JP2016133073A - Injection control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an injection control device which can suppress displacement between a required injection amount and an actual injection amount by performing the correction of an injection amount based on a length of an interval at accuracy higher than that in a prior art.SOLUTION: This injection control device 100 comprises: a signal transmission part 112 which transmits a motion command signal to an injector 12 so that an injection amount of fuel coincides with a required injection amount; a correction amount calculation part 110 which calculates a correction amount on the basis of a length of an interval CP when fuel is injected from the injector 12 a plurality of times; and an error calculation part 111 which calculates an air-fuel ratio displacement amount based on a difference between an actual injection amount from the injector 12 and the required injection amount. After the fuel is injected on the basis of the motion command signal in which the correction amount is reflected, the correction amount is updated on the basis of the calculated air-fuel ratio displacement amount.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an injection control device that controls the operation of an injector provided in an internal combustion engine.

  An injector provided in an internal combustion engine is an electromagnetic valve configured to be switched between opening and closing when a valve body (spool) moves in a cylinder. Fuel pressurized by a pump is supplied to the upstream side of the injector. When the injector is opened, fuel is injected from the injector and supplied to the cylinders of the internal combustion engine.

  The injection control device adjusts the fuel injection amount to match the required injection amount by controlling the opening / closing operation of the injector. Specifically, control is performed to adjust the fuel injection amount to the required injection amount by adjusting the time during which the drive current is supplied to the injector, that is, the time during which the injector is open.

  By the way, in a cylinder of an internal combustion engine, fuel injection from an injector may be performed a plurality of times for each ignition by an ignition plug (divided injection). In such divided injection, a minute amount of fuel is repeatedly injected with a relatively short interval (valve closing time) in between.

  The amount of fuel injected from the injector is roughly proportional to the total time during which the injector is open. However, it is known that when the interval is short, the fuel injection amount changes according to the length of the interval even if the total time during which the injector is open is the same. Such a change in the injection amount is caused by the position and speed of the valve body at the start of the second and subsequent injections being different from the position and speed of the valve body at the start of the first injection. Is.

  Patent Document 1 below describes an injection amount learning device for correcting a deviation between a command injection amount and an actual injection amount according to the length of an interval. In the injection amount learning device, fuel is injected while changing the interval, and a reference interval is determined in advance so that the command injection amount and the actual injection amount coincide. Thereafter, by performing minute injection amount learning (learning for making the correction amount appropriate) based on the reference interval, the deviation between the command injection amount and the actual injection amount is reduced.

JP 2009-191629 A

  However, in the learning method described in Patent Document 1, when obtaining the reference interval, it is necessary to operate the injector while changing the interval over a wide range in advance. For this reason, it is conceivable that combustion becomes unstable and the properties of exhaust gas discharged from the internal combustion engine deteriorate, and the fuel consumption of the internal combustion engine deteriorates.

  In addition, when learning is performed based on a specific reference interval, correction may be performed with relatively high accuracy in areas where the actual interval is close to the reference interval. Regarding the area, it is considered that the accuracy of correction is low. In order to always make the fuel injection amount from the injector substantially coincide with the required injection amount, it is desirable to perform highly accurate correction over a wide range of intervals.

  The present invention has been made in view of such a problem, and an object of the present invention is to correct the injection amount based on the length of the interval with higher accuracy than before, so that the required injection amount and the actual injection amount are obtained. An object of the present invention is to provide an injection control device that can suppress deviation from the above.

  In order to solve the above problems, an injection control device according to the present invention is an injection control device that controls the operation of an injector provided in an internal combustion engine, and the fuel injection amount matches the required injection amount. A signal transmission unit that transmits an operation command signal to the injector, a correction amount calculation unit that calculates a necessary correction amount for the operation of the injector based on the length of an interval when fuel is injected from the injector a plurality of times, and an injector And an error calculation unit that calculates an injection error that is a difference between the actual injection amount and the required injection amount or a value based on the injection amount, and performs fuel injection based on an operation command signal reflecting the correction amount. After that, the correction amount is updated based on the calculated injection error.

  According to such an injection control device, after the fuel is injected based on the operation command signal reflecting the correction amount, the injection error is calculated, and the correction amount is updated based on the injection error. Done. Since it is not necessary to change the interval or adjust the interval to a specific length for the purpose of updating the correction amount, i.e., learning, the properties of the exhaust gas discharged from the internal combustion engine deteriorate. There is no such thing as

  Moreover, since the correction amount can be updated to reduce the injection error regardless of the length of the interval, the correction amount is frequently updated (learning). Will be executed. For example, even if the state of the injector (such as the frictional resistance received by the valve body) changes, the correction amount is immediately updated in response to the change, so that the injection amount is prevented from deviating from the required injection amount. .

  According to the present invention, there is provided an injection control device capable of suppressing a deviation between a required injection amount and an actual injection amount by performing correction of the injection amount based on the length of the interval with higher accuracy than before. can do.

It is a figure which shows typically the whole structure of the injection control apparatus which concerns on embodiment of this invention. It is a time chart for demonstrating operation | movement of an injector. It is a time chart for demonstrating operation | movement of an injector. It is a graph which shows the relationship between an interval and fuel injection quantity. It is a flowchart which shows the flow of the process performed by the injection control apparatus shown by FIG. It is a flowchart which shows the flow of the process performed by the injection control apparatus shown by FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In order to facilitate the understanding of the description, the same constituent elements in the drawings will be denoted by the same reference numerals as much as possible, and redundant description will be omitted.

  An injection control apparatus 100 according to an embodiment of the present invention will be described with reference to FIG. The injection control device 100 is attached to a vehicle GC including the internal combustion engine 10 and is a device (ECU) for controlling the overall operation of the vehicle GC (including the operation of the injector 12 provided in the internal combustion engine 10). It has become.

  The configuration of the vehicle GC will be described first. The vehicle GC includes an internal combustion engine 10, an intake pipe 20, an exhaust pipe 30, and a fuel supply pipe 40.

  The internal combustion engine 10 is a four-cycle reciprocating engine having a plurality of cylinders 11 and generates driving force by burning fuel in the cylinders. Since the configurations of the cylinders 11 are substantially the same, only a single cylinder 11 is shown in FIG.

  Each cylinder 11 is provided with an injector 12 and a spark plug 13. The injector 12 is a device for injecting fuel and supplying it to the cylinder 11. In the present embodiment, fuel injection from the injector 12 is performed in the combustion chamber SP. That is, the internal combustion engine 10 is an in-cylinder direct injection internal combustion engine.

  The injector 12 is an electromagnetic valve having a configuration in which opening and closing is switched by moving a valve body (spool) (not shown) in a cylinder. The injector 12 is supplied with high-pressure fuel from a fuel supply pipe 40 described later. When the valve body moves and the injector 12 is opened, fuel is injected from the injector 12 and fuel is supplied into the combustion chamber SP formed in the cylinder 11. When the valve body returns to the original position and the injector 12 is closed, the fuel injection from the injector 12 is stopped. The opening / closing operation of the injector 12 is controlled by the injection control device 100.

  The spark plug 13 ignites the fuel by performing a spark discharge inside the combustion chamber SP. The operation (discharge) of the spark plug 13 is also controlled by the injection control device 100 in the same manner as the opening / closing operation of the injector 12.

  The intake pipe 20 is a pipe for supplying air to the internal combustion engine 10. The intake pipe 20 is provided with an air cleaner 21, an air flow meter 22, a throttle valve 23, and a surge tank 25 in order from the upstream side (left side in FIG. 1). The internal combustion engine 10 is connected to the downstream end (right side in FIG. 1) of the intake pipe 20.

  The air cleaner 21 is a filter for removing foreign substances from the air introduced from the outside of the vehicle GC. The air flow meter 22 is a flow meter for measuring the flow rate of air supplied to the internal combustion engine 10 through the intake pipe 20. The flow rate measured by the air flow meter 22 is input to the injection control device 100.

  The throttle valve 23 is a flow rate adjustment valve for adjusting the flow rate of air passing through the intake pipe 20. The opening degree of the throttle valve 23 is adjusted according to the amount of operation of an accelerator pedal (not shown) provided in the vehicle GC, thereby adjusting the air flow rate. The throttle valve 23 is provided with an opening degree sensor 24. The opening degree of the throttle valve 23 is measured by the opening degree sensor 24 and inputted to the injection control device 100.

  The surge tank 25 is a box-shaped container formed in the middle of the intake pipe 20. The intake pipe 20 is branched into a plurality of downstream sides of the surge tank 25, and each branched flow path is connected to each cylinder 11. The internal space of the surge tank 25 is wider than the internal space in other portions of the intake pipe 20. The surge tank 25 prevents the pressure fluctuation caused by one cylinder 11 from affecting other cylinders 11. The surge tank 25 is provided with a pressure sensor 26. The pressure in the intake pipe 20 is measured by the pressure sensor 26 and input to the injection control device 100.

  The exhaust pipe 30 is a pipe for discharging the exhaust gas generated in each cylinder 11 of the internal combustion engine 10 to the outside. The upstream end (the left side in FIG. 1) of the exhaust pipe 30 is connected to the internal combustion engine 10. A catalytic converter 31 for purifying exhaust gas is provided in the middle of the exhaust pipe 30 (on the downstream side of the internal combustion engine 10).

  An air-fuel ratio sensor 32 is provided in a portion upstream of the catalytic converter 31 in the exhaust pipe 30, and an oxygen sensor 33 is provided in a portion downstream of the catalytic converter 31. These are all sensors for monitoring the oxygen concentration of the exhaust gas passing through the exhaust pipe 30, and the measurement results are input to the injection control device 100. The injection control device 100 controls the amount of fuel injection from the injector 12 based on the measurement result of the air-fuel ratio sensor 32 or the like so that the combustion in the internal combustion engine 10 is performed at the stoichiometric air-fuel ratio.

  The fuel supply pipe 40 is a pipe for supplying fuel to the injector 12. The fuel supply pipe 40 has an upstream end connected to a fuel tank (not shown) provided in the vehicle GC, and a downstream end connected to the injector 12. In the middle of the fuel supply pipe 40, a pump 41 is provided for pressurizing the fuel and feeding it to the injector 12.

  The fuel pressure is increased by the operation of the pump 41 on the downstream side (injector 12 side) of the pump 41 inside the fuel supply pipe 40. For this reason, when the valve body of the injector 12 is operated and the injector 12 is opened, fuel is immediately injected from the injector 12.

  Between the pump 41 and the injector 12, a pressure sensor 42 for measuring the fuel pressure (fuel pressure) inside the fuel supply pipe 40 is disposed. The fuel pressure measured by the pressure sensor is input to the injection control device 100.

  The configuration of the injection control device 100 will be described. The injection control device 100 is a computer system that includes a CPU, a ROM, a RAM, and an input / output interface. The injection control device 100 includes a correction amount calculation unit 110, an error calculation unit 111, and a signal transmission unit 112 as functional control blocks. The functions of these control blocks will be described together when the details of the processing performed by the injection control device 100 are described later.

  The operation of the injector 12 will be described with reference to FIG. FIG. 2A shows an operation command signal transmitted from the correction amount calculation unit 110 to the injector 12. The operation command signal is a signal transmitted from the signal transmission unit 112 to the injector 12 as a voltage change. When the injector 12 is closed, the operation command signal is set to the voltage V0. When the injector 12 is opened, the operation command signal is set to the voltage V1.

  FIG. 2B shows a change in the position of the valve body in the injector 12 when the operation command signal as shown in FIG. 2A is transmitted. In FIG. 2B, the position of the valve body when the injector 12 is in the fully closed state is shown as “position P0”. Further, the position of the valve body when the injector 12 is fully opened is indicated as “position P1”.

  In the example shown in FIG. 2, at time t0, the operation command signal changes from voltage V0 to voltage V1, and accordingly, the valve body starts to move from position P0 to position P1. Thereafter, the valve body reaches the position P1 at time t1, and the injector 12 is fully opened.

  At time t10 after time t1, the operation command signal changes from voltage V1 to voltage V0, and accordingly, the valve body starts to move from position P1 to position P0. Thereafter, at time t11, the valve body reaches the position P0, and the injector 12 is fully closed.

  When the valve body reaches the position P0 (time t11), the valve body collides with a valve seat (not shown) formed inside the casing of the injector 12. At this time, the valve body may bounce off the position P0 for a short period of time due to the impact.

  In the present embodiment, the fuel injection from the injector 12 is performed in a plurality of times for one ignition by the ignition plug 13. Hereinafter, such fuel injection is also referred to as “split injection”.

  At time t20 after time t11, the second injection in the divided injection is performed. Similar to the first injection, the operation command signal changes from the voltage V0 to the voltage V1 at time t20, and accordingly, the valve body starts to move from the position P0 to the position P1. Thereafter, at time t21, the valve body reaches the position P1, and the injector 12 is fully opened. At time t30 after time t21, the operation command signal changes from voltage V1 to voltage V0, and the valve body is closed accordingly.

  When such divided injection is performed, the fuel injected little by little spreads in a wide range in the combustion chamber SP due to the flow of intake air. Thereby, ignitability and combustion efficiency can be improved.

  The amount of fuel injected from the injector 12 is approximately proportional to the time during which the operation command signal is at the voltage V1. In the example of FIG. 2, the sum of the length of the period from time t0 to time t10 (first valve opening period OP1) and the length of the period from time t20 to time t30 (second valve opening period OP2). Generally proportional. The injection control device 100 controls the amount of fuel injected from the injector 12 by adjusting the lengths of the valve opening period OP1 and the valve opening period OP2.

  When a period from time t10 to time t20, that is, a period during which an operation command signal for closing the injector 12 during the divided injection is transmitted (hereinafter referred to as “interval CP”) is sufficiently long. The fuel injection amount is not affected by the length of the interval CP. On the other hand, when the length of the interval CP is short, it is known that the fuel injection amount changes according to the length of the interval CP.

  Such a phenomenon will be described with reference to FIG. FIG. 3 is a time chart similar to FIG. 2, but differs from FIG. 2 only in that the length of the interval CP is shortened.

  When the first injection in the divided injection is performed, at time t10, the operation command signal changes from the voltage V1 to the voltage V0, and accordingly, the valve body moves from the position P1 to the position P0. start. However, in the example of FIG. 3, the interval CP ends before the valve element reaches the position P0, and the operation command signal changes from the voltage V0 to the voltage V1 again at time t20.

  The valve body changes its moving direction without reaching the fully closed position P0, and starts moving toward the position P1. Thereafter, at time t21, the valve body reaches the position P1, and the injector 12 is fully opened.

  In the example shown in FIG. 3, the amount of fuel injected from the injector 12 in the interval CP is greater than the injection amount in the case shown in FIG. The injection control device 100 opens the valve opening period OP1 and the opening period so that the actual injection amount matches the fuel injection amount (hereinafter also referred to as “required injection amount”) necessary for properly operating the internal combustion engine 10. Each length of valve period OP2 is adjusted. However, in the example of FIG. 3, since the interval CP is shortened, the actual fuel injection amount becomes larger than the required injection amount. When the interval CP is further shortened, the deviation between the two is further increased.

  In addition, after the first injection, when the direction of movement of the valve body is changed immediately before returning to the position P0, and again toward the position P1, the fuel injection amount becomes smaller than the required injection amount. Sometimes. This is because after the first injection is performed, the valve body does not collide with the valve seat, and the deceleration and the direction change are performed slowly.

  FIG. 4 shows the relationship between the length of the interval CP and the injection amount. The horizontal axis of the graph shown in FIG. 4 is the length of the interval CP, and the vertical axis is the actual fuel injection amount minus the required injection amount (injection deviation amount). As indicated by the line GL1, in the region where the interval CP is short, the injection amount increases as the interval becomes shorter. Further, depending on the length of the interval CP, the actual fuel injection amount may be less than the required injection amount, and the sign of the injection deviation amount may be negative. If the interval CP is sufficiently long, the actual fuel injection amount matches the required injection amount.

  Further, the relationship between the length of the interval CP and the injection amount (injection deviation amount) as described above also varies depending on individual differences of the injectors 12. A line GL2 in FIG. 4 is an injection deviation amount when the movement resistance received by the valve body in the injector 12 is relatively large and the movement speed of the valve body is slow. A line GL3 in FIG. 4 is an injection deviation amount when the movement resistance received by the valve body in the injector 12 is relatively small and the movement speed of the valve body is high.

  In the injection control apparatus 100 according to the present embodiment, the operation of the injector 12 is corrected according to the length of the interval CP so that the fuel injection amount is always close to the required injection amount. Hereinafter, the correction will be described.

  Prior to the injection of fuel from the injector 12, the injection control device 100 determines an injection target value for the fuel injection amount (not necessarily equal to the required injection amount), and corresponds to the injection target value of the injector 12. The length of the valve opening period is set. For this reason, as a specific method for correcting the operation of the injector 12 for the purpose of suppressing the amount of injection deviation, either the injection target value in the second injection or the second valve opening period OP2 is defined as an interval. Correction may be made in accordance with CP, and the actual injection amount may be changed accordingly.

  Hereinafter, an example in which the correction amount as a value to be added to the injection target value is calculated according to the interval CP will be described. The correction amount is not limited to this, and may be calculated as a value to be multiplied with the injection target value. Further, it may be calculated as a value added to or multiplied by the valve opening period OP2.

The correction amount is calculated by the following equation (1).
Correction amount = fl × g (x) × f (x × i) (1)

  The reference correction amount fl described as “fl” in Equation (1) is a value obtained in advance for each injector 12 as a correction amount to be set when the interval CP is sufficiently large. It can be said that the reference correction amount fl is a portion that does not change with the interval CP among the values to be added to the injection target value.

  The reference correction amount fl is determined in advance by learning based on the actually measured value of the air-fuel ratio. That is, by adjusting the injection target value so that the actual measured value of the air-fuel ratio of the cylinder 11 (the value calculated based on the measurement results of the air-fuel ratio sensor 32 and the oxygen sensor 33) matches the theoretical air-fuel ratio. It is determined in advance. The injection amount in the fully opened state of the injector 12 changes due to individual variations of the injectors 12, but the influence of the solid variation is reduced by appropriately setting the reference correction amount fl for each injector 12. .

  The first function f written as “f (x × i)” in the equation (1) is obtained by reversing the sign of the vertical axis of the function indicating the line GL1 in the graph of FIG. For example, when the interval CP is short, the value of the first function f is a negative value, and the absolute value thereof becomes larger as the interval CP is shorter. This indicates that when the interval CP is short, the actual injection amount increases, so that the correction amount to be added to the injection target value becomes a negative value.

  I in Formula (1) is the length of the interval CP. X in Equation (1) is a learning value that is a correction parameter, and 1 is set as its initial value. Hereinafter, the learning value is also referred to as “learning value x”. That is, the first function f is prepared as a function of the learning value x multiplied by the length of the interval CP. The first function f is obtained by experiments or simulations performed in advance, and is stored as a table in the storage device of the injection control device 100.

  As already described, the relationship between the length of the interval CP and the injection amount (injection deviation amount) is not uniquely determined, but varies depending on the moving speed of the valve body inside the injector 12 and the like. For this reason, in the present embodiment, the shape of the function on the left side of the above equation (1) is changed by changing the learning value x, whereby an appropriate correction amount for each individual injector 12 (for each cylinder 11). Is adjusted (learning) so as to be calculated.

  For example, if it is determined that the absolute value of the correction amount is too small because the moving speed of the valve body is relatively small, the learning value x may be changed to a smaller value. If it is determined that the absolute value of the correction amount is too large because the moving speed of the valve body is relatively high, the learning value x may be changed to a larger value.

  The second function g expressed as “g (x)” in the expression (1) is for adjusting a change in the correction amount when the learning value x is changed. The second function g is expressed as a function of the learning value x.

  When the second function g does not exist in the expression (1), when the learning value x is changed, a graph indicating the correction amount (inverted vertical axis of the graph shown in FIG. 4) is the first function. The change in f causes expansion / contraction only along the horizontal axis. For this reason, for example, there is a possibility that the correction amount corresponding to the line GL1 cannot be changed to match the correction amount corresponding to the line GL2.

  Therefore, in the formula (1), the second function g is multiplied by the first function f. When the learning value x is changed, the graph indicating the correction amount expands and contracts along both the vertical axis and the horizontal axis. For this reason, the relationship between the interval CP and the correction amount can be easily and appropriately adjusted by changing only one parameter (learned value x). The second function g multiplied for such a purpose can be referred to as a “correction gain table” for adjusting the enlargement ratio along the vertical axis of the graph shown in FIG.

  The specific content of the process performed by the injection control apparatus 100 will be described with reference to FIG. A series of processes shown in FIG. 5 are repeatedly executed at predetermined intervals.

  In the first step S01, it is determined whether or not learning of the reference correction amount fl has been completed. The learning of the reference correction amount fl is performed for each injection amount range set in advance as a range of a plurality of injection target values. That is, the reference correction amount fl corresponding to each of the plurality of injection amount ranges is determined by learning based on the actually measured value of the air-fuel ratio.

  Here, the entire injection amount range in which the injector 12 is temporarily fully opened (the valve body reaches the position P1) is referred to as a “full lift region”. In contrast, the entire injection amount range in which the injection target value is relatively small and the injector 12 is closed before the injector 12 is fully opened (before the valve body reaches the position P1). , Referred to as “partial lift area”.

  In step S01, it is determined whether or not learning of the reference correction amount fl is completed at least in the full lift region. If the learning of the reference correction amount fl is completed, the process proceeds to step S02.

  If the learning of the reference correction amount fl has not been completed, the series of processes shown in FIG. In this case, the fuel injection from the injector 12 is performed without changing the learning value x as described later. That is, the signal transmission unit 112 transmits an operation command signal to the injector 12 so that the injection amount obtained by adding the correction value calculated by the equation (1) to the injection target value.

  In step S02, it is determined whether or not split injection is performed. If split injection is performed, the process proceeds to step S03. If the divided injection is not performed, the relationship between the length of the interval CP and the necessary correction amount cannot be adjusted (learned), so the series of processes shown in FIG.

  In step S03, a correction amount is calculated. As described above, the correction amount is calculated by the equation (1) using the length of the interval CP, the learning value x (initial value is 1), and the reference correction amount fl calculated in advance. The correction amount is calculated by the correction amount calculation unit 110.

  In step S04 following step S03, the calculated correction amount is adjusted. In the present embodiment, a correction amount range to be added to the injection target value (hereinafter, this range is also referred to as “appropriate range”) is predetermined. The adjustment of the correction amount refers to a process of correcting the correction amount calculated in step S03 as necessary so as to become a value within an appropriate range.

  The injection amount in the injector 12 changes according to the length of the interval CP. However, it is impossible to exceed the injection amount (maximum injection amount) when the valve is always open during the interval CP. The upper limit value of the appropriate range is set as a value obtained by subtracting the injection target value from the maximum injection amount.

  In addition, it is impossible that a value obtained by adding the injection amount to the injection target value becomes a negative value. The lower limit value of the appropriate range is a negative value, and the absolute value is set as a value equal to the injection target value.

  FIG. 6 shows the details of specific processing (adjustment) executed in step S04. In the first step S410, it is determined whether or not the correction amount calculated in step S03 is smaller than the upper limit value of the appropriate range (hereinafter simply referred to as “upper limit value”). If the correction amount is greater than or equal to the upper limit value, the process proceeds to step S411.

  In step S411, the value of the correction amount is set to be equal to the upper limit value. In step S412, following step S411, the increase prohibition flag is set to 1. The increase prohibition flag is a storage location of information provided in the storage device of the injection control device 100. When the increase prohibition flag is set to 1, a change in the learning value x that further increases the correction amount is prohibited. After the process of step S412 is performed, it transfers to step S420.

  In step S411, instead of setting the upper limit value as the correction amount value, an initial value set in advance as a value within the appropriate range may be set as the correction amount value. In this case, the increase prohibition flag is not set in step S412.

  In step S410, if the correction amount calculated in step S03 is smaller than the upper limit value, the process proceeds to step S413. In step S413, 0 is set to the increase prohibition flag. That is, the learning value x is allowed to be changed so that the correction amount is further increased. After the process of step S413 is executed, the process proceeds to step S420.

  In step S420, it is determined whether or not the correction amount is larger than the lower limit value of the appropriate range (hereinafter simply referred to as “lower limit value”). If the correction amount is less than or equal to the lower limit value, the process proceeds to step S421.

  In step S421, the correction amount value is set to be equal to the lower limit value. In step S422 following step S421, 1 is set in the reduction prohibition flag. Similar to the increase prohibition flag, the decrease prohibition flag is a storage location of information provided in the storage device of the injection control apparatus 100. When the reduction prohibition flag is set to 1, the change of the learning value x is prohibited so that the correction amount is further reduced. After the process of step S422 is executed, the series of processes shown in FIG. 6 is terminated, and the process proceeds to step S05 (FIG. 5).

  In step S421, instead of setting the lower limit value as the correction amount value, an initial value set in advance as a value within the appropriate range may be set as the correction amount value. In this case, the reduction prohibition flag is not set in step S422.

  If the correction amount is larger than the lower limit value in step S420, the process proceeds to step S423. In step S423, 0 is set to the reduction prohibition flag. That is, the learning value x is allowed to be changed so that the correction amount is further reduced. After the process of step S423 is executed, the series of processes shown in FIG. 6 is terminated, and the process proceeds to step S05 (FIG. 5).

  Returning to FIG. In step S05 following step S04, fuel injection from the injector 12 is performed. That is, the signal transmission unit 112 transmits the operation command signal to the injector 12 so that the injection amount from the injector 12 becomes an injection amount obtained by adding the correction value calculated by the equation (1) to the injection target value. Is done from.

  The processing performed in step S06 and subsequent steps subsequent to step S05 is processing for determining whether or not the current learning value x is appropriate and changing the learning value x as necessary.

  In step S06, it is determined whether or not the absolute value of the correction amount is larger than a predetermined first threshold value. When the absolute value of the correction amount is larger than the first threshold value, the process proceeds to step S07. If the absolute value of the correction amount is equal to or smaller than the first threshold value, the series of processes shown in FIG. 5 is terminated without changing the learning value x.

  In step S07, the absolute value of the correction amount divided by the injection target value (the ratio of the correction amount to the injection target value, hereinafter also referred to as “correction ratio”) is greater than a predetermined second threshold value. It is determined whether or not. When the correction ratio is larger than the second threshold value, the process proceeds to step S08. If the correction ratio is less than or equal to the second threshold value, the series of processes shown in FIG. 5 is terminated without changing the learning value x.

  In step S08, the air-fuel ratio value (actual air-fuel ratio) in the cylinder 11 is calculated. The calculation is performed individually for each cylinder 11 based on the measurement results of the air-fuel ratio sensor 32 and the oxygen sensor 33.

  In step S09 following step S08, the absolute value (hereinafter also referred to as “air-fuel ratio deviation amount”) obtained by subtracting the actual air-fuel ratio calculated in step S08 from a predetermined target air-fuel ratio (for example, theoretical air-fuel ratio). Is calculated, and it is determined whether the air-fuel ratio deviation amount is larger than a predetermined third threshold value. The calculation of the air-fuel ratio deviation amount is performed by the error calculation unit 111.

  When the air-fuel ratio deviation amount is larger than the third threshold value, the process proceeds to step S10. When the air-fuel ratio deviation amount is equal to or smaller than the third threshold value, it means that the current value of the learning value x is relatively appropriate. Therefore, the series of the values shown in FIG. The process ends.

  The “air-fuel ratio deviation amount” calculated as described above can be said to be based on the difference between the actual injection amount from the injector 12 and the required injection amount (injection error).

  In step S10, the learning value x is changed based on the injection deviation amount calculated in step S09. The learning value x is changed so that the air-fuel ratio deviation is as small as possible after the next injection from the injector 12. In the present embodiment, when it is determined that the absolute value of the correction amount is too small based on the air-fuel ratio deviation amount, the learning value x is changed to a smaller value. On the other hand, when it is determined that the absolute value of the correction amount is too large based on the air-fuel ratio deviation amount, the learning value x is changed to a larger value. The relationship between the air-fuel ratio deviation amount and the learned value x to be changed is stored in advance in the storage device of the injection control device 100 as a map.

  Note that when the increase prohibition flag is set to 1 even though the learning value x needs to be changed so as to further increase the correction amount, the learning value is not changed in step S10. Even when the learning value x needs to be changed so that the correction amount is further reduced, the learning value is not changed in step S10 even when 1 is set in the reduction prohibition flag.

  Thereafter, the correction amount is calculated by the equation (1) based on the changed learning value x, and fuel is injected based on the operation command signal reflecting the correction amount.

  As described above, according to the injection control apparatus 100 according to the present embodiment, after the fuel is injected from the injector 12 based on the operation command signal reflecting the correction amount (step S05), the air-fuel ratio shift The amount (injection error) is calculated (step S09), and the correction amount is updated based on the air-fuel ratio deviation amount (step S10). For the purpose of updating the correction amount, that is, learning, it is not necessary to change the interval CP variously or adjust the interval CP to have a specific length. There is no such thing as deteriorating the properties.

  Further, regardless of the length of the interval CP, it is possible to update the correction amount for reducing the air-fuel ratio deviation amount (injection error). Learning) is performed at a relatively high frequency. For example, even if the state of the injector 12 (such as the frictional resistance received by the valve body) changes, the correction amount is immediately updated in response to the change, so that the injection amount is prevented from deviating from the required injection amount. The

  Incidentally, the air-fuel ratio deviation amount calculated based on the measurement results of the air-fuel ratio sensor 32 and the oxygen sensor 33 includes an error. For this reason, it is conceivable that the learned value x is changed based on the air-fuel ratio deviation amount including an error even though it is not actually necessary to change the learned value x.

  However, in the present embodiment, when the absolute value of the correction amount is equal to or smaller than the first threshold value, the learning value x is not changed (step S06). Further, the learning value x is not changed even when the correction ratio is equal to or smaller than the second threshold value (step S07). This prevents an unnecessary change in the learning value x based on the error in the air-fuel ratio deviation amount.

  The ease of operation of the valve body in the injector 12 tends to vary depending on the fuel pressure upstream of the injector 12, that is, the measured value of the pressure sensor 42. Therefore, the correction amount calculated in step S03 of FIG. 5 may be changed based on the measurement value of the pressure sensor 42.

  When the injector 12 having a structure in which the valve body becomes harder to operate as the fuel pressure upstream of the injector 12 becomes larger, the calculated value of the pressure sensor 42 increases as the measured value of the pressure sensor 42 increases. The first function f may be used so as to increase the correction amount.

  For example, a plurality of first functions f may be prepared in advance, and an appropriate first function f may be selected based on the measurement value of the pressure sensor 42 and used for calculating the correction amount. Further, the first function f may be prepared as a function of the measured value of the pressure sensor 42 instead of a function of only the interval CP and the learning value x.

  The learning value x may be set and updated (learned) as a unique value for each fuel pressure range preset as a fuel pressure range divided into a plurality. When the fuel pressure measured by the pressure sensor 42 belongs to an unlearned fuel pressure region, the correction value is calculated in step S03 by using the average value of the respective learned values x for the other fuel pressure regions. Should just be done.

  In the present embodiment, the correction amount calculated in step S03, the air-fuel ratio calculated in step S08, the injection deviation amount calculated in step S09, and the learning value changed in step S10 are all for each cylinder 11. Are calculated individually as values of.

  However, when it is difficult to calculate the air-fuel ratio individually for each cylinder 11, an aspect in which the entire air-fuel ratio of the internal combustion engine 10 is calculated as one value may be employed.

  The embodiments of the present invention have been described above with reference to specific examples. However, the present invention is not limited to these specific examples. In other words, those specific examples that have been appropriately modified by those skilled in the art are also included in the scope of the present invention as long as they have the characteristics of the present invention. For example, the elements included in each of the specific examples described above and their arrangement, materials, conditions, shapes, sizes, and the like are not limited to those illustrated, but can be changed as appropriate. Moreover, each element with which each embodiment mentioned above is provided can be combined as long as technically possible, and the combination of these is also included in the scope of the present invention as long as it includes the features of the present invention.

10: internal combustion engine 11: cylinder 12: injector 32: air-fuel ratio sensor 42: pressure sensor 100: injection control device 110: correction amount calculation unit 111: error calculation unit 112: signal transmission unit

Claims (15)

An injection control device (100) for controlling the operation of an injector (12) provided in an internal combustion engine (10),
A signal transmission unit (112) for transmitting an operation command signal to the injector so that the fuel injection amount matches the required injection amount;
A correction amount calculation unit (110) that calculates a necessary correction amount for the operation of the injector based on the length of the interval when fuel is injected from the injector a plurality of times;
A difference between the actual injection amount from the injector and the required injection amount, or an error calculation unit that calculates an injection error that is a value based thereon,
An injection control apparatus, wherein after the fuel is injected based on the operation command signal reflecting the correction amount, the correction amount is updated based on the calculated injection error. The correction amount is
As the correction amount to be set when the interval is sufficiently large, a reference correction amount obtained by learning in advance,
A first function that is a function of a learning value that is a correction parameter multiplied by the length of the interval;
It is calculated by multiplying the second function which is a function of the learning value, respectively,
The injection control apparatus according to claim 1, wherein the correction amount based on the injection error is updated by changing a value of the learning value. When it is determined that the absolute value of the correction amount is too small based on the calculated injection error, the learning value is changed to a smaller value,
3. The learning value according to claim 2, wherein when the absolute value of the correction amount is determined to be too large based on the calculated injection error, the learning value is changed to a larger value. Injection control device. The correction amount is added to or multiplied by a target value of the fuel injection amount from the injector,
The correction amount is updated based on the injection error only when the calculated correction amount is larger than a predetermined first threshold and the ratio of the correction amount to the target value is larger than a predetermined second threshold. The injection control device according to claim 3, wherein:   The injection control apparatus according to claim 3, wherein the correction amount based on the injection error is updated only when the calculated injection error is larger than a predetermined third threshold.   The injection control device according to claim 3, wherein the correction amount is calculated to be a value within a predetermined range set in advance.   The injection control device according to claim 6, wherein when the correction amount is equal to an upper limit value of the predetermined range, the learning value is not changed so that the correction amount further increases. .   The injection control device according to claim 6, wherein when the correction amount is equal to a lower limit value of the predetermined range, the learning value is not changed such that the correction amount further decreases. .   When the correction amount that matches either the upper limit value or the lower limit value of the predetermined range is calculated, an initial value predetermined as a value within the predetermined range is set as the correction amount. The injection control device according to claim 6.   The injection control device according to claim 3, wherein the learning value is not changed until learning for obtaining the reference correction amount is completed.   4. The injection control apparatus according to claim 3, wherein the calculated correction amount varies depending on the fuel pressure upstream of the injector.   11. The injection control according to claim 10, wherein a plurality of the first functions are prepared in advance, and an appropriate first function corresponding to the pressure is selected and used for calculating the correction amount. apparatus. The injection control apparatus according to claim 10, wherein the first function is a function of the pressure.   The injection control apparatus according to claim 10, wherein the correction amount is calculated as a larger value as the fuel pressure upstream of the injector is larger. The internal combustion engine includes a plurality of cylinders (11),
Both the calculation of the correction amount by the correction amount calculation unit and the update of the correction amount based on the injection error are performed individually for each of the injectors provided for each cylinder, The injection control device according to claim 1.

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