JP2007510855A - Control method for regeneration of particle filter - Google Patents

Abstract

The method involves estimating variation of dilution rate of fuel based on a number of fuel injection phases in combustion chambers, quantity of the injected fuel, the position of pistons in the chambers during the fuel injection and supply pressure of the fuel. The variation of the dilution rate is calculated on a delayed injection phase and a rapid injection phase. An independent claim is also included for a method of controlling a motorization system having an engine and a particles filter.

Description

  The present invention relates to a control method for regenerating a particle filter installed in a vehicle power unit.

  The heterogeneity of the combustion process in engines operating with lean mixtures, especially diesel engines, results in the production of carbon particles that are not effectively burned in the engine. This is represented, for example, by the appearance of black smoke at the outlet of the exhaust line. This phenomenon is an environmental pollution source that needs to be reduced.

  The presence of a particulate filter in the engine exhaust line significantly reduces the amount of dust and other soot particles released into the atmosphere, making it possible to meet environmental pollution control regulations.

  The regenerator of the particle filter allows the particles trapped in the particle filter to be burned periodically to avoid clogging the particle filter. Soot particles are essentially carbon-containing components whose combustion consumes oxygen to form carbon dioxide.

  This is done by raising the temperature in the particle filter to a temperature of about 550-650 ° C. From this temperature, particles trapped in the particle filter begin to spontaneously burn.

  The start of regeneration of the particle filter is controlled by a computer. The computer determines whether the regeneration of the particle filter is to be performed and, if the particle filter is being regenerated, determines whether the regeneration of the particle filter can be continued. For this reason, the computer receives information on the operating state of the vehicle. This information includes, for example, engine coolant temperature, exhaust gas temperature upstream and downstream of the particle filter, vehicle speed, soot mass accumulated in the particle filter, and the last particle filter regeneration. Elapsed time is included.

  The computer confirms the conditions based on these pieces of information, and starts regeneration of the particle filter only when all the conditions are satisfied. The regeneration of the particle filter is sustained even if some conditions are not met for a duration shorter than a predetermined threshold of about 2 minutes. If at least one condition is not met for a duration longer than the above threshold, the regeneration process of the particle filter is interrupted.

  In order to initiate and sustain the regeneration of the particle filter, the operating state of the engine is changed to increase the temperature of the exhaust gas before passing through the particle filter. This change relates to normal fuel injection, where fuel injection is delayed for at least one cylinder. In some cases, post-injection is performed at the end of the expansion stroke. This subsequent fuel injection does not add to the mechanical output of the engine, but increases the temperature of the exhaust gas. Such changes in engine operating conditions increase fuel consumption and the amount of fuel that passes through the gap between the cylinder and piston and dissolves into the engine oil.

  For the new generation of particle filters with integrated catalyst pot and particle filter functions, operate to maintain conditions that allow combustion of the soot trapped in the filter for the entire duration of regeneration of the particle filter There is a need to. Thus, the above problem continues for the entire duration of regeneration of the particle filter. Furthermore, the above problems are exacerbated in some operating conditions of the engine, in which case little heat is brought into the exhaust gas.

  The amount of fuel dissolved in the engine oil can result in changing the characteristics of the oil, possibly until the engine breaks.

  It is an object of the present invention to make it possible to optimally know the fuel dissolution rate in oil in order to prohibit regeneration of the particle filter when the fuel dissolution rate in engine oil exceeds an acceptable limit. It is to provide a way to do.

  In order to achieve the above object, the present invention is directed to a method for estimating a variation of a fuel dissolution rate in oil of an operating diesel engine. According to the present invention, the fuel dissolution rate variation is a function of the fuel injection conditions into each combustion chamber.

  The inventor has actually confirmed that the parameter that has the most influence on the fuel dissolution rate in oil is the fuel injection condition. By taking these conditions into consideration, it is possible to optimally know the fuel dissolution rate in the engine oil.

In particular, the variation of the fuel dissolution rate is the following parameters:
The number of fuel injections into the combustion chamber during -1 cycle;
-For each fuel injection, the amount of fuel injected and the position of the piston in the combustion chamber during fuel injection;
-Fuel supply pressure;
Is a function of In this way, all fuel injections and their individual parameters are taken into account.

  In particular, the variation in fuel dissolution rate is calculated for delayed fuel injection, which is less efficient than normal fuel injection, and post fuel injection, which does not contribute to the supply of engine output. This type of operation is often used to control the regeneration of the particle filter. For example, after fuel injection is fully taken into account, as opposed to some conventional evaluation methods based solely on engine load, which is evaluated by intake air flow or pressure.

  According to one embodiment, a coefficient is calculated for each fuel injection, and the coefficient is the product of the amount of fuel injected during the fuel injection and the angular position of the crankshaft at the start of the fuel injection. The variation of the fuel dissolution rate is a function of the sum of the coefficients over all of the fuel injections, including an equal multiplication term and a division term equal to the fuel supply pressure. The present inventor has confirmed that such a coefficient can effectively represent the contribution of each fuel injection to the variation of the fuel dissolution rate in oil.

  In particular, the coefficient of delayed fuel injection further includes a multiplication term equal to the rate of change of the fuel injection flow rate between the fuel injection flow rate of delayed fuel injection and the fuel injection flow rate of normal fuel injection, The coefficient further includes a multiplication term equal to the rate of change of the fuel injection flow rate between the fuel injection flow rate of the post fuel injection and the fuel injection flow rate of the delayed fuel injection.

  In particular, the variation of the fuel dissolution rate is zero when the sum of the coefficients over all of the fuel injections is less than the influence threshold, and is an affine continuous function when the sum is greater than or equal to the influence threshold. The inventor has confirmed by comparison with a series of measurements that such a function effectively represents a variation in fuel dissolution rate.

  The present invention is also directed to a method for estimating a fuel dissolution rate in an oil of an operating diesel engine, and the fuel dissolution rate is an integral with respect to a variation time of the estimated fuel dissolution rate as described above. Value.

  The present invention is also directed to a control method for a power unit having an engine and a particle filter that receives exhaust gas of the engine and captures exhaust gas particles, and the control method processes information when necessary. In the method for controlling the power unit for controlling the engine so as to regenerate the particle filter, the estimated value of the fuel dissolution rate in the oil according to the estimation method of the fuel dissolution rate in the oil of the diesel engine in operation. If the estimated value of the fuel dissolution rate is smaller than a predetermined threshold fuel dissolution rate, the regeneration of the particle filter is permitted.

The invention will be better understood and the other features and advantages of the invention will become apparent upon reading the following description given with reference to the accompanying drawings. In the attached drawing:
FIG. 1 is a schematic diagram of a power plant compatible with the present invention;
-Figure 2 is a time series graph of various fuel injection modes;
-Fig. 3 is a flow chart of the regeneration control of the particle filter;
FIG. 4 is a graph representing the change in fuel dissolution rate as a function of the sum of the coefficients.

  The power plant shown in FIG. 1 to which the present invention is applied consists of a diesel engine 1 which is supercharged by a turbo compressor 2 and whose exhaust gas is processed by a particle filter 3 with catalyst. The engine 1 is supplied with air from an air circuit including an air intake port 11, a compressor 12 of the turbo compressor 2, a pressure feed pipe 13, and an intake manifold 14 that leads to a plurality of combustion chambers of the engine 1. Only one combustion chamber 15 is shown in the figure.

  Exhaust gas generated by the combustion is discharged from the combustion chamber 15 through the exhaust manifold 16, passes through the turbo compressor 17, and then passes through the particle filter 3 with catalyst. The exhaust gas recirculation circuit includes a branch pipe 18 provided in the exhaust manifold and a selection valve 19. The selection valve 19 guides the exhaust gas through the cooler 20 or directly through the conduit 21 to the pumping pipe.

  The computer 24 receives information related to the operation of the power plant and controls the engine 1. The computer 24 determines the conditions under which fuel injection is performed, particularly in the engine. Referring to FIG. 2, a time series graph of fuel injection under three different conditions is shown. The horizontal axis of this graph represents the angular position ψ of the crankshaft, and the zero angular position represents the top dead center (PMH) of the piston for the combustion chamber under consideration.

  During normal fuel injection when regeneration of the particle filter is not commanded, fuel injection is performed twice. That is, the front fuel injection 25 and the main fuel injection 26 subsequent to the front fuel injection 25 are executed. The main fuel injection 26 generally starts at the crankshaft angular position ψin before the piston reaches top dead center.

  In the fuel injection when the regeneration is commanded, the fuel injection is delayed. In this case, the fuel injection is executed twice. That is, the front fuel injection 27 and the main fuel injection 28 subsequent to the front fuel injection 27 are executed. Main fuel injection 28 generally begins at the crankshaft angular position after the piston has reached top dead center. When it is necessary to further raise the temperature of the exhaust gas, the post fuel injection 29 is executed. The post fuel injection 29 starts at the crankshaft angular position ψip.

  The computer 24 determines whether playback should be performed. For this reason, the computer 24 checks whether or not several evaluation criteria are satisfied. When all the evaluation criteria are satisfied, a regeneration command is generated. The computer maintains the playback command signal for a predetermined duration. The predetermined duration is a time during which playback is stopped when at least one evaluation criterion is not satisfied. Among these evaluation criteria, the computer takes into account the evaluation criteria relating to the fuel dissolution rate Pdir in the engine oil. This fuel dissolution rate is estimated by a computer, and if the estimated fuel dissolution rate Pdir exceeds a predetermined threshold fuel dissolution rate Sdir, the evaluation criterion is not satisfied. The estimation of the fuel dissolution rate will be described later.

  Reference is made to the flowchart of FIG. 3 for examining this evaluation criterion. In the initial stage 30, the estimated fuel dissolution rate Pdir is initialized to a zero value when the oil is new, and initialized to a previously stored value when the oil is not new. In the test step 31, if the reproduction is not being executed, the process proceeds to step 32, and if the reproduction is being executed, the process proceeds to step 33.

  In step 32, the term dPdil is calculated as the sign of the product of the evaporation function Favap of the fuel contained in the oil and the time interval dt. The function Fevap is calculated from the stored mapping as a function of the rotational speed N and the fuel flow rate Qc.

  In step 33, the term dPdir is calculated by the product of the fuel dissolution rate variation DQc and the time interval dt. The variation DQc of the fuel dissolution rate is calculated from the fuel injection characteristics according to a method adapted to the present invention described later.

  After one calculation in step 32 or 33, a new fuel dissolution rate Pdil (n) is calculated by adding the term dPdil to the fuel dissolution rate Pdil (n-1) in the previous time interval. In this manner, the numerical integration of the variation DQc of the fuel dissolution rate is executed.

  In steps 35 and 36, the fuel dissolution rate is maintained so as not to become zero. Next, in step 37, the fuel dissolution rate Pdir is compared with a predetermined threshold fuel dissolution rate Sdir, and if the fuel dissolution rate Pdir exceeds the threshold fuel dissolution rate Sdir, the evaluation criteria are not satisfied and regeneration is stopped (step 38). . If the fuel dissolution rate Pdir does not exceed the threshold fuel dissolution rate Sdir, regeneration is permitted (step 39).

  In step 40, the process returns to step 31 after waiting for the elapse of time interval dt before proceeding to a new calculation cycle.

  The variation DQc of the fuel dissolution rate is given by

によって計算される。ここに：
Ｃｉｒ：遅延燃料噴射係数；
Ｃｉｐ：後燃料噴射係数；
Ｓｃ：所定の影響閾値；
ａ：比例係数；
である。

Is calculated by here:
Cir: delayed fuel injection coefficient;
Cip: post fuel injection coefficient;
Sc: a predetermined influence threshold;
a: proportionality factor;
It is.

  The graph of FIG. 4 represents a function of the variation DQc with respect to C = Cir + Cip. The delayed fuel injection coefficient is:

によって定義される。ここに：
Ｄｉｒ−ｉｎ：遅延燃料噴射と通常燃料噴射の間における燃料噴射流量の変化率；
ψｉｒ：考慮対象燃焼室のピストンの上死点に対する、遅延燃料噴射開始時におけるクランクシャフトの角度位置；
Ｑｉｒ：遅延燃料噴射フェーズ間における噴射燃料量；
Ｐｃ：燃料噴射器に燃料を供給するコモンランプの圧力；
である。

Defined by here:
Dir-in: change rate of fuel injection flow rate between delayed fuel injection and normal fuel injection;
ψir: angular position of the crankshaft at the start of delayed fuel injection relative to the top dead center of the piston of the combustion chamber to be considered;
Qir: the amount of fuel injected during the delayed fuel injection phase;
Pc: pressure of the common lamp that supplies fuel to the fuel injector;
It is.

  The post fuel injection coefficient is:

によって定義される。ここに：
Ｄｉｐ−ｉｒ：遅延燃料噴射の燃料流量に対する後燃料噴射の噴射流量の比；
Ｑｉｐ：後燃料噴射フェーズ間における噴射燃料量；
ψｉｐ：後燃料噴射開始時におけるクランクシャフトの角度位置；
である。

Defined by here:
Dip-ir: ratio of the fuel flow rate of the post fuel injection to the fuel flow rate of the delayed fuel injection;
Qip: the amount of fuel injected during the post fuel injection phase;
ψip: angular position of the crankshaft at the start of post fuel injection;
It is.

  The effectiveness of these mathematical formulas was confirmed by comparing the calculation results of the mathematical formulas with the experimental results of driving. The rate of dissolution in fuel in the engine oil was measured after operating the engine at constant conditions for a duration of 1 hour. The fuel dissolution rate is measured by, for example, chromatography. After determining the proportionality factor and the influence threshold, the simulation showed 86% correlation to the measurement results.

  The method according to the invention can be applied to the whole of the plurality of combustion chambers if the plurality of combustion chambers are controlled in the same way, or the conditions specific to fuel injection only apply to some combustion chambers. If applicable, it applies individually to each combustion chamber.

1 is a schematic diagram of a power plant compatible with the present invention. It is a time series graph of various fuel injection modes. It is a flowchart of regeneration control of a particle filter. 4 is a graph showing the change in fuel dissolution rate as a function of the sum of coefficients.

Claims (8)

A method for estimating the variation of the fuel dissolution rate in the oil of the diesel engine (1) in operation, wherein the variation (DQc) of the fuel dissolution rate is the following parameter in each combustion chamber (15): :
Number of fuel injections into the combustion chamber (15) during -1 cycle;
For each fuel injection, the amount of fuel injected (Qin, Qir, Qip) and the position of the piston (ψin, ψir, ψip) in the combustion chamber (15) during fuel injection;
In the method for estimating the variation of the fuel dissolution rate in the oil of the diesel engine during operation, the variation of the fuel dissolution rate is further a function of the fuel supply pressure (Pc). A method for estimating the variation of the fuel dissolution rate in the oil of an operating diesel engine.   The variation (DQc) of the fuel dissolution rate includes delayed fuel injection (27, 28) whose efficiency is lower than that of normal fuel injection (25, 26), and post-fuel injection that does not contribute to supply of the engine output. The method for estimating the variation of the fuel dissolution rate in the oil of an operating diesel engine according to claim 1, characterized in that it is calculated for (29).   A coefficient is calculated for each of the fuel injections, and the coefficients (Cir, Cip) are calculated based on the fuel amount (Qir, Qip) injected during the fuel injection and the angular position (ψir) of the crankshaft at the start of the fuel injection. , Ψip) and a division term equal to the fuel supply pressure (Pc), the variation of the fuel dissolution rate (DQc) is the coefficient (Cir, Method for estimating the variation of the fuel dissolution rate in the oil of an operating diesel engine according to claim 1 or 2, characterized in that it is a function of the sum (Cip) of Cip).   The coefficient (Cir) of the delayed fuel injection is further a multiplication term (equal to the rate of change of the fuel injection flow rate between the fuel injection flow rate (Qir) of the delayed fuel injection and the fuel injection flow rate (Qin) of the normal fuel injection ( The method of estimating variation in fuel dissolution rate in oil of an operating diesel engine according to claim 3, characterized in that it includes Dir-in).   The coefficient (Cip) of the post fuel injection is further a multiplication term (Dip) equal to the rate of change of the fuel injection flow rate between the fuel injection flow rate (Qip) of the post fuel injection and the fuel injection flow rate (Qir) of the delayed fuel injection. The method of estimating variation in fuel dissolution rate in oil of an operating diesel engine according to claim 3, characterized in that -ir).   The variation of the fuel dissolution rate is zero when the sum (C) of all the fuel injections of the coefficients (Cir, Cip) is smaller than the influence threshold (Sc), and is greater than or equal to the influence threshold (Sc). 4. The method for estimating the variation of the fuel dissolution rate in the oil of an operating diesel engine according to claim 3, characterized in that it is an affine continuous function.   In the estimation method of the fuel dissolution rate (Pdir) in the oil of the diesel engine in operation | movement, the said fuel dissolution rate is based on the estimation method of the variation of the fuel dissolution rate as described in any one of Claims 1-6. A method for estimating a fuel dissolution rate in an oil of an operating diesel engine, characterized by being an integral value with respect to the estimated variation (DQc) of the fuel dissolution rate.   A control method for a power plant having an engine (1) and a particle filter (3) that receives exhaust gas from the engine and captures exhaust gas particles. A method for controlling a power plant that controls an engine (1) to regenerate the particle filter (3) sometimes, according to the method for estimating a fuel dissolution rate in oil of an operating diesel engine according to claim 7. Clarify the estimated value of the fuel dissolution rate (Pdir) in the oil, and regenerate the particle filter if the estimated value of the fuel dissolution rate (Pdir) is smaller than the predetermined threshold fuel dissolution rate (Sdir). A control method for a power unit having an engine and a particle filter that receives exhaust gas from the engine and captures exhaust gas particles.

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