JP2017020436A - Controller for engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correct the ejection amount of a fuel injection valve by properly grasping an individual difference associated with the injection amount.SOLUTION: The present invention relates to a controller for a compression self-injection type engine comprising: a fuel injection valve 13 injecting fuel; fuel injection control means 31 of controlling the fuel injection valve 13; fuel information acquisition means 32 of detecting information on a combustion sound; and combustion storage control means 33 of storing the information on the combustion sound acquired by the combustion information acquisition means 32 and an injection amount of fuel indicated by the fuel injection control means 31. The fuel injection control means 31 instructs the fuel injection valve 13 to perform subordinate injection as fine injection performed in a period of advance before main injection as primary fuel injection in one cycle, the fuel information acquisition means 32 acquires information on change behavior of the combustion sound each time the fuel injection control means 31 decreases an injection amount of subordinate injection a plurality of times from an initial value, and the combustion storage control means 33 determines the smallest injection amount of subordinate injection as a minimum injection amount among regions where loudness of the combustion sound is less than a predetermined determination value.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an engine control device, and more particularly, to an engine control device that performs fuel injection reflecting individual differences of fuel injection valves.

  In general, a fuel injection valve (injector) for injecting fuel has a variation in injection amount due to a dimensional error at the time of manufacture, that is, an individual difference. Injectors that are incorporated in the engine and used are those that have been inspected that the individual difference in the injection amount is equal to or less than a predetermined allowable value and that the predetermined performance is exhibited. .

  Even when the individual difference is less than or equal to the allowable value, learning of the actual injection amount with respect to the indicated value of the injection amount of the injector is performed when the assembly line of the vehicle equipped with the engine is turned off or when the vehicle is subsequently used. Is called. Furthermore, individual differences also occur due to the deterioration of the injector over time, so that learning may be performed at predetermined intervals. These learning contents are utilized for subsequent control, and the injection amount is corrected to reflect individual differences.

  The learning of the individual difference is, for example, the difference between the injection amount instruction value and the actual injection amount due to the relationship between the injector injection amount instruction value and the accompanying generated torque at low revolutions such as idling and deceleration. This can be done by grasping (individual differences).

  For example, in Patent Document 1, in a diesel engine, pilot injection, which is micro injection performed at a timing advanced with respect to main injection, is performed separately from main injection of fuel, and the combustion noise of the engine is generated by performing micro injection. Learning and correction focusing on increasing and decreasing. Specifically, when the minute injection is instructed to the injector and when it is not instructed, if the combustion noise of the engine has not changed (increased) as expected, the injector is instructed. It is determined that the minute injection is not actually performed or is insufficient, and the injector is deteriorated. In this case, correction is performed to increase the injection amount of pilot injection, that is, the minute injection from the initial set value.

JP 2007-187149 A (see paragraphs 0040 and 0041 on page 8 of the specification)

  In the conventional method of learning individual differences of injectors based on the relationship between the indicated value of the injection amount of the injector and the torque generated therewith, the state of the engine at the time of learning, for example, engine temperature, friction, combustion state, etc. The generated torque fluctuates. For this reason, there is a limit to grasping an accurate fuel injection amount.

  In particular, in a diesel engine, when minute injection as sub-injection is performed at a timing advanced with respect to main injection, a more accurate setting is required for the injection amount of the injector. If the injection amount of the injector is not accurate, the injection amount of the fine injection performed as the sub-injection cannot be strictly controlled, which causes an increase in engine noise and deterioration of exhaust gas.

  In the method of Patent Document 1, it is determined whether the deterioration of the injector and the setting value of the fine injection are appropriate or not by comparing the combustion sound when the fine injection is instructed and when it is not instructed. Thus, it is impossible to calculate the lower limit (minimum injection amount) of the minute injection amount that can ensure an appropriate injection amount. Further, when it is determined that the injector is deteriorated based on a change in combustion sound or the like, a specific correction amount related to the injection amount of the injector is not disclosed.

  Therefore, an object of the present invention is to appropriately grasp the individual difference regarding the injection amount of the fuel injection valve and correct the injection amount.

  In order to solve the above-described problems, the present invention provides a fuel injection valve that injects fuel, a fuel injection control unit that controls the fuel injection valve, and a combustion information acquisition unit that detects information on combustion noise from a combustion chamber. And combustion memory control means for storing the information of the combustion sound acquired by the combustion information acquisition means and the fuel injection amount instructed by the fuel injection control means, and the fuel injection control means An instruction is given to the injection valve to perform sub-injection, which is micro-injection performed at a time advanced from the main injection, which is main fuel injection in one cycle, and the combustion information acquisition means is configured so that the fuel injection control means The injection amount of the sub-injection is reduced a plurality of times from the initial value, and information on the change behavior of the combustion sound is acquired each time the sub-injection amount is reduced. The fuel injection valve is adopted a control system of a compression ignition engine to determine the minimum injection quantity can be injected on the basis of the information.

  Here, the combustion memory control means may employ a configuration in which the injection amount of the sub-injection when the combustion noise becomes the minimum is determined as the minimum injection amount from the change behavior information.

  Alternatively, the combustion memory control means determines, as the minimum injection amount, an injection amount with the smallest sub-injection amount in a region where the magnitude of the combustion sound is less than a predetermined determination value from the change behavior information. A configuration can be employed.

  The combustion information acquisition means obtains the combustion sound [N (n−1)] before being reduced from the combustion sound [N (n)] after the injection amount of the sub-injection is reduced from the change behavior information. The subtracted difference [N (n) −N (n−1)] is acquired, and the subsequent combustion sound [N (n)] is equal to or greater than a predetermined determination value and the difference [N (n) −N (n−1). )] Is positive or zero, the minimum injection amount is not updated and the subsequent combustion sound [N (n)] is less than a predetermined determination value or the difference [N (n) −N (n−1)]. ] Is negative, it is possible to adopt a configuration in which the minimum injection amount is reduced and updated.

  Further, it is possible to adopt a configuration in which the acquisition of the change behavior information is terminated when the injection amount of the sub-injection reaches a predetermined limit value. The predetermined limit value can be set to zero injection amount, for example.

  The combustion information acquisition means in each of these configurations is an in-cylinder pressure detection means and a pressure noise conversion means, and the pressure noise conversion means converts the in-cylinder pressure of the combustion chamber acquired by the in-cylinder pressure detection means into information on the combustion sound. A configuration for conversion can be employed.

  The minimum injection amount that can be injected by the fuel injection valve is determined based on the information of the change behavior of the combustion sound while the injection amount of the sub-injection performed before the main injection is reduced from the initial value in one cycle. Therefore, it is possible to appropriately grasp the individual difference regarding the injection amount of the fuel injection valve and correct the injection amount.

It is a mimetic diagram showing the composition of the engine of one embodiment of this invention. It is a flowchart which shows the control of this invention. (A) (b) is a graph which shows the control of this invention.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an overall view showing the configuration of the engine E and the control device for the engine E of the present invention. Engine E is a diesel engine that is a compression self-ignition engine.

  The configuration of the engine E includes an intake passage 1 for sending intake air into a combustion chamber 12 of a cylinder containing a piston 11, an exhaust passage 2 drawn from the combustion chamber 12, a fuel injection valve (injector) 13 facing the combustion chamber 12, and the like. It has. An intake port that is an opening to the combustion chamber 12 of the intake passage 1 and an exhaust port that is an opening to the combustion chamber 12 of the exhaust passage 2 are opened and closed by valves.

  In the intake passage 1, a throttle valve 25 that adjusts the flow passage area of the intake passage 1 from the intake port toward the upstream side, an intake air cooling device (intercooler) 6 that cools the intake air flowing through the intake passage 1, and a turbocharger A compressor 17, a throttle valve 22 that adjusts the flow passage area of the intake passage 1, a case 18 that houses an air cleaner, and the like are provided. In the air cleaner case 18, a temperature sensor capable of detecting the intake air temperature in the pipe is provided as an atmospheric temperature detection device 19.

  In the exhaust passage 2, a turbocharger turbine 7, an exhaust purification unit 8 including a catalyst for removing nitrogen oxide (NOx) and the like in the exhaust, and a silencer (muffler) 9 are provided downstream from the exhaust port. Is provided.

  The turbine 7 in the exhaust passage 2 and the exhaust port and the intake port in the intake passage 1 and the throttle valve 25 communicate with each other by a high-pressure exhaust gas recirculation passage 23 constituting a high-pressure exhaust gas recirculation device. A part of the exhaust gas discharged from the combustion chamber 12 returns to the intake passage 1 as a recirculation gas via the high-pressure exhaust recirculation passage 23. The recirculated gas merges with the intake air in the intake passage 1 in accordance with the opening and closing of the high pressure exhaust recirculation valve 24 provided in the high pressure exhaust recirculation passage 23 and the pressure state in the intake passage 1 as the throttle valve 25 is opened and closed.

  Further, the exhaust purification section 8 and the silencer 9 in the exhaust passage 2 and the compressor 17 and the throttle valve 22 in the intake passage 1 communicate with each other by a low pressure exhaust recirculation passage 20 constituting a low pressure exhaust gas recirculation device. doing. The low pressure exhaust gas recirculation passage 20 is provided with a recirculation gas cooler 10 for cooling the recirculation gas. A part of the exhaust gas discharged from the combustion chamber 12 returns to the upstream side of the intercooler 6 in the intake passage 1 as a recirculation gas via the low pressure exhaust recirculation passage 20. The recirculated gas merges with the intake air in the intake passage 1 according to the pressure state in the intake passage 1 as the low pressure exhaust recirculation valve 21 provided in the low pressure exhaust recirculation passage 20 opens and closes and the throttle valve 22 opens and closes.

  The supply of fuel and air to the engine E, the opening and closing of valves, and other controls are performed by an electronic control unit (Electronic Control Unit) 30 provided in a vehicle equipped with the engine E.

  The electronic control unit 30 includes fuel injection control means 31 that controls the fuel injection valve 13. Further, the electronic control unit 30 includes combustion information acquisition means 32 that detects information of combustion sound from the combustion chamber 12 or a part of the combustion information acquisition means 32. Furthermore, the electronic control unit 30 includes combustion memory control means 33 that stores information on the combustion sound acquired by the combustion information acquisition means 32 and the fuel injection amount instructed by the fuel injection control means 31.

  The fuel injection control means 31 controls normal fuel injection by the fuel injection valve 13 and also controls fuel injection for learning individual differences relating to the fuel injection amount of the fuel injection valve 13. The learned individual difference is utilized for subsequent fuel injection control.

  The fuel injection control means 31 performs a minute operation at a timing advanced from the main injection which is the main fuel injection in one cycle with respect to the fuel injection valve 13 in the normal fuel injection control and the learning fuel injection control. An instruction to perform sub-injection, which is injection, can be performed. In this embodiment, pilot injection that is performed at a timing that is advanced by a larger amount than the main injection is adopted as the sub-injection that is made of minute injection. However, this may be pre-injection that is performed immediately before the main injection.

  The combustion information acquisition unit 32 includes an in-cylinder pressure detection unit 14 provided in a cylinder of the engine E, and a pressure noise conversion unit 34 included in the electronic control unit 30. The in-cylinder pressure detection means 14 is provided facing the combustion chamber 12 and can detect the pressure in the combustion chamber 12. The in-cylinder pressure of the combustion chamber acquired by the in-cylinder pressure detecting means 14 is converted into information on the magnitude of the combustion sound by frequency analysis by the pressure noise converting means 34.

  As a method for converting the in-cylinder pressure of the combustion chamber 12 into the magnitude of the combustion sound, for example, the acquired in-cylinder pressure signal is divided into specific units by Fourier transform to obtain the power (power spectrum) of the combustion sound, Based on the power spectrum, the magnitude (noise level) of the combustion sound can be calculated through predetermined numerical conversion and filter processing.

  As the combustion information acquisition means 32, a sound collecting microphone provided in a cylinder of the engine E may be employed instead of the in-cylinder pressure detection means 14. The sound collection microphone is provided inside or outside the cylinder, and directly acquires information on the magnitude of combustion sound. For this reason, the pressure noise conversion means 34 can be made unnecessary.

  This combustion sound can be evaluated only with a combustion sound in a specific frequency range. For example, the target frequency range can be set to 1 to 4 KHz.

  In the fuel injection control for learning, the fuel injection control means 31 performs control to gradually reduce the injection amount of the sub injection from the initial value f0. During the reduction control, the combustion information acquisition unit 32 reduces the information on the change behavior of the combustion noise, that is, the magnitude of the combustion noise (noise level) while reducing the injection amount of the sub-injection from the initial value f0. Get the change. Since this information is acquired every time the injection amount of the sub-injection is reduced, information on the magnitude of the combustion sound exists corresponding to the information on the individual injection amounts.

  It should be noted that during the period of weight reduction control, a method of continuously acquiring information on the change behavior of the combustion noise and extracting information on the magnitude of the combustion noise corresponding to a specific fuel injection amount from the information. It may be adopted.

  The combustion memory control means 33 determines the minimum injection amount fs that can be injected by the fuel injection valve 13 based on the acquired information on the change behavior of the combustion sound. In this embodiment, the combustion memory control means 33 determines the injection amount of the sub-injection when the magnitude of the combustion sound becomes the minimum as the minimum injection amount fs from the acquired information on the change behavior of the combustion sound.

  Here, the minimum injection amount fs of the fuel injection valve 13 is the minimum unit of the injection amount when fuel is injected by the fuel injection valve 13, that is, the injector. That is, this is the lower limit value of the injection amount that cannot be less than the minimum injection amount fs when fuel is injected.

  In general, the fuel injection valve 13 is opened when an internal solenoid, plunger, or the like is operated by energization to inject fuel from a nozzle at the tip. For this reason, the fuel injection is not performed when the fuel injection valve 13 is not energized, and the fuel injection is started when the energization is started. Further, when the energization to the fuel injection valve 13 is cut off, the fuel injection is finished. Therefore, the fuel injection timing is controlled by the timing when the fuel injection valve 13 is energized. Further, the fuel injection amount is controlled by the energization time (pulse width of the electric signal). By repeating energization / energization of the fuel injection valve 13 during one cycle of the engine E, multi-stage injection that achieves both sub-injection such as pilot injection and pre-injection and main injection that is the main fuel injection is performed. Can do.

  The determination of the minimum injection amount fs is performed by setting the drive instruction continuation time from the electronic control unit 30 to the fuel injection valve 13, that is, the energization time (pulse width of the electric signal) to the fuel injection valve 13. Moreover, the injection period of the fuel injection valve 13 based on the energization time can be calculated using a conversion map from the injection amount to the injection period.

  In particular, in a compression self-ignition engine such as a diesel engine, when performing minute injection as sub-injection at a timing advanced with respect to main injection, a more accurate setting is required for the injection amount of the injector. If the injection amount of the injector is not accurate, the injection amount of the fine injection performed as the sub-injection cannot be strictly controlled, which causes an increase in engine noise and deterioration of exhaust gas. For this reason, such correction of the minimum injection amount fs of the fuel injection valve 13 is effective.

  For example, it is assumed that the minimum injection amount fs is corrected from “3” to “2” by learning control. In this case, it is assumed that the initial adaptation value “3” is being injected during the injection period of the injection amount “2”, and thereafter, the injection period obtained from the indicated injection amount is multiplied by (2 ÷ 3). The injection period can be corrected so that the injection amount becomes the same.

  The control flow of the present invention will be described based on the flowchart of FIG.

  In step S1 of FIG. 2, injection amount learning control is started. This fuel injection control for learning is periodically performed when the assembly line of the vehicle equipped with the engine is turned off or when the vehicle is used thereafter.

  In step S2, the fuel injection amount in the secondary injection (pilot injection) is set to the initial value f0. At this time, the minimum injection amount fs is the initial value f0. For example, the initial value f0 can be a design value that is set when the assembly line of the vehicle is off (see symbol a in FIG. 3A).

In step S3, a noise level N that is information on the magnitude of combustion noise is acquired. In the subsequent step S4, control for reducing the fuel injection amount in the sub-injection is performed. The amount of reduction can be set as appropriate, but here, the amount of reduction is a minute dQpi. Therefore, in the relationship between the injection amount Qpi (n) after being reduced and the injection amount Qpi (n-1) before being reduced,
Qpi (n) = Qpi (n-1) -dQpi
It becomes.

  In step S5, after reducing the fuel injection amount in the sub-injection, the noise level N that is information on the magnitude of the combustion noise is acquired again.

  In step S6, the difference [N (n) −N] obtained by subtracting the combustion sound [N (n−1)] before being reduced from the combustion sound [N (n)] after the fuel injection amount has been reduced. (N-1)] is acquired.

  In this step S6, if the combustion sound [N (n)] after being reduced is not less than the predetermined determination value n0 and the difference [N (n) −N (n−1)] is positive or zero, the minimum The injection amount fs is not updated and the process proceeds to step S8. Further, if the combustion sound [N (n)] after being reduced is less than the predetermined determination value n0 or the difference [N (n) −N (n−1)] is negative, the minimum injection amount is determined in step S7. The fs is decreased and updated, and the process proceeds to step S8. Here, the minimum injection amount fs is set to the reduced injection amount Qpi (n) corresponding to the reduced combustion noise [N (n)].

  The predetermined determination value n0 is set to a value sufficient to determine that the combustion in the combustion chamber 12 in the engine E is stable. If the combustion is not stable, the magnitude of the combustion noise increases, and the combustion noise becomes larger than the predetermined determination value n0.

  However, the predetermined determination value n0 is desirably set lower when the temperature of the engine E, for example, the temperature of the cooling water is low. This is because if the temperature of the engine E is low, the combustion of the fuel in the combustion chamber 12 tends to be slow, and the combustion noise is reduced unless avoidance control such as advance control is performed to suppress it. .

  The control from step S4 to step S7 is performed until the fuel injection amount in the sub injection reaches the predetermined limit value f1. That is, in step S8, when the fuel injection amount in the sub-injection reaches the predetermined limit value f1, the acquisition of the information on the reduction in the fuel injection amount and the magnitude of the combustion noise is terminated. If the fuel injection amount in the sub-injection has not reached the predetermined limit value f1, the process returns to step S4 again, and the acquisition of the information on the reduction in the fuel injection amount and the magnitude of the combustion noise is continued.

  Here, the predetermined limit value f1 is, for example, the limit value of the minimum injection amount fs that cannot be further reduced, that is, the energization time (pulse width of the electric signal) to the fuel injection valve 13 and the corresponding fuel injection. The amount can be set to the minimum value of an area that can be controlled appropriately. However, the predetermined limit value f1 can be set to zero injection amount.

  When the fuel injection amount in the sub-injection reaches the predetermined limit value f1 and the acquisition of the information on the reduction in the fuel injection amount and the magnitude of the combustion sound is completed, the minimum injection amount fs is subjected to a reduction update many times, The fuel injection amount in the sub-injection is set to the smallest injection amount in the region where the volume of the combustion noise is lower than the predetermined determination value n0 (see symbol c in FIG. 3A). In step S9, the determined minimum injection amount fs is stored in the electronic control unit 30 and used for subsequent control.

  When the minimum injection amount fs indicated by reference symbol c in FIG. 3A is set, the occurrence of smoke can be minimized as indicated by reference symbol c in FIG. Note that the symbol b in FIGS. 3A and 3B is an intermediate value between the initial value f0 and the minimum injection amount fs.

  In the above control, the combustion memory control means 33 performs the injection with the smallest fuel injection amount in the sub-injection from the acquired information of the change behavior of the combustion sound, in the region where the magnitude of the combustion sound is lower than the predetermined determination value n0. Although the amount is determined as the minimum injection amount fs, the minimum injection amount fs may be set by another method, for example, as follows.

  That is, when the fuel injection amount in the sub-injection reaches the predetermined limit value f1 and the acquisition of the information on the fuel injection amount reduction and the combustion noise level is completed, the minimum injection amount fs is reduced many times. You may set to the injection quantity of the sub-injection when the magnitude | size of a combustion sound becomes the minimum through an update. This is a method of setting the injection amount of the secondary injection corresponding to the lowest value of the combustion noise in the graph of FIG. 3A to the minimum injection amount fs.

  In this case, in the flowchart of FIG. 2, in step S6, the combustion sound [N (n)] after being reduced is greater than or equal to the predetermined determination value n0, or the difference [N (n) −N (n−1)]. If it is positive or zero, the process proceeds to step S8 without updating the minimum injection amount fs, and the combustion sound [N (n)] after the reduction is less than the predetermined determination value n0 and the difference [N If (n) −N (n−1)] is negative, the minimum injection amount fs is decreased and updated in step S7, and the process proceeds to step S8.

DESCRIPTION OF SYMBOLS 1 Intake passage 2 Exhaust passage 20 Low pressure exhaust recirculation passage 21, 24 Exhaust recirculation valve 22, 25 Throttle valve 23 High pressure exhaust recirculation passage 6 Intake air cooling device (intercooler)
7 Turbine 8 Exhaust gas purification unit 9 Silencer 10 Reflux gas cooler 11 Piston 12 Combustion chamber 13 Fuel injection valve (injector)
14 In-cylinder pressure detection means 17 Compressor 30 Electronic control unit 31 Fuel injection control means 32 Combustion information acquisition means 33 Combustion memory control means 34 Pressure noise conversion means

Claims (7)

A fuel injection valve for injecting fuel;
Fuel injection control means for controlling the fuel injection valve;
Combustion information acquisition means for detecting information of combustion sound from the combustion chamber;
Combustion memory control means for storing information on the combustion sound acquired by the combustion information acquisition means and the fuel injection amount instructed by the fuel injection control means,
The fuel injection control means instructs the fuel injection valve to perform sub-injection, which is minute injection performed at a time advanced from the main injection, which is main fuel injection in one cycle,
The combustion information acquisition means acquires the information on the change behavior of the combustion sound each time the sub-injection amount is reduced while the fuel injection control means reduces the injection amount of the sub-injection a plurality of times from the initial value. ,
The combustion memory control means is a control device for a compression self-ignition engine that determines a minimum injection amount that can be injected by the fuel injection valve based on the acquired information of the change behavior. 2. The control of the compression self-ignition engine according to claim 1, wherein the combustion memory control unit determines an injection amount of the sub-injection when the combustion sound becomes the lowest from the information of the change behavior as the minimum injection amount. apparatus. The combustion memory control means determines, as the minimum injection amount, an injection amount in which the injection amount of the sub-injection is the smallest in a region where the magnitude of the combustion sound is less than a predetermined determination value from the change behavior information. 2. A control device for a compression self-ignition engine according to 1. The combustion information acquisition means obtains the combustion sound [N (n−1)] before being reduced from the combustion sound [N (n)] after the injection amount of the sub-injection is reduced from the change behavior information. Obtain the subtracted difference [N (n) -N (n-1)]
If the subsequent combustion sound [N (n)] is not less than a predetermined determination value and the difference [N (n) −N (n−1)] is positive or zero, the minimum injection amount is not reduced and updated,
The minimum injection amount is reduced and updated if the subsequent combustion sound [N (n)] is less than a predetermined determination value or the difference [N (n) -N (n-1)] is negative. The control device for a compression self-ignition engine according to any one of the above. 5. The control device for a compression self-ignition engine according to claim 4, wherein when the injection amount of the sub-injection reaches a predetermined limit value, the acquisition of the change behavior information is terminated. The control device for a compression self-ignition engine according to claim 5, wherein the predetermined limit value is zero injection amount. The combustion information acquisition means is in-cylinder pressure detection means and pressure noise conversion means,
The control device for a compression self-ignition engine according to any one of claims 1 to 6, wherein the in-cylinder pressure in the combustion chamber acquired by the in-cylinder pressure detecting unit is converted into information on the combustion noise by the pressure noise conversion unit. .

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