JP4537232B2 - Control method of fuel injection amount - Google Patents

Description

  The present invention relates to a fuel injection amount control method, a fuel injection amount control system, and a fuel injection amount control program. More specifically, the present invention relates to a fuel injection amount control method, a fuel injection amount control system, and a fuel injection amount control program that can reduce the amount of soot discharged from a diesel engine or the like and improve fuel efficiency.

  Diesel engine is a power source with excellent fuel efficiency and durability, and HC and CO emitted from the engine is less than gasoline engine, so it is a preferable internal combustion engine against global warming, which has become a problem in recent years. is there. However, in a diesel engine, there are more NOx and exhaust particulates (soot) generated during the combustion of the air-fuel mixture than in a gasoline engine, and it is an urgent issue to reduce this NOx and soot from exhaust gas. In this regard, an oxidation catalyst is provided in the exhaust gas flow path from the diesel engine, and further, a DPF having a ceramic porous wall as a filter element is provided on the downstream side thereof, in the exhaust gas discharged from the diesel engine. NOx, CO, HC, etc. are oxidized by an oxidation catalyst, and when the oxidized exhaust gas passes through the porous wall of the DPF, the exhaust gas collects the soot contained in the exhaust gas at the pores. Purification systems are known.

In this exhaust gas purification system, when soot is collected at the pore portion and the wall surface in the filter wall and the collected soot is removed by combustion (regeneration), the amount of collected soot is too large. Since the filter may be damaged by overheating during combustion, there is a limit to the amount of soot that can be collected by the filter. As a method of detecting the collection limit soot amount, an exhaust gas pressure difference (sometimes referred to as “pressure loss” or “pressure loss” for short) and an exhaust gas temperature on the upstream side and downstream side of the DPF are detected. A method for predicting the soot amount accumulated in the filter and detecting that the DPF is at the collection limit based on the predicted value (see Patent Document 1), and the fuel injection amount, the engine speed, and the exhaust gas A method of predicting the exhaust soot amount from mapping of gas temperature and the like and detecting that the DPF is at the collection limit based on the integrated amount is disclosed (see Patent Document 2).
JP 60-47937 A Japanese Patent Laid-Open No. 5-18228

  However, in the method for detecting that the DPF is at the collection limit from the pressure difference between the upstream side and the downstream side of the DPF as disclosed in Patent Document 1, the amount of accumulated soot before and after the DPF regeneration The relationship with the pressure loss has a hysteresis, which causes a disadvantage that the accuracy of the soot amount predicted from the pressure loss is poor. Further, as disclosed in Patent Document 2, the method of predicting the exhaust soot amount from the mapping of the fuel injection amount, the engine speed, the exhaust gas temperature, etc., and detecting that the DPF is at the collection limit, There is an inconvenience that the accuracy of the estimation of the exhaust soot amount deteriorates because an error between the commanded fuel injection amount and the actual fuel injection amount occurs due to individual variations in fuel injectors and fluctuations with time.

  In order to eliminate the inconveniences described above, the DPF regeneration was conventionally performed by reducing the predicted soot amount to be regenerated. However, if the soot accumulation amount at the time of regeneration is decreased, the regeneration interval is shortened and the fuel consumption is deteriorated. When the soot accumulation amount is small, the soot regeneration is finished while leaving a portion where the soot cannot be completely regenerated due to the variation in the amount of adhering soot at the position in the DPF. There was also a problem of end up.

  The present invention has been made in view of the above-described problems, and reduces the soot amount by increasing the accuracy of predicting the soot amount discharged from a diesel engine or the like and optimally controlling the actual fuel injection amount of the engine. An object of the present invention is to provide a fuel injection amount control method, a fuel injection amount control system, and a fuel injection amount control program capable of improving fuel efficiency as combustion efficiency is improved. .

  To achieve the above object, according to the present invention, the following fuel injection amount control method, fuel injection amount control system, and fuel injection amount control program are provided.

[1] A fuel injection amount control method for controlling a fuel injection amount of an engine by correcting the fuel injection amount from an initial set value based on a predetermined condition during traveling, and is discharged from the engine using a soot sensor Based on the first step of measuring the soot emission amount contained in the exhaust gas, and the soot emission amount estimation element including at least the engine speed, the exhaust gas temperature, and the initial fuel injection amount of the engine, A second step of calculating an estimated soot emission amount, a third step of comparing an error threshold value with an error determination reference value set based on the soot emission amount and the estimated soot emission amount, and the error determination When the reference value is equal to or greater than the error threshold, the engine performance including at least the soot emission amount, the engine speed, and the exhaust gas temperature is included. Whether the actual fuel injection amount of the engine is calculated based on the fuel injection amount calculation element of the engine, the initial fuel injection amount of the engine is corrected to the actual fuel injection amount, and then the process returns to the first step. Or a fourth step of returning to the first step without correcting the initial fuel injection amount of the engine when the error determination reference value is less than the error threshold. Control method of fuel injection amount.

[2] The fuel injection amount according to [1], wherein a value calculated from the relationship shown in the following formula (1) between the estimated soot discharge amount and the soot discharge amount is used as the error determination reference value. Control method.
C = │1- (B / A) │ …… (1)
(In the above formula (1), A represents the soot discharge amount, B represents the estimated soot discharge amount, and C represents the error determination reference value.)

[3] The fuel injection amount control method according to [1] or [2], wherein an instantaneous soot concentration measurement type or cumulative soot amount measurement type is used as the soot sensor.

[4] The method for controlling the fuel injection amount according to [3], wherein the soot sensor of the instantaneous soot concentration measurement type uses a sensor that measures the amount of charge, light transmission, or scattering at the instant of the soot.

[5] As described in the above [3], the soot sensor of the cumulative soot amount measurement type uses a sensor that measures a resistance change, a temperature change, or a resonance frequency change of a piezoelectric / electrostrictive material in the accumulation until the measurement of the soot. Control method of fuel injection amount.

[6] A fuel injection amount control system capable of controlling the fuel injection amount of the engine by correcting the fuel injection amount from an initial setting value based on a predetermined condition during traveling, the soot sensor having a soot sensor, Means for measuring the soot emission amount contained in the exhaust gas discharged from the engine, at least the engine speed, the temperature of the exhaust gas, and the initial setting fuel injection of the engine An estimated soot emission calculating means capable of calculating an estimated soot emission estimated based on a soot emission estimation element including the amount, and the soot emission and the estimated soot emission are set based on An error determination reference value / error threshold comparison means capable of comparing an error determination reference value and an error threshold, and the error determination reference value If the error threshold value is greater than or equal to the error threshold, the actual fuel injection amount of the engine is calculated based on an actual fuel injection amount calculation factor of the engine including at least the soot emission amount, the engine speed, and the exhaust gas temperature. The initial fuel injection amount of the engine is corrected to the actual fuel injection amount and then the soot discharge measuring means returns to the measurement of the soot discharge amount, or the error determination reference value is the error threshold value. A fuel injection amount correcting means capable of returning to the measurement of the soot discharge amount by the soot discharge amount measuring means without correcting the initial set fuel injection amount of the engine. A fuel injection amount control system.

[7] The fuel injection amount according to [6], wherein the error determination reference value is a value calculated from a relationship represented by the following expression (1) between the estimated soot discharge amount and the soot discharge amount. Control system.
C = │1- (B / A) │ …… (1)
(In the above formula (1), A represents the soot discharge amount, B represents the estimated soot discharge amount, and C represents the error determination reference value.)

[8] The fuel injection amount control system according to [6] or [7], wherein the soot sensor is of an instantaneous soot concentration measurement type or an accumulated soot amount measurement type.

[9] The fuel injection amount control system according to [8], wherein the soot sensor of the instantaneous soot concentration measurement type measures a charge amount, a light transmission amount or a scattering amount at an instant of the soot.

[10] The above-mentioned [8], wherein the soot sensor of the cumulative soot measurement type measures a resistance change, a temperature change, or a resonance frequency change of the piezoelectric / electrostrictive material in the accumulation until the measurement of the soot. Fuel injection amount control system.

[11] A computer-readable engine fuel injection amount control program for controlling the fuel injection amount of the engine by correcting the fuel injection amount from an initial setting value based on a predetermined condition during traveling,
A fuel injection amount control program capable of causing the computer to function as the following means (1) to (4).
(1) Soot emission measuring means capable of causing the soot sensor to measure the soot emission contained in the exhaust gas exhausted from the engine;
(2) Estimate capable of calculating an estimated soot emission amount estimated based on a soot emission amount estimation element including at least the engine speed, the exhaust gas temperature, and the initial fuel injection amount of the engine Soot emission calculation means,
(3) an error determination reference value / error threshold comparison means capable of comparing an error determination reference value set based on the soot discharge amount and the estimated soot discharge amount with an error threshold;
(4) When the error determination reference value is greater than or equal to the error threshold, the actual fuel injection amount calculation factor of the engine including at least the soot emission amount, the engine speed, and the exhaust gas temperature is used. Calculating the actual fuel injection amount of the engine and correcting the initial fuel injection amount of the engine to the actual fuel injection amount, and then returning to the measurement of the soot discharge amount by the soot discharge measuring means, or When the error determination reference value is less than the error threshold, the fuel injection that can return to the measurement of the soot discharge amount by the soot discharge amount measuring means without correcting the initial fuel injection amount of the engine Amount correction means.

[12] The fuel injection amount according to [11], wherein the error determination reference value is a value calculated from a relationship represented by the following formula (1) between the estimated soot discharge amount and the soot discharge amount: Control program.
C = │1- (B / A) │ …… (1)
(In the above formula (1), A represents the soot discharge amount, B represents the estimated soot discharge amount, and C represents the error determination reference value.)

[13] The fuel injection amount control program according to [11] or [12], wherein the soot sensor is of an instantaneous soot concentration measurement type or an accumulated soot amount measurement type.

[14] The fuel injection amount control program according to [13], wherein the soot sensor of the instantaneous soot concentration measurement type measures a charge amount, a light transmission amount, or a scattering amount at an instant of the soot.

[15] The above-described [13], wherein the soot sensor of the cumulative soot measurement type measures a resistance change, a temperature change, or a resonance frequency change of the piezoelectric / electrostrictive material in the accumulation until the measurement of the soot. Control program for fuel injection.

  The “program” in the present invention means an ordered sequence of instructions suitable for processing by a computer. Specifically, it is installed in a computer HD (Hard Disk), CD-RW or the like. Means recorded on various recording media such as CD-ROM, DVD, FD, semiconductor memory, and computer HDD; and distributed via an external network such as the Internet.

  As described above, according to the present invention, it is possible to reduce the exhaust soot amount by improving the prediction accuracy of the soot amount discharged from a diesel engine or the like and optimally controlling the actual fuel injection amount of the engine. In addition, a fuel injection amount control method, a fuel injection amount control system, and a fuel injection amount control program capable of improving fuel efficiency as combustion efficiency is improved are provided.

  Hereinafter, the best mode for carrying out the present invention will be specifically described with reference to the drawings.

  The best mode for carrying out the present invention will be specifically described below. The fuel injection amount control method of the present invention is a fuel injection amount control method that controls the fuel injection amount of the engine by correcting the fuel injection amount of the engine from an initial set value based on a predetermined condition during traveling as described above. First to fourth steps are included. Hereinafter, each step will be described in detail. Here, the fuel injection amount control method will be mainly described as the present invention, but the fuel injection amount control system and the fuel injection amount control program are basically the same.

(First step)
The first step is a step of measuring the soot discharge amount contained in the exhaust gas discharged from the engine using a soot sensor.

  Although there is no restriction | limiting in particular as a soot sensor used for a 1st step, For example, the thing of an instantaneous soot density | concentration measurement type or a cumulative soot amount measurement type can be mentioned. Examples of the soot sensor of the instantaneous soot concentration measurement type include a sensor that measures the amount of charge, the amount of transmitted light or the amount of scattering at the moment of soot. Further, examples of the soot sensor of the cumulative soot measurement type include a sensor that measures a resistance change, a temperature change, or a resonance frequency change of a piezoelectric / electrostrictive material in the accumulation until the soot measurement. As a method of measuring the soot discharge amount using such a soot sensor, for example, in the case of the instantaneous soot concentration measurement type, the soot sensor output value can be directly used as the soot discharge amount, and the cumulative soot discharge amount can be mentioned. In the case of the measurement type, the current soot discharge amount can be obtained by subtracting the cumulative soot amount measured in the first step from the cumulative soot amount measured this time.

(Second step)
The second step is a step of calculating an estimated soot emission amount based on at least a soot emission amount estimation element including an engine speed, an exhaust gas temperature, and an engine initial fuel injection amount.

  Examples of the soot emission amount estimation element (an element for estimating the soot emission amount by mapping) include engine speed, exhaust gas temperature, engine initial fuel injection amount, accelerator opening, and the like. In particular, the engine speed, the exhaust gas temperature, and the initial fuel injection amount of the engine are closely correlated with the soot emission amount, and include at least these three elements. As a method for calculating the estimated soot emission amount based on the soot emission estimation element, in the case of the engine speed, for example, as in JP-A-5-18228, in the case of the exhaust gas temperature, For example, as in JP-A-7-139334, in the case of the initial fuel injection amount, for example, as in the fourth embodiment of the Toyota Technical Publication (issued May 31, 2004, issue number 15776) Can be mentioned.

(Third step)
The third step is a step of comparing an error determination reference value set based on the soot discharge amount and the estimated soot discharge amount with an error threshold value.

As described above, the error determination reference value is set based on the soot discharge amount and the estimated soot discharge amount. For example, the relationship shown in the following formula (1) between the estimated soot discharge amount and the soot discharge amount. It is preferable to use a value calculated from
C = │1- (B / A) │ …… (1)
(In the above formula (1), A represents the soot discharge amount, B represents the estimated soot discharge amount, and C represents the error determination reference value.)

  The error threshold is set according to how much fuel injection amount error can be allowed by a vehicle equipped with this system.

(Fourth step)
In the fourth step, when the error determination reference value is equal to or greater than the error threshold, the actual fuel injection amount calculation element (actual fuel injection amount calculation) including at least the soot emission amount, the engine speed, and the exhaust gas temperature is included. The actual fuel injection amount (actual fuel injection amount) of the engine is calculated based on the element), the initial fuel injection amount of the engine is corrected to the actual fuel injection amount, and then the process returns to the first step or an error occurs. When the determination reference value is less than the error threshold, the process returns to the first step without correcting the initial fuel injection amount of the engine.

  Examples of the actual fuel injection amount calculation element include soot discharge amount, engine speed, exhaust gas temperature, accelerator opening, etc., among others, soot discharge amount, engine speed, exhaust gas The temperature is closely correlated with the actual fuel injection amount. The actual fuel injection amount of the engine is calculated based on at least these three factors, and the initial fuel injection amount of the engine is calculated. It is preferable to correct accordingly. The method for measuring these three elements can be the same as that described above.

  Hereinafter, a case where the fuel injection amount control method of the present invention is applied to a control system of an engine system of a vehicle (diesel vehicle) equipped with a diesel engine will be specifically described with reference to the drawings.

  FIG. 1 is an explanatory view schematically showing a control system of an engine system of a diesel vehicle to which the present invention is applied. As shown in FIG. 1, an intake port of a diesel engine (hereinafter also referred to as “engine”) 11 is connected to an intake pipe 13b via an intake manifold 13a, and an exhaust port is connected to an exhaust pipe via an exhaust manifold 16a. A tube 16b is connected. An exhaust passage 16 is constituted by the intake manifold 16a and the exhaust pipe 16b. The intake pipe 13b is provided with a compressor 17a of a turbocharger 17 provided with a supercharging pressure control means, and an intercooler 18 for cooling the intake air compressed by the turbocharger 17, and the exhaust pipe 16b is provided with an exhaust pipe 16b. A turbine 17b of the turbocharger 17 is provided. Although not shown, the rotor blades of the compressor 17a and the rotor blades of the turbine 17b are connected by a shaft. The compressor 17a is rotated via the turbine 17b and the shaft by the energy of the exhaust gas discharged from the engine 11, and the intake air in the feeder pipe 13b is compressed by the rotation of the compressor 17a.

  Further, an oxidation catalyst 21 such as a platinum-based catalyst that functions as a NOx catalyst and an oxidation catalyst, and a DPF 22 are provided in the middle of the exhaust pipe 16b in order from the engine side (exhaust gas upstream side). The oxidation catalyst 21 and the DPF 22 are accommodated in a cylindrical collector 24 in which the diameter of the exhaust pipe 16b is enlarged. An intake throttle valve 26 capable of adjusting the flow rate of intake air is provided in the intake pipe 13b upstream of the compressor 17a.

  The platinum catalyst of the oxidation catalyst 21 is a platinum-alumina catalyst, a platinum-zeolite catalyst, or a platinum-zeolite-alumina catalyst. The platinum-alumina catalyst is formed by coating Pt on a honeycomb carrier made of cordierite after coating a slurry containing γ-alumina powder. The platinum-zeolite catalyst is formed by coating a honeycomb carrier made of cordierite with a slurry containing hydrogen ion-exchanged zeolite powder (H-ZSM-5) and then supporting Pt. Further, the platinum-zeolite-alumina catalyst is formed by coating a honeycomb carrier made of cordierite with a slurry containing hydrogen ion-exchanged zeolite powder (H-ZSM-5) and γ-alumina powder, and then supporting Pt. .

  The DPF 22 has a honeycomb structure, and as shown in FIG. 2, the porous DPF 22 is made of ceramics such as cordierite and SiC (gas is allowed to pass through but soot is blocked by blocking its passage (blocking outflow)). A partition wall 22a having a plurality of pores (pores) having a diameter that can be used as a filter element, and a cell partitioned by the partition wall 22a, for example, having a polygonal cross section and serving as a fluid flow path. Have.

  The DPF 22 is configured by alternately and alternately staggering the entrance side cells 22c and the exit side cells 22d of the cells 22b formed in parallel with each other by the partition walls 22a. Further, a noble metal such as Pt and Pd may be directly supported on the partition wall 22a, and after coating a slurry containing γ-alumina powder on the partition wall 22a, a noble metal such as Pt and Pd is supported on the DPF 22 so You may provide the oxidizing power of hydrocarbon (HC).

  FIG. 2 is an enlarged cross-sectional view schematically showing a DPF used in the present invention. As shown in FIG. 2, the exhaust gas E1 exhausted from the engine 11 is oxidized as NO, CO, and HC components contained in the gas via the oxidation catalyst 21, and then is used as a high-temperature exhaust gas resulting from the oxidation reaction. It flows into the DPF 22 from the open side cell in the entrance side cell 22c of the DPF 22, passes through the plurality of pores of the partition wall 22a, enters the adjacent cell, and is exhausted through the exit side cell 22d at the open end. Further, when the exhaust gas E1 passes through each pore of the partition wall 22a, the soot contained in the exhaust gas E1 is blocked from flowing out to the adjacent cell by each pore, and accumulates in each pore and on the surface of the partition wall 22a. The amount of soot contained in the exhaust gas E2 that has passed through can be greatly reduced.

  The engine 11 is also provided with an EGR (Exhaust Gas Recirculation) control valve for recirculating exhaust gas to intake air for the purpose of reducing NOx in exhaust components and improving fuel efficiency. In addition, an EGR cooler is provided that cools the exhaust when it is turned to intake air again.

  Further, a temperature sensor 36 for detecting the exhaust gas temperature in the exhaust pipe 16b is provided at the exhaust pipe 16b between the turbine 17b and the collector 24, that is, at the entrance of the oxidation catalyst 21, and also at the outlet side of the DPF 22. A temperature sensor 42 for measuring the temperature of the passing gas after the exhaust gas has passed through the DPF 22 is provided. Detection outputs of the temperature sensor 36 and the temperature sensor 42 are connected to a control input of an ECU (Electronic Control Unit) 37 formed of a microcomputer. Other control inputs of the ECU 37 include a rotation sensor 38 that detects the rotation speed of the engine 11, an accelerator opening change sensor 39 that detects changes in the accelerator opening and the accelerator change speed, and the soot discharge amount contained in the exhaust gas. The respective detection outputs of the soot sensors 41a and 41b for measuring the mileage and the travel distance sensor 50 for detecting the travel distance of the vehicle are connected.

  Examples of the soot sensor 41a include an instantaneous soot concentration measurement type, and examples of the soot sensor 41b include a cumulative soot amount measurement type. Examples of the soot sensor of the instantaneous soot concentration measurement type include a sensor that measures the amount of charge, the amount of transmitted light or the amount of scattering at the moment of soot. Further, examples of the soot sensor of the cumulative soot measurement type include a sensor that measures a resistance change, a temperature change, or a resonance frequency change of a piezoelectric / electrostrictive material in the accumulation until the soot measurement. In the case of the cumulative soot amount measurement type, a heater for burning out the soot adhering to the sensor element may be provided.

  In addition, the ECU 37 includes a memory 43. In the memory 43, the opening / closing control of the EGR control valve 20, the opening / closing control of the intake throttle valve 26, and the air generated by the rotation of the compressor 17a according to the engine rotation, exhaust gas temperature, travel distance, accelerator opening, accelerator change speed, etc. A program for performing intake amount control and the like and for instructing the engine 11 to start regeneration of the DPF 22 is stored in advance.

  Further, the fuel injector 40 of the engine 11 is electrically connected to the ECU 37, and the ECU 37 instructs the fuel injector 40 about the fuel injection timing and the fuel injection amount.

  FIG. 3 is a flowchart schematically showing a control operation in a control system of an engine system of a diesel vehicle when an instantaneous soot concentration measurement type soot sensor is used.

As shown in FIG. 3, first, an output value (soot discharge amount) A of the soot sensor 41a of the instantaneous soot concentration measurement type is read by the ECU 37 (see FIG. 1; the same reference numerals are used hereinafter) (step S21). FIG. 5 schematically shows the relationship between the soot sensor output value and time (when the soot discharge amount is substantially constant) when an instantaneous soot concentration measurement type soot sensor is used. Next, the exhaust temperature is read from the temperature sensor 36, the engine speed is read from the rotation sensor 38, and the estimated soot that will be discharged from the engine from the initial set fuel injection amount, the exhaust temperature, the engine speed, etc. of the ECU 37. A discharge amount B is calculated (step S22). Next, the estimated soot discharge amount B is divided by the soot discharge amount A, and it is determined whether or not the division result (error determination reference value = | 1- (B / A) |) is equal to or larger than an error threshold (step S23). If the error determination reference value is not equal to or greater than the error threshold value (is less than the error threshold value) (NO), the process is repeated from step S21. On the other hand, if the error determination reference value is equal to or greater than the error threshold (YES), the actual fuel injection amount (actual fuel injection amount) is obtained from the soot sensor output value, engine speed, exhaust temperature, etc. read in steps S21 and S22. Then, the initial set fuel injection amount is corrected to the actual fuel injection amount (step S24), and the processing is performed again from step S21. 7 and 8 schematically show first and second examples in which the initial fuel injection amount of the engine is corrected to the actual fuel injection amount. That is, among the soot emission estimation elements including the engine speed, the exhaust gas temperature, the initial fuel injection amount of the engine, and the like used for calculating the estimated soot emission B that will be emitted from the engine, the engine When the elements other than the initial set fuel injection amount are constant, the relationship between the initial fuel injection amount and the soot discharge amount is indicated by a solid line in FIGS. Here, an error determination reference value set based on the estimated soot discharge amount B derived from the initial set fuel injection amount, the exhaust temperature, the engine speed, etc., and the soot discharge amount A at that time measured by the soot sensor, Compare the error threshold. At this time, if the error determination reference value is equal to or larger than the error threshold, the map of the soot discharge amount in the fuel injection amount may be corrected as shown by the dotted line in FIG. 7, or as shown in FIG. The initial set fuel injection amount F ₀ may be corrected to the actual fuel injection amount F. In this way, two types of correction can be properly used depending on the system.

  As described above, when an instantaneous soot concentration measurement type soot sensor is used, individual variations and fluctuations over time cannot be avoided by correcting the initial fuel injection amount of the ECU 37 using the output value of the soot sensor 41a. It becomes possible to set the fuel injection amount of the fuel injector to a correct value. As a result, it is possible to improve the accuracy of soot emission prediction by mapping and optimally control the actual fuel injection amount of the engine, and always allow combustion with a fuel injection amount with good combustion efficiency. Can also solve the problem of deterioration.

  FIG. 4 is a flowchart schematically showing a control operation in a control system of an engine system of a diesel vehicle when a soot sensor of a cumulative soot amount measurement type is used.

  As shown in FIG. 4, first, an output value (soot discharge amount) X of a soot sensor 41b of a cumulative soot amount measurement type is read by the ECU 37 (see FIG. 1, and the same reference numerals are used hereinafter) (step S31). The current soot discharge amount A is obtained by subtracting the previous measurement value C from the soot sensor output value X (step S32). FIG. 6 schematically shows the relationship between the soot sensor output value and time (when the soot discharge amount is substantially constant) when a cumulative soot concentration measurement type soot sensor is used. Next, the current soot sensor output value X is registered in the previous measurement value C (step S33). Next, the exhaust temperature is read from the temperature sensor 36, the engine speed is read from the rotation sensor 38, and the estimated soot discharge that will be generated from the engine is determined from the initial fuel injection amount, the exhaust temperature, the engine speed, etc. of the ECU 37. The amount B is calculated (step S34). Next, the estimated soot discharge amount B is divided by the current soot discharge amount A, and it is determined whether or not the division result (error determination reference value = | 1- (B / A) |) is equal to or larger than the error threshold (step S35). ). If the error determination reference value is not equal to or greater than the error threshold value (is less than the error threshold value) (NO), the process is repeated from step S31. On the other hand, if the error determination reference value is equal to or greater than the error threshold (YES), the actual fuel injection amount (actual fuel injection amount) is calculated from the current soot concentration, engine speed, exhaust temperature, etc. calculated in steps S32 and S34. Then, the commanded fuel injection amount is corrected to the actual fuel injection amount (step S36), and the process is performed again from step S31. Note that, as in the case of using an instantaneous soot concentration measurement type soot sensor, two types of correction can be properly used depending on the system.

  As described above, even when the soot sensor of the cumulative soot amount measurement type is used, the same effect as when the soot sensor of the instantaneous soot concentration measurement type is used can be exhibited.

  The present invention is effectively used in various industrial fields such as the automobile industry for manufacturing various vehicles equipped with diesel engines.

It is explanatory drawing which shows typically the control system of the engine system of the diesel vehicle to which this invention is applied. It is an expanded sectional view showing typically DPF used for the present invention. It is a flowchart figure which shows typically the control action in the control system of the engine system of a diesel vehicle at the time of using the soot sensor of an instantaneous soot concentration measurement type. It is a flowchart figure which shows typically the control action in the control system of the engine system of a diesel vehicle at the time of using a soot sensor of a cumulative soot amount measurement type. In the first step, when an instantaneous soot concentration measurement type soot sensor is used, it is a graph schematically showing the relationship between the soot sensor output value and time (when the soot discharge amount is substantially constant). In the first step, when a cumulative soot concentration measurement type soot sensor is used, it is a graph schematically showing the relationship between the soot sensor output value and time (when the soot discharge amount is substantially constant). It is a graph which shows typically the 1st example which correct | amends the initial setting fuel injection quantity of an engine to an actual fuel injection quantity in a 4th step. It is a graph which shows typically the 2nd example which correct | amends the initial setting fuel injection quantity of an engine to an actual fuel injection quantity in a 4th step.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Diesel engine, 21 ... Oxidation catalyst, 22 ... DPF, 36 ... Temperature sensor, 37 ... ECU (an example of a computer), 38 ... Rotation sensor, 39 ... Accelerator opening change sensor, 41a ... Soot sensor of instantaneous soot concentration measurement type 41b, cumulative soot concentration measurement type soot sensor, 42 ... temperature sensor, 43 ... memory, 50 ... mileage sensor.

Claims (15)

A fuel injection amount control method for controlling the fuel injection amount of an engine by correcting the fuel injection amount from an initial set value based on a predetermined condition during traveling,
A first step of measuring a soot emission amount contained in an exhaust gas exhausted from the engine using a soot sensor;
A second step of calculating an estimated soot emission amount based on at least a soot emission estimation element including an engine speed, an exhaust gas temperature, and an initial fuel injection amount of the engine;
A third step of comparing an error determination reference value set based on the soot discharge amount and the estimated soot discharge amount with an error threshold;
When the error determination reference value is equal to or greater than the error threshold, the actual engine injection amount is calculated based on an actual fuel injection amount calculation factor of the engine including at least the soot emission amount, the engine speed, and the exhaust gas temperature. The fuel injection amount is calculated and the initial fuel injection amount of the engine is corrected to the actual fuel injection amount, and then the process returns to the first step, or the error determination reference value is less than the error threshold value. If so, a fourth step of returning to the first step without correcting the initial fuel injection amount of the engine is included. 2. The fuel injection amount control method according to claim 1, wherein a value calculated from a relationship represented by the following expression (1) between the estimated soot discharge amount and the soot discharge amount is used as the error determination reference value.
C = │1- (B / A) │ …… (1)
(In the above formula (1), A represents the soot discharge amount, B represents the estimated soot discharge amount, and C represents the error determination reference value.)   3. The fuel injection amount control method according to claim 1, wherein an instantaneous soot concentration measurement type or a cumulative soot amount measurement type is used as the soot sensor.   4. The fuel injection amount control method according to claim 3, wherein the soot sensor of the instantaneous soot concentration measurement type uses a sensor that measures a charge amount, a light transmission amount or a scattering amount at an instant of the soot.   The fuel injection amount according to claim 3, wherein the soot sensor of the cumulative soot measurement type uses a sensor that measures a resistance change, a temperature change, or a resonance frequency change of a piezoelectric / electrostrictive material in the accumulation until the measurement of the soot. Control method. A fuel injection amount control system capable of controlling a fuel injection amount of an engine from an initial set value by correcting the fuel injection amount based on a predetermined condition during traveling,
A soot emission measuring means capable of measuring the soot emission contained in the exhaust gas discharged from the engine by the soot sensor;
Estimated soot emission amount capable of calculating an estimated soot emission amount estimated based on a soot emission estimation element including at least the engine speed, the exhaust gas temperature, and the initial fuel injection amount of the engine A calculation means;
An error determination reference value / error threshold comparison means capable of comparing an error determination reference value set based on the soot discharge amount and the estimated soot discharge amount with an error threshold;
When the error determination reference value is equal to or greater than the error threshold, the actual engine injection amount is calculated based on an actual fuel injection amount calculation factor of the engine including at least the soot emission amount, the engine speed, and the exhaust gas temperature. The fuel injection amount of the engine is calculated and the initial fuel injection amount of the engine is corrected to the actual fuel injection amount, and then the soot discharge measuring unit returns to the measurement of the soot discharge amount or the error determination is performed. When the reference value is less than the error threshold, the fuel injection amount correcting means that can return to the measurement of the soot discharge amount by the soot discharge amount measuring means without correcting the initial fuel injection amount of the engine. And a fuel injection amount control system. The fuel injection amount control system according to claim 6, wherein the error determination reference value is a value calculated from a relationship represented by the following expression (1) between the estimated soot discharge amount and the soot discharge amount.
C = │1- (B / A) │ …… (1)
(In the above formula (1), A represents the soot discharge amount, B represents the estimated soot discharge amount, and C represents the error determination reference value.)   The fuel injection amount control system according to claim 6 or 7, wherein the soot sensor is of an instantaneous soot concentration measurement type or an accumulated soot amount measurement type.   9. The fuel injection amount control system according to claim 8, wherein the soot sensor of the instantaneous soot concentration measurement type measures a charge amount, a light transmission amount or a scattering amount at an instant of the soot.   9. The fuel injection amount according to claim 8, wherein the soot sensor of the cumulative soot measurement type measures a resistance change, a temperature change, or a resonance frequency change of the piezoelectric / electrostrictive material in the accumulation until the measurement of the soot. Control system. A computer-readable engine fuel injection amount control program for controlling an engine fuel injection amount by correcting from an initial set value based on a predetermined condition during traveling,
A fuel injection amount control program capable of causing the computer to function as the following means (1) to (4).
(1) Soot emission measuring means capable of causing the soot sensor to measure the soot emission contained in the exhaust gas exhausted from the engine;
(2) Estimate capable of calculating an estimated soot emission amount estimated based on a soot emission amount estimation element including at least the engine speed, the exhaust gas temperature, and the initial fuel injection amount of the engine Soot emission calculation means,
(3) an error determination reference value / error threshold comparison means capable of comparing an error determination reference value set based on the soot discharge amount and the estimated soot discharge amount with an error threshold;
(4) When the error determination reference value is greater than or equal to the error threshold, the actual fuel injection amount calculation factor of the engine including at least the soot emission amount, the engine speed, and the exhaust gas temperature is used. Calculating the actual fuel injection amount of the engine and correcting the initial fuel injection amount of the engine to the actual fuel injection amount, and then returning to the measurement of the soot discharge amount by the soot discharge measuring means, or When the error determination reference value is less than the error threshold, the fuel injection that can return to the measurement of the soot discharge amount by the soot discharge amount measuring means without correcting the initial fuel injection amount of the engine Amount correction means. 12. The fuel injection amount control program according to claim 11, wherein the error determination reference value is a value calculated from a relationship represented by the following expression (1) between the estimated soot discharge amount and the soot discharge amount.
C = │1- (B / A) │ …… (1)
(In the above formula (1), A represents the soot discharge amount, B represents the estimated soot discharge amount, and C represents the error determination reference value.)   The fuel injection amount control program according to claim 11 or 12, wherein the soot sensor is of an instantaneous soot concentration measurement type or an accumulated soot amount measurement type.   The fuel injection amount control program according to claim 13, wherein the soot sensor of the instantaneous soot concentration measurement type measures a charge amount, a light transmission amount or a scattering amount at an instant of the soot.   14. The fuel injection amount according to claim 13, wherein the soot sensor of the cumulative soot amount measurement type measures a resistance change, a temperature change, or a resonance frequency change of the piezoelectric / electrostrictive material in the accumulation until the measurement of the soot. Control program.

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