Control strategy for fuel injection quantity after parking regeneration based on DPF (diesel particulate filter)

Abstract

The invention discloses a control strategy based on DPF parking regeneration post-injection oil quantity, relates to an engine, and solves the technical problem that an existing DPF parking regeneration post-injection calibration mode cannot be suitable for a double-frequency mode. The strategy comprises the steps that the regeneration stage of the engine is obtained, when the regeneration stage is the Rgn regeneration stage, the real-time fuel injection quantity and the real-time rotating speed of the engine are obtained, and the upper limit value of the fuel injection quantity is calibrated according to the real-time fuel injection quantity and the real-time rotating speed so that the T5 temperature can be maintained within the preset temperature range. The parking regeneration requirement of the double-frequency machine is met, and the operation requirement of a user at different rotating speeds is met.

Description

TECHNICAL FIELD

[0001] The present application relates to an engine, more particularly, it relates to a control strategy for the post-injection injection oil quantity based on DPF parking regeneration. BACKGROUND

[0002] In the DPF parking regeneration process, when entering the regeneration stage, the post-injection injection is turned on, and the upper limit value of the Post oil quantity upper limit curve is reasonably calibrated through the exhaust temperature closed loop control to make the T5 temperature (the intake temperature of the DPF) rapidly rise, the regeneration temperature is maintained between 550℃-600℃, and parking regeneration is performed to burn off the carbon particles accumulated on the DPF carrier and the crystals accumulated on the mixer. However, as the engine business increases, it is necessary to develop an engine dual frequency, and users will switch between 1500r and 1800r during use according to actual use, but the current DPF parking regeneration about post-injection injection: only one curve is calibrated, which cannot be applied to dual frequency, that is, the calibrated parking regeneration is suitable for 1500r, but in the case of 1800r, the T5 temperature will be lower than 550℃ during parking regeneration, which cannot complete the parking regeneration, and the applicability is poor. SUMMARY

[0003] The technical problem to be solved by the present application is to provide a control strategy for the post-injection injection oil quantity based on DPF parking regeneration, which solves the technical problem that the existing DPF parking regeneration post-injection injection calibration method cannot be applied to dual frequency mode.

[0004] The control strategy for the post-injection injection oil quantity based on DPF parking regeneration, the strategy is, obtaining the regeneration stage of the engine, when the regeneration stage is Rgn regeneration stage, obtaining the real-time injection quantity and real-time speed of the engine, and calibrating the post-injection injection oil quantity upper limit value according to the real-time injection quantity and real-time speed to maintain the T5 temperature in a preset temperature range.

[0005] Further improvement, when the real-time speed is 750~1600rpm and the real-time injection quantity is 40~100mg / str, the post-injection injection oil quantity upper limit value decreases with the increase of the real-time injection quantity.

[0006] Further, when the real-time injection quantity is 100~160mg / str and the real-time speed is unchanged, the post-injection injection oil quantity upper limit value also increases with the increase of the real-time injection quantity.

[0007] Further, when the real-time injection quantity is 40mg / str and the real-time speed increases from 1600rpm to 1700rpm, the post-injection injection oil quantity upper limit value decreases.

[0008] Further, when the real-time rotating speed is 750-1600 rpm and the real-time fuel injection amount is unchanged, the upper limit value of the post-injection fuel injection amount remains unchanged.

[0009] Further, when the real-time rotating speed is 1700-1900 rpm and the real-time fuel injection amount is unchanged, the upper limit value of the post-injection fuel injection amount remains unchanged.

[0010] Further, when the real-time rotating speed is unchanged, the real-time fuel injection amount is greater than 160 mg / str, and the upper limit value of the post-injection fuel injection amount is equal to the upper limit value of the post-injection fuel injection amount when the real-time fuel injection amount is 160 mg / str.

[0011] Advantages The present application has the advantages that: The present application acquires the regeneration stage of an engine, when the regeneration stage is Rgn regeneration stage, acquires the real-time fuel injection amount and real-time rotating speed of the engine, and according to the real-time fuel injection amount and real-time rotating speed, calibrates the upper limit value of the post-injection fuel injection amount to maintain the T5 temperature in a preset temperature range; so that different rotating speeds can satisfy the parking regeneration to perform regeneration under the same version of electronic control data, satisfy the user demand, satisfy the parking regeneration requirement of a double-frequency engine, and satisfy the user's operation requirement under different rotating speeds. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1 The present application is a post-injection fuel injection amount upper limit value calibration map based on the control strategy of the post-injection fuel injection amount of DPF parking regeneration. DETAILED DESCRIPTION

[0013] The present application will be further described below in conjunction with embodiments, but does not constitute any limitation on the present application, and any limited modification made by anyone within the scope of the claims of the present application is still within the scope of the claims of the present application. Reference Figure 1 The present application is a control strategy of the post-injection fuel injection amount of DPF parking regeneration, which acquires the regeneration stage of an engine, when the regeneration stage is Rgn regeneration stage, acquires the real-time fuel injection amount and real-time rotating speed of the engine, and according to the real-time fuel injection amount and real-time rotating speed, calibrates the upper limit value of the post-injection fuel injection amount to maintain the T5 temperature in a preset temperature range. The temperature range is 550-600℃.

[0014] By Figure 1It can be seen that when the real-time speed is 750-1600 rpm and the real-time fuel injection amount is 40-100 mg / str, the upper limit value of the post-injection fuel injection amount decreases with the increase of the real-time fuel injection amount, so that when the main injection fuel injection amount increases, the engine load and the exhaust temperature generally increase. Reducing the post-injection amount can avoid excessive enrichment of the mixture, thereby reducing unnecessary fuel consumption. When the real-time fuel injection amount is 100-160 mg / str and the real-time speed is unchanged, the upper limit value of the post-injection fuel injection amount increases with the increase of the real-time fuel injection amount.

[0015] When the real-time fuel injection amount is 40 mg / str and the real-time speed increases from 1600 rpm to 1700 rpm, the upper limit value of the post-injection fuel injection amount decreases, so that the post-injection amount is appropriately reduced, and excessive fuel injection can be avoided, thereby reducing unnecessary fuel consumption.

[0016] When the real-time speed is 750-1600 rpm and the real-time fuel injection amount is unchanged, the upper limit value of the post-injection fuel injection amount remains unchanged. When the real-time fuel injection amount is 40 mg / str and the real-time speed is 750-1600 rpm, the upper limit value of the post-injection fuel injection amount is 13.00 mg / str; when the real-time fuel injection amount is 60 mg / str and the real-time speed is 750-1600 rpm, the upper limit value of the post-injection fuel injection amount is 12.00 mg / str; when the real-time fuel injection amount is 80 mg / str and the real-time speed is 750-1600 rpm, the upper limit value of the post-injection fuel injection amount is 11.50 mg / str; when the real-time fuel injection amount is 100 mg / str and the real-time speed is 750-1600 rpm, the upper limit value of the post-injection fuel injection amount is 11.20 mg / str; when the real-time fuel injection amount is 120 mg / str and the real-time speed is 750-1600 rpm, the upper limit value of the post-injection fuel injection amount is 12.20 mg / str; when the real-time fuel injection amount is 140 mg / str and the real-time speed is 750-1600 rpm, the upper limit value of the post-injection fuel injection amount is 13.10 mg / str; when the real-time fuel injection amount is 160 mg / str and the real-time speed is 750-1600 rpm, the upper limit value of the post-injection fuel injection amount is 13.50 mg / str; when the real-time fuel injection amount is 180 mg / str and the real-time speed is 750-1600 rpm, the upper limit value of the post-injection fuel injection amount is 13.50 mg / str.

[0017] The above-mentioned mode of keeping the upper limit value unchanged at low speed can ensure the stability of emission control of the engine in the low speed range (such as idling and city slow running), and avoid excessive post-injection amount leading to excessive particulate matter emission or decreased DPF regeneration efficiency. At the same time, this helps to maintain the smoothness of combustion at low speed, reduce the torque fluctuation that may be caused by post-injection intervention, and improve the driving comfort.

[0018] When the real-time engine speed is 1700~1900rpm and the real-time injection quantity remains constant, the upper limit of the subsequent injection quantity remains unchanged. When the real-time injection quantity is 40mg / str and the real-time engine speed is 1700~1900rpm, the upper limit of the subsequent injection quantity is 12.80mg / str; when the real-time injection quantity is 60mg / str and the real-time engine speed is 1700~1900rpm, the upper limit of the subsequent injection quantity is 12.80mg / str; when the real-time injection quantity is 80mg / str and the real-time engine speed is 1700~1900rpm, the upper limit of the subsequent injection quantity is 13.00mg / str; when the real-time injection quantity is 100mg / str and the real-time engine speed is 1700~1900rpm, the upper limit of the subsequent injection quantity is 13.20mg / str; when... When the real-time injection quantity is 120 mg / str and the real-time engine speed is 1700~1900 rpm, the upper limit of the subsequent injection quantity is 13.80 mg / str; when the real-time injection quantity is 140 mg / str and the real-time engine speed is 1700~1900 rpm, the upper limit of the subsequent injection quantity is 14.90 mg / str; when the real-time injection quantity is 160 mg / str and the real-time engine speed is 1700~1900 rpm, the upper limit of the subsequent injection quantity is 15.50 mg / str; when the real-time injection quantity is 180 mg / str and the real-time engine speed is 1700~1900 rpm, the upper limit of the subsequent injection quantity is 15.50 mg / str.

[0019] The aforementioned method of maintaining a constant upper limit at high engine speeds optimizes fuel economy under high-load conditions (such as high-speed cruising and hill climbing). By fixing the post-injection quantity, the ECU can more precisely control the main injection quantity, avoiding unnecessary fuel waste and thus reducing fuel consumption. Furthermore, this also helps maintain stable exhaust temperatures within this engine speed range, providing a suitable operating environment for aftertreatment systems (such as SCR) and ensuring efficient nitrogen oxide (NOx) conversion.

[0020] When the real-time engine speed remains constant, the upper limit of the post-injection fuel quantity calibrated at a real-time injection quantity greater than 160 mg / str is equal to the upper limit of the post-injection fuel quantity calibrated at a real-time injection quantity of 160 mg / str. 160 mg / str is the upper limit threshold for the real-time injection quantity. Once this threshold is exceeded, the upper limit of the post-injection fuel quantity will no longer be adjusted to protect the engine.

[0021] Similarly, T5 temperature indirectly affects the real-time fuel injection quantity, thus affecting the calibrated upper limit of the post-injection quantity. Therefore, while considering the influence of engine speed and load on the real-time fuel injection quantity, the influence of T5 temperature on the real-time fuel injection quantity should also be considered. The following is a method for correcting the real-time fuel injection quantity using T5 temperature: The system acquires real-time T5 temperature, real-time engine speed, and real-time load. When the real-time T5 temperature is within the aforementioned temperature range, the base fuel injection quantity is calibrated using the real-time engine speed and load, and this base fuel injection quantity is used as the real-time fuel injection quantity without correction. When the real-time T5 temperature is less than the minimum value of the temperature range, the difference between the minimum value of the temperature range and the real-time T5 temperature is used to obtain a first temperature difference value. The fuel injection quantity-temperature difference correlation coefficient is calibrated based on the real-time engine speed and load. The first temperature difference value is multiplied by the fuel injection quantity-temperature difference correlation coefficient to obtain the correction value. The positive injection quantity is obtained by adding the base injection quantity and the corrected injection quantity. When the real-time T5 temperature is greater than the maximum value of the temperature range, the difference between the maximum value of the temperature range and the real-time T5 temperature is used to obtain the second temperature difference value. The first temperature difference value is multiplied by the injection quantity-temperature difference correlation coefficient to obtain the corrected injection quantity. The base injection quantity and the corrected injection quantity are added to obtain the real-time injection quantity. This allows for precise response to extreme temperature conditions during DPF regeneration based on the T5 temperature, avoiding fuel injection quantity runaway, and improving fuel economy and system reliability.

[0022] The above calibration method enables regeneration under the same version of electronic control data at different speeds, meeting user needs; it also meets the parking regeneration requirements of dual-frequency machines and the user's operating requirements at different speeds.

[0023] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the structure of the present invention, and these will not affect the effectiveness of the implementation of the present invention or the practicality of the patent.

Claims

1. A control strategy for the amount of fuel injected after DPF parking regeneration, characterized in that, The strategy involves obtaining the engine's regeneration stage. When the regeneration stage is the Rgn regeneration stage, the real-time fuel injection quantity and real-time speed of the engine are obtained. Based on the real-time fuel injection quantity and real-time speed, an upper limit value of the fuel injection quantity is calibrated to maintain the T5 temperature within a preset temperature range.

2. The control strategy for the amount of fuel injected after DPF parking regeneration according to claim 1, characterized in that, When the real-time rotational speed is 750~1600rpm and the real-time injection quantity is 40~100mg / str, the upper limit of the subsequent injection quantity decreases as the real-time injection quantity increases.

3. The control strategy for the amount of fuel injected after DPF parking regeneration according to claim 1, characterized in that, When the real-time injection quantity is 100~160mg / str and the real-time rotation speed remains unchanged, the upper limit of the subsequent injection quantity also increases with the increase of the real-time injection quantity.

4. The control strategy for the amount of fuel injected after DPF parking regeneration according to claim 1, characterized in that, When the real-time injection quantity is 40 mg / str and the real-time speed increases from 1600 rpm to 1700 rpm, the upper limit of the subsequent injection quantity decreases.

5. The control strategy for the amount of fuel injected after DPF parking regeneration according to claim 1, characterized in that, When the real-time rotational speed is 750~1600rpm and the real-time injection quantity remains unchanged, the upper limit of the subsequent injection quantity remains unchanged.

6. The control strategy for the amount of fuel injected after DPF parking regeneration according to claim 1, characterized in that, When the real-time rotational speed is 1700~1900rpm and the real-time injection quantity remains unchanged, the upper limit of the subsequent injection quantity remains unchanged.

7. The control strategy for the amount of fuel injected after DPF parking regeneration according to claim 1, characterized in that, When the real-time rotational speed remains constant, the upper limit of the post-injection fuel quantity calibrated at a real-time injection quantity greater than 160 mg / str is equal to the upper limit of the post-injection fuel quantity calibrated at a real-time injection quantity of 160 mg / str.

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