Patent Grant
11346311
This application is the U.S. national phase of International Application No. PCT/JP2016/082637 filed Nov. 2, 2016, which designated the U.S. and claims priority to Japanese Application No. 2015-233462 filed on Nov. 30, 2015 and Japanese Application No. 2016-158557 filed on Aug. 12, 2016, the entire contents of each of which are incorporated herein by reference.
The present disclosure relates to a fuel injection control device of an internal combustion engine.
It is known that an electromagnetic solenoid fuel injector is used to supply a fuel to each of cylinders of an internal combustion engine mounted to a vehicle. In the above fuel injector, a fuel injection time point and a fuel injection quantity is controlled by driving a valve (needle) in a valve-opening direction to control an energization time point and an energization time interval of a coil in a main body of the fuel injector.
It is known as a driving technology of the fuel injector that a coil applying voltage is initially a high voltage in a valve-opening state and then switched to a low voltage. In this case, a valve-opening responsivity is improved by an application of the high voltage, and then the fuel injector is driven by a low power by switching to the low voltage. A switching from the high voltage to the low voltage is executed based on a sensed current sensed by a current detection circuit. When it is determined that the sensed current has reached a target peak value that is predetermined, a switching of an applied voltage is executed.
Since a machinery difference exists in a fuel injection device, a variation occurs in an actual driving current. A variation occurs in the fuel injection quantity due to the variation of the driving current. According to Patent Literature 1, a machinery difference quantity of the actual driving current is previously stored in a storage unit, and a target driving current is corrected based on the machinery difference quantity.
Patent Literature 1: JP2014-5740A
However, in a multiple-cylinder internal combustion engine, since time intervals of the fuel injections in fuel injectors of each of cylinders overlap each other, it is assumed that plural fuel injectors are divided into plural groups and the fuel injectors in each of the groups are driven. When a driving state of the fuel injector is controlled based on the sensed current of the fuel injector, it is assumed that a current detection circuit is provided to each of the groups. In this case, when a characteristic variation occurs at the current detection circuits of the groups, the driving states of the fuel injectors cannot be evenly controlled, and a variation of the fuel injection quantity may occur. When the driving current of each of the fuel injectors cannot be properly obtained, a variation of the valve-opening responsivity of the fuel injector may occur or a variation of a valve body lifting quantity may occur. Then, it is possible that an excess or a deficiency of the fuel injection quantity occurs. The above matters may be improved.
The present disclosure is made in view of the above matters, and it is an object of the present disclosure to provide a fuel injection control device of an internal combustion engine which can improve an optimization of a driving of a fuel injector and can properly control a fuel injection quantity.
According to the present disclosure, the fuel injection control unit is applied to a fuel injection system of the internal combustion engine, the fuel injection system including fuel injectors, driving circuits that drive the fuel injectors in each of driving systems into which the fuel injectors are divided, and current detection circuits that are provided to each of the driving systems and sense driving currents of corresponding fuel injectors. The fuel injection control device controls driving of the fuel injectors by the driving circuits, based on sensed currents sensed by the current detection circuits. The fuel injection control device includes an acquisition unit to acquire a current change parameter that is a parameter correlative to a change quantity of the sensed current per unit time in each of the driving systems, and a current correction unit to execute a current correction in at least one of the driving systems based on the current change parameter in each of the driving systems.
According to the above configuration, in a fuel injection system that divides plural fuel injectors into plural driving systems and includes the current detection circuit provided to each of the driving groups, the current change parameter that is a parameter correlative to the change quantity of the sensed current per unit time in each of the driving systems is obtained. The current correction of at least one of the driving systems is executed based on the current change parameter. In this case, when injection instructions of the fuel injectors are identical in a case where the characteristic variation occurs at one of the current detection circuits, the current change parameters differ from each other in the driving systems. However, the driving states of the fuel injectors can be controlled to approach each other by executing the current correction based on the current change parameter of each of the driving systems. As a result, the optimization of the driving of the fuel injector can be improved, and the fuel injection quantity can be properly controlled.
The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description made with reference to the accompanying drawings. In the drawings:
Hereafter, a first embodiment of the present disclosure will be described referring to drawings. The present embodiment substantiates as a control system that controls a gasoline engine of a vehicle. First, a constitution of an engine control system will be described referring to
An air cleaner 13 is located at an uppermost stream part of an intake pipe 12 of an engine 11 that is a multi-cylinder internal combustion engine of a cylinder injection type. An air flow meter 14 that senses an intake air quantity is located at a position of the intake pipe 12 downstream of the air cleaner 13. A throttle valve 16 and a throttle opening degree sensor 17 are located at a position of the intake pipe 12 downstream of the air flow meter 14. An opening degree of the throttle valve 16 is adjusted by a motor 15. The throttle opening degree sensor 17 senses the opening degree (throttle opening degree) of the throttle valve 16.
A surge tank 18 is located at a position of the intake pipe 12 downstream of the throttle valve 16. An intake pipe pressure sensor 19 that senses an intake pipe pressure is located at the surge tank 18. An intake gas manifold 20 that introduces an air into each of cylinders 21 of the engine 11 is connected with the surge tank 18. A fuel injector 30 that is an electromagnetic type is mounted to each of the cylinders 21 of the engine 11, and the fuel injector 30 directly injects a fuel into the corresponding cylinder. Ignition plugs 22 corresponding to the cylinders 21 are mounted to a cylinder head of the engine 11. A mixed gas in each of the cylinders 21 is ignited by a spark discharge of the ignition plug 22 of each of the cylinders 21.
An exhaust gas sensor 24 (e.g., air-fuel ratio sensor, oxygen sensor) that senses an air-fuel ratio of the mixed gas or a rich/lean state of the mixed gas based on an exhaust gas is located in an exhaust gas pipe 23 of the engine 11. A catalyst 25 that purifies the exhaust gas such as a three-way catalyst is located at a position of the exhaust gas pipe 23 downstream of the exhaust gas sensor 24.
A coolant temperature sensor 26 that senses a coolant temperature and a knock sensor 27 that senses a knocking are mounted to a cylinder block of the engine 11. A crank angle sensor 29 that outputs a pulse signal every time that the crank shaft 28 rotates at a predetermined crank angle is located at a position around an outer periphery of a crank shaft 28. A crank angle or an engine rotation speed is sensed based on the crank angle signal of the crank angle sensor 29.
Outputs of the above various sensors are transmitted to an ECU 40. The ECU 40 is an electronic control unit mainly constituted by a microcomputer. The ECU 40 executes various controls of the engine 11 by using sensed signals of the various sensors. The ECU 40 calculates a fuel injection quantity according to an engine operation state, controls a fuel injection of the fuel injector 30, and controls an ignition time point of the ignition plug 22.
As shown in
The voltage switching circuit 43 is a circuit that switches a driving voltage applied to the fuel injector 30 of each of the cylinders 21 between a high voltage and a low voltage. Specifically, the voltage switching circuit 43 controls one of a low-voltage power unit 45 and a high-voltage power unit 46 to supply a driving current to a coil of the fuel injector 30 by an on-off operation of a switching element that is not shown. The low-voltage power unit 45 is a low-voltage output circuit that outputs the low voltage V1 such as 12V. The high-voltage power unit 46 is a high-voltage output circuit that outputs the high voltage V2 (boost voltage) such as 60V to 65V. The high-voltage power unit 46 includes a voltage boosting circuit that boosts a battery voltage to the boost voltage.
When the fuel injector 30 is driven by the injection pulse to open, the low voltage V1 and the high voltage V2 are alternatively applied to the fuel injector 30 in time series. In this case, since the high voltage V2 is applied at an initial stage of an opening of the fuel injector 30, a valve-opening responsivity of the fuel injector 30 is ensured. Further, since the low voltage V1 is applied after the initial stage, a valve-opening state of the fuel injector 30 is maintained.
According to the present embodiment, as shown in
In the constitution of
The current detection circuit 44 senses an energization current in a valve-opening driving of the fuel injector 30 and successively outputs a sensed result to the driving IC 42. The current detection circuit 44 may have a known constitution. For example, the current detection circuit 44 may include a shunt resistance and a comparator. DAC ports (DAC1, DAC2) of the driving IC 42 output a reference signal equivalent to a reference current. The comparator of the current detection circuit 44 outputs a comparison result of the driving current of each of the fuel injector 30 and the reference current.
A temperature sensor 47 is located at each of the current detection circuits 44. The temperature sensor 47 senses a temperature of each of the current detection circuits 44. It can be assumed that an affection level of a heat receiving from other heat generation sources or a level of a heat dissipation in each of the current detection circuits 44 differs according to an arrangement of each of the current detection circuits 44 in a housing of the ECU 40. When a temperature difference occurs between the current detection circuits 44, the temperature sensors 47 sense the temperature difference.
According to the present embodiment, in a driving mode of the fuel injector 30, a lifting of a valve body of the fuel injector 30 is stopped in a partially lifting state before the valve body reaches a fully lifting position, and a partially lifting injection that injects the fuel with a required quantity at the partially lifting state is executed. Referring to
As shown in
Next, referring to
As shown in
At the time point t1, an applied voltage of the fuel injector 30 is switched from the low voltage V1 to the high voltage V2. Thus, the driving current is more sharply increased in a voltage boosting time interval from the time point t1 to a time point t2 than that in the time interval from the time point t0 to the time point t1. Then, at the time point t2, when the driving current reaches the target peak value Ip that is previously determined, the application of the high voltage V2 is stopped. In this case, a needle lifting starts at a timing that the driving current reaches the target peak value Ip or at a timing right before the driving current reaches the target peak value Ip, and the fuel injection starts in response to the needle lifting. A determination whether the driving current has reached the target peak value Ip is executed based on the sensed current sensed by the current detection circuit 44. In other words, it is determined whether the sensed current is greater than or equal to Ip at the driving IC 42 in the voltage boosting time interval (t1 to t2). At a time point that the sensed current is greater than or equal to Ip, the voltage switching circuit 43 executes a switching of the applied voltage (V2 application stop).
After the time point t2, the driving current decreases in response to an application stop of the high voltage V2, and the low voltage V1 is intermittently applied to the fuel injector 30 based on a current threshold that is previously determined and the sensed current sensed by the current detection circuit 44. As shown in
Then, when the injection pulse is turned off at the time point t4, the voltage application of the fuel injector 30 is stopped, and the driving current becomes zero. The needle lifting is stopped in response to a stop of a coil energization of the fuel injector 30, and the fuel injection is stopped according to the stop of the coil energization.
In the valve-opening driving of the fuel injector 30, the switching of the applied voltage is executed based on the sensed result of the driving current, that is, the switching of the applied voltage is executed based on a driving profile, as the above description. However, it is possible that an error is included in the sensed current at the current detection circuit 44 due to various factors. For example, it is possible that a detection error occurs due to an individual difference of a shunt resistance or an aging deterioration of the shut resistance. In this case, when an error is included in the sensed current relative to an actual driving current (actual current), a timing that the driving current reaches the target peak value Ip cannot be properly obtained, and it is possible that an excess or a deficiency of the fuel injection quantity occurs as a result.
According to the present embodiment, since plural current detection circuits 44 are provided to each of the driving groups (driving systems), it is possible that a characteristic variation of each of the current detection circuits 44 occurs to be different from each other. In this case, a variation of the fuel injection quantity of each of the cylinders due to the characteristic variation of each of the current detection circuits 44, and it is possible that a torque variation occurs as a result.
Referring to
As shown in
In each of the driving groups, the switching (V1 application stop) of the applied voltage is executed at a timing that the sensed current of the fuel injector 30 reaches the target peak value Ip. In this case, since the timings of voltage switchings at the driving groups actually differ from each other, it is possible that a difference occurs in fuel injection quantities as a result. That is, in the second driving group, since a voltage boosting energy in the voltage-boosting driving time interval is greater than that in the first driving group and a needle lifting operation becomes greater than that in the first driving group, it is possible that the fuel injection quantity becomes excessive.
As shown in
In each of the driving groups, the switching (V1 application stop) of the applied voltage is executed at a timing that the sensed current of the fuel injector 30 reaches the target peak value Ip. In this case, since the timings of the voltage switchings at the driving groups actually differ from each other, it is possible that the difference occurs in the fuel injection quantities as a result, the same as those in
When the detection shift occurs as the above description, a shift of the driving current in a valve-opening maintenance time interval occurs due to the detection shift. Therefore, it is possible that the shift affects a driving state (e.g., needle lifting quantity) of the fuel injector 30 in the valve-opening maintenance time interval.
According to the present embodiment, the microcomputer 41 measures the reaching time interval from a reference timing that is predetermined to a timing that the sensed current reaches a predetermined current value in each of the fuel injections of the fuel injectors 30, based on the detection currents obtained by the current detection circuits 44 of the first driving group and the second driving group. The microcomputer 41 executes a current correction of each of the driving groups those are the first driving group and the second driving group based on a difference between the reaching time intervals of the current detection circuits 44. According to the present embodiment, the reaching time interval of each of the current detection circuits 44 is equivalent to a current change parameter. The microcomputer 41 is equivalent to an acquisition unit and a current correction unit.
Specifically, the microcomputer 41 sets a timing (time point t1 shown in
The microcomputer 41 can set a timing in a time interval (t1 to t2 shown in
As shown in
Then, at step S12, the microcomputer 41 acquires the peak current reaching time interval Tp1 of the first driving group and the peak current reaching time interval Tp2 of the second driving group. The peak current reaching time interval Tp1 and the peak current reaching time interval Tp2 are acquired in driving of the fuel injectors 30 of the driving groups including the first driving group and the second driving group. At step S12, the microcomputer 41 may execute a temperature correction based on a temperature of each of the current detection circuits 44 for the peak current reaching time intervals Tp1 and Tp2 those are acquired. In other words, the microcomputer 41 acquires the temperature difference of the current detection circuits 44 based on sensed temperatures obtained by temperature sensors 47 of the current detection circuits 44, and corrects the peak current reaching time intervals Tp1 and Tp2 based on the temperature difference. In this case, the microcomputer 41 sets one of sensed temperatures of the driving groups those are the first driving group and the second driving group as a reference temperature, and corrects to increase or decrease the peak current reaching time interval based on the temperature difference.
Then, at step S13, the microcomputer 41 calculates the peak current reaching time interval of each of the driving groups those are the first driving group and the second driving group, by using an average value of the peak current reaching time intervals in a predetermined sampling number n. For example, n is equal to 20.
Then, at step S14, the microcomputer 41 calculates a target reaching time interval Tptg. In this case, the microcomputer 41 uses the larger one of the reaching time intervals Tp1 and Tp2 of the driving groups those are the first driving group and the second driving group as the target reaching time interval Tptg. Alternatively, the microcomputer 41 can also use the smaller one of the reaching time intervals Tp1 and Tp2 of the driving groups those are the first driving group and the second driving group as the target reaching time interval Tptg.
When the reaching time intervals Tp1 and Tp2 are large, change quantities of the sensed currents per unit time are small. When the larger one of the reaching time intervals Tp1 and Tp2 is set as the target reaching time interval Tptg, the smaller one of change quantities of the sensed currents per unit time is set as a reference of the reaching time interval (current control). In this case, the reaching time interval of a system that the change quantity of the sensed current per unit time is large (a system that the reaching time interval is small) is controlled to be fit to a system that the change quantity of the sensed current per unit time is small (a system that the reaching time interval is large).
When the reaching time intervals Tp1 and Tp2 are small, the change quantities of the sensed currents pre unit time are large. When the smaller one of the reaching time intervals Tp1 and Tp2 is set as the target reaching time interval Tptg, the larger one of the change quantities of the sensed currents per unit time is set as the reference of the reaching time interval (current control). In this case, the reaching time interval of a system that the change quantity of the sensed current per unit time is small (a system that the reaching time interval is large) is controlled to be fit to a system that the change quantity of the sensed current per unit time is large (a system that the reaching time interval is small).
Then, at step S15, the microcomputer 41 calculates a difference ΔTp between the target reaching time interval Tptg and a correction subject that is one of the reaching time intervals Tp1 and Tp2 of the driving groups including the first driving group and the second driving group. For example, when the microcomputer 41 selects the larger one of the reaching time intervals Tp1 and Tp2 as the target reaching time interval Tptg at step S14, the microcomputer 41 calculates the difference ΔTp between the target reaching time interval Tptg and the correction subject that is the smaller one of the reaching time intervals.
Then, at step S16, the microcomputer 41 determines whether the difference ΔTp is greater than a threshold TH that is predetermined. When the microcomputer 41 determines that ΔTp is greater than TH, the microcomputer 41 proceeds to step S17. At step S17, the microcomputer 41 executes a correction of a target current. In this case, the microcomputer 41 executes a correction of the target peak value Ip in the voltage-boosting driving time interval for the correction subject that is one of the driving groups including the first driving group and the second driving group. Specifically, the microcomputer 41 calculates a current correction value ΔIp based on the difference ΔTp by using a relationship shown in
At step S17, the microcomputer 41 executes a correction of the target holding value Ih in the valve-opening maintenance time interval in addition of the correction of the target peak value Ip in the voltage-boosting driving time interval. In this case, the target holding value Ih is lower than the target peak value Ip. The microcomputer 41 corrects the target holding value Ih of the respective driving group relative to that in the correction of the target peak value Ip, based on ratios (shifts of Ip1 and Ip2) of the target peak values Ip1 and Ip2 of the driving groups including the first driving group and the second driving group. For example, when the microcomputer 41 corrects the target holding value Ih2 of the second driving group in a case where the target holding value Ih1 of the first driving group is used as the reference, the microcomputer 41 corrects the target holding value Ih2 by an equation that Ih2=Ih1×(Ip2/Ip1). When the target holding value Ih in the valve-opening maintenance time interval is set at plural levels, the microcomputer 41 corrects the target holding value Ih at each of the levels.
The microcomputer 41 returns to step S12 after executing the correction of the target current. The microcomputer 41 repeatedly executes steps S12 to S17 until the microcomputer 41 determines that the difference ΔTp is less than or equal to the threshold TH at step S16 (S16 is NO).
When the microcomputer 41 determines that the difference ΔTp is less than or equal to the threshold TH at step S16, the microcomputer 41 proceeds to step S18. At step S18, when the microcomputer 41 has executed the current correction in the present correction operation, the microcomputer 41 stores a correction result of the current correction. In other words, the microcomputer 41 stores the target peak value Ip and the target holding value Ih those are corrected in a backup memory (e.g., EEPROM). The target peak value Ip and the target holding value Ih those are corrected are stored as learning values and are loaded in a driving of the fuel injector 30.
As shown in
At the time point t11, the difference ΔTp is calculated by subtracting the reaching time interval Tp2 of the second driving group from the reaching time interval Tp1 (equivalent to Tptg) of the first driving group, and the current correction value ΔIp is calculated based on the difference ΔTp. The target peak value Ip2 of the second driving group is corrected by the current correction value ΔIp.
In a time interval from the time point t11 to a time point t12, the reaching time intervals Tp1 and Tp2 of the driving groups including the first driving group and the second driving group are obtained again, by using the target peak value Ip1 of the first driving group that is not corrected and the target peak value Ip2 of the second driving group that is corrected. At the time point t12, the current correction valve ΔIp are calculated again, based on the difference ΔTp of the reaching time intervals, and the target peak value Ip2 of the second driving group is corrected by the current correction value ΔIp. The correction of the target peak value Ip2 is repeatedly executed in a case where a condition that the difference ΔTp is greater than the threshold TH is met. At the time points t11 and t12, the current correction value ΔIp gradually decreases in accordance with a gradual decrease in difference ΔTp.
Then, at a time point t13, when the difference ΔTp is determined to be less than or equal to the threshold TH, the correction of the target peak value Ip2 is stopped. At the time point t13, actual peak currents of the driving groups including the first driving group and the second driving group are substantially equal to each other, and then the variations of the fuel injection quantities between the cylinders are canceled.
As shown in
At the time point t21, the difference ΔTp is calculated by subtracting the reaching time interval Tp2 of the second driving group from the reaching time interval Tp1 (equivalent to Tptg) of the first driving group, and the current correction value ΔIp is calculated based on the difference ΔTp. The target peak value Ip2 of the second driving group is corrected by the current correction value ΔIp.
Then, in a time interval from the time point t21 to a time point t22, the reaching time intervals Tp1 and Tp2 of the driving groups including the first driving group and the second driving group are obtained again, by using the target peak value Ip1 of the first driving group that is not corrected and the target peak value Ip2 of the second driving group that is corrected. At the time point t22, the current correction value ΔIp is calculated again based on the difference ΔTp of the reaching time intervals, and the target peak value Ip2 of the second driving group is corrected by the current correction value ΔIp. The correction of the target peak value Ip2 is repeatedly executed in a case where a condition that the difference ΔTp is greater than the threshold TH is met. At the time points t21 and t22, the current correction value ΔIp gradually decreases in accordance with a gradual decrease in difference ΔTp.
Then, at a time point t23, the difference ΔTp is determined to be less than or equal to the threshold TH, and the correction of the target peak value Ip2 is stopped. At the time point t23, the actual peak currents of the driving groups including the first driving group and the second driving group are substantially equal to each other, and the variations of the fuel injection quantities between the cylinders are canceled.
As shown in
In this case, according to the above correction operation, the target peak value Ip2 of the second driving group is corrected to increase based on the difference ΔTp of the peak current reaching time intervals as shown in
As shown in
According to the present embodiment as the above description, following effects are obtained.
In a fuel injection system that divides plural fuel injectors 30 into plural driving groups (plural driving systems) and includes the current detection circuit 44 provided to each of the driving groups, the peak current reaching time intervals Tp are measured based on the sensed current of each of the current detection circuits 44, and the current correction of one of the driving groups is executed based on the difference between the reaching time intervals Tp of the current detection circuits 44. In this case, when injection instructions of the fuel injectors 30 are identical in a case where the characteristic variation occurs at one of the current detection circuits 44, the peak current reaching time intervals Tp differ from each other in the driving groups including the first driving group and the second driving group. However, the driving states of the fuel injectors 30 can be controlled to approach each other by executing the current correction based on the difference between the reaching time intervals Tp. As a result, an optimization of the driving of the fuel injectors 30 can be improved, and the fuel injection quantities can be properly controlled.
The correction of the target current is executed to uniform the peak current reaching time intervals Tp1 and Tp2 of the driving groups including the first driving group and the second driving group. In this case, since the reaching time intervals Tp1 and Tp2 of the driving groups including the first driving group and the second driving group are uniformed, the driving profiles of the fuel injectors 30 can be matched with each other. Thus, the variations of the fuel injection quantities of the fuel injectors 30 can be suppressed.
When it is determined that the sensed current has reached the target current value in a case where the characteristic variation occurs at one of the current detection circuit 44, it is assumed that the actual driving current differs from the target current value. Since the target current value in at least one of the driving groups including the first driving group and the second driving group is corrected, the target current value of each of the driving groups including the first driving group and the second driving group is determined, and a comparison between the target current value and the sensed current is executed. In this case, the timings that the actual driving currents reach the target current values in the driving groups including the first driving group and the second driving group can be matched with each other, and the variations of the fuel injection quantities are suppressed.
Specifically, when it is determined that the sensed current has reached the target peak value Ip in a case where the characteristic variation occurs at one of the current detection circuits 44, it is assumed that the actual peak current differs from the target peak value Ip. Since the target peak value Ip in at least one of the driving groups including the first driving group and the second driving group is corrected, the target peak value Ip of each of the driving groups including the first driving group and the second driving group is determined, and a comparison between the target peak value Ip and the sensed current is executed. In this case, the timings that the actual driving currents reach the target peak values Ip in the driving groups including the first driving group and the second driving group can be matched with each other, and the variations of the fuel injection quantities are suppressed. When the target peak value Ip is set in each of the driving groups including the first driving group and the second driving group, the valve-opening responsivities of the fuel injectors 30 can be matched with each other and then the variations of the fuel injection quantities can be suppressed.
Since the correction of the target holding value Ih is executed in addition of the correction of the target peak value Ip, the valve-opening responsivities of the fuel injectors 30 and valve-body lifting quantities of the fuel injectors 30 can be matched with each other and the variations of the fuel injection quantities can be suppressed.
When the characteristic variation occurs at one of the current detection circuits 44, a variation occurs at one of the voltage-boosting driving time interval in the fuel injector 30 and the valve-opening maintenance time interval in the fuel injector 30 between the driving groups with an increasing-decreasing tendency the same as that of the characteristic variation. When the target peak value Ip1 or Ip2 of the driving groups including the first driving group and the second driving group is corrected, the target holding value Ih of the corresponding driving group where the correction of the target peak value is executed is corrected. Thus, the correction of the target peak value can be properly corrected, and the driving states of the fuel injectors 30 can be properly matched with each other.
When a difference occurs between the reaching time intervals Tp1 and Tp2 of the driving groups including the first driving group and the second driving group, the current control for the smaller one of the reaching time intervals Tp1 and Tp2 (the larger one of the change quantities of the sensed currents per unit time) is executed to match the smaller one with the larger one of the reaching time intervals Tp1 and Tp2 (the smaller one of the change quantities of the sensed currents per unit time) (refer to
When the current control for the larger one of the reaching time intervals Tp1 and Tp2 (the smaller one of the change quantities of the sensed currents per unit time) is executed to match the larger one with the smaller one of the reaching time intervals Tp1 and Tp2 (the larger one of the change quantities of the sensed currents per unit time) (refer to
When the characteristic variation occurs at one of the current detection circuits 44, a difference of the characteristic variation increases accordance with an increase in time length of the energization state. Since a time interval from a reference timing to a timing that the sensed current reaches the target peak value Ip is measured as the reaching time interval, the difference of the characteristic variation of the current detection circuit 44 can be more accurately obtained than a case where a threshold current is established to be lower than the target peak value Ip.
When the characteristic variation occurs at one of the current detection circuits 44, the driving currents of the driving groups including the first driving group and the second driving group at a timing that the pre-charge is completed differ from each other. It is assumed that pre-charge complete timings of the driving groups including the first driving group and the second driving group differ from each other. Since a timing (more widely, a timing in a time interval where the application of the high voltage V2 is executed) that the application of the high voltage V2 starts after the pre-charge is completed is set as the reference timing to measure the peak current reaching time intervals Tp1 and Tp2, the correction of the target current can be properly executed without being affected by variations of the pre-charge complete timings in driving groups including the first driving group and the second driving group.
When the temperature difference occurs at the current detection circuits 44, it is possible that an accuracy of a measurement of each of the peak current reaching time intervals Tp1 and Tp2 is reduced due to an affection of the temperature difference. Since the temperature difference of the current detection circuits 44 in the driving groups including the first driving group and the second driving group is acquired and the peak current reaching time intervals Tp1 and Tp2 are corrected based on the temperature difference, a negative influence due to the temperature difference of the current detection circuits 44 can be suppressed.
When a condition that the fuel injection quantity of one driving of the fuel injector 30 is greater than or equal to a predetermined quantity and is not in a slight injection state, the peak current reaching time intervals Tp1 and Tp2 of the driving groups including the first driving group and the second driving group. When the peak current reaching time intervals Tp1 and Tp2 of the driving groups including the first driving group and the second driving group are measured, the driving current of each of the fuel injectors 30 certainly reaches the target peak value Ip. Thus, the peak current reaching time intervals Tp1 and Tp2 can be accurately obtained and an accuracy of the current correction can be improved.
Hereafter, a second embodiment of the present disclosure will be described mainly about different points from the first embodiment. According to the present embodiment, as the current change parameter, a reaching current that is the sensed current when a predetermined time interval has elapsed from a reference timing that is predetermined in each of the fuel injections of the fuel injectors 30 in the driving groups including the first driving group and the second driving group is obtained. A current correction is executed based on a difference between the reaching currents in the driving groups including the first driving group and the second driving group.
As shown in
As shown in
Then, at step S23, the microcomputer 41 calculates the reaching currents Ia1 and Ia2 of the driving groups including the first driving group and the second driving group, by using average values of the reaching currents in a predetermined sampling number n. For example, n is equal to 20. Then, at step S24, the microcomputer 41 calculates an absolute value ΔIa of a difference between the reaching currents Ia1 and Ia2 of the driving groups including the first driving group and the second driving group.
Then, at step S25, the microcomputer 41 selects the driving group that is the correction subject based on magnitudes of the reaching currents Ia1 and Ia2. In this case, the microcomputer 41 selects the larger one of the reaching currents Ia1 and Ia2 of the driving groups including the first driving group and the second driving group, as the correction subject. Alternatively, the microcomputer 41 may select the smaller one of the reaching currents Ia1 and Ia2 of the driving groups including the first driving group and the second driving group, as the correction subject.
Then, at step S26, the microcomputer 41 determines whether ΔIa is greater than a threshold TH2 that is predetermined. When the microcomputer 41 determines that ΔIa is greater than TH2, the microcomputer 41 proceeds to step S27. At step S27, the microcomputer 41 executes the correction of the target current. In this case, the microcomputer 41 executes the correction of the target peak value Ip in the voltage-boosting driving time interval for the driving group of the driving groups including the first driving group and the second driving group that is the correction subject. Specifically, the microcomputer 41 calculates the current correction value ΔIp based on ΔIa by using a relationship shown in
At step S27, the microcomputer 41 executes the correction of the target holding value Ih in the valve-opening maintenance time interval in addition of the correction of the target peak value Ip in the voltage-boosting driving time interval. However, specifications of step S27 are equivalent to those of step S17 shown in
When the microcomputer 41 determines that ΔIa is less than or equal to TH2 at step S26, the microcomputer 41 proceeds to step S28. At step S28, when the microcomputer 41 has executed the current correction in the present correction operation, the microcomputer 41 stores the correction result of the current correction (the same as step S18 shown in
According to the present embodiment, the same as the first embodiment, the optimization of the driving of the fuel injectors 30 can be improved, and the fuel injection quantities can be properly controlled.
Hereafter, a third embodiment of the present disclosure will be described mainly about different points from the first embodiment. According to the present embodiment, as the current change parameter, a current integration value that is obtained by integrating the sensed current from the reference timing that is predetermined in each of the fuel injections of the fuel injectors 30 in the driving groups including the first driving group and the second driving group to a timing that a predetermined time interval has elapsed from the reference timing is obtained. A current correction is executed based on a difference between the current integration values of the driving groups including the first driving group and the second driving group.
As shown in
As shown in
The, at step S33, the microcomputer 41 calculates the current integration values ΣI1 and ΣI2 of the driving groups including the first driving group and the second driving group, by using average values of the current integration values in a predetermined sampling number n. For example, n is equal to 20. Then, at step S34, the microcomputer 41 calculates an absolute value ΔΣI of the difference between the current integration values ΣI1 and ΣI2 of the driving groups including the first driving group and the second driving group.
Then, at step S35, the microcomputer 41 selects the driving group that is the correction subject based on magnitudes of the current integration values ΣI1 and ΣI2. In this case, the microcomputer 41 selects the larger one of the current integration values ΣI1 and ΣI2 of the driving groups including the first driving group and the second driving group, as the correction subject. Alternatively, the microcomputer 41 may select the smaller one of the current integration values ΣI1 and ΣI2 of the driving groups including the first driving group and the second driving group, as the correction subject.
Then, at step S36, the microcomputer 41 determines whether ΔΣI is greater than a threshold TH3 that is predetermined. When the microcomputer 41 determines that ΣΣI is greater than TH3, the microcomputer 41 proceeds to step S37. At step S37, the microcomputer 41 executes the correction of the target current. In this case, the microcomputer 41 executes the correction of the target peak value Ip in the voltage-boosting driving time interval for the driving group of the driving groups including the first driving group and the second driving group that is the correction subject. Specifically, the microcomputer 41 calculates the current correction value ΔIp based on ΔΣI by using a relationship shown in
At step S37, the microcomputer 41 executes the correction of the target holding value Ih in the valve-opening maintenance time interval in addition of the correction of the target peak value Ip in the voltage-boosting driving time interval. However, specifications of step S37 are equivalent to those of step S17 shown in
When the microcomputer 41 determines that ΔΣI is less than or equal to TH3 at step S36, the microcomputer 41 proceeds to step S38. At step S38, when the microcomputer 41 has executed the current correction in the present correction operation, the microcomputer 41 stores the correction result of the current correction (the same as step S18 shown in
According to the present embodiment, the same as the first embodiment, the optimization of the driving of the fuel injectors 30 can be improved, and the fuel injection quantities can be properly controlled.
The above-mentioned embodiment may be modified as follows.
According to the first embodiment, the peak current reaching time interval Tp is measured when a timing that the application of the high voltage V2 starts after the pre-charge is completed as the reference timing. However, the reference timing may be changed. Specifically, the peak current reaching time interval Tp may be measured when a timing that the injection pulse is turned on is set as the reference timing. In this case, the timing that the injection pulse is turned on is a timing that an energization of the fuel injector 30 starts.
Further, the microcomputer 41 may measure a reaching time interval from the reference timing to a timing that the sensed current reaches a predetermined current value lower than the target peak value Ip instead of measuring the peak current reaching time interval Tp from the reference timing to a timing that the sensed current reaches the target peak value Ip.
According to the first embodiment, the longer one (or the shorter one) of the peak current reaching time intervals Tp1 and Tp2 of the driving groups including the first driving group and the second driving group is set as the target reaching time interval, and the correction of the target peak value Ip is executed based on the difference ΔTp between the reaching time intervals. However, the target reaching time interval may be changed. Specifically, an average of the peak current reaching time intervals Tp1 and Tp2 of the driving groups including the first driving group and the second driving group may be set as the target reaching time interval, and the correction of the target peak value Ip may be executed based on a difference ΔTp between the reaching time intervals. Alternatively, a target driving time interval that is the target reaching time interval may be a specified value that is previously set. In the above cases, the correction of the target peak value Ip is executed to uniform the reaching time intervals Tp1 and Tp2 of the driving groups including the first driving group and the second driving group.
When the correction of the target value Ip is executed based on the difference ΔTp of the reaching time intervals in a case where the average of the peak current reaching time intervals Tp1 and Tp2 of the driving groups including the first driving group and the second driving group is set as the target reaching time interval, both the target peak values Ip1 and Ip2 of the driving groups including the first driving group and the second driving group are corrected. In this case, the target peak value Ip of one of the driving groups is corrected to increase, and the target peak value Ip of the other one of the driving groups is corrected to decrease.
According to the above embodiments, the current correction is executed based on a difference of the current change parameters (reaching time intervals, reaching currents, current integration values) of the driving systems. However, the current correction may be changed. Specifically, the current correction may be executed based on a result of a comparison of the current change parameters (reaching time intervals, reaching currents, current integration values) of the driving systems. More specifically, the current correction may be executed based on a ratio of the current change parameters of the driving systems.
According to the above embodiments, when the target current value (e.g., target peak value) is updated, a limitation of the update may be set. Specifically, an upper limit value of the target current value is set. Alternatively, in a configuration where the target current value is increased or decreased according to the difference ΔTp of the reaching time intervals, a threshold that is used in a threshold determination of the difference ΔTp of the reaching time intervals may have a hysteresis. In this case, a first threshold and a second threshold are set (first threshold>second threshold). When the target current value is increased, the target current value is gradually increased until the difference ΔTp reaches the first threshold. When the target current value is decreased, the target current value is gradually decreased until the difference ΔTp reaches the second threshold.
Another constitution of the ECU 40 will be described.
In the constitution shown in
Alternatively, three cylinders may be established as a driving group when the cylinders do not have an overlapped time interval of the fuel injections.
When plural fuel injectors 30 are established as plural driving groups, a total number of cylinders and a total number of the fuel injectors 30 in each of the driving system are arbitrary. For example, in a two-cylinder engine, each of cylinders (each of fuel injectors) may be established as an individual driving group. It is also applied to an engine including three or more cylinders.
The high-voltage power unit 46 that outputs the high voltage V2 may be constituted by a high-voltage battery without including the voltage boosting circuit that boosts the battery voltage.
While the present disclosure has been described with reference to the embodiments thereof, it is to be understood that the disclosure is not limited to the embodiments and constructions. The present disclosure is intended to cover various modification and equivalent arrangements. In addition, while the various combinations and configurations, which are preferred, other combinations and configurations, including more, less or only a single element, are also within the spirit and scope of the present disclosure.
| Number | Date | Country | Kind |
|---|---|---|---|
| JP2015-233462 | Nov 2015 | JP | national |
| JP2016-158557 | Aug 2016 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2016/082637 | 11/2/2016 | WO | 00 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2017/094430 | 6/8/2017 | WO | A |
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| Number | Date | Country | |
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| 20200141347 A1 | May 2020 | US |
