail pressure value at the end point of the rail pressure drop.

It should be noted that in step S101, after collecting the rail pressure values of the rail pressure drop start point and the rail pressure drop end point under stable working conditions, only one rail pressure drop start point and one rail pressure drop end point can be used. The pressure difference value of the transient signal of the rail pressure can be calculated by the rail pressure value of each point, and the rail pressure can also be calculated by the rail pressure value of the rail pressure drop end point corresponding to the rail pressure drop start point and each rail pressure drop start point The dropout value of the transient signal.

In addition, the present invention also provides the following two preferred methods for calculating the differential pressure value of the rail pressure transient signal through multiple rail pressure drop start points and rail pressure drop end points corresponding to each rail pressure drop start point Detailed ways.

The first implementation method of calculating the pressure difference value at multiple points is to first calculate the average value of the rail pressure value at the start point of the rail pressure drop and the average value of the rail pressure value at the end point of the rail pressure drop, and then make a difference between the two average values to obtain the pressure difference. The difference, the specific process is: read the rail pressure values of the multiple rail pressure drop start points of the high-pressure common rail system and the rail pressure drop end points corresponding to each rail pressure drop start point; calculate the multiple rail pressure drop The average value of the rail pressure drop start point rail pressure value at the drop start point, and the average value of the rail pressure drop end point rail pressure values at the rail pressure drop end points of the plurality of rail pressure drop end points; the rail pressure drop start point rail pressure The difference between the average value of the value and the average value of the rail pressure value at the end point of the rail pressure drop is made, and the difference obtained by doing the difference is used as the pressure difference value of the rail pressure transient signal.

The second way to calculate the pressure difference value at multiple points is to firstly make a difference between the rail pressure value at the start point of each rail pressure drop and the rail pressure value at the end point of the rail pressure drop corresponding to the start point to obtain the difference, and then use all the differences The average value of the value is used as the pressure difference value. The specific process is: read the rail pressure value of the multiple rail pressure drop start points of the high-pressure common rail system and the rail pressure drop end point corresponding to each rail pressure drop start point; The difference between the rail pressure value at each rail pressure drop start point and the rail pressure drop end point corresponding to the rail pressure drop start point; calculate the average value of the difference, and calculate the difference The average value is used as the pressure difference value of the rail pressure transient signal.

After step S101 is executed, proceed to step S102, and calculate the actual required feedforward control amount through the preset corresponding relationship according to the differential pressure value of the rail pressure transient signal:

The pressure difference value of the rail pressure transient signal is actually the difference value of the rail pressure drop in the common rail pipe during the fuel injection process of the electronically controlled injector. According to the pressure difference value representing the rail pressure transient signal during the fuel injection process, using the physical parameters of the engine, the sum of the fuel injection volume and the fuel return volume under the current steady-state working condition can be deduced, that is, the high-pressure common rail The actual fuel consumption required by the system. This fuel consumption is the feed-forward control amount actually required by the high-pressure common rail system. The deduced relationship between the actual required feedforward control quantity and the pressure difference value of the rail pressure transient signal is the corresponding relationship between the two.

In this embodiment, the preset corresponding relationship can be set by those skilled in the art according to actual scenarios and requirements. The present invention provides a physical model as an example of the aforementioned corresponding relationship. The physical model is:

$\mathrm{<span\; class="notranslate">\; Q</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; wxya</span>}<span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; \&Delta;P</span>}}{\mathrm{<span\; class="notranslate">\; 120</span>}\mathrm{<span\; class="notranslate">\; \&beta;</span>}}<span\; class="notranslate">\; ;</span>$

In the physical model, Q is the actual required feedforward control quantity, n is the engine speed, v is the volume of the common rail pipe, ΔP is the pressure difference value of the rail pressure transient signal, and β is the elastic modulus of the oil in the common rail pipe .

In addition, in order for those skilled in the art to have a clearer understanding of this physical model, the specific derivation process for the physical model between the pressure difference value and the actual required feedforward control value is as follows:

According to the hydraulic continuity equation, there is the internal pressure of the common rail:

Where P is the pressure of the common rail pipe, β is the modulus of elasticity, v is the volume of the common rail pipe, Q _{oil supply} is the oil supply flow rate of the high-pressure oil pump, Q _{fuel injection} is the fuel injection flow rate, and Q _dynamic is the dynamic leakage during fuel injection, _QStatic is the static leakage of the injector.

The fuel supply flow is 0 during the injection process, and the static leakage is negligible during the fuel injection process, then:

Integrating both sides of the above equation and sorting out:

Among them, V _injection and V _dynamic are the actual injection volume and actual dynamic leakage volume in one injection process, respectively.

Since the flow in the feedforward is continuous flow, V _injection and V _dynamic are converted into feedforward flow:

Among them, Q is the actual required feed-forward control amount converted according to the actual fuel consumption, ΔP is the pressure difference value of the rail pressure transient signal, n is the engine speed, and N is the number of engine cylinders.

After the actual required feedforward control quantity is calculated in step S102, enter step S103 to judge whether the actual required feedforward control quantity is equal to the current feedforward control quantity of the steady-state working condition in the high pressure common rail system, if If they are not equal, go to step S104:

The actual required feedforward control quantity obtained in step S102 is compared with the current feedforward control quantity of the high pressure common rail system corresponding to the stable working condition in step S101. If the actual required feedforward control amount is not equal to the current feedforward control amount, go to step S104 for correction. If the actual required feedforward control amount is equal to the current feedforward control amount, it may go to step S104 for correction, or the current feedforward control amount may not be corrected.

Step S104, correcting the current feedforward control quantity with the actual required feedforward control quantity to obtain the corrected feedforward control quantity:

If the judging result in step S103 is not equal, the value of the current feedforward control quantity is corrected by the value of the actual required feedforward control quantity, so as to obtain the corrected feedforward control quantity.

Similarly, for step S104, this embodiment also provides two preferred implementation manners of modifying the current feed-forward control amount.

The first implementation manner of modifying the current feedforward control quantity is to replace the value of the current feedforward control quantity with the value of the actual required feedforward control quantity to obtain the corrected feedforward control quantity. In the embodiment of the present invention, the current feedforward control quantity is stored in the calibration two-dimensional table MAP, for example, the value of the current feedforward control quantity in the calibration two-dimensional table MAP in the system can be directly replaced with the actual required feedforward control quantity The value of is used as the modified feed-forward control amount. When the system invokes the feedforward control quantity, the value of the current feedforward control quantity can be directly extracted from the calibration two-dimensional table MAP.

The second method of modifying the current feedforward control amount is to calculate the difference between the actual required feedforward control amount and the current feedforward control amount, and add the difference to the current feedforward control amount to obtain the corrected current Feedforward control amount. For example, the difference between the actual required feedforward control amount and the current feedforward control amount can be added to the modified two-dimensional table MAP in the high-pressure common rail system, which is different from the previous calibration two-dimensional table; when no addition is required, the correction The corresponding difference value of the two-dimensional table is marked with 0. When the system invokes the feed-forward control value, the difference between the modified two-dimensional table MAP and the current feed-forward control value corresponding to the difference in the system's calibration two-dimensional table MAP can be added and summed as the corrected feed-forward Controls the volume fetch call. This implementation is mainly for the convenience of the staff to observe the correction of the actual required feedforward control quantity to the current feedforward control quantity.

It can be understood that, in order to call the feedforward control quantity conveniently and quickly, after the difference between the actual required feedforward control quantity and the current feedforward control quantity is added to the modified two-dimensional table MAP in the high-pressure common rail system, the The modified two-dimensional table MAP is saved to the electrically erasable programmable read-only memory (EEPROM) of the high-voltage common rail system when the power is off. In this way, the high-pressure common rail system does not need to calculate the actual required feedforward control quantity according to the pressure difference value every time the feedforward control quantity is called to control the rail pressure, but only needs to extract the corresponding stored correction results according to the current working conditions That's it.

In addition, besides calculating the actual required feedforward control amount according to the pressure difference value, the correction of the feedforward control amount can also be realized not according to the pressure difference value. For example, the correction value corresponding to the running time may be preset according to the running time of the engine. When the system uses the feed-forward control value to control the rail pressure, the corresponding correction value is transferred according to the engine running time to control the rail pressure.

In this embodiment, the feed-forward control amount used for rapid response to rail pressure control in the high-pressure common rail system is no longer only preset according to the working condition, because the pressure difference of the transient signal of the rail pressure under the steady-state working condition The value can reflect the actual fuel consumption of the engine, and the feed-forward control amount of the high-pressure common rail system can be adjusted according to the actual required feed-forward control amount calculated from the pressure difference value of the rail pressure transient signal under the same working conditions. In this way, the corrected feed-forward control amount can be offset accordingly according to the actual fuel injection situation of the engine. Therefore, when the actual fuel consumption under the same working conditions changes due to the aging or blockage of the high-pressure common rail system, the measured differential pressure value of the rail pressure transient The feedforward control quantity changes and the current feedforward control quantity of the high-pressure common rail system is corrected, so that the revised feedforward control quantity can quickly follow the change of the actual fuel consumption, thereby realizing rapid and accurate control of the rail pressure . Next, step S101 adopts the second embodiment of collecting rail pressure values and the second embodiment of multiple point calculation of differential pressure values, and step S104 adopts the second embodiment of correcting the current feedforward control value and other steps mentioned above In the preferred implementation mode, the specific implementation mode of the technical solution of the present invention will be further described in detail in combination with the flow chart of the embodiment shown in FIG. 4 .

Referring to Fig. 4, it is a flow chart of another embodiment of the correction method of the rail pressure feedforward control quantity in the high pressure common rail system of the present invention. This embodiment may specifically include:

Step S401 , judging that it is enabled and that the engine is in a stable working condition: it is judged whether the engine is in a stable working condition, and if so, go to step S402 . If not, continue to step S401, and wait for a stable working condition to be reached. Judging whether the engine is in a stable working condition belongs to the prior art and will not be repeated here.

Step S402 , collect and store the rail pressure values of N working cycles: the time from when the fuel injector starts to inject fuel in one fuel injection process to when the fuel injector starts to inject fuel in the next fuel injection process is a working cycle time. In the continuous N working cycle times, the rail pressure value corresponding to the time point is read every once in a while, and after the N working cycles are completed, the rail pressure values at all read time points are collected and stored.

Step S403. Read the rail pressure values at the start point and the end point of rail pressure drop: calculate the derivative of the collected rail pressure values at each point, and count the first M rail pressure values whose derivatives are less than a certain value in each working cycle The average value of the rail pressure value at the time point is taken as the rail pressure value at the beginning point of the rail pressure drop in the working cycle; The pressure value is used as the rail pressure value at the end point of the rail pressure drop.

Step S404, calculate the differential pressure value of the rail pressure transient signal: take the average value of the obtained N rail pressure drop start points, and then take the average value of the obtained N rail pressure drop end points, and then combine the two The average value is made difference, and the obtained difference is the pressure difference value of the rail pressure transient signal.

Step S405, calculating the actual required feedforward control amount: according to the pressure difference value of the rail pressure transient signal, using a physical model to calculate the actual required feedforward control amount; the physical model is as follows:

$\mathrm{<span\; class="notranslate">\; Q</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; wxya</span>}<span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; \&Delta;P</span>}}{\mathrm{<span\; class="notranslate">\; 120</span>}\mathrm{<span\; class="notranslate">\; \&beta;</span>}}<span\; class="notranslate">\; ;</span>$

In the physical model, Q is the actual required feedforward control quantity, n is the engine speed, v is the volume of the common rail pipe, △P is the pressure difference value of the transient signal of the rail pressure, and β is the elastic modulus of the oil in the common rail pipe quantity.

Step S406, judging whether the actual required feed-forward control amount is equal to the current feed-forward control amount of the system: if the judgment result is no, go to step S407; if the judgment result is yes, go to step S408.

Step S407 , correcting the current feedforward control amount: calculating the difference between the actual required feedforward control amount and the current feedforward control amount, and using the difference as a correction result to correct the current feedforward control amount.

Step S408 , not correcting the current feedforward control quantity of the system: correcting the current feedforward control quantity with zero as the correction result, so as to realize not correcting the current feedforward control quantity.

Step S409, adding the correction result to the correction MAP: adding the correction result obtained in step S407 and/or step S408 to the correction MAP preset in the system corresponding to the working conditions described in step S401. After the adding is completed, go to step S410. If the current system needs to call the feedforward control amount to control the rail pressure at this time, it can directly enter step S411 without going through step S410.

Step S410, saving the revised MAP at power failure: saving the revised MAP obtained in step S409 to the EEPROM upon power failure.

Step S411, the system calls the feedforward control amount to control the rail pressure: the system calls the corrected difference corresponding to the current working condition in the corrected MAP in step S409 or step S410, and the value in the MAP originally calibrated by the system for the feedforward control amount The uncorrected current feed-forward control value is summed and output as the feed-forward control value to control the rail pressure.

In this embodiment, when the high-pressure common rail system uses the feedforward control quantity to control the rail pressure, it can also correct the feedforward control quantity according to the actual fuel consumption of the engine, so as to realize the feedforward control quantity of the rail pressure control Rapid response to rail pressure changes, fast and accurate control of rail pressure. In addition, this embodiment utilizes the derivative of the rail pressure value to determine the rail pressure values at the start point and the end point of the rail pressure drop, so that the determination of the rail pressure value is more accurate. Moreover, in this embodiment, instead of directly replacing the current feedforward control quantity with the actual required feedforward control quantity, the difference between the two is made, and the difference value and the current feedforward control quantity preset by the system are stored in different Two-dimensional table MAP. In this way, it is convenient for technicians to monitor the correction of the feed-forward control quantity by the system at any time, so as to know the change of the actual fuel injection situation of the engine.

In order to correspond to the method embodiment of the present invention, the present invention also provides a correction device for the feed-forward control amount of the rail pressure in the high-pressure common rail system, as shown in Figure 5, which is an embodiment of the correction device provided by the present invention The structural diagram of this embodiment may include a differential pressure value extraction module 501, an actual required feedforward control amount calculation module 502, a judgment module 503 and a correction module 504;

The pressure difference value extraction module 501 is used to calculate the rail pressure transient state according to the collected rail pressure values of the rail pressure drop start point and the rail pressure drop end point of the high-pressure common rail system under steady-state conditions The differential pressure value of the signal;

The actual required calculation control quantity calculation module 502 is used to calculate and obtain the actual required feedforward control quantity according to the pressure difference value of the rail pressure transient signal through the corresponding relationship;

The judging module 503 is used to judge whether the actual required feed-forward control amount is equal to the current feed-forward control amount of the steady-state working condition in the high-pressure common rail system, and if not, send the judgment result to the correction module 504;

The correction module 504 is configured to correct the current feedforward control quantity with the actual required feedforward control quantity according to the received judgment result, so as to obtain a corrected feedforward control quantity.

Corresponding to the two method embodiments of collecting rail pressure values in the present invention, the present invention provides two device embodiments of the differential pressure value extraction module 501 , as shown in FIG. 6 and FIG. 7 .

Fig. 6 is a kind of structural diagram of differential pressure value extraction module 501, the differential pressure value extraction module 501 as shown in Fig. 6, comprises:

The rail pressure value extraction sub-module 601 is used to read the rail pressure values of multiple rail pressure drop start points and each rail pressure drop start point corresponding to the rail pressure drop end point of the high-voltage common rail system;

The rail pressure value average calculation sub-module 602 is used to calculate the average value of the rail pressure drop start points at the multiple rail pressure drop start points, and the rail pressure drop at the multiple rail pressure drop end points The average value of the rail pressure at the end point;

The first differential pressure value calculation sub-module 603 is used to make a difference between the average value of the rail pressure value at the start point of the rail pressure drop and the average value of the rail pressure value at the end point of the rail pressure drop, and use the difference obtained as the difference The differential pressure value of the rail pressure transient signal.

As shown in Fig. 7, another structure diagram of differential pressure value extraction module 501, the differential pressure value extraction module 501 may include:

The rail pressure value extraction sub-module 601 is used to read the rail pressure values of multiple rail pressure drop start points and each rail pressure drop start point corresponding to the rail pressure drop end point of the high-voltage common rail system;

The second differential pressure value calculation sub-module 701 is used to calculate the difference between the rail pressure value at each rail pressure drop start point and the rail pressure drop end point corresponding to the rail pressure drop start point;

The average pressure difference calculation sub-module 702 is used to calculate the average value of the difference obtained by the rail pressure difference calculation module, and use the average value of the difference as the pressure difference value of the rail pressure transient signal.

Corresponding to the method embodiment of the present invention, a physical model is provided as the corresponding relationship between the pressure difference value of the rail pressure transient signal and the actual required feedforward control quantity, and the present invention provides another calculation method for the actual required feedforward control quantity A device embodiment of the module 502 is shown in FIG. 8 . Fig. 8 is a structural diagram of the actual required feedforward control quantity calculation module 502, and the actual required feedforward control quantity calculation module 502 includes an acquisition submodule 801 and an actual required feedforward control quantity calculation submodule 802:

The obtaining sub-module 801 is used to obtain a pre-established physical model as the preset correspondence; the physical model is:

$\mathrm{<span\; class="notranslate">\; Q</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; wxya</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; \&Delta;P</span>}}{\mathrm{<span\; class="notranslate">\; 120</span>}\mathrm{<span\; class="notranslate">\; \&beta;</span>}}<span\; class="notranslate">\; ;</span>$

In the physical model, Q is the actual required feedforward control quantity, n is the engine speed, v is the volume of the common rail pipe, ΔP is the pressure difference value of the rail pressure transient signal, and β is the elastic modulus of the oil in the common rail pipe ;

The actual required feedforward control quantity calculation sub-module 802 is used to calculate the actual required feedforward control quantity according to the physical model and the pressure difference value of the rail pressure transient signal.

Corresponding to the two correction mode embodiments of the method of the present invention, the present invention provides two device embodiments of the correction module 504 .

The first type of correction module 504 is specifically configured to replace the value of the current feedforward control quantity with the value of the actual required feedforward control quantity to obtain a corrected feedforward correction quantity.

The structure diagram of the device embodiment of the second correction module 504 is shown in FIG. 9 . The correction module 504 includes:

Calculating difference sub-module 901, used to calculate the difference between the actual required feedforward control quantity and the current feedforward control quantity;

The correction processing sub-module 902 is configured to add the difference to the current feedforward control quantity to obtain a revised feedforward control quantity.

Corresponding to the embodiment of using the two-dimensional table MAP for correction in the method of the present invention, the present invention provides another device embodiment, as shown in FIG. 10 . Fig. 10 is a structural diagram of another embodiment of the feedforward control variable correction device of the high pressure common rail system of the present invention. In this device embodiment, the correction submodule 902 includes:

The modified two-dimensional table MAP sub-module 1001 is used to add the difference to the modified two-dimensional table MAP in the high-pressure common rail system;

The addition calculation sub-module 1002 is used to add the difference in the modified two-dimensional table MAP to the corresponding current feedforward control amount in the calibration two-dimensional table MAP to obtain the corrected feedforward control amount;

In this device embodiment, also include:

The calibration two-dimensional table MAP sub-module 1003 is used to save the current feedforward control amount in the calibration two-dimensional table MAP;

The storage module 1004 is configured to save the modified two-dimensional table MAP into the EEPROM in the high-voltage common rail system after power-off.

With the device embodiment disclosed in the present invention, when the actual fuel consumption under the same working condition caused by the aging or blockage of the high-pressure common rail system changes, the pressure difference value of the measured rail pressure transient signal changes accordingly, and then The calculated actual required feedforward control quantity changes and corrects the current feedforward control quantity of the high pressure common rail system, so that the corrected feedforward control quantity can quickly follow the change of actual fuel consumption, thereby realizing the Rapid and accurate control of rail pressure.

It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is a relationship between these entities or operations. There is no such actual relationship or order between them. The use of the verbs "comprise", "comprise" and their conjugations mentioned in the application documents does not exclude the presence of elements or steps other than those stated in the application documents. The article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements.

The above is only a preferred embodiment of the present invention, it should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, some improvements and modifications can also be made, and these improvements and modifications should also be It is regarded as the protection scope of the present invention.

Claims (16)

1. the method for correcting of rail pressure feedforward control amount in high pressure co-rail system, is characterized in that, comprise the steps:

Steps A: according to the described high pressure co-rail system collected rail pressure decline starting point under steady state operating conditions and the rail pressure value of rail pressure decline end point, calculate the pressure difference of rail pressure transient signal;

Step B: according to the pressure difference of described rail pressure transient signal, calculates actual required feedforward control amount by default corresponding relation;

Step C: judge that whether feedforward control amount needed for described reality is equal with the current feedforward control amount under steady state condition described in high pressure co-rail system, if unequal, then enters step D;

Step D: with feedforward control amount needed for described reality, described current feedforward control amount is revised, obtain revised feedforward control amount.

2. method according to claim 1, is characterized in that, described steps A comprises:

The rail pressure value of the rail pressure decline end point that steps A 11, the multiple rail pressure decline starting point reading described high pressure co-rail system and each rail pressure decline starting point are corresponding;

Steps A 12, calculate the mean value of the rail pressure decline starting point rail pressure value of described multiple rail pressure decline starting point, and, the mean value of the rail pressure decline end point rail pressure value of described multiple rail pressure decline end point;

Steps A 13, the mean value of described rail pressure decline starting point rail pressure value and the mean value of rail pressure decline end point rail pressure value are done difference, to do difference that difference the obtains pressure difference as described rail pressure transient signal.

3. method according to claim 1, is characterized in that, described steps A comprises:

The rail pressure value of the rail pressure decline end point that steps A 21, the multiple rail pressure decline starting point reading described high pressure co-rail system and each rail pressure decline starting point are corresponding;

Steps A 22, by the difference of the rail pressure value of rail pressure decline end point corresponding with described rail pressure decline starting point for described each rail pressure decline starting point rail pressure value;

The mean value of gained difference in steps A 23, calculation procedure A22, and using the pressure difference of the mean value of described difference as rail pressure transient signal.

4. method according to claim 1, is characterized in that, described default corresponding relation is physical model; Described physical model is:

$Q=\frac{\mathrm{nvN}}{120\mathrm{\&beta;}}\mathrm{\&Delta;P};$

In described physical model, Q is actual required feedforward control amount, and n is engine speed, and v is common rail pipe volume, and Δ P is the pressure difference of rail pressure transient signal, and β is the Young's modulus of oil in common rail pipe.

5. method according to claim 1, is characterized in that, described step D is specially:

The value of current feedforward control amount is replaced to the value of actual required feedforward control amount, obtain revised feedforward reduction value.

6. method according to claim 1, is characterized in that, described step D is specially:

Calculate the difference of actual required feedforward control amount and current feedforward control amount, and described difference is added with current feedforward control amount obtains revised feedforward control amount.

7. method according to claim 6, is characterized in that, described current feedforward control amount is kept at demarcates in bivariate table MAP, described difference is added with current feedforward control amount and is specially in described step D:

Described difference is added in described high pressure co-rail system and revise in bivariate table MAP;

The current feedforward control amount that difference in described correction bivariate table MAP is corresponding with described demarcation bivariate table MAP is added.

8. method according to claim 7, is characterized in that, also comprises after described step D: described correction bivariate table MAP power down be saved in the EEPROM (Electrically Erasable Programmable Read Only Memo) EEPROM in described high pressure co-rail system.

9. the correcting device of rail pressure feedforward control amount in high pressure co-rail system, is characterized in that, described device comprises pressure difference extraction module, actual required feedforward control amount computing module, judge module and correcting module;

Described pressure difference extraction module, for according to the described high pressure co-rail system rail pressure decline starting point under steady state operating conditions collected and the rail pressure value of rail pressure decline end point, calculates the pressure difference of rail pressure transient signal;

Described reality is required calculates controlled quentity controlled variable computing module, calculates actual required feedforward control amount for the pressure difference according to described rail pressure transient signal by presetting corresponding relation;

Described judge module, for judging that whether feedforward control amount needed for described reality is equal with the current feedforward control amount of steady state condition described in high pressure co-rail system, if unequal, then sends to correcting module by judged result;

Described correcting module, for according to the judged result received, revises described current feedforward control amount with feedforward control amount needed for described reality, obtains revised feedforward control amount.

10. device according to claim 9, is characterized in that, described pressure difference extraction module comprises:

Rail pressure value extracts submodule, the rail pressure value of the rail pressure decline end point that multiple rail pressure decline starting point and each rail pressure decline starting point for reading described high pressure co-rail system are corresponding;

Rail pressure value mean value calculation submodule, for calculating the mean value of the rail pressure decline starting point rail pressure value of described multiple rail pressure decline starting point, and, the mean value of the rail pressure decline end point rail pressure value of described multiple rail pressure decline end point;

First pressure difference calculating sub module, for the mean value of described rail pressure decline starting point rail pressure value and the mean value of rail pressure decline end point rail pressure value are done difference, to do the pressure difference of the poor difference obtained as described rail pressure transient signal.

11. devices according to claim 9, is characterized in that, described pressure difference extraction module comprises:

Rail pressure value extracts submodule, the rail pressure value of the rail pressure decline end point that multiple rail pressure decline starting point and each rail pressure decline starting point for reading described high pressure co-rail system are corresponding;

Second pressure difference calculating sub module, for the difference of the rail pressure value by rail pressure decline end point corresponding with described rail pressure decline starting point for described each rail pressure decline starting point rail pressure value;

Pressure difference mean value calculation submodule, for calculating the mean value of described rail pressure value difference calculating module gained difference, and using the pressure difference of the mean value of described difference as rail pressure transient signal.

12. devices according to claim 9, is characterized in that, feedforward control amount computing module needed for described reality comprises actual required feedforward control amount calculating sub module and obtains submodule, wherein,

Described acquisition submodule is for obtaining the physical model set up in advance as described default corresponding relation; Described physical model is:

$Q=\frac{\mathrm{nvN}\&CenterDot;\mathrm{\&Delta;P}}{120\mathrm{\&beta;}};$

In described physical model, Q is actual required feedforward control amount, and n is engine speed, and v is common rail pipe volume, and Δ P is the pressure difference of rail pressure transient signal, and β is the Young's modulus of oil in common rail pipe;

Feedforward control amount calculating sub module needed for described reality, for calculating actual required feedforward control amount according to the pressure difference of described physical model and described rail pressure transient signal.

13. devices according to claim 9, is characterized in that, described correcting module, specifically for the value of current feedforward control amount being replaced to the value of actual required feedforward control amount, obtain revised feedforward reduction value.

14. devices according to claim 9, is characterized in that, described correcting module comprises:

Calculated difference submodule, for calculating the difference of actual required feedforward control amount and current feedforward control amount;

Correcting process submodule, for and described difference be added with current feedforward control amount obtain revised feedforward control amount.

15. devices according to claim 14, is characterized in that, described device also comprises demarcates bivariate table MAP module, demarcates in bivariate table MAP for current feedforward control amount being kept at; Described correcting process submodule, comprising:

Revise bivariate table MAP submodule, revise in bivariate table MAP for described difference is added in described high pressure co-rail system;

Addition calculation submodule, is added for the current feedforward control amount that the difference in described correction bivariate table MAP is corresponding with described demarcation bivariate table MAP and obtains revised feedforward control amount.

16. devices according to claim 15, is characterized in that, described device also comprises storage module, for correction bivariate table MAP power down being saved in the EEPROM (Electrically Erasable Programmable Read Only Memo) EEPROM in described high pressure co-rail system.